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TRANSLATIONS OF FOREIGN BIOLOGICAL MEMOIRS II
London HENRY FROWDE Oxford University Press Warehouse Amen Corner, E.C.
BY
Dr. ALEXANDER ECKER
PROFESSOR OF HUMAN AND COMPARATIVE ANATOMY
IN THE UNIVERSITY OF FREIBURG
Translated, with numerous Annotations and Additions
BY
GEORGE HASLAM, M.D.
SCIENTIFIC ASSISTANT IN THE MEDICAL DEPARTMENT IN THE UNIVERSITY
OF ZÜRICH; FORMERLY ASSISTANT LECTURER IN PHYSIOLOGY IN THE
OWENS COLLEGE, VICTORIA UNIVERSITY, MANCHESTER
ILLUSTRATED WITH MANY WOOD ENGRAVINGS AND TWO COLOURED PLATES EXECUTED BY HOFMANN, WÜRTZBURG, BAVARIA
Oxford
AT THE CLARENDON PRESS
1889
[All rights reserved]
TRANSLATOR’S PREFACE.
I undertook the publication of a translation of Ecker’s
‘Anatomie des Frosches’ at the suggestion of Professor A.
Gamgee while I was working under his superintendence in the
physiological laboratory of the Owens College. The work was
subsequently accepted by the Delegates of the Clarendon Press, as
one of the series of ‘Foreign Biological Memoirs,’ published by them.
Early in the progress of the work it became evident that a mere
translation would be unsatisfactory, and that it would be desirable
to recast and modify several portions of the book. It was deemed
advisable to give greater completeness to the work by descriptions
of the minute structure of the several organs. For these purposes
the appearance of the work has been unavoidably delayed.
I have done my best to bring the book up to date by including
the results of recent researches, to which I have added many facts
derived from my own personal investigations. All such additions
are enclosed within square brackets [ ]. More than a hundred
new figures, of which one-third are original, have been added; and
copious, though it is feared still incomplete, lists of references to
frog-literature have been drawn up. By these additions the size
of the book has been considerably increased.
In the several sections into which the book is divided the following
points may be more particularly noticed:—
Sect. I. The Bones and Joints. The nomenclature of Parker
and Bettany has been adopted throughout.
Sect. II. The Muscles. This section remains in its original form.
Sect. III. The Nervous System. The chapters on the central
nervous system and the sympathetic system have been rewritten.
The description of the arteries of the brain is
entirely new, while the chapters on cranial and spinal nerves
have received many smaller additions, and have been rearranged
to facilitate reference.
Sect. IV. The Vascular System. The chapter on the heart is
practically new, and many additions and alterations have
been made in the descriptions of the blood-vessels and
lymphatics.
Sect. V. The Alimentary Canal, with its appendages, the Spleen
and the Peritoneum. In this section much new material has
been added: the descriptions of the blood-vessels of the liver,
the ducts of the liver and pancreas, etc., being the results of
original investigation.
Sect. VI. The Respiratory Organs, the Thymus and Thyroid
Glands. These organs have been carefully studied and
numerous new details are noted. The lymphatic glands of
the hyoid region have, after some hesitation, been designated
tonsils.
Sect. VII. The Urino-Genital Organs. A very large number
of preparations have been made to investigate the vessels and
uriniferous tubes of the kidneys; and the descriptions of
the remaining organs of this section have received large
additions from recent publications.
Sect. VIII. The Skin and the Sense-Organs. This section has,
with the exception of very small portions, been re-written and
very much enlarged.
Before concluding this preface, I must thank my friend Professor
A. Milnes Marshall, of the Owens College, for all the help and
kindness he has extended to me before and during the time this
work has been in hand; to him I am indebted not alone for the
loan of books, pamphlets, etc., and for much useful information,
but also for the care and patience with which he has read and
corrected the whole of the proof-sheets.
To Professor G. Lunge, of Zürich, I am indebted for the use of
the library of the Gesellschaft der Naturforscher of Zürich; and
to my friend Mr. C. Herbert Hurst, of the Owens College, for the
drawings for figures 132, 133, 134, and 136; also to Dr. Max
Köppen, of Strasburg, for the proof-sheets of his valuable paper,
‘Zur Anatomie des Froschgehirns’: to these gentlemen I beg to
express herewith my heartiest thanks. Lastly, I must express my
sense of indebtedness to the Delegates of the Clarendon Press, who
have kindly allowed me to alter the original plan of the book, and
to make extensive additions far beyond the limits originally
intended.
A second edition of the original German work is in course of
publication. The first part, on the bones and muscles, has already
appeared.
GEO. HASLAM.
Zürich, 1888.
PREFACE TO THE FIRST PART.
The idea of this manual on the anatomy of the frog, of which I
now offer the first part to physiologists and to those who would
become such, occurred to me during the preparation of the plates
for my ‘Icones Physiologicae.’ I was then convinced of the
necessity of such a book. I regret that many direct and indirect
causes have hindered its earlier completion; fortunately, however,
its appearance is still opportune, as the need for the book has not
diminished. I am conscious that the book requires a recommendation
to the indulgent judgment of my fellow-workers, since almost
every one has studied the frog for one purpose or another, and
each will closely criticize in that department with which he is most
familiar. Although I shall not be able to satisfy all, still I hope
that my work may serve as a useful basis for further investigations,
and I would apply to it the words with which Sömmering prefaced
his anatomy: ‘Ich wünschte ein Handbuch zu liefern und seine
Einrichtung so zu treffen, dass man künftig an ihm als einer Basis
nach Erforderniss leicht ändern, wegnehmen und zusetzen könnte1.’
Lest more be anticipated from the book than it is intended to
supply, I would observe that I have throughout had in mind only
a descriptive anatomy of the indigenous (German) frog; a comparative
anatomy of Batrachians was as foreign to my intention as
were developmental or histological questions: hence morphological
details must not be expected. Any hope of formulating a systematic
nomenclature of the muscles has been abandoned; as neither one
based upon their mode of action, of which we know so little, nor
one based upon their origins and insertions, as demonstrated by
the unpronounceable names of Chaussier and Dugès, is really
practicable. I have therefore preferred to avail myself, as far as
possible, of the received names, which have been chosen partly
according to mode of action, partly according to origin and
insertion, and partly according to position and form; while in the
choice of new names I have given preference to the simplest.
The figures are, with few exceptions, original, and drawn by
myself. Their careful execution in woodcut has added a very
necessary neatness to that correctness, which alone I claim as mine.
ALEXANDER ECKER.
Freiburg, February, 1864.
PREFACE TO THE SECOND PART.
Sixteen years have elapsed since the first portion of this
anatomy of the frog appeared; this second portion, therefore,
requires a somewhat apologetic introduction.
The nervous and vascular systems have, in substance, been
known for some years; still, certain points required a thorough
revision: this seemed especially necessary with regard to the cranial
nerves. In consequence of my anthropological investigations, and
particularly through undertaking the editorship of the ‘Archiv für
Anthropologie,’ my attention was drawn into another channel, and
I found it impossible to work out this chapter: consequently the
whole was deferred, and would have been still longer delayed had I
not received assistance.
At my request Professor Wiedersheim undertook to investigate
afresh the cranial nerves, the brain, the spinal cord, and the sympathetic
system; and the descriptions of these parts are the result of
his work alone. I regard it as most advantageous to this second
part that so experienced an investigator in the anatomy of Amphibia
should have given me his help.
The remaining portions appear almost unaltered as written
several years ago; and the majority of the illustrations date from
the same period. I had neither the time nor the zeal necessary to
re-examine the whole; besides, it is doubtful whether eyes some
twenty years older would improve matters.
This somewhat neglected book is therefore commended to the indulgence
of my fellow-workers, with the hope that it may at least
form a basis upon which further work may easily be done; to proffer
more than this, as I stated, with a quotation from Sömmering,
in the preface to the first part, I have never even hoped.
The final part of the work, on the viscera and sense-organs, has
been undertaken by Professor Wiedersheim, and will appear in the
Spring of 1882.
There is no occasion, now-a-days, to offer a lengthened apology for
devoting a treatise solely to the anatomy of the frog, which enjoys
the doubtful honour of being, κατ’ ἐξοχήν, the physiological domestic
animal. It is kept in every physiological laboratory, and is daily
sacrificed in numbers upon the altar of science. The physiologist has
recourse to it, not only to obtain answers to new questions, but for
the sake of demonstrating easily and quickly the most important known
facts of the science. These unlucky batrachians are to be had in any
number, and are specially adapted for experimental investigation: they
have consequently fallen under a harsher tyrant than the stork in the
fable, and their prophetic outcry in the frog-chorus of Aristophanes,
δεινὰ πεισόμεσθα, has been literally fulfilled.
As the history of the most important physiological discoveries
is closely related with the employment of the frog in physiological
research, it will not be without interest to review briefly the history
of its use in scientific, especially in physiological, investigations,
and to record the services which it has already rendered to science.
Swammerdam (1637–1685), as du Bois-Reymond justly remarks, was the
first to make known the frog as an important means of research; he
says concerning it:—‘An den Thieren, die das heisseste Blut haben,
ist die Bewegung der Muskeln nicht so merklich oder hält vielmehr
nicht so lange an, als an Thieren die mit kälterem Blute begabt
sind. Dergleichen sind die Fische und viele andere Wasserthiere, wie
auch solche, die so wohl im Wasser als auf dem trocknen Lande leben
können. Deswegen habe ich insonderheit mit dem Frosch meine Versuche
angestellt. Denn an diesem Thiere sind die Sehnen sehr sichtbar und
lassen sich leicht entdecken
und entblössen2.’ Swammerdam made the earliest experiments on the
contraction of muscle by means of chemical and mechanical stimulation
of its nerves; thus laying the basis of our present nerve and muscle
physiology, which has been built up within rather less than two hundred
years; though during the first half of this period but little advance
was made.
From the famous September evening of the year 1786, on which
Galvani first observed the twitchings of a frog’s leg suspended by a
metallic hook to an iron balcony, the frog has, down to the present
time, afforded almost the only material for the investigation of
the excitability of nerve and its associated electromotive changes,
and also no inconsiderable part of the remaining nerve and muscle
physiology. It was not until Müller devised the method of operating
on the frog that Bell’s law became capable of easy proof; and much
of our knowledge of the functions of the spinal cord is derived from
experiment upon it. Again, the muscles of frogs served, from the time
of Swammerdam to that of Eduard Weber and his followers, for the
investigation of the phenomena and the conditions of contraction;
and in almost all other branches of physiology there are important
doctrines which were first definitely established by experiment upon
the frog. But for the web of the foot of this animal (and the gills
and tail of its tadpole, in which Leeuwenhoek3 describes the phenomena
most clearly) we should not, perhaps for a long time, have arrived
at a satisfactory knowledge of the existence and the conditions of
the capillary circulation. As is well known, an accurate acquaintance
with the constituents of the blood directly concerned in nutrition
has been obtained by observation on the frog, as well as important
facts in the physiology of the blood and lymph, such as the intimate
knowledge of the corpuscles of both fluids, and the coagulability
of the plasma; while in no less degree have experiments on these
animals served to establish the laws of the heart’s action. Moreover,
physiology is not the only science indebted to the frog: in histology
many important results have been obtained from observations on it, and
for histological instruction it is now indispensable. To it we owe much
of our knowledge of the
structure of nerve fibres, their origin and termination, especially in
muscle, their relations within the ganglia, and even the structure of
muscular fibre itself. For the study of reproduction and development
the frog has, next to the chick, afforded the most important material:
one need but refer to the investigations on impregnation from the time
of Spallanzani to that of Newport4, the phenomena of cleavage, and many others.
Thus with progress of time the field in which the frog has been
submitted to observation and experiment, whether for the demonstration
of established facts to students or for the solving of new problems,
has vastly increased, and this batrachian has indeed become, as we have
stated, the physiologist’s domestic animal.
That, for these manifold uses, a more exact anatomical knowledge of
the frog is very necessary is self-evident. The majority of students
commencing the study of physiology have little more than a superficial
knowledge of the sciatic nerve and the leg-muscles; at most, of the
spinal cord and its nerve-roots; and only acquire any further knowledge
in a disconnected manner. For this they can scarcely be reproached,
the literature of the anatomy of the frog being so widely scattered in
monographs and journals that reference to it involves the expenditure
of much time. This attempt, therefore, to produce a complete anatomy
of the frog, based throughout upon my own observations, cannot be
considered superfluous; it is rather to be feared it may be thought
insufficient.
The European frogs5 alone are treated of in the following
description, i.e. the two species, Rana esculenta, L.,
and R. temporaria, L., the former being more particularly
described, though such differences in structure as occur are noted.
This is not the place to discuss the exact systematic characters of
the two species, yet they cannot be ignored entirely. The species
were, from their habitats, long ago distinguished by C. Gessner6, and named
Rana rubeta, s. gibbosa, the garden or grass-frog, and
Rana aquatica, s. innoxia, the water-frog; at least,
from his figure, the former can be no other than R. temporaria,
though Gessner, probably expecting to find in it the rubeta of
older writers, adds that it ‘ist für giftig zu halten.’
Leeuwenhoek7 also correctly distinguished between
them, but it is to Rösel8 that we are chiefly indebted for a careful
discrimination and an accurate knowledge of the life-histories of the
two species.
Fig. 1.
The green water-frog, Rana esculenta L.
Rana esculenta, L. The green water-frog, Fig. 1, usually
attains a larger size9 and is more active than the other species, and
for this reason is better adapted to the purposes of the physiologist;
hence I have chosen it for description.
The head is flat, as broad as it is long,
and triangular with an obtuse snout in front. The upper surface of the
head, i.e. the space between the eyes, is slightly concave,
grooved, and narrower than in R. temporaria. The tympanic
membrane is circular, and relatively to the eye is larger. The upper
eyelids have several transverse folds in their hinder part. The
pupil is oval, with the long axis horizontal. The vomerine teeth are
arranged in two clusters, which are relatively larger than in R.
temporaria and lie exactly between the posterior nares, without
however touching them. The openings of the Eustachian tubes do not
exceed in size the posterior nares to so great an extent as they do in
R. temporaria. The male possesses a vocal sac on either side,
which reaches the surface beneath the tympanic membrane through a
cleft placed behind the angle of the mouth, and is, in well-developed
specimens, about the size of a cherry. The hind limbs are relatively
longer. The toes are long, and taper towards their tips: the webs
between the toes are cut out semicircularly, and that of the longest
or fourth toe is continued to the tip of the last phalanx. The
supplemental toe is an oval prominence of cartilaginous hardness. The
skin of the back has wart-like tubercles arranged longitudinally in raised
lines; one of these lines runs on each side from the posterior canthus
as far as the thigh, and is very constant: in the male a second line
surrounds the posterior margin of the vocal sac; a corresponding line
exists in the female.
The skin of the belly is quite smooth, the colour presenting many
variations which appear to depend upon very diverse circumstances. It
varies with changes in the physiological condition of the animal. Von
Wittich10
has shown that a bright green specimen changes to a dark leafy green
colour on exclusion of light; also, that dark specimens become almost a
lemon-yellow colour on exposure to bright sunlight; and he has pointed
out that this brightening of the skin is an active condition dependent
upon contraction of the stellate pigment-cells. It is therefore not
surprising, as the same inquirer observes, that one should sometimes
find specimens of R. esculenta in which the ground colour is
almost a greenish yellow (as in Rösel’s figure, Pl. XIII), whilst in
others it can only be distinguished from the dorsal black patches by a
faint greenish shade. There
is no doubt that difference of habitat influences the colour; but this
may again be modified by light11, as has been established in the case of
fish by direct observation12. Apparent varieties may this occur.
In frog-tanks such diversities of colour may not unfrequently be
observed in the same individual, as for example when the lower part
of the body immersed in muddy water is dark, while the part above the
water is bright. That the process of casting the skin exercises an
influence on the brightness of the colouring is certain, yet there are,
as von Wittich has correctly remarked, other alterations of colour
which are in no way connected with this process, and are evidently
more of a pathological nature; such as when the frog assumes a dirty
green spotted appearance, the green fading more and more, until all
the patches which are usually green appear of a dirty greyish-brown
with a faint bronze shimmer. According to this author these changes are
most readily brought about by starvation. The dark colour which frogs
exhibit after hibernation is perhaps to be ascribed to the co-operation
of several of the causes mentioned above.
The usual colouring of healthy animals is as follows: the back is
bright green with three golden yellow longitudinal stripes, one median
and two lateral, and a number of irregular brown or black stripes of
approximately uniform width: on the head are a pair of black stripes
which pass from the angles of the eyes across the nares to the tip of
the nose; now and then the tympanic membrane and surrounding parts have
also a black patch, as in R. temporaria: another black stripe
is found on the anterior surface of the arm, in the region of the
shoulder: and on the thighs are black, yellow, and white mottlings. The
whole of the under-surface is white or yellowish. At times the yellow
stripes of the back are wanting or are indistinct. It has already
been mentioned that many varieties may occur; and these have in all
probability given rise to the descriptions of reputed new species, such
as R. maritima, Risso, found in South Europe; R. alpina,
Risso, found in the high-lying Alpine lakes; R. hispanica of
Fitzinger and Bonaparte, and R. calcarata of Michahelles,
the last three of which certainly cannot be retained. It is not improbable that the
water-frog, which Spallanzani13 used in his experiments on impregnation, was
the R. maritima of Risso. He says, one must not confound his
frog with that which Rösel calls the green water-frog; the former
being much smaller, without the three dorsal golden-yellow stripes,
and the spawning season (in Lombardy) occurring during April and May.
Rusconi14
also describes two varieties in Northern Italy.
Rana temporaria, L., the brown or grass-frog, is so named
from the large black patch in the temporal region, i.e. between
the eye and the shoulder. While the separation of the preceding
species into several varieties does not seem to be well founded,
it appears that two distinct species have been included under the
name of R. temporaria. Millet of Angers15 first described, in his
Fauna du département de Maine-et-Loire, as ‘grenouille rousse,’
a species differing from R. temporaria, and gave the
species previously known as R. temporaria the name of R.
flaviventris, ‘grenouille à ventre jaune.’ No further notice,
however, was taken of this observation, not even by Duméril and
Bibron in their ‘Erpétologie.’ Quite independently Steenstrup16, in the
year 1846, pointed out that two frogs, differing in structure and
habits, had been confounded under the name R. temporaria;
these he distinguished as R. platyrhinus and R.
oxyrhinus. Von Siebold17, and also Schiff18 in part, have confirmed
these statements. My own observations lead me to a like conclusion;
I shall therefore distinguish two species, viz.:—(1) Rana
temporaria, L., Rana platyrhinus, Steenstrup; (2) Rana
oxyrhinus, Steenstrup.
Fig. 2.
The brown grass-frog, Rana temporaria, L.
Rana temporaria, L.; Rana platyrhinus, Steenstrup.
The brown grass-frog, Fig. 2, does not attain
the dimensions of R. esculenta, L., but is, however, always
larger than R. oxyrhinus. The head is somewhat broader than
long, and the upper surface of the skull is not grooved, as in R.
esculenta, but is flat. The space between the eyes is wider
(according to Duméril, equal to the width of the upper eyelid,
whereas in R. esculenta it is just two-thirds this width): the
fronto-parietal bones are wide and flat. The tympanic membrane, in
comparison with the eye, is smaller than in R. esculenta, and
is usually less distinguishable from the surrounding parts as regards
colour and transparency. The apertures of the Eustachian tubes are,
relatively to the posterior nares, larger than in the water-frog. The
vomerine teeth are comparatively small and lie in two groups placed
obliquely to each other, their anterior ends diverging from each other
and being prolonged as ridges to the anterior margins of the posterior
nares. The two groups do not lie between the nasal apertures, but
behind a line drawn transversely through their posterior margins. Vocal
sacs are absent in both sexes. The hind legs are relatively shorter:
the toes are not so evenly tapered off, indeed they are slightly
swollen: the fourth toe, as compared with the third and fifth, is
somewhat longer than in R. esculenta; the web of this toe does
not extend to the tip of the toe, but terminates in both sexes at the
last phalanx but one; the web on the third toe is less developed on the
thumb side than on the other: on the remaining toes also the margins of
the web are less developed
than in R. esculenta, so that the free borders appear more
crescentic. The supplemental toe forms only a soft and inconspicuous
prominence. The back is mostly smooth; the raised glandular ridge,
which extends along each side from the eye to the thigh, is present,
but is much narrower and less prominent than in R. esculenta;
another ridge passes from the angle of the mouth to the shoulder. The
colouring in general, and especially the ground colour of the dorsal
surface, varies from the brightest tints to the darkest brown-black;
the conditions causing these variations being, no doubt, the same as
those described above in R. esculenta. A dark-brown specimen
taken from a dark frog-tank is usually yellowish red on the following
day. The black patch between the angle of the mouth and the shoulder
has given this species the name of R. temporaria, and is
constant. A black stripe passes from the eye across the nostril to
the tip of the snout, and a similar one is found upon the anterior
surface of the upper arm. On the hind legs the bands are chiefly
transverse. The ventral surface is yellowish, and sometimes spotted.
The thighs have a granular appearance, and these as well as the belly
and the neighbourhood of the anus have frequently a reddish coloration
presenting the appearance of an irritated surface.
Rana oxyrhinus, Steenstrup. This species is always smaller
and more elegant in shape than the preceding one. The head is conical,
with the pointed snout projecting beyond the lower jaw; a feature
which is especially evident on looking from below. The space between
the eyes is narrower than in R. temporaria, and is not grooved,
but convex; the fronto-parietal bones are narrow and arched. With
respect to the arrangement of the vomerine teeth and the sizes of the
apertures of the Eustachian tubes, this species holds an intermediate
position between the other two. Next to the pointed snout, the greatest
difference between this species and R. temporaria is the
presence of a much larger supplemental toe, which is of cartilaginous
hardness, compressed from side to side, and contains a larger bone19. The vocal
sacs are absent. In the males the web of the longest toe reaches to
the last phalanx but one; in the females, on the contrary, the last
three phalanges project freely beyond the web. The extremities of the
toes are more pointed than in R. temporaria, in which respect,
as also in several
others, it approaches R. esculenta. In colouring, R.
oxyrhinus resembles R. temporaria; the throat, however,
is usually pure white, at least in the males, the breast dusky white
and spotted, while in R. temporaria the throat and breast are
more uniformly coloured and yellowish. V. Siebold has remarked that,
during the pairing-season, the males are covered with a bluish bloom20; and,
the whole ground colour being bright at this period, very beautiful
tints result. V. Siebold21 moreover states that the note which the males
produce during the pairing-season is different in the two species. On
the whole, R. oxyrhinus appears to stand midway between R.
esculenta and R. temporaria.
Thomas22, in addition, distinguishes another species,
R. agilis, which however may be the ‘grenouille rousse’
of Millet. Schlotthauber23 has described a frog which, in marking and
colouring, might hold a middle place between R. esculenta and
R. temporaria; in my opinion this is probably a cross between
the two. That attempts at copulation are made, despite the difference
of the pairing-season, is well known; Pontallié24 mentions this, and I have
myself often found males of R. temporaria in conjunction with
females of R. esculenta.
I use the following terminology. I suppose the animal to be in its
natural position, the belly towards the ground, the back upwards; a
horizontal plane passing from the snout to the anus divides the body
into a superior or dorsal half and an inferior or ventral half. The
terms superior and inferior, dorsal and ventral, indicate positions
with relation to this plane. I call that part anterior which looks
towards the head, and that posterior which looks towards the anus. A
vertical plane at right angles to the middle of the longitudinal axis
of the body, divides it into an anterior or cephalic and a posterior
or caudal half. All sections and planes which lie parallel to this, as
well as this itself, are frontal. Lastly, by a perpendicular section
along the middle line of the body the animal is divided into right and
left halves; this plane is the median plane; and the position relative
to this plane is expressed by the terms median or lateral. Planes
parallel to the median plane are termed sagittal.
THE BONES AND JOINTS.
LITERATURE.
van Altena, Commentatio ad quæst. zoologicam in academia
Lugduno-Batav. a. MDCCCXXVIII
propositam, qua desideratur ut systematice enumerentur species indigenæ
reptilium ex ordine batrachiorum addita unius saltem speciei anatomia
et præsertim osteographia accurata. Lugd. Bat. 1829. 4o.
With 4 Plates.
Ange, Martin St., Recherches sur les organes transitoires
des batraciens. Annales des Sciences naturelles. 1re Série.
Vol. XXIV. 1831.
Bell, Article Amphibia, in Todd’s Cyclopaedia of Anatomy and
Physiology. Vol. I, p. 90. 1835–1836.
Born, Dr. Gustav, Ue.d. Nasenholen u.d. Thränennasengang der
Amphibien. Leipzig, 1877.
Bruch, G., Beiträge zur Naturgeschichte und Klassification
der nackten Amphibien. Würzburger Naturzeitschrift, 1862.
Bruch, G., Neue Beobachtungen zur Naturgeschichte der
einheimischen Batrachier. Würzburger Naturzeitschrift, 1863.
Cuvier, Recherches sur les ossements fossiles. Vol. V.
Pt. II. Paris, 1825.
Cuvier, Leçons d’anatomie comparée. Paris, 1835. Vol. I.
Cuvier, Ueber die Rückenwirbel der Reptilien und Amphibien,
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Ducrotay de Blainville, Ostéographie ou description
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Dugès, Recherches sur l’ostéologie et la myologie des
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Duméril et Bibron, Erpétologie générale ou Histoire complète
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Gegenbaur, Untersuchungen zur vergl. Anatomie der
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Hallmann, Die vergleichende Osteologie des Schläfenbeins,
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Hoffmann, C. K., Beiträge zur Erkenntniss des Beckens der
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Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
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Huxley, On the Theory of the Vertebrate Skull; Croonian
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Huxley, Lectures on the Elements of Comparative Anatomy.
Huxley, Handbuch der Anatomie der Wirbelthiere. Deutsche
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Kehrer, G., Beiträge zur Kenntniss d. Carpus und Tarsus
d. Amphibien, Reptilien, und Säuger. Berichte d. naturf. Gesell. z.
Freiburg. 1886.
v. Klein, Beiträge zur Anatomie der ungeschwänzten
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Leukart, Zwischenkiefer. Valentins Repertoire. 1841,
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Marshall, A. M., The Frog. Manchester and London. 2nd Edit.,
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Parker, W. K., Structure and Development of the skull of the
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Parker, W. K., Skull of Batrachia. Phil. Trans. 1876,
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Parker, W. K., and Bettany, G. T., Morphology of the
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Vertebrates, translated by W. Newton Parker. London, 1886.
THE BONES AND JOINTS.
The consideration of the differences in form, number, and
histological structure, which the parts of the skeleton present during
the various stages of development does not fall within the scope of
this book: we have here but to deal with the adult frog.
The skeleton is made up of histologically different materials;
these are:—(1) bone, (2) hyaline cartilage, and (3) so-called
calcified cartilage. Concerning the last it is necessary to make some
observations. I have chosen for it the name calcified cartilage in
place of the more usual names ‘cartilaginous bone’ or ‘primordial
ossification,’ as by this term its nature appears to be expressed
without any ambiguity25: it is hyaline cartilage in which calcareous
particles have been deposited to a greater or less extent: in the fresh
state it has the appearance of moderately firm cartilage; when dry it
becomes opaque and white, like the calcareous crusts on the cartilages
of the Plagiostomata. The calcareous material is deposited in the
cartilage in finer or coarser granules; after removal of the lime by
means of acids, the cartilaginous structure becomes apparent although
not so perfectly as in unchanged cartilage.
Fig. 3.
Longitudinal section through the upper extremity
of the femur of Rana esculenta,
magnified.
A
Hyaline cartilage (articular cartilage).
c
Hyaline cartilage closing end of bony cylinder.
c′
Calcified cartilage of epiphysis.
D
Bony cylinder of diaphysis.
E
Epiphysis.
M
Marrow cavity.
o
End of diaphysis.
This calcified cartilage is widely distributed in the frog’s
skeleton: very many parts, which in higher animals consist only
temporarily of this substance during the transition from cartilage to
bone, are in the frog formed of it throughout life. It is especially
well-marked in the epiphyses of the long bones in the hand and foot,
in the bones of the shoulder-girdle, etc. To avoid repetition later on
I will briefly describe it as found in the first-mentioned situation.
Dugès26
has described its external appearance, while Bruch27 has made us acquainted with its histological
peculiarities. If a long bone of the frog be dried, the femur for
example, the middle part is found to differ considerably from the
epiphyses in colour and in other particulars. The shaft alone has the
appearance of bone, the epiphysis consisting of a white, opaque, firm
substance, resembling plaster of Paris or lime, but which in the fresh
moist state is exactly like cartilage. The epiphyses, which are fitted
to the ends of the diaphysis like the cap of a stick-handle, have
sharply defined margins (Fig. 3), as is well seen
in Figs. 36, 39, 45, and
46. If a section be made through the epiphysis
and part of the diaphysis, the long tube of true bone is seen to cease
abruptly above o, Fig. 3, and over the end
of it the epiphysis E is fixed. This epiphysis consists almost
entirely of calcified cartilage c′, and has merely a superficial
layer of hyaline cartilage A. The bony cylinder of the diaphysis
o, which contains the marrow M in its interior, is shut
off from the epiphysis by hyaline cartilage, the cells of which are
arranged in transverse layers, o.
I. THE VERTEBRAL COLUMN. — I. General Description of the nine Vertebrae. — II. Description of Particular Vertebrae. — III. Articulations of the Vertebrae. — IV. Structure of the Vertebrae 28 (Figs. 6 and 7). — V. The Urostyle (Figs. 8 and 9). — II. THE SKULL. — A. The Cranium. — B. The Bones of the Face.
The vertebral column of the frog consists of ten bones,
viz. nine true vertebrae, and the rod-shaped urostyle, which
alone is almost as long as all the remaining vertebrae.
a. The bodies of the vertebrae are compressed from
above downwards; the posterior surface of each body, with the exception
of the eighth, presents an
articular head covered with cartilage; the anterior surfaces, with the
exception of the ninth, present corresponding articular depressions,
covered with cartilage.
Fig. 4.
Vertebrae of Rana esculenta, seen from
below, twice the natural size.
1 to 9
First to ninth vertebræ.
c
Urostyle.
o o
Articular processes.
sc
The two facets for articulation with the urostyle.
b. The arches, which have somewhat sharp margins
both before and behind, bear the following processes:— 1. The
articular processes (Figs. 4 and 5 o o) are similarly placed
to those of the dorsal vertebrae of man: they project horizontally,
the cartilaginous articular surfaces on the posterior processes being
directed downwards, those on the anterior upwards.
Fig. 5.
Vertebral column of Rana esculenta, from
above, twice nat. size.
1 to 9
First to ninth vertebræ.
c
Urostyle.
o o
Articular processes.
sc
Facets for articulation with the urostyle.
t t′
Transverse processes.
2. The transverse processes (Figs. 4 and 5 t
t′) are strong, flat, and of very varying size and direction. The
transverse processes of the fourth vertebra are the longest, those of
the third only a little shorter; the shortest are those of the seventh
and eighth. The atlas has no transverse processes. Those of the second
and third vertebrae project directly outwards and slightly downwards;
those of the fourth, fifth, and sixth upwards and backwards. The
seventh and eighth project more directly outwards and at the same time
backwards; the ninth upwards and markedly backwards. All the transverse
processes have cartilaginous epiphyses; the largest are those of the
second, third, fourth, and ninth vertebrae.
3. The spinous processes are generally small,
but individually of varying size, appearance, and direction. The
longest are those of the third, fourth, and fifth vertebrae; these
are, in transverse section, of a three-sided prismatic form, as in the dorsal vertebrae of
man; they are directed backwards and provided with cartilaginous
epiphyses. The spinous processes of the sixth and seventh are shorter,
compressed from side to side, project directly upwards, and are usually
without cartilaginous epiphyses; that of the eighth is still shorter.
As regards the spinous processes, those of the third, fourth, and fifth
vertebrae resemble those of the dorsal vertebrae in man; those of the
sixth, seventh, and eighth, lumbar vertebrae. The ninth has either
no spinous process or only a rudimentary one. The first and second
vertebrae may be looked upon as cervical vertebrae: the second has a
short spinous process with a cartilaginous epiphysis. In the first,
the cartilage which unites the two halves of the arch represents the
rudiment of a spinous process.
1. The atlas or first vertebra has a thin
body, compressed from above downwards, and an arch. The body has
posteriorly a slightly raised, cartilaginous, articular head, which is
broader transversely: in front it has two oval articular facets, which
are separated from each other by a median projection. Each facet is
concave, and directed forwards, outwards, and slightly upwards. The
arch is completed above by cartilage, which projects slightly to form
the rudiment of a spinous process. The hinder margin of the arch bears
two articular processes. Transverse processes are wanting.
2. The second vertebra presents all the general
characters of an ordinary
vertebra, except that the transverse processes are directed somewhat
downwards.
3. The transverse processes of the third vertebra
are longer than those of the second: each is directed downwards, is
broader at its extremity than at its base, and bears a hammer-shaped
cartilaginous epiphysis larger than those of the remaining transverse
processes.
4. The transverse processes of the fourth vertebra
are the longest: each is broader at its free end than at its base,
is directed upwards and backwards, and provided with a cartilaginous
epiphysis.
5, 6, 7. The transverse processes of the
fifth, sixth, and seventh vertebrae are smaller,
contracted towards their free extremities, and directed upwards.
8. The eighth vertebra is distinguished from the rest
by its body possessing no articular head. It presents, at each end, a
concave articular depression. The transverse processes resemble those
of the seventh.
9. The ninth vertebra unites the vertebral column with
the hip-bones, and is hence to be regarded as a sacrum. The body
bears on its anterior surface an articular head for articulation with
the eighth vertebra: on its posterior surface are two small rounded
and closely approximated processes (Figs. 4 and 5sc) for
articulation with the urostyle. The transverse processes are strong,
broader at the free ends than at their origin, directed upwards and
backwards, and provided with cartilaginous epiphyses.
The articular heads and depressions of the vertebral bodies,
together with the joint surfaces of the articular processes, are
covered with hyaline cartilage. The periosteum of the bodies, as
also that of the articular processes, forms true capsular joint ligaments.
The articulations of the vertebrae are still further strengthened
by longitudinal fibres, which extend along the anterior and
posterior surfaces of the vertebrae, and correspond to the ligamentum
vertebrale commune anticum et posticum of man. Between the
vertebral arches are membranes which represent the ligamenta
intercruralia. Between the spinous processes are bands of connective
tissue which form ligamenta interspinalia. (For the articulation of
the atlas with the occiput, see page 24.)
Fig. 6.
Transverse section through a vertebra
of Rana esculenta, magnified.
c
Cancellous bone.
Ch
Chorda dorsalis.
Ch′
Sheath of chorda dorsalis.
o
Compact bone on the upper and lower surfaces of the body.
Fig. 7.
Longitudinal section through the
posterior half of the body of a
vertebra of Rana esculenta.
a
Cartilage of the head.
c
Cancellous bone.
o
Shell of compact bone.
Each vertebral body consists of a cylinder of compact bone, which
is directly continued into the bony substance of the arch. In the
interior of the cylinder is found an isolated persistent vestige of the
chorda dorsalis (Ch): this is surrounded by cancellous
bone (c), which extends backwards towards the articular head
and forwards directly into the articular cartilage, compact bone being
absent in these parts. In a transverse section of a vertebral body
the following parts are seen (Fig. 6):—a. An outer layer of
compact bone (o) (the transverse section of the above-mentioned
cylinder), which is formed of parallel lamellae of varying thickness.
These, according to Gegenbaur, and as I can confirm, are arranged in
well-defined groups, each of five to eight lamellae. The number of the
secondary lamellae increases with the age of the animal. b.
In the interior, in the form of a cylinder, is the remnant of the
chorda dorsalis. It consists of a double sheath (Ch′) and
contents (Ch) composed of chorda-cells. c. Immediately
around the persistent portion of the chorda lies the central part of
the vertebral body, formed by transformation of the vertebral cartilage
and of the bases of the original cartilaginous arches. At each side
of the chorda are large marrow-spaces (c), filled
with cells, from which proceed narrower canals, winding in various
directions, and anastomosing freely with one another both before and
behind. Their walls are constituted partly of true bone, partly of
cartilage.
Fig. 8.
Urostyle of Rana esculenta, seen from the side, twice nat.
size. A bristle is passed through the canal. vert. and out
through the canal. coccyg. of the right side.
a
Anterior extremity.
c.c.
Canal. coccyg.
s
Dorsal ridge (pr. spinos.).
Fig. 9.
Urostyle of Rana esculenta, seen from the side, twice nat.
size.
c
Ventral border.
c.v.
Canal. vertebralis.
s
Dorsal ridge (pr. spinos.).
The urostyle is a long, median, rod-like bone, which projects
backwards, midway between the two hip-bones, and terminates over the
anus. The anterior end (Fig. 8 a) is the thicker and broader
part of the bone, and has two articular depressions (Fig. 9) for
articulation with the two facets of the ninth vertebra. The hinder
end is pointed and cylindrical, and terminates in a cartilage, which
is fixed in the tubular end of the bone. The middle portion is almost
cylindrical, and has a groove along the ventral surface which gradually
becomes less marked behind. The dorsal surface bears a ridge (Figs. 8
and 9 s), which is high and thick in front, becomes sharper
and less prominent as it proceeds backwards, and gradually disappears
towards the hinder third of the bone, so that in transverse section
the anterior two-thirds of the bone appear triangular, with a ventral
and two lateral surfaces: while the hinder third is cylindrical.
The anterior portion of the bone contains a canal, canalis
vertebralis (Fig. 9 c.v.), which is a continuation of the
vertebral canal, along which the hindermost spinal nerves pass. On
each side of the anterior portion of the urostyle are small apertures
(Fig. 8 c.c.), which lead into canals (canales coccygei),
which open into the vertebral canal, and through which the coccygeal
nerves pass. In front of these openings and partly overhanging them are
small triangular projections (Fig. 8) (processus transversarii):
these, however, are not constant, and are more often found in R.
esculenta than in R. temporaria, in which latter species the
openings are smaller.
The flat form of the frog’s head, as in batrachians generally,
depends upon the wide separation of the jaw-bones of the two sides,
and on the large size of the orbital cavities and the horizontal direction of their floors. The
outer circumference of the head forms a parabolic frame (Figs. 10 and
11), composed of the maxillary (m), premaxillary (i), and
quadratojugal bones (j). In the middle of this curved framework
lies the elongated prismatic cranium. Anteriorly, this is attached
to the fore-part of the frame by means of the cartilaginous skeleton
of the organs of smell (Fig. 11 e′); posteriorly, it widens
out into two transverse arms (p), which contain the organs of
hearing. From this base, on either side, a bony strut, composed of the
posterior arms of the squamosal (t′) and of the pterygoid bones,
passes backwards to the hinder end of the frame. The anterior arm of
the squamosal bone (t) does not quite reach the framework,
but is attached to it by ligament alone. Between the last-named
arm posteriorly, the cranium on the inner side, and the maxillary
frame-work laterally, is a large space representing the orbital and
temporal fossae of human anatomy.
Fig. 10.
Skull of Rana esculenta, seen from above,
twice natural size.
e
Sphenethmoid.
fn
Nasal.
f.p.
Fronto-parietal.
i
Premaxillary.
j
Quadrato-jugal.
m
Maxillary.
o
Exoccipital.
op
Opisthotic.
p
Prootic.
pt
Pterygoid.
pt′
Posterior limb of pterygoid.
t
Squamosal.
t′
Posterior arm of the same.
Fig. 11.
Skull of Rana esculenta, seen from below,
twice natural size.
c
Cartilaginous wall of skull.
e
Sphenethmoid.
e′
Cartilaginous skeleton of nose.
h′
Stylo-hyoid.
i
Premaxillary.
m
Maxillary.
m′
Quadrate tract.
o
Exoccipital.
p
Prootic.
p′
Anterior arm of prootic (ala magna autt.).
p″
Trigeminal foramen.
pl
Palatine.
pt
Pterygoid.
pt′
Posterior arm of pterygoid.
s
Parasphenoid.
v
Vomer.
The cranium of the frog is a prismatic tube, wide behind,
narrow in front, and formed in great part of cartilage (Figs. 15 and 17). Our indigenous
species are characteristically distinguished from one another by
peculiarities in the form of the cranium. In R. esculenta it is
long and narrow, in R. temporaria short and wide. The superior
surface in the former is markedly concave, while in the latter it is
flat, and in R. oxyrhinus arched. These differences are readily
recognised in the living animal.
Cuvier, l. c., p. 387,
Pl. XXIV, bb.—Dugès, l. c., n. 14.—Parker and
Bettany, l. c., p. 166, exoccipitals.
Fig. 12.
Skull of Rana esculenta, seen from behind,
twice natural size.
a
Stapes.
a′
Columella auris.
a″
Extrastapedial.
c
Condyles of exoccipitals.
h
Stylo-hyoid.
o
Exoccipitals.
p
Prootic.
p′
Process to which the jaw is attached.
t
Squamosal.
These paired bones form the hinder part of the cranium; they bound
the foramen magnum, and articulate with the vertebral column.
They are imbedded in the cartilaginous matrix of the skull, and are
separated above by an unossified part of this matrix (occipitale
superius, Dugès), which represents the tabular portion of human
anatomy: below they are separated by a similar part (occipitale
basilare, Dugès) which represents the body of the occipital bone.
They therefore properly represent only the condylar portions (partes
condyloideae) of the human occipital bone. Each possesses a
cartilaginous articular head, for articulation with the first
vertebra: these converge below, and surround the lower half of the
circumference of the foramen magnum. This latter has, in R.
esculenta, a transversely oval outline; in R. temporaria,
a somewhat heart-shaped outline, with the apex directed upwards: in
accordance with this the whole bone is wider than high in the first
species; and in the latter it is higher than it is wide. From the
upper and outer border of the foramen magnum on each side a ridge runs obliquely outwards
and downwards, in which lies the suture between this bone and the
prootic bones. This bony ridge (processus mastoideus, autt.)
is usually cartilaginous in R. esculenta, even in old animals;
in R. temporaria, even in young specimens, it is bony. In the
latter species the bones unite very early, while in the former they
remain separated by the primitive cartilage. Between this crest and
the processus condyloideus there is a depression (fossa
condyloidea), with a hole (foramen condyloideum) through
which the vagus nerve leaves the cranium. The exoccipital take part in
the formation of the labyrinth of the ear, as will be noticed later
on.
Articulation of the Exoccipital Bones with the Atlas. From the
middle of the anterior surface of the body of the atlas a ligament
arises, representing to a certain extent the lig. suspensorium dentis,
and attached to the basal portions of the exoccipital bones.
2. The prootic bones, ossa
petrosa, Cuvier (Figs. 10, 11, and 12 p).
Cuvier, rocher, l. c., p. 388,
Pl. XXIV, ee.—Dugès, n. 12, rupéo-ptéréal.—Stannius,
ala temporalis.—Meckel, Schädelstück des
Schläfenbeins.—Parker and Bettany, l. c.,
prootic.
Fig. 13.
Skull of Rana esculenta, seen from below, twice
natural size.
c
Cartilaginous wall of skull.
e
Sphenethmoid.
e′
Cartilaginous nasal skeleton.
h′
Stylo-hyoid.
i
Premaxillary.
m
Maxillary.
m′
Quadrate tract.
o
Exoccipital.
p
Prootic.
p′
Anterior arm of prootic.
p″
Trigeminal foramen.
pl
Palatine.
pt
Anterior arm of pterygoid.
pt′
Posterior arm of pterygoid.
s
Parasphenoid.
v
Vomer.
These paired bones lie at the sides and in front of the exoccipital
bones. As already explained, they remain in R. esculenta
separated from these by cartilage, while in R. temporaria they
early enter into bony union with them; this is due to the complete
ossification of the processus mastoideus in the latter
species, as stated above. The prootics form the lateral expansions
of the posterior part of the skull in which the organs of hearing
are placed. The large cavity which contains the ear labyrinth is
completed by the exoccipital: internally it opens freely into the
skull, and externally on the posterior wall of the skull through
the foramen ovale, which is formed by both these bones. The
postero-lateral part of the prootic usually remains cartilaginous:
at the side and in front of the foramen ovale this cartilage
is pierced by a small opening, through which passes the nervus
facialis or ramus tympanicus n. vagi (Volkmann). At the
side there is a process to which the suspensorium of the lower jaw is
attached (Fig. 12p): behind this is a
hollow in which the auditory ossicles lie, and which may be designated
fossa tympanica (Fig. 12t).
The anterior border of the bone forms the hinder and inner walls of the orbit. Here also
is the trigeminal foramen (Fig. 11p″)
through which the N. trigeminus and the several nerves for
the muscles of the eye pass; it represents the foramen ovale,
for. rotundum, and the fissura orbitalis superior
(sphenoidal fissure) of the human sphenoid bone. The foramen is
sometimes, especially in young animals, only a notch, which is
completed by cartilage. On account of the relation of this part
(Fig. 11p′) of the bone to the nerves
which pierce it, the whole bone has been named by Stannius the ala
magna or temporalis of the sphenoid; it has been also looked
upon as a bone which contains these elements, as by Dugès, who on this
account calls it rupéo-ptéréal.
Appendages of the Prootic Bones.
1. The styloid cartilage. From the cartilaginous portion
of the prootic the styloid cartilage runs downwards, backwards,
and inwards, and is continued directly into the anterior cornu of
the hyoid bone (Figs. 11h′ and 12h).
2. The auditory ossicles.
a. A thick cartilaginous disc, the operculum (Fig. 12a), closes the foramen ovale.
b. To the operculum is attached a bony, club-shaped piece,
the columella auris (Fig. 12a′),
which has at its inner, thicker end a cartilaginous epiphysis, the
interstapedial; it lies transversely with the apex directed
outwards, and this longer portion is the mediostapedial.
c. To the apex of the mediostapedial is attached, at
an obtuse angle, the
third cartilaginous piece, the extrastapedial (Fig. 12a″). It is attached to the tympanic
membrane, and by its upper portion is fastened to the cartilaginous
tympanic ring by a smaller piece, the suprastapedial.
3. The tympanic ring (annulus tympanicus) is an
annular cartilaginous frame; or more exactly, has the shape of a short,
truncated cone, as it narrows towards the middle line: it is attached
to the squamosal bone. (See Organ of hearing.)
3. The parasphenoid, os
sphenoideum, Cuvier (Figs. 11 and 16s).
Cuvier, l. c., p. 388,
Pl. XXIV, d.—Dugès, n. 8.—Meckel, Theil des
Grundbeins.—Parker and Bettany, l. c.,
parasphenoid.
A large portion of the base of the cranium is taken up by this
cruciform bone. Of the two longitudinal median processes, the posterior
is by far the shorter, and lies in front of and partly below the
cartilaginous os occipitale basilare. The anterior longer
longitudinal arm closes in the greater part of the cranium from below,
and articulates by its outer edges with that part of the prootic bones
often described as the alae magnae, and also with the cartilage
lying in front, which forms the greater part of the lateral walls of
the cranium. The anterior extremity of the bone articulates with the
palatine bones. The transverse arms lie on the under surface of the
exoccipitals and of the prootics.
The greater width of the cranium in R. temporaria is
associated with the greater relative width of the anterior arm of this
bone.
4. The fronto-parietal bones, ossa
fronto-parietalia, Cuvier (Figs. 10 and 14fp).
Cuvier, l. c., p. 387, Pl. XXIV, c.
c.—Dugès, n. 1.—Parker and Bettany, l. c.,
fronto-parietal.
These are a pair of somewhat long, flat bones, which form the
principal part of the upper wall or roof of the cranium, and cover in
superiorly the cartilaginous cranium, which is here, in great part,
persistent. They are united in the middle line by the sagittal suture;
posteriorly they articulate with the exoccipital and prootic bones;
anteriorly with the sphenethmoid, which they overlap like tiles.
The outer margin of each bone is bent somewhat downwards (Fig. 16fp), and between it and the parasphenoid
there is a space in the wall of the cranium which is closed in by
cartilage and connective tissue only.
These bones are narrower in R. esculenta, and along the
sagittal suture are depressed into a groove: where the superior surface
bends down to become lateral the edges are much more prominent.
In R. temporaria the bones are broader and flat or even
somewhat arched. The latter condition is still more marked in R.
oxyrhinus.
5. The sphenethmoid,
os ethmoideum (Figs. 10, 11, 14, and 16e).
Cuvier, os en ceinture, l. c.,
p. 387, Pl. XXIV, a.—Dugès, n. 15.—Rathke, anterior or
sphenoidal wing (Vortr. z. vergl. Anat. d. Wirbelthiere, Leipzig, 1862,
p. 42).—Meckel, Riechbein, l. c., p. 502.—Parker
and Bettany, l. c., ethmoid.
The long tubular cranium is completed anteriorly by a single
bone, which forms at once the roof, floor, and lateral walls. It
is consequently more or less ring-shaped, on which account it has
been named ‘os en ceinture’ by Cuvier. Only the posterior portion is
annular, however: the anterior portion forms a double canal, with
a median partition, for the passage of the nerves of smell, and as
these canals are widened out anteriorly, this part of the bone helps
to complete the nasal cavities, which, however, are bounded for the
most part by cartilage, as described below. In some species of frogs
(as for example R. occellata, Rathke) this cartilage is partly
ossified.
The sphenethmoid has on each side a small bony canal, running
forwards and inwards, through which the ramus nasalis of the
first division of the trigeminal nerve passes.
The cartilaginous skeleton of the nose (Figs. 14 and 16n,
n″, n‴, n⁗). The anterior borders of the
funnel-shaped cavities of the sphenethmoid pass into cartilage,
which forms two capsules, separated from each other by a median
cartilaginous septum, and opening laterally. We can distinguish,
(a) a cartilaginous septum, forming a continuation of the
bony one; (b) the floor of the nasal cavity, narrower behind,
wider in front; (c) a roof somewhat narrower than the floor.
The floor and roof are united in front by an arched surface. From
this cartilaginous capsule various processes project, which unite
it to other portions of the facial skeleton: firstly, from the most
posterior portion of the capsule there passes transversely outwards
a bar of cartilage (sn), which, widening, becomes continuous
with the cartilage (sp″) forming the basis of the anterior
arm of the pterygoid bone. From the anterior angle a cartilaginous
process passes outwards (Figs. 14, 16n″), which is attached to a projection on
the anterior end of the
maxillary bone; from the same spot a horn-shaped cartilaginous process
(n″, n‴) curves round backwards and towards the middle
line. This projection bounds the nasal cavity externally, sending off
a free process (n‴) on the way, and ends with a double point on
the roof of the cartilaginous nasal cavity (n⁗). On the floor
of the nasal capsule, on either side, is a knob-shaped cartilaginous
eminence, running from behind, forwards and outwards; this may be
regarded as an indication of a turbinated bone. From the anterior
wall there passes into each nasal cavity an almost horizontal, partly
ossified plate (c.n.), ending posteriorly in a free pointed
border. These are the cornets of Dugès (l. c., p. 12,
Pl. I, Figs. 1, 5), who correctly regarded them as turbinated bones.
Cuvier described them as rudimentary nasal bones29.
Fig. 14.
Cartilaginous basis of the skull of Rana esculenta, from above,
twice natural size. Cartilage shown by stippling.
a.n.
Wings of nasal cartilage.
c.n.
Concha narium.
e
Sphenethmoid.
ff′
Foramina of cranium.
fn
Nasal.
fp
Fronto-parietal.
i
Premaxillary.
j
Quadrato-jugal.
m
Maxillary.
n, sn
Cartilaginous nasal skeleton.
n′, n″, n‴
Processes of the cartilage.
o
Exoccipital bones.
p.
Prootic.
pt
Anterior arm of pterygoid.
pt′
Posterior arm of pterygoid.
s′
Cartilaginous cranium.
sp
Cartilage of suspensorium.
sp′
Cartilage under the squamosal.
sp″
Cartilage under the pterygoid.
t1
Anterior
arm of the squamosal.
t2
Middle
t3
Posterior
Fig. 15.
Nasal cartilages of frog, front
view.
an
Concha narium.
i
Premaxillary bones.
i′
Ascending process of same.
m
Upper jaw.
m′
Lower jaw.
n
Olfactory capsule.
The alar cartilages of the nose have still to be described. They are
(a.n.) shell-shaped cartilages, hollowed out on the inner sides
and decreasing in width
from before backwards. They are movably attached by their anterior
broader ends to the tips of the projecting portions of the premaxillary
bones, and are so arranged as to bound the lateral margins of the nasal
apertures, which they overlap.
Fig. 16.
Cartilaginous skull of Rana esculenta, from below, twice
natural size. Cartilage shown by stippling.
c
Cartilage of prootic.
e
Sphenethmoid.
fp
Fronto-parietal.
i
Premaxillary.
j
Quadrato-jugal.
m
Maxillary.
n, sn
Cartilaginous nasal skeleton.
n′, n″, n‴, n⁗
Processes of nasal cartilage.
o
Exoccipital.
p
Prootic.
pl
Palatine.
pt
Pterygoid.
pt′
Articular surface for pterygoid.
r
Optic foramen.
r′
Foramen for N. abducens.
s
Parasphenoid.
s′
Cartilaginous cranium.
sp
Cartilage of suspensorium.
sp′
Cartilage under squamosal.
sp″
Cartilage under pterygoid.
v
Vomer.
6. The cartilaginous basisof the
skull, Primordial cranium (Figs. 14, 16).
a. If the fronto-parietals be removed, (Figs. 14, 16), a
cartilage (s′) is found which partially closes the cranial
cavity, and which is usually perforated on either side by a foramen
(f′). More anteriorly in the median line is found a space
(f) which extends to the sphenethmoid bone, and is only closed
by connective tissue: posteriorly the cartilage extends between the
exoccipitals as far as the foramen magnum, representing the
os occipitale superius.
b. The base of the cranium is (Fig. 16) also partly
cartilaginous. If the parasphenoid (s) be removed we find
above it a cartilage (s′) which passes backwards between the
exoccipitals, and extends as far back as the foramen magnum: it
corresponds to the os occipitale basilare.
c. The sides of the cranium are formed almost entirely of
cartilage. This cartilage
fills the space bounded by the nasals above, the parasphenoid below,
the so-called ala magna of the prootic bone behind, and the
sphenethmoid in front; and has in its posterior part an aperture
(r) through which passes the nervus opticus, and below
this a smaller one (r′) for the nervus abducens. The
extent of the cartilage in the antero-posterior direction is greater
in R. esculenta than in R. temporaria, or in other words
the sphenethmoid stretches further back in the latter than in the
former.
The Suspensorium.
Fig. 17.
Cartilaginous basis of the skull of Rana esculenta, from above,
twice natural size. Cartilage shown by stippling.
a.n.
Wings of nasal cartilage.
c.n.
Concha narium.
e
Sphenethmoid.
ff′
Foramina of cranium.
fn
Nasal.
fp
Fronto-parietal.
i
Premaxillary.
j
Quadrato-jugal.
m
Maxillary.
n, sn
Cartilaginous nasal skeleton.
n′, n″, n‴
Processes of the cartilage.
o
Exoccipital bones.
p.
Prootic.
pt
Anterior arm of pterygoid.
pt′
Posterior arm of pterygoid.
s′
Cartilaginous cranium.
sp
Cartilage of suspensorium.
sp′
Cartilage under the squamosal.
sp″
Cartilage under the pterygoid.
t1
Anterior
arm of the squamosal.
t2
Middle
t3
Posterior
7. The squamosal bones, ossa
tympanica, Cuvier (Figs. 10, 14t).
Cuvier, oss. foss., V, 2. 390,
Pl. XXIV, Figs. 1, 2 n.—Dugès, temporo-mastoidien, n.
10.—Meckel, Articular part of temporal.—Hallmann and
others, quadrate-bone.—Parker and Bettany, l. c.,
squamosal.
The suspensorium, which forms the articulation between the cranium
and the lower jaw, is T shaped; and consists of cartilage covered
by bone. Of the three arms of the T the anterior has a free pointed
extremity (Fig. 14t1)
at the postero-lateral margin of the temporo-orbital fossa:
it forms a true processus zygomaticus, and is bound
to the upper jaw by ligaments. In R. temporaria it is
comparatively much shorter than in R. esculenta. The posterior upper arm
(t2) articulates with the prootic bone: the third
or lower arm (t3), supported by a cartilage30, runs
backwards and downwards to unite with the side of the broad hinder
extremity of the quadrato-jugal bone.
The cartilaginous basis30
of the suspensorium (Fig. 17 sp, sp′) is a direct
continuation of the cartilaginous basis of the cranium, and proceeds
from it to the outer extremity of the prootic; from this point the
cartilage runs backwards and divides into two branches; of these,
one (sp′) retains the original course backwards and outwards
towards the articulation of the lower jaw, and in conjunction with the
quadrato-jugal (j) forms this joint. The other (sp″) is
directed forwards along the anterior arm of the pterygoid bone; it
widens in front (sn), and becomes directly continuous with the
cartilaginous strut described above as projecting from the hinder part
of the cartilaginous olfactory capsule.
Dugès, tympano-malléal, n. 11.—Cuvier, l. c., p. 399, Pl. XXIV, Figs. 1
2 o.—Hallmann, quadrato-jugal bone, l. c., p. 39.—Parker and
Bettany, l. c., quadrato-jugal.
This is a small process of bone, likened by Dugès to a comma,
which rests by its posterior broader extremity on the cartilage of
the mandibular arch30,
and forms with it a portion of the articular head for the lower jaw.
The anterior extremity is pointed, directed forwards, and attached by
ligament to the maxillary bone.
Cuvier, l. c., p. 389, Pl. XXIV,
Figs. 1, 2 m m.—Dugès, n. 9.—Parker and Bettany,
l. c., pterygoid bones.
Fig. 18.
Origin of the suspensory cartilage (sp) from the skull,
with attachment of the pterygoid; front view. Cartilage shown by
stippling.
cpt
Cartilaginous epiphyses of the pterygoid bone, from the cartilaginous suspensorium.
j
Quadrato-jugal bone.
pt
Pterygoid bone.
sp
Origin of suspensorial cartilage from the skull.
sp′
Hinder arm of same.
sp″
Anterior arm of same.
These bones, shaped like the Greek letter λ, possess each three
arms: of these the middle one is attached to the under surface of
the prootic bone by a cartilaginous process (Fig. 18 sp); the
hinder grooved arm lies upon the under surface of the cartilaginous
suspensorial arch (Fig. 18 sp′); and the anterior arm
(pt) runs forwards along the inner border of the anterior ramus
of the suspensorium (sp″), in contact with the maxillary,
palatine, and nasal bones.
The cartilage just mentioned, by means of which the middle arm of
the pterygoid is connected with the cranium (compare Fig. 18), proceeds
from the cranial origin of the cartilaginous arch (sp), turns
downwards and then forms a sort of articular head (cpt), which
is articulated to an oval flat elevation of the prootic cartilage by a movable joint. Externally
the articular head curves somewhat abruptly into the bony substance
(Fig. 18 pt) of the pterygoid bone.
Fig. 19.
Cartilaginous skull of Rana esculenta, from below, twice
natural size. Cartilage shown by stippling.
c
Cartilage of prootic.
e
Sphenethmoid.
fp
Fronto-parietal.
i
Premaxillary.
j
Quadrato-jugal.
m
Maxillary.
n, sn
Cartilaginous nasal skeleton.
n′, n″, n‴, n⁗
Processes of nasal cartilage.
o
Exoccipital.
p
Prootic.
pl
Palatine.
pt
Pterygoid.
pt′
Articular surface for pterygoid.
r
Optic foramen.
r′
Foramen for N. abducens.
s
Parasphenoid.
s′
Cartilaginous cranium.
sp
Cartilage of suspensorium.
sp′
Cartilage under squamosal.
sp″
Cartilage under pterygoid.
v
Vomer.
10. The maxillary bones, ossa
maxillaria superiora, Cuvier (Figs. 10,
11, 17, 19 m).
Cuvier, l. c., p. 389, Pl. XXIV, Figs. 1, 2 k k.—Dugès,
n. 4, maxillo-jugal.—Parker
and Bettany, l. c., maxillary bones.
These are elongated, curved bones, narrower behind, broader in
front, and forming with the quadrato-jugals the bony support of the
face. The superior surface is convex and directed outwards, the
inferior surface is grooved and bears teeth along the outer edge of
this groove. From the upper and inner border of the anterior half
of this bone a process (processus frontalis) passes upwards,
which articulates with the nasal bone. The anterior extremity of the
bone articulates with the premaxillary bone, the posterior with the
quadrato-jugal.
The maxillary bone articulates at its anterior end (Fig. 19
n″) with a process of the cartilaginous capsule of the
nose. The broad plate of cartilage (Fig. 19 n), under cover of the processus
frontalis, connects the hindermost transverse portion of the nasal
cartilage with the cartilage which runs forwards from the suspensorium
upon the anterior arm of the pterygoid.
11. The nasal bones, ossa
fronto-nasalia, Dugès (Figs. 10, 17fn).
Cuvier, frontale anterius, l. c., h.—Dugès, n. 2.—Meckel, nasal bone.—Parker
and Bettany, l. c., nasal bones.
These flat, triangular bones, which rest upon the nasal
cartilages (n), assist to bound the orbital cavities in
front, and are connected by their external angles with the maxillary
bone on either side31.
Cuvier, l. c., p. 388, Pl. XXIV, Figs. 1, 2 f f.—Dugès, n. 3.—Parker and
Bettany, l. c., premaxillary bones.
These two bones are united in the middle line: each consists of
a tooth-supporting portion, which completes the maxillary arch, and
an ascending process, to the apex of which the nasal cartilage is
articulated by a movable joint (an). As muscles are attached to
this process, it becomes a lever, by which movements are effected.
Fig. 20.
Skull of Rana esculenta, seen from below, twice
natural size.
c
Cartilaginous wall of skull.
e
Sphenethmoid.
e′
Cartilaginous nasal skeleton.
h′
Stylo-hyoid.
i
Premaxillary.
m
Maxillary.
m′
Quadrate tract.
o
Exoccipital.
p
Prootic.
p′
Anterior arm of prootic.
p″
Trigeminal foramen.
pl
Palatine.
pt
Anterior arm of pterygoid.
pt′
Posterior arm of pterygoid.
s
Parasphenoid.
v
Vomer.
13. The palatine bones,
ossa palatina (Figs. 19, 20 pl).
Cuvier, l. c., p. 389, Pl. XXIV,
Figs. 1, 2 i i.—Dugès, n. 7.—Parker
and Bettany, l. c., palatine
bones.
Are two transverse bony bars, situated under the anterior portion of
the sphenethmoid bone on either side: each extends outwards from the
apex of the parasphenoid to the maxillary bone, where this gives off
its ascending process to the nasal bone.
Cuvier, l.c., p. 389, Pl. XXIV, Figs. 1, 2 l l.—Dugès, n. 6.—Parker
and Bettany, l.c., vomer.
A pair of flat bones, placed horizontally on the under surface of
the cartilaginous nasal capsule in the triangular space between the
palatine bone and the anterior portion of the arch of the jaw. They
limit the outer border of the floor of this capsule, which lies in
a groove on the dorsal surface of the bone. The outer border of
each bone has three processes, and between them two notches; the
hinder of these notches bounding the posterior nares. The inner
borders of the two bones touch, and the under surface of each bears
a transverse row of small, pointed teeth.
15. The mandible, maxilla
inferior (Fig. 21).
Cuvier, l.c., p. 398, Pl. XXIV, Figs. 1, 2 rst.—Dugès, n. 16, 17, 18, 19.—Parker
and Bettany, l.c., mandibular arch.
Fig. 21.
A
Mandible of Rana esculenta, from above, nat. size.
B
External view of left side,
twice nat. size.
C
Angulosplenial,
1.
Angulosplenial.
2.
Dentary.
3.
Mentomeckelian.
4, 4′
Meckel’s cartilage.
a.
Rudimentary processus coronoideus.
b.
Groove for Meckel’s cartilage.
The mandible consists of two bony arches united by ligament in
the middle line, and each formed of four pieces. These are, (1)
the angulosplenial, a strong, bony piece (Fig. 21 C,
B1, A1), which forms the inferior and internal part
of the lower jaw; below, it extends posteriorly, as far as the
articulation; in front, it is attached to the dentary. In the greater
part of its length it has a groove directed upwards and outwards
(C, b), and above has a process which represents the
processus coronoideus: (2) the dentary (A2,
B2), a bony lamella which rests on the outer surface of the anterior half of the
angulosplenial, and articulates in front with Meckel‘s
cartilage; it is a thin, flat lamella of bone; (3) in the groove
of the angulosplenial is found a cartilage occupying its entire length
(A4, B4), Meckel’s cartilage; it is
broader behind, and here forms the articular fossa of the lower jaw;
anteriorly it is covered by the dentary, and articulates with the (4)
mentomeckelian (A3, B3) at its anterior end,
which is bound to its fellow of the opposite side by ligaments, and
unites the two halves of the lower jaw.
The upper part of Meckel’s cartilage, which forms the joint with
the suspensorium, must be regarded as the articulare; to this
also belongs the anterior, ossified portion of the mentomeckelian32;
the dentary, which covers Meckel’s cartilage, must represent
the os dentale33; the first and largest bone, the
angulosplenial, which lies on the inner side of the cartilage, must be
considered as the os operculo-angulare, Dugès, for it contains
the elements of these bones.
Fig. 22.
Hyoid of Rana esculenta,
twice nat. size.
H
Body; h h′ processes.
H′
Anterior horn.
H″
Posterior horn.
16. The hyoid bone, os hyoideum (Fig. 22).
Parker and Bettany, l.c., hyoid.
This consists of a broad, thin, cartilaginous plate, with processes
passing from it as represented in the figure. We distinguish in
it:—(a) the body (H), somewhat oblong, and wider in front
than behind. From the anterior angles there projects on either side a
blunt rounded process (h); from either posterior angle a more
pointed process (h′). (b) The anterior cornua (H′)
(cornua styloidea) project from the anterior border of the body,
first in a forward direction, then in a curve backwards and upwards
(compare Fig. 12), to unite with the cartilage of the prootic bone.
Where the direction of these cornua is changed each sends off
a short blunt process. (c) The posterior cornua (cornua
thyroidea) (H″) are bony rods which run from the hinder
margin of the body, diverge posteriorly, and enclose the larynx.
III. THE STERNUM ( Fig. 24 es , hs ).
Cuvier, l. c., p. 401, Pl. XXIV, Fig. 31e f.—Dugès, n. 27, 28.—Parker
and Bettany, l. c., sternum.
The bones of the sternum are in very close relationship with the
shoulder-girdle, and some difference of opinion exists as to the relations
of the several parts.
Fig. 23.
Omosternum of Rana esculenta, twice nat. size.
a
Anterior,
p
Posterior extremity.
The following parts must be regarded as undoubtedly
belonging to the sternum:—
1. An anterior part, consisting of a bony and a cartilaginous
portion.
a. The omosternum (Figs. 23, 24 e.s.) is a bony
rod, wider behind, narrower in front, and supports
b. The episternum (Fig. 24 es′), a semicircular
plate of calcified cartilage, with a thin free border
of unchanged hyaline cartilage.
2. A posterior part, which also consists of a bony
and a cartilaginous portion.
a. The sternum proper (Fig. 24 h.s.), a rod of
cartilage ensheathed in bone, broader in front and narrower behind. To
its posterior extremity is attached
b. The cartilaginous xiphisternum (Fig. 24
hs′), a plate, the shape of which is best understood by
referring to Fig. 24, and the structure of which is similar to that of
the episternum.
3. The epicoracoids34 lie between the episternum
and the sternum proper: they are a pair of narrow cartilages, closely
applied to each other and placed between the ventral ends of the
precoracoids and coracoids, see p. 40.
Fig. 24.
Shoulder-girdle and sternum of Rana esculenta, twice nat. size.
The scapula and suprascapula are turned outwards.
c.
Connecting cartilage.
hs.
Sternum proper.
cl.
Clavicles and precoracoids.
hs′
Xiphisternum.
co
Coracoid.
o
Bone.
es.
Omosternum.
o′
Calcified cartilage.
es′
Episternum.
sc.
Scapula.
h
Hyaline cartilage.
sc′
Suprascapula.
IV. THE BONES OF THE ANTERIOR EXTREMITY. — A. Bones of the Shoulder-girdle. — B. Bones of the Fore Limb.
The shoulder-girdle of the frog (Fig. 25) consists of four bones,
two in the upper or scapular portion, and two in the lower or
coracoid portion.
Fig. 25.
Shoulder-girdle of the frog in transverse
section, diagrammatic.
c
Connecting cartilage.
c′
Epicoracoids.
cl
Clavicles.
h
Humerus.
s
Scapula.
s′
Suprascapula.
ss
Articulation of these two.
v
Vertebra.
1. The scapular portion. a.
The suprascapula, pars suprascapularis scapulae,
scapula superior s. omolita (Figs. 25 s′, 26, 27).
This forms the upper, thinner portion. It is trapezoid in shape,
its narrowest, thickest, and lowest border articulating with the
scapula. The remaining three borders are free; the posterior and
superior borders are very considerably thinned out, the inferior
surface is curved towards the ventral surface. Only the thin upper
and hinder borders (hh) are of hyaline cartilage; the middle
portion (co) consists of calcified cartilage; the lateral part
(o) and the anterior border (o′) of true bone.
The bony part forms a thin plate striated both radially and concentrically with the margin.
The anterior border (o′) is bent on itself so as to form a
groove (Fig. 27). The dorsal surface of this bony plate is quite
smooth, and covered only by periosteum; the ventral surface, on the
contrary, is for the most part covered by an even layer of calcified
cartilage (Fig. 27 co′). This passes directly into the second
portion of calcified cartilage (co); so that if the whole be
dried, the thin hard lamina of bone can easily be split away from the
underlying parchment-like cartilage. The layer of calcified cartilage
is, however, not so complete that the suprascapula can be said
to consist of calcified cartilage.
Fig. 26.
Suprascapula of Rana esculenta, from above,
twice nat. size.
co
Calcified cartilage.
h
Hyaline cartilage.
o
Bony portion.
o′
Anterior curved border.
Fig. 27.
Suprascapula of Rana esculenta, from below,
twice nat. size.
co
Calcified cartilage.
co′
Layer of calcified cartilage on the under surface of the bone.
h
Hyaline cartilage.
o
Bony portion.
o′
Anterior curved border.
Fig. 28.
Left scapula of Rana esculenta,
from below, twice nat. size.
a
Anterior border.
c.a.
Cavitas articularis.
l
Outer border.
m
Inner border.
p
Posterior border.
Fig. 29.
Scapula seen from behind, twice nat. size.
c.a.
Cav. articularis.
d
Dorsal process.
v
Ventral process.
b. The scapula (Figs. 25s, 28, 29) is a long,
flat, four-cornered plate of compact bone, contracted in the middle,
and wider at either end. From above (Fig. 28 l) it descends to
the shoulder-joint with a slight curvature, with the convexity directed
outwards. The inferior or ventral border (Fig. 28 m), which
assists in the formation of the shoulder-joint, is cleft into two
processes, a ventral and a dorsal. This may be best seen by looking
at the border of the bone from behind or before (as in Fig. 29).
The lower ventral process (Fig. 29 v) may be regarded as the
acromion, or at
least as a rudiment of the acromion, i. e., spina
scapulae. The upper dorsal process evidently represents a
rudimentary processus coracoideus. The anterior border (Fig. 28
a) is free, somewhat sharp, and slightly concave; the posterior
(Fig. 28 p), also concave, is free externally; while internally,
where the division of the ventral border commences, it takes part in
the formation of the articular cavity of the shoulder (Figs. 28 and 29
c.a.).
Articulation with the suprascapula. The scapula consists
of a shell of compact bony tissue and an inner portion of cancellous
tissue; this latter passes, at the boundary between this bone and the
suprascapula, through an intermediate layer of calcified cartilage,
which is directly continuous with the cartilage of the suprascapula.
The compact superficial layer ceases where the calcified cartilage
begins, and the periosteum of the scapula passes directly into the
perichondrium of the suprascapula.
2. The ventral portion of the shoulder-girdle consists of three
parts, which lie one behind the other.
Fig. 30.
Left coracoid, twice nat. size.
a
From below.
b
From behind.
l
Outer extremity.
m
Inner extremity.
Fig. 31.
Clavicle of the left side, twice nat. size.
l
Outer extremity.
m
Inner extremity.
a. The larger and posterior bone, the coracoid
(Figs. 24co, 30), is contracted in the middle, and expanded at
either end, especially at the sternal end. The inner half is flattened
from above downwards; externally it becomes more cylindrical. The
anterior and posterior borders are markedly concave; the outer border
(Fig. 30 l) articulates by means of a cartilage with the
proc. coracoideus of the scapula; the inner border (m)
is separated from its fellow of the opposite side by the epicoracoids.
This inner border is so broad, that it almost touches the inner end of
the clavicle (Fig. 24cl.). A coracoid foramen is thus
formed between the two bones, similar to the foramen ovale of
the pelvis.
Fig. 32.
Right shoulder-girdle of Rana esculenta, from above.
ca
Cav. articularis.
c c
Cartilage.
cl
Clavicle.
co
Coracoid.
sc
Scapula.
sc′
Suprascapula.
b. The small anterior bones of the ventral portion of the
shoulder-girdle (Figs. 24cl., 31), I, like Cuvier and others,
regard as clavicles. Dugès (n. 33) names them ‘acromial.’
Each bone is narrower than the coracoid, smaller internally (m),
broader externally (l), and articulates by this broader end with
the cartilage uniting the
dorsal and ventral portions; the inner extremity rests upon the
epicoracoid. The clavicle is grooved on its superior and posterior
surfaces in almost its whole length; the groove widens externally
(l), and contains
c. The precoracoid (Fig. 34 cl′), a slender
bar of cartilage, connecting the anterior edge of the scapula with the
sternum.
Cartilages of the shoulder-girdle (Figs. 24, 32, 34). A
cartilage (c), described by Dugès as the ‘paraglénal,’ connects
the scapula with the coracoid, and converts the notch between the two
processes (s and v) on the inner border of the scapula
into an aperture opening posteriorly into the glenoid cavity, and
which is filled up by the lining cartilage. This cartilage connects
the two processes with the coracoid; being thicker between this and
the proc. coracoideus, it takes an important share in the
formation of the floor of the glenoid cavity. At the outer extremity
of the clavicle the cartilage projects and is then continued in the
groove on this bone towards
the middle line (Figs. 32, 34), where it widens out, and is united by
its external margin with the sternum, thus forming the precoracoid as
already described, see p. 40. These connections are best seen in young
animals, as is shown in Fig. 34.
Fig. 33
Hinder border of the scapula and coracoid, with the connecting
cartilage and shoulder-joint, twice nat. size.
c
Connecting cartilage.
d
Dorsal process.
co
Coracoid.
sc
Scapula.
v
Ventral process.
Fig. 34.
Clavicular cartilage of a young specimen of Rana esculenta,
enlarged to the adult size.
c
Connecting cartilage.
e
Epicoracoids.
c′
Ligament between the two cartilages.
cl
Clavicle.
cl′
Clavicle and precoracoid.
co
Coracoid.
co′
Cartilage of same.
es
Omosternum.
hs
Sternum proper.
The clavicle (cl) is of ossifying cartilage; the cartilage
(c), the epicoracoid, is very large, and hyaline, and at
cl runs directly into the epicoracoids, which are here united
mesially by ligament. In the fully developed animal the whole of
the epicoracoid changes to calcified cartilage, as also does the
precoracoid lying in the groove of the clavicle.
1. The arm has but one bone.
Fig. 35.
Humerus of Rana esculenta, female, seen from below.
Fig. 36.
Humerus of Rana esculenta, male, seen from below.
Fig. 37.
Humerus of Rana esculenta, female, outer side.
Figures twice natural size.
c Anterior extremity. c′ Posterior extremity. cd Crista deltoidea. cm Crista medialis. t trochlea.
The humerus, os humeri (Figs. 35, 36, 37). The shaft
of the humerus is, on the whole, cylindrical, the middle part being
the narrowest; its dorsal surface is slightly concave, the ventral
surface convex. In the upper half the cylindrical form is indistinct,
from the presence of a well-marked crest (crista deltoidea)
upon the under or ventral surface. The hinder half of the bone has
very different shapes in
the two sexes: in the female it remains cylindrical as far as the
elbow-joint; in the male, on the posterior surface, where the crista
deltoidea ceases, a marked ridge (crista medialis) arises,
which gradually winds inwards and terminates at the inner condyle. This
sexual difference is found in all the three species described in the
Introduction, and it would seem that this ridge increases in height
during the pairing season. The muscle which arises from this process is
the flexor carpi radialis (Fig. 74Fc), and it attains,
in the males, a very large size at the same period; indeed, it is at
its origin twice as broad as in the female. Dugès35 has incorrectly stated
that this crista is a peculiarity of Rana temporaria,
and is wanting in Rana esculenta. Pouchet36 first observed that it was
a sexual distinction.
The anterior articular extremity presents a rounded head, which
is somewhat flattened externally. The inferior ventral border is
sharp, and developed into the above-mentioned bony crest (crista
deltoidea); the free border is arched and curved outwards. Above,
on the outer surface of the head, is found an eminence which may be
a rudimentary tuberc. maius. The inner half of the head is
articular.
The posterior articular extremity consists of a rounded head
(c′), attached to the posterior extremity of the shaft; internal
to this is a small trochlea (t), placed upon the inner
condyle. The external condyle is but small. The head is embraced by
these condyles. Upon the under surface, above the head, is the fossa
cubitalis anterior. The structure of the two articular extremities
of the humerus differs; the upper, as in long bones generally (see
page 16), consists of hyaline cartilage surrounded by calcified
cartilage, which again is covered by hyaline articular cartilage;
the lower extremity is composed of spongy bone, with roundish marrow
spaces, and for the most part covered by a layer of calcified
cartilage.
The shoulder-joint. The socket is formed by the posterior
border of the scapula, by both the processes of that bone, the outer
portion of the coracoid, and besides these by cartilage, which forms
the articular surface already described (Fig. 33). In the macerated
bone the floor of the socket opens dorsally into a fossa between the
processes of the scapula (Fig. 32). This opening, in the natural
condition, is closed by synovial membrane only; the cartilage covering
the rest of the space being absent (the sac may easily be inflated, either from the joint
itself or through the opening). The margin of the socket consists of
a labrum, partly fibrous and partly cartilaginous, which is
easily removed entire. The capsule, which is attached beneath the
caput humeri, arises from this. From the articular cartilage of
the ventral margin of the socket, and from the adjacent part of the
scapula, proceeds a strong band, which is inserted into the flattened
outer surface of the head.
2. The forearm.
Fig. 38.
Radio-ulnar of the right side of
Rana esculenta, twice nat. size.
r
Radius.
r′
Capitulum radii.
u
Ulna.
u′
Olecranon.
The radio-ulnar, os antibrachii (Fig. 38). The two
bony elements of the forearm are fused into one, which, however,
shows traces of its compound character. Of these two bones, that
which forms the inferior (in man anterior) border is the radius, the
other the ulna. The relative positions of the bony elements are such
that they appear to be in a state of semi-pronation; by this the
thumb-border of the arm is directed downwards (in man forwards). The
two bones so united form a flattened, tube-like bone, the grooved
surfaces of which are directed inwards and outwards respectively; the
borders being dorsal and ventral. The shaft of the bone is narrower
above, becoming gradually wider below. In the upper half, the groove
showing the line of junction of the two bony elements is scarcely
visible, and it appears as though this part consisted of ulna alone,
the radius not reaching so far; below the groove is more marked. The
upper articular extremity appears to consist of an olecranon
(Fig. 38 u′) and a processus coronoideus (r′),
between which is the greater sigmoid cavity (cavitas sigmoidea
major) for the processus cubitalis humeri. A more careful
examination shows this to be incorrect: the portion of the concave
articular surface, which lies in the immediate neighbourhood of the
ventral border, undoubtedly represents the articular surface of the
capitulum radii, and the upper portion of the articular surface
(at u′) belongs to the ulna and articulates with the
trochlea (Figs. 35, 36t) of the humerus. The inner
border of the upper extremity of the bone articulates with the groove
t of the humerus. The inferior extremity forms one of the usual
cartilaginous epiphyses, enclosing the two bones. That part of the
extremity corresponding with the radius is triangular and convex, it
is prolonged upon the inner or under surface of the bone by means
of a process; the ulnar
portion of the bone forms a capitulum. The structure of the
inferior extremity is that of epiphyses in general, except that there
are two medullary cavities in a common sheath of calcified cartilage;
the anterior head consists of cancellous tissue, with a covering of
calcified cartilage.
a. Bones of the wrist, ossa carpi. These are
arranged in two rows, proximal and distal. The proximal or anterior row
has three bones, viz.:—
1. Os lunatum, the middle bone (Fig. 39 l), Dugès,
n. 38, articulates with the radial part of the articular surface of
the radio-ulnar by a concave surface; with the large bone of the
second row (hc) it articulates by means of a rounded head; and
with the two other bones of this row, os naviculare (n)
and pyramidale (p), with the former by a saddle-shaped
surface, with the latter chiefly by ligament. The bone is irregularly
cuboid; the dorsal and palmar surfaces are non-articular. With Dugès
I regard this bone as os lunatum; Mertens37 regards it as os
naviculare.
Fig. 39.
Bones of the forearm and hand of Rana esculenta, right side,
dorsum, twice nat. size.
a
Os antibrachii.
hc
Os capitato-hamatum.
l
Os lunatum.
m
Ossa metacarpi.
n
Os naviculare.
p
Os pyramidale.
r
Radial portion of the radio-ulnar.
t
Os multangulum majus or trapezium.
t′
Os multangulum minus or trapezoides.
u
Ulnar portion of the radio-ulnar.
I‑V
First to fifth fingers, the fifth only of os metacarpi, the second and third of two, fourth and fifth of three phalanges.
2. Os pyramidale (Fig. 39 p), Dugès, n. 37,
articulates with the ulnar part of the posterior articular extremity
of the radio-ulnar. Anteriorly the bone has a facet which receives
the capitulum ulnae, and alongside this a small flat surface
which articulates with the radius. Posteriorly, opposite to the
second row, it presents a long raised articular surface, extending
from the dorsum to the palmar surface; and on the palmar aspect of the bone is a ridge running
from before backwards. Mertens names this bone os lunatum.
3. Os naviculare (Fig. 39 n), Dugès, n. 39. The
third bone of the first row does not articulate with the bones of the
forearm. It is connected with the os lunatum by a saddle-shaped
surface, posteriorly with the os capitatum by means of a
concave surface. On the inner surface is a small concave articular
facet for the os multangulum minus or trapezoides
(Fig. 39 t′). The convex palmar surface of the bone articulates
with the os multangulum majus (t); the radial side is
non-articular, and with the os lunatum forms a ridge directed
forwards. Mertens names this bone os triquetrum. It is evident,
however, that if the arrangement in man obtains as a standard, the
nomenclature of Dugès, which I have here used, is correct; but the
os naviculare is no longer in contact with the articular surface
of the os antibrachii.
The second or distal row also consists of three bones:—
4. Os capitato-hamatum (Fig. 39 hc), Dugès, n. 40,
41, 42, corresponds with the os capitatum and hamatum38, which
are here fused together. It is the largest bone, and articulates with
all three bones of the first row; it is crescentic, with the concavity
directed posteriorly, and on the convex surface has three facets for
the three outer ossa metacarpi.
5. Os multangulum minus, s. trapezoides (Fig. 39
t′), Dugès, n. 43, is a small bone lying next to the foregoing;
it articulates with the os metacarpi II, and anteriorly
with the os naviculare. Dugès considers it to be the os
trapezium.
6. Os multangulum majus, s. trapezium (Fig. 39
t), is a small bone, which is placed on the convex palmar
auricular side of the os naviculare. Dugès regards this bone as
os metacarpi pollicis (Dugès, n. 44), Mertens as multangulum
minus. It appears to me that the interpretation here given is
justified, because it articulates with the rudiment of the thumb, and
as it possesses no resemblance to a long bone it cannot be regarded as
an os metacarpi.
Structure of the carpal bones. All the carpal bones consist
of calcified cartilage, though variations due to age occur in the
amount of the deposit.
Wrist joint. As stated above, the os lunatum and
os pyramidale are articulated with the forearm. In addition to
the capsules uniting the parts, there are strengthening ligaments,
two of which require special mention. One of these arises from the
palmar surface of the
posterior extremity of the ulna, and passes to the sharp palmar ridge
of the os pyramidale, where it is attached, and is inserted
into the os capitato-hamatum; the second ligament passes in
a similar manner on the palmar surface from the radius to the os
naviculare. Between the two ligaments there is on the volar surface
a deep excavation.
Fig. 40.
Bones of the forearm and hand of Rana esculenta, right side,
dorsum, twice nat. size.
a
Radio-ulnar.
hc
Os capitato-hamatum.
l
Os lunatum.
m
Ossa metacarpi.
n
Os naviculare.
p
Os pyramidale.
r
Radial portion of the radio-ulnar.
t
Os multangulum majus or trapezium.
t′
Os multangulum minus or trapezoides.
u
Ulnar portion of the radio-ulnar.
I‑V
First to fifth fingers, the first only of a metacarpal, the second and third of two, fourth and fifth of three phalanges.
Movements of the hand. The two bones of the forearm being
firmly united, pronation and supination, as in man, are impossible.
The normal position, as already remarked (see radio-ulnar), is that
of semi-pronation (compare Figs. 2 and 74). If the animal be in its
natural posture, with the arm bent at the elbow (Fig. 1) it can touch
the ground with the ulnar border only; but when the whole surface of
the hand rests upon the ground, the action is brought about as follows:
the plane of the carpus is in extension parallel with that of the
forearm; in flexion, almost at right-angles with that plane (Fig. 74)
The os lunatum glides on the prolongation of the articular
surface on the inner palmar surface of the radius, while the os
pyramidale is held firmly by the ligament just described. The hand
follows the movement of the os lunatum, and at the same time the
three outer ossa metacarpi gliding with it inwards, the fingers
of the hand turn inwards.
b. The Bones of the metacarpus, ossa metacarpi
(Fig. 40 m). Of these there are five: the second to
the fifth are of about equal length; the first, forming the
rudiment of the thumb, hidden beneath the skin, is much shorter. This
metacarpal bone of the thumb is regarded by Dugès and others
as the first phalanx. My reason for describing it as a metacarpal
has already been given.
This bone also presents differences in the two sexes. Meckel’s39
observation that it exists only in the male is incorrect; it is a
large, broad and sickle-shaped mass of calcified cartilage or even
true bone, while in the female it is simply a small cartilaginous
rod; as this almost entirely disappears in dried specimens, Meckel’s
statement is explained. The second finger has in the frog
assumed the functions of the thumb, and, in the males, in the breeding
season swells and undergoes an essential alteration of structure. The
metacarpal of this finger also displays differences in the sexes, being
in the male stronger, broader, and on the inner side provided with a
spine-like prolongation, for the tendon of the abductor digiti II
(pollicis) longus, which attains an unusual development during the
breeding season. The remaining metacarpal bones, the third,
fourth, and fifth, are of similar form, the last being
provided with a tubercle. The anterior articular extremities are rather
broad and concave, and the posterior have rounded heads.
c. The phalanges, phalanges digitorum. The
hand has four fingers and the rudiment of a fifth, which latter is
completely hidden under the skin, and as already explained, consists
of a metacarpal only. Of the four fingers, the fourth is the longest,
the third the shortest, the second and fifth of intermediate and about
equal length; the fourth and fifth fingers have each three phalanges,
the second and third have each two. Their shape is not unlike that of
the human phalanges.
V. THE BONES OF THE HINDER EXTREMITY. — A. Bones of the Pelvic Girdle (Fig. 41). — B. Bones of the Hind-Limb.
Fig 41.
Pelvis of Rana esculenta, from below, nat. size.
a
Acetabulum.
il
Iliac bone.
p
Pubic bone.
The pelvis has a characteristic V-shape, the pubic and
ischiatic bones of the two sides together forming a vertical plate
(a p), which divides anteriorly into the two iliac bones
(il). The pubic and ischiatic bones being united by their median
surfaces, one can only speak of the pelvic cavity as the space between
the two ilia.
Fig. 42.
Pelvis of Rana esculenta, left side, twice nat. size.
a
Acetabulum.
d
Upper sharp border.
il
Iliac bone.
il′
Superior process.
is
Ischium.
is′
Tuber ischii.
p
Os pubis.
s
Inferior process of the ilium.
v
Lower border of same.
1. The ilia, ossa ilii
(Fig. 42 il). In these a broader part or body can be distinguished, which takes part
in the formation of the acetabulum (a). The hinder and
broadest part of the bone is joined to the corresponding portion of its
fellow by ligament; anteriorly the two diverge, bounding a cone-shaped
cavity, the pelvis. The suture, by which the body of the iliac bone is
united with the ischiatic and pubic bones, runs from above downwards
through the middle of the acetabulum (Fig. 42, from p
through the acetabulum to is). Inferiorly and in front
the united ilia form a prominence (s), which represents
the symphysis oss. pub. of man. The expanded portions of the
ilium rest directly over the articular cavity by means of a somewhat
constricted part or root. The ala is a sabre-like bone, with the
sharper, more convex border directed upwards; the more concave, thicker
border downwards. The two surfaces, of which the inner is grooved, are
directed respectively inwards and outwards. The broader part of the
blade springs directly from the neck or root (at il′), and at
this end of the sharp convex border is a process, process. sup.,
from which the tendon of the m. vastus externus arises. The
anterior end of the blade is a hollow cylinder, containing cartilage,
movably articulated to the transverse process of the last vertebra or
sacrum.
Fig. 43.
Horizontal section through the iliac, pubic, and ischiatic bones.
a
Acetabulum.
il
Ilium.
is
Ischium.
p
Pubic cartilage.
s
Ligaments which unite the bones of opposite sides.
2. The ischia, ossa ischii
(is), are irregular, four-cornered plates of bone, united
together by the whole extent of their inner surfaces. The vertical
plate formed by the union of the two bones takes only a very small
share in the formation of the articular cavity. Above, it has a
somewhat sharp border, continued with the ilium into a process (is′) corresponding with
the united tubera ischii; the hinder border, which is united
below with the pubic cartilage, is curved.
3. The pubes, os pubis (Figs. 41,
42, 43 p). Ossified pubic bones do not exist; even in old
animals they are composed of calcified cartilage. Each is a triangular
cartilage, wedged between the ilium and ischium, but also taking part
in the formation of the acetabulum. The pubes of opposite sides
are, as shown in section in Fig. 43, united by ligaments in the median
plane.
1. The thigh.
Fig. 44.
Femur of Rana esculenta, right side, twice nat. size.
a
Anterior extremity.
p
Posterior extremity.
The femur, os femoris (Fig. 44). The shaft is
cylindrical, with a slight double or S-shaped curve. In the anterior
portion the convexity is directed upwards, in the two hinder thirds
downwards. Towards the hinder extremity it is flattened from above
downwards. The anterior extremity is a rounded articular head placed
directly on the shaft like that of the humerus. This head is
somewhat flattened from side to side; and in structure resembles that
of the humerus. The inferior extremity is rounded below, but flattened
above (towards the hollow of the knee) and behind.
Hip-joint. The articular cavity is deepened by a fibrous
ring, labrum cartilagineum, which fits closely upon the caput
femoris; from this labrum the joint-capsule arises, to be
inserted behind the head; close to the lower border of the cavity a
ligamentum teres arises, which is inserted into the caput
femoris.
2. The leg.
Fig. 45.
Tibio-fibula of Rana esculenta, twice nat. size, seen from
below.
a a
Grooves.
f
Foramen nutritium.
t
Anterior articular extremity.
t′
Posterior articular extremity.
t″
Groove on malleolus internus for tendon of m. tibialis posticus.
Tibio-fibula, os cruris (Fig. 45). This consists
of a single bone, the os cruris; it is often called the
tibia, but presents, however, distinct indications of being
formed of two bones, the tibia and fibula. The shaft is
not quite straight; it is thinner in the middle and flattened from above downwards. On the
upper as also on the lower surface of the bone is a groove, passing
from the middle towards each extremity; this deepens as it proceeds,
and is an indication of the compound nature of the bone. In the middle
of each surface of the bone is the opening of a canal, through which a
bristle may be passed: the canal has bony walls. The medullary cavity
is, for the most part, double, being single only in the middle. The
anterior extremity is articular, and presents a median groove, which
is prolonged on to the under surface. The posterior extremity forms a
transverse condyle, which has at its inner part a notch for the tendon
of the m. tibialis posticus.
Fig. 46.
Section of the tibio-fibula through the under extremity.
a
Cartilaginous epiphysis.
m
Marrow cavities.
t″
Connecting mass.
t t′
The two cylinders of bone.
The knee-joint consists of a capsule strengthened by the
insertions of numerous tendons. Within this the articular surfaces
of the femur and tibio-fibula are connected by means of
fibro-elastic bands, which spring from the latter bone and cross each
other, thus representing the lig. cruciata. The articular
surfaces are moreover deepened by loose semilunar cartilages,
corresponding with the inter-articular cartilages of the knee-joint
of man. In addition, on either side of the joint, are found auxiliary
ligaments.
3. The foot (Fig. 47).
a. The ankle, ossa tarsi. The tarsus
consists of two rows of bones.
α. The proximal row consists of two long tubular bones
(Fig. 47 ac), which are parallel to each other, and
undoubtedly correspond with the astragalus (talus)
and calcaneum. The bones are separated in the middle,
but approach each other at either end. The outer of these bones
(c) I have named calcaneum, following Cuvier and Dugès; the
inner, astragalus (a). The two bones are surrounded and enclosed at their anterior
and posterior extremities in a common epiphysis of calcified
cartilage, which has the usual structure found elsewhere. The
ligamentum calcanei, which will be described below (see
Muscles of Foot, Fig. 88lc), may be regarded as an unattached
process of the heel40.
β. The distal row of the tarsals are all composed of
calcified cartilage. They are:—
Fig. 47.
Right foot of Rana esculenta, palmar surface, twice nat. size.
a
Astragalus.
ac
Common epiphysis.
c
Calcaneum.
cb
Os cuboideum.
h
First, h′ second cartilage of supplemental toe.
m
Ossa metacarpi.
n
Os naviculare.
I to V
First to fifth toe.
1. Os cuboideum (Fig. 47 cb), a flat plate of
cartilage, concave in front, convex behind, placed between the common
epiphysis of the astragalus and calcaneum (ac) and the ossa
metatarsi II and III. This corresponds, as Dugès suggests,
with the separated os cuboideum and cuneiforme III of
other batrachians, e. g. Bufo.
2. On the inner side of the above, between the astragalus
and metatarsus I lies a small body, concave in front, convex
behind, which we may regard, with Dugès, as the analogue of the os
naviculare (Fig. 47 n).
3. This latter supports a cartilage which forms a projection
on the inner border, covered with skin. This consists of
closely-united pieces, a small round, basal piece (h), and a flattened beak-like
piece (h′). Dugès considers these pieces as the first and
second ossa cuneiformia; I rather incline to Meckel’s opinion
that they represent a rudimentary hallux, the first being the os
metatarsi, the second a phalanx. Both are composed of
calcified cartilage; in R. temporaria the lime-deposit seems to
be less than in R. oxyrhinus and R. esculenta, and the
projection consequently softer41.
b. The metatarsal bones, ossa metatarsi
(Fig. 47, mI-V). The five ossa metatarsi
are long, thin tubular bones, the anterior articular extremities of
which are broader above and narrow below, hence are wedge-shaped,
and anteriorly present flat surfaces for articulation with the
tarsus. The shafts are long and thin; the posterior extremities
have rounded heads. The comparative length of these is as follows: the
fourth is the longest, then come the third, fifth, second, and first in
order. In structure they resemble other tubular bones.
c. The phalanges, phalanges digitorum
(Fig. 47). The total lengths of the separate toes correspond with that
of the ossa metatarsi, but the distinctive differences are
increased, partly by the difference in number and partly by the varying
lengths of the phalanges. The first and second toes have each only
two phalanges, the third and fifth have each three, the fourth, which
is the longest, has four. The terminal phalanges are somewhat hooked
towards the plantar surface.
SECTION II. THE MUSCLES.
THE MUSCLES.
LITERATURE.
v. Altena, see p. 13.
Anonymous, Ueber das Schultergerüst der Schildkröten mit den daran sitzenden
Muskeln. Isis, 1827. (Contains remarks on the shoulder-muscles of the frog.)
Carus, C. G. (1) Lehrbuch der vergleichenden Zootomie. 2nd Edit. Leipzig, 1834.
(2) Erläuterungstafeln zur vergleichenden Anatomie. 1 Part. 1826. (Muscles
of the Leg.)
Chappuis, Morphologische Stellung der kleinen hintern Kopfmuskeln. Zeit. f. Anat.
u. Entwickl. 1876. Vol. II, pages 287–297.
Cuvier, Leçons d’anatomie comparée. Paris, 1835. Vols. I, II.
Dugès, Recherches anatomiques et physiologiques sur la déglutition dans les
Reptiles. Ext. des Annales des Sciences naturelles. Paris, 1827.
Dugès, Leçons d’anatomie comparée. Paris, 1835.
Duméril and Bibron, Erpétologie générale ou Histoire complète des Reptiles. 1836.
Führbringer, Zur vergleichenden Anatomie d. Schultermuskeln. Jenaische Zeitschr.
1873. Vol. VII.
Klein, Beiträge zur Anatomie der ungeschwänzten Batrachier (Rana temporaria, L.):
in Jahrshefte des Vereins für vaterländische Naturkunde in Würtemburg.
6 Jahrgang. 1850. Page 1.
Kuhl, Beiträge zur Zoologie der Rana esculenta: in Beitr. z. Zool. Frankfurt, a. M.
1820. Page 115.
de Mann, Vergelykende myologische en neurologische studien over Amphibien en
Vogels. Acad. Proefschrift. 1873.
de Mann, Myologie comparée de l’extrémité post. chez les amphibiens. Niederl.
arch. f. Zool. 1874. Vol. II.
Marshall, The Frog. London and Manchester. 2nd Edit. 1885. Pages 60–71.
Martin St. Ange, Annales des sciences naturelles. Vol. XXIV. 1831. Page 393.
Meckel, System der vergleichenden Anatomie. Halle, 1828. Vols. III and IV.
Pfeiffer, Zur Anatomie des Schultergürtels und der Schultermuskeln bei Säugethieren,
Vögeln und Amphibien. Giessen, 1854.
Rymer Jones, Article ‘Reptiles’ in Todd’s Cyclop. of Anatomy and Physiology.
1847–1852. Vol. IV. Page 263.
Stannius, Handbuch der Anatomie der Wirbelthiere. Vol. II. Zootomie der Amphibien.
Berlin, 1856.
Wagner, Icones Zootomicae. Leipzig, 1841.
Wagner, Lehrbuch der vergleichenden Anatomie. Leipzig, 1834–35.
Zenker, Batrachomyologia. Diss. Jena, 1825.
I. MUSCLES OF THE HEAD. — I. Muscles of the Eye. — II. Muscles of the Face. — III. Muscles of the Lower Jaw. — IV. Muscles of the Hyoid Bone and the Tongue. — II. MUSCLES OF THE TRUNK. — I. Muscles of the Abdomen. — II. Muscles of the Back. — III. MUSCLES OF THE ANTERIOR EXTREMITY. — I. Muscles of the Shoulder-girdle. — II. Muscles of the Fore-limb. — C. Muscles Of the Hand. — IV. MUSCLES OF THE HINDER LIMB. — II. Muscles of the Leg. — III. Muscles of the Foot. — V. MUSCLES OF THE SKIN.
THE MUSCLES.
1.M. rectus inferior (Fig. 48 ri′).
Dugès, post-orbito-sous-oculaire, n. 12.—Zenker, depressor oculi.
Fig. 48.
Eye muscles of Rana esculenta, from below.
On the right side (i. e. in the left eye) the lev. bulbi
(l) is taken away; on the left side it is still present.
l
M. levator bulbi.
l.a
M. lev. anguli scapulae
oi
M. obliquus inferior.
os
M. obliquus superior.
p
M. pterygoideus.
r
M. retractor bulbi.
re
M. rectus externus.
1
First cervical vertebra.
This muscle arises by a very thin, almost thread-like tendon from
the parasphenoid, near the foramen opticum, and becomes rapidly
broader; it lies beneath the tendon of the membrana nictitans
and a part of the m. retractor bulbi: then runs forwards and
outwards to be attached into the lower part of the circumference of the
eyeball.
2.M. rectus externus (Fig. 48 re).
Dugès, post-orbito-ex-oculaire, n. 14.
Arises by a thin, thread-like tendon from the parasphenoid near
the foramen opticum, internal to and a little behind the m.
rectus inferior: it then passes obliquely outwards over the m.
retractor bulbi and the tendon of the membrana nictitans, to
be inserted into the outer and hinder part of the circumference of the
eyeball.
3.M. rectus internus (Fig. 48 ri).
Dugès, post-orbito-in-oculaire, n. 13.
A long, thin muscle, which arises by a thread-like tendon
from the parasphenoid at the inner and hinder angle of the orbit, passes along its
inner wall, and is inserted into the antero-internal part of the
circumference of the eyeball.
4.M. rectus superior (Fig. 49 rs.).
Dugès, post-orbito-sous-oculaire.
Fig. 49.
Eye-muscles of Rana esculenta, from above.
n
Membrana nictitans.
n′
Tendon of membrana nictitans.
p
M. pterygoideus.
rs.
M. rectus superior.
t
M. temporalis.
Arises by a slender tendon from the fronto-parietal bone, widens
rapidly, and runs forwards and outwards to be inserted into the upper
part of the circumference of the bulbus.
5.M. obliquus inferior (Fig. 48 oi).
Dugès, pré-sous-orbito-oculaire.
This muscle arises near the floor of the orbital cavity, at the
inner and anterior angle, from the palatine bone by a thin and long
tendon, runs under Harder’s gland outwards and backwards, and is
inserted, almost at a right angle with the axis of the eye, into the
anterior part of the circumference of the eyeball.
6.M. obliquus superior (Fig. 48 os).
Dugès, pré-sus-orbito-oculaire, n. 7.
The tendon of this small muscle arises from the inner end of the
palatine bone, near the origin of the m. obliquus inferior, runs
upwards, backwards, and outwards, and passes into a flat muscle, which
rapidly becomes broader, and is inserted into the upper surface of the
eyeball.
Fig. 50.
Eye-muscles of Rana esculenta, from below, the m. recti and
obliqui have been removed.
n′
Tendon of membrana nictitans.
r
M. retractor bulbi, lower part.
r′
Second part of same.
7.M. retractor bulbi (Figs. 48 r, 50 r, r′).
Dugès, orbito-post-oculaire or choanide, n. 10.—Zenker,
m. opticus.
This muscle surrounds the optic nerve, and is situated within
the cone formed by the four recti muscles; it consists of three
portions, which take their broad and fleshy (the recti
and obliqui arise by thin tendons) origins from the under
surface of the parasphenoid. The first portion (Fig. 50 r)
arises from the under surface of the parasphenoid, nearly as far
as the middle line, is
broad and fleshy, and covers, from below, the tendon of the rectus
externus, then runs forwards and outwards. The second portion
(r′), which lies over this and the tendon of the m.
rectus externus, has also a broad and fleshy origin, but runs
more directly forwards, slightly crossing the preceding. The third
portion arises above the two others by a strong thin tendon from the
parasphenoid: it runs almost in the direction of the m. rectus
internus, but more directly forwards. The first two portions pass
more to the upper surface of the eyeball, the third more to the under
surface; consequently the whole muscle forms a sheath surrounding the
eyeball. The fibres to the upper surface of the eyeball are inserted
somewhat in front of the equator of the eyeball, those to the under
surface somewhat behind it.
Dugès, fronto-pterygoidien, n. 9.—Klein,
sustentator bulbi.
Fig. 51.
Transverse section through the skull and orbital cavities of Rana
esculenta.
b
Bulb of eye.
c
Skull cavity.
g
Mucous membrane.
l
M. levator bulbi.
m
Upper jaw.
n
Membrana nictitans.
n′
Continuation of same to the lower eyelid.
p
Upper eyelid.
Fig. 52.
M. levator bulbi of Rana esculenta, seen from above;
the eyeball which rests on it has been removed.
d.p
M. depressor palpebrae inferioris.
l
M. levator bulbi.
n
Membrana nictitans.
p
M. pterygoideus.
t
M. temporalis.
There is no bony floor to the orbital cavity, and the oral and
orbital cavities are only separated by soft tissues; these are:—the
mucous membrane of the mouth, a thin fascia, and above this the muscle
under consideration. The fibres of this muscle run from before and
from the inner side obliquely backwards and outwards, below all the
remaining muscles of the eye, with the exception of the origin of
the m. retractor bulbi, and the tendons of the m. obliquus
inferior, and the m. pterygoideus; they arise on the
inner side from the upper and outer border of the fronto-parietal
bone (Fig. 51), also from the transverse portion of the parasphenoid
and pterygoid bones, anteriorly from the sphenethmoid and palatine
bones; they run first downwards, then, in the direction indicated,
underneath the eye; and
are inserted externally by means of tendinous fibres into the superior
border of the upper jaw.
9. From the foregoing muscle certain fibres
pass to the lower eyelid, which may be regarded as a depressor
palpebrae inferioris (Fig. 52 d.p).
Manz42
has described a muscle as depressor palpebrae inferioris which
arises in the neighbourhood of the external angle of the eye, somewhat
behind and below the lower border of the orbit, thence passes obliquely
upwards to be inserted into the lower eyelid. This description is
right as regards the insertion, but needs correction as regards the
origin. The muscle is attached to the orbital border in so far that the
tendinous expansion, into which the levator bulbi passes at its
external border, is attached into the upper jaw; this bundle splits off
from the upper surface of the levator bulbi at its middle, and
runs outwards on the under surface of the eyeball to the hinder part of
the lower eyelid.
Fig. 53.
Eye-muscles of Rana esculenta, from below, the m. recti and
obliqui have been removed.
n′
Tendon of membrana nictitans.
r
M. retractor bulbi, lower part.
r′
Second part of same.
10. Tendon of the membrana nictitans43 (Fig. 53
n′). The pigmented free border of the nictitating membrane
passes, at the inner and outer angles of the eye, into a tendon which
passes for some distance through fibrous tissue, then descends to the
under surface of the eyeball and joins that of the opposite side,
so that the free border of the eyelid, together with this tendon,
form a complete ring. The tendinous part of the ring, which is thin
and thread-like, is found on the under surface of the eyeball, and
lies under the m. retractor bulbi, and is bound to this
muscle by connective tissue. Manz is right in saying that the two
muscles described by Dugès as levatores palpebrae inferiores
(orbito-palpebral anterieur and posterieur, n. 5 and 6) do not exist;
as is also the suggestion that he has confounded the tendon of the
nictitating membrane with these; this is clearly shown in the figure
in Plate VI of Dugès. With regard to the actions of these
eye-muscles, it is plain that the four straight and two oblique muscles rotate the eyeball
about three axes, one the axis of the eye, one vertical, and the third
passing from behind forwards and inwards. The m. retractor pulls
the eyeball into the orbital cavity backwards and downwards, while the
levator raises it.
There is less agreement about the movements of the eyelids, or
rather of the lower eyelid, for the upper has no independent movements.
Dugès (l. c.) says that the two muscles, which he considers to
be levatores palpebrae inferiores, and which, according to him,
are connected with the m. retractor bulbi, draw up the lid as
it is being drawn backwards and downwards by the latter muscle. The
depression of the lid on the relaxation of the retractor and projection
of the eyeball is due simply to elasticity. Manz44, on the contrary, has
shown that the sinking of the eyeball by the contraction of the
retractor must necessarily cause a rising of the nictitating
membrane, as its tendons are attached to that muscle and so must follow
its movements.
The depression of the lower lid occurs simultaneously with the
raising of the eyeball by means of the m. levator bulbi, through
the contraction of the m. depressor palpebrae inferioris, which
proceeds from that muscle; this is easily understood, as they are but
parts of the same muscle.
11.M. intermaxillaris s. dilatator narium (Fig. 54 im).
Dugès, intermaxillaire, n. 1.—Zenker, intermaxillaris medius.
Fig. 54.
Facial muscles of Rana esculenta.
an
Cartilaginous nasal alae.
i′
Vertical process of premaxillary bone.
im
M. intermaxillaris.
ln
M. lateralis narium.
n
Cartilaginous nose capsule.
This small muscle lies in the space between the vertical processes
of the two premaxillary bones, and consists of obliquely-crossing
fibres arising from the one bone and inserted into the opposite one.
It brings together the processes of the intermaxillary bones, so that
their upper extremities approach each other. At the same time, the
cartilaginous nasal coverings or wings (an) diverge and the
nares expand; hence we may regard this muscle as corresponding to a
dilatator narium.
12.M. lateralis narium (Ecker), (Fig. 54 ln).
Zenker, m. intermaxillaris lateralis.—Klein, m. nasalis inferior.—Dugès,
sus-maxillo-pré-nasal, n. 2.
This small muscle occupies the space between the anterior portion
of the maxillary bone and the ascending process of the premaxillary
bone. It arises from the maxillary, and ascends obliquely forwards
to be inserted into the outer border of the ascending process of the
premaxillary bone. It is antagonistic to the foregoing.
A third muscle is described by Dugès as
sus-maxillo-post-nasal, n. 3 (nasalis externus, Klein);
according to him it passes from the proc. nasalis of the
maxillary bone to the outer border of the nasal opening, which it
widens. According to Klein (l. c., p. 9), this muscle in R.
temporaria runs to the upper border of the maxillary bone beneath
the lower eyelid, and is long and narrow. I have, however, never been
able to find muscular fibre in this situation.
Fig. 55.
Muscles of the back and shoulder.
c
M. cucullaris.
dm,dm
M. depressor maxillae, arising from the fascia dorsalis.
On the right side it is cut through and reflected.
Cuvier, l. c., II, 141, digastricus.—Dugès,
sus-occipitodorso-angulaire, 32.
This is a strong, triangular muscle, wide above, pointed below. It
is placed between the head and the shoulder-blade. It arises in two
portions; the greater, from the fascia dorsalis (fd),
covers the scapula, and passes inwards and backwards over the muscles
of the back; anteriorly it passes over the m. temporalis and
is attached to the fronto-parietal and squamosal, being continued to
the fascia of the upper eyelid. The second part is smaller, and arises
by fleshy fibres from the postero-superior arm of the squamosal, and from the posterior
and inferior border of the cartilaginous tympanic ring. The two
parts unite and are inserted into the hinder angle of the lower jaw.
Cuvier correctly considers that only the anterior portion corresponds
to the digastricus, the posterior answering to the m.
cervico-maxillaris of snakes. It draws the lower jaw down and opens
the mouth.
Cuvier, m. temporalis, I, l. c., p. 138.—Dugès, sous-rupéo-temporo-coronoidien.
This muscle, together with the M. pterygoideus, occupies the
space between the prootic and the eyeball; it arises by the greater
part of its fibres from the upper surface of the prootic; it passes,
narrowing, beneath the anterior arm of the squamosal, then over the
pterygoid bone, between this and the maxillary and quadrato-jugal,
receiving on the way other fibres which arise from the anterior
border of the inferior arm of the squamosal and from the anterior
circumference of the tympanic ring. The collected fibres end in a
broad, flat tendon, which is inserted into the inner surface of the
so-called proc. coronoideus.
Cuvier, m. temporalis, II, l. c.—Zenker, m. massetericus, l. c., p. 25.—Dugès,
pré-rupéo-pterygo-maxillaire, 31.
This is partly covered by the foregoing, and lies between it
and the eyeball. It arises at the inner wall of the orbit from the
fronto-parietal, and from that portion of the prootic which may be
regarded as the ala magna, above the m. retractor bulbi.
The muscle is broad, and compressed from before backwards: it runs
downwards covered by the m. temporalis, and soon passes into a
long, thin tendon (Fig. 57 pt), which is inserted, behind the
m. temporalis and immediately in front of the joint, into the
inner surface of the lower jaw.
Fig. 56.
Muscles of the lower jaw of Rana esculenta.
d
M. deltoideus.
dm
M. depressor maxillae, its origin where covering the m. temporalis reflected at *.
ld
M. latissimus dorsi.
m
M. masseter.
t
M. temporalis, origin.
t′
Lower portion of same.
Fig. 57.
Muscles of the lower jaw of Rana esculenta.
dm
M. depressor maxillae cut through and reflected.
la
M. levator anguli scapulae.
l.d.
M. latiss. dorsi, cut through and reflected.
m
M. masseter.
pt
M. pterygoideus.
s
Scapula.
s′
Suprascapula.
s.c.
M. sternocleidomastoideus.
t t
M. temporalis cut through and reflected.
16.M. masseter (Figs. 56, 57 m).
Dugès, zygomato-maxillaire, n. 29.
Arises as a somewhat broad muscle from the horizontal process of the
quadrato-jugal and is inserted into the outer side of the lower jaw,
opposite the insertion of the m. temporalis.
This muscle forms the floor of the mouth as does the
mylo-hyoideus in man; it is, however, not inserted into the
hyoid bone.
It arises—1. From the whole of the inner surface of the upper
border of the lower jaw45, except near the angle (Fig. 58 sm);
2. By a small portion (Figs. 58, 59, 61sm′) near the skull,
from the cartilaginous anterior cornu of the hyoid-bone which projects
from the cartilaginous part of the prootic bone. This portion descends
along the cornu to unite with the other portion. The two together form
a membranous layer, the fibres of which run transversely and meet in
a band of connective tissue along the middle line, forming a kind of
linea alba. The sheath runs forwards to the most projecting
part of the lower jaw superficially to the m. submentalis.
Slightly in front of its posterior border the muscle is attached in
its whole breadth to the skin of the throat by a fine lamella of
connective tissue, which is not always complete. The posterior border
of the muscle is attached to a fascia, which passes between the deeper
muscles and is attached to these. It is known that this muscle plays an
important part in the movements of respiration and swallowing; but its
precise action has not yet been worked out.
18.M. submentalis (Fig. 59 smt).
Cuvier, transversus, l. c., p. 588.—Dugès, 4, sous-mentonnier.—Zenker,
m. lingualis (incorrectly brought into connection with m. hyoglossus).
This small muscle lies in the anterior angle of the lower jaw
between the dentary bones. It consists of transverse fibres which pass
from one bone to the other. Below it is covered by the most anterior
portion of the m. submaxillaris.
Its action is to approximate the sides of the lower jaw: according
to Dugès (l. c., p. 123), it assists in closing the nostrils,
by drawing together the sides of the lower jaw and thus raising the
premaxillae.
Cuvier, IV, 1, 536.—Dugès, n. 16.—Zenker, p. 30.—M. St. Ange, l. c.,
Pl. XXVI, f. 1, 13, p. 423.
Fig. 59.
Muscles of the hyoid bone and the tongue of Rana esculenta.
The m. submaxillaris has been removed close to its insertion.
cm′
Origin of the hinder portion of same from the hyoid bone.
gh
M. geniohyoideus.
gh′
External portion of same.
gh″
Internal portion of same.
H
Body of hyoid bone.
H′
Anterior horn.
hg
M. hyoglossus.
oh
M. omohyoideus.
ph
Mm. petrohyoidei.
sh
M. sternohyoideus.
sh′
External origin of same.
sh″
Internal origin of same.
sm
M. submaxillaris.
sm′
Origin of hinder portion of same.
smt
M. submentalis.
Arises from the lower jaw in two portions, the one from near the
middle line above the m. submentalis, the other more externally
from the upper border of the lower jaw. The two parts unite to form
a long, flat muscle, which lies on the ventral surface of the body
of the hyoid bone, and divides posteriorly into two portions. One of
these, the median (Figs. 59, 60 gh″), is inserted into the inner
border of the posterior horn of the hyoid bone, and is here attached
to a fascia which covers the m. hyoglossus from beneath. By the
same fascia the muscles of opposite sides are connected in the space
between the two posterior cornua. The lateral division (Figs. 59, 60
gh′) is attached to the posterior cartilaginous process of the
hyoid bone.
20.M. sternohyoideus (Figs. 59,
60 sh).
Cuvier, IV, 1, 538 (pubio-hyoideus).—Dugès,
n. 17, sterno-xipho-hyoidien.—Zenker,
p. 30.
This muscle forms the cervical part of the m. rectus
abdominis and is, in fact, a direct continuation of it. It arises
by an inner portion (Fig. 59 sh″) from the upper surface
of the inner extremity of the coracoid and from the xiphisternum,
while the outer portion
(sh′) is an immediate continuation of the m. rectus
abdominis, which passes into this muscle at about the fifth
inscriptio tendinea. The muscle passes forwards on the upper
surface of the coracoid and of the clavicle, under the pericardium
towards the hyoid bone; here the muscle, hitherto horizontal,
suddenly becomes (compare Fig. 60) vertical, and passes between the
two insertions of the m. geniohyoideus, and is inserted for a
considerable length into the lower surface of the hyoid bone and the
anterior extremity of the posterior cornu.
Fig. 60.
Muscles of the tongue and of the hyoid bone of
Rana esculenta, from below.
gh
M. geniohyoideus.
gh′
External origin
of same
gh″
Internal origin
H
Body of hyoid.
H′
Anterior cornu.
H″
Posterior cornu.
hg
M. hyoglossus.
hg′
Hinder origin of same.
oh
M. omohyoideus.
ph.
1, 2, 3, 4, first, second, third, and fourth m. petrohyoideus.
sh
M. sternohyoideus.
21.M. omohyoideus (Figs. 59,
60 oh).
Cuvier, l.c., p. 539.—Dugès, n. 18,
interscapulo-hyoidien ou omohyoidien.—
Zenker, p. 31.—M.
St. Ange, l.c.
Arises from the anterior border of the bony scapula, and is inserted
into the outer part of the ventral surface of the body of the hyoid: it
is partially covered by the m. sternohyoideus.
Dugès, 10, rupéo-cérato-hyoidien.—Zenker, m. petro-ceraus? p. 30.—Klein,
basio-hyoideus, l.c., p. 71.
A thin, flat muscle, narrow above, but broadening rapidly below,
which arising from the outer extremity of the prootic bone, partially
surrounds the pharynx below, into which some of its fibres are
inserted; it is attached to the ventral surface of the body of the
hyoid bone, near the lateral notch. The chief action of this muscle
appears to be that of a m. constrictor pharyngis.
Cuvier, mm. stylohyoidei, l. c., p. 537.—Dugès, 20, 21, 22, masto-hyoideus
(Fig. 4).—Zenker, petro-hyoideus superior and inferior.—Klein,
stylo-hyoideus, l. c., p. 18.
Fig. 61.
Muscles of the hyoid bone of Rana esculenta,
seen from the right side and below.
H′
Anterior cornu.
H″
Posterior cornu.
hg
M. hyoglossus.
H H
Body of hyoid bone.
ph
1 M. petrohyoideus anterior.
ph
2, 3, 4 Mm. petrohyoidei posteriores.
sm
M. submaxillaris.
sm′
Hinder portion of same.
These are three long, thin muscles, which lie nearly parallel
to one another, and run from the prootic bone to the posterior
cornu of the hyoid bone. All three arise, covered by the m.
sternocleidomastoideus, from the lateral extremity of the prootic,
pass round the pharynx and are attached, the m. petrohyoideus
posterior primus (Fig. 61 ph 2) to the anterior extremity,
the secundus (Fig. 61 ph 3) to the middle; and the
tertius (Fig. 61 ph 4) to the hinder extremity of the
posterior horn of the hyoid bone.
Arises from the bony posterior extremity of the hinder process of
the hyoid bone (hg′). The muscles of the two sides pass forwards
and converge to the middle line, where they unite. The azygos muscle
thus formed runs forwards on the ventral surface of the hyoid bone,
between the mm. geniohyoidei, over the anterior border of the
hyoid, and passes into the tongue, where it turns backwards and runs to
the tip. (For action, see tongue.)
27.M. genioglossus.
Cuvier, l. c., p. 587.—Meckel, l. c., IV, 339.—Dugès, 23, genio-glosse.
Arises above the insertion of the m. geniohyoideus on either
side near the middle line from the two anterior bones of the lower
jaw. The two origins quickly unite to form a thick, very firm muscular
belly, which in its course backwards rapidly thins, and is distributed
by numerous bundles; decussating with the fibres of the m.
hyoglossus at an acute angle, it runs on to the anterior extremity
of the tongue.
Fig. 62.
Muscles of the chest, throat, and belly of Rana esculenta.
ch
M. coraco-humeralis.
d
M. deltoideus.
oi
M. obliquus abdom. internus.
oe
M. obliq. abdom. externus.
oe′
Scapular portion of same.
oh
M. omohyoideus.
p′
Port. sternalis anterior of m. pectoralis.
p″
Port. sternalis posterior of same.
p‴
Port. abdominalis of same.
r
M. rectus abdominis.
r′
Inner portion of same.
sh
M. sternohyoideus.
sm
M. submaxillaris.
sm′
Hyoid origin of same.
sr
M. sternoradialis.
In the formation of the abdominal wall the following muscles take
part:—(1) m. rectus abdominis, (2) m. obliquus externus,
(3) m. obliquus internus, (4) the portia abdominalis of
the m. pectoralis. Above, the m. obliquus internus forms
a kind of diaphragm, partially separating the abdominal from the
thoracic cavity (p. 70).
28.M. rectus abdominis (Fig. 62 r).
Dugès, pubio-thoracique, n. 52.
These muscles, situated on either side of the middle line of the
abdomen, are as a rule traversed by five notched inscriptiones
tendineae. Each muscle arises, by a narrow, strong tendon, from the
inferior border of the pubes, passes forwards, and quickly widening,
divides at the second inscriptio tendinea (counting from behind)
into two portions.
(a) The Outer portion (Fig. 62 r) runs into the
portio abdominalis of the m. pectoralis, and forms the
greater lateral division of that muscle.
(b) The Inner (r′) continues as the m. rectus
abdominis and gradually narrows anteriorly. At the sternum some of
the fibres (the median) are inserted into the dorsal surface of the
cartilaginous plate of the xiphisternum, while the greater part of
the muscle continues forwards over the coracoid to become the m.
sternohyoideus at about the fifth inscriptio tendinea
(p. 64).
29.M. obliquus externus (Fig. 63 oe, oe′).
Zenker, l. c., p. 31, m. obliquus.—Dugès, dorso-sous-abdominal, n. 54.
The m. obliquus externus arises from—
(a) The aponeurosis covering the long muscles of the back,
and by this from the spinous processes. The anterior edge of the m.
obliquus externus covers the posterior edge of the m. latissimus
dorsi, which arises from the inferior, ventral surface of the
aponeurosis. The aponeurosis also divides laterally into two parts,
one of which, the posterior, passes into the obliquus externus,
while the anterior forms the tendon of origin of the depressor
maxillae inf. (dm) (compare Fig. 66).
Fig. 63.
Muscles of trunk of Rana esculenta, from the right side.
cd
M. cutaneus femoris.
d
M. deltoideus.
d.m.
M. depressor maxillae.
i
M. infraspinatus.
ld
M. latiss. dorsi.
oe
M. obliquus abdom. externus.
oe′
Scapular origin of same.
ss
M. subscapularis.
t
M. triceps brachii.
(b) A second, narrow portion, portio omo-abdominalis
(Fig. 63 oe′)
(m. xipho-adscapulaire, Dugès, n. 62), arises from the posterior
border of the scapula by a thin tendon, and becomes broader as it runs
downwards and backwards, to join the anterior border of the other and
larger portion.
The whole muscle is attached by its most anterior fibres to the
cartilage of the xiphisternum, the rest passing into an aponeurosis
which, inseparably connected with the inscriptiones tendineae,
traverses the lower surface of the m. rectus abdominalis to the
linea alba.
Dugès, ileo-transverso-sous-sternal, p. 53.—Zenker,
transversus, l. c., p. 31.—Kuhl,
transversus, l. c., p. 116.
This muscle corresponds with the combined obliquus internus
and transversus, and has therefore been described either as the
one or the other, by various authors.
The fibres arise tendinously—
a. From the transverse processes of the vertebrae from
the fourth backwards, and from the fascia covering the mm.
intertransversarii.
b. From the iliac bone, by a strong tendon from its upper
border, and by a few weaker fibres from its outer surface. The latter
fibres are covered by the former, and these end posteriorly in a sharp
concave border.
Fig. 64.
Second layer of abdominal muscles of Rana esculenta, from the
right side and below. The m. obliquus externus and the right anterior
extremity has been removed.
dm
M. depressor maxillae.
hg
M. hyoglossus.
ld
M. latissimus dorsi and infraspinatus.
oi
M. obliquus internus.
oi′
Insertion of third portion of same.
oi″
Second portion inserted into the pharynx.
pc
Pericardium.
ph4.
M. petrohyoideus quartus.
r
M. rectus abdominis.
ss
M. subscapularis.
The muscular bundles diverge from these points, some running
forwards, some backwards; the former are only partially covered by
the portio omo-abdominalis of the m. obliquus externus
(compare Figs. 62, 63), in
front of the anterior edge of that muscle. The posterior border of the
muscle is uncovered.
The insertions of the muscle are very various, and as a consequence
very various functions are accomplished by it.
Fig. 65.
M. obliquus internus, showing its attachments superiorly.
h
Xiphisternum.
oe
Oesophagus.
oi
M. obliquus internus.
oi′
Fibres of m. obliq. int., which are inserted into the oesophagus.
oi″ oi‴
Fibres of same, which are attached to coracoid and xiphisternum.
p
Pericardium.
r
M. rectus abdominis.
a. The most anterior part of the muscle (Fig. 65 oi‴),
the fibres of which run forwards, is attached—
1. Partly to the xiphisternum and the coracoid.
2. A second portion, viz. that arising from the transverse
processes of the fourth vertebra (Fig. 64 oi″), surrounds the
pharynx like a diaphragm (Fig. 65 oe), and is attached to its
side as far as the dorsal aspect (Fig. 65 oi′). This portion is
lightly separated from the following.
3. A third portion, placed behind the preceding, runs from the
pharynx over the pericardium (Fig. 64 pc), and is attached to
this nearly as far as the middle line (Figs. 64 oi′ and 65
oi″), resting on the sternum, the m. rectus and m.
sterno-hyoideus. The lines of insertion of the muscles of opposite
sides form an angle, open in front. In the thin borders of this portion
the muscular bundles lie almost entirely in simple layers, and they are
therefore well adapted for microscopical purposes.
b. The middle and posterior portions of the muscle pass
downwards and slightly
backwards, towards the outer border of the m. rectus; there they
pass into a tendon which, for the most part, runs on the upper surface
of the rectus to the linea alba.
The muscles of the back are covered by a fascia, the fascia
dorsalis (Fig. 66fd), attached to the spinous processes of
the vertebrae. Anteriorly, where it covers the m. temporalis,
it is attached to the fronto-parietal and squamosal bones, posteriorly
to the superior border of the iliac bones and the extremity of the
urostyle. The posterior part, which covers the origins of the m.
longissimus dorsi, of the m. coccygeo-iliacus, and of the
coccygeo-lumbaris, is especially strong. From the anterior part
several muscles arise laterally, viz. a portion of the m. obliquus
abdominalis externus, of the m. latissimus dorsi, and of
the m. depressor maxillae inferioris. In the uppermost layer,
immediately covered by the fascia dorsalis, lie the m.
cucullaris, the m. retrahens scapulae, the m. latissimus
dorsi arising from the fascia itself, and the scapula with its
muscles; then come the long muscles of the back; and in the third and
deepest layer the short muscles of the back.
The individual muscles are as follows:—
A. Limb Muscles of the Back (for moving the shoulder-girdle
and arm).
31.M. cucullaris (Fig. 66 c).
Cuvier, angularis.—Dugès, n. 38, sous-occipito adscapulaire.—Zenker,
levator scapulae sublimis.
Fig. 66.
Muscles of the back and shoulder-blade.
c
M. cucullaris.
dm
M. depressor maxillae arising from the fascia dorsalis, cut through and reflected on the right side.
fd
Fascia dorsalis.
fd′
Same cut through at the spines.
i
M. infraspinatus.
l.a
M. levator anguli scapulae.
ld
M. Latissimus dorsi.
r
M. retrahens scapulae.
sc
M. sternocleidomastoideus.
In order to see this muscle, it is necessary to separate the
fascia dorsalis from the spines of the vertebrae and to turn it
back with the m. depressor maxillae inf. arising from it. It is
then seen to rise from the
posterior surface of the exoccipital as far as the middle line; the
muscles of the two sides run backwards, diverging each from the other,
so as to form an angle, and are then attached on each side to the
anterior superior angle of the suprascapula at its under surface and
median border.
Cuvier considers this muscle as the analogue of the m. levator
anguli scapulae. Dugès and Meckel consider it to be the anterior
part of the m. cucullaris, the former thinking the posterior
part of the muscle to be the m. rhomboideus. I cannot agree with
these opinions, and I regard the muscle as simply representing the
m. cucullaris of man (Ecker).
Dugès, n. 66, lombo-huméral.—Zenker, depressor brachii.
This thin, triangular muscle arises from the ventral surface of
the fascia dorsalis, and is posteriorly covered in part by the
anterior border of the m. obliquus abdominis externus. The
muscle becomes narrower towards the sides, and passes into a flat
tendon, which blends with that of the m. infraspinatus, and is
attached to the outer surface of the crista deltoidea of the
humerus by a triangular expansion.
33.M. retrahens scapulae
(Ecker), (Fig. 66 r).
Dugès, n. 59, lombo-adscapulaire.—Klein, m.
rhomboideus, l. c., p. 26.—Zenker, omoplateus
rectus? p. 37, l. c.—Kuhl, l. c., 124,
retrahens rhomboideus.
This flat, oblong muscle arises from the transverse process of the
fourth vertebra, and is connected with the third tendinous inscription
(counting from before) of the m. longiss. dorsi. Posteriorly
its origin forms a convex border, whence it runs forwards and to the
side; it is inserted into the ventral surface of the suprascapula,
near its inner border.
This muscle lies near the m. serratus or transv. scap.
tertius (Fig. 68ts″), and has an analogous position. It
would, therefore, possibly be more correct to regard it also as a
m. serratus. It arises from parts which represent ribs, and
is inserted into the scapula. It has, at any rate, no analogy to the
m. cucullaris, with which Dugès connects it, nor with the m.
rhomboideus, which Klein holds it to be, as it does not arise from
spinous processes.
B. Long Muscles of the Back.
34.M. extensor dorsi communis (Fig. 67 lg.d.).
Dugès, n. 33–40, masse des muscles surspinaux devisée
en huit faisceaux principaux: 1. vertebro-sus-occipital,
2–5. transverso-spinaux, 6. transverso-coccyg., 7.
sacro-coccygien, 8. ileo-coccygien. The muscles 1–7 form the
lombo-costal, 8 the ischicoccyg., Cuv.—Zenker, m.
sacrolumbaris.—Klein, longiss. dorsi,
coccygeo-lumb., coccyg.-iliac.
This muscular mass is covered by the fascia dorsalis,
the m. cucullaris and retrahens scapula, and the
suprascapula: it corresponds with (1) the m. ileo-costalis and
longissimus dorsi, dorsi and cervicis (Henle); (2)
the semispinalis and spinalis (Henle).
The following separate portions may be made out:—
35. (1) M. longiss. dorsi (Fig. 67 lg.d.).
Fig. 67.
Muscles of the back and pelvic girdle of Rana esculenta.
c.i.
M. coccygeo-iliacus.
c.l.
M. coccygeo-sacralis.
g.l.
M. glutaeus.
i
MM. intertransversarii.
i′
MM. intercrurales.
i.c.i.
M. intertransv. capitis inferior.
i.c.s.
M. intertr. cap. sup.
il.
M. ilio-lumbaris.
lg.d.
M. longissimus dorsi.
o.i.
M. obliq. internus.
t M.
temporalis.
This muscle arises from the most anterior part of the urostyle,
runs forwards near the middle line, separated from the muscle of the
opposite side by the spinous processes of the vertebrae. The inner
portion passes over the posterior spinous processes without being
connected with them, as far as the fifth, it is then inserted into the
succeeding spines as far as the exoccipital bone. The lateral portion
runs outwards and forwards to be attached to the transverse processes
and oblique processes of all the vertebrae, from the sixth forwards,
while accessory muscular slips arise from the transverse processes
and from the anterior spinous processes which, merging in the general
muscle-mass, are inserted with this into the occiput.
The muscle is subdivided by a series of wavy, tendinous partitions
(Fig. 67), which arise from the transverse processes, and traverse the
muscle in planes, the upper surfaces of which are directed upwards and
forwards. This arrangement of the muscle indicates its relation with
the lateral trunk muscles of fish and fish-like amphibians.
36. (2) M. coccygeo-sacralis (Fig. 67 c.l.).
This muscle is partially covered by the preceding, it arises
from the lateral surfaces of the anterior half of the urostyle;
from this origin the
fibres pass forwards and outwards to be inserted in two portions, the
anterior set into the arch and the posterior set into the transverse
process of the last vertebra. The former may be regarded as m.
intercruralis, the latter as m. intertransversarius.
37. (3) M. coccygeo-iliacus
(Fig. 67 c.i.).
This muscle arises from nearly the whole length of the lateral
surface of the urostyle, the anterior portion being concealed by the
preceding muscle. The fibres pass outwards and forwards to be inserted
into the anterior two-thirds of the inner surface of the ilium.
38.M. ilio-lumbaris
(Klein), (Fig. 67 il.).
Dugès, n. 51, transverso-iliaque.—Cuvier, Zenker,
etc., quadr. lumborum.
Evidently represents the quadratus lumborum of human anatomy;
it takes its origin from the anterior extremity of the ilium, and runs
forwards to be inserted into the transverse processes of the vertebrae
from the seventh to the fourth.
C. Short Muscles of the Back.
39.M. intertransversarius capitis superior (Ecker), (Fig. 67 i.c.s.).
Dugès, n. 41, ex-occipito-transversaire sup.
A small muscle arising from the prootic: it lies above the
levator anguli scapulae, and is inserted into the transverse
process of the second vertebra.
40.M. intertransversarius capitis inferior (Fig. 67 i.c.i.).
Dugès, n. 42, ex-occipito-transv. inf.
This muscle lies on the ventral surface of the preceding one, but is
easily separable from it; it arises from the angle of the prootic and
is inserted, together with the preceding muscle, into the transverse
process of the third vertebra. The n. vagus passes outwards
between these two muscles.
41.MM. intertransversarii dorsi (Fig. 67 i).
Dugès, n. 43 to 50, intertransversaires.
Seven small muscles, placed between adjacent transverse processes
of the vertebrae; from the second to the last, in continuity with the
muscles last mentioned.
42.MM. intercrurales (Ecker), (Fig. 67 i′).
Klein, p. 29, interspinales, interobliqui.
Those muscular fibres found between the arches of adjacent vertebrae
are so named. On account of the shortness of the spinous processes they
can scarcely be named m. interspinales.
A. Dorsal Muscles of the Shoulder-blade.
(I.) Muscles arising from the head or trunk, and inserted into the
scapulae, which they act upon primarily, and upon the shoulder-girdles
secondarily.
Some of these muscles, such as m. cucullaris and
retrahens, are situated on the back, and have already been
described with the muscles of that region. Others are attached partly
to the under-surfaces of the scapulae and are only visible from below;
they are best seen in such a preparation as is shown in Fig. 68, made
by cutting through the sternum in the middle line, and reflecting each
half outwards.
Dugès, sous-occipito-adscapulaire, n. 60.—Zenker, protractor scapulae,
Pl. I, Fig. 5.—Cuvier, Leçons I, p. 379, describes this muscle as part
of the m. serratus anticus magnus.
A fairly strong muscle, which has a broad origin from the prootic
and exoccipital bones as far as the foramen magnum, a few fibres
are also attached to the lateral portions of the parasphenoid. The
fibres run backwards and outwards, first in a frontal plane and then
in a sagittal plane, to be inserted into the under surface of the
suprascapula near the posterior border, where it encloses the hinder
border of the m. interscapularis.
Its action is to draw the shoulders forwards and inwards, or the
head downwards.
44.M. sternocleidomastoideus (Fig. 68 sc).
Dugès, scapulo-mastoidien, n. 65.—Cuvier, sterno-mastoidien.—Zenker,
protractor scapulae, Pl. I, Fig. 5, 1.
A narrow muscle placed in front of and externally to the preceding
muscle; its general direction resembles that of the m. levator ang.
scap.
The fibres arise from the most external part of the prootic
and from the hindermost part of the squamosal, under cover of the
m. digastricus maxillae, and from the hinder portion of the
cartilaginous tympanic ring. Covered by these muscles, it passes
backwards and downwards to be inserted into the concavity of the
anterior border of the scapula; externally to the origin of the
deltoid.
The action of this muscle is to draw the shoulder forwards and
towards the middle line, or to bend the head downwards.
45.M. protrahens scapulae (Fig. 68 ps).
Dugès, Zenker, protractor acromii, Pl. I, Fig. 5, 3.
This muscle lies to the outer side of the rectus capitis
inferior: it arises from the prootic, and runs backwards and
outwards upon the levator anguli scapulae, to be inserted into
the scapula.
It pulls the scapula forwards.
(b) Muscles which arise from the vertebrae.
46.M. transverso-scapularis major (Ecker), (Fig. 68 ts).
Dugès, transverso-interscapulaire, n. 63.—Cuvier,
l. c., p. 380, probably regarded as a portion of the
serratus.—Zenker, Pl. I, Fig. 5, 3; depressor
acromii, Pl. II, Fig. 3, 15.—Klein, depressor
scapulae.
Fig. 68.
Muscles of the shoulder, from below; the sternum has been cut
through and the sides drawn apart.
d
Deltoideus.
is
Interscapularis.
it
Intertransversarii.
la
Lev. anguli scapulae.
ps
Protrahens scapulae.
sc
Sternocleidomastoideus.
ss
Subscapularis.
ts
Transverso-scap. major.
ts′
Transverso-scap. minor.
ts″
Transverso-scap. tertius.
This muscle arises by tendon from the cartilage of the transverse
process of the fourth vertebra and by a slip from the cartilage of the
transverse process of the third vertebra. Diminishing in size, the
muscle passes outwards, forwards, and upwards to be inserted into the
posterior border of the scapula, opposite the insertion of the m.
sternocleidomastoideus. It draws the shoulder inwards, backwards,
and downwards.
47.M. transverso-scapularis minor (Ecker), (Fig. 68 ts′).
Dugès, transverso-adscapulaire, n. 61.—Cuvier, regarded as part of the
serratus.—Zenker, Pl. I, Fig. 5, 7, detractor scapulae.
This is much shorter than the muscle just described; it arises
under cover of the m. levator scapulae, from the transverse
process of the third vertebra in front of the transverso-scapularis
major; and runs outwards and forwards to be inserted into the
ventral surface of the cartilage of the scapula. The action of the
muscle is to draw the shoulder inwards, backwards, and outwards. Dugès
regards this muscle as a portion of the serratus anticus magnus,
the remainder of which he considers is to be found in the portio
scapularis of the m. obliquus externus (xipho-adscapulaire,
Dugès, n. 62).
48.M. transverso-scapularis tertius s. serratus (Ecker), (Fig. 68
ts″).
This is larger than the muscle just described; arising by a
broad and flat origin from the transverse processes of third and fourth
vertebrae, it runs upwards and inwards to be inserted into the
ventral surface of the cartilaginous scapula near its inner border.
In position, course, and action the muscle most nearly represents the
m. serratus anticus of human anatomy.
(II.) Muscles on the scapula, that is, arising from
the scapula and inserted into the scapula or humerus.
(a) Muscles on the deeper surface.
49.M. interscapularis
(Fig. 69 i.s.).
Dugès, interscapulaire, n. 64.
Fig. 69.
Muscles of right shoulder and upper arm. The coracoids (co)
and the clavicles (cl) have been drawn apart after cutting
through the sternum.
c.h.
M. coraco-humeralis.
cl
Clavicle.
c.o.
Coracoid.
d
M. deltoideus.
d′
Clavicular portion of m. deltoideus.
i
M. infraspinatus.
i.s.
M. interscapularis.
l.a.
M. levator anguli scapulae.
l.d.
M. latissimus dorsi.
p′
Sternal portion of m. deltoideus.
p″
Anterior sternal portion of the m. pectoralis.
p‴
Posterior sternal portion of the m. pectoralis.
s
Scapula.
s.r.
M. sternoradialis.
t.r.
M. triceps brachii.
One end of this muscle is tendinous, and is attached to the outer
extremity of the suprascapula; from this the muscle, becoming fleshy
and narrower, runs towards the middle line to become attached to the
ridge on the ventral surface of the scapula, from which the m.
deltoideus and the m. subscapularis arise, and between which
it passes. It approximates the scapula and suprascapula and lessens the
angle between them.
50.M. subscapularis (Fig. 70
ss).
Dugès, sous-scapulo huméral,
n. 72.
Fig. 70.
Right shoulder, from below, arm strongly abducted.
cl
Clavicle.
co
Coracoid.
d
Deltoideus.
d′
Clavicular portion of deltoid.
h
Humerus.
ss
Subscapular muscle.
This muscle is situated on
the upper or visceral surface of the scapula.
It arises from a bony ridge found on the upper surface of the coracoid
and of the proc. coracoideus of the scapula. The muscle runs
outwards and is inserted, after widening, into the inner surface of
the crista deltoidea of the humerus; it is antagonistic to the
deltoid, and draws the raised arm backwards and towards the trunk.
(b) Muscles on the superficial surface.
51.M. infraspinatus
(Fig. 57, between ld and
dm, Fig. 71 i).
Dugès, adscapulo-huméral, n. 67.
Fig. 71.
Muscles of the back and shoulder.
c
M. cucullaris.
dm
M. depressor maxillae.
fd
Fascia dorsalis.
fd′
Fascia dorsalis reflected.
i
M. infraspinatus.
l.a
M. levator anguli scapulae.
ld
M. latissimus dorsi.
r
M. retrahens scapulae.
sc
M. sternocleidomastoideus.
The m. infraspinatus represents the m. infraspinatus,
teres major and minor of human anatomy. It is of
triangular form, with the broad base directed inwards; it arises from
the whole of the upper surface of the suprascapula except along the
inner border which is formed of hyaline cartilage alone: from this
origin the fibres converge outwards to a flat tendon which unites
with that of the m. latissimus dorsi to be inserted into the
crista deltoidea humeri, by means of a thin, triangular,
tendinous expansion.
General arrangement of the muscles of the shoulder-blade.
The muscles attached to the scapula and suprascapula are:
1. Muscles of the back (m. cucullaris and m. retrahens scap.).
2. Muscles of the neck (m. omohyoideus).
3. Muscles of the abdomen (portio scapularis of the m.
obliquus externus).
4. True shoulder muscles (m. levator anguli scapulae; m.
sternocleidomastoideus; m. protrahens scapulae; mm.
transverso-scapularis major, minor, and tertius s.
serratus; m. interscapularis; m. subscapularis; and
the long head of the m. triceps).
From above the following are visible: m.
cucullaris, a portion of the m. subscapularis, and the
transverso-scapularis maior.
From below (after cutting through and drawing aside the
two halves of the sternum) may be seen: the omohyoideus,
sternocleidomastoideus, levator anguli scapulae,
protrahens scapulae, transverso-scapularis minor and
tertius, interscapularis and subscapularis.
B. Ventral Muscles of the Shoulder (Pectoral
Muscles)
These arise from the sternum or shoulder-girdle and are inserted
either into the humerus or into the radio-ulnar.
52.M. pectoralis (Fig. 72).
This is placed on the ventral surface of the shoulder-girdle and
consists of the following parts:
Dugès, clavi-huméral, n. 70 (port. clavic. du grand pectoral).
This is the anterior portion of the m. pectoralis, it arises
from the sternum proper and the epicoracoids. Broad at the origin, it
becomes narrower as it runs outwards into a tendon attached to the
crista deltoidea humeri.
Dugès, sterno-huméral, n. 71 (port. sternal du grand pectoral).—Klein,
humero-sternalis.
This muscle is placed immediately behind the portio sternalis
anterior, it has a somewhat broad origin from the sternum and
xiphisternum; the muscle runs outwards and slightly forwards to be
inserted into the groove beside the crista deltoidea humeri.
The tendon of the m. sterno-radialis passes between these two
portions of the m. pectoralis.
(γ) Portio abdominalis (Figs. 72, 73 p‴).
Dugès, abdomino-huméral, n. 69 (port. costal du grand
pectoral).—Zenker, brachio-abdominalis.—Klein,
humero-abdominalis.
Fig. 72.
Muscles of the chest, throat, and belly of Rana esculenta.
ch
M. coraco-humeralis.
d
M. deltoideus.
oi
M. obliquus abdom. internus.
oe
M. obliq. abdom. externus.
oe′
Scapular portion of same.
oh
M. omohyoideus.
p′
Port. sternalis anterior to m. pectoralis.
p″
Port. sternalis posterior to same.
p‴
Port. abdominalis of same.
r
M. rectus abdominis.
r′
Inner portion of same.
sh
M. sternohyoideus.
sm
M. submaxillaris.
sm′
Hyoid origin of same.
sr
M. sternoradialis.
This portion represents that part of m. pectoralis major
of human anatomy which
arises from the costal cartilages, and more particularly that part
which is connected with the aponeurosis of the m. obliquus abdominis
externus. The muscle arises (1) from the m. rectus abdominis
(Fig. 72 r), that is, it forms a direct continuation of the
outer portion of this muscle; (2) the inner, smaller part arises from
the superficial surface of the aponeurosis of the m. obliquus
abdominis. The muscle becomes narrower as it courses outwards and
forwards, the outer fibres being longer and more oblique than the
inner. The action of this muscle will necessarily vary according to the
part or parts which are brought into action; speaking generally, the
anterior extremities will be drawn downwards and towards each other.
A long, narrow muscle, lying upon the posterior border of the
coracoid and the lowest part of the m. subscapularis. By
its position it corresponds most nearly with the m. pectoralis
minor, although its insertion does not. It has a narrow origin
from the coracoid near the sternum, whence it courses outwards, under
cover of the port. sternalis anterior and posterior of
the m. pectoralis, to be inserted into the middle of the humerus
between the deltoid and internal head of the triceps. It draws the limb
towards the trunk.
Muscle of right shoulder and upper arm. The coracoids
(c.o.) and the clavicles (cl) have been drawn
asunder after cutting through the sternum.
c.h.
M. coraco-humeralis.
cl
Clavicle.
c.o.
Coracoid.
d
M. deltoideus.
d′
Clavicular portion of m. deltoideus.
i
M. infraspinatus.
i.s.
M. interscapularis.
l.a.
M. levator anguli scapulae.
l.d.
M. latissimus dorsi.
p′
Sternal portion of m. deltoideus.
p″
Anterior sternal portion of the m. pectoralis.
p‴
Posterior sternal portion of the m. pectoralis.
s
Scapula.
s.r.
M. sternoradialis.
t.r.
M. triceps brachii.
This muscle evidently represents the biceps of man, it lies in front
of the portio sternalis anterior of the m. pectoralis,
its hinder border being under cover of the latter muscle. It takes
origin from the episternum, omosternum, and the epicoracoid; from this
broad origin the fibres converge while coursing backwards and outwards
to be attached to a strong tendon. This tendon plays in a groove along
the crista deltoidea, and is held in position by tendinous bands
arising from the insertion of the m. pectoralis; it then pierces
the lower portion of the muscular belly of the deltoid, and is inserted
into the anterior extremity of the radial side of the radio-ulnar. The
muscle is a powerful flexor of the forearm.
It is placed in front of and external to the m.
sternoradialis, and represents both the m. deltoideus and
supraspinatus of man. The muscle has two points of origin:—
(a) Portio scapularis, the larger, external portion is
attached to the outer end of the clavicle, and to the anterior process
of the precoracoid, but it arises chiefly from the dorsal surface of
the scapula (from the same ridge as the m. subscapularis), and
lastly from the anterior border and ventral surface of the scapula. The
fibres pass outwards over the shoulder-joint.
(b) Pars clavicularis (musc. cleido-humeralis,
Klein) arises from the inner extremity of the clavicle and from the
omosternum and joins the portio scapularis.
The muscle is inserted into the humerus, the under part of the
portio scapularis being attached to the upper portion of the
crista deltoidea; the outer fibres of this part, together with
those of the pars clavicularis, are attached to the extremity
of the crista deltoidea and to the inner surface of the humerus
as far as the distal extremity; just before its insertion the muscle
is pierced by the tendon of the m. sternoradialis. The deltoid
draws the limb forwards.
Dugès, scapulo-huméro-olecranien, n. 75.—Capes, Zenker, m. anconaeus.
This muscle lies on the upper or dorsal surface of the arm, and
has relations similar to those of the corresponding muscle in man.
The long head arises from the posterior border of the scapula at
the upper border of the glenoid cavity, and is here attached to the
capsule of the joint; the inner head arises from the upper and inner
surfaces of the anterior
half of the humerus as far as the extremity; the outer head arises
from the outer surface of the humerus. Additional fibres, which may
be regarded as a fourth origin (m. subanconaeus), arise from
the upper surface of the hinder half of the humerus. The fibres from
these several origins unite to form a strong muscle, which covers the
upper, inner, and outer surfaces of the bone, and then passes into a
tendon. This tendon is attached to the capsule of the elbow-joint and
inserted into the proximal extremity of the radio-ulnar. A cartilage,
representing the olecranon, is found in the capsule at the point of
attachment of the tendon.
B. Muscles of the Forearm.
(I.) Muscles of the flexor surface.
The muscles of this surface are arranged in two groups, so as
to form, at the elbow-joint, a triangular depression (plica
cubiti), into which the tendon of the m. sternoradialis
sinks.
A. Muscles of the Inner Group.
57.M. flexor carpi I s. radialis (Fig. 74
Fc).
Dugès, sous-huméro-carpien, n. 83.
This represents either the flexor carpi radialis longior or
radialis brevior of man; it has a broad origin from the inner
border of the humerus above the epicondylus medialis. It becomes
narrower as it passes downwards to be inserted by a tendon into the
os semilunare and naviculare. The muscle is much stronger
in males than in females, and the crest from which it takes origin is
correspondingly larger in the former sex (p. 42). Tendinous fibres
connect it with the following muscles:—
58.M. flexor carpi II s. ulnaris (Fig. 74
Fc′).
Dugès, epitrochlo-carpien, n. 84.
This muscle represents the flexor carpi ulnaris or ulnaris
anterior, and is close to the inner side of the foregoing. It
arises from the epicondylus medialis, being connected by fibres
with the flexor digitorum communis, and is inserted into the
os naviculare.
Fig. 74.
Muscles of the right arm of Rana esculenta.
ed
M. extens. digitorum communis.
ei
M. abductor digiti II longus.
Fa′
M. flexor antibrachii lateralis superficialis.
Fc
M. flexor carpi radial.
Fc′
M. flexor carpi ulnar.
Fd
M. flexor digitorum communis.
sr
Tendon of the M. sternoradialis.
59.M. flexor digitorum communis (Figs. 75, 76, 77Fd).
Dugès, epitrochlo-sous-phalangettien, n. 118.
This muscle lies most internally, and corresponds to the m.
flexor digitorum sublimis of man. It arises in common with the
foregoing muscle from the epicondylus medialis, and runs
downwards to the palm of the hand. At its entrance into this it
diminishes and passes into the flat aponeurosis palmaris. (See
hand, B.)
Dugès, epitrochlo-sous-radial, n. 79. (Frequently
described as the pronator rotundus, a description which
cannot be retained, as the implied movement does not occur in the
frog.—Ecker.)
This muscle lies deeply on the inner side of the forearm, covered
by the flexores carpi; it arises tendinously from the
epicondylus medialis and is inserted into the inner surface of
the radial side of the radio-ulnar as far as the inferior articular
extremity.
Dugès, premier ex-huméro-radial, n. 76. (Usually described
as supinator longus, this, for reasons similar to those in the
case of m. flexor antibrachii medialis, cannot be retained.)
The situation of this muscle corresponds with that of the
supinator longus of man; it lies to the outer side of the
tendon of the m. sternoradialis, and arises by two heads, the
one, above from the outer edge of the humerus, the other deeper from
the epicondylus lateralis. They unite and pass into a tendon
which, running over the lower articular extremity of the radio-ulnar,
is partly attached to the carpus and partly connected with the tendon
of the m. extensor digiti II proprius longus. From its position
and insertion, this muscle evidently flexes the forearm and extends the
hand.
Fig. 75.
Muscles of the right arm of Rana esculenta, deep layer.
Dugès, epicondylo-sus-radial, n. 78.—Klein, flexor antibrachii. (Supinat.
brevis autt.)
This muscle arises under cover of the foregoing, from the
epicondylus lateralis of the outer surface of the humerus,
it becomes broader and
is inserted into the whole length of the lower (volar) ridge of the
radio-ulnar. It is a powerful flexor of the forearm.
(II.) Muscles of the extensor surface.
63.M. extensor digitorum communis longus (Fig. 75 ed).
Dugès, huméro-sus-digital, n. 95.
This muscle lies on the outer border of the forearm; it arises
in common with the short head of the flexor antibr. lateralis
superficialis from the epicondylus lateralis, and from
the surface above it; it runs downwards along the outer side of the
forearm, in order to pass into an aponeurosis on the back of the hand,
which expands upon the third, fourth, and fifth fingers, and ends
between them in a free concave border. This aponeurotic expansion is
connected with the tendons of the extensor brevis digitorum.
63*.M. abductor digiti II (i. e. pollicis) longus (Fig. 74 ei).
*Dugès, cubito-métacarpien, n. 87.
Fig. 76.
Muscles of forearm of Rana esculenta, dorsal view.
aa
M. anconaei.
ec
M. extens. digit. communis.
Fd
M. flex. digit.
This muscle lies between the foregoing and the flexor antibrachii
lateralis superficialis, and appears superficially in the interval
between them. It arises from the lateral surface of the radio-ulnar,
and runs obliquely over the m. flexor antibrachii lateralis
profundus and the hinder extremity of the radio-ulnar towards the
second finger into the metacarpal bones of which it is inserted.
64.M. extensor carpi ulnaris s. ulnaris post.
(Fig. 76 ec).
Dugès, epicondylo-sous-carpien, n. 85.—Klein,
abductor carpi internus.
This muscle has a somewhat narrow origin from the epicondylus
lateralis; during its course through the forearm, where it lies
between the mm. anconaei on the one side and the extensor
digitorum communi on the other, it becomes broader and is inserted
into the outer surface of the carpus in the following manner. By
one tendinous slip it is attached to the palmar border of the os
pyramidale, by a second slip to the outer border of the os
capitato-hamatum. This latter slip is usually connected in its
dorsal portion with the extensor digitorum communis brevis.
65, 66.M. anconaei s. extensores
antibrachii (Fig. 76 aa).
Dugès, epicondylo-cubital and epitrochlo-cubital, n. 80, 81.
Both these muscles lie on the extensor side of the forearm; they
spring, the one from the epicondylus lateralis, the other from the
epicondylus medialis; converging, they run downwards, enclose the
olecranon, and are inserted into the upper (dorsal) border of the
ulna, each forming a penniform muscle. They are extensors of the
forearm and assist the m. triceps.
(I.) Muscles on the palmar surface.
(1) Muscles common to all the digits.
67.M. flexor digitorum communis and m. palmaris brevis (Fig. 77fd, pb).
The origin and course of this muscle has been described above. At
its entrance into the palm it suddenly diminishes in size and passes
into a triangular aponeurosis, aponeurosis palmaris. Into
the outer border of this aponeurosis is inserted the m. palmaris
brevis (Fig. 77pb); this latter muscle arises from the
posterior or ulnar border of the lower extremity of the radio-ulnar
below the insertion of the mm. anconaei, and runs obliquely
downwards to this insertion.
From the lower free border of the aponeurosis a number of muscles
arise which will be described with the rest of the digital muscles.
(2) Muscles of the rudimentary thumb.
68.M. abductor pollicis (Figs. 77, 78 ap).
Dugès, cubito-pollicien, n. 100.
This short muscle arises from the upper border of the lower
extremity of the radio-ulnar, passes transversely outwards, and is
then inserted into the anterior border of the rudimentary thumb.
69.M. adductor pollicis (Figs. 77, 78 ad.p).
Dugès, sous-carpo-pollicien, n. 101.
This lies more superficially than the last, it arises from the
palmar surface of the os capitato-hamatum, and is inserted
together with the abductor pollicis into the thumb. Several
fibres of the extens. dig. II brevis are also inserted into the
thumb. As this member is completely covered with skin, the motions of
which it is capable are very limited.
(3) Muscles of the second finger, which serves the purposes of a
thumb.
70.M. flexor digiti II longus s. sublimis (Fig. 77 f2).
Dugès, sous-carpo-phalangettien de l’index, n. 133.
Fig. 77.
Muscles of hand of Rana esculenta, volar surface, larger than
nature.
A
Aponeurosis palmaris.
ab5
M. abductor dig. V primus.
ab5′
M. abductor dig. secundus.
ac
MM. anconaei.
adp
M. adductor pollicis.
ap
M. abductor pollicis.
ec
M. extensor digitorum communis.
e5
M. extens. dig. commun. brevis.
f2
M. flexor dig. II longus.
f3
M. flexor dig. III longus.
f4
M. flexor dig. IV longus.
f5
M. flexor dig. V longus.
fb2
M. flexor dig. II brevis.
fb3 and fb3′
MM. flexores dig. III breves.
fb4 and fb4′
MM. flexores dig. IV breves.
fb5
M. flexor dig. V primus.
fd
M. flexor digitorum communis.
o
M. opponens.
pb
M. palmaris brevis.
I
First finger, rudimentary thumb.
II
Second finger, functions as thumb.
III-V
Third to fifth fingers.
This is a flat muscle, which arises for the most part by fleshy
fibres from the hinder free border of the aponeurosis palmaris,
also by a smaller part from the palmar surface of the os
capitato-hamatum. It quickly passes into a thin long tendon which
is inserted into the terminal phalanx of the thumb (second finger).
Fig. 78.
Second layer of muscles on volar surface of
hand of Rana esculenta, larger than nature.
71.M. flexor digiti II brevis s. profundus (Fig. 77 fb2).
Dugès, sous-carpo-phalangien de l’index, n. 102.
This flat muscle, covered by the preceding, has a tendinous origin
from the palmar surface of the os capitato-hamatum, together with
one head of the flexor sublimis, and is inserted into the basal
phalanx.
72.M. flexor digiti II tertius (Fig. 78 fb2′).
Dugès, tendini-phalangien de l’index, n. 103.
A small, thin muscle which arises close to the foregoing from the
os capitato-hamatum, and is inserted into the basal phalanx (see
below, m. interosseus volaris I).
73.M. adductor digiti II (Fig. 78 ad2).
Dugès, métacarpo-métacarpien de l’index, n. 90.
This muscle represents the adductor pollicis of man; it
arises from the base of the third os metacarpal and is inserted into
the metacarpal of the second finger, which latter it draws towards the
third finger.
74.M. opponens digiti II (Figs. 77 and 78 o).
Dugès, sous-carpo-métacarpien de l’index, n. 90.
This muscle represents the muscle of like name in man. It arises
from the palmar process of the os capitato-hamatum by a narrow
tendon and passes into a broad, flat muscle, which is inserted into
the under surface and outer border of the metacarpal of the second
finger throughout its length. It has, undoubtedly, the same action
as the corresponding muscle in man.
(4) Muscles of the third finger.
75.M. flexor digiti III longus s. sublimis (Fig. 77 f3).
The smaller portion of this muscle arises from the free border
of the aponeurosis palmaris, the chief portion, together
with the flexor brevis, from the palmar surface of the os
capitato-hamatum. The two portions pass into one long tendon, which
is inserted into the last phalanx.
76, 77.MM. flexores digiti III breves s. profundi I, II (Fig. 77
fb3 and fb3′).
Dugès, tendini-phalangiens du medius, n. 104, 105.
These two muscles arise in part from the free border of the
aponeurosis palmaris, in part from the volar surface of the
os capitato-hamatum, and pass backwards on either side of the
muscle last described, to be inserted into the basal phalanx. Dugès
regards these as analogues of the mm. lumbricales.
78.M. flexor metacarpi dig. III.
This is a somewhat strong muscle, which arises by fleshy fibres
from the palmar surface of the os capitato-hamatum, and is inserted
into the palmar surface of the metacarpal bone.
(5) Muscles of the fourth finger.
79.M. flexor digiti IV longus s. sublimis (Fig. 77 f4).
It arises at the free border of the aponeurosis palmaris, and
is inserted into the terminal phalanx by a thin tendon.
80, 81.MM. flexores digiti IV breves s. profundi I, II (Fig. 77
fb4 and fb4′).
Dugès, tendini-phalangiens de l’annulaire, n. 108, 109.
Dugès regards these also as analogues of the m. lumbricales;
they arise on either side of the foregoing muscle from the free border
of the aponeurosis palmaris, and are inserted by tendons into
the basal phalanx.
82.M. flexor proprius phalangum dig. IV (Fig. 78 fp).
Dugès, phalango-phalangien, n. 115.
A small muscle which arises by two slips from the palmar surface
of the basal phalanx, and is inserted into the base of the middle
phalanx.
83.M. flexor metacarpi dig. IV (Fig. 78 i4).
This somewhat strong muscle arises from the os
capitato-hamatum, and is inserted into the palmar surface of the
metacarpal bone.
(6) Muscles of the fifth finger.
84.M. flexor dig. V longus s. sublimis (Fig. 77f5).
This corresponds exactly with the corresponding muscle of the
fourth finger.
Dugès, deuxième sous-carpo-métacarpien du digitule, n. 92.
This muscle has a narrow origin from the palmar surface of the os capitato-hamatum, it
widens and is inserted into the outer border of the metacarpal of the
small finger. It draws this finger towards the thumb.
88.M. abductor dig. V primus (Figs. 77 and 78 ab5).
Dugès, sous-pyro-pré-métacarpien du digitule, n. 93.
This muscle arises from the palmar border and the outer surface of
the os pyramidale, and is inserted into the basal phalanx by a
thin tendon.
89.M. abductor dig. V secundus (Figs. 77 and 78 ab5′).
Dugès, sous-pyro-post-métacarpien du digitule, n. 94.
It arises from the posterior part of the os pyramidale, is
short, and is inserted into the outer side of the metacarpal.
(II.) Muscles on the dorsal surface.
M. extensor digitorum communis longus (Figs. 75ed and 77ec).
90.M. extensor digitorum communis brevis (Fig. 79e3, e4, e5).
Dugès, sous-pyro-phalangettien du III, IV, V, n. 124, 128, 131.
Covered by the foregoing, this muscle arises from the os
pyramidale in conjunction with the extensor pollicis and
from the os capitato-hamatum. The part destined for the third
finger, together with that for the fourth, arises from the os
pyramidale, passes obliquely backwards into a tendon which runs
along the inner side of the corresponding finger to be inserted into
the last phalanx. That for the fifth finger arises from the inner
projection of os capitato-hamatum being here attached to the
insertion of the m. extensor carpi ulnaris, and is inserted in a
similar manner into the terminal phalanx of the fifth finger.
91.M. abductor digiti II (i.e.pollicis) longus (Figs. 74ei and
79 ab.2).
For the origin and course of this muscle in the forearm see
No. 63. The muscle passes obliquely over the wrist-joint from
the little finger towards the inner side and from before backwards,
it is inserted into the metacarpal of the second finger (thumb).
The place of insertion of this muscle into the metacarpal (compare
p. 47) is, in the males, developed into a ridge and process, the
muscle itself is enlarged during the breeding season. This muscle
abducts the thumb and by this means presses upon the chest of the
female when clinging to her.
92.M. extensor digiti II proprius longus (Fig. 79 e2, e2′).
Dugès, cubito-radio-sous-phalangien de l’index, n. 96.
Fig. 79.
Muscles of hand of Rana esculenta. Dorsal view, twice natural
size.
This muscle lies obliquely on the back of the hand, parallel with
the m. abductor digiti II. It arises by two heads, one from
the tendon of the flexor antibr. lat. superf. (n. 60) upon the
hinder extremity of the radio-ulnar. This tendon conceals the hinder
end of this bone by means of a patella-like thickening, and sends
forth three tendinous prolongations; of these, the one is attached
to the ulnar border of the radio-ulnar, the second to the os
naviculare, while the third constitutes that portion of the m.
extens. dig. II proprius long. which is under consideration. The
second head arises from the os pyramidale in connection with
the extensor digitorum communis brevis (n. 90). The heads unite
to form a long muscle, which runs obliquely towards the second finger,
passes into a tendon, which, after forming connections by some muscular
fibres with the metacarpal, is inserted into the terminal phalanx.
93.M. extensor dig. II proprius brevis (Fig. 79 eb2).
Dugès, sus-luno-phalangettien de l’index, n. 120.
This muscle lies between the preceding muscle and the abductor
dig. II longus. It arises from the os naviculare, and also includes
some fibres which arise from the second metacarpal. The tendon
runs along the radial side and is inserted along with the last
muscle into the terminal phalanx.
94.M. abductor dig. II brevis (Fig. 79 ab.2′).
Dugès, sus-luno-métacarpien de l’index, n. 88.
This represents the abduct. pollic. brevis of man, lies on
the outer side of the hand, arises from the os naviculare, and
is inserted into the second metacarpal.
95.M. extensor dig. III proprius.
Dugès, sus-luno-phalangettien du médius, n. 122.
This muscle has two heads of origin, from the os naviculare
and lunatum. These form one muscular belly, which rapidly
diminishes and passes into a tendon; this, after receiving a few
muscular fibres from the second metacarpal, runs to the outer part of
the dorsal surface of this finger as far as the terminal phalanx, where
it is inserted.
96.M. extensor dig. IV proprius.
Dugès, sus-pyro-phalangettien de l’annulaire, n. 128.
By a somewhat broad base, this muscle arises from the os
naviculare and lunatum. The tendon receives fibres from the
fourth metacarpal and runs on the outer half of the dorsal surface of
this finger as far as the middle phalanx, where it is inserted.
These lie transversely between the metacarpals. There are three; the
first has been already described as m. adductor digiti II (n.
73); the second is stretched between the third and fourth metacarpals,
and the third between those of the fourth and fifth fingers.
99, 100, 101. [b.] MM. interossei volares.
One may regard as such, four long, thin muscles, which take origin
near one another on the palmar surface of the carpal bones, and diverge
from this towards the second and fifth fingers.
1. The first of these muscles (Fig. 78fb2′) has already been
described above as the m. flexor digiti II tertius (n. 72).
2. The second (Fig. 78i3) passes from the origin already
described to the palmar surface of the basal phalanx of the third
finger.
3. The third (Fig. 78i4) runs, in like manner, to the fourth
finger.
a. The m. triceps femoris forms the outer
border of the thigh, and extends on to both the dorsal and ventral
surfaces. The outer border therefore corresponds with the anterior
surface of the thigh of man, in consequence of the thigh in the frog
being normally rotated outwards.
b. The m. vastus internus (v.i.) and a portion
of the adductor longus (ad′), the sartorius
(s), a portion of the adductor magnus (ad‴),
and the rectus internus major (r.i′) are found on the
inner surface of the thigh.
c. The rectus internus minor (r.i″) forms the
inner border.
d. On the dorsal surface are to be seen, nearest
the trunk, the glutaeus (gl), on the outer border the
vastus externus (v.e.), the pyriformis and
biceps (p and b), then the semimembranosus
(sm), and lastly the rectus internus minor
(ri″).
e. By reflecting the rectus internus major (compare
Fig. 82) there are exposed to view: the semitendinosus
(st), the whole length of the adductor longus,
magnus (ad′ and ad‴), and brevis
(ad″). By reflecting the triceps, one sees (Figs. 84, 85) the
ilio psoas (ip), and beneath the semimembranosus,
the quadratus (qf), and capsularis femoris
(og).
Muscles of left thigh of Rana esculenta. Dorsal view.
b
M. biceps.
ci
M. coccygeo-iliacus.
g
M. gastrocnemius.
gl
M. glutaeus.
p
M. pyriformis.
pe
M. peroneus.
r.a.
M. rectus anterior.
ri″
M. rectus internus minor.
sm
M. semimembranosus.
t.a.
M. tibialis anticus.
tr.
M. triceps fem.
v.e.
M. vastus externus.
The tendinous origin of this muscle is found on the outer surface
and upper border of the two hinder thirds of the iliac bone. Thence
it runs outwards and backwards between the head of the m. vastus
externus (ve) on the one side, and the ilio-psoas
and rectus anticus (ra) on the other, to be inserted into a tubercle
(trochanter) of the femur.
110.M. Pyriformis (Fig. 80
p).
Cuvier, pyramidal.—Dugès, coccy-fémoral, n. 136.
A narrow, slender muscle, arising from the apex of the coccyx; it
passes obliquely outwards and backwards to the thigh, to be inserted
deeply between the m. vastus externus and the biceps,
into the inner surface of the femur, but towards the ventral
surface.
M. triceps femoris s. extensor
cruris communis (Fig. 80).
Dugès, pelvi-fémoro-rotulien, n. 145, 146, 147.
This is a large, strong muscle, having three heads of origin, and
inserted by a tendon into the tibio fibula. The three heads are the
caput longum or the rectus femoris anticus (r.a.),
the caput externum or the vastus externus (v.e.),
and the caput internum or the vastus internus (Fig. 82vi); of these, the first is situated on the outer border of the
thigh, the second on the dorsal surface, and the third on the ventral
surface.
111. [a.] M. rectus femoris
anticus (Figs. 80, 82ra).
This arises from the under (ventral) surface of the iliac bone about
its middle and beneath the m. glutaeus. The muscular belly
quickly passes into an
aponeurosis, which covers the other two muscular masses and combines
with their tendons.
112. [b.] M. vastus externus (Fig. 80 v.e.).
It arises from the upper and hinder extremity of the iliac bone
(Fig. 42il′) behind the glutaeus, which here sinks in
between this muscle and the rectus anterior.
It arises from the whole of the under and outer surfaces of the
hip-joint capsule, and from tendinous slips which pass from this
capsule downwards on the under surface of the muscle, (from the pubis
and the femur I have not seen any fibres of origin, as stated by
others). Anteriorly the vastus may easily be separated into two
heads. The two vasti unite and form one muscular belly, in the
formation of which, as above stated, the rectus anticus takes
no part. This united muscle passes into a tendon which, without the
mediation of a patella, passes over the knee-joint to be inserted into
the anterior extremity of the tibio fibula, and is prolonged into the
fascia of the leg.
114.M. ilio-fibularis s. biceps (Fig. 80 b).
Dugès, ilio-péronien, n, 149.—Zenker, flexor externus tibiae, p. 42.
This is a long, somewhat narrow muscle, which lies to the inner side
of, and partly covered by, the vastus externus, between which
and the semimembranous it is placed. It arises by a tendon between
the ilio-psoas and pyriformis from the ilium above the
acetabulum and behind the origin of the vastus externus. From
here it passes backwards, separated from the vastus externus
by a strong ligam. intermusculare. On the inner side of this
muscle, between it and the m. semimembranosus, run the vessels
of the thigh and the N. ischiadicus. The muscle then divides
into two portions, of which one is inserted high up on the inner and
under surface of the femur. This is probably the muscle which Klein
(l. c., p. 61) describes as the extensor brevis. The
other long muscular belly passes into a thin tendon, opposite the
hinder extremity of the thigh, it divides into two portions; the
anterior is inserted into the dorsal surface of the hinder extremity
of the femur, the other into the dorsal surface of the tibio-fibula.
Between the two is stretched an arch with the concavity outwards. This
insertion of the biceps is covered by the stronger tendon of origin of
the m. gastrocnemius (compare Fig. 87).
Dugès, sus-ischio-poplité, n. 148.—Klein, p. 60, extensor femoris
sublimis.
This muscle lies on the dorsal surface of the thigh, to the inner
side of the biceps and pyriformis: it is a broad muscle,
which takes a tendinous origin from the hinder and upper angle of the
symphysis ossis ilei, and is inserted by a flat tendon into the
dorsal surface of the ligaments of the knee-joint, and through these
into the tibio-fibula. The tendon is formed rather abruptly from the
muscle, and is surrounded (Fig. 86) by the concave arch, which forms
the tendon of origin of the gastrocnemius (q. v.). A
little behind its middle (compare Fig. 81) the muscle is divided
obliquely into an anterior and a posterior portion by an aponeurotic
septum. As all the fibres are interrupted by this structure, the muscle
may very easily be torn through.
(B.) Muscles on the ventral surface.
Fig. 81.
Muscles of left thigh of Rana esculenta. Ventral surface.
ad′
M. adductor longus.
ad″
M. adductor brevis.
ad‴
M. adductor magnus.
e.c.
M. extensor cruris.
f.t.
M. flexor tarsi.
g.c.
M. gastrocnemius.
r.i′
M. rectus internus major.
r.i″
M. rectus internus minor.
s
M. sartorius.
t.a.
M. tibialis anticus.
t.p.
M. tibialis posticus.
v.i.
M. vastus internus.
116.M. sartorius (Figs. 81, 82 s).
Dugès, sous-iléo-tibial, n. 150.—Klein, gracilis.
This long, flat muscle lies along the middle of the ventral surface
of the thigh; it arises by a tendon from the anterior inferior angle
formed by the symphysis of the innominate bones, and terminates in a
tendon behind the knee-joint, forming a kind of pes anserinus in
the fascia of the leg, similar to that of the semitendinosus47.
117.M. rectus internus major (Ecker), (Figs. 81 r.i′, 82ri′).
Dugès, post-ischio-tibial profond, n. 152.—Klein, semimembranosus.
This is a broad and flat muscle, thinned out at either extremity;
it occupies the inner half of the ventral surface of the thigh,
and is in relation with the adductor magnus externally and
anteriorly, with the sartorius posteriorly, and the rectus
minor muscle internally. The muscle arises by a tendon from the
pubic symphysis; it covers in its course the semitendinosus,
then passes into a strong tendon, which blends with the tendon of the
rectus minor, to be inserted by a slip into a process of the
tibio-fibula representing the tuberositas tibiae; first passing
between the tendons of the sartorius and semimembranosus,
which here form an aponeurotic arch; a second slip passes under
the tendon of the
m. semitendinosus to be inserted into the upper surface of
the tibio-fibula, under it passes the N. tibialis. A third
thread-like tendon passes to the m. semimembranosus. Somewhat
behind its middle (Fig. 82) the muscle is traversed by an inscriptio
tendinea, by which the whole of the fibres are interrupted.
118.M. rectus internus
minor (Ecker), (Figs. 80, 81 r.i″).
Dugès, post-ischio-tibial superficiel, n. 151.—Zenker,
flexor tibiae magnus.—Klein, ischio-tibialis.
Situated entirely on the inner surface of the thigh, this narrow
muscle arises by a tendinous band which runs the whole length of the
pubic symphysis, and is connected posteriorly with the sphincter
ani, anteriorly with the rectus abdominis; posteriorly
it passes into a thin tendon which is also connected with the
muscle just described (117). In its course this muscle is attached to the skin by strands
of vessels and connective tissue.
The vastus internus major and minor together undoubtedly correspond
with rectus internus or gracilis of human anatomy. The rectus internus
major is, however, regarded as corresponding with the adductor magnus
by Dugès, and with the semimembranosus by Klein; by considering
the position and attachments of these muscles one must arrive at a
different conclusion.
MM. adductores femoris.
Fig. 82.
Muscles of the left thigh of Rana esculenta.
Ventral surface.
ad′
M. adductor longus.
ad‴
M. adductor magnus.
gl
M. glutaeus.
ip
M. ilio-psoas.
ra
M. rectus fem. anticus.
ri′
M. rectus int. major.
s
M. sartorius.
st
M. semitendinosus.
vi
M. vastus internus.
119. [a] M. adductor longus (Fig. 82
ad′).
Dugès, sous-ilio-fémoral, n. 141.
Without further dissection this muscle is only partially visible
between the m. sartorius and vastus internus (Fig. 81ad′). The muscle is flat and long, and arises by a tendon from
the anterior inferior angle of the pubic symphysis (Fig. 42s),
partially covered by the origin of the sartorius. Thence the
muscle passes between the vastus internus and the adductor
magnus, and finally is inserted below the middle of the femur,
together with the latter muscle.
Dugès, sous-ischio-pubi-fémoral (adductor 1 and 2), n. 142,
143.—Klein, adductor magnus and extensor femoris
profundus.
This muscle is visible between the sartorius and rectus
internus major in the anterior half of the thigh, posteriorly it
is covered by these muscles. It arises by a tendon from (a) the
pubic symphysis and ischii, and is in this position divided into
two portions, between
which passes the tendon of one head of the m. semitendinosus
(Fig. 83 st″); (b) a second part arises from this same
tendon (Fig. 83 st‴) and joins with the first part. Thus formed
the muscle passes to be inserted into the distal half of the inner
surface of the femur as far as the condyle. Near its hinder extremity,
however, it passes on to the dorsal and outer surfaces, and thus
forms a kind of muscular sheath surrounding the distal portion of the
bone.
Dugès, sous-pubio-fémoral (analogue of the pectineus,
possibly of the add. brevis also).
Fig. 83.
Deep muscles of left thigh of Rana esculenta.
ad′
M. adductor longus.
ad″
M. adductor brevis.
ad‴
M. adductor magnus.
ip
M. ilio-psoas.
pe
M. pectineus.
ra
M. rectus anticus,
ri′
M. rectus internus major
cut through.
ri″
M. rectus internus minor
s
M. sartorius.
st
Belly of m. semitendinosus.
st′
M. semitendinosus (cap. posticum).
st″
M. semitendinosus (cap. anticum).
st‴
Fibres passing into the adductor magnus.
vi
M. vastus internus.
These two small muscles which lie under cover of the
sartorius, adductor longus and magnus, appear
externally as one muscle, but may easily be separated (Fig. 83). They
arise close together from the pubic symphysis, and are inserted into
the inner surface of the anterior half of the femur. They are not
attached to the adductor magnus.
123.M. semitendinosus
(Fig. 83 st, st′, st″).
Dugès, bis-ischio-tibial,
n. 153.—Zenker, biceps.
This is a long thin muscle, only visible after removal of the m.
rectus internus, by which it is entirely covered. It arises by two
long thin tendons, one (caput posticum, st′) from the
pubic symphysis, the other (caput anticum, st″) from
the hollow between the symphysis and the acetabulum. The latter passes through a slit in
the adductor magnus, and so affords this muscle another point
of origin; then backwards between the adductor magnus and
the rectus internus major and under the lower third of the
thigh, and unites with the posterior head of origin. The muscle so
formed passes into a thin tendon, and, together with that of the
sartorius, forms an aponeurotic arch, connected with the fascia
of the leg, under which the tendons of the rectus internus major
and minor pass.
(C.) Deep muscles of the thigh.
To these, in addition to the adductor brevis, pectineus, and the
portion of the biceps already described, belong also the following:
Fig. 84.
Deep muscles of the left thigh of Rana esculenta. Dorsal
view.
Dugès, intra-ilio-fémoral (=iliacus and psoas).—Cuvier, Zenker,
Klein, iliacus internus.
The fibres of this muscle take a broad origin from the pelvic
surface of the ilium, pass outwards over the lower margin of the
bone and form a flat muscle with its apex pointed posteriorly. It
crosses the hip-joint between the m. rectus and vastus
internus, covering
the hinder part of the m. glutaeus, and is inserted into the
outer surface of the middle third of the femur.
125.M. quadratus femoris (Fig. 84 qf).
Dugès, post-ilio-fémoral (Homologue of the glutaeus maximus), n. 197.—Zenker,
glutaeus minor, p. 42.
Fig. 85.
Left half of pelvis of Rana esculenta. Thigh turned forwards
under the abdomen.
gl
M. glutaeus.
og
M. obturatorius.
This muscle is of a somewhat elongated, triangular shape, and
arises, under cover of the pyriformis, from the ilium behind the
acetabulum; it passes backwards over the joint to be inserted into the
inner and under surfaces of the femur, between the pyriformis
and ilio-psoas; below, it is in direct relation with the
adductor brevis.
126.M. obturatorius (Figs. 84, 85 og).
Dugès, ischio-pubi-fémoral, n. 139 (?).—Zenker, m. capsularis femoris.
This small muscle is deeply situated upon the hip-joint, and covered
by all the other muscles that arise from the symphysis. Its origin from
the innominate bone extends from the superior posterior angle of the
symph. ossis ilii to about the middle of the pubic symphysis;
the muscle fills the space between the crest of the symphysis and the
acetabulum. The fibres converge to pass into a strong tendon, which is
inserted into the posterior and anterior surfaces of the head of the
femur. The muscle appears to represent collectively the small rotators
of human anatomy, m. obturator externus and internus and
the gemelli.
On the outer surface (the anterior of man), covered by the fascia
cruris, into which the tendon of the extensor communis
cruris or triceps is prolonged, are found the following
muscles: nearest to the bone, the m. extensor cruris brevis
(ec); externally, the m. tibialis anticus (ta)
and the m. peroneus (pe). On the inner surface (the
hinder of man) lie the gastrocnemius (gc) and tibialis
posticus (tp), and deeply the flexor tarsi sup.
(ft).
Fig. 86.
Muscles of the right leg and foot of Rana esculenta.
Dorsal view.
a.h.
M. abductor hallucis.
a.l1
M. abductor longus digiti I.
A.p.
Aponeurosis plantaris.
b
M. biceps.
e.t.
M. extensor tarsi.
F.l.
M. flexor digitorum III, IV, V longus.
F.l′.
M. flexor digitorum I and II longus.
g
M. gastrocnemius, drawn towards the right.
g′
Tendon of origin of gastrocnemius.
l.c.
Ligamentum calcanei.
p
M. plantaris.
r.i.
MM. internus maior and minor.
s.m.
M. semimembranosus.
s.t.
M. semitendinosus.
t.A.
Tendo Achillis.
t.A′.
Thickening of tendo Achillis.
t.p.
M. tibialis posticus.
v.e.
M. vastus externus.
v.i.
M. vastus internus.
Fig. 87.
Muscles of leg and foot of Rana esculenta,
seen from below.
a.b.5
M. abductor dig. V longus.
ec
M. extensor cruris brevis.
e.d.1
M. extensor digit I longus.
e.d.4
M. extensor digit IV longus.
e.d.5
M. extensor digit V longus.
Ft
M. flexor tarsi anterior.
Ft′
M. flexor tarsi posterior.
g
M. gastrocnemius.
p
M. peroneus.
ta
M. tibialis anticus.
tF
M. triceps femoris.
This important muscle arises by two tendinous heads. The one
(Fig. 86 g′) rather nearer the middle line of the popliteal
space, is by far the stronger: it arises by a broad, tendinous
expansion, which covers the knee-joint, and is attached to the femur
and the tibio-fibula by anterior and posterior bands respectively; it
ends internally in a
concave aponeurotic arch: the second head is a thin, tendinous slip,
arising from the common tendon of the triceps as this lies
on the knee-joint. The muscle is thickest near its origin, and then
gradually diminishes in size as it passes backwards; the superficial
surface is convex, the deep surface is flat. By tracing the tendons of
origin, they are seen soon to unite and form a common flat tendinous
surface, broad in front, contracted behind; this aponeurosis lies in a
plane running obliquely from the deep surface towards the superficial
surface, without, however, reaching this. The muscular fibres arise
from both surfaces of the aponeurosis, the fibres of the two sides
diverging slightly as they pass backwards so as to be inclined at a
small angle to each other. The fibres are inserted into a fibrous
expansion (Ap) which lies on the superficial surface of the
muscle; thin and slight in front, this aponeurosis rapidly thickens
posteriorly until it passes into the tendo Achillis.
128.M. tibialis posticus (Fig. 86
t.p.).
Dugès, cruro-astragalien, n. 160.
Covered by the gastrocnemius this muscle occupies the whole of the inner and
upper surfaces of the tibio-fibula, from which it arises by numerous
fibres. Opposite the hinder extremity of the bone the muscle becomes
free and passes somewhat abruptly into a tendon, which courses
behind and over the malleolus internus, on to the dorsum
of the foot, and is here inserted into the anterior extremity of
the astragalus. I cannot agree with Dugès that this muscle
corresponds with the soleus (Ecker).
129.M. extensor cruris brevis (Fig. 87 ec).
Dugès, pré-fémoro-tibial, n. 154.
Covered by the strong fascia cruris, and lying between the
m. tibialis anticus and the tibio-fibula, this muscle arises by
a long tendon from the inner condyle of the femur; it passes backwards
in the groove on the anterior extremity of the tibio-fibula, covered
by the tendon of the triceps femoris, and is then inserted by muscular
fibres into the outer surface of the tibio-fibula almost as far as the
posterior third of the bone. (Dugès regards this muscle as the upper,
i. e. anterior, portion of the tibialis anticus.)
Dugès, pré-fémoro-astragalien and pré-fémoro-calcanien, n. 156 and 157;
the former he regards as one part of the tib. anticus, the latter
as the peroneus longus I.—Zenker, tib. ant. biceps.
The tendon of origin of this muscle is attached to the femur
near the tendon of the m. extensor cruris brevis, and to the
joint-ligaments. The muscle is placed under the fascia cruris,
its long tendon of origin passing beneath the tendon of the
triceps in a special sheath through the joint; the tendon then
gains a muscular belly which bifurcates at about the middle of the leg,
forming two muscular masses, coursing along the outer and the inner
side of the leg respectively. The latter is inserted into the dorsal
surface of the astragalus by a tendon, and the former into the
dorsal surface of the calcaneus in a similar manner. The muscle
extends the foot and flexes the tarsus; the latter movement is very
distinct on account of the insertion of the muscle being so near the
hypomochlion.
131.M. flexor tarsi anterior (Ecker), (Fig. 87 Ft).
Dugès, ex-tibio-astragalien, n. 155.—Zenker, tibialis anticus simplex.
This muscle arises where the insertion of the extensor cruris
brevis ceases, from the middle of the under surface of the
tibio-fibula, and passes backwards between the two tendons of the
m. tibialis anticus along the outer side of this muscle, to be
inserted by a tendon
into the inner side of the anterior articular extremity of the
astragalus and the fascia dorsalis pedis.
This is a strong muscle which is attached by a long tendon of
origin to the hinder extremity of the femur and the ligaments of
the knee-joint. The tendon runs in a sheath through the joint and
posteriorly becomes muscular; the muscle passes downwards on the
outer side of the tibio-fibula to be inserted into the malleolus
externus of this bone and into the anterior extremity of the
calcaneus. It has an action similar to that of the m.
tibialis anticus.
A. Muscles on the Plantar Surface.
Fig. 88.
Muscles of the right leg and foot of Rana esculenta.
Dorsal view.
a.h.
M. abductor hallucis.
a.lI
M. abductor longus digiti I.
A.p.
Aponeurosis plantaris.
b
M. biceps.
e.t.
M. extensor tarsi.
F.l.
M. flexor digitorum III, IV, V longus.
F.l.′
M. flexor digitorum I and II longus.
g
M. gastrocnemius, drawn towards the right.
g′
Tendon of origin of gastrocnemius.
l.c.
Ligamentum calcanei.
p
M. plantaris.
r.i.
MM. internus maior and minor.
s.m.
M. semimembranosus.
s.t.
M. semitendinosus.
t.A.
Tendo Achillis.
t.A′.
Thickening of tendo Achillis.
t.p.
M. tibialis posticus.
v.e.
M. vastus externus.
v.i.
M. vastus internus.
Fig. 89.
Muscles of the plantar surface of foot
of Rana esculenta, twice natural size.
A.p.
Aponeurosis plantaris, divided.
ab.5.
M. abductor dig. V.
ad.5.
M. adductor dig. V.
ad.l.1.
M. adductor longus dig. I.
e.t.
M. extensor tarsi.
F.5.
M. flexor brevis dig. V.
F.l.
M. flexor digitorum III, IV, V longus.
F.l′.
M. flexor digitorum I, II longus.
l.1.
Musculi lumbricales.
l.2.
l3
l3′
l4′
14″
l.5.
l.c.
Ligamentum calcanei.
p
M. plantaris.
t.A.
Tendo Achillis.
t.A′.
Thickening in tendo Achillis.
t.p.
M. transversus plantae posterior.
t.p.′
M. transversus plantae anterior.
133.Aponeurosis plantaris
(Fig. 88 A.p.).
As already mentioned, the tendon of the m. gastrocnemius
is, at the heel, continued into a strong aponeurosis, and possesses
at this place a thickening48. The aponeurosis is of triangular form, the
base directed towards the toes and attached to these. The lateral
borders of this triangle are continued into weaker fasciae,
which are attached to the two long tarsal bones. The inner border
in particular gives a strong bundle of fibres to the astragalus, and is thus
connected with the fascia of the dorsum of the foot; externally this
aponeurosis is attached to a cartilage (Dugès, os sesamoïde, l.
c., n. 66), situated on the plantar surface of the joint between
the calcaneus and the os metatarsi IV.
If the tendo Achillis be divided and the aponeurosis
plantaris reflected towards the toes, there is seen, arising
from the posterior head of the tibio-fibula, in its whole breadth,
a ligament (between the tib. posticus and peroneus).
This ligament forms a firm surface on which the thickened portion of
the tendo Achillis may move, and which evidently represents
the tuberosity of the heel bone. I have therefore named the entire
structure the ligamentum calcanei.
Several muscles arise from this
ligament, viz.:—
135.M. extensor tarsi (Klein),
(Figs. 88, 89 e.t.).
Dugès, tibio-sous-astragalien (regarded by him as the
homologue of the tibialis posticus).
Covered by the two succeeding muscles, this muscle arises from
the ligamentum
calcanei, runs backwards, and is inserted into the whole length of
the plantar surface of the astragalus. It extends the foot.
136.M. plantaris (Figs. 88, 89 p).
This takes its origin from the ligamentum calcanei to
the inner side and below the last muscle. It passes backwards
and is inserted into the dorsal surface of the aponeurosis
plantaris.
137.M. flexor digitorum III, IV, V longus (Ecker), (Figs. 88,
89 F.l.).
This muscle also arises from the ligamentum calcanei to the
outer side of the m. plantaris. It runs backwards over the
aponeurosis plantaris, and at the free margin of this passes
somewhat suddenly into a strong tendon, which traverses an aponeurotic
canal, formed by fibres of the aponeurosis passing above and below
the tendon, from the
cartilaginous enlargement in the tendon to the median border of the
aponeurosis. The tendon forms three slips for the fifth, fourth, and
third toes: these are slightly attached to the aponeurosis, but reach
beyond its free border to be inserted into the terminal phalanges
of the toes mentioned, and are held down by fibrous bands. (The
small m. lumbricales arising from these tendons are described
below.)
138.M. flexor digitorum I, II longus (Ecker), (Figs. 88, 89 F.l′.).
The tendons, by means of which the terminal phalanges of the
first and second toes are flexed, arise directly from the posterior
border of the aponeurosis.
The movements of the aponeurosis and through it the movements
of the tendons attached to it are influenced not only by the m.
gastrocnemius and plantaris, but also by two other muscles,
which together have been described as the flexor dig. longus
internus (Klein), or as the tarso-sous-phalangettien (Dugès,
221).
a.M. transversus plantae posterior (t.p.).
This takes its origin from the plantar cartilage, widens as it
courses backwards and inwards to be inserted into the dorsal surface of
the aponeurosis plantaris; from this the tendons for the first
and second toes (flexor dig. longus I and II) arise, thus
there is no direct connection between the muscular fibres of the two
muscles.
b.M. transversus plantae anterior (t.p′.).
This muscle is covered by the last; broader anteriorly, it arises
from the calcaneum, and is inserted to the inner side of the last
muscle into the dorsal surface of the aponeurosis. This muscle,
like that just described, is not continued directly into the tendon
of the flexor of the toes, they cannot therefore be regarded as
flexors of the toes.
This muscle arises from the inner border of the aponeurosis
plantaris, at the spot where the m. plantaris is inserted,
it may therefore almost be regarded as a continuation of this muscle;
it is inserted into the anterior border of the rudimentary toe.
(II.) Muscles of the great and first toes.
151.M. adductor longus digiti I (Figs. 89, 90ad.l1).
Dugès, calcanéo-scaphoidien, n. 164.
This powerful muscle arises from the plantar surface of the
calcaneum and astragalus; its fibres converge towards a tendon lying
in its middle, which
becomes free towards its posterior end; the tendon passing inwards
under the ligamentum tarsi transversum through a groove on
the hinder extremity of the astragalus in an arched direction, to be
inserted into the os naviculare, which bears the rudimentary
great toe and the os metatarsi I.
(III.) Muscles of the first toe.
152.M. abductor longus digiti I (Figs. 88al.1, 90 a.b.1).
It takes its origin from the inner border of the aponeurosis
plantaris, and lies on the plantar surface of the abductor
hallucis. Its tendon runs in the hollow which the great toe forms,
and is inserted into the inner side of the os metatarsi I.
153.M. flexor brevis digiti I (Fig. 90 F.b.1).
A small, thin muscle, which arises from the anterior extremity of
the os metatarsi II, and is inserted into the basal phalanx of
the first toe. In this small muscle, and also in the m. lumbrical.
dig. V (Fig. 89l.5.), the nerve distribution may be very
well seen.
154.M. opponens dig. I (Fig. 90 op).
Dugès, sous-metatarso-phalangien du pouce, n. 192.
This is situated to the inner side of the preceding muscle, arises
from the os metatarsi II somewhat narrow, widens in a fan-like
manner towards the os metatarsi I, into the anterior half of
which it is inserted.
(IV.) Muscles of the second toe.
155.M. flexor metatarsi dig. II (Fig. 90 F.m.2).
Dugès, sous-tarso-metatarsien du II doigt.—Klein, extensor metatarsi.
By a narrow origin from the hinder end of the calcaneum, posteriorly
this muscle becomes broader and is inserted, somewhat thinned out, into
the plantar surface of the second os metatarsi.
156.M. flexor dig. II proprius (Fig. 90 F.p.2).
Dugès, sous-metatarso-phalangien, n. 194.
It arises from the plantar surface of the os metatarsi II,
and is inserted by a thin tendon into the plantar surface of the first
phalanx.
Dugès describes this and the analogous muscles of the third,
fourth, and fifth toes (F.p.3, 4, 5) as the
interossei plantares, a nomenclature which, to me, does not appear correct, as
these muscles lie entirely on the plantar surface, and do not adduct or
abduct the toes, but flex them.
(V.) Muscles of the third toe.
Fig. 90.
Muscles of plantar surface of foot of Rana esculenta.
a.b.1
M. abductor longus digiti I.
ab5
M. abductor digiti V.
ad.l.1
M. adductor longus digiti I.
a.h.
M. abductor hallucis.
F.b.1
M. flexor brevis digiti I.
F.m.2, 3, 4
M. flexores metatarsi II, III, IV.
F.p.2, 3, 4, 5
MM. flexor. proprii digit. 2, 3, 4, 5.
F.ph.3, 4, 4′, 5
MM. flexor. phalang. digit. 3, 4, 5.
op
M. opponens digiti I.
t.m′
MM. transversi metatarsi 1, 2, 3.
t.m″
t.m‴
157.M. flex. metatarsi dig.
III (Ecker), (Fig. 90 F.m.3).
Dugès, sous-calcaneo-métatarsien du III doigt, n.
174.—Klein, extensor metatarsi.
Like the corresponding muscle of the second toe (n. 155), this
arises by a small tendon from the hinder extremity of the calcaneum,
runs backwards and is inserted into the plantar surface of the os
metatarsi III. The greatest portion of the muscle lies beneath the
m. transversus metatarsi (tm), the most anterior portion,
however, lies above this. Dugès has described this latter portion as
a special muscle (n. 176, metatarso-métatarsien du III), the same
description holds good for the second toe (n. 177, Dugès).
158.M. flexor dig. III
proprius (Ecker), (Fig. 91Fp3).
Dugès, sous-métatarso-phalangien du III doigt, n. 195.
Like the corresponding muscle of the second toe, this arises from
the plantar surface of the os metatarsi III, and is inserted by
a thin tendon into the plantar surface of the anterior extremity of the
first phalanx.
159.M. flexor phalangum proprius digiti III (Ecker), (Fig. 91
F.ph.3).
Dugès, phalango-phalangien, n. 204.
This arises by tendon from the plantar surface of the basal phalanx,
and is inserted into the anterior extremity of the terminal phalanx.
(VI.) Muscles of the fourth toe.
160.M. flexor metatarsi
dig. IV (Fig. 91 F.m.4).
Dugès, métatarso-métatarsien, n. 175.
Similarly to the corresponding muscle of the third toe, this one
arises from the hinder extremity of the calcaneum, and is inserted into
the anterior portion of the plantar surface of the os metatarsi
IV, but not into the greater portion of this surface, as in the
second and third os metatarsi.
Dugès, sous-métatarso-phalangien du IV doigt (interosseus
plantaris), n. 196.
The origin and insertion are similar to those of the muscles of the
second and third toes.
Fig. 91.
Muscles of plantar surface of foot of Rana esculenta.
a.b.1
M. abductor longus digiti I.
ab5
M. abductor digiti V.
ad.l.1
M. adductor longus digiti I.
a.h.
M. abductor hallucis.
F.b.1
M. flexor brevis digiti I.
F.m.2, 3, 4
M. flexores metatarsi II, III, IV.
F.p.2, 3, 4, 5
MM. flexor. proprii digit. 2, 3, 4, 5.
F.ph.3, 4, 4′, 5
MM. flexor. phalang. digit. 3, 4, 5.
op
M. opponens digiti I.
t.m′
MM. transversi metatarsi 1, 2, 3.
t.m″
t.m‴
162.M. flexor brevis dig.
IV.
A small muscle, which arises with the m. flexor brevis of the
fifth toe, from enlargement of aponeurosis plantaris, and is
inserted into the basal phalanx of the fourth toe.
163.M. flexor phalangum proprius dig. IV anterior (Fig. 91
F.ph.4).
Dugès, phalango-phalanginien, n. 205.
It resembles the corresponding muscle of the third toe.
Its origin and insertion are as in the corresponding muscles of the
second, third, and fourth toes, n. 159, 163, 164, 169.
170 to 172. MM. interossei (Fig. 91 t.m.).
Dugès, 1, 2, and 3, intermétatarsien, n. 170, 171, 172.
These are three muscles with their fibres arranged transversely,
which occupy the anterior portion of the spaces between the metatarsals, and approximate
these. The first arises (tm′) from the edge of the plantar
surface of the first metatarsal, and is inserted into the corresponding
part of the second: the second (tm″) passes from this point to
the third, and the third (tm‴) to the fifth.
B. Muscles of the Dorsal Surface.
173.M. flexor tarsi posterior (Ecker), (Fig. 92 F.t.).
Dugès, péronéo-sus-astragal, n. 161.
This is a strong muscle, which has a narrow origin from the outer
side of the tibio-fibula, directly over the distal extremity, and is
inserted into the dorsal surface of the astragalus from the middle to
the distal extremity.
Fig. 92.
Dorsal view of muscles of foot of Rana esculenta.
a.b.1
M. abductor brevis dig. I.
e.b.1
M. extensor brevis dig. I.
e.b.2
M. extensor brevis dig. II.
e.b.3
M. extensor brevis dig. III.
e.b.4
M. extensor brevis 1 dig. IV.
e.b.4′
M. extensor brevis 2 dig. IV.
e.b.5
M. extensor brevis dig. V.
e.l.1
M. extensor longus dig. I.
e.l.2
M. extensor longus dig. II.
e.l.3
M. extensor longus dig. III.
e.l.4
M. extensor longus dig. IV.
e.l.5
M. extensor longus dig. V.
F.t
M. flexor tarsi posterior.
i.2 to i.10 MM. interossei
Muscles of the first toe.
174.M. extensor longus dig. I (Fig. 92 e.l.1).
Dugès, calcanéo-sus-métatarsien du pouce, n. 166.
This lies to the outer side of and near the foregoing muscle; it
arises by a long, strong head from the middle of the calcaneum, runs
obliquely backwards and inwards to unite with a small head which
arises from the common epiphysis of the astragalus and calcaneum,
in common with the m. extensor dig. II. The muscle so formed
passes into a flat tendon to be inserted into the basal phalanx of
the first toe.
175.M. extensor brevis dig. I (Fig. 92 e.b.1).
A small, short muscle which arises from the os naviculare and is
inserted into the dorsal surface of the first metatarsal.
176.M. abductor brevis dig. I (Fig. 92 a.b.1).
Dugès, ex-tarso-métatarsien du pouce, n. 168.
This small muscle is situated near the preceding; it arises from
the first bone of the supplemental toe, and is inserted into the inner
side of the first metatarsal.
Muscles of the second toe.
177.M. extensor dig. II longus (Fig. 92 e.l.2).
Dugès, calcanéo-sus-phalangien du II doigt, n. 182.
This arises from the calcaneum, in common with the m. extensor
longus of the third toe, and is inserted into the basal phalanx of the
second toe by a tendon.
178.M. extensor dig. II brevis (Fig. 92
e.b.2).
Dugès, astragalo-sus-phalangien du II, n. 183.
This is partly covered by the preceding muscle: it arises from the
astragalus, and unites with the tendon of the preceding muscle.
Muscles of the third toe.
179.M. extensor dig. III longus
(Fig. 92 e.l.3).
Dugès, sus-astragalo-phalangien du médius, n. 199.
This arises with the extensor longus of the second toe from
the calcaneum: its tendon unites with that of the following muscle.
180.M. extensor
dig. III brevis (Fig. 92 e.b.3).
Dugès, astragalo-sus-phalangien du médius, n. 181.
This muscle arises from the astragalus, and is inserted with the
tendon of the preceding muscle into the dorsal surface of the basal
phalanx.
Muscles of the fourth toe.
Fig. 93.
Dorsal view of muscles of foot of Rana esculenta.
a.b.1
M. abductor brevis dig. I.
e.b.1
M. extensor brevis dig. I.
e.b.2
M. extensor brevis dig. II.
e.b.3
M. extensor brevis dig. III.
e.b.4
M. extensor brevis 1 dig. IV.
e.b.4′
M. extensor brevis 2 dig. IV.
e.b.5
M. extensor brevis dig. V.
e.l.1
M. extensor longus dig. I.
e.l.2
M. extensor longus dig. II.
e.l.3
M. extensor longus dig. III.
e.l.4
M. extensor longus dig. IV.
e.l.5
M. extensor longus dig. V.
F.t
M. flexor tarsi posterior.
i.2 to i.10 MM. interossei.
181.M. extensor longus dig. IV (Fig. 93 e.l.4).
Dugès, péroneo-sus-phalangien du IV, n. 178.
A narrow muscle arising in common with the flexor tarsi inf.,
but external to it. It is inserted into the tendinous expansion on
the dorsum of the toe.
182.MM. extensores dig. IV breves (Fig. 93 e.b.4 and e.b.4′).
Dugès, calcanéo-sus-phalangien and sus-calcanéo-phalanginien, n. 179
and 198.
These two small muscles arise from the calcaneum: one is inserted
into the basal phalanx, the other, by means of a long
thin tendon, passes along with the tendon of the corresponding
m. interosseus to the second phalanx, to which it is attached.
Muscles of the fifth toe.
183.M. extensor dig. V longus (Fig. 93 e.l.5).
Dugès, calcanéo-sus-métatarsien, n. 165.
A strong muscle which covers almost the whole length of the
calcaneum; it arises from the anterior extremity of this bone, runs
backwards to the outer side of the dorsum of the foot, and is
attached to the outer surface of the fifth metatarsal.
184.M. extensor dig. V brevis (Fig. 93 e.b.5).
Dugès, calcanéo-sus-phalangien du V, n. 180.
This is a long thin muscle, which, together with the muscle last
described, arises from the calcaneum and is inserted into the basal
phalanx of the fifth toe.
185.M. abductor dig. V brevis (Fig. 93 i.10).
This, the last m. interosseus, arises from the outer side of the
fifth metatarsal, and is inserted into the hinder extremity of the
second phalanx of the same toe.
186 to 195. MM. interossei dorsales (Fig. 93 i.1 to i.10).
First toe.
(1) The analogue of the first m. interosseus is the m.
abductor brevis dig. I (a.b.1).
(2) The second m. interosseus (i.2) arises from the
outer side of the first metatarsal, and is inserted into the outer
surface of the second phalanx of the same toe, dorsally to the m.
opponens and flexor brevis dig. I.
Second toe.
Fig. 94.
Dorsal view of muscles of foot of Rana esculenta.
a.b.1
M. abductor brevis dig. I.
e.b.1
M. extensor brevis dig. I.
e.b.2
M. extensor brevis dig. II.
e.b.3
M. extensor brevis dig. III.
e.b.4
M. extensor brevis 1 dig. IV.
e.b.4′
M. extensor brevis 2 dig. IV.
e.b.5
M. extensor brevis dig. V.
e.l.1
M. extensor longus dig. I.
e.l.2
M. extensor longus dig. II.
e.l.3
M. extensor longus dig. III.
e.l.4
M. extensor longus dig. IV.
e.l.5
M. extensor longus dig. V.
F.t
M. flexor tarsi posterior.
i.2 to i.10 MM. interossei.
(3) The third m. interosseus (i.3) takes origin from
the anterior part of the outer surface of the first metatarsal by
a thin tendon; it is inserted into the inner surface of the second
phalanx by a similar tendon.
(4) The fourth m. interosseus (i.4) arises from the
outer side of the second metatarsal, and is inserted into the outer
surface of the second phalanx.
Third toe.
(5) The fifth m. interosseus arises from the outer surface of
the second metatarsal, and is inserted by a thin tendon into the inner
surface of the second phalanx of the same toe.
(6) The sixth arises from the outer surface of the third metatarsal,
and is inserted laterally by a thin tendon into the hinder extremity of
the second phalanx of the same toe.
Fourth toe.
(7) The seventh m. interosseus (i.7) arises by a thin
tendon from the hinder
extremity of the astragalus, and by fleshy fibres from the hinder
extremity of the fourth metatarsal; it is inserted by a thin tendon
into the inner surface of the second phalanx of the same toe.
(8) The eighth m. interosseus (i.8) takes its origin
from the outer surface of the fourth metatarsal and from the inner
surface of the fifth: it is inserted into the hinder extremity of the
second phalanx.
Fifth toe.
(9) The ninth m. interosseus (i.9) arises from the
inner surface of the fifth metatarsal, and is inserted into the hinder
extremity of the second phalanx.
(10) The tenth m. interosseus has already been described as
the abductor digiti V brevis (Fig. 94 i.10).
If we take the fourth toe as the axis of movement, the first,
third, fifth, seventh, eighth, and tenth mm. interossei will
abduct from an imaginary line which runs through this toe. The second,
fourth, sixth, and ninth
will adduct towards this line. If we compare them with those of man
(in whose case the second toe affords the central line), those of the
first group must be regarded as mm. interossei dorsales, of the
latter as plantares. Dugès holds all these interossei
(with the exception of the first, abductor brevis dig. I) to
be mm. interossei dorsales (métatarso-sus-phalangettiens, n.
210, 211, 212, 214, 215, 216, 218, 219). Those which I have described
as flexores proprii digitorum, he regards as interossei
volares.
Fig. 95.
Pectoral region of Rana esculenta.
cp
M. cutaneus pectoris.
p″
Port. abdominalis of the m. pectoralis.
196.M. cutaneus pectoris (Fig. 95 cp).
Dugès, abdomino-guttural, n. 53.—Klein, abdomino-cutaneus.—Zenker,
subcutaneus pectoris.
This is an elongated quadrangular muscle, attached by its hinder
margin to the side of the xiphisternum, and to the superficial surface
of the aponeurosis of the m. obliquus externus. The fibres
course forwards and slightly outwards to be inserted, at a very acute
angle, into the skin: lying between the two muscles and attached to
them on either side is a thin fascia, which, together with the muscles
and the septum thoracicum, assists in closing a triangular space
between these structures and the deeper muscles.
The thinness and transparency of this muscle render it
especially suitable for the investigation of nerve-terminations49.
197.M. cutaneus dorsi (Fig. 96 cd).
Dugès, pubio-dorso-cutané, n. 56.—Zenker, cutaneus iliacus.
Fig. 96.
Hind portion of back and thigh of Rana esculenta.
cd
M. cutaneus dorsi.
cx.
Coccyx.
gl.
M. glutaeus.
H
Skin reflected to left side.
oc
M. obliquus externus.
rf
M. rectus femoris anterior.
sm
M. semimembranosus.
v.e
M. vastus externus.
This muscle has a narrow origin in the space between the
muscles of the belly and
of the thigh, and is here inserted into the fasciae, which are attached
to the pubic symphysis; it passes inwards and upwards to the outer side
of the anterior insertion of the m. rectus femoris anticus, then
widens and is inserted by diverging fibres into the inner surface of
the skin of the hinder portion of the back.
198.M. coccygeo-cutaneus.
Dugès, coccy-dorso-cutanés,
n. 57.
The muscular fibres which Dugès has described under this
name, lie covered by the m. pyriformis, behind the m.
coccygeo-iliacus, etc., and above the muscles of the rectum. They
arise from the hinder extremity of the urostyle: they appear to be
connected with the rectal muscles, and pass outwards to be attached to
the skin.
Among the cutaneous muscles may perhaps be included the m.
submaxillaris (p. 62).
The fibrils passing from the flexor tendons to the warty bodies
on the plantar surface of the toes are described50 with the skin (p. 373).
SECTION III. THE NERVOUS SYSTEM.
THE NERVOUS SYSTEM.
LITERATURE.
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Vol. XL, pp. 331–337.
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Arndt, A. W., Untersuchungen über die Ganglienkörper des Nervus sympathicus.
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Arnold, J., Zur Histologie der Lungen des Frosches. Virchow’s Arch. 1863.
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Arnold, J., Histologische Verhältnisse des Frosch-Sympathicus. Centralbl. f. d.
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Arnold, J., Ueber die feineren histologischen Verhältnisse der Ganglienzellen
in dem Sympathicus des Frosches. Virchow’s Arch. 1865. Vol. XXXII,
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Arnold, J., Die Spinalfasern im Sympathicus des Frosches. Arch. f. Anat. und
Physiol. 1866, p. 398.
Arnold, J., Das Gewebe der organischen Muskeln. Leipzig, 1869; and Chap. IV
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Beale, L. S., On the Structure and Formation of the so-called Apolar, Unipolar,
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Beale, L. S., Further observations in favour of the view that nerve-fibres never end
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Beale, L. S., New observations upon the structure, etc. of certain nervous centres.
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Beale, L. S., On the Distribution of Nerves to the elementary fibres of Striped
Muscle. Phil. Trans. 1864, p. 611.
Beale, L. S., Of very fine nerve-fibres ramifying in certain fibrous tissues and
trunks, and plexuses consisting entirely of very fine nerve-fibres in the bladder
of the frog. Beale’s Archives of Medicine, 1864. Vol. IV, pp. 19–251.
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1847.
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Bremer, D. L., Die Nerven der Capillaren, der kleinen Arterien und Venen.
Arch. f. mik. Anat. Vol. XXI. 1882, p. 663.
Bremer, L., Ueber die Muskelspindeln sowie über Structur, Neubildung u. Innervation
der quergestreiften Muskelfaser. Waldeyer’s Arch. 1883. Vol. XXII,
p. 2.
Bremer, L., Ueber die Endigungen der markhaltigen und marklosen Nerven im
quergestreiften Muskel. Arch. f. mikrosk. Anat. 1882. Vol. XXI, p. 165.
Brenner, A., Ueber das Verhältniss des nervus laryngeus inferior vagi zu einigen
Aortenvarietäten des Menschen und zu dem Aortensystem der durch Lungen
athmenden Wirbelthiere überhaupt. His u. Braune’s Arch. 1883, pp. 373–397.
Budge, J., Ueber den Verlauf der Nervenfasern im Rückenmark des Frosches.
Arch. f. Anat. u. Physiol. 1844, p. 160.
Budge, J., Ueber die Bewegung der Iris. (Concerning ganglia of motor-oculi, p. 36.)
Budge, J., Wagner’s Handwörterb. d. Physiologie. 1846. Vol. III, p. 451.
Burdon-Sanderson, J., Circulation of the Blood. Handbook for the Physiological
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I. THE CENTRAL NERVOUS SYSTEM. — A. The Spinal Cord (Fig. 97 ). — B. The Brain (Figs. 98 , 102 , 103 , and 105 ). — C. The Coverings of the Brain and Spinal Cord. — D. The Vessels of the Brain and Spinal Cord. (Fig. 110 .) — II. THE PERIPHERAL NERVOUS SYSTEM. — E. The Cranial Nerves. — F. The Spinal Nerves. — G. The Sympathetic System ( Sympathicus ). — H. Histological Notes on the Nervous System.
THE NERVOUS SYSTEM.
(Re-written by the translator.)
1.External form. The spinal cord is, in comparison
with the brain, somewhat small; the two organs are directly continuous,
and present no distinct line of demarcation: the point of origin of the
first spinal nerve is, therefore, arbitrarily accepted as the anterior
limit of the spinal cord; posteriorly it terminates in the filum
terminale.
The spinal cord is flattened dorso-ventrally, and is constricted at
a point (pars media, Reissner) somewhat anterior to its middle:
in consequence of this constriction the cord has two enlargements; an
anterior smaller, and a posterior larger (intumescentiae anterior
v. posterior), from which arise the nerves of the brachial
and lumbar plexuses respectively. At about the sixth or seventh
vertebra, the hinder enlargement diminishes rather abruptly to form
the so-called conus medullaris; this is continued into the
filum terminate, which enters the cavity of the urostyle. The
hinder portion of the lumbar nerves forms a cauda equina, the
constituent nerves of which surround the filum terminale.
A dorsal longitudinal fissure (sulcus longitudinalis
superior) is well marked in the middle line of the dorsal surface
of the posterior enlargement; anteriorly and posteriorly it rapidly
fades away, its position being merely indicated by a small amount of
connective-tissue and a blood-vessel.
The ventral longitudinal fissure (sulcus longitudinalis
inferior) is well marked throughout the length of the cord. Neither
fissure can be traced in the hinder part of the conus medullaris
or in the filum terminale.
Ten pairs of nerves arise from the spinal cord, each nerve arising
by two roots, a ventral and a dorsal (anterior and posterior),
from points near the
ventral and dorsal longitudinal sinuses respectively: the two roots
unite at their point of exit from the vertebral canal through the
intervertebral foramen; each dorsal root possesses a ganglion.
Fig. 97.
The nervous system of Rana esculenta, from the ventral
surface. (From Icones physiologicae by A. Ecker. Pl. XXIV, Fig. 1.)
F
Facial nerve.
G
Ganglion of pneumogastric nerve.
He
Cerebral hemisphere.
Lc
Optic tract.
Lop
Optic lobe.
M
Boundary between medulla oblongata and spinal cord.
M1‑10
Spinal nerves.
MS
Connection between fourth spinal nerve and sympathetic chain.
N
Nasal sac.
Ni
Sciatic nerve.
No
Crural nerve.
o
Eyeball.
S
Trunk of sympathetic.
S1‑10
Sympathetic ganglia.
Sm
Rami communicantes of sympathetic.
Sp
Continuation of sympathetic into head.
I
Olfactory nerve.
II
Optic nerve.
III
Motor oculi nerve.
IV
Trochlear nerve.
V
Trigeminal and facial nerves.
Va
Ramus ophthalmicus of trigeminal.
Vc
Ramus maxillo-mandibularis of trigeminal.
Vd
Mandibular branch of trigeminal.
Ve
Hyomandibular branch of facial.
Vg
Gasserian ganglion.
Vs
Upper end of sympathetic trunk in connection with Gasserian ganglion.
VI
Abducens nerve.
VII
Facial nerve.
VIII
Auditory nerve.
X
Glossopharyngeal and pneumogastric nerves.
X1
Ramus anterior of glossopharyngeal.
X2
Ramus Posterior of glossopharyngeal.
X3–4
Branches of pneumogastric.
2.Internal structure. As in other vertebrates,
the spinal cord consists of white and grey matter, the latter being
surrounded by the former; the relative amount of the one to the other
varies in different parts of the cord.
A transverse section of the cord presents the same general
characteristics as a similar section from a bird or mammal. The grey
matter lies in the middle, surrounding the central canal, and is
prolonged into each half of the section by ventral and dorsal horns or
cornua. The grey matter is surrounded by the white, but is not
so sharply marked off from this in amphibia as in birds and mammals.
A section through the anterior enlargement is almost
quadrangular in outline, and somewhat broader below than above; the
ventral longitudinal fissure is well marked and deep, while the dorsal
is indistinct. The dorsal horns are narrow and short, the ventral
longer and much broader. The space between the dorsal horns is narrow
and deep, that between the ventral shallow; the outer boundary of the
grey matter is almost straight, and the central canal is placed above
the centre of the section.
In the constricted portion of the cord (pars media)
the relative proportion of the white matter is increased at the expense
of the grey; the horns are less distinct, the dorsal being directed
outwards and the ventral somewhat flattened. The central canal is in
the centre of the section.
The posterior enlargement shows the ventral horns projecting
outwards, very much enlarged, and approaching the periphery; the
space between them is semilunar. The dorsal horns are well developed,
especially at their upper parts; the space between them is narrow and
deep. The outer margin of the grey matter is again nearly a straight
line. The central canal is below the centre of the section.
The arrangement of the parts in the conus medullaris
approaches that in the pars media: the horns are much diminished
in size, and posteriorly they entirely disappear, the ventral horns
persisting longer than the dorsal. The central canal approaches the
lower surface.
No cornua can be recognised in the filum terminale behind
the origin of the last pair of spinal nerves. The grey matter has here
a circular outline, with the exception of a very slight indentation
below; the white matter is almost absent: the central canal is on the
lower border of the section in the anterior part, while posteriorly it
occupies almost the entire space below the pia mater.
The Central Canal lies in the median line, and always
presents a distinct
lumen; in the two enlargements this lumen forms a vertical ellipse51, while in
the pars media it is circular. The canal is lined by a single
layer of ciliated columnar epithelium, the cells of which are usually
conical, with their bases directed towards the lumen; but other forms
may be noticed. These cells average about 0·040 mm. in length and about
0·002 mm. in width at their broadest part. The peripheral extremities
of the cells have processes, which, in the case of the cells above and
below the cord, may often be traced as far as the pia mater;
the processes of the lateral cells are less distinct and seem to be
shorter. Anteriorly the central canal opens into the floor of the
fourth ventricle. The termination of the central canal, posteriorly,
has been described by Masius and Vanlair. According to these observers,
the canal towards the hinder end of the filum terminale
increases very gradually in width, until its epithelial cells are
immediately underneath the pia mater, its walls then converge
somewhat more sharply to close the cavity. From the point where the
canal commences to increase in width, a change takes place in its
epithelial wall, which, instead of having a single layer of cells, now
possesses two to three layers; towards the posterior end it is again
thinned out to a single layer.
The grey matter varies in different parts of the cord and in
different parts of the same section. In a section through the anterior
enlargement a portion of the grey matter, placed immediately above
the central canal, is easily distinguished by its vertically-placed,
elliptical outline, and by its transparency: it is known as the
substantia reticularis. It consists of a mesh-work of branched
cells, through which course distinctly contoured fine commisural fibres
which are derived chiefly from the dorsal cornua, the vertical from
the epithelial cells of the roof of the central canal. In a series of
sections the substantia reticulosa may be seen to originate
indistinctly in the most anterior part of the cord; in the anterior
enlargement it already possesses the elliptical form mentioned, and
in the pars media it commences to send off lateral processes
to either side. In the posterior enlargement it reaches its greatest
absolute development, as it here surrounds the central canal; while
further backwards it encroaches until, together with the remaining
grey matter, it constitutes almost the whole of the filum
terminale.
Immediately underneath the central canal is a narrow band, which
immediately connects the grey matter of the two sides; above it
is bounded by the epithelium of the central canal, below by medullated fibres. This
septum medium (Reissner) may be traced backwards from the
anterior extremity of the cord to the posterior enlargement. It
consists chiefly of transverse fibres, together with vertical fibres
derived from the epithelial cells on the floor of the canal, and like
the substantia reticulosa, is distinguished by its greater
transparency from the rest of the grey matter.
The grey matter consists of connective-tissue and nervous elements,
which are very intimately united; each of these elements including its
special cells and fibres. The nerve-cells vary much in size and
appearance. A prominent group of large cells in the ventral cornua,
the lateral group (Stieda), is very conspicuous. The individual
cells are seldom rounded, but are usually spindle-shaped or angular,
and each possesses one to five processes, which may often be traced
through considerable distances. These cells have an average length of
0·040 mm., and are about 0·016 mm. broad; they are somewhat larger
in the anterior enlargement than in the posterior, and are also more
numerous in a section from the anterior enlargement than in a section
from the posterior. In the terminal filament they gradually disappear.
Some of their processes are continued into the lateral columns
(Köppen).
Smaller, spindle-shaped or triangular cells are scattered
irregularly throughout the grey matter, without forming distinct
groups, though for descriptive purposes those of the centre have been
named the central group. In a stained, transverse section of the
cord are seen numerous nuclei; these undoubtedly belong both to
small nerve-cells and to connective-tissue cells, but except under the
most favourable conditions the two are indistinguishable. The larger
nerve-cells present the usual characters of nerve-cells: more or less
granular contents, nucleus, well-marked nucleolus, more or less marked
fibrillation; their processes are usually more homogeneous. The cells
are frequently pigmented.
The processes of the cells belonging to the lateral group
radiate in all possible directions, but certain well-marked processes
directed towards the middle line can always be made out. From the
lowest part of this group a few processes may be traced into the
ventral roots. The small cells seem to be chiefly arranged vertically,
although their processes radiate in all directions (Stieda).
The Fibres of the grey substance are nearly all
non-medullated. They may be traced in all directions, but the
best-marked groups are either vertical or transverse. The vertical
fibres appear to arise from the central grey matter, and to ascend
in larger or smaller
bundles towards the periphery. The transverse fibres are arranged
chiefly in the two commissures: the dorsal commissure (commissura
superior) is the smaller; the fibres are parallel, and show no
trace of decussation; externally they radiate in various directions
to the dorsal horns. The ventral commissure is composed of two
layers, the upper grey (commissura inferior grisea), the lower
white (commissura inferior alba): both are interrupted by the
septum medium. A well-marked decussation of the fibres is seen
in the middle line; the exact mode of termination of these fibres has
not been made out, but many appear to communicate with the large cells
of the ventral horns.
The white matter consists chiefly of longitudinal, medullated
fibres, in which various columns may be distinguished. The dorsal
columns are separated from the lateral by a process of neuroglia,
continued from the general investment of neuroglia lying under the
pia mater. The line of separation between the lateral and
ventral columns is not well marked; it is about the line which would be
formed by prolonging the ventral horns to the surface.
The fibres vary in size, and fibres of all sizes may be found in
any particular part of a transverse section; still the fibres of the
ventral columns have an average greater diameter than those of the
lateral columns, and the fibres of the dorsal columns are finer than
those of the lateral. The largest fibres of the ventral column are
placed near the ventral fissure and on its lower border; they attain
their greatest development in the posterior enlargement; these fibres
frequently contain two or three axis-cylinders each. Köppen suggests
that they may represent the formatio reticularis of higher
animals.
In the lateral columns the larger fibres are placed close to the
grey matter, these columns also receive fibres from the cells of the
lateral group.
In the dorsal columns the radiating root-fibres never reach the
median plane, but leave an area of purely longitudinal fibres on each
side of the dorsal fissure; these represent Goll’s columns, and have a
club-shaped outline in transverse section.
The white matter is pierced in all directions by fine
connective-tissue fibres and bundles of fibres which radiate from
the grey matter; some branch and join with others to form a network,
others pass almost uninterruptedly to the periphery. From the
connective-tissue cells of the pia mater, processes pass into
the white matter and assist in completing the connective-tissue matrix
for the nervous elements.
Dorsal roots of the spinal nerves. Each root consists of
a single bundle of nerve
fibres, which suddenly bends at the periphery of the cord in order to
descend vertically through the white matter towards the dorsal horn;
the fibres divide into three sets, one to the dorsal commissure, a
second to the upper horn itself, and the third helps to form the dorsal
columns.
Ventral roots of the spinal nerves. Each ventral root
consists of three or four delicate threads, which may be traced to the
ventral cornua, which they reach after a vertical or very slightly
oblique course through the white matter. Other fibres arise from the
ventral columns, but these oblique fibres never extend to the median
plane.
Pigment is found distributed irregularly through a section
from any part of the spinal cord; it is increased in amount in those
parts in which there is an increased amount of grey matter. The
pigmentation is always found more marked in the lower parts of the
ventral horns than in other parts.
1.General description. From behind
forwards, the dorsal surface of the brain presents the
following parts for examination: the medulla oblongata, the
cerebellum, the optic lobes, the thalamencephalon, the cerebral
hemispheres, and the olfactory lobes.
The medulla oblongata is a direct continuation of the spinal
cord; it is wider anteriorly than posteriorly, and is separated in
front from the optic lobes by a vertical plate of nervous matter,
the cerebellum. The optic lobes are two symmetrical ovoid
bodies touching each other in the median plane, and together forming
the widest part of the brain. In front of the optic lobes is the
thalamencephalon, with a thick vascular membrane, the choroid plexus,
lying on its upper surface, and connected with the pineal gland; the
thalamencephalon extends forwards between the posterior ends of the
cerebral hemispheres. The cerebral hemispheres are two symmetrical
ovoid bodies, narrow in front, wider and slightly diverging behind:
each hemisphere is prolonged forwards to form an olfactory lobe.
The ventral surface has in front the olfactory lobes, then
the cerebral hemispheres, behind these the lamina terminalis,
the tuber cinereum, the optic chiasma, the pituitary body, the
crura cerebri, and lastly the medulla oblongata, in the
order here given.
The various cranial nerves (Figs. 102 and 103) may
be seen to arise as follows:—The olfactory nerve (I,
I′, L.ol′) arises directly from the anterior end and outer side of the
corresponding olfactory lobe, and from the cerebral hemisphere. The
optic nerve (To and II) arises, as the optic tract, from
the side of the brain below the optic lobe, whence it passes to the
chiasma on the under surface of the brain. The oculo-motor (III)
takes its origin from the ventral surface close to the median line
and between the crura cerebri. The pathetic or trochlear nerve
(IV) is attached to the dorsal surface between the optic lobes
and the cerebellum. The trigeminal nerve (V) arises
from the side and anterior part of the medulla oblongata. The
abducens (VI) arises behind the pituitary body close to
the median line from the ventral surface of the medulla halfway between
the sulcus and the origin of the vagus. The facial and
auditory (VII and VIII) nerves arise from the medulla
oblongata behind the trigeminal nerve, the facial being in front
of the auditory nerve. The glossopharyngeal (IX) nerve arises,
in common with the pneumogastric nerve (X), behind the auditory
nerve.
2.The several parts of the brain.
a. The medulla oblongata (Figs. 98,
102, and 103Mo) α. External form. The medulla
is limited behind by the origin of the first pair of spinal nerves, at
which point a very faint constriction is sometimes found: it extends
forwards as far as the cerebellum. It gradually widens as it
passes forwards until just before it reaches its anterior limit, where
it presents a shallow but sharp constriction. The dorsal surface
is characterised by the presence of a deep, triangular fossa, the
fourth ventricle (Fig. 98 S.r), (ventriculus
quartus, Stieda; sinus rhomboideus s. sinus triangularis,
Reissner; fossa rhomboidalis); the sides of the triangle are,
however, not quite straight, but are slightly bent outwards just before
they converge towards the posteriorly-directed apex; the base of the
triangle is formed by the cerebellum. By careful examination,
the ventricle is seen to be continued for a short distance under the
cerebellum, where it opens into the Sylvian aqueduct. In the
floor of the fourth ventricle is a well-marked median longitudinal
fissure (sulcus centralis), (Fig. 98 S). Into the
posterior part of the ventricle opens the central canal of the spinal
cord. As the fourth ventricle is formed by the white matter passing to
either side, and the simultaneous flattening of the grey matter, the
floor of the fourth ventricle is composed of grey matter.
Fig. 98.
Dorsal view of brain of Rana esculenta.
Ad
Choroid plexus.
C
Cerebellum.
f
Groove between cerebral hemispheres and olfactory lobes.
G
Opening in the roof of the third ventricle.
Gp
Pineal body.
Hc
Cerebral hemispheres.
I
Olfactory nerve.
Li
Wall of fourth ventricle.
L.ol
Olfactory lobe.
L.op
Optic lobe.
Mo
Medulla oblongata.
S
Longitudinal fissure of the fourth ventricle.
S.r
Fourth ventricle.
Tho
Thalamencephalon.
The fourth ventricle is closed in by a highly vascular membrane,
the choroid plexus of the fourth ventricle (plexus
choroideus ventriculi
quarti, Reissner; velum medullare posterius). The
blood-vessels of the plexus will be described together with the
other vessels of the brain (p. 162). They are supported by a
connective-tissue matrix, and the whole covered with flattened
epithelium, which in the fourth ventricle is ciliated and often
pigmented.
The ventral surface of the medulla oblongata
(Fig. 102Mo) has a median ventral longitudinal fissure, a
direct continuation of that of the cord; in the anterior part of the
medulla oblongata there is also to either side of this a lateral
fissure, continued on to the crura cerebri; these fissures
correspond to the positions of the two rami posteriores of the
internal carotid arteries; they are always well seen in microscopical
sections. The medulla oblongata is so intimately connected with
the pars commissuralis (pp. 149, 150) that the minute anatomy of
the two is best described at the same time.
β. Internal structure. Examined by means of serial sections,
the medulla oblongata is seen to have, in comparison with the
cord, an increased amount of grey matter; this is especially the case
in its anterior part. The floor and inner parts of the walls of the
ventricle are formed of grey matter, in which the largest-sized cells
have disappeared, to be replaced by medium-sized cells. Traced from
behind, the ventral horns of the cord are seen to increase in size and
to be more widely separated until they form two isolated masses, while
the dorsal horns gradually diminish; at the same time they are forced
outwards and upwards, until they lie under the floor of the ventricle,
and so extend to the pars peduncularis.
Grey matter. The substantia reticularis is not
present, but the septum medium extends forwards as far as
the pars peduncularis. The central canal extends upwards at
the expense of the tissue above it, and is here pear-shaped; at the
same time the dorsal
longitudinal fissure deepens until the two meet in the fourth
ventricle; beyond this point one cannot speak of dorsal and ventral
horns.
Small nerve cells are irregularly distributed throughout the
whole of the grey matter and cannot be grouped; the larger cells, on
the other hand, are arranged in distinct groups which have special
relations with the nerves arising from the part. Occasionally these
groups are not so isolated as usual; in this case processes of one
group can be traced into another group (Reissner). Of these groups the
chief are:
Fig. 99.
Transverse section through hinder end of Medulla oblongata
(magnified 30–80)52, from Stieda.
b
Inferior commissure.
f
Dorsal horns.
g
Ventral horns.
h
Fourth ventricle.
i
Nucleus centralis.
k
Isolated mass of grey matter in which longitudinal
fibres of the pneumogastric nerve course.
1. The nucleus centralis (upper inner group, Reissner),
nucleus medullae oblongatae, Stieda (Fig. 99 i), is
a group of cells found towards the hinder end of the medulla
oblongata, on either side of and below the central canal; the group
can be traced under the floor of the fourth ventricle to about its
middle. The cells are rounded or spindle-shaped, the processes directed
upwards, downwards, or outwards; their average size is 0·040–0·048 mm.
long by 0·020 mm. broad.
2. The auditory nucleus (nucleus acusticus, Reissner,
Stieda), (Fig. 100 n) is a large group of cells found in the
wall of the fourth ventricle opposite the point of origin of the
auditory nerve. The cells are rounded, pear-shaped, or of spindle
form, and interspersed between the nerve fibres; these cells have
an average length of 0·040 mm., and are about half as broad. The
fibres of the auditory nerve radiate from their superficial origin in
all directions through
the grey matter towards these cells, and evidently communicate with
them (Fig. 101p). One small group (Fig. 101r) passes
to a lower level than the rest, and is regarded by Stieda as the
true auditory centre. Köppen considers that the auditory nerve has a
threefold origin: (1) from small cells on the median surface of the
auditory area; (2) from the large cells between the above; (3) from a
group of free nuclei on the dorsal surface of the auditory area.
Fig. 100.
Transverse section through the Medulla oblongata at the point of origin of the abducens nerve,
from Stieda. (Magnified 30 x 80.)
h
Fourth ventricle.
m
Abducens nerve.
n
Auditory nucleus.
o
Abducens nucleus.
3. The trigeminal nucleus (nucleus trigeminus),
(Fig. 101q) lies in part beneath the auditory nucleus but
extends further forwards. It forms a rounded group of cells placed
under the outer angle of the grey matter. The cells are somewhat
crowded together, and are chiefly of an elongated spindle-form, with
their processes directed obliquely downwards and outwards. The fibres
of the trigeminal nerve separate into two groups; the upper group is
best traced in a horizontal section, the fibres curving round to join
the longitudinal fibres continued from the dorsal columns of the cord.
The fibres of the lower, smaller group pass transversely inwards to
the trigeminal nucleus.
According to Reissner the latter fibres are motor, the former sensory.
Probably other nerves are connected with the hinder part of this
group.
4. The abducens nucleus (Fig. 100 o). From its
superficial origin, the fibres of the abducens nerve may be traced
vertically upwards to a small, rounded, grey mass; at this point the
mass is somewhat isolated, but further forwards it may be traced
as belonging to the central grey matter; it contains small spindle
cells.
Fig. 101.
Transverse section of the Medulla oblongata, at the point of
origin of the auditory nerve, from Stieda. (Magnified 30 x 80.)
h
Fourth ventricle.
n
Auditory nucleus.
o
Abducens nucleus.
p
Auditory nerve.
p′
Ganglion of auditory nerve.
q
Hinder portion of trigeminal nerve.
r
Bundle of fibres arising from trigeminal nucleus and joining the auditory nerve.
5. The pneumogastric nucleus. The pneumogastric, with its
numerous irregular roots, arises from the side of the medulla
oblongata. The hindermost fibres can be traced as a small bundle,
passing almost transversely through the white matter to the outer
margin of the grey matter. The larger portion of the fibres is placed
in front of these; part of this seems to be directly continuous with
the longitudinal fibres of the white matter; a second part, however,
can be traced from the surface transversely through the white matter to the grey matter.
These latter fibres, together with those of the group first described,
do not arise from the grey matter in this part of the medulla
oblongata, but curve round and run backwards longitudinally through
the grey matter, thus forming a rounded bundle of fibres (Fig. 99k). Between these fibres are interspersed small nerve-cells and
nuclei which disappear as the fibres approach the white matter. The
vagus undoubtedly receives fibres from the grey matter throughout a
long course, and again receives a large bundle just before leaving the
grey matter. The more exact origin of the various fibres has not been
traced.
6. The nucleus magnus (Reissner and Stieda) is a very
peculiar group of cells placed on either side, in the most anterior
portion of the pars commissuralis, that is, immediately
underneath the valvula cerebelli. The large cells are arranged
in a transverse section in a single row so as to enclose a pear-shaped
space on either side, which has its long axis directed from above,
downwards and outwards, the narrower end being above. In longitudinal
section the line of cells is seen to be open in front. The space
enclosed by these cells is occupied by a granular ground-substance
which contains only few nuclei. Bellonci is of opinion that these
nuclei represent the corpora quadrigemina posteriora of higher
animals.
White matter. In the hinder part of the medulla
oblongata the arrangement of the white matter resembles that of
the white matter of the spinal cord; further forwards the white matter
of the dorsal surface commences to pass to either side, and ultimately
it forms the outer part of the walls of the fourth ventricle. The
fibres of the white matter of the ventral surface are unchanged in
direction as they proceed forwards. The fibres of the anterior part of
the medulla are thinner than those of the posterior portion (Stieda),
according to Reissner they gradually thin as they pass forwards. The
fibres are nearly all longitudinal, such transverse and oblique fibres
as are present being chiefly in connection with the various nerve-roots
and the commissures.
The commissura superior is naturally lost in consequence
of the opening of the central canal into the fourth ventricle; the
commissura inferior is increased in the anterior half and
decreased in the posterior half of the medulla oblongata; in
the latter the fibres become more and more oblique, and decussate very
freely; ultimately they seem to be either continued as longitudinal
fibres or to join the ganglia.
Near the pars commissuralis is a transverse arched band of
fibres, passing from the under surface of one half of the cord over the
ventral longitudinal fissure through the septum medium to the
under surface of the opposite half; part of the fibres are continued
upwards along the periphery to the cerebellum, part to the
nucleus magnus. Vertical, straight, or slightly arched fibres
are found in the walls of the fourth ventricle.
A section from the medulla oblongata has a larger amount
of pigment than a section from the spinal cord, and the
anterior portion of the medulla oblongata contains more than
the posterior portion. The pigment is chiefly found in a curved line,
placed in the lower and outer parts of the grey matter; the amount
present varies in different specimens.
b. The Cerebellum and Valvula
cerebelli.
α. External form. The cerebellum is a thin, semilunar
plate, which projects between the optic lobes and the fourth ventricle,
its base covering the most anterior part of the ventricle; the
posterior surface possesses a very faint median fissure (Reissner). The
valvula cerebelli (Velum medullare anterius, Reissner)
is the thin lamella which connects the anterior surface of the
cerebellum with the optic lobes.
β. Minute structure. By means of longitudinal, vertical
sections, the posterior surface of the cerebellum is seen to
be covered with epithelium; in the lower part of the surface this
is columnar or conical, above it is flattened: immediately beneath,
that is in front of this is a finely granular layer, with very
closely packed and granular nuclei. In front of these is a stratum of
nerve-fibres forming the second layer of the cerebellum.
Fig. 102.
Ventral view of brain of Rana esculenta.
Cho
Optic chiasma.
Hc
Cerebral hemispheres.
Hy
Pituitary body.
L.ol
Olfactory lobe.
L.ol1
Origin of olfactory nerve from the cerebral hemisphere.
Lt
Lamina terminalis.
Mo
Medulla oblongata.
To
Optic tract.
Tu.c
Tuber cinereum.
I 1st
root of the olfactory nerve.
I1 2nd
II
Optic nerve.
III
Oculo-motor nerve.
IV
Trochlear nerve.
VI
Abducens nerve.
V, VII, VIII
Trigeminal, facial, and auditory nerves.
IX, X, XI
Glossopharyngeal, pneumogastric, and accessory nerves.
Still more anteriorly is the third layer of the cerebellum, an
irregular double layer of large cells (Purkinje’s cells, Denissenko);
the cells have an average length and breadth of 0.040 mm. and 0.015 mm
respectively; they are pear-shaped or of spindle-form, and possess
usually two well-marked processes, one passing into the layer behind,
the other forwards into the anterior layer to be immediately described,
while other less distinct processes radiate irregularly in all
directions. The fourth and most anterior layer of the cerebellum is a
thick stratum of nerve fibres with numerous nuclei (0.006 to 0.008 mm.
diameter). The fibres are for the most part arranged transversely, but
some course in various directions. These fibres underlie the flattened
epithelium which covers the anterior surface of the cerebellum.
The fibres of the second layer course, for the most part, in an
almost vertical plane; they connect the cerebellum with the
optic lobes (processus cerebelli ad corpora bigemina) and with
other parts of the brain.
The fibres of the fourth layer receive numerous long processes
from the large cells of Purkinje; they form a large commissural
system, which can be followed ventrally on each side into the pars
commissuralis. A part of the fibres ends here in the grey matter,
a second portion enters the auditory area and forms a descending
auditory root, a third part joins the lateral columns (in the
medulla oblongata), and more anteriorly some join the ventral
columns. The descending fibres from the cerebellum, together
with the fibrae arcuatae found in the ventral columns, indicate
the presence of a pons Varolii. The fibres of this ventral
commissure decussate only on its dorsal surface (Köppen).
The Valvula cerebelli contains a few medullated fibres and
the roots of the trochlear nerves; these pass from the medulla
oblongata into the valvula cerebelli, cross in the median
line, and then proceed forwards as the trochlear nerves.
The pigment in the pars commissuralis is arranged in a
curved line similar to that found in the medulla oblongata, but
the line is shortened at either extremity, and consequently does not
extend into the cerebellum.
c. The optic lobes and Crura
cerebri. (Corpora geminata and Pars peduncularis,
Reissner; Lobus opticus, Stieda; Vierhügel, Tiedemann; Vierhügel
(Zweihügel) and Pedunculi cerebri, Schiess; Mesencephalon,
Huxley.)
α. External form (Figs. 98, 102, 103 L.op). The optic
lobes are two prominent ovoid bodies placed immediately in front
of the cerebellum, and connected with it by the valvula
cerebelli; posteriorly they touch each other in the median plane,
while anteriorly they diverge and thus constitute the widest part of
the brain; in the angle thus formed is the thalamencephalon. The optic
lobes are always more darkly pigmented than any other part of the
central nervous system.
Fig. 103.
Lateral view of brain of Rana esculenta.
Ad
Choroid plexus.
C
Cerebellum.
Gp
Pineal body.
Hc
Cerebral hemisphere.
Hy
Pituitary body.
L.ol
Olfactory lobe.
L.ol1
Disc at origin of second root.
L.op
Optic lobe.
Mo
Medulla oblongata.
Tho
Thalamencephalon.
To
Optic tract.
Tu.c
Tuber cinereum.
I 1st
root of the olfactory nerve.
I1 2nd
II
Optic nerve.
IV
Trochlear nerve.
V
Trigeminal nerve.
VII
Facial nerve.
VIII
Auditory nerve.
IX, X, XI
Glossopharyngeal, pneumogastric, and accessory nerves.
The Crura cerebri are two columns of white matter, placed
beneath the optic lobes, and partly hidden by the pituitary gland. At
their junction with the medulla oblongata, or rather with the
pars commissuralis, is a very slight transverse fissure; at
the same point the ventral longitudinal fissure is interrupted by an
extremely small grey tubercle (Stieda).
β. Internal structure. From the anterior extremity of
the fourth ventricle a canal, the Sylvian aqueduct (Aqueductus
Sylvii, iter a tertio ad quartum ventriculum), may be traced
forwards under the cerebellum, in the median line of this section of
the brain. At about opposite the middle of the length of the optic
lobes the canal is dilated and communicates with the cavities or
ventricles (Ventriculi lobi optici, Stieda) enclosed by these;
a general cavity is formed, which in transverse section has something
of the form of the letter T. The roof of the cavity is thinner than the
floor; this is especially the case in the median plane opposite the
superior longitudinal fissure between the optic lobes; the floor is
thinned in the middle line by the descending portion of the cavity. The
cavity of each optic lobe extends both forwards and backwards beyond
its point of communication with the dilated Sylvian aqueduct, hence in a transverse section
taken in front of this point (Fig. 104 h′) the cavity of either
side appears to be isolated; in a horizontal and longitudinal section
(Fig. 105Aq) the general arrangement of the parts may be well
seen.
Fig. 104.
Transverse section through the anterior portion of the optic lobes
opposite the origin of the motor-oculi nerve; from Stieda (magnified
30–80).
h
Lower portion of cavity.
h′
Lateral portion of cavity.
u
Ganglia of oculi-motor nerve.
v
Oculo-motor nerve.
w
Large cells of the optic lobe.
x
Roof of optic lobe.
y
Posterior commissure.
z
Anterior diverticulum of the cavity.
The grey matter is chiefly arranged in a layer so as to surround
the cavity (Fig. 104), this layer being deeper on either side of the
descending portion of the cavity than elsewhere. For the rest the
grey matter is much interspersed among the white matter, except at
the circumference of the section, which is entirely formed of white
matter. It contains a large number of small cells, of which the nuclei
are alone visible; in the parts mentioned where the layer is most
marked these cells are arranged in oblique rows, between which pass
fine bundles of medullated fibres (Fig. 104, between u and
h′). A group of large cells (Fig. 104 u) is found on
either side of the middle line and under the floor of the cavity; the
cells are about 0.032 mm. long, and 0.016 mm. broad; the oculo-motor
nerve may be traced to this group, which is the oculo-motor
nucleus. A small commissure of decussating fibres connects the
nuclei of opposite sides (Köppen).
The substance of the roof of the optic lobes (Fig. 104 x)
is arranged in very distinct layers: above is a layer free from
cells; the fibres
of this layer are extremely fine and delicate, and have not been
accurately traced; under this is a nuclear layer; a second layer of
fine fibres follows, which is succeeded by a second layer of nuclei in
a granular matrix, and lastly epithelium (Stieda). (Reissner describes
three nuclear layers in Bufo variabilis, and this is also the
case in R. temporaria, G. H.; according to Köppen, the number
is variable.) In the anterior portion of the roof a distinct bundle
of fibres may be made out; externally they bend downwards, and can be
traced as far as the crura cerebri.
Fibres corresponding with the commissural and arched fibres of the
medulla oblongata are continued into the hinder portion of the
crura cerebri, the change from pars commissuralis to
crura cerebri being very gradual. The longitudinal white fibres
are much increased in number in the crura cerebri, and a portion
of them can be traced to the nucleus magnus.
A peculiar irregular group of large cells (Fig. 104 w)
is found where the roof meets the crura cerebri; these vary
in diameter from 0.024 to O.040 mm., and their processes are very
indistinct.
The fibres of the optic tracts arise, according to Köppen, from two
different origins: the one lies on the hindermost part of the optic
lobe; from this point the fibres curve downwards and forwards to form
longitudinal fibres; this root Köppen names the ventral ascending root,
it can be traced through the entire length of the organ. The second
root arises in the tectum opticum near the longitudinal fissure;
it is smaller than the foregoing, and has been named the dorsal
ascending optic root. The fibres of these two roots unite anteriorly
near the posterior commissure, at which point they receive additional
fibres (Köppen). Bellonci traces a large proportion of the fibres of
the optic tract to the nucleus magnus, which pair of nuclei,
as already stated, he regards as the posterior pair of corpora
quadrigemina of higher animals.
The pars peduncularis is the continuation of the pars
commissuralis underneath the optic lobes; a gelatinous mass
lying in the median plane and containing numerous isolated nuclei
(Ganglion interpedunculare) divides it into two lateral halves.
The longitudinal fibres are ungrouped posteriorly, but arranged in
rounded strands in the middle, especially dorsally; anteriorly the
grouped arrangement is lost and the number of fibres diminished.
The pigment of this region has, in a transverse section, an
outline which has something the form of a lyre; commencing on either
side of the median line, and underneath the deepest portion of the
cavity, the pigment
line passes, first, directly outwards; then suddenly turns upwards and
slightly outwards parallel with the wall of the deeper part of the
cavity; it then curves outwards to pass below the cavity of the optic
lobe, where it divides, one portion passing outwards, the other between
the Sylvian aqueduct and the ventricle of the optic lobe.
d. The Thalamencephalon (Huxley),
(Lobus ventriculi tertii, Stieda; Thalami optici,
Reissner; Thalamus opticus s. Lobus ventriculi tertii, Stannius;
Ganglien der Haemisphaeren, Carus).
α. External form. From above (Fig. 98Tho) the
thalamencephalon is seen as a lozenge-shaped mass lying in front of the
optic lobes, and behind and between the diverging posterior ends of
the cerebral hemispheres; it is covered by a thick vascular membrane,
the choroid plexus, through which passes the pedicle of the
pineal body (Glandula pinealis). On removing the choroid
plexus a small aperture is seen in the roof of the thalamencephalon,
connecting the hollow pedicle of the pineal gland with the third
ventricle. The ventricle appears as a narrow slit in the median
line, its walls being formed by the optic thalami. By pressing aside
the cerebral hemispheres the posterior commissure (Commissura
posterior) may be seen lying quite in front and deep in the cleft
of the ventricle. Immediately behind the pedicle of the pineal body is
a slight but well-marked depression (Fig. 98G), the origin of
which has not been investigated (Wiedersheim).
The choroid plexus is continued forwards between the cerebral
hemispheres (Figs. 98, 103 Ad) for some distance, and terminates
in a fine thread of connective-tissue.
The under surface of the thalamencephalon (Fig. 102) is divided
into two parts by the optic chiasma (Cho): the anterior
portion (Lt) is the lamina terminalis (Substantia
cinerea anterior); the posterior (Tu.c) the tuber
cinereum. The lamina terminalis is bounded on either side
by the cerebral hemispheres. The tuber cinereum (Figs. 102,
103Tu.c) is a small median swelling immediately behind the
optic chiasma, and caused by the depression of the floor of the
third ventricle to form the infundibulum (Diverticulum
infundibuli, Reissner).
Fig. 105.
Horizontal section through the brain to show the ventricles.
Aq
Ventricles of optic lobes and the aqueduct of Sylvius.
Dv
Third ventricle.
MF
Foramen of Monroe.
Sv
Lateral ventricle.
Vv
Fourth ventricle.
The pituitary body (Hypophysis cerebri) is a flattened
sac, placed behind the tuber cinereum and continuous with it by
means of the infundibulum.
β. Internal structure. The aqueduct of Sylvius, after
communicating with the ventricles of the optic lobes, again contracts
(Fig. 105), but still remains somewhat larger than before. In the
thalamencephalon the Sylvian aqueduct opens into the third ventricle,
which gradually assumes the form of a vertical slit with the walls
bulging slightly outwards in their upper parts. The thin roof of this
ventricle, where complete, contains a band of transverse fibres. The
floor is depressed both before and behind the part immediately above
the optic chiasma, the posterior depression lying above the tuber
cinereum, which here descends towards the infundibulum: a
transverse section through this portion of the third ventricle has
the form of a square standing on one angle, the superior angle being
produced into the vertical slit of the general cavity. The anterior
depression is formed by the general cavity being prolonged downwards
and forwards to the lamina terminalis in the form of a narrow
and shallow slit.
The white and grey matter of the thalamencephalon are only so far
distinct in that the portion immediately surrounding the cavity is
darker than the rest of the section. In the immediate neighbourhood
of the cavity are many small cells and nuclei, which become scarcer
further from the ventricle; they are arranged in rows, separated by a
fibrillated matrix. On either side is a distinct bundle of longitudinal
fibres, the ‘round bundle’ of Köppen, which come from the optic lobes
but appear to arise from either the pars commissuralis or
the medulla oblongata, and to receive additional fibres from
the optic thalami; they pass forwards to the base of the cerebral
hemispheres (Stieda). A second set of longitudinal fibres arises in
the substance of the tuber cinereum and passes forwards to the
hemispheres (strand of the Tuber-cinereum and Thalamus,
Köppen); this band, together with the ‘round bundle,’ form a crus
cerebri (Köppen).
The commissural fibres of the thalamencephalon are: (1) a
commissura transversa Halleri in the posterior portion of
the organ; (2) an optic commissure, consisting of fibres arising
from the thalamencephalon (thalamencephalic root) and crossing the
median line to join the optic tract of the opposite side; (3) a
probable commissure between the optic nerves just in front of the
chiasma opticorum; the existence of the latter is not yet
proved beyond doubt;
(4) the large commissure of transverse fibres found in the roof of
the third ventricle; whether the fibres decussate or not is uncertain
(Köppen).
The fibres of the large commissure of the roof are, in part,
continued into the strand of the Tuber-cinereum above mentioned,
and thus conducted to the posterior parts of the hemispheres (Köppen).
A group of fibres (Meynert’s band, Köppen) is found in each lateral
wall of the third ventricle; they pass from the region of the
nucleus parvus downwards in a curved course almost parallel with
the external border of the thalamencephalon.
A distinct group of cells may be noted in this section of the
brain, an arciform or circular group (Nucleus parvus, Reissner;
ganglion of the habenula, Köppen) of large spindle cells
(average diameter 0.016 mm.), placed under the upper border close to
the third ventricle; the group extends alongside the whole length of
the ventricle. A second group lying in the middle and posterior parts
beneath the ventricle, Köppen names the ‘ventral nucleus’ of the
thalamencephalon.
The pigment in the posterior part of the thalamencephalon is
arranged in a manner similar to that in the optic lobes and crura
cerebri; anteriorly where the third ventricle is prolonged forwards
and downwards the arrangement is different; the pigment lies in a
curved line above the process of the ventricle, with its concavity
directed downwards, each end bifurcating, in order that one branch may
pass upwards, the other downwards.
The pineal body53 is a small vesicle placed underneath the
skin above the fronto-parietal bones; in the embryo it is connected
with the third ventricle by means of the pedicle54 already mentioned; the
skin covering the body is always paler than the surrounding skin,
and the usual cutaneous glands are absent in this part; the paler
spot on the head may always be found, but is more distinct in
Rana temporaria than in Rana esculenta. The structure
on the roof of the third ventricle, which is usually known as the
pineal body, is nothing more than a thickened portion of the choroid
plexus, and consists of a group of convoluted vessels surrounded by
pia mater, which is described by Wyman as being covered with
ciliated epithelium (R. pipiens). The true pineal body is a
small body with an outer connective-tissue capsule, derived from the pia mater;
this encloses an irregular mass of epithelial cells; according to
de Graaf a twig of the ramus supramaxillaris reaches it
subcutaneously, and a blood-vessel accompanies the pedicle through the
foramen parietale. According to Darkschewitsch, the pedicle
contains medullated nerve-fibres derived directly from the brain.
The pituitary body (Figs. 102, 103Hy) when examined
with a lens is seen to consist of two portions: an anterior, superior,
and smaller white portion, and a larger, inferior, posterior, and
reddish portion. The anterior portion has the form of a very small,
flat disk, and is enclosed in a connective-tissue capsule which sends
in larger and smaller processes. In either transverse or longitudinal
section it is seen to be formed of two horizontal layers separated
by a line of blood-vessels and connective-tissue. The upper layer
consists of a granular and reticular matrix, containing many nuclei
(averaging 0.006 to 0.010 mm. diameter), and divided into irregular
rounded or polyhedral spaces by bands of tissue derived from the
capsule. This layer is more vascular than the lower. The lower layer
consists of a mass of clear, nucleated rounded or polyhedral cells
(0.016 to 0.024 mm. in diameter; nuclei from 0.008 to O.012 mm. in
diameter, Reissner), pierced by very fine connective-tissue septa
derived from the capsule. The septa are, for the most part, vertical
and longitudinal (Reissner), the blood-vessels are very few.
Fig. 106.
Section through the lower division of the pituitary body (magnified
360 times); from Stieda.
a
Tubes lined with epithelium.
b
Blood-vessels.
The posterior larger portion of the pituitary body (Fig. 106) is
also compressed from above downwards, and in transverse section as an
oval outline. It possesses an external thin connective-tissue capsule,
which sends in fine processes to support a mass of convoluted tubes,
between which course a few blood-vessels; these tubes possess an outer
nucleated basement-membrane, and are lined with a single layer of
more or less cylindrical epithelium, which entirely fills the tube;
hence the tubes possess no lumen. The tubes are from 0.04 to 0.08 mm.
in diameter; the cells are clear or granular, and possess distinct,
rounded nuclei.
e. The Cerebral Hemispheres
and Olfactory Lobes. The cerebral hemispheres (Lobi
hemisphaerici, Stieda; Lobi cerebrales, Reissner;
Centralmasse des Geruchssinns, Carus; Hemisphaeren des grossen Hirns,
Tiedemann; Grosse Hemisphaeren, Schiess; Prosencephalon, Huxley).
The olfactory lobes (Tubercula olfactoria, Stieda; Lobi
olfactorii, Reissner; Riechkolben, Schiess; Rhinencephalon,
Huxley).
α. External form (Figs. 98, 102, 103Hc and
L.ol). The two cerebral hemispheres form together the largest
section of the brain; from above they are seen to be separated by a
dorsal longitudinal fissure, which is here well marked: each hemisphere
is an ovoid body with the smaller end directed forwards and continuous
with the corresponding olfactory lobe; the posterior end forms one
half of the anterior boundary of the thalamencephalon. The olfactory
lobes are two elongated, rounded bodies directly continuous with the
corresponding cerebral hemispheres, and likewise partially separated in
the median line by a dorsal longitudinal fissure: at the point of union
of the cerebral hemispheres and olfactory lobes is a faintly marked
transverse depression.
On the ventral surface the parts are again marked off from one
another by a corresponding ventral longitudinal fissure and a
transverse groove; the two longitudinal fissures being continuous,
anteriorly, between the olfactory lobes. The cerebral hemispheres
appear to be more widely separated behind (Fig. 102) than is the case
on the dorsal surface, and in the space so formed is the lamina
terminalis (Lt). Seen from the side, the slight depression
of the upper surface, between the cerebral hemispheres and the
olfactory lobes, is seen to be continued downwards and slightly
backwards to join the corresponding groove on the inferior surface.
The longitudinal fissures are shallow and do not meet, except at
one point, at about the middle of the cerebral hemispheres (Fig. 105).
The olfactory bulbs arise superficially (Figs. 102, 103I′ and
L.ol) from the whole length of the olfactory lobe, between the
anterior extremity (I′) and the posterior (L.ol), where
they are also attached to the cerebral hemispheres.
β. Internal structure. The cerebral hemispheres and olfactory
lobes are hollow, the common cavity of each side being known as the
lateral ventricle (Ventriculus lateralis); these ventricles
communicate with each other, and with the third ventricle (Fig. 105).
The narrow aperture by which the lateral ventricles communicate is
known as the Foramen of Monro(MF); it communicates
with the third ventricle posteriorly, and with the space between the
cerebral hemispheres anteriorly, and thus forms a common cavity (Ventriculus communis
loborum hemisphaericorum, Stieda).
Fig. 107.
Transverse section through the hinder portion of the cerebral
hemispheres; from Stieda.
c
Lateral ventricle.
c′
Common ventricle of Stieda.
d
Longitudinal fibres.
f
Anterior prolongation of the third ventricle.
Fig. 108.
Transverse section near the middle of the cerebral hemispheres.
c
Lateral ventricle.
d
Groove on the inner wall.
In general terms, each ventricle may be said to be a semilunar
cavity, prolonged backwards and forwards (Fig. 107 c); the outer
wall is always more or less concave, while the inner varies according
to the part of the hemisphere examined. At the anterior and posterior
extremities the inner wall is convex and bulges into the cavity
(Fig. 107); in the middle portion of the cavity the inner wall presents
a longitudinal groove (Ventriculi lateralis cornu internum,
Reissner), (Fig. 108 d), and consequently the inner wall has
here two rounded masses, an upper and a lower (Corpus striatum,
Wiedersheim), projecting into it. By tracing them backwards and
forwards, the lower swelling is seen to increase at the expense of
the upper, while at the same time the lateral grooves disappear; the
outline of the cavity shown in Fig. 107 is then obtained. The roof
of the ventricle is arched and broader than the floor, which, in the
middle part, exists only as a vertical slit (Fig. 108), (Ventriculi
lateralis cornu inferius, Reissner): towards the anterior and
posterior extremities it widens and becomes shallower (Fig. 107).
The cerebral hemispheres and olfactory lobes are composed of a fine
granular matrix, enclosing spindle-shaped, rounded, or pear-shaped
nerve cells and nuclei, and containing very fine fibres. The cells
(Fig. 109 b) are more numerous towards the ventricle, and
somewhat sparse towards the superficial surface. The cells are of
two chief sizes, the smaller and more numerous average 0.004 mm. to
0.008 mm. in diameter; they are found chiefly in the deeper portions
of the section, but also form a very thin irregular layer beneath
the pia mater: the larger cells have an average diameter
of 0.010 mm. to 0.012 mm., and are placed towards the periphery,
especially in the dorsal part of the inner wall.
Fig. 109.
From a transverse section through one of the cerebral hemispheres; from Stieda.
(Magnified 360 times.)
a
Epithelium of lateral ventricle.
b
Nerve cells.
c
Connective-tissue processes from the Pia mater.
In this irregular collection of cells the following centres
have been described: (1) The nucleus, through which the corpus
callosum passes (Köppen); (2) the lower internal or median
cell-area (Osborne),
situated above the foregoing nucleus in the posterior and middle
portions of the hemispheres; (3) the upper internal cell-area (Osborne)
is the area of large cells in the dorsal part of the inner wall; (4)
the Corpus striatum (Osborne) is a mass of cells between the
corpus callosum and the commissura anterior; Köppen
doubts the correctness of Osborne’s opinion, and suggests that a
group of cells found in the wall of the third ventricle in front of
‘Meynert’s band’ may perhaps be a corpus striatum.
A bundle of longitudinal medullated nerve-fibres, the ‘round
bundle,’ is found on either side of the median line (Fig. 107d), and near the lower border in the posterior portion of this
region; these fibres can be traced from the posterior section of the
thalamencephalon; they diminish in number as they course through the
base of the cerebral hemispheres, and are ultimately lost in the lower
anterior part of the outer walls. A second strand of longitudinal
fibres is the continuation of that of the Tuber-cinereum above
described, which can be followed to the outer wall of the posterior
part of the ventricles, and to the anterior commissure.
The commissures are: (1) The corpus callosum, a large
bundle of transverse fibres, seen best in a transverse section, at
the point of junction between the lamina terminalis and the
cerebral hemispheres, forming an arch over the roof of the anterior
prolongation of the third ventricle. The fibres course to the inner
and anterior parts of the hemispheres, and are situated chiefly behind
the foramen Monroi. To this commissure must be added those
fibres which unite the two olfactory lobes, and possibly the fibres
(Commissura posterior) found in the roof of the third ventricle
(Köppen). (2) The Commissura anterior (Stieda), a smaller set,
found immediately under
the floor of the common ventricle, forming in their course outwards a
curve, with the concavity directed downwards. This commissure connects
the ‘round bundles’ of opposite sides, and those fibres coursing with
the ‘round bundles’ to the olfactory lobes constitute the pars
olfactoria of the commissura anterior. To this commissure
must also be added some fibres found on the ventral surface of the
commissura anterior and connecting the two strands of the
Tuber-cinereum; an unusually coarse strand of these fibres can
be traced to the inner wall of the ventricle, and is termed the pars
olfactoria interna by Osborne.
The general structure of the olfactory lobes resembles that of the
hemispheres; the olfactory nerves arise each by two roots, an outer
and inner. The outer root arises from the outer wall near the groove
between the corresponding hemisphere and olfactory lobe; the inner or
anterior root arises from the anterior surface of the olfactory lobe.
Both roots have a peculiar method of origin from the extremely fine
fibrillar network of the matrix (Nerve-fibre-conglomerate, Köppen), in
which are rounded dark bodies known as ‘glomeruli;’ in the ‘glomeruli’
dark points and nuclei are seen, between larger and smaller bands of
nerve-fibres. Köppen holds that all the sensory nerves of the brain
arise in a similar manner.
A decussation takes place between the two inner roots of the
olfactory nerves; possibly the external roots are connected by means of
the commissura anterior.
Very little pigment exists in the cerebral hemispheres or
olfactory lobes, the greater portion is found in the upper part of the
inner walls of the cerebral hemispheres.
The epithelium of the ventricles of the brain, like
that of the central canal of the spinal cord, consists of
conical cells with their bases directed towards the cavity, and their
apices directed peripherally and prolonged into distinct processes
(Figs. 104, 109 a). In such situations, as the choroid
plexuses, where nervous tissue is absent and the cavity is completed
by pia mater alone, the epithelial cells are flattened.
Everywhere else it is ciliated55 and possesses distinct round nuclei which
are as broad as the cells themselves. The epithelium is somewhat
irregularly and sparsely pigmented; the ventral parts of the central
canal of the spinal cord, of the fourth ventricle, and of the Sylvian
aqueduct are always more pigmented than the dorsal parts.
PLAN OF THE ARRANGEMENT OF THE NERVE-FIBRES OF THE CENTRAL
NERVOUS SYSTEM, ACCORDING TO KÖPPEN.
Nerve fibre strands in the white matter.
Nerve-fibre strands in the grey matter.
Commissures.
Nerve-fibres which connect the strands of white fibres.
The spinal cord.
1.
The ventral columns, including the strand of coarse fibres.
1.
Longitudinal fibres in the dorsal portion of the grey matter.
1.
The ventral commissure.
2.
The lateral columns.
2.
The dorsal commissure (rudimentary).
3.
The dorsal columns, including Goll’s column.
The medulla oblongata.
1.
The ventral columns, including the strand of coarse fibres and dorsal longitudinal strand.
1.
Longitudinal fibres of the Substantia gelatinosa Rolandi, and which give off ascending vagal and trigeminal roots.
1.
The ventral commissure: a. Dorsal portion. b. Ventral portion.
1.
The fibrae arcuatae.
2.
The lateral columns, which give off an ascending (recurrent) vagus-root.
2.
(The dorsal commissure is wanting.)
3.
The dorsal columns. a. Ascending trigeminal root. b. Auditory root. c. Descending auditory root.
The cerebellum and the pars commissuralis.
1.
The ventral columns, including the dorsal longitudinal strand (the strand of coarse fibres has disappeared).
1.
Longitudinal fibres of the grey matter. Small ascending trigeminal root.
1.
The ventral commissure.
1.
The fibrae arcuatae.
2.
The lateral columns (each receives a strand from the cerebellum).
2.
The dorsal commissure, cerebellar commissure and trochlear decussation.
3.
The dorsal columns. a. Large ascending trigeminal root. b. Descending auditory root.
The optic lobes.
1.
The ventral columns, including the dorsal longitudinal strand.
(Wanting.)
1.
The ventral commissure.
1.
The fibrae arcuatae.
2.
(The lateral columns cannot now be distinguished from the ventral columns.)
2.
The dorsal commissure. a. Commissura posterior. b. Marginal commissure.
3.
The dorsal columns: two ascending opticus-roots.
The thalamencephalon and the cerebral hemispheres.
1.
The ventral and dorsal columns. a. Fibres from the optic lobes. b. The ‘round bundle.’ c. The ‘Thalamus-Tuber-cinereum strand.’
(Wanting.)
1.
The ventral commissure: a. Commissura transversa Halleri. b. Commissura anterior.
1.
The fibrae arcuatae.
2.
The dorsal commissure, the corpus callosum.
1. The Pia mater closely invests the whole of the brain
and spinal cord; it may, in fact, be regarded as the flattened,
outermost layer of the connective-tissue material which supports the
nervous elements; fine processes (Fig. 109c) pass radially
from its inner surface to join the general connective-tissue matrix
or neuroglia. It is usually pigmented, those portions covering the
optic lobes and spinal cord being especially deeply pigmented: on the
cerebral hemispheres it contains very little pigment; at times, indeed,
in R. temporaria, pigment is absent from this part.
The pia mater is continued on to the choroid plexuses and
pituitary body, and on to the pineal body by means of the pedicle;
the membrane is very vascular, and forms, especially for the cerebral
hemispheres and the olfactory lobes, a very important source for the
direct supply of blood-vessels.
2. The Dura mater, or lining membrane of the cranial cavity
and vertebral canal, is a connective-tissue membrane containing many
very much branched, pigmented cells. This membrane is not so deeply
pigmented as the pia mater, except in that portion covering the
cerebral hemispheres and the olfactory lobes, which is much darker than
the corresponding portion of the pia mater.
3. The arachnoid membrane is the layer of endothelial cells
covering the inner surface of the dura mater: by means of the
blood-vessels and nerves, etc., it is continued on to the pia
mater of the spinal cord and brain, which it in like manner closely
invests. Masses of calcareous crystals are found between the
epineurium and the arachnoid (Wiedersheim) on each spinal nerve at its
exit from the intervertebral foramen, also on the trigeminal nerves in
the cranium. Additional smaller and more irregular masses are found on
the dorsal part of the dura mater of the spinal cord.
The arteries of these organs are derived from the internal carotids
and the arteriae vertebrales. As soon as the internal carotid
arteries reach the cranial cavity each divides into two branches,
an anterior (Ramus anterior, Schöbl56) and a posterior (Ramus
posterior, Schöbl); the anterior branches course forwards on
the lower part of
the surface of the brain as far as the anterior portion of the
thalamencephalon, where they again divide; one division, arteria
lobi hemisphaerici inferior externa (Schöbl), continues forwards
along the outer surface of the cerebral hemisphere and of the olfactory
lobe as far as the olfactory bulb, where it may still be distinctly
seen; it gives off branches to the adjacent parts in its course
forwards. The vessels of the two sides communicate with each other
by means of delicate transverse vessels (Arteriae communicantes
anteriores). The second division, arteria lobi hemisphaerici
superior interna (Schöbl), of the ramus anterior courses on
the thalamencephalon to the dorsal surface, gives a large branch to the
choroid plexus of the fourth ventricle, and runs forwards in the dorsal
longitudinal fissure; it supplies vessels to all the neighbouring
parts.
The rami posteriores converge as they course backwards,
and ultimately unite to form an arteria basilaris, which is
continued in the median line of the under surface of the spinal cord as
the arteria spinalis anterior. The ramus posterior gives
off, in its course, many small vessels to the neighbouring parts, and
two larger vessels on either side, one of which, the arteria lobi
optici (Schöbl), is distributed to the optic lobes, while the other
passes to the pituitary body.
The branches of these vessels form a network in the pia
mater, from which the nervous tissue is supplied; they also send
numerous branches directly into the brain and cord, and these have a
similar arrangement for all parts of the brain with the exception of
the cerebral hemispheres and olfactory lobes; more or less vertical
branches arise from the posterior parts of the upper borders of the
rami anteriores, from the whole of the rami posteriores,
and from the arteria basilaris; these course upwards from
their place of origin into the corresponding part of the brain, give
off a few branches in the white matter, and then branch freely,
and at somewhat sharp angles, in the grey matter. In the pars
commissuralis a large branch may be traced from the ramus
posterior on either side upwards into the cerebellum almost to its
upper border. The vessels of the cerebral hemispheres and olfactory
lobes seem to possess no other definite arrangement than that described
above. The grey matter seems, on the whole, to be more vascular than
the white; the vessels of the latter are chiefly arranged radially to
the surface, and run in courses which are more or less straight; the
vessels of the grey matter are more irregular and sinuous.
The Arteria spinalis anterior courses along the whole length
of the spinal cord, giving off lateral branches and communicating
with rami
spinales (branches of the Arteria vertebralis). These
branches form a plexus in the pia mater, from which vessels pass
at irregular points into the cord; one set of small vessels, described
by Reissner, pass in a straight course from the superior longitudinal
sinus towards the substantia reticularis, where they divide.
Other branches pass directly from the arteria spinalis anterior,
through the ventral longitudinal fissure, and there divide; the twigs
as a rule avoiding the septum medium and passing in greater part
towards the ventral horns. The vessels in the white matter are for the
most part radial and straight, while in the more vascular grey matter
they are irregular and more sinuous in their course.
Fig. 110.
Diagram to show the Vena spinalis posterior, the Venae
spinales superiores, and the origin of the Vena jugularis
interna.
H
Hemispheres.
ji
Internal jugular.
op
Optic lobes.
mo
Medulla oblongata.
spp
Vena spinalis posterior.
The choroid plexus of the third ventricle (Plexus choroideus
ventriculi tertii, Reissner) lies, as already described, on
the roof of the third ventricle; it is somewhat triangular in form
(Plexus venosus triangularis, Schöbl), and is evidently a
prolongation of the pia mater, with an increased supply of
vessels. It receives, at its anterior angle, veins from the cerebral
hemispheres and the adjacent parts. The under surface is covered with
a layer of ciliated pavement epithelium. At the posterior angles of
the plexus the veins communicate on either side (Fig. 110) with the
anterior lateral prolongation of the vena spinalis superior,
and with the internal jugular vein. The small body usually named the
pineal body, and placed on the roof of the ventricle, is only a small
thickened portion of the plexus, and consists of a group of convoluted
blood-vessels. This plexus sends a considerable bunch of vessels into
the upper part of the third ventricle. The choroid plexus of the fourth
ventricle (Plexus choroideus ventriculi quarti, Reissner) is a
triangular membrane, slightly attached to the borders of the fourth
ventricle. Its upper surface is flat and bounded at either side by a
large vein, the vena spinalis superior; anteriorly it is bounded
by the cerebellum. The under surface is not flat; in the middle
line is a slight furrow corresponding to the position of a median
vessel, which may, when injected, be seen from the dorsal surface; from
it a number of short
vessels pass outwards and slightly backwards to the outer border. The
connective-tissue between these vessels is pushed down into the cavity;
in this manner one obtains a double row of flattened villous-looking
bodies, which frequently have their tips pigmented. The under surface
of the plexus is clothed with flattened, ciliated epithelium.
On either side of the pituitary body is another small venous
plexus (Plexus lateralis, Schöbl); it communicates above with
the posterior angle of the choroid plexus of the third ventricle;
externally, with the internal jugular vein; and internally with its
fellow of the opposite side by more or less irregular transverse
vessels, which, together with a median vein from the fissure between
the cerebral hemispheres, form an irregular circulus venosus
around the pituitary body. These plexuses receive blood from the lower
part of the cerebral hemispheres, the thalamencephalon, the optic
lobes, and from the pituitary body. The veins of the spinal cord open
into the dorsal, vena spinalis posterior (Fig. 110 spp),
which bifurcates at the posterior angle of the fourth ventricle, one
division passing to either side and forming, as already described,
the outer border of the choroid plexus; anteriorly it opens into the
internal jugular vein (Fig. 110 ji).
The blood-vessels, both arteries and veins, are irregularly
pigmented, both on the surface and in the interior of the central
nervous system; those of the cerebral hemispheres and olfactory lobes
have very little or no pigment.
DESCRIPTION OF THE FIGURES ON PLATE I.
Fig. 111. Dorsal view of the orbit, etc.; deep dissection.
c
Course of the palatine nerve.
II
Optic nerve.
db
Fibrous plate.
III
Motor oculi nerve.
dm
M. depressor maxillae.
IV
Trochlear nerve.
ef
Terminal branches of the ophthalmic nerve.
Vb
R. palatinus
of the trigeminal nerve.
F
Facial with R. anterior of the glossopharyngeal.
Vc
R. maxillo-mandibularis
g,g,g
Terminal twigs of the ophthalmic nerve.
Vc′
R. maxillaris
h
Muscular twigs of the Ram. maxillaris.
Vd
R. mandibularis
ics
M. intertransversar. capitis superior.
Ve(VII) Facial nerve.
ii
Twigs of upper eyelid.
Vg
Gasserian ganglion.
K
Terminal twigs of the Ram. maxillaris.
VN
Trigeminus.
la
M. levator anguli scapulae.
VS
Sympathetic nerve.
pt
M. pterygoideus.
VI
Abducens nerve.
sc
M. sterno-cleido-mastoideus.
VII′
Facial nerve.
Sp
Sympathetic nerve.
VIII
Auditory nerve.
t
M. temporalis.
X1
Ram. anterior of the glossopharyngeal.
tr
Nasal branch.
X2
Glossopharyngeal nerve.
*
Union of facial nerve with Ram. anterior of the glossopharyngeal nerve.
X3
Pneumogastric nerve.
I
Olfactory nerve.
XG
Ganglion nervi vagi.
XI
Accessory nerve.
Fig. 112. Dorsal view of the orbit, etc.; superficial dissection.
e
External branch of the ophthalmic nerve.
Va
Ophthalmic nerve.
f
Internal branch of the ophthalmic nerve.
Vc
R. maxillo-mandibularis.
g,g,g
Terminal twigs of the ophthalmic nerve.
Vc′
R. maxillaris of the trigeminal nerve.
II
Optic nerve.
Vd
R. mandibularis of the trigeminal nerve.
III
Motor oculi nerve.
VI
Abducens nerve.
IV
Trochlear nerve.
VI′
Ciliary nerves.
Fig. 113. View of roof of mouth; mucous membrane, etc., removed.
a
Branch of the Ram. palatinus to the Harderian gland.
ri
M. rectus internus.
b
Branch of the Ram. palatinus to the intermaxillary gland.
ri′
M. rectus inferior.
c
Inosculating-branch of the Ram. palatinus.
sc
M. sterno-cleido-mastoideus.
Ch
Internal naris.
uk
Mandible.
d
Cutaneous branch of the Ram. palatinus.
†
Terminal branch of Ram. palatinus.
db
Fibrous plate.
*
Union of facial nerve with Ram. anterior of the glossopharyngeal.
F
Ramus mandibularis of the facial nerve.
III
Motor oculi nerve.
Gl
Intermaxillary gland.
Vb
Ramus palatinus of trigeminal nerve.
HD
Harderian gland.
Vc
Ramus maxillo-mandibularis of the trigeminal nerve.
l
Eyeball.
Vc′
Ramus maxillaris of the trigeminal nerve.
m
M. masseter.
Vd
R. mandibularis.
Ms.ob.i. M. obliquus inferior.
Ve(VII) Facial nerve.
OK
Upper jaw.
X
Pneumogastric nerve.
r
M. retractor bulbi.
X1
Glossopharyngeal nerve.
Fig. 11457. Lateral dissection of head, etc., to show the cranial nerves, etc.
c
Cardiac nerve.
pp
Pharyngeal branches of the pneumogastric nerve.
F
Union of facial and Ram. anterior of the glossopharyngeal nerve.
tt′
M. temporalis.
h
Ram. hyoideus of the glossopharyngeal nerve.
us
Muscular twigs of the Ram. mandibularis of the trigeminal nerve.
la
M. levator angi scapulae.
Z
Tongue.
lgd
M. longissimus dorsi.
Va
Terminal twigs of the ophthalmic nerve.
m
M. masseter.
Vc
Ram. maxillaris of the trigeminal nerve.
mt
Ram. mandibularis of the glossopharyngeal nerve.
Vd
Ram. mandibularis of the trigeminal nerve.
M1
Hypoglossal nerve.
Ve(VII) Facial nerve.
M2
Brachial nerve.
X1
Ram. anterior of the glossopharyngeal nerve.
Oh
Anterior cornu of the hyoid bone.
X2
Glossopharyngeal nerve.
oi
M. obliquus internus.
X3
Pneumogastric nerve.
ph1
M. petrohyoideus I.
X3g
Ram. gastrici of the pneumogastric nerve.
ph2
M. petrohyoideus II.
X3l
Ram. laryngeus.
ph3
M. petrohyoideus III.
X3p
Ram. pulmonales of the pneumogastric nerve.
ph4
M. petrohyoideus IV.
XI
Accessory nerve of the pneumogastric nerve.
Fig. 115. Dissection of the floor of the mouth.
dm
M. depressor maxillae.
ph3
M. petrohyoideus III.
F
United facial nerve and Ram. anterior of the glossopharyngeal nerve.
ph4
M. petrohyoideus IV.
gh
M. geniohyoideus.
sc
M. sterno-cleido-mastoideus.
gh′
sh
M. sterno-hyoideus.
h
Ram. hyoideus of the glossopharyngeal nerve.
sm
M. mylohyoideus (submaxillaris).
H
Heart.
smt
M. submentalis.
Lg
Lung.
TT
Thyroid.
m′
Ram. mandibularis of the glossopharyngeal nerve.
uk
Mandible.
M1
Hypoglossal nerve.
us
Muscular twigs of the Ram. mandibularis.
M2
Brachial nerve.
X2
Glossopharyngeal nerve.
Oh
Anterior cornu of the hyoid bone.
X3
Pneumogastric nerve.
oh
Momohyoideus.
X3c
Rami cardiaci of pneumogastric nerve.
ph1
M. petrohyoideus I.
X3l
Ram. laryngeus of the pneumogastric nerve.
ph2
M. petrohyoideus II.
X3p
Ram. pulmonalis of the pneumogastric nerve.
(To facilitate reference the original arrangement
of this part has been altered.)
[There are ten pairs of cranial nerves in the frog, which are
numbered in order from before backwards. The mode of origin of these
nerves, and their deeper relations with the respective parts of the
brain to which they belong, have already been described.]
1. The olfactory nerve (N. olfactorius),
[(Figs. 97, 98, 102, 103, 111I) runs
a very short course only a few lines in length, and escapes from the
cranium by an opening in the cartilage of the sphenethmoid into the
nasal cavity, where it divides into two branches, each of which breaks
up into a brush of filaments, to be distributed in the olfactory mucous
membrane. The nerve contains no white fibres]. (See organ of smell,
p. 385.)
2. The optic nerve (N. opticus), (Figs. 97,
102, 103, 111II) [arises, as already described, by the optic
tract, and joins with its fellow at the optic chiasma or commissure,
where part of the fibres pass over to the opposite side (according to
Michel all the fibres cross). Each optic nerve then courses outwards,
piercing the cartilage of the cranium and so reaching the eyeball].
(See organ of sight, p. 408.)
3. The motor oculi (N. oculomotorius,
Oculo-motor, Motor communis), (Figs. 102, 111, 112,
113III). From its origin it courses outwards and forwards,
perforating with a slight obliquity the cartilaginous wall of
the cranium, just in front of the Gasserian ganglion (Fig. 116III); on reaching the orbit it divides into two branches,
between the Levator bulbi and the Rectus internus and
inferior. One branch, Ramus superior, runs over and
parallel to the Ramos ophthalmicus Trig. and enters the under
surface of the Rectus superior; the second, lower branch,
Ramus inferior, supplies filaments to the Rectus internus
and inferior and to the Obliquus inferior. Apparently
it exchanges fibres with the ophthalmic division of the trigeminal
nerve.
[That portion of the motor-oculi between its branch to the Rectus
superior and to that to the Rectus internus contains a
number of nerve cells; according to Schwalbe (l. c., p. 235
and Pt. XII, Fig. 4) these cells are arranged in four groups or
ganglia; the second
group forms a very slight prominence, and is covered by a very fine
layer of nerve fibres, it also gives off some extremely fine nerves
to the eyeball; this is perhaps a ciliary ganglion (Ganglion
ciliare, Schwalbe). Beard, however, names it ‘mesocephalic
ganglion.’ The other three groups are simply clusters of cells between
the fibres of the nerve.]
4. The pathetic or trochlear nerve (N.
trochlearis, patheticus), (Figs. 102,
103, and 112IV). From its origin it courses forwards with and then crosses
the motor-oculi; it perforates very obliquely the cartilaginous lateral
wall of the cranium, in front of the motor oculi but above and very
slightly behind the optic foramen (Fig. 116);
it runs parallel to and in company with the Ramus opthalmicus
trigemini, and appears to exchange a few fibres with it, which,
however, according to de Watteville, Stannius, Cuvier, and Wyman, is
not really the case. In this course it lies first to the inner, then
to the outer side of the ophthalmic, over which it passes to supply
the Rectus superior. [The pathetic and ophthalmic nerves are
sometimes enclosed in a common
sheath (de Watteville).]
5. The trigeminal nerve (N. trigeminus),
(Figs. 97, 102,
103, 111, 112, 113, and 114V) is the largest of the cranial
nerves in the frog; from its origin it runs outwards and forwards
to the skull wall, and just before reaching this enters the large
Gasserian ganglion. It then passes through the cranial
wall immediately in front of the auditory capsule, and divides at
once into two main branches (Fig. 111Vg, etc.), the Ramus ophthalmicus and the Ramus
maxillo-mandibularis.
The Gasserian ganglion is a large, yellow, oval ganglion placed
in a depression in the outer wall of the cranium; it is covered by
a ‘periganglionic gland,’ which is similar in structure to that of
a spinal ‘periganglionic’ gland (see p. 180), the fibrous capsule
being stronger. This ganglion receives three other nerves besides the
trigeminal, viz. the sixth and seventh nerves, and branches of
the sympathetic.
According to de Watteville, these nerves are arranged on the
lower surface of the ganglion, so that the sympathetic is below,
the sixth above it, then the seventh, while the fifth is uppermost;
the sympathetic splits into several bundles which join the various
branches of the ganglion; the sixth divides into two bundles, one of
which usually joins the ophthalmic, while the other makes its exit
independently; the seventh splits into two bundles, one of which leaves the ganglion as the
hyomandibular branch, the other gives some fibres to the palatine
branch of the trigeminal nerve, and is then continued as the palatine
branch of the facial.]
a. The Ramus ophthalmicus (Ramus nasalis,
Fischer; Ophthalmic or Orbital Branch, Wyman; Orbito-nasal or
Ophthalmic Nerve, de Watteville), (Figs. 111
and 112Va). After leaving the
Gasserian ganglion the nerve is directed forwards parallel to the
side of the cranium, between this and the eyeball. It lies beneath
the Rectus superior, but above all the other muscles of the
eyeball and the optic nerve. At the anterior end of the orbit it
divides into two branches (e and f) which pass through
apertures (Foramen pro ramo nasali) in the cartilage of the
sphenethmoid, to reach the nasal cavity, where they lie between
the cartilage and mucous membrane. In this position the nerves
supply branches to the mucous membrane and then pierce the skull
to appear on the surface (Figs. 111, 112g,g,g, 114Va), the skin of which they supply. The branches inosculate with
each other and communicate with the anterior twigs of the Ramus
maxillaris (Fig. 114Vc) and with
those of the Ramus palatinus (Fig. 113Vb).
In its course through the orbit the Ramus ophthalmicus gives
off:—
(1) Near the Gasserian ganglion one, two, or three small branches,
which communicate with the trochlear nerve, and may then be traced to
the sclerotic of the eyeball; some of the twigs enter near the optic
nerve, others nearer the cornea. They are regarded as Ciliary
nerves (Nervi ciliares).
(2) A large branch, the palatine nerve (Ramus
palatinus), (Figs. 111 and 113Vb, b). This nerve, after
receiving the palatine branch of the facial, descends on the inner
border of the Levator bulbi to the mucous membrane of the mouth,
to which it gives numerous filaments; it then runs parallel and near
to the median line, lying on the base of the skull; and near the front
of the orbit it divides into three branches. The smallest (a)
supplies the Harderian gland (HD); the second (b)
continues in the course of the original nerve, pierces the vomer, and
divides, giving filaments to the mucous membrane in its whole course,
while the terminal twigs supply the intermaxillary gland (Gl)
and the surrounding structures. One of these (†) ascends on the
anterior border of the sphenethmoid to the intermaxillary (internasal,
Born) space to supply the numerous glands and to inosculate by one or
two twigs with the nasal branch (tr) of the trigeminal. The third branch of the
palatine nerve (c) curves directly outwards, just behind the
palatine bone, to the inner surface of the maxillary bone; it then
courses backwards, pierces the fibrous plate (db) between the
eyeball and the pterygoid bone, and ultimately unites with superior
maxillary division of the trigeminal nerve (Vc′). Just before
piercing the fibrous plate it gives off a tolerably large nerve
(d) to the mucous membrane, and in its whole course it gives off
twigs to the mucous membrane and surrounding structures; many of these
twigs inosculate with other terminal twigs of the trigeminal.
[This nerve has been minutely described by Stirling and Macdonald;
these observers find that the branches form a very fine and
close plexus in the mucous membrane, etc.; fibres were traced to
blood-vessels, glands, etc., and ganglion cells were found scattered
along the nerves. The fibres are both medullated and non-medullated,
and many of the cells are described as ‘spiral cells’ (see page 201) such as those described by Arnold in the
sympathetic system of the frog.]
b. The Ramus maxillo-mandibularis (Ramus
maxillaris, Ecker and Hoffmann; Supra-maxillary, Humphry; Upper
Maxillary Branch, Wyman), (Figs. 111, 112, and 113Vc).
This nerve is the largest division of the trigeminal; it runs directly
outwards behind the eyeball, in front of the auditory capsule, and
between the temporal and pterygoid muscles. After a very short course
it divides into the maxillary and mandibular nerves. The nerve gives
off before its division a few fine filaments (i,i) to the hinder
half of the upper eyelid and to the surrounding skin, also a branch
(h) [not correctly drawn in Fig. 111]
which divides to supply twigs to the temporal and pterygoid muscles.
(1) The Ramus maxillaris (Ramus supramaxillaris,
Ecker; Ramus maxillaris superior, Hoffmann; Upper Maxillary
Branch, Wyman; Supramaxillary, Humphry and de Watteville), (Figs. 111, 112, 113, and 114Vc)
runs outwards and then forwards, between the eyeball and the outer
wall of the orbit, to the margin of the upper jaw (K); a large
portion terminates in a number of small branches for the supply of
the skin of the lower eyelid, the upper lip, and of the parts between
the tympanic membrane and the external nares. Some of these twigs
inosculate with twigs of the palatine and ophthalmic nerves. The
second portion of the nerve unites with the palatine nerve, as already
described.
(2) The Ramus mandibularis (Ramus maxillaris inferior,
Hoffmann; Mandibular or Lower Jaw Branch, Wyman; Inframaxillary,
Humphry and de Watteville), (Figs. 111,
112, 113, 114, and 115Vd,
us). As far as the outer margin of the eyeball, this nerve
runs parallel to and behind the Ramus maxillaris, in which
course it supplies branches to the temporal and pterygoid muscles; it
then curves backwards, outwards, and downwards to the under surface
of the squamosal bone, where it supplies a twig to the Depressor
maxillae, and then perforates the Masseter: in this
manner it reaches the outer surface of the mandible, just behind the
insertion of the temporal muscle; it then courses forwards, under the
skin, to the Symphysis menti. In this course the nerve gives
off numerous branches to the skin and surrounding parts, it also
supplies the mylo-hyoid and submental muscles; one branch (Figs. 114 and 115us)
is larger than the rest, and supplies the under surface of the floor of
the mouth and lower lip.
6. The abducens nerve (Nervus abducens,
Ecker and Hoffmann; included in the trigeminal, Wyman), (Figs. 111 and 112VI).
This very slender nerve courses along the inner wall of the cranium
from its origin to the Gasserian ganglion (q.v.) which it
joins, and leaves this in contact with the ophthalmic division of the
trigeminal nerve: the nerve then bifurcates in the orbit; the outer
branch supplies the Rectus externus, the inner inosculates with
small twigs of the ophthalmic division of the trigeminal, and then
gives off a number of small ciliary nerves, already described, and one
special branch to the Retractor bulbi.
7. The facial nerve (N. facialis, Ecker and
Hoffmann; Facialis (Portio dura), Wyman; Facial or
Jugular Nerve, Stannius), (Figs. 111, 113, and 114VeVII) arises immediately behind the trigeminal, and runs
forwards, first in company with the auditory nerve, then alone, to
the Gasserian ganglion (q.v.), with which it unites; it again
appears at the posterior angle of the ganglion, and escapes from
the cranium in company with, and immediately behind, the Ramus
mandibularis of the trigeminal, and divides at once into two
branches.
a. The Ramus palatinus at once unites with the
palatine branch of the ophthalmic division of the trigeminal nerve.
Wiedersheim doubts this arrangement, and holds that the two portions
arise in common from the Gasserian ganglion; neither has Wyman
(Rana pipiens) described this branch of the facial. [De Watteville states that the
Ramus palatinus and the palatine branch of the ophthalmic nerve
are separated by the carotid artery. In urodeles the two nerves are
distinct.]
b. The Ramus hyomandibularis (Ramus jugularis,
Hoffmann; Facial Nerve, Wyman), (Figs. 113
and 114, VeVII). The nerve is
directed outwards and backwards so as to pass around the bony wall
of the auditory capsule, it then crosses over the inner end of the
columella, with which it is in close contact, and is then joined,
under cover of the sterno-cleido-mastoideus (sc), by a
branch (Ramus communicans) of the glossopharyngeal (see Fig. 111 *). The single trunk (F) so formed is
directed downwards in the posterior wall of the Eustachian tube to just
above the angle of the mandible, where it divides into three branches,
or sometimes into two, in which case a third nerve is supplied by one
of the others, usually by the Ramus hyoideus.
(1) The Ramus mandibularis (Ramus mentalis, Hoffmann;
Third Trunk of the Facial, Wyman), (Figs. 114mt and 115m′) passes inside the
angle of the jaw and courses forwards, between the skin and mylo-hyoid
muscle, parallel to the Ramus mandibularis of the trigeminal
nerve, as far as the symphysis. It supplies small twigs to the
neighbouring parts of the mucous membrane of the mouth.
(2) The Ramus hyoideus (Ramus jugularis,
Hoffmann; Second Trunk of the Facial, Wyman), (Figs. 114, 115h)
is the largest division of the facial; it courses forwards
subcutaneously over the deltoideus and the hinder fibres of the
mylo-hyoideus to the anterior cornu of the hyoid bone, supplying
its muscles and the skin of the throat and sternal region.
(3) The Ramus auricularis (First Trunk of the Facial, Wyman);
is a small branch, directed outwards; it supplies a branch to the walls
of the tympanic cavity, and is finally distributed in the skin under
the tympanic membrane and behind the angle of the mouth.
Fig. 116.
Right half of skull of Rana esculenta, seen from within.
II
Optic nerve.
III
Motor oculi nerve.
IV
Trochlear nerve.
VN
Root of the trigeminal nerve.
Vg
Gasserian ganglion.
VS
Sympathetic nerve.
VI
Abducens nerve.
VII1
Facial nerve.
VIII
Auditory nerve.
X1–3
Pneumogastric and glossopharyngeal nerves.
8. The auditory nerve (N. acusticus, Ecker,
Hoffmann; Auditory Nerve, Wyman). This nerve has a very short course
in the cranium; it reaches the auditory organ by a foramen (Fig. 116
VIII) in the auditory capsule, and is then distributed in the
ear, with which it will be described.
9. The glossopharyngeal nerve (N.
glossopharyngeus, Ecker; Ramus glosso-pharyngeus,
Hoffmann; Glossopharyngeal, Wyman; Glossopharyngeal of the Vagus, Müller),
(Figs. 102 and 103X, 111, 113,
114, and 115X2) arises in common with the pneumogastric nerve,
and quits the skull with it through an opening (Canalis nervi
vagi) immediately behind the auditory capsule, and at once
divides into two branches; both of which lie under the MM. in
tertransversarii capitis and are covered by the Depressor
mandibulae.
a. The Ramus anterior (Verbindungsast des
Glossopharyngeus, Wiedersheim; Ramus communicans, Hoffmann;
Uniting Branch, Wyman; Laryngeal Branch of the Vagus, Volkmann;
Communicans ad facialem, de Watteville), (Figs. 111, 113, and
114 X1). This nerve curves downwards and forwards
around the auditory capsule and beneath the Depressor mandibuli
to join the facial nerve, as already described.
b. The Ramus posterior (N. glossopharyngeus,
Wiedersheim; Ramus lingualis, Hoffmann), (Figs. 111, 113, and 114
X2). This nerve runs downwards and forwards to the
ventral surface of the pharynx, dips underneath the Petrohyoideus
IV, to appear again, after a short interval, by piercing the
Petrohyoideus II or III, courses parallel to and behind
the anterior cornu of the hyoid bone, and thus reaches the floor of
the mouth. The nerve then runs forwards in a very sinuous course,
close to the median line, and between the Geniohyoideus and
Hyoglossus; in its course on the floor of the mouth it crosses
the hypoglossal nerve. It supplies the petrohyoid muscles, and gives
numerous small branches to the mucous membrane of the pharynx (Ramus
pharyngeus, Hoffmann).
10. The pneumogastric or vagus nerve
(Vagus; Ramus intestinalis nervi vagi, Fischer,
Hoffmann; Vagal Trunk, Wyman; Vaso-sympathetic, Gaskell),
(Figs. 111, 113,
114, and 115X3). This nerve arises in common with the
glossopharyngeal; the two nerves leave the skull together by an
opening in the exoccipital bone (Canalis nervi vagi);
immediately outside the skull they acquire a ganglionic enlargement
(Ganglion condyloideum, Ganglion nervi vagi),
(Fig. 111XG); in this course the
glossopharyngeal lies in front of the pneumogastric, which it then
leaves. The pneumogastric lies first upon the M. levator anguli
scapulae, then running backwards and downwards along the hinder
border of the Petrohyoideus IV it comes to the side of the
pharynx; it is covered by the trapezius, and passes between the
hypoglossal nerve and the Aorta ascendens; arriving at the
Arteria pulmonalis, it gives off its terminal branches. [Gaskell has proved that this
nerve contains both sympathetic and vagal elements, and that it is
therefore really a vago-sympathetic.]
The branches and communications of the pneumogastric nerve are:—
a. Communications between the ganglion of the pneumogastric
and the sympathetic system (Fig. 111Sp), which again connect it with the Gasserian ganglion of
the trigeminal nerve (Fig. 111VS,
Vg); (see sympathetic system).
b. [The Ramus cutaneus dorsalis (Fischer) is
considered by Stannius and Fürbringer to be the homologue of
the Ramus auricularis; it passes outwards between the
digastricus and temporalis to be distributed in the skin
of the suprascapular region. This nerve is the persistent portion of
the N. lateralis nervi vagi of the tadpole.]
c. During its course over the petrohyoidei the vagus
gives off a few twigs (Fig. 114pp), which form a fine plexus
to supply these muscles and the pharynx [also a twig to the trachea,
according to Hoffmann].
d. The Ramus accessorius (Fürbringer, Hoffmann,
Ecker), (Fig. 114XI) is usually a single small nerve which runs
between the intertransversarii muscles and the trapezius:
it supplies the under surface of the latter muscle.
e. The Ramus scapularis (Hoffmann) is a very slender
nerve arising near the Ramus accessorius; it passes along the
under surface of the trapezius to the inner surface of the
interscapularis, which it supplies.
f. The Ramus laryngeus (Recurrens vagi),
(Figs. 114 and 115X3l) runs for some distance parallel to
the pneumogastric, separated from it by the petrohyoideus IV;
arriving at the hinder cornu of the hyoid bone the nerve loops round
the Arteria pulmonalis, and divides into two branches for the
supply of the larynx.
g. The Rami gastrici (Fig. 114X3g) are usually
two in number: they pierce the partial diaphragm formed by the anterior
fibres of the M. obliquus internus and terminate in the walls of
the stomach.
h. The Rami pulmonales (Figs. 114 and 115X3p)
also perforate the partial diaphragm, and then course along the
pulmonary arteries to the lungs.
i. The Ramus cardiacus (Figs. 114 and 115X3c).
This nerve is usually smaller on the right side than on the left; it
passes along the dorsal surface of the pulmonary artery and Vena
cava superior to the Sinus venosus; in this course it gives
off two or three twigs to the roots of the lungs: the two nerves
communicate just before reaching the heart and pass on to the auricular
septum, whence they are distributed to the heart.
j. A slender Laryngeal nerve arises from the vagus
alongside the Ramus cardiacus; it courses along the hinder end
of the greater cornu of the hyoid to the outer side of the pharynx,
which it pierces to pass to the larynx.
I.General description. Ten pairs of
nerves arise, as already described (p. 135), from the spinal cord; each
nerve has two roots, a ventral or anterior, and a dorsal or posterior,
which unite at their points of exit from the intervertebral foramen:
just before, and for a short distance beyond this union, each dorsal
root bears a ganglionic enlargement.
a. The length and direction of the various Nerve-roots
vary greatly; the roots of the anterior spinal nerves run a very short
course, almost transversely outwards, from their points of origin to
the intervertebral foramina: the roots of the middle and posterior
nerves, in consequence of the vertebral column being considerably
longer than that part of the cord belonging to it, pass obliquely
backwards to the foramina, the hinder nerves of the Cauda equina
running for a considerable distance in the vertebral canal (Fig. 116).
The relations of these roots are as follows:—
(1) The roots of the first nerve (N. hypoglossus) arise from
the spinal cord at a point between the first and second vertebrae;
they run transversely outwards to escape between the first and second
vertebrae. The dorsal root is extremely slender.
Fig. 117.
The nervous system of Rana esculenta, from the ventral
surface. (From Icones physiologicae by A. Ecker. Pl. XXIV, Fig. 1.)
F
Facial nerve.
G
Ganglion of pneumogastric nerve.
He
Cerebral hemisphere.
Lc
Optic tract.
Lop
Optic lobe.
M
Boundary between medulla oblongata and spinal cord.
M1‑10
Spinal nerves.
MS
Connection between fourth spinal nerve and sympathetic chain.
N
Nasal sac.
Ni
Sciatic nerve.
No
Crural nerve.
o
Eyeball.
S
Trunk of sympathetic.
S1‑10
Sympathetic ganglia.
SM
Rami communicantes of the same.
Sp
Continuation of sympathetic into head.
I
Olfactory nerve.
II
Optic nerve.
III
Motor oculi nerve.
IV
Trochlear nerve.
V
Trigeminal and facial nerves.
Va
Ramus ophthalmicus.
Vc
Ramus maxillaris.
Vd
Mandibular branch of trigeminal.
Ve
Hyomandibular branch of facial.
Vg
Gasserian ganglion.
Vs
Upper end of sympathetic trunk in connection with Gasserian ganglion.
VI
Abducens nerve.
VII
Facial nerve.
VIII
Auditory nerve.
X
Glossopharyngeal and pneumogastric nerves.
X1
Ramus anterior of glossopharyngeal.
X2
Ramus posterior of glossopharyngeal.
X3, 4
Branches of pneumogastric.
(2) The roots of the second nerve (N. brachialis) arise at the level of the
second vertebra and leave the vertebral canal between the second and
third vertebrae.
(3) The roots of the third nerve arise from the cord between the
second and third vertebrae, and pass out between the third and fourth
vertebrae.
(4) The fourth nerve arises by its two roots at the level of the
fourth vertebra, and quits the vertebral canal between the fourth and
fifth vertebrae.
(5) The fifth nerve arises opposite the fourth vertebra, and passes
outwards and slightly backwards to the foramen between the fifth and
sixth vertebrae.
(6) The roots of the sixth nerve are attached to the cord opposite
the fourth vertebra, and leave the vertebral canal between the sixth
and seventh vertebrae.
(7) The seventh nerve arises from the cord at a point between the
fourth and fifth vertebrae, and leaves the canal between the seventh
and eighth vertebrae.
(8) The eighth nerve quits the cord at a point opposite the
articulation between the fifth and sixth vertebrae, then runs backwards
to the eighth vertebra, and escapes between this and the ninth
vertebra.
(9) The ninth nerve arises at the level of the sixth vertebra, and
passes out between the sacrum (ninth vertebra) and the urostyle.
(10) The tenth nerve (N. coccygeus) arises from the cord
immediately behind the ninth nerve and opposite the sixth vertebra, and
courses alongside the terminal filament to pass out through a foramen
in the urostyle (canalis coccygeus).
b. [The Spinal ganglia (Ganglia
intervertebralia).
At their exit from the intervertebral foramen the two roots of each
nerve unite and bear a ganglionic enlargement, which is in intimate
connection with the dorsal root, but is merely in contact with the
ventral root. The ganglia lie58 in the large intervertebral depressions, upon
the under surface of the Proc. obliqui, above and behind, being
in relation with the bodies of the vertebrae internally, and the
Musculi intertransversarii externally (Fig. 119); ventrally the
ganglia are, more or less, covered by the ‘periganglionic glands.’ The
ganglia vary much in size; that of the first spinal nerve is the smallest. The ganglion is not
attached to the dorsal root alone but is prolonged a short distance
beyond the point of union of the two roots; this is best seen in the
nerves of the lumbar plexus. Each ganglion is a yellowish-white rounded
or oval body, with an outer thick (sometimes 0.15 mm. thick) sheath of
connective-tissue, connected by the epineurium of the nerve roots with
the Dura mater. This sheath is composed of bundles of parallel,
wavy, white, connective-tissue fibres, which enclose a large number
of connective-tissue corpuscles, and here and there contains brown
pigment.
Fig. 118.
Ventral view of the brain and spinal cord, to show the
points of exit of the spinal nerves.
M1‑10
Spinal nerves.
VG
Trigeminal ganglion.
W1‑10
Vertebrae.
XG
Ganglion of vagus.
By means of longitudinal and transverse sections it may be seen
that the ganglion surrounds the ventral root, but that it forms a
thinner layer on that side, where the dorsal root joins the ventral;
although at this point the two roots and the ganglion are firmly
united together, the thick fibrous sheath of the ganglion prevents any
communication between the nervous elements of the ventral root and
those of the ganglion.
The sheath contains nerve-cells and fibres, and sends in a few fine
processes to support these structures. The fibres of the posterior
root enter and pass out of the ganglion without suffering any changes,
except that the nerve fibres are slightly separated by the presence of
a few nerve-cells, and that a distinct increase in the number of nerve
fibres takes place. The nerve-cells, of which the ganglion is chiefly
composed, and upon the number of which its size directly depends,
are arranged chiefly around the fibres of the dorsal root; such few
as lie between the fibres are smaller than the rest and vary more in
their relative numbers; at times one or two isolated cells are found
in the capsule or even in the adjoining ‘periganglionic gland.’ The
cells near the capsule are somewhat smaller than the deeper cells.59 Each of
these cells, which are usually pear-shaped, possesses only one process;
the cell membrane is thick, resistant, and possessed of an external
nucleated, endothelial covering, the space around being probably
a pericellular lymph-space; it often contains one to three small
fat-globules; the protoplasm of these has, according to v. Lenhossék, a
concentric fibrillation; the nucleus is round, clear, and distinct, and
relatively larger the smaller the nerve-cell; it is usually placed in
the centre of the cell.
Fig. 119.
Ventral view of the spinal ganglia; on the right side they are still
hidden by the ‘periganglionic glands.’
Fig. 120.
Schema of spinal ganglion.
A
Ventral root.
C
Ramus communicans.
G
Ganglion
O
Dorsal division.
P
Dorsal root.
R
Ventral division.
In that portion of the cell towards the process is a portion
brighter and less easily stained than the rest of the cell
(Polarkernen, Courvoisier); this apparently possesses one or two
nuclei, and is regarded as a cell by Lenhossék (Polarzellen); the
process of each cell soon acquires a medullated sheath, and after a short course, 0.09 mm. to
0.35 mm., divides usually about the third constriction (Lenhossék).
These processes all pass peripherally, even those which appear at first
to pass in the opposite direction curve round again; it is chiefly due
to these fibres that the spinal nerve is larger than its two roots.
In addition to the above, smaller, irregular cells from 5 µ to 7 µ
in length are found; Rawitz regards them as young cells, Lenhossék as
cells capable of (entwicklungsfähige) developing into nerve-cells. The
ganglia contain only few blood-vessels.]
The above description is founded upon that of Lenhossék, and has
been confirmed by the translator in every particular, except that
only very indistinct and unsatisfactory indications of the concentric
fibrillation so clearly delineated by Lenhossék were obtained; the
structure of the Gasserian ganglion was found to correspond exactly
with the description here given of the structure of the spinal ganglia.
The nucleus was oftener at the side than at the centre of the cell.
c. The ‘Periganglionic Glands’ (Periganglionäre
Kalkdrüsen, v. Lenhossék; Kalksäckchen, Ecker, and others; Crystal
capsules, Wyman; Calcareous Sacs or Masses, of other writers),
(Fig. 119). These bodies are found on the ganglia of all the spinal
nerves and on the Gasserian ganglion of the trigeminal nerve; they have
recently been carefully investigated by v. Lenhossék. According to his
description there are usually two to each ganglion, lying on its sides
and ventral surface; each consists of a connective-tissue capsule which
sends in a few fine trabeculae to support a system of glandular tubes:
these usually run parallel to the long axis of the gland, and are about
14 µ to 15 µ in diameter; each tube is lined with a single layer of
somewhat columnar epithelium, the cells of which have sharp, distinct
outlines and oval nuclei.
A membrana propria was not made out with certainty; the
lumen of the tubes is wide and contains a milky fluid, which gives the
whole structure its characteristic appearance; it has long been known
(Blasius, 1681, mentions the fact, l.c., p. 291) that this
fluid contains calcareous matter, which effervesces and dissolves in
the presence of hydrochloric acid; the crystals vary in form but are
chiefly oval (Wyman).
These glands bear no definite proportion to the size of the nerves
to which they are attached (Fig. 118); they already contain calcareous
matter during the tadpole stage before the limbs are developed
(Stannius, Wyman). No ducts have been traced to these glands. This description, founded
upon that of Lenhossék, can be confirmed by the translator in every
particular; his sections, however, would lead him to believe that the
glands are far more vascular than the description and the drawings of
Lenhossék imply.]
d. The Branches of the complete spinal nerves formed
by the union of the dorsal and ventral roots with the ganglion (Fig.
120) are usually described as two, a dorsal and a ventral branch,
which latter at once gives off a Ramus communicans to the
sympathetic system; these two branches are given off almost immediately
beyond the ganglion.
II. The Individual Nerves.
A. The Dorsal Branches (Fig. 121).
Fig. 121.
Dorsal branches of the spinal nerves. The Fascia dorsalis is
dissected, removed from the left side.
rc
Rami cutanei.
rm
Rami musculares.
The dorsal branches are smaller than the ventral; they pass upwards
between the inner borders of the Musc. intertransversarii and
the articular processes of the vertebrae to reach the under surface of
the M. longissimus dorsi; the general course of these nerves is
very similar for all; each nerve gives off—
(a) A twig to the Musc. intertransversarius and then
divides into two branches.
(b) A Ramus muscularis (Fig. 121 rm), which
passes outwards to supply the M. longissimus dorsi.
(c) A Ramus cutaneus (Fig. 121 rc); this nerve
continues under the extensor muscle of the back, running on the arch
of the vertebra towards the middle line; it then pierces the muscle
and Fascia dorsalis to reach the large dorsal lymph-sac (Sacc.
cranio-dorsalis), through which it courses to end in the skin. In
its course through the sac the nerve is connected with a small artery
and vein by a small amount of connective-tissue, the whole being
enclosed in a sheath of
endothelium continuous with that of the general cavity.
The three anterior cutaneous nerves pierce the Fascia
dorsalis near the spinous processes, the fourth a little to the
side, the fifth perforates the M. coccygeo-iliacus at about
the junction of its anterior and middle thirds; the sixth and seventh
perforate the same muscle, but more posteriorly. There are seven of
these Rami cutanei, the first coming from the second spinal
nerve, the rest from the succeeding six spinal nerves.
B. The Ventral Branches.
The ventral branches of the spinal nerves are larger than their
corresponding dorsal branches: each nerve gives off immediately
a Ramus communicans to the sympathetic system (Figs. 117SM, 120C); these Rami communicantes will be
described with the sympathetic system; the remaining portions of the
ventral divisions of the original spinal nerves are usually known as
the spinal nerves; they will be described as such in detail.
1. The hypoglossal nerve60 (N. hypoglossus,
N. spinalis I), (Figs. 114115, and 117M1), or first
spinal nerve, is of small size; it leaves the vertebral canal
between the first and second vertebrae to lie between the Musculi
intertransversarii and the pharynx, where it has in front the
Arteria vertebralis, behind the Arteria and Nervus
brachialis; passing under the Levator anguli scapulae, it
touches the Aorta ascendens and crosses the Vagus and
the Carotid-gland, and thus reaches the space between the Musculi
sterno-hyoidei and the Petro-hyoideus; then curving forwards
sharply it turns under the Mylo-hyoideus to course between the
fibres of the Genio-hyoideus to the root of the tongue, where
it ends. It first lies to the inner and then to the outer side of the
glossopharyngeal nerve. In its course the nerve gives off the following
branches:—
(a) One or two communicating twigs (Figs. 114 and 122) to the
second spinal nerve.
(b) Muscular twigs to the Longissimus dorsi,
Intertransversarii capitis, Levator anguli scapulae, and
the Retrahens scapulae.
(c) When near the glossopharyngeal it supplies twigs to the
Geniohyoideus, Sternohyoideus, and Omohyoideus,
where it bifurcates.
(d) One of the branches passes inwards to supply the
Hyoglossus.
(e) The other terminal branch passes forwards with the
Ramus lingualis and the glossopharyngeal, between the fibres of
the Geniohyoideus, which it partially supplies, and sends twigs
to the neighbouring parts.
(f) [Hoffmann describes a communicating branch to the
pneumogastric nerve, which the translator has not been able to
discover, and which no other observer has mentioned.]
Fig. 122.
The brachial plexus.
Cc
N. coraco-clavicularis.
Cc′
Nerve to musc. obliq. abdom internus.
d
Deltoid muscle.
la
Musc. lev. ang. scap.
ld
Musc. lat. dorsi.
oi
Musc. obliq. abdom. intern.
sc
Musc. sterno-mastoid.
ss
Musc. subscapularis.
SI
First spinal nerve.
SII
Second spinal nerve.
SIII
Third spinal nerve.
IIc
Ramus cutaneus axillaris.
IIIc
Ramus cutaneus abdominalis.
2. The second spinal or brachial nerve (N.
brachialis, N. spinalis II), (Fig. 122) is a large nerve,
leaving the vertebral canal between the second and third vertebrae; it
then accompanies the Art. axillaris along the anterior border
of the transverse process of the third vertebra, over the hinder end
of the Musc. levator scapulae and the anterior end of the m.
transverso-scapularis major, to the inner border of the Musc.
subscapularis, under which it passes into the arm. In this course
it gives off or receives the following branches:—
(a) It first receives a branch from the second spinal
nerve.
(b) It gives off a large branch, the N.
coraco-clavicularis (Fig. 122 Cc), which first accompanies
a branch of the Art. axillaris on the Musc. levat.
scapulae, then courses forwards and outwards over the Musc.
subscapularis to pass from above into the Foramen ovale
between the clavicle and coracoid bones. It gives off two branches:
(1) One immediately beyond its origin, which runs backwards over
the Musc. subscapularis to supply the Musc. obliq. abdominis
internus (Fig. 122 Cc′).
(2) While in the Foramen ovale, the N.
coraco-clavicularis bifurcates; the anterior twig runs forwards
and outwards to the deltoideus and also supplies a recurrent
filament to the Musc. sterno-radialis; the posterior twig enters
the upper surface of the Musc. stero-radialis.
(c) At the outer extremity of the Musc.
transverso-scapularis the brachial nerve gives off a posterior
branch, which at once bifurcates:
(1) The first branch passes into the under surface of the
Musc. latissimus dorsi (ld), giving a twig to the
Infraspinatus.
(2) The second is the Ramus cutaneus axillaris (IIc);
it passes on the under
surface and posterior border of the Musc. latissimus dorsi to
the skin of axilla and dorsal surface of the upper arm.
(d) Several small branches are given off from the upper and
anterior surfaces of the brachial nerve near the Foramen ovale;
they accompany an artery to pass forwards and upwards between the
Musc. subscapularis and the M. transverso-scapularis on
the one side, and the long head of the M. triceps brachialis
on the other, and are lost in the M. deltoideus and the M.
infraspinatus.
The N. brachialis continues its course by passing between
the long and inner heads of the M. triceps, reaches the arm
and splits into two nerves, the N. ulnaris and the N.
radialis.
Fig. 123.
Nerves of the central surface of the arm. The hand
pronated.
rc
Upper cutaneous branch of the N. radialis.
rc′
Lower cutaneous branch 4-,f the N radialis
U
N. ulnaris.
uc
R. cutan. sup. of the N. ulnaris.
uc′
R. cutan. inf. of the N ulnaris.
up
R. pectoralis of the N. ulnaris.
[I.] The N. ulnaris (Fig. 123 U) escapes from
cover of the long head of the M. triceps and runs obliquely over
its inner head towards
the outer side of the Plica cubiti; in this course it supplies
four branches:
α. The Ramus subscapularis passes dorsally to the M.
subscapularis.
β. A Ramus pectoralis (Fig. 123up), passes forwards
to the M. abdomino-pectoralis and to the skin of the pectoral
region (R. cutaneus pectoralis).
γ. The N. cutaneus antibrachii superior s. medialis
(uc) passes to the skin of the inner side of the forearm;
this and the two following nerves are given off near the Plica
cubiti.
δ. The N. cutaneus antibrachii inferior s. dorsalis s.
musculo-cutaneus (uc′) at once supplies branches to the
M. flexor carpi radialis61, and then runs downwards upon the muscle and
bifurcates:—
[1] The R. lateralis is distributed, by two twigs, in
the M. flexor carpi ulnaris and in the skin of the second
finger, to which it supplies the Rami digitales volaris and
dorsalis.
[2] The R. dorsalis, after giving a cutaneous twig to the
second finger, is distributed by numerous twigs to the skin of the
dorsal surface of the hand.
The N. ulnaris then passes between the M. flexor carpi
radialis and the tendon of the M. sterno-radialis, sinks
deeply into the Plica cubiti, where it lies between the M.
flexor carpi radialis and the Flexor carpi ulnaris, then
between the latter and the Flexor anti-brachii medialis on the
one side and the Flexor digitorum communis on the other: it
supplies branches to all these muscles, and while still in the forearm
divides into two terminal branches:—
α. The R. ulnaris medialis is the smaller; it runs
inwards, passes under
the tendon of the M. extensor carpi ulnaris into the palm of the
hand and ends as the N. volaris digiti V medialis.
Fig. 124.
Nerves of the ventral surface of the arm. The hand supinated, and
the superficial layer (Flex. carpi rad. and uln., Flex. dig. commun.)
has been removed.
R
N. radialis.
u
N. ulnaris.
uc
R. cutan. inf. of the N. ulnaris.
um
Bifurcation of the N. ulnaris.
β. The R. ulnaris lateralis passes near the thumb-rudiment,
covered by the M. abductor pollicis, deeply into the palm of the
hand, and supplies by bifurcating branches the adjacent sides of the
second, third, fourth, and fifth fingers (R. volares); it also
gives twigs to the muscles of the palm.
[II.] The N. radialis (Figs. 123, 124, and 125
R) passes immediately beyond its origin from the N.
brachialis, between the humerus and the M. triceps, runs
along the bone to its outer side; in this course it gives off:—
α. Rami musculares to the separate parts of the M.
triceps.
β. The Ramus cutaneus superior (Fig. 125 rc) to the
skin of the outer surface of the upper arm and forearm.
The nerve then sinks deeply under the origins of the M. extensor
carpi ulnaris and the M. extensor digitorum communis, where
it bifurcates after giving off some small twigs:—
γ. Small muscular twigs to the extensor muscles of the hand and
fingers.
Fig. 125.
The N. radialis.
ec
M. extensor carpi ulnaris.
ed
M. extensor digit. comm.
R
N. radialis.
R1
R. lateralis.
R2
R. medialis.
rc
R. cutaneus superior.
rc′
R. cutaneus inferior.
δ. The R. radialis medialis (R2), the smaller terminal branch,
supplies a branch to the M. extensor digit. comm. longus and the
skin over the carpus (Ramus cutaneus inferior, rc′), and
ends on the muscles of the little finger as the R. dorsalis digiti V
medialis.
ε. The R. radialis lateralis (R), the larger of the
two branches, supplies the extensor muscles of the fingers and gives
bifurcating branches, Rami digitales dorsales, to the adjacent
sides of the second, third, fourth, and fifth fingers (the Ramus
dorsalis lateralis of the second finger is supplied by the N.
ulnaris).
3. The third spinal nerve (N. spinalis III)
(Fig. 122SIII) leaves the vertebral canal by the foramen
between the third and fourth vertebrae, and runs outwards and forwards
upon the large transverse process of the third vertebra to the brachial
nerve (N. spinalis II). Its behaviour at this point is subject
to considerable variation; at times it joins the brachial nerve
completely, at other times the two nerves are simply in contact; or
lastly, it may send a small twig to the brachial nerve. Externally to
this point the two nerves supply a number of small branches, which may
belong almost entirely to either one nerve or the other; these nerves
again inosculate in a variable manner, to form an axillary plexus. The
more constant branches are:—
(1) One or more twigs to the Musc. transverso-scapularis
major.
(2) Several branches, usually two larger and one smaller; they
course in the M. obliq. abdom. internus (Fig. 122oi) to
the M. rectus, where they give off branches, then pierce the
muscle to reach the skin (R. cutaneus abdominalis), (Fig. 122IIIc).
Fig. 126.
Ventral view of the brain and spinal cord, to show the
points of exit of the spinal nerves.
M1‑10
Spinal nerves.
VG
Trigeminal ganglion.
W1‑10
Vertebrae.
XG
Ganglion of the vagus.
4. The fourth spinal nerve (N. spinalis IV)
(Fig. 126 M4) appears between the fourth and fifth vertebrae;
it runs on the ventral surface of the transverse process of the fifth
vertebra and upon the Musc. intertransversarius obliquely
outwards and downwards, and reaches the deeper surface of the Musc.
obliquus internus, into which it descends, about opposite the
articulation between the eighth and ninth vertebrae; it then bifurcates
into:—
(1) A Ramus cutaneus abdominalis, which pierces the muscle
and supplies the skin.
(2) A Ramus muscularis, which supplies the broad abdominal
muscle and the M. rectus abdominis.
5. The fifth spinal nerve (N. spinalis V)
(Fig. 126 M5) emerges through the foramen between the fifth and
sixth vertebrae, runs
obliquely downwards and outwards over the transverse processes
of the sixth and seventh vertebrae and the corresponding M.
intertransversarii, and at a point nearly opposite the middle of
the urostyle pierces the M. obliquus internus.
The rest of its course corresponds exactly with that of the fourth
spinal nerve.
6. The sixth spinal nerve (N. spinalis VI)
(Fig. 126 M6), after escaping from the vertebral canal between
the sixth and seventh vertebrae, runs obliquely downwards and outwards
on the under surfaces of the transverse processes of the seventh,
eighth, and ninth vertebrae, then under the iliac bone to a point
opposite the hinder half of the urostyle, where it descends under cover
of the M. obliquus abdom. internus. In the rest of its course
it repeats the corresponding courses of the fourth and fifth spinal
nerves.
7, 8, 9, and 10. The seventh,
eighth, ninth, and tenth spinal nerves
(Nervi spinales VII, VIII, IX, and N.
spinalis X s. N. coccygeus) (Figs. 126 and 127M7, M8, M9, and
M10) are best described together, as they are intimately
associated to form the sciatic plexus (Plexus ischiadicus,
Plexus cruralis).
Within the vertebral canal the roots of these nerves form the
Cauda equina; the seventh nerve leaves the canal between the
seventh and eighth vertebrae, the eighth nerve between the eighth
and ninth vertebrae, the ninth between the sacrum or ninth vertebra
and the urostyle, and the tenth by the Canalis coccygeus in
the urostyle; from these points the four nerves run obliquely on the
ventral surface of the M. ilio-coccygeus to the pelvis, where
they form the sciatic plexus. Although subject to some variation,
the usual arrangement is that the seventh and eighth nerves unite to
form a trunk, which then receives the ninth nerve; the large nerve so
formed is the sciatic nerve: a branch of the tenth usually then joins
either the sciatic plexus or the sciatic nerve; the plexus gives off or
receives the following branches:—
(a) Like other spinal nerves, these nerves give off Rami
communicantes (see Sympathetic System).
(b) The M. ilio-hypogastricus (Fig. 127M7a).
This arises from the seventh spinal nerve, before its union with the
eighth spinal nerve; it runs obliquely outwards and downwards on the
Musc. ilio-coccygeus and under the border of the M. obliquus
abdom. internus, where it bifurcates:—
(1) One branch, the Ramus cutaneus abdominalis, pierces the
M. obliq. abdom. internus in the same fashion as the cutaneous
branches of the fourth, fifth, and sixth spinal nerves; it supplies the
skin of the abdomen.
(2) The second or Ramus muscularis supplies the flat
abdominal muscles and the M. rectus abdominis.
(c) The M. cruralis (Fig. 127 M7b) also arises
from the seventh spinal nerve at or just beyond its point of union with
the eighth spinal nerve. It accompanies the A. cruralis on the
pelvic wall to the thigh, where it lies upon the M. ilio-psoas
in a triangle between the M. rectus fem. anterior and the M.
adductor longus, and divides into two main branches:—
(1) Muscular twigs to the M. ilio-psoas, M. rectus femoris
anticus, MM. adductores longus and brevis.
(2) The Ramus cutaneus femoris, which runs downwards in the
hinder wall of the Lymph-sac (Saccus iliacus), and supplies the
skin of the under and outer surfaces of the thigh.
Fig. 127.
The sciatic plexus, from a drawing by Wiedersheim.
a
Communicating nerve from the ninth spinal nerve.
a′
Nerve to musc. lev. ani.
b
Nerve to oviduct.
c
Urostyle.
cc
Communicating twig from the ninth spinal nerve.
ci
M. coccygeoiliacus.
c.I
M. coccygeosacralis.
d
Nerve to bladder.
d′
Twig to the m. iliacus.
e
Twig from sciatic plexus to coccygeal plexus.
i
M. intertransversarius.
il
M. ilio-coccygeus.
ip
M. ilio-psoas.
lev
M. lev. ani.
oi
M. obliq. abdom. internus.
t′
Transverse process of sacrum.
Ao
Aorta.
Com
Point of union of nerves a and cc.
Is
Ischium.
M5
Fifth spinal nerve.
M6
Sixth spinal nerve.
M7
Seventh spinal nerve.
M8
Eighth spinal nerve.
M9
Ninth spinal nerve.
M10
Tenth spinal nerve.
M7a
M. iliohypogastricus.
M7b
M. cruralis.
Ni
Sciatic nerve.
Ovd
Oviduct.
Rect′
Rectum.
S7, S8, S9, S10
Rami communicantes of seventh, eighth, ninth, and tenth spinal nerves.
Ves
Bladder.
8, 9
Eighth and ninth vertebrae.
(d) The Ramus dorsalis is a very small nerve;
according to Waldeyer it possesses only twenty nerve-fibres. It arises
from the coccygeal nerve
immediately beyond the Canalis coccygeus, perforates the M.
ilio-coccygeus, and runs on its dorsal surface obliquely over the
lymph-heart, without supplying it; the nerve then pierces the fascia to
supply the skin of the back and thigh.
(e) The Ramus abdominalis also arises from the
coccygeal nerve; it is larger than the R. dorsalis, and arises
at the same point; the nerve runs on the ventral surface of the M.
ilio-coccygeus towards the lymph-heart, and inosculates with the
sympathetic. It is from this nerve that the branch to the sciatic
plexus is usually given off; it further supplies a varying number of
branches, which with branches derived directly or indirectly from
the sciatic nerve, form a plexus (Plexus coccygeus); the two
plexuses may together be regarded as a Plexus ischio-coccygeus
or a Plexus sacro-coccygeus.
(f) In addition to the Rami communicantes given off
by the spinal nerves near the vertebral column, the sciatic plexus
supplies a few twigs, usually two (Fig. 127).
(g) Other small twigs pass from the sympathetic system
forwards and outwards to join the sciatic plexus or the sciatic nerve.
According to Waldeyer two of these are very constant.
(h) Branches to the oviduct (Fig. 127 b).
(i) Branches to the rectum (Fig. 127 cc).
(k) Branches to the bladder (Fig. 127 d).
(l) Branches to the M. levator ani (Fig. 127
a′).
(m) A branch to the lymph-heart, which runs along the
anterior border of the M. lev. ani, on to its dorsal surface,
and then direct to the lymph-heart.
Variations in the sciatic plexus. The arrangement
of the nerves in the sciatic plexus is subject to many variations;
according to Wiedersheim most of these variations belong to two chief
classes: either the N. coccygeus inosculates directly with
the ninth spinal nerve by one or several branches, or it joins the
ninth nerve indirectly by uniting with its branches. A case of the
latter arrangement is seen in Fig. 127, and is thus described by
Wiedersheim:—
‘After cutting through the pelvic symphysis and drawing to one
side the contained viscera, namely, the hinder end of the oviduct,
the rectum, and the bladder, one sees a row of small twigs (a,
b, cc, d, and e) arising from the
inner, hinder, and anterior surfaces of the ninth spinal nerve: the
first (a) runs backwards parallel with the N. coccygeus over the M.
ilio-coccygeus to join this nerve at the point marked Com.
The twig cc behaves in like manner after receiving a twig from
b. The twig b arises from the inner surface of the ninth
nerve between the two foregoing and close to its union with the eighth
spinal nerve; from this origin twig b passes almost transversely
outwards to the hinder extremity of the oviduct (“uterus”), and partly
to the rectum, crossing in its course twig a, the sciatic nerve,
and the urostyle. Its branches form a net-like plexus with the terminal
branches of the last sympathetic ganglion and with a branch cc
from the point of union Com.
‘A second branch (a′), arising from the point of junction
Com, is a continuation of the N. coccygeus (M10);
it passes vertically downwards towards the hinder end of the cloaca
and at the upper border of the Levator ani, divides into two
branches, which are distributed to the inner and outer surfaces of
this muscle and to the cloaca. Other branches pass dorsally to the
lymph-hearts, while a third set pass to the hindermost part of the
bladder.
‘These three sets of nerves, to the M. coccygeus, M.
levator ani, and to the lymph-hearts, are not supplied entirely
by the N. coccygeus, as this is reinforced by one or more
branches (e) from the sciatic plexus: this branch (e)
supplies twigs to the M. ilio-coccygeus, which is also supplied
anteriorly from the trunk of the N. coccygeus.
‘The bladder receives a special branch (d), which arises
from the sciatic plexus at the junction of the eighth and ninth
spinal nerves; this nerve gives a twig (d′) to the M.
iliacus.’
Fig. 128.
Distribution of the sciatic nerve.
I
The sciatic nerve.
II
N. tibialis.
III
N. peroneus.
1
Branches to the M. pyramidalis.
2
N. cut. fem. posterior.
3
Large collateral branch.
5
Branch to the M. biceps.
6
Branch accompanying the art. circumfl. genu lateralis sup.
7
Branch of tibial nerve to the M. gastrocnemius.
8
N. suralis.
ad‴
M. adductor magnus.
b
M. biceps.
bb
Twig accompanying the art. cutanea.
ci
M. coccygeo-iliacus.
cp
N. cut. cruris lateralis.
ct
R. cut. cruris posterior.
g
M. gastrocnemius.
gl
M. glutaeus.
p
M. pyramidalis.
pe
M. peroneus.
ra
M. rectus anterior.
ri′
M. rectus internus minor.
sm
M. semimembranosus.
st
M. semitendinosus.
ve
M. vastus externus.
I. The sciatic nerve (N. ischiadicus) (Fig. 128
I) is the largest nerve of the body; it passes under the M.
coccygeus, between the origins of the M. vastus externus and
of the M. pyramidalis: lies then between the M. biceps
and the M. pyramidalis, and later between the M. biceps
and the M. semimembranosus; lastly, it bifurcates under the
M. biceps to form the N. tibialis (II) and the
N. peroneus (III). In this course it gives off:—
(a) A twig to the M. coccygeo-iliacus, while still in
the pelvis.
(b) The N. cutaneus femoris posterior (Fig. 128, 2),
which passes between the M. pyramidalis and the M. vastus
externus, to appear behind and beneath the former; it accompanies
an artery of like name to supply the skin of the hinder and inner
surfaces of the thigh.
(c) A little below the foregoing it gives off a collateral
branch (Fig. 128, 3), which passes under the M. pyramidalis and
divides to form—
(1) A branch to the upper third of the M. semimembranosus.
(2) A branch to the Rectus internus minor. A twig of this
branch (bb) pierces the muscle transversely in company with the
Arteria cutanea, and passes to the skin of the middle of the
inner surface of the thigh.
(3) Branches to both heads of the semitendinosus.
(4) Branches to the M. adductor magnus.
(d) Branches covered by the M. pyramidalis to the
M. quadrat. femoris and M. obturator.
(e) A branch (5) forwards to the M. biceps.
(f) A branch (6) which accompanies the Art. circumflexa
genu lateralis sup. forwards to the M. extensores cruris,
the M. vastus externus, and the M. rectus anterior.
II. The Nervus tibialis (Figs. 128 II, 129
T) passes backwards and inwards to supply the extensors of the
foot and the flexors of the toes. Its branches are:—
(a) The R. cutaneus cruris posterior (Figs. 128 and
129 ct), accompanied by an artery and vein, passes to the skin
of the calf.
(b) A twig to the upper part of the gastrocnemius (Fig. 129
g′). The main nerve, after supplying this twig, bifurcates to
form the next two nerves.
(c) The Nervus suralis (Figs. 128 8; 129 s)
runs downwards on the inner border of the M. gastrocnemius and
gives off:—
(1) A twig (g″) to the upper third of the muscle.
Fig. 129.
Nerves of the leg and sole of the foot.
ab5
Branch to the M. abduct. digit. V.
ad5
Branch to the M. adduct. digit. V.
ar
M. rectus anterior.
b
M. biceps.
cs
Ramus cutaneus medius.
ct
Ramus cutaneus cruris posterior.
dvI
Ramus digitalis volaris I.
dvII
Branch supplying R. digit. volaris I and II.
dvIII
Second branch of the N. tibialis.
F5
Branch to the M. flex. brev. digit. V.
flp
Branches to the M. plantaris and the M. flexor digitorum.
g′
Branch to the M. gastrocnemius.
g″
Branch to the M. gastrocnemius.
pc
N. peroneus.
s
N. suralis.
sm
M. semimembranosus.
T, t
Nervus tibialis.
(2) The Ramus cutaneus medius (cs) is given off below
the middle of the M. gastrocnemius; it passes to the skin of
the lower third of the leg. After giving off the latter branch, the
N. suralis runs downwards along the inner aspect of the Tendo
achillis to the Aponeurosis plantaris of the sole of the
foot as far as the calcar, and gives off:—
(3) Branches (flp) to the Musc. plantaris and the
M. flexor digitorum.
(4) A branch to the M. abductor hallucis.
(5) The R. digitalis volaris I (dvI) supplies the
inner side of the first toe by its terminal twig.
(d) The Nervus tibialis (Fig. 129 t) passes
downwards on the hinder surface of the tibio-fibula, sinks into the
M. tibialis posticus to appear again at its hinder border; it
then runs over the ankle-joint into the sole of the foot, where it lies
midway in the space between the two Ossa tarsi and between the
M. extensor tarsi and the M. abductor digiti I longus;
the nerve then runs downwards in the groove of the small Os
tarsi and divides to form three branches:—
(1) The first branch (dvII) runs to the space between the
second and third fingers, where it bifurcates:—
(α) The Rami digital. volaris I run transversely over the
muscles of the second toe, supply the muscles of the first toe, and
bifurcate to form the R. digital. volaris I and II.
(β) The Ram. digit. volar. II divides in the space between
the second and third fingers to supply the Flex. phalang. and
the adjacent sides of these toes.
(2) The second branch (dvIII) runs over the M. flex.
metatarsi of the third toe to the space between the third and
fourth toes, and bifurcates to supply the adjacent sides of these toes
and the web between them.
(3) The third branch at once divides to supply:—
(α) The M. transv. metatarsi.
(β) The MM. lumbricales of the fourth toe.
(γ) The M. abductor digit. V (ab5), the M. flexor
brevis dig. V (F5), and the M. adductor dig. V
(ad5); it then ends as—
(δ) A bifurcating branch forming the R. digit. volar. of the
fourth and fifth toes.
III. The Nervus peroneus (N. peroneus communis
superior, Ecker), (Fig. 130 pc) is the second division
of the sciatic nerve; it passes between the outer head of origin
of the M. gastrocnemius and the tendon of insertion of the
M. biceps, it then lies on the tibio-fibula between the M.
gastrocnemius and the M. peroneus, where it is accompanied
by the Vena tibialis postica, then runs downwards upon the M.
extensor cruris and the Flexor tarsi ant., and passes under
the M. tibial. anticus and bifurcates; its branches are:—
Fig. 130.
Distribution of the N. peroneus.
A
Inner terminal twig of N. peron. comm. inf.
B
Outer terminal twig of N. peron. comm. inf.
cpl
N. cutaneus dorsi pedis lateralis.
pc
N. peroneus.
pci
N. peroneus communis inferior.
pl
N. peroneus lateralis.
pm
N. peroneus medialis.
a. The N. cutaneus cruris lateralis (Fig. 128cp); which, like other cutaneous nerves, runs in a common sheath
together with an artery and vein to the skin. It arises close to the
sciatic nerve.
b. Muscular branches to the MM. peroneus, tibialis
anticus, extensor cruris brevis, and the flexor tarsi
anterior.
c. The N. peroneus medialis (Fig. 130 pm) is
the smaller of the two terminal branches of the N. peroneus; it
courses with the Art. tibialis antica under the MM. flexores
tarsi anterior and posterior and supplies the latter.
d. The N. peroneus lateralis (Fig. 130 pl)
is the larger terminal branch of the N. peroneus; it passes
downwards between the heads of the M. tibialis anticus to the
tendon of origin of the Flexor tarsi posterior, where it gives
off two branches (Nos. 1 and 2); the nerve then unites with the N.
peroneus lateralis to form a common stem, the N. peroneus
communis inferior (Ecker). The N. peroneus lateralis gives
off:—
(1) The N. cutaneus dorsi pedis lateralis (cpl), which
passes to the skin of the outer side of the dorsum of the foot.
(2) A second branch to the M. extensor of the fourth and
fifth toes.
e. The N. peroneus communis inferior (Fig. 130
pci) runs on the dorsum of the foot in company with the Art.
dorsalis pedis, underneath the MM. extensores digiti I and
II; it supplies several branches and then bifurcates. It gives
off:—
(1) Branches to the MM. extensor longus and brevis digiti
I.
(2) Rami digitales dorsales to the adjacent sides of the
first and second toes.
(3) Branches to the MM. extensores digiti II.
(4) The inner, terminal branch (Fig. 130 A) at once
divides:—
(α) The outer branch runs between the third and fourth toes as far
as the commencement of the web, where it bifurcates to form two Rami
cutanei, which course along the adjacent sides of these toes as far
as their apices.
(β) The inner branch passes to the extensor muscle, and, in part, to
the adjacent sides of the third and fourth toes.
(5) The outer, terminal branch (Fig. 130 B) of the N.
peroneus communis inferior passes to the muscles of the fourth and
fifth toes, and supplies Rami cutanei dorsales to the outer side
of the fourth and inner side of the fifth toes.
Cutaneous branches of the N. tibialis supply the outer side
of the fifth and inner side of the first toe.
(Re-written by the translator.)
The sympathetic cord or chain is a row of nervous
ganglia (vertebral or lateral ganglia), connected by nerve-fibres, and
lying on either side of the vertebral column (Figs. 117 and 131); with
the exception of the last spinal nerve there is usually one sympathetic
ganglion associated with each spinal nerve; in the case of the tenth
spinal nerve there may be only one ganglion or as many as twelve.
The first ganglion (Figs. 111, opposite ics; 117S1)
is placed on the hypoglossal nerve just as it emerges from the first
intervertebral foramen; it is large, but smaller than the second; its
Ramus communicans is represented by several fine and very short
fibres, which connect the ganglion with the nerve. This ganglion is
connected with the second by two or three nervous threads, between
which passes the subclavian artery, a true Annulus Vieussenii
being thus formed (de Watteville). The other ganglia are connected by
single bands of fibres. The first ganglion supplies also branches to
the axillary artery and to the cardiac plexus.
The second ganglion (Figs. 117 and 131) is the largest, and is
closely applied to the brachial nerve; as in the case of the first
ganglion and hypoglossal nerve, it is attached to the second spinal
nerve without a distinctly marked Ramus communicans.
The third ganglion (Ganglion cardiacum basale, Gaskell
and Gadow) is sometimes fused with the second, but is usually close
to the third spinal nerve: it has a short but distinct Ramus
communicans.
Fig. 131.
Sympathetic cord. From Ecker (Icones physiologicae,
Pl. XXIV, Fig. 3).
The heart, lungs, and liver have been removed; the stomach, intestine,
kidneys, and testes drawn to the right side; the left sympathetic cord
is thus pulled to the right side to expose the Rami communicantes.
S Sympathetic cord attached to the ganglion of the vagus.
The numbers refer to the ganglia, which are enumerated from before backwards.
Behind the third ganglion the sympathetic cord is continued
backwards along the corresponding aortic arch, then parallel with and
close to the abdominal aorta (Figs. 117, 127, and 131), receiving
Rami communicantes, which are long and well marked, from each of
the spinal nerves; the fourth, fifth, and sixth nerves usually supply
each one Ramus communicans, the seventh two, and the eighth and
ninth each two or three: from the tenth nerve it receives three or
more, as many as twelve having been noted. The ganglia are usually more
or less spindle-shaped or flattened and triangular; the hinder part of
the cord usually receives in addition two or three branches from the
sciatic plexus and twigs from the R. abdominalis of the N.
coccygeus.
The branches and communications of the sympathetic cords are as
follows:—
a. Communicating branches between the two cords; these are
extremely numerous and irregular, forming a net-like plexus, which
surrounds the abdominal aorta and other adjacent structures, and gives
off numerous small twigs to the neighbouring vessels and organs.
b. Communications with the cranial nerves; these are two
branches (Wiedersheim), (Figs. 111 and 116) which pass from the first
ganglion to the Ganglion nervi vagi, where one terminates, the
other leaves the ganglion to pass on to the Gasserian ganglion (Figs. 111 and 116VS):
according to Gaskell a single nerve passes from the first
ganglion to the Ganglion nervi vagi, whence one portion of
its fibres is continued to the Gasserian ganglion, the remainder
accompanying the pneumogastric nerve without any connection with the
ganglion; he therefore names this nerve the vago-sympathetic. (See
Gasserian ganglion, p. 168.)
c. Communications with the spinal nerves; these are:—
(1) The Rami communicantes.
(2) Communications between the sympathetic ganglia or their branches
and the spinal nerves or their branches (Fig. 117); by means of these
connections, fibres of the sympathetic system are conducted by the
spinal nerves and their branches to all parts of the body.
d. Branches to the heart, which form the following
ganglia:—
(1) A relatively large plexus lies on the auricles in the median
plane immediately beneath the division of the M. hyoglossus.
It supplies a network of fibres to the auricles and the adjacent
large vessels. It is said to communicate at various points with the
pneumogastric nerve.
(2) A smaller ganglion of oval form, supplies twigs to the
neighbouring vessels and a communicating branch to the hypoglossal
nerve (Wiedersheim).
e. Branches to the abdominal viscera; these form intricate
plexuses by which the organs are supplied: the one best known is the
solar plexus (Fig. 131); it is formed chiefly from branches derived
from the third, fourth, and fifth ganglia, and supplies the stomach,
etc.; other plexuses for the various viscera are known by corresponding
names, such are the Plexus hepaticus, renalis,
genitalis, haemorrhoidalis, and vesicalis.
The sympathetic system is characterised by the fact that the
branches form intricate plexuses, which include numerous ganglia and
which are very irregular; it is also characteristic that most of its
fibres are non-medullated. According to the investigations of Gaskell,
the fibres of the sympathetic system arise in mammalia as very fine
medullated fibres from the posterior vesicular (Clarke’s) columns
(Mason has recently described cells in the frog’s spinal cord, which he
holds to be homologous with the cells of these columns); they leave the
cord by both the ventral and dorsal roots of the spinal nerves, and are
thus connected with two sets of ganglia, (1) with the ganglia of the
dorsal roots, and (2)
through the Rami communicantes with the sympathetic ganglia
(vertebral or lateral ganglia); these two sets of ganglia Gaskell
terms proximal. By means of the branches from the sympathetic ganglia
(Rami efferentes) part of the fibres pass to another set of
ganglia, the solar plexus, etc., which he terms prevertebral or
collateral; from these the fibres pass to be distributed to the various
viscera and blood-vessels, where a fourth set of very small ganglia
(terminal ganglia) is found. The prevertebral and terminal ganglia
are together classed as distal ganglia. Gaskell holds that the fine
medullated fibres from the cord lose their medullary sheath in one or
other of these ganglia according to the function they fulfil.
The inhibitory fibres of the heart and vaso-dilator fibres of the
blood-vessels continue as white fibres along the vago-sympathetic and
spinal nerves to the distal ganglia (Bidder’s ganglion, etc.), where
the medullary sheath disappears: whereas the ‘augmentor’ fibres of
the heart and vaso-constrictor fibres of the blood-vessels lose their
medullary sheath in the proximal ganglia and pass on as non-medullated
fibres. In the same way the nerve-fibres that bring about contraction
of the circular muscle fibres of the hollow viscera lose their
medullary sheaths in the proximal ganglia, while those fibres, the
influence of which negatives the former, become pale fibres in the
distal ganglia.
Waters has demonstrated that in the frog the various spinal nerves
have each a localised physiological action upon the blood-vessels and
muscular walls of various parts of the alimentary canal: he shows
that
The third spinal nerve supplies the oesophagus.
The fourth spinal nerve supplies the stomach.
The fifth spinal nerve supplies the upper third of the small
intestine.
The sixth spinal nerve supplies the lower two thirds of the small
intestine.
The seventh spinal nerve supplies the large intestine.
The eighth spinal nerve supplies the bladder, this supply being,
however, not so definite as the others given above.
It has long been known that the branches of the spinal ganglia
(ganglia of the posterior roots) are together larger (one-third,
Lenhossék), and contain more fibres than the ventral and dorsal roots
together; this is supposed to be in part due to an acquisition of new
fibres derived from the ganglia. The majority of recent observers
hold that each ganglionic cell has only one process, which, however, soon bifurcates;
whether any of the fibres so formed pass as far as the cord or beyond
its blood-vessels is doubted by most observers, and denied by Gaskell.
These remarks and the description of the cells of the spinal ganglia
(p. 176) hold good for the lateral or vertebral ganglia and the
prevertebral ganglia (solar ganglion, etc.) of the sympathetic system;
the terminal ganglia will be described with the organs in which they
are found.
(In order to render the foregoing description
of the nervous system more complete, the following notes have been
added by the translator.)
[The histological elements of the nervous system are nerve-cells
and nerve-fibres; of these the nerve-cells have been described with
the parts in which they occur; it may simply be remarked that later
observers have been unable to discover the ‘spiral cells’ described by
Beale, Arnold, and others. The nerve-fibres, as in most other animals,
are of two kinds, medullated and non-medullated.
1. Medullated nerve-fibres or white fibres are found in all
cranial and spinal nerves, with the exception of the olfactory nerves,
and in many of the sympathetic nerves (see Sympathetic System); also in
the white matter of the brain and spinal cord; examined microscopically
the fibres are seen to consist of an external sheath or neurilemma, a
medullary sheath, and an axis-cylinder:—
a. The neurilemma (Sheath of Schwann, Outer or Primitive
Sheath) is a nucleated endothelial layer covering the nerve-fibre;
it is continuous with the corresponding coat of the nerve-cells, and
is uninterrupted throughout the length of the nerve; at the nodes,
however, it dips down towards the axis-cylinder, the circular groove so
formed being filled with cement substance.
b. The medullary sheath (White substance of Schwann);
the presence of this sheath is the chief cause of the whiteness of
these nerves; the thickness of the sheath varies considerably, and
towards the ultimate distribution of the nerve it is entirely lost.
At more or less regular intervals along the course of the nerve-fibre
the continuity of the medullary sheath is broken, and gives the
fibres the appearance of being constricted at these places; such
constrictions are known as nodes of Ranvier; the portion between two
such nodes being termed an internode. Each internode possesses an oval,
flattened, granular nucleus at about its middle
and placed between the neurilemma and the medullary sheath; the nucleus
has a nucleolus. In the fresh state the medullary sheath seems to be
fluid; it is of a fatty nature.
Medullary segments are caused by breaks in the continuity of the
medullary sheath, which are seen only in nerves which are no longer in
their normal condition, and are especially well marked after treatment
with osmic acid. The breaks are oblique; hence the conical end of one
segment fits into the funnel-shaped end of the next. How far they
correspond to pre-existent structures is uncertain. The segments in the
frog vary in length from 0.010 to 0.040 mm.
c. The axis-cylinder is the essential part of every
nerve-fibre; it shows a longitudinal striation corresponding to the
fine fibrils (primitive fibrillae) of which it consists; these fibrils
often exhibit minute varicosities: at times it has the appearance
of being invested with a very delicate structureless sheath. It is
continuous through the nodes of Ranvier.
2. Non-medullated nerve-fibres (Grey or Varicose Fibres;
Fibres of Remak); these occur chiefly in branches and plexuses of the
sympathetic system; they consist of a neurilemma and an axis-cylinder,
which agree exactly with the corresponding elements found in the
medullated fibres.
The nerve-fibres, whether medullated or non-medullated, are bound
together by connective-tissue to form nerves. A number of fibres bound
together by connective-tissue to form a slender cord is known as a
funiculus; a small nerve may consist of one such funiculus; the sheath
surrounding it is known as the perineurium, and sends in supporting
processes between the fibres (endoneurium): when several funiculi are
bound together to form a large nerve the common sheath is known as the
epineurium. These sheaths support nerves (nervi nervorum) and
vessels (vasa vasorum) supplying the nervous elements, and their
intercellular spaces form lymph-canals. The whole nerve is surrounded
by an endothelial coat, which helps to form a lymph-space, which more
or less completely surrounds the nerve.
The ultimate distribution of the nerve-fibres will be included in
the description of the various organs in which they end.]
SECTION IV. THE VASCULAR SYSTEM.
THE VASCULAR SYSTEM.
LITERATURE.
THE HEART AND BLOOD-VESSELS.
Aeby, Ueber den feineren Bau der Blutcapillaren. Centralbl.
f. d. med. Wiss. 1865, p. 209.
Altmann, R., Ueber Corrosion in der Histologie. Centralbl. f.
d. med. Wiss. 1878, p. 245.
Aubert, H., Die Innervation der Kreislaufsorgane. Hermann’s
Handbuch der Physiologie. Leipzig, 1880. Vol. VI, Pt. I, p. 377.
Beck, K., Zur Kenntniss der Herznerven. Arch. f. mik. Anat.
1884. Vol. XXIV, pp. 11–19.
v. Bezold, Untersuchungen über die Innervation des Herzens.
Leipzig, 1863.
Bidder, F., Ueber functionell verschiedene und räumlich
getrennte Nervencentra im Froschherzen. Arch. f. Anat. u. Physiol.
1852, p. 163.
Bidder, F., Zur näheren Kenntniss des Froschherzens und
seiner Nerven. Arch. f. Anat. u. Physiol. 1866, p. 1.
Bidder, F., Endigungsweise der Herzzweige des N. vagus beim
Frosche. Arch. f. Anat. u. Physiol. 1868, p. 1.
Bidder, F., and Gregory, Beiträge zur Physiologie der
Herzbewegung beim Frosche. Dorpat, 1865.
Boas, J. E. V., Ueber den Conus arteriosus und die
Arterienbogen der Amphibien. Morph. Jahrb. 1881. Vol. VII,
pp. 271–273.
Boas, J. E. V., Beiträge zur Angiologie der Amphibien. Morph.
Jahrb. 1882. Vol. VIII, pp. 169–187.
Bobretzky, C., Ueber die Entwickelung der Capillargefässe.
Centralbl. f. d. med. Wiss. 1885, p. 769.
Bremer, L., Die Nerven der Capillaren der kleinen Arterien
und Venen. Arch. f. mik. Anat. 1882. Vol. XXI, p. 663.
Brenner, A., Ueber das Verhältniss des N. laryngeus inferior
vagi zu einigen Aortenvarietäten des Menschen und zu dem Aortensystem
der durch Lungen athmenden Wirbelthiere überhaupt. Arch. f. Anat. u.
Physiol. 1883, pp. 373–397.
Brücke, E., Ueber Mechanik des Kreislaufes des Blutes bei
Fröschen. Wiener Sitzungsb. 1851. Vol. VI, p. 61; also p. 114.
Brücke, E., Beiträge zur vergl. Anatomie u. Physiologie des
Gefässsystems der Amphibien. Denkschriften d. Wiener Academie. 1852.
Vol. III, p. 335.
Burdon-Sanderson, J., Circulation of the Blood, in Handb. for
the Physiological Laboratory. London, 1873.
Burow, De vasis sanguiferis ranarum. Diss. inaug.
Regiomontani, 1834.
Calori, L., Sugli organi della circulatione e della
respirazione dei gyrini della Rana esculenta e della Salamandra
cristata. Nuov. Ann. delle Scienz. nat. de Bologna. 1838.
Champness, F., The Septum Atriorum of the Frog and the
Rabbit. Journ. of Anat. and Physiol. 1874, p. 340.
Chapmann, S. H., Beiträge zur Kenntniss des Baues des
normalen und entzündeten Pericardiums der Batrachier. Wiener Med.
Jahrbücher.
Chrzonzczewsky, N., Ueber die feinere Structur der
Blutcapillaren. Virchow’s Arch. 1866. Vol. XXXV, p. 169.
Darwin, F., Contributions to the anatomy of the sympathetic
ganglia of the Bladder in their relation to the vascular system. Quart.
Journ. Micros. Sci. 1874. Vol. XIV, p. 109.
v. Deen, De differentia et nexu inter nervos vitae animalis
et vitae organicae. Diss. inaugur. Lugduni; also in Arch. f. Anat. u.
Physiol. 1834, p. 477.
v. Deen, Over de zijelingsche Takken dar zwervende van den
Proteus anguinis (includes frog-larva). Bijdragen tot de Naturkundige
Wetenschappen. 1834.
Dogiel, J., Die Ganglienzellen des Herzens bei verschiedenen
Thieren und beim Menschen. Arch. f. mik. Anat. 1877. Vol. XIV,
p. 471.
Dogiel, J., Die Nervenzellen und Nerven des Herzventrikels
beim Frosche. Arch. f. mik. Anat. 1882. Vol. XXI, p. 21.
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Wiener Sitzungsb. 1878. Vol. LXXVI, Pt. III, p. 7.
Thoma, R., Die Ueberwanderung farbloser Blutkörperchen von
dem Blut in das Lymphgefässsystem. Heidelberg, 1873.
Welcker, H., Grösse, Zahl, Volum, Oberfläche und Farbe
der Blutkörperchen bei Menschen und Thieren. Henle u. Pfeuffer’s
Zeitschr. 1864. Vol. XX, pp. 258–307.
PART 1. THE HEART AND BLOOD-VESSELS. — I. THE HEART. — II. THE ARTERIES. — III. THE VEINS.
(The original arrangement of this section has been
modified.)
The heart is situated in the middle line above the central portion
of the shoulder-girdle and M. sternohyoideus, and below the
oesophagus; the apex is directed backwards and lies between the lobes
of the liver, the base is directed forwards and lies a short distance
behind the larynx. The heart is surrounded by the pericardium.
Fig. 132.
The heart and blood-vessels, seen from the ventral
surface; after Howes.
AC.
Left anterior caval vein.
C′.
Carotid arch.
LA.
Left auricle.
P′.
Right pulmo-cutaneous arch.
RA.
Right auricle.
S′.
Left systemic arch.
TA.
Truncus arteriosus.
V.
Ventricle.
A. The Pericardium [is a very thin membranous
sac, which completely encloses the heart; it is attached, at some
distance, to the large vessels passing to and from the heart, and
has inserted into it some fibres of the M. obliquus abdominis
internus (see page 70). A fold of the pericardium extends from the
dorsal surface to the truncus arteriosus, and through it courses the
vena cardiaca.
The pericardium is a connective-tissue membrane, and is lined on
either side with endothelium, which is in part ciliated (Leydig); the
endothelium of the inner surface is continued on to the heart and so forms a closed
lymph-sac. The pericardium is more or less pigmented, and contains both
vessels and nerves; it may contain fat-cells].
B. The Heart.
[The heart is a hollow muscular organ, composed of: (1) two
auricles, forming the wider anterior portion; (2) the ventricle,
placed behind the auricles; (3) the sinus venosus, situated dorsally;
and (4) the truncus arteriosus, lying ventrally. Examined while
still living, the auricles are seen to be much darker in colour than
the ventricle, due to the blood being seen through their thinner
walls; between the auricles and the ventricle is a distinct groove,
the auriculo-ventricular groove. The whole organ is more or less
pigmented, especially the ventricle (R. temporaria has much less
pigment).]
Fig. 133.
The heart, seen from above, and dissected to show the
opening from the Sinus venosus to the right auricle;
after Howes.
C′.
Right carotid arch.
IC.
Posterior caval vein.
LA.
Left auricle.
P′.
Right pulmo-cutaneous arch.
PV.
Pulmonary vein.
RA.
Right auricle.
S′.
Right systemic arch.
SV.
Sinus venosus.
SV′.
Opening of Sinus venosus into the right auricle.
V.
Right anterior caval vein.
a. The Sinus venosus (Sinus venarum cavarum),
(Fig. 133 SV.) is a thin-walled sac lying on the dorsal surface
of the heart, and very slightly to the right side (Hoffmann). It is
somewhat triangular in form, receiving an anterior caval vein at each
anterior angle (V.), and the posterior caval vein (IC.)
at the posterior angle. The ventral wall has a transverse opening
(SV′.), by which it communicates with the right auricle; the
opening possesses two valves, an anterior and a posterior, and is
placed close to the auricular septum.
Fig. 134.
The frog’s heart seen from the ventral surface, and
dissected so as to show its structure. The ventral
walls of the truncus arteriosus and of the
auricles and ventricle have been removed. From
a drawing by Mr. Hurst.
A.
Auriculo-ventricular aperture and valve.
B.
Aperture leading from ventricle to truncus arteriosus.
C.
Left carotid arch.
LA.
Left auricle.
P.
Left pulmo-cutaneous arch.
P′.
Style passed down right pulmo-cutaneous arch into the truncus arteriosus, T.
PV.
Opening of pulmonary vein.
RA.
Right auricle.
S.
Left systemic arch.
SA.
Septum atriorum.
SV.
Opening of Sinus venosus into right auricle.
V.
Ventricle.
b. The auricles [are not always separated, as the
septum which usually brings about the separation is in some cases
incomplete, and in rare instances appears to be absent (Hoffmann)];
according to Ecker, the auricular septum is sometimes placed so far to
the left side that it
appears to be absent (Fig. 135). The septum is attached to the walls
of the auricles so as to form two distinct cavities, which communicate
at the auriculo-ventricular opening, where the septum has a free
concave border (Fig. 134). The right auricle is much larger than the
left, and receives the systemic venous blood from the sinus venosus
by the opening (Figs. 133 and 134 SV.) already described. The
left auricle receives the blood from the lungs by the pulmonary vein
(Fig. 133 PV.), which opens into the auricle near the septum
(Fig. 134 PV.): [the openings from the sinus venosus and from
the pulmonary vein may be so closely approximated as to be separated by
the septum only. The septum is much thinner than the auricular walls].
Both auricles open into the ventricle by the auriculo-ventricular
opening (Fig. 134).
Fig. 135.
Dissection of a case in which the auricular septum is placed more to
the left than is normal.
S
Septum.
SS
Left auricle.
V
Opening into the Sinus venosus.
c. The ventricle (Figs. 132, 134, and 136 V.),
examined while still living, is seen to be bluntly conical in shape
and darker on the left side than on the right; this is due to the
ventricular wall of the right side, near the truncus arteriosus, being
somewhat thinner. The inner wall is not smooth but possesses muscular
ridges (Trabeculae). At its base the ventricle communicates
with the auricles by the auriculo-ventricular opening (Figs. 134
and 136), and with the truncus arteriosus by a separate opening
(Fig. 134 A.). The ventricle is lined by a layer of endocardial
endothelium.
Fig. 136.
Dissection of the heart from the left side; after Howes.
A.
Auriculo-ventricular opening.
AC.
Anterior caval veins.
IC.
Posterior caval vein.
LA.
Left auricle.
PV.
Pulmonary vein.
RA.
Right auricle.
SV.
Sinus venosus.
TA.
Truncus arteriosus.
V.
Ventricle.
The auriculo-ventricular opening (Fig. 134 A.) is a
large aperture guarded by two valves, a dorsal and a ventral: each
valve is formed by a reduplication of the endothelium, and contains a
small amount of connective-tissue; its free margin is bound down by a
number (about twelve) of fibrous cords, the chordae tendineae,
which are attached by their posterior extremities to the trabeculae.
d. The truncus arteriosus (Figs. 132TA., 134
A.) arises at the base of the ventricle, on the right side of
its ventral surface, then passes forwards and to the left, across the
auricles, to reach their anterior border near the median line, where it
divides to form two vessels.
Internally it is incompletely divided into two compartments by a
spiral valve (Fig. 134); the valve is attached to the dorsal surface
and is free ventrally: when the vessel is fully dilated (artificially),
the valve extends two-thirds of its diameter. The opening of the
vessel into the ventricle is guarded by two semilunar valves (Fig. 134
A.), the free margins of which are bound to the inner surface
of the tube by chordae tendineae. The distal extremity has a
semi-lunar valve in the left compartment (Fig. 134), which is attached
by a delicate band to the spiral valve (Ecker).
C. The minute structure of the Heart.
[The heart consists chiefly of muscle, but possesses also
nerve-fibres, nerve-cells, endothelium, and connective-tissue; the
truncus arteriosus has, in addition, blood-vessels.
a. The muscular structure of the
heart.
Fig. 137.
I. Transverse section through the junction of the hinder and middle
thirds of the ventricle of R. temporaria. II. Transverse section
through junction of middle and anterior thirds of the same heart. Occ.
I, Syst. 1, Leitz. The heart was freely distended62 with dilute spirit, and so
hardened.—G. H.
CC
Central cavity.
CM
Circular muscle.
LM
Longitudinal muscle.
TM
Transverse muscle.
(1) The arrangement of the muscle-fibres varies in the
different portions of the heart. That of the ventricle will be easily
understood by reference
to Fig. 137. A layer of circular fibres (CM) extends round the
whole ventricle, and from it more or less radial or transverse bands
(TM, also Fig. 138 TM) pass inwards; these, in the apical
portion of the ventricle, seem to extend almost transversely across;
towards the base they are directed onwards and forwards towards the
auricles. Of these bands some, near the apex, can be traced directly
to the opposite side, others join the wall more anteriorly, and
still others join bands of muscular fibres (LM), which may be
described as longitudinal, and form the Musculi papillares. In
the anterior portion of the ventricle the same arrangement holds good,
but is modified to form a central cavity; still more anteriorly, at the
junction of auricles and ventricle, the trabecular structure is much
less apparent, the fibres being closer and mainly circular.
In the auricles the muscular fibres are chiefly arranged in
circular rings which cross one another; on the inner surface, however,
traces of an arrangement similar to that in the ventricle may be
made out. In the heart, from which the sections in Fig. 137 were drawn, transverse bands
(cut longitudinally), 0.33 mm. in length, were numerous; their central
ends terminated in bands, the fibres of which were cut transversely.
The auricular septum (Fig. 141M) also possesses muscular
fibres which cross one another in its substance.
The fibres of the truncus arteriosus resemble those of an ordinary
artery; those of the sinus venosus are arranged in rings, mostly
transverse, but others oblique, and a few longitudinal.]
(2) The structure of the cardiac muscle-fibres
(Figs. 138 and 141 a).
Fig. 138.
Portion of a transverse section through the middle of the ventricle
of R. temporaria. From same heart as the sections in Fig. 136.
Oc. I. Syst. 7, Leitz.—G. H.
A
Rod-shaped nuclei of muscle fibre.
B
Oval nuclei of muscle fibre.
CM
Circular layer of muscle.
CT
Connective-tissue.
E
Endothelium of the epicardium.
TM
Transverse bands of muscle.
[The cardiac muscle of the frog consists of spindle-shaped cells,
which as Pohl-Pincus pointed out, are of two kinds; the main difference
between the two being in the size of the nucleus, which is much broader
in one than in the other.
α. Cells with a broad nucleus (Fig. 138 B): the nucleus is
lenticular or egg-shaped, 4 to 7 µ broad, 8 to 14 or 18 µ long; the
ratio of length to breadth being 1 : 2.
β. Cells with a narrow nucleus (Fig. 138 A): the nucleus
is rod-shaped, 2·5 to
3·5 µ broad and 25 to 43 µ in length. The ratio of length to breadth
varying from 1 : 8 to 1 : 16. These cells are more frequent in the
right half of the base of the ventricle than the former variety. In the
trabeculae the second variety is more numerous (Pohl-Pincus).
The muscle-fibre may be simple (Fig. 141 a M) or possess
branches (Fig. 138); the fibres are all more or less spindle-shaped,
and striated transversely and longitudinally, but possess no
sarcolemma. The protoplasmic contents of the cell are finely granular;
the nucleus much more coarsely granular and possessing one or more
distinctly marked nucleoli. The striations are due to the presence
of a network, which has been carefully described by Messrs. B.
Melland and C. F. Marshall63, and is similar to that of ordinary voluntary
muscle (see histology of muscle).]
b. The nerves of the heart.
Fig. 139.
Course of the cardiac nerves in the auricular septum.
d
Dorsal nerve.
v
Ventral nerve.
Fig. 140.
Group of nerve-cells on the cardiac nerve, from
the auricular septum. Stained with picrocarmine.
Occ. III, Syst. 3, Hartnack; after Dogiel.
F
Fibres of the cardiac nerve.
G
Nerve-cells.
The nervous supply of the heart is derived from the sympathetic
system and from the cardiac branches of the pneumogastric nerve; the
course of which has already been traced (page 175) to the roots of the
anterior caval veins, where they form a simple plexus by means of a
connecting link (Fig. 139). The plexus possesses nerve-cells and sends
off two nerves into the auricular septum; the one (d) lies
dorsally and is shorter and thicker than the other (v), which
lies ventrally in the septum. They course backwards to the posterior
border of the septum, and there distribute fine branches to the base of
the ventricle and surrounding parts.
[In the whole of their course in the heart they have numerous
nerve-cells, either imbedded between their fibres or attached to the
nerves and their branches.
The nerve-fibres are both medullated and non-medullated.
The nerve-cells (Figs. 139, 140, 141) are usually oval, and are unipolar or rarely
bipolar; sometimes two cells exist in the same envelope, forming
the ‘twin-cells’ of Dogiel (Fig. 141 b II). According to the recent
observations of Lavdowsky and Dogiel each cell receives one medullated
fibre and gives off a fine non-medullated fibre; the two run together
for a short distance, after which the non-medullated fibre separates to
supply muscle-fibres.
Fig. 141 a.
Small group of nerve-cells from the auricular septum. Stained with
picrocarmine and silver nitrate, after Dogiel.
E
Endothelium (endocardium).
G
Nerve-cells.
M
Muscle-fibres.
N
Nucleus.
N′
Nucleolus.
Fig. 141 b.
Isolated nerve-cells from frog’s heart. I. Usual form of nerve-cell.
II. ‘Twin-cell.’
C
Capsule.
N
Nucleus.
N′
Nucleolus.
P
Process.
Two large clusters of nerve-cells have received special names.
Remak’s ganglion is a large group of nerve-cells in the wall
of the sinus venosus.
Bidder’s ganglion is formed, collectively, by groups of cells
in the auriculo-ventricular groove, the chief groups being attached to
the two cardiac nerves.
No nerve-cells have been discovered behind that portion of the
ventricle near the auriculo-ventricular groove, nor has a direct
connection between the cells or their processes with the fibres of the
pneumogastric nerve been made out.
c and d. [The endothelium and
connective-tissue of the heart.
Fig. 142.
Arteries and veins of the Truncus arteriosus of Bufo vulgaris, after
Hyrtl.
a
Arteria bulbi.
b
Truncus arteriosus.
h, i
Hepatic portal veins.
t
Right and left synangium.
v
Vena bulbi anterior.
vi
Left innominate vein.
vc
Vena bulbi posterior (V. cardiaca).
A
Right auricle.
A′
Left auricle.
V
Ventricle.
Nerve-fibres have been described as existing in all parts of the
ventricle and being connected with the muscle-fibres (Openchowsky and
others); this cannot, as yet, be accepted as proved.
The truncus arteriosus also possesses nerve-fibres and nerve-cells
(Pagliani, Löwit, and others), but their arrangement seems to be very
irregular. Löwit did not succeed in finding the nerve-cells in all
cases examined; and Engelmann denies their occurrence.]
The connective-tissue of the heart exists only in very small
quantity. A fine layer on the outer surface of the ventricle,
especially towards the auriculo-ventricular groove, can easily
be seen (Fig. 138CT); the various valves, the auricular
septum, and more particularly the truncus arteriosus, all contain
connective-tissue. In
the latter part the spiral valve is wholly formed of this tissue.
The whole of the inner surface is lined with endothelium (endocardium), which
covers the various trabeculae; the external surface of the heart is
likewise covered with an epicardial layer of endothelium (Fig. 138E).]
e. The blood-supply to the heart.
With the exception of the truncus arteriosus, no part of the
heart possesses blood-vessels (Hyrtl). [The truncus arteriosus
(Fig. 142 b) has a rich anastomosis, which receives its blood
by the arteria bulbi (a), a branch of the carotid arch.
Two veins connect this anastomosis with the systemic veins, and with
the hepatic portal veins: the former, vena bulbi anterior
(v), passes over the auricles to open into the left innominate
vein (vi); the latter, the vena bulbi posterior
(vc) or vena cardiaca, as it is more usually named,
passes from the truncus arteriosus in a fold of pericardium, and
then courses backwards to open into the anterior-abdominal vein.]
(The original arrangement of this section has been
modified.)
The Truncus arteriosus divides to form two vessels
(Figs. 132, 134); each of these is divided by two partitions into three
compartments, which after a short course together separate to form
three distinct vessels, the carotid, systemic, and pulmo-cutaneous
arches.
1. The carotid arch (Canalis
carotico-lingualis, Brücke; Ductus caroticus), (Fig. 143I) is the most anterior of the three arches: it winds round
the side of the oesophagus as far as the carotid gland, where it
divides to form two branches; the right carotid arch gives off a small
branch to the Truncus arteriosus, the Arteria bulbi (see
above).
Fig. 143.
Schema of the arterial system of Rana esculenta.
A
Dorsal aorta.
c
Cutaneous artery.
ca
Carotid artery.
d
Carotid gland.
ic
Iliac arteries.
ie
External iliac artery.
ii
Internal iliac artery.
J
Mesenteric artery.
l
Lingual artery.
o
Occipital artery.
ov
Occipito-vertebral artery.
P
Pulmonary artery.
s
Subclavian artery.
T
Truncus arteriosus.
ug
Urinogenital arteries.
v
Vertebral artery.
I
Carotid arch.
II
Systemic arch.
III
Pulmo-cutaneus arch.
The carotid gland (Fig. 144 c′) is a dilated portion
of the vessel. The interior contains bands or trabeculae of muscle,
which give its walls a
more or less spongy structure; the muscle-fibres are not transversely
striated (Hoffmann).
Fig. 144.
Right carotid gland.
c
Carotid arch.
c′
Carotid gland.
c″
Carotid artery.
L
Lingual artery.
a. The lingual artery (Arteria lingualis,
Arteria hyoidea-lingualis, Arteria hyoidea), (Figs. 143
l, 144 L) arises by two roots from the inner surface of
the carotid gland, and courses forwards and inwards, supplying branches
to the thyroid gland and the Musculi geniohyoidei, to the
ventral surface of the hyoid; another continues forwards on the outer
border of the M. hyoglossus to supply branches to the hyoid and
tongue.
b. The carotid artery (Arteria carotis
communis), (Figs. 143 ca, 144 c″) arises by several
roots from the outer wall of the carotid gland; and passes over the
Musculus petrohyoideus I to the anterior end of the oesophagus,
round which it courses towards the vertebral column, and then runs
forwards to the base of the skull. The artery then courses forwards,
lying immediately above the mucous membrane and underneath the
transverse arm of the parasphenoid, which it crosses about midway
between its back and external end; [at this point the artery gives off
two palatine arteries, then ascends in the orbit to the origin of the
M. pterygoideus, and divides into two branches, the internal
carotid artery and the ophthalmic artery]. The branches are:—
Fig 145.
Arterial system of Rana esculenta.
A
Dorsal aorta.
Ad
Right systemic arch.
As
Left systemic arch.
c
(opposite fore-limb) Carotid artery.
c
(in abdomen) Coeliac artery.
cm
Cutaneous artery.
e
Lingual artery.
H
Heart.
H′
Harderian gland.
L
Liver.
Lu
Lung.
m
Mesenteric artery.
M
Stomach.
M′
Spleen.
o
Ophthalmic artery.
p
Pharyngeal artery.
p′
Anterior palatine artery.
S
Subclavian artery.
I
Carotid arch.
II
Systemic arch.
III
Pulmo-cutaneous arch.
(1) The pharyngeal artery (Arteria pharyngea ascendens),
(Fig. 145 p) which runs towards the opening of the Eustachian
tube, distributes branches to the pharynx, and anastomoses with the
Arteria pharyngeo-maxillaris of the cutaneous artery, and with
the Ramus inframaxillaris of the occipital artery.
(2) [The posterior palatine artery (Arteria palatina
posterior, Virchow) immediately divides into a number of small
twigs to supply the mucous membrane of the hinder and outer parts of
the gums.]
(3) The anterior palatine artery (Arteria palatina anterior,
Virchow; Arteria palatina, Ecker), (Fig. 145 p′) runs
forwards, between the Musc. levator bulbi and the mucous
membrane, with the Ramus palatinus of the trigeminal nerve. [On
reaching the palatine bone, it curves outwards to the outer anterior
angle of the orbit, where it gives off a branch backwards along the
upper jaw to the hinder portion of the orbit.] In its course it
supplies twigs to the
surrounding tissues, but chiefly to the mucous membrane and Harder’s
gland.
(4) The internal carotid artery (Art. cerebralis, Virchow);
see Arteries of Brain, p. 162.
(5) The ophthalmic artery (Art. ophthalmica), (Fig. 145
o) [is larger than the internal carotid artery at this point;
it crosses the origins of the M. rectus externus and of the
M. retrahens bulbi and reaches the optic nerve; the artery
then runs forwards along the under surface of this nerve and of the
eyeball, lying close to the sclerotic coat as far as a little beyond
the equator, where it pierces the sclerotic coat so obliquely that the
choroid coat is only
reached at the ciliary processes. In its course the artery
supplies:—
α. Muscular branches, given off at the point where the artery
reaches the eyeball.
β. Two arteries (AA. ciliares) to the choroid, given off at
the same point as the foregoing.
γ. Two arteries to the iris.
δ. The Art. hyaloidea, the terminal portion of the ophthalmic
artery. (For further description of these vessels, see Eye.)].
2. The systemic arch (Ductus
aorticus), (Figs. 132, 143, and 145 II) is the middle
arch of the three; it arises from the middle canal of the Ductus
arteriosus, and winds obliquely round the oesophagus between
the MM. petrohyoidei I and II towards the vertebral
column, which it reaches at about the level of the sixth vertebra. The
right systemic arch is continued as the dorsal aorta, the left arch
communicates with it merely by a small opening, and is then continued
as the coeliaco-mesenteric artery.
Branches of the systemic arch:—
Fig. 146.
Transverse section at level of the larynx.
C
Carotid gland.
G
Glottis.
lg
Laryngeal artery.
S
Subclavian artery.
I
Carotid arch.
II
Aortic arch.
a. The laryngeal artery (Arteria laryngea),
(Fig. 146lg) arises from the inner border of the systemic arch
before it reaches the oesophagus; it passes forwards and inwards to be
distributed in the larynx and pharynx. According to Brücke this artery
possesses a valve at its point of origin.
b. The oesophageal arteries (Arteriae
oesophageae) pass from the upper part of the arch to the dorsal
surface of the oesophagus.
α. The Rami spinales, which pass through the intervertebral
foramina to the spinal cord (see Arteries of Spinal Cord, p. 162).
Fig. 147.
Dissection to show the occipito-vertebral and the cutaneous arteries.
The skin of the back has been divided by a median incision and drawn to either side; the right arm
dislocated and removed through the opening in the skin (at A). On the left side the extensor
muscles of the back have been removed.
c.m.
Cutaneous artery.
c.p.
Arteria cutanea pectoris.
o
Occipital artery.
s
Scapular artery.
v
Vertebral artery.
c. The occipito-vertebral artery (Ecker), (Art.
occipito-vertebralis), (Fig. 147 o, v) [arises from
the systemic arch immediately in front of the transverse process
of the second vertebra, and ascends immediately in contact with
the body of the first vertebra, which it separates from the MM.
intertransversarii capitis and the sympathetic cord]. Immediately
under the most anterior portion of the M. longissimus dorsi
the artery divides into two branches, the vertebral and occipital
arteries:—
(1) The vertebral artery (Arteria vertebralis or
supra-vertebralis)
(Fig. 147 v) courses backwards lying on the transverse processes
of the vertebrae and on the MM. intertransversarii, under cover
of the M. longissimus dorsi. In this course it is close to the
oblique processes, and may even be partially covered by these; it
extends beyond the sacrum, and gives off:—
β. The Rami dorsales; these supply the muscles of the
back and send branches to the skin, which accompany the cutaneous
branches of the spinal nerves through the Saccus lymphaticus
cranio-dorsalis.
γ. The Rami intercostales are distributed in part to the
MM. intertransversarii; other twigs pass ventrally to the
periganglionic glands; the longest branches accompany the anterior
divisions of the spinal nerves to the muscles and skin of the belly
(Fig. 145).
(2) The occipital artery (Arteria occipitalis),
(Figs. 147 and 148 o), the anterior branch of the
occipito-vertebral artery, pierces the M. longissimus dorsi;
then courses forwards under cover of the Fascia dorsalis and
upon the M. temporalis, and divides, behind the eyeball [at
the anterior border of the M. temporalis, Virchow], into two
branches:—
Fig. 148.
Branches of the occipito-vertebral and cutaneous arteries in the
head; side view. The skin (H) has been reflected downwards.
c.m.
Cutaneous artery.
l.a.
M. levator scapulae.
m
Art. maxillaris communis.
m′
Art. maxillaris superior.
m″
Art. maxillaris inferior.
o
Occipital artery.
on
Art. orbito-nasalis.
p.m.
Art. pharyngo-maxillaris.
v
Vertebral artery.
α. The Ramus orbito-nasalis (Fig. 148 on) accompanies
the ophthalmic nerve along the wall of the cranium, and passes through
the sphenethmoid, with the nasal branch of the ophthalmic nerve, to the
nose, where it divides into two branches supplying the mucous membrane
of the nose. In its course through the orbit the artery supplies
branches to the Harderian gland and neighbouring parts, and anastomoses
with the ascending branch of the Arteria palatina.
β. The Ramus maxillaris communis (Art. temporalis,
Virchow), (Fig. 148 m) runs downwards and outwards along the
anterior border of the M. temporalis, and passes under the
anterior arm of the squamosal bone to course backwards on the upper
jaw. At this point the Ramus maxillaris superior (m′)
is given off. The main artery continues its backward course to
the tympanic membrane, where it divides into its three terminal
branches:—
[(1) The Ramus maxillaris superior (AA. maxillares
superiores, Virchow), usually not a single artery but a number
of small twigs, which supply the space between the eye and the upper
jaw.
(2) A small ascending branch to the tympanic membrane (Virchow).
(3) A Ramus auricularis (Virchow), which forms a rich
anastomosis on the hinder wall of the tympanic cavity, and supplies
a twig to the tympanic membrane. This passes from the upper border of the membrane to the
point of attachment of the Columella auris (extrastapedial),
round which it forms a circular anastomosis. The Ramus
auricularis also anastomoses with the cutaneous artery.
(4) A branch passing inwards to the fat-body, and lying immediately
in front of the deltoid muscle (Virchow).
(5) A small branch running on to the inner surface of the angle of
the jaw and then forwards (Virchow).
Fig. 149.
Dissection to show the occipito-vertebral and the
cutaneous arteries.
The skin of the back has been divided by a median incision and
drawn to either side; the right arm dislocated and removed through
the opening in the skin (at A). On the left side the extensor
muscles of the back have been removed.
c.m.
Cutaneous artery.
c.p.
Arteria cutanea pectoris.
o
Occipital artery.
s
Scapular artery.
v
Vertebral artery.
(6) A larger vessel, the Ramus maxillaris inferior
(Fig. 148 m″), which arises from the Ramus maxillaris
superior under cover of the tympanic membrane, and accompanies the
Ramus mandibularis of the trigeminal nerve through the M.
masseter, or between this muscle and the M. temporalis to
the mandible, and then courses forwards to the chin. A large cutaneous
branch is given off half-way along the floor of the mouth. The artery
gives off many small twigs to supply the neighbouring structures.]
3. The pulmo-cutaneous arch (Ductus
pulmo-cutaneus), (Figs. 132143, and 145III) is the
hindmost (fifth embryonic) of the three persistent arches; it passes
upwards and forwards on the oesophagus, and at the level of the carotid
gland divides into two branches, the pulmonary artery and the cutaneous
artery.
a. The pulmonary artery (Arteria pulmonalis)
runs backwards to the root of the lung, along the outer surface of
which it is continued in a sinuous course. It supplies the lung.
b. The cutaneous artery (Arteria cutanea
magna), (Fig. 149 c.m.) [passes along the deeper surface of
the M. petrohyoideus III until near the prootic bone; in this
course it travels forwards, outwards, and upwards, crosses the outer
border of the muscles, and appears between the M. levator anguli
scapulae and the M. sternocleidomastoideus. At this point
the artery curves sharply round to reach the angle of the jaw, the
hinder border of the M. depressor maxillae inferioris. The curve
so formed and the descending limb are covered by the M. depressor
maxillae inferioris. The artery then passes backwards to form a
rich anastomosis in the skin almost as far as the posterior end of the
trunk. It supplies the following branches:—
(1) The Ramus dorsalis (Virchow) arises immediately in
front of the curve of the main artery; it ascends behind the M.
temporalis, and passes along the anterior border of the M.
depressor maxillae to the skin, where it curves backwards. It
supplies small twigs forwards as far as the eyelids.
(2) The Ramus auricularis (Virchow) also arises in front
of the curve in the cutaneous artery; sometimes it arises from the
Ramus dorsalis. The artery winds around the M. petrohyoideus
III near its insertion, and so reaches the posterior wall of the
tympanic cavity, where it anastomoses with the R. auricularis of
the Ramus maxillaris communis.]
(3) The Arteria pharyngo-maxillaris (Fig. 148p.m.)
is a small branch running forwards and outwards to supply the mucous
membrane of the larynx, Eustachian tubes, gums, the lower jaw,
and the skin under
the mouth. It forms a rich anastomosis with branches of the Ramus
maxillaris inferior of the occipital artery, and with others from
the pharyngeal branch of the carotid artery; a large branch passes
forwards to supply the skin of the throat and floor of the mouth.
(4) The Arteria cutanea pectoris (Fig. 149c.p.) is
distributed to the skin of the breast.
Fig. 150.
Subclavian artery of the left side.
A
Systemic arch.
A′
Dorsal aorta.
c
Arteria cutanea medialis superior.
c′
Arteria cutanea medialis inferior.
ls
M. levator scapulae.
o.v
Occipito-vertebral artery.
p
Arteria pectoralis.
R
Radial artery
s
Subclavian artery.
U
Ulnar artery.
1
Arteria costo-cervicalis.
2
Arteria coraco-clavicularis.
3
Arteria scapularis posterior.
4
Arteria scapularis superior.
5
Cutaneous artery.
6
Arteria subscapularis.
4. The subclavian artery (Arteria
subclavia), (Fig. 150 s). The subclavian artery arises from
the systemic arch immediately behind the occipito-vertebral artery
at the level of the second or third vertebra. The artery then runs
outwards alongside and in front of the brachial nerve, between the
M. subscapularis and the M. triceps to the arm, where it
is known as the brachial artery; in its course it gives off:—
a. The Arteria costo-cervicalis (Fig. 150, 1). This
artery arises near the systemic arch, and runs backwards, parallel
to the vertebral column, over the brachial nerve, and across the
transverse processes of the vertebrae. It is distributed more
especially to the M. obliquus internus.
b. The Arteria coraco-clavicularis (Fig. 150, 2)
arises more externally than the last artery; it accompanies the
coraco-clavicular nerve on the dorsal surface of the ventral portion of
the shoulder-girdle, and passes between the M. deltoideus and
M. subscapularis into the Foramen ovale, where it divides
to supply these muscles and the M. pectoralis.
c. The Art. scapularis posterior (Fig. 150,
3), a small branch arising opposite at the tip of the
second transverse process and passing backwards over the MM.
transverso-scapulares, to which it is distributed.
d. The Art. scapularis superior (Fig. 150, 4)
accompanies several nerves between the M. subscapularis, M.
transverso-scapularis major, and the long head of the M.
triceps towards the dorsal surface, where it is distributed to the
MM. infraspinatus, latissimus dorsi, etc.
e. The Ramus cutaneus maxillaris.
f. The Art. subscapularis (Fig. 150, 6) is
distributed in the subscapular muscle.
A. The brachial artery (Arteria brachialis),
(Fig. 150) accompanies the brachial nerve under cover of the long
head of the M. triceps and over its inner head to the Plica
cubiti, into which it sinks near the tendon of the M.
sternoradialis; beyond this point it is continued as the ulnar
artery. In its course the brachial artery gives off:—
a. The Arteria pectoralis (Fig. 150 p).
b. The Arteria cutanea medialis superior (Fig. 150
c).
c. The radial artery (Arteria radialis),
(Fig. 150 R) which winds round the humerus with the radial nerve
between the muscles of the outer side of the forearm, to which it gives
branches: in the palm of the hand it passes between the M. extensor
carpi ulnaris and the M. flexor antibrachii to the dorsal
surface of the hand, where it anastomoses with the ulnar artery. In its
course it supplies:—
(1) Muscular branches to the surrounding muscles.
(2) The Ram. cut. radialis inferior, which arises from
the radial artery towards the distal end of the forearm, and passes
underneath the M. flexor carpi ulnaris to the skin.
Fig. 151.
Arteries of the palmar surface of the hand.
B
Ulnar artery.
ci
R. cutaneus medialis inferior.
d
Digital branches.
F
M. flexor digitorum communis.
II
Thumb.
V
Fifth finger.
Fig. 152.
Arteries of the dorsal surface of the hand.
B
Ulnar artery.
cri
R. cutan. rad. inferior.
R
Radial artery.
II
Thumb.
V
Fifth finger.
B. The ulnar artery (Arteria ulnaris), (Figs. 150
U, 151 B) accompanies the ulnar nerve towards the hand,
passes between the M. flexor digitorum communis and the M.
anconeus to the palm of the hand, and then winds round the outer
side to the dorsal surface of the carpus to form its terminal branches.
The branches are:—
(1) The Ram. cutan. med. inferior (Fig. 151 ci); it
arises near the wrist-joint and supplies (α) twigs to the skin of the
inner surface; (β) a branch downwards, which courses along the inner
side of the second finger to its tip; and (γ) a branch which passes
upwards to anastomose with the R. cutaneus medialis superior.
(2) In the palm of the hand a branch (Fig. 151 d) is given
off, which divides to form Arteriae digitales volares: one for
the second finger, two for the third finger, two for the fourth finger,
and one for the fifth finger.
(3) Given off on the dorsum of the hand (Fig. 152) it supplies
branches corresponding exactly with those of the palmar surface.
Fig. 153.
Arterial system of Rana esculenta.
A
Dorsal aorta.
Ad
Right systemic arch.
As
Left systemic arch.
c
(opposite fore-limb) Carotid artery.
c
(in abdomen) Coeliac artery.
cm
Cutaneous artery.
e
Lingual artery.
H
Heart.
H′
Harderian gland.
L
Liver.
Lu
Lung.
m
Mesenteric artery.
M
Stomach.
M′
Spleen.
o
Ophthalmic artery.
p
Pharyngeal artery.
p′
Anterior palatine artery.
S
Subclavian artery.
I
Carotid arch.
II
Systemic arch.
III
Pulmo-cutaneous arch.
5. The dorsal aorta (Aorta communis
s. abdominalis) (Fig. 153 A). The two systemic arches unite
at about the level of the sixth vertebra to form the dorsal aorta:
as already mentioned the union is very incomplete, the dorsal aorta
being practically a continuation of the right systemic arch, and only
communicating with the left by means of a small opening. The branches
are as follows:—
a. The coeliaco-mesenteric artery (Arteria
intestinalis communis), (Fig. 153), the true continuation of the
left systemic arch, at once divides to form the gastric and mesenteric
arteries.
(1) The gastric artery (Arteria gastrica s. coeliaca)
(c) immediately divides into two branches:—
α. The Ramus dexter s. anterior; this artery gives off the
Arteria hepatica to the liver and gall-bladder and passes to the
right (anterior) surface of the stomach, running along the attachment
of the mesentery and
supplying branches forwards to the oesophagus and backwards towards the
intestine.
β. The Ramus sinister s. posterior passes to the left
(posterior) surface and behaves like the Ram. dexter.
(2) The mesenteric artery (Arteria mesenterica
superior and inferior, and the Arteria splenica),
(Fig. 153 m) supplies:—
α. The superior mesenteric artery, which supplies the upper part of
the intestine, and gives off a recurrent branch to the stomach, which
anastomoses with the gastric arteries.
β. The splenic artery to the spleen.
γ. The inferior mesenteric artery to the lower part of the
intestine.
All the arteries to the intestine course in lymph-spaces.
Fig. 154.
The urinogenital arteries.
A
Dorsal aorta.
H
Testis.
N
Kidney.
ug
Urinogenital arteries.
b. The urinogenital arteries (Arteriae
urino-genitales), (Fig. 154 ug) are four to six small
arteries arising from the ventral surface of the aorta between the
kidneys: they immediately divide into right and left branches to supply
the kidneys, fat-bodies, reproductive organs, and their ducts (see
kidney).
c. The lumbar arteries (Arteriae lumbales),
are small paired vessels to the neighbouring muscles, and send
branches through the intervertebral foramina to the vertebral canal.
Sometimes these arteries arise from the Art. spinalis or Art.
vertebralis, etc.; in the former case they pass outwards from the
vertebral canal to the surrounding structures.
d. The haemorrhoidal artery (Art. mesenterica inf.
s Art. haemorrhoidalis superior) is a small median artery running
from the posterior end of the aorta to the large intestine.
6.Bifurcation of the aorta.The
iliac arteries (Arteriae iliacae communes). Opposite the
middle of the urostyle the aorta bifurcates to form the iliac arteries;
each of these courses on the corresponding sciatic plexus to the thigh,
beyond which it is continued as the sciatic artery. The branches of the
iliac artery are:—
a. The vesico-epigastric artery (Arteria
epigastrico-vesicalis), (Fig. 155 ev); it arises near the
bifurcation, passes outwards on the plexus, and divides into two
branches:—
Fig. 155.
Bifurcation of the aorta and the iliac arteries.
e
Epigastric artery.
ev
Vesico-epigastric artery.
f
Femoral artery.
o
Internal oblique muscle.
v
Vesical artery.
(1) The epigastric artery (Arteria epigastrica) (e)
immediately gives off a recurrent branch to the iliac bone and the
M. ilio-coccygeus; it then continues to the ventral muscles of
the abdominal wall, where it runs forwards on the deeper surface of the
M. obliquus internus, and is distributed more especially to this
muscle.
(2) The hypogastric artery (Arteria vesicalis) (v)
winds downwards around the sciatic plexus to reach the mesentery, along
which it courses to the bladder, where it forms a rich anastomosis.
b. The femoral artery (Arteria femoralis s.
cruralis), (Fig. 155 f) is the representative of the femoral
artery of man, although it does not perform the same functions. The
artery passes under the hinder free border of the M. obliquus
internus to the thigh, where it lies upon the M. ilio-psoas,
and sends twigs to the neighbouring muscles, the skin, and lymph-sac
(Lamina inguinalis), and then divides into:—
(1) A twig, which runs forwards on the ventral surface of the iliac
bone and is covered by the epigastric artery.
(2) A twig, running forwards and downwards on the MM.
ilio-psoas, vastus internus, and sartorius, to send
branches to the hip-joint.
c. The spermatic artery (Arteria spermatica),
which arises, in males, from the iliac artery, and ascends to the
Vesicula seminalis.
7.Arteries of the hinder extremity.
A. The sciatic artery (Arteria ischiadica), (Fig. 156i) is the continuation of the iliac artery; it leaves the pelvis
between the hinder (outer) border of the M. coccygeo-iliacus
and the inner surface of the origin of the M. ilio-psoas,
then lies between the former muscle and the origin of the M.
vastus externus. It appears on the thigh between the M. vastus
externus (in front) and the M. pyriformis (behind); it
is the main arterial trunk for the hinder extremity. The artery
courses backwards, lying upon the sciatic nerve and between the M.
biceps and the M. semimembranosus; in this course it runs
in a lymph-space placed in the Septum femorale superius (see
page 259). Arrived at the popliteal space the artery bifurcates to form
the peroneal and tibial arteries; near the pelvis it gives off two
branches (a) and (b), and in its course along the thigh
two branches (c) and (d).
a. The Art. haemorrhoidalis inferior (h) runs
backwards and inwards
under the M. pyriformis to be distributed in the M. sphincter
ani and the skin of the anus.
b. The Art. cutanea femoris posterior v. superior
(cf′) runs with the corresponding nerve and the M.
pyriformis, and over the M. semimembranosus to the skin of
the inner and hinder surfaces of the thigh.
c. The Rami musculares supply the M.
semimembranosus, the M. biceps, and the MM. extensores
auris; the branch to the M. rectus inferior major pierces
the muscle in company with the nerve, and is continued as:—
d. The Art. cutanea femoris media (cf″) to the
skin of the middle of the inner surface of the thigh. Several small
twigs pierce the M. rectus internus minor, reach the skin, and
communicate with this artery.
Fig. 156.
Arteries of the hinder extremity.
cc
Art. cutanea calcanei.
cf
Cutaneous branch of the femoral artery.
cf′
Art. cutanea fem. post. superior.
cf″
Art. cutanea femoris media.
cgl
Art cut. genu lateralis superior.
cgl′
Art. circumflexa genu lateralis inferior.
cgm
Art. circumflexa genu superior medialis.
cgm′
Art. circumflexa genu inferior medialis.
ci
M. coccygeo-iliacus.
g
M. gastrocnemius.
gl
M. glutaeus.
h
Art. haemorrhoidalis inferior.
i
Sciatic artery.
ml
Art. malleolaris lateralis.
mm
Art. malleolaris medialis.
p
Art. peronea.
p′
Muscular branch to the M. peroneus.
P
M. pyramidalis.
ra
M. rectus anterior.
ri″
M. rectus internus.
sm
M. semimembranosus.
su
Art. suralis.
t
Tibial artery.
to
Aperture in tibio-fibula.
tr
Art. tarsea.
ve
M. vastus externus.
B. The peroneal artery (Art. peronea), (Fig. 156
p) runs outwards
under cover of the tendon of the M. biceps femoris, and
accompanies the peroneal nerve downwards to give off:—
a. The Art. circumflexa genu lateralis superior, which
runs forwards on the outer side of the knee, gives a twig to the joint,
and is continued as:—
b. The Art. cutanea genu lateralis superior
(cgl) to the skin of the anterior and outer sides of the knee.
It anastomoses with branches of the Arteriae circumflexae genu
mediales to form a rich anastomosis (Rete articulare genu):
other branches pass upwards to inosculate with the Art. cutanea
femoris anterior (cf), and others downwards to anastomose
with the next artery.
c. The Art. circumflexa genu lateralis inferior
(cgl′) runs under the tendon of origin of the gastrocnemius to
the outer side of the knee, and terminates in the skin as the Art.
cutanea genu lateralis inferior. Some of the cutaneous twigs pass
upwards to anastomose with the Art. cut. genu lat. superior,
others downwards to anastomose with the AA. malleolares.
d. A muscular branch (p′) for the M. peroneus;
it is the real continuation of the peroneal artery, and runs behind the
outer tendon of origin of the gastrocnemius to be distributed in the
M. peroneus.
C. The tibial artery (Arteria tibialis), (Fig. 156
t), arises at the bifurcation of the sciatic, and runs inwards,
meeting the tibial nerve between the tendons of origin of the M.
gastrocnemius, and deep in the popliteal space under cover of the
calf-muscles. It then pierces the M. tibialis posticus, and
leaves this to perforate the tibio-fibula (see p. 50), appearing again
on the anterior surface as the anterior tibial artery. Before meeting
the tibial nerve this artery gives off the following branches:—
a. The Art. circumflexa genu superior medialis
(cgm), which winds round to the front of the knee-joint, and
gives off a cutaneous branch, the Art. cutanea genu medialis
superior, which is distributed in the skin of the inner side
of the knee and anastomoses above with the Art. cutanea femoris
media, below with the following branches (b, c, and
d).
b. The Art. circumflexa genu inferior medialis
(cgm′) supplies twigs to the knee-joint, and passes to the
skin of the knee and inner surface of the calf as the Art. cutanea
inferior medialis.
c. Muscular twigs to the M. gastrocnemius.
d. The Art. suralis (su); this accompanies the
N. suralis downwards along the calf-muscle, and is distributed
in the skin of the inner side of the heel.
e. While passing between the fibres of the M. tibialis
posticus, the tibial artery gives off muscular twigs; one larger
than the rest is known as the Ramus descendens.
Fig. 157.
Arteries of the dorsal surface of the foot.
c.c.
Art. cutanea calcanei.
c.c.i.
Art. cutanea cruris inferior.
Ft′
M. flexor tarsi.
h
Art. cutanea hallucis.
i1
Art. interossea dorsalis I.
i2
Art. interossea dorsalis II.
i3
Art. interossea dorsalis III.
i4
Art. interossea dorsalis IV.
ml
Art. malleolaris lateralis.
m.m.
Art. malleolaris medialis.
t.a.
Anterior tibial artery.
ta*
Bifurcation of the dorsalis pedis artery.
tr
Art. tarsea.
D. The anterior tibial artery (Arteria tibialis
antica), (Fig. 157 t.a.) is the continuation of the tibial
artery after piercing the tibio-fibula. It runs downwards on the
anterior surface of the leg, then between the two heads of the M.
tibialis anticus to the dorsum of the foot, where it is continued
as the Arteria dorsalis pedis. It supplies:—
a.Rami musculares to the M. peroneus, M.
extensor cruris, and to the M. flexor tarsi anterior.
b. The Art. cutanea cruris inferior (c.c.i.)
passes between the two heads of the M. tibialis anticus to the
skin of the anterior and outer sides of the leg.
c. The Art. cutanea calcanei (c.c.) is
given off at the ankle-joint; it runs outwards on the lower end
of the tibio-fibula, giving branches to the joint, then backwards
between the tibio-fibula
and the M. peroneus to be distributed to the skin of the
heel. Above it anastomoses with the A. circumflexa genu inf.
lateralis, and below with the malleolar arteries.
d. The Art. malleolaris lateralis (ml) arises a
little beyond the last artery; it runs outwards under the origin of the
M. flexor tarsi, gives branches to the joint and muscles, and
terminates in the skin of the outer border and dorsal surface of the
foot.
e. The Art. malleolaris medialis (m.m.) arises
at about the same level as the Art. malleolaris lat. from the
inner border of the anterior tibial artery. It supplies branches to
the joint, gives numerous branches to the skin, which anastomose with
the Art. suralis, and passes to the inner border of the foot,
where it ends by distributing branches to the M. plantaris, the
extensor aponeurosis, and, as the Art. cutanea plantaris, to the
skin of the sole of the foot.
E. The dorsal artery of the foot (Art. dorsalis
pedis), (Fig. 157 t.a.) runs under the M. flexor tarsi
posterior to the point ta*, where it is superficial; the
artery then bifurcates; the branches are:—
a. The Art. tarsea (tr) which arises from the
dorsal artery of the foot while under cover of the M. flexor tarsi
posterior; it passes to the M. extensor digiti V and to the
skin of the dorsum and outer border of the foot. One branch courses
along the outer border of the fifth toe to its tip; another passes
upwards to anastomose with the neighbouring vessels.
Fig. 158.
Arteries of the sole of the foot.
i
Art. interossea.
pf
Rami perforantes.
b. The inner branch, formed by the bifurcation of the dorsal
artery of the foot, at once divides to form:—
(1) The Art. cutanea hallucis (h) to the supplemental
great toe.
(2) The Art. interossea dorsalis I (i1),
which at once bifurcates to form two Rami digitales for the
first and second toes; these inosculate with the Art. cutanea
plantaris, and send twigs to the skin of the inner border of the
foot.
c. The outer branch formed by the bifurcation of
the dorsal artery divides to form the Arteriae interossei
dorsales II, III, and IV (i2, i3,
i4); they are distributed in a rich anastomosis to
the web.
d. The Arteria interossea (Fig. 158 i) arises
from the dorsal artery of the foot at the tarsus, and perforates
the membrane between the astragalus and calcaneum to reach the sole
of the foot. It forms a rich subcutaneous plexus on the calcar, and
anastomoses with the Rami perforantes (Fig. 158 pf),
which pass above the upper borders of the Musculi interossei to
reach the plantar surface, where they give off small Rami interossei
volares to anastomose with the AA. interosseae dorsales.
(The arrangement of this section has been
modified.)
The blood, distributed to the body by means of the arteries, is
returned to the heart by the veins, which conduct the blood directly
or indirectly to the auricles. The pulmonary vein opens directly into
the left ventricle, the three Venae cavae open into the Sinus
venosus.
A. Vein opening into the left auricle.
The pulmonary vein (Vena pulmonalis communis),
(Fig. 159 vp). The blood returning from each lung is gathered
into a vessel lying along the inner side of the root of the lung.
That of the right side is somewhat longer than the left; the two
vessels (Venae pulmonales dextra et sinistra) run above the
corresponding anterior caval veins to form a common trunk, the
pulmonary vein, which opens into the left auricle (see p. 215).
B. Veins opening into theSinus venosus.
Fig. 159.
Schema of the veins of Rana esculenta.
a
Subclavian vein.
ab
Anterior abdominal vein.
Ad
Right auricle.
As
Left auricle.
Ca
Anterior vena cava.
Cp
Posterior vena cava.
cm
Cutaneous vein.
d
Vena dorso-lumbalis.
D
Intestine.
f
Femoral vein.
i
Sciatic vein.
ic
Vena communicans iliaca.
je
External jugular vein formed by lingual and maxillary veins l and m.
ji
Internal jugular vein.
L
Hepatic veins.
N
Kidney.
o
Oviducal veins.
P
Hepatic portal vein.
raI
Renal portal vein.
raII
Secondary renal portal veins.
re
Renal veins.
s
Subscapular vein.
SC
Sinus venosus.
va
Innominate vein.
vc
Vena bulbi posterior (cardiac vein).
vp
Pulmonary veins.
The veins opening into the Sinus venosus are the three caval
veins; of these the two anterior open into the anterior angles of the
Sinus venosus, the posterior into the posterior angle.
1. The Anterior Caval Veins (Vena cava
superior), (Figs. 133V, 159 C a) are a pair of large
veins opening into the Sinus venosus and returning to it blood
from the fore-limbs and sides of the head. Each vein is formed by the
union of a small vein, the external jugular, with two large veins, the
innominate and the subclavian veins.
a. The external jugular vein (Vena jugularis
externa), (Fig. 159 je) is formed, at the outer border of
the hyoid bone, by the union of two veins:—
(1) The lingual vein (Vena lingualis) (Fig. 161l).
This originates at the tip of the tongue and passes in a very tortuous
course along the ventral surface of the hyoid; it receives numerous
branches from the tongue and hyoid muscles.
(2) The mandibular vein (Vena maxillaris inferior), (Fig. 161m) runs along the insertion of the M. submaxillaris, and
turns inwards at its hinder border to join the lingual vein.
b. The innominate vein (Vena anonyma),
(Fig. 160 A) is formed by the union of the internal jugular
and the subscapular veins. By tracing the innominate vein upwards
between the suspensorium and the shoulder-girdle, the internal jugular
vein will be seen to receive the vertebral vein at the outer border
of the M. levator scapulae. The left innominate vein receives
the Vena bulbi anterior from the Truncus arteriosus
(p. 222).
Fig. 160.
Distribution of the internal jugular vein and the
anterior portion of the cutaneous vein.
A
Innominate vein.
c.m.
Cutaneous vein.
f
Nasal vein.
h
Harderian gland.
H
Skin, reflected downwards.
J
Internal jugular vein.
L
Anterior lymph-heart.
l
M. levator scapulae.
O
M. obliquus internus.
o
Vena orbitalis anterior.
o′
Vena orbitalis posterior.
P
Lateral process of the prootic bone.
S
Subscapular vein.
S′
Shoulder-girdle.
T
Tympanic membrane.
V
Vertebral vein.
2
Transverse process of the second vertebra.
3
Transverse process of the third vertebra.
4
Transverse process of the fourth vertebra.
(1) The internal jugular vein (Vena jugularis),
(Fig. 160 J) can be traced from the border of the M. levator
scapulae upwards and forwards to the hinder part of the prootic
bone: it then passes forwards under the lateral process of the prootic,
in a groove on the anterior surface of the same bone, towards the
hinder angle of the orbit, where it receives the veins from the cranial
cavity (see vessels of brain, p. 165), and also a branch from the
orbit.
α. [The Vena orbitalis media (Virchow); it arises from the
anterior internal angle of the orbit, from the Harderian gland, the
nasal cavity, or from other veins on the anterior wall of the orbit.
The vessel lies close to the cranium, immediately underneath the
Arteria nasalis, and sinks under the M. rectus superior
to join the internal jugular vein. In its course it receives the
Vena bulbi superior (see eye), and near its termination
communicates with the Vena orbitalis posterior.]
β. The Vena vertebralis (Fig. 160 V) arises
posteriorly and runs forwards over the transverse processes of the
vertebrae, the Musculi intertransversarii, and the M. levat.
scapulae, to join the internal jugular vein. In its course it
receives branches (Venae spinales) from the vertebral canal
through the intervertebral foramina, and cutaneous branches which
accompany the corresponding arteries and nerves through the dorsal
lymphatic sac. The vein pulsates in consequence of its connection with
the anterior lymph-heart (Müller).
(2) The subscapular vein (Vena subscapularis),
(Fig. 160 S). This vein arises in the transverse abdominal
muscles and the muscles of the shoulder girdle; it unites with the
internal jugular vein under the shoulder-girdle.
Fig. 161.
The anterior caval vein and its branches.
a
Innominate vein.
c.m.
Cutaneous vein.
c.s.
Anterior cava vein.
i
Internal jugular vein.
i′
External jugular vein.
l
Lingual vein.
m
Mandibular vein.
s
Brachial vein.
s.c.
Subscapular vein.
c. The subclavian vein (Vena subclavia),
(Fig. 159) passes backwards from the anterior caval vein on the dorsal
surface of the coracoid bone and the clavicle, and then under cover
of the Portio sternalis of the M. pectoralis major, to
the internal border of the Portio abdominalis of the M.
pectoralis major, where it is formed by the union of the cutaneous
vein and the brachial vein.
(1) The cutaneous vein (Vena cutanea magna, Ecker;
Vena
musculo-cutanea, Gruby), (Figs. 160, 161, and 162c.m.).
This vein arises by small branches in the head; these are:—
α. The Vena nasalis (Virchow); it arises by an upper and a
lower branch from around the nostril, and courses backwards along the
superior maxillary bone to about the middle of the orbit, where it
joins the facial vein.
β. The Vena orbitalis anterior (Virchow), (Vena
ophthalmica anterior, Ecker), (Fig. 160o) commences at the
Harderian gland from a rich anastomosis, receives branches from the
floor and anterior wall of the orbit, and joins the facial vein with
the Vena nasalis.
γ. The Vena orbitalis posterior (Virchow), (Vena
ophthalmica posterior, Ecker), (Fig. 160o′) arises on the
posterior wall of the orbit on the M. pterygoideus; it passes
under the Processus zygomaticus to join the facial vein, and
in its course receives the Vena ophthalmica (see eye), and
communicates with the Vena orbitalis medialis and the internal
jugular vein.
δ. The Vena facialis (Fig. 160) is formed about the middle
of the orbit by the union of the Vena nasalis and the Vena
orbitalis anterior; it courses backwards towards the angle of the
jaw. On reaching the M. depressor maxillae, about 4 mm. in
front of the angle of the jaw, it passes on to the skin. It receives
in its course the Venae palpebrales (Fig. 162) and the Vena
orbitalis posterior.
Fig. 162.
Course of the cutaneous vein as seen from the side.
c.m.
Cutaneous vein.
d
M. depressor maxillae.
i
M. infraspinatus.
The musculo-cutaneous vein is the direct continuation of the Vena
facialis after this has left the upper jaw; it immediately receives
one or more twigs (Venae tympanicae), (Fig. 162) from the
tympanic membrane and the tympanic cavity.
The vein then courses backwards in the outer wall of the lateral
lymph-sac as far as the middle of the trunk, where it passes,
by means of the Septum abdominale, to the outer border
of the Portio
abdominalis of the M. pectoralis; here the vein curves
round to pass forwards between the fibres of this muscle to its inner
border where it terminates by joining the brachial vein. In the whole
of this lengthy course the vein receives numerous branches from the
neighbouring parts.
(2) The brachial vein (Vena brachialis) is formed in
the Plica cubiti by the union of two veins.
α. The radial vein (Vena radialis) arises on the
dorsum of the hand from a venous arch, the distal convexity of which
receives the Venae digitales dorsales: the vein courses
superficially along the outer side of the forearm to the elbow.
β. The ulnar vein (Vena ulnaris) arises from the veins
in the palm of the hand, and courses towards the elbow, lying deeply
between the muscles of the inner and outer surfaces of the forearm. In
the elbow the vein becomes superficial near the tendon of the M.
sterno-cleidoradialis, and joins the radial vein to form the
brachial vein.
The cutaneous veins of the fore-limb follow courses corresponding
with those of the arteries.
2. The Posterior Caval Vein (Vena cava
inferior), (Fig. 159Cp, 163 v.c.i.). The posterior caval vein is
a median vein which, commencing between the kidneys, runs forwards to
open into the posterior end of the Sinus venosus. It receives
the hepatic, renal, and ovarian or spermatic veins.
Fig. 163.
Veins in the region of the kidney.
a
Renal portal vein.
a′
Dorso-lumbar veins.
abd
Anterior abdominal vein.
d
Intestine.
f
Femoral vein.
i
Sciatic vein.
N
Kidney.
o
Right ovary, drawn to the left.
o′
Oviduct.
ov
Oviducal veins.
p
Mesenteric veins.
r
Renal veins.
V
Bladder.
v.c.i.
Posterior vena cava.
Vv
Vesical veins.
a. The hepatic veins (Venae hepaticae), (Fig. 164v.h.) are two in number, one from either side of the liver; they
open into the posterior caval vein near the Sinus venosus.
b. The renal veins (Venae renales or Venae
revehentes), (Fig. 163 r) are four or five small vessels on
each side; they pass from the inner border of the kidney inwards and
forwards, to form, by their union, the posterior caval vein. The most
anterior receive branches from the fat-bodies (see kidney).
c. The spermatic or ovarian veins are four or
five in number on each side; they open into the posterior caval vein
between the renal veins.
3. The Portal Systems.
[There are, in the frog, two portal systems; the renal and the
hepatic. Each of these receives vessels which are derived, directly or
indirectly, from the veins of the hinder extremity.
The femoral vein on entering the pelvis divides to form two
branches; an iliac vein placed dorsally, and a pelvic vein placed
ventrally; the two pelvic veins converge to the middle line of ventral
wall of the abdomen, where they unite to form the anterior abdominal
vein.]
a. The renal portal vein (Vena renalis advehens
princeps), (Fig. 163 a). This vein is formed by the union
of the sciatic and the iliac veins; it courses forwards to the outer
border of the kidney, and is distributed, by numerous branches, to
that organ, chiefly on its dorsal surface. It receives the following
veins:—
(1) The iliac vein (Vena iliaca externa); this is the
dorsal branch formed by the bifurcation of the femoral vein.
(2) The sciatic vein (Vena ischiadica), (Figs. 163
and 165i) arises at the popliteal space, courses upwards in
company with the sciatic nerve between the M. semitendinosus
and the M. biceps, then passes, still with the nerve, between
the M. vastus externus and the M. pyramidalis into the
pelvis. It continues forwards to join the iliac vein. At the root of
the thigh this vein communicates with the femoral vein by the Ramus
communicans iliacus.
(3) The dorso-lumbar vein (Vena dorso-lumbalis),
(Fig. 163 a′) is a vein (or more usually several) arising by
twigs in the dorsal and outer walls of the abdomen; it joins the renal
portal vein opposite the kidney.
(4) The oviducal veins (Fig. 163 ov) are irregular
veins from the oviducts, which open either into the dorso-lumbar vein,
or into the renal portal vein.
b. The hepatic portal system.
The liver receives blood from two sources: (1) from the hind-limbs
by means of the anterior abdominal vein, and (2) from the alimentary
canal by the hepatic portal vein.
The anterior abdominal vein (Vena abdominalis),
(Figs. 159ab, 164Va) is formed, a little in front of
the symphysis pubis, by the union of the two pelvic veins. It courses
forwards along the middle line of the ventral body-wall until opposite
the liver, where it ascends and divides into three branches, of which
two enter the right and left lobes of the liver respectively. The
third, the Ramus descendens, joins the hepatic portal vein. The
anterior abdominal vein receives the following veins:—
α. The vesical vein (Vena vesicalis), (Fig. 163Vv); a
median vein arising in the groove between the lobes of the bladder from
lateral branches, which extend outwards on the bladder. This vein communicates above with other
vesical twigs which open into the haemorrhoidal vein.
β. Parietal veins, which join the anterior abdominal vein in its
course along the ventral body-wall.
γ. A cardiac vein (Vena cardiaca), (Figs. 142, 159vc,
164 c), which joins the anterior abdominal vein just before its
division (see p. 222).
Fig. 164.
Veins of the liver.
AA
Auricles.
aa
Right and left branches of anterior abdominal vein.
b
Ramus descendens.
c
Vena bulbi (Vena cardiaca).
D
Intestine.
G
Gall-bladder.
L.l.
Left lobe of liver.
L.r.
Right lobe of liver.
P
Hepatic portal vein.
P′
Intestinal veins.
P″
Gastric veins.
S
Sinus venosus.
V
Ventricle.
Va
Anterior abdominal vein.
V.c.i.
Posterior vena cava.
v.h.
Hepatic veins.
The hepatic portal vein (Vena portarum), (Figs. 159,
164 P) is formed by the union of the gastric, intestinal,
splenic, and one of the haemorrhoidal veins. The large vein so
constituted passes forwards towards the liver, receives the Ramus
descendens from the anterior abdominal vein, and then passes into
the left lobe of the liver. Its branches are the following:—
(1) The gastric veins. The stomach has three veins:—
α. [The Vena coronaria ventriculi, which receives blood
from the hinder end of the oesophagus and anterior portion of the
stomach.
β and γ. Two other veins which form an Arcus coronarius on
the concave surface of the stomach; the hinder receiving in addition
the small Venae pancreaticae and the Vena duodenalis;
the trunk so formed receives the Vena coronaria ventriculi
(Hoffmann).
(2) The intestinal veins; the veins of that portion of the
alimentary canal between the middle of the duodenum and the anterior
end of the large intestine open into a common vein which joins the
hepatic portal vein.
(3) The splenic vein joins either the hepatic portal vein or
one of the intestinal veins.
(4) The haemorrhoidal veins are three in number; the anterior
opens into the splenic vein, the remaining two into the portal veins
through the agency of the intestinal veins.]
4.The Veins of the Hinder Extremity.
The hinder extremity has two venous trunks, the sciatic vein and the
femoral vein.
Fig. 165.
Veins of the hinder extremity, half schematic.
c.i.
Vena communicans iliaca.
f
Femoral vein.
i
Sciatic vein.
i′
Vena cutanea cruris medialis.
r.a.
M. rectus anterior.
s.m.
M. semimembranosus.
v.e.
M. vastus externus.
a. The femoral vein (Vena femoralis), (Fig. 165
f) is the larger venous trunk of the hinder extremity. It arises
in the popliteal space as a direct continuation of the posterior tibial
vein, courses upwards in company with the sciatic artery and nerve,
then leaves these to wind forwards and outwards, and appears between
the origins of the M. vastus externus and of the M. rectus
anterior. The vein
here gives off the Ramus communicans iliacus to the sciatic
vein, and turns forwards and downwards around the M. glutaeus
maximus to reach the floor of the pelvis, near the femoral artery.
The vein then bifurcates to form the pelvic and iliac veins.
(1) The Ramus communicans iliacus (Fig. 165 c.i.)
forms a communication with the sciatic at the base of the thigh.
(2) The posterior tibial vein (Vena tibialis postica), of
which the femoral is a continuation, arises on the dorsal surface of
the toes and foot. It runs superficially on the M. extensor longus
digiti primi over the ankle-joint, courses upwards and winds
round the outer surface of the tibio-fibula to the flexor surface. It
receives, in its course, muscular branches, and at the knee a large
cutaneous branch.
b. The sciatic vein: this vein has already been
described (see p. 247), but the vein from which it arises requires
description.
The anterior tibial vein (Vena tibialis antica)
arises on the dorsum of the foot by twigs from the toes; it courses
under the M. extensor longus digiti primi, then upwards on the
anterior surface of the leg, and enters the canal in the tibio-fibula
to appear on its hinder surface. The vein then receives twigs from the M. peroneus,
the M. tibialis posticus, the M. gastrocnemius, and a
large cutaneous branch.
α. The Vena cutanea cruris medialis (Fig. 165 i′)
receives branches from both above and below, and enters the popliteal
space to join the anterior tibial vein.
β. The anastomosis on the dorsum of the foot, from which the
anterior tibial vein arises, receives perforating twigs from the
plantar surface.
PART II. THE LYMPHATIC SYSTEM.
(The arrangement of this section has been
considerably altered.)
[The lymphatic system of the frog may, for descriptive purposes, be
advantageously treated of in four parts:
1. The subcutaneous lymph-sacs.
2. The lymph-hearts.
3. The lymph-spaces of the body, and those lying between the
various organs.
4. The lymph-vessels of the separate organs.
The first two parts will be described in this section; the remainder
with the organs or parts of the body with which they are more
intimately associated. The spleen will be described with the abdominal
viscera.
1. The Subcutaneous Lymph-Sacs.
A number of large spaces exist between the skin and the muscles,
in which there is no direct attachment between these parts. These
spaces are separated from each other by thin connective-tissue septa,
stretched between the muscles and the skin, and by attachments of the
skin to the underlying structures.
Joh. Müller first demonstrated that these spaces were connected with
the lymphatic system, and that the contained fluid was lymph. Although
this fact was contradicted by Meyer it received confirmation from
Stannius, Leydig, and especially from Recklinghausen, who showed that
the fluid of the lymph-sacs was carried away by the lymphatics, and
that later it entered the blood-stream.
A. The Lymph-sacs of the Head and Trunk.
Fig. 166.
Transverse section of a septum with the attached skin, its contained
sinus injected with blue injection mass.
H
Skin.
s
Septum.
S
Sinus contained in the septum.
a. The septa. The connective-tissue
septa themselves contain sinuses which occupy the space between
their two surfaces (Fig. 166) these septal sinuses receive the
contents of the cutaneous lymph-vessels and forward their contents
into lymph-vessels situated in the septa. Such a sinus is shown in
transverse section in Fig. 166 which is a section of the ventral
septum. The same sinus, in plan, is seen in Fig. 167.
Fig. 167.
The sinus abdominalis lateralis (Ecker) injected
with blue mass.
H
Skin with its lymph-vessels.
S
Sinus of the septum with lymph-vessels opening into it.
s
The septum cut parallel with the skin.
(1) The dorsal septum (Septum dorsale), (Figs. 169
and 171d) of each side commences at the tympanic membrane;
it is then attached to the M. depressor maxillae, M.
infraspinatus, and M. longissimus dorsi; and continued
backwards over the M. obliquus abdominis externus to the
anterior end of the M. glutaeus, whence it extends along the
iliac bone, where it is connected with the posterior lymph-heart and
the M. pyriformis, to the tip of the urostyle. At the tip of
the M. glutaeus it is joined by the iliac septum. The posterior
part of the septum is horizontal, and forms the roof of the iliac
lymph-sac.
(2) The ventral septum (Septum abdominale),
(Figs. 169, 170, and 171a), commencing at the Symphysis
pubis, runs forwards and outwards, on either side, along the
outer border of the M. rectus abdominis to the Portio
abdominalis of the M. pectoralis (p‴), where it is
attached, at a right angle, to the pectoral septum; it then extends
forwards, after attachment to the axillary septum, to the outer angles of the maxillary
septum. At the root of the anterior extremity it divides to enclose the
root of the limb, and so form the axillary septum.
(3) The pectoral septum (Septum pectorale), (Figs. 170
and 171p) is attached to the superficial surface of the
M. pectoralis (Portio sternalis, anterior and
posterior); it runs transversely across the body, and is
attached at its outer end to the ventral and to the maxillary septa.
The septum passes obliquely backwards and downwards to be attached
to the skin, and so forms a very acute angle with the M. cutaneus
pectoris (cp): a vertical band of connective-tissue, broad
behind, narrow in front, extends in the middle line from the septum
to the body wall; from it a certain amount of loose connective-tissue
extends in all directions, and forms open lymph-spaces between the
MM. cutanei pectorales and the vertical septum.
Fig. 168.
Sinus thoracicus transversus (Ecker).
cp
M. cutaneus pectoralis.
H
Skin reflected forwards.
s
Sinus with its afferent vessels.
(4) The perineal septum (Septum perineale), (Fig. 170pe). This median septum extends from the attachment of the
dorsal septum to the tip of the urostyle, backwards to the symphysis
pubis, where it joins the ventral septa. In its attachment it follows
the middle line of the perineum.
(5) The maxillary septum (Septum maxillare),
(Figs. 170, 171m) is attached by either extremity to the dorsal
septum, near the tympanic membrane, is continued downwards to unite
with the anterior end of the ventral septum, and then runs across the
anterior pectoral region, forming a curve with the convexity forwards.
It has inserted into it fibres of the M. submaxillaris. The
septum is formed of very loose tissue, and frequently contains deposits
of fat; it encloses a well-marked septal sinus, the Sinus thoracicus
transversus (Ecker).
(6) The iliac septum (Figs. 169, 17215, 173S′) is a
septum extending from the dorsal septum to the inguinal septum. It is
attached to the dorsal septum opposite the anterior end of the M.
glutaeus, and extends outwards and downwards to the inguinal septum. In it the M.
cutaneus iliacus passes from the trunk to the skin.
(7) The inguinal septum (Lamina inguinalis, Ecker),
(Figs. 169 171), the dotted line near 15, Fig. 172, separates the
belly from the thigh; on the ventral surface it is attached to the
groove which forms the
boundary between the belly and thigh; on the dorsal surface it is more
posterior, and is attached to the dorsal surface of the muscles of the
thigh at some little distance from the trunk. It completely surrounds
the root of the hinder limb. It has attached to it the ventral, dorsal,
and iliac septa, together with the septa of the thigh.
The lymph-sacs of Rana esculenta, seen from the dorsal
surface.
1
Dorsal lymph-sac.
3
Lateral lymph-sac.
7
Brachio-radial lymph-sac.
9
Femoral lymph-sac.
10
Suprafemoral lymph-sac.
11
Interfemoral lymph-sac.
12
Crural lymph-sac.
13
Dorsal lymph-sac of the foot.
14
Plantar lymph-sac of the foot.
15
Iliac lymph-sac.
a
Ventral septum.
d
Dorsal septum.
f′
Superior femoral septum.
f‴
Intermediate femoral septum.
i
Inguinal septum.
s
Posterior brachial septum.
s‴
Anterior brachio-radial septum.
V
Vocal sac.
b. The lymph-sacs.
(1) The dorsal lymph-sac (Saccus cranio-dorsalis), (Figs. 169 and
1711). This is a large lymph-sac, extending from the tip of the
snout to the tip of the urostyle; it is bounded in front by the
attachment of the skin to the premaxillary bones; the line of
attachment is continued, on either side, along the inner border of
the external nares, then forms a pouch towards the jaw and in front
of the eye, and runs backwards along the upper border of the orbit,
where it is attached to the upper eyelid, to the inner border of
the tympanic membrane. In this course the skin is firmly attached
to the underlying parts. The lateral boundary of the lymph-sac,
behind this point, is formed by the dorsal septum, which separates
it from the lateral lymph-sac.
Fig. 170.
Lymph-sacs of Rana esculenta, seen from the ventral surface.
2
Ventral lymph-sac.
3
Lateral lymph-sac.
4
Submaxillary lymph-sac.
5
Thoracic lymph-sac.
6
Brachio-ulnar lymph-sac.
8
Anterior brachial lymph-sac.
9
Femoral lymph-sac.
11
Interfemoral lymph-sac.
12
Crural lymph-sac.
13
Dorsal lymph-sac of the foot.
14
Plantar lymph-sac of the foot.
a
Ventral septum.
a′
Anterior division of ventral septum.
a″
Posterior division of ventral septum.
cf
Intermediate femoral septum.
cp
M. cutaneus pectoris.
f″
Inferior femoral septum.
i
Inguinal septum.
i′
Attachment of inguinal septum to skin.
m
Maxillary septum.
m′
Attachment of maxillary septum to skin.
p
Pectoral septum.
p‴
Port. abdom. of the M. pectoralis.
pe
Perineal septum.
r
M. rectus abdominis.
ri
″ M. rectus internus minor.
s″
Anterior brachio-ulnar septum.
s‴
Anterior brachial-radio septum.
sm
Musc. submaxillaris.
Fig. 171.
The lymph-sacs of Rana esculenta,
seen from the side.
1 Dorsal lymph-sac.
2 Ventral lymph-sac.
3 Lateral lymph-sac.
4 Submaxillary lymph-sac.
5 Pectoral lymph-sac.
9 Femoral lymph-sac.
10 Suprafemoral lymph-sac.
12 Crural lymph-sac.
15 Iliac lymph-sac.
a Ventral septum.
d Dorsal septum.
i Inguinal septum.
m Maxillary septum.
m′ Attachment of M. submaxillaris to the skin.
p Pectoral septum.
sm M. submaxillaris.
v Vocal sac.
(2) The ventral lymph-sac (Saccus abdominalis),
(Figs. 170, 1712) is triangular in form, with the base forwards at
the breast, and the apex behind at the pelvic symphysis; it occupies
the space between the skin below and the belly muscles and part of the
M. pectoralis above. It is bounded anteriorly by the pectoral
septum (p) and laterally by the ventral septa (a).
(3) The lateral lymph-sac (Saccus lateralis),
(Figs. 169, 170, and 1713) exists on either
side; below, the sac is bounded by the ventral septum (a), above
by the dorsal septum (d), anteriorly by the maxillary septum
(m), and posteriorly by the inguinal septum (i) and the
wall of the iliac lymph-sac.
(4) The submaxillary lymph-sac (Saccus submaxillaris),
(Figs. 170 and 171 4) is a space between the
M. submaxillaris and the skin; the sac is bounded behind by the
maxillary septum, which separates it from the pectoral lymph-sac, and
more laterally from the lateral lymph-sac. In front and at the sides
the skin is firmly attached to the margin of the mandible.
(5) The pectoral lymph-sac (Saccus thoracicus),
(Figs. 170 and 171 5) lies between the
submaxillary and ventral lymph-sacs. The sac is bounded behind by the pectoral septum
(p), and in front by the maxillary septum (m).
(6) The iliac lymph-sac (Saccus iliacus), (Figs. 171
and 172 15, 173) does not really belong to
the subcutaneous lymph-sacs, as it does not lie directly under the skin
except by a very narrow border. It is bounded in front by the iliac
septum, above by the dorsal septum, and posteriorly by the inguinal
septum. By these boundaries a space is enclosed, which lies under
the dorsal septum and dorsal sac, and at the same time partly under
the lateral sac. In this sac the M. glutaeus, the anterior
ends of the M. vastus externus, M. rectus anterior, and
M. cutaneus iliacus, lie free together with the hindmost part of the M. obliquus
abdominis externus, and the hinder portion of the posterior
lymph-heart. Anteriorly the floor is depressed between the M.
obliquus abdominis and the M. glutaeus, the depression
leading to a canal, which communicates with the abdominal cavity.
Fig. 172.
Transverse section through the trunk in the
region of the iliac lymph-sac.
c
Urostyle.
c′
Skin.
o
Muscles of abdominal wall.
1
Dorsal lymph-sac.
3
Lateral lymph-sac.
15
Iliac lymph-sac.
Fig. 173.
Dissection to show the iliac
lymph-sac.
g
M. glutaeus.
i.c.
M. ilio-coccygeus.
m.c.
M. cutaneus iliacus.
o
M. obliq. abdom. externus.
r
M. rectus.
S
Dorsal septum.
S′
Iliac septum.
S‴
Portion of dorsal septum, which forms the roof of the iliac lymph-sac.
v
M. vastus externus.
*
Aperture, by which the iliac lymph-sac communicates with the abdominal cavity.
B. The Lymph-sacs of the Anterior Extremity.
a. The septa.
(1) The axillary septum (Septum axillare), (Figs. 170a′, a″, 171) is practically a
portion of the ventral septum, which divides at the root of the arm to
enclose it. The dorsal and ventral portions of this circular septum
have received special names.
α. The dorsal axillary septum (Septum axillare dorsale)
crosses the M. triceps and joins the pectoral septum.
β. The ventral axillary septum (Septum axillare dorsale)
passes through the axilla and joins the pectoral septum.
The circular axillary septum has attached to it the following:—
(2) The posterior brachial septum (Septum brachiale
posticum) (Fig. 169s); it is
attached along the middle line of the extensor surface of the arm (long
head of the M. triceps) to the elbow and to the forearm (MM.
anconaei), then passes obliquely over the volar surface of the hand
to the fourth finger.
(3) The anterior brachio-ulnar septum (Septum brachiale
anticum ulnare), (Fig. 170s″)
commences at the same point as the foregoing, passes obliquely over the
outer head of the M. triceps, and is continued over the M.
flexor antibrachii lateralis, M. supinator longus, and M.
extensor digitorum communis, to the dorsal surface of the fourth
finger.
(4) The anterior brachio-radial septum (Septum brachiale
anticum radiale), (Fig. 170s‴)
passes from the outer angle of the wall of the pectoral lymph-sac,
over the inner head of the M. triceps and M. flexor carpi
radialis to the thumb.
b. The lymph-sacs are enclosed by these
three septa; they are four in number:—
(1) The brachio-ulnar lymph-sac (Saccus brachialis
ulnaris), (Fig. 1706) is situated between the first and second septa
along the extensor and ulnar surfaces.
(2) The brachio-radial lymph-sac (Saccus brachialis
radialis), (Fig. 1697) is placed along the extensor and radial
surfaces.
(3) The anterior brachial lymph-sac (Saccus
brachialis anticus), (Fig. 1708) lies on the flexor surface between the
second and third septa; it is a long cavity and interrupted
by connective-tissue bands, in which the tendon of the M.
sterno-radialis and the nerve and vessels are situated.
(4) The axillary lymph-sac (Saccus axillaris)
corresponds to the iliac lymph-sac; it is bounded by the divisions of
the ventral septum.
In the hand no large lymph-space exists; the skin is attached by
numerous bands to the underlying structures.
C. The Lymph-sacs of the Hinder Extremity.
a. The septa.
Fig. 174.
Plan of attachments of the inferior femoral,
inguinal, and perineal septa.
(1) The superior femoral septum (Septum femorale
superius), (Figs. 169 and
175 f′) is attached above to the inguinal
septum near the posterior lymph-heart; and is continued, from this
point, over the M. vastus externus and along the M.
triceps to the knee.
(2) The inferior femoral septum (Septum femorale
inferius), (Figs. 170 and
175 f″) runs from the inguinal septum near
the point of insertion of the M. rectus abdominis, along the
M. rectus internus minor to the knee.
(3) The intermediate femoral septum (Septum femorale
intermedium), (Figs. 169 and 175f‴) passes from near the posterior
lymph-heart over the M. semimembranosus and the M. rectus
internus minor to join the inferior femoral septum.
(4) The tibio-femoral septum (Septum femoro-crurale)
is a circular band, separating the lymph-sacs of the thigh from the leg
sac.
(5) The septa of the foot. At the ankle joint the skin is
closely attached all round to the underlying parts. Along the outer
border of the foot a septum is attached to the skin externally, and
to the underlying parts, especially the M. abductor longus digiti
primi, internally. A similar but weaker band is attached along
the outer border of the foot, especially to the M. adductor digiti
quinti.
b. The lymph-sacs.
(1) The femoral lymph-sac (Saccus femoralis),
(Figs. 169, 170, 171, 175 9) covers
the lower and outer surfaces of the thigh; it is bounded by the
superior femoral and inferior femoral septa, and in front by the
inguinal septum.
Fig. 175.
Transverse section of the thigh.
b
M. biceps.
f′
Superior femoral septum.
f″
Inferior femoral septum.
f‴
Intermediate femoral septum.
H
Skin.
ri′
M. rectus internus major.
ri‴
M. rectus internus minor.
s
M. Sartorius.
sm
M. semimembranosus.
ve
M. vastus externus.
9
Femoral lymph-sac.
10
Suprafemoral lymph-sac.
11
Interfemoral lymph-sac.
(2) The suprafemoral lymph-sac (Saccus
suprafemoralis), (Figs. 169, 171, 175 10) lies on
the upper surface of the thigh, between the superior and intermediate
femoral septa; above it is bounded by the inguinal septum.
(3) The interfemoral lymph-sac (Saccus
interfemoralis), (Figs. 169, 170, 175 11) is a
narrow sac on the inner surface of the thigh, between the inferior
femoral septum and the intermediate femoral septum. It covers the
M. rectus internus minor, and is interrupted by numerous bands
of tissue which pass from the surface of the muscle to the skin. It
is, therefore, not a simple sac, but a very wide-meshed trabecular
structure of connective-tissue. The sac is triangular in shape, with
the base directed forwards at the inguinal septum.
(4) The lymph-sac of the leg is a simple sac enclosing
the whole leg, bounded above by the tibio-femoral septum, and below by
the attachment of the skin to the ankle.
(5) The lymph-sacs of the foot. On the dorsum of the
foot the skin is free, and there is consequently a lymph-sac. On the
plantar surface the skin is attached by numerous connective-tissue
bands and thread-like tendons, particularly to the flexor tendons.
The skin of the
dorsal and plantar surfaces meet on the web and enclose a very rich
anastomosis of lymph-capillaries.
2. The Lymph-Hearts.
The frog has two pairs of lymph-hearts, one pair anterior, the other
posterior.
Fig. 176.
The anterior lymph-hearts.
L
The left anterior lymph-heart.
l.s.
M. levator scapulae.
N
Brachial nerve.
t.s.
M. transverso-scapularis maior.
1–4
Vertebrae numbered from before backwards.
A. The anterior lymph-hearts (Fig. 176). These organs
lie, one on each side, behind the broad transverse processes
of the third vertebra (Müller, Panizza, Priestley), in a deep
triangular space formed by the separation of the fibres of the M.
intertransversarius, between the transverse processes of the third
and fourth vertebrae. Each heart is a rounded sac, slightly elongated
anteriorly where it is connected with the subscapular vein. [The hearts
receive lymph from the anterior part of the body and the surrounding
parts, and empty their contents into the vertebral vein. Each of these
hearts is supplied by a branch from the second spinal nerve (Volkmann,
Eckhard, Schiff, Priestley).]
Fig. 177.
The posterior lymph-hearts.
gl
M. glutaeus.
ic
M. ilio-coccygeus.
L
Posterior lymph-hearts.
p
M. pyriformis.
r
M. rectus.
ve
M. vastus externus.
B. The posterior lymph-hearts (Fig. 177) are situated
on either side of the urostyle in the triangular spaces (Müller,
Panizza, Priestley), bounded externally and above by the M.
glutaeus, internally
and above by the M. coccygeo-iliacus, below and externally
by the origin of the M. vastus externus, and below by the
M. pyramidalis. Each posterior heart is about two lines long
and one broad, with its long axis placed antero-posteriorly; the
outer surface is uneven and appears to be unequally dilated. The
lymph-heart is closely attached to the surrounding parts, especially
to the fascia covering the M. ilii-coccygea, and posteriorly
to the M. levator ani and the M. pyramidalis. [The
posterior lymph-hearts receive lymph from the parts surrounding them,
and from the hinder extremities, and forward it into the V. iliaca
communicans.
The posterior lymph-hearts are each supplied by a branch from the
corresponding coccygeal nerve (Waldeyer) by its dorsal branch. The
lymph-hearts are also in close connection with the sympathetic system
(Waldeyer).]
PART III. THE BLOOD, LYMPH, AND HISTOLOGY OF THE VESSELS.
[The parts described in this section will be considered very
briefly, and only from an anatomical point of view.
The blood varies in colour, according as it is obtained from an
artery or from a vein; from an artery it has a bright red or scarlet
colour; from a vein a darker shade: in the pulmonary vessels these
colours are reversed. The blood consists of a fluid plasma which
contains red and white corpuscles: the whole forming a slightly
alkaline, opaque, and somewhat sticky fluid.
a. The plasma or liquor sanguinis is a
transparent, clear, slightly yellow fluid, faintly alkaline in
reaction.
b. The corpuscles are of two kinds, colourless and
coloured.
(1) The colourless or white corpuscles are subspherical masses of
protoplasm, endowed with the power of spontaneous motion. They are much
fewer than the red corpuscles, though the proportion of white to red
varies considerably. Three chief varieties of colourless corpuscles can
be distinguished, all of which are true cell forms, and behave like
other cells with staining or other reagents. They have no cell-wall,
but are simply nucleated masses of protoplasm. These corpuscles possess
the power of passing through the walls of the blood-vessels, and are
then known as migratory cells; such migratory cells can be found in
nearly all tissues, but more especially in the connective-tissues.
α. Ordinary large colourless corpuscles are large transparent masses
of protoplasm containing one or two nuclei, rarely three or more. The
cell contains few granules, and usually has one or more vacuoles or
clear spaces containing fluid.
β. Granular corpuscles are less numerous than the foregoing, but
larger, and are distinguished by the numerous large dark granules which
they contain. The processes such a corpuscle sends out are hyaline.
γ. Smaller corpuscles also occur varying much in form: they may
consist of a nucleus with a very small amount of hyaline or granular
protoplasm, or of several nuclei with an extremely small amount of
protoplasm.
(2) The coloured corpuscles are much more numerous
than the colourless corpuscles; each is a bi-concave, oval disc,
about 0.0255 mm. in length, and 0.017 mm in breadth (Gulliver)66
(R. temporaria, 0.0235 and 0.0145 mm. respectively). Each
corpuscle possesses an oval nucleus (Hewson)67, which projects into
either concave surface of the whole corpuscle. These corpuscles do
not possess the power of spontaneous movement; and have no cell-wall.
The corpuscles are of a reddish-yellow colour, and give the blood its
characteristic hue. The colouring matter is haemoglobin, and when
separated it crystallizes in prisms (Preyer). The corpuscles show a
well-marked intracellular and intranuclear network.]
B. [The Lymph and Chyle.
The lymph is that portion of the blood which has filtered
from the blood-vessels, through the tissues, into the lymphatics.
It is a clear, transparent fluid, containing colourless corpuscles,
which agree in all particulars with the colourless corpuscles of the
blood. During digestion the lymph from the alimentary canal contains
particles of fatty matter, and is then known as chyle.] The
colourless corpuscles of the lymph frequently contain portions of red
corpuscles or granules of pigment. Non-nucleated masses of protoplasm
and decolourised red corpuscles (slightly diminished in size) have
also been described as occurring frequently in the lymph (Fuchs68).]
C. [Histological Remarks on the Vascular System.
a. The heart has already been described
(pp. 216–222).
b. The blood-vessels present the same structure as
the corresponding vessels in higher animals. The arteries
and veins have each the three walls or layers usually
described—Tunica adventitia, Tunica media, and Tunica
intima. The only characteristic to be mentioned is that the
Tunica adventitia contains branched, pigmented corpuscles.
The Nervi vasorum, especially of the smaller arteries, are
arranged in two plexuses, one in the Tunica adventitia (His)69,
the second in the muscular coat (J. Arnold)70. The fibres of both
plexuses are non-medullated, and have the usual beaded appearance; they
communicate freely with each other. The capillaries present,
as a rule, the usual structure: such special arrangements of the
capillaries or peculiarities in structure as occur will be described
with the organs in which they are found.
c. The subcutaneous lymph-sacs are lined with a layer
of endothelium resembling the endocardium shown in Fig. 140; the
endothelial layer possesses stomata (see peritoneum), through which the
lymph-sacs communicate with the underlying lymphatics. The endothelium
is continued on to the vessels, nerves, etc., which course through the
sacs, and excludes these from the cavities. As a rule an artery, vein,
and nerve are enclosed in a common sheath.
d. The lymph-hearts are small saccular bodies
with thin transparent walls, which contain obscurely striated
muscle-fibres. The vessels communicating with the hearts appear to
possess valves (Müller).
The walls of the hearts are formed of three layers; an external,
compared by Waldeyer to an adventitia, a muscular layer, and
an endothelial lining. The muscular fibres form a close interlacing
mass, the fibres being small, branched (Leydig), and possessed of
many nuclei. Among the muscular fibres are pigmented corpuscles,
together with medullated and non-medullated nerve-fibres, but no
ganglion-cells (Volkmann, Waldeyer, Priestley). The adventitia
is a connective-tissue layer with many pigment cells (Leydig, Hyrtl,
Waldeyer).]
SECTION V. THE ALIMENTARY TRACT WITH ITS APPENDAGES, THE SPLEEN, AND THE PERITONEUM.
THE ALIMENTARY TRACT,
ETC.
LITERATURE.
THE MOUTH.
(Except the mucous membrane of the tongue, for
which see organ of taste.)
Ducrotay de Blainville, H. M., Ostéographie ou description
iconographique comparée du squelette et du système dentaire des cinq
classes d’animaux vertébrés. Paris, 1841.
Erdl, Ueber den Bau der Zähne bei den Wirbelthieren, etc.
München, 1841.
Fixen, C., De linguae raninae structura. Dorpat, 1857.
Heincke, F., Untersuchungen über die Zähne niederer
Wirbelthiere. Zeitsch. f. wiss. Zool. 1873. Vol. XXIII, p. 495.
Hertwig, O., Ueber das Zahnsystem der Amphibien, etc. Suppl.
to Vol. XI, Arch. f. mik. Anat. 1874.
Hoffmann, C. K., Bronn’s Thierbuch. Leipzig and Heidelberg,
1873–1878. Vol. VI, p. 379.
Holl, M., Zur Anatomie der Mundhöhle von Rana temporaria.
Wiener Acad. Sitzungsb. 1887. Vol. XCV, Pt. III, p. 47.
Hoyer, Ueber die Epithelzellen der Froschzunge, sowie über
den Bau der Cylinder- und Flimmerepithelien und ihr Verhältniss zum
Bindegewebe. Arch. f. Anat. u. Physiol. 1858, p. 163; also Deutsche
Klinik, 1857.
Langer, C., Ueber das Lymphgefässsystem des Frosches. Wiener
Acad. Sitzungsb. 1867. Vol. LV, Pt. I, pp. 614–621.
Leydig, Die Anuren Batrachier der deutschen Fauna. Bonn,
1877.
Owen, R., Odontography. London, 1840–1845, p. 187.
Reichel, P., Beiträge zur Morphologie der Mundhöhlendrüsen
der Wirbelthiere. Leipzig, 1882; also in Morph. Jahrb. 1882, Vol. VIII,
pp. 1–72.
Santi Sirena, Untersuchungen über den Bau und die Entwicklung
der Zähne bei den Amphibien und Reptilien. Verhandl. d. phys.-med.
Gesellsch. in Würzburg, 1872. Vol. II, new series, p. 125.
Schöbl, J., Ueber divertikelbildende Capillaren in der
Rachenschleimhaut nackter Amphibien. Sitzungsb. d. k. b. Gesellsch. d.
Wiss. in Prag. 1878, p. 25; also in Arch. f. mik. Anat. 1885, Vol. XXV,
p. 89.
Schultze, F. E., Das Drüsenepithel der schlauchförmigen
Drüsen des Dünn- und Dickdarms und die Becherzellen (of the
pharyngo-oral cavity). Centralbl. f. d. med. Wiss. 1866, p. 61.
Schultze, F. E., Epithel- und Drüsen-Zellen. Arch. f. mik.
Anat. 1867. Vol. III, p. 137.
Smith, W. J., Beitrag zur differentiellen Diagnose der Rana
fusca s. platyrrhinus und Rana arvalis s. oxyrrhinus auf Grund der an
den Gaumenzähnen nachweisbaren Unterschiede. Pflüger’s Arch. f. d. ges.
Physiol. 1883. Vol. XXXII, pp. 581–588.
Tomes, C. S., On the development of the teeth of the newt,
frog, slowworm, and green lizard. Phil. Trans. 1874, p. 285.
Török, Untersuchungen über die Entwickelung der Mundhöhle,
etc. Wiener Sitzungsb. 1866. Vol. LIV, Pt. I, p. 75.
Waller, A., Microscopic examination of the principal tissues
of the tongue, etc. Phil. Mag. 1846, pp. 273–290.
Waller, A., On the development of the mouth and tongue of the
frog. Phil. Mag. 1850. Vol. I, pp. 38–43.
Zeller, A., Die Abscheidung des indig.-schwefelsauren
Natrons in den Drüsen (Intermaxillary gland). Virchow’s Arch. 1878.
Vol. LXXIII, p. 257.
THE OESOPHAGUS AND STOMACH.
Biedermann, Untersuchungen über Magenepithel. Wiener Acad.
Sitzungsb. 1875. Vol. LXXI, Pt. III, p. 377.
Bischoff, Ueber den Bau der Magenschleimhaut. Arch. f. Anat.
u. Physiol. 1838, p. 503.
Bleyer, E., Magenepithel und Magendrüsen der Batrachier.
Dissert. Königsberg, 1874.
Braun, Zum Vorkommen von Flimmerepithel im Magen. Zool.
Anzeiger. 1880. No. 69, p. 568.
Brinton, in Cyclopaedia of Anat. and Physiol., edited by
R. B. Todd. 1859. Vol. I, p. 320.
Cobelli, Le gliandole acinose del cardia. Wiener Acad.
Sitzungsb. 1866. Vol. LIII, Pt. I, p. 251.
Ebstein, W., Beiträge zur Lehre vom Bau und den
physiologischen Funktionen der sogenannten Magenschleimdrüsen. Arch. f.
mik. Anat. 1870. Vol. VI, p. 515.
Ecker, A., Ueber die Drüsen der Magenschleimhaut. Zeitsch. f.
rat. Med. 1852, p. 243.
Foster, M., On some points in the epithelium of the frog’s
throat. Journ. of Anat. and Physiol. 1869. Vol. IV, p. 394.
Frerichs, On the Stomach, in Wagner’s Handwörterbuch d.
Physiol. 1848. Vol. II, p. 748.
Glinsky, A., Zur Kenntniss des Baues der Magenschleimhaut der
Wirbelthiere. Centralbl. f. d. med. Wiss. 1883, p. 225.
Gonjaew, K., Die Nerven des Nahrungsschlauches. Arch. f. mik.
Anat. 1875. Vol. XI, pp. 479–496.
Hebold, O., Ein Beitrag zur Lehre von der Sekretion und
Regeneration der Schleimzellen. Dissert. Bonn, 1879, pp. 21–27.
Heidenhain, R., Untersuchungen über den Bau der Labdrüsen.
Arch. f. mik. Anat. 1870. Vol. VI, p. 368.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreichs. Leipzig und Heidelberg. 1873–1878. Vol. VI,
pp. 408–412.
Just, A., Zur Histologie und Physiologie des Flimmerepithels.
Breslauer ärztliche Zeitsch. 1885. No. 18, pp. 205–206.
Klein, E., Darmkanal, in Stricker’s Gewebelehre, p. 388,
etc.
v. Kölliker, A., Mikroskopische Anatomie, 1854. Vol. II,
p. 147.
Langley, J. N., and Sewall, H., On the changes in
pepsin-forming glands during secretion. Journ. of Physiol. 1880.
Vol. II, pp. 261, 281.
Langley, J. N., On the histology and physiology of
pepsin-forming glands. Phil. Trans. 1881. Vol. CLXXII, Pt. III,
pp. 663–712.
Langley, J. N., On the structure of secretory cells and on
changes which take place in them during secretion. Internat. Monatschr.
f. Anat. u. Histol. Vol. I, pp. 69–76.
Leydig, Lehrbuch der Histologie. 1857.
Nussbaum, M., Ueber den Bau und die Thätigkeit der Drüsen.
Arch. f. mik. Anat. 1882, Vol. XXI, p. 296; 1882, Vol. XXVIII, p. 296;
1877, Vol. XIII, p. 721.
Partsch, C., Beiträge zur Kenntniss des Vorderdarmes einiger
Amphibien und Reptilien. Arch. f. mik. Anat. 1877. Vol. XIV, p. 179.
Regéczy, E. N., Ueber die Epithelzellen des Magens. Arch. f.
mik. Anat. 1880. Vol. XVIII, pp. 408–411.
Robinson, C., Ueber die Lymphgefässe der Abdominaleingeweide
des Frosches, etc. Froriep’s Notizen, 1846. No. 807, col. 225.
Rollett, Bemerkungen zur Kenntniss der Labdrüsen und der
Magenschleimhaut. Untersuch. in d. Institut f. Physiol. u. Histol. zu
Graz. 1871.
Schultze, F. E., Epithel- und Drüsenzellen. Arch. f. mik.
Anat. 1867. Vol. III, p. 174; abstract in Centralbl. f. med. Wiss.
1866, No. 4.
Schmidt, C., Ueber eingenthümliche aus dem Flimmerepithel
hervorgehende Gebilde. Arch. mik. Anat. 1881. Vol. XX, p. 123.
Sewall, H., A note on the processes concerned in the
secretion of the pepsin-forming glands of the frog. Studies in the
Biol. Laborat., Johns Hopkins Univers. Vol. II, pp. 131–134.
v. Swiecicki, H., Untersuchungen über die Bildung und
Ausscheidung des Pepsins bei den Batrachiern. Pflüger’s Arch. f. d.
ges. Physiol. 1876. Vol. XIII, p. 444.
Trinkler, N., Zur Kenntniss des feineren Baues der
Magenschleimhaut, insbesondere der Magendrüsen. Centralbl. f. med.
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mik. Anat. 1885. Vol. XXIV, p. 74.
Trütschel, Ueber die Endigung der Nerven in der Schleimhaut
des Magens. Centralbl. f. d. med. Wiss. 1870, p. 115.
Valatour, Recherches sur les glandes gastriques et sur les
tuniques musculaires du tube digestif dans les poissons ossieux et les
Batraciens. Annales de Sc. nat. 1861. Series IV. Vol. XVI, p. 219.
THE INTESTINE.
Arnstein, C., Ueber Becherzellen, etc. Virchow’s Arch. 1867.
Vol. XXXIX, p. 527.
Arnstein, C., and Gonjaew, K., Ueber die Nerven des
Verdauungskanals. Pflüger’s Arch. f. d. ges. Physiol. 1874. Vol. VIII,
pp. 614–615.
Auerbach, L., Fernere vorläufige Mittheilung über den
Nervenapparat des Darmes. Virchow’s Arch. 1864. Vol. XXX, p. 457.
Auerbach, L., Untersuchungen über Lymph- und Blutgefässe.
Virchow’s Arch. 1865. Vol. XXXIII, p. 340.
Auerbach, L., Organologische Studien.
Billroth, T., Ueber die Epithelzellen der Froschzunge; der
Bau, Cylinder- und Flimmerepithel und ihr Verhältniss zum Bindegewebe.
Arch. f. Anat. u. Physiol. 1858, p. 159.
Billroth, T., Einige Beobachtungen über das ausgedehnte
Vorkommen von Nervenanastomosen im Tractus intestinalis. Arch. f. Anat.
u. Physiol. 1858, p. 148.
Brettauer und Steinach, Untersuchungen über das
Cylinderepithelium. Wiener Akad. Sitzungsb. 1857. Vol. XXIII, p. 303.
Moleschott’s Zeitsch. 1857. Vol. III, p. 157.
Darsch, O., Beiträge zur Kenntniss des feineren Baues des
Dünndarms. Wiener Sitzungsb. 1880. Vol. LXXXII, Pt. III, p. 168.
Dönitz, Ueber die Schleimhaut des Darmcanals. Arch. f. Anat.
u. Physiol. 1864, p. 367.
Dönitz, Ueber Darmzotten. Arch. f. Anat. u. Physiol. 1866,
p. 757.
Eberth, C. J., Ueber den feineren Bau der Darmschleimhaut.
Würzb. naturw. Zeitschr. 1864. Vol. V, p. 23.
Eimer, T., Zur Fettresorption, etc. Virchow’s Arch. 1867.
Vol. XXXVIII, p. 428.
Eimer, T., Zur Geschichte der Becherzellen. Dissert. 1867.
Eimer, T., Die Wege des Fettes in der Darmschleimhaut bei
seiner Resorption. Virchow’s Arch. 1869. Vol. XLVIII, p. 119.
Eimer, T., Zur Becherfrage. Virchow’s Arch. 1867. Vol. XL,
p. 282.
Erdmann, Die Resorptionswege in der Schleimhaut des
Dünndarms. Dissert. Dorpat, 1867.
Fries, E., Ueber die Fettresorption und die Entstehung der
Becherzellen. Virchow’s Arch. 1867. Vol. XL, p. 519.
Gerlach, L., Ueber den Auerbachschen Plexus mysentericus.
Arbeiten aus d. physiol. Anstalt. Leipzig. 1872, pp. 102–112.
Gonjaew, K., Die Nerven des Nahrungsschlauches. Arch. f. mik.
Anat. 1875. Vol. XI, pp. 479–496.
Gruby and Delafond, Résultats des recherches faites
sur l’anatomie et les fonctions des villosités intestinales, etc.
Compt. rend. 1843. Vol. XVI, p. 1194.
Grugenhagen, A., Ueber Fettresorption und Darmepithel. Arch.
f. mik. Anat. 1887. Vol. XXIX, p. 139.
Heidenhain, R., Die Absorptionswege des Fettes. Moleschott’s
Untersuchungen. 1858. Vol. IV, p. 251.
Henle, J., Symbolae ad anatomiam villorum intestinalium impr.
eorum epithelii et vasorum lacteorum. Berolini, 1837.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreichs. Leipzig und Heidelberg, 1873–1878. Vol. VI,
pp. 412–424.
Klein, E., Der Darmkanal in Stricker’s Gewebelehre, Article
XVI.
Klein, E., Contributions to the anatomy of Auerbach’s Plexus
in the intestine of the frog and toad. Quart. Journ. Micros. Sci. 1873.
Vol. XIII, p. 377.
Klein, E., and Verson, E., Der Darmcanal, in
Stricker’s Gewebelehre, 1871, p. 355.
Klein, E., Der neue Nervenapparat v. Thanhoffer’s. Centralbl.
f. d. med. Wiss. 1883, p. 82.
v. Kölliker, A., Nachweis eines besonderen Baues der
Cylinderzellen des Dünndarms. Verhandl. d. phys.-med. Gesells.
Würzburg, 1856. Vol. VI, p. 153.
v. Kölliker, A., Handbuch der Gewebelehre.
Lambl, Ueber die Epithelialzellen der Dünndarmschleimhaut.
Wiener med. Wochenschr. 1859. Nos. 24 and 25.
Langer, C., Ueber das Lymphgefässsystem des Frosches. Wiener
Acad. Sitzungsb. 1866. Vol. LIII, Pt. I, p. 395.
Letzerich, L., Ueber die Resorption der verdauten Nährstoffe
im Dünndarm. Virchow’s Archiv. 1866, Vol. XXXVII, p. 232; 1867,
Vol. XXXIX, p. 435.
Lipsky, A., Beitrag zur Kenntniss des feineren Baues des
Darmcanals. Wiener Akad. Sitzungsb. 1865. Vol. LV, Pt. I, p. 183.
Oeffinger, Einige Bemerkungen über die sogenannten
Becherzellen. Arch. f. Anat. u. Physiol. 1867, p. 337.
Partsch, C., Beiträge zur Kenntniss des Vorderdarmes einiger
Amphibien und Reptilien. Arch. f. mik. Anat. 1877. Vol. XIV, p. 179.
Remak, R., Ueber peripherische Ganglien an den Nerven des
Nahrungsrohrs. Arch. f. Anat. u. Physiol. 1858, p. 189; also in Zeit.
d. Vereins f. Heilkunde in Preussen. 1840.
Renzoni, Osservazioni e ricerche sul epitelio intestinale.
Rendiconti dell Acad. di Napoli. 1868.
Rusconi, Riflessioni sopra il sistema linfatico dei rettili.
Pavia, 1845.
Sachs, J., Zur Kenntniss der sogenannten Vacuolen oder
Becherzellen im Dünndarm. Virchow’s Arch. 1867. Vol. XXXIX, p. 493.
Schultze, F. E., Das Drüsenepithel der schlauchförmigen
Drüsen des Dünn- und Dickdarms und die Becherzellen. Centralbl. f. d.
med. Wiss. 1866, p. 160.
Schultze, F. E., Epithel- und Drüsen-Zellen. Arch. f. mik.
Anat. 1867. Vol. III, p. 145.
Thanhoffer, L., Beiträge zur Fettresorption und
histologischen Structur der Dünndarmzotten. Pflüger’s Arch. f. d. ges.
Physiol. 1874. Vol. VIII, pp. 391–443.
v. Thanhoffer, L., Ein neuer Nervenapparat im Dünndarm.
Centralbl. f. d. med. Wiss. 1883, p. 33.
v. Thanhoffer, L., Antwort auf Herrn Prof. Klein’s ‘Der neue
Nervenapparat etc.,’ betitelte Bemerkungen. Centralbl. f. d. med. Wiss.
1883, p. 176.
Valatour, M. M., Recherches sur les glandes gastriques et
sur les tuniques musculaires du tube digestif dans les poissons et les
Batraciens. Annales des Sci. nat. 4th Series, Vol. XVI. Zool. 1861,
pp. 219–285.
Watney, H., The minute anatomy of the alimentary canal. Phil.
Trans. 1877. Vol. CLXVI, Pt. II, p. 451.
Wiegandt, Untersuchungen über das Dünndarmepithel. Dissert.
Dorpat, 1860.
v. Wittich, Beiträge zur Frage über Fettresorption. Virchow’s
Arch. 1857. Vol. XI, p. 37.
THE LIVER, GALL-BLADDER, AND PANCREAS.
Barfurth, D., Vergleichend-histochemische Untersuchungen über
das Glycogen. Arch. f. mik. Anat. 1885. Vol. XXV, p. 369.
Brotz, J., and Wagenmann, C. A., De amphibiorum hepate
et glandularum ductu excretio carentium structura deque earundem
functionibus experimenta. Berolini, 1841.
v. Brunn, A., Flimmerepithel in den Gallengängen des
Frosches. Zool. Anzeiger. 1883. No. 148, p. 483.
Eberth, C. J., Die Pigmentleber der Frösche und die
Melanämie. Virchow’s Arch. 1867. Vol. XL, p. 305.
Eberth, C. J., Zur Kenntniss der Verbreitung glatter Muskeln.
Zeitschr. f. wiss. Zool. 1863. Vol. XII, p. 360.
Eberth, C. J., Ueber den feineren Bau der Leber. Centralbl.
f. d. med. Wiss. 1866, p. 897.
Eberth, C. J., Untersuchungen über die Leber der
Wirbelthiere. Arch. f. mik. Anat. 1867. Vol. III, p. 423.
Eberth, C. J., Untersuchungen über die normale und
pathologische Leber. Virchow’s Arch. 1867. Vol. XXXIX, p. 70.
Eberth, C. J., Ueber die Pigmentleber der Frösche. Virchow’s
Arch. 1862. Vol. XXIX, p. 70.
Gerlach, L., Ueber die Nerven der Gallenblase. Centralbl. f.
d. med. Wiss. 1873, p. 562.
Hering, E., Ueber den Bau der Wirbelthierleber. Wiener Acad.
Sitzungsb. 1886. Vol. LIV, Pt. I, p. 335.
Hering, E., Ueber den Bau der Wirbelthierleber. Arch. f. mik.
Anat. 1867. Vol. III, p. 88.
Hering, E., On the liver. Stricker’s Gewebelehre. 1872,
p. 429.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreichs. Leipzig und Heidelberg, 1873–1878. Vol. VI, p. 424.
Jones, C. H., On the structure and development of the liver.
Phil. Trans. 1849. Pt. I, p. 122.
Langley, J. N., On variations in the amount and distribution
of fat in the liver-cells of the frog. Proc. Roy. Soc. 1886.
Vol. XXXIX, p. 234.
Leydig, F., Lehrbuch der Histologie. 1857.
Leydig, F., Die Leber der Fische und Batrachier.
Nussbaum, M., Ueber den Bau und die Thätigkeit der Drüsen
(Pancreas). Arch. f. mik. Anat. 1877. Vol. XIII, p. 752.
Popoff, M., The nerves of the gall-bladder (in Russian).
Rudneff’s Journ. f. normal. u. pathol. Histol., etc. 1872.
Remak, R., Ueber runde Blutgerinnsel und über pigmenthaltige
Zellen. Arch. f. Anat. u. Physiol. 1852, p. 115.
Weber, E. H., Ueber die periodische Farbenänderung welche die
Leber der Hühner und Frösche erleidet. Bericht von Verhandl. K. Säch
Gesell. Leipzig, 1850, p. 15.
Zeller, A., Die Abscheidung des indig.-schwefelsauren
Natrons in den Drüsen (Pancreas). Virchow’s Arch. 1878. Vol. LXXIII,
p. 257.
THE SPLEEN.
Billroth, T., Beiträge zur vergleichenden Anatomie der Milz.
Arch. f. Anat. u. Physiol. 1857, p. 88.
Billroth, T., Beiträge zur vergleichenden Anatomie der Milz.
Virchow’s Arch. 1861, Vol. XX, p. 410, and 1862, Vol. XXIII, p. 457;
also Zeitschr. f. wiss. Zool. 1862, Vol. XI, p. 325.
Ecker, Blutgefässdrüsen, in Wagner’s Handwörterbuch der
Physiologie. 1849. Vol. IV.
Gray, H., On the structure and use of the spleen. London,
1854.
Hoffmann, C. K., Bronn’s Thierbuch. Leipzig und Heidelberg,
1873–1878. Vol. VI, p. 509.
v. Kölliker, A., Ueber den Bau und die Verrichtungen der
Milz. Mittheil. d. naturf. Gesell. in Zürich, 1847. Vol. I, p. 120.
Kusnezoff, F., Ueber blutkörperchenhaltige Zellen der Milz.
Wiener Sitzungsber. 1873. Vol. LXVII, Pt. III, pp. 58–67.
Müller, W., Ueber den feineren Bau der Milz. Leipzig und
Heidelberg, 1865.
Remak, R., Ueber runde Blutgerinnsel und über pigmenthaltige
Zellen. Arch. f. Anat. u. Physiol. 1852, p. 115.
Schweigger-Seidel, F., Untersuchungen über die Milz.
Virchow’s Arch. 1862. Vol. XXIII, p. 526.
Stieda, L., Zur Histologie der Milz. Dorpat, 1862.
THE PERITONEUM.
Alltmann, R., Ueber die Veränderungen des serösen Epithels
am blosgelegten Froschmesenterium. Arch. f. mik. Anat. 1878. Vol. XVI,
p. 111.
Arnold, J., Ueber die Durchtrittsstellen der Wanderzellen
durch entzündete seröse Häute. Virchow’s Arch. 1878. Vol. LXXIV,
p. 245.
Batelli, A., Dello addaltamento di alcune cellule endotiali
nelle membrane serose. Lo Sperimentale. 1884, p. 132.
Cyon, Ueber die Nerven des Peritoneum. Bericht über d.
Verhandl. d. Kön. Säch. Gesell. d. Wiss. z. Leipzig, 1868. Vol. XX,
p. 119. Leipzig, 1869.
Grunau, H., Ueber das Flimmerepithel auf dem Bauchfell des
weiblichen Frosches und über den Eileiterbau desselben. Dissert.
Königsberg, 1875.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreichs. Leipzig und Heidelberg, 1873–1878. Vol. VI.
Hoffmann, T., Die Lungen-Lymphgefässe der Rana temporaria.
Dissert. Dorpat, 1875.
Kapff, Untersuchungen über das Ovarium und dessen Beziehungen
zum Peritoneum. Arch. f. Anat. u. Physiol. 1872, p. 553.
Klein, E., On Remak’s ciliated vesicles and corneous
filaments of the peritoneum of the frog. Quart. Journ. Mic. Sci. New
Series, 1872. Vol. XII, p. 43.
Klein, E., On the peripheral distribution of non-medullated
nerve-fibres (nerves of the peritoneum). Quart. Journ. Micros. Sci.
1872. Vol. XII, p. 32.
Leydig, Lehrbuch der Histologie. 1857, p. 325.
Mayer, Ueber die Flimmerbewegung. Froriep’s Notizen, 1836.
Vol. XLVII, p. 179.
Neumann, E., Die Beziehungen des Flimmerepithels der
Bauchhöhle zum Eileiterepithel beim Frosch. Arch. f. mik. Anat. 1875.
Vol. XI, pp. 354–377.
Nicolsky, P., Ueber das Flimmerepithel beim Frosche.
Centralbl. f. d. med. Wiss. 1880, p. 641.
Paladino, G., Dell’ endotelio vibratile nei Mammiferi ed in
generale di alcuni dati sulla fisiologia delle formazioni endoteliche.
Estr. dal Giornale intern. delle Scienze Mediche. 1882. Vol. IV.
Schweigger-Seidel and Dogiel, Ueber die
Peritonealhöhle der Frösche. Arbeiten aus d. physiol. Anstalt zu
Leipzig. 1866, p. 68.
Solger, B., Ueber einige Entwicklungsstadien des
Peritonealepithels der Amphibien-larven. Manusc. d. Naturf. Versamml.
zu Freiburg. 1884.
Thiry, Ueber das Vorkommen eines Flimmerepitheliums auf
dem Bauchfell des weiblichen Frosches. Göttinger Nachrichten. 1862,
pp. 171–174.
Tourneux, Recherches sur l’épithelium des sereuses. Journ. de
l’anat. et de la physiol. 1874.
Waldeyer, Eierstock und Ei. Leipzig, 1870, pp. 72 and 122.
Wolff, W., Ueber freie sensible Nervenendigungen. Arch. f.
mik. Anat. 1882. Vol. XX, pp. 377–381.
THE ALIMENTARY TRACT, ETC. — I. THE ALIMENTARY TRACT.
The alimentary tract consists of the mouth or pharyngo-oral cavity,
the oesophagus, the stomach, the small intestine and the large
intestine; these together forming a tube extending from the mouth to
the cloaca. From the commencement of the oesophagus, at the entrance to
the larynx, to the end of the cloaca, the length of the tube is about
31.5 cm., that of the various parts being:
From glottis to pylorus
5.5 cm.
From pylorus to large intestine
22.0 cm.
Large intestine to end of cloaca
4.0 cm.
Total length
31.5 cm.
A. The Mouth.
The mucous membrane covering the tongue will be described with the
sense-organs (see organ of taste).
a.General description. The mouth of R.
esculenta, as in all other amphibia, with the exception of the
lowest (Siren, Proteus, etc.), is of considerable width,
and extends backwards as far as the middle of the tympanic membrane.
The upper margin of the mouth possesses a lip or fold of the skin
(SS1), which projects sufficiently to prevent the
teeth being seen from the front or from the sides. This lip-like rim is
most prominent in the premaxillary and superior maxillary regions, but
can be traced along the whole length of the upper jaw, and on to the
lower jaw, by means of a well-marked fold at the angle of the mouth.
Beyond this point the lip is absent, as the skin is closely attached to
the bony mandible.
Fig. 178.
The roof of the mouth.
Cho
Posterior naris.
ID
Opening of intermaxillary glands.
F
Fold of mucous membrane.
F1, F1
Prominences of mucous membrane.
K
Muscles.
O
Floor of the orbit.
S
Lip.
S1
Lip.
T
Eustachian tubes.
Vo
Vomer.
On the roof of the mouth the following structures
can be made out:
immediately within the lip is a deep, well-marked groove, the outer
boundary formed by the lip, the inner by a fold of the mucous membrane
(Fig. 178 F); this fold increases from behind forwards as
far as the premaxillary bones, where it forms two prominences
(F1, F1) with an interval between.
These correspond to the palatine processes of the premaxillary bones:
immediately behind them are openings of the ducts of the intermaxillary
glands. In the groove so formed are placed a single row of simple
teeth, which, though subject to many variations, are usually about
fifty in number.
A little further back and to either side of the median line is a
small group of vomerine teeth (Vo); each group has from five to
ten teeth; external to these is on each side a transversely-placed oval
opening, the posterior nares (Cho). These apertures are directed
outwards and backwards into a shallow groove, bounded anteriorly by a
fold of mucous membrane.
According to Wiedersheim the mucous membrane immediately around the
vomerine teeth is supplied with taste-bulbs; the epithelium surrounding
these being non-ciliated.
The roof of the mouth underneath the parasphenoid is somewhat
vaulted and on either side depressed by the eyeballs, which project
downwards more or less prominently (O, O). Still further
back are the openings of the Eustachian tubes (Fig. 178 T),
one on each side, and almost surrounded by the limbs of the pterygoid
bones.
Fig. 179.
The floor of the mouth.
K
Muscles.
L
Opening to larynx.
M
Mandible.
S
Opening to voice-sac (in males only)
Sm
Chin.
Z
Tongue.
Z1
Left cornu of bifid tongue.
†
Folds opposite hinder border of the hyoid.
On the floor of the mouth (Fig. 179) the tongue
(Z, Z1) forms the most prominent object;
its shape varying according to the state of contraction of its
muscles. Behind it, in the middle line, is a transverse groove
(†), corresponding to the posterior border of the hyoid bone, and
still further back is the opening to the larynx (L), a longitudinal slit about
3 mm. in length. The mucous membrane to either side of the tongue is
only slightly folded, and a little in front of the angle of the mouth
is depressed into an aperture (S), opening into the vocal sac.
This opening is surrounded by small radiating folds of mucous membrane,
and is oval in shape.
Towards the oesophagus the mucous membrane of both the roof and the
floor of the mouth is thrown into numerous longitudinal folds.
b. The minute structure of the several parts.
(1) The mucous membrane of the mouth. At the junction of the
skin and the mucous membrane there is a gradual transition from the
stratified epithelium of the skin to a single layer of columnar
epithelium. On the floor of the mouth this condition is reached
at the tongue; on the roof the transition takes place more quickly.
The columnar epithelium of the mouth (that of the tongue is excluded
from this description) is ciliated; scattered cells, which are not
ciliated, are found here and there irregularly, but are not numerous.
The cylindrical cells are very finely granular in their upper parts,
clearer in the middle portion, more coarsely and darkly granular in
their deeper portions; each cell is possessed of a large, well-defined,
oval nucleus, which contains one or sometimes two nucleoli. The
non-ciliated cells usually present a sharply differentiated,
structureless, hyaline, free border (Schultze). The epithelium towards
the margin of the mouth, where it is stratified, is also ciliated.
Goblet-cells occur in every part of the epithelium, whether ciliated
or non-ciliated, and their forms vary very greatly.
[The submucous layer is a fibrous connective-tissue
matrix, very rich in nerves and blood-vessels. The capillaries are
arranged in small, somewhat polygonal meshes (Fig. 180), and are
peculiar, with those of the anterior part of the oesophagus, in having
small dilatations.
This arrangement was first71 described by Langer, and later by Schöbl.
The dilatations are placed quite irregularly on the capillaries,
sometimes only on one side, sometimes on both sides of the vessel;
a slight constriction occurs at the neck of each dilatation, where
it opens into the capillary72. The nerves of the mucous membrane underneath
the orbits have nerve-cells attached to them (Stirling and Macdonald,
page 170). The lymphatics are very numerous, and for the most part
follow the course of the blood-vessels to their finest twigs, beyond
which they follow an independent course (Langer).]
(2) The teeth are wanting in the lower jaw; on the roof
of the mouth they are found in two situations: as a single row in
the groove within the lip, and a group on each vomer. Each tooth has
the form of an elongated cone, which in the case of the jaw-teeth is
curved, in that of the vomerine teeth straight. The teeth are fixed
to the jaw so as to project upwards and slightly inwards, those
at the front of the mouth projecting backwards, and those on the
vomers project backwards. Each tooth has a small, sharp projection,
or secondary crown on its outer surface (Fig. 181), placed near the
mucous membrane. The teeth are fixed to the bones by means of Crusta
petrosa, which is again united to the bones of the mandible by
a matrix of spongy bone, continuous for the several teeth. Between
the tooth and the mucous membrane is a layer of flattened epithelium
(II), which extends more deeply on the inner side of the tooth
than on the outer; the layer is continuous with the epithelium of
the mouth, and is two to three cells in thickness. Each tooth has
fine longitudinal grooves on the basal part of its outer surface, and
consists of two parts, a crown and a root. The teeth possess large
cavities, the wall being thin and almost of even thickness, except on
the inner surface of the basal portion of the root, where the wall is
wanting, and so forms a large aperture to the root.
Fig. 181.
I. Transverse section of the premaxillary bone to
show attachment of the teeth; after Hertwig.
Magnified 22 times.
II. Dentine and enamel; after Hertwig. Magnified
500 times.
III. Enamel: after Hertwig. Magnified 500 times.
A
Blood-vessel of the pulp-cavity.
C
Crusta petrosa.
D
Dentine.
F
Processus dentalis.
H
Layer of epithelium.
O
Tooth cuticle.
R
Reserve.
S
Enamel.
X
Cutaneous glands.
The general skeleton of the tooth is formed of dentine, this
is covered on the crown by a layer of enamel, and the Cuticula
dentis on the socket by a layer of Crusta petrosa.
α. The dentine is a homogeneous substance pierced by numerous
tubules (D), which arise at the pulp-cavity and course in a
parallel direction to the surface of the dentine, where they form a
rich network with irregular, interglomerular spaces. The inner surface
of the dentine is rough, through the presence of numerous small, dark
tubercles.
β. The enamel covers the dentine on the apical portion of
the tooth. It has tubes coursing through it, which are continuous with
those of the dentine, and presents also circumferential striations
(Fig. 181 III).
γ. The tooth cuticle (Cuticula dentis) is colourless
and covers the enamel. It is highly refractive, very transparent,
and very resistant to chemical reagents. From the apex, towards
the Crusta petrosa, it thins very rapidly, but is continued
sufficiently far to cover a portion of the Crusta petrosa.
δ. The Crusta petrosa resembles bone, except that it contains
no Haversian canals; it possesses cells which resemble bone corpuscles,
and are usually somewhat rounded or oval and communicate with each
other by their processes; for the most part it is homogeneous and free
from cells (Hertwig).
ε. The pulp-cavity contains a connective-tissue very rich in
cellular elements; those cells adjacent to the dentine are arranged
in a layer (Membrana eboris) which has somewhat the appearance
of a layer of epithelium. The cells (odontoblasts) of this layer are
spindle-shaped, and send processes (dentinal fibres) into the dentinal
tubules. A small blood-vessel can be traced into each cavity, but as
yet no nerve has been found in the pulp-cavities.
[Smith (l. c.) has, after careful investigation, come
to the conclusion that the teeth of R. esculenta and R.
temporaria are practically alike, therefore the methods of
differentiating the two species by means of the teeth, as given by
Leydig, are not to be relied on.]
(3) The intermaxillary glands (Glandula
intermaxillaris) consist of a mass of convoluted tubes, lying
chiefly between the premaxillary bones and the capsule of the nose,
and opening by about twenty to twenty-five ducts at the fore-part of
the mouth (Fig. 178ID). A portion of the glands extends high
into the nasal cavity (Born), while dorsally another portion lies under
the skin and the M. dilatator and M. lateralis narium,
which together act as compressors to the subjacent glands: a small,
elastic, cartilaginous rod, placed between the anterior margin of
the nasal capsule and the under surface of the ascending limb of the
premaxilla, opposes these muscles on either side by its spring-like
action (Wiedersheim).
In a fresh skull the openings of the ducts can easily be seen after
washing away the mucous secretion; they are, however, seen to better
advantage by treatment with Müller’s fluid and subsequent staining
with carmine. With sufficient magnifying power, they are then seen as
a row of bright dots. The tubules are of uniform thickness, placed
closely side by side, and surrounded by a nervous plexus, which
contains numerous branching nerve-cells. The epithelium of the tubules
is cylindrical, with a rounded, finely granular nucleus; processes
from the peripheral ends of the cells are continued to a Membrana
propria. The ducts are lined with columnar, ciliated epithelium.
The secretion of the glands is remarkably adhesive, and is
wiped off by the tongue when it is projected; by this means the tongue
becomes a particularly efficacious instrument for capturing prey. The
glands are, both histologically and chemically, pure mucous glands. In
urodeles the homologous glands are placed in the hollow septum of the
nose, between the nasal cavities.
The M. genio-glossus arises, in two parts on either side,
at the side of the chin. One part (Fig. 182 G) is dorsal
and median, the other (Fig. 182 G1) ventral and
external.
Fig. 182.
Muscles of the tongue, seen from the ventral
surface.
G
Median portion of M. genio-glossus.
G1
Lateral portion of M. genio-glossus.
H
Hyoid.
Hy
M. hyoglossus.
L
Larynx.
M
Mandible.
N
Glossopharyngeal nerve.
(4) The tongue (Figs. 179, 182, 183) is a broad, fleshy flap
on the floor of the mouth, to which it is attached by the anterior half
of its ventral surface as far forwards as the chin. Seen from above it
has a wedge-like form, being narrow in front and wider behind, where it
is prolonged at each angle to form two cornua.
By raising the tongue one obtains a view of a portion of the M. hyoglossus. The
two MM. hyoglossi arise (see page 66) some distance apart,
and run forwards and towards each other to meet on the ventral
surface of the hyoid bone; they now assume a longitudinal direction,
and course forwards parallel to each other until they reach the
M. genio-glossus (Fig. 182 G). Each muscle now
divides to form coarse bundles, which ascend on either side of the
M. genio-glossus towards the dorsum of the tongue. In this
course they are encircled by a strong, elastic, connective-tissue
sheath. The sheath is incomplete at the hinder end of the M.
genio-glossus, where it possesses rounded apertures, through which
the glossopharyngeal nerves (N, N) disappear, to be
distributed, after a sharp curve backwards, in the substance of the
organ.
Fig. 183.
Muscles of the tongue, from the ventral
surface.
G
M. genio-glossus.
Gg
Straight fibres of the M. genio-glossus.
Gg1
Curved fibres of the M. genio-glossus.
Hy and Hy1
M. hyoglossus.
Z
Borders of the tongue.
The first part, with its fellow of the opposite side, forms an
arched commissure in the form of muscular rings, which decrease in size
from before backwards, and so form a pear-shaped mass: the second,
external portion, extends backwards, with a slight obliquity, as a
thin, fan-like expansion, to the mucous membrane, where it is inserted.
This arrangement can easily be seen after dissecting away the sheath
(Fig. 183 Hy); the hindermost fibres curve sharply into the
tongue (Hy1); the anterior fibres pass obliquely
forwards and blend with the straight fibres of the dorsal portion of
the M. genio-glossus (Fig. 183 Gg). The arcuate fibres
of the M. genio-glossus pass, for the most part, upwards and
outwards to the tips of the posterior bifid border of the tongue; in
this course they lie as a rule above the M. hyoglossus, but here
and there the two muscles intermix (Fig. 183 Gg1),
and it is by no means easy to separate them.
The M. hyoglossus is the retractor of the tongue, the M.
genio-glossus the protractor.
(For mucous membrane of the tongue, see organ of taste. The vocal
sacs are described with the organs of voice and respiration.)
B. The Oesophagus and Stomach
(Figs. 184, 185, 189, 194, 195, 199).
Fig. 184.
The alimentary canal.
A
Opening of large intestine into cloaca.
Cl
Cloaca.
D
Small intestine.
Du
Duodenum.
HB
Urinary bladder.
M
Stomach.
Mz
Spleen.
Oe
Oesophagus.
Py
Pylorus.
R
Large intestine (rectum).
†
Junction of small and large intestine.
a.General description. The oesophagus is not
separated from the pharyngo-oral cavity by a sharp line of demarcation.
It has a length of only a few mm. in medium-sized frogs (Fig. 184
Oe), and lies in the middle line of the body, supported on
either side by the cornua of the hyoid bone. The oesophagus lies on the
dorsal wall of the larynx, is smooth externally, and is thrown into
well-marked longitudinal folds internally.
The transition from oesophagus to stomach is somewhat indefinitely
marked by a slight dilatation of the tube, often scarcely perceptible,
still it can always be recognized by an abrupt curvature to
the left (Fig. 184 M), which becomes more prominent when the
stomach is distended. Externally the stomach is seen as an elongated,
slightly curved cone, smooth externally and of equal diameter
throughout.
The oesophagus and stomach are held in position by folds of
peritoneum (mesentery), which attaches them to the dorsal wall of
the abdominal cavity, to the lungs, pericardium, and liver; and by
the blood-vessels.
b.Minute structure. The walls of these viscera are
composed of four layers or coats.
(1) The serous coat (Fig. 186) is a layer of endothelium,
lying on a very thin stratum of connective-tissue; the whole derived
from the peritoneum, which encloses the organs.
(2) The muscular coat (Fig. 186 LM and TM) is
arranged in two layers,
one (LM) longitudinal, the other (TM) transverse. The
longitudinal layer is thicker in the oesophagus, and thins as it is
continued to the pyloric end of the stomach. The circular layer, on the
other hand, gains in thickness; both layers are of unstriated muscular
fibre.
(3) The submucous coat (Fig. 186A,
B, and SM) is better developed in the stomach than in
any other part of the alimentary canal. It is formed of a wide-meshed,
loose connective-tissue, which supports numerous blood-vessels and
lymphatics. Towards the mucous coat it possesses a well-differentiated
Muscularis mucosa, which is arranged in two layers, a
longitudinal (B) and a transverse (A).
(4) The mucous coat is possessed of numerous tubular glands,
which vary in structure according to the part of the membrane examined.
They have been the subject of much investigation (Heidenhain, Nussbaum,
Partsch, Langley, and others), and are best described in three groups:
those of the oesophagus, of the first part of the stomach, and of the
pyloric end of the stomach respectively; between each pair of groups
are transitional forms.
Fig. 185.
The abdominal viscera of Rana esculenta (female).
D
Small intestine.
Du
Duodenum.
EE
Ovaries.
H
Heart.
HB
Urinary bladder.
L
Left lobe of liver.
L1
Right lobe of liver.
L2
Middle lobe of liver.
Lg
Left lung.
Lg1
Right lung.
M
Stomach.
Fig. 186.
Transverse section through one of the longitudinal
folds of stomach of Rana temporaria. To show
general arrangement of the walls.—G. H.
A
Transverse layer of muscularis mucosae.
B
Longitudinal layer of muscularis mucosae.
LM
Longitudinal muscular coat.
M
Mucous membrane.
SM
Submucous coat.
TM
Transverse muscular coat.
α. [The oesophageal glands are complete tubular glands lined by
a single layer of epithelium, which very closely resemble the glandular cells of the
fundus of the stomach (Plate II, Fig. 187). The cells are conical or
cylindrical, the protoplasmic contents granular, the granules being
larger than those of the corresponding cells in the stomach (Langley).
Mucous cells are found among the true secretory cells. The cells of the
ducts are sometimes, but rarely, ciliated (Langley).]
β. [The glands of the fundus of the stomach73 are not so complex as the
typical glands of the oesophagus. The cells at the mouth of the gland
are continued into fine processes (Fig. 187), and their outer parts
contain mucigen. The cells of the neck of the gland are more cubical,
and towards the lower part of the neck are mucous cells. The cells of
the body of the gland are of irregular shape, and so placed that the
nucleus of one cell faces the junction of two cells on the opposite
side (Langley). These cells are very finely granular.]
γ. [The glands of the pyloric end of the stomach have been compared
with the mouths and necks of the glands of the fundus (Partsch,
Langley). The cells are of two kinds only (Fig. 188). The cylindrical
cells of the surface of the stomach are continued into the gland,
where they become shorter and sub-cubical; these form the greater part
of the gland. The cells at the deepest portion of the gland are more
rounded, and resemble the mucous cells in the neck of the glands of the
fundus.]
Fig. 188.
Transverse section through the mucous membrane of the pyloric end of
the stomach of Rana esculenta. After Partsch. (Obj. II, Syst. 7,
Hartnack.)
δ. [Between these well-marked groups of glands are various
transitional forms. The transition from oesophageal to gastric glands
is not a continuous one, as glands resembling those of the stomach
can be found nearer the oesophagus than other glands, which more nearly resemble
oesophageal glands. At the same point the mucous membrane is thinner
than either in front or behind. In the same way an intermediate zone
exists between the typical glands of the fundus and pylorus of the
stomach.]
In both oesophagus and stomach the mucous membrane is thrown into
longitudinal folds when the organs are empty. The epithelium of the
surface of the oesophagus is mostly ciliated, and possesses numerous
goblet-cells; according to Klein the cells are not set vertically on
the subjacent submucosa, but obliquely.
[The epithelium of the surface of the stomach is, at least in part,
ciliated (Regéczy, Trinkler, and others), and has numerous goblet-cells
(Schultze, Heidenhain, Bleyer, Eimer, Oedmonson, and others).]
(5) [The nerves of these organs, according to Gonjaew,
contain both medullated and non-medullated fibres, which have
nerve-cells attached to them. From these fine branches pass, either
with the blood-vessels or alone, to the mucous coat, losing their
medulla on the way. In this course they inosculate very freely, and
are then distributed as very fine, beaded fibrils to the glands and
epithelium, which are very richly supplied.]
(6) [The blood-vessels and lymphatics very closely
resemble the corresponding structures in the small intestine (p. 290);
the blood-vessels form a rich anastomosis in the submucous membrane;
the lymphatics are arranged in two systems, one under the serous coat,
and a larger system in the mucous and submucous coats. The oesophagus
lies free in a peri-oesophageal lymph-sac (Robinson).]
C. The Small Intestine.
a. General description. The small intestine commences behind
the middle of the abdomen at the pyloric end of the stomach, from which
it is marked off by a slight constriction. The first portion of the
small intestine is the duodenum (Figs. 184 and 194Du); by means
of an abrupt turn it winds directly forwards, parallel to the long axis
of the stomach; the pancreas is placed in the loop so formed.
The whole of this portion of the intestine, together with the greater part of the stomach,
is, in the normal condition, under cover of the liver (Figs. 185,
194): while under the liver the intestine is firmly attached to
the deep surface of that organ by a short but strong Ligamentum
hepato-duodenale; it then turns suddenly backwards, increases in
size, and by means of numerous convolutions occupies a considerable
portion of the right half of the abdomen (Fig. 184D). It is
held in position by a well-developed mesentery.
b.Minute structure. Like other portions of the
alimentary canal, the small intestine is formed of four layers:—
(1) The serous coat presents no peculiarities; it consists
simply of a layer of endothelial cells, with a small amount of
sub-endothelial connective-tissue.
(2) The muscular coat is in two layers, the outer
longitudinal layer being very thin, the inner circular layer thick.
(3) The submucous layer resembles that of the stomach, but
is not so thick; the muscularis mucosae is well developed and
arranged, as in the stomach, in two layers.
(4) The mucous coat (Fig. 189) is thrown into folds, which
differ in various parts of the tube.
Fig. 189
Mucous membrane of the pyloric end of the stomach and the
duodenum.
a
Mucous membrane of the stomach.
a1
Commencement of duodenum.
b
Duodenal mucous membrane arranged in irregular network.
c
Semi-lunar folds of the mucous membrane.
c1
d
Longitudinal folds of the mucous membrane.
The longitudinal folds of the stomach are compressed together
towards the pyloric end of the stomach (a) and diminish
in size; at the commencement of the duodenum they end abruptly
(a1), but without any indication of a valvular
arrangement.
Immediately beyond the pylorus the mucous membrane is folded so as
to form an irregular network of folds which inclose irregular alveoli;
the folds are thicker on the concave surface of the duodenum, and form
a longitudinal ridge (b); in this ridge the alveolar spaces
are much smaller than those to either side. The irregular folding
extends through two to three cm., when a more regular arrangement
commences in the form of two adjacent series of transverse folds
(c, c1). Each fold is semi-lunar in shape, with the
convexity attached to the wall of the tube and directed forwards, while
the concave free border and pocket-like space enclosed are directed
backwards.
The arrangement of these folds reminds one of the semi-lunar valves
of the human heart, and probably one of their functions is to prevent
the regurgitation of the chyme (Wiedersheim).
The corresponding valves of opposite sides meet at each end at an
angle, the apex of which is directed away from the stomach. On these folds and between them
are smaller, secondary folds, partly irregularly arranged, partly
longitudinal (d d).
Towards the middle of the small intestine this valvular arrangement
is lost, to be replaced by an irregular net-like folding; beyond this
longitudinal folds arise, which proceed in a sinuous course towards the
large intestine.
The whole mucous membrane, both on the folds and otherwise,
is covered with a simple layer of columnar epithelium, which is
continued into numerous simple follicles (glands of Lieberkühn) found
throughout the mucous membrane of the small intestine. The cells are
placed on a basement membrane, which rests on a thin layer of loose
connective-tissue, intervening between the epithelial coat and the
muscularis mucosae. The epithelial cells are intermixed with a
large number of goblet-cells, and have between them fine processes from
the connective-tissue corpuscles of the subjacent layer; many of these
processes extend to or even beyond the free margin of the epithelial
cells.
The individual cells are columnar, possessed of a well-marked
cell-wall, and have distinct, large, oval nuclei, containing one
or more nucleoli. The protoplasmic contents are granular, and with
proper treatment show a very distinct intracellular network. The free
margins of the cells are sharply marked off from the cell-contents,
and are more firmly attached to the corresponding portions of adjacent
cells than the rest of the cell-wall. This margin has a longitudinal
striation, which owing to the important function performed by this part
of the intestine, namely, absorption of the fat, has been the subject
of many important investigations.
[In the following brief summary of the earlier researches on the
minute structure of the intestinal epithelium, in which the intestine
of the frog was chiefly used, the memoirs in which these investigations
are recorded are referred to in the order of time.
1837. Henle first described the border as a thickened, highly
refractive portion of the cell-wall.
1855. Kölliker and Funke, after independent research, described the
longitudinal striation:
Funke offered no explanation of the fact, while Kölliker considered
it due to the presence of fine tubules. Later Funke gave a modified
support to Kölliker’s view by admitting the presence of tubules around
the circumferential part of the border.
1856. Donders gave a description corresponding with that of
Henle.
1857. Brettauer and Steinach gave it as the result of their
investigations that the border was composed of closely-applied fine
rods: v. Wittich first showed that the borders of adjacent cells
were more firmly attached than the rest of the cell; he admitted the
presence of apertures, but considered the whole appearance to be due to
post-mortem changes.
Welcker and Friedreich agreed with the views of Brettauer and
Steinach, but traced the striation throughout the length of the cells,
in fact traced the tubules to the connective-tissue below.
1858. In this year Heidenhain published his results; he held the
striation to be due to the presence of fine rods, and was the first
to show that processes of the connective-tissue corpuscles passed up
between the epithelial cells; he found fat globules in the epithelial
cells, in the connective-tissue, and in the lacteals.
Friedreich described the striation as continued through the whole
length of the cells, and as due to tubules.
1859. Lambl denied the presence of the rods, and considered the
whole phenomenon an optical appearance due to the cell-wall; in this
view he was supported by Vlakovich of Padua and Amici of Florence.
1860. Wiegandt held the border to be an independent covering, and
the striation to be due to folding or wrinkling.
Col. Balogh described the border as formed of rods, but denied that
these existed except when brought about by the action of fats; in
support of this view he showed that the striation was wanting when fat
was absent.
1865. Lipsky held the border to be composed of rods.
1866. Henle described the cells as in his former work, but now held
the border to be composed of rods, in fact to represent a ciliated
border.
1867. Erdmann described the border as being of two layers, an upper,
thicker layer, with both longitudinal and transverse striation, and a
lower, thinner layer, the true cell-wall. The upper layer he described
as capable of splitting in the directions of both striations.
Schultze described the border as not being in intimate connection
with the protoplasm of the cell. Arnstein and Wiegandt supported
Heidenhain’s description.
1868. Albini e Renzoni described the part as resembling resting
cilia.
1869. Eimer traced fat-globules into all the parts, epithelium,
connective-tissue, and vessels; and held that the fat could pass from a
lacteal to a branch of the Vena porta.
1870. Heidenhain, after further investigation, supported his earlier
views.
1874. Thanhoffer described the membrane as perforated, and the
protoplasm of the cells as actively sending protoplasmic processes
through these apertures; this he had seen in frogs in which all
connection with the spinal nerves had been severed.
1875. Benjamins could not find the striation to be a constant
occurrence, and failed to find the processes described by
Thanhoffer.
1876. Krause found rod-like bodies round the margin of the
border.
1877. Fortunatow supported Thanhoffer’s view.
1881. Landois observed appearances in Spelerpes fuscus, which led
him to support Thanhoffer’s views.
1883. Wiedersheim supported Thanhoffer’s views.
1884. Wiemer supported Thanhoffer’s observations.
1888. Paneth failed to find any contractile protoplasmic processes,
and asserts that the circumference of the border, when examined under
certain conditions, is composed of rods.
From the same causes the goblet- or chalice-cells, already
mentioned, have been the subject of much speculation and
investigation.
1846. Frerichs drew and described these cells as empty cells.
In 1848 these cells were first described as epithelium capitatum by
Gruby and Delafond.
In 1856 Donders described the cells as being open, and as
discharging their contents into the canal; the cell-walls being then
pressed together by the neighbouring cells, and the cell-contents being
then gradually reformed.
In the same year Kölliker published results closely agreeing with
those of Donders, and he traced the various stages of the process.
1857. Brettauer and Steinach held them to be cells which had lost
their contents, and as the ‘cuticular border’ was absent, concluded
that the cell-contents were in closer connection with the ‘border’ than
with the rest of the cell-wall.
1865. Lipsky and Sachs both doubted the presence of such cells, and
considered them due to the action of reagents or post-mortem change.
1866. Letzerich described the cells as open, and regarded them as
the commencement of the lacteal system, while Dönitz thought the whole
appearance due to reagents.
1867. Schultze and Eimer, independently, described them as
unicellular glands. Erdmann, however, again denied their occurrence
under normal conditions.
Oeffinger held the goblet-cells to be modified ordinary cylindrical
epithelium cells; in which view he was supported by Arnstein.
1868. Schultze and Eimer, after renewed investigations, reiterated
their former opinions.
1869. Eimer described the goblet-cells as secreting mucin, and as
capable, by division, of throwing out pus-like cells.
1876. Krause described the cells as containing granular contents,
which under certain conditions are thrown out.
1877. Tolldt considered them artificial productions. Edinger
asserted that they are formed from the cylindrical cells.
1877–1885. Partsch (1877), Klein and Hebold (1879), Stöhr (1880),
Patzelt (1882), Haller (1883), Holl (1885), support the last view.
1878. Hoffmann supported Schultze’s views.
1886. List describes these organs as unicellular mucous glands.
1887. Paneth described them as secreting mucous and as being derived
from the cylindrical cells.]
(5) [The blood-vessels of the small intestine (p. 234) have
been described by Langer; he finds the vessels arranged in networks,
one a subserous network, placed underneath the serous coat, and formed
of elongated, irregular, four-cornered meshes. When the intestine is
distended the meshes are rectangular.
The vessels to the mucous membrane divide and anastomose very freely
in the submucous layer, and then form an irregular network on the inner
surface of the Muscularis mucosa; this network follows all the
foldings of the mucous membrane, and thereby supplies a double layer
to each villous fold of the mucous membrane. The meshes are usually
four-sided or five-sided.]
Fig. 190.
Isolated fold of mucous membrane of small intestine
of Rana temporaria; after Langer. Forty times
natural size. Blood-vessels striped, lacteals shaded.
Fig. 191.
Transverse section of a fold of the mucous membrane of Rana
temporaria; after Langer. Sixty times natural size.
(6) [The lymphatics of the small intestine (Figs. 190, 191).
The lymphatic vessels on reaching the intestine usually bifurcate; the
two branches, as a rule, follow and enclose an arterial twig. From the
serous layer they receive the contents of a very fine lymphatic plexus,
the lumens of which are slightly greater than that of the corresponding
capillaries; from the mucous layer they receive the contents of the
lacteals: between these two layers the lymphatics anastomose very
freely by means of numerous branches (Langer).
The lacteals are lined with an epithelioid layer and traversed by
connective-tissue trabeculae, which have a like covering. The lacteals are not simple but in
the form of a coarse network (Fig. 189) (Langer).]
(7) [The nerves of the small intestine (p. 200) usually
follow the arteries to the muscular coats, between which they form a
plexus (Auerbach’s plexus); from this numerous twigs are given off,
which course alone or in company with vessels to the mucous coat, where
a second plexus (Meissner’s plexus) is formed. Auerbach’s plexus,
according to Klein, consists of bands of nervous fibrils in endothelial
sheaths; they branch and inosculate, and thus form a plexus. Where
several such branches meet, a more or less complicated decussation of
the bands of fibres takes place. Along these nervous bands are ganglion
cells, either isolated or in groups. The cells are large, generally
spherical, and contain a sharply outlined nucleus with a single or
double nucleolus. The smaller cells generally appear to possess only
one process, which can be traced from the protoplasm of the cell
between the fibrils of the nerve-trunk. The larger cells are distinctly
multipolar, their protoplasm being provided with a number of fine
processes, or, as is oftener the case, with one large and several small
processes. In many instances Klein was able to distinguish around the
ganglion-cells a capsule of a spherical or ovoid shape. In these cases
the body, as well as the processes of the ganglion-cell, were lying
within the capsule. This system of ganglion-cells is in connection with
the individual bundles within the nerve-trunks.
Klein describes a second system of ganglion-cells, situated in
meshes, which are formed by the nerve-trunks of the plexus itself.
These ganglion-cells are much larger than the former, and are
multipolar; their protoplasm, which is distinctly fibrillar, with
granules between the fibrils, is provided with one or two long, thick
processes and several short and thin ones; generally the processes
are branched. The general shape of the cells is oblong, the thick,
long processes being commonly at the two opposite poles. The cells are
generally isolated, sometimes situated in the centre of a mesh, or
more commonly near a nerve-trunk that borders the mesh on one side.
Each ganglion-cell is connected with a nerve-trunk of the plexus by at
least one process. In a few of the nerve-trunks of the general plexus,
isolated medullated nerve-fibrils are seen to pursue an almost straight
course from one trunk into another and divide into two. There is no
connection between these medullated fibres and the ganglion-cells.
Auerbach’s plexus is a much finer plexus than that just
described, and the ganglia are much smaller. It supplies twigs to the
Muscularis mucosa; these break up into fine fibrils, which
follow the direction of the muscle-fibres; other twigs supply the
blood-vessels, with which they can be traced into the bases of the
folds of mucous membrane. Thanhoffer has recently (l. c.)
described nerve-fibrils, which terminate in the mucous epithelium.]
From a transverse section of the large intestine
of Rana temporaria, moderately distended.—G. H.
A
Denser portion of submucous coat.
B
Looser portion of submucous coat.
C
Artery, cut obliquely.
D
Circular muscle-layer.
E
Longitudinal muscle-layer.
a.General description. The large intestine is a flask-shaped
viscus, lying in the median line. The small intestine opens into it
by an abrupt curve at its anterior end. The large intestine is the
widest part of the alimentary canal, is thin-walled, and diminishes
in width towards its hinder end, where it opens into the cloaca
above the opening of the bladder.
b. [Minute structure.
(1) The serous coat resembles that of the small intestine, etc.
(2) The muscular coats resemble those of the small intestine, but
are thinner; the longitudinal layer is, however, proportionally
thicker (Wiedersheim).
(3) The submucous coat (Fig. 192) resembles that of the small
intestine in its general structure; the portion lying immediately
beneath the mucous membrane (B) is denser in structure.
This layer has no Muscularis mucosa.
(4) The mucous coat (A) is a simple layer of large,
columnar, epithelial cells, with large oval nuclei. The cells have
a hyaline free border, but this possesses no striation. The mucous
membrane is usually described as possessing numerous simple follicles
(glands of Lieberkühn); in those specimens which I have examined
they have been entirely absent (Figs. 192, 193). At six to eight
points in a transverse section of a rectum moderately distended the
submucous coat is thinner, and so throws the mucous coat into slight,
longitudinal grooves; but these do not in the least resemble the glands
of Lieberkühn.
Fig. 193.
Transverse section of large intestine of Rana esculenta; the
mucous membrane thrown into longitudinal folds in consequence of the
organ being contracted. Arteries injected with carmine.—G. H.
A
Large circular vessels within the muscular coats.
B
Fine anastomosis to the mucous coat.
(5) The epithelium possesses goblet- or chalice-cells (Hoffmann),
the number of which probably depends upon the period of the year and
the state of digestion. In the rectum, from which the section for
the figures 192 and 193 were cut, not one goblet-cell was found in a
complete series of sections.
If the rectum be contracted, the mucous membrane is thrown into
longitudinal folds.
(6) The blood-vessels (Fig. 193) have a simple arrangement.
The arteries are large, and form oblique loops around the intestine,
lying under the peritoneum; from these branches are given off to form
a series of rings in the submucous membrane (Fig. 193 A); from
these fine twigs are given off to form a fine anastomosis under the
mucous membrane (B).
(7) The lymphatics of the large intestine are arranged in two
chief systems: one under the serous coat resembles the corresponding
system of the small intestine. The second set forms a network of
rounded loops in the submucous coat, which give rise to a secondary
set of smaller vessels towards the mucous membrane; this secondary
system forms a sort of trellis-work standing on the rounded loops,
and so maps out small blocks of the thick submucous coat. Towards the
cloaca the arrangement is simpler; the secondary lymphatics are lost,
while the primary lymphatics tend to form elongated, longitudinal loops
(Langer).]
II. THE GLANDS CONNECTED WITH THE INTESTINAL CANAL. — III. THE SPLEEN. — IV. THE PERITONEUM.
A. The Liver and Gall-bladder.
a.External form.
(1) The liver (Figs. 185, 194) is a large, reddish-brown
organ, occupying a large part of the anterior abdominal region.
It consists of three or more lobes, which present many individual
variations; as a rule there are two larger lateral lobes
(L and L1), and a smaller median lobe
(L2). Each lobe has a superficial or ventral surface,
which is convex, and a deep or dorsal surface, which is concave and
directed towards the other abdominal viscera lying above the liver. The
two surfaces of each lobe meet to form a sharp border around the lobe,
except where the three lobes are more intimately attached, opposite the
apex of the heart (Figs. 185, 194); at this place each lobe possesses a
small, flat, or slightly concave anterior surface.
Fig. 194.
The liver, seen from the ventral surface.
Du
Duodenum.
H
Heart.
L
Left lobe of liver.
L1
Right lobe of liver.
L2
Middle lobe of liver.
M
Stomach.
The left lobe (L) hides the greater portion of the stomach,
and has near its inner border a deep fissure, which runs forwards
and so marks off a more
or less well-marked fourth lobe. The anterior portion of the left lobe
is attached to the corresponding portion of the right lobe by a narrow
commissure.
The median lobe (L2) extends backwards as far as
the pylorus, and covers the commencement of the intestine together
with the pancreas; these organs can, therefore, not be seen until
this lobe is displaced. A fifth lobe is sometimes found on the dorsal
surface of the median lobe, and to it or to the dorsal surface of
the median lobe the small intestine is attached by the Ligamentum
hepato-duodenale (Fig. 195 Lhp). The Vena portarum
enters the liver behind this ligament.
The right lobe extends much further dorsalwards than the left lobe,
and even comes in contact with the lung, the vessels of which sometimes
indent its surface in spirit specimens. This lobe is also in contact
with the base of the fat-body, and in females with the oviduct.
By drawing the lobes of the liver to either side and displacing the
heart towards the head, the posterior caval vein is seen passing from
the liver to the heart, and the hepatic commissure joining the lateral
lobes is brought into view.
(2) The gall-bladder (Fig. 195G) is placed on the
dorsal surface of the liver in the deep niche between the right and
left lobes; it is attached to the liver by connective-tissue and
peritoneum.
Fig. 195.
The pancreas and bile-canals. The liver has been displaced
towards the head.
Dc
Common bile-duct.
Dc1
Common bile-duct after leaving the pancreas.
Dc2
Opening of the common bile-duct into the duodenum.
Dcy
Cystic ducts.
Dh
Hepatic ducts.
Dh1
Supplementary hepatic ducts from the middle lobe of the liver.
Du
Duodenum.
G
Gall-bladder.
L
Left lobe of the liver.
L1
Right lobe of the liver.
L2
Middle lobe of the liver.
L3
Fourth lobe of the liver.
Lhp
Gastro-hepatic ligament.
M
Stomach.
P
Pancreas.
Py
Pylorus.
P1
Ducts of the pancreas.
The gall-bladder is round or oval in form; when moderately full it
has a smooth, outer wall, which is thin and allows the green colour of
the bile to be seen. It possesses a duct (Dcy), the cystic duct
(Ductus cysticus), which bifurcates near its origin.
The two cystic ducts (Fig. 195 Dcy) join the larger hepatic
ducts, as shown in the figure, and so form a simple anastomosis, from which three branches (3)
of varying size unite at the anterior extremity of the pancreas to form
the common bile-duct (Ductus choledochus, Dc). The common
bile-duct runs through the whole length of the pancreas, receiving
near its origin additional hepatic ducts (Dh1)
from the middle lobe of the liver. In this course the duct lies
either on the ventral surface of the pancreas or under a thin layer
of the glandular tissue; it receives the ducts of the pancreas and
leaves that organ at its posterior border as a round and strong canal
(Dc1). The duct courses in the gastro-duodenal
ligament, and reaches the dorsal surface of the duodenum at a very
acute angle; it then pierces the wall obliquely and terminates with a
slit-like or elongated oval opening.
b. [Minute structure.
(1) The liver is composed of various tissues: it possesses a
peritoneal covering, a fibrous covering, which supplies trabeculae to
support the various other tissues, blood-vessels, hepatic cells or true
liver parenchyma, and bile-canals.
α. The peritoneal covering of the liver encloses the organ
almost completely, the only exceptions being where the various attachments of the liver
are found (see peritoneum). The peritoneal covering of the liver is
for the most part composed of flattened, ciliated cells (Neumann
and Grunau); on the middle lobe these are, however, more or less
replaced by non-ciliated cells. The thickness of these cells varies
considerably, according to the amount of distension to which the liver
is subjected.
β. The fibrous covering of the liver is very thin and very
difficult to demonstrate; it consists of connective-tissue fibres with
very few corpuscles. This covering is prolonged into the liver along
the portal canals, where traces of connective-tissue can always be made
out.
From these processes and from the whole of the inner surface of the
general connective-tissue capsule are given off fine trabeculae, in
which it is very difficult to find any nuclei; these trabeculae are
everywhere extremely delicate and difficult to demonstrate; nowhere do
they form distinct boundaries between lobuli: the structure closely
resembles the sustentacular tissue of a lymphatic gland (Eberth).
γ. The blood-vessels to the liver are the portal
vessels (p. 249) the hepatic veins
(p. 247), and the hepatic artery
74 (p. 233)
(1) The portal vessels pass into the liver on its ventral surface;
they divide into branches which course along the middle parts of
each lobe and give off smaller branches in all directions towards
the periphery; the interlobular branches (Fig. 196 I) forming a very
complex capillary network. As compared with the hepatic veins (Fig. 196
II), the interlobular veins do not give off their capillaries so
abruptly, but tend to supply these from small lateral branches. The
portal veins are accompanied in their course by branches of the hepatic
artery, and often by larger bile-ducts, and thus form portal canals. In
no part do the portal (interlobular) veins or their branches limit the
lobules by distinct rings of vessels, as seen in many higher animals.
The interlobular veins and intralobular veins simply interdigitate with
each other.
(2) The hepatic veins (Fig. 196 I and II) also course chiefly in the
middle parts of the lobes of the liver; they branch, and ultimately
supply intralobular veins which interdigitate with the interlobular
veins (I and II). The capillaries arise very abruptly from an
intralobular vein, and form a network of vessels communicating very
freely with the corresponding capillaries of the interlobular veins.
(3) The hepatic arteries (Fig. 196 III) break up into small branches
which, as a rule, course along the portal canal until near the surface
of the liver, when they leave the portal veins and pass to the surface
to supply the coverings of the liver. In their course along the portal
canals they supply a few very small twigs to the structures forming the
canals. At the surface of the liver the branches of the hepatic artery
form capillaries, which empty themselves into the general capillary
anastomosis beneath (Fig. 196 III).
Fig. 197
Liver-cells, after Kupffer.
δ. The liver-cells (Figs. 197, 198) are large, and of
compressed spheroidal or polygonal shape. They possess no cell-wall,
have usually one but sometimes two large nuclei, each with a
distinct nucleolus. The cells often contain granules of glycogen or
fat-globules. The main fibrillae of the intercellular network are
arranged so as to extend between a bile-capillary and a blood-capillary
(Fig. 197).
ε. The bile-ducts (Fig. 198) commence as fine tubes between
the liver-cells, where they are simply small spaces enclosed by the
hepatic cells; they are usually enclosed by three or four cells,
possibly sometimes by only two cells (Hering). Such bile-capillaries
are usually separated from a blood-capillary by the thickness of one
liver-cell only (Fig. 198).
Fig. 198.
The bile-capillaries; natural injection with sulphindigotate of sodium: v v v represent
blood-capillaries.—G. H.
As a number of such bile-capillaries run together to form a larger
duct, the cells enclosing them change their character, becoming
flattened and broader; these cells may, however, be traced continuously
into the true hepatic cells (Hering and Eberth). The bile-duct so
formed then obtains a slight covering of fibrous tissue, which rapidly
increases in quantity, courses along a portal canal, and receives other
ducts on the way; the epithelium lining it gradually becomes more
elongated, and ultimately resembles that found in the common bile-duct
or the gall-bladder.
In the larger ducts the epithelium is, according to v. Brunn, ciliated; they also possess a
layer of unstriated muscle-fibre (Eberth).
ζ. The pigment of the liver varies very much in amount and
character, according to the time of the year and state of health of the
animal. According to Eberth the pigmentary masses are of about the same
size as the white blood-corpuscles, and are possessed of the power of
amoeboid movement (in young animals). The cells possess two to seven
nuclei and vary much in colour and distribution. As a rule the larger
the amount of pigment in a given liver the smaller is the number of
fat-globules found in the individual liver-cells (Eberth).]
(2) [The gall-bladder and bile-ducts. The gall-bladder
has four coverings.
Fig. 199.
The pancreas and bile-canals. The liver has been displaced
towards the head.
Dc
Common bile-duct.
Dc1
Common bile-duct after leaving the pancreas.
Dc2
Opening of the common bile-duct into the duodenum.
Dcy
Cystic ducts.
Dh
Hepatic ducts.
Dh1
Supplementary hepatic ducts from the middle lobe of the liver.
Du
Duodenum.
G
Gall-bladder.
L
Left lobe of the liver.
L1
Right lobe of the liver.
L2
Middle lobe of the liver.
L3
Fourth lobe of the liver.
Lhp
Gastro-hepatic ligament.
M
Stomach.
P
Pancreas.
P1
Ducts of the pancreas.
Py
Pylorus.
α. A serous coat of peritoneal endothelium.
β. A muscular coat, containing unstriated muscle-fibres and
connective-tissue.
γ. A sub-mucous coat of areolar-tissue.
δ. An internal lining of columnar epithelium.
ε. The walls of the gall-bladder are richly supplied with
blood-vessels from the cystic arteries (p. 233); these form a close
network in the submucous coat.
ζ. The muscular and submucous coats also possess a rich nervous
plexus, which contains ganglia and resembles Auerbach’s plexus of the
intestine (Popoff, Gerlach).]
B. The Pancreas (Fig. 199 P).
a.General description. The pancreas is a flattened,
light yellowish-brown organ, placed in the loop of the duodenum
between this latter and the stomach. The whole organ is within the
gastro-duodenal ligament, and is attached to the liver; hence it is
little influenced by changes in the amount of distension of the stomach
or intestine.
The organ may be completely exposed by either of two methods: in the
former, the liver, stomach, and duodenum are drawn towards the head
and the dorsal surface
of the organ so exposed. In the second method the liver is drawn
backwards, the various peritoneal folds which connect the duodenum with
the posterior border of the liver cut through, and the three organs
then separated; the pancreas can then be conveniently examined.
The size and shape of the pancreas are subject to great variations
in different specimens. The usual shape of the organ is somewhat
triangular (Fig. 199), the left border being usually unbroken, while
the other two shorter borders are broken into lobes. The longest lobe
stretches as far as the pylorus (Py), to which it is attached by
connective-tissue: the opposite extremity of the gland is attached to
the liver.
The excretory duct of the pancreas (Ductus Wirsurgianus)
opens into the common bile-duct at about the middle of the pancreas
(P1); other smaller ducts may open into the same
canal.
b.Minute structure. [The pancreas consists of a
number of lobes loosely held together by connective-tissue; each lobe
is composed of a number of lobules attached to each other much more
intimately. The lobules are made up of tubes lined by a single layer of
glandular epithelium. This epithelium is, as a rule, broadly columnar,
but in the smaller tubes may be cubical or polygonal. Each cell has a
cell-wall, nucleus, and very granular protoplasm; the latter shows two
zones (in the inactive condition), a granular zone near the lumen, and
an outer, clear, and finely striated zone (Nussbaum). The lumen of each
alveolus is very small, and in many cases difficult to make out.
The smallest ducts have no special lining, and are therefore bounded
by the glandular cells; the larger ducts have a flattened, cubical
epithelium, which when seen from the surface has an appearance as if
the individual cells were widely separated from one another; these
ducts have a considerable layer of connective-tissue around them. The
largest ducts are lined with a layer of columnar, ciliated epithelium;
the cilia are very long, usually of about the same length as the cell,
sometimes appearing to be even longer. This epithelium is continuous
with the ciliated, epithelial layer of the common bile-duct, which
it resembles. These largest ducts have an extremely thick layer of
connective-tissue around them.
The pancreas and its ducts are very richly supplied with vessels
and nerves; the nerves forming everywhere a fine plexus, the larger
strands of which usually, but not always, course with the larger blood-vessels. The larger
ducts have an especially rich supply of nerves, of which fibrils may
be traced towards the ciliated epithelium; an anatomical connection
between the two has not, however, been made out.]
a.General description. Although the spleen belongs to
the lymphatic system, it is considered here in order to complete the
description of the abdominal viscera. It is a small, rounded-oval body,
of a reddish-brown colour, suspended in the mesentery near the anterior
end of the large intestine (Fig. 184Mz). In medium-sized
animals the longer diameter is about 6 mm., and is parallel with the
long axis of the body; the shorter diameter is about 5 mm., and the
thickness varies from about 3 mm. to 4 mm. The dorsal surface is flat
or slightly concave (Hilus lienis), and receives the relatively
large afferent and efferent vessels; the rest of the organ is smooth
and rounded, and with its greatest convexity directed towards the left
side.
b. [Minute structure. The structure of the spleen
resembles that of higher animals. It possesses a serous coat
of peritoneum, under which is a fibrous coat; the latter
sends in trabeculae, which divide and form a fine meshwork of
supporting-tissue; the finest trabeculae are formed by the processes
of the connective-cells of the sustentacular structure. According to
Hoffmann, the thickness of the fibres averages 0.001 to 0.011 mm.;
the intervening spaces measure 0.002 to 0.012 mm. The spaces are
filled by the spleen pulp, which consists of true spleen-corpuscles,
blood-corpuscles, and pigment-corpuscles.
The spleen-corpuscles have an average diameter of 0.006 mm.,
and are round or of a rounded oval form. Each consists of a nucleus,
with a very small amount of adherent protoplasm; the nucleus possesses
one or two nucleoli. Some of these cells contain a brownish or black
pigment in granules, but most of them are colourless (Hoffmann).
The pigment-cells equal the white blood-corpuscles in size,
and exactly resemble the corresponding pigment-cells of the liver.
The blood-corpuscles are found in various stages of
disintegration and regeneration.
The arteries, on entering the spleen, at once break up into
branches which pass in all directions, giving off twigs on all sides
and at varying angles; from these capillaries are supplied, which
traverse the parenchyma in all directions. The capillaries empty
themselves partly into veins, partly into the splenic spaces.
The veins commence either as capillaries in connection
with the arteries or by communicating with the splenic spaces. This
communication is brought about by small twigs of about 0.015 mm.
diameter, which have incomplete walls, and so open into the splenic
spaces (Hoffmann).
Malpighian bodies are represented by collections of splenic
cells on various arterial twigs; they are, however, not so sharply
defined as is the case in some higher animals.]
a.General description. The peritoneum is
a thin, pigmented membrane lining the abdominal cavity. Tracing
it forwards from the ventral wall of the abdomen (Peritoneum
parietale), it can be followed along the deeper surface of the
muscles to the pericardium. The middle portion leaves the abdominal
wall by accompanying the anterior abdominal vein; the lateral portions
are continued further forwards, and then ascend on the pericardium and
the deeper surfaces of the lateral walls in the thoracic region.
The peritoneum passes thence to the ventral surface of the liver
(Ligamentum coronarium), covers this surface and passes on to
the dorsal surface of the organ, which, together with the gall-bladder,
it completely encloses. The membrane thus reaches the dorsal wall
(Ligamentum suspensorium hepatis et pericardii); from the
lateral borders of the liver it passes upwards to the dorsal wall, and
thus forms a pocket-like pleuro-peritoneal cavity on either side.
From the dorsal wall and above the attachment of the coronary
ligament of the bladder the peritoneum reaches the root of the lung on
each side, and completely invests the organ: while in the middle line
it covers the outer surface of the oesophagus and attaches it to the
dorsal wall, thus forming the first part of the mesentery.
Just behind the root of the lung, the peritoneum, in female
specimens, has an opening on each side (Ostium abdominale tubae
Fallopiae), by which the oviduct communicates with the peritoneal
cavity.
Tracing the peritoneum backwards, it passes over the ventral surface
of the kidneys so as to exclude them from the peritoneal sac: in the
middle line, between the kidneys, the peritoneum descends to form the
mesentery for the small intestine. At the inner borders of the kidneys,
the testes or ovaries are pushed into the abdominal sac, and so possess
well-marked mesenteries; the mesovarium becomes longer towards the
cloaca, but attains its greatest development in the breeding season,
when it is arranged in numerous folds. Along the outer borders of the
kidneys, in females, the peritoneum again descends into the abdominal
cavities to enclose the oviducts, which have broad mesenteries. Towards
the rectum these mesenteries are shorter and attached to either side
of the bladder by a well-marked free border: as the middle line of
the bladder is attached by the peritoneum to the rectum, two distinct
pouches (Cava recto-vesicalia) are formed, which descend
deeply into the pelvic cavity. The upper walls of these pouches are
pushed in between the urostyle and the rectum, and together form a
strong meso-rectum, which is longer near the Valvula Bauhinii
and continuous with the mesentery of the small intestine. The hinder
portion of this mesentery is very short, and only covers the lateral
walls of the rectum.
With the exception of a small portion of its dorsal surface, which
is attached to the rectum, the whole surface of the bladder is covered
with peritoneum.
The mesentery of the alimentary canal commences in connection with
the oesophagus between the roots of the lungs; it is attached to the
dorsal surface of the liver, covering the posterior caval vein, and is
attached to the gall-bladder. From this point it extends, as a free,
arched fold, to the concave right border of the stomach, which is
completely surrounded by peritoneum.
The gastro-duodenal fold (Ligamentum gastro-duodenale)
extends from the stomach to the pylorus and includes the pancreas. The
hepato-duodenal fold (Lig. hepato-duodenale) extends from the
portal fissure of the liver to the duodenum.
The mesentery of the small intestine is broad and arranged in folds,
which follow the curves of the intestine; and is attached in the
middle line, immediately beneath the vertebrae, where it encloses the
aorta.
The various folds and mesenteries carry the blood-vessels and nerves
to the different organs; in this course the vessels are surrounded by
large lymphatics, which communicate with each other.
b.Minute structure (Fig. 201).
Fig. 201.
Preparations from the peritoneum of Rana esculenta.—G. H.
I. From peritoneum of the ventral wall of abdomen, stained with
silver and logwood (Hartnack, Oc. I, Syst. 7).
II. From mesentery of small intestine of Rana esculenta,
stained with silver (Hartnack, Oc. I, Syst. 7).
III. Preparation to show ciliated cells between non-ciliated cells;
after Neumann.
IV. Vertical section at border of liver to show ciliated
epithelium; after Neumann.
A
Stoma.
B
Pigment-cells.
C
Ciliated cells.
D
Non-ciliated cells.
[The peritoneum is a serous membrane, formed for the most part of
a layer of irregular endothelial cells, arranged on a thin layer of
subserous, connective-tissue (Fig. 201 I, II, and III).
The endothelial cells are attached to each other by
cement-substance, easily stained by silver nitrate. The cells covering
the general surface of the peritoneal cavity are larger and broader
than those covering the mesentery of the small intestine (compare I and
II, Fig. 201).
At various points stomata are found, bordered by smaller and more
deeply staining epithelium (I, A). The membrane covering the
general cavity is also much more pigmented than that covering the
mesentery (compare I and II).
Various portions of the peritoneal surface possess ciliated
cells, and these cells
are usually thicker than the surrounding non-ciliated cells. Such
cells are found especially near the openings of the oviducts and on
the liver. The dimensions of the cells vary; according to Neumann
the average dimensions of ciliated cells on the liver are: 0.006 mm.
depth (without the cilia); nucleus, 0.012 mm. long and 0.003 mm.
broad. The cells are five- or six-sided and bounded by straight sides
(Neumann).]
SECTION VI. THE LARYNX, LUNGS, VOCAL SACS, THYMUS AND THYROID GLANDS, AND THE LYMPHATIC GLANDS (TONSILS?) OF THE HYOID REGION.
THE LARYNX,
LUNGS, VOCAL SACS, ETC.
LITERATURE.
THE LUNGS AND LARYNX.
Arnold, J., Zur Histologie der Lungen des Frosches. Virchow’s
Arch. 1863. Vol. XXVIII, p. 433.
Auerbach, L., Ueber den Bau der Blutcapillaren in den Lungen
des Frosches und an einigen andern Orten. Amtlicher Bericht über die
vierzigste Versammlung deutscher Naturforscher und Aerzte. 1886,
p. 241.
Brittan, Brit. and Foreign Medico-chirurgical Review, 1857.
Vol. XX.
Eberth, C. J., Ueber den feineren Bau der Lunge. Zeitschr. f.
wiss. Zool. 1863. Vol. XII, p. 427.
Eberth, C. J., Ueber den Bau und die Entwicklung der
Blutcapillaren. Würzburger naturw. Zeit. 1866–67. Vol. VI,
pp. 27–32.
Egorow, W., Ueber die Nerven der Lungen. Centralbl. f. med.
Wiss. 1879, p. 305.
Elenz, E., Ueber das Lungenepithel. Würzburger naturw. Zeit.
1864. Vol. V, pp. 66–84.
Frommann, C., Ueber die spontan, wie durch Durchleiten
inducirter Ströme, an den Blutzellen v. Salamandra maculata und an den
Flimmerzellen von der Rachen-schleimhaut des Frosches eintretenden
Veränderungen. Jenaische Sitzungsb. 1880.
Gegenbaur, C., Ueber Drüsenzellen in der Lungen-Schleimhaut
bei Amphibien. Arch. f. Anat. u. Physiol. 1863, p. 157.
Griffini, L., Contribuzione alla patol. del tessuto
epiteliale cilindrico. Arch. per le scienze mediche, 1884. Vol. VIII,
pp. 1–43.
Grützner, Physiologie der Stimme und Sprache. Hermann’s
Handb. d. Physiol. Vol. I, Pt. II, p. 146.
Henle, J., Vergleichende Anatomische Beschreibung des
Kehlkopfes. Leipzig, 1839.
Hoffmann, C. K., in Bronn’s Klassen und Ordnungen des
Thierreichs. Leipzig und Heidelberg, 1873–78. Vol. VI, pp. 514–531.
Hoffmann, T., Die Lungengefasse der Rana temporaria. Dissert.
Dorpat, 1875.
Holmgren, F., Upsala Läkareförenings Förhandlingar, 1867.
Vol. III, pp. 389–399.
Howes, G. B., On a hitherto unrecognised feature in the
larynx of the anurous amphibia. Proc. Zool. Soc. London, 1887,
p. 491.
Hüter, C., Ueber den Kreislauf und die Kreislaufsstörungen in
der Froschlunge. Centralbl. f. med. Wiss. 1873. Nos. 5 and 6.
Kandarazki, M., Ueber die Nerven der Respirationswege. Arch.
f. Anat. u. Phys. 1881, p. 1.
Küttner, Beitrag zu den Kreislaufsverhältnissen in der
Froschlunge. Virchow’s Arch. 1874. Vol. LXI, p. 21.
Leydig, Anatomische-histologische Untersuchungen über Fische
und Reptilien. 1853.
Malpighi, De pulmonibus. Oper. omn. Lugd. Batav. 1687.
Vol. II, p. 328.
Müller, H., Ueber das Vorkommen glatter Muskelfasern in den
Lungen der Amphibien. Würzburger naturw. Zeit. 1861.
Pertik, O., Untersuchungen über Nervenfasern. Arch. f. mik.
Anat. 1881. Vol. XIX, p. 183.
Ranvier, L., Leçons sur l’histologie du système nerveux.
Vol. I, pp. 98–101.
Schestopol, A., Ueber die Durchlässigkeit der Froschlunge
für gelöste und körnige Farbstoffe. Virchow’s Arch. 1879. Vol. LXXV,
p. 199.
Schultze, F. E., Epithel und Drüsenzellen. Arch. f. mik.
Anat. 1867. Vol. III, p. 145.
Schultze, F. E., Die Lungen, in Stricker’s Handbuch der
Gewebelehre.
Stirling, W., On the nerves of the lungs of the newt. Journ.
of Anat. and Physiol. 1882, p. 96.
Treviranus, C. R., Beobachtungen aus der Zootomie u.
Physiologie; nach dessen Tode herausgegeben von L. C. Treviranus.
Bremen, 1839.
THE THYMUS GLAND.
Ecker, Blutgefässdrüsen, in Wagner’s Handwörterbuch der
Physiologie, 1853. Vol. IV, p. 114.
Fleisch, E., Ueber den Bau einiger sogenannten Drüsen ohne
Ausführungsgänge. Wiener Akad. Sitzungsb. 1870. Vol. LX, Pt. II,
p. 55.
Gegenbaur, Vergleichende Anatomie.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreiches. 1873–1878. Vol. VI, p. 503.
Leydig, Lehrbuch der Histologie. 1857, p. 422.
Tolldt, Ueber lymphoide Organe der Amphibien. Wiener Acad.
Sitzungsb. 1868. Vol. LVIII, Pt. II, p. 171.
Watney, H., The minute anatomy of the thymus. Phil. Trans.
1882. Vol. CLXXIII, p. 1100.
THE THYROID GLAND.
Baber, E. C., Researches on the minute anatomy of the thyroid
gland. Phil. Trans. 1881. Pt. III, p. 577.
Ecker, Blutgefässdrüsen, in Wagner’s Handwörterbuch der
Physiologie, 1853. Vol. IV.
Fleisch, E., Ueber den Bau der sogenannten Schilddrüse des
Frosches. Wiener Acad. Sitzungsb. 1868. Vol. LVIII, p. 57.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreiches. 1873–1878. Vol. VI, p. 503.
Huxley and Martin, Practical Biology. 4th edit., 1877,
p. 181.
Leydig, Lehrbuch der Histologie. 1857, p. 376.
Müller, J., Ueber die Entwicklung der Schilddrüsen des
Frosches. Wiener Sitzungsb. 1871. Vol. VI, pp. 428–553.
Müller, W., Ueber die Entwicklung der Schilddrüse. Jenaische
Zeitschr. 1871. Vol. VI, p. 438.
Poincaré, Zur Anatomie der Glandula thyroidea. Journ. de
l’anat. et de la physiol. 1877. Vol. XIII, pp. 123–143.
Rolleston, Forms of Animal Life. 2nd Edit. 1888, p. 77.
Zeiss, O., Mikroskopische Untersuchungen über den Bau der
Schilddrüse. Dissert. Strassburg, 1877.
THE LARYNX, LUNGS, VOCAL SACS, ETC. — I. THE LARYNX. — II. THE LUNGS. — III. THE VOCAL SACS. — IV. THE THYMUS GLAND. — V. THE THYROID GLAND. — VI. THE LYMPHATIC GLANDS OF THE HYOID REGION (TONSILS?).
Fig. 202.
Dissection to show the position and relations of the larynx. The animal
(Rana esculenta) is in the natural sitting position; the toes of the
fore-foot are, however, too much flexed.—G. H.
B
Brain.
C
Gall-bladder.
E
Opening of Eustachian tube.
Eo
Oesophagus.
F
False vocal cords.
G
Epiglottis.
H
Heart.
L
Liver.
V
True vocal cords.
The larynx (Fig. 202) is a short wide tube placed between
the posterior cornua of the hyoid, to which it is attached by
connective-tissue. The long axis of the tube lies in the median line
and almost horizontally, but the posterior end is on a slightly lower
level than the anterior, when the animal is in the natural sitting
position (Fig. 202). The anterior end of the larynx opens into the
mouth by a longitudinal slit (Fig. 179L), and is placed in a
slight depression caused by the folding of the mucous membrane; the
posterior end communicates with the cavities of the lungs.
The larynx is lined with mucous membrane, which is continuous, in
front with that of the mouth, behind with that of the lungs. The organ
has a skeleton of cartilage, and possesses special muscles, by which the supply of air to
the lungs, and the voice can be regulated.
a. The cartilages of the
larynx.
The cartilages of the larynx are five in number, of which four are
paired and one is single.
(I) The cricoid cartilage (Figs. 203, 204) is an oval ring
of cartilage with various processes. The ring-like portion of the
cartilage is placed in a plane which is almost vertical, but which
is directed slightly upwards anteriorly, and slightly downwards
posteriorly (the animal being in the usual sitting position).
Fig. 203.
The cartilaginous skeleton of the larynx.
I. Seen from in front; the spinous process would
normally be more curved.
II. Seen from the left side; the spinous process
should be more curved.
Ca
Right arytenoid cartilage.
Ca1
Left arytenoid cartilage.
C.l.1‑C.l.4
Cricoid cartilage.
P
Lateral plate of cricoid cartilage.
Sp
Spine of cricoid cartilage.
SR
Opening to larynx.
***
The two outer asterisks are above the two apices of the left arytenoid cartilage; the middle one above the pre-arytenoid cartilage.
The sides of the ring are slightly curved inwards on the
anterior surface, and possessed of irregular enlargements
(C.l.1-C.l.4), the space enclosed
by this portion of the cartilage is occupied by a membrane (M),
which forms the floor of the body of the larynx.
From each side of the body of the cartilage, a process
(C.l.2) is given off, which curves backwards and
inwards to join its fellow of the opposite side, the two forming a
blunt spinous process (Sp), which projects backwards, and
is intimately attached to the oesophagus. Between these processes
and the lower portion of the body of the cricoid cartilage are the apertures of the
roots of the lungs (Fig. 203), which, by their attachments to these
cartilages, are kept open.
(2) The arytenoid cartilages (Fig. 203 I, II, Ca,
Ca1) are a pair of cartilages placed in front of
the cricoid cartilage, one on each side. Each cartilage is semilunar
in shape, concave internally, and convex externally. The cartilages
are placed almost vertically, with their posterior borders or bases
parallel to the body of the cricoid cartilage. The superior borders
(Fig. 204) are directed upwards and forwards, the inferior downwards
and forwards. The superior and inferior borders are separated by a
semicircular notch, bounded by two sharp apices. The superior and
inferior angles of the two cartilages are close together, and movably
attached to each other by connective-tissue.
These cartilages vary very greatly in the two sexes. In the males
they are thick, strong, and large; in the female the cartilages are
very thin, more hollowed and much smaller.
Fig. 204.
The larynx and surrounding parts, seen from the ventral surface.
Ca1
Arytenoid cartilages.
Cl1‑Cl4
Cricoid cartilage.
G, G1
Fibrous tissue connecting the larynx with the posterior
cornua of the hyoid.
H
Lesser cornua of the hyoid.
HH
Greater cornua of the hyoid.
Lg
Right lung.
Lg1
Left lung.
M
Fibrous membrane filling the ring-like cricoid cartilage.
Ph4
The M. petrohyoideus tertius.
S
Part of tendon of M. petrohyoideus tertius.
SB, SB1
Mucous membrane bulging from the anterior ventricle of the larynx.
Sp
Spinous process of the cricoid cartilage.
ZK
Body of the hyoid.
(3) [The pre-arytenoid cartilages (Fig. 206 I, P)
are two small elongated cartilages placed in the semicircular notch
between the superior and inferior borders of the arytenoid cartilages.
They are subject to much variation in size, sometimes being merely a
very slender rod, at others a moderately thick oval mass. In female
specimens they appear to be, at times, absent, or to unite with the
arytenoid cartilages, as in these cases a third very small apex is
found on each arytenoid cartilage; but it is always much smaller than
the two neighbouring apices.]
The muscles of the larynx appear in the following order, when
dissected from the mouth:—
b. The attachments of the
cartilages to each other.
The cartilages do not articulate directly with each other, but are
connected by connective-tissue only; there are, therefore, no synovial
sacs.
(1) The M. dilatator aditus laryngis (Henle), (Fig. 205
D.l.) arises on either side from the hinder end of the larger
posterior cornu of the hyoid: the fibres diverge slightly to be
inserted into the middle portion of the outer surface of the arytenoid
cartilage; a smaller bundle of fibres is attached to the deeper-lying
constrictor muscle and to the cricoid cartilage.
(2) The M. constrictor aditus laryngis (Henle), (Fig. 205
C.a.l.), arises on either side from the hinder half of the
dorsal surface of the posterior cornu of the hyoid. The two muscles
enclose the larynx, and are inserted into a median tendinous raphe on
the under surface of the larynx (Jt). The raphe is connected
with the skeleton of the larynx by connective-tissue.
Fig. 205.
The muscles of the larynx.
A.l.
Aperture between the arytenoid cartilages.
C.l.
Cricoid cartilage.
C.a.1
Superior angle of the arytenoid cartilage.
C.a.l.
M. constrictor aditus laryngis.
C.o.l.
M. hyo-arytenoideus anterior.
C.o.l.1
M. hyo-arytenoideus posterior.
D.l.
M. dilatator laryngis.
G
Connective-tissue.
G1
Connective-tissue.
H
Smaller posterior cornua of the hyoid.
HH
Greater cornua of the hyoid.
Jt
Fibrous tissue into which the two constrictions are inserted.
Ph2
Second petrohyoid muscle (M. petrohyoid. I).
Ph3
Third petrohyoid muscle (M. petrohyoid. II).
Ph4
Fourth petrohyoid muscle (M. petrohyoid. III).
S, S1, S2
Tendon of the fourth petrohyoid muscle.
Sp
Spinous process of the cricoid cartilage.
ZK
Body of the hyoid.
(3) The M. hyo-arytenoideus anterior (Fig. 205 C.o.l.)
arises on each side from the inner border of the anterior end of the
cornu of the hyoid; the muscle lies close to the anterior border of
the arytenoid cartilage, and is inserted into a fibrous lamella on the
dorsal surface of the larynx. The M. petrohyoideus tertius is
also partially inserted into this lamella.
(4) The M. petrohyoideus tertius (Fig. 205
Ph4), (see also p. 66). The greater part of this
muscle is inserted into the end of the posterior cornu of the hyoid
(HH); a smaller portion (S, S2) is
prolonged to be inserted into the cricoid cartilage and into the
fibrous lamella into which the MM. hyo-arytenoidei anteriores
are inserted.
(5) The M. hyo-arytenoideus posterior (Fig. 205
C.o.l.1) arises on each side from the superior angle
of the corresponding arytenoid cartilage, under cover of the tendon of
the M. petrohyoideus tertius. The muscle is inserted into the
inferior angle of the arytenoid cartilage.
d. The interior of the larynx
(Figs. 202, 206, 207). The cavity of the larynx is constricted at two
points: anteriorly it is constricted by the true vocal cords (Figs. 206
V, 207 SB), posteriorly by the false vocal cords. The
whole cavity is lined with mucous membrane, which is continuous with
that of the mouth anteriorly, with that of the lungs posteriorly.
Fig. 206.
Three sections through the larynx of Rana esculenta.—G. H.
I. Sagittal section near the median plane through the larynx.
II. Oblique transverse section through larynx.
III. Almost horizontal section through larynx.
A
Arytenoid cartilage.
C
Cricoid cartilage.
E
Epiglottis.
F
False vocal cords.
G
Epiglotidean glands.
H
Hyoid.
M
Membranous floor of the larynx, cut obliquely.
O
Opening into root of lung.
P
Pre-arytenoid cartilage.
V
Vocal cord.
(1) The true vocal cords are two vertical flat bands of
connective-tissue, attached above to the superior angles of the
arytenoid cartilages, below to their inferior angles; their anterior
borders are thin and free; near their posterior borders they are
attached by mucous membrane to the internal surfaces of the arytenoid
cartilages. The anterior
and posterior borders are not parallel but are each concave (Fig. 202V).
The anterior border is thin, the posterior thick and rounded.
Seen from in front (Fig. 206), the opening between the cords
(Rima glottidis) is slightly wider at each end than in the
middle. The ends of the concave posterior border are prolonged
backwards and enclosed in a fold of mucous membrane. Part of the tissue
enclosed is unstriated muscular fibre, which may be traced to the
cricoid cartilage.
Fig. 207.
The Rima glottidis, seen from the front.
G
Rima glottidis.
SB
Vocal cords.
(2) [The false vocal cords (Figs. 202 and 206 F) are
simply folds of mucous membrane, which extend vertically on each side
of the larynx behind the true vocal cords; they do not extend so far
towards the median plane as do the true vocal cords.]
(3) [The ventricles of the larynx (Figs. 202 and 206) are two
on each side. The anterior ventricles are between the true vocal cords
and the arytenoid cartilages; they are open anteriorly, and closed by
mucous membrane posteriorly.
The posterior ventricles open towards the median plane, each
presenting an oval opening (Fig. 202), which widens outwards into a
large cavity (Fig. 206 II). The cavity is bounded in front by
the base of the true vocal cord, and the mucous membrane attached to
it; posteriorly by the false vocal cord, and externally by the cricoid
cartilage and the connective-tissue capsule of the larynx.]
(4) [The mucous membrane of the larynx varies in structure
in various parts of the organ. From the anterior opening of the
larynx to the posterior borders of the vocal cords it is lined with
stratified epithelium, which is firmly attached to the underlying
structures by a small amount of sub-epithelial tissue. This is especially well marked on the
vocal cords themselves.
Behind the vocal cords the mucous membrane is much more loosely
attached to the surrounding structures by an extremely vascular areolar
tissue. The epithelium is arranged in a single layer of columnar cells,
among which are numerous goblet-cells. In the more external parts of
the posterior ventricles, the mucous membrane is thrown into deep
folds and so forms polygonal acini. In the median line of the floor
of the larynx and behind the false vocal cords is a vertical fold of
mucous membrane, which increases in height and breadth as it proceeds
backwards towards the roots of the lungs. The mucous membrane behind
the true vocal cords is extremely vascular, in the most posterior
portion of the larynx the blood-vessels form a capillary network
exactly like that of the lungs.]
e. [The epiglottis (Fig. 206 E)
is a small bilobed fold of mucous membrane placed on the floor of the
mouth in the median plane and immediately in front of the aperture
to the larynx. Between it and the mucous membrane covering the
arytenoid cartilages are a number of large mucous glands (G).
The epiglottis does not contain cartilage; it is, however, constant
in its appearance and sharply marked off from the surrounding mucous
membrane.]
a.General description. The lungs are two
large thin-walled sacs (Figs. 185 and 204Lg and
Lg1). The roots of the lungs are contracted at their
origin from the larynx and then expand to form two ellipsoid sacs,
which terminate posteriorly in bluntly-pointed ends. With the exception
of their roots they lie entirely free in the pleuro-peritoneal
cavity, and are covered by the pleuro-peritoneal membrane. In the
recent state they have a bright red colour due to the large supply of
blood-vessels.
b.Minute structure.
(I) The muscular tissue of the lungs is for the most
part arranged in large bands, which form a coarse network on the
deeper surface of the
organ; when seen in section76 (Pl. II, Fig. 208A, B) these
bands are found to be composed of well-developed involuntary muscular
fibres. Between the larger bands are smaller bands having a similar
arrangement. From these networks of muscular bands finer processes of
muscular tissue pass peripherally towards the surface of the organ, and
are attached to the thin and incomplete muscular layer found in the
wall of the lung (C).
(2) The connective-tissue of the lungs is present in only
small quantity, but is still sufficient to fill in the spaces between
the various muscular bands and the surface of the lung, and to invest
the whole of that surface. There is thus formed a series of pits, the
mouths of which open into the general cavity of the lung, while their
bases are at the surface. Through this connective-tissue course the
blood-vessels, nerves, and lymphatics. It contains numerous yellow
elastic fibres.
(3) The blood-vessels of the lungs. The pulmonary artery
courses along the outer surface of the lung to the apex, giving off, at
right angles, lateral branches in the whole of its course; these show
a tendency to be alternately larger and smaller. The lateral branches
divide and form a rich capillary network (T. Hoffmann).
The capillary network has very small meshes; the diameter of a given
mesh being frequently less than that of the capillary bounding it. The
meshes are rounded or polygonal in shape.
The pulmonary vein arises by lateral branches from this capillary
network; the branches join, at right angles, the main vein, which
courses from the apex of the lung along its inner surface to the root
of the organ.
(4) The epithelium of the lungs. Externally the lungs are
covered with a layer of endothelium derived from the peritoneum.
Internally the surface is covered with an epithelium which varies
considerably in different positions.
On the free borders of the muscular trabeculae forming the borders
of the alveoli is a short columnar ciliated epithelium (Fig. 208)
such epithelium is also found in the root of the lung; it contains
goblet-cells.
The alveoli, for the most part, are lined with a single layer of
tesselated epithelium; the cells are polygonal in outline, with finely
granular contents and a distinct nucleus: the average diameter of the
cells is from 0.0074 to 0.0108 mm., that of the nucleus 0.0054 mm.,
that of the nucleolus 0.0009 mm.; four to eight of such cells occupy
the space enclosed by one mesh of the capillary network (Eberth).
The epithelium rests on a structureless basement membrane, which
is continuous over the whole inner surface of the lung, whereas the
epithelium does not pass over the capillaries, and is therefore only
found in isolated patches in the areas enclosed by the capillaries
(Eberth).
In various isolated spots, small groups of short columnar or
goblet-cells are found in the tesselated epithelium (Eberth,
Hoffmann).
(5) [The lymphatics of the lungs have been described by
T. Hoffmann; they form a network of vessels surrounding the larger
blood-vessels: from this branches are given off, which form a network
of fine canals through the whole of the lung; part of this secondary
network accompanies the blood-capillaries, but other portions run a
separate course. They communicate with the pleuro-peritoneal cavity.
(6) The pigment-cells are very numerous, branched, and
large; they accompany the lymphatics, and not the blood-vessels (T.
Hoffmann).
(7) The nerves of the lungs (p. 172) course along the
larger blood-vessels, under the serous coat; the fibres are chiefly
medullated fibres (Egorow, Kandarazki). Non-medullated branches, which
form a plexus in each alveolus, are given off. The branches have small
triangular enlargements (ganglia), where they unite. The nerves are
accompanied by nerve-cells, which occur either singly or in groups.
Egorow describes the nerves as being distributed in three networks:
one for the mucous membrane and muscular trabeculae; a second for the
superficial muscular layer; and a third for the serous membrane.]
Fig. 209.
Dissection to show the vocal sac of the
right side.
HH
Larger posterior cornua of the hyoid.
HH1
Smaller posterior cornua of the hyoid.
My
Mylo-hyoid muscle.
My1
Mylo-hyoid muscle continued on to the vocal sac.
Thy
Thyroid glands.
VH
Anterior cornua of the hyoid.
Z
Body of the hyoid.
a.General description. The vocal sacs are a pair of
sacs which open in the floor of the mouth (Fig. 179S); they are
found only in the males. When the animal croaks these sacs are dilated
and act as resonators; when so dilated the sacs force up the skin
under the angle of the mouth and tympanic membrane. In well-developed
specimens they are about as large as an average sized cherry. The skin
covering the sacs is extremely elastic, but is not directly attached to
the sacs.
b.Minute structure. The sac consists of
connective-tissue, with a large proportion of yellow elastic fibre.
Internally it is lined with a flattened epithelium, and externally
is covered with a layer of striated muscular fibre, derived from the
mylo-hyoid muscle (Fig. 209 My, My1).
Fig. 210.
Dissection to show relations of the thymus gland.
De.
M. deltoideus.
D.m.
M. depressor mandibulae.
L.d.
M. latissimus dorsi.
St
M. sternocleidomastoideus.
Tf
Tympanic membrane.
Th
Thymus gland.
a.General description. The thymus gland (Fig. 210
Th) is placed on each side behind the angle of the jaw; it
is best exposed by removing the skin behind the tympanic membrane
and the angle of the jaw, and then reflecting the M. depressor
mandibulae (D.m.). The gland is then found as an elongated,
oval body, not quite 3 mm. long, lying in the space between the M.
depressor mandibulae and the M. sternocleidomastoideus
(St); it extends slightly beyond the posterior border of the
former muscle. The space also includes connective-tissue, fat, and
numerous vessels.
In Rana temporaria this gland is spherical, much smaller,
and placed further behind on the M. sternocleidomastoideus,
between the M. latissimus dorsi and the M. deltoideus
(Wiedersheim).
b.Minute structure (Fig. 211).
[The gland is surrounded by a connective capsule, which is indented
on the inner surface to form a hilus through which blood-vessels course
into the organ.
The capsule sends in numerous fine trabeculae, which form a
connective-tissue skeleton such as is found in all lymphatic glands.
The corpuscles of the trabeculae possess elongated nuclei from 0.019 to
0.028 mm. in length, and 0.010 to 0.015 mm. in breadth (Tolldt). The
trabeculae support a network of blood-vessels.
The meshes of this sustentacular tissue are filled with
cells; these are:
(α) Lymphoid cells, rounded or oval, possessing a round nucleus and
nucleolus, and an extremely small amount of adhering protoplasm; the
size of the nucleus is from 0.011 to 0.015 mm. (Tolldt).
Fig. 211.
From various sections from the thymus gland of Rana esculenta.—G. H.
I. Complete gland (Hartnack, Oc. I, Syst. 3).
a
Pigment-cells.
II. Portion of a section (Hartnack, Oc. I, Syst. 7) showing small corpuscles of Hassall.
III. Portion of a section showing lobules with degenerating cells.
a
Capsule of lobe.
b
Lobules.
c
Large corpuscle of Hassall, surrounded by normal tissue.
IV. Nerve-cell? (corpuscle of Hassall), after Fleischl.
(β) Corpuscles of Hassall (Fig. 211 II, III, and IV) are, as a
rule, large bodies, but are subject to much variation in size. Their
general appearance is seen in Fig. 211 III; they show a concentric
striation and usually enclose one or more smaller cells. They
therefore closely resemble similar corpuscles found in higher
animals.
(γ) In many frogs the cellular structure of at least a part of
the gland seems to have undergone a degenerative stage (III). In
such cases the connective-tissue is increased in quantity, and marks
off portions of the section into small lobules (III) which are
filled with cells containing mucus or sometimes fat (III). Under
what conditions this degeneration, if such it be, takes place has
not yet been determined77.
(δ) Large branched pigment-cells are found in the course of the
larger blood-vessels.
(ε) Watney describes also four varieties of ‘granular cells:’
1. polygonal or rounded; 2. vacuolated; 3. spheroidal masses;
4. club-shaped masses attached to the blood-vessels. I have, however,
not been able to distinguish them.]
[Tolldt (l. c. 1868) described the lymphoid tissue and the blood-vessels of this gland
but did not find the corpuscles of Hassall.
Fleischl (l. c. 1870) disputed Tolldt’s description; he evidently found the corpuscles
of Hassall (see Fig. 211 IV), but he held them to be nerve-cells, and described them
as such. He was also of opinion that the blood-vessels open into the intercellular
spaces (as in the spleen). This has not been found to be the case by any other
observer. Watney (l. c. 1882) first described the concentric corpuscles of Hassall
as such.
Most writers describe the parenchyma as arranged in lobules. This I have only
seen in a part of the gland and under what I believe to be pathological conditions.]
Fig. 212.
Minute structure of the thyroid gland of Rana
esculenta.—G. H.
I. Section through the gland (Hartnack, Oc. I, Syst. 3).
II. Small portion of above (Hartnack, Oc. I, Syst. 7).
a
Epithelium lining the vesicles.
b
Mucus.
c
Blood-vessels, injected with blue mass.
a.General description. A thyroid gland (Fig. 209Thy) is found on either side as a small, triangular, or
oval, reddish-coloured body on the dorsal surface of the M.
sternohyoideus, just before it passes between the MM.
genio-hyoidei. It lies in the angle formed between the
larger and smaller posterior cornua of the hyoid (HH,
HH1). It is easily found by the presence of a
large number of vessels in its neighbourhood, and especially by the
large jugular vein, to the ventral surface of which it is intimately
attached.
Not uncommonly several smaller supplemental glands are found in the
rich anastomosis surrounding the organ.
The dorsal surface of the gland is lobulated, the ventral
surface flatter and convex. The glands of opposite sides are seldom
symmetrical.
b.Minute structure (Fig. 212 I and II). [The gland
possesses a connective-tissue capsule, which sends in trabeculae to
support the vesicles of which the gland is composed.
The vesicles (I and II), which vary greatly in size, are closed
cavities, usually of a rounded or oval form, but sometimes branched
(Baber). Each vesicle is lined with a single layer of cubical or
slightly columnar epithelium (II, a), which rests on a delicate
basement-membrane of connective-tissue, placed between the epithelium
and the surrounding lymphatics (Baber).
Zeiss describes a delicate reticulum between the epithelial
cells.
The vesicles always contain mucus (b), and are surrounded by
a fine anastomosis of blood-vessels (c).]
Fig. 213.
Part of section through the lymphatic gland
(tonsil?) of Rana esculenta (Hartnack, Oc. I,
Syst. 13).—G. H.
a
Extremely large lymphoid follicle.
a. [General description. These are two oval,
reddish-coloured, soft lymphatic glands, placed one on each side of the
larynx. Frequently they are divided into two or three lobes by more
or less deep fissures.
They are constant in their occurrence, and are frequently supplemented
by one or more smaller glands; each gland has the larynx on its inner
side, the Vena jugularis externally, the M. omohyoideus
in front, and above the mucous membrane of the pharynx (Tolldt).
b.Minute structure. The glands consist of dense
lymphoid tissue (Fig. 213), but possess in addition one or more large
bodies (a) which resemble lymphoid follicles in structure. Each
is composed of a dense mass of small cells; and the whole follicle is,
as in similar follicles of higher animals, sharply differentiated from
the rest of the organ.
The glands possess an extremely rich vascular supply, and are
frequently pierced by one or more large arterial trunks.
The mucous membrane covering the glands is thinner than that
immediately around, but is not perforated.]
[As far as I am aware, Tolldt is the only observer who describes
these glands; he makes no mention of the lymphoid follicles.]
SECTION VII. THE URINO-GENITAL SYSTEM, THE ADRENALS, AND THE FAT-BODIES.
THE URINO-GENITAL
SYSTEM, ETC.
LITERATURE.
THE URINO-GENITAL ORGANS.
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Beale, L. S., On very fine nerve-fibres ramifying in certain
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Hyrtl, Ueber die Injection der Wirbelthierniere, etc. Wiener
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Jensen, O. S., Recherches sur la spermatogénèse. Archives de
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THE ADRENALS.
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den vier Wirbel-thierklassen. Braunschweig, 1846.
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THE FAT-BODIES.
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fat-bodies as suprarenals).
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreichs. Heidelberg und Leipzig, 1873–1878. Vol. VI.
Marshall, A. Milnes, The frog. Manchester and London,
1884.
v. Wittich, W., Beiträge zur morphologischen und
histologischen Entwicklung der Harn- und Geschlechtswerkzeuge der
nackten Amphibien. Zeitsch. f. wiss. Zool. 1853. Vol. IV, p. 152.
THE URINO-GENITAL SYSTEM, THE ADRENALS, ETC. — THE URINO-GENITAL SYSTEM. — I. THE URINARY ORGANS. — II. THE REPRODUCTIVE ORGANS. — III. THE ADRENALS. — IV. THE FAT-BODIES.
Fig. 214.
The male urino-genital organs.
Ao
Aorta.
Cl
Cloaca.
Cv
Inferior vena cava.
FK
Fat-body.
H
Testis.
N
Kidney.
S, S1
Openings of ureters.
Ur
Ureter.
Vr
Renal veins.
†
Appearance of ureters on the ventral surfaces of kidneys.
By cutting through the meso-rectum the posterior caval vein is seen,
as a large vessel, arising by numerous transverse branches from the
ventral surfaces of the kidneys and testes (Fig. 214 Cv), lying
in the median line between the kidneys; by drawing it to one side the
dorsal aorta is brought into view (Fig. 214 Ao). The testes are
placed on the ventral surface of the kidneys, and together with the
fat-bodies conceal the anterior portions of these organs. The posterior
portions of the kidneys are covered by peritoneum only, and may by seen
without further dissection. The kidneys lie dorsal to the peritoneum,
and have this membrane on their ventral surfaces only; their dorsal
surfaces are in contact with the lumbo-sacral plexus.
The ureters extend from the anterior border of the eighth vertebra
to the middle of the urostyle, where they terminate by two orifices in
the dorsal wall of the cloaca (Fig. 184).
The testes are entirely surrounded by peritoneum, except a small
part (Hilus) of the inner surface, where the vessels and ducts
enter.
The urino-genital organs are arranged in the same manner in the
two sexes; the ovaries corresponding in position with the testes (Fig. 214), that is,
they are bilaterally symmetrical, and placed on the ventral surfaces of
the kidneys.
The oviducts (Fig. 224Ov) lie externally to the kidneys and
ovaries, and course through the whole length of the trunk from the
roots of the lungs to the cloaca. The size of the ovaries and oviducts
varies very greatly according to the season of the year; at times, the
kidneys may be entirely hidden by them.
A. The kidneys.
a.General description. Each kidney (Fig. 215) is a
reddish-brown, elongated organ, almost semilunar in shape; the inner
border being straight and the outer convex. The organ is flattened from
above downwards, and decreases in thickness towards either end. In
animals of average size the kidney is about 16 mm. long, and from 6 to
7 mm. broad. The kidneys lie parallel to the vertebrae.
Fig. 215.
The right kidney, seen from the ventral surface.
The outer border is smooth and even, except at its posterior third,
where a slight depression for the ureter exists; the inner border has
usually two or three well-marked notches, the hindermost of which is
the deepest (Fig. 215). Each notch is continued outwards as a groove,
traversing the whole breadth of the ventral surface and containing a
branch of the renal portal vein. The ventral surface is, as a whole,
slightly concave, grooved, and lobulated; the dorsal surface is smooth
and slightly convex.
b. [Minute structure. The kidney is enclosed in a
thin capsule of fibrous tissue (Fig. 220Bg), which sends
in fine trabeculae to support the glandular structures and the
blood-vessels.]
(1) The blood-vessels of the kidney are the renal veins, the
renal arteries, and the renal portal vein.
α. The renal portal vein (p. 247) courses along the outer border of
the posterior part of the kidney, and then along the outer margin of
the dorsal surface; in this course it gives off large branches, which
course inwards and forwards and supply numerous lateral twigs. These
anastomose to form a network of vessels on the dorsal surface of the
organ, from which very numerous large branches course downwards and
somewhat inwards to join corresponding branches of the renal veins
(Fig. 216 I).
Fig. 216.
The blood-vessels and lymphatics of the kidney.—G. H.
I. Transverse vertical section through kidney. Venous system blue; arteries red (Hartnack,
Oc. I, Syst. 3).
II. Part of a horizontal section through kidney. Venous system blue; arteries red (Hartnack,
Oc. I, Syst. 3).
III. Part of a transverse vertical section through kidney; lymphatics blue (Hartnack, Oc. I, Syst. 7).
A
Ventral surface.
B
Dorsal surface.
C
Two arterial twigs uniting before entering the Malpighian body.
β. The renal veins (p. 247) form a coarse plexus on the ventral
surface of the kidney, from this numerous large branches (Fig. 216 I)
course upwards and outwards.
The venous system between the renal portal veins on the dorsal
surface, and the renal veins on the ventral surface, are so large that
they can scarcely be named capillaries (Hyrtl).
γ. The renal arteries (p. 233) are distributed to the ventral
surface of the kidney; their mode of distribution varies in different
parts of the organ. A simple arrangement is that shown in Fig. 216
I, where a branch traverses the breadth of the kidney and gives off
branches to the Malpighian corpuscles; in one case (C) I have seen two twigs passing
to the same corpuscle; as a rule, however, each Malpighian corpuscle
receives only one twig. A more general arrangement is that the artery
courses nearer the ventral surface and in a more winding course,
several twigs are then given off close together, from the convex
surface of one of the curves, and these course to their respective
corpuscles.
In the Malpighian corpuscle the arterial twig forms a series of
loops and then passes out to open abruptly into one of the branches of
the neighbouring venous anastomosis (Hyrtl).
(2) [The Malpighian corpuscles and their capsules
(Figs. 216 I, 218 III). The corpuscles lie nearer the ventral
than the dorsal surface. They are rounded oval bodies, formed of
loops of an arterial twig, held together by a small amount of
connective-tissue. Each corpuscle is enclosed in a capsule, which it
incompletely fills (Fig. 217)78.
The capsules are formed of connective-tissue and lined with a
flattened epithelium (Fig. 218 III): according to Duncan the fibrous
coat is arranged in two layers (III a). Towards the opening of
the uriniferous tube the epithelium increases in thickness.
According to Hyrtl, the corpuscles are arranged in two layers, a
more superficial one and a deeper one; and are of two sizes, the larger
being as a rule the more superficial (ventral).]
(3) [The uriniferous tubes (Figs. 217 and 218). Each tube
originates at a narrow opening on the dorsal surface of a Malpighian
capsule. The tube gradually widens and is lined with a short rounded
or cubical epithelium (Roth), (Fig. 218 III); each epithelial cell
bearing a small number of extremely small cilia (Bowman, Kölliker,
Duncan, and others). The cilia of the cells nearest the capsule are
directed towards it (Heidenhain), those of the cells further away have
an opposite direction (Spengel). This portion of the tube is known as
the neck; it courses dorsalwards.
The second portion of the tube (Tubulus contortus), (Fig. 218
III, IX, and XII) has a very tortuous course in the dorsal part of
the kidney, and then winds towards the ventral surface. This portion
is lined with columnar epithelium, which has granular contents,
and possesses large distinct nuclei. The cells of this part of the kidney are usually more
or less coloured with a golden-yellow pigment. According to Tornier it
bears short cilia (Fig. 218 XIV).
Fig. 218.
Various preparations to show the structure of the uriniferous tubes, etc.
I.
Three portions of the uriniferous tubes from Rana esculenta, from a natural injection with sulphindigotate of sodium (Hartnack, Oc. I, Syst. 3).—G. H.
II.
From the third part of a uriniferous tube; short
ciliated epithelium, borax-carmine (Hartnack, Oc. I, Syst.
7).—G. H.
III.
A Malpighian corpuscle and capsule; shows the capsule
of two layers at a. After Duncan.
IV.
Part of uriniferous tube after natural injection with
sulphindigotate of sodium (Hartnack, Oc. I, Syst. 3).—G. H.
V.
Transverse section of one of the larger branches
of the ureter, from Rana esculenta (Hartnack, Oc. I, Syst.
7).—G. H.
VI.
Epithelial lining of the ureter itself while still in
the kidney (Hartnack, Oc. I, Syst. 7).—G. H.
VII.
Portion of a uriniferous collecting-tube from section
in Fig. 217 I, stained with silver (Hartnack,
Oc. I, Syst. 7).—G. H.
VIII.
Renal epithelium; a to b, tubulus
contortus; b to c, third portion of uriniferous tube;
c to d, fourth portion of tube. After Heidenhain
(enlarged 210 times).
IX.
Ciliated cells of the neck, after Duncan.
X.
Isolated rod-cells of Triton taeniatus, after Heidenhain.
XI.
Isolated rod-cells, after Heidenhain (enlarged 300 times).
XII.
Isolated cells of the neck, after Heidenhain (enlarged 210 times).
XIII.
Portion of the fourth part of a uriniferous tube, after
Heidenhain (enlarged 300 times).
XIV.
Ciliated epithelium of tubulus contortus, after Tornier
(magnified 550 times).
XV.
From kidney of Rana temporaria, after Spengel.
a
Uriniferous tube opening into seminiferous duct.
b
Dilated seminiferous duct cut longitudinally.
c
Vas efferens cut transversely.
The third portion corresponds with the narrow limb of Henle’s loop;
it is lined with ciliated epithelium (Fig. 218 VIII, b to
c), similar to that in the neck of the tube.
The fourth portion (Fig. 218 VIII, c to d, and XIII)
represents the wider limb of Henle’s loop. It has a winding course
in the ventral part of the kidney, and then ascends dorsally to open
into a collecting-tube. The fourth part of the tube is lined with a
short, columnar epithelium (Fig. 218 VIII, c to d), which
has a clear, cuticular, free border, large nucleus, and a peculiar
arrangement of the protoplasm, which shows a rod-like structure
(Fig. 218 XI).
The collecting-tubes course transversely near the dorsal surface
of the kidney (Fig. 217), and the uriniferous tubes meet them at
right-angles. They are lined with a short polygonal epithelium
(Fig. 218 VII).
The peritoneal funnels of the kidney (nephrostomes). Spengel,
Meyer, and Hoffmann describe these funnels as existing in the frog;
according to them they open on the ventral surface by narrow apertures,
and each is connected, by a vertical tubule, with the fourth part of
the uriniferous tube (Spengel), but according to Nussbaum, with the
neck of the tube. According to Spengel and Meyer the number of these
funnels is in Rana from 250 to 360.
According to Wiedersheim the funnels hang free from the ventral
surface like so many parasites attached by fine filaments, and do
not open on the surface.
Heidenhain (Arch. f. mik. Anat., Vol. X) was unable to find these
organs.
Being unable to find any trace of these organs in the kidneys of
either R. temporaria or R. esculenta, in microscopic sections or in
teased preparations, I inserted canulae into the ureters of both male
and female specimens of both species, and injected the uriniferous
tubes with a solution of Berlin blue. Although the tubules were, in
some cases, completely injected, in no case could I find any trace
of a peritoneal funnel, nor was there any escape of the solution
from the kidney as would be the case if the funnels were open and
communicated with any part of the uriniferous tubes. Even when the
pressure was increased to the extent of a column of 25 cm. high of the
injection-mass, no escape took place from the surface of the kidney,
though in numerous cases the uriniferous tubes were ruptured by the
abnormally high pressure.
Properly dissected frogs were placed in 0.6% sodium chloride
solution, in which finely divided gamboge was suspended. No trace
of ciliary action was, in any case, found on either surface of the
kidneys.
One may therefore conclude that if the peritoneal funnels exist in
the adult frog (1) they are very difficult to find; (2) they do not
form a free communicating path between any part of the uriniferous
tubes and the abdominal cavity; (3) their superficial terminations
have no free cilia. As before stated I have found no trace of any such
organs.
The lobules of the kidney. When treated with proper reagents
the kidney shows a marked tendency to separate into lobules (Fig. 219
I).
The lymphatics of the kidney (Fig. 216 III79) form
an irregular network of fine canals with elongated meshes. They run
chiefly in the direction of the blood-vessels. The large vessels, which
supply the kidney, are surrounded by large lymphatics.]
The nerves of the kidney (Fig. 219 II79). Little is
known of these. Nerve-fibres have been traced alongside the larger
blood-vessel through the greater part of the kidney.
B. The ureters.
a.General description. In the males the ureters are,
at the same time, the seminiferous ducts. Each ureter commences on
the dorsal surface of the kidney by bifurcating branches, which are
continuous with the collecting-tubes of the kidney. In the anterior
two-thirds of the kidney the ureter is wholly on the dorsal surface;
at the junction of the middle and posterior thirds it winds round to
the outer border of the kidney (Fig. 214Ur), and there lies
in a groove accompanied by the renal portal vein (Fig. 220 Ur
and Va), the two organs being intimately attached to the kidney
substance and enclosed by the fibrous capsule (Bg).
C. The bladder.
Fig. 220.
Transverse section of the kidney, enlarged.
Bg
Connective-tissue capsule.
D
Dorsal surface.
NC
Renal parenchyma.
Ur
Ureter.
V
Ventral surface.
Va
Renal portal vein.
This portion of the ureter possesses a spindle-shaped enlargement,
which represents the Receptaculum seminis. In Rana
temporaria the Receptaculum seminis forms a large saccular
dilatation.
In its further course the ureter runs backwards and slightly
inwards, converging with its fellow of the opposite side; the ureters
lie free in the abdominal cavity, and terminate by two openings placed
side by side in a groove on the dorsal wall of the cloaca (Fig. 214S, S1).
In females the ureters are intimately attached to the dilated
oviduct, immediately after leaving the kidney; they pursue a similar
course to those of the males, but are attached to the oviduct in the
whole of their course to the cloaca.
b. Minute structure. The ureter is a tube composed of
connective-tissue and
involuntary muscular fibre, and lined with a mucous membrane. The
mucous membrane is thrown into longitudinal folds, and consists, in
the larger tubes, of two or three layers of epithelium (Fig. 218 V),
that on the free surface is columnar; the deeper cells being rounded or
polygonal. The larger branches of the ureter are lined with columnar
epithelium (Fig. 218 VI), with small intervening cells. In some parts
of the branches the columnar epithelium bears short cilia.
No glands have been found in the ureter or Receptaculum
seminis; in Rana temporaria, however, the Receptaculum
seminis possesses large, branching mucous glands (Wiedersheim).
a.General description. The urinary bladder (Fig. 185HB) is closely attached to the ventral wall of the cloaca and is
easily distended from that organ. In relation to the animal it is of
very large size; in consequence of its being contracted in the middle
it has two lobes, which may be of unequal size. The organ is somewhat
heart-shaped (Figs. 184 and 185), with the narrow neck attached
to the cloaca, into which it opens by a smaller aperture on the
ventral surface. The aperture is surrounded by a small fold of mucous
membrane.
b. [Minute structure. The urinary bladder is bounded
by a thin, transparent wall, lined internally with mucous membrane, and
covered externally by peritoneum.
(1) The muscular coat is formed of a network of fine bands of
unstriated muscular fibre (Fig. 221); it is supported and completed
by a connective-tissue layer, rich in connective-tissue corpuscles and
yellow elastic fibres.
(2) The peritoneal coat is a single layer of endothelial cells
derived from the peritoneum and resting on a very thin layer of
subperitoneal tissue.
Fig. 221.
Various preparations from the bladder.
I.
Silver preparation of the mucous membrane; seen
from the surface. After List (enlarged 400 times).
a
Cells of the surface.
d
Goblet-cells.
e
Young cells.
II.
Vertical section of the mucous membrane; after
List (enlarged 600 times).
a
Cells of upper layer.
b
Cells of middle layer.
c
Cells of lower layer.
III.
Large multicellular ganglion; after Wolff.
IV.
Vertical section from a silver preparation of the
mucous membrane; after List (enlarged 600 times).
a
Upper layer.
b
Middle layer.
c
Lower layer.
d
Goblet-cells.
V.
Small ganglion of bladder; after Wolff.
a
Non-medullated nerve-fibre leading to ganglion.
b
Process of a ganglion cell.
(3) The mucous coat is formed of epithelium resting on a layer
of loose, areolar tissue. The epithelium (Fig. 221 I, II, and IV)
is arranged in three layers: the cells of the uppermost (II and IV,
a) always present a flat or convex border to the cavity of
the organ; seen from their free surfaces (I) they have polygonal
outlines intermixed with round apertures belonging to goblet-cells, the
remaining surfaces of these cells are serrated. The cells of the middle
layer (II and IV, b) are polygonal in outline, they are not so
tall as the cells of the layer above; all their borders are serrated.
The cells of the deepest layer (II and IV, c) are more or less
pointed above where they project between the cells of the second layer;
their lowest surfaces are flattened towards the subepithelial tissue,
and all their surfaces are serrated.
The cells of all three layers possess a cell-wall, and finely
granular contents, and each cell has a large oval nucleus (List).
The goblet-cells (Fig. 221 I and IV, d) vary very much in
shape; they are always more or less rounded in outline: they vary
greatly in size (from 190 µ to 54 µ in length); some possess ‘feet’
or basal prolongations, in others these are absent. They usually open
freely by rounded apertures on the surface of the mucous membrane, but
are sometimes closed. The nucleus is placed towards the base of the
cell and surrounded by a smaller or larger amount of protoplasm. These
cells usually extend into the middle layer of the epithelium, and they
probably constitute unicellular mucous glands (List).
(4) The blood-vessels of the urinary bladder (p. 235) are
very numerous and run in very tortuous courses; they are accompanied by
large lymphatics and by nerves.
(5) The nerves of the urinary bladder (p. 191) are of both
medullated and non-medullated fibres, which course together towards
their points of distribution; the non-medullated fibres are, however,
much more frequent than the medullated fibres (Wolff).
The non-medullated nerve-fibres stand in close relation with the
nerve-ganglia of the bladder. These ganglia may be unicellular, or
composed of groups of nerve-cells; the cells vary considerably in
shape, round, oval, triangular, and other forms being equally frequent
in their occurrence; to some extent the form appears to depend upon the
number and position of the processes of the cells. The diameter of the
cells varies from 0.05 mm. to 0.1 mm.; the nucleus has a diameter of
0.025 mm., that of the nucleolus measures 0.005 mm. (Wolff).
The cells may be unipolar or multipolar; the former are however
rare. The processes of these cells supply the muscle-fibres (Fig. 221
V, a), and other non-medullated processes connect the cells with
the nerves (V, b (Wolff)).
The number of muscular fibres is far in excess of the number of the
fibres of distribution of the ganglia; Wolff hence concludes that the
nervous impulse may pass from one muscle-fibre to another.]
A. The male reproductive organs are the testes
and their ducts.
a.General description. The relations of the testes
have already been given (p. 234); the organs vary much in shape and
size in different individuals and with the different seasons; when
greatest they are spherical, or of a rounded oval form, occasionally
cone-shaped or pear-shaped. The surface of the testes is not smooth,
but presents a series of convexities, each corresponding to a lobule of
the gland. At the hilus on the inner border the vessels pass to
and from the organ, and the Vasa efferentia leave the testis.
Fig. 222.
The male reproductive organs (enlarged).
CC
Vasa efferentia within the kidney.
H
Testis.
LL
Collecting-tube at inner border of kidney.
N
Kidney.
Ne
Vasa efferentia within the mesorchium.
Ur
Ureter.
†
Vasa efferentia ending blindly.
The number of Vasa efferentia (Fig. 222 I and II) is subject
to considerable variation, not only in different animals, but on the
two sides of the same animal. In some cases these ducts form a network
(I), in other cases this is absent (II); usually the ducts bifurcate at acute angles,
just before entering the kidney. Most of the tubes so formed open into
the collecting-tube; a few, however, end blindly in the mesorchium
(I, †). The course of the Vasa efferentia from the testis is
first inwards, within the mesorchium; on reaching the kidney they
curve dorsalwards between that organ and the corresponding testis:
the ducts then travel in the ventral surface of the kidney towards
its inner border, where they open into a longitudinal canal (Bidder),
(Fig. 222 I, L). Just before their terminations each duct has an
enlargement (I, C), the exact import of which is unknown (see
also Fig. 218 XV).
Fig. 223.
Various preparations from the testis.
I.
Various stages of the spermatozoa; from testis of Rana temporaria. After Neumann.
II.
Section from testis of Rana esculenta (Hartnack, Oc. I, Syst. 7).—G. H.
a
Thin connective-tissue capsule.
b
Trabeculae.
c and d Seminiferous tubes.
III.
From testis of Rana temporaria. After Neumann.
x
Rounded epithelium of seminiferous tubes.
y
Spermatoblasts.
IV.
Surface view of seminiferous tube of Rana temporaria. After Neumann.
a
Granular protoplasmic feet of spermatoblasts.
b
Rounded epithelium.
The collecting-tubes open into the ureter at the hinder extremity
of the kidney.
b. [Minute structure. The testis possesses a thin
connective-tissue capsule underneath its peritoneal covering (Fig. 223
II, a); this sends in trabeculae (b) towards the centre
of the organ, and so encloses the separate lobules. Each seminiferous
tube arises from an elongated irregular sinus placed towards the middle
of the organ; the tubes (c) are slightly convoluted in their
course towards the periphery, near which they branch (Spengel). The
tubes are from 0.16 mm. to 0.12 mm. in diameter (Kölliker), and are
lined with two kinds of cells (Fig. 222 III); the cells (x)
nearer the periphery are rounded and have large rounded nuclei, the
diameters of which vary from 0.013 to 0.02 mm.; these again possess
large and distinct nucleoli. The other cells (y) are of
elongated, spindle-shaped form; and have oval nuclei, with an average
length of 0.016 mm. and an average breadth of 0.005 mm. (Neumann).
The rounded cells lie in groups which vary in thickness and
arrangement, and are often compressed so as to have polygonal outlines.
The spindle cells are arranged so as to radiate from the lumen of the
tube to the periphery, at an angle which varies from 45 to 90 degrees;
these are the spermatoblasts.
The various changes which the spermatoblasts undergo in the
formation of spermatozoa will easily be understood by reference to
Fig. 223 I, a to k, where i and k represent
the fully developed spermatozoa. These have three parts, head, middle
part, and tail, the respective lengths of which in the two species are,
according to Neumann, the following:—
Head.
Middle part.
Tail.
Rana esculenta
0.0140
mm.
0.0025
mm.
0.040
mm.
Rana temporaria
0.0066
"
0.0330
"
0.045
"
At the hilus of the testis the rounded cells of the seminiferous
tubes are gradually modified to form short cylindrical cells (0.01 mm.
long and 0.006 mm. broad), the spindle cells being absent (Neumann).
The Vasa efferentia are also lined with a similar columnar
epithelium (Spengel).]
B. The female reproductive organs.
The position of these organs has already been given (p. 335).
I. The ovaries.
a.General description.
Fig. 224.
The female reproductive organs; the ovary of the right
side has been removed.
N
Kidney.
O.T.
Opening of the oviduct into pleuro-peritoneal cavity.
Ov
Oviduct.
Ova
Ovary.
P
Opening of oviduct into the cloaca.
S, S1
Openings of the ureters.
Ut
Dilated hinder portion of the oviduct.
†
Groove in which ureters lie.
*
Fold in groove separating the openings of the ureters.
Each sac-like ovary (Fig. 224) is subdivided by thin-walled septa
into numerous complete chambers, to the
inner walls of which the ova are attached. The walls of adjacent
sacs are intimately attached to each other, and the subdivision
corresponds with the external lobulated appearance of the organ.
According to Spengel the number of lobules is about fifteen (Rathke
nine to thirteen, Brandt nine). Whether this segmentation of the ovary
corresponds with the segmentation of the body has not been determined
(Spengel). No part corresponding with Bidder’s organ has been found in
Rana esculenta.
During the breeding season the ovaries undergo an extraordinary
increase in size so as to occupy the greater part of the body-cavity
and to displace the other viscera. The ovaries are entirely surrounded
by peritoneum.
b.Minute structure. [The layer of peritoneum covering
the ovary possesses cilia (Thiry), the ciliated cells being arranged in
isolated patches (Schweigger-Seidel, Waldeyer) on the ventral surface
of the organ, and on the mesovarium; these patches are sometimes united by very fine connecting
lines of ciliated epithelium; the ciliated epithelium is always sharply
marked off from that surrounding it (Kolessnikow). Under the peritoneum
is a thin layer of connective-tissue, which is prolonged inwards to
form the septa above-described. To these septa are attached the ova.
Between the connective-tissue layer and the peritoneum are isolated
patches of germinal epithelium (Fig. 225 IV); these are easily
distinguished, by the rounded outlines of their cells, from the
surrounding epithelial cells (Waldeyer, Kolessnikow). These patches
of germinal epithelium measure from 0.093–0.186 mm. in diameter; the
germinal cells average 0.0139–0.0232 mm. in diameter (Kolessnikow).
The patches are most numerous on the outer surface of the ovary, and
particularly so near the mesovarium.
The follicles contained in the ovary have a connective-tissue coat
developed in a manner similar to that of higher animals; the primordial
ova which they contain have large nuclei (0.0325 mm.). The epithelium
of the follicles has an average diameter of 0.0232–0.0325 mm.
(Kolessnikow).
Schultze’s description of the ovaries (l. c.) varies
considerably from that of Waldeyer and Kolessnikow. Briefly he
describes the ovaries as a series of sacs separated by and lined
externally and internally by endothelium; between these two layers are
found the germinal epithelium and follicles: the structures being held
together by an extremely minute quantity of connective-tissue.]
II. The oviducts.
a.General description. In young animals the oviducts
are quite straight, thin-walled, and of small calibre. During the
breeding season, however, they undergo an immense increase in size, and
become much convoluted; in this state they are forced in between the
other abdominal viscera, and usually cover the whole of the kidneys,
and sometimes even part of the ovaries (Fig. 224Ov).
The openings of the oviducts into the pleuro-peritoneal cavity
(p. 304) are semilunar slits, directed inwards and lined with ciliated
epithelium (p. 306).
Immediately behind this opening (Ostium abdominale) the
oviduct is contracted, and is there narrower than in the rest of its
length; beyond this it expands, and then retains an even size nearly to
its hinder extremity, where it suddenly expands (Fig. 224Ut).
This dilatation gradually diminishes in size as it proceeds backwards
towards the cloaca, into which each tube opens on a small papilla. The
dilated portions of the tubes lie close together, but do not communicate with each other; the
opening of the right tube is always slightly behind that of the left
side (Fig. 224P). From the papillae, into which the oviducts
open, a fold of mucous membrane extends backwards on the dorsal surface
of the cloaca to meet its fellow of the opposite side at an acute angle
(Fig. 224 *). The orifices of the ureters are placed within these
folds.
Fig. 225.
Preparations from ovary and oviduct.
I.
Ciliated epithelium and goblet-cells of the oviduct; after Neumann.
II.
Isolated goblet-cells and secretory cells from oviduct; after Neumann.
a, b, c
Goblet-cells.
d, e, f
Secretory cells after treatment with Müller’s fluid.
x
Stoma of secretory cells.
III.
Surface view of the ovary; after Kolessnikow.
a
Peritoneal endothelium.
b
Germinal epithelium.
b.Minute structure.
(1) The tubular portion of the oviduct has three walls: a
peritoneal covering with sub-peritoneal tissue (a); a glandular
layer (b); and an epithelial lining (c). Of these the
glandular layer forms by far the thickest layer, especially during
the breeding season, when it is much increased in thickness. It
consists of long cylindrical glands, often bifurcated at their blind,
peritoneal ends. The epithelial cells, with which they are lined, have
the power of absorbing more than a hundred times their own weight of
water (Boettcher). This layer is absent at the anterior opening of the
oviduct.
The cells have an average diameter of 0.012 mm., the lumen of the
individual glands 0.1 mm. (in spirit-hardened specimens, Neumann).
The cells contain small rounded bodies of very varying size, which
may exist singly, grouped, or even arranged in rows; they swell on
the addition of water. Each cell possesses, in addition, an oval,
granular, distinct nucleus. When treated with Müller’s fluid many
of the secretory cells have the appearances shown in Fig. 225 II,
d, e, f; they each possess an opening (x),
(Neumann).
According to Neumann the great power of absorbing water, which the
oviducts possess, is due to the presence of these bodies, which he
names ‘colloid granules.’ The mucous secretion of these glands passes
into the oviduct and surrounds the eggs on their passage towards the
cloaca: it is due to this secretion that the egg-spawn is so extremely
slippery and difficult to handle.
The inner surface of the oviducts is lined with a ciliated, columnar
epithelium (Fig. 225 I), containing numerous goblet-cells (I and
II).
(2) The dilated portion of the oviduct has much thinner walls
than the anterior, narrower portion; the glands cease abruptly at the
junction of the two parts. The outer coat also contains unstriated
muscular fibre; the inner surface is lined with ciliated epithelium
similar to that of the anterior portion.
The lymphatics of the oviducts form a net with polygonal
meshes on their outer surfaces; from this branches pass inwards in the
spaces between adjacent glands to the inner surface, where a network
with elongated meshes is formed (Langer).
C. [The Cloaca.
a.General description. The cloaca is a short tube
lying beneath the urostyle; anteriorly it receives the openings of the
ureters, rectum, and bladder; and in the female the openings of the
oviducts, in addition: posteriorly it terminates at the anus.
b.Minute structure. The cloaca is lined internally
with a mucous membrane resembling that of the rectum, e.g.
a simple layer of columnar epithelium, which rests on a submucous,
areolar layer.
The outer walls consist of a thick superficial, longitudinal
muscular layer, and a deeper, ill-developed, transverse muscular
layer.
c.Special muscles of the cloaca.
(1) The M. sphincter ani surrounds the end of the cloaca
from the anus to the tip of the urostyle. It consists of striated
muscle.
(2) The M. compressor cloacae arises from the tip of the
urostyle, and is inserted into the hinder end of the rectum; it is also
attached to the symphysis of the iliac bones; from this point a few
fibres pass to the anus (Hoffmann).]
a.General description. The adrenals are small yellow
bodies attached to the renal veins on the ventral surface of the
kidney, towards its outer border.
b. [Minute structure. The superficial layer of the
adrenals consists of solid, rounded, or elongated groups of polygonal
cells, containing numerous fat-granules; these represent the cortical
substance of the corresponding organs of higher animals. The medullary
part is present only in small quantity; it consists of small groups of
polygonal cells, placed between trabeculae of connective-tissue; both
trabeculae and cell-groups are covered with an endothelium. The whole
organ is surrounded by a connective-tissue capsule, which sends in
trabeculae to support the parenchyma (Hoffmann).
No nerves have been traced into these organs (Eberth).]
a.General description. The fat-bodies (Fig. 226) are
bright yellow, lobulated bodies, placed in front of the testes and
ovaries respectively. The greater portion of each organ lies parallel
to the long axis of the body, and from its anterior, posterior, and
external borders are
given off finger-like processes; these may divide dichotomously either
near the base or more peripherally. The external processes are much the
longest, and in the male often conceal the greater part of the testis
(Fig. 226 FK). The organs vary greatly in size with the season
of the year.
Fig. 226.
The male urino-genital organs.
Ao
Aorta.
Cl
Cloaca.
Cv
Inferior vena cava.
FK
Fat-body.
N
Kidney.
S, S1
Openings of ureters.
T
Testis.
Ur
Ureter.
Vr
Renal veins.
†
Appearance of ureters on the ventral surfaces of kidneys.
Fig. 227.
Two preparations from the fat-body of Rana
esculenta80.—G. H.
I.
Section of fat-body, stained with borax-carmine
(Hartnack, Oc. I, Syst. 7).
b
Fat-cells.
c
Adenoid tissue.
II.
Three lobes of fat-body of Rana esculenta;
coarsely injected (Hartnack, Oc. I, Syst. 3).
Arteries striped. Veins shaded.
b. [Minute structure. Each organ is completely
surrounded by peritoneum, under which is a very fine layer of
connective-tissue. The interior of the organ (Fig. 227 I) consists of
large fat-cells with small patches of adenoid tissue interspersed.
The organs are extremely vascular; each lobe has a main artery which
gives off lateral branches: each of these immediately divides to form
two vessels, which run in opposite directions and almost parallel
with the main stem; the vessels then break up into a fine network of
capillaries.]
SECTION VIII. THE SKIN AND THE SENSE-ORGANS.
THE SKIN AND THE
SENSE-ORGANS.
LITERATURE.
I. THE SKIN.
Ascherson, Ueber die Hautdrüsen der Frösche. Arch. f. Anat.
u. Physiol. 1810, p. 15.
Axmann, Beiträge zur mikroskopischen Anatomie und Physiologie
des Ganglien-nervensystems. 1853.
de Betta, Erpétologia delle provincie Venete e del Tirolo
meridionale. 1857.
Biesiadecki, Ueber Basenbildung und Epithelregeneration
an der Schwimmhaut des Frosches. Untersuchungen aus d. Krakauer
path.-anatom. Institut. 1872, pp. 60–84. Abstract in Centralbl. f. d.
med. Wiss. 1873, No. 7, p. 106.
Bimmermann, E. H., Ueber den Einfluss der Nerven auf die
Pigmentzellen des Frosches. Dissert. Strasburg, 1878.
Bimmermann, E. H., Ueber den Einfluss der Nerven auf
die Pigmentzellen des Frosches. Centralbl. f. d. med. Wiss. 1879,
p. 545.
de Blainville, M. H. M. Ducrotay, De l’Organisation des
animaux. Paris, 1822, pp. 142, 225.
Bolaw, Beitrag zur Kenntniss der Amphibienhaut. Göttingen,
1866.
Bruch, Beiträge zur Naturgeschichte und Classification der
nackten Amphibien. Würzburger naturwiss. Zeitsch. 1864. Vol. III.
Brücke, Untersuchungen über den Farbenwechsel des
afrikanischen Chamaeleon. Sitzungsb. der Wiener Acad. 1852. Vol. IV,
p. 196.
Bugnion, Recherches sur les organes sensitifs qui se trouvent
dans l’épiderme du Protée et de l’Axolotl. Dissert. Zürich.
Canini, A., Die Endigungen der Nerven in der Haut des
Froschlarvenschwanzes. Arch. f. Anat. u. Physiol. 1880, pp. 143–153.
Ciaccio, J. V., Intorno alla minuta fabbrica della pella
della Rana esculenta. Palermo, 1866. Giornale di Scienze naturali ed
economiche. Vol. II, pp. 103–158.
Ciaccio, J. V., On the distribution of the nerves to the skin
of the frog, with physiological remarks on the ganglia connected with
the cerebro-spinal nerves. Trans. Micros. Soc. London, 1864. Vol. XII,
pp. 15–31.
Czermak, J. N., Ueber die Hautnerven des Frosches. Arch. f.
Anat. u. Physiol. 1849, p. 252.
Da Collin, Danemarks Froer og Tudser. Naturhist. Tidsskrift.
1870.
Dewitz, Ueber das verschiedene Aussehen der gereizten und
ruhenden Drüsen im Sehenballe des Laubfrosches. Biol. Centralbl. 1883,
p. 558.
Dogiel, Neue Untersuchungen über den pupillenerweiterden
Muskel, etc. Arch. f. mik. Anat. 1886. Vol. XXVII, p. 403.
Duméril et Bibron, Erpétologie générale. 1841.
Vol. VIII.
Eberth, C. J., Untersuchungen zur normalen und path. Anatomie
der Froschhaut. Leipzig, 1869.
Eberth, C. J., Zur Entwickelung der Gewebe im Schwanze der
Froschlarven. Arch. f. mik. Anat. 1866. Vol. II, pp. 490–503.
Eckhard, Ueber den Bau der Hautdrüsen der Kröten und die
Abhängigkeit der Entleerung ihres Secretes vom centralen Nervensystem.
Arch. f. Anat. u. Physiol. 1849.
Ehrmann, S., Ueber Nervenendigungen in den Pigmentzellen der
Froschhaut. Sitzungsb. der Wiener Acad. 1882. Vol. LXXXIV, Pt. III,
pp. 165–170.
Engelmann, T. W., Pflüger’s Arch. f. d. ges. Physiol. 1871,
Vol. IV, p. 321, and 1872, Vol. V, pp. 500–513. (Contractile glands in
skin of frog.)
Harless, E., Ueber die Chromatophoren des Frosches. Zeitsch.
f. wiss. Zool. 1854, Vol. V, p. 372; also in Münchener Gelehrten
Anzeiger, 1853, No. 35.
Harley, G., On the organs of cutaneous respiration;
principally on those of Rana temporaria. Trans. Micros. Soc. London,
1857. Vol. V, p. 148.
Hensche, A., Ueber die Drüsen und glatten Muskeln in der
äusseren Haut von Rana temporaria. Zeitsch. f. wiss. Zool. 1856.
Vol. VII, p. 273.
Henslow, Way in which toads shed their skin. Annals of Nat.
History, 1850, p. 69.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreichs. Leipzig und Heidelberg, 1873–1878. Vol. VI.
Huber, O., Ueber Brustwarzen bei Rana temporaria, L. Zeitsch.
f. wiss. Zool. 1887. Vol. XLV, p. 664.
Huizinga, D., Untersuchungen über die Innervation der Gefäsze
in der Schwimmhaut des Frosches. Pflüger’s Arch. 1875. Vol. XI,
p. 207.
Huxley, T. H., Tegumentary organs. Todd and Bowman’s
Cyclopædia of Anat. and Physiol. p. 500.
Klein, E., On the lymphatic system of the skin and mucous
membranes. Quart. Journ. Micros. Sci. 1881. Vol. XXI, pp. 379–406.
Kölliker, A., Stiftchenzellen in der Epidermis von
Froschlarven. Zoolog. Anzeiger. 1885.
Krause, Handbuch der Gewebelehre. 1862.
Krukenberg, C. F. W., Die Hautfarbstoffe der Amphibien, in
Vergleich. Physiol. Studien, by same author, 1882, pp. 43–49.
Kutschenko, N., Ueber die Krappfärbung der Froschgewebe.
Arch. f. mik. Anat. 1882. Vol. XXVIII, pp. 360–364.
Langer, Ueber das Lymphgefässsystem des Frosches. Wiener
Sitzungsberichte. 1867. Vol. LV, pp. 593–636.
Langerhans, Anat.-hist. Untersuchungen über Fische und
Reptilien. Berlin, 1853. Journal de Medicine. Vol. XI.
Leboucq, H., Recherches sur le développement et la
terminaison des nerfs chez les larves des Batraciens. Bull. de l’acad.
roy. de Belgique. 1876. Vol. XLI, p. 4.
Leydig, F., Histologisch-anatomische Untersuchungen über
Fische und Reptilien. 1853.
Leydig, F., Tastkörperchen und Muskelstruktur. Arch. f. Anat.
u. Physiol. 1856, pp. 150–159.
Leydig, F., Lehrbuch der Histologie. 1857.
Leydig, F., Ueber die Nervenendigung in den sogenannten
Schleimkanälen der Fische und über entsprechende Organe der durch
Kiemen athmenden Amphibien. Arch. f. Anat. u. Physiol. 1861.
Leydig, F., Ueber die Organe eines sechsten Sinnes. Nov. act.
acad. Leop. Carol. 1868. Vol. XXXIV, pp. 1–102.
Leydig, F., Ueber die allgemeinen Bedeckungen der Amphibien.
Arch. f. mik. Anat. 1876. Vol. XII, p. 119.
Leydig, F., Ueber die Schleichenlurche. Zeitsch. f. wiss.
Zool. Vol. XVIII.
Leydig, F., Ueber die Schwanzflosse, Tastkörperchen und
Endorgane der Nerven bei Batrachiern. Arch. f. mik. Anat. 1876.
Vol. XII, pp. 513–527.
Leydig, F., Die anuren Batrachier der deutschen Fauna. Bonn,
1877, p. 123.
Lister, J., On the cutaneous pigmentary system of the frog.
Phil. Trans. 1857. Vol. CXLVIII, p. 627.
Macallum, A. B., The nerve terminations in the cutaneous
epithelium of the tadpole. Quart. Journ. Micros. Sci. 1886. Vol. XXVI,
p. 53.
Mayer, A., Ueber das Epithelium bei den Amphibien. Froriep’s
Notizen, 1839. Vol. IX, coll. 49–51.
Menke, Rana rubita, Linn. Zeitschr. Isis von Oken. 1827.
Vol. XX, p. 172.
Merkel, Ueber die Endigungen der sensiblen Nerven in der Haut
der Wirbelthiere. Rostock, 1880.
Meyer, Ueber die Abhängigkeit der Gefässe und Pigmentzellen
beim Frosch von dem Nerveneinfluss. Virchow’s Arch. 1854. Vol. VI,
p. 581.
Openchowski, T., Histologisches zur Innervation der Drüsen.
Pflüger’s Arch. 1882. Vol. XXVII, pp. 223–232.
Pfitzner, W., Die Epidermis der Amphibien. Morph. Jahrb.
1880. Vol. VI, p. 469.
Rainey, On the structure of the cutaneous follicles of the
toad. Quart. Journ. Micros. Sci. Vol. III, p. 257.
Roesel, Historia natur. rana. nostrat. Nürnberg, 1758, p. 3,
etc.
Rudneff, Ueber die epidermiodale Schicht der Froschhaut.
Arch. f. mik. Anat. 1865. Vol. I, p. 295.
Sattler, E. E., Die Verwendung des Lapisstiftes zur
Untersuchung der Epithelien. Arch. f. mik. Anat. 1882. Vol. XXI,
p. 672.
Schneider, Historia amphibiorum. 1739.
Schultze, F. E., Epithel und Drüsenzellen. Arch. f. mik.
Anat. 1867. Vol. III, p. 145.
Schultze, F. E., Ueber cuticulare Bildungen und Verhornung
von Epithelzellen bei den Wirbelthieren. Arch. f. mik. Anat. 1869.
Vol. V, p. 295.
Schultze, M., Ueber die Nervenendigung in der Netzhaut
des Auges bei Menschen und Thieren. Centralbl. f. med. Wiss. 1869,
p. 885.
Stieda, L., Ueber den Bau der Haut des Frosches. Arch. f.
Anat. u. Physiol. 1865, pp. 52–66.
Stricker, S., and Spina, A., Untersuchungen über die
mechan. Leistungen d. acinösen Drüsen. Wiener med. Jahrb. 1880, p. 355;
und Wiener Sitzungsb. 1880. (Skin and Membrana nictitans.)
Swammerdam, J., Biblia naturae. Vol. II, p. 808.
Szcesny, Beiträge zur Kenntniss der Textur der Froschhaut.
Dissert. inaug. Dorpat, 1867.
Turner, Way in which toads shed their skins. Annals of Nat.
History, 1850, p. 430.
Wagner, R., Handwörterbuch der Physiologie. Vol. III,
p. 389.
Walter, Ueber die Drüsen des Daumenballens des
Froschmännchens. Verhandl. d. naturf. Vereins der pr. Rheinlande und
Westphalen. 1851, p. 351.
v. Wittich, Die grüne Farbe der Haut unserer Frösche, etc.
Arch. f. Anat. u. Physiol. 1854, p. 41.
v. Wittich, Entgegnung auf Herm. Harless’s über die
Chromatophoren des Frosches. Arch. f. Anat. u. Physiol. 1854,
p. 264.
II. SPECIAL ORGANS OF TACTILE SENSATION.
a. The lateral sense-organs.
Beard, J., On the segmental sense-organs of the lateral line
and on the morphology of the vertebrate auditory organs. Zool. Anz.
1884. Vol. VII, p. 162.
Bugnion, E., Recherches sur les organes sensitifs qui se
trouvent dans l’épiderme du Protée et de l’Axolotl. Dissert. inaug.
Zürich. Tire du Boll. No. 7, de la société vaucloise des Sc. nat.
Vol. XII. Lausanne, 1873. Verhandl. d. schweiz. naturforsch. Gesells.
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Froriep, A., Ueber Anlagen von Sinnesorganen am Facialis,
Glossopharyngeus und Vagus. Arch. f. Anat. u. Physiol. 1885.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
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v. Kölliker, A., Ueber neue Sinnesorgane von Froschlarven.
Sitzungsb. Würzburg. 1885, p. 79.
Krause, W., Die Nervenendigung innerhalb der terminal
Körperchen. Arch. f. mik. Anat. 1880. Vol. XIX, pp. 53–137.
Leydig, F., Ueber die Organe eines sechsten Sinnes. Nova acta
Acad. Leopold. Carol. Dresden, 1868. Vol. XXXIV, pp. 1–102.
Leydig, F., Ueber die allgemeinen Bedeckungen der Amphibien.
Arch. f. mik. Anat. 1875. Vol. XII, pp. 513–527.
Leydig, F., Ueber Tastkörperchen und Muskelstructur. Arch. f.
Anat. u. Physiol. 1856, p. 150.
Malbranc, M., Bemerkung betreffend die Sinnesorgane der
Seitenlinie der Amphibien. Centralbl. f. med. Wiss. 1875, p. 5.
Malbranc, M., Von der Seitenlinie und ihren Sinnesorganen bei
Amphibien. Zeitsch. f. wiss. Zool. 1876. Vol. XXVI, pp. 24–86.
Schultze, F. E., Ueber die Nervenendigung in den sogenannten
Schleimkanälen der Fische und über entsprechende Organe der durch
Kiemen athmenden Amphibien. Arch. f. Anat. u. Physiol. 1861, p. 759.
Schultze, F. E., Ueber die Sinnesorgane der Seitenlinie bei
Fischen und Amphibien. Arch. f. mik. Anat. 1870. Vol. VI, p. 62.
b. The touch-corpuscles of Golgi.
Golgi, C., Della terminazione dei nervi nei tendini e di un
nuovo apparato nervoso terminale musculo-tendineo. Atti della Società
Italiana di scienze naturali. Milan, 1879. Vol. XXI; and abstracted in
Centralbl. f. med. Wiss. 1879, p. 725.
Golgi, C., Intorno alla distribuzione e terminazione dei
nervi nei tendini dell’ uomo e di altri vertebrali. Estratto dai
Rendiconti del R. Istituto Lombardo. Serie II. Vol. XI. Fasc. IX.
Milan, 1878. Abstract in Centralbl. f. med. Wiss. 1879. Vol. 41,
p. 725.
Löwe, L., Ueber eine eigenthümliche Art von
Gelenknervenkörperchen beim Frosch. Arch. f. mik. Anat. 1880. Vol. XVI,
p. 613.
III. THE ORGANS OF TASTE.
Beale, L. S., New observations upon the minute anatomy of the
frog’s tongue. Phil. Trans. 1865, p. 443.
Biedermann, W., Ueber morphologische Veränderungen der
Zungendrüsen des Frosches, etc. Wiener acad. Sitzungsb. 1882.
Vol. LXXXVI, Pt. III, p. 67.
Billroth, T., Ueber die Epithelzellen der Froschzunge, etc.
Arch. f. Anat. u. Physiol. 1858, p. 159.
Engelmann, T. W., Ueber die Endigungsweise der
Geschmacksnerven des Frosches. Centralbl. f. med. Wiss. 1867,
p. 785.
Engelmann, T. W., Ueber die Endigungen der Geschmacksnerven
in der Zunge des Frosches. Zeitsch. f. wiss. Zool. 1868. Vol. XVIII,
p. 142.
Engelmann, T. W., Die Geschmacksorgane. Stricker’s Handbuch
der Gewebelehre. 1872.
Fixsen, C., De linguae raninae structura. Dorpat, 1857.
Gottschau, M., Ueber Geschmacksorgane der Wirbelthiere. Biol.
Centralbl. 1882, pp. 240–248.
Hartmann, R., Ueber die Endigungsweise der Nerven in den
Papillae fungiformes der Froschzunge. Arch. f. Anat. u. Physiol. 1863,
p. 634.
Hoyer, Mikroskopische Untersuchungen über die Zunge des
Frosches. Arch. f. Anat. u. Physiol. 1859, p. 481.
Hoyer, Ueber die Epithelzellen der Froschzunge, etc. Arch.
f. Anat. u. Physiol. 1858, p. 163; also in Deutscher Klinik, 1857. No.
21.
Hyrtl, Ueber abwickelbare Gefässknäuel in der Zunge der
Batrachier. Wiener Acad. Sitzungsb. 1863. Vol. XLVIII, Pt. I,
p. 437.
Key, E. A., Ueber die Endigungsweise des Geschmacksnerven in
der Zunge des Frosches. Arch. f. Anat. u. Physiol. 1861, p. 329.
Lépine (On the nerve supply of the glands of the tongue).
Arbeiten aus d. physiol. Anstalt zu Leipzig, 1870, p. 113.
Molin, R., Ueber die Theilung der Nervenprimitivröhren in den
Papillae fungiformes der Froschzunge. Wiener acad. Sitzungsb. 1849.
Vol. III, p. 183.
Schultze, F. E., Die Geschmacksorgane der Froschlarven. Arch.
f. mik. Anat. 1870. Vol. VI, p. 407.
Waller, A., Minute structure of the organ of taste in
vertebrate animals. Proc. Roy. Soc. 1848. Vol. V, p. 751.
Waller, A., Minute structure of the papillae and nerves of
the tongue of the frog and toad. Phil. Trans. 1848. Pt. I, p. 139.
Waller, A., Microscopic examination of some of the principal
tissues of the tongue, etc. Phil. Mag. 1847. Vol. XXX, p. 277.
IV. THE NOSE.
Babuchin, Das Geruchsorgan, in Stricker’s Handbuch der
Gewebelehre. 1872, p. 964.
de Blainville, M. H. M. Ducrotay, L’Organisation des animaux.
Paris, 1822, p. 328.
Blaue, J., Untersuchungen über den Bau der Nasenschleimhaut
bei Fischen und Amphibien, namentlich über Endknorpel als Endapparate
des Nervus olfactorius. Arch. f. mik. Anat. 1884. Vol. XXX,
pp. 231–309. Zool. Anzeiger. Vol. V, pp. 657–680.
Born, G., Ueber die Nasenhöhlen und den Thränennasengang der
Amphibien. Morph. Jahrb. 1875. Vol. II, p. 4.
Born, G., Ueber die Nasenhöhlen und den Thränennasengang der
Amphibien. Breslau. Habilit.-Schrift. 1877.
Born, G., Die Nasenhöhlen und der Thränennasengang der
amnioten Wirbelthiere. Morph. Jahrb. 1879. Vol. V, p. 62. 1882.
Vol. VIII, pp. 188–232.
v. Brunn, Die Membrana limitans olfactoria. Centralbl. f.
med. Wiss. 1874, p. 709.
v. Brunn, Untersuchungen über das Riechepithel. Arch. f. mik.
Anat. 1875. Vol. XI, pp. 468–478.
v. Brunn, Weitere Untersuchungen über das Riechepithel u.
sein Verhalten zum N. olfactorius. Arch. f. mik. Anat. 1880. Vol. XVII,
p. 141.
Cisoff, Zur Kenntniss der Regio olfactoria. Centralbl. f.
med. Wiss. 1874, pp. 689–691.
Cisoff, Zur Frage über die Endigung der Riechnerven beim
Frosche. Arbeiten der naturf. Gesells. an der Universität Kassan. 1879.
Vol. VIII (in Russian).
Clarke, J. Lockhart, Ueber den Bau des Bulbus olfactorius
und der Geruchsschleimhaut. Zeitsch. f. wiss. Zool. 1862. Vol. XI,
p. 31.
Colossanti, Untersuchungen über die Durchschneidung des N.
olfactorius bei Fröschen. Arch. f. Anat. u. Physiol. 1875.
Dogiel, A., Ueber die Drüsen der Nasenschleimhaut, besonders
die Bowmanschen Drüsen. Arch. f. mik. Anat.
Dogiel, A., Ueber den Bau des Geruchsorgans bei Garroirren,
Knochenfischen, und Amphibien. Arch. f. mik. Anat. 1887. Vol. XXIX,
p. 74.
Dogiel, A., Ueber den Bau des Geruchsorgans bei Fischen und
Amphibien. Biol. Centralbl. Vol. I, pp. 428–431.
Dogiel, A., Ueber die Drüsen d. Regio olfactoria. Arch. f.
mik. Anat. 1885. Vol. XXVI, p. 50.
Ecker, E., Bericht über die Verhandl. der Gesellschaft für
Beförd. der Naturw. zu Freiburg, 1855, p. 199; and in Zeitsch. f. wiss.
Zool. 1856, Vol. VIII, p. 303.
Eckhard, C., Beiträge zur Anatomie und Physiologie. Pt. I,
1855, p. 77.
Eckhard, C., Ueber die Endigungsweise der Geruchsnerven.
Beiträge zur Anat. u. Physiol. Giessen, 1882. Vol. I, p. 77.
Exner, S., Untersuchungen über die Riechschleimhaut des
Frosches. Sitzungsb. der Wiener Acad. 1871. Vol. LXIII, Pt. II,
p. 44.
Exner, S., Weitere Studien über die Structur der
Riechschleimhaut bei Wirbelthieren. Sitzungsb. der Wiener Acad. 1872.
Vol. LXV, Pt. III, p. 7.
Exner, S., Fortgesetzte Studien über die Endigungsweise des
Geruchsnerven. Sitzungsb. der Wiener Acad. 1878. Vol. LXXVI, Pt. III,
p. 171.
Gastaldi, Nuove Ricerche sovra la terminazione del nervo
olfatt. Mem. della reale Acad. della scienze di Torino. 1858.
Vol. XVII, Series II, p. 369.
Hoffmann, Lehrbuch der Anatomie der Sinnesorgane.
Hoffmann, C. K., Ondersockingen over den anat. bouw van de
membrana olfactoria en het periph. uitiende van den Nervus olfactorius.
Dissert. inaug. 1866.
Hoffmann, C. K., Amphibia in Bronn’s Klassen und Ordnungen
des Thierreichs. Leipzig und Heidelberg, 1873–1878. Vol. VI,
pp. 335–347.
Horn, H., Ueber die Endschlingen des Geruchsnerven (nervus
olfactorius) der Rana temporaria. Arch. f. Anat. u. Physiol. 1850.
Hoyer, H., Ueber die mikroskopischen Verhältnisse der
Nasenschleimhaut, etc. Arch. f. Anat. u. Physiol. 1860, p. 50.
Langer, C., Ueber das Lymphgefässsystem des Frosches. Wiener
Acad. Sitzungsb. 1867. Vol. LV, Pt. I, p. 615.
Legal, E., Die Nasenhöhlen und der Thränennasengang der
amnioten Wirbelthiere. Morph. Jahrb. 1882. Vol. VIII, p. 353.
Martin, Studies from the physiological laboratory in the
University of Cambridge. Pt. I. 1873.
Paschutin, V., Ueber den Bau der Schleimhaut der Regio
olfactorio beim Frosch. Medicinisky Wjestnik. 1872. Nos. 38–40.
Paschutin, V., Ueber den Bau der Schleimhaut der Regio
olfactoria des Frosches. Arbeiten aus d. phys. Laborat. Leipzig,
1873.
Paulsen, E., Ueber die Drüsen der Nasenschleimhaut besonders
die Bowman’schen Drüsen. Arch. f. mik. Anat. 1886. Vol. XXVI,
pp. 307–321.
Piersol, G. A., Beiträge zur Histologie der Harderschen
Drüsen der Amphibien. Arch. f. mik. Anat. 1887. Vol. XXIX, p. 594.
Reichert, B., Arch. f. Anat. u. Physiol. 1857, p. 39.
Bericht.
Schultze, M., Ueber die Endigungsweise des Geruchsnerven und
die Epithelial-gebilde der Nasenschleimhaut. Monatsb. Acad. z. Berlin.
1856, p. 504.
Schultze, M., Untersuchungen über den Bau der
Nasenschleimhaut, namentlich die Structur und Endigungsweise der
Geruchsnerven bei dem Menschen und den Wirbelthieren. Halle, 1862.
Vol. VII, pp. 32–41; also published in Berlin, 1875. Abstract in
Centralbl. f. med. Wiss. 1863, p. 97.
Stirling, W., and Macdonald, The minute structure
of the palatine nerves of the frog and the termination of nerves in
blood-vessels and glands. Journ. of Anat. and Physiol. 1884. Vol. XVII,
p. 293.
Wiedersheim, R., Ueber die Kopfdrüsen der Amphibien.
Sitzungsb. d. phys.-med. Gesell. in Würzburg, 1876. Febr. 5.
Wiedersheim, R., Die Kopfdrüsen der geschwänzten Amphibien
und die Glandula intermaxillaris der Anuren. Zeitsch. f. wiss. Zool.
1876. Vol. XXVII, pp. 1–50.
Wiedersheim, R., Lehrbuch der vergl. Anatomie der
Wirbelthiere. Pt. I. Jena, 1882.
V. THE EAR.
Chatin, J., Recherches pour servir a l’histoire du noyau dans
l’épithelin auditif des batrachiens. Annales des sciences nat. Zool.
1883. Vol. XVI, Series VI, Art. No. 2.
Comparetti, A., in gymnasio patavino observationes anatomicae
de aure interna comparatae. Patavii, 1789.
Crombie, J. M., On the membrana tympani. Journ. of Anat. and
Physiol. 1883, pp. 523–536.
Cuvier, G., Leçons d’anatomie comparée. Paris, 1800.
Vol. II.
Deiters, O., Ueber das innere Gehörorgan der Amphibien. Arch.
f. Anat. u. Physiol. 1862, p. 277.
Eberth, C. J., Zur Kenntniss der Verbreitung der glatten
Muskelfasern (Tympanic membrane). Zeitsch. f. wiss. Zool. 1863.
Vol. XII, p. 364.
Ferré, Étude sur la crête auditive chez les vertébrés. Ann.
Sci. Nat. Bordeaux. Vol. I, No. III.
Hasse, C., Die Histologie des Bogenapparates und des
Steinsacks der Frösche. Zeitsch. f. wiss. Zool. 1868. Vol. XVIII,
p. 71.
Hasse, C., Das Gehörorgan der Frösche. Zeitsch. f. wiss.
Zool. 1868. Vol. XVIII, p. 359.
Hasse, C., Das knöcherne Labyrinth der Frösche. Anatomische
Studien, 2nd Pt. 1872, p. 377.
Hasse, C., Die vergleichende Morphologie und Histologie des
häutigen Gehörorgans der Wirbelthiere. Supplement to the Anatomische
Studien. Vol. I, 1873.
Hasse, C., Die Lymphbahnen des inneren Ohres der
Wirbelthiere. In the Anatomische Studien of Hasse, 1873. No. XIX.
Hasse, C., Das Gehörorgan der Wirbelthiere von Gustav
Retzius. Arch. f. Ohrenheilk. 1884. Vol. XXI, pp. 314–324.
Hoffmann, Lehrbuch der Anatomie der Sinnesorgane.
Hoffmann, Bronn’s Klassen und Ordnungen des Thierreichs.
Leipzig and Heidelberg, 1873–1878. Vol. VI, pp. 304–335.
Ibsen, J., Anatomiske Undersögelser over orets Labyrinth.
Udgivet vet P. L. Panum. Kjöbenhawn, 1846 (abstract in Virchow and
Hirsch’s Jahresb. 1881, p. 88).
Kuhn, Ueber das häutige Labyrinth der Amphibien. Arch. f.
mik. Anat. 1880. Vol. XVII, pp. 479–550.
Kuhn, Zur Anatomie des inneren Ohres der Wirbelthiere. Compt.
rend. du III Congrès internat. d’Otologie à Bàle, 1884, pp. 228–238.
Leydig, F., Lehrbuch der Histologie des Menschen und der
Thiere. Frankfurt a. M. 1857.
Leydig, F., Ueber neuere den Aquaeductus vestibuli des
Menschen und der Thiere betreffende Forschungen. Sitzungsb. d.
Niederrheinischen naturf. Gesellsch. in Bonn, 1874. Vol. XXXIV,
p. 124.
Moldenhauer, Vergleichende Histologie des Trommelfells. Arch.
f. Ohrenheilk. 1878, p. 1.
Pappenheim, S., Ueber Verbreitung der Flimmerbewegung. Arch.
f. Anat. u. Physiol. 1840, p. 533.
Retzius, G., On hörselnervens ändningssätt i maculae och
cristae acusticae. Nordiskt medicinskt arkiv. 1871. Vol. III.
Retzius, G., Zur Kenntniss der Morphologie des inneren Ohres
bei Wirbelthieren. Nord. Med. Ark. 1880. Vol. XII, No. 12.
Retzius, G., Zur Kenntniss des Gehörorgans der Wirbelthiere.
Arch. f. Anat. u. Physiol. 1880, pp. 235–244.
Retzius, G., Das Gehörorgan der Wirbelthiere. Pts. I and II,
1881. Stockholm.
Retzius, G., Das Gehörorgan der Wirbelthiere. Congr.
internat. de Copenhagen. Anatomy, p. 29.
Retzius, G., Das Gehörorgan der Fische und Amphibien. Pt. I,
1881. Stockholm.
Retzius, G., Zur Kenntniss der Morphologie des inneren Ohres
bei Wirbelthieren. Nord. Med. Ark. 1880. Vol. XII, p. 6.
Retzius, G., Ueber die peripherische Endigungsweise der
Gehörnerven. Biol. Untersuch. Stockholm and Leipzig, pp. 51–61.
Schultze, F. E., Zur Kenntniss der Endigungsweise der
Hörnerven bei Fischen und Amphibien. Arch. f. Anat. u. Physiol. 1862,
p. 381.
Stannius, H., Handbuch der Zootomie von v. Siebold und
Stannius. Berlin, 1856. 2nd Edit., Pt. II.
Tafani, A., L’organo dell’ udito. Firenze, 1885.
Waldeyer, W., Hörnerv und Schnecke. Stricker’s Handbuch der
Gewebelehre, pp. 915–963.
Weber, E., Amtlicher Bericht über die neunzehnte Versammlung
deutscher Naturforscher und Aerzte in Braunschweig im Sept. 1841.
Printed Braunschweig, 1842.
Windischmann, De penitiori auris in amphibiis structura
Lipsiae, 1831.
VI. THE EYE.
a. The cornea and sclerotic.
Angelucci, A., Ueber den Bau u. die Entwickelung des vorderen
Uvealtractus der Vertebraten. Centralbl. f. d. med. Wiss. 1879. No. 24,
p. 417.
Altmann, R., Ueber die Verwerthbarkeit der Corrosion in der
mikroskopischen Anatomie. Arch. f. mik. Anat. 1879. Vol. XVI, p. 471
(Corneal corpuscles).
Arnold, J., Die Vorgänge bei der Regeneration epithelialer
Gebilde. Virchow’s Arch. 1869. Vol. XLVI, p. 168.
Arnold, J., Experimentale Untersuchungen über die Entwicklung
der Blutcapillaren. Virchow’s Arch. 1871. Vol. LIII, p. 70. 1872.
Vol. LIV, p. 1.
Boddaert, Zur Histologie der Cornea. Centralbl. f. med. Wiss.
1871, p. 337.
Ciaccio, J. V., On the nerves of the cornea and of their
distribution in the corneal tissue of man and animals. Trans. Micros.
Soc. London, 1863. Vol. XI, p. 77.
Clasow, E., Om corneal epithel. Upsala läkareförenings
förhandlingar. 1869. Vol. IV, p. 411.
Cohnheim, J., Ueber die Endigung der sensiblen Nerven in der
Hornhaut. Virchow’s Arch. 1867. Vol. XXXVIII, p. 343.
Durante, F., Sulla terminazione dei nervi della cornea.
Richerche fatte nel laborat. di anat. normal. Roma, pubbl. dal dott. F.
Tocharo. 1873, pp. 81–87.
Engelmann, T. V., Ueber die Hornhaut des Auges. Leipzig,
1867.
v. Ewetsky, Ueber das Endothel der Membrana Descemeti.
Untersuch. aus d. pathol. Institut. Zürich, 1875. Vol. III.
Frey, H., Handbuch der Histologie und Histochemie.
Generisch, Zur Lehre von den Saftkanälchen in der Cornea.
Med. Jahrb. der Gesellsch. d. Aerzte in Wien. 1871, p. 1.
Guye, A. G., Over bekercellen en in het byzonder over
de bekercellen in de membrana nictitans van den Kïkvonch. Nederl.
Tydschrift v. Gewesh. 1868. Vol. II, p. 135.
Hansen, A., Untersuchungen über die entzündlichen
Veränderungen der Hornhautkörper. Wiener Med. Jahrb. 1871, p. 210.
Harpeck, C., Ueber die Bedeutung der nach Silberimprägnation
auftretenden weissen lücken- und spaltähnlichen Figuren in der Cornea.
Arch. f. Anat. u. Physiol. 1864, p. 222.
Hartmann, R., Ueber die durch den Gebrauch der
Höllensteinlösung künstlich dargestellten Lymphgefässanhänge,
Saftcanälchen und epithelähnlichen Bildungen. Arch. f. Anat. u.
Physiol. 1864, p. 235.
Heiberg, H., Ueber die Neubildung des Hornhaut-Epithels.
Wiener Med. Jahrb. 1871.
Heisrath, F., Ueber d. Zusammenhang d. vordern Augenkammer
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Helfreich, Ueber die Nerven der Conjunctiva und Sclera.
Würzburg, 1870.
Henle, J., Handbuch der systematischen Anatomie, 1866.
Vol. II.
His, W., Untersuchungen über der Bau der Hornhaut, in
Verhandlungen der phys.-med. Gesellschaft in Würzburg. 1856. Vol. IV,
p. 90.
His, W., Ueber die Einwirkung des salpetersauren Silberoxydes
auf die Hornhaut. Schweizerische Zeitsch. f. Heilkunde. 1864. Vol. II,
p. 1.
Hoffmann, F. A., Ueber Contractilitätsvorgänge im vorderen
Epithel der Froschhornhaut. Diss. Berlin, 1868.
Hoffmann, F. A., Epithelneubildung auf der Cornea. Virchow’s
Arch. 1870. Vol. LI, P. 373.
Hosch, F., Ueber die angebliche Contractilität der
Knorpelzellen und Hornhaut-körperchen. Pflüger’s Arch. f. d. ges.
Physiol. 1873. Vol. VII, p. 515.
Hoyer, H., Ueber den Austritt von Nervenfasern in das Epithel
der Hornhaut. Arch. f. Anat. u. Physiol. 1866, pp. 180–195.
Hoyer, H., Ueber die Nerven der Hornhaut. Arch. f. mik. Anat.
1873. Vol. IX, p. 220.
Klebs, E., Das Epithel der hintern Hornhautfläche. Centralbl.
f. d. med. Wiss. 1864, p. 513.
Klein, E., Some remarks on the finer nerves of the cornea.
Monthly Journ. Micros. Sci. 1872. Vol. VII, pp. 156–164.
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I. THE SKIN AND ITS APPENDAGES. — II. THE ORGANS OF TACTILE SENSATION. — III. THE ORGANS OF TASTE. — IV. THE NOSE. — V. THE EAR. — VI. THE EYE.
THE SKIN AND THE SENSE-ORGANS.
The general characters and the colouring of the skin have already
been described (pp. 4 to 7). The skin consists of the cutis vera
or corium, and the cuticle or epidermis, and is possessed of numerous
glands.
Fig. 228.
Vertical section through the epidermis from the head of Rana
esculenta; after F. E. Schultze. Magnified 600 times.
A
Horny layer.
B
Middle layer.
C
Deep layer.
D
Isolated mucous-cells.
a. The epidermis (Figs. 228, 230) consists of several
layers of epithelial cells, those of the deepest layer being more or
less columnar in form, those of the middle layer shorter and polygonal,
while those of the superficial layer are flattened, very transparent,
and horny.
All the surfaces of these cells are serrated, the serrations being,
however, with difficulty seen on the free surface of the superficial
cells (Leydig). Each cell has a distinct nucleus; in the deeper cells
the nucleus is oval, broad, and rounded, in the superficial cells
flattened and thin.
Fig. 229.
Vertical section through the skin of the back; after Wiedersheim.
Co
Superficial layer of cutis.
Co1
Middle layer of cutis.
Co2
Deep layer of cutis.
D
Cutaneous glands.
D1
Ducts of cutaneous glands.
Ep
Epidermis.
H
Horny layer of epidermis.
P
Pigment-cells.
W
Papillae.
The surface of the epidermis (Fig. 230) forms a very beautiful
mosaic of flat cells, chiefly hexagonal in form, with pale, central,
oval nuclei. Here and there two adjacent cells appear to enclose a
semilunar space (Fig. 228 D); these spaces are occupied by
peculiar cells (goblet-cells, E. Schultze; mucous cells, Leydig),
which do not belong to the superficial cells but the layer of cells
immediately beneath the horny layer (Schultze, Pfitzner). The cells
are rounded or flask-shaped, and closely resemble the epithelial
goblet-cells or chalice-cells. According to Rudneff they open on the
free surface by stomata; this is, however, denied by Schultze and
others.
According to Pfitzner these cells secrete a substance, which has
an important function in connection with the process of casting the
skin, which consists in the separation of the upper layer from that
below brings about a complete shedding of the skin (Wiedersheim).
Fig. 230.
Surface view of epidermis of Rana temporaria;
after Eberth.
A
Epidermal cell.
B
Stoma-cell.
C
Attached cuticle from duct of gland.
D
Protoplasm and nucleus of stoma-cell.
Fig. 231.
Nerve terminations in the branched pigment-cells
of the cutis; after Ehrmann. Hartnack, Obj.
8, Oc. 3.
I.
Pigment ceasing abruptly at junction of nerve.
II.
Pigment gradually ceasing along the nerve.
[The horny layer is, for the most part, very thin, as it consists
of one or two layers of flattened cells only (Schultze), but in some
situations, as on the back and especially on the under surface of the
toes, it is much thickened, and is then rough.
Deeply pigmented, branched cells, capable of contractile movements,
are also found, somewhat sparsely distributed, in the epidermis
(Leydig, H. Müller, Schultze).]
b. The cutis (Fig. 229, Co,
Co1, Co2). The epidermis is
generally attached to the corium by means of a continuous layer of
branched cells, which is deeply stained when the animals are fed with
madder (Katschenko). Many of these cells are pigmented. This layer
is seldom flat, but is raised into papillae and folds, which are
repeated by the superimposed epidermis. In addition to this layer the
corium has, except in the webs and supplemental toes, three distinct
layers of connective-tissue, together with much unstriped muscle-fibre
(Eberth).
The superficial layer (Fig. 229Co) is a
loosely-meshed, much pigmented, vascular layer; it forms a loose
support for the numerous glands, and is traversed by numerous
nerves.
The middle layer (Co1) forms the
groundwork of the cutis; it is much firmer and more compact than the
superficial layer; in section it appears as a broad band, bounded
superficially by a sharp line. It is chiefly composed of closely packed
connective-tissue fibres, which have, for the main part, a horizontal
or wavy course; at certain points, however, vertical fibres are seen
passing towards the surface and hiding the sharp contour (between
Co and Co1). At such points the two sets of
fibres form a sort of basket-work arrangement.
The deepest layer (Fig. 229Co2) is
composed of very delicate, white and yellow elastic fibres, and vessels
and nerves; it attaches the whole integument to the underlying organs.
By the looseness of its structure it forms an important lymph-space.
[The muscle-fibre of the cutis is very unevenly distributed.
It is found somewhat freely in the region of the back, the dorsal
surface of the head, and the neck; less freely on the dorsal surfaces
of the extremities, very sparsely on the abdomen, breast, and ventral
surfaces of the extremities; in the feet it appears to be absent
(Eberth).
The pigment of the skin. As already mentioned pigmented
cells occur in the
epidermis, but by far the greater quantity of the cutaneous pigment is
found in the cutis, and more especially in the loose layer of branched
cells, which form the boundary between epidermis and true cutis. These
cells, known as chromatophore-cells, have been carefully investigated
by Harless. They play an extremely important part in bringing about the
well-known changes in the colouring of the skin. Bimmerman has proved
that these cells are influenced by stimulation of the nerves supplying
the region in which they occur. Ehrmann has been able to trace a direct
connection between the nerve-fibres and the pigment-cells (Fig. 231 I,
II). In such cases the pigment was sometimes sharply marked off, at
others was gradually lost along the nerve.]
c. The papillae and ridges of the skin are
classified by Leydig as follows: (1) Small ridges, (2) larger ridges,
(3) papillae with touch-bodies, (4) papillae without touch-bodies,
(5) papillae with the ducts of glands, (6) capillaries in the form of
papillae, (7) small elevations, including the lateral organs.
[All these structures are derived from the cutis, the epithelium
above simply repeating the elevation, and being itself either not
increased in thickness or only to a slight degree. (For further
description of some of these papillae, see Organs of Tactile Sensation,
p. 380.)
Peculiar wart-like papillae are found on the articulations of the
first phalanges with the metatarsus, on the same articulations and on
the articulations between the first and second phalanges of the third
and fifth toes, and on the articulations between the first, second, and
third phalanges of the fourth toe. These papillae are connected with
the long flexor tendons by fine tendinous bands (Klein).
Temporary papillae are developed in the females of Rana
temporaria during the breeding season; according to O. Huber (l.
c.), who has described them, their distribution and structure is as
follows:—
During the breeding season the skin of the sides of the trunk
of female specimens of Rana temporaria is rough; the small
elevations, to which this roughness is due, are each about the size of
the head of a pin, and have the appearance of small, rounded, white or
pale rose-coloured, warty growths. The papillae reach their greatest
development and are most numerous on the sides of the trunk (Fig. 232
I); they may be traced on to the tympanic membrane, where they are
arranged in a ring, and in some cases under the eyes to the sides of
the snout.
Anteriorly the papillae are absent from the median portion of the
dorsal surface of the trunk, but posteriorly, behind a line joining the
anterior extremities of the two iliac bones, the papillae cover the
whole surface.
The papillae are large and very numerous around the arms, and pass
by gradual, transitionary stages into the ordinary papillae of the
region. Further they may be traced backwards along the anterior or
extensor surface of the thigh, the upper surface of the leg, foot, and
fifth toe. Occasionally a few papillae were found on flexor surfaces of
the third and fourth metatarsus, and very rarely were any discovered
on the fore-limbs. They occur in no other batrachian of Germany
(Huber).
Fig. 232.
I. Diagram to show the distribution of the temporary papillae in Rana
temporaria; after Huber.
II, III. Vertical sections through a temporary papilla; after Huber.
Each papilla (Fig. 232 II and III) consists of a hemispherical
elevation of the cutis, and is covered either by a layer of normal
epidermis or in some very rare cases the epidermis was slightly
thickened. The papilla consists of a firm connective-tissue stroma, and
is from 0.2–0.4 mm. in height, 0.4–0.5 mm. broad (after hardening in
alcohol). Such glands as exist in the papilla usually open laterally
(Fig. 232 III), and the blood-vessels are numerous.
The epidermis covering the papilla is well supplied with
nerve-fibres, derived from large ganglion-cells in the papilla
(Fig. 232 III). The branched pigment-cells, so numerous in the rest of
the skin, are absent from the upper parts of the papillae (Fig. 232
II); the pigment-cells may cease either abruptly or gradually.
The rose-colour of the papillae is due to the presence of a golden
red pigment. After the breeding season the papillae are gradually lost,
and the pigment-cells wander into the unoccupied parts.
Huber compares the arrangement of the nerves to that of the
‘touch-spots’ of Merkel.
d. The glands of the skin are of two kinds, serous and
mucous; they have been fully described by Engelmann and Openchowski.
(1) The serous glands (Körnerdrüsen, Engelmann) are large,
averaging in diameter 0.2–0.4 mm., but others vary in size from
0.13–0.8 mm. in diameter. They are found chiefly on the dorsum of the
trunk and arranged in groups, which vary in dimensions from 3–20 mm. in
length and 2–4 mm. in breadth. They may be found in any part between
the ear-region and the anus, on the dorsal surface of the thigh,
especially towards the outer and inner borders. They are found very
sparsely distributed on the ventral surface of the trunk and on other
parts of the extremities, though as a rule a few are found on the
dorsal surface of the feet and near the phalanges. They are wanting in
the nictitating membrane.
The glands have a rounded form, with the ducts placed at their
superficial poles. The glands possess three coats; externally is a
coat of connective-tissue, the fibres of which are arranged closely
together, and cross one another at acute angles: these fibres are
continuous with the connective-tissue of the surrounding cutis. Inside
this coat is a thick layer of muscle-fibre (0.005–0.015 mm.); the
muscle-cells are arranged meridionally, with the one pole towards the
superficial surface of the gland, the other pole at the deep surface
(Hensche). Many of the fibres, however, extend only one-fourth or
one-third of this distance.
The innermost coat is a simple layer of epithelial cells, which
rests directly on the muscle-layer; no basement-membrane or space of
any kind having been discovered between the two layers. When examined
in the recent state these cells are conical or cylindrical in shape,
and have the appearance of goblet-cells: they possess a delicate but
distinct cell-wall, but are open towards the lumen of the gland. One
or sometimes two rounded nuclei are found towards the base of the
gland, and surrounded by a small amount of granular protoplasm; the
rest of the cell is occupied by a mass of small, rounded, highly
refractive granules of about 0.002–0.01 mm. in diameter. These granules are also to be found
in the protoplasm of the cell; they contain a substance capable of
swelling freely, and present many points of resemblance to the granules
found in the cells of the oviducts.
These glands represent the poison-glands or lateral glands of toads,
and the ear-glands or parotids of Caecilia (Leydig). According to
Leroux81,
Gratiolet and Cloëz82, the reaction of these glands in toads varies;
according to du Bois-Reymond83 the reaction is, in frogs, acid; Engelmann84 found the
reaction of these glands, in frogs, to be neutral, frequently, however,
with a tendency to either acidity or alkalinity.
These glands correspond with the ‘large glands’ of Hensche, the
‘contractile glands’ of Stieda, the ‘large, dark glands’ of Eberth, and
the ‘large contractile glands’ of Leydig’s earlier publications.
(2) The mucous glands are, as a rule, smaller, more numerous,
and more evenly distributed than the serous glands. Usually they lie
in such close proximity as almost to touch one another; according to
Engelmann an average number of sixty is found in one square millimeter;
on the abdomen 62–68; flexor surfaces of the posterior extremities in
some places 76, but in others only 30–40; on the webs only 2–6 to the
square millimeter. On the nictitating membrane they are arranged in two
or three parallel rows, are large, and closely applied to each other.
They are wanting on the deeper surface of the nictitating membrane.
The glands are generally rounded in form and have a short neck
(Fig. 229). Glands in the recent condition, and not fully contracted,
have a diameter of 0.06–0.21 mm., the majority measure 0.12–0.16 mm.
in diameter. The upper pole of the gland is usually placed directly
under the boundary between epidermis and cutis, and, as a rule, about
0.06–0.1 mm. beneath the superficial surface of the skin. The duct
usually passes directly to the surface, in a straight line.
The structure of the glands corresponds, in general, with that
of the serous glands. Externally is a coat of connective-tissue,
which is, however, more firmly attached to the muscular coat than
in the case of the serous glands, and may easily be mistaken for a
structureless basement-membrane85 (Eberth). The muscular coat is very thin, and
consists of 16–20 flat, spindle-shaped fibres; extending from the upper
to the lower pole as in the serous glands. At a short distance (0.015–0.022 mm.) from the
upper or superficial pole each fibre has an ellipsoid thickening,
composed of granular protoplasm, and containing a clear oval
nucleus.
The inner coat is composed of a single layer of epithelium, placed
directly on the muscular coat. The epithelium has a thickness of about
0.01–0.02 mm.; it is, however, usually thicker towards the base than
towards the duct. The boundaries between the cells are very indistinct,
and so give the epithelium the appearance of a continuous layer of
protoplasm. The glandular epithelium is not directly continuous with
the epithelium of the duct.
The shape of the cells depends upon their physiological condition.
In a state of semi-contraction of the gland, the cells are cubical,
and their free borders pushed into the lumen in a slight convexity;
when the gland is fully distended the cells are two or three times as
broad as deep; in a fully contracted gland the cells are conical or
cylindrical. In the first-mentioned condition their diameter varies
from 0.006–0.018 mm. The larger glands are estimated to possess about
150 cells, the smaller only thirty to forty (Engelmann).
The cells appear to have no cell-wall, certainly they possess none
on their free surfaces. Their protoplasm distends very freely on the
addition of water. As a rule some cells are much more granular than
others of the same gland; each cell has a rounded oval, clear nucleus,
and vacuoles are frequently met with.
The lumen of the gland contains a colourless, transparent, watery
fluid, which contains mucous material.
The ducts of the glands are thick-walled cylinders, circular in
section. Their diameter varies from 0.02–0.05 mm., their length is
equal to the depth of the superimposed epidermis. The wall of the duct
is lined with two or three concentric layers of highly refractive,
nucleated cells. The cells are arranged parallel to the length of the
duct: in transverse section they are sickle-shaped or semilunar. In
the upper third or fourth of the duct the inner wall is lined with
a cuticle, very resistant to the action of acids or alkalies: it is
thrown off with the skin in the process of casting. In the horny layer
of the epidermis this cuticle is partially closed by a stoma-cell
(Eberth), (Fig. 230), which possesses a tri-radiate opening.
The glands correspond with the ‘non-contractile glands’ of Hensche,
the ‘dark and bright glands’ of Stieda, the ‘glandule mezzane, piccole
e piccolissime (ad epitelio pavimentoso)’ of Ciaccio, and the ‘small,
dark, and medium-sized, bright glands’ of Eberth.
Fig. 233.
Vertical section through the epidermis of the supplemental toe of
Rana esculenta; after E. Schultze. Magnified 400 times.
e. The peculiarities of the skin
of the supplemental toe and webs. The supplemental toe presents, in
the male, a rounded, oval swelling (Fig. 234 I, D), with the end
of the digit projecting from the distal end.
Normally this swelling is usually of a grey colour; during the
breeding season, however, the swelling enlarges, and becomes of a black
or deep brown colour (Leydig).
The epidermis covering this swelling (Fig. 233) is much thickened
and produced into projecting papillae. The cutis also shows a marked
thickening and an increase in vascularity; the glands are of the kind
described as mucous glands (Engelmann). They present, however, an
immense increase in size, and at the same time are so closely applied
to one another as to form the main part of the enlargement (see also
Organs of Tactile Sensation).
In the webs the various layers of the corium are more or
less fused together, and
cannot be distinguished from each other; the glands are, as a rule,
smaller than on the general surface of the skin.
Fig. 234.
Fore-foot of a male frog.
Vertical section through the swelling on the supplemental toe
of a male frog.
D
Glandular swelling on the supplemental toe.
W
Warty papillae on the inter-phalangeal joints.
B
Blood-vessels.
Co
Cutis.
D
Glands.
Ep
Epidermis.
M
Muscles.
P
Pigment-cells.
f. The blood-vessels and lymphatics of the
skin.
(1) The blood-vessels of the skin are arranged in two
networks; the one is situated immediately beneath the epidermis, and
consists of fine capillaries, forming a fine-meshed network, which
enclose the ducts of the glands. The meshes vary considerably in size
and shape (Hyrtl and Langer). The second network of vessels is situated
under the cutis; the vessels forming it are small, and the meshes
formed are large. From this network vertical branches pass to form the
superficial network; these branches usually course along the strands
of vertical fibres already described, and break up to form capillaries
only when they reach the deeper surface of the epidermis (Langer),
(Fig. 235 I).
Fig. 235.
The blood-vessels and lymphatics of the skin; after Langer. Arteries striped, lymphatics shaded.
I.
Vertical section through skin of thigh.
II.
Horizontal view of arteries and lymphatics of the skin.
III.
Peculiar tortuous arteries of the lamina inguinalis.
IV.
Arteries and lymphatics of the web.
In some situations, however, the vertical branches divide
earlier; this is especially the case in parts where the glands are
very closely packed, as in the nictitating membrane, the upper lip,
and the swelling of the
supplemental toe (in the male). In these parts the division takes place
at the deeper surface of the glands (Langer).
A peculiar arrangement of the cutaneous blood-vessels is
found in the lamina inguinalis, where a chain of reddish points can be
made out with the naked eye; examined more carefully (Fig. 235 III)
each reddish point is found to be a complex loop of capillaries. They
extend from the skin to the hinder lymph-hearts, where they form a
close network which partially invests the lymph-hearts (Langer).
(2) The lymphatics of the skin (see also p. 252), like the
arteries, reach the deeper surface of the epidermis by coursing along
the bands of vertical fibres; they then form a network of capillaries
with rounded meshes (Fig. 235 I, II, IV), and lying immediately under
the epidermis, and a network which surrounds the various glands. The
lymphatic-capillaries are as a rule larger than the blood-capillaries.
The lymphatic network lies beneath the blood network, and the vessels
of the two systems branch independently (Langer).
In those parts where the glands are placed closely together this
arrangement is modified, and corresponds with the modifications found
in the blood-capillaries in these regions. The vertical branches divide
so as to form a network below the glands, and from this vertical
branches pass in the same direction between the glands to form a
secondary network on the superficial surface of the glands (Langer).
g. The nerves of the skin. The cutis is very richly supplied
with both medullated and non-medullated nerves. In the subcutaneous
tissue the nerves destined for the skin branch freely to form numerous
fine twigs, which, without actually inosculating, form a fine meshwork.
From the larger trunks numerous vertical branches pass vertically to
form a secondary network, from which both coarse and very fine twigs
pass to encircle the glands. The fine fibres which supply the glands
are non-medullated and possess oval nuclei; their diameter varies from
0·001–0·002 mm. The number of nerve-fibres is not much smaller than
that of the muscle-fibres (Engelmann). (See also Organs of Tactile
Sensation.)]
The organs of tactile sensation are the nerve-plexus of the
epidermis, the touch-spots of Merkel, the lateral sense-organs, and the
touch-corpuscles of the tendons.
a. [The nerve-plexus of the epithelium is very
incomplete as compared with the plexus found in the epithelium of
the cornea; here and there a few non-medullated fibres have been
traced a short distance between the epithelial cells. No such mode of
nerve-terminations in the epithelium as is described by Eberth and
Macullum in the tadpole can be found in the adult.]
b. The touch-spots. What knowledge we possess of these
organs is due to the labours of Leydig, Ciaccio, Eberth, and more
particularly those of Merkel.
At the base of each papilla, which contains such a touch-organ, is
found a number of colourless, flattened cells, arranged either in a
single layer, or heaped up and connected with very fine nerve-fibres.
The flat surface of the cells is parallel to the surface of the body,
and they do not form a separate or circumscribed body, they are
therefore better spoken of as touch-spots than as true touch-bodies
(Merkel). The larger organs are found in the papillae, but smaller ones
may be found on any part of the skin.
Fig. 236.
I.
Lateral sense-organ of tadpole of frog. Half-schematic.
c
Central zone (nerve-epithelium).
Ml
Membrana limitans.
p
Peripheral zone (sustentacular cells).
R
Hyaline tube.
II.
Touch-corpuscle from the sheath of a digital
tendon of the frog; after Löwe. Schieck, Oc. O., Obj. 9.
These organs are best seen in the prominence or swelling upon the
supplemental toe during the breeding season; they are numerous on the
dorsal surface of the trunk, but occur most frequently on the under
surface of the hinder feet (Planta pedis). After the breeding season the organs of
the thumb undergo a retrogressive change, which results in a network of
spindle-shaped and branched cells with fibres (Wiedersheim).
c. The lateral sense-organs attain their highest
development in the tadpole; in the adult the organs have undergone
a retrogressive change, the result of which is that the organs are
diminished in size; the whole organ sinks by the formation of a tube,
which is then closed by a mucous secretion, consequently the organ is
functionless: with this loss in function and change in position of the
organs a corresponding diminution of the ramus lateralis nervi vagi
occurs (Merkel).
Each lateral organ (Fig. 236 I) consists of a slightly elevated
papilla, with the centre depressed, and in each may be distinguished
a central and a peripheral zone (c, p). The central
zone consists of a group of pear-shaped cells, with the narrower ends
directed towards the free surface; each is connected below with a
nerve-fibril, while above it bears a short, stiff cilium. The cilia
are enclosed in a delicate hyaline tube (R), which is open
superficially, closed by the papilla below; consequently the cilia are
in direct contact with the surrounding medium. The peripheral zone
is a layer of pale, flattened, cylindrical cells (p); they
possess, at their upper borders, a perforated membrana limitans
(Ml), through which the cilia pass. These cells serve as a
support to the central cells, and are themselves surrounded by ordinary
epithelial cells.
The distribution and arrangement of the lateral organs is alike in
fish and larval amphibia. They are most numerous on the head, where
they surround the eye, and are continued forwards to the snout and on
to the lower jaw. All these organs on the head are in connection with
the trigeminal nerve. A line of these organs passes from the hinder
part of the circumference of the eye along the gill-cover to the neck,
where the lines of opposite sides are usually, though not constantly,
joined by a transverse line of the same organs; thence the lines
are continued along the trunk to the tip of the tail. In fish there
exists, as a rule, only one pair of such longitudinal lines (Linea
lateralis); in anura-larvae, proteus, and in all salamanders there
are three pairs: of these one pair lies near the vertebral column, the
second at the junction of the flank with the abdomen, and the third
corresponds to the lateral line in fish (Malbranc).
At an early developmental period each metamere possesses one pair of
such lateral organs; in later life, however, this simple arrangement is
lost, and each segment usually possesses a group of organs.
The organs of the trunk and tail are supplied by branches of the
Ramus lateralis nervi vagi. Both in fish and amphibia a reparative
process, by means of fission, occurs; as a consequence the organs are
found in various stages of development.
d. [The touch-corpuscles of Golgi and Löwe (Fig. 236
II) are found on the joints of the digits. They are surrounded by
connective-tissue
and are spindle-shaped; the two ends of the spindle are glassy in
appearance, the middle portion is fibrous. In the thickest part of the
corpuscle is a zone of nuclear bodies.
They are regarded as touch-bodies (Golgi and Löwe). Golgi (l.
c.) describes two kinds of touch-organs in connection with muscle
and tendon; one class correspond with those just described, he names
them ‘nervous muscle-tendon organs.’ The second class he compares with
the touch-bodies found in the conjunctiva.]
The organs of taste are not confined to the surface of the tongue,
but are also found on the mucous membrane of the roof of the mouth,
especially in the neighbourhood of the vomerine teeth; on both roof and
floor of the mouth these organs can be traced to the commencement of
the oesophagus.
[The mucous membrane of the tongue possesses two kinds of papillae
and numerous glands.
a. The filiform papillae are the more numerous; they
are conical or thread-like in form, and consist of connective-tissue,
with a few striated muscle-fibres; they include blood-capillaries, but
no nerves have been traced into them (Leydig). They are covered with
ciliated epithelium and goblet-cells.
b. The fungiform papillae are much larger, and are
paler than the filiform papillae. The free ends of these papillae
are broader than the bases, and when the epithelium is removed the
free ends present a concavity. From the base to the border of the
free surface each papilla is covered with the usual oval, ciliated
epithelium, but at this border an abrupt transition takes place.
The epithelium covering the end of the papillae is of three kinds:
goblet-cells, cylindrical cells, and forked cells; the three forms of
cells are quite characteristic, and no intermediate transitionary forms
are met with.
(1) The goblet-cells (Fig. 237 I) are arranged vertically
to the free surface of the papilla; they are from 0.020–0.024 mm. in
length, and from 0.01–0.02 mm. in diameter. In the lower third of
the cell is found a nucleus of about 0.008 mm. in diameter, and this
encloses a nucleolus of about 0.001 mm. in diameter. Close underneath
the nucleus the cell is contracted to form an irregular process or
foot. The contents of the cells are a very finely granular, transparent protoplasm.
These cells form the outermost part of the epithelium, covering the
end of the papilla; all the cells belonging to the same papilla are
of the same size. In consequence of the mutual pressure which they
exert on each other they present, in transverse section, six-sided
outlines (Fig. 237, 2). The nuclei of adjacent cells are placed at
almost exactly the same level. By the action of reagents on these cells
very remarkable forms are obtained, in consequence of the protoplasm
swelling and being forced upwards (Fig. 237, 5).
Fig. 237.
I.
Various parts from the fungiform papillae; after Engelmann.
1.
Nerves of a fungiform papilla. Magnified 450 times.
2.
Surface view of the epithelium, after five minutes’ action
of iodized serum. Magnified 600 times.
3.
Goblet-cell with adjacent forked cell. Magnified 450 times.
4.
Portion of the papilla, after removal of the goblet- and forked
cells; only cylindrical cells remaining. Magnified 400 times.
5.
Goblet-cell, with swollen contents. Magnified 450 times.
6‑13.
Various forms of isolated forked cells. Magnified 450 times.
II.
Sections of two glands of the tongue; after Biederman.
1.
Resting-gland.
2.
Gland after stimulation.
(2) The cylindrical cells (Fig. 237 I) have rounded free
extremities, which reach to the general surface of the epithelium;
the remainder of the cell is cylindrical except towards its lower
extremity, where it
is slightly dilated and encloses an oval nucleus: the protoplasm
of the cells is very finely granular. These cells rest on the
connective-tissue of the papilla, and are in close juxtaposition, so
that several hundreds of them are found on one papilla.
The spaces between the upper parts of the cylindrical cells are
occupied by the goblet-cells and by the forked cells.
(3) The third form of cell found on the fungiform papillae
are named forked cells (Fig. 237 I) by Engelmann. The body of
the cells has an ellipsoidal form, is from 0.006–0.008 mm. in its
longer diameter, and 0.003–0.004 mm. in the shorter diameter. Processes
arise from both poles. The peripheral processes arise by a short
common stem, which then divides into two or rarely three branches; the
whole process is from 0.004–0.008 mm. in length, and is always just
sufficiently long to reach the general surface of the epithelium: when
the peripheral process is long the central is usually shorter, and
vice versâ.
The central processes arise by a stem from 0.001–0.002 mm. in
thickness, which usually divides dichotomously. The length of this
process may be as much as 0.025 mm. or almost nil.
The forked cells are about twice as numerous as the goblet-cells,
they occupy the spaces between the cylindrical cells and the
goblet-cells. The branched central processes form a network on the
connective-tissue of the papilla, which is, at this point, perforated
by a rich plexus of fine non-medullated nerve-fibrils. It is not
decided whether the processes of various cells inosculate. Engelmann
regards these forked cells as the taste-cells and as the sensory
nerve-endings.
The bodies of the fungiform papillae contain blood-vessels
and nerves, the latter enter as medullated nerves, but lose the
medulla, somewhat abruptly towards the upper end of the papilla, where
they form a sort of nerve-cushion (Nervenkissen, Engelmann).]
Taste-organs are also found on the roof and other parts of
the mouth, and present many points of resemblance to the lateral
sense-organs. Like them they present a peripheral zone and a central
zone; the cells of the latter, however, are not longer than the
peripheral cells, and possess no cilia (J. van der Hoeven, Merkel).
The anterior nares or nostrils are two small openings, placed
directly in front of the anterior angle of the eye; the distance
between the eye and the corresponding nostril being, in the case of
adult animals, about five or six millimeters. The anterior nares are
surrounded by rims, which are contracted below, and so form very short,
tentacular-like prominences.
The posterior nares (choanae) are about four millimeters
from the anterior nares, consequently the long axis of the nose is,
approximately, of this length. (For the external muscles of the nose,
see p. 59.)
The boundaries of the nasal cavities are as
follows:—the roof of each cavity is formed by the dorsal plate of the
sphenethmoid, the nasal bone, and the premaxillary bone; the floor
is formed by the vomer and the palatine bone, the inner wall by the
vertical septum of the sphenethmoid, the outer wall by the premaxillary
and maxillary bones, the anterior wall by the premaxillary bone, and
the posterior wall by the sphenethmoid. The cartilaginous portion of
the nasal skeleton (see also p. 27) projects into
the general cavity and subdivides it into various sinuses, which have
been the subject of careful investigation by Born and Wiedersheim.
a. The nasal cavities are best examined by means of
serial transverse sections; in a section through the anterior nares
(Figs. 238, 239) there
will be seen three sinuses on either side:—
(1) The superior sinus (on) is large, rounded,
and placed against the cartilaginous septum; the sinus is lined
with olfactory epithelium. Posteriorly the sinus extends beyond
the posterior nares, and is bounded by the anterior surface of the
sphenethmoid. In front it ends in a rounded concavity, likewise lined
with olfactory mucous membrane. Opposite the anterior nares the cavity
is partially subdivided, by a longitudinal process on the floor, into
two cavities; the anterior nares open into the external chambers, and
therefore not directly into the main cavity of the superior sinus. The
superior sinus communicates with the inferior sinus by a narrow, almost
vertical, slit.
(2) The inferior sinus (un) is narrow and flattened
from above downwards; it is placed against the maxillary bone, and
represents the maxillary sinus of the frog. Externally it possesses a
descending arm.
The inferior sinus is continued backwards and opens on its inner side into the posterior
nares, or rather into the mouth. The descending arm extends only a
short distance forwards, to terminate near the point where the superior
and inferior sinuses communicate by only a narrow opening. This sinus
is on the whole broader in front than behind, and has a general
direction from without, inwards and forwards underneath the superior
sinus.
Fig. 238.
Fig. 239.
Frontal sections through the nose of two tadpoles; after G. Born.
A
Anterior naris.
b
Cartilaginous floor.
C
Cutis.
d
Cartilaginous roof.
Ep
Epidermis.
gi
Intermaxillary gland.
gni
Lower nasal gland.
gns
Upper nasal gland.
K
Maxillary sinus.
l
Concha narium (os lachrymale).
m
Maxillary bone.
MS
Oral mucous membrane.
ok
Cartilage.
on
Upper blind sac.
R
Pharyngeal gland.
S
Nasal septum.
se
Septum between the upper and lower nasal cavity.
sn
External blind sac.
T
Trabeculae.
Th
Lachrymal duct.
un
Lower blind sac.
(3) The lateral sinus (sn) is situated in the
partition between the superior and inferior sinuses, or rather between
the external chamber of the upper sinus and the inferior sinus. The
lateral sinus is triangular in form, being narrow in front and broad
behind; at its inner
posterior angle it opens on the free border of the horizontal partition
between the superior and inferior sinuses; this opening is, however,
continued along its roof, so that the lateral sinus opens also into the
superior sinus.
b. The nasal cartilages. The two nasal cavities are
completely separated by the cartilaginous septum (Figs. 238 and 239
S), and are for the most part lined by cartilage. The anterior
end is formed of concave cartilages, while the posterior, being
situated in the sphenethmoid, is usually more or less ossified in the
adult. The posterior wall has two openings: a larger near the septum
for the olfactory nerve, and a smaller, more externally, for the nasal
branch of the trigeminal nerve.
The anterior wall is more complex than the posterior, being thicker
in the middle than at the sides, and possessing three blind sacs
for the three sinuses. From the anterior wall two processes project
backwards between the sacs and enclose them more or less completely.
Of the three sacs or cavities only the lower is completely
surrounded by cartilage. The upper sac is in part bounded by a
shell-shaped, concave cartilage (Concha narium, of various
authors; Os lachrymale, Born), which covers it anteriorly and
externally, and is attached by a small base to the roof of the lower
sac (Fig. 239, l), its upper border bounding the anterior naris
(Fig. 15). The upper and external parts of the upper sac have no
cartilage. The cartilages of the outer wall of the lower, blind sac
extend backwards to the point where the maxillary sinus commences to
descend: the roof, however, is prolonged further backwards by two small
cartilaginous processes; the inner is short, the outer forms the roof
of the descending arm of the sinus, and joins a cartilaginous process,
which commences at the anterior portion of the roof of the nasal
cavity, passes backwards and downwards to a broad plate, and forms
an incomplete outer wall to the nasal cavity. There are also three
cartilaginous processes—α. One arising from the outer side of the floor
at the level of its junction with the anterior wall; it is a flattened
process and passes outwards, and bifurcates at its end to meet the
premaxillary and maxillary bones (this is the Oberkieferfortsatz of
Ecker), (p. 28, Fig. 14n″). β. A delicate process on either
side, described by Wiedersheim (see p. 280). γ. The third pair of
processes are fully described for the first time by Born; each arises
at the lower border of the corresponding Concha narium, passes
forwards and downwards under the ascending process of the premaxillary
to the point where
process β is attached to this bone. The processes are flat and approach
one another obliquely; in older animals they are united at the point of
contact.
At the junction of the anterior wall, the septum, and the floor is a
large aperture in the cartilaginous capsule, through which passes the
chief nasal branch of the trigeminus, which supplies numerous branches
to the intermaxillary gland.
c. The glands of the nasal region are Bowman’s
glands, the intermaxillary glands (Wiedersheim), the lower nasal gland
(Born), the upper nasal gland (Born), the pharyngeal gland (Born), and
the lachrymal duct.
(2) The lower nasal gland is placed along the septum and
extends as far back as the posterior nares, opening by its ducts
(Figs. 238 and 239gni) into the inferior blind sac of the
nasal cavity. In histological structure it corresponds with the
intermaxillary glands, except that the glandular tubes are somewhat
smaller, and the glandular epithelium stains somewhat less easily with
carmine (Born).
(3) The upper nasal gland occupies the space between the
Concha narium (Os lachrymale, Born) and the neighbouring
cartilages, it also surrounds the anterior naris and the opening of the
lachrymal canal (Figs. 238 and 239gns). The numerous ducts open
on the mucous membrane covering the oblique cartilage (above described,
as passing from in front, downwards and backwards, and forming an
incomplete outer wall of the cavity), and its hinder prolongation.
(4) The pharyngeal gland is placed transversely behind
the posterior nares, and surrounds the vomerine teeth. A portion of
the ducts open into
the posterior nares, the remainder on the mucous membrane of the
pharyngo-oral cavity at two symmetrically placed points (Fig. 238R).
(5) The lachrymal duct (see p. 428) opens into the nasal
cavity at the point where the lateral sinus opens into the external
chamber of the superior nasal sinus.
Fig. 240.
I.
A.
Bowman’s glands in situ from Rana temporaria;
after C. K. Hoffmann. Magnified 150 times.
B.
Section of Bowman’s gland; after C. K. Hoffmann.
Magnified 300 times.
II.
Vessels of nasal mucous membrane of Rana
esculenta; after Langer. Blood-vessels striped, lymphatics
shaded.
(6) [The glands of Bowman (Fig. 240 I) are freely
distributed in the nasal mucous membrane. Each gland is usually rounded
or flask-shaped, and consists of a single layer of large epithelial
cells possessing distinct nuclei and nucleoli. The epithelium of the
glands possesses no basement membrane (M. Schultze and Hoffmann86), but is
bounded externally by a layer of nerve-fibres and connective-tissue.
The glands situated more superficially have straight ducts opening
on the surface; those placed more deeply have usually curved ducts
(Paschutin).]
d. The mucous membrane of the nasal cavities. That
part of the superior sinus immediately around the anterior naris is
lined with stratified epithelium; the rest of the nasal cavity is lined
with columnar ciliated epithelium The epithelial layer rests on a
subepithelial network, and this again on a submucous connective-tissue
layer possessing numerous vessels and nerves.
Fig. 241.
Separations from the olfactory mucous
membrane of Rana temporaria;
after C. K. Hoffmann.
I.
Surface view of the olfactory mucous membrane. Magnified 350 times.
II.
Epithelial and olfactory cells. Magnified 600 times.
III.
Epithelial cells. Magnified 600 times.
(1) The epithelial layer (Fig. 241) consists of columnar
cells, which in the olfactory region are of two kinds; in other regions
the epithelium consists of closely-applied ciliated, thick cells,
possessing large oval nuclei, and having irregular, branched bases or
‘feet.’ The cells are 0.032–0.048 mm. long; the nuclei 0.016–0.018 mm
long, and 0.006–0.008 mm. broad. The free borders of the cells bear a
number of fine cilia.
In the olfactory region a second set of cells, olfactory cells,
are met with; these cells (Fig. 241 II) possess each an oval body,
enclosing a large nucleus, and a peripheral and central process. The
peripheral processes reach to the general surface of the surrounding
epithelium and there terminate in a number (5–8) of stiff cilia; these
cilia are sometimes 0.09 mm. long, they are thicker at their bases than
the ordinary cilia (Schultze); according to Hoffmann, a second system
of stiffer and longer cilia is met with; of which each olfactory cell
possesses as a rule only one. The bodies of the olfactory cells are
0.009–0.010 mm. long, and 0.007–0.008 mm. broad; the peripheral processes vary considerably
in length, according to the position of the body (0.03–0.05 mm.). The
central processes vary from 0.02–0.03 mm. in length. The peripheral
processes are considerably thicker than the central processes. No
membrana limitans olfactoria has been discovered in the frog.
(2) The second layer consists of a network of processes
belonging to the bases of the central processes of the superimposed
epithelial and olfactory cells. Numerous highly refractive nuclei
possessing nucleoli are situated in the meshes of this network; they
correspond in all particulars with the nuclei of the olfactory cells
(M. Schultze). According to Exner the branched processes of the
epithelial cells and of the olfactory cells unite to form a complex
plexus. Other observers, Paschutin, Cissoff, v. Brunn, Schultze, and
Hoffmann oppose this view, and hold that the central processes of the
olfactory cells do not unite with the processes of the epithelial
cells, but that they are in direct continuity with the fibrils of the
olfactory nerve. This view is probably correct.
The submucous layer has a loose connective-tissue matrix, which
encloses the glands, nerves, and vessels; according to Paschutin
two pigment-layers may be distinguished: the one, immediately under
the middle layer of this mucous membrane, is continuous and deeply
pigmented; the second is deeper and does not form a continuous layer.
This layer is extremely rich in blood-vessels and lymphatics (Langer
and Paschutin), (Fig. 240 II). The lymphatics are relatively very large
and are very numerous (Langer).
In this layer the central processes of the olfactory cells form
bundles of fibres, lying parallel with the surface of the mucous
membrane (Paschutin, Cissoff, and Schultze).]
(Re-written by the translator from Das Gehörorgan
der Wirbelthiere, by G. Retzius, 1881.)
The organ of hearing is divisible into two parts, the tympanum or
middle ear, and the labyrinth or internal ear; an external ear is
absent, unless a very slight depression of the tympanic membrane be
regarded as such.
A. The tympanum (Cavum tympani) is a cavity, bounded
externally by the tympanic membrane and internally by the capsule of
the internal ear; it communicates by means of the Eustachian tube (tuba
Eustachii) with the pharyngo-oral cavity (Fig. 178).
Fig. 242.
I.
The tympanic membrane of Rana esculenta; natural size. After Retzius.
II.
The tympanum as seen after removing the tympanic membrane; natural size. After Retzius.
at
Annulus membranae tympani.
col
Columella.
ct
Fissure-like cavity.
dm
M. depressor maxillae.
mt
Tympanic membrane.
sq
Squamosal.
t
M. temporalis.
a. The tympanic membrane lies immediately underneath
the skin, but can be separated from that structure; externally it
possesses a very slight depression, the only trace of an external ear
found in the frog.
The tympanic membrane is of a rounded oval form, being a little
wider in the transverse than in the longitudinal diameter; the membrane
is directed outwards.
After detaching the skin (Fig. 242 I) the membrane is seen to be
attached by its circumference to a ring of cartilage (Annulus
membranae tympani; see also p. 26) (at); the ring is
attached anteriorly and above to the squamosal bone (sq),
and in the rest of its circumference to the surrounding soft parts,
i.e. the M. depressor maxillae (dm), the M.
temporalis (t), and their fasciae. In the middle of the
membrane is a small, rounded, white part (col) which can be
traced backwards and upwards towards the circumference.
The membrane consists of fibres of connective-tissue which radiate
peripherally from the central point of attachment of the columella;
in the peripheral portion unstriated muscular fibres are also found
(Leydig).
Internally the tympanic membrane is covered by columnar
epithelium, a
continuation of the mucous membrane lining the tympanic cavity.
b. The tympanic cavity (Fig. 242 II) is seen, after
removing the tympanic membrane, as a flattened, funnel-shaped cavity.
The walls of the cavity are lined with a pigmented mucous membrane,
under which the cartilaginous ring (annulus membranae tympani)
extends internally to form the greater part of the wall of the cavity.
The cavity is an elongated oval slit (Fig. 242 II, ct), with its
longer axis directed from above and in front, downwards and backwards,
and leading inwards; it is bounded above, below, and in front by
the squamosal, behind by the soft parts; above in the roof is the
cartilaginous part of the columella. The inner or deeper portion
of the tympanic cavity is bounded in front by the squamosal, and by
the squamous process of the prootici (proc. squamosus prootici)
in front and above; internally by the cartilage (primordial-cranium)
between the prootic and the exoccipital; behind by the M. depressor
maxillae. This part of the cavity is rounded and covered with
mucous membrane, and has in its roof the bony part of the columella,
which covers the foramen ovale (fenestra ovalis) by its
oval, widened end-piece. This deeper portion of the cavity communicates
by a short, wide Eustachian tube with the pharyngo-oral cavity; the
tube is wide and is of a rounded oval form in section: anteriorly,
externally, and internally it is bounded by the pterygoids, posteriorly
by soft parts, in which is embedded the styloid process.
The tympanic cavity can be examined from without after removing the
tympanic membrane, or from below by means of the Eustachian tube.
Fig. 243.
The columella; after Retzius. Magnified eight times.
A. Seen from above.
B. Seen from behind.
a′
Extrastapedial (Parker). Outer cartilaginous portion attached to middle of tympanic membrane (Retzius).
a″
Attachment of extrastapedial to mediostapedial.
a‴
Suprastapedial (Parker). Portion embedded in mucous membrane (Retzius).
c. The columella auris (Figs. 12, 243) is described by
Retzius as consisting of three portions, of which the middle is bony,
the external and internal cartilaginous. Parker divides it into four
parts (see pp. 25, 26).
The extrastapedial (Fig. 243 a′, a″) is
attached to the middle of the tympanic membrane by the oval surface
opposite a′, and is attached by the process a‴ to
the annulus tympanicus; this process of Retzius is the
suprastapedial of Parker.
The mediostapedial (Parker), or middle bony piece of Retzius
(Figs. 12a′, 243 b, b′), is narrow externally but
widens internally to articulate with the interstapedial. Just before
reaching the latter it gives off a process (b′), to which are
attached a few fibres of striated muscle (m).
The interstapedial (Figs. 12a, 243 c) is
cartilaginous; it is thick with a sharply cut-off, slightly concave
end, which is placed against the fenestra ovalis. The inner
surface of the interstapedial is, however, distinctly larger than the
opening of the fenestra ovalis, consequently it does not fit
in accurately, but is attached to the border of the opening by means
of connective-tissue; the margins of the fenestra ovalis are
hollowed (Fig. 245 II) so as to form a fossa fenestrae ovalis,
and it is really to the margin of this fossa that the connective-tissue
capsule of the interstapedial is attached.
B. The labyrinth or internal ear is contained in a capsule formed of
bone and cartilage.
a. The capsule of the labyrinth (Fig. 244) is formed
of two bones, the prootic and the exoccipital (according to Hasse this
includes the opisthotic), which are united by cartilage belonging
to the primordial-cranium. The fronto-parietal, squamosal, and
parasphenoid take only an indirect part in its formation.
Fig. 244.
Antero-posterior section through the capsule of the right labyrinth
of Rana esculenta; after Retzius. Enlarged five times.
ac.
Aquaeductus cochleae.
av.
Aquaeductus vestibuli.
cp.
Posterior semicircular canal.
cra.
Canalis rami anterioris acustici.
crp.
Canalis rami posterioris acustici.
fr.
Fenestra rotunda.
fsc.
Fovea sacculi et cochleae.
ft.
Trigeminal foramen.
kn.
Cartilaginous suture.
ol.
Exoccipital.
pr.
Prootic.
ps.
Parasphenoid.
On the whole the anterior half of the capsule is formed by the
prootic, and the hinder half by the exoccipital; the cavity has its
long axis directed from within and above, downwards and outward; the
cavity is comparatively large and rounded, and contains the membranous
ear.
Four surfaces can be distinguished: a supero-external, an
interno-inferior, an anterior, and a posterior (Retzius).
(1) The supero-external surface is divided into two parts
by a strong, transverse, bony ridge, the processus squamosus
prootici. The upper half is concave, is directed upwards and
outwards, and is formed by the prootic; it is separated from the
anterior surface by
a bony ridge, which marks the position of the anterior semicircular
canal. Posteriorly and medianly it is separated from the posterior
surface by a cartilaginous ridge, running from above, downwards and
outwards, which marks the position of the posterior semicircular
canal. The cartilaginous hinder root of the processus squamosus
prootici arises in the cartilaginous ridge just mentioned, and runs
outwards and forwards, covering the external semicircular canal.
The lower half of the supero-external surface (under the
processus squamosus) is irregularly concave; immediately under
the proc. squamosus is a shallow groove in the prootic; it is
continued on the exoccipital to the jugular foramen. The remaining part
of this surface consists of a rounded cartilage, and is part of the
primordial-cranium cartilage between the prootic and the exoccipital;
posteriorly it has a small oval aperture, the foramen ovale
(fenestra vestibulare), which with the groove is covered by
the columella. Above the aperture the cartilage narrows and is
continued to the processus squamosus.
(2) The posterior surface is directly continuous with the
supero-external surface, and is formed by the exoccipital. This
surface lies behind the ridge formed by the posterior semicircular
canal, it is concave, and has two small apertures, separated by a
narrow, bony process, and situated near the jugular foramen; these
are the foramen rotundum (fr.) and the aquaeductus
cochleae (ac.).
(3) The anterior surface is altogether bony and formed by the
prootic (pr.); the anterior surface of this part of the wall is
continuous with the surface of the cranium, and abuts on to the large
trigeminal foramen (ft.); below it is continuous with the under
surface of the cranium, below and externally it articulates with the
pterygoid.
(4) The interno-inferior surface is as a whole hollowed
internally, the upper part being pushed in towards the cranial cavity.
It is formed by the prootic anteriorly, by the exoccipital posteriorly,
and is completed by the cartilage lying between these bones. In the middle of the upper part
of the cartilage is a small oval opening (av.), the ap.
aquaeductus vestibuli: about midway between this aperture and the
jugular foramen is a second opening in the cartilage (cra.), the
opening of the canalis rami anterioris (vestibularis) acustici:
a little behind and above this is the opening of the canalis rami
posterioris (cochlearis) acustici, situated in the exoccipital. The
cartilage between the prootic and exoccipital in the lower half of the
interno-inferior surface rests on the parasphenoid.
b. The position of the soft parts in the
capsule. The large outer, rounded part of the cavity contains the
saccule and cochlea (fovea sacculi et cochleae) (fsc.).
Above, the cavity is more irregular, and contains the utricle and the
sinus utriculi superior. In front and externally, imbedded
in a deep groove, are the anterior and external ampullae (fovea
ampullae anterioris et amp. externae); to these are attached the
corresponding semicircular canals. The anterior semicircular canal
opens above and externally into the canal of the sinus utriculi
superior; the posterior passes into a groove for the posterior
ampulla (fovea ampullae posterioris), and opens above and
internally into the posterior semicircular canal. The external
semicircular canal courses in the processus squamosus prootici,
the posterior in the cartilage (Fig. 244cp) between the
prootic and exoccipital, and the anterior in the prootic. The upper
and posterior part of the anterior semicircular canal is imbedded in
cartilage, on which rests the parasphenoid.
c. The perilymphatic space (Fig. 245 I and II). The
membranous labyrinth does not occupy the whole space enclosed by the
hard parts but is surrounded by the perilymphatic space, which contains
the perilymph. The periosteum and perichondrium form the outer lining
of the space, and are for the most part pigmented:
The perilymphatic space is widest in the lower part of the organ,
in the region of the fovea sacculi et cochleae, especially
externally and behind (per); in front it is much narrower
(per1). A little higher, in the region of the
tegmentum vasculosum, the space is wanting, as the membranous
labyrinth is here attached to the periosteum.
Around the utricle and saccule the space is comparatively wide; it
is continued into the bony canals and ampullae. In the semicircular
canals the space is wider on the concave side than on the convex
side, the membranous canals being placed eccentrically, as are also
the ampullae, though to a less extent. The periosteum and perichondrium lining this
cavity form a very delicate, pigmented membrane, formed of numerous
fine elastic fibres which cross each other irregularly; its inner
surface is lined with an incomplete layer of branched protoplasmic
cells with large oval nuclei. From this membrane numerous irregular
bundles of fibres, in the form of trabeculae, pass into the space and
form a rich network, which is attached internally to the outer surface
of the membranous labyrinth and holds it in position. Free nucleated
leucocytes are occasionally met with in the meshes of this network. The
perilymphatic space is prolonged into two subsidiary cavities:—
Fig. 245.
The membranous labyrinth of Rana esculenta, within its natural covering of periosteum;
after Retzius.
I. Seen from the side; magnified ten times.
II. The hinder half; magnified ten times. Seen obliquely from above, and in front, and from
the side.
aa
Anterior ampulla.
adf
Apertura fenestrae ovalis.
al.
Apertura lagenae.
ap.
Posterior ampulla.
apb.
Opening into the pars basilaris.
ca
Anterior semicircular canal.
ce
External semicircular canal.
cp
Posterior semicircular canal.
dfo
Ductus fenestrae ovalis.
dp
Ductus perilymphaticus.
dp′
Saccus perilymphaticus.
l.
Lagena cochlea.
ms.
Macula sacculia.
pb
Pars basilaris cochleae.
per
Wider part of perilymphatic space.
per1
Narrower part of perilymphatic space.
ra.
Ramus anterior.
rn.
Ramulus neglectus.
rp.
Ramus posterior.
rs.
Ramulus sacculi.
s.
Saccule.
sfo
Saccus fenestrae ovalis.
spl
Saccus perilymphaticus.
tv
Tegmentum vasculosum.
u
Utricle.
(1) The ductus fenestra ovalis (Retzius), (Fig. 245
dfo) commences as an opening (adf) immediately opposite
the foramen ovale of the hard capsule, which leads into a
moderately large canal, the structure under consideration. It passes
forwards and outwards through the fenestra ovalis between
the interstapedial and the outer wall of the capsule into the oval
depression (fossa fenestrae ovalis), and rapidly widens to form a short, flattened,
blind sac (saccus fenestrae ovalis), which is lodged in the
fossa (sfo). Its walls are thin and pigmented.
Fig. 246.
Part of the outer wall of the perilymphatic space:
after Retzius. Vérick’s Syst., Obj. III, Oc. 3.
per.
Periosteum.
pg.
Perilymphatic network.
zn.
Leucocytes.
(2) The ductus perilymphaticus (Hasse), (Fig. 245 dp)
passes above and behind the ductus fenestrae ovalis, behind
the auditory-nerve, and near the cochlea, then behind and above
the lagena to the aquaeductus cochleae (Fig. 244ac), where it forms a short, wide tube, which passes backwards
and inwards through this canal to the canalis jugularis; here
it lies close to the nerves and forms a short oval sac (saccus
perilymphaticus) (dp′), which communicates with the
sub-arachnoid space of the cranial cavity by means of a tube from the
neck of the sac. The walls of this structure are thin and formed of
connective-tissue with very few pigment-cells. The other extremity
of the tube passes to the pars basilaris and under the
sinus post. utri., between it and the pars neglecta;
it then courses to the outer side of the hinder end of the external
semicircular canal: the tube then bends downwards to the outer side
of the utricle and saccule to open into the general perilymphatic
space.
d. The membranous labyrinth (Figs. 247, 248) has the
following parts: the utricle and sinus superior, the recessus
utriculi, the anterior semicircular canal and anterior ampulla,
the external semicircular canal and external ampulla, the posterior
semicircular canal and the posterior ampulla, the saccule, ductus
endolymphaticus, and saccus endolymphaticus, the pars
neglecta, the lagena cochleae, the pars basilaris
cochleae, and the so-called tegmentum vasculosum.
In addition the following nerve-terminations can be distinguished:
(1) The macula ac. recessus utriculi, (2) the three cristae
acusticae ampullorum, (3) the macula ac. sacculi, (4)
the macula ac. neglecta, (5) the papilla ac. lagenae
cochleae, and (6) the papilla ac. basilaris cochleae.
The auditory nerve divides immediately beyond its origin from the
medulla oblongata to form a ramus anterior and a ramus
posterior, which course alongside each other for a short distance,
the latter lying behind and above the former. The R. anterior
runs forwards and
outwards under the utricle, giving off the R. sacculi, which
runs downwards and outwards; the R. rec. utriculi is then
given off as a number of fibres, which run upwards and forwards; the
main nerve then divides to form the R. ampullae anterioris and
the R. ampullae externae, which course together for a short
distance and then separate to reach their respective ampullae. The
R. posterior runs backwards and outwards, gives off the R.
lagenae, and then divides to form the R. neglectus, running
upwards, the R. basilaris running downwards and backwards,
and the R. ampullae posterioris which courses backwards and
outwards.
(1) The utricle (utriculus) (Figs. 247 and 248u) is irregularly cylindrical in form: commencing at the
recessus utriculi it passes forwards and outwards; then
backwards, inwards, and upwards, to terminate at the sinus
posterior, where it is slightly contracted. At about its middle
it is divided into an anterior and a posterior part by an incomplete,
sickle-shaped partition, formed by the posterior semicircular canal
opening obliquely into the utricle, and so causing a fold in the
posterior wall: on the anterior wall there is no fold; the aperture
left in the partition is the apertura utriculi.
The posterior part of the utricle receives the sinus
superior, which is formed by the junction of the two vertical
semicircular canals. The anterior part of the utricle receives the
hinder dilated end of the external semicircular canal by an opening in
its posterior wall, close to the apertura utriculi. In the lower
wall or floor is the narrow opening leading into the saccule
(canalis utriculo-saccularis): this opening is placed with its
long axis parallel to the long axis of the utricle, with its broader
end posterior, and the narrower end anterior.
(2) The recessus utriculi (Figs. 247 and 248rec).
The anterior end of the utricle widens and curves downwards and
outwards to form the recessus utriculi; on its floor is a
thin, kidney-shaped plate or otoliths, resting on the macula ac.
recessus utriculi (mu), which receives the ramulus
rec. utriculi; under it the ramulus amp. anterioris and
the ramulus amp. externae run forwards and close together to
reach their respective ampullae, which are close together at the
antero-external wall of the recessus utriculi. The otolith is
a glassy, homogeneous plate, with numerous vacuole-like spaces and
striated borders; it covers the whole of the macula.
Fig. 247.
Fig. 248.
The right membranous labyrinth of Rana esculenta;
after Retzius. Magnified 20 times. Fig. 247 seen from the inner side;
Fig. 248 seen from the outer side.
aa
Anterior ampulla.
ae
External ampulla.
ap
Posterior ampulla.
apn
Apertura partis neglectae.
au
Apertura utriculi.
ca
Anterior semicircular canal.
ce
External semicircular canal.
cp
Posterior semicircular canal.
cus
Canalis utriculo-saccularis.
de
Ductus endolymphaticus.
l
Lagena cochleae.
mn
Macula acustica neglecta.
ms
Macula acustica sacculi.
mu
Macula acustica recessus utriculi.
pb
Pars basilaris cochleae.
pl
Papilla ac. lagenae.
ppb
Papilla ac. basilaris.
raa
Ramulus ac. anterioris.
rae
Ramulus amp. externae.
rap
Ramulus amp. posterioris.
rb
Ramulus basilaris.
rec
Recessus utriculi.
rl
Ramulus lagenae.
rn
Ramulus neglectus.
rs
Ramulus sacculi.
s
Saccule.
sp
Sinus utriculi posterior.
ss
Sinus utriculi superior.
tv
Tegmentum vasculosum.
u
Utriculus.
(3) The anterior ampulla and semicircular canal
(Figs. 247, 248, aa, ca). The anterior ampulla is a
rounded, oval vesicle, with a depressed roof (Fig. 250 I); on the floor
is a transverse low septum, which bears the crista acustica
(cr) on its free border; seen from above the crista
acustica (Fig. 249 II, aa, cr) has concave borders
anteriorly and posteriorly; the ends are broad, rounded, and somewhat raised; and in the
middle it presents a small elevation (Fig. 249cr). On the
crista acustica rests the cupula terminalis (Fig. 250 I,
cu); this is arched above but of the same form as the crista
acustica below, from which it is separated by an even slit-like
space; the ends are not rounded but hollowed out. The substance of the
cupula is very soft and has parallel striations, formed of fine
fibres and running from above downwards; it separates very easily from
the crista acustica. The anterior ampulla is directed forwards,
outwards, and slightly upwards, to open into the anterior semicircular
canal (canalis m. anterior) (ca), which curves first
upwards and forwards, then backwards, inwards, and upwards, to
open by means of a slightly dilated end into the sinus superior
utriculi.
(4) The external ampulla and semicircular canal
(Figs. 247, 248 ae, ce). The external ampulla lies
immediately external to the anterior ampulla; it also is an oval
vesicle, and corresponds with the anterior ampulla in size and shape,
except that the roof is higher. The roof is directed backwards,
the floor forwards; the septum transversum is low, placed
vertically, and bears a triangular, slightly depressed crista
acustica: the broader, rounded end of the crista is directed
upwards, the apex downwards. The corresponding cupula terminalis
is relatively high, and is of the same shape as the crista,
and is striated. The external ampulla is continuous with the external
semicircular canal (canalis m. externus) (ce), which
courses outwards and backwards; then backwards, inwards, and slightly
upwards, touches the roof of the posterior ampulla; then curves
forwards and inwards to terminate by a slightly dilated end in the
anterior part of the utriculus.
(5) The posterior ampulla and semicircular canal
(Figs. 247, 248, and 249 ap, cp). The posterior ampulla
commences at the posterior end of the sinus post. utriculi,
and is directed outwards and backwards. It corresponds in all other
points with the anterior ampulla. The posterior semicircular canal
(ce) (canalis m. post.), into which the ampulla opens,
curves upwards, inwards, and forwards, to open into the upper end of
the sinus superior.
Fig. 249.
The membranous labyrinth of Rana esculenta; after Retzius.
I.
Part of membranous labyrinth to show relations of the ductus and saccus endolymphaticus to the cochlear part; magnified.
II.
The recessus utriculi and the external ampulla; magnified.
III.
To show tegmentum vasculosum, pars basilaris, pars neglecta, etc.
IV.
To show relations of the cochlear part to the pars neglecta.
aa.
Ampulla anterior.
ae.
Ampulla externa.
al.
Apertura lagenae.
ap.
Posterior ampulla.
apn
Apertura partis neglectae.
au.
Apertura utriculi.
ca.
Canalis m. anterior.
ce.
External semicircular canal.
cp.
Posterior semicircular canal.
cpb.
Opening into pars basilaris.
cr.
Crista acustica.
cus.
Canalis utriculo-saccularis.
de.
Ductus endolymphaticus.
dp.
Ductus perilymphaticus.
l.
Lagena cochleae.
ma.
Macula ac. recessus utriculi.
mn.
Macula ac. neglecta.
mp.
Membrana basilaris.
pb.
Pars basilaris cochleae.
pe′.
Dark spot on either side of crest of ampulla.
pl.
Pars ac. lagenae.
pn.
Pars neglecta.
ppb.
Papilla ac. basilaris.
ra.
Ramus anterior.
raa.
Ramulus amp. anterioris.
rae.
Ramulus amp. externa.
rap.
Ramulus amp. posterioris.
rb.
Ramulus basilaris.
rec.
Recussus utriculi.
rl.
Ramulus lagenae.
rn.
Ramulus neglectus.
rp.
Ramus posterior.
rs.
Ramulus sacculi.
s.
Saccule.
sp.
Posterior semicircular canal.
spl.
Saccus perilymphaticus.
ss.
Sinus utriculi superior.
tv.
Tegmentum vasculosum.
u.
Utricle.
(6) The saccule (s), ductus endolymphaticus (de), and the
saccus endolymphaticus (Figs. 247, 248, 249). The saccule (s)
is an oval vesicle, placed under the anterior part of the utricle and
directed outwards and downwards; below it is flattened in a direction
from in front and within, outwards and backwards; above
it is wider. In the inner and anterior surface is the rounded, oval
macula acustica sacculi (Figs. 247 and 248 ms), to which is distributed
the R. sacculi (rs) from above; a large otolith rests on the
macula and occupies a large portion of the cavity, more especially
the lower portion. The tubular ductus endolymphaticus (de) arises
by a narrow oval opening placed in the upper and inner part of the
wall, runs upwards and to the angle between the utricle and the
sinus superior, continues in the same direction for a short space, and
then curves inwards to pierce the apertura aquaeductus vestibuli, and
so reach the cranial cavity. It then forms a large, thin-walled sac
(saccus endolymphaticus), placed between the brain and cranium.
The sac is very vascular and contains crystalline otoliths.
(7) The pars neglecta (Figs. 247, 248, 249) was described by
Hasse as the ‘first part of the cochlea’ (‘Anfangstheil der Schnecke’),
but according to Retzius it does not belong to the cochlea. It is
placed above and in front of the pars basilaris cochleae, above and a
little behind the lagena cochleae, therefore above the upper and posterior
part of the saccule, and under the middle part of the utricle.
It is really a prolongation of the saccule, with which it communicates
by an elongated oval opening placed externally and immediately
below the opening of the canalis utriculo-saccularis. It is an
oval vesicle, with its roof intimately united with the lower wall of
the utricle; anteriorly it is broad, posteriorly narrowed. The
macula acustica neglecta is attached to the roof of the vesicle and
consists of an anterior heart-shaped and a posterior semilunar
portion united by a narrow connecting piece (Fig. 250 III and VII).
The ramulus neglectus divides into two branches, which supply the
two parts of the macula. On the macula acustica neglecta rests the
membrana tectoria (Deiters); the membrane is S-shaped, with the
anterior end narrow, the posterior broad (Fig. 250 VII); the borders of
the membrane are pierced by numerous small round holes, the central
part has smaller and fewer perforations, and is finely striated.
From the middle of the posterior part of the upper surface a thicker
portion projects downwards into the cavity of the pars neglecta; it
has a narrow, deep notch for the nerve at about its middle; anteriorly
it points towards a sickle-shaped piece, which is curved inwards.
Canals run obliquely downwards and inwards from the
apertures on the superior surface. The membrane is clear, homogeneous,
partly finely striated, and corresponds with the membrana
tectoria of the pars basilaris, etc.
(8) The lagena cochleae (Figs. 247, 248, and 249l) is an oval
swelling of the membranous labyrinth; it lies close to the sacculus
with its broader end forwards, the narrower directed backwards.
By a large rounded opening at the posterior end it communicates
with the saccule by means of a rounded space common to the lagena
cochleae and the cochlea. The papilla acustica lagenae (pl) is situated
in the posterior wall of the lagena; it is elongated, oval, and supplied
by the ram. lagenae. The papilla is covered by a plate-like otolith
formed of numerous rounded particles.
Fig. 250.
The membranous labyrinth of Rana esculenta; after Retzius.
I.
Transverse section of the anterior ampulla. Magnified 50 times.
II.
Piece from under surface of the cupula from the anterior ampulla. Vérick’s Syst., Obj. VIII. Oc. 3.
III.
The macula acustica neglecta, seen from below. Vérick’s Syst., Obj. IV, Oc. 3.
IV.
Part of wall of the anterior ampulla.
V.
Part of the cochlea, the pars basilaris cut longitudinally. Vérick’s Syst., Obj. I, Oc. 3.
VI.
Longitudinal section of the pars basilaris. Vérick’s Syst., Obj. I, Oc. 3.
VII.
The macula ac. neglecta, seen from below. Vérick’s Syst., Obj. IV, Oc. 3.
VIII.
The pars basilaris, seen from behind and the outer side. Vérick’s Syst., Obj. I, Oc. 3.
IX.
Transverse section of the external ampulla. Magnified 175 times.
apb
Oval opening into sacculo-cochlear space.
cr
Crista acustica.
cu
Cupula terminalis.
dp
Ductus perilymphaticus.
mb
Section of thinner wall of pars basilaris.
mt
Tectorial membrane.
mw
Thickened membranous wall.
n
Nerve-fibres.
pb
Pars basilaris.
pe′
Area of coarsely granular cells.
ppb
Papilla acustica basilaris.
r
Epithelium on raphe.
rb
Ramulus basilaris.
rn
Ramulus neglectus.
tv
Tegmentum vasculosum.
(9) The pars basilaris cochleae (Figs. 247, 248, and 249pb) is
placed on the posterior thickened wall of the saccule and lies above
and behind the lagena. It forms a small, oval, pocket-like protuberance,
with the long axis directed from in front and above, backwards
and outwards, its opening being directed forwards and
outwards. The short ram. basilaris passes in from above to supply
it. The walls of this dilatation are thick and stiff, with the exception
of a small portion, the membrana basilaris (Hasse) (mb), which closes
the opening into a small dilatation on the anterior inner wall. The
ramulus basilaris (rb) divides into, at least, two branches, and passes
close to the membrana basilaris (mb), where the elongated and
oval papilla ac. basilaris (Fig. 250ppb) is placed. The papilla
is covered by a membrana tectoria (Fig. 250mt), which is often
found separated from the papilla, probably by the action of the
reagents used. The form of this membrane is peculiar but will
easily be understood from the figure (Fig. 250mt). In structure
it is similar to the corresponding structures found in other parts
of the ear.
Fig. 251.
Preparations from the ear of Rana esculenta; after Retzius.
I.
Part of the membranous wall seen from the surface. Vérick, Obj. VI, Oc. 3.
II.
Transverse section of the membranous wall. Vérick, Obj. III, Oc. 3.
III.
Epithelium from the neighbourhood of the macula ac. rec. utriculi. Vérick, Obj. III, Oc. 3. Oc. 3.
IV.
Branched cells from the yellow spot on the floor of the anterior ampulla. Vérick, Obj. III,
V.
Epithelium from the roof of the anterior ampulla. Vérick, Obj. III, Oc. 3.
re
Epithelium of raphe.
e
Pavement epithelium.
pe
Protoplasmic cells.
pg
Perilymphatic tissue.
(10) The tegmentum vasculosum (Deiters) (Figs. 245, 248, and
250 tv) is an oval, shell-shaped dilatation of the membranous
labyrinth; its long axis is directed from above and in front, downwards
and backwards. The walls of the tegmentum are thin and
intimately attached to the periosteum.
e. The minute structure of the membranous labyrinth
(Figs. 251 252).
(1) The walls of the membranous labyrinth have the same
general structure throughout: the walls are usually thicker at the
nerve-terminations, in the ampullae, semicircular canals, pars
neglecta, and especially the pars basilaris; the wall of the
tegmentum tympani are the thinnest. The walls are transparent,
homogeneous, refractive, and, at places, show a faint striation, which
is, as a rule, not due to the presence of fibres; in parts of the
recessus utriculi, and in the outer wall of the saccule,
especially near the tegmentum vasculosum, more or less distinct
fibres can be made out. Sections of the wall show spindle-shaped
cells, with the processes usually arranged parallel to the surfaces;
seen from the surface, the cells are seen to branch in all directions
(Fig. 251 I, II). In the thinner parts of the walls the cells are few
or altogether absent. The outer surface of the membranous labyrinth is
uneven, in consequence of the attachment of the perilymphatic network.
Blood-vessels are also attached to the outer surface, and pierce the
wall, especially near the nerve-terminations.
The whole of the inner surface is lined with a layer of polygonal,
tesselated epithelium-cells. The size and height of the epithelium
varies in different parts. On the outer wall of the saccule the cells
are large, but on the inner wall small; they are also large in the
semicircular canals, except on a small raphe on the inner and outer
side, where they are smaller but higher (Fig. 251 re); in the
ampullae the cells are large, except on the roof. In the utricle and
sinus superior they are also moderately large. In addition to
the places mentioned, a smaller epithelium is found on the floors
of the ampullae, in the recessus utriculi, and near all the
nerve-terminations and on the sides of the ampullar septa. Surrounding
the nerve-terminations of the macula rec. utriculi, macula
sacculi, and papilla lagenae are found narrow, branched,
yellowish cells (Fig. 251 pe) with spindle-shaped nuclei. Cells
of a third kind, first described by Deiters, Hasse, and Kuhn, in the
tegmentum vasculosum, and in the ampullae by Hasse and Kuhn, are
also found in the utricle. They contain a yellowish pigment, and are
collected into two sharply differentiated groups in each ampulla (Hasse
has one placed before and one behind the septum on the floor). The
cells are cylindrical, the upper parts striated, the lower narrower,
and the bases again widened to a polygonal, more homogeneous plate,
which is fixed to the wall. On the tegmentum vasculosum the
corresponding cells are not so high.
(2) The nerve-terminations. The larger branches of the
auditory nerve contain
medullated fibres of various dimensions and bipolar, spindle-shaped
ganglion-cells. The nerves pierce the walls obliquely or vertically,
and retain their medullary sheaths until near their final distribution.
On each of the nerve-terminations is found nerve-epithelium, which
varies in height in different parts. In the crista acustica
it measures 0.075 mm. in height in the middle part, 0.06 mm. at the
sides; on the macula rec. utriculi 0.09 mm., on the macula
sacculi 0.075 mm., on the papilla lagenae 0.06 mm., on the
papilla part. basil. 0.045 mm., on the macula neglecta
0.075 mm. The epithelium is of two kinds, hair-cells and sustentacular
cells.
Fig. 252.
The nerve-terminations in the membranous labyrinth of Rana esculenta; after Retzius.
I.
Vertical section through the crista acustica of the anterior ampulla. Vérick’s Syst., Obj. III, Oc. 3.
II.
Vertical section through the macula ac. recessus utriculi. Vérick’s Syst., Obj. VIII, Oc. 3.
III.
Three isolated hair-cells from the crista ac. of the anterior ampulla. Vérick’s Syst., Obj. VIII, Oc. 3.
IV.
Two isolated sustentacular cells from the crista ac. of the anterior ampulla. Vérick’s Syst., Obj. VIII, Oc. 3.
cr
Crista acustica.
cu
Cupula terminalis.
fz
Sustentacular cells.
h
Hairs of hair-cells.
hz
Hair-cells.
n
Nerve-fibres.
α. The hair-cells (Fig. 252 hz) have, on the whole,
elongated, flask-like forms, but are not all of the same length
(0.024–0.04 mm.). The free ends of the cells are rounded, flattened,
and yellowish, and each bears a stiff cilium, which is fixed by a
broad base to the cell, and thins out towards its free end: the
cilia vary in length; in the ampullae their greatest length is
0.13 mm., on the macula rec. utriculi 0.011 mm., and on
the papilla lagenae 0.017 mm. The cells are granular, possess rounded oval
nuclei, and are fixed by a fine, narrow process (Fig. 252 hz),
though they usually seem to be rounded off without possessing a
process.
β. The sustentacular cells. Under the hair-cells is a finely
granular substance, possessing numerous rounded oval nuclei, which
are placed in superimposed rows (Fig. 252 fz), the deepest row
being placed close together and immediately on the membranous wall.
After proper treatment and isolation these nuclei are seen to belong
to narrow, elongated cells, which rest by a slightly widened base on
the wall, and are continued upwards between the hair-cells to reach
the surface of the epithelium, where their upper processes are again
slightly widened.
γ. The nerve-fibres (Fig. 252n) lose their medullary
coats, ascend towards the epithelium, and frequently divide to form
two unequal branches, which ascend to the level of the hair-cells,
and curve so as to course horizontally as extremely fine varicose
fibrillae; these frequently form a network, of which the exact method
of termination has not been made out. In some cases a fine fibril may
be traced to the base of a hair-cell, but a direct continuation of the
one into the other has not yet been traced.
(Re-written by the translator.)
The organ of sight, the eyeball (bulbus oculi), together
with its appendages (tutamina oculi), will be described in this
chapter.
A. The Eye is flattened on the outer surface, more
convex on the inner or deeper surface. Its principal axis is directed
from behind, forwards and outwards.
The outer transparent portion of the eyeball is the cornea, which
forms the outer boundary of the anterior chamber. The larger, white,
opaque, and inner portion is the sclerotic coat, which, together
with two deeper tunics, the choroid coat and the retina, enclose the
posterior chamber of the eye. The pigmented ring placed behind the
cornea is the iris, and the aperture it encloses the pupil. The lens is
placed immediately behind the iris. On the inner side the optic nerve
pierces the sclerotic to enter the eyeball.
a. The sclerotic coat (sclerotica s.
sclera) forms about three-fourths of the surface of the eyeball; posteriorly
it is pierced by the optic nerve at a point (porus opticus)
nearer the temporal side than the nasal. The sclerotic coat consists of
fibrous tissue externally, with a layer of hyaline cartilage internally
(Helfreich). The fibrous layer is formed of bundles of parallel
fibres, which cross each other, chiefly at right angles (Hoffmann).
The cartilaginous layer ends just behind the line of insertion of the
extrinsic muscle of the eye, and is thickest at the point of entrance
of the optic nerve (Helfreich).
Fig. 253.
Endothelium from the inner surface of the sclerotic coat; after
Hoffmann.
The sclerotic coat is rich in nerve-fibres, which form a close
network; the fibres, however, do not unite but form the meshes of the
network by simply crossing each at acute angles.
The deeper surface of the sclerotic coat is lined with a layer of
large endothelial cells (Hoffmann), (Fig. 253), which form the outer
wall of the capsule of Tenon.
b. The cornea and the anterior chamber. The
cornea forms about one-fourth of the surface of the eyeball and is
directly continuous with the sclerotic. In it five layers can be
distinguished: a layer of stratified epithelium or conjunctiva, an
anterior hyaline membrane, the true corneal substance, a posterior
hyaline membrane, and a layer of endothelium.
(1) The corneal epithelium is a layer of stratified
epithelium covering the superficial surface of the cornea. The
superficial layer forms a beautiful mosaic of polygonal cells; the
middle layers are polygonal in all sections, while the deepest layer is
more or less columnar. Except in the most superficial layer, all the
cells have serrated surfaces. Smaller cells possessing each two nuclei
are also found between the columnar cells, and are evidently cells in
process of division; according to Waldeyer, cell-proliferation may also
take place in the middle layers.
The basal or deeper portions of the columnar cells possess a clear
border, which reminds one of the hyaline border found on the free
border of columnar epithelium in other parts. The cells are here so
closely applied to one another that these borders have the appearance
of a continuous, highly refracting membrane (Rollett); according to
Henle, the border consists of a network of very fine processes from the
cells above.
(2) The true corneal substance, and (3) the anterior
hyaline membrane.
The corneal substance consists of flat bundles of fibres arranged
in laminae, with cement-substance and connective-tissue corpuscles
interposed. The fibrils are extremely fine (0·0001 mm., Engelmann), and
bound together into bundles by cement-substance. The bundles of the
laminae are arranged at various angles, though many are placed at right
angles to each other (Waldeyer).
Between the laminae are flattened spaces, which seen in section are
spindle-shaped. By proper treatment they are seen to be irregular,
branched spaces, which communicate by fine canals and form part of the
Recklinghausen-canals or lymph-system. These spaces contain branched,
connective-tissue corpuscles (Toynbee), and a colourless fluid.
The corpuscles (Fig. 254 e) do not fill the spaces which
they occupy. They possess large nuclei, surrounded by granular
protoplasm.
Fig. 254.
Preparation from cornea of Rana esculenta; after Klein,
Hartnack’s Syst., Obj. VII, Oc. 3.
a
Nerve of first order.
b
Nerve of second order.
c
Nerve of third order.
d
Nerve of fourth order.
e
Corneal corpuscles.
The canals by which
these spaces communicate (‘Saftcanälchen’ of Recklinghausen) lie,
in general, parallel to the surfaces of the cornea, and communicate
by joining at acute angles or by short transverse branches.
According to Lavdowsky, these canals have a distinct lining
membrane.
The anterior hyaline87 layer (Bowman’s or Reichert’s lamella) is
not so well seen in the frog as in some higher animals; it is simply
a portion of the corneal substance, of somewhat denser structure
than the rest, into which it passes by a gradual transition.
(4) The posterior hyaline membrane (Descemet’s membrane)
is a highly elastic, very transparent layer, placed behind the
true corneal substance; in the frog some few bundles of fibres
belonging to the true corneal substance appear to pass into the
posterior hyaline layer, although they cannot be traced further
through its substance. The structure of the membrane is, in consequence
of its transparency, unknown, though the above observation
seems to point to a fibrillar origin.
(5) The corneal endothelium is a single layer of polygonal
cells of 0·02 mm. diameter. The cells possess the power of altering
their shape when stimulated
(Klebs).
Fig. 255.
Preparation from cornea of Rana esculenta; after
Klein. Hartnack’s Syst., Obj. X immers., Oc. 3.
a
Endothelial cells.
b
Nuclei of endothelial cells.
c
Nerves of third order in the tissue of the cornea propria.
d
Nerves of the fourth order.
(6) The nerves of the cornea are derived from the ramus
ophthalmica trigemini; they pierce the sclerotic coat in front of
the sclerotic cartilage and then course towards the cornea, at the
margin of which they form a coarse network of medullated fibres. From
this about thirty nerves pass towards the cornea, which they enter,
and then very quickly lose the main part of their medullary sheaths.
According to Wolff, a portion of the nerves retain their medullary
sheaths, or in some cases appear to regain it after having lost it.
The nerves passing from the plexus (nerves of the first order,
Klein) give off smaller branches, which for a short distance have a
serpentine or rectilinear course. By a few anastomoses they form a
loose plexus (nerves of the second order, Klein). After a longer or
shorter course they give off numerous lateral fibres, or terminate in
several such fibres arising at one point (nerves of the third order,
Klein). These are distinguished by their size, varying only within
small limits, and by the possession of more or less regularly placed
varicosities; the clearer portions are longitudinally striated as
though made up of fibrillae; they have a nearly rectilinear course,
and, after a longer or shorter course, turn into a direction which
is at right angles to the former one; lastly, they remain for long
distances unbranched. These nerves are connected one with another by
cross fibres running at
right angles to them, and in this way a rectangular trellis-work is
formed.
The fibrils (nerves of the fourth order) given off by these nerves
form networks around the connective-tissue corpuscles, but no direct
connection between nerve and corpuscle has been traced; they always
appear to lie on that surface of the corneal corpuscle which is
directed towards the superficial surface of the cornea (Klein). In the
endothelium covering the membrane of Descemet these fibrils can be
traced coursing along the margins of the cells (Fig. 255 d), and
sometimes undergoing dichotomous division (Klein).
Almost all observers have described these fibrils as possessing
varicosities; Hulke, and more recently Wolf, however, deny their
presence. Lavdowsky traces nerve-fibrils to the nuclei of the
connective-tissue corpuscles.
(7) The anterior chamber is the space between the cornea and
the iris, and is filled with a watery fluid, the aqueous humour. At
the circumference of the chamber are a number of spaces (spaces of
Fontana), formed by interruptions in the tissue between the posterior
surface of the cornea and the iris; the result is that bands or
trabeculae (ligamentum pectinatum iridis) pass from the one structure
to the other, and between these are the spaces of Fontana.
According to Angelucci these trabeculae are of three kinds:
trabeculae passing from the cornea to the iris, formed of connective-tissue;
trabeculae from the cornea to the ciliary processes,
which contain elastic tissue; trabeculae from the interstitial connective-tissue
of the ciliary muscle to the cornea, and formed
almost entirely of elastic tissue.
At the junction of the cornea and sclerotic, and just in front of the
spaces of Fontana, is a larger and similar space, which may be traced
round the whole circumference of the cornea; this, the canal of
Schlemm (Sinus circularis iridis), is held to be a venous plexus by
some observers (Angelucci, and others), according to others it is a
lymphatic space in connection with the anterior chamber (Schwalbe,
and others). It is certain that the vessels can be very easily injected
from the anterior chamber, although a direct communication
has not yet been seen.
c. The choroid coat and the iris (tunica choroidea et iris, tunica
vasculosa).
Fig. 256.
The vessels of the choroid and iris; after Hans Virchow.
I.
The two roots of the V. bulbi superior. Magnified 10 times.
II.
Vessels of the iris. Magnified 9 times.
III.
Origin of the ventral vein.
IV.
Schema of the choroid vessels; seen from the proximal pole.
V.
Transverse section through the choroid at the equator.
VI.
The origin of the choroid arteries from the ophthalmic artery. The greater part of the sclerotic has been removed. Left eye twice natural size. A. From the proximal pole. B. From the temporal side.
VII.
Part of a choroidal artery attached to the choriocapillaris. Magnified 10 times.
VIII.
A portion of the choriocapillaris, more highly magnified.
IX.
The V. ophthalmica and V. bulbi superior on the sclerotic of the right eye. A. Seen from proximal pole. B. Seen from above. Twice natural size.
A
Art. ophthalmica.
A′
Art. choroidea.
An
R. nasalis of the ophthalmic artery.
At
R. temporalis of the ophthalmic artery.
ch
Area of membrana choriocapillaris.
Le
Outer pigmented layer of choroid.
Li
Inner pigmented layer of choroid.
N
Optic nerve.
r
Vasa recta.
r′
Transitional part between choriocapillaris and ventral whorl.
r″
Transitional part between choriocapillaris and upper whorl.
R
Branches of the circulus iridis major.
Rd
Distal root of vein of under surface of eye.
Rd′
Distal root of nasal vein.
Rd″
Proximal root of nasal vein.
Rp′
Nasal root of ventral vein.
Rp″
Temporal root of ventral vein.
Vbs
V. bulbi superior.
Vh
V. hyaloidea.
Vo
V. ophthalmica.
Vp.
Proximal root of vein of under surface of eye.
Vs′
Nasal root of V. bulbi superior.
Vs″
Temporal root of V. bulbi superior.
1. The choroid coat lines the deeper surface of
the sclerotic coat, but is also prolonged under the cornea to form
the iris. The choroid is firmly attached to the sclerotic in two
positions, at the point of entrance of the optic nerve, and at the
line of junction of the sclerotic and the cornea. Its external surface
is closely applied to the deeper surface of the sclerotic, from which
it is only separated by a very narrow serous cavity (supra-choroidal
space), and to which it is attached by numerous vessels and nerves.
The deep surface of the choroid is covered by the retina, to which it
is closely attached, except at the ora serrata, the attachment being
especially intimate at the processus ciliares.
The choroid coat consists of a fibrous layer containing corpuscles
and traversed by a very rich vascular anastomosis. The corpuscles of
this layer are deeply pigmented, in some cases to such an extent that
the oval nucleus cannot be seen; the fibrous tissue is also pigmented,
and has consequently a brownish tinge. That portion of the layer
immediately below the sclerotic is termed the lamina fusca or
suprachoroidea, the vessels on the deeper surface forming the
membrana choriocapillaris. This again is lined on its deeper
surface by a hyaline membrane.
α. The arteries (Fig. 256 VI; VII, VIII) supplying this coat are
two branches of the arteria ophthalmica; these form a capillary
network (Fig. 256 VII) resembling the corresponding structure found
in mammals. The meshes have approximately the same size, while the
capillaries themselves vary considerably in size. This network is,
however, only complete on the nasal, temporal, and proximal part of the upper surfaces.
Towards the corpus ciliare the meshes become wider and
elongated; the capillaries then unite at acute angles parallel with the
longitudinal axis of the eye. The network (choriocapillaris)
exists in a simple layer within the two arteries which form it, and
superficial to the veins (Virchow).
β. The veins of the choroid (Fig. 256 III, IV, IX) are (1) a vein
which unites at the lowest point of the equator of the eye with the
V. hyaloidea to form (2) the V. ophthalmica, two small
branches of the V. bulbi superior, which unite outside the
sclerotic, and (3) the vasa recta.
(1) The larger vein arises from the greater part of the under
surface of the eye; it gives off branches to each side, which radiate
to form a ‘whorl’ or star-shaped capillary anastomosis (Fig. 256
III), the two halves of which have no connection. A proximal and a
distal root can be distinguished in the anastomosis; the distal lies
towards the corpus ciliare, and occupies exactly one-fourth of
the circumference of the choroid at its junction with the corpus
ciliare.
(2) The two branches of the V. bulbi superior lie alongside
the corpus ciliare on the upper surface, and each occupies
one-fourth of the circumference; they form a similar though simpler
figure (Fig. 256 I) to the foregoing, each forming one half.
(3) The vasa recta are numerous parallel vessels which arise
in the iris, and coursing centrally empty themselves into the branches
of the V. bulbi superior on the superior surface, and into the
branches of the venous capillaries on the inferior surface.
2. The iris is covered anteriorly by a layer of
endothelium, continuous with that covering the posterior surface of the
cornea, and of similar character. The border of the pupil (margo
pupillaris) is of a golden colour, outside this bright ring to its
outer margin (margo ciliaris) the iris is black; the golden
colour is due to the presence of cells containing a pale yellow
pigment; the nuclei of these cells are round and granular; the cells
themselves have rounded outlines (Hoffmann). The black portion of the
iris contains more irregular, spindle-shaped cells, with round nuclei,
which are hidden by a dense mass of pigment-granules (Iwanoff and
Hoffmann).
The true substance of the iris consists of muscle, nerves,
blood-vessels, and a connective-tissue stroma, but on the posterior
surface is another layer of black, pigmented cells, and this is again
covered with a hyaline membrane, in which, however, a fibrous structure
may be made out (Koganeï).
The muscle-fibres are long, spindle-cells, which are abruptly
swollen in the middle, where the nuclei are situated; the nucleus is
oval, 0.009–0.0012 mm. in length, 0.0025 mm. broad, and occupies nearly
the whole of the swollen part of the cell (Hoffmann, Grünhagen).
According to Koganeï the iris possesses a M. constrictor
iridis (l. c. Berlin Sitzungsber.), but no M. dilatator
iridis; in a former publication (l. c. Arch. mik. Anat.) he
was unable to find any muscular fibre, and holds the muscle-fibres of
Grünhagen to be connective-tissue elements.
The stroma consists of delicate connective-tissue fibrils, enclosing
a very large number of pigmented, branched cells.
α. The arteries of the iris (Fig. 256 II) arise from an
arch (see Vessels of Eye) formed by the A. ophthalmica in the
corpus ciliare. It commences between the ventral and temporal
surfaces by two branches: one courses along the temporal border, the
other along the nasal, to meet each other on the nasal surface; the
former courses through one-third, the latter embraces two-thirds of the
circumference at the iris.
The temporal artery courses along the ciliary border during the
first third of its course, it then gradually approaches the border of
the pupil; the nasal artery runs at once towards the pupil. On the
nasal border of the pupil they anastomose by their branches, and so
form a circulus iridis major.
Except near their termination, no small vessels arise from this
arterial circle; in Fig. 256 II, for example, only five larger branches
are given off, three from the temporal side and two from the nasal.
The five large branches run towards the circumferential border of the
iris and break up into numerous vessels, which form a very irregular
and open network. From this network arise the vasa recta already
described.
d. The lens is almost spherical, and is composed of
cellular elements enclosed in a capsule (capsula lentis).
The capsule is a homogeneous, transparent, structureless, and highly
elastic membrane. The deeper surface of the anterior capsule is lined
with a simple layer of regular nucleated six-sided epithelial cells.
Fig. 257.
Fibres from the lens of the frog; after Hoffmann. Magnified 700
times.
The lens itself consists of long, flat fibres; seen from the
surface these are broad, narrow edge-wise, and in section six-sided
prisms. Those lying parallel to the anterior and posterior surfaces
are broad and thicker,
those towards the border are narrower. These cells are striated, both
longitudinally and transversely (Arnold). The cells near the margin,
however, have no transverse striation (Hoffmann). The cells of the
central parts form a much closer and firmer structure than those at the
periphery (Arnold). The peripheral cells are nucleated, and sometimes
even possess two nuclei to one cell; the central cells have no nuclei
(Arnold).
The cells are held together by a cement-substance and by their
serrated surfaces; the serrations are the cause of the transverse
striations. The fibres of the lens have a simple arrangement:
commencing at the middle point or pole of one surface they pass over
the equator to the opposite pole; consequently the long borders of
adjacent cells are in juxtaposition, and their pointed extremities meet
at points in the axis of the lens (Hoffmann).
Ritter has described short, nucleated cells in the centre of the
lens; these are held by Babuchin to be cells which have been arrested
in their development.
e. The retina is the innermost coat of the eye; in the
recent state it is pale, soft, and smooth. The structures composing it
are arranged in ten layers; from the deeper surface towards the choroid
these are: the internal limiting membrane, the optic-fibre layer, the
ganglion layer, the inner molecular layer, the inner nuclear layer, the
outer molecular layer, the outer nuclear layer, the external limiting
membrane, the layer of rods and cones, and the pigment layer.
These layers are held together by connective-tissue elements.
Fig. 258.
Vertical section through retina of frog; after Hoffmann. Magnified
500 times.
a
Internal limiting membrane.
b
Ganglion-cell layer.
c
Internal molecular layer.
d
Internal nuclear layer.
e
External molecular layer.
f
External nuclear layer.
g
Layer of rods and cones.
h
Pigmented epithelium layer.
1.
Inner segments of rods and cones.
2.
Outer segments of rods and cones.
3.
Outer transparent segments of pigmented epithelium.
(1) The internal limiting membrane (Membrana limitans
interna) will be described together with the connective-tissue
elements (10).
(2) The optic-fibre layer is formed by the fibres of the
optic nerve. The nerve-fibres in their course towards the eye are
possessed of medullary sheaths, but on piercing the sclerotic these
sheaths are lost. The fibres are now pale, non-medullated, and of very
varying thickness. In the mass of fibres nothing can be seen except
an extremely fine fibrillation and very fine varicosities; the latter, however, appear to be
artificial productions (Hoffmann). This layer of fibres extends over
the inner surface of the retina, and gradually thins from the point of
entrance of the optic nerve to the limits of the retina.
(3) The ganglion-layer lies immediately without the
nerve-fibre layer (Fig. 258 b). The ganglion-cells are small and
usually pear-shaped. The cells possess large nuclei, round which is a
thin layer of very granular protoplasm. The cells have inner and outer
processes; the inner pass into the nerve-fibre layer, the outer into
the inner molecular layer in more or less radiating directions. Manz
claims to have traced a direct connection between the inner processes
and the fibres of the nerve-fibre layer.
Each ganglion-cell, whatever its shape or size, has only one inner
process, which is easily distinguished from the outer process by its
being more glistening, by the possession of varicosities, and because
this process never branches.
The outer processes are single (Schwalbe) or rarely double
(Hoffmann), and have as a rule a direction at right angles to the inner
processes. Each outer process is finely granular, which suggests rather
a prolongation of the cell-substance than a true process. Frequently
they are branched, sometimes forming two equal sized processes, which
give off finer twigs; at other times they appear to pass through
the whole of the inner molecular layer without undergoing division
(Schwalbe). The processes do not inosculate (Santi Sirena).
(4) The inner molecular layer (Fig. 258 c) is
0·07–0·08 mm. thick (Hoffmann), and consists of a finely granular mass together with
the outer processes of the ganglion-layer, and connective-tissue
elements.
The granular matter consists of an extremely fine network or
reticulum, through which numerous fine fibres course (Schultze,
Kölliker, Manz, Heinemann, and others); according to Schultze the
supposed molecules or granules of others (Henle, Merkel, and Retzius)
are simply the fine meshes of this reticulum. The branched, outer
processes of the ganglion-cells form a rich anastomosis in this
layer.
(5) The inner nuclear layer (Fig. 258 d) contains
parts of two kinds of cellular elements; these are radial nerve-fibres
with large nuclei, and connective-tissue elements (see below, par.
10). The nerve-fibres are easily distinguished by their spindle-shaped
varicosities; both cellular elements possess large oval nuclei. The
bodies of the cells surrounding the nerve nuclei are almost filled by
the nuclei, which have sharply-defined, rounded nucleoli. The fibres
to which these cells are attached may be distinguished as inner and
outer processes; the inner process is fine, irregularly varicose, and
unbranched; the outer process is thicker, finely granular, and is not
varicose (Schwalbe). At the margin of the outer molecular layer the
outer processes divide, usually into two branches, and at an acute
angle to each other, though sometimes at a right angle. The further
course of these branches in the outer molecular layer is unknown.
(6) The outer molecular layer (Fig. 258e) corresponds
in general with the inner molecular layer as regards its structure; it
is, however, much thinner.
(7 and 9) The outer nuclear layer and the layer of rods
and cones (Figs. 258f, g, 259). The rods and cones
are intimately connected with the elements of the outer nuclear layer,
hence the two layers are best described together.
The rods (bacilli) have two parts or limbs, an outer and
an inner, which differ in structure, and in chemical and physical
characters. The outer part is highly refractive, the inner more
homogeneous and less refractive, the two parts being sharply
differentiated from one another.
The outer part is also weakly doubly refracting, the inner has no
trace of this property. The rods are 0·05–0·06 mm. in length, of which
0·035–0·04 mm. belongs to the inner limb. The outer end of the outer
limb is more or less rounded; the whole has a longitudinal striation
(Schultze), due to its being composed of rounded fibrils, about twenty-four to each rod
(Hensen). The fibrils are sharply differentiated from each other and
have a slightly spiral course; when seen in transverse section these
outer limbs do not appear to be round (Schultze), although others hold
them to be perfectly rounded (Hoffmann and others), and that the loss
of the cylindrical form is due to the methods of treatment. According
to Merkel the longitudinal striation is caused by a canalisation of
the outer limb, which according to him encloses the processes of the
pigmented epithelial layer; he is also of opinion that the spiral
appearance is an artificial product. In the latter opinion he is
probably wrong, as perfectly fresh rods examined in aqueous humour
show the same spiral appearance (Hoffmann): against the canalisation
view others observe that the longitudinal striation is most distinct
near the inner limit of the outer limb, and that it is impossible to
conceive that the processes of the pigment-cells should terminate with
such extremely regular ends (Hoffmann).
Fig. 259.
Various preparations from the eye of the frog:
chiefly from the retina.
1.
Rod from retina in aqueous humour, showing spiral striation.
2.
Three rods and one cone after treatment with osmic acid.
3, 4, 5. Rods examined in recent state.
6, 7. Inner segments of two rods after treatment with osmic acid.
a
Outer limb.
b
Inner limb.
c
Lenticular body.
d
Nucleus of outer nuclear layer.
e
External limiting membrane.
8.
Nuclear body from inner nuclear layer.
9.
Twin-cone.
10.
Sustentacular fibre of retina.
11.
Surface view of pigmented epithelium of retina.
12, 13. Isolated pigmented cells of retina.
14.
Four pigmented cells, rods and cones, external limiting membrane, and part of outer nuclear layer attached.
15.
Two pigmented cells; each showing three attached rods.
16.
Muscle-fibre from the iris.
Figs. 1, 2, 3, 4, 5, 6, 7, 8, 9 are magnified 500 times. Fig. 10,
300 times. Fig. 16, 400 times. All are copied from Hoffmann’s
figures.
Figs. 12, 13, 14, 15 are copied from Morano’s figures; Hartnack,
Oc. II, Obj. 9.
In the central part of the inner end of the outer limb is
seen a dark point when the structures are examined in transverse
section (Ritter, Manz, Schiess, Schultze, and others). The cause of this is not clearly
understood; some hold it to be a fibre (Ritter’s fibres), others hold
it to be an artificial product (Hensen).
After treatment with certain reagents the outer limbs show a
transverse striation, which is probably produced by the action of
these reagents on the sheath of the outer limbs; that a sheath is
present is proved by its possession of a different refractive index
(Zenker, Schultze) to the rest of the outer limb, and this transverse
striation is not seen until the whole organ has undergone considerable
post-mortem changes (Hoffmann). Should this change be allowed to
proceed a stage further, the outer limbs of the rods split transversely
and form small discs from 0·0005–0·00055 mm. thick; this takes place in
the outer limb only.
The inner segments of the rods (Figs. 258, 259) are short
(0·020–0·022 mm.) and of the same thickness as the outer limbs. When
perfectly fresh they appear homogeneous; very quickly changes commence,
which are probably due to coagulation. A plano-convex figure (Fig. 259)
is then seen at the outer portion of the segment (lens-shaped figure
of Schultze); with staining reagents it gives the same reactions as
the outer segment of the rods. The rest of this segment forms a short
cylinder, which probably has no distinct sheath (Hoffmann, Merkel);
some observers are inclined to think that a sheath exists (Landolt,
Schwalbe).
The outer segments of the rods are of two chief sizes (Schwalbe).
Those of the one kind are large; the second variety occurs less
frequently, and the segments are shorter, measuring only 0·002 to
0·0025 mm. The inner segment is a long, thread-like process, except
where it is swollen to enclose the lens-shaped body.
The rods are much more numerous than the cones, except at one small
spot (macula lutea) on the posterior surface of the retina,
where only cones are found (Krause).
The cones (coni) have each two segments like the rods
(Figs. 258, 259). The outer segments are short (4–5 µ), they are
slightly conical and terminate externally in a blunt point; they
possess a longitudinal striation (Schultze), and very easily break
up transversely into small discs, which, however, do not separate so
completely as in the case of the rods, in consequence of the presence
of a sheath continuous with a sheath on the inner segment.
The inner segments (Figs. 258, 259) have convex sides and measure
12–14 µ; like the corresponding parts of the rods they possess
lens-shaped bodies at their junction with the outer segments, but the bodies differ in
shape, being bi-convex or rather oval in form. The inner segments
are enclosed in a delicate sheath continuous with that of the outer
segments.
In some cases two cones are united to form a twin-cone; in such
cases the one is always larger than the other (Fig. 259 9), and has several peculiarities which
distinguish it from the smaller.
The smaller or secondary member of a twin-cone is longer, and
possesses a lens-shaped body which is plano-convex. The larger or
principal member of a twin-cone is shorter, has a plano-convex body,
but also an oval, homogeneous, glistening body, which is directly
attached to the plano-convex body. The shape of the two members is also
different.
The outer nuclear layer (Fig. 258f) is 14–16 µ thick;
the nuclei lie in two layers. The nuclei belonging to rods and cones
have the same characters, each nucleus being a large, oval, hyaline
body, and enclosing a bright nucleolus. Each nucleus is surrounded by
an extremely thin layer of finely granular matter. The inner processes
of the nuclear bodies both of the rods and the cones extend to the
outer molecular layer, are there dilated and serrated, where they
become attached to the outer molecular layer (Schultze, Hoffmann). In
some cases, however, the inner process of the nuclear bodies, belonging
to the rods, forms only a short fine fibre.
In the case of twin-cones the corresponding parts in the outer
nuclear layer possess two nuclei (Schultze).
(8) The pigment layer (Figs. 258h, and 25911, 12, 13, 14, 15) is not intimately attached
to the rest of the retina. It consists of cylindrical cells in which
two parts or segments are sharply differentiated; the external part,
directed towards the choroid coat, is of pale, or colourless granular
protoplasm, and occupies one-third of the length of the cell; this part
encloses a large, round, nucleolated nucleus. This colourless segment
of the cell also includes one or two bright yellow, fat globules
(Morano). Seen from the surface the cells are hexagonal (Fig. 25911). The remaining two-thirds of the cells
consists of a brush formed of numerous fine pigmented processes; the
ultimate terminations of the processes, which lie parallel to each
other, are frequently unpigmented; each cell possesses thirty to forty
such processes (Morano).
The processes extend between the rods and cones as far as the
external limiting membrane (Figs. 258, 259), or sometimes a little
further (Merkel, Morano, Hoffmann). The processes from one pigment-cell
surround a number of rods and cones; according to Morano twelve to fifteen rods and cones may be
encased or surrounded by the processes of a single cell.
The thickness of this layer varies from 60–70 µ; the nuclei of the
cells have a diameter of 10–12 µ, the width of a single cell is from
20–25 µ (Hoffmann).
(10) The connective-tissue elements of the retina and the
external and internal limiting membranes. The elements of
the retina are supported by connective-tissue elements or sustentacular
cells, which have a radial arrangement, and which form the two limiting
membranes (Müller).
Each sustentacular cell (Fig. 25910)
has two segments, an inner and an outer, the boundary between these
lying in the inner nuclear layer, and being marked by the presence
of a large oval nucleus. The inner segment of each cell terminates
internally in a wide ‘foot’ or base, or may form several such after
having undergone division (Schultze): these bases together form a
transparent, thin membrane, the internal limiting membrane (membrana
limitans interna).
Within the ganglion-layer these cells possess peculiar appendages,
which fit round the ganglion-cells and support them (Schwalbe).
The outer segments of the sustentacular cells extend into the outer
molecular layer, and then break up into irregular processes which
extend radially to the external limiting membrane, and which they
probably form. The external limiting membrane (membrana limitans
externa) is therefore a membrane corresponding to the internal
limiting membrane, and formed by the flattened ends of the processes
belonging to the sustentacular cells.
The sustentacular cells have a distinct, resistant cell-wall
(Schwalbe); the cell-contents are a finely granular protoplasm, and a
large oval, nucleated nucleus placed in the inner nuclear layer.
f. The ciliary processes have the same structure
as the rest of the choroid coat: the vessels form more or less
longitudinal meshes and are more irregular than in the rest of the
choroid.
g. The posterior chamber and vitreous body
(Fig. 260). The vitreous humour occupies the greater portion of the
cavity of the eyeball, i.e. the posterior chamber. The humour
consists of a mass of cells enclosed in a transparent hyaloid membrane
(membrana hyaloidea), which is in contact with the internal
limiting membrane of the retina.
The cells forming this structure are small, flattened,
transparent, and
nucleated (Iwanoff and Virchow); according to the former observer the
cells have contractile powers.
The hyaloid membrane is described as structureless by Schwalbe, as
fibrous by Pappenheim, Bowman, and Fuikbeiner.
The vessels of the vitreous body (Fig. 260) are as follows. The
A. hyaloidea arises at the lowest point of the corpus
ciliare; it almost immediately divides into two branches, which
form a ring at a distance of about 0·5 mm. from the lens and lying
on the surface of the vitreous body (Fig. 260 I, II). One, R.
nasalis, passes to the nasal side and courses through one-fourth
of the circle; the other, R. temporalis, courses through
three-fourths of the circle. The branches are all given off proximally
and at right angles to the circle (Fig. 260 I, II). From the R.
nasalis only one branch arises, from the R. temporalis
seven, the first of which corresponds in point of origin with the
branch from the R. nasalis. The branches on the nasal and
temporal surfaces of the vitreous body are the shortest.
Fig. 260.
The vessels of the vitreous body; after Hans Virchow.
I.
Vessels of the vitreous body; seen from the deeper pole and slightly from above. Magnified 6 times.
II.
Arteries of the vitreous body of the right eye.
A
Seen from the proximal pole.
B
Seen from the nasal side.
III.
Veins of the vitreous body of the left eye.
A
Seen from the proximal pole.
B
Seen from the nasal side.
a
Nasal vein.
b
Temporal vein.
c
Branch (constant) of temporal vein.
n
R. nasalis of the ophthalmic artery.
t
R. temporalis of the ophthalmic artery.
t′
Termination of the R. temporalis.
V
Ventral vein.
These branches form a capillary network (Fig. 260 I) with elongated
meshes, formed by the capillaries anastomosing at acute angles. The
capillary network is more dense towards the middle of the proximal
surface than in other parts.
The veins arising from this network are three in number (Fig. 260
III); two of these accompany the arteries from their origin, and form
a somewhat similar circle around the lens, while the third passes
backwards along the ventral surface of the vitreous body to the
papilla nervi optici. The nasal vein, however, takes a more
proximal course than the corresponding artery, the branches of which
it crosses; consequently the venous ring is not so perfect as the
arterial. The nasal vein is larger and the temporal vein smaller than
the corresponding arteries.
The ventral vein is formed near the papilla nervi optici
by the union of two smaller branches. The capillary system of these
vessels has the usual structure of capillaries, the cells being united
by cement-substance (Zimmermann).
The blood-vessels of the vitreous body are accompanied by
lymphatics; according to Iwanoff they completely enclose the
capillaries: Zimmerman contradicts this view, as he has been unable to
find lymphatics on that side of the capillaries directed towards the
vitreous body.
B. Appendages of the eye.
The appendages of the eye are the eye-muscles (see pp. 55–59), the
eyelids, the Harderian gland, and the lachrymal duct.
a. The eyelids are two in number, an upper and a
lower. The upper eyelid is intimately attached to the eyeball and
follows the movements of that organ.
The lower eyelid (membrana nictitans) is much larger
than the upper and has the same functions as the lower eyelid of higher
vertebrates. It forms a transparent covering for the eyeball, and is
raised by a special muscle (see p. 58); functionally it takes the place
of both eyelids of higher vertebrates.
The lower eyelid is a prolongation of the skin, but has only a
few pigment-cells, except at its free margin, and no serous glands.
Mucous glands are found in two or three rows, closely applied to
one another, on the superficial surface of the lid; on the deeper
surface they are wanting. The stroma of the lid, like the cutis, is of
connective-tissue.
Nerve-fibres can be traced in all directions through the
substance of the lid,
forming a wide-meshed plexus. Around each gland the plexus becomes
finer and by numerous branchings much closer; from the plexus twigs are
given off, which divide to form a number of fibrils traceable into the
epithelial cells of the glands (Openchowski).
The vessels of the lower eyelid have been investigated by Stricker,
(l. c.); according to him they possess some interesting
peculiarities. Many of these capillaries course within a lymphatic
vessel, in some places the capillary being contracted by a projection
from its inner wall; where this is found the accompanying lymphatic
is correspondingly dilated. Such points are especially met with where
the capillaries branch; in many cases the capillary was contracted
to such an extent that the blood-corpuscles were unable to pass the
obstruction. Stricker further observed in the living tissue that such
constrictions could take place in a part which a short time previously
had been comparatively wide and dilated; further, that many of the
nerves were enclosed in similar lymphatics. Langer, however (l.
c.), describes the vessels as being accompanied by an irregular
network of small lymphatic vessels.
Fig. 261.
Preparations from the nictitating membrane of Rana
esculenta to show distribution of nerves.
I.
Preparation of the nictitating
membrane to show nervous supply to a capillary vessel; after Klein.
Hartnack, Oc. III, Obj. 8.
a
Capillary vessel.
b
Blood-corpuscles.
c and d Non-medullated nerve-fibres.
II.
To show distribution of nerves in the epithelium; after Klein. Hartnack, Oc. IV, Obj. 8.
a
Subepithelial nerve-fibres.
b
c
Fine fibrils between the deepest epithelial cells.
d
Deepest epithelial cells.
The distribution of the nerves in the lower eyelid has been
described by Klein. In the epithelium they form a network resembling
that found in the cornea (Fig. 261 II); along the blood-vessels
the fine fibrils form a perivascular network, which supplies fine twigs to the walls of
the vessels (Fig. 261 I). He distinguishes three kinds of pigmented
cells.
b. The Harderian gland is situated at the inner
angle of the eye, and is pear-shaped in form. It consists of a
number of racemose glands held together by connective-tissue, the
whole being enclosed in a relatively thick and strong capsule of
connective-tissue.
The alveoli have a diameter of 0·040–0·060 mm.: they possess a
lining of epithelium and a lumen which varies considerably in size.
The epithelial layer is bounded externally by a membrana propria. The
cells are placed eccentrically, they are cylindrical, and composed of
finely granular protoplasm; each cell contains a pale, rounded nucleus.
The ducts of the alveoli are lined with a single layer of cylindrical
epithelium, the cells of which are usually shorter and narrower than
those of the epithelium of the alveoli; the ducts open into a single
main tube, lined with similar epithelium but strengthened externally by
a layer of connective-tissue. The glands secrete a fluid which moistens
the free surface of the eye.
The Harderian glands are surrounded by a rich capillary anastomosis
which completely invests the alveoli.
c. The lachrymal duct opens behind and below into the
nasal cavity (see p. 389), anteriorly it can be traced forwards, as a
small tube imbedded in connective-tissue and lying immediately beneath
the skin, to the outer angle of the eye, where it opens by numerous
tubules.
The lachrymal duct is lined with ciliated columnar epithelium.
ADDENDA.
HISTOLOGY OF MUSCLE, CARTILAGE, BONE, AND THE CONNECTIVE TISSUES.
LITERATURE.
I. MUSCLE AND NERVE-ENDINGS IN MUSCLE.
Arnold, J., Gewebe der organischen Muskeln. Stricker’s
Gewebelehre, 1871. Vol. I, p. 142.
Arnold, J., Ueber die Abscheidung des indigschwefelsauren
Natrons im Muskelgewebe. Virchow’s Arch. Vol. LXXI, p. 1.
Babuchin, Ueber den feineren und Ursprung des Axencylinders.
Centralbl. f. med. Wiss. 1868, p. 755.
Barfurth, D., Die Rückbildung des Froschlarvenschwanzes und
die sogenannten Sarkoplasten. Arch. f. mik. Anat. 1887. Vol. XXIX,
p. 35.
Biedermann, W., Zur Lehre vom Bau der quergestreiften
Muskelfaser. Wiener Sitzungsber. 1876. Vol. LXXIV, Pt. III,
pp. 49–62.
v. Biesiadecki, A., and Herzig, A., Die verschiedenen
Formen der quergestreiften Muskelfasern. Wiener Sitzungsber. 1859,
Vol. XXXIII, p. 146: and in Moleschott’s Untersuchungen, 1860, Vol. VI,
p. 105.
du Bois-Reymond, E., Ueber facettenförmige Endigung der
Muskelbündel. Berlin. Acad. Monatsber. 1872, pp. 791–814. Abstract in
Centralbl. f. d. med. Wiss. 1873. No. 55, p. 868.
Bowman. On the minute structure and movements of voluntary
muscle. Phil. Trans. 1840, p. 457.
Bremer, L., Ueber die Endigungen der markbaltigen und
marklosen Nerven im quergestreiften Muskel. Arch. f. mik. Anat. 1882.
Vol. XXI, p. 165.
Bremer, L., Ueber die Muskelspindeln nebst Bemerkungen über
Structur, Neubildung, und Innervation der quergestreiften Muskelfaser.
Arch. f. mik. Anat. 1883. Vol. XXII, p. 318.
Calberla, E., Studien über die Entwicklung der
quergestreiften Muskeln und Nerven der Amphibien und Reptilien. Arch.
f. mik. Anat. 1875. Vol. XI, p. 442.
Calberla, E., Ueber die Endigungsweise der Nerven in den
quergestreiften Muskeln der Amphibien. Dissert. Freiburg i. B. 1874;
also in Zeitschr. f. d. wiss. Zool. 1874. Vol. XXIV, pp. 164–178.
Chittenden, R. H., Histochemische Untersuchungen über das
Sarkolemm und einige verwandte Membranen. Untersuch. d. physiol.
Instituts d. Universität Heidelberg. Vol. III.
Cohnheim, J., Ueber die Endigung der Muskelnerven. Centralbl.
f. d. med. Wiss. 1863, p. 865.
Eberth, C. J., Untersuchungen über die normale und
pathologische Leber. Virchow’s Arch. 1864. Vol. XXXIX, p. 74.
Engelmann, T. W., Zur Lehre von der Nervenendigung im Muskel.
Jenaische Zeitschr. 1868. Vol. IV, p. 307.
Engelmann, T. W., Untersuchungen über den Zusammenh. von
Nerven u. Muskelfasern. Leipzig, 1863.
Engelmann, T. W., Microscopische Untersuchungen über die
quergestreifte Muskelsubstanz. Pflüger’s Arch. 1873. Vol. VII,
pp. 33–71, and pp. 155–187.
Engelmann, T. W., Ueber die Endigung der motorischen Nerven
in den quergestreiften Muskeln der Wirbelthiere. Centralbl. f. med.
Wiss. 1863, p. 289.
Ewald, A., Ueber die Endigung der motorischen Nerven in den
quergestreiften Muskeln. Pflüer’s Arch. 1876. Vol. XII, p. 529.
Ewald, A., and Kühne, W., Die Verdauung als
histologische Methode. Heidelb. naturhistor.-med. Verhandl. 1877.
Vol. I, p. 451.
Exner, S., Notiz zu der Frage von der Faserverteilung
mehrerer Nerven in einem Muskel. Pflüger’s Arch. 1885. Vol. XXXVI,
p. 572.
Fischer, E., Ueber die Endigung der Nerven im quergestreiften
Muskel der Wirbelthiere. Arch. f. mikrosk. Anat. 1877. Vol. XIII,
p. 365.
Froriep, A., Ueber das Sarcolemm und die Muskelkerne. Arch.
f. Anat. u. Physiol. 1878, p. 416.
Gerlach, J., Ueber das Verhalten der Nerven in den
quergestreiften Muskelfäden der Wirbelthiere. Sitzungsb. Erlangen.
1873. Vol. V, p. 97; Abstract in Centralbl. f. d. med. Wiss. 1874,
p. 227.
Gerlach, J., Das Verhältniss der Nerven zu den willkürlichen
Muskeln der Wirbelthiere. Leipzig, 1874.
Gerlach, J., Ueber das Verhältniss der nervösen und
contractilen Substanz des quergestreiften Muskels. Arch. f. mik. Anat.
1877. Vol. XIII, p. 399.
Golgi, C., Sui Nervi dei Tendini dell’ Uomo e di altri
Vertebrati e di un nuovo Organo Nervoso terminale Musculo-tendineo.
Torino. Estr. dalle Memorie della Reale Acc. di Torino. Series II.
1880, Vol. XXXII.
Grützner, P., Zur Anatomie und Physiologie der
quergestreiften Muskeln. Recueil Zoolog. Suisse, 1884. Vol. I,
pp. 665–684.
Haycraft, J. B., Upon the cause of the striation of voluntary
muscular tissue. Quart. Journ. Micros. Soc. 1881. Vol. XXI, p. 307.
Hensche, Ueber die Drüsen und glatten Muskeln in der äusseren
Haut von Rana temporaria. Zeitschr. f. wiss. Zool. 1856. Vol. VII,
p. 273.
Hensen, V., Ueber die Entwicklung des Gewebes und der Nerven
im Schwanze der Froschlarve. Virchow’s Arch. 1864. Vol. XXX, p. 51.
Jakimovitsch, Ueber die Regeneration der glatten
Muskelfasern. Centralbl. f. d. med. Wiss. 1879, p. 897.
Key, A., Bidrag till Nervernas ändningsätt i Musklerna.
Förhandlingar vid Skandinaviska Naturforskaemötet i Stockholm, 1863.
Abstract in Centralbl. f. d. med. Wiss. 1866, p. 212. (Muscles of
frog’s tongue.)
Klebs, E., Die Nerven der organischen Muskeln. Centralbl. f.
d. med. Wiss. 1863, p. 561.
Klebs, E., Die Nerven der organischen Muskeln. Virchow’s
Arch. 1865. Vol. XXXII, pp. 169–198.
v. Kölliker, A., Gewebelehre.
v. Kölliker, A., Einige Bemerkungen über die Endigung der
Hautnerven u. den Bau der Muskeln. Zeitschr. f. wiss. Zool. 1857,
Vol. VIII, p. 311.
Krause, W., Ueber den Bau der quergestreiften Muskelfaser.
Zeitschr. f. rat. Med. Vol. XXIII.
Krause, W., Die Nervenendigungen in den Froschmuskeln.
Internat. Monatschr. 1884. Vol. I, pp. 194–203.
Krause, W., Die motorischen Endplatten, etc. Hannover,
1869.
Krause, W., Ueber die Endigungen der Muskelnerven. Göttinger
Nachrichten. 1863, p. 21.
Krause, W., Ueber die Endigungen der Muskelnerven. Henle and
Pfeufer’s Zeitschr. 1863. Vol. XX, pp. 1–19.
Kühne, W., Untersuchungen über Bewegungen und Veränderungen
der contractilen Substanzen. Arch. f. Anat. n. Phys. 1859, p. 816.
Kühne, W., Die Muskelspindeln. Virchow’s Arch. 1864.
Vol. XXVIII, pp. 528–538.
Kühne, W., Untersuchungen über das Protoplasma und die
Contractilität. Leipzig, 1864.
Kühne, W., Ueber die peripherischen Endorgane der motorischen
Nerven. Leipzig, 1862.
Kühne, W., Zur Lehre von den Endplatten der Nervenhügel.
Virchow’s Arch. 1866. Vol. XXXIV, pp. 412–422.
Kühne, W., Ueber das Verhalten des Muskels zum Nerven.
Verhandl. d. natur-hist.-med. Vereins zu Heidelberg. 1880. Vol. II,
p. 227.
Kühne, W., Ueber Nervenendigungen in den Muskeln nach
Beobachtungen von M. B. van Sykel. Abdruk. aus den Verhandl. d. Naturh.
med. Verein zu Heidelberg. 1884. Vol. III, pp. 238–242.
Kühne, W., Wiederlegung der Bemerkung E. du Bois-Reymond’s
über mehrfache. Nervenendigungen einer Muskelfaser. Zeitschr. f. Biol.
1884. Vol. XX, pp. 531–539.
Kühne, W., Ueber die Endigung der Nerven in den Muskeln.
Virchow’s Arch. 1866. Vol. XXVII, pp. 508–533.
Kühne, W., and Voit, C., Neue Untersuchungen über
motorische Nervenendigung. Zeitschr. f. Biologie. Vol. XXXIII.
Lavdowsky, M., Die feinere Struktur und die Nervenendigungen
der Froschharnblase. Arch. f. Anat. u. Physiol. 1872, p. 55.
Leboucq, H., Recherches sur le développement et la
terminaison des nerves chez les larves des Batrachiens. Bull. de
l’Acad. de roy. de Belgique. 1876. Vol. XLI, p. 561.
Letzerich, L., Ueber die Endigungsweise der motorischen
Nerven. Med. Centralz. 1863, No. 37.
Leydig, F., Ueber Tastkörperchen und Muskelstructur. Arch. f.
Anat. u. Physiol. 1856, p. 150.
Löwit, Die Nerven der glatten Muskulatur. Sitzungsb. d.
Wiener Acad. 1875. Vol. LXXI, Pt. III, p. 355.
Marshall, C. F., The structure and distribution of striped
and unstriped muscle. Quart. Journ. Micros. Sci. 1887. Vol. XXV.
Martin, H., Sur la structure de la fibre musculaire striée et
sur les analogies de structure et fonction entre les tissus musculaires
et les cellules à bâtonnets (protoplasma strié). Arch. de physiol.
norm. et pathol. 1882, p. 465.
Mayer, S., Die sogenannten Sarkoplasten. Anat. Anzeiger,
1886. No. 9, p. 231.
Mayer, S., Einige Bemerkungen zur Lehre von der Rückbildung
der quergestreiften Muskelfasern. Prager Zeitschr. f. Heilkde. 1887.
Vol. VIII, p. 177.
Mays, K., Histo-physiol. Untersuchungen über die Verbreitung
der Nerven in den Muskeln. Zeitschr. f. Biol. Vol. XX.
Mays, K., Ueber die Nervatur des Musculus rectus abdominis
des Frosches. Heidelberg, 1886.
Melland, B., A simplified view of the histology of the
striped muscle-fibre. Quart. Journ. Micros. Sci. 1885. Vol. XXV,
p. 371.
Merkel, F., Der quergestreifte Muskel. Arch. f. mik. Anat.
1873. Vol. IX, pp. 293–367.
Minra, M., Untersuchungen über die motorischen
Nervenendigungen der quergestreiften Muskelfasern. Virchow’s Arch.
1886. Vol. CV, p. 129.
Nasse, O., Zur Anatomie und Physiologie der quergestreiften
Muskelfasern. Leipzig, 1882. Abstract in Centralbl. f. d. med. Wiss.
1882, pp. 884 and 908.
Newman, D., New theory of contraction of striated muscle and
demonstration of the composition of the broad dark bands. Journ. of
Anat. and Physiol. 1879, p. 4.
Nicolaides, R., Ueber die caryokynetischen Erscheinungen der
Muskelkörper während des Wachstums der quergestreiften Muskeln. Arch.
f. Anat. u. Physiol. 1883, p. 441.
Odenias, M. W., Undersökungen öfer de sensibla muskelnervena.
Nord. Medic. Arch. Vol. IV, No. 18.
Paneth, J., Die Entwickelung von quergestreiften Muskelfasern
aus Sarkoplasten. Wiener Sitzungsber. 1886. Vol. XCII, Pt. III,
p. 561.
Petrowsky, Zur Frage über das Wachstum der Muskelfasern des
Muskelgewebes beim Frosch. Med. Centralbl. No. 49, pp. 769–772.
Pohl-Pincus, Ueber die Muskelfasern des Froschherzens. Arch.
f. mik. Anat. 1884, Vol. XXIII, p. 500; and Verhandl. der Physiol.
Gesell. zu Berlin. 1882–3. No. 9.
Ranvier, L., Appareils nerveux terminaux des muscles de la
vie organique; cœurs sanguins, cœurs lymphatiques; œsophagus; muscles
lisses. Leçons recueillies par Weber et Lataste. Leçons d’Anatomie
générale faites au Collège de France. Paris, 1880. Vol. VII, p. 350.
Ranvier, L., Leçons sur l’histologie du Système nerveux.
1878. Vol. II.
Reichert, K. E., Ueber das Verhalten der Nervenfasern bei dem
Verlauf und Endigung in einem Hautmuskel des Frosches, Rana temporaria.
Arch. f. Anat. u. Physiol. 1851, p. 29.
Retzius, Zur Kenntniss der quergestreiften Muskelfaser.
Biologische Untersuchungen. 1881, p. 1.
Rouget, Note sur la terminaison des nerfs moteurs dans les
muscles chez les reptiles, les oiseaux et les mammifères. Comptes
rendus. 1862. LV, p. 548.
Sachs, C., Die quergestreifte Muskelfaser. Arch. f. Anat. u.
Physiol. 1872, pp. 607–648.
Sachs, C., Die Nerven der Sehnen. Arch. f. Anat. u. Physiol.
1875, p. 402.
Sandmann, D. G., Ueber die Verteilung der motorischen
Nervenendapparate in den quergestreiften Muskeln der Wirbelthiere.
Arch. f. Anat. u. Physiol. 1885, p. 240.
Schönn, Anatomische Untersuchungen im Bereich des Muskel- und
Nervengewebes. Jenaische Zeitschr. 1865. Vol. II, pp. 26–60.
Schultze, M., Ueber Muskelkörperchen und das was man eine
Zelle zu nennen habe. Arch. f. Anat. u. Physiol. 1816, p. 17.
Sokolow, A. A., Sur les transformations der terminaisons des
nerfs dans les muscles de la grenouille après les section des nerfs.
Arch. de Physiol. normale et pathologique, 1874, pp. 300–315.
Sokolow, A. A., Ueber die Nervenendigungen in den Muskeln
ausgehungerter Frösche. Medicin. Bote. 1876, St. Petersburg.
Tergast, P., Ueber das Verhältniss von Nerve und Muskel.
Arch. f. mik. Anat. 1873. Vol. IX, p. 36.
v. Thanhoffer, L., Beiträge zur Histologie und Nervenendigung
der quergestreiften Muskelfasern. Arch. f. mik. Anat. 1882. Vol. XXI,
p. 26.
Thin, G., On the structure of muscular fibre. Quart. Journ.
Microsc. Sci. 1877. Vol. XVI, pp. 251–259.
Tolotschinoff, Ueber das Verhalten der Nerven zu den glatten
Muskelfasern der Froschharnblase. Arch. f. mik. Anat. 1869. Vol. V,
p. 510.
Trinchese, S., Mémoire sur la terminaison périphérique
des nerfs moteurs dans la série animale. Journ. de l’Anat. et de la
Physiol. 1867, pp. 485–504 (original in Italian, 1867).
Tschiriew, S., Sur les terminaisons nerveuses dans les
muscles striés. Arch. de physiol. norm. et path. 1879. Vol. VI,
p. 89.
Tschiriew, S., Sur les terminaisons nerveuses dans les
muscles striés. Compt. rend. 1878. Vol. LXXXVII, p. 604.
Unger, Untersuchungen über die quergestreiften Muskelfasern
des lebenden Thieres. Wiener med. Jahrb. 1879, p. 61; and in Centralbl.
f. d. med. Wiss. 1879, No. 34, p. 622.
Wagener, G. R., Ueber die Verbindung von Muskel und
Sehne unter einander. Sitzungsber. naturw. Gesells. Marburg. 1874,
pp. 38–46.
Waldeyer, W., Ueber die Endigung der motorischen Nerven
in den quergestreiften Muskeln. Centralbl. f. d. med. Wiss. 1863,
p. 369.
Waldeyer, W., Untersuchungen über den Ursprung und den
Verlauf des Axencylinders bei Wirbellosen und Wirbelthieren, sowie
über dessen Endverhalten in der quergestreiften Muskelfaser. Henle and
Pfeuffer’s Zeitschr. 1864. Vol. XX, pp. 193–257.
Weismann, A., Ueber die Musculatur des Herzens beim Menschen
und in der Thierreihe. Arch. f. Anat. u. Physiol. 1861, p. 41.
Wolff, W., Ueber den Zusammenhang des Muskels mit der Sehne.
Diss. Berlin, 1877; Abstract in Centralbl. f. d. med. Wiss. 1877,
p. 733.
Consult also: Arnold, J., Kühne, W., and
Schweigger-Seidel, F., in Stricker’s Handbuch der
Gewebelehre.
II. CARTILAGE AND BONE.
Arnold, J., Ueber die Abscheidung des indigschwefelsauren
Natrons im Knochengewebe. Virchow’s Arch. 1877. Vol. LXXI, p. 17.
Arnold, J., Die Ausscheidung des indigschwefelsauren Narions
im Knorpelgewebe. Virchow’s Arch. 1878. Vol. LXXIII, p. 125.
Bigelow, W. S., Notiz über den Theilungsvorgang bei
Knorpelzellen sowie über den Bau des Hyalinknorpels. Arch. f. mik.
Anat. 1879. Vol. XVI, p. 457.
Boll, F., Untersuchungen über den Bau und die Entwicklung der
Gewebe. Arch. f. mik. Anat. 1871. Vol. VII, p. 275.
Bruch, C., Ueber die Verknöcherung der Wirbelsäule bei den
Batrachiern. Würzb. naturw. Zeitschr. 1862. Vol. III, pp. 225–238.
Bush, F., Das Knochengewebe der Batrachier nach den
Untersuchungen von N. Kastschenko. Verhandl. d. physiol. Gesells. zu
Berlin. 1881, pp. 358–361.
Flesch, Untersuchungen über die Grundsubstance des
Hyalinknorpels. Würzburg, 1880.
Heidenhain, Zur Kenntniss des hyalinen Knorpels. Studien aus
d. physiol. Inst. zu Breslau. 1863. Pt. II, p. 1.
Hertwig, O., Anatomisch histologische Untersuchung des
Skelets der Mundhöhle und der Zähne der Amphibien; supplement to
Vol. XI. Arch. f. mikroskopische Anat. 1874, pp. 29–32.
Kastschenko, N., Ueber die Genese und Architectur der
Batrachierknochen. Arch. f. mik. Anat. 1881. Vol. XIX, pp. 1–52.
Kastschenko, N., Ueber die Krappfärbung der Froschgewebe.
Arch. f. mik. Anat. 1882. Vol. XXI, p. 357.
v. Kölliker, Gewebelehre Leipzig. 1867, p. 66.
Lehmann, J. C., Ueber den Knorpel in der Achillessehne des
Frosches. Zeitschr. f. wiss. Zool. 1864. Vol. XIV, p. 109.
Levschin, L., Ueber die Entwicklung des Knochengewebes des
Frosches. Centralbl. f. med. Wiss. Nos. 18, 19.
Mays, C., Ueber den Bau der Sehnen, etc. Virchow’s Arch.
1879. Vol. LXXV, p. 112.
Renaud, M. J., Système hyalin de soutènement des centres
nerveux et de quelques organes des sens. Arch. de Physiol. 1881,
p. 6.
Schleicher, W., Die Knorpelzelltheilung. Arch. f. mik. Anat.
1879. Vol. XVI, P. 248.
Spina, A., Ueber die Saftbahnen des hyalinen Knorpels. Wiener
Sitzungsber. 1879. Vol. LXXX, Pt. III, p. 267.
Stadelmann, E., Die Histologie des ‘Pseudoknorpels’ in der
Achillessehne des Frosches, etc. Virchow’s Arch. 1880, Vol. LXXX,
p. 105; also as Dissert. inaug. Königsberg, 1878.
van Stricht, O., Recherches sur le cartilage hyalin. Annales
de la société de médicine de Grand. 1885, pp. 221–232.
Thin, G., On the structure of hyaline cartilage. Quart.
Journ. Micros. Sci. 1876. Vol. XVI, pp. 1–22.
v. Török, A., Der feinere Bau des Knorpels des Achillessehne
des Frosches. Centralbl. f. d. med. Wiss. 1872, No. 5, p. 66; and
Verhandl. d. phys.-med. Gesells. zu Würzburg, 1872, Vol. III,
pp. 1–26.
III. THE CONNECTIVE TISSUES.
Billroth, T., Ueber die Epithelzellen der Froschzunge,
den Bau des Cylinder- und Flimmerepithel und ihr Verhältniss zum
Bindegewebe. Arch. f. Anat. u. Physiol. 1858, p. 159.
Bizzozero, G., Ueber den Bau des Sehnengewebes. Moleschott’s
Untersuchungen. 1876. Vol. XI, p. 36.
Bobinzky, C., Zur Kenntniss des Baues, der Entwicklung and
der regressiven Metamorphose der Fetzellen. Centralbl. f. d. med. Wiss.
1885. No. 43, pp. 753–755.
Boll, F., Untersuchungen über den Bau und die Entwicklung der
Gewebe. Arch. f. mik. Anat. 1871. Vol. VII, p. 276.
Ciaccio, G. V., Nuove Ricerche sull’ interna tessitura dei
tendi. Memorie dell’ Academie delle scienze dell Istituto di Bologna,
1872. Series III, Vol. II. Abstract in Centralbl. f. d. med. Wiss.
1873.
Czumak, J., Notiz über elastische Sehnen. Centralbl. f. med.
Wiss. 1863, p. 785.
Flemming, W., Ueber Bildung und Rückbildung der Fettzelle im
Bindegewebe; und Bemerkungen über die Structur des letztern. Arch. f.
mik. Anat. 1871. Vol. VII, p. 32.
Gerlach, J., Ueber Bindegewebe. Sitzungsb. d. phys.-med.
Societät zu Erlangen. 1872, p. 78.
Ginsburg, L., Ueber das Verhalten der Sehnenzellen bei der
Entzündung. Virchow’s Arch. 1882. Vol. LXXXVIII, p. 263.
Golgi, C., Sui Nervi dei Tendini dell’ Uomo e di altri
Vertebrati e di un nuovo Organo nervoso terminale Musculo-tendineo.
Estr. dalle Memorie della Reale Acc. di Torino. 1880. Series II,
Vol. XXXII, p. 29; No. 6, p. 86.
Hensen, V., Ueber die Entwicklung des Gewebes und der Nerven
im Schwanze der Froschlarve. Virchow’s Arch. 1864. Vol. XXXI, p. 51.
Hoyer, Ueber den Bau der Cylinder- und Flimmerepithelien
und ihr Verhältniss zum Bindegewebe. Arch. f. Anat. u. Physiol. 1858,
p. 163; also Deutsche Klinik. 1857, No. 21.
Iwanoff, A., Beiträge zur normalen und pathologischen
Anatomie des Frosch-Glaskörpers. Centralbl. f. d. med. Wiss. 1868,
p. 129.
Kollmann, Ueber den Bau der Sehne. Münchener Sitzungsber.
1878. Abstract in Centralbl. f. d. med. Wiss. 1879, p. 881.
Maddox, On the apparent relation of nerve to
connective-tissue corpuscles. Proc. Roy. Soc. Lond. 1868. Vol. XVI,
p. 61.
Mays, C., Ueber den Bau der Sehnen mit besondere
Berücksichtigung über Saftbahnen. Virchow’s Arch. 1879. Vol. LXXV,
p. 112.
Sachs, C., Die Nerven der Sehnen. Arch. f. Anat. u. Physiol.
1875, p. 402.
Spina, A., Untersuchungen des lebenden Bindegewebes.
Oesterr. med. Jahrb. 1884. Pt. II.
NOTE BY THE TRANSLATOR.
Reference has already been made to the views of Messrs. Melland
and Marshall on the structure of muscle-fibres. The opinion that the
striation of voluntary muscle is wholly or in part due to the presence
of a regularly arranged network was previously published by Retzius,
Bremer, and others. The authors referred to have now for the first
time shown the importance of this network in all vertebrate muscular
tissues, whether voluntary or involuntary.
Mr. Marshall gives the following summary of the result of
his researches, which the Translator has confirmed by his own
observations:—
1. In all muscles which have to perform rapid and frequent
movements, a certain portion of the muscle is differentiated to perform
the function of contraction, and this portion takes on the form of a
very regular and highly modified intracellular network.
2. This network, by its regular arrangement, gives rise to certain
optical effects which cause the peculiar appearances of striped
muscle.
3. The contraction of the striped muscle-fibre is probably caused by
the active contraction of the longitudinal fibrils of the intracellular
network; the transverse networks appear to be passively elastic, and by
their elastic rebound cause the muscle to rapidly resume its relaxed
condition when the longitudinal fibrils have ceased to contract; they
are possibly also paths for the nervous impulse.
4. In some cases where muscle has been hitherto described as
striped, but gives no appearance of the network on treatment with
the gold and other methods, the apparent striation is due to optical
effects caused by a corrugated outline in the fibre.
5. In muscles which do not perform rapid movements, but whose
contraction is comparatively slow and peristaltic in nature, this
peculiar network is not developed. In most if not all of the unstriped muscles of
invertebrates there does not appear to be an intracellular network
present in any form, but in the unstriped muscle of vertebrates
there are longitudinal fibres only; these possibly represent a form
of network intermediate between the typical irregular intracellular
network of other cells and the highly modified network of striped
muscle.
6. The cardiac muscle-cells contain a network similar to that of
ordinary striped muscle.
Preparation of the mucous membrane of the dorsal surface of the
mouth and oesophagus to show the vascular supply. Arteries red, veins
blue; after Schöbl.
II.
Small portion of the above to show the dilatations on the
capillaries; after Schöbl.
Transverse section through the mucous membrane of the fundus of the
stomach of Rana esculenta. Alcohol preparation, doubly stained
with carmine and anilin blue. After Biedermann. (Oc. II, Syst. 7,
Hartnack.)
Two portions from a gold preparation of the kidney of Rana
esculenta.—G. H.
I.
Showing the tendency to split into lobules.
II.
Nerve-fibres accompanying the blood vessels.
a Blood-vessels. b Nerves.
APPENDIX. — I. WORKS WHICH DESCRIBE ORGANS OR SETS OF ORGANS IN THE FROG. — II. WORKS RELATING TO THE EMBRYOLOGY AND DEVELOPMENT OF THE FROG. — III. ADDITIONS TO THE LISTS GIVEN AT THE HEADS OF THE SECTIONS.
Bettade, E., Sulle diverse forme delle R. temp. in Europa e
più particolammente nell’ Italia. Venezia, 1885.
Brehm, A. C., Illustriertes Thierleben. Hildburghausen, 1869.
Vol. V.
Burdon-Sanderson, Handbook for the Physiological Laboratory.
London, 1873.
Camerana, L., Recherches sur les variations de in R.
esculenta et du Bufo viridis dans le bassin de la Méditerranée. Paris,
1883.
Carus, C. G., Lehrbuch der vergleichenden Zootomie. 2nd Edit.
Leipzig, 1834.
Cepède, Comte de la, Histoire naturelle des quadrupèdes
ovipaires et des serpens. Paris, 1808.
Dugès, Recherches anatomiques et physiologiques sur les
Reptiles. Ext. des Annales des Sciences naturelles. Paris, 1827.
Duméril and Bibron, Erpétologie générale ou histoire complète
des Reptiles. 1836.
Ecker, A., Icones physiologicae. Leipzig, 1851–1859.
Fatio, V., Faune des vertébrés de la Suisse. Genève et Bâle,
1872.
Gegenbaur, C., Grundzüge der vergl. Anatomie. Leipzig,
1870.
Gegenbaur, C., Grundriss der vergl. Anatomie. Leipzig,
1878.
Gerlach, Handbuch der Histologie. 1853–1854.
Gesner, C., Historia Animalium. Liber I. 1551.
Gesner, C., Icones Animalium. 1560.
v. Griesheim, A., Ueber die Zahlenverhältnisse der
Geschlechter bei R. fusca. Pflüger’s Arch. f. d. ges. Physiol. 1881.
Vol. XXVI, p. 3.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreichs. Vol. VI, Amphibien. Leipzig, 1873–1878.
Howes, G. B., An Atlas of Practical Elementary Biology.
London, 1885.
Huxley, T., Anatomy of the Vertebrated Animals. London,
1871.
Huxley, T., Lectures on the Elements of Comparative
Anatomy.
Rösel v. Rosenhof, Historia naturalis ranarum nostratium.
Nürnberg, 1758.
Rudolphi and Breyer, Observationes anatomicae circa abricam
Ranae pipae. Berolini, 1811.
Rusconi, M., Développement de la grenouille commune. Milan,
1826.
Schneider, J. G., Historia amphibiorum. Jenae, 1799.
Schwalbe, G., Lehrbuch der Anatomie der Sinnesorgane.
Erlangen, 1885.
Stannius, H., Zootomie der Amphibien (Handb. der Zoot. der
Wirbelthiere, 2 Buch). 2nd Edit. Berlin, 1856.
Stricker, S., Beiträge zur Biologie der Batrachier. Wien.
Zool. Bot. Verhandl. 1866. Vol. XVI, pp. 451–456.
Stricker, S., Handbuch der Gewebelehre.
Stricker, S., Manual of Human and Comparative Histology.
Translated by H. Power. London, 1870.
Swammerdam, J., Biblia Naturae Amstelodamensis. (Dutch and
Latin by Gaubius. Leidae, 1738.)
Todd and Bowman, The Physiological Anatomy and Physiology of
Man. London, 1845–1857.
Vogt, C., Zoologische Briefe. Frankfurt a. M., 1851.
Wagler, J., Natürliches System der Amphibien. München,
Stuttgart, and Tübingen, 1830.
Wagner, R., Lehrbuch der vergleichenden Anatomie. Leipzig,
1834–1835.
Wagner, R., Icones Zootomicae. Leipzig, 1841.
Wagner, R., Handwörterbuch der Physiologie. 1842.
Waters, W. H., Histological Notes. Manchester and London,
1884.
Wiedersheim, R., Lehrbuch der vergleichenden Anatomie der
Wirbelthiere. 2nd Edit. Jena, 1886.
Wiedersheim, R., Elements of Comparative Anatomy of
Vertebrates. Translated by N. Newton Parker. London, 1886.
Balfour, F. M., Treatise on Comparative Embryology. London,
1880.
Born, G., Beiträge zur Bastardirung zwischen den
einheimischen Anurenarten. Pflüger’s Arch. f. d. ges. Physiol. 1883.
Vol. XXXII, p. 453.
Durham, H. E., Note on the presence of a Neurenteric Canal in
Rana. Quart. Journ. Micros. Sci. 1886. Vol. XXVI, p. 509.
Giles, A. E., The development of the fat-bodies in Rana
temporaria. Quart. Journ. Micros. Sci. 1888. Vol. XXIX.
Goette, A., Kurze Mittheilungen aus der
Entwicklungsgeschichte der Unke. Arch. f. mik. Anat. 1873. Vol. IX,
p. 396.
Goette, A., Entwicklungsgeschichte der Unke. Leipzig,
1875.
Hertwig, O., Die Entwicklung des mittleren Keimblattes der
Wirbelthiere. Jena, 1883.
Johnson, A., and Sheldon, L., Notes on the Development
of the Newt (Triton cristatus). Quart. Journ. Micros. Sci. 1886.
Vol. XXVI, p. 573.
Marshall, A. M., The Frog: An Introduction to Anatomy,
Histology, and Embryology. 3rd Edition. Manchester and London, 1888.
Pflüger, E., Einige Beobachtungen zur Frage über die das
Geschlecht bestimmenden Ursachen. Pflüger’s Arch. f. d. ges. Physiol.
1881. Vol. XXVI.
Pflüger, E., Hat die Concentration des Samens einen Einfluss
auf das Geschlecht? Pflüger’s Arch. f. d. ges. Physiol. 1883.
Vol. XXIX, p. 1.
Pflüger, E., Zusammenstellung der Ergebnisse und Erörterung
der Principien der Zeugung. Pflüger’s Arch. f. d. ges. Physiol. 1883.
Vol. XXXII, p. 542.
Pflüger, E., and Smith, W. J., Experimente über
Bastardirung der anuren Batrachier. Pflüger’s Arch. f. d. ges. Physiol.
1883. Vol. XXXII, p. 519.
Remak, Untersuchungen über die Entwickelung der Wirbelthiere.
Berlin, 1855.
Schultze, O., Zur ersten Entwickelung des braunen
Grasfrosches. Leipzig, 1887.
Schultze, O., Die Entwicklung der Keimblätter und der Chorda
dorsalis von Rana fusca. Zeitschr. f. wiss. Zool. 1888. Vol. XLVII,
p. 325.
Spencer, W. B., Some Notes on the Early Development of Rana
temporaria. Quart. Journ. Micros. Sci. 1885. (Supplement.)
Stricker, S., Untersuchungen über die Entwicklung des Kopfes
der Batrachier. Arch. f. Anat. u. Physiol. 1864, p. 52.
Törok, A., Beiträge zur Kenntniss der ersten Anlagen der
Sinnesorgane und der primären Schädelformation bei den Batrachiern.
Moleschott’s Untersuchungen, 1870. Vol. X, p. 338.
1. The Bones.
Albrecht, P., Note sur le basi-occipital des batraciens
anoures. Extr. d. Bullet. d. Musée royal d’hist. nat. de Belgique.
1883. Vol. II.
Born, G., Die sechste Zehe der Anuren. Morphol. Jahrb. 1876.
Vol. I.
Born, G., Ueber das Skelet des Fersenhöckers von Rana fusca,
etc. Sitzungsb. d. Schles. Gesell. f. vaterländ. Cultur. 1879.
Born, G., Nachträge zu Carpus und Tarsus. Morph. Jahrb. 1880.
Vol. VI.
Ecker, A., Icones physiologicae. Leipzig, 1881–1889.
Ecker, A., Die Anatomie des Frosches. 2nd Edition.
Braunschweig, 1888, pp. 17–62.
Gegenbaur, Untersuchungen zur vergl. Anatomie der Wirbelsäule
bei Reptilien und Amphibien. Leipzig, 1862.
Gegenbaur, Grundzüge der vergl. Anatomie. Leipzig, 1870.
Goette, A., Brustbein und Schultergürtel auf
entwickelungsgeschichtlicher Grundlage verglichen bei Amphibien und
Anurioten. Arch. f. mik. Anat. 1877. Vol. XIV, p. 502.
Howes, G. B., On some abnormalities of the Frog’s vertebral
column. Anat. Anz. 1886. Vol. I, Pt. II.
Leydig, F., Ueber den Bau der Zehen bei Batrachiern und die
Bedeutung des Fersenhöckers. Morphol. Jahrb. 1876. Vol. II.
Parker, W. K., A monograph on the structure and development
of the shoulder-girdle and sternum. Ray. Soc. 1867.
Schneider, J. G., Historia amphibiorum. Jenae, 1799.
Stöhr, P., Zur Entwickelungsgeschichte des Anurenschädels.
Zeitschr. f. wiss. Zool. 1881. Vol. XXXVI.
Törok, A., Beiträge zur Kenntniss der ersten Anlagen der
Sinnesorgane und der primären Schädelformation bei den Batrachiern.
Moleschott’s Untersuchungen. 1870. Vol. X, p. 338.
2. The Muscles.
Albrecht, P., Beitrag zur Morphologie des M. omohyoides und
der ventralen inneren Interbranchial-Musculatur. Inaug. Dissert. Kiel,
1876.
Ecker, A., Die Anatomie des Frosches. 2nd Edition.
Braunschweig, 1888, pp. 65–139.
Hoffmann, C. K., Bronn’s Klassen und Ordnungen des
Thierreichs. Vol. VI. Amphibien. Leipzig, 1873–1878.
Howes, G. B., An Atlas of Practical Elementary Biology.
London, 1885.
3. Nervous System.
Engelmann, T. W., Ueber die Discontinuität des Axencylinders
und den fibrillären Bau der Nervenfasern. Pflüger’s Arch. f. d. ges.
Physiol. 1880. Vol. XXII, p. 1.
Grandry, Recherches sur la structure interne du cylindre de
l’axe et des cellules nerveuses. Bull. de l’Acad. Roy. du Belgique.
1868.
Hodge, C. F., Some effects of stimulating ganglion-cells.
(Some anatomical details regarding the relations of nerve-fibres with
nerve-cells are given.) American Journ. of Phys. 1888.
Owsjannikow, P., Ueber die Rinde des Grosshirns. Mémoires de
l’acad. impériale des sciences de St. Pétersbourg. 1879. Series VII,
Vol. XXVI, No. 11.
Spiro, Physiologisch-topographische Untersuchungen am
Rückenmark des Frosches. Mémoires de l’acad. impériale des sciences de
St. Pétersbourg. 1870. Series VII, Vol. XVI, No. 7.
Waldeyer, W., Untersuchungen über den Ursprung und Verlauf
des Axencylinders. Henle u. Pfeuffer’s Zeitschr. 1864. Vol. XX,
pp. 193–257.
Consult also: Gerlach, J., Mayer, S., and Schultze,
M., in Stricker’s Handbuch der Gewebelehre.
4. The Vascular System.
Barthol, P., Sopra il sistema linfatico dei Rettili. Pavia,
1833.
Blaschek, A., Untersuchungen über Herz, Pericard, Endocard,
und Pericardhöhle. Schenk’s Mitt. 1885. New Series, p. 32.
Eberth, C. J., in Stricker’s Handbuch der Gewebelehre.
Klein, E., On the peripheral distribution of non-medullated
nerve-fibres (nerves of the blood-vessels in the frog’s tongue). Quart.
Journ. Micros. Sci. 1872. Vol. XII, p. 123.
Mayer, S., Studien zur Histologie und Physiologie des
Blutgefässsystems. Wiener Sitzungsb. 1886. Vol. XCIII, Pt. III,
p. 45.
v. Recklinghausen, F., (The lymphatics) in Stricker’s
Handbuch der Gewebelehre.
Rollett, A., (The Blood) in Stricker’s Handbuch der
Gewebelehre.
Teichmann, L., Untersuchungen über das Saugadersystem.
Leipzig, 1861.
5. The Alimentary Canal.
Heidenhain, R., Beiträge zur Kenntniss des Pancreas.
Pflüger’s Arch. f. d. ges. Physiol. 1875. Vol. X, p. 557.
Krause, W., Anatomische Untersuchungen (Tongue). Hannover,
1861.
Consult also: Klein, E., The Oral Cavity and the Oesophagus;
Müller, W., The Spleen; Eberth, C. J., The Liver, in
Stricker’s Handbuch der Gewebelehre.
6. The Lungs and Larynx.
Holmgren, F., Methode zur Beobachtung des Kreislaufs in
der Froschlunge. Beitr. z. Anat. u. Physiol. Festgabe f. C. Ludwig.
Leipzig, 1874.
Meckel, J. F., Beiträge zur Geschichte des
Respirations-Systemes der Amphibien. Meckel’s Arch. 1849. Vol. V.
Schmidt, C., De l’épithelium pulmonaire. 1866.
Williams, Article Respiration, in Todd’s Cyclopaedia of Anat.
and Physiol. 1859. Vol. V.
7. The Urino-Genital System, the Adrenals, and
the Fat-bodies.
Aeby, C., Ueber glatte Muskelfasern im Ovarium und Mesovarium
von Wirbelthieren. Arch. f. Anat. u. Physiol. 1859, p. 675.
Giles, A. E., The development of the fat-bodies in Rana
temporaria. Quart. Journ. Micros. Sci. 1888. Vol. XXIX.
Grohe, F., Ueber die Bewegung der Samenkörper. Virchow’s
Arch. 1865. Vol. XXXII, p. 416.
Virchow, R., Ueber die Dotterplättchen bei den Fischen und
Amphibien. Zeitschr. f. wiss. Zool. 1849. Vol. IV.
Consult also: Eberth, C. J.; v. La Valette St. George;
Ludwig, C.; Grünwald; Obersteiner, H.; and
Stricker, S., in Stricker’s Handbuch der Gewebelehre.
8. The Skin and Sense-Organs.
a. The Skin.
Busch, A., Phänomene aus dem Leben der Pigmentzellen. Arch.
f. Anat. u. Physiol. 1856, p. 415.
b. Special Organs of Tactile Sensation.
Mitrophanow, P., Zur Entwicklungsgeschichte und Innervation
der Nervenhügel der Urodelenlarven. Biologisches Centralb. 1887,
p. 174.
c. The Organs of Taste.
Beale, L. S., New Observations upon the Minute Anatomy of the
Papillae of the Frog’s Tongue. Phil. Trans. 1865. Vol. CLV, p. 443.
Engelmann, T. W., in Stricker’s Handbuch der Gewebelehre.
Maddox, R. L., A Contribution to the Minute Anatomy of
the Fungiform Papillae and terminal arrangement of Nerve to striped
Muscular Tissue in the Tongue of the common Frog. Monthly Micros.
Journ. 1869, p. 1.
d. The Ear.
Albrecht, P., Sur la valeur morphologique de la trompe
d’Eustache. Communication faite à la Société d’Anatomie Pathologique de
Bruxelles. 1884.
v. Kölliker, Handbuch der Gewebelehre. 5th Edit. Leipzig,
1867.
Leydig, F., Handbuch der Histologie. Frankfurt a. M.,
1857.
Rüdinger, in Stricker’s Handbuch der Gewebelehre.
e. The Nose.
Marshall, A. M., Morphology of the Vertebrate Olfactory
Organ. Quart. Journ. Micros. Sci. 1879. Vol. XIX, p. 330.
f. The Eye.
Ciaccio, G. V., Beobachtungen über den inneren Bau des
Glaskörpers im Auge des Menschen und der Wirbelthiere im Allgemeinen.
Moleschott’s Untersuchungen, 1870. Vol. X, p. 383.
Hannover and Finkbeiner, Vergleichende Untersuchungen
der Stärke des Glaskörpers bei den Wirbelthieren. Zeitschr. f. wiss.
Zool. 1855. Vol. VI, p. 335.
Hirschberg, J., Zur Dioptric und Ophthalmologie der Fish- und
Amphibienaugen. Arch. f. Anat. u. Physiol. 1887, p. 493.
Ranvier, L., Le mécanisme de la Sécrétion. Leçons faites au
Collége de France en 1886–1887. (Nictitating membrane.)
Consult also: Rollett and Stieda, in Stricker’s
Handbuch der Gewebelehre.
The Anatomy of the Frog. — University Press Oxford.
Plate II.
The Anatomy of the Frog. — University Press Oxford.
FOOTNOTES:
TRANSLATIONS OF
FOREIGN BIOLOGICAL MEMOIRS.
I.
The Physiology of Nerve, of Muscle, and of the
Electrical Organ. Edited by J. Burdon-Sanderson, M.D., F.R.SS.
L. & E., Waynflete Professor of Physiology in the University of Oxford.
Medium 8vo., cloth, price 21s.
II.
The Anatomy of the Frog. By Dr. Alexander Ecker,
Professor in the University of Freiburg. Translated, with numerous
Annotations and Additions, by George Haslam, M.D.; and profusely
Illustrated.
III.
Contributions to the History of the Physiology of
the Nervous System. By Professor Conrad Eckhard. Translated
by Miss Edith Prance. In Preparation.
IV.
Essays upon Heredity and Kindred Biological
Problems. By Dr. August Weismann, Professor in the University of
Freiburg-in-Breisgau. Authorised Translation edited by Edward B.
Poulton, M.A., F.L.S., F.G.S., Tutor of Keble College, Lecturer in
Natural Science, Jesus College, Oxford; Selmar Schönland, Ph.D.,
Sub-Curator of the Fielding Herbarium in the University of Oxford;
and Arthur E. Shipley, M.A., F.L.S., Fellow and Lecturer of Christ’s
College, and Demonstrator of Comparative Anatomy in the University
of Cambridge. Medium 8vo., cloth, price 16s.
Oxford
AT THE CLARENDON PRESS
LONDON: HENRY FROWDE
OXFORD UNIVERSITY PRESS WAREHOUSE, AMEN CORNER. E.C.
1
‘I wished to furnish a manual so arranged that it might serve as a basis easily
altered, pruned, or enlarged as the future might need.’
2
‘In animals with warm blood the action of the muscles is neither so apparent
nor so long continued as in those animals which have cold blood, such as fishes and
many other aquatic animals, and those also which live both in water and on dry
land. On this account I have made my investigations chiefly on frogs, for in them
the nerves are very distinct, and are easily found and exposed.’ Buch der Natur,
Leipzig, 1752, p. 330.
3
Leeuwenhoek, Arcana Naturæ III, epist. 65 ad Reg. Soc. Lond., p. 158.
4
It may be well to remind the reader that this introduction was written in 1864.
5
For purposes of comparison other than European frogs were examined, especially
American species of Rana, for which I am indebted to the kindness of my much
esteemed friend Agassiz. These were Rana Catesbyana, Shaw (R. mugiens, Catesby—R.
pipiens, Harlan); R. sylvatica, Leconte; R. clamitans, Daudin; R. palustris,
Leconte; R. halecina, Leconte. To these, however, no further reference will be made
in the text.
7
Leeuwenhoek, Arcana Naturæ, Vol. III of Ecker’s edition. Leyden, 1722. Epist. 65
ad Reg. Soc. Lond., p. 154.
8
Rösel, Naturgeschichte der Frösche Deutschlands, ed. Schreber. Nürnberg, 1815,
p. 36.
9
The extreme sizes are much more pronounced in this species. I have never found
R. temporaria of the size attained by large specimens of the water-frog.
11
Lister, On the Cutaneous Pigmentary System of the Frog. Phil. Trans., 1857,
p. 627.
12
Agassiz et Vogt, Histoire naturelle des poissons d’eau douce (Neuchatel, 1839),
Pl. IV, mention that the colour of trout is very variable and that in shaded and
deep-lying brooks and rivers a variety is found which is black.
13
Spallanzani, Versuche über Erzeugung der Thiere and Pflanzen. Leipzig, 1786,
p. 5.
14
Rusconi, Développ. de la Grenouille. Milan, 1826, p. 6.
15
Annales des Sciences naturelles. Zoologie, IV Série, Vol. IV, 1855, p. 368.
16
Amtl. Bericht über die 24. Versammlung deutscher Naturforscher in Kiel, 1846,
p. 141; Wiegmann’s Archiv, 1847, Vol. II, p. 341; Steenstrup, Oversigt K. Danske
Selsk. Forhandlgr., 1846, p. 92.
18
Annales des Sciences naturelles. Zoologie, IV Série, Vol. IV, 1885, p. 368.
19
According to Steenstrup, l. c., the size of the supplemental toe is in R. temporaria
one-half and in R. oxyrhinus two-thirds of that of the next toe.
20
I do not find, however, that this disappears when the animals are on land; in
fact I have animals before me in a glass in which it is plainly seen.
24
Annales des Sciences naturelles. Zoologie, III Série, Vol. XVIII, 1852, p. 243.
25
Compare Müller, Zeit. f. wissen. Zoolog., Vol. IX.
26
Dugès, Recherches sur l’ostéologie et la myologie des batraciens à leurs différents
âges, p. 116.
27
Bruch, Beiträge zur Entwicklungsgeschichte des Knochensystems. Schweiz.
Denkschriften, p. 118.
28
Cf. Gegenbaur, (1) Über Bau u. Entwicklung der Wirbelsäule bei Amphibien
überhaupt u. beim Frosch insbesondere. Abhand. d. Naturforsch. Gesell. zu Halle,
vol. vi, 1861; (2) Untersuch. zur vergleich. Anat. d. Wirbelsäule bei Amphibien
u. Rept., Leipzig, 1862. As regards the adult animal I can bear out Gegenbaur’s
observations. The scope and limits of this book forbid me to go further into the
developmental history.
29
Cuvier (Ossem. fossil., V, 2. 388) says that these little bones are fixed outside
the nasal cavity, so that we may suppose that he confounded them with the
nasal cartilages found in this situation. Dugès correctly indicates their position
to be inside of the nasal capsule. Meckel (Vergl. Anat. II, 504) also regards
them as nasal bones. Bruch (Würzb. naturwiss. Zeitschrift, vol. II, 1861, p. 213)
could not find them in any frog-skull, doubtless because he did not look inside the nasal
capsules.
30
This cartilage is the quadrate cartilage of Parker; others regard it as the upper
end of the cartilaginous mandibular arch, of which Meckel’s cartilage is the lower
distal part.
31
For os nasale, Cuvier (l. c., g), cornet (concha), Dugès, see cartilaginous nasal
capsule, p. 27.
45
A second origin from the lower border of the mandible, described by Klein, is
not to be found. The appearance is due to the exit of vessels and nerves from the
groove between the mandible and the muscle.
46
Whether these muscles may be regarded as mm. interossei is open to discussion,
as they appear to act more as mm. opponentes.
47
The sartorius has lately been used by Kühne in his researches on the nerve-endings
in muscle and on muscle contraction without nerve supply (du Bois-Reymond’s
and Reichert’s Archiv, 1859. Page 314).
48
Lehmann, Ueber den Knorpel in der Achillessehene des Frosches, Zeitschs. f.
U. Zool. XIV, p. 109. (See also literature on cartilage, Sect. VII.)
49
Kölliker, Mikrosk. Anatomie, 1866, vol. II. 1, p. 247; Reichert, Müller’s Archiv,
1851, p. 29, Pl. I; Kölliker, Untersuchungen über die letzten Endigungen der Nerven
in den Muskeln des Frosches; Leipzig, Engelmann, 1862.
50
Compare Klein, Beiträge zur Anatomie der ungeschwänzten Batrachier (R. temporaria,
L.): Jahreshefte des Vereins für vaterländische Naturkunde in Württemberg,
1850, p. 72.
51
v. Kölliker states that the lumen is everywhere circular.
52
In these diagrams, from Ludwig Stieda’s Studien über das centrale Nervensystem
der Wirbelthiere, the outline of the diagram is magnified thirty times, while the
details are magnified eighty times.
53
Compare Ehlers, Ueber die Zirbel der Haifische, Zeit. f. wiss. Zool. 1878, Vol. XXX;
and Balfour, Development of the Elasmobranch Fishes, chap. ix.
54
Wiedersheim states that the pedicle is hollow, and regards the part formerly
known as the pineal body as a thickened portion of this pedicle.
55
Schmidt (l. c.) states that the epithelium of the central canal of the spinal cord is
not ciliated.
56
These names are those adopted by Schöbl for corresponding vessels in the newt,
the translator has accepted them as being suitable, with slight modification, to the
vessels of the frog.
57
The branches of the vagus which are represented in this figure as crossing the petrohyoid muscles ought to
be underneath them.—Trans.
59
Larger cells of deeper layer 80 µ to 90 µ in diameter, sometimes one or two as
large as 0·1 mm. v. Lenhossék.
60
[Observers have differed considerably as to the relations of this nerve: Volkmann
describes it as the first nerve of the neck, and describes a ganglion on its dorsal
root; Vogt denies the presence of this ganglion, and regards it as a true cranial
nerve; Stannius asserts that no ganglion exists, and holds the nerve to represent the
first two spinal nerves; Wyman describes the two roots and regards it as a spinal
nerve; Hoffmann regards this nerve as the second spinal (N. spinalis II); Fürbringer
as the representative of two spinal nerves; de Watteville describes two roots
and names it first spinal nerve.—Trans.]
61
As this muscle increases in size during the breeding season. it would be interesting
to know whether a corresponding change takes place in the nerve.
62
The base of the ventricle measured, when distended, 8 mm. by 5 mm.
63
I have had opportunity of examining Mr. Marshall’s slides and have convinced
myself of the correctness of his observations.
64
In Figs. 168, 169, and 170 the dotted lines denote the boundaries of the various
lymph-sacs.
65
Mr. Hurst has noticed a frog (R. temporaria) in which the blood was perfectly
colourless.
66
Gulliver, Proc. Zool. Soc. London, 1845, Vol. XIII, p. 93 seq.
67
Hewson, Phil. Trans. 1773, Vol. LXIII, p. 310 seq.
68
Fuchs, Virchow’s Arch. 1877, Vol. LXXI, p. 78 seq.
69
His, Virchow’s Arch. 1863, Vol. XXVIII, p. 427.
70
Arnold, in Stricker’s Handbuch d. Gewebelehre, p. 137.
71
Beale, Phil. Trans., 1863, p. 153, shows dilatations in his drawing, but makes no
reference to them in the text.
72
The vascular supply of the mucous membrane of the dorsal surface of the mouth
and oesophagus is shown (after Schöbl) in Plate II, Fig. 180, I. Arteries red, veins
blue. II. in the same figure represents the dilatations on the capillaries; after
Schöbl.
73
A transverse section through the mucous membrane of the fundus of the stomach
of Rana esculenta is shown in Plate II, Fig. 187. Alcohol preparation, doubly
stained with carmine and anilin blue. After Biedermann. (Obj. II, Syst. 7,
Hartnack.)
