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CORNELL UNIVERSITY. 


THE 


KHoswell PP. Flower Library 
THE GIFT OF 


ROSWELL P. FLOWER 
FOR THE USE OF 
THE N. Y. STATE VETERINARY COLLEGE. 
1897 


The comparative an 


Ml 


atomy of the domestica 


Cornell University 


The original of this book is in 
the Cornell University Library. 


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the United States on the use of the text. 


http://www.archive.org/details/cu31924000012389 


THE 


COMPARATIVE ANATOMY 


OF THE 


DOMESTICATED ANIMALS. 


er 


By AY’;CHAUVEAU, 


PROFESSOR AT THE LYONS VETERINARY SCHOOL. 


Second Edition, Rebised and Gnlarged, with the Go-operution of 
8. ARLOING, 


LATE PRINCIPAL OF ANATOMY AT THE LYONS VETERINARY SCHOOL; 
PROFESSOR AT TIE TOULOUSE VETERINARY SCILOOL. 


TRANSLATED AND EDITED 


BY @ 


GEORGE FLEMING, F.R.G.8. M A.L, 


t 
VETERINARY SURGEON, ROYAL- ENGINEERS, 
AUTHOR OF “TRAVELS ON HORSEBACK IN MANTCHU TARTARY,"' HORSE-8AOES AND HORSE-SHOEING, 
“ ANIMAL PLAGUES,” “PRACTICAL HORSE-SHORING;” “RABIES AND HYD ROPHOBIA,” ETO. 
7 


” 


WITH 4850 ILLUSTRATIONS. 


a 


NEW YORK: 
D. APPLETON AND COMPANY, 
549 & 551 BROADWAY. 


1873. 
Al 


Dedicates 


TO THE MEMORY OF 


JOHN LAWSON, MRCYV.S., 


OF MANCHESTER, 


WHO FIRST URGED THE DESIRABILITY OF UNDERTAKING THIS TASK, 
AND WHOSE SINCERE AND INESTIMABLE FRIENDSHIP AND ENCOURAGEMENT FOR 
MANY YEARS 
o 


THE EDITOR AND TRANSLATOR HEREBY ACKNOWLEDGES WITH SORROWFUL 


a AFFECTION AND GRATITUDE. 


bene eer cine emad 
Sera, 
‘ \BL6 Qoe Dh. Saw. 


PREFACE BY THE TRANSLATOR AND 
EDITOR. 


In undertaking the arduous task of translating and editing the ‘ Traité @ 
Anatomie Comparée des Animaux Domestiques’ of M. Chauveau, I have been 
moved by a desire to fill a void in medical literature which has always 
existed, so far as the English language is concerned. There has been no 
complete treatise on the anatomy of the domesticated animals, and the 
absence of such a work has exerted a serious influence on the progress of 
veterinary science, and doubtless proved more or less of a loss to the 
community at large. 

The only text book to which the student or practitioner of animal 
medicine could until recently refer, has been that on the anatomy of the 
Horse, written by the late distinguished army veterinary surgeon, William 
Percivall, more than forty years ago: a book which, though in every way 
creditable to its author, was notoriously incomplete, even as regards the 
anatomy of the only animal it treated of, and was without illustrations. No 
serious attempt has been made to teach the structure of the other useful 
creatures domesticated by man, valuable though many of them are; and 
the student who was anxious to acquire this knowledge had no guide to 
lead or instruct him. At college, this loss may not have been so severely 
felt as when, having graduated, he entered on the practice of his profession ; 
and if the experience of veterinary surgeons in general has been like my 
own, they will be ready to testify to the almost daily regret they felt 
at the very meagre notions of anatemy they possessed, and the benefit a 
complete and trustworthy manual would confer. 

My professional avocations in the army would not permit me to make 
the necessary dissections for the production of such a work: and indeed 
so many classical and standard treatises on the subject have appeared, 
during this century, on the Continent, and notably in France and Germany, 
that it would seem a mere waste of time and labour to attempt a task which 


viii PREFACE BY THE TRANSLATQR AND EDITOR. 


has been already so thoroughly accomplished by very zealous and pro- 
ficient anatomists. 

In selecting for translation the present treatise in preference to other 
works which are justly held in high estimation, I was influenced not only 
by the knowledge that it was written by one of the most talented com- 
parative anatomists and physiologists of the day, but by the ability and 
originality which are so conspicuous in every page. I was also aware 
that, for more than a century, the French veterinary schools have been 
celebrated for the careful and thorough manner in which anatomy has been 
taught by most efficient teachers, who are all selected by open com- 
petition; and that Professor Chauveau’s book was the approved dissection 
manual of these and other Continental schools. 

Excellent as was the first edition of the work, the second is still more 
complete; indeed it may be said to be almost a new book, owing to the 
assistance afforded by M. Arloing, an anatomist who promises to assume a 
high rank in his profession. 

The French treatise is illustrated by three hundred and sixty-eight wood- 
cuts, but for several reasons it was deemed advisable to select only one 
hundred and seventy-three from this number : those rejected being chiefly 
human figures, and either far larger than was necessary or compatible with 
the space at disposal, or not so well suited for such a work as 1 was 
intent on producing. Nearly sixty original figures have been added to those 
selected; and through the courtesy and liberality of Messrs. J. and A. 
Churchill, the total number has been increased to four hundred and fifty. 
The profuseness and general excellence of these drawings, and their great 
accuracy, will, it is hoped, materially lessen the fatigue and time demanded 
for the study of this most important subject, and prove valuable for reference 
to the operator or busy practitioner. 

No labour or pains have been spared to make the work the most complete 
and useful of any that has been produced. The best treatises in German, 
French, and Italian have been consulted in editing it, and when necessary, 
I have added to the descriptions. These additions are contained within 
brackets, thus ( ). As my task has been accomplished without any 
aid, I assume the entire responsibility for any errors of omission or 
commission that may exist; my aim bemg to. furnish what has been an 
urgent desideratum for very many years—a complete dissection manual for 
the student of veterinary science, a book of reference for the veterinary 
surgeon, and a work that might be available for the zoologist, comparative 
anatomist, ethnologist, and medical practitioner. I have for a long time 
believed that the two branches of medicine—human and animal—should be: 
more closely allied than they are at present, and that this alliance can only: 
be effected by a mutual study and recognition of the facts which prove that 
the two are really one—wide apart though they have hitherto been kept 
in this country—and that each is capable of conferring on the other great 
and lasting benefits. Hence my retaining what constitutes a new feature 


“~ 


PREFACE BY THE TRANSLATOR AND EDITOR. ix 


in the second edition of Chauveau’s treatise—the comparison of the organs 
of Man with those of ANIMALS. 

I have omitted from the translation the references made to the Dro- 
medary and Rabbit; these animals seldom, if ever, coming under the notice 
of the comparative pathologist in this country. 

My grateful acknowledgments are due to my friend and colleague, 
Professor Chauveau, for the great courtesy with which he not only sanc- 
tioned the translation now before the public, but offered to supply me with 
the proof sheets of the new edition as it passed through the press. 

To the numerous professional friends who pressed upon me the necessity 
of making such an extensive sacrifice of my few leisure hours, by under- 
taking a work of this magnitude, I have to express my deep regret at the 
delay which has occured in its appearance. The fault was not mine: but for 
the disturbance and abeyance of all business, save that of slaughter, in and 
around Paris while the book was in course of publication, my task must 
have been achieved nearly two years ago. 

I may assure them, however,. that the delay has been rather beneficial 
than otherwise; as it has allowed me to give more time to perfect what 
might, under other circumstances, have been less complete and satisfactory. 


GEORGE FLEMING. 


Brompron BARRACKS, CHATHAM. 
February, 1873. 


PREFACE TO THE FIRST EDITION. 


To present in a concise and complete form an exact description of the 
anatomical machinery of which the bodies of our domesticated animals are 
composed, has been our aim in writing the book now offered for public 
appreciation. 

We have sought for concision, not only in language, but also in the 
choice of facts and ideas, with a kind of stubbornness. In imposing on 
ourselves this condition, we believe we have rendered a service to those 
who may have recourse to the book, in economising their time. In an age 
of progress like the present, when the sciences are becoming multiplied and 
developed, and when the human mind, seized by the fever of production, 
gives forth every day books consecrated to the study of these sciences, there 
is scarcely leisure to read and to learn. It is, therefore, the duty of a 
writer to be brief. If he loads his book with puerile details; if he says 
that which may éasily be divined by his reader; and if he describes facts 
and ideas too redundantly; will he have attained the wished-for perfection 
—in a word, will he be complete? No, he will be tedious: a serious 
inconvenience, which neither elegance, warmth, nor brilliancy of style will 
always excuse when met with in a didactic work, and especially in an 
elementary treatise. 

No effort has been spared to achieve exactitude—the primary desideratum 
in such a work as this; neither have evenings spent in bibliographic re- 
searches, nor fatigue in the dissecting-room been considered. All published 
writings on animal organisation, general treatises, special manuals, mono- 
graphs, and articles in periodicals have been read and interrogated. But we 
have more particularly sought for information from Nature—that certain 
and infallible guide, always wise, even in her diversities ; we have consulted 
her, scalpel in hand, with a perseverance that nothing could repel. Animals 
of every kind were had recourse to, and we have largely profited by the 
immense resources which our position as principal of anatomical teaching 
in the Imperial Veterinary School has placed at our disposal. 


xii PREFACE TO THE FIRST EDITION. 


It was not enough that we should be correct, that we should faithfally 
describe the organs of the animal economy. It was desirable that the truth 
might be presented from a high philosophical point of view—one that 
should rise above details. It is necessary in a book, and especially in one 
on anatomy, that there should be a salient idea which might indicate 
its purpose and originality, and distinguish it as something more than a 
mere arid catalogue, by unifying the thousand different objects of which 
it treats. In support of this, we would ask permission to explain, in a few 
words, the idea that presided in the construction of our work. 

Among the beings or objects composing the natural world, animals are 
distinguished by diversity in size and external conformation. Is this 
diversity repeated in their internal structure? When order and simplicity 
prevail everywhere else in nature, should we expect to find disorder and 
complication there, or look for as many different organisations as there are 
particular species? To state these questions, and to resolve them in the 
affirmative, would be to insult the wisdom of the Creator. The early 
naturalists, guided by instinct rather than knowledge, admired a certain 
uniformity in the composition of animals. ; 

It was a good inspiration, which threatened to become effaced at the 
period when anatomical science, diffused and cultivated everywhere with the 
most laudable eagerness, daily discovered the secrets of the organisation of 
new species. Without a guide in the search for analogies, struck with the 
apparent differences their scalpel exposed every moment, the anatomists of 
that epoch neglected to compare the diverse animals. In presence of a new 
form of organs, they believed in the existence of a new instrument, and 
created a new name to designate it. Then was human anatomy, and that of 
the Horse, Ox, etc., established ; monographs became multiplied; as tbe 
different opinions increased, so there was the greater need for a bond to 
unite these incongruous materials; confusion commenced, and chaos was 
about to appear; and the principle of analogies was on the point of being 
buried beneath the ruins of science. 

Happily, two men appeared, men of genius, who were the glory of 
France—G. Cuvier and Etienne Geoffroy Saint-Hilaire ; two names which 
will be for ever illustrious, and which we love to unite as the expression 
of one and the same symbol. 

The first, after immense researches, ventured to compare the imnu- 
merable species in the animal kingdom with each other; he seized their 
general characters—the analogies which allied them to one another; he 
weighed these analogies, contrasted them with the dissimilarities, and 
established among them different kinds and different degrees; and in this 
way was he able to form natural groups, themselves subdivided into several 
categories in which individuals were gathered together according to their 
analogies and affinities. Then the chaos was swept away, light appeared, 
and the field of science was no longer obscured ; comparative anatomy was 
created in all its branches, and the structure of the animal kingdom was 


PREFACE TO THE FIRST EDITION. xiii 


brought within those laws of uniformity which shine throughout the other 
parts of creation. 

Geoffroy Saint-Hilaire followed Cuvier over the same ground. More 
exclusive than Cuvier, he entirely neglected the differential characters, and 
allowed himself to be governed by the consideration of resemblances. He 
especially pursued the discovery of a fixed rule for guidance in the search 
after these resemblances—a difficult task, and a dangerous reef, upon 
which the sagacity of his illustrious rival was stranded. To be more 
certain than Cuvier, and the better to grasp his subject, he restricted the 
scope of his observations, confining himself more particularly to the class of 
vertebrata in order to solve the enigma whose answer he sought. At last 
he found it, and made it known to us in those memorable, though abstruse 
pages, in which the meaning is often obscure and hidden, but which 
contain, nevertheless, magnificent hymns chanted to the honour of the 
Creator. The shape and functions of organs, he says, do not offer any 
stability, only their relations are invariable; these alone cannot give 
deceptive indications in the comparison of the vital instruments. He thus 
founded his great principle of connections, firmly established its value, 
fortified it by accessory principles, and held it up to the generations to 
come as a compass, a succourable beacon-light, under whose protection they 
might proceed to the conquest of analogies with confidence and security. 
Then was the philosophical sentiment decidedly introduced into the 
researches in organisation, and anatomy became a veritable science. 

Enthusiastically admiring these two great masters, we glory in be- 
longing to their school; it is, therefore, enough to say that the prevailing 
idea in our work has been inspired by their labours. Thus, in describing 
the organs in the somewhat numerous species of animals treated of, 
and noting their differential characters, we have always endeavoured to 
demonstrate their analogies. 

The hopes that Geoffroy Saint-Hilaire entertained for the future of 
philosophical anatomy have not been entirely realised. Naturalists, it is 
true, have always cultivated this admirable science ; Lecoq has preserved 
its traditions at the Lyons Veterinary School, in his simple, lucid, and 
elevated teaching; and at Toulouse, an able and learned professor, Lavocat, 
~ has courageously hoisted his flag. But everywhere else, and particularly in 
the Medical Schools, has not anatomy remained essentially monographic 
and purely surgical? And many medical men and veterinary surgeons, only 
looking at the practical side of this science, and full of defiance with 
respect to speculative theories, will perhaps give us no credit for our efforts 
in bringing the anatomy of animals into philosophical courses. To these 
we have nothing to say; if they do not see how much science is developed 
and becomes comprehensible with. such elements; if they cannot under- 
stand all that is noble and useful in these generalising views; and if they 
do not feel elevated sentiments revolve in their mind in presence of the 
simplicity of Nature’s laws, it is because their thoughts are not in unison 


xiv PREFACE TO THE FIRST EDITION. 


with ours, and we carefully abstain from engaging in a sterile discussion 
with them. 

Such is our plan: have we executed it in a satisfactory manner ? We 
have not deluded ourselves with regard, to our strength, and willingly 
acknowledge that many resources and many qualities have failed us in 
carrying the enterprise to a favourable termination ; therefore we hope to 
be indulgently judged. 

If we have succeeded in facilitating the study of so important a subject 
as anatomy for the pupils of the veterinary schools ; if our book becomes, in 
the hands of practitioners, a useful surgical guide; if, lastly, medical men 
and naturalists find that it will assist them in their researches in com- 
parative anatomy, our object will have been attained, and we shall have 
received the best recompense which the honest writer can hope to obtain. 

Before terminating, a sentiment of justice and recognition again brings 
the honourable name of M. Lecog to our pen; the idea of this book was 
conceived at his lectures, and it is from these lectures that we have derived 
the major part of our materials; it was to satisfy the most imperious 
desire of our heart and conscience that we offered to dedicate this first 
attempt to him. Could it be better placed than under his patronage ? 

We have also willingly joined to his name that of M. H. Bouley, that 
eminent and devoted master, to whose advice we owe so much, and who has 
evinced the liveliest solicitude for us in circumstances which we can never 
forget. May he deign to accept this homage as the expression of our 
sincere recognition. 

We have found in the obligingness and intelligence of M. Rodet a very 
efficacious aid; he will permit us to tender all our gratitude. 

We have frequently put the complaisance of the students around us to a 
severe test; but they have never failed, and we are gratified in being able to 
thank them most cordially. We especially mention the name of M. Violet, 
whose intelligent zeal has spared us much toil in the difficult task imposed 
upon us. 


A. CHAUVEAU. 
Lyons, 


September 30, 1854, 


TABLE OF CONTENTS. 


a pees 
Translator and Editor’s Preface. . ‘ , 
Preface to the First Edition . : ‘ ‘i ‘ . ‘ 
Preface to the Second Edition : . z 3 E a 
Table of Contents , f : : F 5 : 

Table of Illustrations ‘ : - . ‘ i 


GENERAL CONSIDERATIONS. 


Definition and Division of Anatomy , ‘ 

Enumeration and Classification of the Domesticated Animals - 

General Idea of the Organisation of Animals, and the order followed i in studying 
their apparatus . 


BOOK I. 


LOCOMOTORY APPARATUS, 


First Section.—The Bones 
CuapPrer I.—The Bones in Generet 
Article 1.—The Skeleton . 
Article 1.—General Principles applicable. to the Study of all the Bones 
Name, Situation, Direction, and Configuration of the Bones 
Internal Conformation of the Bones. Structure of the Bones 
Development of the Bones 
Cuaprer II.—The Bones of Mammalia in Particular 
Article 1—Vertebral Column 
Characters Common to all the V esfabiee 
Characters Proper to the Vertcbree in each region 
1. Cervical Vertebree 
2. Dorsal Vertebree 
3. Lumbar Vertebre 
4. Sacrum 
5. Coceygeal Vertebne 
Of the Spine in General 
Differential Characters in ise Vertebral Columa of ‘oglier than Soliped 
Animals : 
Comparison of the Vortabual Calum of Man with that of Antasie 
Article 1.—Tbe Head é ; : ' . 
The Bones of the Cranium 


J. Occipital a _ : . . . 
2. Parietal . ‘ : . . % “ 
8. Frontal : . é, & 6 


2 


xviii TABLE OF CONTENTS. 


4. Ethmoid . 
5. Sphenoid 
6. Temporal 
The Bones of the Fae : 
1. Superior Maxillary or Great Supermaxillary ; 
. Intermaxilla, Incisive Bone, Small Supermaxilla, or Premncilie 
. Palate 
Pterygoid 
. Zygomatic : 
. Lachrymal 
. Bones proper to the Nose, or Supernasal 
Turbinated Bones 
. Vomer 
10. Inferior Maxillary 
ll. Hyoid. 
Of the Head in General 
Differential Characters in the Head. of other than Soliped Animals | 
Comparison of the Head of Man with that of Animals 
Article 11.—The Thorax . : : 
The Bones of the Thorax in Partibulay 
1. Sternum of the Horse 
2. Ribs . 5 
Of the Thorax in General . 
Differential Characters in the Thorax of other than Soliped Animals 
1. Sternum . 
2. Ribs 
Comparison of the Thorax of Man with that of Animals 
1. Sternum ; ‘ 4 ‘ F : . 
2. Ribs ; F 2 ‘ 
Article 1v.— Anterior Limbs . 3 3" ° : 
Shoulder ‘ c 7 : 
Scapula i F 5 F : 
Arm. 2 = : ‘i - = . 
Humerus . : : - 5 ‘ F 
Fore-arm ‘ 5 3 r is 2 
1. Radius 
2. Ulna 
Anterior Foot , 
1. Bones of the Carpus 
2. Bones of the Metacarpus 3 
3. Bones of the Digit, or Phalangeal Region 


OMAR owed + 


Differential Characters in the Anterior Limb of other than Soliped Ausnate 
Comparison of the Thoracic Limb of Man with that of the Domesticated 


Animals ‘ i 
Article v.—Posterior Limbs . ‘ is 
Pelvis 3 ; < . ¥ ‘ 
A. Coxee : F 4 e 5 3 
. The Pelvis in Gensral : 5 . a 
Thigh . ‘ : . 
Femur : i‘ : . . 
Leg. : : . ‘ 
1. Tibia . 
2. Fibula 
3. Patella 


TABLE OF CONTENTS. xix 


Posterior Foot . 
1. Bones of the Tarsus 
2. Bones of the Metatarsus 


105 
3. Bones of the Digital Region 105 
Differential Characters in the Posterior Limb ‘of other then Soliped 
Animals 105 
Comparison of the Abdomiual Liab of Man with that of the Plonidsticatad 
Animals ‘ . 107 
Article v1—The Limbs in Genus amid their Payallstian : 109 
Cuaprer III.—The Bones in Birds 5 . 112 
Cuapter [V.—Theory of the Vertcbril Constitution of ihe Skeleton : 118 
Seconp Srction.—The Articulations ‘ . é . 121 
Cuarrer IL.—The Articulations in General A 3 i ‘ 121 
General Characters of Diarthroses . z " . ‘ . 123 
General Characters of Synarthroses . : 3 128 
General Characters of Amphiarthroses or Symphyees : . 129 
Cuaprer II.—The Articulations of Mammalia in Particular 3 129 
Article 1.— Articulations of the Spine 2 . 180 
Articulations between the Vertebre, or Inter eartebral Atealstions 3 130 
Article u.—Articulations of the Head 2 : : . 135 
1. Atlo-axoid Articulation . ‘ $ : 7 135 
2. Occipito-atloid Articulation . p - 137 
8. Articulations between the Bones of thie fed ‘ : 4 137 
4. Temporo-maxillary Articulation ‘ 3 ‘ F 138 
5. Hyoideal Articulations . . r . 2 . 139 
Article 111.— Articulations of the Thorax ‘ 140 
1, Costo-vertebral, or Articulations of the Ribs witehs the Valtebral etumina 140 
2. Costo-sternal Articulations . . 141 
8. Chondro-costal Articulations, or Avtiontations between the Ribs 4 142 
4, Articulations between the Costal Cartilages . 5 3 142 
5. Sternal Articulation peculiar to the Ox and Pig . : 142 
6. The Articulations of the Thorax considered in a general manner, with 
respect to their Movements . , : : 142 
Article 1v.—Articulations of the Anterior Linibs F 3 143 
1. Scapulo-humeral Articulation. A : é 143 
2. Humero-radial Articulation 6 . 144 
8. Radio-ulnar Articulation : i 147 
4, Articulations of the Carpus Z : ‘ 148 
5. Intermetacarpal Articulations. ; : 152 
6. Metacarpo-phalangeal Articulations 153 
7. Articulation of the First Phalanx ithe the Seconil, or : Hest Tnier: 
phalangeal Articulation : 156 
8. Articulation of the Second Philans with the Third, Second Tuter- 
phalangeal Articulation, or Articulation of the Foot ‘ 157 
Article v-—Articulations of the Posterior Limbs : . 5 . 159 
1. Articulations of the Pelvis . : : . : 159 
2. Coxo-femoral Articulation . : . . . . I6l 
3. Femoro-tibial Articulation i ‘ . 163 
4, Tibio-fibular Articulation i ‘ . 7 167 
5. Articulations of the Tarsus, or Hock : 3 ‘ 168 
Cuarter III. —The Articulations in Birds . 7 7 ' 172 
"PyTRD Srction.—The Muscles. ; 173 
Cuarrer I.—General Considerations on the Striped ‘Muscles : : 174 


The Striped Muscles in General : ‘ . . 174 


XX TABLE OF CONTENTS. 


PAGE 
Structure of the Striped Muscles. ° ° « 178 
Physico-chemical Properties of the Striped Muscles . 3 S 180 
Physiological Properties of the i Muscles. . . . 181 
Annexes of the Muscles : : ° a f 183 
Manner of Studying the Muscles. : a 3 . 183 
Cuarrer II.—The Muscles of Mammalia in Particular é 3 3 186 
Article i—The Muscles of the Trunk . ‘i ‘ Z . 186 
Subcutaneous Region . : ‘ é ‘ - ; 186 
Fleshy Panniculus ‘ i j . - . . 186 
Cervical Region . < ‘ 187 
A, Superior Cervical or Spinal Region of the Neck . . . 187 
1. Rhomboideus 5 ‘ : ‘ 4 ‘ 188 
2. Angularis Muscle of the Scapula : : F . . 189 
8. Splenius . : : . . : : 189 
4. Great Complexes. i : : A . 191 
5. Small Complexus (Trdislosnacteltensy : : 191 
6. Transverse Spinous Muscle of the Neck (Spinalis Colli) : . 193 
7. Intertransversal Muscle of the Neck ; ; 193 
8. Great Oblique Musele of the Head (Obliquus Cavite Tiana) . 198 
9. Small Oblique Muscle of the Head (Obliquus Capitis Superior) . 194 
10. Great Posterior Straight Muscle of the Head . 195 
11. Small Posterior Straight Muscle (Rectus Capitis Padtions Minor) 195 
B. Inferior Cervical or Trachelian Region . . 195 
1. Subcutaneous Muscle of the Neck ’Pannleutas Carnosus) . 196 
2. Mastoido-humeralis (Levator Humeri). 5 . . . 196 
3. Sterno-maxillaris . ; : é 2 3 ‘ 198 
4. Sterno-hyoideus . : 7 3 : : . 198 
5. Sterno-thyroideus. : : : 198 
6. Omo-hyoideus, or Subscaqule-hyeldens 198 

7. Great Anterior Straight Muscle of the Head (Rectus Capitis Anticus 
Major) ‘ 199 

8. Small Anterior Straight Muscle of the Head eating Capitis Anticus 
Minor) é ‘ . 199 
9. Small Lateral Straig). t Muscle (Obliquus Copiti Antivag) ; 199 
10. Scalenus . : . 200 
11. Long Muscle of the Neck Cones Coli) . 200 

Differential Characters in the Muscles of the Cervical Reston of other tha 
Soliped Animals . : 3 F F ‘ 201 
A. Superior Cervical Region 3 3 : 3 . 201 
s. Inferior Cervical or Trachelian Heston . i ‘ : 201 
Spinal Region of the Back and Loins. dé : » 203 
1, Trapezius i i 3 5 203 
2. Great Dorsal ‘atiedioons Dad . , 203 
8. Small Anterior Serrated Muscle (Super ficialis Gostaruaiy : 205 
4, Small Posterior Serrated Muscle (Superficialis Costarum) . . 205 
5. Tlio-spinalis Muscle (Longissimus Dorsi) ‘ : 206 
6. Common Intercostal Muscle (Transversalis Costarum) : 208 

7. Transverse Spinous Muscle of the Back and Loins (Spinalis and 
Semispinalis Dorsi ! 209 

Differential Characters in the Muscles of the Spinal Révion of the Back sual 
Loins of other than Soliped Animals . 909 

Comparison of the Muscles of tle Back, Neck, and ere in Ria: with fii 
analogous Muscles in the Domesticated Animals . 209 


A. Muscles of the Back ard Cervix . : ‘ F , ‘ 210 


TABLE OF CONTENTS. xxi 


PAGE 

B. Muscles of the Neck . . : : i i: » 211 
Sublumbar or In “erior Lumbar Region fi ‘ ‘ ; 211 
1. Iliac Fascia or Lumbo-iliac Aponeurosis . F « 212 
2. Great Psoas Muscle. 4 - - ‘ 212 

3. Iliac Psoas Muscle (Iliacus) . : ‘ : : » 212 
4. Small Psoas Muscle. F : ‘ 214 
5. Square Muscle of the Loins (Gaevoctumibelis) j 214 

6. Intertransverse Muscles of the Loins (Intertransversales Lamborum) 215 


Differential Characters in the Muscles of the Sublumbar Region of other 


than Soliped Animals . . 215 
Comparison of the Sublumbar Muscles of Man with those a Kiet : 215 
Coccygeal Region. 3 , 2 . ‘ 3 . 215 
1. Sacro-coccygeal Muscles Z : 215 
2. Ischio-coccygeus (Compressor Caceyaaus) : : . 217 
Region of the Head . i : F : : 217 
A. Facial Region : at . : . . 217 
1. Tabialis (Orbicularis Oris) 3 . . ‘ - 217 
2. Alveolo-labialis (Buccinator) s 5 ; . 218 
3. Zygomatico-labialis (Zygomaticus) . . : : 219 
4, Lachrymo-labial, or Lachrymal Muscle . ‘ . 220 
5. Sunornase labialis (Levator Labii Superioris) : 220 
6. Supermaxillo-labialis (Nasalis Longus Labii Supevidris) : . 220 
7. Great Supermaxillo Nasalis (Dilatator Naris Lateralis) P 221 
8. Small Supermaxillo-nasalis (Nasalis Brevis Labii pee . 221 
9. Transversalis Nasi (Dilatator Naris Anterior). 221 
10. Middle Anterior Muscle (Depressor Labii Superiori) . 222 
11. Maxillo-labialis (Depressor Labii Inferioris) . : ‘ 222 
12. Mento-labialis, or Muscle of the Chin ‘ é ; . 222 
13. Middle Posterior Muscle (Levator Menti) , ‘ 222 
B. Masseterine or Temporo-maxillary Region . F 223 
1. Masseter : : : . ; 223 
2. Temporal or Crotaphitic Muscle ‘ : é . 223 
8. Internal Pterygoid (Pterygoideus Intern) ‘ . ‘ 224 
4, External Pterygoid ‘ ; : ‘i . 224 
5. Digastricus . ‘ ‘ > , F 225 
co. Hyoideal Region . ‘ - . : F » 225 
1. Mylo-hyoideus ¥ z z : j : 225 
2. Genio-hyoideus . J : 5 + 226 
3. Stylo-hyoideus tit eutdeus, Magnus) F F : 227 
4, Kerato-hyoideus (Hyoideus sila 3 . 3 . 227 
5. Occipito-styloideus  . : . ‘ - 227 
6. Tranversalis Hyoidei : 228 
Differential Characters in the Muscles of the Head of other than Soliped 
Animals é r 3 ; : . : . 228 
A. Facial Region . : : 228 
B. Masseterine or Manapote aanctlibaey Baeion a : . 229 
9. Hyoid Region é 230 
Cormpantion. of the Muscles of the Human Head with those of the Domes 
ticated Animals 230 
A. Epicranial Muscles : : : : | 
B. Muscles of the Face F : . . ca 
c. Muscles of the Lower Jaw 5 : . : » 231 
p. Hyoid Muscles. ‘ ‘ : . ‘ : 231 
Axillary Region . . ° : . ° . . 231 


TABLE OF CONTENTS. 


PAGE 


1. Superficial Pectoral (Pectoralis Transversus) . : F 23% 
2. Deep Pectoral ; 233 
Diflerential Characters in the Muscles of the Axillary Region of thee than 
Soliped Animals ‘ : ‘ ; . Z 235 
Costal Region ; : : é . : 235 
1. Great Serratus 5 ‘ é . 236 
2. Transverse Muscle of the Ribs (Lateral Sterni) . 236 
3. External Intercostals ; ‘ ‘4 é . 287 
4, Internal Intercostals a ‘5 . 7 . 237 
5. Supercostals (Levatores Costarum) . . : . 237 
6. Triangularis of the Sternum (Sterno- epctales) ‘ 237 
Differential Characters in the Muscles of the Costal Region of other than 
Soliped Animals . ‘ 238 
Comparison of the Thoracic Muscles of Man wiih those ‘of the Damncsticnted 
Animals : ‘ F . ‘ 238 
Inferior Abdominal Rasta 5 ‘ F é : . 238 
1. Abdominal Tunic : 3 r ‘ ‘ F 239 
2, White Line. : ‘i 240 
3. Great or External Oblique of the Abdomda F : ‘ 240 
4. Small or Internal Oblique of the Abdomen . F ‘ 242 
5. Great Rectus Muscle of the Abdomen . : ‘ : 243 
6. Transverse Muscle of the Abdomen . 244 
Differential Characters in the Muscles of the Abdominal Region of other 
than Soliped Animals 2 ‘ 245 
Comparison of the Abdominal Muscles of Man with those of Animals . 245 
Diaphragmatic Region . é : : . 246 
Diaphragm : 3 = ‘ 4 : ; 246 
Differential Characters in the Diaphragm of other than Soliped Animals 248 
Comparison of the Diaphragm of Man with that of Animals. ‘ 248 
Article 1.—Muscles of the Anterior Limbs. 5 : . 248 
Muscles of the Shoulder ‘ . - : ‘ : 249 
A. External Scapular Region. : ‘ < . 249 
1. External Scapular Aponeurosis . 249 
2. Long Abductor of the Arm, or Scapular portion af the Deltoid (Teres 
Major) . : é . 249 
3. Short Abductor of the on or Toins nor F és ‘ 250 
4, Superspinatus (Antea Spinatus) . z : , . 251 
5. Subspinatus (Postea Spinatus) . 4 : - is 251 
B. Internal Scapular Region . 7 , : 252 
1. Subseapularis  . : ‘ é : 252 
2. Adductor of the Arm, or - Teres Major ‘ 5 . 253 
3. Coraco-humeralis, Cai aco-brachialis, or Omo-brachialis A ‘ 254 
4, Small Scapulo-humeralis 254 
Differential Characters in the Muscles of ihe Shoulder of other then Soliped 
Animals. 254 
Comparison of the Muscles of the Shoulder of Man with those of Animals . 255 
Muscles of the Arm. ° ‘ ‘i : 255 
A. Anterior Brachial Région. _ . 255 
1. Long Flexor of the Fore-arm, or Brachial Biceps (Flexor Brachii) 255 
2. Short Flexor of the Fore-arm (Humeralis Externus) . ; 256 
B. Posterior Brachial Region . : . 258 
1. Long Extensor of the Fore-arm (Caput Magnum) 3 : 258 
2. Large Extensor of the Fore-arm (Caput Magnum) . : 258 


3. Short Extensor of the Fore arm (Caput Medium) 4 ‘ 259 


TABLE OF CONTENTS. 


4. Middle Extensor of the Fore-arm (Caput Parvum) 
5. Small Extensor of the Fore-arm, or Anconeus : 
Differential Characters in the Muscles of the Arm of other then Soliped 
Animals ‘ 
Comparison of the Muscles of the Arm of Man with those of Antinaly 
Muscles of the Fore-arm 
Antibrachial Aponeurosis 
a, Anterior Antibrachial Region. 
1. Anterior Extensor of the Metacarpus (Extensor Metncarpi tiene) 
2. Oblique Extensor of the Metacarpus (Extensor Metacarpi Obli oe 
3. Anterior Extensor of the Phalanges (Extensor Pedis. 
4. Lateral Extensor of the Phalanges aaa Suffraginis) 
s. Posterior Antibrachial Region 
1. External Flexor of the Metacarpus, « or Posterior Winaries , 
2. Oblique Flexor of the Metacarpus, or Anterior Ulnaris (Flexor 
Metacarpi Medius) * 
3. Internal Flexor of the Metacarpus, or Palmeria Magnus (Flexor 
Metacarpi Internus) 
4. Superficial Flexor, Sublimis of the Phalanges, or  Perforatus 
5. Deep Flexor of the Phalanges, or Perforans 
Differential Characters in the Muscles of the Fore-arm of other thats Soliped 


Animals . . . 
Muscles proper to the Fore-arm i in : Carnivora . . . 

1. Proper Extensor of the Thumb and Index . ; 7 

2. Long Supinator. 7 3 . . r 

8. Short Supinator .. . ‘ ‘ . 

4. Round Pronator : : : ‘ : % 


5. Square Pronator 
Comparison of the Muscles of the Fore- -arm. of Man with itiane of Animal 
a, Anterior Region % ‘ 3 Fi : a 
B. External Region : . : ‘ 
c. Posterior Region i . i ‘ 
Muscles of the Anterior Foot or Head . : A 
A. Muscles of the Anterior Foot in Canitvery ‘ : i 
. Short Abductor of the Thumb . . . 7 . 
. Opponens of the Thumb. : ° , , 
. Short Flexor of the Thumb - . . . . 
. Adductor of the Index ‘ . . . . 
. Cutaneous Palmar : Palmaris Brevis) . . . ° 
. Adductor of the Small Digit ‘ 2 . . . 
Short Flexor of the Small Digit és 3 A . 
. Opponens of the Small Digit ‘ : . . 
. Lumbrici ‘ 3 7 . 
. Metacarpal Tikensesoais: uses 3 ‘ ‘ : 
B, Muscles of the Anterior Foot in the Pig . . é 
c. Muscles of the Anterior Foot in Solipeds ‘ é ‘ 
p. Muscles of the Anterior Foot in Ruminants “ . 
Comparison of the Hand of Man with that of Animals , 
A. Muscles of the Thenar Eminence . 3 : . 
B. Muscles of the Hypothenar Eminence. : . . 
c. Interosseous Muscles ‘ . s é 
Article 11.—Museles of the Posterior Limbs i - 
Muscles of the Gluteal Region, or Croup , . 
1, Superficial Gluteus (Gluteus Externus) —. . 


SOMNAAEWDE, 


ry 


xviii 
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xxiv 


TABLE OF CONTENTS. 


2. Middle Gluteus (Gluteus Maximus) 
3. Deep Gluteus (Gluteus Internus) 
Differential Characters in the Muscles of the Gluteal Region of ather ita 
Soliped Animals . , 
Comparison of the Gluteal Muscles of Man sel those of Animals ‘ 
Muscles of the Thigh , 
a. Anterior Crural, or Femoral Region . : : 
1. Muscle of the Fascia Lata (Tensor Vagine). 
2. Crural Triceps 6 : 
8. Anterior Gracilis (Crureus vel Croralis). 
B. Posterior Crural Region F 
1. Long Vastus (Biceps Abductor Femor is) 
2. Semitendinosus Muscle (Adductor Tibialis) 
3. Semimembranosus (Adductor Tibialis) . 
c. Internal Crural Region ‘ 
. Long Adductor of the Leg (Sartorius) 
. Short Adductor of the Leg (Gracilis) 
. Pectineus 
. Small Adductor of the Thigh (Adductor Femoris) . 
. Great Adductor of the Thigh (Adductor ssiceks 
. Square Crural (Quadratus Femoris). 
. External Obturator 
. Internal Obturator . 
. Gemelli of the Pelvis eGeiniut) 
Differential Characters in the Muscles of the Thigh af other shai Soliped 
Animals : 2 : : 
4. Anterior Crural Region 
B. Posterior Crural Region 
c. Internal Crural Region . 
Comparison of the Muscles of Man’s Thigh swith those of the Thigh of 
Animals : 2 - é . 
A. Anterior Muscles . : 
s. Muscles of the Posterior Region 
c. Muscles of the Internal Region 7 
Muscles of the Leg : . é . 
Tibial Aponeurosis 
A. Anterior Tibial Region ‘ 
1. Anterior Extensor of the Phalanges (Extensor Pedis) - 
2 Lateral Extensor of the Phalanges eo 
3. Flexor of the Metat:rsus F 
B. Posterior Tibial Region 
. Gastrocnemii, or Gemelli of the Tibia (Gastrvonemins Batons) 
. Soleus, or Solearis (Plantaris) 
. Superficial Flexor of the Pha'anges, or Perforatus (Gastroonemius 
Internus) . 
4. Popliteus ; 
5. Deep Flexor of the Phalanges, or Porthnans ( Flexor Pedi) 
6. Oblique Flexor of the Phalanges (Flexor Pedis Accegssorius) . 
Differential Characters in the Muscles of the Leg of other than dia 


DHIARrpHDe, 


wrne 


Animals 
A. Anterior Tibial Region 
B. Posterior Tibial Region 
Comparison of the Muscles of the Leg of Man with those of Animals 
A. Anterior Region 


PAGE 
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282 


283 
283 
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284 
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285 
286 
286 
287 
288 
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288 
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289 
291 
291 
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TABLE OF CONTENTS. 


gs, External Region . 
c. Posterior Region 
Muscles of the Posterior Foot 
Comparison of the Muscles of the Foot of Man with those of Animals 
A. Dorsal Region 
s. Plantar Region 
c. Interosseous Muscles 
Cuarter ITI—The Muscles in Birds . 
Cuartrr IV.—General Table of the insertions of the Museles 3 in | Solipeds 


BOOK II. 


THE DIGESTIVE APPARATUS, 


Cuapter I.—General Considerations on the Digestive Apparatus 
Cuarter Il.—The Digestive Apparatus in Mammalia 
Article 1.—Preparatory eee ot the ae See 
The Mouth 
Lips. . 
Cheeks 
. Palate . 
. Tongue 
. Soft Palate 
. Teeth 
. The Mouth in General . 
Differential Characters in the Mouth of other than Soliped Animals 
Comparison of the Mouth of Man with that of Animals 
The Salivary Glands i 
1, Parotid Gland . 
2. Maxillary, or Submaxillary Gland . 
3. Sublingual Gland 
4. Molar Glands ‘ 
5. Labial, Lingual, and Palatine Glonds 3 
Differential Characters in the Salivary Glands of other thaw Soliped 
Animals ‘ 
Comparison of the Salivary ‘Glands of Man att thoes of Animals 
The Pharynx 
Differential Characters in the Diaries of other ‘tien Soliped Misia 3 
Comparison of the Pharynx of Man with that of Animals 
The @sophagus 
Differential Characters in the (Raowhawne of other ‘ia Seine Autiaals 
Comparison of the esophagus uf Man with that of Animals : 
Article 1.—The Essential Organs of Digestion 
The Abdominal Cavity . 
Differential Characters in the Abdominal Cavity of “other than 8. JHipeil 
Animals ‘ 
Comparison of the Abddininel Cavity of Man with that of Aeimels: 
The Stomach. . ts : ‘ 
1. The Stomach of Solipeds F ‘ 
Differential Characters in the Stomach of other than Soliped Animals 
1. The Stomach of the Pig 
2. The Stomach of Carnivora . 
3. The Stomach of Ruminants 
Comparison of the Stomach of Man with that of Attias 


Ce oe ee 


XXV 
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313 
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315 


325 
330 
330 
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332 
332 
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340 
344 
355 
356 
362 
364 
365 
367 
369 
369 
370 


370 
372 
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376 
377 
377 
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380 
380 
380 


384 
385 
385 
385 
393 
893 
393 
393 
400 


xxvi TABLE OF CONTENTS. 


PAGE 

The Intestines 7 : : . ° 5 A 400 

1. The Small Intestine : . . . . . 400 

2. The Large Intestine. % : 7 < : 407 

a. Coecum é ‘ F . 407 

B. Colon. F : : : . . 410 

c. Rectum . 413 

Differential Charstens i in the fraestines of other than Soliped Aniiale : 414 

1. The Intestines of Ruminants : 7 F 3 . 414 

2. The Intestines of the Pig : : , j e 416 

3. The Intestines of Carnivora F . . 416 

Comparison of the Intestines of Man with those of Animals 417 
General and Comparative Survey of the Abdominal or Essential Portion of 

the Digestive Canal. . 418 

Organs Annexed to the Ahduainel Putian of hie Hiessuve Cunal ‘ 419 

1. Liver j : ‘ és : ‘ . 419 

2. Pancreas . ‘ . : ‘ ‘ 427 

3. Spleen z 428 
Differential Characters in ite Or; an ‘Aanescedl to the Abalone Portion of 

the Digestive Canal in other than Soliped Animals 4382 
Comparison of the Organs Annexed to the Abdominal Portion of the Digestive 

Canal of Man with those of Animals . ‘ 4 . 434 

Cuapter III.-—The Digestive Apparatus of Birds . . : é 435 

BOOK III. 
RESPIRATORY APPARATUS, 

Cuapter I.—Respiratory Apparatus in Mammalia . és . . 439 

The Nasal Cavities . ‘ . : . ‘ 439 

1. The Nostrils , . . . : . 440 

2. The Nasal Fossee : . . . . F 441 

3. The Sipuses 446 

Differential Characters in the Nasal Cavities of other than Boliped Animals 448 

Comparison of the Nasal Cavities of Man with those of Animals ‘5 449 

The Air-tube succeeding the Nasal Cavities 2 ‘ « » 449 

1. The Larynx . ‘ . . & , 449 

2. The Trachea . ‘A A * ° . 457 

3. The Bronchi ; 460 
Differential Characters in the Aietube suecsading the Nasal Fosse of other 

than Soliped Animals 461 
Comparison of the Larynx aud Trachea of Man with these Organs in the 

Domesticated Animals . . ‘ 462 

The Thorax . . 462 

Differential Characters in es Merage of other fin Soliped Nrimoods 466 

The Lungs ‘ . 466 

Differential Characters in he ere of other than Soliped Atal : 470 
Comparison of the Larynx, Trachea, and Lungs of Man with the same 

Organs in Animals . 471 

E Glandiform Bodies connected with the Respiratory Apparat ‘ 472 

. The Thyroid Body . : . 472 

2 The Thymus Gland ‘ 473 


Differential Characters in the Glandiform Bodies annexed to the Respiratory 
Apparatus of other than Soliped Animals ‘ . 474 


TABLE OF CONTENTS. xxvii 


Comparison of the Glandiform Bodies annexed to the Respiratory Apparatus ie 
in Man with those of Animals ‘ 7 . . . 475 
Cuarter II.—The Respiratory Apparatus of Birds 5 : . - 475 
BOOK IV. 
URINARY APPARATUS. 

1. The Kidneys . . Z é ‘ ‘ 7 484 
2. The Ureters : e ‘ ‘ : . 490 
3. The Bladder . c : ‘ ‘ , z 491 
4. The Urethra. é : : z 2 . 493 
5. The Suprarenal Capsules : 494 

Differential Characters of the Tikinary Apparatas in “thes thou Soliped 
Animals ‘ 495 
Comparison of the Urinary Avgparitus of Man with that of Avinials . 496 

BOOK V. 
CIRCULATORY APPARATUS. 

First Section.—The Heart : : , F : « 499 
1. The Heart as a Whole F : 5 . F 499 
2. External Conformation of the Hae ‘ : ‘ 3 - 500 
3. Internal Conformation of the Hvart . é : s s 503 
4. Structure of the Heart . 4 7 - . . - 507 
5. The Pericardium . : ‘ “i : Fs - 512 
6. The Action of the Heart. . 513 
Differential Characters in the Ebant of sthee than Solipad Animals 5 513 
Comparison of the Heart of Man with that of Animals sl ‘ . 514 
Seconp Section.—The Arteries ; ; ‘ ! - : 515 
Cuapter I.—General Considerations . : - . A . 515 
Cuaprer II.—Pulmonary Artery . ‘ . 3 ° . 521 
Cuarrer III.—Aorta . 2 ei . . 522 
Article 1—Common Aorta, or “Aortie Trunk . . _ ‘ 522 
Cardiac, or Coronary Arteries . A . 3 . - 523 
Article 1.—Posterior Aorta é : . ‘ A 523 
Parietal Branches of the Posterior Aorta . 3 3 ‘ . 525 
1, Intercostal Arteries ‘ 7 . 7 < é 525 
2.. Lumbar Arteries. : - ‘ ; . . 526 
3. Diaphragmatic Arteries : 5 . , ‘ 526 
4. Middle Sacral Artery : : 5 ‘ . 526 
Visceral Branches of the Posterior Aorta “ ‘ : ‘4 526 
1. Broncho-Césophageal Trunk E : . 526 
2. Coeliac Artery . ‘ ‘ ; . ‘ 527 
3. Great Mesenteric Artery £ 7 : : . §29 
4, Small Mesenteric Artery . ¥ ‘ ‘ é 532 
5. Renal, or Emulgent Arteries ” J A . 584 
6. Spermatic Arteries . ‘ 534 
7. Small Testicular Arteries (Male), Uterine Aviadien (Female) . 535 

Differential Characters in the Posterior Aorta and its Collateral Branches of 
other than Soliped Animals é ; F , he 585 
1. Posterior Aorta in Ruminants 3 2 : . 535 
2. Posterior Aorta in the Pig ; “ “ ; 537 
38. Posterior Aorta in Carnivora 3 ‘: . 537 


Comparison of the Aorta of Man with that of Animals : - - 538 


xXvili TABLE OF CONTENTS. 


Article nt.—Internal Iliac Arteries, or Pelvic Trunks F ; 

. Umbilical Artery . 

. Internal Pudie, or Bulbous Avery 

. Subsacral, or Lateral Sacral Artery 

. Iliaco-muscular, or Ilio-lumbar Artery 

. Gluteal Artery 

. Obturator Artery 

. Iliaco-femoral Artery ‘ 

Differential Characters in the Internal Iliac Aarteries of other than Soliped 
Animals : 5 : 

1. Internal Tiac Meieries of Tintaadts 

2. Internal Iliac Arteries of the Pig 

8. Internal Iliac Arteries of the Carnivora . 

Comparison of the Internal Iliac Arteries of Man with those of sernal 
Article 1v.—Exterual Iliac Arteries, or Crural Trunks 
Femoral Artery . 

1. Prepubic Artery . 

2. Deep Femoral, Deep Muscular, or iGirent Postoniey Muscular Artery of 

the Thigh i ‘ 

3. Superficial Muscular, or Great Anterior Muscular Avery 

4. Innominate Muscular, or Small Muscular Arteries . 

5. Saphena Artery : 3 ‘ . ‘ . 
Popliteal Artery . ‘ 3 : . 
Terminal Branches of the Popliteal Artery 

1. Posterior Tibial Artery 

2. Anterior Tibial Artery 

3. Pedal Artery 

Differential Characters in the External ine Ar re of other than Solined 

Animals fs 

1, External Tiac Arteries of Ruminants 

2, External Iliac Arteries of the Pig 

3. External Iliac Arteries of Carnivora 

Comparison of the External Iliac Arteries of Man with ifiose of Andmdle 
Article v.—Anterior Aorta 
Article v1.—Axillary Arteries, or Bradhial Praake 
Collateral Branches of the Axillary Arteries . 
1. Dorsal, Dorso-muscular, or Transverse Cervical Agary 
. Superior Cervical, Cervico-muscular, or Deep Cervical Artery 
. Vertebral Artery 
. Internal Thoracic, or ‘teen Mammary Aetery A 
. External Tvarntic, External Mammary, or Inferior Thoracic Revere 
. Inferior Cervical Artery 
. Superscapular Artery 
. Subseapular Artery ; : 2 ; 
Terminal Branch of the Brachial Tran, or Humeral Artery 
1. Anterior Radial Artery ; 
2. Posterior Radial Artery 
1. First Terminal Branch of the Posterior Radial Artery, or Common 
Trunk of the Interosseous Metacarpals 
2. Second Terminal Branch of the Posterior Radial Avhony: or Colla- 
teral Artery of the Canon 3 é 
Differential Characters in the Axillary Arteries of Non- sotiped Animals 
1, Axillary Arteries of Ruminants 
2. Axillary Arteries of the Pig 


PUMA wWde 


DN Op wD 


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TABLE OF CONTENTS. 


3. Axillary Arteries of Carnivora . : . 
Comparison of the Axillary Arteries of Man with those of Animals 
Article vir—Common Carotid Arteries 

Occipital Artery é 
Internal Carotid Artery 
External Carotid Artery . 

1, External Maxillary, Facial, or Glosso-Facial Axtery 

2. Maxillo-Muscular Artery . : 

3. Posterior Auricular Artery : 

4, Superficial Temporal Artery, or Temporal Trunk 

5. Internal Maxillary, or Gutturo-maxillary Artery 


Differential Characters in the Carotid Arteries of Non-soliped Acitinals 


1, Carotid Arteries of Carnivora 
2. Carotid Arteries of the Pig . 
8. Carotid Arteries of Bunions ; 
Comparison of the Carotid Arteries of Man with those of Katronis : 
Tuirp Section.—The Veins 
Cuarter I.—General Considerations 
Cuapter II.—Veins of the Lesser Circulation, or 7 Palmonasy Veins 
Cuapter III.—Veins of tle General Circulation 
Article 1.—Cardiac, or Coronary Veins 
Article 1.—Anterior Vena Cava 
Jugular Veins - 
Roots of the Jugular Z : 
1. Superficial Temporal Vein 


2. Internal Maxillary Vein F é . 
3. The Sinuses of the Dura Mater . : : 5 
Axillary Veins . : : F F F : 
1. Subscapular Vein : é 7 . 
2. Humeral Vein . F E . 
3. Spur, or Subcutaneous Thoracic Veia a zi . 
4, Deep Veins of the Fore-arm ; ‘ ‘ - 
5. Superficial Veins of the Fore-arm - . 
6. Metacarpal Veins . F ‘ ‘ : ‘ 
7. Digital Veins . 7 és . 
8. Veins of the Foot, or Uoxval Revton : 5 . 
a, External Venous Apparatus . : < . 
b. Internal, or Intra-osseous Venous Apparatus . F 
Article m1.—Posterior Vena Cava ‘ ‘ e ° 
Diaphragmatic Veins. ‘ 7 . : 
Vena Porte . : : ‘ 
1. Roots of the Vena Portes 2 : . 


2. Lateral Affluents of the Vena Porte 
Renal Veins % 

Spermatic Veins 

Lumbar Veins 

Common Iliac Veins, or Pelvi gpl mane 

. Internal Iliac Vein . F ; p ‘ F 
. External Iliac Vein r 3 P, 

. Femoral Vein 

. Popliteal Vein . : ° . 

Deep Veins of the Leg ‘ ‘ . : 

. Superficial Veins of the Leg. $ ; 

. Metatarsal Veins. 3 ‘ * : 

. Veins of the Digital Region. é . . 


xxix 
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XXX TABLE OF CONTENTS. 


Differential Characters in the Veins of other than Soliped Animals . 
Comparison of the Veins of Man with those of Animals 
Fourrs Srcrion.—The Lymphatics 
Cuarrnr I.—General Considerations 


' Lymphatic Vessels . : . 5 ‘ 7 
Lymphatic Glands, or Ganglia i : 7 ‘ 
Cuarter I].—The Lymphatics in Particular. ‘i 3 ‘ 


Article 1.—The Thoracic Duct . 
Article u—The Lymphaties which constitute the Affiuents of sig Thewaie 


Duct . 
Lymphatics of the Abdominal Limb, Pelvis, Abdominal Parietes, and 
Pelvi-inguinal Organs : . . 
1. Sublumbar Glands . 
2. Deep Inguinal Glands 
8. Superficial Inguinal Glands 
4. Popliteal Glands é 
5. Iliac Glands ‘ : 
6. Precrural Glands ‘ 3 
Lymphatics of the Abdominal Viera j 
1. Glands and Lymphatic Vessels of the Reston and Floating Colon 
2. Glands and Lymphatic Vessels of the Large Colon ‘ 
3. Glands and Lymphatic Vessels of the Caecum : : 
4. Glands and Lymphatic Vessels of the Small Intestine 
5. Glands and Lymphatic Vessels of the Stomach 
6. Glands and Lymphatic Vessels of the Spleen and Liver . 
Glands and Lymphatic Vessels of the Organs contained in the Thoracic 
Cavity a : 
Glands and Lymphatic Vessels of the Thoverte Parietes 
Lymphatic Vessels of the Head, Neck, and Anterior Limb 
1. Prepectoral Glands ‘ 
2. Pharyngeal Glands . 
8. Submaxillary, or Subglossal ‘Cande 
4. Prescapular Glands : 
5. Brachial Glands 
Article 11.—Great Lymphatic Vein 
Differential Characters in the Lymphatics of Ni omseliped Animes 
Cuaprer III.—The Circulatory a a in Birds 
Article 1.—The Heart 4 : Pe 
Article 1.—The Arteries - . - - ‘ ‘ " 


Article 11.—The Veins i ‘i : ‘ : 
Article 1v.—The Lymphat'es ; e “ F 
BOOK VI. 


APPARATUS OF INNERVATION. 


First SEcTION.—The Nervous System in General 
General Conformation of the Nervous System 
Structure of the Nervous System 
Properties and Functions of the Nervous Systems 
Srconp Srcrion.—The Central Axis of the Nervous System 
CaaptTer I.—Protective and Enveloping Parts of the Cerebro- acta Axis 
The Bony Case which lodges the Central eee Axis 
1. The Spinal Canal. ‘ , 
2. The Cranial Cavity ° ae ‘ : . : 


PAGE 
625 
626 
627 
627 
627 
632 
634 
634 


637 


638 
638 
638 
638 
640 
640 
640 
640 
640 
641 
641 
641 
641 
642 


642 
642 
643 
643 
643 
644 
644 
644 
644 
645 
647 
647 
648 
649 
649 


650 
651 
652 
655 
659 
659 
659 
659 
660 


TABLE OF CONTENTS. 


The Envelopes of the Cerebro-spinal Axis 
1. The Dura Mater 
2, The Arachnoid 
3. The Pia Mater . 


Differential Characters in the Protecting ant Brvdloptue Parts at the 


Cerebro-spinal Axis in other than Soliped Animals 


Comparison of the Protective and Enveloping Parts cf the Contiro- spiel 


Axis of Man with those of Animals 
Cuaprer IJ.—The Spinal Cord . 
External Conformation of the Spinal Cord ‘ 
Internal Conformation and Structure of the Spinal Cord . 


Differential Characters in the Spinal Cord of the Domesticated pauls 


other than Solipeds 
Comparison of the Spinal Cord of Man with that of Animals 
Cuarter III.—The Encephalon : z z 
Article 1—The Encephalon as a Whole 
Article 1.—The Isthmus . 7 
External Conformation of the Isthmus : 
1. The Medulla Oblongata a 
2. The Pons Varolii . 
. The Crura Cerebri 
. The Crura Cerebelli 
The Valve of Vieussens . 
. The Corpora Quadrigemina, or Bigemina 
. The Optic Thalami 
. The Pineal Gland . 
. The Pituitary Gland 
Internal Conformation of the Isthmus 
1. The Middle Ventricle, or Ventricle of the optic Thalami 
2. The Aqueduct of Sylvius 
3. The Posterior, or Cerebellar ‘Veutuidle 
Structure of the Isthmus . 
Differential Characters in the fates of orher fia Solyped aml . 
Comparison of the isthmus of Man with that of Animals 
Article 11.—The Cerebellum : . 
1. External Conformation of the Cersballuns 
2, Internal Conformation of the Cerebellum 
Differential Characters of the Cerebellum in other than Galiued, seth 
Comparison of the Cerebellum of Man with that of Animals 
Article 1v.—The Cerebrum : 
External Conformation of the Cerebrum 
1. The Longitudinal Fissure 
2. The Cerebral Hemispheres 
Internal Conformation of the Brain 
1. The Corpus Callosum 
. The Lateral, or Cerebral Ventricles 
. The Septum Lucidum . 
. The Cerebral Trigonum (or Forni) 
. The Hippocampi 
. The Corpora Striata 
. The Cerebral Choroid Plexus, and Yelum Interpositum : 
Structure of the Cerebrum 
Differential Characters in the Braitt of thier than Soliped Animals 
Comparison of the Brain of Man with that of Animals : 


OHDIHMAUPW 


NYOSHONP WD 


EXxi 
PAGE 


660 


663 


666 


666 


672 
672 


672 
675 


679 


693 
694 


695 
696 


698 


xxxii TABLE OF CONTENTS. 


TuirD Section.—The Nerves 

Cuaprer I.—The Cranial, or Sneephallis Nerves 
. First Pair, or Olfactory Nerves 
2. Second Pair, or Optic Nerves . ‘ 
3. Third Pair, or Common Motor Ocular Nerves 
4. Fourth Pair, or Pathetici Nerves 
5. Fifth Pair or Trigeminal Nerves . 
6, Sixth Pair, or External Motor Ocular Nerves 
7%, 
8. 


— 


. Seventh Pair, or Facial Nerves 
Eighth Pair, or Auditory, or Acoustic Werves A 
9. Ninth Pair, or Glosso-Pharyngeal Nerves . 
10. Tenth Pair, Vagus, or Pneumogastric Nerves 
11. Eleventh Pair, Spinal, or Accessory Nerves of the Preumogastries 
12. Twelfth Pair, or Great Hypoglossal Nerves 
Differential Characters in the Cranial Nerves of other than Boliped Animals 
Comparison of the Cranial Nerves of Man with those of Animals 
Cuapter II.—Spinal Nerves : 
Article 1—Cervical Nerves (Eight Pairs) 
Article 1.—Dorsal Nerves (Seventeen Pairs) 
Article m1.—Lumbar Nerves (Six Puirs) 
Article 1v.—Sacral Nerves (Five Pairs) 
Article v.—Coccygeal Nerves (Six to Seven Bites) 
Article v1.—Composite Nerves formed by the Inferior Ramuscules of the Spinal 
Branches 
Diaphragmatic Nerves ‘ . : 3 
Brachial Plexus A : . ‘ . ‘ 
. Diaphragmatic Br: tisha 
. Branch to the Angularis and Bhombaidens 
. Branch to the Serratus Magnus, or Superior Thoracic 
. Branches to the Pectoral Muscles, or Inferior Thoracic . 
. Subcutaneous Thoracic Branch 
. Branch to the Great Dorsal 
. Axillary, or Circumflex Nerve 
. Nerve of Adductor of tiie Arm, or Teres Major 2 
. Subseapular Branches 
. Superscapular Nerve 
11. Anterior Brachial Nerve 
12. Radial Nerve 
13. Ulnar, or Cubito- cutscene Nerve 
14. Median, or Cubito-plantar Nerve 
Differential Characters in the Brachial Plexus of wthar ‘tiie Soliped 
Animals : 
Comparison of the Bragiital Plexus et Man wath that of Actiamais 
Sacro-lumbar Plexus 
1. Iliaco-muscular Nerves . i: 
2. Crural, or Anterior Femoral Nerve . 
3, Obturator Nerve 
4. Small Sciatic, or Anterior and Postenior Gluteal ‘Neves, 
5. Great aetatin: or Great Femoro-popliteal Nerve . 
Collateral Branches 
Terminal Branclies 
Differential Characters in the Sacto-lumbar Plexus af other than Soliiped 
Animals 
Comparison of the Sacro-lumbar Plexus of Man with that of Animals 


a 
SODMNMS MWh H 


752 
753 


793 


760 


763 


T717 


777 
778 


TABLE OF CONTENTS, xxxili 


Cuarter III.—The Great Sympathetic . : i : 

1. Cephalic Portion of the Sympathetic Gain A . . . 782 
2. Cervical Portion of the Sympathetic Chain ‘ ‘ ‘ - 783 
3. Dorsal Portion of the Sympathetic Chain. : ‘ 786 
4, Lumbar Portion of the Sympathetic Chain - : . 788 
5. Sacral Portion of the Sympathetic Chain. 7388 

Differential Characters in the Great Sympathetic of other than Solipea 
Animals ‘ . 789 
Comparison of the Gr eat Sympathetic of Man with that of Ania 789 
Cuapter IV.—The Nervous System of Birds. ‘ : - . 790 

BOOK VII. 
APPARATUS OF SENSE. 

Cuarter I.—Apparatus of Touch . F ‘ < 792 
Article 1—Of the Skin Proper Fi < + , 782 
Article 1.—The eo y aed a ‘ < 7 797 

The Hair % P i . 797 

Horny ‘Prodtaiions 7 , ‘ . 3 799 

1, The Hoof of Solipeds 2 P . 3 - 800 

a. The Parts contained in the Hoot ‘ ‘ ° ‘ 800 

b. Description of the Hoof . 5 a ‘ . $805 

2; The Claws of Ruminants and Bachedexus ' - r 812 

3. The Claws of Carnivora z 3 : ” . 812 

4, The Frontal Horns ‘ 3 B . ‘i 813 

5. The Chesnuts : - : ‘ . . 813 

(6. The Ergots 5 . é s : 813) 

Cuarrer II.—Apparatus of Taste : $13 
Differential Characters in the bic nai of Taste of other then Soliped 

Animals . »  , 815 

Comparison of the Apparatus of Taste in Man sith that of bi weds . 8lb 

Cuarrer III.—Apparatus of Smell . a : 3 : 815 

Cuarrer IV.-—Apparatus of Vision P : 816 
Article 1—Essential Organ of Vision, or Globe of the Eye ; 817 

Membranes of the Eye . : 3 ‘ : 817 

1. The Sclerotica . i : : . : 817 

2, The Transparent Cornea . : : 819 

3. The Choroid Membrane ; : - : 820 

4. Thelris. 7 : : : 3 - . 822 

5. The Retina « ‘ , é : 824 

The Humours of the Eye ‘ ‘i - 826 

1. Crystalline Lens 2 , 7 . 826 

2. Vitreous Humour . : ® 5 . 827 

3. Aqueous Humour : . 827 

Article 11.—Accessory Organs of the Apparatus of Vision : ; 828 

Orbital Cavity . % 828 

Motor Muscles of the ‘Gloke af the Eye . 4 : . 828 

Protective Organs of = Eye : : F 830 

1. Eyelids 7 ‘ : ; . 830 

2. Membrana Nictitans : : : ; ‘ 833 

Lachrymal Apparatus. 834 
Differential Characters in the Visttel Apparotis of other then Soliped 

Animals . : 835 

Comparison of the Viena Apparatus of Man mah that of Sesiuiale : . 836 


3 


xxxiv TABLE OF CONTENTS. 


Cnarter V.—Apparatus of Hearing ; : ° 
Article 1—Internal Ear, or Labyrinth 
Bony Labyrinth : 7 
1. The Vestibule B 7 é , 
2. The Semicircular Canals F ‘ é . 


3. The Cochlea . 
The Membranous Labyrinth . 
1. The Membranous Vestibule 
2s The Membranous Semicircular Canals . 
. The Membranous Cochlea 
Liquids of the Labyrinth 
Distribution and Termination of the Saito Nerve i in the Membranous 
Labyrinth . F . . . 
Article 1.—Middle Ear, or Case of the Tympanum 
. Membrane of the Tympanum F 
. The Promontory, Fenestra Ovalis, Fenestra Rotinila, 
. The Mastoid Cells ‘ 
. Chain of Bones of the Middle Ear 
. Mucous Membrane of the Tympanic Case 
, Eustachian Tube 
. Guttural Pouches 
Article 11.—The External Ear 
External Auditory Canal 
The Concha, or Pavilion 
1. Cartilaginous Basis of the Couche 
2. Muscles of the External Ear : 
8. Adipose Cushion of the External Ear 
4. Integuments of the External Ear 7 
Differential Characters in the Auditory Apparatus of other than Boliped 
Animals 
‘Comparison of the Auditions Appartus of Man with that of Ayia 


TEP WON 


BOOK VIII. 


GENERATIVE APPARATUS, 


‘Cuaprer I.—Genital Organs of the Male : P : ‘ 
The Testicles, or Secretory Organs of the Semen . 
1. Description of the Vaginal Sheath 
2. Description of the Testicles . : 
Excretory Apparatus for the Semen . 


1. The Epididymis and Deferent Duct é 
2. The Vesiculee Seminales and Ejaculatory Ducts 
8. The Urethra 
4. The Glands Raneued to the Utethinal Canal 
5. The Corpus Cavernosum 
6. The Penis 
Differential Characters in the Male Genital Oronna of other thaw | Soliped 
Mammals 


Comparison of the Genital Omens of Man with those of Animals 
Cuarter II.—Genital Organs of the Female 

1. The Ovaries . 4 

2. The Uterine Cornua, “Fallopian Tubes, or Oviduets 

3. The Uterus . . A : 


. 


PAGE 
$37 
837 
837 
837 
837 
837 
838 
838 
839 
839 
840 


840 
840 
841 
842 
842 
842 
844 
844 
844 
846 
846 
846 
846 
847 
850 
850 


850 
850 


851 
851 
852 
853 
858 
858 
860 
861 
864 
864 
865 


867 
871 
872 
872 
876 
877 


TABLE OF CONTENTS. 


4, The Vagina 
5. The Vulva 
6. The Mamme 


Differential Characters in the Fonale Genital Organg of other than Soliped 


Mammals . 


Comparison of the Genital Organs of “Woman with those of Domesticated 


Female Animals 
Cuaprter III.—Generative Apparatus oe Birds 
1. Male Genital Organs 
2. Female Genital Organs 


. 


BOOK IX. 


EMBRYOLOGY. 


Cuaprer I.—The Ovum and its Modifications after Impregnation 
Article 1—The Ovum 


Article 11.—Modifications in the Oven antl the Sepeetanes of the 3 Embryo s 


Article 11.—Development of the Blastodermic Lamine 

External Lamina 
Middle Lamina 
Internal Lamina 

Cuapter IJ.—The Feetal Envelopes of Salted 
1. The Chorion 
2. The Amnion 
3. The Allantois 
4, The Umbilical Vesicle 
5. The Placenta. 
6. The Umbilical Cord . 


Differential Characters in the Annexes of the Feetus of other Dotaesticated 


Animals than Solipeds 


Comparison of the Annexes of the Human Foetus with those of the Footus a 


Animals 
Cuapter ILE —Development of the Footus 
Article 1.—Formation of the Embryo 
Development of the Chorda Dorsalis and Vecisweil Taming 
Development of the Lateral and Cephalic Lamine : . 
Article 11.—Development of the Various Organs of the Animal Economy 
Development of the Nervous System 
Development of the Organs of Sense 
Development of the Locomotory Apparatus 


Development of the Circulatory Apparatus . . 
Development of the Respiratory Apparatus d . 
Development of the Digestive Apparatus : . 
Development of the Genito-urinary Apparatus . P : . 
Cuaprer IV.—The Ovum of Birds ‘ : . ° r 


Index . i é i F 3 é S 5 


XXKV 
PAGE 
880 
882 
884 


886 


888 
889 
889 
889 


890 
890 
890 
892 
893 
893 
894 
895 
895 
896 
896 
899 
899 
900 


901 


904 
905 
905 
905 
905 
907 
907 
908 
911 
914 
918 
919 
922 
925 
927 


my 
fe 
OMAR HOND EE 


TABLE OF ILLUSTRATIONS. 


. Skeleton of the Dog 

. Skeleton of the Pig 

. Skeleton of the Horse 

. Skeleton of the Cow 

. Skeleton of the Sheep . 

. Vertical section of bone 

. Minute structure of bone 

. Lacunix, or osteoplasts of osseous agen 

. Cartilage at the seat of ossification 

. Elements of a vertebra 

. Atlas, inferior surface r 7 ‘ 

. A cervical vertebra é ‘ ‘ 
. The axis or dentata, lateral view 

. Type of a dorsal vertebra, the fourth 

. Upper surface of lumbar vertebree 

. Lumbar vertebra, front view 

. Lateral view of sacrum 

. Horse’s head, front view 

. Anterior bones of the head of a ftobus at hiv 

. Posterior bones of the head of a foetus at birth 

. Posterior aspect of Horse’s skull 

. Antero-posterior and vertical section of the Horse’ 8 head 
. Longitudinal and transverse section of the Horse’s head 
. Inferior maxilla 


. Hyoid bone ‘ 
. Lateral view of the Horse’s skull ‘ - 
. Ox’s head, anterior aspect ‘ : 


. Ram’s head, anterior aspect 

. Ox’s head, posterior aspect 

. Median and vertical section of the Ox’ 8 head : 
. Head of the Pig, anterior aspect 

. Head of the Pig, posterior aspect . 

. Head of Dog, anterior aspect . 

. Dog's head, posterior aspect 

. Front view of the human cranium ‘ 

. External or basilar surface of human skull : 


. The sternum . ‘ ‘ ; 

. Typical ribs of the Horse . 5 . ° 

. Thorax of Man, anterior face . . . : 
. Right scapula, outer surface é e . 


PAGE 
Chauveau . 7 
Chauveau . T 
Original. 8 
Original 9 
Chauveau . 9 


Carpenter . 18 
Carpenter . 14 
Carpenter . 14 
Carpenter . 17 
After Owen. 19 


Original . 22 
Original . 22 
Original 23 
Original . 24 
Chauveau . 26 
Original . 26 
Original. 27 
Original . 83 
Chauveau . 88 
Chauveau 41 
Original . 46 
Chauveau. 49 
Chauveau . 50 
Chauveau . BL 
Chauveau . 53 
Original 55 


Chauveau . 56 
Chauveau . 57 
Chauveau 58 
Chauveau . 59 
Chauveau . 60 
Chauveau . 61 
Chauveau . 62 
Chauveau 63 


Wilson i 64 
Wilson i 65 
Chauveau 66 
Chauveau . 68 
Wilson . WW 


Original . 72 


TABLE OF ILLUSTRATIONS. 


. Antero-external view of right humerus 

. Posterior view of right humerus 

. External face of the radius and ulna 

. Right fore-foot of a Horse 

. Posterior view of the right carpus 

. Front view of right carpus 

. Posterior view of right metacarpus 

. Lateral view of the digital region: outside of right litn 
. Posterior view of front digital region . 

. Plantar surface of third phalanx 

. Navicular bone 

. Fore-arm and foot of the Ox, jrontt view 

. Fore-arm and foot of the Dog, anterior face 

. Human scapula, external aspect 

. Right human humerus, anterior surface 

. Human arm bones, front view 

. Palmar surface of left human hand 

. The Coxe, seen from below 

. Pelvis, front view 

. Pelvis, lateral view 

. Left femur, anterior view 

. Left femur, posterior view 

. Section of left femur, showing its structure 

. Posterior view of right tibia 

. Left hind foot, external aspect 

. Left hock, front view R . 

. Left hock, internal aspect . 

. Posterior aspect of left metatarsus E 

. Human pelvis, female 

. Right human femur, anterior aspect 

A Human tibia and fibula of right leg, anterior agpect 
. Dorsal surface of left human foot . 

. Skeleton of a Fowl 

. Cephalic vertebra of the Toe 

. Plans of the different classes of artioulations . 
. Section of branchial cartilage of Tadpole . 

. Fibro-cartilage 

. White or non-elastic fibrous tisaue 

. Yellow or elastic fibrous tissue 

. Intervertebral articulations 

. Atlo-axoid and occipito-atloid articulations ; 
. Temporo-maxillary articulation 

. Articulations of the ribs with the vertebra, upper pian’ 

. Articulations of the ribs with the vertebrae, inferior plane 
. Scapulo-humeral and humero-radial articulations, external face 
. Carpal articulations, front view 

. Lateral view of the carpal articulations 

. Section of inferior row of carpal bones, and metacarpal. and sus- 


pensory ligament 


. Posterior view of metacarpo-phalangeal and interphalangeal 


articulations 


. Sacro-iliac and coxo-femoral sereoniatinnd. 
. Femoro-tibial articulation 


. Ligaments attaching the three bones of the leg . 


Buisnihi and Bouchard 


XXXViL 

PAGE 

Original 73 
Original 74 
Original 76 
Original TT 
Original 80 
Original 80 
Original 81 
Original 83 
Original 83 
Original 84 
Original . 86 
Chauveau . 87 
Chauveau . §&8 
Wilson 89 
Wilson 90 
Wilson 90 
Wilson 91 
Chauveau . 92 
Original 93 
Original 94 
Original 99 
Original 99 
Original 100 
Original 101 
Original 103 
Original 104 
Original 104 
Original 105 
Wilson 108 
Wilson 109 
Wilson 109 
Wilson 109 
Chauveau . 113 
Lavocat 120 
122 

Carpenter . 124 
Wilson 124 
Carpenter 125 
Carpenter . 125 
Chauveau 133 
Chauveau 137 
Chauveau . 138 
Chauveau . 140 
Chauveau . 140 
Chauveau . 145 
Chauveau . 150 
Chauveau . 151 
Chauveau . 155 
Original 156 
Chauveau . 161 
Chauveau . 164 
Chauveau . 167 


xxxviti TABLE OF ILLUSTRATIONS. 


. Tarsal articulations, front view 

. Articulations of the tarsus, lateral view 

. Ultimate fibril of muscle é 

. Striated muscular tissue fibre 3 3 

. Termination of nerves in muscular fibre 

. Distribution of capillaries in muscle 

. Termination of nerves in an elementary musoular fibre 

. Striated fibre of muscle during contraction 

. Lateral view of the neck, superticial muscles 

. Superficial muscles of the neck and spinal region of ‘the back 


and loins 


. Lateral view of the neck, middle lager of muscles 

. Cervical ligament and deep muscles of the neck 

. Muscles of the spinal vee of the neck, back, and loins 

. Deep ditto ‘ 

. Muscles of the back and cervix of ‘Man 

. Muscles of the sublumbar, patellar, and internal eral regions: 
. Deep muscles of the sublumbar region 

. Superficial muscles of the face and head . 2 

. Hyoideal and pharyngeal regions : ¢ ‘ ; 
. Superficial muscles of the Ox’s head 

. Muscles of the human head : 

. Muscles of the axillary and cervical regions : . 
. Axillary and thoracic muscles : Z A F 
. Muscles of the inferior abdominal region . 

. Muscles of the anterior aspect of the body of Man 

. Diaphragm, posterior face ; : 

. External muscles of the anterior limb 

. Muscles of anterior aspect of Man’s upper arm 

. Internal aspect of left anterior limb 

. Deep muscles on external aspect of 1ight anterior fey 

. Muscles of the fore-arm of the Ox 

. Tendinous and ligamentous apparatus in the digital : region of 


the Ox . 


. Muscles of the ibis -arm antl paw of the Dog : 

. Superficial muscles of human fore-arm 

. Deep layer of superficial muscles of human fore-trm 

. Muscles of human hand ; 

. Superficial muscles of the croup and tigi 

. Muscles of the sublumbar, patellar, and internal craral regions 
. Coceygeal and deep muscles surrounding the coxo-femoral 


articulation 


. Superficial muscles of the croup and thigh i in the Cow 

. Muscles of the anterior femoral region in Man 

. Muscles of the posterior femoral and gluteal region in Man 
. External deep muscles of right posterior limb 

. Flexor muscle of metatarsus i 

. Muscles on inner aspect of left posterior limb 

. External muscles of the leg of the Ox . : 

. Muscles of the human leg, anterior tibial region 

. Superficial posterior muscles of the human leg 

. First layer of plantar muscles of human foot 

. Third, and part of second layer of plantar muscles of Trema 


foc 


PAGE 
Chauveau . 169 


_Chauveau . 171 


Bowman . 178 


Bowman . 178 
Kiihne 179 
Berres . 180 
Beale . 180 


Bowman . 181 
Original . 188 


Chauveau . 190 


Original . 192 


Chauveau . 194 
Chauveau 204 
Chauveau . 207 
Wilson . 210 
Chauveau . 213 
Chauveaw . 214 
Original . 218 
Original . 226 
Chauveau . 228 


. Wilson . 231 
‘Chauveau . 232 


Original 234 
Chauveau . 248 
Wilson . 245 
Chauveau . 247 
Chauveau . 250 


. Wilson » 255 


Original . 257 
Original . 260 
Chauveau . 270 


Chauveau . 271 
Chauveau . 273 


Wilson . 275 
Wilson . 275 
Wilson . 279 


Original . 282 
Chauveav, . 290 


Chauveau 293 
Chauveau . 294 
Wilson . 296 
Wilson . 296 
Original . 299 
Chauveau . 800 
Original . 303 
Chauveau 307 
Wilson . 810 


, Wilson . 3810 


Wilson 312 


Wilson . 812 


Flas, 
143. 
144. 
145. 
146. 
147. 


, 148. 


149. 
150. 
151. 

152. 
153. 
154. 
155. 
156. 
157. 
158. 
159. 
160. 
161. 


162. 
163. 
164. 
165. 
166. 
167. 
168. 
169. 
170. 
Ii 
172. 
173. 


174 


175. 
176. 
177. 
178. 
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180. 
181. 


182. 
183. 


184. 


185. 
186. 
187. 
188. 
189. 
190. 
191. 
192. 
193. 
194. 
195. 


TABLE OF ILLUSTRATIONS. 


Squamous epithelium trom the mouth 
Columnar epithelium . 
Columnar ciliated epithelium z 
Conical villi on mucous membrane of small intestine 
Fusiform cells of smooth muscular fibre. ; 
Hard and soft palate 
Muscles of the tongue, soft alae, and pherpns 
Lobe of racemose gland from the floor of the mouth 
Follicular gland 
Median longitudinal section of the head and upper part of neck 
Section through the fang of a molar tooth 
Transverse section of enamel 5 : 
Magnified section of a canine tooth . : ‘ 
Theoretical section of dental sac of permanent incisor 
Section of dentine and pulp of an incisor tooth 
Dentition of inferior jaw of Horse . 
Incisor teeth of Horse, details of structure 
Profile of upper teeth of the Horse 7 
Transverse section of Horse’s upper molar : r 
The teeth of the Ox 
Ox’'s incisor tooth 
Incisor teeth of a Sheep two years old 
Teeth of the Pig ; 
General and lateral view of the Dog’s teeth . 
Anterior view of the incisors and canine teeth of Dog . 
Section of the human face . 
Lobule of parotid gland 
Capillary network of follicles of parotid: piand 
Termination of the nerves in the salivary glands 
Inferior aspect of head and neck 
Maxillary and sublingual glands 
Pharyngeal and laryngeal region . 
Median longitudinal section of head and appear part of jnedte 
Muscles of the pharyngeal and hyoideal regions 
Human pharynx 3 ‘ 
Transverse vertical section of head and neck 
Pectoral cavity and mediastinum 
Theoretical transverse section of abdominal cavity ‘ 
Theoretical, longitudinal, and median section of abdominal 
cavity 
The abdominal cavity, with the stomach and other eiganig: 
Stomach of the Horse . 
Interior of the Horse’s stomiéls 
Muscular fibres of stomach, external and middle layers 
Deep and middle muscular fibres of stomach : 
Peptic gastric gland . ‘ . : . : 
Portion of a peptic caecum : ‘ 
Mucous gastric gland . 
Capillaries of mucous membrave of stomach 


Stomach of the Dog. . 5 : 

Stomach of the Ox ‘ ‘ . 
Interior of the stomach of Husiinanta z 
Section of the wall of the omasum of Sheep . 7 
Section of a leaf of the omasum 6 : $ 


Xxxix 

PAGE 

Wilson 327 
Kolliker 827 
Carpenter . 327 
Wilson 328 
Bowman 328 
Chauveau . 333 
Chauveau . 3388 
Kolliker 339 
Kélliker 339 
Original . 341 
Carpenter . 345 
Carpenter . 346 
Wilson 347 
Chauvreau 348 
Carpenter . 349 
Chauveau . 350 
Chauveau . 351 
Chauveau . 353 
Chauveau . 354 
Chauveau . 357 
Chauveau . 358 
Chauveau . 359 
Chauveau . 360 
Chauveau . 361 
Chauveau . 361 
Quain 362 
Wagner 365 
Berres 365 
Pfliger 366 
Original 367 
Chauveau . 368 
Original 372 
Original 373 
Original 375 
Wilson 377 
Original . 378 
Chauveau . 379 
Chauveau . 382 
Chauveau . 383 
Original 386 
Chauveau . 387 
Chauveau . 388 
Chauveau . 390 
Chauveau . 390 
Kélliker 391 
Kélliker 391 
Kélliker 392 
Carpenter . 392 
Chauveau . 393 
Chauveau 394 
Chauveau . 395 
Chauveaw . 398 


After Chauveau 399 


TABLE OF ILLUSTRATIONS. 


. Longitudinal section of a large papilla from the omasum 
. Villi of human and Sheep’s intestine . 

. Portion of Brunner’s gland 

. Section of mucous membrane of small intestine 

. Section of mucous membrane of large intestine 

. Injected villi of intestine : . . 

z. Blood-vessels in Peyerian glandule 

. Diagram of origin of lacteals in villi 3 ; 
. General view of the intestines of the Horse, right side 
. General view of the Horse’s intestines, inferior aspect . 
. The colon of the Horse. 

. Plan of the colon 


. General view of the intestines of the Ox i 


. Intestines of the Dog . 
. Human intestines . 
. Abdominal cavity, with the liver avid oer organs 


. Portion of a hepatic column, with secreting cells 
. Biliary capillaries and ducts 
. Bloud-vessels in lobules of liver 


. Section of lobules of liver, with igualdinane veins 


. Excretory apparatus of the Horse’s liver . 


. Malpighian corpuscles attached to splenic artery 
. Splenic corpuscle from the spleen of Ox 


. Liver of the Dog, with its excretory apparatus 
. Under surface of the human liver . 


. General view of the digestive apparatus of a fowl 

. Cartilages of the nose 

. Transverse section of the head of Hoike 

. Longitudinal section of the head, and upper part of neck . 


. Cells of the olfactory mucous membrane . 


. Fibres of olfactory nerve 
. Superior face of larynx - : - 


. Inferior face of larynx. 3 ; 
. Postero-lateral view of larynx . 


. The respiratory organs, inferior aspect 

. Ciliated epithelium fot the trachea . 

. Bronchial tube, with its bronchules ; 
. Mucous membrane of a bronchial tube 


. The pectoral cavity and mediastinum 
. Theoretical section of thoracic cavity, behind the heart 


. Theoretical section of thoracic cavity, at root of lungs 
- Theoretical section of thoracic cavity, in front of right ventricle Chauveau . 


. Plan of a pulmonary lobule 
. Air-cells of lung . 


. Capillaries and air-cells ee lung 

. Lung of the Sheep, inferior view . 
: iuecaey dungs and heart ‘ 

. Gland vesicles of thyroid 

. Portion of thymus of calf 


. Course and termination of ducts in tiem anil of calf 


. General view of the air-sacs in the duck : 
. General view of the yenito-urinary apparutus in the male . 


- Horizontal longitudi. 1 section of the Horse’s kidney . 
. Section of the cortical . ~bstance of the kidney 


: Chauveau . 
Teichmann. 
Thomson 
Teichmann. 
Teichmann. 
Kolliker 
Kolliker 
Funke 


After Chauveau 


Chauveau . 
Original 
Chauveau . 
Chauveau . 
Chauveau . 
Wilson 
Original 
Leidy 


Irminger and Frey 


Kiernan 
Kiernan 
Chauveau . 
Kolliker 
Kélliker 
Chauveau . 
Wilson. 
Chauveau . 
Chauveau 
Chauveau . 
Original 
Clarke and Schultze 
Ecker ‘ 
After Chauveau 
After Chauveau 
- Original 
Original 
Kolliker 
Heale 
Heale 
Chauveau . 
Chauveau . 
Chauveau . 


. 


Waters 
Kélliker 
Carpenter 
Chauveau , 
Wilson 
Kélliker 
Kolliker 
Wilson 
Chauveau . 
Chauveau . 
Chauveau 
Ecker 


PAGE 
399 
403 
403 
404 
405 
405 . 
406 
406 
408 
409 
410 
411 
415 
416 
417 
421 
423 
423 
424 
424 
425 
430 
430 
433 
434 
436 
440 
442 
443 
445 
446 
452 
452 
454 
458 
459 


465 
468 


488 


287. 


288. 
. Arteries of the face and head of Man . 
Roots of the superior jugular vein, with its ealindsial affluents 


290. 
291, 
292. 
293. 


296. 


297. 


299. 
300. 


302. 


TABLE OF ILLUSTRATIONS. 


. Course of the uriniferous tubuli 

- Diagram of the circulation in the kidney . 

. Transverse horizontal section of kidney 

. The kidneys and bladder in the foetus of Solipeds . 
. Right kidney of Ox, upper and external face . 

. Left kidney of Ox, internal and inferior face 
. The calices in left kidney of Ox 

. Theoretical plan of the circulatory system . 

. The heart and principal vessels, left face 

. The heart and principal vessels, right face 

. Right side of the heart laid open 5 : 5 
. Section of the heart at the level of the valves e 

. Left cavities of the heart laid open. ‘ 

. Anastomosing muscular fibres of heart 
. Epithelium of the endocardium : 
. Human lungs and heart, front view 

. Web of Frog’s foot, showing blood-vessels and hele eeinnnaed 
7. Epithelial cells of blood-vessels 
. Fenestrated membrane from the carotid artery of the Horse 
9. Coarse elastic tissue from pulmonary artery of the Horse 
. Transition of a minute artery of the brain into capillary vessels 
. Distribution of the great mesenteric artery 
. Distribution of the small mesenteric artery 
. Arteries of the stomach in Ruminants . 

. Upper and general view of the genito- pei: apparatus and 


. 


. 


arteries in the male 


. Lateral view of the genito-urinary organs in the inal A 
. Abdominal aorta, with its branches, in Man 

. The external and internal iliac arteries in the Mare 
. Principal arteries and veins of the posterior foot 

. Anterior aspect of iuman leg and foot 

. Posterior aspect of human leg 

. Arteries of sole of human foot . 

. Distribution of the anterior aorta . 

. Arteries of the fore-foot, seen from behind 

. Arteries of the human fore-arm and hand . 

5. Arteries of the brain 

. Arteries of the head 


Réseau admirable of the Sheep, seen in piefile; 
Réseau admirable of the Ox, posterior face 


Section of the cranial cavity and spinal canal 
Veins of the foot . . 
General view of the veins in the Horse 


. The vena porte and its roots . ‘ ‘ 
. Section of a lymphatic rete mirabile 


Section of lymphatic gland. : . 
Section of simple lymphatic gland. 


. Section of the medullary substance of lympnatic winind of Ox 


Ordinary disposition of the thoracic duct . 
Double variety of the thoracic duct 


. Triple variety of the thoracic duct : os 
Lymphatic system of the Horse - A Be! 


Hertz 
Bowman 
Original 
Chauveau . 
Chauveaw . 
Chauveau . 
Chauveau . 
Colin 
Chauveaw . 
Chauveau . 
Wilson 
Sibson 
Wilson ~ 
Kaélliker 
Kolliker 
Wilson 
Wagner 
Kélliker 
Kolliker 
Kolliker 
Kélliker 


Chauveau . 
Chauveau . 
Chauveau . 


Chauveau . 


Chauveau . 
Wilson 
Chauveau 


Chauveau . 


Wilson 
Wilson 
Wilson 
Chauveau . 


Chauveau . 


Wilson 
Chauveau 


Chauveau . 
Chauveau . 
Chauveau . 


Heath 


Chauveau . 
Chauveau . 
After Bouley 
Chauveau . 
Chauveau . 
Teichmann. 


Kolliker 
Teichmann. 
Kolliker 
Colin 

Colin 

Colin 

Colin 


xli 
PAGE 
488 
489 
489 
492 
496 
496 
496 
498 
501 
502 
504 
505 
507 
509 
511 
514 
518 
518 
519 
519 
519 
530 
533 
536 


539 
542 
544 
546 
552 
558 
558 
559 
562 
568 
574 
580 
583 
593 
594 
595 
604 
607 
614 
618 
620 
631 
632 
632 
633 
636 
636 
636 
639 


. Nerves of the axilla of Man 


TABLE OF ILLUSTRATIONS. 


. Great lymphatic vein and entrance of the thoracic duct 


. Great lymphatic duct, another variety 

. Thoracic duct in the Ox . E 
. A variety of the thoracic duct in the Ox 

. Another variety of the thoracic duct 


. A fourth variety of the thoracic duct . 
. Thoracic duct of small Ruminants. 

. Diagram of structure of nerve-fibre 

. Multipolar, or stellate nerve-cell 


. Ganglion from heart of Frog . . 
. Bipolar ganglionic cells and nerve-fibres . 
. Stellate nerve-cell 3 ; . 


. Structure of ganglionic cells 
. General view of the spinal cord 


. Segment of thespinal cord at the cervical bulb 
. Section cf the spinal cord of the Horse at the lumbar region . Chauveau . 
. Transverse section of spinal cord of Man at the middle of the 


lumbar region 


Cat : 
. General view of the brain, ‘Appet surface 
. General view of the brain, lower surface 


. Superior view of the encephalie isthmus 

. Lateral view of the isthmus i 

. Transverse section of the encephalon . r . 
. Dissection of the medulla oblongata 

. Median and vertical section of the encephalon . 

. Section of the cortical substance of the cerebellum . 

. Antero-posterior and vertical section of the encephalon 


. Corpus callosum 

. Anterior portion of the litera vonfielas 

. Corticle substance of the cerebral ais 
. Base of the human brain 


. Muscular fibres, with termination of sitet nerve . 
. Nerves of the eye F 
. General view of the superior and ‘nferiol maxillary nerves Chauveau . 
. Section through the summit of the medulla oblongata . 

. Origin of the nerves arising from the medulla oblongata 
. Pneumogastric nerve, with its branches in the neck 

. Origin and distribution of the eighth pair of nerves in Man Wilson 
. Distribution of the nerves in the larynx of the Horse . 
. Deep nerves of the head 7 : 

. Nerves of the guttural recion in the Ox ‘ 


Nerves of the face and scalp of Man 


. External nerves of anterior limb 


. Nerves of the digit of Horse 


. Nerves of the digital region of imitate: 
. Nerves of the palmar face of Dog’s foot . 
. Nerves of the palmar face of Cat’s foot . 


Colin ‘ 
Colin E 
Colin ; 
Colin 
Colin 
Colin 
Colin : 
Carpenter . 
Ecker 
. Ecker 
Ecker 
Beale P 
. Beate and Arnold 
- Colin Fi 
Colin 


I. L. Clarke 


. Longitudinal section through cebuieal bulb of ental cord of the 


I, L. Clarke 
Chauveau . 
Original 
Chauveau . 
Chauveau . 
Chauveau . 
Solly and Carpenter 
. Chauveau . 
Kolliker 
Chauveau . 
Chauveau . 
Chauveau . 
Killiker 


Hivscfe and Leveillé 


Cohnheimn . 
Chauveau . 


Carpenter . 
Toussaint 
Toussaint . 


Toussaint . 
Chauveau . 
Toussaint 


. Hirschfeld and Levetlte 
. Distribution of eighth pair of nerves on left side Hirschfeld and Leveillé 
. Ganglion of a spinal nerve from the spinal region . : 

. Nerves of the brachial plexus . 


Kélliker 

Chauveau . 
Chauveau . 
Bouley 
Chauveau . 
Chauveau . 
Chauveau . 


Hirschfeld and Leveille 


. Nerves of the front of fore-arm and hand of Man - Hirschfeld and Leveille 


646 
647 
652 
653 
654 
654 
654 
654 
667 
667 
669 


670 


671 
673 
676 
678 
680 
682 
684 
687 
689 
690 
693 
696 
697 
699 
702 
708 
714 
721 
730 
731 
732 
734 
738 
740 
745 
746 
748 
757 
759 
762 
764 
766 
767 
768 
769 


FIGS. 


356. 


380. 
381. 
382. 
383. 
384. 


385. 
386. 
387. 
388. 
389. 
390. 
391. 
392. 
393. 


394. 
395. 
396. 
397. 
398, 
399. 
400. 
401. 
402. 
403. 
404. 
405. 
406. 


TABLE OF ILLUSTRATIONS, 


. Lumbo-sacral plexus and internal nerves of posterior limb 


Posterior portion of the lumbo-sacral plexus 


Horizontal section of the junction of the wall with the sole of 
hoof 

Horizontal sention of wall aaa horny ‘wail waseuine lamin 

Fibres of ultimate ramifications of olfactory nerves 


xiii 
PAGE 
Chauveau . 771 
Chauveau . 773 


. External nerves of posterior limb Chauveau . 776 
. Lumbar plexus of Man . . Hiadifae and Leveillé 779 
. Nerves at the posterior aspect of aria fess Hirschfeld and Leveillé 780 


. Nerves at the front aspect of human leg. . Hirschfeld and Leveille 780 
. Sympathetic ganglion froma Puppy . F 

. Sympathetic system of the Horse . 

. Section of Horse’s skin 3 

. Capillary loops in cutaneous papilla 

. Tactile papilla from the skin . 

. Interungulate gland of Sheep 2 . . 

. Branches of cutaneous nerves in skin . ‘ 7 . 
. Sudoriparous gland 

. Oblique section of epidermis . 

. Longitudinal median section of Horse's s foot 

. Horizontal section of Horse’s foot 

. Lower surface of the Horse’s foot . 

. Lateral view of the Horse’s foot 

. Hoof removed from the foot 

. Hoof with outer portion of wall removed 

. Plantar surface of hoof 

. Horn-cells from the sole of hoof 

. Constituent elements of the wall 

379. 


Kolliker . 782 
Chauveau . 784 
Chauveau 793 


Bervres » G08 
Licker . 794 
Owen . 794 
Ecker 795 
Wagner . 795 
Carpenter . 796 
Original . 800 


Original . 801 
Original 802 
Original . 83 
Leisering . 806 
Leisering . 806 
Leisering . 807 
Leisering . 809 
Leisering . 810 


Leisering . 811 
Leisering . 811 
Licker . 816 


Cells of olfactory mucous membrane : Claris and Shultze 816 


Theoretical section of the Horse’s eye . : 

Anterior segment of a transverse section of the globe of the aye 
(human) : 

Cells from pigmentum aan 5 

The eye (human) with the sclerotic coat seo: 

Muscular structure of the iris . 

Vertical section of retina . zs 

Diagram of the structure of the retina : 

Capillaries in the vascular layer of the retina 

Muscles of the eye-ball, viewed from above 

Section of lamina spiralis of the cochlea 

Section of the cochlea parallel to its axis 

Right tympanic cavity of Horse’s ear 

Bones of the middle ear of the Horse . 

Muscles of the ear 

Human testis, injected with menu 

Vertical section of the Horse’s testis 

Internal genito-urinary organs of the foetus of a Mare. 

Spermatozoa of various animals 

Diagram of the testicle 

Superior view of the genito-urinary aieaae 

Longitudinal section of the free extremity of the Horse’s penis 

Sections of the urethra of the Ox at different points 

Penis and muscles of the sheath of the Bull 

Section of human pelvis : 


Chauveau 818 


Wilson < 821 
Carpenter . 822 
Holden . 823 
Kolliker . 823 
Miller . 825 
Krause . 826 
Berres . 826 


Original . 829 
Carpenter’. 838 
Breschet . 838 
Chauveau . 841 


Lavocat . 843 
Original . 848 
Lauth 854 


Chauveau . 855 
Chauveau . 857 
Carpenter . 858 
Holden . 859 
Chauveau . 860 
Chauveau . 866 
Chauveau . 868 
Chauveau . 869 
Gray . 871 


TABLE OF ILLUSTRATIONS. 


~ Ovarium of the Rabbit 

. Constituent parts of mammalian ovum, "entire 

. Constituent parts of mammalian ovum, ruptured 
. Formation of the corpus luteum 


. Generative organs of the Mare, isolated F 

. Generative organs of the Mare, in situ 

. Termination of milk-duct in cluster of follicles 

. Ultimate follicles of mammary gland, with secreting cells . 
. Microscopic appearance of milk 

. Human uterus, with its appendages 5 

. First stages in segmentation of mammalian ovum 

. Later stages in segmentation 

. Section through embryo of the Chick, first cee of fenton 
. Plan of early uterine ovum 

. Diagram of ovum at formation of tne amnion . 

. Exterior of the chorial sac, Mare i 

. Fecundated egg, showing formation of amnion reel allantots 


. Fecundated egg, with amnion nearly completed. ‘ 
. Foetus of the Mare, with its envelopes. 5 
. Portion of ultimate ramifications of umbilical vessels ‘ 


. Portion of one of the feetal villi 

. Equine foetus, opened on left side to show manila yeuels 
. Blood-vessels in liver of an equine foetus at mid-term 

. Liver of a Lamb at birth . 

. Diagram of an early human ovum ‘ : 

. Diagram of a human ovum in second month . 

. Early stages in the development of a Fowl 

. Transverse section of embryo of Chick on third day 

. Plan of development of eye 

. Origin of encephalic centres in utien anbipe of sixth week 
. Plan of chorda dorsalis at period of formation of embryo 

. Plan of vertebra at an early period of development 

. Head of a foetal Lamb, showing Meckel’s eau eee 

. Plan of first system of vessels, embryo . . 

. Embryonic heart at an early period, anterior view 
. Ditto, seen from behind 

z Heart of an equine foetus . 

. Plan of the aorta and its arches at an euly pete 
. Plan of the circulation in the human embryo, side view 
. First appearance of the lungs . 

. Embryo of Dog at twenty-five days 

. Origin of liver from intestinal wall of embryo Chick 

. Urinary and genital apparatus in embryo Chick 

. Section of Fowl's egg . . . ‘3 . 


Pouchet 
Coste 

Coste 
Pouchet 
Chauveau . 
Chauveau . 


. Sir A. Cooper 


Lebert 
Funke 
Wilson 
Coste 

Coste 
Kélliker 
Wagner 
Wagner 
Chauveaw . 
Dalton 
Dalton 
Chauveau . 
Carpenter 
Ecker 
Chauveau . 
Colin 
Colin 
Wagner 
Wagner 
Hualey 
Kolliker 
Kélliker 
Wagner 
Kolliker 
Kolliker 
Hualey 
Kélliker 
Kolliker 
Kélliker  . 
Chauveau . 
Kélliker 
Coste 
Wagner 
Bischoff” 
Miiller 
Miiller 


Allen Thomson 


PAGE 
874 
875 
875 
875 
878 
881 
885 
885 
885 
888 
891 
891 
893 
894 
894 
895 
896 
896 
898 
899 
900 
901 
902 
902 
904 
904 
906 
908 
909 
910 
912 
912 
913 


914 ° 


915 
915 
916 
917 
918 
919 
919 
922 
922 
925 


THE COMPARATIVE ANATOMY 


OF THE 


DOMESTICATED ANIMALS. 


GENERAL CONSIDERATIONS. 


DEFINITION AND DIVISIONS OF ANATOMY. 


Anatomy is the science of organisation; it studies the structure of 
animated beings when these have been deprived of life. It comprises two 
grand divisions: physiological anatomy, which describes healthy organs, and 
pathological anatomy, whose object is the description of diseased organs. 

Physiological anatomy, in its turn, embraces :— 

1. General anatomy, which is occupied with the analogous matters or 
tissues of the animal body, with regard to their texture, and their physical, 
chemical, and physiological properties, irrespective of the organs in which 
these tissues exist. The particular study of the anatomical elements 
entering into the composition of the tissues is named histology. 

2. Descriptive anatomy, which studies the situation, form, and relation 
of organs, as well as the relative arrangement of the various tissues 
composing them, with the exception of the structure and properties of these 
tissues. 

If this study be devoted to a single species, it is designated special 
anatomy. Example: human anatomy, or anthropotomy ; the anatomy of the 
Horse, or hippotomy. 

When descriptive anatomy embraces the study of the organisation of the 
entire animal kingdom, and examines the differences which characterise the 
same organ or the same series of organs in each class, family, genus, or 
species, it is named comparative anatomy. Restricted to the domesticated 
animals, this study constitutes veterinary anatomy. 

Philosophical or transcendental anatomy differs from comparative anatomy, 
inasmuch as it indicates the analogies of organs or apparatus, in order to 
exhibit the simplicity of Nature’s plan in the general laws of organisation. 

Finally, if descriptive anatomy is limited to denoting the relations 
existing between the various organs of a region, particularly with a view to 
the performance of operations and the diagnosis of external diseases, it takes 
the names of topographical, regional, or surgical anatomy. 


2 GENERAL CONSIDERATIONS. 


ENUMERATION AND CLASSIFICATION OF THE SPECIES OF DOMESTICATED 
ANIMALS, 


The object of this book is the study of veterinary anatomy. The 
animals of which it treats belong to the mammiferous class and to that of 
birds. ; ; Me sack 

The domesticated mammals of our regions have their representatives in 
a large number of orders. Thus, we find among them :— 


1. Of the carnivora, the Dog and Cat ; 

2. A rodent, the Rabbit ; - 

3. A pachyderm, the Pig ; ; ; 

4. Of solipeds, the Horse and Ass; the produce of the male ass with 
the mare, i.e., the Mule, and that of the horse with the female ass, 
known by the name of Hinny ; 

5. Of ruminants, the Ox, Sheep, and Goat, 


With regard to poultry, they range themselves :-— 


1. In the gallinaceous order, the genera to which the common owl, 
guinea fowl, turkey, and pigeon belong ; 
2. In the order of palmipeds, the geese and ducks. 


Girard has proposed a special classification for the domesticated mammals, 
based upon the number of digits terminating each of their limbs, and has 
defined four categories: the first comprises the horse, ass, mule, and hinny, 
which take the name of monodactyles, because their digital region is composed 
of a single digit; in the second, under the denomination of didactyles or 
bisulcate animals, those with two digits, such as the ox, sheep, and goat; in 
the third, or regular tetradactyles, is found ranged the pig, each of whose 
limbs shows four digits; lastly, the dog and cat, which most frequently 
have four digits on the posterior members and five on the anterior ones, and. 
form the class of irregular tetradactyles, 

This nomenclature will not be followed here, as it is opposed to the general 
laws of organisation ; philosophical anatomy has, in fact, demonstrated that 
there are really no veritable monodactyles, didactyles, etc., all are materially. 
or virtually pentadactyles. It is therefore considered better to keep to the 
classification established by zoologists, because it prevents confusion in 
scientific language, which should always be the same for everyone engaged 
in the study of anatomy. 

The regimen. and habits of the domesticated animals bring about differ- . 
ences in their organisation which appear very great at first sight, though in 
reality they are not so profound as they seem. 

In order to study the descriptive anatomy of all these animals, we will 
not pass them in review, one after another, giving for each the description 
of every organ; but shall take a type, which will most frequently be 
the Horse, and briefly compare all the others with it, 
cases, we will describe, without leaving the Horse, all 
apparatus ; afterwards the same organs in the other species will be studied 
in the same order. In this comparison, the animals will be generally classed 
according to their domestic value: though exceptions will be made to the 
rule which has been instituted by our predecessors, whenever any advantage 
1 point of concision or perspicuity is likely to be obtained. . 


GENERAL CONSIDERATIONS, 3 


GENERAL IDEA OF THE ORGANISATION OF ANIMALS, 
Order followed in studying the Various Apparatus. 
a bodies of animals, formed of organised matter, contain fluids and 
solids. 

The fluids are very abundant in the animal economy; not only do they 
fill certain vessels constructed for them, but they also impregnate all the 
solid parts of the body. Their importance is very great, for without them 
the organic solids would perish; an element deprived of humidity is an 
element deprived of life. 

Fluids vary in their nature and composition. Apart from those that 
the solids imbibe, there is not one which is completely amorphous. In the 
midst of a liquid holding organised matter in solution there are always 
elements which will be referred to hereafter. Examples: the blood and lymph. 

In studying the organic solids, we will proceed from the simple to the 
complicated. 

Exemenrs.—Solid organised matter presents itself in the form of more or 
less voluminous particles, in every instance invisible to the naked eye, and 
named the anatomical elements. They may be reduced to three principal: 
the granule,-cell, and fibre. 

Granules.—These are the smallest known elements. They may be held 
in suspension in animal fluids, remain free among the other elements, or be 
enclosed in the interior of cells. Their nature is not always the same: 
they are proteic or fatty. They are called pigmentary when they exhibit 
a brown colour. 

Cells.—The cell is pre-eminently the anatomical element. 

It may be represented to the mind as a microscopic collection of a 
nitrogenous substance, viscid or slightly granular, and endowed with extreme 
vitality. Frequently in the midst of this protoplasm (for so it has been 
called), there is perceived a nucleus provided with a nucleolus, and at its 
periphery an enveloping membrane is discovered. It must not be forgotten 
that this membrane, and even the nucleus, is necessarily a constituent portion 
of the cell. 

The cell lives like an entire organism: it feeds, grows, multiplies, 
absorbs, secretes, moves, etc. It behaves like a complete animal, though it 
be a microscopic one. 

The form of the cell varies greatly, as does its volume and its nature. 
It has therefore received various names. 

There are round, polyhedral, fusiform, stellate, and other shaped cells. 
Some have a diameter of 1-12000th part of an inch, while others are 1-2000th 
part. Cells multiply in various ways: Ist, by the division of the nucleus 
and segmentation of the protoplasm in the interior of the enveloping 
membrane (endogenous multiplication); 2nd, by constriction, the division 
of the nucleus, protoplasm, and enveloping membrane ( fisstparous multipli- 
cation) ; 3rd, by a kind of bulging or swelling of the enveloping membrane, 
and strangulation and separation of the enlargement thus formed 
(gemmation). mee : = 

A large number of cells only temporarily remain in this condition. In 
consequence of modifications that cannot be referred to here, they are con- 
yerted into fibrille or other elements, in which it is difficult to recognise 
them. 

Others maintain the cellular form: then they are developed, live, and 
die in several ways. Sometimes they are worn by the contact of foreigr 


4 GENERAL CONSIDERATIONS. 


bodies, as on the surface of the skin; at other times they become dissolved, 

as in some glands; finally, at other periods they submit to fatty degeneration, 

which gradually brings about their complete destruction. : 

The permanent cells have been arranged according to the following 
denominations :— 

1. Hematies or red globules, which are found in a state of suspension 
in the blood; they are round or elliptical. 

. Leucocytes, or white globules, which float in the blood, lymph, and chyle. 

. Connective cells, comprising the connective cell properly so-called, 
the plasmatic cell, and the adipose cell. 

. Medullary cells, forming the principal elements of the marrow of 
bones (myeloplaxes and medullo-cells). 

. Contractile cells, which constitute the basis of muscular tissue. 

. Nerve cells, met with in the cerebro-spinal centres and the ganglia 
of the cerebro-spinal and sympathetic systems. 

. Epithelial cells, comprising the epithelial cells properly called, 
situated on the surface of the skin and mucous membranes, and 
the glandular cells. 

Fibres.—A fibre is an elongated anatomical element, of variable dimensions 
and composition. It may be very fine and represented by a single line, or 
thicker and marked by two lines more or less apart from one another. It 
is homogeneous throughout, or the contents are distinct from the envelope. 

The vitality of fibres is not to be compared with that of cells; after they 
are formed, they can only be nourished, and cannot multiply of themselves. 
In the animal economy four kinds of fibres are distinguished :—the connective 
fibre, elastic fibre, muscular fibre, and nervous (or nerve) fibre. 

Tissurs.—The elements that have now been rapidly described, in 
becoming united and grouped in different fashions, form the tissues. 

Some tissues are composed of one kind of element; these are the simple 
tissues. Example :—The epithelium. 

® The majority, however, are formed by the union of several different 
elements: these are the composite tissues. Example :—Nervous tissue. 

It is also remarked that there are tissues in which exists a fundamental 
intercellular substance, and others in which this is absent. The latter are 
few in number, for the vessels and nerves may, in certain tissues, be 
considered as intercellular substance. 

The anatomical, physico-chemical, and physiological characters of the 
tissues repeat, as might easily be inferred, the anatomical, physico-chemical, 
and physiological properties of the elements entering into their formation. 

Only four fundamental tissues are recognised, basing them on the 
morphological, chemical, and physiological characters of the elements. 

In the first place, the tissue of the conjunctival substance should be noticed ; 
this, in consequence of some differential characters, may be divided into :— 
gelatinous tissue, conjunctival (or connective) tissue, cartilaginous tissue, and bony 
tissue. 

Then comes the cellular tissue, formed entirely of persistent cells. It 
comprises the epithelial tissue and the glandular tissue. 

The cells of the epithelial tissue may affect different arrangements. If 
they are disposed in a single row, there results a simple epithelium ; if they 
are superposed it is a stratified epithelium. According to the form of the 
cells of the superficial layer, the epithelium is polyhedral, pavement, cylindrical, 
or spherical, In certain points, these superficial cells are furnished with 
Vibratile filaments; they are then designated vibratile (or ciliated) epithelium. 


“I DD or e co bo 


GENERAL CONSIDERATIONS, 5 


In the third place, is the muscular tissue, which may be divided into 
striated and non-striated (or striped, and non-striped or sthooth) fibres. 

Lastly comes the nervous tissue, which offers two aspects: the white and 
grey substance. The first is entirely formed by nerve fibres, and the second 
by fibres and nerve cells. ; 

Orcans.—The term organ is given to an agglomeration of tissues 
possessing a determinate form, and having a function to fulfil. Organs are 
therefore composed of tissues, as the tissues themselves are constituted by 
anatomical elements. 

All animal organs are enclosed between two membranes named limitary 
or tegumentary membranes, which are continuous with one another at the 
margin of the natural openings. These are the skin and the mucous 
membranes, in whose composition is included a layer of connective tissue 
covered by an epithelium. 

Organs are distinguished into those which are solid, and those which are 
hollow. 

Among the first, a certain number act as supports: such are the organs 
formed by the connective tissue, and particularly the cartilages and bones. 

Others are destined to produce movements: these are the two kinds of 
muscles. The action of the muscles is communicated directly to the organs 
that are to be moved, or it is transmitted through the medium of other 
organs, such as the tendons and aponeuroses. 

The central nervous organs, nerves properly so called, and the vascular 
glands, belong to this group of solid organs. 

With regard to the hollow organs, they are everywhere covered by the 
internal, tegumentary, or mucous membrane. Examples:—the lungs and 
stomach. There must also be included the vessels formed by elastic and 
contractile membranes arranged as canals, in which the blood and lymph 
circulate; and, lastly, the serous membranes, which line the interior of the 
splanchnic cavities, and cover the surface of the organs contained in them. 

Apparatus.—Organs are very numerous in the animal economy, and in, 
order to study them profitably it is necessary to classify them in a methodi- 
cal manner, according to their physiological affinities. Consequently, there 
have been collected into a single category all those organs which are destined 
to achieve the same physiological finality, and to such a group has been given 
the name of apparatus. 

An apparatus is, then, an assemblage of all those organs of an animal 
which concur to the same end, and which serve for the accomplishment of 
the same function. 

We will successively describe, in the following order, the different appa- 
ratus of which the organism is composed :— 


1. Locomotory Apparatus ; 

2. Digestive Apparatus ; 

3. Respiratory Apparatus ; 

4. Urinary Depurative Apparatus ; 
. Circulatory Apparatus ; 

. Innervatory Apparatus ; 

. Sensory Apparatus ; 

. Generative Apparatus ; 


CO MTS Or 


This description will be terminated by a brief exposition of the evoluticn 
of the fetus and its appendages. 
: 4 


BOOK I. 
Locomotory APPARATUS, 


Tux locomotory apparatus is composed of all those organs which minister to 
the movements an animal may execute. It is certainly one of the most im- 
portant in the economy, from the number and volume of the pieces which 
enter into its formation, and by the necessary co-operation that it affords the 
other apparatus in the performance of the physiological acts which are 
allotted to them. 

It is constituted of two kinds of organs; the bones and muscles. The 
bones, hard and resisting, stony in appearance, are real inert levers, joined to 
each other by firm and movable articulations, which permit their playing 
upon each other with the greatest facility, at the same time maintaining 
them in their relative positions. The muscles, grouped around the bones 
and attached to them, are soft organs which possess the property of contrac- 
tion, under certain determinate conditions and of involving in that move- 
ment the bones to which they are fixed by their extremities. The first are 
altogether passive in their motion, while the second are really the active 
organs of locomotion—the powers intended to move the bony levers. 

We will treat successively of :— 


1, The study of the bones, a particular branch of descriptive anatomy 
which has received the name of osteology ; 

2. The study of the articulations, or arthrology , 

8. The study of the muscles, or myology. 


FIRST SECTION, 
THE Bones. 


CHAPTER I, 
THE BONES IN GENERAL. 


Bonzs, properly speaking, are only to be found ir vertebrate animals, and 
constitute their principal zoological character. In the animal body they 
form an internal framework which consolidates the entire edifice, and gives 
it its general form and dimensions. It is advantageous, before commencing 
a particular description of each bone, to survey them ina general manner. 
This study comprises: 1, The description of the skeleton 3 2, The summary 
indication of the general principles which should be known in order to com- 
prehend the details of the special descriptions. 


THE SKELETON, 7 


Articte I.—Tuer SKELETON, 


The whole of the bones, considered in their natural relations to each 
other, constitute the skeleton. In order to prepare the skeleton of any 
animal, it is sufficient to free it from the soft parts surrounding it. The 
skeleton should be designated natural, if in this operation the ligaments 


SKELETON OF THE PIG. 


8 THE BONES. 


that naturally join the various pieces together are allowed to remain; and 
artificial if, after these ligaments have been destroyed, it ig necessary to 
replace them by materials foreign to organisation, such as iron or bras¢ 
wire. 

The skeleton is divided into trunk and limbs. 

The trunk offers for consideration, in the median line, the spine or 
vertebral column, a flexible stalk measuring the entire length of the animal, * 
‘and composed of a series of distinct pieces articulated one behind the 
other, Anteriorly, this stalk supports the head, a pyramidal protuberance 
which itself results from the assemblage of a large number of bones. 
On each side of the middle portion of the spine, there are detached bony 


SKELETON OF THE HORSE, 


arches which have received the name of ribs, and which rest direct 
or indirectly, by their inferior extremities, on a single bone called the 
sternum. These bony arches in this way circumscribe the thorar. a 
spacious cavity destined for the reception of the principal organs of re- 
spiration and circulation. is 

The limbs, four in number, two antertor and two 1 
appendages which support the trunk. Each represents a eek Sided 
into several rays resting upon one another, and generally forming more 
or less acute angles. The anterior limbs are each divisible into four 
principal regions: the shoulder, applied against the front part of the thorax; 
the arm, which succeeds the shoulder; and the fore-arm and foot. The 
oad ae? Hage comprise four regions: the haunch or pelvis "which 
articulates wi ine ; igh, 1 
oo the posterior part of the spine; and the thigh, leg, and 


“HE SKELETON, 


In birds, the posterior limbs al 


of support.’ The anterior limb, 
wings, 


9 


one assume the function of columns 
s, formed for flight, constitute the 


Fig. 4, 


HT i Field hr 
FEM Fa A$ Gy) 
oa a Nt 


a) \ 


SKELETON OF THE SHEEP, 


The number of bones entering into the composition of the skeleton of 
the domesticated animals, arrived at the adult period of life varies according 


10 GENERAL PRINCIPLES APPLICABLE TO 


to the species. They are apportioned to the regions of the trunk and limbs 
just mentioned, in the manner indicated in the following table: 


DESIGNATION. Solipeds.! | Ruminants. Pig. Dog.2 
Vertebral Column*® . , . 44 43 42 43 
Head? or a ee 28 28 a9 28 
Thorakic i 2 4 3 37 27 29 27 
Shoulder . 1-2 1-2 1-2 1-2 
Arm . \ 1-2 1-2 1-2 1-2 
Fore-arm. 2-4 2-4 a ae 
Fore-foot . . 16-32 20-40 36- 36-7 
Pelvis Houle regione 1-2 1-2 1-2 1-2 
Thigh . 1-2 1-2 1-2 1-2 
Leg . . 3-6 ae 3-6 3-6 
Hind-foot | 15-30 | 19- 36-7 32-64 

1391 (QA Z bal HEA 


Articte Il.—Gzxyerat Princrptes APPLICABLE TO THE STUDY OF ALL 
THE Bones. 


The description of any bone comprises its name, situation, direction, 
conformation, structure, and mode of development. 


Name. 


The nomenclature of osteology does not rest on any basis capable of 
conferring upon it a methodic form. Consequently, we find bones which 
derive their name from their shape, (example: the fibula); others from 
their resemblance to known objects (the tibia and vomer). Some owe it 
to their position (cétes, sides or ribs), or their uses (the axis and parietal 
bones). Several attempts have been made to submit the nomenclature of 
the bones to more precise and uniform rules, but the new designations 
proposed have not been sanctioned by custom. 


Situation. 

The situation of a bone should be viewed ia two ways: 1st, Relative to 
the median plane of the body ; 2nd, Relative to the other portions of the skeleton. 

A. Situation relative to the median plane of the body. The designation 
of median plane, or improperly median line, is given to an imaginary vertical 
plane, passing through the middle of the skeleton which it divides, from 
before to behind, into two equal portions. The bones may be situated 
on the median plane, in which case there is only one of each kind, and 
they are called single; they are also named symmetrical bones, because 
the median plane divides them into two equal lateral halves exactly alike. 
The bones disposed in a double and regular manner on the sides of the 
median plane bear, for this reason, the name of pairs; they are also called 
asymmetrical bones, because their form does not admit ‘of their being 
separated in any sense into two similar portions. On the contrary, a bone 


of this kind always offers the most perfect symmetry with its fellow on the 
opposite side. 


? One lumbar vertebra less is found in the ass, and sometimes also in the mule. 
"? The os penis has not been included. 
* The sacrum is reckoned as a single bone, and the number of coccygeal vertebra: at 
an average of 12 for the Horse, 16 for the Ox, 14 for the Pig, and 15 for the Dog. 
* Theos hyoides comprises, and is reckoned as, a single bone. 


THE STUDY OF THE BONES. 11 


B. Relative situation to the other parts of the skeleton.—To indicate the 
situation of a bone, considered from this point of view, is to make known the 
place it occupies in the region to which it belongs, and the connections it may 
have with adjoining regions. Thus the radius is situated in front of the 
ulna between the arm-bone and the carpus.’ 


Direction. 


This is absolute or relative. The direction of a bone may be vertical, 
horizontal, or oblique. Example: the scapula is placed in an oblique direc- 
tion from above to below, and from behind to before. 


Configuration of the Bones. 


Formu.—This is also absolute or relative. 

A. Absolute Form—tThe absolute form of a bone is that which it owes to 
the relations existing between its three dimensions—length, width, and 
thickness. a. A bone in which one of its dimensions much exceeds those of 
the other two is a long bone. Example:—the femur. All the long bones are 
hollowed out internally by an elongated space—the medullary cavity. Long 
bones belong exclusively to the limbs. In the animal economy, there are found 
bones which resemble them in their dimensions, but they have no medullary 
canal. Example:—the ribs. These differ essentially from the true long 
bones, and are sometimes distinguished from them by the appellation of 
elongated bones. b. A bone that offers two dimensions much more developed 
than the third, is a flat or wide bone. Example:—the parietal bone. The 
bones of this category, destitute of a medullary cavity, are met with in the 
head and the upper regions of the limbs. c¢. A bone which offers nearly the 
same development in all its dimensions, is called a short-bone. Example :— 
the astragalus. Destitute, like the preceding, of a medullary cavity, the 
short. bones are found in the spine and some regions of the limbs. 

B. Relative Form.—To make. known the relative form of a bone is to 

indicate the greater or less exact resemblance it may bear to geometrical 
figures, or to familiar objects.. Thus the scapula is a bone of a triangular 
form. 
_ Exrernan Pscuriariries or Bones.—These markedly attract the atten- 
tion, because they modify the general shape of bones, and singularly assist 
us in distinguishing one bone from another. These peculiarities, which are 
real distinctive features that permit their description to be precisely esta- 
blished, are always either eminences (processes) or depressions. 

E'minences.—The eminences that stand out in relief from the surfaces of. 
bones are divided into two different categories. One class concurs in the 
formation of the articulations which join the bones to each other; they are 
named articular eminences, in which, again, are distinguished diarthrodial and 
synarthrodial eminences, according as they belong to movable or immovable 
articulations. ‘The others, usually destined for the insertion of ligaments 
and muscles, are called non-articular, or eminences of insertion. 

(The term imprint is also used in anatomy, and signifies a collection of 
small rugged eminences which make the surface of the bone uneven and 
rough. There are muscular, tendinous, ligamentous, and aponeurotic im- 
prints, according as they give attachment to muscles, tendons, ligaments, or 
aponeuroses. ) ; : 

The synarthrodial eminences are always indentations more or less deep 
and finély cut. 


12 GENERAL PRINCIPLES APPLICABLE TO 


The diarthrodial eminences are voluminous and smooth, and in a fresh 
state are covered with cartilage. They are named heads and condyles: 
heads, when they describe the segment of a sphere (head of the femur, head 
of the humerus); condyles, when they represent tne segment of an oval 
figure, cut parallel to its large axis (condyles of the femur.) ; 

The non-articular eminences receive various names. If they are volumi- 
nous and much detached from the bone, they are called processes or apophyses. 
Apophyses receive qualificatives derived from the analogies perceived between 
them and known objects. (Examples :—the styloid, clinoid, coronoid and 
coracoid processes.) The appellations of protuberances and tuberosities 
are given to non-articular eminences when they are large and round, and 
but slightly prominent. Lastly, they are named lines, crests, and ridges, 
when they are narrow and very long. ; 

Cavities. —The cavities of bones have also been divided into articular and 
non-articular cavities. 

The first correspond to the eminences of the same name in the bony 
joints. They take the designation of cotyloid cavities when they are deeply 
excavated, like a basin or the cup of an acorn (the glenoid cavity of the 
scapula, and the cotyloid cavity of the coxa). 

The non-articular cavities serve either for ligamentous or muscular 
implantation, or for the passage of vessels, nerves, tendons, etc. 

They are termed channels or furrows, when they are wide, deep, and 
smooth; grooves, when they are long, narrow, and even at the bottom; 
Jissures, when they are narrow and rough. Digital impressions ts the name 
given to those excavations in bones which look as if produced by the 
pressure of the finger. The fosse, sinuses, cells, and notches are also non- 
articular cavities of bones. The sinuses and cells are formed by open 
spaces in the interior of bones; notches, by cavities excavated on their 
margins. 

When a cavity passes quite through a bone it is termed a foramen. If 
this foramen offers a certain length, it is then designated a conduit or canal. 
Fissures are long, narrow foramina; hiatus is the term applied to wide 
openings with irregular outlines. 

Recions or THE Bonzs.—When it is desired to describe the eminences 
and external cavities of a bone, it is essential not to notice them, as it were, 
by chance—passing indifferently from one to another. In order to avoid 
the difficulties which would result from the application of such an irrational 
system, it is convenient to divide the bone to be described into several 
regions, in which are examined, one after another, all the external peculiari- 
‘ties that may offer. 

The following is the course to pursue in order to establish the regions 
of a long, a flat, and a short bone. 

(a) A long bone is always divided into three parts: a body and two 
extremities. The body, middle part, or diaphysis, is the narrowest portion of 
the bone. It represents a geometrical solid, approaching more or less the 
figure of a very elongated prism. In a long bone, therefore, it is necessary 
ee study as many faces, angles, or borders, as the prism it represents may 
offer. 

With regard to the extremities, or epiphyses, these are more or less con- 
siderable enlargements, showing articular surfaces, as well as surfaces 
intended for muscular or ligamentous insertion. 

( b) A flat bone must necessarily have two faces, as well as borders and 
angles, 


THE STUDY OF THE BONES, 13 


. (c) A short bone offers for description a variable number of faces, and 


plane or salient angles, which are often neglected because of their trifling 
importance. 


Internal Conformation of Bones. 


Sections made in various directions through the substance of bones show 
that their internal conformation varies, according as they belong to the 
category of long, flat, or short bones. The diaphysis of long bones is 
hollowed out into a large fusiform cavity; this is the medullary canal. 
This canal is absent in the flat and short bones. Its walls are formed by a 
very dense bony tissue, whose pores are scarcely visible to the naked eye, 
and which is called the compact substance. The extremities of long bones 
are surrounded by a thin layer of compact substance, while the remainder 
of their mass is constituted by the spongy substance—bony tissue channeled 
into cells, or very large areole, which freely communicate with each other. 
(Reticulated bony tissue is but another form of spongy substance, the only 
difference between the two consisting in the cells or meshes of the first 
being formed of intercrossed osseous fibres, while those of the second are 
formed of lamelle.) The medullary canal, and areole of the spongy tissue, 
are filled by a cellulo-fatty substance, the marrow (or medulla), The flat 
bones are constituted by a layer of spongy tissue placed between two laminz 
of compact substance. In the flat bones of the cranium, the two layers of 
compact tissue are termed the vitreous tables, while the cells of the spongy 
tissue are designated diploé. In certain points of their extent, the spongy 
substance disappears, and then the bone is found to be composed of a single 
lamina of compact tissue. The short bones have a nucleus of spongy 
substance, enveloped in a layer, more or less thick, of compact tissue. ~ 

The compact substance of the bones being very resisting, is found in all 
those situations which have to sustain violent efforts. The spongy substance 
is very light and bulky, and is met with in the widened portions of the 
bones, to which it affords increased size without adding sensibly to their 
weight, 


Structure of Bones. 
Bones are formed of a proper tissue, covered externally by a particular 
Fig, 6. 


membrane, the periosteum, and occupied internally 
by the medulla, vessels, and nerves. 

Proper tissue.—The texture of the proper tissue 
of bones varies slightly in the compact and spongy 
substance. 

The compact tissue is composed of a funda- 
mental substance, which is amorphous, or slightly 
granular, white, and more or less opaque, accord- 
ing to the thickness it offers. 

This fundamental substance is penetrated by 
an infinite number of vascular canaliculi, known 
as the Haversian canals. These canals, which 
measure from 1-2500th to 1-200th of an inch in 


C 


ry ted [ \ | 
diameter, are parallel to each other and to the a 
municate by transverse branches. The most | oan section a ny 
superficial open on the surface of the bone, be- “showing the network of 


larger axis of the bone; they frequently com- jf} ‘ Nile Wt \ 
neath the periosteum, and the deepest into the Haversian canals. 


14 GENERAL PRINCIPLES APPLICABLE TO 


medullary canal; while a certain number terminate in the areole of the 


spongy substance. : 2 
tituted by several concentric lamelle 
The walls.of these canals are cons " eel owt sae alee 
Fig. 7. the body of these are lodged the 
essential elements of the bony 
tissue, or osteoplasts (corpuscles or 
lacune). These are minute cavi- 
ties lined by a cellular membrane, 
and furnished, at their: circum- 
ference, with a great number of 
canaliculated prolongations, which . 
communicate with the adjacent 
osteoplasts,-or with the Haversian 
canals, In a thin dried section 
of bone, the osteoplasts appear 
black by transmitted light, and 
= white and brilliant by direct light; 
MINUTE STRUCTURE OF BONE, as shown ina thin t¢hig appearance has led some ob- 
Halil aaa a | to the direction of the servers to suppose that they Scans 
1, A Haversian canal surrounded by its concentric formed of small masses of calca- 
lamelle; the lacune are seen between the la~- reous matter. It is now well 
mellz, but the radiating tubuli are omitted; known. that they are minute 
2, dbid, with its concentric lamina, lacune, and ramifying cavities, lodging a cell 


radiating tubuli; 3, The area of one of the . : Boa 
eanals; 4, 4, Intervening lamella, and between impregnated with liquid. 


them, at the upper part, several very long In the spongy texture no 
lacunz with their tubuli, Haversian canals can be seen, 
the osteoplasts are irregularly 

Fig. 8. disposed in the thickness of the 


fundamental substance, which con- 
stitutes the septa of the areole of 
this tissue. 

As a rule, the proper tissue of 
the bones is composed of a frame- 
work of organic matter which has 
gelatine for its base, and in which 
are deposited the calcareous phos- 
phates and carbonates, which give 
to this tissue its characteristic 
hardness. This is easily rendered 
evident by immersing any bone in dilute nitric or hydrochloric acid ; acids 
dissolve the calcareous salts, but do not act upon the organic framework. 
So it is that, after some days’ maceration, the bone becomes flexible, like 
cartilage, and loses part of its weight, although it preserves its volume. 
The counterpart of this experiment may be made by submitting it to the action 
of fire. It is then rendered quite friable, because its organic skeleton has 
been destroyed without the earthy salts it contained being affected. 

Periosteum.— This is a very vascular and nervous fibrous membrane that 
covers the entire bone, with the exception of the articular surfaces. Its 
thickness and adherence are not the same everywhere. By its inner face it 
corresponds to the surface of the bone; by its external face, it is confounded 


with the insertion of the tendons and ligaments, or with the surrounding 
connective tissne, 


LACUN#E, OR OSTEOPLASTS OF OSSEOUS SUBSTANCE, 
magnified 500 diameters. 


a, Central cavity; }, Its ramifications. 


THE STUDY OF THE BONES. 15 


The periosteum may be resolved into two layers, though these are not 
very distinct. The superficial layer is essentially fibrous, and is formed by 
a mixture of connective and elastic fibres and plasmatic cells. The deep 
layer also contains a loose connective tissue, but more especially elastic 
fibres, and more or less voluminous spherical or fusiform cells, This is 
called the osteogenous layer. 

Medulla.—The medulla, or marrow, is a pulpy, fatty substance, which fills 
the medullary canal and the areole of the spongy tissue of the bones. 
Somewhat consistent, and of a rose tint in the bones of the young animal, the 
marrow becomes diftluent and yellow in the bones of those advanced in age. 
In the first instance, it only contains traces of fat; while in the second it has 
96 per cent. of this substance. The medulla of bones is composed of: 
Ist, Some trabecule of delicate connective tissue, which serves to support 
the vessels and nerves; 2nd, Fat either free or inclosed in vesicles; 
8rd, Particular cells, named by M. Robin medullo-cells and myeloplaces. 

The medullo cells, abundant in the red or foetal marrow, are small cells 
with a spherical nucleus; while the myeloplaxes are large, flattened, or 
polyhedral elements of an irregular outline, containing a great number of 
nuclei. Rare in the yellow marrow, they are more particularly found 
adhering to the walls of the medullary canal, or the alveoli of the spongy 
tissue. 

Blood-vessels.—The arteries of bones belong to three orders; a distinction 
founded on their volume and the extent of their distribution. 

The arteries of the first order penetrate to the interior of the medullary 
canal of long bones by a particular orifice, the nutritious foramen. They 
soon divide into two branches, which break up into a network that lines the 
walls of the canal and enters the tissue of the medulla. This network 
communicates with the arteries of the second order, which are destined to 
the spongy tissue of the extremities of the long bones, penetrating them by 
the numerous nutritious foramina that surround the epiphyses. Lastly, the 
arteries of the third order are branches of the periostic network which enter 
the superficial Haversian canals. These canals which open in this manner 
on the surface of the bones may be considered, strictly speaking, as a third 
category of nutritious conduits. In the flat and short bones there are no 
arteries of the first order. . 

Veins accompany the arteries, and are always more voluminous than 
these; they frequently make their exit by special and very large openings 
at those points where the spongy tissue is abundant. The veins of 
bones sometimes exhibit saccular dilatations on their course. Certain veins 
in the cranial bones have their parietes entirely composed of osseous tissue. 

Lymphatic vessels.—The existence of these in the interior of bones 
cannot be affirmed. ee 

Nerves.—These belong to the cerebro-spinal and ganglionic system of 
nerves ; the latter are always vaso-motory nerves. 

Almost constantly a somewhat voluminous nerve enters the medullary 
canal by passing through the nutritious foramen, and is distributed to the 
medulla. The compact tissue receives few nervous filaments; while, on 
the contrary, the spongy tissue at the extremities of the long bones, as well 
as the short bones, obtains an abundant supply. Certain short bones, such 
as the vertebra, are especially remarkable for the numerous nerves they 


receive, 


16 GENERAL PRINCIPLES. APPLICABLE TO 


DEVELOPMENT OF BONES. 


Bones, before arriving at the state in which they present themselves in 
the adult animal, pass through several successive phases, whose study consti- 
tutes what is termed osteogeny. 

In the embryo, at a very early period, the bones are composed of a 
mucous material analogous to that which enters into the composition of all 
the other organs; this matter is constituted by a mass of what are called 
embryonic cells, Ata later period they are impregnated with gelatine, and 
nearly all become harder, white, and elastic, passing into the cartilaginous 
state. Exception must be made, however, to the lateral and anterior parietes 
of the cranium and the face, the bones of which are at first fibrous but 
never cartilaginous. The cartilaginous bones show a fundamental amorphous 
substance, in which are disseminated spherical cells containing one or more 
nuclei. This condition is transitory; the cartilaginous tissue soon submits 
to modifications which result in conferring on the pieces that it composes 
the hardness and structure of perfect osseous tissue. These modifications 
constitute the process of ossification. ‘There are several portions of the 
skeleton which do not undergo this osseous transformation, and which 
most frequently remain in the cartilaginous condition during the entire life 
of the animal. These permanent cartilages are met with at those points 
where the bony skeleton must preserve a certain degree of flexibility, 
and on the articular surfaces. During the process of ossification, the 
cartilages become vascular, are impregnated with calcareous salts, and 
excavated with Haversian canaliculi and medullary cavities. The saline 
molecules are deposited in the amorphous substance, which grows more 
hard and opaque ; at the same time the cartilaginous cells become the point of 
departure of a new embryonic proliferation, from which results the neoplasts. 

Ossification begins at the same time in several parts of the skeleton, and 
in each of the bones in particular; though it does not appear over the 
whole extent of the latter at once; on the contrary, in certain determinate 
points of the cartilaginous mass, bony tissue can be perceived developing 
itself and extending gradually until it finishes by completely invading it. 
These points are called centres of ossification. 

These centres are primary or complementary ; the latter are in some way 
added to the bone, and form, wholly or in part, certain processes. Although 
these centres of ossification enlarge from day to day, yet for a somewhat 
long period they remain completely independent of one another, and are only 
connected by cartilaginous tissue. 

The term epiphyses is given to the osseous centres which are placed at 
the extremities of the principal centre. When the skeleton is completely 
developed, the various centres of ossification are fused into each other, and 
then there are no longer epiphyses ; this fusion always takes place at an almost 
determinate epoch. It has been remarked that, of two epiphyses, it is con- 
stantly the one near which the nutritious foramen is directed that is first 
united to the body of the bone. 

Growth.—Bones grow in width and thickness by the apposition of new 
elements. In the long bones, the growth in length takes place by the 
ossification of the cartilage uniting the epiphyses to the body of the bone. 
Consequently, elongation should cease as soon as the epiphyses are incor- 
porated with the diaphysis. With regard to the long bones of the limbs, 
Duhamel, Flourens, and particularly MM. Ollier and Humphry, have 
remarked that, in the thoracic limb, the extremity furthest removed from 


THE STUDY OF THE BONES. WwW 


the humero-radial articulation grows fastest; while in the abdominal limb. 
the extremity most distant from the femoro-tibial articulation grows the least, 
‘Concerning the growth of the bones in thickness, this occurs by the ossifi- 
cation of the deep layer of the periosteum called the osteogenetic layer. The 
experiments of the above-named authors have irrefutably demonstrated this 
fact. ‘The formation of bony tissue in the deep layer of the periosteum is very 
active during the youth of animals; but it soon slackens, and in advanced 
age ceases completely. In the first period of life, in proportion as the new 
layers are added to the surface of the bone, the old layers, those nearest the 
medullary canal, disappear by resorption. Later, the process of resorption 
exceeds that of formation, which is, in old age, completely annihilated. It 
has also been observed that the formation of a certain quantity of the 
osseous elements takes place on the inner face of the medullary canal, at the 
expense of the medullary tissue. In the flat bones, the primitive centre of 
ossification is developed nearly in the middle, and the calcareous salts are 
afterwards deposited in radiating lines from this spot towards the periphery. 
These bones are augmented in thickness by the formation of subperiostic 
layers, and by the development of the spongy tissue between their two 
compact lamine; they increase in width by the ossification of what are 
termed the marginal epiphyses. 

The short bones grow from the periosteum 
and the epiphysery cartilages, when they possess 
complementary centres. 

Nutrition.—The experiments which consisted 
in feeding young animals with madder, and 
afterwards examining their osseous system, have 
for a long period demonstrated the nutrition of 
bones. When bones cease to grow, their nutri- 
tion becomes less active; but it is evident that 
it does go on, in order to maintain the organic 
matter of the osseous tissue in a proper con~ 
dition. 

(Professor Owen has explicitly and concisely 
stated the development of bone to occur as fol- 
lows :—-“ The primitive basis, or ‘ blastema’ of 
bone is a transparent glairy matter containing 
numerous minute corpuscles. It progressively 
acquires increased firmness ; sometimes assuming 
a membranous or ligamentous state, usually a 
gristly consistence, before its conversion into 
bone. The change into cartilage is noted by 
the appearance of minute nucleated cells, which 
increase in number and size, and are aggregated 
in rows, with intercellular tracts, where the 
ossification is about to begin, as in fig. 9. Gaerne An eR) BERR OR 

These rows, in the cartilaginous basis of “ ossipicarton, showing at its 
long bones, are vertical to its ends; in that of lower portions the clusters 
flat bones they are vertical to the margin. The of ge oe ae eal 
cells furthest from the seat of ossification are ech of which is inclosed in a 
flattened and in close contact; nearest that seat cbstance. 
they become enlarged and separated. ; ; ; 

The first appearance of bone is that of minute granules in the inter- 
columnar and intercellular tissue. Canals are next formed in the bone by 


18 THE BONES 


absorption, which ultimately receive bloodvessels, and become the ‘ — 
canals’ The immediate nutrition of bone is provided for by the production 
of minute ‘plasmatic canals’ from the vascular ones. When uhese canals 
become dilated, so as to offer definite forms, they are termed ‘ lacune ae 
‘bone-cells, and to some extent characterise, by their shape and size, the 
osseous tissue of the respective vertebrate classes. In the concentric 
lamine surrounding the vascular canal, the bone-cells or osteoplasts are 
arranged concentrically, between the lamina, with the long axis in the 
direction of the circular line of the plate. Most of the plasmatic tubes con- 
tinued from the bone-cells pierce the plates at right angles in their course 
to the vascular canal, with which they communicate; and they form the 
essential vehicle of the material for future growth. Extension of parts, 
however, is not the sole process which takes place in the growth of bone; 
to adapt it to its destined offices, changes are wrought in it by the removal 
of parts previously formed. In marine creatures, the bones usually remain 
solid; but in the active land quadrupeds, the shaft of the long bones is 
hollow, the first-formed osseous substance being absorbed, as new bone is being 
deposited without. The strength and lightness of the limb-bones are thus 
increased after the well-known principle of the hollow column. The bones 
of birds present this quality in the highest degree, particularly those of 
powerful flight. In these the medullary cavity of beasts is transformed into a 
capacious cavity containing rarified air instead of marrow. In the mam- 
malian class, the air-cells of bone are confined to the head, and are filled 
from the cavities of the nose or ear, not from the lungs, as in birds. Such 
cells are called ‘frontal sinuses, ‘antrum,’ ‘sphenoidal, and ‘ ethmoidal.’ 
The frontal sinuses extend backward over the top of the skull in the rumi- 
nant and some other quadrupeds, and penetrate the cores of the horns in 
oxen, sheep, and certain antelopes. The most remarkable development of 
cranial air-cells is presented by the elephant, the intellectual physiognomy 
of this large quadruped being caused, as in the owl, not by the actual 
capacity of the brain-case, but by the vast extent of the pneumatic cellular 
structure between the outer and inner plates of the skull-wall. All these 
varied changes in the osseous tissue, from mere cancelli to large medullary 
or pneumatic cavities, are the result of secondary changes by absorption, 
and not of the primitive constitution of bones, which were at first solid.”) 


CHAPTER II. 
THE BONES OF MAMMALIA IN PARTICULAR. 


Arvictz I.—Verreprat Conumy. 


Tue vertebral column, or spine, is a solid and flexible stalk situated in the 
middle and upper part of the trunk, of which it forms the essential portion. 

It protects the spinal cord and sustains the thorax, as well as the principal 
organs of the circulation, respiration, and digestion. Articulated anteriorly 
with the head, and terminating in a point at its posterior extremity, this 
piece is formed by a Somewhat considerable assemblage of short single 

tuberous bones, to which has been given the name of vertebrae, These’ 


THE VERTEBRAL COLUMN. 19” 


bones, though all constructed on an uniform type, yet do not offer the same 
configuration throughout the whole rachidean stalk. The differences they 
present into this respect, have allowed of their being formed into five prin- 
cipal groups; whence the division of the vertebral column in five regions, 
which are, enumerating them from before to behind: 1, Cervical region; 
2, Dorsal region ; 3, Lumbar region ; 4, Sacral region ; 5, Coccygeal region. 
The first comprises seven vertebre, which serve as a base for the animal's 
neck; the second has eighteen, against which the ribs are placed ; the third 
has only six, which correspond to the loins; in the fourth there are five, 
constantly solidified into one mass in the adult, to constitute a single bone— 
the sacrum ; while the fifth possesses a variable number of small degenerate 
vertebrx, gradually decreasing in size to form the tail. The pieces consti- 
tuting the first three regions are called true vertebree; those of the last two 
are designated false vertebre. : 
The characters belonging to all these vertenre will be first studied ; then 
a particular description of the vertebre of each region will be given; and, 
finally, an examination will be made of the spine as a whole. 


CHARACTERS COMMON TO ALL THE VERTEBRE. 
Each of these small bones is pierced from before to behind by a wide 


ELEMENTS OF A VERTEBRA: AFTER OWEN. 2 
al typical vertebra; B, Actual thoracic vertebra of a bird; c, Centrum (or 
5: me eins off, d, d, the ‘diapophyses, and p, P, the parapophyses Cag nealn eu 
articular processes); the neural arch, inclosing the spinal cord, is forme i 
n, n, the neurapophyses (/aminw), and 1, », the neural spine (spinous process); 
the heemal arch, inclosing the great centres of the circulation, is formed by A, h, 
the hamapophyses (costal cartilages) , and fh, s, the ner lee Coat ay 
From both the neurapophyses and heemapophyses may be given o a e aygapop yses, 
z, 2. The lateral arches, which may inclose the vertebral arteries, 0, ® are 
completed by the pleurapophyses (ribs), pl. 5 these in Bare bent downwards, so 
as to form part of the hemal arch, and give off the diverging appendages, u, a. 


s a ‘ ' iy 
i he spinal foramen ; whence results, for the entire spine, a 
pea eae its whole length, and which lodges a very important 


20 THE BONES. 


portion of the nervous centres—the spinal marrow. This canal, which 
traverses the vertebra’ from one end to the other, transforms it into a 
veritable ring in which we recognise, for facility of description, two parts— 
the one inferior, the other superior. ‘The first, or body; is very thick, and 
forms the base of the vertebra; the second, which is thin, has been de- 
signated spinous or spinal, from one of the peculiarities it, presents, or annular, 
because it circumscribes the major portion of the spinal foramen. This 
division is not altogether an arbitrary one, for the body and the annular por- 
tion constitute, in the foetus, two distinct pieces, which do not become 
united for a long time after birth. ; ; 

Bopy.—The shape of the body of a vertebra is that of a prism with four 
faces, of which two only—the superior and inferior—are free, and can be 
studied in the adult; the two lateral faces being united and confounded 
with the annular portion. This prism also presents two extremities—an 
anterior and posterior. ; 

Faces. —The superior face, limited in extent, forms part of the spinal 
foramen, constituting its floor. It exhibits: 1, On the median line, two 
roughened, prominent surfaces, representing two triangles, whose summits 
are opposed; 2, On the sides, two depressed smooth surfaces, perforated by 
one or more openings that lead to the interior of the bone. The inferior 
face is divided into two lateral portions by a median crest. 

Extremities.—The anterior has a prominent convex head, more or less 
detached. The posterior offers a cavity for the reception of the head of the 
next vertebra.. These two planes, the one convex, the other concave, do not 
come into immediate contact; an elastic, flexible fibro-cartilage, firmly 
attached to each, being interposed between them. 

Annutar Portion.—This is formed by an osseous plate that curves sud- 
denly downwards, in the shape of an arch, the two extremities of which 
approach each other, inclose the body, and become united to it. It offers 
for study: 1, An internal and an external surface; 2, An anterior and a 
posterior border. 

Surfaces.—The internal surface, concave and smooth, forms, with the 
superior face of the body, the spinal foramen. The ewternal, convex and 
irregular, presents: 1, A single prominence, raised in the middle of the 
superior portion, and named the spinous process ; 2, The transverse processes 
are a double pair of eminences, one on each side, and projected transversely 
outwards. 

Borders,—The anterior border has two articular facets looking upwards: 
these are the anterior articular processes, right and left. In each is a notch 
which, when placed in opposition to a similar excavation in the preceding 
vertebra, forms the intervertebral foramen. The posterior border presents the 
same peculiarities, with this difference, that the articular faces of the pos- 
terior articular processes are inclined downwards, to correspond with the 
anterior facets of the succeeding vertebra. 

Structure of the vertebre.—The compact substance, which is abundant in 
the spinous portion, forms, in the body, an extremely thin layer, inclosing \ 
a voluminous nucleus of spongy tissue. The latter is traversed by numerous 
venous canals, which open on the surface of the bone. 

Development.—tIt has been already shown that the body and spinous 
portion of a vertebra constitute, in young animals, two distinct pieces. Each 
was primarily formed from two lateral centres, which met on the median line. 
In the body, the fusion of these centres is so prompt, that it is generally 
believed, perhaps justly, that the development of this part of the vertebra 


THE VERTEBRAL COLUMN. 21 


proceeds from a single centre of ossification. The union of the two centres 
in the annular portion, usually designated the vertebral lamin, is slower 
It commences in the most anterior vertebre, and is latest in the sacral mee 
coccygeal regions. To the two principal pieces of the vertebra in process of 
ossification, is added, at a subsequent period, complementary points of ossifi- 
cation, five or six in number: one or two for the spinous process, one for the 
summit of each transverse process, another for the head, and the last for the 
posterior cavity of the body. 


CHARACTERS PROPER TO THE VERTEBRE OF EAOH REGION. 


A casual inspection of a vertebra might suffice, strictly speaking, to dis- 
tinguish the region of the spine to which it belonged. For instance, a 
cervical vertebra is recognised by its volume, the absence of a spinous 
process, and the foramen which traverses the base of its transverse processes. 
The dorsal vertebra is conspicuous by its tubercular transverse processes, 
and by being furnished, outwardly, with an articular surface, as well as 
by the depression on its body destined to receive the heads of the ribs. The 
lumbar vertebra has its long flattened transverse processes; while the 
coccygeal vertebra offers rudimentary lamines and processes. There is no 
necessity for noticing the sacrum, whose five pieces form one bone: a feature 
_ which markedly distinguishes it from the other regions of the vertebral 

-column. But these few distinctive characteristics do not satisfy the require- 
‘ments of descriptive anatomy; so that it is necessary to undertake a more 
extensive study of each of these regions. 


1. Cervical Vertebre., 


GervzeraL Coaracters.—These vertebre, the longest and thickest in the 
spine, present generally a cubic form. They are usually distinguished from 
the vertebre of the other regions by the following characters :—The 
inferior spine of the body is strongly marked, especially behind, where it 
terminates in a small tubercle. The head is well detached from the re- 
mainder of the bone, and deseribes a very short curve. The posterior cavity, 
wide and deep, represents a veritable cotyloid depression, which is too 
large to fit the head exactly; the intermediate fibro-cartilage on these two 
surfaces is also of a great thickness. The spinous process forms a simple 
roughened, and but slightly prominent, ridge. The transverse processes, very 
developed, are elongated in an antero-posterior direction, and inclined down- 
wards. ‘In this region they are designated the trachelian processes, because 
of their relations with the trachea; a foramen that traverses them from 
before to behind at their base has been, for the same reason, named the 
trachelian foramen (vertebral foramen). The articular processes, large and 
prominent, are inclined downwards and inwards. The notches are wide and 
deep. 
Apectera Cuaracrens.—The seven cervical vertebra are reckoned from 
before to behind, and receive numerical names indicating their place in the 
region. ‘ 

O riet,—The first vertebra of the neck, which has been named the atlas, 
deserves a very careful description. At first sight there is recognised the 


1 So named from thé mythological personage who was supposed to support the earth, 
as the first vertebra (human) supports the head. (For this bone in the domesticated 


animals the name is not appropriate.) 
5 


Neeme 


99 af THE BONES. 
great development of its ‘transversal diameter, the considerable dimensions 
of the spinal foramen, and the thinness of its body. The intra-rachidian- 
face of the latter is divided into two portions by a transverse ridge: one 
anterior, furnished with ligamentous imprints, exhibits, laterally, two deep 
excavations, which lodge the venous sinuses; the other, posterior, is smooth 
and concave from side to side, and forms an articular surface into which 
is received the odontoid process of the axis; this surface resembles the 


ATLAS 5 INFERIOR SURFACE. 

1, Articular processes for condyles of 
the occipital bone; 2, ibidem; 3, 
Vertebral or antero-internal fora- 
men; 4, Posterior, or cervical fora- 
‘men; 5, Transverse process; 6, 
Tubercle representing the inferior 
spinous process; 7, Superior arch, 
forming the roof of the spinal fora- 
men. 


Fig. 12. 


@ 
A CERVICAL VERTEBRA, 

1, Superior spinous process; 2, An- 
terior articular processes; 3, Pos- 
terior articular processes; 5, An- 
terior convex face of body, 6, 7, 
Transverse processes, with their 
.tubercles or rudimentary ribs; 8, 
Inferior crest, or spine; 9, Concave 
posterior face. 


from six centres of ossification 


becomes a solid piece, and two for 


complementary centres, each 


undulated facets, and the lip of 
Second.—This is named the axis 
cervical vertebrae ; those which succeed it 


augment in thickness. 


cotyloid cavity. The inferior spine of the 
body appears as a large tubercle. The head 
is absent, and is replaced by two concave 
facets. The anterior articular processes have 
their gliding surfaces looking downwards; 
they are joined to the two preceding facets 
to constitute two large diarthrodial cavities, 
which correspond to the occipital condyles. 
There is no spinous process, but a rough- 
ened surface instead. The transverse pro- 
cesses are large, flattened above and below, 
incline forwards and downwards, and are 
provided with a thick rugged lip. Pos- 
teriorly, quite at their base, and on each side 
of the spinal foramen, they show two large 
vertical facets which represent the posterior 
articular processes; these facets are uneven, 
are confounded with the articular cavity of 
the upper face of the body, and correspond 
to the two analogous facets of the axis. 
Each transverse process is pierced at its 
base by two foramina, which traverse it 
from below upwards. The posterior repre- 
sents the vertebral foramen of the other ver- 
tebree ; while the anterior is continued to the 
external surface of the process by a wide, 
deep, but very short channel, running from 
without to within, and joins a third fora- 
men, which enters the spinal canal. These 
last two openings, with the demi-canal 
which unites them, replace the anterior 
notch; the posterior is altogether absent. 
Lastly, an inflected venous canal, whose 
position varies, and whose presence is not 
constant, crosses the lamine of the atlas, 
and opens, on one side, into the spinal 
canal, and on the other, beneath the trans- 
verse process. The atlas contains much 
compact tissue, and is generally developed 
two for the body, which at an early period 
the annular part; the other two are 
of which forms one of the two posterior 
the corresponding transverse process. 

(or dentata). It is the longest of all the 
gradually diminish in length and 


The body of the axis has not any head anteriorly, 


THE VERTEBRAL COLUMN, .- 23 


but conical process termed the odontoid, which is flattened above and below, 
concave and rough from one side to the other on its superior face ; convex 
in the same direction, and perfectly smooth on its inferior face. The latter 
represents an articular half-hinge, 
around which glides the concave arti- 
cular surface on the superior face of 
the body of the atlas. The anterior 
articular processes are carried to the é 
base and to each side of the odon- 1/ 
toidian pivot, in the shape of two un- 
dulated facets, which are confounded 
with the gliding surface of the latter, 
whose destination has been already 
noted. The spinous process, very 
powerful and elongated antero-pos- 
teriorly, is divided behind into two) gyn AXIS, OR DENTATA} LATERAL VIEW, 
roughened lips. The transverse PTO- 1, Superior spinous process; 2, Odontoid pro- 
cesses are slightly developed, and ter- cess; 3, Intervertebral foramen, or hole of 
minate posteriorly inasingle tubercle, conjugation; 4, Body; 5, Inferior spinous 
directed backwards. The anterior Process; 8,7, Inferior and superior articu- 
lating processes. 
notches are very deep, and are most 
frequently converted into foramina. This vertebra, although voluminous, 
is light, in consequence of its containing much spongy substance. In the 
young animal, the odontoid process and the articular surfaces on each side, 
constitute two centres, distinct from each other and from the body of the 
vertebra. After the axis, the cervical vertebre diminish in length and 
increase in thickness ; while the obliquity of their articular processes becomes 
the more pronounced the more distant they are from that vertebra. 

Third, fourth, and fifth—Each of these has, at its transverse processes, 
two prolongations, one anterior, the other posterior. The inferior face of their 
bodies exhibits a median spine terminated posteriorly by a tubercle, which 
gradnally increases in volume from the third to the fifth vertebra. 

The third presents, between its anterior and posterior articular processes 
an almost complete gap; if its anterior extremity be placed on a horizontal 
plane, it will touch that plane by its articular and transverse processes and 
its head. In the fourth, the articular processes are united by a thin, sharp 
osseous plate, notched only in front. Laid on a horizontal plane, the head 
remains some distance from it. The fifth is known by the continuous, thick, 
and rugged lamina which unites the articular processes, and by the tubercle 
of the inferior spine on the body, which is in shape like the heart on a 
playing-card. : . 

Sixth.—This is distinguished by the slight prominence of the spinous 
process, but particularly by the almost total disappearance of the inferior 
spine, and the presence of a third prolongation, very strong and inclining 
downwards at its transverse process, a circumstance to which this vertebra 
owes its designation of tricuspid. ; ; 

Seventh.—This has received the name of prominens, because its spinous 
process, terminating in a point, is more distinct than in the preceding 
vertebrae, the axis excepted. It exhibits, besides: deep imprints, which 
replace the inferior spine, a concave demi-facet on each side of the posterior 
cavity for the articulation of the head of the first rib; a particular disposition 
of its transverse processes, which are unituberculous ; the complete absence of 
the vertebral foramen; and, lastly, the depth and width of its notches, 


24 THE BONES. 


The spinal foramen, which has already assumed a somewhat considerable 
diameter in the sixth cervical vertebra, is still larger in the seventh." 


2.—Dorsal Vertebre. 


GuryzraL Caaracters.—In the dorsal vertebra the body is very short, 
and in front has a large slightly projecting head; behind, it has a shallow 
cavity. laterally, these vertebre present, at the base of the transverse 
processes, four concave articular facets, the two anterior of which are 
situated near the head, while the posterior two are hollowed out of the 
Border of the articular cavity of the body. Each of these facets is joined to 

Fig. 14. an analogous facet on the neighbouring ver- 
5 tebra to form a small excavation, into which 
is received the head of the corresponding 
rib. The spinous process is very high, is 
compressed on both sides, inclines backwards, 
and its summit is terminated by a tubercle. 
The transverse processes are unitubercular, 
and directed obliquely cutwards and up- 
wards; on their external aspect they have a 
diarthrodial plane facet which corresponds 
to the tuberosity of the rib, The articular 
processes are narrow, and constitute simple 
unrelieved facets cut on the base of the 
spinous process. The posterior notches are 
deep, and sometimes converted into foramina. 

Spzcirrc CHaracters.——None of the 
eighteen dorsal vertebre differ much from 
the type just described; and it is difficult 
to establish special characters for each. 


TYPE OF A DORSAL VERTEBRA 3 é . . 
THe FOURTH: ’ Tt is, nevertheless, possible to assign to a 


1, Body; 2,2, Articular facets for the dorsal vertebra, approximately, the rank it 
head of rib; 3, Articular facet for should occupy, in accepting the following 
tuberosity of the rib; 4, Articular facts as a guide:—1. The vertical diameter 


processes; 5, Spinal foramen; 6, . é 
Tastone ese on epinouspimecsas of the vertebral bodies augments progres 


7, Posterior articular face of body; Sively from before to behind. Their lateral 

8, 8, Transverse processes; 9, diameter, which determines that of the spinal 

Superior spinous process; 10, An- canal, becomes, on the contrary, less from the 

ual ertieullnearol venye first to the tenth vertebra; after which it 
assumes increasing proportions to the last one. The articular surfaces, which 
serve for the mutual contact of head and cavity, become larger and shallower 
in proportion as the vertebre are more posterior. The inferior spine on the 
body is very salient and tuberculous in the two first vertebrae, very acute in 
the third and fourth; it disappears in the sixth and ninth, to re-appear and 
become more marked from the tenth to the last. 2. The intervertebral cavities, 
intended for the reception of the heads of the ribs, diminish in depth and 
extent from the first to the last. 3. The longest spinous process belongs to the 
third, fourth, and fifth vertebre; those which follow gradually decrease to 
the eighteenth. Their width diminishes from the second to the eighth; it 
afterwards increases in a progressive manner in the succeeding vertebrae; 


' M. Goubaux has sometimes met with asymmetrical cervical vertebrae ; certain 
vertebre, tricuspid on one side, are only bicuspid or unicuspid on the opposite side. 


THE VERTEBRAL COLUMN. 25 


from the second to the tenth vertebra, the summit of the spinous process is 
large and tuberculous; in the last seven it is flattened laterally. Their 
obliquity is less marked as they proceed backwards; in the sixteenth and 
seventeenth vertebre, the spinous process is nearly vertical; it inclines 
slightly forward in the eighteenth. Those of the tenth, eleventh, and 
twelfth vertebre are slightly curved like an S. 4. The articular processes, 
from the first to the tenth vertebra, gradually contract and approach the 
median line; in the succeeding vertebre they, on the contrary, increase, 
and become concave and wider apart from those of the opposite side. 
5. The volume of the transverse processes and the size of their diarthrodial 
facets diminish from before to behind. In the three first vertebre this 
facet is concave; in the first nine the articular facet looks outwards and 
backwards, while the facet on the body looks forwards; in the last the two 
facets are directed forwards. These two facets are generally confounded in 
the seventeenth and eighteenth vertebrae. The first dorsal vertebra much 
resembles the prominens; it is distinguished from it, however, by the 
presence of four diarthrodial facets on its extremities. It also differs from 
the other vertebrae by the shortness of its spinous process, which terminates 
in a point; by the size and prominence of its articular processes ; and by the 
depth of its notches. The last vertebra never has facets on the contour of 
its posterior cavity. 


8. Lumbar Vertebre. 


GeveraL Cuaracters.—A little longer and wider than the dorsal vertebra, 
which they resemble in the arrangement of their bodies, these vertebrz are 
characterised: 1, By their short, thin, and wide spinous processes, which 
are slightly inclined forwards, and are provided at their summits with a 
scabrous tubercle; 2, By their largely developed transverse processes, 
flattened above and below, and directed horizontally outwards;? 8, By the 
salient anterior articular processes, hollowed out on each side, and provided 
externally with a tubercle for insertion; 4, By their equally prominent 
posterior articular processes, rounded in the form of a half-hinge. 

Sprciric CHaractEers.—The characteristics which may serve to distinguish 
these vertebre from one another are derived from the body, and the spinous 
and tranverse processes. 1. From the first to the last there is a progressive 
diminution in the vertical diameter of the bodies, and an increase in their 
transverse diameter. The inferior spine on the body becomes shorter and 
wider from the first to the last vertebra; in the six vertebre it resembles an 
elongated triangle whose summit is directed forwards. 2. The spinous 
processes decrease in width from before to behind, and their anterior 
border becomes more and more concave; their summits are thickened and 
tuberculous in the three first, and thin and sloping forward in the three 
last. 8. The transverse processes are longer in the middle vertebra 
than in those placed before and behind. The processes in the first and 


' In well-formed horses, it is not uncommon to find nineteen dorsal vertebre, with an 
equal number of ribs; though in these instances there are most frequently only five 
lumbar vertebre. Husson and Goubaux have sometimes met with nineteen, and the 
normal number in the other regions. Sometimes there are only seventeen dorsal 
vertebree. 

2 It has been correctly stated that these processes are the representatives of rudi- 
mentary ribs which have become united to the vertebre. Therefore it is that they are 
frequently designated costiform processes. 


26 THE BONES. 


second vertebre incline slightly backward; in the third they are more up- 
right ; and in the supieeiiiste an are directed a little forward. In the last 


Fig. 15. 


UPPER SURFACE OF LUMBAR VERTEBR.E. 
1, Summit of spinous process, 2, 2, Anterior 

articular processes; 3, 3, Posterior articu- 

lar processes, 4, 4, Transverse processes. 


Fig. 16, 


LUMBAR VERTEBRA; FRONT VIEW. 

1, Body; 2, Its articular face ; 3, Superior spinous 
process; 4, Spinal foramen; 5, Anterior articular 
processes; 6, 6, Transverse, or costiform pro- 
cesses, 7, Posterior articular process. 


two they are remarkable for their 
thickness ; in the fifth an oval-shaped 
articular facet is observed on their 
posterior border; in the sixth, two 
are present—one in front, correspond- 
ing to the preceding, and one behind, 
slightly concave, meeting a similar 
facet on the sacrum. The fourth and 
fifth vertebrae very often correspond, 
at their transverse processes, by 
means of analogous facets.’ 

In the Ass, and sometimes in the 
Mule, only five lumiar vertebre are 
found. According to M. Sanson, this 
is the natural number in the Arab 
Horse.” 


4, Sacrum. 


The sacrum results, as already 
stated, from the consolidation of 
five vertebre. This single bone 
articulates, in front, with the last 
lumbar vertebra; behind, with the 
first coccygeal bone, and on the 
sides with the ossa innominata. It 
is triangular, flattened above and 
below, and from before to behind 
describes a slight curve up- 
wards. It offers for study a 
superior and an inferior face, 
two borders, a base, a summit, 
and a central canal, the exten 
sion of the spinal canal. 

Faces—The superior face 
presents, on its middle, the spi- 
nous processes of the sacral 
vertebrae, which together con- 
stitute what is called the sacral 
or supersacral spine. These 
processes are united at their 
base only, and remain isolated 
for the remainder of their ex- 
tent; they all incline backwards 


' We possess the skeleton of a horse which has seven lumbar vertebrae, with the 


normal complement in the other regions, 
has all its characters, 
region. 

* (This statement is scarcely correct. 


which has six.) 


The seventh is no doubt the first sacral, as it 
The fifth sacral vertebra is evidently derived from the coccygeal 


i i M. Sanson_has established the fuct that there 
is in reality no Arab horse; and asserts that the specific t 


is very probably of African origin, and that these vertebr 
offer individual characteristics different from those obs 


ype with five lumbar vertebra, 
ve, independently of their number, 
erved in the vertebra of the type 


THE VERTEBRAL COLUMN. 27 


and terminate, with the exception of the first, by a tuberous summit, which 
is often bifid; their length diminishes from the second to the fifth bone. 
On each side of the sacral spine 
exists a groove, at the bottom Fig. 17. 
of which are four openings—the 
supersacral foramina. These 
orifices open into the spinal 
canal, and communicate with 
four analogous, but wider aper- 
tures, pierced at the inferior 
face of the bone, and for this 
reason named the subsacral fo- 
ramina, The inferior face is 
smooth, and shows traces of the 
primitive separation of the ver- 
tebral bodies ; the subsacral fo- ko EBA VIEW OR SCRUM 
ramina, which represent, with sy i begat body ie oe shacks 
the corresponding supersacral  o¢ ee terete sia no ig “ 5 race oe 
! f° rtebra; 4, Spinal foramen; 5, 
openings, the intervertebral fo-  Auricular facet; 6, Anterior articular processes; 
ramina of the other regions of 7, Inferior or subsacral foramina; 8, Superior 
the spine, are observed on this spinous processes; 9, Summit or coccygeal ex- 
tremity. 
surface. 

Borders.—The two borders, thick and concave, form, posteriorly, a rugged 
lip; in front, they present an irregular surface inclining obliquely from 
above to below, from within outwards, and from before to behind. This 
surface, which is intended for the articulation of the sacrum with the ossa 
innominata, is divided into two parts: one, the inferior, named in man the 
auricular facet, is slightly undulated and diarthrodial; the other, the 
superior, serves for ligamentous insertions. 

Base.—This offers: 1, On the median line, the anterior orifice of the 
sacral canal, and the anterior articular surface of the body of the first sacral 
vertebra, which is oval and slightly convex; 2, On the borders, the articular 
processes and anterior notches of this vertebra, as well as the elliptical 
and somewhat convex facets which bring it into contact with the transverse 
processes of the last lumbar vertebra. 

Summit.—The summit. thrown back, presents: 1, The posterior orifice 
of the sacral canal; 2, The posterior articular surface of the body of the 
last sacral vertebra; 8, The vestiges of the articular processes and posterior 
notches of that vertebra. 

Sacral canal—This is the portion of the spinal canal which is 
channeled out of the sacrum; it is triangular, and diminishes in width 
from before to behind. 


5. Coccygeal Vertebree. 


The coceygeal region, or coccyx, comprises from fifteen to eighteen de- 
generate vertebre, which gradually diminish from the first to the last. In 
the first three or four, nearly all the characteristics of true vertebre are 
found; they show a spinal foramen, a body, a spinous process, and 
transverse processes, looking backwards; the articular processes only are 
altogether absent. In the succeeding vertebre, these characters become 
effaced ; the vertebral lamina do not join completely, and the spinal canal 
is only a simple groove, which, gradually decreasing in depth, at last 


28 THE BONES. 


entirely disappears. The insertion eminences also become less salient, 
and the coceygeal vertebre are soon reduced to small bony cylinders, 
narrow in the middle and wider at both extremities, with a convex articular 
surface at each end (except the last, which has only one articular surface). 
These small cylinders, the last traces of the vertebral bodies, are each 
developed from three centres of ossification ; they are very spongy and 
light. The first coceygeal vertebra is frequently consolidated with the 


sacrum in aged animals. 


THE SPINE IN GENERAL. 


The vertebral column has now to be considered in its entirety, and 
examined successively in its superior face, its inferior face, its lateral faces, 
and its spinal canal, Afterwards its direction and mobility will be 
noticed. 

Superior face.—This presents, on its median line, the series of spinous 
processes. But little salient in the cervical region, these eminences are 
much developed in the dorsal and lumbar, where they constitute a long 
crest, the dorso-lumbar spine, as well as in the sacrum, where they form 
the sacral spine. They soon disappear in the coccygeal vertebra. 
Outwards, and on each side of these processes, is seen a succession of 
tubercles of insertion, represented in the cervical and lumbar vertebre 
by articular processes, and in the dorsal vertebra by the superior or rugose 
portion of the transverse processes. These tubercles are disposed in line, 
and separated from the spinous processes by a channel designated the 
vertebral groove, which is more or less deep and wide. It is on these, and 
on the spinous processes, that the extensor muscular fasciculi of the spine 
receive the greater portion of their fixed or moveable insertions. 

Inferior surface.—Wide at the neck, this face becomes narrow in the 
dorsal region, to be again widened at the lumbo-sacral region, and once 
more contracted at the coccyx. Crests more or less developed, which divide 
the vertebral bodies into two lateral portions, right and left, are remarked. 

Lateral surfaces.—These offer for study the thirty-six intervertebral 
foramina, through which the spinal nerves pass. They exhibit besides, 
on the neck, the transverse processes; in the back, the external facets 
of these processes, and the intervertebral facets, all destined to sustain 
the heads of the ribs; on the loins, the transverse or costiform processes. 
It may be remarked that the ribs and the transverse processes of the neck 
and loins furnish points of insertion to the powerful muscles which produce 
the lateral movements of the spine. In the sacrum, the lateral faces are 
formed for the articulation of the spine with the ossa innominata. 

Spinal canal.—This canal communicates, in front, with the cranial cavity. 
Very wide in the atlas, for the reception of the odontoid process and to permit 
the rotatory movements of the head without injury to the spinal cord, this 
canal suddenly diminishes in the axis. It again dilates at the termination 
of the cervical region and the commencement of the dorsal; there the spinal 
cord presents a greater volume, and the movements of the spine are very 
extensive. Towards the middle of the back, the spinal canal offers its 
smallest diameter; it widens from this part to the lumbo-sacral articula- 
tion; after which it contracts rapidly, and disappears altogether near the 
fourth or fifth coccygeal vertebra. The lumbo-sacral dilatation coincides 
with the enlargement of the cord in this region, and with the enormous 
quantity of nerves lying beside it. 


THE VERTEBRAL COLUMN. 29 


Direction of the vertebral column.—The spine does not extend in a 
straight line from the head to the posterior extremity of the body. If it 
is followed from the caudal termination, which is free and looks downwards 
to the anterior extremity, it will be seen that it rises upwards and forwards, 
forming a convex inflexion corresponding to the roof of the pelvis. Tn 
the lumbar and the posterior half of the dorsal region it is nearly horizontal 
and rectilinear; from thence it descends to the cervical region, when it 
again rises and forms two curves, the one posterior, bending upwards, the 
other anterior, turned down. This disposition of the cervical spine gives 
it the shape of a console. 

Mobility of the vertebral column.—In the cervical region, the almost total 
absence of spinous processes, the great development of the articular 
processes, and the very short curve described by the surfaces of contact 
of the vertebral bodies, allows the spine very extensive and very diverse 
movements. In the dorsal region, however, these movements are very 
limited, the spinous processes and the costal arches preventing the play 
of the vertebre on each other. In the lumbar region, the spine can be 
flexed or extended more than in the dorsal; but its lateral movements are 
quite as restricted, owing to the presence of the transverse processes and 
the reciprocal joining or dovetailing of the articular processes. Lateral 
motion is even rendered impossible in the posterior half of this region, 
from the manner in which the transverse processes are adapted to each other. 
It may be remarked, however, that this disposition singularly favours the 
integral transmission of the propulsive efforts thrown upon the trunk by 
the posterior extremities. 

The sacral vertebra, having to afford the ossa innominata a solid fixed 
point, could not preserve their independence and mobility, and are conse- 
quently consolidated into a single piece which fulfils all its requirements 
in this respect. In the coccyx the rachidean stalk again recovers its 
mobility, and to a degree more marked than elsewhere ; the coccygeal bones, 
articulated with each other by means of convex surfaces, and deprived of 
long processes at their extremities, are placed in the best possible conditions 
for variety and extent of movement, 


DIFFERENTIAL CHARACTERS IN THE VERTEBRAL COLUMN OF OTHER THAN 
SOLIPED ANIMALS. 


The NumBer of Pieces composing the Sprvz slightly varies in the Domesticated 
Animals, as will be seen in the following Tas. 


VERTEBR&, 

ANIMALS, 

Cervical. Dorsul. Lumbar. Sacral. Coccygeal. 
Ox . 7 13 6 5 16 to 20 
Sheep 7 13 6 or 7 4 16 to 24 
Goat 7 13 6 4 11 to 12 
Pig . 7 14 6 or 7 4 | 21 to 23 
Dog 7 13 7 3 16 to 21 
Cat . 7 13 7 3 21 


A. VERTEBRE or THE Ox, SHEEP, AND Goat.—1. Cervical Vertebrx.—The cervical 
vertebrae of the Ox differ from those of solipeds by their shortness and the greater deve- 
lopment of their insertion eminences. In the Sheep and Goat they are relatively longer 
than in the Ox. The transverse processes of the atlas are less inclined than in the Horse, 


30 THE BONES. 


and have no vertebral foramina; the posterior facets for articulation with the axis are 
nearly flat and join each other. The axis has a semicylindrical, not a conical, odontoid 
process, which is so concave on its upper surface that it looks like a groove. Its spinous 
process is not so thick as in the Horse, and is not bifid posteriorly. . . 

In the jive succeeding vertebre, a rugged continuous lamina unites the anterior articular 
“processes to the posterior. The spinous process inclines forward and is flattened trans- 
versely at its summit, which is sometimes bifid; it augments progressively in height 
from the third to the fifth vertebra. : ; 

In the sixth, the transverse processes have only two prolongations—a superior and 
inferior; the latter, large and flattened on both sides, is bent abruptly downwards. ‘The 
spinous process has already attained the height of 14 to 2 inches in this vertebra, and 
is flattened laterally. : 

The seventh well deserves the name of prominens: its spinous process being no less 
than from 4 to 43 inches. 

2. Dorsal vertebre.—In the Ox these bones are longer and thicker than in the Horse. 
Their spinous processes are larger and incline more backward ; their transverse processes 
are very voluminous, and are provided with a convex facet from above to below; while 
their posterior notches are nearly always converted into foramina. - 

Considered individually, they are more slender in the middle than at the extremities. 
Their spinous processes diminish in width, especially at their summits, from the first to 
the eleventh vertebra, and widen again in the two last; they progressively increase in 
slope to the tenth, after which they become more and more upright; the first four are 
the longest, and are nearly the same in height; the others gradually decrease. 

In the first four or five vertebra, the articular facet of the transverse processes, while 
retaining its vertical convexity, is concave in an antero-posterior direction. This facet is 
always absent in the last vertebra, and sometimes even in the preceding one. The two 
bones terminating the dorsal region show, in addition, the articular processes disposed 
like those of the lumbar vertebrae. 

The dorsal vertebree of the Sheep and Goat are relatively less strong than those of the 
Ox; their spinous processes are not so wide, and their posterior notches are never con- 
verted into foramina. 

3. Lumbar vertebrx.—The lumbar vertebre of the Ox are longer and thicker than in 
the Horse. The transverse processes are also generally more developed, are concave on the 
anterior border, convex on the posterior, and incline slightly downward, with the 
exception of the two first, which remain nearly horizontal. They increase in length from 
the first to the fourth vertebra; in the latter and the fifth, they are nearly of the same 
dimensions; in the last they suddenly become shorter. Their width gradually decreases 
from before to behind. In the fifth and sixth vertebra, these processes have no articular 
facets between them and the sacrum, these being only met with in solipeds. The artic- 
ular processes are prominent, and further removed from the median line as they belong 
to posterior vertebra. 

In the Goat the transverse processes are more inclined downwards. 

In the Sheep, on the contrary, the processes rise up towards their extremities. 

4. Sucrum.—The sacrum of the Ox is more voluminous and curved than that of the 
Horse. The spinous processes are entirely consolidated, and are surmounted by a thick 
rugged lip; they are lengthened at their base and on each side by a ridge that represents 
the rudiments of the articular processes, The lateral borders are sharp and bent down- 
wards, The surfaces that serve to unite the sacrum to the ossa innominata have a some- 
what vertical direction. There are no lateral facets on the base of the bone for the union 
of the sacrum with the transverse processes of the last lumbar vertebra. In the Sheep 
and Goat, the sacrum is shorter; sometimes the consolidation of the spinous processes is 
late, or never occurs. 

5. Coceygeal vertebre.—In proportion, the coccygeal vertebre of ruminants are 
stronger and more tuberous than those of the Horse. The anterior articular processes 
exist in a rudimentary condition. 

:B. Verreseex or tus Pic.—l. Cervical vertebrx.—Of all the domesticated animals, 
this has the shortest, the widest, the most tuberous, and consequently the strongest cervi- 
cal vertebre. The body of these bones is deprived of its crest on the inferior face ; its 
head, but little detached, is scarcely round, and looks as if driven back on itself ; con- 
sequently, its posterior cavity is not deep. 

The vertebral lamin are very narrow, and scarcely extend from one part of the 
vertebra to the other in the superior portion; so that the spinal canal appears at this 
point to be incomplete. 

In the atlas, the transverse processes are yet. less inclined than in ruminants; the 
vertebral foramen is not constant, and when it exists, opens on one side, under the 


THE VERTEBRAL COLUMN. 31 


transverse process, and on the other, on its posterior margin, after pursuing a certain 
track in the substance of the bone. 

The odontoid process of the aais is constricted at its base. This vertebra is distin- 
guished by its high and thin spinous process inclining slightly back, by its transverse 
processes being but slightly prominent and perforated by an enormous vertebral 
foramen. 

In the four succeeding vertebre, the spinous process terminates in a blunt point, and 
inclines forward ; slightly salient in the first, it gradually rises in the others. ‘The trans- 
verse processes form two prolongations: one, the superior, is tuberculous, and is joined 
to the anterior articular process by a plate of bone, which is pierced by a foramen; the 
other, the inferior, flattened on both sides, bent downwards, and large, as it belongs to 
the posterior vertebree, transforms the inferior face of these vertebral bodies into a large 
groove. The seventh is provided with a spinous process as long as those of the dorsal 
region. A perforated bony plate, as in the preceding vertebrae, unites the anterior 
articular process to the single tubercle composing the transverse process; the latter is 
continued back nearly to the pusterior notch by a second plate, also perforated with a 
foramen (see Fig. 2). 

2. Dorsal vertebre—The Pig has fourteen dorsal vertebrae, which, in their general 
disposition, are not unlike those of the Ox. As with that animal, the intervertebral fora- 
mina are double, each vertebral lamina being perforated laterally by an opening situated 
in front of the posterior notch. In addition, the vertebre of the Pig present this pecu- 
liarity, that their transverse processes are generally traversed at the base by a single or 
multiple foramen which communicates with the preceding. 

With regard to the special characters proper to some of the vertebra, these are, as with 
the other animals, very few, and may be described as follows: 1. The transverse pro- 
cesses of the four vertebra preceding the last project but slightly; 2. In the fourteenth 
this process resembles those of the lumbar vertebre; 3. The articular facet of the trans- 
verse process in the four last vertebrae is confounded with the anterior lateral facet 
corresponding to the head of the rib, 4. The articular processes of the last five vertebree 
are arranged like those of the lumbar vertebre ; and the prominence formed by the 
tubercle on the outside of the anterior articular process replaces, to a certain degree, the 
transverse process of these vertebree. é , 

3. Lumbar vertebre.—These bones in the Pig greatly resemble those of ruminant 
animals. It commonly happens that seven are met with; but in this case the supple- 
mentary vertebra is generally a sacral one. It is not denied, however, that seven lumbar 
vertebree may exist in the Pig, along with the normal number of sacral vertebre. 

4. Sacrum.—This is formed by four vertebrae, which are a long time in becoming 
fused together, and it is often difticult to discover where the sacrum ends and the coccyx 
begins! The spinous processes are entirely absent. The vertebral laminw are not 
consolidated ; so that the spinal canal is half cut through in its upper portion, as in the 
cervical region; this canal is also much compressed above and below. 

5. Coccygeal vertebre—These vertebre in the Pig are more particularly distin- 
guished by the presence of articular processes, by means of which the foremost bones 
correspond with each other. 

C. VexTesre or tHE Dog anp Cat.—l. Cervical Vertebrx.—In these animals, the 
cervical vertebre are long and thick, and much resemble those of solipeds. Nevertheless, 
besides their smaller volume, they are distinguished: 1, By the disposition of their 
corresponding articular surfaces; the anterior, or head, is nearly flat, and is even slightly 
excavated in its centre; the posterior, or cavity, is but little hollowed to receive the head 
of the next vertebra; 2, By the width of the vertebral lamine, which exactly cover one 
another; 3, By the height of their spinous processes, which increases as the vertebra 
extend back; 4, By the great extent of the anterior and posterior articular processes, 
which are united by means of a continuous and very salient bony plate, that considerably 
augments the transversal diameter of each vertebra. ; f / 

In the atlas, the articular surface for the odontoid pivot is confounded in front with the 
cavities which correspond to the occipital condyles. The two facets which are annexed 
posteriorly to this articular surface, instead of being plane or gently undulated, as in the 


1This can always be made out, however, by consulting the disposition of the 
articular processes. Thus, in the sacral vertebra these eminences—if we except the 
anterior ones of the first and the posterior of the last—never exist except in a rudi- 
mentary state; while in the other five coccygeal vertebre they re-appear with all their 
characters. 


32 THE BONES. 


other domesticated animals, are transformed into real glenoid cavities.) The transverse 
processes are carried directly outwards and a little backward; the lip which borders 
each is slightly raised; of the two foramina which replace the anterior notch, one only 
exists, and this penetrates to the interior of the spinal canal; the other is merely a simple 
notch. 

In the axis, the odontoid process is cylindrical, narrow at its base, and bent a little 
upwards; the lateral facets of this eminence represent true condyles? The spinous 
process is very thin and undivided, and is curved forward above the lamine of the atlas. 
The anterior notches are never converted into foramina. 

The third cervical vertebra is the largest, and the succeeding ones gradually 
diminish in thickness to the last, contrary to what occurs in the other species. The 
seventh does not show the spinous process so developed as in ruminants and pachyderms 

see Fig. 1). 

f 2. Fonaal vertebr.—In the Dog the dorsal vertebra are formed on the same model as 
those of the Horse; but their spinous processes are in general narrower and thicker. The 
tenth always has its spinous process vertical, triangular, and terminated in a sharp point. 
The last three have no posterior facets for the articulation of the heads of the ribs, and 
exhibit, in the conformation of their articular processes, the same disposition as the 
lumbar vertebra. In the Cad, the transverse processes of the three last dorsal vertebrae 
are thin, sharp, and turned backwards, they never possess facets for the tuberogity of 
the ribs. 

3. Lumbar vertebre.—In the Dog and Cat, the lumbar vertebre are remarkable for 
their strength, due to their length, thickness, and the development of the eminences of 
inseition. ‘The spinous process is low, and becomes acute in the last vertebra. The 
transverse processes incline very much forward and downward ; they become longer from 
the first to the second-last bone, in the latter they become contracted, and in the seventh 
vertebra they are still more diminished, and terminate in an obtuse point. The tubercle 
of the anterior articular process is extremely prominent, and the posterior notches are 
surmounted by a small, very acute prolongation, directed backwards, which becomes 
more developed towards the anterior vertebre. This small prolongation exactly 
represents the transverse process of the dorsal vertebrae. 

4. Sacrum.—The three vertebre which form the sacrum of carnivora are early con- 
solidated. The supersacral spine constitutes a thin sbarp ridge; while the lateral 
surfaces for articulation with the ossa innominata are turned quite outwards and are nearly 
vertical. 

5. Coecygeal vertebrex.—The vertebre of the coecyx are very strong and tuberous, 
The first five or six are as perfect as the true vertebree, and comport themselves in every 
respect like them. The last are small V-shaped bones, which M. Goubaux has described 
by the name of hypstloid bones. 


COMPARISON OF THE VERTEBRAL COLUMN OF MAN WITH THAT OF THE DOMESTICATED 
ANIMALS. 


The vertebral column of Man is composed of twenty-nine bones . twenty-four vertebra, 
the sacrum, and four pieces constituting the coccyx. The twenty-four vertebre are thus 
distributed : 

Cervical vertebrae Pia ie £5 7 
Dorsal 4s etal Leo bys 1g gtk 
Lumbar ‘3 a" us , 5 


_ Inall these vertebra, the bodies are slightly excavated at the two extremities, while 
in the domesticated animals, the superior or anterior is convex, and the inferior or posterior 
concaye. 

1. Cervical vertebre.—These are wide and. short. The spinous processes are mode- 
rately developed and bifid at their summits; the transverse processes are also divided 
into two branches—a posterior and an anterior. 

2. Dorsal vertebre.—In these vertebrae, the bodies increase in thickness from the 
first to the last. In the first as well as in the last dorsal vertebree, the spinous process is 
almost immediately directed backwards; in the middle portion of this region these 
processes are very obliquely directed downwards and backwards. 


: (A glenoid cavity is a shallow, oval, articular depression.) 
(A condyle is an articular eminence representing an ovoid segment, Condyles 
always correspond to the glenoid cavities in the articulations.) 


THE HEAD. 


33 


3. Lumbar vertebre.—The lumbar vertebree are the strongest bones in the spine, 


and their bodies are nearly as thick as those of the larger domesticated animals, 


This 


enormous development of the lumbar vertebree in Man is related to his positi i 

: 7 : a position as a biped. 
In the fifth, the lower face of the body is cut very obliquely backwards and upwards, pnd 
the transverse processes are more voluminous than those of the other lumbar vertebra. 


4. Sacrum.—The sacrum is formed by the union 
.of five pieces. It is very concave from above to 
below and before to behind. In becoming united 
to the lumbar region, it forms a salient angle in 
front, to which has been given the name of promon- 
tory or sacro-vertebral angle. The sacral spine is 
continuous or interrupted, according to the subject; 
it is alway bifid inferiorly. 

5. Coccygeal vertebre.—These are little bones 
or flattened tubercles, four in number, rarely five, 
and usually consolidated. ‘The coccyx is conical in 
shape. Its base shows two processes directed up- 
wards, which are called the cornua of the coccyx. 
Tts summit is often deviated to the right or left. 


ArticLe [].—THe Heap. 


The head is a large bony pyramid, elon- 
gated from above to below, and quadran- 
gular, suspended to the anterior extremity 
of the spine ; it is in a direction varying with 
the attitudes of the animal, but which we will 
suppose, for convenience of description, to 
be nearly vertical. It is formed of a great 
number of particular bones, which are only 
distinct from one another in very young 
animals; for well before the adult period is 
reached the majority of the bones are united 
and cannot be separated. 

The head is divided into two parts: the 
cranium and the face. 


BONES OF THE CRANIUM. 


The cranium, or upper part of the head, 
is composed of seven flat bones, five of 
which are single: the occipital, parietal, 
Frontal, sphenoid, and ethmoid ; one only, the 
temporal, is double. These bones cireum- 
scribe a central cavity, the cranial, which 
communicates behind with the spinal canal, 
and lodges the principal portion of the 
nervous centres—the encephalon. 


1, Occipital Bone. 


The occipital bone occupies the superior 
extremity of the head, which it supports 
from the anterior extremity of the spine. 
This bone is very irregular in its form, and 
is bent at a right angle in front and behind. 


Tt has an eaternal and an internal face, and 
a circumference which brings it into contact 


HORSE’S HEAD; FRONT VIEW. 


1, Occipital protuberance ; 2, Origin 


of the mastoid crest; 3, Parietal 
bone; 4, Saggital suture; 5, Junc- 
tion of the parietal and temporal 
bones; 6, Zygomatie arch; 7, 
Frontal bone; 8, Frontal suture ; 
9, Temporal fossa ; 10, Supraorbi- 
tal foramen; 11, 12, Lachrymal 
bone; 13, Malar bone; 14, Nasal 
border of frontal bone; 15, Nasal 
bone; 16, Suture of nasal bones ; 
17, Superior maxillary bone; 18, 
Infraorbital foramen; 19, Ante- 
rior, or pre-maxillary bone; 20, 
Foramen incisivum; 21, Incisor 
teeth—young mouth. 


with the adjoining cranial bones ; the latter is subdivided into two anterior 


84 THE BONES. 


lateral borders, two posterior lateral borders, an anterior and posterior salient 
angle, and two lateral re-entering angles. : 

Faces.—The external face is dividéd into three portions by the double 
flexure of the bone: one looks forward, another upward, and the third 
backward. It exhibits:—1. On the median line, and from before to behind : 
a, an antero-posterior ridge which constitutes the origin of the parietal 
ridges, to be mentioned hereafter; b, a transverse, voluminous, and very 
prominent eminence, marked posteriorly by deep imprints, with a medium 
projection named the cervical tuberosity; this is the eaternal occipital pro- 
tuberance which, in the Horse, corresponds at the same time to the superior 
curved lines of the occipital bone of Man. This protuberance forms the 
culminating point of the head, and divides the anterior and superior parts of 
the external face of the bone; ¢, the occipital foramen (foramen magnum), a 
large orifice that passes through the bone at the posterior flexure, and esta- 
blishes a communication between the cranial cavity and spinal canal; d, the 
external surface of the basilar process, a narrow and thick prolongation formed 
by the bone as it passes to meet the sphenoid : this surface is convex laterally. 
2. On the sides: a, A sharp crest which prolongs, laterally, the superior 
curved lines, and descends on the middle of the lateral anterior border to be 
continued with the superior root of the zygomatic process and the mastoid 
crest of the temporal bone; b, Linear imprints, parallel to the latter, and 
prolonged on the base of the styloid process: they are destined for the 
insertion of the small oblique muscle of the head, and represent the inferior 
curved lines of the occipital bone of Man ; c, Within these imprints is a slightly- 
roughened cavity for the insertion of the posterior recti muscles; d, The two 
condyles, articular eminences with a double convexity, one superior, the other. 
inferior : these eminences are situated on each side of the occipital foramen 
(foramen magnum), and correspond to the anterior cavities of the atlas; 
e, More outwards are the two styloid processes, or jugular eminences, long 


projections flattened on each side, terminated in blunt points, directed back- 


wards, and separated from the condyles by a deep space, the stylo-condyloid. 
notch; f, Under the condyles is the condyloid fossa, a smooth depression, 
pierced at the bottom by the condyloid foramen, which penetrates the cranium. 
The internal face of the occipital bone is concave, and shows :, behind, 
the foramen magnum ; above, an uneven surface, which forms the roof of the 
cerebral cavity; below, the superior face of the basilar process, slightly 
hollowed into a groove; on the sides, the internal orifice of the condyloid 
foramen. 
Circumference.—The anterior lateral borders are thick, and are united by 
suture with the parietal bone, and with the tuberous portion of the tem; oral 
bone by the harmonia! suture. The posterior lateral borders are sharp, and 
constitute the sides of the basilar process; each concurs in the formation of 
the occipito-spheno-temporal hiatus, also termed the lacerated foramen, a vast 
irregular opening, extending from above downwards, penetrating the 
cranium, and divided by a ligament, in the fresh state, into two portions, 
one inferior, the anterior lacerated foramen, the other superior, the posterior 
lacerated foramen. The anterior angle, which is dentated, is dovetailed into 
the parietal bone. The posterior angle is very thick, and forms the summit 
of the basilar process; it is united by suture with the body of the 
sphenoid. The lateral re-entering angles, or jugular notches, correspond to the 
1 (The harmoni iy, t i i ition « i : 
ace are esha abet reel hear asi 6 atic aa 
® (The anterior and posterior lacerated foramen of Man.) 


THE HEAD. 35 


point where the bone is bent posteriorly ; they separate the anterior lateral 
from the corresponding posterior lateral border, and are occupied by the 
tuberous portion of the temporal bone. 
Structure.—The occipital bone contains much spongy substance. 
Development.—It is developed from four centres of ossification : one, the 
anterior, is single, and forms the occipital protuberance; another ” the 
posterior, also single, forms the basilar process; the other two are pairs, and 


comprise each a condyle, with the styloid process and the corresponding 
condyloid foramen. 


2. The Parietal Bone. 


The parietal is a wide and thin bone, very much arched to form the roof 
of the cranial cavity. It is bounded above by the occipital bone, below 
by the frontal, and laterally by the two temporal bones. It offers for study 
on is and internal face, and a circumference divided into four regions or 

orders. ; 

Faces.—The external face is convex. It exhibits two curved ridges whose 
concavity is directed outwards; these two crests, which are termed the 
parietal ridges, approach each other and unite superiorly, to be continued 
with the antero-posterior ridge of the occipital bone; below they diverge 
and proceed, one on each side, to join the supraorbital process. They 
divide the surface of the bone into three portions: two lateral, which are 
rough and traversed by vascular channels, forming part of the temporal fosse ; 
the third, or middle, is plane, smooth, and of a triangular form, and covered 
by the skin. The internal face is concave, covered by digital impressions, 
and grooved by small vascular canals; it offers, on the median line, and 
altogether above, the parietal eminence.’ This trifacial and very salient pro- 
jection presents at its base, on each side, an excavation elongated trans- 
versely, into‘which opens the parieto-temporal canal, and which is destined 

ve tO lodge a venous sinus. It is continued, in front, by a median crest, which 
is often replaced by a slight groove, the saggital furrow, bordered by linear 
imprints. Two other ridges, resulting from the abutment of the lateral 
border of the bone against the anterior face of the petrous bone, rise from the 
sides of this eminence and descend to the sphenoid bone; they separate the 
cerebral from the cerebellar cavity. 

Borders.—The superior border is notched, thick, and slightly dentated ; 
it articulates with the occipital bone. The inferior border, slightly concave, 
and deeply dentated, offers an external bevel in its middle portion, and an’ 
infernal bevel on its sides; it corresponds with the frontal bone. The 
late ul borders are very thin, and are cut at the expense of the external plate 
into a wide, sloping edge, which shows a groove destined to form the 
parieto-temporal canal. A very prominent angle separates each into two 
portions, an inferior, that articulates by suture with the squamous portion 
of the temporal bone ; and a superior, curved inwards towards the centre of 
the cranial cavity; the latter portion of the lateral border is in contact 
with the anterior face of the petrous portion of the temporal bone, with 
which it concurs to form the lateral crest that descends to the parietal 
eminence. . 

Structure.—This bone contains much compact tissue, the spongy sub- 


stance existing only in its middle. ; : 
Development.—It is developed from two large centres of ossification, to 


1 The internal occipital eminence of Man, 


36 THE BONES. 


which is added a single centre to form the parietal eminence.’ In early 


life the parietal ridges are absent. 


3. Frontal Bone. © 


The frontal is a flat quadrilateral bone, whose sides are bent in the 
middle at an acute angle, and are carried back, and a little inwards, to meet 
the wings of the ‘sphenoid bone. It assists in forming the cranial roof and 
part of the face. It is bordered: above, by the parietal bone; below, by the 
nasal and lachrymal bones; and on each side, by the temporal bones. It 
offers for study an external and an internal face, and four borders. 

Faces.—The external face is divided, by the double flexure of the bone, 
into three regions: a middle and two lateral. The first, nearly plane, is 
lozenge-shaped, is covered by the skin, and constitutes the base of the fore- 
head. It gives rise on each side, at the point where it is inflected, to a long 
process, flattened above and below, which curves backward, forming the orbital 
arch. The superior or external face of this process is convex and slightly 
roughened ; the internal face is smooth and concave, and forms part of the 
orbital fossa. Its posterior border, thick and concave, is continued, in- 
wardly, with the corresponding parietal ridge, and outwardly with the 
superior border of the zygomatic process. It limits, in front, the temporal 
fossa. The anterior border, also concave, but thin, concurs in the forma- 
tion of the orbital margin; the summit, thickened and denticulated, rests 
upon, and is united to, the zygomatic process of the temporal bone; the base 
is wide, and is traversed by an opening termed the supraorbital, or super- 
ciliary foramen. The two lateral regions of the external face of the frontal 
bone are slightly excavated, and assist, for the greater portion of their 
extent, to form the orbits. They often show, near the base of the orbital 
arch, a small depression corresponding to the flexure described by the 
great oblique muscle of the eye in passing through its pulley. ; 

The internal face of the frontal bone is concave, and divided into two 
unequal parts by a transverse ridge, corresponding to the anterior border of 
the cribriform plate of the ethmoid bone. The superior, the most extensive, 
is covered with digital impressions, and belongs to the cranial cavity. It 
exhibits: 1, On the median line, a slight furrow, or a crest which is con- 
tinuous, above, with the median ridge of the parietal bone, and below, with 
the crista-galli process ; 2, On the sides, and in the re-entering angle formed 
by the flexure of the boné, there is a narrow slit, or mortice, which receives 
the wing of the sphenoid bone. The inferior part is united, on the median 
line, to the perpendicular plate of the ethmoid. It assists in forming the 
bottom of the nasal cavities, and presents laterally two large openings 
which lead to the frontal sinuses—vast anfractuous spaces excavated 
between the two plates of the bone. 

Borders.—The superior border is denticulated, and cut obliquely, in its 
middle portion, at the expense of the internal plate, and on the lateral pdrts 
at the expense of the external table; it is in contact with the parietal and 


' This centre is described as the interparietal bone by those anatomists who consider 
the two lateral centres as two distinct parietals. (Leyh is one of the veterinary anatomists 
who describe this nucleus as a separate bone, designating it the falciform or interparietal 
bone. He also describes the parietal as a pair or double bone; whereas the majority of 
French anatomists include the interparietal bone as the median protuberance of the 
parietal, which they look uponas a single or impair bone. Percivall names it a pair bone, 
but follows the example of the French hippotomists with regard to the interparictal.) 


THE HEAD. 37 


squamous portion of the temporal bone. The inferior, prolonged tu a 
point in the middle, is in apposition with the nasal bones through the 
medium of a wide external bevel; laterally, it is very thin, faintly serrated, 
and articulates with the lachrymal bone. The lateral borders, thin and 
irregular, present two notches: one, the superior, is wide and deep, and 
occupied by the wing of the sphenoid bone; the other, inferior, is very 
narrow, and uniting with a similar notch in the sphenoid bone, forms the 
orbital foramen, which opens into the cranium, very near, but external to, 
the ethmoid fossa. Each of these borders, also, is adapted, for a limited 
extent, to the corresponding palate bone. * : 

Structure.—The two compact plates of the frontal bone are separated by 
spongy texture towards the middle and in the upper part; they separate 
below to form the frontal sinuses. Laterally, they are very thin and 
consolidated with each other. 

Development.—The frontal bone is developed from two lateral centres of 
ossification, which only coalesce at a late period. In youth the cranial 
portion of the bone forms, in front of the head, a large rounded protuberance 
standing beyond the facial portion. This prominence disappears when the 
frontal sinuses begin to be developed. These cavities do not exist at an 
early period of foetal life ; but commence to form about the fourth month of 
conception, by a process of resorption, which removes the spongy substance 
interposed between the two compact tables of bone, and may even cause the 
destruction of the internal table. The sinuses enlarge with age, and remain 
during life separated from one another by a vertical septum. 


4, Ethmoid Bone. 


The ethmoid bone, deeply situated in the limit between the cranium and 
the face, is inclosed between the frontal, the sphenoid, the vomer, the palate, 
and the supermaxillary bones. It is composed of three portions: a 
perpendicular plate, and two lateral masses. 

Tue Prrrsnpicunar Lamina or tHe Eramor Bonz.—Situated in the 
median plane, and flattened on both sides, this bone presents two faces, a left 
and right, and four borders. 

Faces—The faces, covered by the pituitary membrane, present, pos- 
teriorly, small sinuous crests; elsewhere they are smooth. A very narrow 
interval, constituting the bottom of the nasal cavities, separates them from 
the lateral masses. 

Borders.—The superior border looks towards the centre of the cranial 
cavity, and constitutes what is called the ethmoidal ridge, or crista-galli 
process. It is free, concave, and sharp, prolonged in front and above by the 
median crest of the frontal bone, and confounded behind with the middie 
portion of the inferior sphenoid. The inferior border is continuous with the 
cartilaginous plate which separates the nasal cavities. When this plate 
becomes ossified, which is not unfrequent, it is impossible to discover the 
point where it begins or the ethmoid bone terminates. The middle septum 
of the mose has been considered, and justly, as a prolongation of the perpen- 
dicular plate (or lamina) of this bone. The anterior border is consolidated 
with the vertical septum which separates the frontal sinuses. The posterior 
border is joined, above, to the median plate which divides the sphenoidal 
sinuses into two compartments. Below, it is fixed in the groove of the 
vomer, and goon becomes confounded with that bone, which is itself conso- 
lidated with the inferior sphenoid. 

Lateran Masszs or THE Eramor Bons.—Theso are two large pyriform 

6 


38 


THE BONES. 


tuberosities placed on each side of the perpendicular lamina, and offering 
for study a middle portion, a base, and a summit. Each of these is formed by 
an assemblage of numerous, extremely thin, osseous plates, curved into 


small and very fragile convolutions. 


These, elongated from above to below, 


become longer as they are more anterior; they are attached by their superior 
extremities to the transverse plate which separates the cranium from the 
nasal cavities, and by one of their borders to a thin leaf of bone which 


Fig. 19. 


ANTERIOR BONES OF THE HEAD OF A FETUS 


(HORSE) AT BIRTH; 
VIEWED FROM BEHIND, 


DISARTICULATED, AND 


envelops the lateral masses out- 
wardly. They have received the 
name of the ethmoidal volutes (or 
cells). 

Middle portion.—This should 
be studied externally and inter- 
nally. 

The eaternal surface of each 
ethmoidal mass is divided into two 
sections: an internal, making 
part of the nasal cavities; the 
other, external, concurs in form- 
ing the walls of the frontal and 
maxillary sinuses. The first, the 
least extensive, is almost plane; 
parallel to the perpendicular la- 
mina, it is isolated from it by the 
narrow space which forms the 
bottom of the nasal cavities; it 
presents several openings which 
separate the most superficial cells, 
and join the internal canals to be 
hereafter noticed. The second, 


A, Occipital bone.-—1, Condyle; 2, Con- 
dyloid foramen; 3, Styloid process; 
4, Summit of basilar process.—x, Parie- 
tal bone.—8, Parietal protuberance; 
9, Channel which concurs to form the 
parieto-temporal canal.—c, Frontal 
bone.—10, Transverse crests separating 
the cranial from the facial portion of 
the bone; 11, Frontal sinuses; 12, 
Notch on the lateral border occupied 
by the wing of the sphenoid bore; 13, 
Notch for the formation of the orbital 
foramen; 14, Summit of the orbital 
Process; 15, Supraorbital foramen.— 
D, Perpendicular lamina of the ethmoid 
bone.—x, ©, Lateral masses of ithe eth- 
moid bone.—16, The great ethypoid cell. 
—F, Squamous portion of the;temporal 
bone—17, Supercondyloid process ; 
18, Channel for the formation of the 
parieto-temporal canal.—a, Tuberous 
portion of the temporal bone.—5, Mas- 
toid process; 6, Internal auditory 
hiatus; 7, Opening for the eustachian 
tube into the tympanum.—x, Lach- 
rymal bone.—z, Nasal bone—J, Su- 
perior turbinated bone, 


THE HEAD. 39 


very extensive and convex, looks outwards in front and behind, and is covered 
by an osseous plate traced with shallow furrows, which correspond internally 
with the small crests to which the cells are attached. This lamella is 
prolonged, inferiorly, a little beneath the inferior extremity of these latter, 
and turns outwards to articulate with the palate and superior maxillary 
bones ; superiorly, it coalesces with the sphenoid and the orbital portion of 
the frontal bone. 

Internally, the lateral masses are hollowed from above to below by 
extremely diverging canals, which open inferiorly into the nasal cavities, 
and separate the cells from one another. ‘The latter are so incurvated that 
the internal cells communicate with each other. There are some, however, 
which are completely closed ; the anterior, or great cell, is frequently so. 

Base.—The base of each lateral mass looks upwards, and is formed by the 
transverse septum between the cranium and the nasal cavitics. This 
septum is perforated by openings which give passage to the ethmoidal nerves ; 
it is named the cribriform plate of the ethmoid bone. It is concave on 
the superior surface, which constitutes the ethmoidal fossa, and convex on 
the opposite face, where attachment is given to the superior extremities of 
the cells. It is consolidated internally with the perpendicular plate; the 
other points of its circumference are attached to the sphenoid bone, and to 
the transverse ridge on the internal face of the frontal bone. 

Summit.—The summit of each lateral mass is formed by the inferior 
extremity of the ethmoidal cells, which is directed downwards towards the 
nasal cavities. One, more voluminous than the others, is carried much 
lower, and terminates by a rounded protuberance. It corresponds to the 
middle cornu (concha media) of Man. 

Structure of the ethmoid bone.—Very little spongy tissue enters into the 
composition of this bone, and this is only found near the anterior border of 
the perpendicular plate. 

Development.—The ethmoid bone is late in attaining its development, 
and the adjoining bones are nearly completely ossified when it is yet 
entirely cartilaginous. The bony transformation commences in it at the 
inferior extremity: of the cells, and advances progressively from below 
upwards. The perpendicular plate is only ossified in part when the cells 
have passed through the first half of the process; at the same time it 
coalesces with the inferior sphenoid. The cribriform plate is the last to 
become ossified; this transformation having scarcely been achieved when 
the animal is six or eight months old. 


5. Sphenoid Bone. 


The sphenoid bone is situated behind the cranium, between the occipital, 
ethmoidal, palate, vomer, pterygoid, frontal, and temporal bones. It is 
flattened from before to behind, curved from one side to the other, thick in 
its middle part, named the body, and thin on the sides, which, in their 
inferior half, are prolonged in the form of alc or wings. Tt has two surfaces 
and four borders. : 

Surfaces.—The external surface 18 convex, and presents: 1, On the 
median line, the external surface of the body, rounded from one side to the 
other, is continued with that of the basilar process, and has marked mus- 
cular imprints superiorly; 2, On the sides and from within outwards: a, 
the videan (or pterygoid) fissure, directed from above downwards, and con- 
tinued by the vidian canal, a very small foramen which opens into the 


1 Tt ig not rare to find it opening into the frontal sinus. 


40 THE BONES. 


orbital hiatus; b, the subsphenoidal, or pterygoid process, a long eminence, 
flattened on both sides, inclining downwards, articulating with the palate 
and pterygoid bones, and traversed at its base by the vidian canal; c, a 
little behind and above this eminence, the superior orifice of the sub- 
sphenoidal foramen, a large canal which bifurcates inferiorly ; d, more in 
front, the orbital hiatus, a kind of vestibule into which open in common the 
principal branch of the subsphenoidal canal, the three supersphenoidal 
canals, the vidian and optic canals, and the orbital opening: this hiatus is 
surmounted by a thin and sharp bony plate, above which opens the smallest 
branch of the subsphenoidal foramen; e, altogether without the hiatus is 
remarked a smooth surface belonging to the wing of the sphenoid, and 
which concurs to form the orbital cavity. 

The internal face is concave from side to side. It shows: 1, On the 
median line, and from before to behind, a small projection united to the 
crista-galli ; the optic fossa, elongated transversely in the form of a shuttle, 
and presenting at the bottom, and on each side, the superior orifice of the 
optic foramen, a cylindrical canal directed obliquely downwards, forwards, 
and outwards, to reach the orbital hiatus; the supersphenoidal or pituitary 
fossa, also named the sella turcica, a slight depression, limited behind by a 
scarcely noticeable transverse projection separating it from the superior 
channel of the basilar process; 2, On the sides, and in front, the internal 
surface of the wings, depressed by very superficial digital impressions ; 
more behind and outwards, a fossa, elongated from before to behind, which 
lodges the mastoid lobule of the brain; between this fossa and the sella 
turcica, two vertical fissures : an internal, named the cavernous sinus, and an 
external, wider and deeper, for the passage of a large nervous branch. 
These two fissures open below, near the junction of the three super- 
sphenoidal canals. Two of these, which are very wide, are placed one before 
the other, and separated only by a slight partition. The superior of these 
constitutes the great sphenoidal fissure ; the other, the lower, is the foramen 
rotundum, and opens into the orbital hiatus. The third, very small, is situated 
outside the great anterior canal, opens above the optic foramen, within the 
bony mass surmounting the hiatus, and sometimes on the free margin of 
this lamina. 

Borders.—The superior is a little concave, and shows, in its middle, the 
superior extremity of the body, mammillated and articulated with the 
summit of the basilar process; on each side, two notches which circumscribe 
below the occipito-spheno-temporal hiatus (foramina lacera basis cranit). 
The internal notch is the narrowest, and from its affording a passage for the 
internal carotid artery, is called the carotid notch ; it is continued on the 
external face of the bone by a smooth excavation to which Rigot has given 
the name of carotid fossa. The external is also prolonged on the exterior 
surface cf the sphenoid by a short and wide fissure; it lodges the inferior 
maxillary nerve. Outside this is another very narrow notch, intended for 
the passage of the middle meningeal artery. The fibro-cartilaginous sub- 
stance that partly fills the occipito-spheno-temporal hiatus, transforms these 
notches into foramina, the first of which is named the carotid canal, the 
second, the foramen ovale, and the third, the foramen spinosum. The inferior 
border, also concave, is likewise divided into three portions, a middle and 
two lateral. The first is thick, and formed by the inferior extremity of the 
body ; it is excavated by two large cavities belonging to the sphenoidal sinus. 
These cavities are separated from one another by a vertical osseous plate, 
often perforated, which, at an early period, is fused with the perpendicular 


VHE HEAD, 41 


lamina of the ethmoid bone, The very thin lateral portions form part of the 
circumference of the wings; they are notched near their union with the 
middle piece to assist in the formation 
of the orbital foramen. The two lateral 
borders are thin and convex in their an- 
terior half, as is also the contour of the 
wings, which are mortised in the frontal 
bone. For the remainder of their extent 
they are thick, denticulated, and bevelled 
at the expense of the external plate, to 
articulate with the squamous portion of 
the temporal bone. 

Structure.—This bone is compact on 
its sides, and spongy in its middle part; 
inferiorly, it is excavated by the sphe- 
noidal sinuses. 

Development.—lt is developed from 
two principal nuclei of ossification; a 
superior forms the subsphenoidal pro- 
cess and the canal of the same name, 
the vidian fissure, pituitary fossa, fissures 
of the internal face, and the most pos- 
terior of the great supersphenoidal 
canals ; the other, the inferior, forms that 
portion of the body hollowed by the 
sinuses, the lateral ale,! and the optic 
fossa and canals. In meeting each 
other, these centres form the vidian canal 
and the two anterivr supersphenoidal 
canals. They are not consolidated with 
each other until a very late period ; for 
which reason they are sometimes de- 
scribed as two distinct bones. M. porepion BONES OF THE HEAD aniok 
Tabourin has even proposed to attach parts (ose) AT BIRTH; DISARTICU- 
the description of the inferior sphenoid Larep aND VIEWED IN FRONT. 
to that of the ethmoid, because it is a, Sphenoid bone,—1, Maxillary notch; 2, 
united with this bone along time before Carotid notch ; 3, Groove for the passage 
a, &. 6% : . of the maxillary nerve; 4, Cavernous 
it is joined to the superior portion. muss &, Otic tomes 6 Great wines 
5" i ti reat, wing ; 
6. Te emporal B one. a fete Puen he the abil 


The temporal bones ihelose the foramen—x, Vomer.—c, Palate bone.— 

¥ : : 4 D, Zygoma.—F, Superior maxilla,—8, In- 
cranial cavity laterally , and articulate ferior orifice of the maxillo-dental canal. 
with the occipital, parietal, frontal, __», Premasillary bone. 
sphenoidal, and the zygomatic bones; ee . 
also with the inferior maxilla and the hyoid bone. Each is divided into 
two pieces, which are never consolidated in the horse; one forms the 
squamous portion of the temporal bone ; the other, the tuberous portion. They 
will be described separately. : sa 

Squamors Portion—This is flattened on both sides, oval, and’ slightly 
incurvated like a shell, a shape to which it owes its name. It offers for 
study an external and an internal fage, and a circumference. 

1 These wings are not analogous to f. Se portions of the sphenoid bone in Man bear- 
ing the same name, They are the processes of Ingrassias enormously developed. 


42 THE BONES. 


Faces.—The external face is convex, and marked by some muscular 
imprints, vascular fissures, and openings which penetrate the parieto- 
temporal canal. It forms part of the temporal fossa, and gives origin near 
its middle to the zygomatic process, a long eminence which at first runs 
outwards, and goon curves forwards and downwards to terminate in a 
thin summit. The base of this eminence forms, in front, a concave surface 
belonging to the temporal fossa ; behind, it offers the articular surface which 
corresponds with the maxillary bone. The latter is composed of: 1, A condyle 
transversely elongated, convex above and below, and slightly concave from 
side to side; 2, A glenoid cavity, limited below by the condyle, above | by a 
mammiform eminence, the supercundyloid,} against which rests the maxillary 
condyle when this bone is drawn backwards; it is immediately above this 
eminence that the inferior orifice of the parieto-temporal canal.opens. The 
external ‘face of the zygomatic process is smooth and convex; the internal, 
concave, is also smooth, and bordered cutwards by the temporal fossa. Its 
anterior border is sharp and convex; the posterior, very short, is thick and 
roughened. Its summit is flattened from before to behind, and marked by 
notches on its two faces; it somewhat resembles a wedge, fixed as it is 
between the orbital process of the frontal bone and the zygoma; it comes 
in contact with the maxillary bone, and by a small portion of its anterior 
face, which is deprived of notches, it concurs in circumscribing the orbital 
cavity. In the domesticated animals, as in Man, the zygomatic process 
appears to arise from the surface of the bone by two roots: one, the inferior 
or transverse, is represented by the condyle; the other, the superior, forms a 
sharp crest which is continuous with the anterior border of the process, and 
above, joins the lateral crest of the occipital protuberance. 

The internal or cerebral face of the squamous portion is divided into two 
parts by an almost vertical channel which terminates above the super- 
condyloid eminence, and which, meeting a similar furrow on the parietal 
bone, forms the parieto-temporal canal. The superior portion is but of 
small extent, and of a triangular form; it articulates by a simple harmonia 
suture with the external face of the petrous portion. The inferior part, the 
widest, presents in its middle some cerebral impressions. For the re- 
mainder of its extent or circumference, it is cut into a wide, dentated, and 
lamellar bevel, which brings it in contact with the surrounding bones. 

Circumference.—This may be divided into two borders: one, anterior, is 
convex and united with the parictal and frontal bones; the other, posterior, 
articulates with the sphenoid in its inferior moiety, and is provided, above 
the level of the supra-condyloid eminence, with a deep notch which receives 
the external auditory canal. Superiorly, the two borders unite at the summit 
in a thin point which rests on the occipital bone. 

Structure.—The squamous portion of the temporal bone is formed of 
two very thin compact plates which have but little spongy tissue between 
them ; the latter, however, is very abundant in the body of the zygomatic 
process. 

Development.—It is developed from a single nucleus of ossification. 

Tuszrovs Portion.—This is one of the most interesting parts of the 
skeleton for study, in consequence of its containing two systems of cavities 
which inclose the essential organs of hearing. One of these systems is 
named the cavity of the tympanum or middle ear ; the other forms the internal 
ear, These cavities will be studied when we come to speak of the auditory 


’ In Man this is represented by the inferior or vertical ramus of the upper root of the 
zygomatic process, 


THE HEAD. 43 


apparatus. In the meantime, only the exterior surface and the structure 
and development of this portion of the temporal bone will be noticed. 

It is wedged between the antero-lateral border of the occipital bone, the 
lateral border of the parietal, and the superior part of the internal face of 
the temporal shell. It represents a quadrangular pyramid whose base is 
turned downwards and a little backwards. It will be studied successively in 
its four faces, a summit, and base. 

Faces.—The anterior face is united by harmonia suture to the parietal 
bone. The postericr face articulates in the same manner with the 
occipital bone, The eaternal face lies against the squamous portion of the 
bone. The internal face, slightly concave and marked by very superficial 
digital impressions, forms a part of the lateral wall of the cerebellar cavity. 
It presents the canal or internal auditory hiatus (meatus auditorius internus), 
a small fossa, the bottom of which is pierced by several foramina for the 
transmission of nerves; the largest of these is the internal orifice of the 
aqueductus Fallopii, a flexuous canal which passes through the bone and 
opens at the external surface of its base; the other foramina penetrate the 
cavities of the internal ear. 

These faces are separated from each other by so many borders or plane 
angles, two of which more particularly merit attention; one of these isolates 
the external from the posterior face, and the other separates the anterior 
from the internal face. The first is thick and rugged, and constitutes the 
mastoid crest ; it is continuous above with the lateral ridge of the occipital 
bone, after being united to the superior root of the zygomatic process, and 
terminates, near the base of the bone, by a tuberosity for muscular insertion, 
to which has been given the name of mastoid process. This border is 
traversed by a slit, the mastoid fissure,! which passes under the squamous 
portion and enters the parieto-temporal canal. The second is thin, and, 
with the superior part of the lateral border of the parietal bone, forms the 
crest which establishes the line of demarcation between the cerebral and 
cerebellar cavities of the cranium; it gives attachment to the tentorium 
cerebelli. 

Summit—This is slightly denticulated, and articulates with the occipital 
bone. 

Base.—This is very irregular, and offers: outwardly, the external auditory 
canal which penetrates the middle ear, and the external orifice of which has 
been named in veterinary anatomy the external auditory hiatus ; inwardly, a 
sharp crest which circumscribes the external contour of the lacerated 
foramen ; above, and under the mastoid process, the stylo-mastoid or pre-mastoid 
foramen, the external orifice of the aqueduct of Fallopius; below, the 
subuliform (or styloid) process for the attachment of the stylo-staphyleus 
(tensor palati) muscle and the Eustachian tube : this is a long, thin, and pointed 
process presenting, at its base and within, a canal which enters the cavity of the 
tympanum, and which is incompletely partitioned by a small bony plate into 
two parallel portions ; in the centre, the hyoid prolongation or vaginal process,” 
a little cylindrical eminence surrounded by a bony sheath, and the mastoid 
protuberance or process, a slightly salient, smooth, and round eminence 
hollowed internally by numerous cells, which form part of the middle ear. 

The several small and very remarkable canals which pass through the 
tuberous portion of the temporal bone, will be noticed when the nervous and 
arterial branches they lodge are described. 


1 This ig the analogue of the mastoid canal in Man. . 
2 This process is prolonged by a cartilage that unites it to the styloid bone. 


44 THE BONES. 


Development.—The tuberous portion of the temporal bone is developed 
from two principal centres of ossification which are consolidated at birth, and 
which are often described as two distinct portions: the one as the petrous or 
stony portion, the other as the mastoid portion. 

The faces, borders, summit and inner side of the base of the bone are 
formed by the petrous part, which contains the cavities of the internal ear 
and furnishes the inner wall of the middle ear. 

The mastoid portion constitutes almost entirely the base of the temporal 
pyramid ; to it belongs the external anditory canal, the mastoid process, the 
sheath of the hyoid prolongation, and the styloid process; it forms the 
external wall and circumference of the case of the tympanum. 

For the tuberous portion of the temporal bone there are also two small 
complementary nuclei: one for the vaginal process, whose base is united 
to the petrous portion, and another forming the ring of the tympanum. 

Structure—The petrous portion is the hardest mass of bone in the 
skeleton, and scarcely contains any spongy tissue, except at the centre of the 
mastoid process ; in the mastoid portion it may be said not to exist. 

In the other domesticated animals, the tuberous portion of the temporal 
bone is always consolidated with the squamous, and the summit of the 
zygomatic process only articulates with the malar bone. 


BONES OF THE FACE. 


The face is much more extensive than the cranium in the majority of the 
domesticated animals, and is composed of two jaws, a bony apparatus that serves 
as a support to the passive organs of mastication—the teeth. The superior 
or anterior jaw, traversed in its entire length by the nasal cavities, is formed by 
nineteen wide bones, only one of which, the vomer, is a single bone ; the. 
pairs are: the superior and intermawillaries (or premawillaries), the palate, 
plerygoid, zygomatic, lachrymal, nasal, and superior and inferior turbinated bones. 
Of these only four, the maxillaries, are intended for the implantution, of 
the teeth; the others form the union between the cranium and the superior 
maxilla, or concur in the formation of the nasal cavities. The lower jaw has 
for its base a single bone, the inferior maxilla or mamillary bone. 


1. Great Supermawilla, or Superior Mawillary Bone. 


This bone, the most extensive in the upper jaw, is situated on the 
side of the face, ard is bordered above by the frontal, palate, zygomatic, and 
lachrymal bones; below, by the premaxillary bones ; in front, by the nasal 
bone; behind and within, by that of the opposite side. It is elongated 
vertically, is irregularly triangular, and exhibits two faces, two borders, and 
two eatremities. 

Faces.—The external face, which is more convex in the young than the 
old animal, presents: 1, On the level of the fourth and fifth molar teeth, a 
vertically elongated ridge which is continued above with the inferior border 
of the zygomatic bone; this is the supermaaillary spine ; 2, The inferior 
orifice of the supermaaillo-dental canal, or infra-orbital foramen. 

The internal face concurs in forming the external parietes of the 
nasal cavities. We observe, above and in front, a deep, wide, and diverticu- 
lated excavation, forming part of the maxillary sinus; above and behind, a 
surface roughened by fine lamelle and dentations to correspond with the 
palate bone, and traversed from above to below by a fissure which forms, 
in uniting with a similar fissure in the latter bone, the palatine canal. For 
the remainder of its extent it is unequally smooth, covered by the membrane 


THE HEAD. 45 


of the nose, and divided into two surfaces by a slightly vertical and sinuous 
crest that affords attachment to the maxillary turbinated bone: the anterior 
surface, which responds to the middle meatus of the nasal fossa, shows the 
lower orifice of the osseous lachrymal canal continued by a fissure to the lower 
extremity of the bone ; the posterior surface belongs to the inferior meatus. 
This face presents, near its inferior border, a large vertical apophysis, the 
palatine process, which offers an anterior slightly concave face, forming the ° 
floor of the nasal fosse@; a posterior face, furrowed by small fissures, 
perforated by fine openings, and traversed along its length by a somewhat 
wide groove, the palatine fissure, which commences above at the lower orifice 
of the palatine canal. The internal border of this process articulates with 
the analogue of the palatine process of the opposite side. 

Borders.—The anterior, thin and convex, is divided into two parts: an 
inferior, which is mortised to receive the external border of the nasal bone 
and the external process of the premaxillary ; and a superior, cut in a wide 
bevel at the expense of the external plate, to respond to tle lachrymal and 
zygomatic bones. The external border is very thick and hollowed into six 
large quadrilateral cavities, named alveoli, in which are implanted the molar 
teeth. Above the last alveolus it forms a rugged eminence designated the 
alveolar tuberosity ; below the first it becomes thin and sharp, and constitutes 
part of the interdental space which separates the molar from the incisor teeth. 

Extremities —The superior is the thickest, and represents a smooth 
rounded protuberance, into the interior of which the maxillary sinus is 
prolonged. Above and within this eminence, is a wide and deep excavation, 
in the formation of which the palate bones participate. This is the 
maxillary hiatus, situated directly opposite the orbital hiatus. At the 
bottom of this cavity is seen the nasal foramen, as well as the upper orifice 
of the supermaxillo-dental and the palatine canals. The nasal foramen 
belongs to the palate bone and enters the nasal cavity. The super- 
maxillo-dental or infra-orbital canal traverses the maxillary sinus in passing 
above the roots of the molar teeth, and terminates by two branches: one, 
short and wide, which opens on the external surface of the bone, on a 
level with the third molar; the other, very narrow, continues the course of 
the canal in the thickness of the bone, and is prolonged by several small 
very fine branches into the premaxillary bone. The palatine canal, channeled 
between the supermaxillary and the palate bone, extends from the maxillary 
hiatus to the palatine fissure. 

The inferior eatremity presents a cavity which forms the alveolus of the 
tusk by uniting with a similar space in the premaxillary bone. 

Structure and development.—This bone is developed from a single nucleus, 
and is the more spongy, particularly towards the alveolar border and the 
superior extremity, as the animal is young. 


2. Premaxillary, Intermawillary, Anterior Mawillary or Incisive Bone. 


This bone occupies the inferior extremity of the head, and is composed of 
a thick prismatic portion, lengthened superiorly by two long processes. 

Thick portion or base.—This presents a solid mass with three faces: an 
external or labial, smooth and convex; an internal, denticulated for union 
with the opposite bone, and traversed from before to behind by an inflexed 
fissure, which forms, with an analogous one in the other premaxillary, 
the incisive canal or foramen ; the third or posterior, also called the buceal, is 
slighty concave, and shows the continuation of the palatine fissure, which 


46 THE BONES. 


opens into the incisive foramen. These three faces are separated by as 
many borders: two internal, limiting before and behind the corresponding 
face; and an external, separating the labial from the buccal face. The latter 
only merits notice; it is very thick, and is divided into two parts: an 
inferior, which describes a curved line with the concavity upwards, and 
is hollowed by three alveoli to receive the incisor teeth; another, the 
superior, is straight, vertical, and somewhat sharp, and forms a part of 
the dental interspace. It is limited above, near the base of the external 
process, by a cavity for the formation of the alveolus of the tusk. 
Processes.—These are distinguished as ew- 
Fig. 21. ternal and internal. The first, the longest and 
strongest, is flattened on both sides; its ex- 
ternal face is smooth and continued with that 
of the thick portion of the bone; its internal 
face is covered by the mucous membrane of 
the nose; the anterior border is smooth and 
rounded; the posterior, denticulated to re- 
spond to the supermaxillary bone, is in con- 
tact with the external border of the base ; its 
summit is thin, and is insinuated between the 
latter and the nasal bone. The internal pro- 
cess, the smallest, is flattened from before to 
behind, and forms a very thin tongue of bone, 
separated from the other portions by a nar- 
row and very deep notch named the incisive 
opening or cleft. Its inferior face constitutes a 
small portion of the floor of the nasal fosse ; 
the posterior, continuous with the same face 
of the principal mass of the bone, forms part 
of the palatine roof; its external border cir- 
cumscribes, inwardly, the incisive opening ; 
the internal is united by dentated suture with 
the opposite bone. 
Structure and development.—It is a spongy 
bone, developed from a single nucleus. 


3. Palate Bones. 


The palate bones are situated between the 
supermaxillaries, at the margin of the guttural 
opening of the nasal cavities, and are articu- 
POSTERIOR ASPECT or Horsr’s lated with the sphenoid, ethmoid, vomer, 

SKULL, frontal, and pterygoid bones. Elongated from 
1, Occipital protuberance; 2, #bove to below, flattened laterally, and curved 
Foramen magnum; 3, 3, Oc- 
cipital condyles; 4, 4, Styloid processes; 5, 5, Petrous bone; 6, Basilar process; 7, 
Pterygoid fissure of the sphenoid bone; 8, Foramen lacerum; 9, 9, Supra-condyloid, or 
anterior mastoid process; 10, 10, Articular eminence, or temporal condyle; 11, Body ot 
sphenoid bone; 12, Pterygoid process; 13, Ethmoid bone; 14, Temporal bone and sphe- 
noidal suture; 15, Lachrymal bone; 16, Vomer; 17, Malar bofie; 18, Maxillary tube- 
rosity; 19, Posterior, or guttural opening of the nose; 20, Palate bone; 21, Palatine 
styloid process; 22, Palato-maxillary foramen; 23, Palatine process of superior maxil- 
lary bone with suture; 24, Ditto of premaxillary bone; 25, Premaxillary bone; 26, 


Upper incisor teeth; 27, Point of junction of the premaxillary with the superior maxil- 
lary bone; 28, Upper molar teeth—young mouth. 


THE HEAD. 47 


towards each other at their inferior extremity, which is flattened from 
before to behind, these bones, though irregular in shape, offer for study 
two faces, two borders, and two extremities. 

Faces.—The eaternal face of the palate bone is divided into three frac- 
tions, ® superior, or orbital, an inferior, or palatine, and a middle, or articular. 
The first is smooth and slightly excavated, and participates in the forma- 
tion of the maxillary hiatus ; it shows a small fissure, the staphyloid, which 
reaches the palatine fraction in passing between the posterior border of the 
bone and the alveolar tuberosity. The second is not extensive, and looks 
backwards in consequence of the antero-posterior flattening which the bone 
presents at its inferior extremity; it forms part of the roof of the palate. 
The third presents a lamellar and denticulated ‘surface which corresponds to 
a similar face on the supermaxillary bone, and is channeled from above to 
below by the internal fissure of the palatine canal. 

The internal face, smooth and concave, forms part of the external wall 
and the floor of the nasal fossa. 

Borders.—The anterior is indented, near its superior third, by a deep 
notch, which is often converted into a foramen, the nasal. Below this notch 
the bone is thin and denticulated for union with the supermaxillary bone; 
above, its two plates separate widely from one another, giving rise to a 
very spacious cavity which forms part of the sphenoid sinus. The posterior 
border presents, above, a rugged crest called the palatine, flattened from side 
to side, bent outwards, and bordered at its base and inwards by a very 
narrow synarthrodial surface which responds to the pterygoid bone. It is 
smooth and concave in its inferior half, and forms, with that of the opposite 
side, a parabolic arch which circumscribes, below and at the side, the double 
guttural orifice of the nasal cavities. 

Extremities —The superior, flattened on both sides, is bevelled on the 
external side to articulate with the subsphenoidal process. The inferior, 
flattened from before to behind, is curved inwards and united by simple 
suture with that of the opposite bone. 

Structure and development.—This is a very compact bone, developed from 
a single centre of ossification. 


4, Pterygoid Bones 


A small and very narrow bone, elongated from above to below, flattened 
on both sides, and situated on the inner aspect of the subsphenoidal process, 
but external to the vomer. 

Its eaternal face is in contact with the palate and sphenoid bones ; 
the internal is smooth and covered by the pharyngeal mucous membrane. 
Its superior extremity is tapering, and concurs in forming the vidian canal ; 
the inferior is thickened into a small pointed process (the hamular process), 
whose apex, directed backwards, offers outwardly a groove which serves as a 
pulley to the tendon of the tensor palati. This bone is composed entirely 
of compact tissue, and is developed from a single centre of ossification. 


5. Zygomatic Bone. 


This bone, also designated the malar and jugal bone, is elongated from 
above to below, flattened on both sides, and irregularly triangular in shape; 
it is situated on the side of the face, and articulates with the supermaxillary, 


1 This bone is the representative of the internal wing of the pterygoid process in Man, 


48 THE BONES. 


lachrymal, and temporal bones. It is described as having two faces, two 
borders, a base, and a summit. ; 

Faces.—The external face comprises two portions separated from each 
other by a semicircular ledge that extends from the summit to the middle of 
the anterior border of the bone, and concurs to form the outer margin of the 
orbit. The anterior portion, smooth and concave, belongs to the orbital 
cavity. The posterior, more extensive, is also smooth and slightly convex, 
The internal face is excavated in its central part, which corresponds to the 
maxillary sinus. On its margin it shows dentations and lamelle for articu- 
lation with the supermaxillary bone. 

Borders.—The anterior, thin aud denticulated, is joined to the lachrymal 
bone. The posterior, or masseteric border, is thicker, and constitutes a 
roughened crest, the zygomatic ridge, which is continued above with the 
posterior border of the process of the same name, and below with the 
maxillary spine.! 

Base and summit.—The base, very thin, is united to the supermaxillary 
bone. The summit, flattened from before to behind and bevelled on its 
anterior face, joins the zygomatic process, and forms with it the jugal bridge 
or zygomatic arch. 

Structure and development.—This bone is rather spongy in its upper part, 
and is developed from a single nucleus of ossification. 


6. Lachrymal Bone. 


A small, thin, and very light bone, bent on itself at a right angle, it is situ- 
ated beneath the orbit, which it aids in forming, and is wedged between the 
frontal, nasal, supermaxillary, and zygomatic bones. It is studied on its 
external and internal faces and circumference. 

Faces.—The external is divided into two regions, superior and inferior, 
by a curved crest which forms part of the orbital margin, and is provided 
with notches, which are variable in their form and number. The superior 
region, named the orbital, because of its situation in the orbit, is slightly 
concave and smooth. It presents, near the orbital margin, the orifice of the 
lachrymal duct, which traverses the maxillary sinus and opens on the internal 
face of the supermaxillary bone, where it is continued by a fissure ; behind 
this is the lachrymal fossa. The inferior or facial region is slightly bulging, 
and provided sometimes with a tubercle of insertion, the lachrymal tubercle. 
The internal face is employed, for the whole of its extent, in the formation of 
the walls of the maxillary and frontal sinuses; it exhibits a cylindrical 
prominence produced by the bony tube of the lachrymal duct. 

Circumference—This is very irregular and denticulated to respond to 
the neighbouring bones. 

Structure and development.—This bone is entirely compact, and is 
developed from a single nucleus of ossification. 


7. Nasal Bones. 


Situated on the anterior aspect of the head, these bones articulate with 
each other in the median line, and are fixed between the frontal, lachrymal, 
and supermaxillary bones; they are triangular in shape, elongated from 
above to below, flattened from before to behind, and offer for study two faces, 
two borders, a base, and a summit. 


Faces.—The external or anterior face, larger above than below, is convex 


> The designation of zygomatic crest ig often given to these three parts collectively. 


THE HEAD. 


from side to side and almost smooth. The 
posterior, internal, or nasal face exhibits a ver- 
tical crest passing along the external border 
of the bone, which gives attachment to the 
nated portion of the ethmoid; at its supe- 
rior extremity this crest bifurcates, and between 
its two branches shows a concave surface which 
forms part of the frontal sinus. For the 
remainder of its extent the internal face is 
smooth, and covered by the mucous membrane 
of the nasal fossa; it is also excavated into a 
channel to form the superior meatus of this 
cavity. 

Borders.—The external border is very thin 
in its upper two-thirds, and articulates with 
the lachrymal bone, the anterior border of 
the supermaxillary, and the upper extremity 
of the premaxillary bones. In its lower third 
it becomes isolated from the latter bone, in 
forming with the anterior border of its large 
process a very acute re-entering angle whose 
opening looks downwards. The internal border 
s denticulated to correspond with the opposite 

one. 

Base and Summit.—The base occupies the 
superior extremity of the bone; it describes 
a curved line with the convexity above, and in 
uniting on the median line with that of the 
opposite bone, forms a notch similar to that 
of the heart figured on playing cards; it is 
bevelled at the expense of the internal plate to 
articulate with the frontal bone. The summit 
of the two nasal bones, which is pointed, 
constitutes the nasal prolongation: the name 
given to a single triangular process which 
comprises all that portion of the nasal bones 
separated from the premaxillaries by the re- 
entering angle before mentioned. 

Structure and development.-—Almost entirely 
compact in structure, it is developed from a 
single centre. 


8. Turbinated Bones. 


The iturbinated bones, two on each side, 
represent two irregular bony columns, wider 
above than below, compressed laterally, hol- 
lowed internally, and lying vertically side by 
side on the external wall of the nasal fossa, 
which they divide into three meatuses or pas- 
sages. 

They are distinguished into anterior and 
posterior turbinated bones. 

The anterior or superior, also named the 


49 


ANTERO-POSTERIOR AND VERTICAL 
SECTION OF THE HORSE’S HEAD. 

1, Condyloid foramen; 2, Parietal 
protuberance; 3, Internal audi- 
tory hiatus; 4, Cerebral cavity 5 
5, Cerebellar cavity; 6, Supe- 
rior border of the perpendicular 
plate of the ethmoid bone (crista- 
galli process); 7, Ethmoidal 
volutes—nasal face; 8, Vestiges 
of the right frontal sinus, 9, 
Ditto of the sphenoidal sinus; 
10, Pterygoid process; 11, Eth- 
moidal turbinated bone; 12, 
Maxillary turbinated bone; 13, 
Crest of the supermaxillary 
bone to which the latter is fixed ; 
14, Vomer.—a, Orifice of com- 
munication between the nasal 
cavity and the sinus, 


50 
Fig. 23. 


LONGITUDINAL AND TRANSVERSE SEC™ 
TION OF THE HORSE’S HEAD, SHOW- 
ING THE FLOOR OF THE CRANIAL 


AND NASAL CAVITIES, WITH THE 
MAXILLARY SINUSES. 

Condyloid foramen; 2, Section of the 
parieto-temporal canal; 3, Occipito- 
spheno-temporal hiatus; 4, Carotid 
notch; 4’, Maxillary  notch.—«, 
Supermaxillary fissure; 6, Cavernous 
fissure; 5, Origin of the supersphe- 
noidal canals.—c, Sella turcica; 6, 
Optic fossa; 7, Portion of the 
crista-galli process; 8, Cribriform 
plate of the ethmoid bone; 9, Per- 
pendicular plate of the same bone; 
10, 10, Its lateral masses; 11, Inte- 
rior of the great ethmoidal cell; 12, 


12, Bottom of the maxillary sinuses communicating with the sphenoidal sinuses; 13, 


THE BONES. 


ethmoidal, is formed by a very thin plate 
of compact tissue, fragile and like papyrus, 
fixed by its anterior border to the internal 
crest of the nasal bone, and rolled on 
itself, from befvre to behind, in the same 
manner as the cells of the ethmoid bone, 
Above, it is confounded with the last- 
named bone, of which it is only, properly 
speaking, the most anterior volute. At its 
inferior extremity, it is prolonged by a 
fibro-cartilaginous framework to the ex- 
ternal orifice of the nose. 

Its internal cavity is partitioned by a 
transverse plate into two portions: the 
superior compartment forms part of the 
frontal sinus; the inferior is subdivided by 
other small lamelle into a variable number 
of cells which communicate with the nasal 
cavity. This bone, developed from a 
single nucleus, is ossified at the same time, 
and in the same manner, as the ethmoidal 
cells. Before birth, it is already intimately 
consolidated with the nasal bone. 

The posterior, inferior, or mazillary 
turbinated bone resembles the first, except 
in some particulars. Thus, its bony or 
proper portion is not so long or volu- 
minous, while its cartilaginous part is, on 
the contrary, more developed. It is at- 
tached, by its posterior border, to the ver- 
tical and sinuous crest of the super- 
maxillary bone, and is rolled from behind 
to before, or in an inverse direction to the 
other. It has no connection with the 
ethmoid, and its superior cavity forms 
part of the inferior maxillary sinus. It 
is late in becoming ossified, and is scarcely 
united in a definife manner to the max- 
rik bone until the horse is about a year 
old. ; 

The meatuses are distinguished into 
anterior or superior, middle, and posterior 
or inferior, The first passes along the 
front of the ethmoidal turbinated bone; 
the second separates the two turbinated 
bones, and presents, near its superior 
extremity, the opening communicating 
between the sinuses and the nasal cavi- 


Supe- 


rior maxillary sinus; 14, Inferior maxillary sinus; 14’, Superior compartment of the max- 
illary turbinated bone, forming part of the latter sinus; 15, Section of the supermaxillo- 
dental canal; 16, Channel of the vomer; 17, Internal process, or point of the premax- 


illary bone, 


THE HEAD. 51 


ties.) The third is situated behind the maxillar i 
is confounded with the floor of the nasal fossa. epee eee 
The turbinated bones are essentially destined to furnish the membrane 
of the nose with a vast surface of development. This membrane, indecd 
covers their entire superficies, and even penetrates the anfractuous cells of 
their lower compartment. 
9. Vomer. 


; This, a single bone, elongated from above to below, flattened on both 
sides, and extending on the median line from the body of the sphenoid to 
the premaxillary bone, offers for study two lateral faces, two borders, and 
two extremities. 

The faces are smooth, plane, and covered by the nasal membrane. The 
anterior border is channeled for the whole of its length by a deep groove 
which receives the posterior border of the cartilaginous septum of the 
nose. The posterior border is sharp and smooth in its upper half, which 
separates the two guttural openings of the nasal cavities: it is thick and 
slightly denticulated for the remainder of its extent, and rests on the 
median suture resulting from the union of the two supermaxillary bones. 
The superior extremity is provided, in its middle, with a notch which divides 
it into two lateral prolongations shaped like a cat’s ears; it articulates 
with the inferior sphenoid, ethmoid, palate, and pterygoid bones. The 
inferior extremity rests on the prolongations of the incisive bones. 

This bone is entirely compact, and is developed from one centre of 
ossification. 

10. Inferior Maxillary Bone. 

The mazillary bone is not consolidated with any of the preceding bones, 
and is only united to two of them, the temporals, by diarthrodial articula- 
tion. It is a considerable bone, situated behind the upper jaw, and composed 
of two symmetrical branches, which are flattened on both sides, wider 
above than below, curved férwards in their upper third, joined at their lower 
extremities, and separated superiorly so as to leave a wide gap between 
them, like the letter V in shape, called the intramasillary space. Each 
offers for study two faces, two borders, and two extremities. 

Faces.—The external face of the maxillary branches is smooth and 
rounded in its inferior two-thirds, and transformed superiorly into a 
rugged surface, in which is implanted the fibres of the masseter muscle, 
The internal face presents, in the corresponding point, an excavated surface 
on which is remarked the superior orifice of the mawillo-dental canal, a long 
channel which descends between the two plates of the branch, passing under 
the roots of the molar teeth, and insensibly disappearing in the body of the 
bone after being widely opened externally by the mental (or anterior masillary) 
foramen. In its inferior two-thirds, the internal face is smooth, nearly 
plane, and shows nothing very remarkable. Near the alveolar border there 
is a slightly-projecting line—the myloid ridge ; and quite below, or rather 
at the very summit of the re-entering angle formed by the separation of 
the branches, there is a slight rugged ee confounded with that of the 

i ch, and named the genial surface. 
ne anterior, ma named the alveolar border, exhibits for 
study a straight or inferior, and a curved or superior portion. The first is 
hollowed by six alveoli to receive the inferior molar teeth. 

1 The two turbinated bones, in being applied against the excavation on the inner 
face of the supermaxillary, almost entirely close it, only leaving between them a vertical 
slit which constitutes the opening mentioned above. 


52 THE BONES. 


The second, thinner, concave, and rugged, serves for muscular insertion. 
The posterior border is also divided into straight and curved portions. The 
latter is convex, thick, rugged, and margined on each side by an uneven 
lip; the first is regularly rectilincar, so that all its points rest at the same 
time on a horizontal plane; it is thick and rounded in the young animal, 
but becomes sharp with age; an oblique and transverse fissure—the mawillary 
—separates it from the curved part. ‘The union of these two portions forms 
the angle of the jaw. : 

Extremities—The superior extremity has two eminences: a condyle, 
and a long non-articular process named the coronoid process. The condyle is 
elongated transversely, and convex in its two diameters; it responds, through 
the medium of a fibro-cartilaginous dise, to the articular surface of the zygo- 
matic process. The coronoid process is situated in front of the condyle, from 
which it is separated by a division called the sigmoid or corono-condyloid notch ; 
it is fattened on both sides, and curved backwards and slightly inwards. 


Fig. 24, 


INFERIOR MAXILLA. 


1, Mental foramen; 1’, Superior orifice of the maxillo-dental canal; 2, Surtace ot 
implantation for the masseter muscle; 3, Myloid ridge, 4, Coronoid process; 
5, Condyle. 


From tke union of the branches of the maxillary bone at their inferior 
extremity results a single piece, flattened before and behind, and widened 
like a spatula, which has been designated the body of the bone. This merits 
a special description. 

Its form allows us to divide it into an anterior or buccal face, a posterior 
or labial face, and a circumference. The anterior face is smooth and concave, 
is lined by the buccal mucous membrane, and supports the free extremity 
of the tongue. The posterior face is convex, more extensive than the 
preceding, and continuous with the external face of the branches; it presents: 
1, On the median line, a slight crest or small groove, traces of its being 
originally separated into two pieces; 2, On the sides and above, the mental 
foramen, the inferior orifice of the maxillo-dental canal. On a level with 
this foramen, the bone very markedly contracts to form the neck. The 
circumference describes a parabolic curve, the concavity being uppermost, 
and joins, by its extremities, the anterior border of each branch. It is 
excavated in its middle part by the six alveoli for the lodgmen* of the 


THE HEAD. 53 


inferior incisors, and behind these, in male animals only, there i 
additional alveolus for the tusk. The portion included on soak side borers 
the last incisor and first molar, forms a more or less sharp ridge, which 
constitutes the inferior interdental space or bars. : 

Structure and development.—Formed, like all the flat bones, by two 
compact plates separated by spongy tissue, the inferior maxilla is developed 
from two centres of ossification, which correspond to each branch, and which 
coalesce some time after birth. : 


11.—The Hyoid Bone. 


The hyotd bone constitutes a small and special bony apparatus which 
serves to support the tongue, as well as the larynx and pharynx; its 
description is placed immediately after that of the bones of the head 
because of its connection with that region, it being situated between the two 
branches of the supermaxillary bone, and suspended to the base of the cra- 
nium in an oblique direction from above to below, and from before to behind. 

This apparatus is composed of seven distinct pieces, arranged in three 
series: a middle, constituted by a single bone, and named the body; two 
lateral, forming two quasi-parallel branches, to the extremities of which the 
body is articulated. 

Body.—The body of the hyoid resembles a fork with two prongs. It 
presents: 1, A middle part flattened above and below, and consequently pro- 
vided with a superior and an 
inferior face ; 2, A single and 
long prolongation flattened 
on both sides, which is de- 
tached from the middle part, 
and directed forward and 
downward to plunge into the 
muscular tissue of the 
tongue: this is the anterior pate are 
app endia of the hyoideal body 3 1, 1, Superior extremity of the styloid bones, 2, Angle 
3, Two lateral cornua, thyroid described by their posterior border; 3, 3, Styloid 
cornua, or great cornua, pro- bones; 4, 4, Extremities of the thyroid cornua; 5, 
jecting backwards and up- Articular surface of the body corresponding with the 
wards, articulating by their — $73/!_ Pranches; 6 Se ee ee 
extremities with the thyroid a Sa Ce asta a 
cartilage of the larynx, and offering, at their point of union with the 
middle part, two convex diarthrodial facets looking upwards, and corre- 
sponding with the styloid cornua. The body of the hyoid bone is developed 
by three centres of ossification, a middle, and two lateral for the cornua. 

Branches.—The three pieces composing these are articulated end to 
end, by means of a cartilaginous substance that joins them together; they 
are of very unequal dimensions. The first, which is in relation with the 
body, is of medium size, and is named the styloid cornu, small cornu, or small 
branch. The second, termed the stylotd nucleus, is the smallest. The third, 
the largest, constitutes the styloid process, or bone, or great branch. 

1. The styloid cornu is a small cylindrical piece bearing a concave 
diarthrodial surface on its inferior extremity to unite it to the body ; it is 
very spongy, and is developed from two ossifying centres, one of which, the 
epiphysary, is for the inferior extremity. a: : = 

2. The styloid nucleus, which is often absent, is imbedded in the uniting 
cartilaginous substance. 


Fig. 25, 


St THE BONES. 


3. The styloid bone, or great hyoideal branch, is long, thin, flattened 
on both sides, and directed obliquely from above to below, and before to 
behind ; it presents two faces, two borders, and two extremities. The faces 
—an external and internal—are marked by some few imprints. The 
anterior border is sharp and slightly concave in its upper third. The 
posterior border is thicker, and is divided into two portions: a superior or 
horizontal, which is very short, and an inferior or vertical, much more 
extensive. The angle they form at their point of junction presents a 
salient, and more or less roughened, tuberosity. The superior extremity is 
united to the hyoideal prolongation of the temporal bone by means of a 
cylindrical fibro-cartilage. By its inferior extremity, the styloid bone is 
united either to the styloid nucleus or the styloid cornu, forming a sharp 
elbow directed forwards. The. styloid bone, developed from a single 
centre of ossification, is almost entirely formed of compact tissue. 


OF THE HEAD IN GENERAL. 


From the union of all the bones which constitute the cranium and face 
results a quadrangular pyramid, whose summit is inverted, which it is 
necessary to study as a whole. We will pass in review, successively, its 
four faces, its base, and its summit. 

Anterior Face.—The anterior aspect of the head has the parietal, frontal, 
and nasal bones for its base. Superiorly, it inclines backwards and. offers, 
on each side of the parietal ridges, two bulging surfaces which form part 
of the temporal fosse. For the remainder of its extent, it presents a plane 
surface which forms the base of the forehead and the middle portion of 
the face. Wide above, this surface gradually tapers to the extremity of the 
nasal spine. In well-formed animals, it is as straight and wide as possible. 

Posterior Face.-—This face, which is extremely irregular, presents : 
above, the basilar process, the lacerated foramina, and the base of the 
tuberous portion of the temporal bones; then the intramaxillary space, 
and, at the bottom of this, the body of the sphenoid bone, vidian fissure, 
superior orifice of the subsphenoidal canal, sphenoidal process, palatine 
ridges, pterygoid bones, guttural openings of the nasal cavities separated 
from one another by the posterior border of the vomer, roof of the palate, 
incisive openings, and the incisive foramen. 

Lateral Faces.—These exhibit : behind, the external face of the maxillary 
branches ; before, a surface more or less convex, though sometimes hollow 
in old animals, presenting at its middle the inferior orifice of the maxillo- 
dental canal, and forming the base of the lateral parts of the face; above, 
the zygomatic ridge and arch, the orbit, and the temporal fossa. These 
two cavities, in the formation of which many bones participate, have been 
hitherto merely indicated ; this is the place for giving them a more detailed 
description. 

_ The orbit or orbital cavity is irregularly circular in outline, and 
circumscribed by the orbital process of the frontal bone, the lachrymal and 
malar bones, and the summit of the zygomatic process. At the bottom, 
which shows the maxillary and orbital hiatus, it is confounded, in the 
skeleton, with the temporal fossa.' It lodges the globe of the eye and 
the muscles which move it. Some organs, accessory to the visual apparatus, 


1 A fibrous membrane, the ocular sheath, isolates it from the temporal fossa in the 
majority of mammiferous animals. Only in Man and the quadrumana has the orbital 
cavity complete bony walls. ‘ 


THE HEAD, 55 


such as the ]: icti 
oe a gland and the membrana nictitans, are also contained 
The temporal fossa surmounts the orbit, and is i 
from it by the orbital arch (or process). Oval = shapes Tyee te ey an 
above to below, and from within outwards, on the sides of the fe eae 
temporal fossa is limited, within, by the parietal ridge, and o vi gant c 
the anterior border of the longitudinal root of the z 0 ti abo s 
toler the temporal muscle. : Peeruan eae ee 
ase or superior extremity of the head.—This pre: ipi 
tuberance, cervical tuberosity, occipital foramen, menos ie eae a 
- styloid processes of the occipital bone, stylo-condyloid notches, and the aoe 
dyles. Ona lower plane, and behind, the curved portion of "the osteri 
border of the maxillary bone is remarked. cea 


Summit.—Formed by the premaxillary bones and the body of the super- 
Fig. 26, 


LATERAL VIEW OF THE HORSE’S SKULL. 

1, Premaxillary bone; 2, Upper incisors; 3, Upper canine teeth; 4, Superior 
maxillary bone; 5, Infraorbital foramen; 6, Superior maxillary spine; 7, Nasal 
bones; 8, Lachrymal bone; 9, Orbital cavity ; 10, Lachrymal fossa; 11, Malar 
bone; 12, Upper molar teeth; 13, Frontal bone, 15, Zygomatic process, or arch; 

16, Parietal bone; 17, Occipital protuberance; 18, Occipital crest; 19, Occipital 
condyles; 20, Styloid processes; 21, Petrous bone; 22, Basilar process; 23, 
Condyle of inferior maxilla; 24, Parietal crest ; 25, Inferior maxilla; 26, Inferior 
molars; 27, Anterior maxillary foramen; 28, Inferior canine teeth; 29, Inferior 
incisor teeth. 
maxilla, the summit supports the incisor teeth, and presents a tuberosity 
more or less rounded, according to the age of the animal. In front, it is 
surmounted by the external opening of the nasal cavities; this opening, 
which is comprised between the external process of the premaxillary bones 
and the nasal spine, is divided in the fresh state into two orifices which 
constitute the nostrils. ; : 

Internally, the head contains the nasal fosse and the cranial cavity. 

These will be described when the apparatus belonging to them is noticed. 
(See the respiratory and nervous apparatus). 
DIFFERENTIAL CHARACTERS OF THE HEAD IN OTHER THAN SOLIPED ANIMALS. 


A. Heap or THE Ox, SHEEP, AND GoAT.—l. Ocetpital bone.—The occipital bone in 
these animals docs not show any anterior elbow. The cervical tuberosity, or occipital 


56 THE BONES. 


i i i i the superior curved lines; in the 
tuberance is obtuse, and gives rise on each side to : 
Bheep slice curved lines are very salient and occupy the summit of the head. oi 
The styloid processes are short and much bent inwards. The basilar process, wide, 
short, and Thick has a groove in the middle of its external face ; this groove is sometimes 
it in the Sheep and Goat. 
ae cone ean are double, sometimes triple; the superior foramen does not 
ass directly into the cranium, but goes to a vast conduit that opens behind on the lateral 
Le in of the occipital foramen, and which terminates in front by two orifices, one 
calgae the parieto-temporal canal, the other opening on the external surface of the 
bone. The foramen lacerum is divided into an anterior and posterior foramen by the 
ol ‘tion of the temporal bone. ; 
Ee kee parietal bone in the Ox does not occupy the anterior aspect 


Fig. 27. 


= 
Ss al | 
GA E \ 


NU 
| yi 
\ WN ae 


| i 
i 


Ox’s HEAD; ANTERIOR FACE. 
1, Mastoid process; 2, Superciliary, or supra-orbital foramen; 3, Zygoma; 4, 
Lachrymal bone; 5, Maxillary spines 6, Inferior orifice of the supermaxillo-dental 
canal. 


of the head, but concurs with the occipital to form the base of the neck. It represents a 
very narrow osseous plate, elongated transversely, and curved at its two extremities, 
-which descends into the temporal fosse to rest upon the sphenoid bone. There are no 
parietal ridges. The internal protuberance is only marked by a slight elevation of the 
internal plate ; for the most part it belongs to the occipital bone. 

The parietal bone of the Ox is developed from three centres of ossification, and the 
middle nucleus is even primerily divided into lateral halves ; but these centres are 
consolidated with each other at an early period, as well as with the anterior portion of 
the occipital. It does not aid in the formation of the parieto-temporal canal, and is 
excavated internally by cavities which communicate with the frontal sinuses, 

__ The parietal bone of the Sheep and Goat is relatively much larger than that of the Ox. 
It participates in the formation of the parieto-temporal canal, and has no sinuses. 

3. Frontal bone.—In ruminants, the frontal bone does not respond to the temporal 

and palate bones. 


Inthe Ox, this bone is extremely developed, by itself occupying the anterior half of the 


THE HEAD, 57 


face. It is particularly distinguished by:—1, Its great thickness. 2, The osseous 
conical cores which support the horns. These eminences, more or less loug and curved, 
very rugged, perforated by foramina, and grooved by small vascular channels, are 

® detached outwards from each side of the bone, near the summit of the head. The 
processes which form the orbital arches rest by their summits on the zygomatic bone. 
‘The supra-orbital foramen is transformed into a veritable and frequently multiple canal; 
its anterior orifice opens into a vasculo-nervous groove, which ascends towards the base 
of the horns, and descends to near the lower border of the bone. Between this groove 
and the base of the orbital arch is the frontal boss. The orbital foramen entirely belongs 
to this bone. The inferior border is deeply notched in its middle to receive the nasal 
bones, the frontal sinuses are prolunged into the horn-cores, the parietal bone, and even 
into the occipital bone. 

In the Sheep and Goat, the frontal bone is relatively less extensive and strong than in 
the Ox; it does not ascend to the summit of the head, and the frontal sinuses are not 
prolonged beyond its superior border. 

4, Kthmoid bone.—In ruminants, 
the great ethmoidal cell is enor- Fig. 28, 
mously developed, and looks like a 
third turbinated bone prolonged be- 
tween the usual two; it has been 
named the olfactory antrum. 

The ethmoid bone is closely im- 
prisoned between the adjacent bones, 
in consequence of the slight develop- 
ment of the sinuses around it. This 
character otherwise belongs to all 
the domesticated animals, except soli- 
peds. 

5. Sphenoid bone.—In the Oz, 
the subsphenoidal or pterygoid pro- 
cesses are large and thin. The sub- 
sphenoidal canal is absent. The 
sella turcica is deep, and the bony 
projection separating it from the 
basilar process is very high. The 
three suprasphenoidal canals are 
converted into a single, but wide 
one. There are no notches in the 
superior border for the passage of 
the internal carotid and spheno- 
spinous arteries, That for the in- 
ferior maxillary nerve is converted 
into a canal—the oval foramen. 

In the Sheep, the osseous promi- 
nence that limits the pituitary fossa 
posteriorly forms a lamina cury- 
ing forwards and prolonged at its ex- 
tremities into two points, which 
constitute the posterior elinoid pro- 
cesses. 


6. Temporal bone—In the Oz, RAM’S HEAD; ANTERIOR FACE. 
Sheep, and Goat,the tuberous portion 4, Occipital bone; 2, Parietal bone; 3, Core of right 
of the temporal bone is always con- _—fyontal bone; 4, The left core covered by its horn; 


solidated with thesquamous portion, 5, Superciliary foramen; 5’, Channel descending 
and the summit of the zygomatic from it; 6, Lachrymal bone; 7, Zygoma; 8, Nasal 
process only articulates with the bone; 9, Supermaxillary bone; 10, Premaxillary 
malar bone. bone; 10’, Its internal process; 11, Incisive open- 
In the Ox, the condyle of the img. 
zygomatic process is very wide and j ; 
convex in every sense. The parieto-temporal canal is very large and entirely excavated 
in the temporal bone; its superior or internal extremity opens above the petrous portion 
in an excavation which represents the lateral cavity of the parietal protuberance in the 
Horse: at its inferior extremity it always shows several orifices. ° 
The mastoid process is very salient, and belongs to the squamous portion. The 
mastoid crest is confounded with the upper root of the zygomatic process; inferiorly, it 


58 THE BONES. 


th toid process, and is prolonged to the mastoid protuberance. The latter 
a ee ctlviainees The salalifeutd prooond is larger and stronger than in the Horse; 


i stoid fissure. 2 Fis ' 
eae en ned Goat, the mastoid process is scarcely distinct from the crest; and 


the mastoid portion of the bone is only at a late period consolidated with the petrous 
portion. : 


Ox’s HEAD; POSTERIOR FACE. 

A, Parietal bone.—1, Occipital foramen; 2, Occipital condyle; 3, Styloid process 
of that bone; 4, Condyloid foramina; 5, Mastoid process; 6, Mastoid protuber- 
ance; 7, Subuliform (temporal) process; 8, Hyoideal sheath; 9, Stylo-mastoid 
foramen; 10, External auditory hiatus; 11, Inferior orifice of the parieto-tem- 
poral canal; 12, Temporal condyle; 13, Posterior foramen lacerum; 14, Oval 
foramen; 17, Subsphenoidal process; 18, Orbital hiatus; 19, Optic foramen.— 
B, Frontal bone.—20, Superciliary foramen; 21, Orbital foramen; 22, Lachrymal 
protuberance.—c, Zygoma.—23, Pterygoid bone.—p, Palate bone.—24, Nasal fora- 
men; 25, Inferior orifice of the palatine canal.—r, Supermaxillary bone.—26, 
Maxillary spine-—G, Premaxillary bone.—27, Its internal process; 28, External 
process; 29, Incisive openings. 


7. Supermaxillary bone.—In the Ox, Sheep, and Goat, the maxillary spine does not 
directly join the zygomatic crest a curved line, whose concavity is posterior, effects the 
union between these two parts. The inferior orifice of the supermaxillo-dental canal 
or infraorbital foramen is pierced above the first molar tooth. There is no fissure for 
the formation of the palatine canal. The cavity of the sinus is more spacious than in 
the Horse, and is prolonged (in the Ox only) between the two laming of the palatine 
roof. There is no alveolus for the tusk. 


8. Premaxillary bone—The inferior or principal portion of this bone is flattened before 


THE HEAD, 


and behind. and deprived of aveoli in its external 
border; neither is there any incisive foramen. 
It is rarely consolidated with the adjacent bones, 
and is never, in the smaller ruminants, articu- 
lated with the nasal bone. 

9. Palate bone.—This bone is very developed 
in the Ox, and noticeable tor the considerable 
extent of the palatine portion of its external sur- 
face. The palatine canal is entirely channeled 
out in its substunce. The palatine crest, very 
thin and elevated, is formed altogether by the 
posterior border of the palate bone, the ptery- 
goid, and the subsphenoidal process. There is 
no excavation for the sphenoidal sinuses; but, 
instead, all that part of the bone which enters 
into the roof of the palate is hollowed by irre- 
gular cavities which communicate with the max- 
illary sinus of the same side, The nasal foramen 
is very wide. In the Sheep and Goat, the maxil- 
lary sinuses do not extend to them. 

10. Pterygoid bone.—The pterygoid of the Ow, 
Sheep, and Gvat is very large, and closes an aper- 
ture left between tle sphenoid and pilate bones. 

1l. Zygoma.—The jugal bone of Ruminants is 
very developed. The zygomatic crest is no 
longer formed by the posterior border of the bone, 
but is carried to the posterior part of the external 
face, and runs parallel with the eyebrow. The 
summit is bifurcated, the anterior branch form- 
ing a buttress against the summit of the orbital 
process of the frontal bone, while the posterior 
articulates with the temporal. 

12. Lachrymal bone—The lachrymal bone, 
much more extensive than that of the Horse, forms 
in the bottom of the orbit an enormous protube- 
rance, hollowed internally by the maxillary sinus, 
and whose walls are so thin and fragile that the 
slightest jar is sufficient to cause their fracture 
(in the skeleton). It would be convenient to 
designate it the lachrymal protuberance.’ In the 
smaller ruminants, the inferior region of the exter- 
nal face shows a depression, the lachrymal fossa. 

13. Nasal bones—Thbe nasal bones of the. Ox 
are never consolidated with each other, nor yet 
with the neighbouring bones. The external border 
only comes in contact to a small extent with the 
supermaxillary bone; the superior extremity is 
fixed in the notch of the inferior border of the 
frontal bone. At their inferior extremity, they 
each present a notch which divides them into two 
points. 

In the Sheep and Goat the nasal spine is 
unifid, as in the Horse. 

14, Turbinated bones.—In the Oz, the eth- 
moidal turbinated bone is very small, and united 
to the nasal bone by the two borders of its osseous 
plate; its internal cavity entirely belongs to the 
frontal sinus. The maxillary turbinated bone is 
very developed, and is joined to the bone which 
sustains it at a later period than in the Horse. 
The bony lamina of which it is composed is curved 


1 Girard, who named this eminence the orbital 
protuberance. wrongly described it as belonging 
to the supermaxillary bone. 


5) 


—— Z 


MEDIAN AND VERTICAL SECTION OF 
THE OX’S HEAD. 

1, Condyloid foramen; 1', Posterior ori- 
fice of the occipital lateral canal 
joining the parieto-temporal canal 
in front; 2, Internal auditory hiatus; 
3, Anterior foramen lacerum; 4, Pos- 
terior ditto; 5, Intra-cranial orifice 
of the parieto-temporal canal; 6, 6, 
Median bony plate separating the 
frontal sinuses; 7, Lamina which iso- 
lates the sphenoidal sinus; 8, Lamina 
partitioning the palatine portion of 
the maxillary sinuses, 9, Oval fora- 
men; 10, Optic fossa; 11, Vomer; 
12, Pterygoid bone; 13, Large open- 
ing leading into the maxillary sinus, 
and which, in the fresh state, is closed 
by the pituitary membrane; 14, Max- 
illary turbinated bone, 15, Ethmoidal 
turbinated bone; 16, Great ethmoidil 
cell. 


60 THE BONES. 

on itself in two different directions: from before to behind by its posterior border, and 
behind to before by its anterior border. It is fixed to the supermaxillary bone by its 
middle part, through the medium of a particular bony lamina, and it very incompletely 
closes the excavation which concurs to form the maxillary sinus. In the skeleton 
there is also’found behind, und at the base of this turbinated bone, a vast opening which 
is totally closed in tlie fresh condition by the pituitary membrane. The maxillary sinus 
is not prolonged in its interior. In the smaller ruminants, the cavity of the sinus is 
clused by the maxillary turbinated bone in a more complete manner than in the Ox. 

15. Vomer.—This is a very large thin bone, resting only on the inferior half of the 

i he premaxillaries. 

Tener eee 16. Premawillary bone.—In the Oz, the inferior part of the 
posterior border is convex, and cannot rest on a horizontal 
plane by all its points at the same time. The condyle is 
convex in its small diameter, and slightly concave laterally. 
The coronoid process is bent backwards and outwards. The 
body does not show any alveolus for the tusk, because this 
tooth is absent in these animals; but it is hollowed by eight 
alveoli for the incisor teeth. The two branches of the bone 
are never consolidated, but remain movable on each other 
during life. 

17. Hyoid bone—The hyoid bone of Ruminants is always 
composed of seven pieces; the styloid nucleus, whose presence 
is not constant in solipeds, is never absent in these, and 
assumes the proportions of a second small branch. The 
anterior appendix is very short and thick. 

B, Heap or rue Pic.—l. Occipital bone—The occipital 
bone in this animal is not bent anteriorly; but the transverse 
protuberance representing the curved lines forms, nevertheless, 
as in the Horse, the summit of the head. This eminence, which 
is excavated on both sides on the posterior face, unites in front 
with the parietal bone, which abuts on the occipital at an 
acute angle. There is no external occipital protuberance, 
properly speaking, and the styloid processes are very long and 
directed downwards. 

2, Parietal bone.—This bone is very thick, and deprived 
of an internal protuberance. The process concurring to cir- 
cumscribe the orbit is short, and joins neither the zygomatic 
or temporal bones; the orbital arch is completed by a liga- 
ment. The superciliary foramen, disposed as in the Ox, opens 
in front into a channel that descends to the nasal bones. The 
orbital foramen is formed by the frontal bone only. There 
is no mortice for the union of the frontal with the sphenoid 
bone, and the maxillary sinus is prolonged into the parictal 
bone. The frontal bone of the pig articulates with the super- 
maxillaries, 

3. Frontal bone—The frontal bone of the Pig is very thick 


Fig. 31. 


HEAD OF THE PIG35 
ANTERIOR FACE. 


1, Summit of occipital pro- 


tuberance; 2, Parietal 
bone; 3, Frontal bone. 
—A, Superciliary fora- 
men; A’ Channel des- 
cending from it.—4, 
Zygomatic process; 5, 
Zygoma; 6, Lachrymal 
bone.—B, — Lachrymal 
canals.—7, Supermax- 
illary bone.—c, Inferior 
orifice of the supermax- 
illo-dental canal; 8, 
Nasal bone; 9, Pre- 
maxillary bone. 


and short, and does not join the t-mporal or zygomatic bone ; 
the orbital arch is completed bya ligament. The superciliary 
foramen, disposed as in the Ox, abuts in a channel that 
descends on the nasal bones. ‘The orbital foramen is formed 
by the frontal bone only. There is no mortice for the union of 
the frontal with the sphenoid bone ; and the frontal sinuses are 
prolonged into the parietal. The frontal bone of the Pig 
articulates with the supermaxillaries. 

4. Sphenoid bone.—The sphenvid of the Pig is very short, but 
the subsphenoidal processes are extraordinarily developed and 
flattened before and behind. There is no subsphenoidal canal, 
and the sella tureica is deep, and limited behind by a very salient 
crest. A single canal replaces the foramen rotundum and the 
great sphenoidal fissure, as in the Ox. The wings, slightly 
salient, are articulated by suture with the frontal bone. 


5. Temporal bone.—The articular surface of this bone resembles that of rodents ; it is 
not limited posteriorly by a subcondyloid eminence, and, in addition, offers a wider 


transverse surface. 


; _ The zygomatic process articulates with the jugal bone by the whole 
extent of its posterior border. A crest leading 


from the external auditory hiatus to the 


THE HEAD, 


mastuid protuberance replaces the mastoid process. 


confounded with the superior root of the zygomatic p 
The projcction formed by the mastoid protuberance is enormous. 


61 


The mastoid crest is, as in the Ox, 


rocess, 


The subuliform 


process is little marked, and there is no hyoideal prolongation or parieto-temporal canal. 


6. Supermaxillary bone—In the Pig, the ex- 
ternal surface of this bone is hollowed in its middle, 
and presents in front a voluminous relief formed 
by the alveolus of the canine tooth. ‘The cavity 
is entirely formed in the supermaxilla. ‘here is 
no alveolar tuberosity, and the interdental space 
is very short, while the cavity for the sinus is little 
developed. ‘The lower orifice of the palatine canal 
is even pierced in the substance of the super- 
maxilla. 

7. Premaxillary bone—The external process of 
the premaxillary bone is very long and wide at its 
base, and consolidated with the nasal bone for 
about the upper two-thirds of its length. ‘There 
is no incisive foramen or cavity for the tusk. ‘The 
incisive openings are oval. 

8. Palate bone —The palatine portion of the ex- 
ternal face is more developed than in the Ox, but 
the orbital portion is ‘very limited. The palatine 
crest is rvplaced by a tuberosity, against which 
rests, outwardly, the subsphenoidal process, and 
inwardly, the pterygoid bone. The union of these 
three parts constitutes, on the posterior surface of 
the head, a thick and very remarkable trifid pro- 
jection or mamelon. 

9. Pterygoid bone—Sce the description of the 
palate bone. 

10. Zygomatic bone-—The summit of this bone 
in the Pig is flattened on each side, and divided 
into two bianches, between which is wedged the 
summit of the zygomatic process; the anterior 
branch is very short, and does not join the frontal 
bone. 

11. Lachrymal bone.—In the Pig there are ob- 
served a lachrymal fossa and two lachrymal canals, 
which are pierced outside the orbital cavity, and 
soon coalesce in the substance of the bone to consti- 
tute a single canal. The fossa is very deep. 

12. Nasal bones.— These bones are long and nar- 
row, and traversed on their external face by the 
fissure that descends from the superciliary foramen. 
The nasal prolongation is short. 

13. Turbinated bones——The same arrangement 
as in the Sheep and Goat, except that they are 
much longer and less fragile. 

14. Inferior Mazilla.—A straight line leading 
from the greater axis of the alveoli of the molar would 
not traverse the posterior border of the maxillary 
branches; the bottom of these alveoli corresponds 
to the relief on the inner face. The condyle is 
compressed on both sides, and elongated from before 
to behind ; while the coronoid prucess is short and 
wide. There igs no neck; the interdental spaces 
are very short; and the maxillo-dental canal opens 
inferiorly by multiple orifices. : P 

15. Hyoid bone.—The body is voluminous and 
deprived of an appendix; the small branches are 


Fig. 32. 


HEAD OF THE PIG; POSTERIOR FACE 
1, Occipital protuberance; 2, Occi- 
pital foramen; 3, Occipital con- 
dyle; 4, Condyloid foramen; 5, 
Basilar process ; 6, 6, Mastoid crest; 
7, Styloid process of the occipital 
bone; 8, Articular surface of the 
temporal bone; 9, Mastoid protu- 
berance; 10, Foramen lacerum; 11, 
Subsphenoidal process — external 
wing of pterygoid process; 12, 
Palatine crest; 13, Pterygoid bone 
internal wing of the pterygoid 
process; 14, Inferior orifice of the 
palatine canal; 15, 15, Incisive 
openings. 


short and consolidated with the body; while the large branches, curved like an S, are very 
thin, and are united to the small branches and the temporal bone no longer by fibro- 


cartilage, but by veritable yellow elastic ligaments, 


C. Heap or Carnivora.—l, Occipital bone-—The eminence which constitutes the 


62 THE BONES. 


origin of the superior curved lines is very elevated and strong. The cervical tuberosity 
of the external occipital protuberance is absent or little marked ; the styloid processes 
are short, and well deserve the name of jugular eminences. The foramen lacerum is 
divided into two portions by the mastoid protuberance, and the basilar process is wide, 
long, and thick, and hollowed on the side by a channel that joins a similar one in the 
temporal bone to form a large venous canal. This last communicates, behind, with the 
posterior foramen lacerum, and opens, in front, in the cranium, where it is continuous 
with the cavernous groove of the sphenoid. The anterior angle forms a very marked 
prominence, which is deeply fixed into the parictal bone, and partly constitutes the 
internal protuberance of that bone. f 

2. Parietal bone.—In the Dog the parietal bone, formed by two ossific centres only, 
is distinguished by the great development of the ridges and the parietal protuberance. 
This last, constituted in part by the occipital bone, does not show any lateral excavations 
at its base; they are carried lower, near the summit of the petrous process, on the 
sides of the occipital bone. The parieto-temporal canals are continued, notwithstanding, 

to the base of the protuberance, which they traverse, to 
Fig. 33. open into each other in its interior. 

In the Cat there are scarcely any parietal crests, and 
the internal protuberance is replaced by two great trans- 
verse bony plates which separate the cavity of the cerebrum 
from that of the cerebellum. 

3. Frontal bone.—In carnivora, the external face of this 
bone presents in its middle a more or Jess marked de- 
pression. The orbital arch is incomplete, and there is no 
superciliary foramen, or mortice on the inner face. The 
bone is united with the supermaxillaries. 

4. Ethmoid bone —The ethmoidal fossa is very deep, 
avd the cells very developed and diverticulated. The per- 
pendicular lamina is at a late period consolidated with the 
sphenoid bone. 

5. Sphenotd bone-—The superior sphenoid of the Dog is 
very short, and bears, laterally, two wide wings which 
ascend to the temporal fossa; they correspond to those of the 
sphenoid bone in Man. The inferior sphenoid is, on the’ 
contrary, very narrow, and its Jateral prolongations, or pro- 
cesses of Ingrassias, are reduced to very small proportions. 
The sub-sphenoidal or pterygoid process is very short, and 
the canal is single, and communicates with the foramen 
rotundum. The pituitary fossa is shallow, limited behind 
and before by the posterior clinotd and anterior clinoid 
HEAD OF DOG; ANTERIOR processes, SO named because of their being compared to the 

FACE. four posts of an pee bed. The supersphenoidal canals 
int : ‘ance: 2, #re only two in number: one represents the great sphenoidal 
hi Met ee ee fissure. the other the round foramen. The carotid notch, 
pital bone; 3, Parietal Joining @ similar one in the temporal bone, forms an open- 
bone; 4, Origin of the pa- ing which may be designated the carotid foramen, because 
rietal crests; 5, Zygomatic it gives passage to an extremely remarkable loop the in- 
process of the temporal ternal carotid artery describes after passing through the 
bone; 6, Frontal bone; 6’, carotid canal. The oval foramen is the same as in the Ox. 
Orbital’ process; 7, Zy- In the Cat there is the same disposition, with the ex- 
goma3 8, Lachrymal bone; ception of no sphenoidal canal or carotid notch being present. 
9, Nasal bone; 10, Super- 6. Temporal bone.—In the carnivora, the articular sur- 
maxilla; 11, Inferior ori- face of the zygomatic process merely forms a glenoid 
fice of the supermaxillo- cavity, into which the eondyle of the maxillary bone 
dental canal; 12, Pre- exactly fits. The temporal bone in these animals is also 
maxillary bone. distinguished by the width of the external auditory canal, 
the absence of a hyoid prolongment, the small development 
; of the mastoid and styloid processes, the enormous volume 
of the mastoid protuberance, and the presence of two paiticular canals which cannot be 
traced in the other animals. One of them, the carotid canal, traverses the mastoid 
portion, and joins, superiorly, the venous canal which passes between the basilar 
process and the temporal bone; by its inferior extremity it joins the carotid foramen 
which itself penetrates the cranium, a little beyond the venous canal just mentioned. 
The other conduit is pierced in the petrous portion immediately above the carotid canal ; 
it affords a passage to the fifth pair of encephalic nerves. 


THE HEAD, 


63 


7. Supermazillary bone—In carnivora, this bone is very short; its anterior border 


offers a long process analugous to the nasal spine of Man. 


It alone furnishes the alveolus 


of the tusk. The palatine canal, pie:ced entirely in the bone of that na 

—_ ! } L L me, neverthe 
opens, by its inferior extremity, at the junction of the supermaxillary with he ue 
bone. ‘The maxillary sinus is not very spacious, and there is no maxiliary spin 


8. Premaxillary bone.—Ot little size, the premaxillary 
of carnivora has no incisive foramen or alveolar cavity for 
the canine tooth. The incisive openings are the same as 
in the Pig. 

9. Palate bone.—In the carnivora, the palate bones are 
of great extent in their proper palatine portion. ‘They have 
no Share in the formation of the spheuoidal sinuses, but 
furnish a small excavation to the maxillary sinuses. 

10. Pterygoid bune—This bone is very strong in car- 
nivora, and quaurilateral in shape. 

11. Zygoma.—The zygoma of the Dog and Cat only 
articulates with the supermaxillary bone by its base. The 
crest describes a curve backwards, and the summit com- 
ports itself as in the lig. 

12. Lachrymal bone.—This bone in carnivora is ex- 
tremely small. Its external face entirely belongs to the 
orbit, and does not descend beneath the margin of that 
cavity; it has no lachrymal fossa. 

13. Nasal bone-—The two bones of the nose are little 
developed, and are wider below than above; they have 
no nasal prolongation, but offer instead a semicircular 
notch. 

14. Turbinated bones.— These bones in the Dog and Cat 
are particularly distinguished for their numerous convo- 
lutions. Neither participate in the formation of the frontal 
or maxillary sinuses; the latter is not in any way closed 
by the maxillary turbinated bone, but opens into the 
nasal cavity by a lurge gaping aperture. 

15. Inferior maxillary bone—In carnivora, this is 
hollowed at the point corresponding to the insertion of 
the masseter murcle into a sumewl.at dcep fossa, The 
posterior border is disprsed as in ruminants, and below 
the condyle has a very marked tuberosity. The condyle 
represents an ovoid segment, and fits exactly into the 
temporal cavity. The co:onoid process is very strong, 
elevated, and wide. The mental foramina are double or 
treble. There are no interdental spuces, nor excavated 
surface on the inner face of the branches; and the latter 
are never consolidated. 

16. Hyotd bone.—The three pieces composing the body 
of the hyoid in early life are never consolidated in the 
adult animal, but always remain isolated, as in Mun. 
The middle piece las no anterior appendix; the tibro- 
cartilages uniting the styloid portions tv each other and 
to the temporal bone are very long and flexible. 


COMPARISON OF THE HEAD OF MAN WITH THAT OF THE 
DOMESTICATED ANIMALS. 


1. Occipital bone.—The occipital of Man is large, flat, 
incurvated like a shell, and the external protuberance is 
slightly developed, and united by a ridge to the occipital 
foramen, which is relatively very wide. Two serie§ of 
ridges arise from the external protuberance and pass 
towards the circumference of the bone; these are the 
superior and inf-rior curved or semicirenlar lines. There 
is an anterior and a posterior condyloid fossa pierced by a 


Fig. 34 


DOG’S HEAD ; POSTERIOR FACE, 
1, Occipital protuberance; 2, 


Occipital foramen; 3, Occi- 
pital condyle; 4, Condyloid 
foramen; 5, Styloid process 
of the occipital; 6, Mastoia 
protuberance; 7, Concave 
temporo-maxillary articular 
surface ; | 8, Supercondy- 
loid eminence; 9, Inferior 
orifice of the parieto-tem- 
poral canal; 10, Lacer- 
ated foramen, posterior; 11, 
Ditto, anterior —On the op- 
posite side at a is shown 
the orifice communicating 
with the Eustachian tube 
and the tympanum; at 6 
the passage for the carotid 
convolution.—12, Body of 
the sphenoid; 13, Oval fora- 
men; 14, Interior orifice of 
the subsphenoidal canal; 
15, Pterygoid bone; 16, 
Nasal surface of the palate 
bone; 17, Palatine surface 
of the same; 18, Vomer; 
19, Supermaxillary bone; 
20, Incisive opening. 


foramen at the boitom; and the jugular eminences, wide and slightly prominent, re- 


place the styloid processes of the domesticated animals. 


The internal face of the ovcipital of Man corresponds with the cerebrum and 


64 THE BONES, 
cerebellum ; and for this purpose it shows four fosse, distinguished into superior or 
cerebral, and inferior or cerebellar. These fosse are separated by a crucial projection 


whose most developed portion forms the internal occipital protuberance. , 
The union of the occipital with the parietal bones constitutes the lambdoidal suture. 


At the point where this bone meets the parietal and the squamous portion of the 


temporal, is found, in the infant, the lateral posterior fontanella. ; ; 
2, Parietal bones—The parictals are always isolated in early life, and_ sometimes 


consolidated with each other at the adult age. 


They are very large, quadrilateral, and 


occupy the summit and sides of the cranium. 


Fig. 35. 


FRONT VIEW OF THE HUMAN 
CRANIUM. 

1, Frontal bone; 2, Nasal tuberosity ; 
3, Supra-orbital ridge; 4, Optic 
foramen; 5, Sphenoidal fissure; 
6, Spheno-maxillary fissure; 7, 
Lachrymal fossa; 8, Opening of 
the nose divided by the vomer; 9, 
Infra-orbital foramen; 10, Malar 
bone; 11, Symphysis of the lower 
jaw; 12, Mental foramen; 13, 
Ramus of the lower jaw; 14, Parie- 
tal bone; 15, Coronal suture; 16, 
Temporal bone; 17, Squamous 
suture; 18, Upper part of the great 
ala of the sphenoid bone; 19, Com- 
mencement of the temporal ridge; 
20, Zygoma of the temporal bone, 
concurring to form the temporal 
arch; 21, Mastoid process. 


of the orbit 


The parietal crests are absent, but are replaced, 
in certain individuals, by two faintly-marked 
curved lines situated a little above the inferior 
border of the bone. The middle portion of the 
external face is very convex. : 

On the internal face there is no parietal pro- 
tuberance, but in its stead the internal occipital 
protuberance. It also exhibits ramous channels, 
which in disposition are analogous to the ribs of 
a fig-leaf; as well as the parietal fossa which cor- 
responds to the parietal eminence. 

3. Frontal bone—The frontal bone of Man forms 
the upper part of the face and the anterior portion 
of thecranium, Convex from behind forward, then 
vertical in its upper three-fourths, the bone sud- 
denly bends at the orbits, so as to become hori- 
zontal in its lower fourth. 

The external face offers, above the forehead, two 
lateral frontal eminences, and above the nose, a 
middle frontal boss. To the right and left of the 
latter are two salient arches, the supraorbital ridges. 
‘he internal face entirely belongs to the cranial 
cavity. It offers on the median line, the saggital 
groove terminated by a frontal crest; and on each 
side of this line the frontal fossz, corresponding 
to the eminences of that name, and orbital bosses 
to match the orbital roofs. There is no mortice for 
the articulation of the sphenoid bone. 

On the middle portion of the superior frontal 
border, in young persons, is the anterior angle of 
the anterior fontanella. The anterior border ex- 
hibits three superciliary foramina and the orbital 
arches. 

4, Ethmoid bone.—In Man, the external face of 
the lateral masses, formed by a very thin lamina, 
termed the os planum or lamina papyrace, belongs 
to the internal wall of the orbit. 

5. Sphenoid bone—This is distinguished, in 
Man, into a body and four wings, two large and 
two small. 

The inferior surface of the body offers nothing 
remarkable, except the presence of a conical pro- 
longation named the beak (rostrum) of the sphe- 
noid. The external face of the greater wings forms 
part of the temporal fossa, as also the external wall 


At the union of the wings with the body are detached two bifid ptery- 


goid processes; their internal branch represents the pterygoid bones of animals. ‘There 
is no subsphenoidal canal. 

The two lesser wings are very thin and triangular, and visible only on the superior sur- 
face of the bone; they constitute the processes of Ingrassias. 

On the internal face of the bone are found :—1, A deep pituitary fossa, limited by 
four clinoid processes: 2, An optic fossa, shallow, showing very short optic canals trans- 
formed into foramina: 3, The sphenoidal fissure, which replaces the great super- 
sphenoidal canal in the Horse; 4, The great foramen rotundum : 5, The internal face of 
the wings, much excavated ; 6, The foramen ovale, which transmits the inferior maxillary 
nerve; 7, The small foramen rotundum that lodges the spheno-spinous artery, 


THE HEAD. 


65 


6. Temporal bone.—In the squamous portion of the temporal bone of Man, the 


zygomatic process only rests on the malar bone, as in ruminants. 


The glenoid cavity 


is concave in every sense, and divided into two parts by an opening named the 
Glasert ; the anterior portion ouly is articular, the posterior lying against the gale 
auditory canal, does not belong to the articulation ; it corresponds to the supracondyloid 


eminence of the Horse. 


The tuberous portion is consolidated with the squamous. It is 


divided into a mastoid and a pyramidal portion; the latter ccmprises, in its turn, the 


petrous and tympanic portions, 
mastoid protuberance, and superior border of the 


a rugged mastoid process; above this is the mast 


digastric groove; the pyramid forming wu con- 
siderable projection in the interior of the cra- 
nium. The styloid process or bone is altogether 
separate from the other pieces of the byoid, and in 
the adult is consolidated with the temporal bone. 

7. Supermazilla—tIn Man the premaxilla is 
no longer found independent, the centre which 
formsit coalescing with the supermaxillary bone. 

The supermaxilla of Man concurs, for the 

greater part of its extent, to form the floor of the 
orbit; it is also divided into three faces: an 
external or facial, a superior or orbital, and an 
internal or naso-palatine. The external face 
presents, from before to behind: 1, A small 
fossa, into which is inserted the myrtiform 
muscle; 2, The infraorbital, or canine fossa, 
showing the inferior orifice of the infraorbital 
canal; 3, A crest corresponding to the maxillary 
spine of solipeds; 4, The alveolar tuberosity. 
This face carries, in front, a prolongation that 
forms the ascending process, also named, be- 
cause of its relation, the fronto-nasal process. 
The superior or orbital face offers a fissure which 
precedes the infraorbital canal, and, outwards, 
the malar process. The internal face is divided 
by the palatine process. It shows, in front, the 
half of the anterior nasal spine and a groove 
which participates in the formation of the in- 
cisive canal. 
_ &. Palate bone.—The palate bone of Man is 
formed of two osseous Jaminz: one horizontal, 
the other vertical, which are joined at a right 
angle. The first part presents’ one-half of the 
posterior nasal spine, which is altogether rudi- 
mentary, or even null in animals; the orifice of 
the posterior palatine canal, which belongs 
entirely to the pulate bone; the pterygo-palatine 
foramen; lastly, the pterygoid process, which 
represents the pterygoid bone of animals. The 
vertical portion forms the external wall of the 
nasal cavities by its internal face, and by its ex- 
ternal face concurs in the formation of the 
zygomatic or temporal fossa. 

9. Zygoma.—This offers three faces. The 
external, or cutaneous, serves as a base for the 
most salient part of the cheek. The superior, or 
orbital, forms part of the external wall and floor 
of the orbit; it belongs to a long apophysis, 
the orbital process, which rests on the sphenoid 
and frontal bones. 


The mastoid portion corresponds to the mastoid process, 
petrous bone in the Horse. It presents’ 
oid canal; and above and behind it, the 


EXTERNAL OR BASILAR SURFACE OF 


THE BASE OF THE HUMAN SKULL 


1,1, The bony palate; 2, Incisive, or 


anterior palatine foramen; 3, Palatine 
process of palate bone, with the pos- 
terior palatine foramen; 4, Palate 
spine with transverse ridge; 5, Vomer ; 
6, Internal pterygoid palate; 7, Sca- 
phoid fossa; 8, External pterygoid 
plate, with fossa; 9, Zygomatic fossa ; 
10, Basilar process of occipital bone ; 
11, Foramen magnum; 14, Glenoid 
fossa, 15, Meatus auditorius exter- 
nus; 16, Foramen lacerum anterius,; 
17, Carotid foramen of left side; 18, 
Foramen lacerum posterius, or jugular 
foramen; 19, Styloid process; 20, 
Stylo-mastoid foramen, with jugular 
tubercle and digastric fossa; 21, Mas- 
toid process; 22, Occipital bone; 23, 
Posterior condyloid fossa, 


The posterior face is smooth and concave behind, where it aids to 


form the temporal fossa; in front it is uneven, and articulates with the supermaxilla. 
The posterior, or masseteric border, unites with the zygomatic process of the temporal 


bone. 


10. Lachrymal bone.—This bone is also called the os unguis in Man, because of its 
likeness to the nail in shape and tenuity. It is entirely lodged in the orbit, and its 


66 THE BONES. 


external face is divided into two portions by a vertical crest; the portion situated in front 
of this crest forms part of the lachrymal channel. By its internal face, the lachrymal 
bone limits, outwardly, the bottom of the nasal cavities, and covers the anterior cells of the 
ethmoid; by its posterior border, within the orbit, it articulates with the os planum of 


the ethmoid. on 
11. Nasal bone.—The proper bones of the nose of Man exhibit a great analogy to 


those of the Dog. They do not possess a nasal prolongation, and they articulate with 


the lateral cartilage of the nose. ; ; 

12. Vomer.—The same general form and relations as in solipeds, : 

13. Inferior maxillary bone.—This bone in Man is in shape somewhat like a horse- 
shoe. It is nearly of the same width throughout its whole extent. The symphysis is 
vertical—a character peculiar to Man. Below this symphysis 1s a triangular projection, 
the mental eminence The genial surface of the Horse is replaced by four little tubercles 
termed the genial processes. The alveoli of the molar teeth form a great projection on 
the inner face of the bone. The mylo-hyoid ridge is very developed. The superior 
orifice of the dental canal is covered by a litile sharp lamina. From this orifice begins the 
mylo-hyoidean groove. The coronoid process is short; the condyle is bent towards the 
median line, and the sigmoid notch is wide and shallow. The superior border contains 
fourteen or sixteen alveoli. 


ArticLe IJI.—Tue THorax. 


The thorax represents a conoid cage, elongated from before to behind, 
suspended under the vertebre of the dorsal region, and destined to contain 
the principal organs of respiration and circulation. It is composed of bony 
arches named ribs, thirty-six in number—eighteen on each side—and a single 
piece, the sternum, which serves for the direct or indirect support of the 
inferior extremities of the ribs. 


THE BONES OF THE THORAX IN PARTICULAR. 
1. Sternum of the Horse. 


This is an osteo-cartilaginous body, elongated from before backwards, 
flattened on each side in two-thirds of its anterior extent, and from above 
to below in its posterior third, slightly curved on itself, and situated beneath 
the thorax in an oblique direction from above to below, and before to behind. 
It offers for study. a superior face, two lateral faces, three borders, and two 
extremities. 

Fig. 37, 


THE STERNUM. 


1. The cervical prolongation (or cariniform cartilage); 2, The xiphoid appendage (or ensiform 
cartilage; 3, 3, Cavities for the articulation of the sternal cartilages; 4, Inferior border. 


Faces.—The superior face, slightly concave longitudinally, represents an 
isoscelated, lengthened triangle, the summit of which is directed forwards: 
it constitutes the floor of the thoracic cavity. ach lateral face comprises 
two parts—a superior and an inferior, The first shows eight diarthrodial 


THE THORAX. 67 


cavities, which receive the inferior extremity of the cartilages of the true 
ribs. These cavities are elongated vertically, and draw closer to each other 
as they extend backwards. The inferior part, which is more extensive before 
than behind, offers to the powerful pectoral muscles a large surface for 
insertion. 

Borders.—The two lateral borders separate the superior from the lateral 
faces ; they are situated above the diarthrodial cavities, are united anteriorly, 
and each gives attachment to a fibrous band. The inferior border is opposite 
the superior face ; convex, thin, and very prominent in its anterior two-thirds, 
it somewhat resembles the keel of a ship. 

Extremities.—The anterior flattened on each side and curved upwards, 
exceeds to some extent the first articular cavity of the lateral faces, and in 
this way constitutes the cervical prolongation of the sternum. The posterior 
extremity is flattened superiorly and inferiorly, and forms a large cartila- 
ginous plate, very thin, concave above, convex below, which has received the 
name of the abdominal prolongation (ensiform cartilage) or xiphoid appendage. 

Structure and development.—The sternum is one of the parts of the skeleton 
which do not submit to complete osseous transformation. It is developed, 
in solipeds, from six single centres of spongy substance, ranged one behind 
the other, like beads on a string. These centres never coalesce to form a 
solid piece, but remain separated, during the life of the animal, by the 
primitive cartilaginous mass. The latter constitutes the entire anterior pro- 
longation of the bone and its carina, as well as the xiphoid appendage. When 
these parts of the sternum become ossified, which is rare, it is only partially. 


2. The Ribs. 


As has been already noticed, on each side of the thorax eignteen ribs are 
counted. These are nearly parallel to each other, and separated by the 
intervals termed the intercostal spaces. Attached by their superior extremity 
to the vertebra of the dorsal region, these bones terminate at their inferior 
extremity by an elastic and flexible prolongation, named the costal cartilage, 
by means of which they are brought into direct or indirect relations with 
the sternum. The characters common to all the ribs will be first noticed, 
then the special features which serve to distinguish them from each other, 
and, lastly, the differences they exhibit in other than soliped animals. 

A. CHARACTERS COMMON To ALL THE Rips.—These will be studied from a 
typical point of view, first in the rib itself, and then in its cartilage. 

1. Description of a typical rib—A rib is an elongated symmetrical bone, 
oblique from above to below, and from before to behind, flattened on both 
sides, curved like a bow, and twisted on itself in such a fashion that its two 
extremities cannot rest on the same horizontal plane. It is divided into a 
middle portion and two extremities. 

Middle portion.—This offers two faces and two borders. The external 
face is convex, and hollowed by a wide groove in its anterior half; it shows 
superiorly, towards the point corresponding to the angle of the rib in Man, 
some tubercles and muscular imprints. ‘lhe internal face is concave and 
smooth, and covered by the pleura, which separates it from the lungs. The 
anterior border is concave, thin, and sharp; the posterior, convex, thick, and 
covered with rugged eminences, is channeled inwardly by a vasculo-nervous 
fissure, which disappears near the middle of the rib. 

Extremities—The superior has two eminences, a head and a tuberosity, 
which serve for the support of the rib against the spine. The first is formed 
by two articular demi-facets, placed one before the other, and separated by a 


68 THE BONES. 


groove for ligamentous insertion; it is isolated from the tuberosity by a 
narrow part, named the neck, which exhibits a rugged fossa for the implanta- 
tion of a ligament. The second, situated behind the head, and smaller than 
it, is provided with imprints on its margin, and presents an almost flat 
diarthrodial facet at the summit. Each rib articulates by its head and 
tuberosity with two dorsal vertebre ; the head is received into the inter- 


Fig. 38, 


TYPICAL RIBS OF THE HORSE. 


A, Inner face of the fifth sternal rib; B, External face of the first asternal rib.— 
1, Head of the mb; 2, Its fissure; 3, Neck; 4, Tuberosity ; 5, Articular facets 
6, Scabrous fossa for the insertion of the interosseous costo-transverse ligament 5 
7, Groove on the external face; 8, Vasculo-nervous groove of the posterior 
pe 9, Prolonging cartilage; 10, a, Articular tuberosity for union with the 
sternum. 


vertebral articular cavity; the tuberosity corresponds, by its facet, to the 
transverse process of the posterior vertebra. ; 
_ The inferior extremity is tuberous and excavated by a shallow cavity 
irregular at the bottom, for the reception of the upper end of the costal 
cartilage. 

Structure and development.—The ribs are very spongy bones. especially 


LHE THORAX. 69 


in their inferior moiety, and are developed at a very early period by three 
centres of ossification: a principal for the middle portion and inferior 
extremity, and two complementary for the head and tuberosity. 

2. Description of a typical costal cartilage—The costal cartilage very 
evidently represents the inferior rib in birds; it is a cylindrical piece, 
slightly compressed at the sides, and round and smooth on its faces and 
borders. By its superior extremity, it is united to the rib it serves to 
lengthen, and forms with it an angle more or less obtuse, opening in front. 
At its inferior extremity, it is terminated by an articular enlarge- 
ment, or by a blunt point. In youth, the costal prolongations are entirely 
composed of cartilaginous matter, but they are soon invaded by ossification ; 
so that in the adult animal they are already transformed into a spongy 
substance, with large areole which remain during life surrounded by a thin 
layer of cartilage. 

B. Spsctric Cuaracters or THE Rrss.—The ribs, like the vertebrae of each 
region of the spine, have received numerical designations of first, second, third, 
etc., computing them from before to behind. (See Fig. 1.) Owing to the pre- 
sence of an altogether essential characteristic, they are naturally divided into 
two great categories: the sternal or true ribs, and the asternal or false ribs. 
The sternal ribs, numbering eight (the first eight), have their cartilages 
terminating inferiorly by an articular enlargement, which corresponds to one 
of the lateral cavities of the sternum, and brings the true ribs into direct 
contact with this portion of the skeleton. The asternal ribs, ten in number, 
rest on each other—the last on the seventeenth, this on the sixteenth, and so 
on-—by the inferior extremity of their cartilage, which ends in a blunt point. 
The cartilage of the first false rib is united somewhat closely to the last 
sternal rib, and it is through the medium of this that all the asternal ribs lie 
indirectly on the sternum. 

If, however, the ribs are considered altogether, with regard to the differen- 
tial characters presented by them in their length, width, and degree of 
incurvation, it will be noted: 1, That their length increases from the first 
to the ninth, and from this diminishes progressively to the last: 2, That the 
same progressive increase and decrease exists in the cartilages; 3, That they 
become gradually wider from the first to the sixth inclusive, and then con- 
tract by degrees until the eighteenth is reached ; 4, That the curve described 
by each is shorter and more marked as the rib is situated more behind. It 
may be added that the channel on the external face is less conspicuous in 
proportion as the rib is narrow. 

The first rib, considered individually, is always distinguished by the 
absence of the groove on its outer surface, the vasculo-nervous fissure on its 
posterior border, and the groove or notch intermediate to the two facets of 
its articular head. It is also recognised by the deep muscular imprints on 
its external face, the shortness and thickness of its cartilage. and particularly 
by the articular facet which this cartilage exhibits inwardly, to correspond 
to that of the opposite rib. The last rib has no channel on its ‘external 
surface; the facet of its tuberosity is confounded with the posterior facet of 
the head. This last character is- also nearly always remarked in the 
seventeenth rib, and sometimes even in the sixteenth. 

In the Ass and Mule, all the ribs in general, but particularly those most 
posterior, are less curved than in the Horse. (In the Horse, a nineteenth 
pair of ribs is sometimes found, and this even with five, and at other times 
with six lumbar vertebre; it happens that the nineteenth rib is formed by 
the transverse process of the first lumbar vertebra, and at times a ligament 

8 


70 THE BONES. 


is given off from this process, which joins it to a pointed bone or @ cartilage 
in its vicinity. If the hymn on the ‘Sacrifice of the Horse,” in the most 
ancient collection of Aryan poems, is to be credited, the horses of antiquity 
in Central Asia had only seventeen pairs of ribs. The mobility of the ribs 
is scarcely perceptible in the first, but increases until the ninth or tenth is 
reached, after which it gradually diminishes.) 


THE THORAX IN GENERAL. 


The description of the interior of the thoracic cavity will be referred to 
when treating of the respiratory apparatus. It is only necessary here to 
examine the external surface of this bony cage; for this purpose it is 
divided into six regions :—a superior plane, an inferior plane, two lateral planes, 
a base, and a summit. 

Planes.—The superior plane is separated into two portions by the spinous 
processes of the dorsal vertebra ; each forms, with these spinous processes, the 
costo-vertebral furrow, intended to lodge the majority of the muscles belong- 
ing to the spinal region of the back and loins. The inferior plane, less 
extensive than the preceding, offers: 1, On the median line, the cariniform 
and xiphoid cartilages of the sternum; 2, On the sides, the chondro-sternal 
articulations, and the cartilages of prolongment of the true ribs. The 
lateral planes are convex and wider at their middle part than in front or 
behind, and exhibit the intercostal spaces. They serve to give support, 
anteriorly, to the superior rays of the two fore-limbs. 

Base.—This is circumscribed by the posterior border of the last rib, and 
by the cartilages of all the asternal ribs; it is cut obliquely from above to 
below, and from before to behind. It gives attachment, by its internal 
circumference, to the diaphragm, a muscle which separates the thoracic from 
the abdominal cavity. 

Summit.—lt occupies the anterior portion of the thorax, and presents an 
oval opening, elongated vertically, situated between the two first ribs. This 
opening constitutes the entrance to the chest, and gives admission to the 
trachea, the cesophagus, and important vessels and nerves. 


DIFFERENTIAL CHARACTERS OF THE THORAX IN OTHER THAN SOLIPED ANIMALS. 


1, Sternum, 


In all the domesticated animals except solipeds, the sternum is flattened above and 
below, instead of from side to side. 

_ Rusmnayrs.—In ruminants, each piece is developed from two lateral centres of ossifica- 
tion. The bones which compose it are seven in number; they are much more compact 
than those in the sternum of the horse, and at an early period are united to each other, 
with the exception of the first, which is joined to the second by a diarthrodial articula- 
tion that permits it to execute lateral movements. There is no cervical prolongation, 
and the xiphoid cartilage is feebly developed and well detached from the body of the 
bone. In the sternum of the Goat and Sheep, the two first pieces have no diarthrodial 
joint, but are simply united by a layer of cartilage which, in old animals, becomes 
completely ossified. : 

Pia.—The sternum of this animal presents in its general conformation the essential 
features of that of large ruminants. It is provided with a well-defined cervical prolonga- 
tion, and is composed of six pieces which, at least in the four or five last, are each 

divided into two lateral centres. : j 

Carnivora.—The sternum of the Dog and Cat is formed of eight pieces elongated from 
‘before to behind, hollowed in their middle part, and thick at their ends—formed, indeed, 
like the last coccygeal vertebrae of the Horse. They are never ossified to each other. 


THE THORAX, 71 


2. Ribs. 


: The number of ribs varies like that of the dorsal vertebre. The following table 
indicates the number of these bones in the ditterent domesticated animals. 


Pig s th . 14 
Ose! gs ley ee ae ae ee 
Sheep. ° . . . . . 13 
Goat'e, eae oe a aS 
DOS wh: Serie viel es we 


Rominants.—These animals have eight sternal and five asternal ribs. 

In the Ox, they are longer, wider, and less arched than in solipeds. The articular 
eminences of the superior extremity are voluminous and well detached; the neck 
especially is very long. The sternal ribs are joined to their cartilage of prolongment by 
a real diarthrodial articulation. In the last rib, and sometimes in the one before it, 
the tuberosity is scarcely perceptible, and has no articular facet. In the Sheep and Goat, 
the sternal ribs are consolidated with the cartilages (see fig. 5.) 

Pic.—In this anima] there are fourteen pairs of ribs, seven of which are sternal and 
seven asternal. The first are provided with cartilages of prolongment flattened on both 
sides, extremely wide aud sharp, and convex on their superior border. In the four last 
asternal ribs, the facet of their tuberosity is confounded with the posterior facet of the 
head. (Otherwise, the ribs of the Pig resemble, in their general conformation, those of 
the Sheep or Goat; though more incurvated and wider.) 

CarNivora.—They possess thirteen ribs 
on each side—nine sternal and four asternal. 
These are very much arched, narrow, and 
thick, and their cartilages rarely ossify. In 
the Dog, the articular facet of the tuberosity 
remains isolated from the posterior facet of 
the head in all the ribs. It is absent in the 
three last ribs of the Cat. 


COMPARISON OF THE THORAX OF MAN WITH 
THAT OF THE DOMESTICATED ANIMALS, 


1. Sternum. 


The sternum of Man is flattened before /A\ 
and behind, and diminishes in width from [\¥g 
above to below. The xiphoid appendage is 
narrow, and single or bifid. Besides the 
articular surfaces for the ribs, there are found 
-on the upper end two lateral notches for 
articulation with the clavicles. 


2. Ribs. 
Of the twelve ribs in Man, seven are 
sternals and five asternals. They are 


short, narrow, and much incurvated, especially 
the first ones. In each rib the curvature 1s 
more marked in the posterior fourth or fifth 
than in the anterior three-fourths or four- 
fifths; this sudden change of curvature Js 
indicated in the external face by a kind of 
inflexion and thickening called the angle of 
the ribs. The prolonging cartilages of the 
eleventh and twelfth ribs are short, and are 
lost in the texture of the abdominal parietes:; 
for this reason they are termed the floating (or 


false) ribs (see fig. 39). 


THORAX OF MAN; ANTERIOR FACE, 
1, Superior piece of the sternum; 2, 
Middle piece, or body; 3, Inferior piece, 


or ensiform cartilage; 4, First dorsal 
vertebra; 5, Last dorsal vertebra; 6, 
First rib; 7, Its head; 8, Its neck, rest~ 
ing against the transverse process of the 
first dorsal vertebra; 9, Its tubercle; 10, 
Seventh, or last true rib; 11, Costal car- 
tilages of the true ribs; 12, The last two 
false or floating ribs; 13, The groove 
along the lower bérder of the rib. 


Agtiote IV.—AyteRion Lines. 


The anterior (or thoracic) 
the shoulder, arm, fore-arm, 


limb is divided into four secondary regions : 
and fore-foot or hand. 


72 THE BONES. 


SHOULDER. 


In solipeds, this region has for its base a single bone, the scapula or 
omoplat. 
Scapula. 


This is a flat, triangular, and asymmetrical bone, prolonged — at its 
superior border by a flexible cartilage, articulated inferiorly with the 
humerus only, and applied 
against the lateral plane of the 
thorax in an oblique direction 
downwards and forwards. It 
has two faces, three borders, and 
three angles. 

Faces.—The external face is 
divided by the scapular or acro- 
mian spine, into two cavities of 
unequal width—the supra and 
infraspinous (or antea and postea 
spinatus) fossse. The spine isa very 
salient crest which runs the whole 
length of the external scapular 
surface; very elevated in its 
middle part, which shows an 
irregular enlargement—the tube- 
rosity of the spine—it insensibly 
decreases towards its two ex- 
tremities. The supraspinous 
fossa, the narrowest, is situated 
above, or rather in front of the 

- Spine; it is regularly concave 
. from side to side, and perfectly 
smooth, The tnfraspinous fossa 
is twice the width of the pre- 
ceding, and occupies all the sur- 
face behind the spine. It ex- 
hibits: 1, Below, and near the 


THE RIGHT SCAPULA}; OUTER SURFACE. 


1, Antreior border; 2, Superior margin for insertion el A 1 
of cartilage; 3, Tuberosity of the spine ;4, Antea- POSverlor bor er, several rows 
spinatus fossa; 5, Postea-spinatus fossa; 6, Neck of roughened lines for muscular 
of the scapula; 7, Coracoid process; 8, Glenoid insertion; 2, Near the neck, the 


une ae 
cavity! nutritious foramen of the bone, 


and some vascular grooves. 

The internal face is excavated in its centre to form a hollow called the 
subscapular fossa, which is prolonged superiorly by three diverging points. 
The anedian point extends to the superior border of the bone, and separates 
two roughened triangular surfaces destined for muscular implantation. 

Borders.—The superior is indented by an irregular groove to receive the 
inferior margin of the cartilage of prolongment. 'The latter is convex on its 
superior border, extends beyond the posterior angle of the bone, and 
gradually diminishes in thickness as it leaves its point of attachment. 
In old horses it is nearly always found partially ossified. The «anterior 
border, thin and sharp, is convex in its superior two-thirds, and slightly 
concave for the remainder of its extent. The posterior is thicker and a little 
concave. 


THE ANTERIOR LIMBS. 73 


Angles.—The anterior or cervical angle is the thinnest of the three. The 
posterior or dorsal angle is thick and tuberous, The inferior or humeral 
angle is the most voluminous, and is separated from the remainder of the 
bone by a slight constriction, which constitutes the neck of the scapula. It 
exhibits : 1, The glenoid cavity, an oval diarthrodial surface, excavated to a 
slight extent to receive the head of the humerus, notched on the inner side 
and bearing on the external margin of the ridge which surrounds it a amall 
tubercle of insertion; 2, The \coracoid process, situated in front, and at a 
certain distance from the glenoid cavity. This is a large eminence 
in which may be distinguished two parts: the base, a thick rugged process ; 
and the summit, a kind of beak curved inwards. ; 

Structure and development.—Like all the wide bones, the scapula is 
formed of two compact lamelle separated by spongy tissue. The latter is 
yery scanty towards the centres of the supra and infraspinous fosse, where it 
is often altogether wanting; it is most abundant in 
the angles. The scapula is developed from two centres 
of ossification, one of which forms the coracoid pro- 
cess. 


Fig. 41. 


ARM, 
This region has only one bone, the humerus. 


AMumerus. 


The humerus is a long single bone, situated between 
the scapula and the bone of the fore-arm, in an oblique 
direction downwards and backwards. Like all the long 
bones, it offers for study a body and two extremities. 

Body.—The body of the humerus looks as if it 
had been twisted on itself from within to without in 
its superior extremity, and from without to within at 
the opposite end. It is irregularly prismatic, and is 
divided into four faces. The anterior face, wider: 
above than below, has in its middle and inferior por- 
tions some muscular imprints. The posterior, smooth 
and rounded from one side to the other, becomes 
insensibly confounded with the neighbouring faces. 
The external is excavated by a wide furrow, which 
entirely occupies it, and turns round the bone ob- 
liquely from above to below and bebind to before ; 
it is to the presence of this channel that the humerus ayrmro-exTeRNAL VIEW 
owes its apparent twist, a2PTCiggs "in consequence oF RIGHT HUMERUS. 
designated the furrow of tor: the body of the 1, Trochlear or bicipita 


humerus. ee i pe bale 
This furrow is separat 1 the anterior face fyasq or articulan 

by a salient border, the a wst of the furrow face; 4, External? 

of torsion, which ends inft , the | coronoid cle; 5,Shas 

‘fossa, and superiorly, tow third of the om ; 

bone, by the imprint. Thisisa oO 

roughened, very pr haficce = y 

and behind, and ‘ ed 

torsion ; by-it= ' 

a, curved liz ” 


base ef 


74 THE BONES, 


¢ 


outwards, is seen the posterior crest of the furrow of torsion, which separates the 
latter from the posterior face of the bone. The interdal face of the body of 
the humerus, rounded from side to side, is not, separated from the anterior 
and posterior faces by any marked line of demarcation. © It offers, near its 
middle, a depressed scabrous process for the insertion of the adductor 
muscles—teres major and great dorsal—of the arm. Towards its inferior 
third it shows the nutritive foramen of the bone. 

Extremities —These are distinguished into superior and inferior. Both 
are slightly curved, the first backwards, the second forwards, a disposition 
which tends to give to the humerus the form of an S. 

The superior eatremity is the most voluminous, and has three thick 

eminences; a posterior, external, and internal. The 
Fig. 42, first constitutes the head of the humerus; it is a 
very slightly-detached articular eminence, rounded 
like the segment of a sphere, and corresponding to 
the glenoid cavity of the scapula, which is too small 
to receive it entirely. The external eminence, named 
the trochiter, large trochanter, and great tuberosity, com- 
prises three portions, named the summit, convexity, and 
crest of the great tuberosity. The internal eminence, 
the trochin, little trochanter, or small tuberosity, also 
presents three distinct portions, which, by their posi- 
tion, correspond exactly with the three regions of 
the large trochanter: these are so many muscular 
facets. Bi 

The great and small trochanters are separated 
from one another in front by a channel called the 
bicipital groove, because the superior tendon of the 
biceps muscle glides over it; it consists of two 
vertical grooves with a median ridge between 
them. 

The inferior extremity of the humerus has an 
articular surface corresponding to the radius and ulna. 
This surface, elongated transversely, convex from 
before backwards, and of greater extent within than 
without, exhibits two trochlea separated by an antero- 
posterior relief. 


e 


POSTERIOR VIEW OF THE . . ” . 
HIGHT KOMERYS: The .median or, internal trochlea, the deepest, is 


2, External tuberosity; 3, limited internally by a kind of voluminous condyle, 
Articular head of the Which corresponds to the inner lip of the humeral 


bone; 4, External tu- trochlea of Man, ~ external trochlea is bordered 
ae ate i he outwardly by a sl salient lip, which corresponds 
bond; 10, Condyloid to the condyle of aumerus of Man. Above and 
+, fossa, behind this articul dace is a wide deep fossa, the 
«a 6 olecranian (or con. - Q named because it lodges the 
‘the olecranon in the exteny ents of the fore-arm. It is 

*9 eminences, the er’ ry is less elevated than the 

rst represents ‘ and the second the epi- 

umervs.nf, Mai “ove the inner trochlea, 

pug cet Bat as the coronoid pro- 


vy this reason, it 
ihastly, at the 
‘rface is 


THE ANTERIOR LIMBS. 15 


remarked: outwardly, an excavation for ligamentous insertion ; inwardly 
a small tuberosity intended for the same purpose.! ° 

Structure and development—The humerus, like all the long bones, is 
only spongy at its extremities. It is developed from six points of ossi- 
fication ; one of which alone forms the body, one the head and the small 
trochanter, another the large trochanter, a fourth the inferior articular 
surface, a fifth the epicondyle, and the last for the epitrochlea, The latter is 
sometimes absent. 


FORE-ARM. 


_ This region has for its base two bones, the radius and cubitus (or ulna) 
united into a single piece at an early period.in most of the domesticated 
animals, 


1. Radius. 


This is a long bone, placed in a vertical direction between the 
humerus and the first row of carpal bones, and divided into a body and 
two extremities. k 

Body.—Slightly arched and depressed from before to behind, the body 
presents for study two faces and two borders. The anterior face is convex 
and perfectly smooth. The posterior, a little concave from one extremity to 

“the other, offers: 1, Near the external border, a triangular surface, covered 
with asperities, elongated vertically, very narrow, commencing near the 
upper fourth of the bone and terminating in a fine point towards the lower 
fourth: this surface is brought into contact with the anterior face of the 
ulna by an interosseous ligament, which is completely ossified before the 
animal reaches adult age; 2, Above, there is a wide, transverse, but shallow 
groove, which aids in forming the radio-ulnar arch and shows, near the point 
where it touches the preceding surface, the nutrient foramen of the bone; 
'8, Near the internal border, and towards the inferior third, there is a ver- 
tically elongated and slightly salient eminence of insertion. The two 
borders, external and internal, are thick and rounded; they establish an 
insensible transition between the faces. . 

Extremities.—The superior is larger than the inferior. It has: 1, An 
articular surface elongated from one side to the other, concave from before 
to behind, wider within than without, and moulded to the articular surface 
of the inferior extremity of the humerus; there is also seen, outwardly, a 
double gorge which receives the two lips of the external trochlea; in the 
middle, an antero-posterior ridge which is received into the internal trochlea ; 
within, an oval cavity corresponding to the internal border of the former ; 
2, The external tuberosity, placed at the extremity of the great diameter of - 
the articular surface; it is prominent and ‘well detached ; 3, The internal or 
bictpital tuberosity, a large, very rugged, and depressed process, situated 
within and in front of the glenoid cavity; 4, A little lower, and on the same 
side, there is a strong muscular and ligamentous imprint, separated from the 
preceding tuberosity by a transverse groove intended for the passage of a 
tendinous branch ; 5, The coronoid process,? a small conical eminence, at the 
summit of which terminates, anteriorly, the median ridge of the articular 


1 The articular surfaces which, in veterinary anatomy, have received the names of 
trochlea and condyle, not being the same as in human anatomy, there results an annoying 
inversion of the situation of the epitrochlean and epicondyloid eminences, so named. It 
has therefore been our endeavour to remedy the improper employment of these 
denominations, which has been a cause of error in comparative anatomy. 

\ 2 In Man this belongs to the ulna. 


76 . 


THE BONES. 


surface; 6, Two diarthrodial facets elongated transversely, cut on the 
posterior outline of the large articular surface, with which they are con 


Fig. 43. 


EXTERNAL FACE OF THE 
RADIUS AND ULNA. 


1, Ulna; 2, Point of the ole- 
cranon; 3, Beak of the ole- 
eranon; 4, Radio-ulnar arch; 
Supero-external tuberosity ; 
6, Radio-ulnar articular sur- 
faces for the humerus; 7, 
Bicipital tuberosity; 8, 
Shaft or body of the radius ; 
9, Grooves for tendons, 


founded by their superior border ; they correspond 
to similar facets on the ulna; 7, Below these, a 
roughened surface which extends to the radio- 
ulnar arch, and is in contact with an analogous 
surface of the same bone through the medium of 
an interosseous ligament; in the Horse this liga- 
ment rarely ossifies. 

The inferior extremity, flattened from before 
to behind, ‘presents: 1, Below, an articular sur- 
face elongated transversely and somewhat irregu- 
lar, responding to the four bones in the upper 
row of the carpus; 2, On the sides, two tube- 
rosities for ligamentous insertion, the internal 
salient and well circumscribed, the other eaternal- 
and excavated by a vertical fissure, in which passes 
a tendon; 38, In front, grooves for the 
gliding of tendons; the external is the largest, and. 
vertical like the median; the internal, the nar- 
rowest, is oblique downwards and inwards; 4, 
Posteriorly, a strong transverse ridge which sur- 
mounts the articular surface and serves for the 
insertion of ligaments. 

Structure and development. The radius is a 
very compact bone, and is developed from three. 
centres of ossification: one for the body and two 
for the extremities. 


2. Ulna. 


This is an elongated, asymmetrical bone, in 
the form of an inverted triangular pyramid, applied 
against the posterior face of the radius, to which 
it is united in adult solipeds. It offers for des-. 
cription a middle portion and two extremities. 

Middle portion —This has three faces wider 
above than below, and three borders which become 
joined at the inferior extremity of the bone. The. 
eaternal face is smooth and nearly plane. The 
internal is also smooth and slightly hollowed. 
The anterior is formed to correspond to the radius, 
and presents peculiarities analogous to those of 
the posterior face of that bone. Thus there is 


found in proceeding from above to below: 1, Two small diarthrodial 
facets ;1 2, A rough surface; 3, A transverse groove for the formation of 
the radio-ulnar arch; 4, A triangular surface, studded with rugosities, 
which occupies the remainder of the bone to its lower extremity. The lateral 
borders, external and internal, are sharp, and, like the anterior face, are in 
contact with the radius. The posterior border is concave, rounded, and thicker 


than the other two. 


_ Extremities.—The superior extremity comprises all that portion which 
exceeds the articular surface of the radius. It constitutes an enormous 
1 It is represented in Man by the smaller sigmosd notch, 


THE ANTERIOR LIMBS. 77 


process—the olecranon—flattened on both sides, and presenting: 1, An 
external face, slightly convex; 2, An internal excavated face; 8, An 


anterior border, thin and sharp superiorly, 
notched below to for mthe sigmoid cavity :! an 
articular surface concave from above down- 
wards, rounded from one side to the other, 
which corresponds with the humeral cavity, 
and is surmounted by a salient prolongation 
named the beak of the olecranon; 4, A con- 
cave and smooth posterior border; 5, The 
summit, a kind of thick roughened tuberosity 
which terminates the olecranon above, and into 
which are inserted the extensor muscles of the 
fore-arm. 

At its inferior extremity, the ulna ends, 
towards the lower fourth of the principal por- 
tion of the fore-arm,in an acute point, and 
sometimes by a small knob (capitulum ulnve). 
It is not rare to see it prolonged, especially 
in the Ass and Mule, to the inferior external 
tuberosity of the radius. This tuberosity then 
appears to belong to it, at least in part; and 
all that portion which is situated behind its 
vertical groove might be justly considered as 
belonging to the ulna. 

_ Structure and development.—The ulna con- 
tains much compact tissue, even in the region 
of the olecranon; it is also very solid. It is 
an imperfect bone, developed from two centres 


of ossification only, one of these being for the , 


apex of the olecranon. 


FORE-FOOT OR HAND. 


The anterior foot, or hand, is the region 
which presents the greatest differences when it 
is inspected in the various individuals of the 
animal series. Nevertheless, in all the mam- 
malia the constitution of the hand is funda- 


mentally the same, and may be divided into - 


three sections: the carpus, metacarpus, and 
phalangeal region. 

The hand is formed by five parallel or 
quasi-parallel rays that constitute the digits, 
each of which is effectively or virtually com- 
posed of two superposed carpal, a metacarpal, 
and three phalangeal bones, forming altogether 
the digit, properly so called. But this typical 
composition, established through the labours 
of MM. Joly and Lavocat, is rarely found to 
be realised in a complete manner. 


Fig. 44, 


RIGHT FORE-FOOT OF A HORSE. 

1, Radius; 2, Groove for the an- 
terior extensor of the phalan-- 
ges; 3, Scaphdides; 4, Lunare, 
5, Cuneiform; 6, Trapezium ; 
7, Magnum; 8, Uncifurm; 9, 
Metacarpal; 10, Small meta- 
carpal; 11, Sesamoid bone; 12, 
Suffraginis; 13, Coronary; 14, 
Naviculars 15, Pedal; 16, Its 
ala. 


The following is what is presented in the hand of Man, who is the most 


1 The greater sigmoid cavity of Man. 


78 THE BONES. 


perfect pentadactylous type. The carpus is composed of eight bones, the 
metacarpus of five small, parallel, bony columns; the phalangeal region of five 
digits—thumb, index, medius, annularis, and auricularis, formed each of three 
phalanges, with the exception of the thumb, which has only two. 

In the domesticated animals, the constitution of the hand is more or less 
removed from this type, in consequence of abortive development, which 
diminishes either the number of rays, or the number of pieces composing 
these. 

Thus, in the Cat and Pig there are eight bones in the carpus; but in the 
Dog and Horse there are no more than seven; in the Ox and Sheep there are 
only six, for in them two or three bones are fused together. 

The metacarpus of the Dog and Cat has certainly five metacarpal bones, 
but the metacarpus of the Pig hasno more than four, that of the Horse three, 
and that of Ruminants only two. In the metacarpus of the Pig the fifth bone 
is not developed. In the Horse it is entirely absent; the fourth and first are 
independent, and the third and second are confounded to form a voluminous 
bone which has been named the principal (or large) metacarpal. In Ruminants, 
the fourth and fifth metacarpals are quite imperfect, the first being arrested 
in its development, and the second and third becoming consolidated as in 
the horse. 

Lastly, it is noted that the digital region of Carnivora has five digits, 
the Pig four, Ruminants two, and Solipeds only one. In the Pig, the thumb 
is undeveloped; in ruminants it is completely absent, and the first and 
fourth are represented by two small bones situated behind the metacarpo- 
phalangeal articulation; while in solipeds the single digit already mentioned 
results from the fusion of the auricularis and medius. 

From this preliminary synthetical exposition, it will be easy to 
understand the description of the bones composing the hand in solipeds. 


1. Carpal Bones. 


The carpus forms the base of the hand. Situated between the inferior 
extremity of the radius and the superior extremity of the metacarpal bones, 
it is composed of several small bones joined to each other in the fresh state 
by extremely solid articular bands. Collectively, they form an almost 
quadrilateral mass in which may be distinguished two faces and four 
borders. 

The anterior face is slightly convex from side to side and irregular; it 
corresponds to the tendons of the extensor muscles of the metacarpus and 
phalanges. 

_ The postertor face is very unequal and converted, especially outwardly, 
me a groove in which the tendons of the flexor muscles of the phalanges 
glide. 

The superior border articulates with the radius; the inferior border with 
the metacarpal bones. 

_ The lateral borders are nearly level; above and behind the external border 
is remarked a considerable eminence, formed by the bone which will be 
hereafter studied as the supercarpal bone (or trapezium). 

In the carpus of the Horse are seven bones, which are disposed in two 
superposed rows. The superior row comprises four bones placed side by 
side, and designated by the numerical names of first, second, third, and fourth, 


viewing them from without to within. The inferior row has only three, 
which are named in the same manner, 


THE ANTERIOR LIMBS. 79 


In applying to them the names proposed by Liser, we have, in the upper 
row: 
#1. The pisiform, or supercarpal bone (trapezium) ; 
$2. The pyramidal (or cuneiform) bone; — 

23. The semilunar (or lunare) bone 

} 4, The scaphoid bone; 


In the inferior row: 


7 1. The hook or unciform bone ; 
6 2. The great bone or capitatum (magnum); ~ 
5 3. The trapezoid bone. 


The description of these bones is most simple, and may be made in a 
general manner for all. Thus, with the exception of the supercarpal bone, 
they are solids, nearly cubical in form, and exhibit’ on their periphery : 
1, Articular surfaces ; 2, Surfaces of insertion. 

The articular surfaces represent small, flat, or slightly-undulating facets, 
distributed on the superior, inferior, and lateral surfaces ; none are found in 
front or behind. The superior and inferior faces are entirely occupied by 
a single facet which responds either to the radius, the metacarpal, or to the 
bone of the other row. The lateral facets are always multiple and in contact 
with the bones of the same tier ; they do not exist, of course, on the eccentric 
side of the first and third bones of the superior or inferior rows. 

The surfaces of insertion are absent on. the superior and inferior faces; 
they separate, in the form of roughened fosse, the lateral articular facets. 
Before and behind they are covered by more or less marked rugosities. 

Bonzs or THE Upper or AntipracuiaL Row.—The first, or os pisiforme, 
is without the row; it is situated above and behind the carpus, from whence 
its name of supercarpal bone, by which it is usually known in veterinary 
anatomy. .This bone, which merits a special description, represents a disc 
flattened on both sides, offering for study two faces and a circumference. 
The external face is convex, roughened, and channeled anteriorly by a 
groove that traverses it from above to below, and in which glides the 
inferior tendon of the external flexor of the metacarpus. Its internal face, 
smooth and concave, concurs to form the external wall of the carpal sheath. 
The circumference presents, in front, two articular facets: the superior, 
concave, corresponds to the radius; the inferior, convex, is in contact with 
the second bone of the upper row. 

The other three bones of this row increase in volume from without to 
within. 

The second, or os pyramidalis (or cuneiform), responds to the radius, 
the first bone of the lower row, the third of the upper, and the supercarpal 
bone ; it has in all five articular facets. . . 

The third, or os semilunare (lunare), has six facets, and is united below to 
the first and second bones of the second row. 


1 The analogue of the trapezium of Man is not found in the Horse. According to M. 
Lavocat, we ought to regard as such a small supernumerary bone sometimes seen articu- 
lating behind the third bone. We are entirely of his opinion. (Leyh jis also of this 
opinion, and states that this supernumerary bone is more frequently found in large 
common-bred horses. Stubbs, in his old, but fine ‘ Anatomy of the Horse, does not refer to 
it, but describes the seventh bone as the pisiform. Percivall says the supernumerary bone 
is not invariably present, and that sometimes two are found. He designates Stubbs’ and 
Chauveau’s pisiform bone as the trapezium. Girard nameg tie supernumerary bone the 
“pisiform” or pea-shaped. When one or more of these osseous nodules are present, they 
represent the pollex and fifth digit of the human hand.) 


80 THE BONES. 


3 : ly 
The fourth, or os scaphoides, the most voluminous of the row, has only. 
four ee and sriculates by its inferior face with the os magnum and 


ides. 
rE Collectively, the second, third, and fourth bones of the upper row form 


ticular surfaces. _ - ; ; : 
eee or radial articular surface, is very irregular; but in ex- 
amining it from without to within there may be observed: 1, A glenoid 
cavity on the pyramidal bone ; 2, In front, a transversely-elongated condyle 


Fig. 45. Fig. 46. 


POSTERIOR VIEW OF THE RIGHT FRONT VIEW OF RIGHT CARPUS. 
: CARPUS. 1, Second of upper row, or cuneiform ; 
1, Second cuneiform, or pyramidalis; 2, 2, Third, or lunare; 3, Fourth, or 
Third, or lunare; 3, Fourth, or sca- scaphiides; 4, First, supercarpal, or 
phiéides; 4, First, supercarpal, pisiform, trapezium; 5, First of second row, or 
or trapezium; 5, First of lower row, unciform; 6, Second, or magnum; 
or unciform; 6, Second, or magnum; 7, Third, or trapezoides. 


7, Third, or trapezoides; *, *, Small 
metacarpal bones, 


on the semilunar and scaphoid bones; 3, A groove placed behind the pre- 
ceding condyle. . 

_ The inferior articulating surface, which corresponds to the second row, 
is constituted by several undulated facets; it is convex outwardly and in 
front, concave posteriorly and inwardly. 

Bones or THE Inrerion on Mrtacarpan Row.—The thickness of these 
bones decreases from without to within. 

The first, uneiform, or hookbone (0s hamatum), has four diarthrodial 
facets, and responds, above, to the two first bones of the superior row; 
below, to the first and second metacarpals. : 

The second, os magnum, or os capitatum, the largest, has seven articular 
facets, three of which are on the interno-lateral face. It articulates, above, 


THE ANTERIOR LIMBS. 


with the" semilunar and scaphoides; below, 
and the internal rudimentary metacarpal. 


81 


with the principal metacarpal 


é The third, or trapezoides, the smallest, is provided with five facets, and 
is In contact with the scaphoides above, and the middle and internal meta- 


-carpals below. 

Collectively, these bones of the lower row form two 
large diarthrodial surfaces. The upper surface responds 
to the bones of the upper row, and is constituted in front, 
and from without to within, by a small condyle and two 
glenoid cavities; behind, by two isolated condyles, 
formed by the os magnum and the trapezoides. The 
inferior articular surface is only formed by more or less 
long and plane facets, which incline towards each other. 
It corresponds to the three portions of the metacarpus. 

Structure and development.—Hach carpal bone is 
formed by a nucleus of close spongy substance enveloped 
in a layer of compact tissue. . Hach is developed from 
a single centre of ossification. 


2. Metacarpal Bones. 


In Solipeds, the metacarpus is composed of three 
bones, named the “ metacarpals,” standing parallel to each 
other. These are the principal metacarpal and the two 
rudimentary metacarpals, an external and. internal. 

Principat Mrtacarpat.—This is a long cylindrical 
bone, situated vertically between the carpus and the 
digital region. 

Body.—The body is a little depressed before and 
behind, a disposition which permits it to be described 
as having two faces and two borders. The anterior face 
is perfectly smooth and rounded from side to side. The 
posterior face is flat, and exhibits: 1, Towards the upper 
third, the nutritive foramen of the bone; 2, On the 
sides, two narrow, roughened surfaces, parallel and elon- 
gated. vertically, commencing near the superior extremity 
to disappear a little below the middle of the bone; these 
surfaces are held in apposition with the rudimentary 
metacarpals by means of an interosseous ligament which 
is often ossified in old horses. The borders, external and 
internal, are very thick, round, and smooth, like the an- 
terior face. : 

_ Extremities —The superior is flattened before and 
behind, and presents: 1, Above, an undulating articu- 
latory surface, formed by the union of several flat 
facets more or less inclined on one another: they 
respond to all the lower row of carpal bones; 2. An- 
teriorly and inwardly, a tuberosity for muscular inser- 
tion; 3, Posteriorly, and directly above the roughened 


POSTERIOR VIEW OF 
RIGHT METACARPUS. 


1, Head of large meta- 
carpal bone for ar- 
ticulation with the 
trapezoides, mag- 
num, and unciform ; 
2, Inner splint, or 
small metacarpal 
bone, for articula- 
tion with the trape- 
zoides; 4, Scabrous 
surface for the at- 
tachment of the sus- 
pensory ligament ; 
5, Nutrient fora- 
men; 6, Median 
ridge separating the 
two inferior con- 
dyles. 


surfaces of the posterior face, four small diarthrodial facets in pairs, and 
running into the larger ‘articular surface by their superior border: they are 


adapted to similar facets on the rudimentary metacarpals. 
— corresponds to the first phalanx and the 


extremity, elongated transversely, 


The inferior 


large sesamoids by an articular surface, convex from before to behind, which 


82 THE BONES. 


is composed of two lateral condyles separated by a median spine. The two 
condyles would be exactly alike, if the antero-posterior diameter of the 
external condyle was not less extensive than that of the opposite condyle. 
Both are hollowed on the sides by an excavation for the attachment of 
ligamentous fasciculi. . 

Structure and development—The principe’ metacarpal is one of the 
most compact bones in the body. It is developed from two centres of 
ossification, one of which is for the inferior extremity. 

Rupimentary Meracarpars.—The two rudimentary (small) metacarpal 
(or splint) bones are elongated, and placed against the posterior face of the 
principal bone, one without, the other within. Each is in the form of an 
inverted pyramid, and exhibits a middle part and two extremities. 

Middle portion.— Prismatic and triangular, this offers: 1, Three faces,—an 
external, smooth and rounded from one border to the other; an énternal, 
plane, and equally smooth; an anterior, covered with asperities to give 
attachment to the interosseous ligament uniting the lateral metacarpal bone 
to the median; 2, Three salient borders which markedly separate the faces 
from each other. 

Extremities —The superior, the largest, is named the head, and shows: above, 
a diarthrodial facet which corresponds to one or two bones of the inferior row 
of the carpus; in front, other two small facets continuous with the pre- 
ceding, and in contact with similar facets on the median metacarpal bone; 
on the other points of its periphery are rugosities for the attachment of 
ligamentous and tendinous fibres. The inferior extremity only reaches to 
about the lower fourth of the large metacarpal bone, and terminates in a 
small enlargement or button, which is never consolidated with the latter. 

The two lateral metacarpals, although very much alike, may yet be 
easily distinguished from each other. For instance, the internal bone is 
always the thickest and often the longest; besides, the superior articular 
surface of its head results from the union of the two facets corresponding 
to the two last carpal bones of the lower tier. 

Structure and development.—Of a somewhat compact texture, like all 
the long bones, these have no medullary canal, and are developed from only 
one ossific centre. Not unfrequently, however, the tubercle is formed from 
a special centre. 


38. Bones of the Phalangeal Region or Digit. 


Solipeds have only one digit, supported by the principal metacarpal bone, 
and composed of three pieces placed end to end, one upon another. The 
first comprises three bones: a principal, the first phalanx, and two com- 
plementary ones, the sesamoids. The second is formed by the second 
phalanx, and the last, which terminates the limb, is constituted by the 
third phalanx and an accessory bone which has received the name of the 
small sesamoid (navicular bone). 

First (proxtmaL) on Meracarpat Paananx.—The first phalanx (or 


pastern bone), the smallest of all the long bones, is situated in an oblique ~ 


direction from above downwards, and behind to before, between the principal 
metacarpal and the second phalanx. : 

Body.—Depressed in front and behind, this bone exhibits: an anterior 
face, round from one side to the other, and slightly roughened above and 
below; a posterior face, flat, covered with ligamentous imprints in the form 
ofa triangle with the base reversed ; two lateral borders, thick, rounded, and 
provided with some imprints, 


THE ANTERIOR LIMBS. 8&3 


Extremities —The superior, the largest, presents: Above i 
surface adapted to the inferior snetecatpal se and sonsequently el 
of two glenoid cavities separated by a groove running from front to ite 
laterally, and a little posteriorly, a well-defined tubercle of insertion. The 
inferior extremity has a transversely elongated articular surface to cor- 
respond to the second phalanx; this surface is formed by two condyles 
separated by a middle groove, and surmounted laterally by a small 
tuberosity for ligamentous insertions. The external condyle is smaller 


id 


Fig. 48. Fig. 49. 


LATERAL VIEW OF THE DIGITAL 
REGION 3 OUTSIDE OF RIGHT LIMB. 

1, Large metacarpal bone; 2, 3, Outer 
and inner sesamoids ; 4, First, proximal, 
suffraginis or metacarpal phalanx, 5, 
Its posterior surface; 6, Tuberosity for 
ligamentous insertion; 7, Inner condyle 
of ditto; 8, Eminences on second pha- 
janx for attachment of lateral liga- 
ment; 9, Smooth surface for passage 
of deep flexor tendon on second pha- 
lanx; 10, Imprint for the insertion of 
the terminal branch of the perforatus 
tendon; 11, Navicular bone; 12, Third 
phalanx, pedal, or coffin bone; 13, Its 
basilar process. 


POSTERIOR VIEW OF FRONT DIGITAL 
REGION. 

1, Large metacarpal bone; 2, 3, Outer 
and inner splint bones; 4, 5, Sesamoid 
bones; 6, Suffraginis; 7, 8, Tuberosi- 
ties for insertion of crucial ligaments ; 
9, Triangular space for insertion of 
short sesamoid ligament; 10, Anterior 
face of suffraginis; 11, 12, Tuberosities 
for ligamentory insertion; 13, Articu- 
lar depression separating condyles; 14, 
15, Second phalanx; 16, Scabrous sur- 
face for ligamentous attachment; 17, 
Smooth surface for gliding of deep 
flexor tendon; 18, Navicular bone; 
19, Pedal bone; 20, Basilar process ; 
21, Plantar foramen. 


than the internal, and when the bone is placed upon a horizontal plane, 
the anterior face turned upwards, it only touches by three points—the two 
tubercles of the upper extremity and the internal condyle; by pressing on 
the external condyle, it is easy to make the bone rock. 

The first phalanx is a very compact bone, and is developed from two 
points, one of which is for the superior extremity alone. 


84 THE BONES. 


Susamors.—These are two small short bones placed side by side behind 
the superior extremity of the first phalanx, whose articular surface it 
completes, as it has not extent enough to be exactly adapted to the 
metacarpal surface. Each of these bones represents a small, irregularly- 
shaped polyhedron, or rather, a short trifacial pyramid. It otters : an 
anterior face, which is articular, and corresponding to the inferior extremity 
of the principal metacarpal bone, moulded, as it were, on one of the condyles 
and one of the sides of the median ridge; a posterior face, covered with 
cartilage in the fresh state, and forming, with that of the opposite bone, 
a gliding concave surface for the flexor tendons of the phalanges ; a lateral 
face, studded with ligamentous imprints; a summit, directed upwards ; and a 
base, turned downwards, and serving for the attachment of several ligaments. 

Seconp (on Mrippie) Paaranx (Os Corona, Smatu Pastern Bonz).— 
This is a short bone, situated in the same oblique direction as the first 
phalanx, and between it and the third. Its general form is that of a cube 
flattened before and behind, and offering the following features: an anterior 
face, covered with some slight imprints; a posterior face, provided, above, 
with a transversely elongated gliding surface; a superior face, channeled 
by two glenoid cavities, to match the inferior articulating surface of the 
first phalanx; an inferior face, formed on the same plan as the last, being 
occupied by two unequal condyles which articulate with the third phalanx 
and the navicular bone ; two laterul faces exhibiting a very marked imprint. 
In the interior of this bone is found a nucleus of very condensed spongy 
substance, enveloped in a layer of compact tissue. It is usually developed 
from a single centre of ossification; though in many subjects there is a 
complementary nucleus for the superior articular surface and the posterior 
gliding surface. 

Tarp (Disra) PHatanx, Os Pepis (orn Pepa Bonn).—This is a short 
bone which terminates the digit, and sustains the hoof’ that incloses it and 
the navicular bone. When completed by a special fibro-cartilaginous apparatus, 
it represents the segment of a very short cone, obliquely truncated behind, 
from the summit to the base. It offers for study: three faces, three borders, 
and two lateral angles 

Faces.—The anterior, convex from side to side, and cribbled by porosities 
and vascular openings, shows on each side: 1, 
The preplantar fissure, a horizontal groove more 
or less ramified, which commences behind, 
between the retrossal and basilar processes, ter- 
minating in front in one of the foramina which 
penetrate the bone; 2, The patilobe eminence, a 
roughened projecting surface, situated between the 
preceding fissure and the inferior border of the 
bone. The superior face is occupied by an articu- 
lar surface formed by two glenoid cavities and a 
slight median ridge ; it comes in apposition with 
PLANTAR surFacr or turrp the inferior face of the second phalanx. The 

PHALANX. inferior (or solar) face, hollowed out like an arch, 

1, Lower face, or sole; 2, 3, is divided into two regions by the semilunar crest, 

Wings, or retrossal pro- a salient line which describes a curve forwards. 
pease’ internal. borders phe anterior xegion j f i 

5, Plantar faremiine, an gion 1s perforated with very fine 

porosities, and corresponds to that part of the 

hoof named the sole. The posterior region shows, immediately behind the 

semilunar crest, a median imprint, and two lateral channels designated the 


Fig. 50. 


THE ANTERIOR LIMBS. 85 


plantar Jissures. These originate at the root of the basilar process, are 
directed obliquely downwards and inwards, and open into the plantar jora- 
mana, the external orifices of two large canals which enter the bone and unite 
in its interior to form the semilunar sinus, 

Borders.—The superior describes a curve, with the convexity forward, 
and presents: 1, In its middle, the pyramidal eminence of the os pedis, a 
single triangular process, flat before and behind, roughened on its anterior 
aspect, and concurring, by its posterior surface, to form the articular surface 
which responds to that of the second phalanx, 2, Laterally, two facets of 
insertion which encroach on the anterior surface, and even advance, 
posteriorly, nearly to the preplantar fissure. The inferior border is thin, 
dentated, convex, and semicircular; it is perforated by from five to ten 
large foramina which pass into the bone. ‘The posterior border is slightly 
concave ; on it is observed a very narrow, transversely elongated, diarthrodial 
facet, which becomes confounded with the superior large articular surface, 
and is adapted to a similar facet on the navicular bone. 

Lateral angles.—These are two projections directed backwards, on whose 
summit the three borders of the bone unite, and which gives attachment 
to the later fibro-cartilages. A deep notch, the origin of the preplantar’ 
fissure, separates each into two particular eminences: one, the superior, 
named by M. Bouley the basilar process ; the other, the inferior, prolonged 
behind, and designated by Bracy Clark the retrossal process, from retro, 
behind, and ossa, bone. 

Structure.—The os pedis exhibits in its interior the semilunar sinus, a 
cylindrical, transversely elongated, and semicircular cavity resulting from 
the arching anastomoses of the two plantar carals. From this cavity pass 
off numerous channels, which anastomose frequently with each other, and 
open externally by the foramina on the anterior face of the bone, or by 
those on its inferior border. The os pedis has for its base a nucleus of 
spongy substance, surrounded by a layer of compact tissue. The latter is 
thicker towards the pyramidal eminence than elsewhere, and sends into 
the interior numerous prolongations which form the walls of the semilunar 
sinus, as well as the bony channels which spring from it. 

Development.—The third phalanx, formed from a single nucleus of 
ossification, undergoes numerous changes in its configuration during life. 
Thus, in the young animal the lateral angles are thick, obtuse, and but 
little prolonged posteriorly ; but as it grows older, they increase in length 
and become salient. The development they then assume is due to the 
progressive ossification of the lateral cartilages implanted on their surface. 
It often happens, in very old horses, that this ossifying process is carried 
to an extreme degree, and nearly the whole substance of these complementary 
organs is invaded. From the commencement, its inevitable result is to 
convert the notch which separates the basilar from the retrossal process 
into a foramen. : 

The complementary fibro-cartilaginous apparatus of the os pedis.—To 
understand properly the disposition of this portion of the foot, it is necessary 
that a previous knowledge of the ligaments and tendons attached to the os 
pedis should have been obtained ; therefore a detailed description will only 
be given when the Horse’s foot is studied as a whole. It will be svfiicient 
here to state that this apparatus consists of two lateral pieces, tho fibro- 
cartilages of the os pedis, united behind and below by the plantar cushion, a 
fibrous and elastic mass on which rests the navicular bone through the 
medium of the perforans tendon. 

9 


86 THE BONES. 


Tus Smatt Szsamorp (orn NavicuLar) Boyz.—This short bone is annexed 
to the third phalanx, behind which it is situated ; it is elongated transversely, 
flattened above and below, and narrowed at its extremities. It offers: 1A 
superior face, on which are prolonged the glenoid cavities and the median ridge 
of the articular surface of the os pedis; it responds to the second phalanx ; 

Fig. 51 2, An inferior face, divided by a 

é 9 . slight relief into two undulated 

/ i sug facets, and covered with cartilage 

Cp La a to form a gliding surface; 3, An 

Wiis aS anterior border, channeled length- 

“% ways by a groove of insertion, above 

SAGTGUE AR BROWNE which is remarked a diarthrodial 

u, Upper, or articular surface ; b, inferior border ; facet that brings the small sesa- 

v, Superior border; d, Inferior, or posterior moid into contact with the pos- 

surface; e, The median transverse ridge; f, terior border of the third phalanx; 

Interior margin; g, Superior margin. 4, A posterior border and two ex- 

tremities, for ligamentous insertion. This bone, as well as the sesamoids, 

originates from a single centre of ossification. It is formed of a layer of 
compact tissue enveloping a nucleus of very condensed spongy substance. 


DIFFERENTIAL CHARACTERS OF THE ANTERIOR LIMB IN OTHER THAN SOLLPED 
ANIMALS. 


A, Suoutper.—In Carnivora the shoulder is composed of two bones, these creatures 
being furnished with a clavicle. This bone in the Dog is a little osseous shell inbedded 
among the muscles situated in front of the scapulo-humeral angle. That of the Cat 
constitutes a small styloid bone, which is jcined to the acromion and steruum by two 
ligamentous cords. 

In all the domesticated animals except Solipeds, the coracoid process is immediately 
applied against the glenoid cavity. In all, also, with the exception of the Pig, the 
scapular spine gradually rises from above to below, and terminates in a sharp salient 
point, the acromion. 

The spine partitions the external face of the bone into two equal fosse in the Dog, 
and in Ruminants into two fossee, which, for extent, are a3 one to three to each other. 
The scapular spine of the Pig is much elevated towards the middle part, and bends more 
or less backwards, 

In the Carnivora the prolonging cartilage is entirely absent; the anterior border of 
the scapula is very convex, as if the bone had bees curved downwards. In the other 
domesticated mammals the scapula is somewhat regularly triangular. 

B. Arm.—Proportionately, the humerus is longer, and more inflected like an S, as 
the number of apparent digits is increased. Therefore it is that in the Carnivora the 
characters of length and inflexion are most marked. 

In the Ux, Sheep, Pig, and Dog, the furrow of torsion is not so deep as in the Horse, 
and the deltoid imprint is less salient. In the Dog this imprint is represented hy a large 
roughened surface; in the Pig by some asperitics only. The nutrient foramen is on 
the posterior face, It has been stated that the medullary canal in the Ox is traversed by 
an osseous band; but the presence of this is not constant. : 

The summit of the trochiter 18 very elevated, particularly in Ruminants, and is thrown 
back on the bicipital groove, which is single; in the Dog and Pig, this groove is carried 
inwards above the internil face of the humerus. 

The external trochlea in the Ox and Pég is well marked. In Carnivora, the inner lip 
of this trochlea is very high, and the external lip incomplete; a foramen establishes 
communication between the olecranian and coronoid fosse. In the Cat there is found, on 
the inner side of the lower extremity, a particular foramen that forms a vascular arch. 

C, Fore-arm.—The fore-arm is short in the Ox, Sheep, and Pig; very long in the 
Carnivora. The principal differential characters that it presents are connected with the 
relative dimensions of the two bones and their mode of union. Regarding these, and as 
generally applicable, the following principles may be laid down :— 

1. The development of the ulna is in direct relation to the division of the foot.—Mono- 
dactylous animal, such as the Horse, Ass, and Mule, have in fact only a rudimentary 


THE ANTERIOR LIMBS. 


87 


ulna. In the pentadactylous animals, as Man, the Cat, etc, on ane: 
the contrary, this is » veritable long bone which equals, or even Fig. 52, 
’ exceeds, the radius in volume. 

: 2. The closeness of union between the radius and ulna is in 
increased proportion as the animal exclusively employs its inferior 
extremity for standing or walking.—Thus, in Solipeds and Rumi- 
nants, and Pachyderms in general, the two bones are consolidated 
or at least united, by an interosseous ligament, and in so firm a 
manner that they can only execute very obscure movements on 
each other. The anterior limb of these animals is indeed only 
used to support the body on the ground. In those, on the con- 
trary, which may employ it to dig up the soil, climb on trees, etc., 
‘or as an organ of prehension, the radius and ulna are merely 
joined at their extremities by an articulation, which permits them 
to move upon one another with the greatest facility. Rodents, the 
majority of the Carnivora, and the quadrumana, are so provided ; 
but it is in Man that the relative independence of the two bones is 
carried to the highest degree. No animal can so easily execute 
the movements of pronation and supination of the hand, which 
are determined by the play of the two bones of the fore-arm on 
each other. 

To the indication of these fundamental characters may be 

added some details on a few particular and important points. 
_ In all the domesticated animals other than Solipeds, the ulna 
is developed from three ossifying centres, extends the whole length 
of the radius, and concurs to form the articular surface correspond- 
ing to the carpal bones. It is an elongated bone in Ruminants, 
and a long bone, hollowed by a medullary canal, in the Pig and 
Carnivora. 

The inferior articular surface of the bone of the fore-arm in , ~ 
Ruminants is cut obliquely from above to below, and from with- 4 
out to within. In these animals we find the radius very flat from 
before to behind, the bicipital tuberosity scarcely noticeable, and 
two radio-ulnar arcades united externally by a deep fissure. The 
union of the two bones is more intimate than in the Horse, for the 
ossification always finishes by invading that portion of the inter- 
osseous ligament placed above the superior vascular arcade. 

In the Pig, the ulna is flattened from before to behind, and 
spread out on the posterior face of the radius, which it almost 
completely covers. Its olecranon is very prominent. In the Dog 
and Cat, the two hones of the fore-arm are nearly equal in volume, 
and are slightly crossed in an X fashion. The superior extremity 
of the ulna is thicker than its lower extremity; it is nearly the 
opposite of this in the radius. Movable on one another, these 
‘bones only touch by their extremities, and to this effect offer: A 
Above, on the ulna, concave articular surface, the small sig- 
moid cavity, and on the radius a rounded hinge-like facet; 2, 
‘Below, on the radius, a concave surface, and on the ulna a convex 
one. 

'‘D. Fore-Foor, on BAND.—1. Carpal bones.—The carpus of the 
Pig, like that of Man, contains eight bones—four in each of the 
rows. ‘The second bone of the upper row corresponds with the ulna, 
and to a small extent with the radius. In the bones of the lower 
‘row, it is observed that the first corresponds with the two external 
‘metacarpals, the second with the great internal metacarpal, the third 
with the preceding and the small internal metacarpal. The fourth, 
or trapezium, terminates inferiorly by a blunt point, and has no 

‘relations with the metacarpal bones, because the thumb is entirely 
undeveloped in this animal. 


‘1, Olecranon ; 2, Body of the ulna; 3, Body of the radius; 4, 5, 6, 
First, second, and third bones of the upper row of the carpus; 7, 8, 
First and second bones of the lower row ; oy, Rudimentary metacar- FORE-ARM AND FOOT 
pals; 10, Principal metacarpals; 11, External digit; 12, Internal OF THEOX; FRONT 

“digit. : VIEW. 


88 THE BONES. 

In the Cat there are also eight bones. The second, or pyramidalis, of the upper row 
is very developed; it occupies all the external border of the carpus, and articulates with 
the ulna, the first bone of the second row, and the first metacarpal. The supercarpal 
bone, elongated, prismatic, and thickened at its extremities, offers in front two coalescing 
articular facets, one to correspond with the ulna, the other to join the pyramédalis, 
The bones of the inferior row decrease in thickness from the first to the fourth, and 
correspond: the first, to the first and second meticarpals; the second, to the metacarpal 


3a 


FORE-ARM AND FOOT OF 


THE DOG; ANTERIOR 
FACE. 

1, First digit; 2, Second 
digit; 3, Third digit; 
4, Fourth digit; 5, 
Thumb; 6, 7, 8, 9, First 
second, third, and fourth 
bones of the lower row 
of carpal bones; 10, 11, 
First and second bones 
of the upper‘row; 12, 
Supercarpal bones 13, 
Body of the ulna; 14, 
Apex of the olecranon ; 
15, Beak of the olecra- 
non; 16, Body of the 
radius, 


of the third digit; the third, to that of the fourth digit; the 
fourth, to the metacarpal of the thumb. 

In the Dog there are only seven bones, as the scaphoid 
and semilunar bones are united, but the general disposition 
is the same as that in the Cut. 

Lastly, in the Ox and Sheep the carpus is only composed 
of six bones: four in the upper row, and only two in the 
lower, where the os magnum and trapezvides are consolidated. 
The supercarpal bone has no groove for gliding, and the 
pyramidalis articulates with the radius and cubitus. The 
bones of the lower row only articulate with the principal 
metacarpal bone. (Professor Gobaux, in 1865, exhibited 
specimens which go to prove that of the two bones of the 
lower row in the carpus of Ruminants, the internal really 
represents two; so that these animals actually have seven 
carpal bones like the Horse.) 

2. Metacarpal bones—Vhe number of metacarpal bones 
varies much in the domesticated animals :— 


In the Carnivora thereare. . . . . 5 
Inthe Pigthereare. . . . . .. 4 
In Ruminants thereare. . . . . . 2 


The five metacarpals of the Dog and Cat articulate with 
each other, at their superior extremities, by lateral facets; 
they offer, at their inferior extremity, a condyle prolonged 
backwards by an articular surface resembling that of the 
Horse. The middle two are always longer than the two 
lateral. The smallest belongs to the fifth digit, or thumb, 
and is terminated inferiorly by a trochlea. 

The four metacarpals of the Pig articulate with each other, 
as in the Carnivora. The second and third are larger than the 
first and fourth. The fifth metacarpal is not developed. 

In Ruminants the metacarpal bones are two in number: 
a principal, which itself results from the consolidation of the 
second and third metacarpals, and another altogether rudi- 
mentary. 

The principal metacarpal is channeled on its anterior face, 
and for its whole length, by a deep vascular fissure—a trace 
of the primitive separation of the bone in two pieces. This 
fissure presents, inferiorly, the anterior orifice of a canal that 
completly traverses the bone. The posterior face is also 
marked by a very slight longitudinal groove. Tlie superior 
extremity exhibits, externally and posteriorly, « single diar- 
throdial facet for the articulation of the rudimentary meta- 
carpal. The inferior extremity is divided by a deep notch 
into two articular surfaces, which together resemble the single 
surface in the Horse; each corresponds to one of the digits; 
the external is always smaller than the internal. In the 
foetus, the two long bones that form the great metacarpal 
are simply laid together, and their medullary canals are sepa- 
rated from each other by the double partition which results 
from this apposition ; after their coalescence, however, the par- 
titions are completely destroyed by resorption, and in a short 
time there is only a single medullary canal for the entire bone. 

The rudimentary metacarpal is only a small osseous stylet, 
articulating, by a diarthrodial facet, behind and to the outside 
of the superior extremity of the principal metacarpal; it is 


sometimes absent in the Sheep and Goat. 


THE ANTERIOR LIMBS. 89 


fan Digital Region.—In the domesticated animals the number of complete digits is as 
Carnivora. . . . . 5 
Pig. 2... 4 
Ruminants. . . . . 2 


The five digits of the Dog and Cat are exactly analogous to those of Man. Thus, the 
external corresponds to the auricularis, the second to the annularis, the third to the 
medius, the fourth to the index, and the internal to the thumb.—The latter, very small. 
has only two phalanges and does not come into contact with the ground. Each of the 
first four is composed: 1, Of a first phulanx, to which are annexed two sesamoids; 
2, A second phalanx, which yet represents a veritable long bone; 3, A conical phalan- 
gette, pointed, bent downwards, and hollowed at its base by a circular groove, in which 
is lodged the matrix of the claw. ‘The small sesamoid (or navicular bone) is absent, but 
is replaced by a prominence of the ungual phalanx. The auricularis and index are 
alike, and not so long as the annularis and medius, which are the same in length. 

The Pig has four complete digits articulating from the metacarpals; the thumb is 
absent. The index and auricularis, or fourth and fifth digits, are short, and do not 
usually rest on the ground. 

Ruminants certainly possess four digits, but only two are perfect—the medius and 
annularis—and. these articulate with the inferior extremity of the principal metacarpal. 
The two others—the index and awuricularis - are in a rudimentary condition, and are 
represented by two small.bones situated above and behind the metacarpo-phalangeal 
articulation. __ 

In the Oz, Sheep, and Goat, each of the perfect digits comprises three phalanges and 
three sesamoids. 

The first phalanz fairly represents the moiety 
of the phalanx in the Horse. It has no posterior 
imprints, but shows them on its inner surface us 
for the attachment of several ligaments. This 
internal face is plane, and the external convex; 
these characters are repeated in the other two 
phalanges. It is also remarked in all the plia- 
langeal bones, that the external articular facet 
of the extremities is always larger than the 
internal, Of the two sesamoids, the external is 
larger and less elongated than the internal. 
first particulate witi each other, and with the 
They halanx by small diarthrodial facets. 

The second phalanx is hollowed internally 
by a small medullary cavity. 

The ungual phalanx, as a whole, resembles 
one of the lateral moieties of the os pedis of 
solipeds. This phalanx has no complementary 
fibro-cartilage, basilar process, or retrossal emi- 
nence, nor yet a cavity of insertion on the sides 
of the pyramidal eminence. The semilunar 
crest is replaced by an obtuse, thick, and rugged 
relief, which occupies quite the posterior limit 
of the inferior face of the bone. Three large 7 
canals penetrate the third phalanx, two to the woman sCAPULA; EXTERNAL ASPECT. 
base of the pyramidal eminence, and one towards 
the origin of the preplantar fissure. They form, 
in the interior of the bone, a vast sinus, giving 
rise to several vascular canals which open on the 
surface. There is only one foramen at the base of 
the pyramidal eminence in thesmaller Ruminants. 


Fig. 54, 


a. {)))) 
2), am IS 


1, Supraspinous fossa; 2, Infraspinous 
fossa; 3, Superior border; 4, Supra- 
scapular notch ; 5, Anterior or axillary 
border ; 6, Head of the scapular and 
glenoid cavity; 7, Inferior angle; 8, 
Neck of the scapula; 9, Posterior 
border; 10, Spine; 11, Triangular 

COMPARISON OF THE THORACIC LIMB OF MAN WITH smooth surface, over which the tendon 

THAT OF THE DOMESTICATED ANIMALS. of the trapezius glides, with the tuber- 


i it and 

A. Suoriper.—The shoulder of man (fig. 54) culum spina scapula between it an 

has for its base two well-developed bones, the 103 12, Acromion process; 13, Nutrient 
scapula and clavicle. The scapula is more dig- foramen, 14, Coracoid process. 
tinctly triangular than that of all the domesti- ; r ' 

cated animals; its vertebral border is also more extensive. The scapular spine, very 


90 THE BONES. 


elevated, is followed by an acromion who 
humeral articulation. The latter is separa 
constriction called the pedicle of the acromion. 
resembles a semi-flexed finger. The clavicle e 


it is flattened above and below, and flexed 
n the male than the female. 


clavicle is more pronounced i 


like an italic S. 


se extremity reaches to above the. scapulo- 
ted from the remainder of the spine by a 


The cvracoid process is voluminous, and 


xtends from the acromion to the sternum ; 


This inflexion of the 


B. Anw.—The humerus of Man is much longer than that of animals. Its diaphysis 


is prismatic and divisible into three faces; 


the deltoid imprint has the form of a V with 


its point directed downwards, The voluminous articular head is turned inwards; the 


Fig. 55. 


RIGHT HUMAN HUMERUS; ANTERIOR 
SURFACE, 

1, Shaft; 2, Head; 3, Neck; 4, Greater 
tuberosity; 5, Lesser tuberosity ; 6, Bici- 
pital groove; 7, Interior bicipital groove ; 
8, Posterior bicipital ridge; 9, Rough sur- 
face for insertion of deltoid; 10, Nutrient 
foramen; 11, Eminentia capitata; 12, 
Trochlea; 13, External condyle; 14, In- 
ternal condyle; 15, External condyloid 
ridge; 16, Internal condyloid ridge; 17, 
Fossa for the coronoid process of ulna. 


Fig. 56. 


HUMAN ARM-BONES; FRONT VIEW. j 


1, Shaft of ulna; 2, Greater sigmoid 


notch; 3, Lesser sigmoid notch; 4. Ole- 
eranon process; 5, Coronoid process; 6; 
Nutrient foramen; 7, Ridges for inser- 
tion of interosseous membrane; 8, Capi- 
talum ulne; 9, Styloid process; 10, 
Shaft. of radius; 11, Its head; 12, Its 
neck; 13, Its tuberosity; 14, Oblique 
line; 15, Lower end of bone; 16, Styloid 
process.. , 


bicipital groove is single, and looks outwards. The inferior arti 
that of animals, expert that the condyle is more distinct. siete aca 
C. Forz-arm.—The two bones of the fore-arm, as we have already seen, only articu- 
late by their extremities; they are separated from one another in their middle part. 
The superior extremity of the radius corresponds to the condyle of the humerus; that of 
the ulna articulates with the humeral trochlea. The coronoid process belongs to the 
ulna. At the lower extremity of the fore-arm it is remarked: 1, That the radius cor- 
responds to the greater portion of the carpus, while the ulna only articulates with the 
pyramidalis; 2, That the radio-carpal articulation is protected outwardly and inwardly 
by two small osseoug prolongations, the styloid processes of the ulna and radius. 
D. Hanp.—1. Carpus.—The carpus of Man is composed of eight bones—four in-each 


THE POSTERIOR LIMBS 91° 


row. The three first of the upper row articulate with the radius; the fourth responds 
to the ulna, In the bones of the lower row, the trapezium responds to the metacarpal 
of the thumb and that of the index. the trapezoides tu the latter only, the os magnum 
and uuciform to the metacarpals of the medius, annularis, and little finger. “The 
pisiform bone and the cuneiform process of the unciform convert the posterior face of the 
carpus into a channel. 

2. Metacarpus.—The five metacarpals of Man are parallel to each other, and articulate 
by their superior extremities with the bones of the car- 
pus; by their inferior extremities with the phalanges. 
They are all concave in their middle portion, and 
thickened at their ends. The metacarpal of the thumb 
is the shortest and strongest. The others diminish in 
volume from the fourth to the first. 

3. Digital RegionHere we find five digits, each 
composed of three bony columnettes, with the exception 
of the thumb, in which only the second and third pha- 
langes are present. They decrease in length from the 
third to the first, and the third to the fifth. The first 
and second phalanges are small semicylindrical bones, 
slightly thickened at their extremities. The ungueal 
phalanges are constricted in their middle, and widened 
like a horse-shoe at their inferior extremity; the palmar 
face is roughened, the dorsal face smooth. 


ARTICLE V.—PostTERIor Limes. 


Each of these is divided, as already noted, 
into four secondary regions: the pelvis, thigh, 
leg, and foot. 


PELVIS, 


The pelvis is a kind of bony cavity formed PALMAR SURE ACE OSULEND 
by the union of the sacrum with two lateral a 
: 5 . +41, 1, Scaphoid bone; 2, Semilunare; 
pieces, the coxw, which are-consolidated with “’s “Cuneiform; '4, Pisiform; 5, 
each other in the inferior median line. The Trapezium 5 6, Groove in tia 
description of the sacrum having been already  pezium for tendon of flexor 


iven, it now remains to speak of the coxa. carpi radialis; 7, Trapezoides s 
BAYER P 8, Magnum ; 9, Unciform ; 10, 
A. Coxa 10, The five metacarpal bones; 


11, 11, First row of phalanges ; 

The coxa, also designated os liacum, os inno- 12, 12, Second row; 13, 13, 
eas is a very irregularly-shaped flat bone, fae We Eee et 

ouble (with its fellow on the opposite side),  jast phalanx, > 
and directed obliquely from above to below and 
before to behind.: It is contracted in its middle part, which presents exter- 
nally an articular cavity, the cotyloid ; anteriorly, where it rests on the 
sacrum, it becomes widened, as it also does in its posterior portion, which 
is inflected inwards to be united, on the median line, with the bone of 
the opposite side. 

It is divided, in the foetus, into three distinct pieces, joined by cartilage 
in the centre of the cotyloid cavity, which the three concur in forming. 
Although they soon become consolidated into a single piece, it is customary 
to describe them as so many separate bones by the names of ilium, pubis, and 
ischium. 

In1um.—The ilium, a flat and triangular bone, curved on itself, directed 
obliquely from above to below, before to behind, and within outwards, forms 
the anterior portion of the coxa which corresponds with the sacrum. It is 
the most considerable of the three divisions, and has two faces, three borders, 
and three angles. 


92 THE BONES. 


Faces.—The external or superior face, studded with some muscular 
imprints, is excavated on both sides, and is named the eaternal iliac fosssa, 
The internal or inferior face offers for study: 1, An external portion, 
smooth, and crossed by some vascular grooves; this is the iliac surface, 
which is replaced in Man by an excavation called the internal iliac fossa ; 
2, An internal portion, roughened and uneven, presents, posteriorly, the 
auricular facet, an irregular diarthrodial surface, elongated from side to 
side, a little oblique in front and inwards, and responding to an analogous 
surface on the sacrum. ; 

Borders.—The anterior border, or crest of the ilium, is slightly concave, 


Fig. 58. 


THE COX; SEEN FROM BELOW. 


1, liae surface; 2, Auricular facet; 3, Angle or crest of the ilium; 4, Angle 
of the haunch; 5, Cotyloid cavity; 6, Its bottom; 7, One of the imprints 
for the insertion of the anterior straight muscle of the thigh (rectus femoris) ; 
8. Nio-pectineal ridge, 9, Channel on the external face of the pubes ; 10. Oval 
(or obturator) foramen; 11, Ischial spine; 12, 12, Ischial arch. pee te 


and bears a roughened lip for muscular insertion. The external border is 
thick, concave, and furrowed by vascular fissures ; it presents, inferiorly, the 
nutrient foramen The internal border is thin and concave ‘particularly in 
its posterior part, which constitutes the great ischiatic notch. ; 

. Angles. —The external angle, or anterior and superior spinous process, is 
thick, wide, and flat, and bears four tuberosities: two superior andtwo 
inferior. The internal angle, or posterior and superior spinous process, 
represents ® rugged tuberosity curved backwards and upwards’ ; The 


(! At the external angle of the ilium, there is sometimes found in the horse a process— 
often a very marked one—directed downwards, and completely enveloped by the external 
ilio-femoral muscle.) . ; ‘ 


‘ 


THE POSTERIOR LIMBS. 93 


posterior or cotyloid angle is prismatic and very voluminous. It exhibits: 
1, Behind, a wide concave articular facet, which forms part of the cotyloid 
cavity; 2, Above this cavity, the supracotyloid crest, represented in 
Man by the ischiatic spine. This is an eminence elongated from before to 
behind, sharp on its summit, smooth inwardly, roughened outwardly, and 
continuous by its anterior extremity with the internal border of the bone; 
38, Outwardly, two deep imprints for the insertion of the rectus muscle; 
4, In front and inwards, the ilio-pectineal eminence, a small elongated pro- 
minence forming the most salient point of a kind of ridge (linea ilio-pectinea) 
that insensibly subsides above on the inner face of the ilium, and is continued 
below by the anterior border of the pubis. 

Of the three angles of the ilium, the first is also termed the angle of the 
haunch, and the second the angle of the croup. 

Pousis,—Situated\petween the ilium and ischium, elongated from side to 


PELVIS; FRONT VIEW. 

1, Crest and anterior spinous process of the ium; 2, Angle of the croup, with the 
auricular facets proceeding from it ;, 3, Shaft of the ilium, with the ilio-pectineal 
crest ; 4, Cotyloid cavity; 5, Symphysis pubis; 6, Ischiatic tuberosity. 


side, flattened above and below, and irregularly triangular, the pubis, the 
smallest of the three divisions, is divided for convenience of description into 
‘iwo faces, three borders. and three angles. : ; 
Faces.—The superior, smooth and concave, concurs in forming the floor 
of the pelvis. It shows one or two nutrient foramina. The inferior is 
roughened, and marked throughout its length by a wide channel which 
reaches the bottom of the cotyloid cavity. This fissure lodges the pubio- 
femoral ligament and a very large vein. ; a 
Borders.—The anterior is constituted by a thin rugged lip, which is 
curved upwards. The posterior, thick and concave, circumscribes anteriorly 
a wide opening, the oval, subpubic, or obturator foramen ; it is channeled near 
the cotyloid angle by a fissure which runs obliquely inwards and down- 
wards. The internal is united with that of the opposite pubis to form the 
pubic portion of the pelvic symphysis. 
t 


94 THE BONES. 


Angles—The external, also named the cotyloid angle, is the thickest of the 
three. To it chiefly belongs the rugged depressed surface that constitutes 
the bottom of the cotyloid cavity. ‘The internal unites with the analogous 
angle of the opposite pubis. The posterior is consolidated at an early period 
with the antero-internal angle of the ischium, to inclose, inwardly, the oval 
foramen. ; ; 

Iscu1um.—This is the mean, in volume, of the three pieces of the coxa. 
Situated behind the pubis and ilium, it is flattened above and below, and of 
a quadrilateral form. It offers for study: two faces, four borders, and four 
angles. 

Faces.—The superior is smooth and nearly plane, and forms part of the 
floor of the pelvic cavity. It has a small nutritious foramen directed out- 
wards. The inferior presents some rugosities clustered particularly about 

mphysis. 
ee Fig. 60. 


PELVIS; LATERAL VIEW. 
1, Crest of the ilium; 2, Angle of the croup; 3, Shaft of the ilium ; 4, Cotyloid 
cavity, or acetabulum, 6, Ischial spine, 


Borders.—The anterior, thick and concave, circumscribes the oval foramen 
posteriorly. The posterior, straight and directed obliquely forwards and 
inwards, forms, with the analogous border of the opposite bone, a large 
notch named the ischiatic arch. It exhibits, throughout its extent, a rugged 
depressed lip (the spine), arising from the side of the inferior face. The eax- 
ternal, thick and concave, constitutes the lesser ischiatic notch. The internal 
is joined to the ischium of the other side to constitute a portion of the pelvic 
symphysis. 

Angles—The antero-external or cotyloidean is the most voluminons ‘of the 
four, and affords for study: 1, An excavated diarthrodial facet, making part 
of the cotyloid cavity ; 2, The posterior extremity of the super-cotyloidean 
crest, limited by a small transverse fissure which separates it from the 
external border of the bone. The antero-internal angle is consolidated with 
the posterior angle of the pubis. The postero-external angle forms the 
ischiatic tuberosity. This is a large prismatic process which looks upwards, 
and is prolonged by a salient ridge, elongated from before to behind, with 
its sharp border turned outwards and downwards, The postero-internal angle 


THE POSTERIOR LIMBS. 95 


forms, with that of the other ischium, the summit of the triangular space 
which constitutes the ischiatic arch, or pubic arch of some species. 

_ THe Coxa In GenERAL.—The bone whose three constituent parts we have 
just been studying, presents for consideration, as a whole, a middle portion 
and two extremities. The middle, very much contracted, offers, outwards 
and downwards, the cotyloid cavity (or acetabulum), which has not yet been 
described, because its study does not properly pertain to either of the three 
regions of the coxa. This cavity is intended to receive the articulating head 
of the femur, and represents the segment of a hollow sphere; it is cireum- 
scribed by a very salient rim which is thin at its free margin and widely 
notched on the inner side. The deeper portion is occupied by the rough- 
ened and depressed surface already designated as the bottom of the cotyloid 
cavity (fundus acetabuli), and which communicates by the internal notch of 
the rim with the inferior groove of the pubis. The anterior extremity, 
flattened on both sides, and formed by the ilium, rests, as has been shown, 
on the sacrum. The posterior extremity, flattened in an inverse sense to the 
preceding, is constituted by the pubis and the ischium, and traversed, from 
above to below, by the sub-pubic (or obturator) foramen, the large oval 
aperture which separates these two bones from one another, and perforates 
the floor of the pelvis; this opening is closed in the fresh state by muscles. 

The two coxe, by uniting in their posterior part, form the articulation 
to which has been given the name of ischio-pubic or pelvic symphysis ; thus 
united, the two bones represent something like a V with the opening in 
front; a circumstance which makes the lateral diameter of the pelvis greater 
in front than behind. 

SrructuRE AND DEVELOPMENT or THE Coxa.—To the three centres of 
ossification which constitute the coxa, are added two complementary 
centres: one for the anterior spinous process and spine of the ilium, another 
for the ischiatic tuberosity. 

In youth, the different parts of the coxa are very thick, and the spongy 
tissue is abundant, while the compact is rare. The pubis is always convex 
on its two faces, and the middle part of the coxa-—that adjoining the cotyloid 
cavity—is of considerable thickness, a feature which much diminishes the 
extent of the pelvic reservoir. As the animal advances in age, however, 
the layers of compact tissue increase in thickness, approaching each 
other as the spongy substance is lessened. The pubis becomes thinnest, and 
at an advanced period of life is sometimes even translucid. 

The compact tissue is always abundant in the neighbourhood of the 
cotyloid cavity, as this is the centre on which converge all the impulsive 
efforts communicated to the trunk by the posterior limbs. It is also in this 
cavity that ossification commences. 


B. The Pelvis in General. 


1. Exrervat AND Internat Conformation or THE Petvis.—The pelvis is a 
kind of rear cavity in the form of a cone, which prolongs the abdominal cavity. 

Tt occupies the posterior part of the trunk, and with regard to its 
conformation, presents for study an external and an internal surface. 

External surface.—This may be resolved into four regions or faces. 

The superior region is slightly oblique from above to below, and before 
to behind; its degree of obliquity varies. It is contracted from before to 
behind, and shows: 1, On the median line, the spinous processes of the 
sacral and the first coceygeal vertebre ; 2, On each side the sacral grooves, 
at the bottom of which open the supersacral canals. 


96 THE BONES. 


The inferior region is nearly horizontal. Formed by the pubes and ischia, 
it presents from before to behind: 1, In the middle, the ischio-pubie 
symphysis; 2, On each side the subpubic groove, the oval foramina, and 
the inferior face of the ischia ; 3, Quite externally, the cotyloid cavities, by 
which the pelvis rests on the posterior limbs. vs 

The lateral regions are oblique from above to below and within to 
without, and wider in front than behind. They exhibit: 1, The spine of 
the ilium and the two anterior spinous processes; 2, The external iliac 
fossa; 3, The ischiatic arch; 4, The supercotyloid crest or ischiatic spine, 
which presents outwardly the surface of insertion for the internal or deep 
gluteus muscles; 5, The lesser ischiatie notch ; 6, The ischiatic tuberosity. 

In'ernal surface.—The internal surface of the Horse’s pelvis cannot be 
divided into two portions as in Man, because the inner aspect of the iliac bones 
is not hollowed out to form an anterior cavity. 

The pelvis of Solipeds is, therefore, a simple conoid cavity, in which are dis- 
tinguished four regions or faces, and two apertures called the inlet and outlet. 

The anterior opening or inlet is nearly circular, especially in the Mare, 
and a little oblique downwards and backwards. It is limited above by the 
inferior face of the base of the sacrum; inferiorly, by the anterior border of. 
the pubis; and on the sides by a portion of the inner face of the iliac bones, 
and algo the internal aspect of the pectineal crests. 

The inlet presents four diameters: a vertical, horizontal, and two 
oblique. The first extends from the inferior face of the sacrum to the 
anterior border of the pubic symphysis; its mean length is 84 inches. 
The second is measured from one pectineal crest or eminence to another ; 
the mean of this is 8,2; inches. The two last diameters are estimated from 
she inferior face of the sacro-iliac articulation of one side to the ilio-pectineal 
eminence of the other; this is on an average 8, inches. These measurements 
irrefutably demonstrate that the inlet is not elliptical in the vertical direction. 

The posterior aperture or outlet, situated at the posterior end of the pelvic 
cavity, gives exit to the rectum and genital organs. As the pelvis of the 
horse is horizontal, the outlet should be considered as limited, we think, by 
the inferior face of the summit of the sacrum, the superior face of the ischia, 
the supercotyloid crest or ischiatic spine, and the internal face of the 
sacro-ischiatic ligaments. At the outlet only two diameters are recognised : 
a vertical anda horizontal. The vertical measures on an average 6; inches; 
it extends from the inferior face of the sacrum to the superior face of the 
ischial symphysis. The horizontal diameter, comprised between the two 
supercotyloid crests, is 71% inches. 

The superior region of the pelvic cavity is a little concave from before 
to behind; it has for base the sacrum, which presents on each side of the 
median line the subsacral foramina. This part is also called the sacral 
plane or roof of the pelvis. 

The inferior region, or ischio-pubic plane, is formed by the pubis and 
the ischia. It is concave from side to side; its anterior border is nearly 
straight, and its posterior border is scooped out by a wide notch to form the 
arch of the ischium. 

It has been remarked by M. Gobaux, that the portion of this plane corre- 
sponding to the pubis presents numerous varieties. The superior face of the 
pubis may be convex in its anterior moiety and concave in its posterior ; or 
it may be concave before and convex behind, the concavity being separated 
from the convexity by a transverse ridge. This ridge is sometimes represented 
by a series of small conical eminences, at other times this upper face is 


THE POSTERIOR LIMBS. 97 


disposed as a smooth inclined plane, directed backwards and upwards, and 
a kind of rim surmounts the anterior contour of the oval foramen. 

With regard to the lateral reyions, they are formed by a small portion 
of the inner face of the ilia, and in great part by the sacro-sciatic ligaments. 

2. Dirrerenors tn tHE Privis or tHe Suxes—The pelvis of the Mare 
exceeds that of the Horse in all its dimensions, but the difference is most 
marked in the transverse diameters. 

The anterior inlet forms a vast circumference when compared with that of 
the male ; the pectineal crests are widely apart, and the distance separating the 
anterior border of the pubis from the lower face of the sacrum is considerable. 

If the pelvis be viewed in its superior plane, it is found that in the 
Mare the ischiatic notches are very deep; that the internal border of the 
ilium forms @ regularly curved and very concave line ; and that the supracoty- 
loid crests, or ischiatic spines, are widely separated from each other. It is 
also noticed that the floor of the pelvis is wide, and that the bones com- 
posing it tend towards the same horizontal plane. 

In the male, the ischiatic border is only represented by a very curved 
line; this line is composed of two almost straight portions, which join at 
an obtuse angle at the origin of the neck of the ilium; the supracotyloid 
crests are relatively near each other, and bent towards the longitudinal axis ; 
while the two moieties of the pelvic floor are directed very obliquely down- 
wards and inwards. 

In the Mare, the ischial arch is larger than in the male, and forms a 
regular curve uniting the two tuberosities of the same name. In the Horse, 
the two ischiatic tuberositics are but little apart from each other, and the 
ischial arch forms a somewhat acute angle whose borders are nearly straight. 

Lastly, when the pelvis is examined in its inferior plane, in addition to 
the features already indicated in the ischiatic arch, it is found that in the 
Mare the obturator foramina are large and nearly circular, while in the 
Horse they are elliptical ; the cotyloid cavities are also further removed from 
the ischio-pubic symphysis in the female than the male. 

‘The sacrum of the Mare has appeared to us, in some individuals, to be a 
little more arched from before to behind than that of the Horse; but this 
character is not constant. 

The following figures relating to the capacity of the pelvis in the Mare 
and Horse confirm what has just been enunciated. 


MARE, HORSE. 
Horizontal Diameters. Horizontal Diameters, 


Between the Pectineal | Between the Supercoty- | Between the Pectineal | Between the Supercoty- 


Crests. loid Crests, Crests. loid Crests. 
Inches. Inches. Tnches, tach; 
9% a: Str Gi 
MARE. HORSE. 
Vertical Diameters. Vertical Diameters. 
Between the Sacrum and’ Between the Sacrum and Between the Sacrum and} Between the Sucrum and 
Pubis. | Ischium. | Pubis. Ischium. 
Inches. Inches, Inches, Inches. 


8% 6% 8 6% 


-98 THE BONES. 


To recapitulate, there is observed in the pelvis of the Mare: 


. A great increase in the transverse diameters ; 

. A deep and regularly concave ischiatic notch 5 

. A wide and concave ischial arch ; 

. Cireular obturator foramina; 

. The cotyloid cavities distant from the pubic symphysis. 


Oc 09 DD 


THIGH. 
This has for its base one bone, the femur. 


Femur. 


The femur is a long, pair bone, situated in an oblique direction down- 
wards and forwards, between the coxa and the principal bone of the leg; it 
is divided into a body and two extremities. 

Body.—It is irregularly cylindrical, and presents for study four faces, 
The external, internal, and anterior, confounded with one another, are 
regularly rounded and almost smooth, showing only some slight imprints 
and vascular grooves. The posterior, nearly plane, and wider above than 
below, offers: 1, Outwardly and towards the superior third, an uneven 
circular surface ; 2, On the same level, and inwardly, a slight crest, oblique 
downwards and outwards; 38, In the middle, a very extensive roughened 
surface, having the form of an obliquely angular parallelogram, for the 
attachment of the great adductor muscle of the thigh; 4, Below this 
surface, a large vascular groove running obliquely outwards and downwards. 

On the limit of the posterior and external faces are found, towards the 
upper third, a large rugged, flattened eminence, curved in front, and termed 
the subtrochanterian crest fe of its position under the trochanter ; below, a 
deep fossa, named. the’ ondyloid, garnished at its bottom with asperities 
and bordered in front by an uneven lip. On the limit of the posterior and 
internal face, there is observed from above to below: 1, The small trochanter, 
a large scabrous tuberosity, elongated in conformity with the bone, and 
situated near its upper fourth; 2, A marked longitudinal imprint for 
the attachment of the pectineus; behind, it is confounded with the surface 
for the insertion of the great adductor muscle of the thigh, and presents, in 
front, the nutrient foramen of the bone; 8, The origin of the great 
posterior fissure ; 4, Quite below, a collection of large tubercles which form 
the supracondyloid crest. 

Eutremities—The superior eatremity is sensibly flattened before and 
behind, and shows: 1, Inwardly, an articular head which is received into the 
cavity of the acetabulum. This head is separated from the other portion of 
the body by a neck, which is, however, not well marked in the Horse, and 
forms two-thirds of a sphere, excavated in its internal part by a very deep 
cavity for ligamentous insertion , 2, Outwardly, a very large eminence, the 
trochanter, or great (external) trochanter, in which is recognised, as in the 
trochlea of the humerus: a summit, much more elevated than the articular 
head and slightly bent inwards; a convewity, incrusted with cartilage and 
anterior to the summit, from which it is separated by a narrow ang deep 
notch; a crest situated under the convexity, and formed by a tuberculous 
surface on which one of the tendons of the middle gluteus muscle becomes 


* This is the third trochanter of Cuvier, and takes the place of the external and 
superior branch of the Linea aspera of Man, (It ig the i ‘Gosienken : 
Percivall and the middle troehanter of Leyh.) : Crete einer Re 


. 


THE POSTERIOR LIMBS. 99 


inserted, after gliding over the convexity ; i 
id: y; 3, Posteriorly, the fossa th 
trochanter, or digital fossa, a deep cavity studded with ee an 
ate cae i ayes be by a salient lip which descends vertically from the 
it of the trochanter to the posteri re i 
me ere posterior face of the bone, where it 
The inferior extremity is flattened on both sides; con i 
> Q ; sequently, its 1 
axis crosses at a right angle that of the upper extremity. it is dednauicted 


Fig. 61. Fig. 62. 


LEFT FEMUR; ANTERIOR VIEW. LEFT FEMUR; POSTERIOR VIEW. 

1, Head; 2, 2, Trochanter major, with its 1, Head; 2, Great trochanter; 3, Third, or 
crest; 3, Trochanter minor externus, sub- trochanter minor externus; 4, Lesser, or 
trochanterian crest, or third trochanter; internal trochanter; 5, Fossa for insertion 
4, Lesser, or internal trochanter; 5, Notch of ligamentum teres; 6, Trochanterian 
for insertion of ligamentum teres; 7, 8, fossa; 7, 8, Tuberosities; 9, Fossa for the 
Tuberosities for tendinous and ligamentous insertion of the external meniscus; 10, 

' insertion ; 9, Trochlea. Supracondyloid fossa; 11, Condyles. 


py the presence of two condyles and a trochlea. The two condyles, placed one 
beside, the other behind, correspond to the superior extremity of the tibia. 
They are separated by a deep depression designated the intercondyloid fossa, 
which lodges the spine of the tibia and the interosscous ligaments of the 
femoro-tibial articulation. The external condyle bears outwardly two fosse: 
one superior, for ligamentous insertion; the other, inferior, for muscular 


100 THE BONES. 


attachment. The internal condyle presents, posteriorly and inwardly, near 
the posterior extremity of the intercondyloid notch, a roughened depression 
for the insertion of the fibro-cartilaginous meniscus interposed between the 
external condyle and the corresponding articular plane of the tibia. It is 
surmounted outwardly, ic, on the side opposite to the intercondyloid 
notch, by a large tubercle of insertion, The érochlea, a wide pulley on 
which the patella glides, is situated in front of the condyles. It is slightly 
oblique downwards and inwards, and appears to continue in front the inter- 
condyloid notch. Of the two lips which border its cavity laterally, the 
internal is the thickest and the most prominent. 
Bag Pe Between the external and the corresponding con- 
dyle is seen a digital fossa for muscular insertion. 
Structure and development.—The femur, very 
‘spongy at its extremities, is developed, from four 
principal centres of ossification: one for the body, 
another for the articular head, the third for the 
trochanter, and the last for the inferior extremity 
alone. 


LEG. 


This has for its base three bones: the tibia, 
peroneus (or fibula), and the rotula (or patella), 


1. Tibia. , 


The tibia is a long, prismatic bone, thicker at 
the superior than the opposite extremity, and 
situated between the femur and the astragalus, 
in an oblique direction downwards and backwards, 
constituting the principal portion of the leg. 
SS : Body.—This offers for study three faces and 
pt | three borders. The faces are wider above than 

SECTION OF LEFT FEMUR, below. The external is almost smooth, and is 
SHOWING ITS STRUCTURE. Concave in its superior part and convex below, 
where it deviates to become the anterior. The 
internal, slightly convex on both sides, presents, superiorly, deep imprints 
tor the attachment of the adductor muscles of the thigh and; the semi- 
tendinosus. The posterior, nearly plane, is divided into two triangular 
surfaces: one, superior, slightly roughened, serves for the attachment of the 
popliteus muscle ; the other, inferior, much more extensive, is furrowed into 
numerous longitudinal crests which give attachment to the perforans 
“muscle. On the limit of these two surfaces is remarked the nutrient foramen 
of the bone. The borders are distinguished as anterior, external, and internal, 
The first is rounded, and not very salient in its inferior two-thirds; it forms 
in its superior third, a curved crest, with the concavity external, which joins 
the anterior and superior tuberosity of the bone; this has received the name 
of the tibial crest. The ewternal border is very thick and concave above, 
where it constitutes, in common with the fibula, the utbial arch. The 
imternal is also very thick, straight, and provided superiorly with some 
salient tubercles to which the poplitcus is attached. 

Extremities.—The superior extremity, the most voluminous, is formed by 
three tuberosities, an anterior and two lateral, which are external and 
internal, The first, the smallest, is a rugged process continuous with 
the tibial crest, and separated from the external tuberosity by a wide and 


THE POSTERIOR LIMBS. 


101 


deep groove in which passes a tendinous cord; it is excavated, in front, by a 
vertically elongated fossa which lodges the middle ligament of the patella, 
The external tuberosity, medium in size and the most detached, has outwardly 


an articular facet for the head of the fibula. The 
internal tuberosity, the largest and least detached, 
presents: on the sides, ligamentous imprints; behind, 
a small tubercle which gives attachment to the pos- 
terior crucial ligament of the femoro-tibial articu- 
lation. The superior face of the two lateral tube- 
rosities is occupied by two large irregular and 
undulated articular surfaces, which respond to the 
condyles of the femur through the medium of the 
two meniscus-shaped fibro-cartilages interposed be- 
tween the two bones. Of these two surfaces the 
external is always the widest, because it serves, by 
its posterior part, for the gliding movements of the 
popliteal tendon. They are separated from each 
other by the tibial spine, a conical articular eminence 
divided into two lateral parts by a groove of inser- 
tion excavated at its base, and in front by two lateral 
facets for the insertion, anteriorly, of the two inter- 
articular cartilages; it is bordered belind by another 
fossa which receives the posterior insertion of the 
internal meniscus. 

The inferior extremity, flattened behind and before, 
exhibits an articular surface moulded on the pulley 
of the astragalus, and two lateral tuberosities. The 
articular surface is formed by two deep cavities oblique 
from behind to before and within outwards, and 
separated by a median tenon which terminates pos- 
teriorly by a very prominent projection on which the 
bone rests when it is made to stand vertically on 
a horizontal plane. The external tuberosity) projects 
but little, and is traversed in its middle by a vertical 
fissure. The internal tuberosity,’ better defined, is 
margined posteriorly by an oblique channel. 
‘Structure and development.—The tibia is very 
‘compact in its inferior portion, and is developed from 


four chief centres of ossification. The body is formed’ 


by one and the superior extremity by two, the anterior 
tuberosity taking one of these; the last develops the 
whole of the inferior extremity. It is rare to see 
the external tuberosity of this extremity formed from 
a separate nucleus. 


2. Fibula (or Peroneus). 


A small, undeveloped bone, elongated and sty- 
loid in shape, situated outside the tibia, and extend- 
ing from the superior extremity of that bone to the 
‘middle or lower third of its body. 

‘The middle portion of the fibula is thin and cylin- 


Fig. 64, 


POSTERIOR VIEW OF 
RIGHT TIBIA, 


1, Tibial spine; 2, Fossa 


for the insertion of the 
internal meniscus; 3, 
External tuberosity with 
articulation for the fib- 
ula; 4, Fossa for the 
insertion of external 
meniscus; 5, Fibula, 
forming with the tibia 
the tibial arch; 6, Shaft, 
or body. of the tibia; 
7, 8, External and in- 
ternal malleoli, inferior 
tuberosities, or lateral 
processes of the tibia; 
9, Articular trochlex 
with a median ridge, 
for articulation with the 
astragalus, 


drical, and forms above, in common with the external border of the larger 


1 The external malleolus of Man. 


10 


2 The internal malleolus. 


102 THE BONES. 


bone, the tibial arch. Its superior extremity, wide and flattened on both 
sides, has received the name of head; it offers, on its internal face, a 
diarthrodial facet to articulate with the external and superior tuberosity 


of the tibia; on its external face it shows ligamentous imprints. The. 


inferior eatremity of the fibula terminates in a blunt point, and gives 
attachment to the ligamentous fibres that unite it to the tibia. 

The fibula is sometimes continued to the external inferior tuberosity 
of the latter bone, with which it is confounded; and as it is particularly 
under such circumstances that this tuberosity has been noticed to be deve- 
loped from a special nucleus, it seems quite natural, having regard to 
the disposition observed in pachyderms and carnivores, to consider it as 
the inferior extremity of the fibula joined to the tibia. With these animals, 
indeed, the tuberosity or external malleolus is formed by the inferior ex- 
tremity of the fibula. 

Structure and development—This bone is very compact, and developed 
from a single nucleus of ossification. 


3. Patella. 


A small, short, and very compact bone, situated in front of the femoral 
trochlea, and annexed to the tibia, to which it is attached by three extremely 
solid ligamentous bands. 

The small polyhedron which it represents only offers for observation 
three faces: the superior, roughened, and serving for the insertion of the 
triceps cruralis and rectus muscles; the anterior, convex and irregular ; and 
the third, the posterior, moulded on the femoral trochlea, to which it is but 
imperfectly adapted. In the fresh state, however, the articular surfaco 
formed by the latter face is completed by a fibro-cartilaginous apparatus, 
which will be noticed when describing the femoro-tibial articulation. This 
articular surface is composed: 1, Of a median ridge, which occupies the 
bottom of the trochlear cavity ; 2, Of two depressed, gliding, lateral facets 
on the sides of this cavity; the internal facet is always larger than the 
external, a disposition which permits the patella of one limb to be distin- 
guished from that of the other. 


POSTERIOR FOOT. 


This region, which bears the greatest resemblance to the same region in 
the anterior limb, comprises three subdivisions: the tarsus, metatarsus, 
and the digital region. 


1. Bones of the Tarsus. 


These are short, very compact bones, six or seven in number, and 
situated between the inferior extremity of the tibia and the superior 
extremity of the metatarsal bones; they are arranged, like the bones of 
the carpus, in two tiers—a superior and an inferior. 

The superior row only comprises two bones, the largest; these are the 
astragalus and the calcaneus (or calcis). The inferior row is formed, out- 
wardly, by the cuboides alone; inwardly and anteriorly, it is subdivided 
int» two secondary rows, the superior of which is constituted by the 
scaphoides, and the inferior by the large and small cuneiform bones. The 
last is sometimes divided into two, in which case there are three cuneiforms ; 
then the total number of the bones is seven. 

Astragalus—An irregular cubical bone, situated in front of the 


THE POSTERIOR LIMBS. 


103 


calcaneus, between the tibia and the seaphoid, and divided into five faces :-— 


Fig. 65, 


LEFT HIND FOOT; EXTERNAL 
ASPECT. 

1, Tibia; 2, Summit of calcis or cal- 
caneus; 3, Astragalus; 4, Cuboid ; 
5, Scaphoid; 6, Cuneiform mag- 
num; 7, Large metatarsal bone, 
8, Small metatarsal bone; 9, Suf- 
fraginis, proximal, or first phalanx ; 
10, Sesamoid bones ; 11, Coronary, 
middle phalanx; 12, 


second, or 
Pedal ” bone, or third or distal 
phalanx; 14, Navicular bone; 15, 


Basilar process of pedal bone. 


1, A superior and anterior, formed as an 
articular pulley to correspond to the in- 
ferior extremity of the tibia; this pulley, 
oblique from above downwards, forwards, 
and outwards, may be considered as the 
type of the most perfect trochlea in the 
organism; its groove receives the median 
tenon of the tibia, and its two ridges or lips 
fit into the lateral furrows of that bone. 
2, An inferior face, occupied by a slightly 
convex articular surface responding to the - 
scaphoid ; this surface is notched outwardly 
by an excavation for ligamentous insertion. 
3, A posterior face, irregular, cut into three 
or four diarthrodial facets adapted for 
similar facets on the calcaneus, and which 
are separated by a wide, rugged excavation. 
4, An external face, covered with imprints. 
5, An internal face, provided below with 
a small tubercle of insertion. 

Calcaneus. —A bone vertically elongated, 
flattened on both sides, and presenting iwo 
faces, two borders, and two extremities. 

The external face is smooth and nearly 
plane. The internal face is excavated into 
a gliding groove to form the tarsal arch, in 
which passes the tendon of the perforans. 
The anterior border is slightly concave. 
The posterior border is thicker, straight, 
and rugged. The superior extremity, 
slightly tuberous, constitutes the summit 
of the calcaneus, and is divided into three 
parts: a middle, which gives attachment to 
the tendon of the gastrocnemius; the other, 
the anterior, is a smooth surface on which 
this tendon rests when the foot is much 
flexed; the third, altogether posterior, also 
constitutes a gliding surface for the tendon 
of the perforatus. The inferior extremity, 
wide and voluminous, shows in front three 
or four articular facets which correspond 
to the astragalus, and are separated, like 
those of the last bone, by an irregular and 
slightly excavated surface of insertion. 
Below, it shows for articulation with the 
cuboid a fifth facet, continuous with one of 
the preceding. 

Development.—The calcaneus is deve- 
loped from two nuclei of ossification, one of 
which is for the summit. 

Cuboid bone.—This little bone, situated 
at the external side of the scaphoid and the 


104 THE BONES. 


large cuneiform bone, between the calcaneus and two of the metatarsals, does 
not resemble a cube, but a parellelopiped elongated from before to oehind, 
It offers sia faces: a superior, an articular face, and in contact with the 
calcaneus ; an inferior, also articular, responding to the principal and external 
rudimentary metatarsal bones; an internal, furnished with three facets for 
contact with the scaphoid and great cuneiform, and crossed from before 
to behind by a fissure, which forms with these two bones a vascular canal ; 
an external, an anterior, and a posterior, covered with imprints. 

Scaphoid bone (the large cuneiform of Percivall).—Flattened above and 
below, it is described as having two faces and a circumference. The faces, 
both articular, are furrowed by a channel of insertion, and are distinguished 
as superior and inferior. The first is concave, and responds to the astra- 
galus; the second is convex and in contact with the two cuneiform bones. 
The circumference offers, outwardly, two small facets which are adapted to 
similar facets on the cuboid bone. For the remainder of its extent, it is 
covered with imprints. 

Great Cuneiform bone (the middle cuneiform of Percivall).—Flattened 
above and below, and triangular in shape, this bone is much smaller than 
the scaphoid, though resembling it in a striking manner. Its superior face 
is in contact with the latter bone, and its inferior face articulates with the 
middle and internal lateral metatarsal bones. Its eternal border is 
provided with one or two facets to correspond with the cuboid bone; and its 
internal border also offers one, which is in contact with another on the small 
cuneiform. Its anterior border is roughened throughout its extent. 


Fig. 66. Fig, 67. 


LEFT HOCK; FRONT VIEW. LEFT HOCK; INTERNAL ASPECT. 
1, Apex of calcaneus; 2, Astragalus, inner 1, Apex of calcaneus; 2, Inner articular 
ridge; 3, Scaphoid; 4, Cuneiform mag- ridge of astragalus ; 3, Navicular, scaphoid 
num; 5, Cuboides. or cuneiform medium; 4, Cuneiform mag- 


num; 5, Cuboides; 6, Cuneiform parvum. 
Small Cuneiform bone.—Situated at the inner side of the tarsus, this 
bone, the smallest of any yet examined, is elongated from before to behind, 
flattened on both sides, and wedged in between the os scaphoides, the large 
cuneiform bone, and the large and internal small rudimentary metatarsal 
bones, with which it corresponds by four articular facets: a superior, two 
se and internal. When this bone is in two portions, there are 
then three cuneiforms, which may be distinguished, as in Man, by namin 
them first, second, and third. : oe z 


THE POSTERIOR LIMBS. 


2. Bones of the Metatarsus. 


105 


These bones are three in number, a median and two lateral, and offer the 


greatest analogy to the metacarpal bones. 


This enables us to dispense with 


a general description of them, and to confine ourselves only to indicating 
the differential characters which distinguish them from the corresponding 


bones in the anterior limb. 


The principal, or median metatarsal bone, is longer than the same 
metacarpal, and its body, instead of being slightly compressed before and 


behind, is nearly a regular cylinder. It presents out- 
wardly a fissure which is directed at first obliquely 
backwards and downwards, and afterwards descends 
vertically along the lateral external metatarsal bone. 
The articular surface of the superior extremity is ex- 
cavated in its centre by a large fossa of insertion. The 
inferior extremity is at the same time wider and thicker 
than that of the metacarpus. 

Of the two rudimentary (digital) or lateral metatarsal 
bones, the external is always longest and thickest. The 
internal bears on the superior face of its head three 
articular facets, two of which respond to the small 
cuneiform, and the third to the large bone of that name. 


3. Bones of the Digital Region. 


The digital region of the posterior closely resembles 
that of the anterior limb. The analogy in the con- 
formation of these bones is even pushed so far, that 
it becomes very difficult to distinguish them from one 
another. 

It is remarked, nevertheless: 1, That the first pha- 
Janx is not so long as in the anterior limb, and less 
wide and thick at its inferior extremity, but is, on the 
contrary, wider and thicker at its superior extremity ; 2, 
That the lateral diameter of the second phalanx is 
shorter; 8, That the third phalanx, less spread out 
towards its inferior border, has more the shape of a V, 
and that its inferior face is more concave; 4, That the 
sesamoids are less voluminous; 5, That the navicular 
bone is shorter and narrower. 


DIFFERENTIAL CHARACTERS OF THE POSTERIOR LIMB IN 
OTHER THAN SOLIPED ANIMALS. 


A. Pevvis.—It is remarked: 1, That in all the domesticated 
animals, with the exception of Solipeds, the direction of the coxz 
is nearly horizontal; 2, That in all, except Solipeds, the ilium 
tends to assume a vertical direction; 3, That in all the trans- 
verse diameter of the pelvis is relatively less extensive. 

In the Ox, Sheep, and Goat, the space between the two coxee 
is scarcely so great in front as behind; the ilium is not volumi- 
nous, and has only three processes on the superexternal iliac 
spine. There is no furrow on the lower face of the pubis, and 
its upper face, like that of the ischium, is very concave. 


POSTERIOR ASPECT OF 
LEFT METATARSUS. 
1, Head of principal 
metatarsal bone; 2, 
3, External and in- 
ternal splint bones, 
or metatarsals of the 
rudimentary digits, 
4, Rough surface for 
insertion of suspen- 
sory ligament; 5, 
Nutrient foramen; 
6, Middle ridge of 
inferior articular 

surface. 


Three eminences are seen on 


the postero-external angle of the ischium, In early life, the ischio-pubic symphysis 


shows an epiphysary nucleus in the middle of its inferior face. 


(The epiphysis on 


the inner border of the ischium has been considered by some anatomists as an inde- 


pendent bone, ‘and deacribed by them as the interischial bone.) 


106 THE BONES. 


The rim of the cotyloid cavity has also three notches, and the supracotyloid crest, or 
ischiatic spine, is very elevated and sharp, and but little roughened outwardly. 

The external iliac fossa of the Sheep and Goat is separated into two portions by a small 
longitudinal crest. : 

The pelvis of the Pég closely resembles that of the smaller ruminants; though the 
crest of the ilium is convex, and there is no protuberance outside the ischio-pubic 
symphysis. Ar : . 

In Carnivora the lateral diameter of the pelvis is greater behind than in front. The 
ilium is nearly vertical, and its external face is much depressed. The notch forming the 
ischial arch occupies no more than the internal moiety of the posterior border of the 
ischium ; between this arch and the ischiatic tuberosity is a rugged lip directed down- 
wards. There is no furrow on the lower face of the pubis. 

B. Tsicu.—In ail the domesticated animals except Solipeds, the femur tends to become 
curved, prismatic, and triangular ; the posterior face contracts, and the surfaces of insertion 
that it presents gradually approach each other until they become confounded and form the 
linea aspera in certain species. The head is more distinct; the small trochanter is a 
rough tubercle, and is joined to the large trochanter by an oblique osseous lip; the latter 
trochanter subsides and forms a single mass whose summit and convexity are con- 
founded; the third trochanter, the fossa, and the supracondyloid crest are more or less 
effaced. 

In the Oz, there is no subtrochanterian crest; the supracondyloid fossa is shallow, 
and the crest little noticeable. ‘The head is well detached and has its centre ex- 
cavated by a shallow fossa of insertion. The trochlea is narrow, and its inner border 
ascends much higher on the anterior face of the bone than the external. 

In the Sheep and Goat, the general fotm of the femur resembles that of the Ox. It is 
observed, however, that the body is slightly curved backwards; that the supracondyloid 
fossa is nearly obliterated; that the trochanter has subsided nearly to a level with the 
articular head, and that the trochlea is circumscribed by two equal-sized lips. 

In the femur of the Pig there is also noticed u supracondyloid fossa, but it is wide 
and shallow; the rugosities of the posterior face are replaced by some salient lines; the 
trochanter is on a level with the head; the latter is supported by a somewhat constricted 
neck, and is situated within and in front of the great trochanter. This latter disposition 
changes the direction of the great axis of the superior extremity, which obliquely crosses 
that of the inferior extremity. 

In the Dog and Cat, the femur is long and curved like a bow. The rugged surfaces 
of the posterior face are confounded, and form two crests representing the linea aspera of 
the human femur. These crests do not lie against each other in the middle portion of 
the bone; they are merely parallel, then they diverge above and below, to terminate 
beneath the great and small trochanters, and above the two condyles, The great tro- 
chanter is not so high as the articular head. The femur of Carnivora is also distin- 
guished: 1, By the complete absence of the third trochanter and the supracondyloid 
fossa—this last being replaced by a small tubercle which terminates below the external 
branch of the linea aspera; 2, By the marked constriction and length of the neck sup- 
porting the articular head; 3, By the depth of the digital fossa, which is bordered by an 
oblique lip extending from the great to the small trochanter. 

C. Lxc.—In the leg-bone there is observed, in the various domesticated animals, differ- 
ences analogous to those mentioned as existing in the fore-arm of the thoracic limb. More 
particularly is this the case with regard to the development of the fibula; in Ruminants 
this bone is reduced to its inferior nucleus. In these animals the patella is also very 
narrow; and in all the domesticated species except Solipeds, the articular grooves in the 
lower end of the tibia are directed immediately from before to behind. 

In the Oz, the tibia is short; it is longer in the Goat and the Sheep. The tibia of 
these animals is remarkable for: 1, The absence of the lateral facet on the supero- 
external tuberosity; 2, The absence of a vertical fossa on the anterior tuberosity ; 
8, The absence of roughened lines on the posterior face; the obliquity downwards and 
inwards of the inferior articular surface. The most salient point of this surface is the 
anterior extremity of the middle tenon. 

The body of the fibula and its upper extremity are replaced by a fibrous cord which 
is sometimes ossified wholly or in part. 

In the Pig, the fibula is flattened on both sides, extends the whole length of the leg, 
and is united to the tibia by its two extremities: above, by a diarthrodial facet: below, 
by an interosseous ligament. It is developed from three ossifie centres: the inferior 
articulates with the calcaneus and astragalus, and forms a prominence resembling the 
external malleolus. 

In Carnivora, the tibia is long and slender, and presents a salient anterior crest, The 


THE POSTERIOR LIMBS. 107 


fibula is also as long as the tibia, and is united to that bone at three points: at the two 
extremities by articular surfaces, in the inferior third and middle by an interosseous 
ligament. 

_ D. Posrertor Foor.—l. Bones of the tarsus—The number of tarsal bones varies a 
little in the domesticated animals, as the following list will show : 


Carnivora and Pig. gts 
Ox, Sheep, and Goat . e 8 © | 2 

In the Dog, Cat, and Pig, there are three cuneiform bones, and in the Ox and Sheep, 
in addition to there being only two cuneiforms, the scaphoid and cuboid bones are con- 
solidated into one piece. 

The astragalus of the carnivora articulates with the scaphoid by means of a veritable 
head, separated from the rest of the bone by a constriction termed the ncck of the astia- 
galus. The cuboid and the cuneiform bones respond to all the metatarsals. 

In the Pig, the astragalus and calcaneus are very long. The cuneiforms and cuboid 
respond to the four perfect digits. 

The tarsus of the domesticated Ruminants isslender above. The astragalus is elongated 
from above to below, and is united to the scaphoid by an antero-posterior groove, and to 
the calcaneus by a more superficial vertical groove. The calcaneus is long and tlin; 
the posterior gliding surface on the summit is excavated into a channel; the small 
cuneiform is pisiform and but slizhtly developed. 

2. Bones of the metatarsus—The metatarsus is also a region in which the number of 
bones varies in the domesticated animals. Thus in the Carnivora and Pig there are 
five. and only two in Ruminants. 

The metatarsals of the Carnivora and Pig are exactly like the same bones in the 
anterior limb, Those of Ruminants are slightly different. 

In the Dog and Cat are one rudimentary and four perfect metatarsals. The former 
is articulated with the internal cuneiform, and represents the vestige of the thumb, 

The Pig has four perfect metatarsals, and an internal rudimentary one. The latter 
is a small bone flattened on both sides, articulating by means of a diarthrodial facet, and 
sometimes consolidated behind the upper end of the fourth metatarsal. 

In the Ox, Sheep, and Goat, is found a principal and a rudimentary metatarsal bone. 
The latter is like the rudimentary metacarpal bone, but the former differs from the 
principal metacarpal bone in being longer, quadrilateral in form, and having a vascular 
canal traversing the posterior face of its upper extremity. 

3. Bones of the digital region.—In all the domesticated animals, the posterior digits 
comport themselves exactly like the anterior. The Carnivora alone offer a notable differ- 
ence; in them, in reality, the thumb does not exist, or rather, it is only represented by 
the rudimentary metatarsal bone alluded to above. Nevertheless, it frequently occurs 
that a completely developed thumb is found in this animal; and in this case the rudi- 
mentary metatarsal is ordinarily followed by a ligamentous cord, to which is suspend d a 
bony stylet that represents either the inferior extremity of the metatarsal, or the first 
phalanx; it is to this stylet that are found articulated in succession the second and third 

halanges. 
P CP entoast Fuchs, of Carlsruhe, found, in a Newfoundland dog, four true claws and 
two false; the internal of the latter corresponded to a well-developed, small metatarsal 
bone, while the external was only rudimentary, terminating in a point, and bound to the 
tarsus by a simple ligament.) 


COMPARISON OF THE ABDOMINAL LIMB OF MAN WITH THAT OF ANIMALS, 


A. Petvis.—The longitudinal axis of the pelvis of Man forms, with the horizon, an 
angle of about 40°. ; 

‘The bones which compose it are proportionately larger and stronger t!.an in all the 
domesticated animals. 

The two faces of the ilium, and especially the inner face, are much hollowed; the 
iliac crest has the form of an italic S. ; 

The pubis alone participates in the formation of the pelvic symphysis, and the con- 
cavity which, in the domesticated animals, is called the ischial arch, is designated in Man 
the pubic arch. : : as ; ; 

In consequence of the excavation on the inner face of the ilium, the pelvic cavity 
may be divided into the great and lesser pelvis In the latter are lodged the genital 
and urinary organs, as well as the extremity cof the digestive tube. ; 

8. Tuigu.—The femur of Man is nearly vertical, and situated in a direction slightly 


108 THE BONES. 


oblique downwards and inwards; it presents a curvature forwards. The body of the bone 
is prismatic and triangular in its middle part ; the posterior border of this prism forms a 
somewhat salient crest, which takes the place of all the insertion eminences on the pos- 
terior aspect of the femur in animals, and is designated the linea aspera. This line 
bifureates above and below; below, the branches margin a triangular or popliteal space. 


Fig. 69. 


HUMAN PELVIS; FEMALE. 

1, Last lumbar vertebra; 2, 2, Intervertebral substance; 3, Promontory of the 
sacrum; 4, Anterior surface of the sacrum; 5, Coccyx; 6, Iliac fosse; 7, Antero- 
superior spinous process; 8, Antero-inferior spinous process; 9, Acetabulum.— 
a. Its notch; b, Body of ischium; ¢, Its tuberosity; d, Its spine; e, Pubis; f, 
Symphysis pubis; g, Arch of the pubes; h, Angle of os pubis; 2, Spine of pubes, 
with crest between it and h; h, &, Pectineal line; /, Z, Ilio-pectineal line, with its 
prolongation, m, m; m, Ilio-pectineal eminence; 0, Smooth surface for femoral 
vessels; p, p, Great sacro-ischiatic notch. 


The head is supported by a long neck, inserted obliquely into the superior extremity. 
The two coudyles are joined together in front by the trochlea, which is wide and 
shallow. 

C. Lec.—Three bones: the tibia, fibula, and patella. 

The tibia is very long; its crest (or spinous process) is much more developed than in 
any of the domesticated animals, and describes a kind of curve like an italic S. On the 
inner aspect of the inferior extremity is seen a voluminous process which occupies, inwardly, 
a portion of the tibio tarsal articulation: this is the internal malleolus, The articular 
surface is not exactly formed to correspond with the whole articular surface of the 
astragalus. 

The fibula is a3 long as the tibia. It is prismatic, and slightly twisted on itself. It 
articulates above and below with the tibia. ‘lhe lower extremity responds to the astra- 
galus, and forms a prominence named the external malleolus, 

There is nothing particular to note in the patella. 

D. Foor.—The foot of Man is situated in a horizontal direction. Its upper aspect is 
convex; its inferior face is excavated, and it rests on the ground by its two extremities, 

1. Tarsus.—In the tursus there are seven bones, three of which are cuneiform The 
astragalus articulates with the tibia and fibula; it responds to the scaphoid by a well 
detached convex articnlar surface, named the head. 

In the bones of the lower row, it is remarked that the cuboid responds to the fifth 
and fourth metatarsals: the first cuneiform to the third; the second cunciform to the 
second metatarsal, and the third to the first. 

2. Metatarsus——The metatarsus is composed of five bony columns, nearly parallel to 
each other. They are enumerated from without to within, and increase in leneth from 
the first to the fourth; tle fifth is the shortest and most voluminous. = 


THE LIMBS IN GENERAL. 


‘3. Digital region.—This comprises five digits or toes. 
are analogous to those of the fingers, from which they are 
size, 


109 


ie phalanges of these toes 
They inerease in volume from the first to the fifth digit, Eee een 


RIGHT HUMAN FEMUR} 
ANTERIOR ASPECT. 

1, Shaft; 2, Head; 3, 
Neck; 4, Great tro- 
chanter; 5, Anterior 
intertrochanteric lines 
6, Lesser trochanter ; 7, 
External condyle ; 8, In- 
ternal condyle; 9, Tu- 
berosity for attachment 
of external lateral liga 
ment; 10, Fossa for ten- 
don of origin of popliteus 
muscle; 11, Tuberosity 
for attachment of in- 
ternal lateral ligament. 


HUMAN TIBIA AND FIB- 
ULA OF RIGHT LEG; 
ANTERIOR ASPECT. 

1, Shaft of tibia; 2, Inner 


tuberosity; 3, Outer 
tuberosity; 4, Spinous 
process; 5, Tubercle; 6, 
Internal surface of shaft; 
7, Lower extremity of 
tibia; 8, Internal mal- 
leolus; 9, Shaft of fib- 
ula; 10, Its upper ex- 
tremity; 11, Its lower 
extremity; between 1 
and 6 is the sharp crest 
of the tibia. 


DORSAL SURFACE OF LEFT 
HUMAN FOOT, 

1, Astragalus; 2, Its An- 
terior extremity articu- 
lating with the cuboid 
bone, 4; 3, 3, Calcis; 
4, Scaphoid; 5, Inter- 
nal cuneiform bone; 6, 
Middle cuneiform bone; 
7, External cuneiform 
bone; 8, Cuboid bone; 
9, Metatarsal bones of 
first and second toes; 
10, First phalanx of 
great toe; 11, Second 
ditto; 12, 15, 14, Pha- 
langes of second tae. 


Articte VI.—Tue Limes 1n GENERAL AND THEIR PARALLELISM. 


A. Tue Lmss my Gunnrat.—The interrupted columns which compose 
the limbs are destined not only to support the trunk in a stationary attitude, 
but also to transport it during progression. This double destination gives rise 
toa difference between the anterior and posterior members, The front limbs, 


110 THE BONES. 


being nearer the centre of gravity than those behind, have to sustain the 
largest share of the weight. They ought, consequently, to be specially 
organised as organs of support. Therefore it is that the four principal rays 
composing each of them—shoulder, arm, fore-arm, and foot—although flexed, 
or disposed to be flexed, in an inverse sense to one another, oppose to the 
pressure of the weight of the trunk, which tends incessantly to throw them 
down, obstacles purely mechanical, and of such energy that we may still 
understand how the body can be sustained on the anterior limbs, if we 
suppose all the muscular masses surrounding these bony rays removed except 
one. 

Thus, the weight of the body is at first transmitted to the scapula through 
the muscles thut attach that bone to the trunk. It then passes to the 
humerus, and from thence to the radius, to be thrown, finally, on the different 
pieces composing the foot. Now the humerus forming with the scapula an 
angle which is open behind, and with the bones of the fore-arm another angle 
open in front, the weight of the body pressing continually on these angles tends 
to close them, and thus cause the flexion of the bony rays. But this result is 
prevented by the combined action of two muscular powers—the biceps and 
the extensors of the fore-arm. With regard to the radius, carpus, and 
metacarpus, owing to their verticul direction they themselves support the 
pressure of the weight of the body without requiring any muscular aid. But 
the digital region, being directed obliquely forward and downward, forms, 
with the principal metacarpal, a third angle open in front, for the sustenance 
of which nature has given solid, inert, or contractile mechanical bands. 

The anterior limbs are also agents of transport, for they can elevate the 
trunk by the spring of their bony rays, and fix themselves on the ground by 
their free extremity. 

The posterior limbs are less favourably disposed than those in front to 
assume the function of columns of support, as their rays are for the most 
part in a state of permanent flexion, and joined in an angular manner to one 
another, as may be seen by glancing at the skeleton (See Figs. 1, 2, 8, 4, 
5). It is therefore necessary that muscular agency should prevent the 
breaking-down of these rays. Though defective as supporting columns, 
they are nevertheless admirably designed to serve as agents of locomotion. 
The slightest erection of these inclined rays propels the mass of the body 
forward, and this impulsion is almost wholly transmitted to the trunk in 
consequence of the very intimate union of the pelvis with the vertebral 
column. 

B. ParaubEL BETWEEN THE ANTERIOR AND Posterior Liwss.—After 
what has just been said, it will be seen that the anterior limbs are more par- 
ticularly destined for the support of the body, while.the posterior ones more 
especially play the part of impulsive agents in the locomotory acts. 

Notwithstanding this difference in the functions assigned them, these two 
columns offer in their conformation such striking resemblances to each other, 
that some authors have been inclined to consider the posterior as an exact 
repetition of the anterior limb. The following is a brief analysis of the 
analogies existing between them. 

At the end of the last century, Winslow and Vicq-d’Azyr, and nearer our 
own time, Cuvier, Flourens, Paul Gervais, Martins, Gegenbaur, and Lavocat, 
have occupied themselves with the parallelism existing between the anterior and 
the posterior members. All these anatomists did not absolutely arrive at the 
same conclusion ; for several of them, forgetting that the question should be 
examined in the whole animal series, made Man alone the subject of their 


THE LIMBS IN GENERAL. 111 


meditations. In such a matter, it must not be forgotten that the limbs are 
constructed with a view to their physiological functions, and that the 
differences remarked in examining them in several species are dictated by 
the kind of life the animals are intended to lead. ‘ 

Vicq-d’Azyr and Cuvier recommend that the anterior and posterior limbs 
of opposite sides should be compared. Martins and Gegenbaur, allowing a 
torsion of the humerus of 180°, advise that the two members of the same 
side should be collated, care being taken to make allowance for the 
untwisting of the 180° contortion at the lower end of the humerus. 
Lastly, Flourens and Lavocat contrast the two members of the same pair 
with each other, after placing the hand in a position of natural pronation by 
rotation of the radius on the ulna, and without turning either limb or ray, or 
even a portion of a ray, no matter what kind of animal may be under 
examination. We will adopt the latter proceeding, as it is the simplest and 
most natural. 

Parallel between the cora and scapula.—The analogies existing between 
these two bones are but little striking at first sight ; nevertheless, with atten- 
tion there is no difficulty in finding in the coxa the three pieces that enter 
into the composition of the shoulder. 

The ilium represents the scapula. The external iliac fossa reminds one 
of the supra- and subspinous fossee. Occasionally, there is met with in the 
Horse a rudiment of the crest dividing the iliac fossa into two parts, and, in 
some animals—the Pig, Sheep, and Goat—this crest, which is the trace 
of the scapular spine, becomes constant and very evident. 

With regard to the cotyloid cavity, it repeats in the posterior limb the 
glenoid cavity of the scapula. There remains to determine in the latter 
bone the portions analogous to the ischium and pubis. If we rely upon the 
evidence afforded by the muscular insertions, we come to the conclusion that 
the ischium corresponds to the coracoid process, and the pubis to the clavicle 
of animals which are provided with one. It will also be remarked that the 
coxa is directed backwards, while the scapula inclines obliquely forwards; 
this opposition in the direction of the bones in no way alters their analogies ; 
the functions of the members to which they correspond require this inverse 
position. 

Parallel between the femur and humerus—-The resemblance between 
these two bones is remarkable. Thus there is found in the first: 1, An 
articular head, better detached than that of the humerus, but shaped in the 
game manner; 2, A trochanter analogous to the great tuberosity, and also 
like it decomposable into three distinct parts—summit, crest, and convexity ; 
3, A lesser trochanter, representing the smaller tuberosity ; 4, An eminence 
for the insertion of the superficial gluteus muscle, which takes the place of 
the deltoid imprint; 5, An inferior articular pulley continued between the 
two condyles by a non-articular groove; this trochlea certainly corresponds 
to the median groove of the inferior humeral face. 

There are, no doubt, differences between the two bones, but they have 
no bearing upon the result just indicated. Thus the linea aspera of the 
femur is situated behind; that of the humerus in front. In the femur the 
two condyles of the inferior extremity are placed behind the trochlea ; the 
contrary holds in the humerus. These modifications are necessary in order 
to give the movements of the limbs a convenient direction. The leg is 
flexed backward on the thigh, while the fore-arm is flexed in front on the 
humerus. : 

Parallel between the bones of the leg and those of the fore-arm.—tt 1s 


112 THE BONES. 


more particularly in these two regions that the question of analogies has 
been resolved in a contradictory manner by anatomists. It would have 
appeared less complicated had it been studied in a large number of species, 

It has been pretended that the patella and the upper part of the tibia 
represent the superior extremity of the ulna and radius; and that the 
inferior portion of the ulna is represented by the fibula, and the lower part 
of the radius by that of the tibia. This opinion is erroneous. It is true 
that in Man the tibia and patella articulate with the femur, as the superior 
extremity of the ulna and radius responds to the humerus. But in quad- 
rupeds, whose thoracic members are destined to sustain the weight of the 
body, this disposition is no longer observed; the radius is seen to give 
support to all the humeral surface, just as the tibia receives the femoral 
surface; and, besides, the ulna becomes only a simple complement to the 
elbow articulation, as the fibula does to the femoro-tibial articulation. 

The tibia, therefore, corresponds to the radius, and the fibula to the ulna. 

The olecranon is represented by the superior nucleus of the fibula, and 
not by the patella. The latter bone is nothing more than a kind of sesamoid, 
intended to facilitate the action of the extensor muscles of the leg. It 
might be objected to this comparigon that, in the anterior limb, the extensor 
muscles are attached to the olecranon. But we reply that it matters little 
where the muscles which move the leg or arm are fixed on one or other 
of the two bones of these regions, because these bones act conjointly in the 
movements of flexion and extension. 

Parallel between the bones of the posterior and those of the anterior foot.— 
The analogy becomes so marked when these two regions are compared, that 
it is scarcely necessary to allude to it. The tarsal bones are to the posterior 
limb what the carpals are to the anterior one; it is even possible to compare, 
one by one, the several pieces in these regions. The metatarsals are but a 
repetition of the metacarpals; while the digital bones are so much alike that 
it is difficult to distinguish the anterior from the posterior phalanges. 


CHAPTER III. 


THE BONES IN BIRDS. 


Tuxse animals, destined for the most part to sustain themselves in the air, should 
exhibit in the conformation of their skeleton all the conditions which may favour zrial 
locomotion ; from this arise the differences which distinguish their skeleton from that 
of mammalia,—differences which will now be rapidly traced. 

Verteprat, CoLumn.— Cervical vertebrx.—The cervical stalk represents in the bird, 
as in the mammal, a kind of balancing pole curved like an 8, which supports the head, 
and by its changes of furm and direction varies the centre of gravity. When a bird 
rises in the air and flies rapidly, it lengthens the neck and stretches out the head to 
carry the centre of gravity forwards. But when it rests on the ground, it makes the 
balancing-pole assume the natural and more or less graceful inflection, by throwing the 
head backwards, and transferring the greater portion of the weight of its body to the 
columns of support formed by the posterior members. These displacements of the centre 
of gravity are executed in birds on a more extensive scale than in mammalia; the 
vertebral stalk in the former is also longer, lighter, and enjoys an excessive mobility. 

The vertebrae composing it number fourteen in fouls, twelve in the pigeon, fifteen in 
the duck, and eighteen in the goose; in the swan twenty-three have been counted :—a 
curious variety which singularly contrasts with the numerical unity noticed as one of 
the most remarkable characters in mammalia! These vertebra: are generally longer 
than in the latter class, and are particularly distinguished by the configuration of the 


THE BONES IN BIRDS. 113 


articular surfaces of the inferior part or bod iarthrodi 
c y. These are diarthyodial facets convex i 
ove sense and concave in the other, articulating the vertebral bodies by a alitable acd 


Fig. 73. 


o B. “ia 


SKELETON OF A FOWL. 
Spinous process of the third vertebra ; 2, Inferior 
lord prolongation of the transverse process of 


From Ato B, Cervical Vertebre.—1, 
ridge on body of the same ; 3, Sty 


114 THE BONES. 


reciprocal clamping. In this manner, the anterior head of the body of each vertebra ig 
replaced by a facet concave from one side to the other, and convex vertically ; while the 
posterior extremity of the bone bears, instead of a concavity, a facet convex in the lateral 
sense, and concave from above to below. The inferior crest of the body (fig. 73, 2, 2’) 
only exists in the first and last vertebre; but it forms a veritable spine. analogous to 
that observed in the lumbar vertebre of the rabbit. The spinous process (fig. 73, 1, 1’) 
only forms a simple crest in the middle part of the neck, it becomes more salient in 
the vertebres which occupy the two extremities of this region. The transverse process 
represents on the side of the vertebra a thick, obtuse, and irregular tubercle, situated 
under the anterior articular process, and pierced at its base by a large vertebral foramen 
(tig. 73, 4, 4°). It is most frequently furnished with a small styloid prolongation 
(fiz, 73, 3, 3’) directed backwards and downwards, forming an epiphysis at an early 
period, and representing a real undeveloped rib. 

The atlas has no transverse processes, This vertebra is shaped like a thin ring, 
and is excavated on its anterior contour by a small cavity into which is received the 
single condyle of the occipital bone. 

The axis shows a very marked odontoid process with a single facet under that 
eminence. 

Dorsal vertebra (Fig. 73. 8B, C.).—These are seven in the Fowl and Pigeon, and nine in 
the Goose and Duck, they are nearly always consolidated intoa single piece to which the 
trunk is fixed, and which gives the wings a solid support in the violent efforts that flight 
demands. The two or three last are often even covered by the wing-bones, and joined 
to them. The inferior crest of the body forms a very long spine, especially in the first 
vertebre. The spinous processes, flat, wide, short, and consolidated with each other by 
their opposite borders, constitute a long crest extending from the last cervical vertebra to 
the bones of the wings (fig. 73, 7). Tne transverse processes widen to their summit; in 
the fowl they are nearly constantly fused with each other. 

Lumbar and sacral vertebre.—All these vertebrae are formed exactly on the same 
type; so that it becomes difficult, if not impossible, to fix the point where the lumbar 
region ends or the sacral begins. At first independent of each other, these vertebra, 
numbering fourteen, soon become consolidated with one another and with the ribs; but 
their primitive separation is always indicated by the lateral septa which form, on their 
inferior face, the vestiges of the transverse processes. The former are closely united to 
the latter in the dorsal region. 

Coccygeal vertebra.—In the coccygeal region, the spine recovers its mobility. The 
tail of the bird, indeed, fulfils the office of a rudder to direct it during flight; and it is 
absolutely necessary that the vertebree which serve as a base fur the steering feathers 
should preserve their independence, so as to allow these to be carried to the right, left, 
downwards, or upwards. ‘These vertebre, seven in number, present spinous processes 
which are often bifurcated, transverse processes very developed, and sometimes even 
spines more or less long on the inferior surface of their bodies. The last vertebra is 
always the most voluminous; it is flattened on both sides, and terminates in a curved-up 
point. 

Heap (Fig. 73, F. G.).—The head of the bird is small, and of a conical form. The 
anterior extremity is elongated, and terminated by a pointed or flattened beak, which 
allows the animal to cut the air with more favility. ; 


- 


x 


the same; 4, Vertebral foramen of the same; 1’, 2', 3’, 4’, The same parts in the 
twelfth vertebra——From B to c, Dorsal Vertebra.—6, Spinous process of the first ; 
7, Crest formed by the union of the other spinous processes.—From D to E. Cocey- 
geal Vertebra.—r, G, Head.—8, Interorbital septum; 9, Foramen of communica- 
tion between the two orbits; 10, Premaxillary bone; 10’, External openings of 
the nose; 11, Maxilla; 12, Square bone; 13, Jugal bone.—u, Sternum.—14, 
Brisket or keel; 15, Episternal process; 16, Internal lateral process; 17, Lateral 
external process ; 18, Membrane which closes the internal notch; 19 Membrane 
of the external notch.—1z, etc., Superior ribs.—20, Posterior process of the 
fifth.—J, Inferior ribs; K, Scapula; L, Coracoid bone; m, Furculum.—m, m, Its 
two branches.—Nn, Humerus; 0, Ulna—o, Radius.—p, p’, Bones of carpus 
Q, Q', Bones of metacarpus; R, First phalanx of the large digit of the wing.—r, 
Second phalanx of the same.—r’, Phalanx of thumb; s, Ilium; s’, Ischium: s” 
Pubis.—21, Sciatic foramen; 22, Foramen ovale.—r, Femur} u, Patella; v, 
Tibia; x, Fibula—y, Single bone of tarsus.—Y, Metatarsus,—23, Superior process" 
‘representing a united metatarsal bone; 24, Process supporting the claw.— 
Z, etc., Digits. : 


THE BONES IN BIRDS. 115 


Bones of the cranium—tThe bones which compose the cranium are, as in mammalia, 
an occipital, parietal, frontal, ethmoid, sphenoid, and two temporals. These bones aro 
net isolated from each other, excepting during early life in the shell; and the ossifying 
process which unites them is so rapid, that the cranium, shortly after hatching, is 
already a single piece. No detailed description of the separate bones will be given here, 
but only a few brief observations which may be of some utility. 

Thus, the occipital bone shows for articulation with the spine only a single condyle, 
situated under the occipital foramen, and excavated by a slight groove. In palmipedes, 
this bone is pierced, behind the crests which give attachment to the extensor muscles, 
by two foramina which penctrate the cranium, and represent permanent fontanella. 
The parietal bone is feebly developed, and formed from only two primary nuclei. 
The frontal is the largest bone of the cranium; its orbital process is supported 
by a particular piece which is generally considered as belonging to the large wing 
of the sphenoid. The perpendicular lamina of the ethmoid is considerable, and 
forms between the two orbits a thin vertical septum (fig. 73, 8). Its posterior border is 
notched opposite to the optic foramen, and thus constitutes an opening which com- 
municates between the two orbital cavities (fig. 73, 9). It is also channeled, near its 
upper border, by a fissure which terminates by two openings at its extremities, one 
entering the cranium, the other the nasal cavities. ‘This fissure and these foramina 
permit the passage of the ethmoidal nerve, which in this way traverses the orbit before 
arriving at its destination. The ethmoddal cells are more membranous than bony ; their 
base is attached to a very delicate transverse plite, which is often membranous and not 
eribbled, and forms part of the «anterior orbital wall. These cells replace, at the same 
time, the lateral masses of the ethmoid and turbinated bones of mammalia. The 
sphenoid appears to be formed of a single piece, and shows on its sides two diarthrodial 
facets corresponding to the pteryguids. It is pierced by one foramen for the passage of 
the optic nerves; but this foramen opens on the outer and opposite side of the posterior 
notch of the interorbital septum, and thus allows each of the nerves passing through it 
to reach the eye for which it was intended. i. ; : ae 

It is worthy of remark, that an analogous disposition is also noticed in the rabbit. 
The temporal bones present at their base an articular surface corresponding to the square 
bone. In the fowl species, the zygomatic process forms a small flattened tongue, 
directed forwards, sometimes free, and at other times united by its superior border 
to the summit of the orbital process. These two eminences are exceedingly short 
in pigeons. In palmipedes they are consolidated and confounded so intimately, that it 
becomes impossible to distinguish them from one another. From this union results a 
long and strong process, which inclines forward and meets a purticular prolongation of 
the os unguis, forming with it areal bony arch. This arch limits, below and outwardly, 
the orbital cavity. : . 

Bones of the face—The supermaxilla ec mprises: a premaxilla, two nasal, two 
lachrymal, two palate, two pterygoid, two zygomatic bones, and a vomer. The inferior 
jaw has for its base a maxillary bone, which articulates with the cranium by means = 
two supplementary pieces named the square bones. The premaxillary bone is ee 
before hatching is completed, of two lateral pieces, which represent the two gos 
premaxillaries of mammals. This bone is very considerable, and of itself forms the base 
of the upper beak, whose form it determines; it is pointed and conical in the ga 
and wide and flattened above and below in palmipedes. In front it cireumscribes the 
external openings of the nose, and is prolonged superiorly into two lengthy pecs 
which dovetail between the nasal bones. Two inferior processes belonging also to ze 
bone concur in the formation of the palatine roof. The supermazillaries, Paes a 
the supermaxillaries of mammals, are two rudimentary bones situated on the a si - 
at the base of the beak. They form a part of the palatine roof and the wa ae i 
nasal cavities. The nasal bones circumscribe above, inwardly, and even et ar yp i 
external orifices of these cavities. The palate bones encircle, as in ee e on ura 
openings of the nose, and constitute in great part the roof of the palate a eir pee 

tremity lies against the pterygoids; the anterior joins the supermaxillaries an 
inf er praeen of the premaxillary bone. The pterygofds extend obliquely from the 
eohenriast the square bones, and are united to the sphenoid by diarthrouial articulation. 


1 i 1 is really striking, and might, in our opinion, serve a8 a basis for 
pena of ai interorbital septam. We are tempted, indeed, to consider 

flije We lamina as the inferior sphenoid and the middle portion of the ethmoid of birds. 
This a ee of viewing it tends to confirm the ideas of M. Tabourin on the inferior 


sphenoid and the ethmoid of mammals, 


116 THE BONES. 


The zygomatic bones have the form of two very thin stylets, and are united to the square 
bone by their posterior, and consolidated with the supermaxillary by their anterior 
extremity. The vomer separates the guttural openings of the nose from one another. 

The bones of the upper jaw are not fused with each other so rapidly as the bones of 
the cranium. The ascending processes of the premaxillary and nasal bones even remain 
for a long time united to the frontal bone by a simple synarthrodial articulation. This 
arrangement allows the upper beak to execute a certain elevating movement, of which 
we will speak when describing the articulations. . 

The inferior maxillary bone is originally formed of a great number of distinct seg- 
ments which are soon united into a solid piece. The square, petrous, or bone of the 
tympanum ought to be considered as detached from the temporal. It is prismatic in 
shape, and provided on its upper surface with a diarthrodial facet which unites it to the 
temporal, and on its lower face with another facet articulating with the branch of the 
maxilla. Outwards it joins the zygomatic bone, and inwards with the pterygoid: 
Behind, it gives attachment to the membrane of the tympanum; and in front it 
presents a small eminence of insertion which Meckel considered « second zygomatic 

TOCess. 

: Tuorax.—Sternum (fig. 73, H).—The sternum of birds, serving as a basis of support to 
the muscles moving the wings, should offer, and does in fact show, a remarkable degree 
of strength, because of the extraordinary volume of these muscles. And these being more 
powerful and energetic as the bird exhibits a greater degree of aptitude for flight, it results 
that the structure of the sternum is solid.in proportion as the bird is strong on the wing, 
For this reason we may infallibly pronounce as to the extent and power of a bird’s flight 
by an inspection of the sternum of individuals of its species. In this respect, however, we 
only announce what is well known to be a particular application of the rules established 
by the great law of concordance between the anatomical disposition of organs and their ~ 
physiological finality. 

Studied in Palmipedes, which will serve as a type for description, the sternum presents 
itself in the form of a large rectangular cuirass, elongate from before to behind, of itself 
constituting the inferior wall of the thoracic cavity, and also largely protecting the 
abdominal cavity. Its superior face is concave, while the inferior is convex, and entirely 
occupied by the insertion of the pectoral muscles. It presents, on the median line, a 
thin and very salient ridge, named the brisket (or keel), which in a remarkable manner 
multipiies the points of attachment of these muscles. The anterior border offers in its 
middle a small eminence of insertion, the episternal. Laterally, two articular grooves 
are seen which correspond to the coracoids. The posterior border is eut by two notches 
which are often converted into foramina. On the lateral borders are observed small 
double articular facets answering to the inferior ribs. The angles which separate these 
two borders from the anterior are both prolonged into a little eminence, named by some 
authors the costal process, 

In the Fowl, the sternum is not so strong as in the Goose or Duck. On each side of 
the brisket it shows two wide notches, which greatly reduce its substance. These 
notches, closed in the fresh state by membranes, are distinguished as external and 
internal. The latter, of greater size than the former, extends nearly to the extremity of 
the bone. From this division of the lateral plates of the sternum result two long and 
slender processes directel backwards. The external terminates by becoming widened, 
and forming a kind of bony plate, which covers the last inferior ribs. 

The sternum of Pigeons is distinguished by the enormous development of the brisket. 
The two notches of the fowl are also met with in these birds, but the internal is nearly 
always converted into a narrow foramen. 

This comparative study of the sternum in the chief domesticated birds leads us to 
appreciate the correctness of the principles just enunciated, wit! regard to the form and 
extent this bone may exhibit. The Gall/naceous Birds, properly so called, which fly 
little and badly, have the sternum singularly weakened by the deep notches cut in its 
lateral parts. With Palmipedes, the sternum is wide and but slightly notched, so that 
the goose and duck, which waddle along so awkwardly in our poultry yards, are capable 
of sustaining long and rapid flight, like that of the wild individuals of the same species. 
With regard to Pigeons, which are well known to be swift and powerful flyers, may this 
aloes i not be due to the extraordinary development of the keel which constitutes the 

risket ? 

Ritbs.—In the Fowl and Pigeon there are seven pairs of ribs; and in the Duck nine 
pairs. Articulated superiorly with the dorsal vertebra, as in mammals, these bones are 
provided near their middle with a flat eminence which commences at the posterior 
border, and is directed backwards and upwards to rest by its free extremity on the 
external face of the next rib, These eminences (Fig. 73, 20) form an epiphysis at an 


gh 


J 


THE BONES IN BIRDS. 


early period, and aro usually absent in the first and last ri i 
efficacious manner to increase the solidity of the thorax. Pe ENSY eo ta ae 


7 


or ribs by a diarthrodial articulation (Fig. 73,1. These 
ung, and all terminate at their lower extremity by a double 


1 , : ; they are nearly alwa 
absent in the two first ribs. It is not rare to see the last united to the one before it, 


instead of passing directly tu the sternum; in which case i i i 
er ae Pee case it comports itself like the 


ANTERIOR MemBers.—Shoulder-bone-—The shoulder 
ticular bone named the coracoid by Cuvier; and a clavi 
with that of the opposite side, a single bone called 
The scapula is narrow, elongated, and falciform, 
anterior extremity only forms a portion of the gleno 
a fibro-cartilage with the fork of the coravoid bone. 
represents the coracoid process of mammals, and 
obliquely from above downwards, and before to behind. Its superior extremity is often 
fused with the scapula, and united at an acute angle with that bone to form a portion of 
the articular cavity which receives the head of the humerus. Its inferior extremity is 
flattened from before to behind, and responds by a diarthrodial articulation to the 
anterior border of the sternum. The coracoid is long in birds which fly slowly ; it is, on 
the contrary, short, thick, and therefore very solid in quick flyers. The fork is a single 
bone, shaped like a V or U, situated at the base of the two wings, in front of the trunk, 
and in an oblique direction downwards and backwards. The two branches which form 
it represent the clavicles; they meet and are united at their inferior extremities, where 
they describe a curvilinear angle more or less open, attached to the brisket by means of 
a membranous ligament. Their superior extremity rests within, and opposite to the 
glenoid cavity, against the scapula aud coracoid, forming with these bones a remarkable 
foramen, through which passes the tendon of the elevator muscle of the wing (Fig. 73, 
A, 4, B,6). The fork plays the part of an elastic spring, whose office it is to prevent the 
wings coming towards each other during cpntraction of the depressor muscles. The 
conformation of this bone is, therefore, like the sternum, related to the extent and power of 
flight ; and for this reason it is that, in swift flyers, the two branches of the furculum are 
thick, solid, widely separated, and curved like a U; while in those which fly heavily and 
with difficulty, these branches are thin and weak, and joined at an acute angle. The 
latter formation greatly diminishes its strength, and lessens, in a singular manner, 
the reactionary power of the bony arch it represents. 

Bone of the arm.—The humerus offers an articular oval-shaped head, and an air- 
opening placed beneath this eminence. It is long in Palmipedes, ordinarily so in the 
Gallinace proper, and very short in Pigeons. 

Bones of the fore-arm.—The radius is much less voluminous than the ulna. The 
latter has an extremely short olecranon; and the two bones are separated from one 
another in their middle part to meet again at their extremities, where they are united 
by ligamentous bands in such a way as to render the movements of pronation and 
supination impossible. This mode of fastening, which nevertheless does not prevent the two 
bones from gliding slightly on each other in the direction of their length, has been wisely 
adopted by nature in order that the wing might strike the air, like an oar, by its inferior 
face ; otherwise, the resistance of the aerial medium would make these two bones pivot, 
and cause the wing to present itself to the air in a wrong direction. 

Bones of the carpus.—These are only two, and are distinguished by the names of 
radius and ulna, in consequence of their corresponding more particularly to these bones 
in other animals. . 

Bones of the metacarpus.—These also number only two, and are separated at their 
middle portion, to be consolidated at their extremities. aA 

Bones of the digital region.—The wing of a bird is composed of three digits. One 
of them, which resembles the thumb and forms the basis of the false wing, is composed 
of a single styloid-shaped phalanx, articulated at the base of a small particular process 
belonging to the superior extremity of the largest metacarpal bone. The largest digit 
comprises two phalanges which succeed the last bone. The third digit is represented by 
a small rudimentary phalanx, which corresponds to the inferior extremity of the small 
metacarpal bone, and lies beside the first phalanx of the large digit in the closest manner. 

It is well to remark that the hand and tie fore-arm are longer in proportion to the 
qnality of flight ; those two regions of the wing, for example, are very short in Gallinaceous 

rds. : Fae 
= De Mempers.—Coca or os iliac.—This is a voluminous and very solid piece, 


11 


comprises: a scapula, a par- 
cle, which forms, in coalescing 
the fork ( furculum), or os furculare, 
and shows no trace of a spine. Its 
id cavity, and is united by means of 
The latter is so named because it 
is a long prismatic bone, directed 


118 THE BONES. 


particularly in walking birds, and composed, as in the mammalia, of an ilium, ischium, 
and pubis, The ilium is consolidated with the last dorsal, the lumbar, and the sacral 
vertebree; it is excavated on its internal face. The ¢schium partly incloses the side of 
the pelvic cavity ; between its internal border and the external border of the ilium is an 
orifice which replaces the great ischiatic notch, Its inferior border is united to the pubis. 
The latter is thin and elongated, and follows the direction of the inferior border of the 
ischium, with it circumscribing an oval opening more or less spacious. Its inferior 
extremity extends beyond the ischium to curve inwards towards that of the opposite side, 
but without uniting with it. We do not, therefore, find the pelvic symphysis in birds, 
and the pelvis is widely open below, a circumstance which favours the passage of the 
egg through the cavity and out of the cloaca. The cotyloid cavity is perforated by an 
opening at the bottom which traverses the bone. 

Thigh bone.—The femur is articulated inferiorly with the patella, tibia, and fibula. In 
all walking birds, like the gallinace, it is long and strong, as well as the rays below it. 

Leg bones.—The patella is wide aud thin. The tibia terminates, below, by two con- 
dyles separated by a groove which becomes articular behind. The fibula articulates 
by its head with the external condyle of the femur, and is consolidated with the tibia; 
it never descends to the inferior extremity of that bone. 

Tarsal bones.—The tarsus appears to be altogether absent in birds. Nevertheless 
we may venture to consider, as a vestige of the bones of this region, a small bony nucleus 
buried in a fibro-cartilaginous mass which glides on the posterior pulley of the tibia. 
This nucleus represents the calcaneus of mammals. 

Metatarsal bone —A single metatarsal bone is found in birds, articulating superiorly 
with the inferior extremity of the tibia, and terminating inferiorly by three pulleys 
which support the three principal digits. This bone shows in the Fowl, near its inferior 
third, a conical process turned backwards, which serves as a base for the spur. Behind 
its superior extremity, it exhibits another which may be considered as a consolidated 
metatarsal bone. 

Bones of the digital region.—All the domesticated birds have four digits on the inferior 
members: three principal, directed forwards, and one rudimentary, carried backwards. 
The first, designated as internal, median, and external, articulate with the inferior 
pulleys of the metatarsal bones. The internal is formed by three phalanges, the second 
has four, and the third five. These phalanges are formed something like those of t: e 
carnivora: the last is pointed, conical, and enveloped in a horny sheath. The fowh 
digit, or thumb, is composed of three pieces; one of these, the first, is generally con- 
sidered as a rudimentary metatarsal bone. It is attached by fibro-cartilaginous tissue 
a the inner and posterior aspect of the inferior extremity of the principal metatarsal 

one, 


CHAPTER IV. 
THEORY OF THE VERTEBRAL CONSTITUTION OF THE SKELETON. 


In the series of vertebrated animals the bony pieces of the trunk bearing 
the name of vertebre are those which offer the highest degree of fixity, and 
to which the existence or the arrangement of the others appears to be subor- 
dinate. This feature in organisation, recognised by E. Geoffroy Saint- 
‘Hilaire and Professor Owen, has caused these.men of science to assert that 
the type of construction of vertebrated animals is the vertebra. 

After E. Geoffroy Saint-Hilaire and Professor Owen, several German, 
English, and French anatomists have studied the vertebral composition of 
the skeleton ; and among the works published in France on this subject must 

be specially noticed those of M. Lavocat.! In principle, all the writers 
have arrived at the same conclusions, and only differ in some few details. 

It is certain that the base of the vertebral column is formed by a series 
of bony segments. Each of these segments is called an osteodesm, and each 


. osteodesm represents the body or centrum of a vertebra. 


(The distinguished anatomist and Director of the Imperial Veterinary School of 
. Toulouse.) 


THE VERTEBRAL CONSTITUTION OF THE SKELETON. 119 


In examining the dorsal region, it is evident that to the body or centrum 
of a vertebra are added two complete osseous arches, a superior and an 
inferior. The superior arch is formed by the vertebral lamina; the inferior 
by the ribs, the cartilages, and a portion of the sternum. The first is desig- 
nated the neural arch, because it furnishes a protecting sheath for the 
nervous centres; and the second, which more particularly protects the 
vascular system, is called the hemal arch (see Fig. 10). 

The hemal arch may have prolongations or appendices more or less 
developed, and comparable to the apophysary prolongations of the ribs in 
birds and some fishes. 

Such is the general composition of a typical vertebra; but there are 
a to be distinguished in the neural and hemal arches the following 
parts :— 


NEURAL ARCH. HEMAL ARCH, 
1. Neural parapophysis =the posterior - Hemal parapophysis = the tuberosity 


costal cupola. of the rib, 
2. Neural metapophysis = the anterior . Hemal metapophysis = the head of the 
costal cupola. rib. 


3. Neural diapophysis = the summit of the . Heemal diapophysis = the rib proper. 

transverse process. . Heumapophysis = the costal cartilage. 
4, Neurapophysis = the vertebral lamina. . Hemal spine = the corresponding 
5. Neural spine =the summit of the sternal portion. 


spinous process, 


OUP oo nw land 


The vertebrae sometimes depart more or less from the model just 
described. They may vary not only from one species to another, but also 
in the same animal, and even in the same region. Thus the neural arch 
may be absent, as has been observed in certain coccygeal vertebre ; or the 
hemal arch is incomplete or null, as in the cervical or lumbar vertebre ; or, 
lastly, the arches are often unequal; though this inequality is of no import- 
ance, since their size is in relation to the volume of the parts they should 

rotect. 
- Notwitstanding these differences and variations, or the transformations 
experienced by certain parts, there is not a bone in the skeleton which can- 
not be included in the vertebral type. 

The vertebra being admitted as the type of construction of the skeleton, 
it is easy to find it in all the regions of the bony framework. In the 
thoraco-abdominal region, the centrum, neural arch, and hemal arch are 
readily perceived ; in the lumbar vertebre, the enormously developed trans- 
verse process indicates the existence of an infravertebral arch. 

In the sacral region, the bony girdle of the pelvis represents the hemal 
arch. The posterior limbs, articulating with the bones of the pelvis, belong 
to the hemal arch, and should be considered as appendices of this arch, 
analogous to the costal appendices of birds. ; ae 

The cervical region may be compared to the sacral region; as in it the 
inferior hemal arch is represented by the osseous ring supporting the 
anterior imbs—the scapulo-clavicular cincture. The limbs themselves are 
appendices of the cervical hemal arch. oy 

Difficulties begin to appear when the extremities of the trunk—the head | 
and coceyx—come to be examined. Nevertheless, the composition of the 
coccyx is revealed when the caudal vertebre of certain fishes, especially 
those of the pleuronectide, in which the neural and hemal arches are com 
plete, are examined. But the vertebral constitution of the head remained 
for long time an insoluble question, or was solved in a contradictory 


120 THE BONES. 


manner by the naturalists who attempted it. Some admitted a single 
cephalic vertebra; others admitted three or four ; while others again arrived 


at six or seven. : _ 
These difficulties and contradictory results may be understood, when it is 


2, Parieto-maxillary vertebra; 3, Fronto-mandibular vertebra ; 
4, Naso-turbinal vertebra. 


CEPHALIC VERTEBR& OF THE DOG.—After Lavocat. 


1, Occipito-hyoideal vertebra ; 


borne in mind what profound modifications the vertebra must have ex- 
perienced to constitute the bones of the head 

At present the problem appears solved. The head is composed of four 
vertebre, in which are found the various parts enumerated in the description, 
of the typical vertebra. 


THE VERTEBRAL CONSTITUTION OF THE SKELETON, 121 


In the four classes of vertebrata, the head is constantly formed of four 
vertebrae, which are determined as follows :”! 


| VERTEBRA, CENTRUM. | NEURAL ARCH, : HASMAL ARCH. 
\ : ! 
Occipito-hyoidel. Basilar process | Occipital (3 pieces). | Hyoideal appa- 
, of the Occipi- | Mastoid walls of the | 1atus (5 pieces). 
tal. » ‘Tympanum. H 
Sao 
| Parieto-maxillary. | Body of the pos- | Wing and _ pterygoid | Inferior Maxilla 
i i terior Sphe- | process of the pos | 5 pieves), 
3 noid. {terior Sphenoid. | 
| Squamous portion and 
‘ zyyomatic process of | 
| the Temporal. { 
Parietal. ! 
i 
Fronto-mandibular, , Body of the | Wing and_ pterygoid | Jugal. 
Auterior Sphe- | process of the anterior | Lavhrymal, 
noid. | Sphenoid. ‘ Palatine. 
| Posterior Frontal and , Supermaxillary. 
its orbitul process. ; Premaxillary. 
' Frontal. | 
| 
Naso-turbinal. Vomer, Ethmoid. | Turbinated 
Nasal. | Subetumoidal, 
I 


The number of cephalic vertebre is invariable, as each is destined to. 
lodge the organs of one of the four senses. The occipito-hyoideal lodges the 
principal organs of hearing; the paricto-maxillary osteodesm protects the 
sense of taste; finally, the organs of vision are sustained by the fronto-man- 
dibular vertebra, while the naso-turbinal contains the sense of smell. 

It was therefore with reason that Geoffroy Saiut-Hilaire and Professor 
Owen proclaimed that the type of construction of the vertebrated animals is 
the vertebra. 


SECOND SECTION. 


Tue ARTICULATIONS. 


CHAPTER I. 


THE ARTICULATIONS IN GENERAL. 


Tux different pieces constituting the solid framework of the animal body 
are, as has been said, united in such a manner that they can move one upon 
the other From this union results the articulations or articular joints, whose 
construction will now be referred to in a general manner, before commencing 
a particular description of each. 
To form articulations, the bones correspond to each other by certain 
points of their periphery, which are named articular surfaces. Every articu- 


1 Lavocat, ‘ Nouvelles études sur le systeme vertébral,’ 1860, 


122 THE ARTICULATIONS. 


lation is, therefore, essentially constituted by two opposite osseous surfaces, 
which are moulded to each other. These are either contiguous, independent, 
and very movable—continuous with each other by means of a cartilaginous 
substance which condemns them, if not to total immobility, at least to very 


Fig. 75. 


A 


| —~2 


PLANS OF THE DIFFERENT GLASSES OF ARTICULATIONS. 


A, Suture.—1, Periosteum; 2, Sutural ligament.—b, Amphiarthrosis; a, First 
degree.—l1, Periosteum; 2, Articular cartilage; 3, Interarticular ligament.—d, 
Second degree; 4, Single cavity in the interarticular ligament.—c, Third degree ; 
5, Double cavity in the interarticular ligament.—c, Diarthrosis; 6, Simple 
diartinrosis—1, Periosteum; 2, Articular cartilage; 3, Epithelial layer of the 
synovial membrane—dotted line; 4, Fibrous capsule; 5, Cul-de-sac of the syno- 
vial membrane ; 6, Fibrous layer of the synovial membrane.—e, Double diarthrosis ; 
7, Interarticular meniscus; 8, 9, Cavities of the two synovial membranes. 


limited movements : or united by a fibro-cartilage whose elasticity permits a 
certain degree of displacement between the bones which are in contact. 

In the first case, the articulations are classed as diarthroses, or movable 
articulations. 

In the second, they are designated synarthroses, sutures, or immovable 
articulations. 


THE ARTICULATIONS IN GENERAL, 123 


In the third, they are amphiarthroses, or mixed articulations; so termed 
because they participate in the movements of the other two classes ; synar- 
throses, by the continuity established between the articular surfaces; and 
diarthroses, by the extensive motion they permit. 

The general characters that distinguish each of these three great classes 
of articulations will be successively studied. 

(The study of the articulations, or rather of the ligaments, is termed 
syndesmology—from ovv, together, and decpds, bond; or arthrology—from 
&pOpov, a joint, and Adyos, a description. ) 


GENERAL CHARACTERS OF DIARTHROSES. 


We ought to consider in the diarthrodial articulations: 1, The con- 
tiguous bony surfaces which form them ; 2, The cartilaginous layer (cartilages 
of incrustation) which cover these; 3, The fibro-cartilaginous tissue (articular 
jibro-cartilages) which complete them, when they are not shaped so as to be 
reciprocally adapted to each other; 4, The kgaments which maintain them 
in contact; 5, The serous membranes (synovial capsules) that cover the 
internal face of the latter, and which secrete the synovia, a kind of animal 
oil that facilitates the gliding of the articular surfaces; 6, The movements 
of which these articulations may be the seat; 7, Their methodical classifica- 
tion; 8, Their nomenclature. 

ARTICULAR SurFaces.—These surfaces have the common character of 
being destitute of asperities, so that they can glide with the greatest facility 
on each other. They are designated, according to their form, by the names 
of facets, heads, condyles, cotyles, glenes, pulleys, etc. There is no need to 
revert to their general description, as they have already been sufiiciently 
studied in the osteology; so we will confine ourselves to repeating that 
they are found at the extremities of long bones, on the faces of short bones, 
and on the angles of wide bones." We may mention also that they are often 
excavated by one or several hollows named synovial fosse, a sort of natural 
reservoirs which receive the unctuous fluid secreted by the interarticular 
serous membranes. 

Carntitaces or Incrustation.—This designation is given to the layers of 
cartilaginous matter which, as it were, varnish the articular surfaces they 
adhere to by their inner face; their free surface is distinguished by a 
remarkable polish and brilliancy Thicker towards the centre than at the 
circumference when they cover bony eminences, these cartilages show an 
inverse disposition when they line cavities. They are elastic, of a pearly 
whiteness, and resisting, though they are soft enough to be cut by a sharp 
instrument; in a word, they possess all the physical characteristics of the 
primary cartilage of bones They appear to be formed of parallel fibres 
placed perpendicnlar to the bony surfaces, and implanted it. these by one of 
their extremities ; the opposite extremity corresponding to the free surface 
of the cartilage. Viewed by the microscope. they are found to consist of a 
fundamental substance excavated by small cavities The cartilage of 
incrustation therefore belongs to the group of true or hyaline cartilages. 

The fundamental matter is amorphous and homogeneous, and more or 

-less transparent, according to its thickness. It is transformed into chondrine 
by boiling in water. 

The cavities are irregular, and more or less wide. They contain from 
one to five cells whose walls are very thin, and their contents slightly gran- 
ular; in the centre of each cell is a nucleus with a nucleolus. These 


124 


cavities are elongated and directed 
articular surface in the deep layer ; 


THE ARTICULATIONS. 


almost perpendicularly towards the 
in the middle layer they are oblique, 


and are parallel to the surface of friction in the superficial layer. 


SECTION OF BRANCIIIAL CARTILAGE OF 
TADPOLE. 

u, Group of four cells separating from each 
other; 0, Pair of cells in apposition ; ¢, c, 
Nuclei of cartilage-cells; d, Cavity con- 
taining three cells. These cells are im- 
bedded in the finely-granular matrix, or 
fundamental substance, 


(Under a high magnifying power 
the fundamental substance, or matrix, 
loses its homogeneous and amorphous 
character, and appears to be granular 
or faintly striated. In the midst of 
this granular matrix, the lacune or 
cavities are observed to contain from 
one to six different-sized cells. It 
has been stated that a membrane lines 
these spaces. In addition to the 
granular matter observed in the cells, 
it is not rare to find fat globules, 
The nuclei of the cells vary from 
soba 10 s2yq of an inch in diameter. 
The cells multiply endogenously.) 

The cartilage cells are insoluble 
in boiling water; consequently, so far 
as their chemical composition is con- 
cerned, they are distinct from the 
fundamental substance. 

The diarthrodial cartilages receive 


neither vessels nor nerves. The 
presence of cartilages of incrustation in the articulations is of the greatest 
importance. When they are worn, absorbed, or transformed into bone in 
consequence of certain articular maladies, the movements become painful and 
very difficult. With regard to the part they play in the economy, it may 
be said that: 1, They favour, by their smoothness, the gliding ard displace- 
ment of the bones, 2, They attenuate, by their suppleness and elasticity, 
the violent shocks to which the articulations are exposed; 3, They resist the’ 
wear and deformation of the articular surfaces. 

CompLemuntary Fisro-cantinaces.—There are several kinds of com- 
plementary fibro-cartilages :—Some (interosseous) represent circular cushions 
which bolster the margins of certain cavities, filling up the notches which 
might render them imperfect. They increase the depth of these cavities 


Fig. 77. 


FIBRO-CARTILAGE, MAGNIFIED 155 TimEs. Showing interlacement of fibrous 
fasciculi, with scattered groups of cartilage-cells, 


and protect their borders from injury. Others (interarticular) are inter- 
posed between articular surfaces when these do not exactly fit each other, as 


THE ARTICULATIONS IN GENERAL 125 


when two opposing extremities are convex. It may be remembered that the 
lateral tuberosities of each tibial surface present, for articulation with the 
condyles of the femur, two convex diarthrodial faces whose coaptation is 
rendered perfect by the interposition between each condyle and correspond: 
ing tibial surface of a crescent-shaped fibro-cartilage, which for this reason 
has been named a meniscus. In other joints these interarticular fibro- 
cartilages are shaped like discs or biconcave lenses. There then result 
double diarthroses :—example, the temporo-maxillary articulation. (Fibro- 
cartilage also covers bony surfaces over which tendons play, as on the 
trochlear surface of the humerus, postero-inferior face of the navicular bone, 
and elsewhere. In these situations it is named stratyform Jibro-cartilage.) 
These organs are formed, as their name indicates, by fibrous and car- 
tilaginous tissue; their mode of association need not be referred to here, 
though it may be observed that the cartilage is more particularly found in 
all those points where there is most articular friction. They receive vessels, 
and sometimes nerves, 

Licaments.—These are bands which unite contiguous diarthrodial 
surfaces. They are sometimes formed of white fibrous tissue, and some- 
times of yellow; from whence their division into two great classes of white 
and yellow ligaments. 

a. The white ligaments are distinguished by the pearly whiteness of 
their tissue and want of elasticity. Those which are found on the outer 


Fig 78 Fig 79. 


if vt Y Le \ ik 
NE aN (AINA 
a LN 7 
MAR 


WHITE OR NON-ELASTIC FIBROUS YELLOW OR ELASTIC FIBROUS TISSUE, FROM 
TISSUE. THE LIGAMENTUM NUCH. 


} 
Ah 
\) 
) 


oi) 
Coy oe i 


aspect of the articulations are termed peripheral, and those in their interior 
are designated interosseous or interarticular ligaments. 

The peripheral ligaments are generally composed of parallel fibres 
collected in fasciculi, or spread out as membranes. In the first they are 
called funicular, or ribbon-shaped; in the second, they are termed mem- 
braniform, or capsular. The funicular ligaments constitute short, round, or 
flattened bands, attached by their extremities to the two bones they unite; 
they are lined on their inner aspect by the synovial capsule, and covered 
externally by tendons, aponeuroses, muscles, vessels, or nerves. The 
capsular ligaments are often complete—that is to say, they envelope the 
whole articulation like a sack. At other times they are incomplete, and 


126 THE ARTICULATIONS. 


then they are simple membranes, binding together the different funicular 
bands of a joint. . 

The interosseous ligaments, less numerous than the preceding, are often 
formed of interlacing fibres; they are always funicular, and fixed by their 
extremities into excavations in the centre of articular surfaces. 

b. The yellow ligaments are all peripheral, funicular, or membranous, and 
enjoy a marked degree of elasticity, which permits them mechanically to 
bring back to their usual position the bony levers which have been momen- 
tarily displaced. These ligaments, which are powerful auxiliaries to the 
muscular forces, are destined to give equilibrium in a permanent manner to 
the weight of certain parts of the body which incessantly tend to fall to the 

round. 
‘ SynovraL CapsuLes.—These are very thin membranes of a serous nature, 
intended to secrete the synovia. They are composed of two layers: a deep, 
formed by fasciculi of the connective tissue; the other, superficial, is of 
an epithelial character. The first sometimes adheres intimately to the inner 
face of the funicular or membranous ligaments of the articulation ; at other 
times it is loosely attached to them by an abundance of connective tissue. 
The second layer is constituted by a single row of flattened polygonal cells. 

It is generally admitted that the synovial membranes comport themselves 
like the other serous membranes, by forming sacs which are everywhere 
closed. According to this admission, a synovial membrane, after covering 
the internal face of the peripheral ligaments of a diarthrodial articulation, 
ought to be prolonged on the free surface of the cartilages of incrustation, 
and should give them their brilliancy and polish, But it is necessary to 
state that this is a pure hypothesis, against which rises a multitude of care: 
fully-observed facts. The discussion of these belongs to general anatomy, 
but they will be referred to here as briefly as possible. 

1. If direct observation be consulted, it gives on this debated subject 
the most precise information; the cartilages are uncovered, and there is 
no synovial membrane on their face. The anatomists who have mistaken for 
this membrane the thin pellicle which it is possible to render evident on the 
cartilages in obliquely cutting their substance and separating morsels by 
tearing it off, were evidently deceived. This pellicle has nothing of a serous 
nature in its texture; it is not vascular, for it has never been possible to 
inject vessels on the surface of cartilages, nor yet in their thickness; it is 
not covered by epithelium; and submitted to microscopical examination, it 
exhibits all the characters of the amorphous matter of cartilage. It ought, 
then, to be considered as a cartilaginous pellicle, detached from the super- 
ficial layers of the articular surface—a pellicle which it has always been 
impossible to find on cartilages which are quite fresh; and it has never 
been possible to observe it without giving, by a preliminary desiccation, a 
certain degree of tenacity to the cartilaginous substance about to. be 
examined. 

2. Pathological facts prove nothing in favour of the existence of a 
synovial membrane on the cartilages. Hypertrophy of this pretended 
membrane has never been witnessed ; the fungosities looked upon asa result of 
this hypertrophy are derived from another source. It has been demonstrated 
that they extend, in certain cases, from the articular margins of the cartila- 
ginous surface, whence their successive invasions may often be followed. In 
other cases, the vegetating membrane which constitutes them appears in the 
centre of the articular surfaces, at points deprived of cartilage ; they after- 
wards extend to a certain distance on the remaining cartilage. 


THE ARTICULATIONS IN GENERAL, 127 


3. It may be asked of the partisans of the opinion now combated, how 
they can believe in the existence of a serous membrane between two 
articular surfaces, without its being exposed to bruises and destruction a 
thousand times in the day? Do they take into account the amount of 
pressure sustained by certain articulations, and the intense friction to which 
their surfaces are submitted? Have they compared the intensity of these 
destructive influences, with the delicate texture of the serous membranes, 
and their great inflammatory susceptibility ? It is sufficient to lightly touch 
in this way the weak side of our adversaries’ argument, and to conclude the 
third portion of this discussion: There is friction between the cartilages 
of the two opposed articular surfaces, therefore there must be wear, this is 
a physical law which no body escapes, let it be as hard as the diamond, or as 
soft as caoutchouc. And if there is wear between these rubbing surfaces, 
there cannot be an irritable and sensitive membrane lying on the inert and 
insensible strata which constitute them. In fine, a synovial membrane, 
after being fixed to the margin of the articular cartilage of a diarthrodial 
joint, is reflected in every direction to cover the inner aspect of the liga- 
ments, and becomes attached to the periphery of the diarthrodial surface 
corresponding to the first. 

There are generally found within articulations little masses of fat which 
push the synovial membrane enveloping them inwards. Erroneously con- 
sidered by Clopton Havers as glands for the secretion of synovia, these 
accumulations of fat have been named synovial fringes. They are more par- 
ticularly numerous in the neighbourhood of the articular margins: that is, 
on the edges of diarthrodial surfaces. 

The synovia is a viscid, colourless, or slightly yellow fluid, in its physical 
characters somewhat resembling oil; it does not possess them, however, 
so far as its composition is concerned, for chemical analysis has not 
demonstrated the presence of fatty principles. It is the albumen it contains 
which gives it its viscidity, and which fits it for lubricating the articular 
surfaces over which it is spread. Its use in the animal economy is 
absolutely identical with that of the greasy substances employed to lubricate 
the axles of carriages. : 

Movenents.—The movements peculiar to diarthrodial articulations are 
divided into seven principal classes : 


1. Simple gliding, the only movement possible between two plane or 
undulating facets. 

2. Fleaion, which brings two bony pieces nearer each other by closing 
more or less their angle of union. 

3. Extension, the inverse movement, during which the bones are 
straightened on each other. 

4, Adduction, which brings the inferior extremity of the movable bone 
towards the median line. 

5. Abduction, the contrary movement to the preceding 

6. Circumduction, or the sling movement, during which the bone passes 
successively through the last four positions. 

7. Rotation, in which one bone pivots on another 


CragsrricaTIon or THE DiarrHroses.—The basis of this classification is 
founded on the configuration of the articular surfaces and_the nature of the 
movements they permit. This double base serves to establish five kinds of 
diarthrodial articulation - eget 

1, Enarthrosis, characterised by the reception of an articular head within 


128 THE ARTICULATIONS. 


a cavity of appropriate form. This articulation may be the seat of the most 
extensive and varied movements: flexion, extension, abduction, adduction, 
circumduction, and rotation. Example: the coxo-femoral articulation. 

2. The trochlean, angular ginglymoid, or perfect hinge articulation, 
when the articular surfaces are formed into trochlea, reciprocally fitting 
into each other, and whose movements—flexion and extension only—are 
executed with the precision of a hinge. Example: the tibio-tarsal ar- 
ticulation. : 

3. The condyloid, or imperfect hinge articulation, which permits, like the 
preceding, the two principal movements of extension and flexion, and the 
accessory movements of rotation or lateral inclination. The articular 
surfaces, fhough very diversely shaped, nevertheless exhibit in all the 
articulations one or more condyles opposed to an equal number of oval 
excavations. Example: the femoro-tibial articulation. 

4, The pivot, trochoid, or lateral ginglymoid articulation, is a diarthrosis 
formed by a pivot which turns in a senti-cylindrical cavity. Rotation 
is the only movement. Example: the atlo-axoid articulation. 

5. Arthrodia, or planiform diarthrosis, is constituted by plane, or nearly 
plane facets. Gliding is the only possible movement. Example: the carpo- 
metacarpal articulation. 

Nomznciature.—The names of the articulations are usually those of 
the bones which form them. For instance, the scapulo-humeral articulation 
is the joint between the scapula and humerus ; the intervertebral articulations 
join to each other the various pieces constituting the spine. When the 
qualifying name of an articulation is composed of two elements, as in the 
first instance, it is well to place first the word which indicates the bone 
usually most fixed. 


GENERAL CHARACTERS OF THE SYNARTHROSES. 


Sutures are the temporary articulations which exist only at an early 
period of life. They nearly all disappear in the adult animal, in con- 
sequence of the.bones forming them becoming consolidated. They belong 
almost exclusively to the bones of the head. 

ArricuLar Surraces.—The bones forming these come in contact by their 
borders or angles, which, for this purpose, generally present very anfractuous 
surfaces. 

Sometimes they are cut perpendicularly and simply roughened; at 
other times they are bevelled and joined by means of fine lamine or trifling 
inequalities; again, they are notched into deep and sinuous dentations; 
and lastly, one bone is fixed into a groove cut in the other. It will be 
understood that such conformations of the articular surfaces ought to limit 
their movements and assure the solidity of their union. 

Moves or Union.—Cartilage interposed between these synarthrodial 
surfaces directly unites them to each other. It absolutely possesses the 
same texture as the primary cartilage of the bones, and like it, has the 
property of becoming ossified after having been vascularised. This ossi- 
fication, which causes the disappearance of the sutures, occurs earlier 
inwards than outwards. The periosteum, in passing from one bone to 
another, adheres intimately to the sutural cartilage, and also aids in bringing 
about a more complete synarthroses. It should, therefore, be included in 
their means of union. 

Movements.—These are very obscure, and only noticeable in young 


ARTICULATIONS OF MAMMALIA IN PARTICULAR. 129 


animals by the elasticity they communicate to the bony walls of the cranium 
or face. In the adult, they may be said to be null. 
Crassirication.—There are four principal descriptions of sutures : 

_ 1. When two wide bones correspond by means of denticulations fitting 
into each other, the suture is named frue or dentated. Example: the 
articulations uniting the three portions of the parietal bone. 2. If the 
opposed borders of two bones in contact are widely bevelled, one inwards, 
the other outwards, it forms a scaly or squamous suture. Example: the 
parieto-temporal articulations, 3. When the union of bones takes place 
by plane or roughened surfaces, evt perpendicularly on their borders or 
angles, this constitutes the harmonia suture, or suture by juxtaposition (or appo- 
sition). Example: the occipito-temporal articulations. 4. The schindylesis, 
or mortised suture, results from the reception of a bony plate into a groove 
more or less deep in another bone. Example: the spheno-frontal and 
supermaxillo-nasal articulations. 


GENERAL CHARACTERS OF THE AMPHIARTHROSES OR SYMPHYSES,. 


ArticuLar Surraces.—They are frequently smooth, and formed almost 
on the same model as the diarthrodial surfaces. They are covered by a 
thin layer of cartilage, but instead of being smooth and polished, they are 
more or less rugged, without, however, presenting the anfractuous disposition 
of the majority of synarthrodial surfaces. 

Moves or Unton.—The organs which perform this office are: 1, The 
fibro-cartilage which establishes continuity between the articular surfaces ; 
2, Ribbon-shaped or peripheral ligaments. These latter do not differ from 
the analogous bands attaching the diarthrodial articulations. With regard 
to the fibro-cartilage, it is distinguished from the complementary discs of 
these same articulations by a less intimate mixture of the cartilaginous and 
fibrous elements entering into its composition. The last may be sometimes 
absent, as well asthe peripheral bands; and then the articulation only differs 
from the synarthroses by the extent of motion it permits Occasionally the 
interarticular fibro-cartilages are excavated by one or two little narrow cavities ; 
but these are never lined by a synovial membrane like the diarthrodial 
cavities, 

Movements.--The amphiarthroses only permit of a see-saw or swinging 
movement. the extent of which depends on the thickness of the intermediate 
fibro-cartilage. 

Cuasstrication.—Only one kind of amphiarthrosis is recognised, the 
most remarkable example of which is found in the articulations between the 
bodies of the vertebra. 


CHAPTER II. 


ARTICULATIONS OF MAMMALIA IN PARTICULAR. 


In the special study of the articulations, the same order will be followed 
as for the bones; the articulations of the spine will be first noticed, then 
those of the head, thorax, and anterior and posterior limbs. ; 
Preparation —The preparation of the bones which have been described 
has not been made the subject of any particular recommendation, because 
it suffices, in order to study them, to remove the soft parts by which they 


130 THE ARTICULATIONS. 


are surrounded either by boiling, maceration, or scraping. But when we 
come to examine the soft textures, in order to do so profitably it is necessary 
to learn beforehand the rules which should be followed in their preparation, 
The following are laid down with regard to the study of the articulations : 


1. To prepare the articulations, young subjects are chosen in preference to those ad- 
vanced in years, because the density of the cellular tissue in them is not so great, and this 
tissue is easily removed from around the ligaments. As these are prepared with difficulty 
when the external surface is in a dry state, care should be taken before dissecting them 
to have them excluded from the air by covering them with damp cloths, or with the 
skin of the animal. . ; 

2. It is convenient to separate the articulation we wish to dissect by sawing through 
the bones at a certain distance from the articular surfaces. ‘The manipulation of the 
part is then rendered easier, and its dissection can be made under the most favourable 
conditions. 

3. It is necessary to preserve as carefully as possible the muscles surrounding the 
articulations, in order to be able to study their relations with the ligaments which bind 
these. If it be absolutely necessary to remove them, their insertions corresponding to 
the articulation should always be retained. 

4, The capsular ligaments should be the first studied, as these have soon to be 
removed the better to show the funicular ligaments. These, in their turn, must be 
sacrificed in order to display, by different sections, the interosseous cords, when these exist. 
Lastly, the two articular surfaces should be completely separated, so as to examine 
their conformation. 

5. The synovial membranes, with their different culs-de-sac, being a very important 
study, with reference to the diagnosis and treatment of articular tumours, it is convenient 
to devote a special piece to the examination of these serous membranes. It is very 
useful to inject their interior with plaster or tallow coloured black, in order to distend 
their cavities, and thus aid the study of their relations with ligaments, tendons, or 
muscles. 

For the preparation of each articulation it is not necessary to give any directions; 
a glance at the figures accompanying the description will suffice to dispel any embarass- 
ment the student may experience, while he always requires particular indications. 

(Notwithstanding the above remarks with regard to the preparation of the ligaments, 
I have thought it advisable to follow the example given in the last edition of ‘Leyh’s 
Anatomy’ by Zundel, and briefly indicate the readiest method of demonstrating these 
organs, for the special benefit of the student.) 


ArticLe J.—ARTICULATIONS OF THE SPINE. 


(Preparation.—Remove all the soft parts surrounding the vertebral column, taking 
care not to injure the inferior longitudinal ligament in cutting away the pillars of the 
diaphragra and the psoas muscles; nor the ligaments uniting the articular processes to each 
other and the transverse processes of the dorsal vertebrx to the ribs, in removing the 
supercostal and transverse spinal muscles. To expose the common superior longitudinal 
ligament, separate the bodies of the vertebre frum their annular portions by the saw or 
chisel, and remove the spinal cord and dura mater; in doing this the inferior face of the 
interannular ligaments will be also removed. Examine an intervertebral fibro-cartilage 
by two sections—a transverse at an equal distance from the two vertebra, and a longi- 
tudinal through the middle line of the bodies.) 


These articulations are intrinsic and extrinsic. The first comprises all 
the articulations of the vertebra with each other; the second those of the 
spine with the head, the ribs, and the coxa. 


Intervertebral Articulations. 


The vertebra correspond: 1, By their bodies; 2, By their spinal or 
annular portion. There results from this union two kinds of articulation, 
which must be studied separately, as they do not belong to the same 
class. It is well to mention, however, that the general details into which 
this study leads us apply only to the articulations uniting the last six 


ARTICULATIONS OF THE SPINE. 131 


cervical vertebra, all the dorsal and lumbar vertebre, and the first sacral 
vertebra, 


; Union or THE Vertzpr” By Tuer Bopres.—The articulations forming this 
union are so many amphiarthroses. 

Articular surfaces.—The vertebral bodies come into contact by the 
surfaces which terminate them before and behind. In the cervical region 
these surfaces represent, anteriorly, a veritable head, posteriorly, a cotyloid 
cavity which receives the head of the next vertcbra. Beginning from the 
first dorsal vertebra and passing on to the sacrum, these tend to become 
pac iia weir nee and more plane, though they still preserve their convexity 
and concavity. 

Modes of wnion.—1, By fibro-cartilages interposed between the articular 
surfaces; 2, By a common superior vertebral ligament; 3, By a common 
inferior vertebral ligament. 

a. Intervertebral fibro-cartilages (Fig. 80, 1, 1).—These are circular or 
elliptical discs, convex in front, concave behind, and solidly fixed by their 
faces to the articular planes which they separate. The fibro-cartilaginous 
substance composing them consists of concentric layers, which become denser 
and closer to each other as they near the circumference; they even disappear 
towards the centre of the disc, where this substance becomes pulpy and 
assumes the histological characters of pure cartilage. It may be remarked, 
that each of these layers is made up of a collection of thick parallel filaments, 
which cross with those of other layers like an X, and are attached by their 
extremities to the articular surfaces. From this arrangement results so inti- 
mate an adherence between the vertebral bodies and their intermediate fibro- 
cartilages, that an attempt to disunite them is more likely to determine a 
fracture of the former. The fibro-cartilages, thicker in the cervical and 
lumbar regions than in the dorsal, respond by their circumference to the 
two common ligaments. Those which separate the vertebre of the back 
concur to form the intervertebral cavities, » hich are destincd for the reception 
of the heads of the ribs, and give attachment to the interosseous costo- 
vertebral ligaments. 

(Leyh ieee the superficial fibres of the excentric layer of these 
fibro-cartilages as intervertebral ligaments. Luschka has shown that the 
‘cartilages are in reality articular capsules.) 2 a 

b. Common superior vertebral ligament (Fig 838, 1).—This ligament 
extends from the axis to the sacrum, and is lodged in the spinal canal ; it 
represents a long fibrous band cut on its borders into wide festoons. (The 
wide portions correspond to the discs.) ; ; 

By its inferior face, it is attached to the intervertebral discs and the 
triangular imprints on the upper faces of the bodies of the vertebra. Its 
superior face is in contact with the dura mater through the medium of an 
abundant cellulo-adipose tissue. Its borders are margined by the intra- 
vertebral venous sinuses (venee basium vertebrarium). ; 

c. Common inferior vertebral ligament (Fig. 84, 5).—Situated under the spine, 
this ligament is absent in the cervical and the anterior third of thedorsal region. 
It only really begins about the sixth or eighth vertebra of the latter region, 
and is prolonged in the form of a cord, at first narrow, then gradually 
widening until it reaches the sacrum, on the inferior surface of which it 
terminates by @ decreasing expansion, From its commencement, it 18 
attached to the inferior crest of the bodies of the vertebree and the interver- 
tebral discs. By its inferior face, it responds to the posterior aorta. 

(Leyh commences this ligament at the seventh cervical vertebra, and says 


132 THE ARTICULATIONS. 


that it adheres to the crests on the bodies of the dorsal and lumbar vertebra, 
as well as to the lower face of the sacrum and coccyx. At the fifth dorsal 
vertebra it widens and thickens, and in the lumbar region is bound up with 
the pillars of the diaphragm and confounded on each side with the large 
ligaments of the pelvis.) 

Unron or THe Vertesra sy THEIR Sprvaz Porrions.—Each vertebra, 
in uniting by its annular portion with that which follows or precedes it, 
forms a double arthrodial joint. : ; 

Articular surfaces. —These are the facets cut on the anterior or posterior 
articular processes, and which have been described when speaking of tlie 
vertebre themselves. They are covered by a thin layer of cartilage. 

Modes of wnion.—1, A common superspinous ligament; 2, Interspinous 
ligaments; 3, Interlamellar ligaments ; 4, Ligamentous capsules, proper 
to the articular processes, ae 

a. Common superspinous ligament.—This ligament, whose name suf- 
ficiently indicates its situation, extends from the sacrum to the occipital bone 
and is divided into two portions : one posterior, or superspinous dorso-lumbar 
ligament; the other anterior, or superspinous cervical ligament. These two 
ligaments, although continuous with one another, yet differ so strikingly 
in form and structure that they are best described separately. 

1. Superdorso-lumbar ligament (Fig. 80, 2).—This is a cord of white 
fibrous tissue, which commences behind on the sacral spine and ceases in 
front about the inferior third of the dorsal region by insensibly assuming 
the texture and elasticity of the cervical ligament, with which it is continuous, 
It is attached in its course to the summits of all the lumbar spinous processes 
and to the ten or twelve last dorsal. On the sacral spine, it is confounded 
with the superior ilio-sacral ligaments, In the lumbar region, it is united 
on each side to the aponeuroses of the common mass of muscles. 

2. Superspinous cervical, or simply cervical ligament (Fig. 104, 1, 2).— 
This ligament is entirely formed of yellow fibrous tissue, and constitutes, 
in the median plane of the body, a very remarkable elastic apparatus which 
separates the superior cervical muscles of the right side from those of the 
left, and plays the part not entirely of an articular band, but rather of a 
permanent stay charged to balance the weight of the head. 

In the cervical ligament there is distinguished a funicular and a lameliar 
portion. The first, usually called the cord of the cervical ligament, is a 
wide funiculus which extends directly from the first dorsal spinous processes 
to the summit of the head. Divided into two lateral lips by a median groove, 
this cord is continued posteriorly with the dorso-lumbar ligament, and is 
inserted forwards into the cervical tuberosity of the occipital bone. It is 
covered above by a mass of fibro-adipose tissue which, in certain common- 
bred horses, is very abundant. Below, it gives rise, in its posterior two- 
thirds, to the majority of the fibres belonging to the lamellar portion. .On 
the sides, it receives the insertions of several cervical muscles. The lamellar 
portion, comprised between the funicular portion, the spinous processes of the 
second dorsal vertebra, and the cervical stalk, constitutes a vast triangular 
and vertical septum, which itself results from the apposition of the two 
lamine which lie back to back, and are united by cellular tissue; they are 
bordered above by the two lateral lips of the cord. The elastic fibres which 
enter into their composition are given off either from the latter, or from the 
spinous processes of the second and third dorsal vertebra ; they are directed 
downwards or forwards, and reach the spinous processes of the last six 
cervical vertebre, into which they are inserted by so many digitations, 


ARTICULATIONS OF THE SPINE. 133 


becoming confounded with the interspinous ligaments of the neck. The 
fibres of the two last digitations are few in number, widely separated from 
one another, and united by many anastomosing branches, which make them 
appear as a kind of wide network. The lamine of the cervical ligament are 
in relation, outwardly, with the superior branch of the ilio-spinal ligament 
the transverse spinous muscle of the neck, and the great complexus. : 

(This important structure, which is in reality the mechanical stay and 
support of the heavy head and neck of quadrupeds, and is usually termed the 
ligamentum nuche, is all but absent in Man, being represented in him by a thin 
narrow band, or rather two thin planes of fibres, the ligamenta subflava. It is 
described by Leyh as if there were not two portions, and that excellent 
anatomist does not appear to insist sufficiently on the difference between the 
dorso-nuchal and the dorso-lumbar divisions. Percivall, who almost entirely 
neglects the ligaments, also makes no distinction. The difference in structure, 
elasticity, and situation, warrants the distinction made by Chauveau. As 
already indicated, the function of this ligament, and more particularly of its 
nuchal division, is to maintain the head and neck in their natural position 
during repose, and to allow the most extensive movements at other 
times. ) ; 

b. Interspinous ligaments (Fig. 80, 3).—Fibrous lamine fill the inter- 
spinous spaces, and are attached, before and behind, to the opposite borders 
of the spimous processes which they unite; they 
are continued below by the interlamellar liga- 
ments, forming two lateral planes which are 
applied against each other, like the lamine of the 
cervical ligament, and covered outwardly by the 
transverse spinous (dorsalis colli) muscle. 

In the region of the neck, the interspinous 
ligaments ave yellow and elastic. In the dorso- 
lumbar region, they are formed by fasciculi of 
white fibrous tissue, loosely united to each other 
at their extremities, and directed very obliquely 
backwards and downwards. In consequence of 
this disposition, and notwithstanding their in- 
extensibility, they permit the separation of the iyreRyERTEDRAL ARTICULA- 
spinous processes. Their lateral surfaces are TIONS. 
divided by a layer of grey elastic fibres, which a, , c, Bodies of three dorsal 
cross like an X the direction of the preceding vertebra divided longitudi- 
fasciculi. Very abundant in the anterior moiety nally and vertically to show 

vos : (1, 1) a section of the in- 
of the dorsal region, these fibres operate, by their —tgtvertebral discs; 2, Super- 
proper elasticity, in bringing the spinous pro- spinous dorso-lumbar liga- 
cesses towards each other. ment; 3, Interspinous liga- 

c. Interlamellar, or interannular ligaments— ments 4, Ce pnea SCOT 
Situated, as their name indicates, between the ae cayenls 

: coms é processes 
vertebral laminew, and divided into two lateral in the dorsal region. 
moieties, these ligaments appear to be produced 
by the two fibrous planes of the preceding ligaments, which, on arriving 
at'the base of the spinous processes, separate from one another to be carried 
outwards. Their anterior border is inserted into the posterior margin of the 
vertebral lamina in front. Their posterior border is fixed to the anterior 
border and inferior face of the lamina behind. Their superior face is in 
relation with some spinal muscles, and their inferior face is in contact with 
the dura mater. Outwardly, they are confounded with the capsules proper 


12 


134 THE ARTICULATIONS. 


to the articular processes. Yellow and elastic in the cervical region, these 
ligaments are white and inelastic in the dorso-lumbar region. ; 

d. Capsules proper to the articular processes (Fig. 81, 5).—Each anterior 
articular process is maintained against the corresponding posterior process 
by a direct band: this is a peripheric capsule attached around the 
diarthrodial facets, doubled internally by a synovial membrane which 
facilitates their gliding, and covered, outwardly, by the insertions of some 
spinal muscles. These capsules, yellow and elastic in the cervical, are 
composed of white fibrous tissue in the dorso-lumbar region. Very developed 
at the neck, in consequence of the thickness of the articular tubercles they 
envelope, they become reduced, near the middle of the back, to sume fibres 
which cover, outwardly, the diarthrodial facets in contact. 

CHARACTERS PROPER TO SOME INTERVERTEBRAL ARTICULATIONS.—1. Inter- 
coccygeal and sacro-coccygeal articulations.—These are constructed after the 
same type as the other spinal articulations, except that they are appropriate to 
the rudimentary state of the vertebre they unite. The coccygeal bones only 
come in contact by their bodies, their spinal lamine being reduced to the 
merest traces, or are altogether absent. The anterior and posterior articular 
surfaces of each vertebra are convex, and the interarticular fibro-cartilages, 
hollow on both faces, resemble a biconcave lense. With regard to the 
peripheral bands, they are represented by a bundle of longitudinal fibres 
spread over the surface of the bones, which they envelope in a common sheath. 

2. Intersacral articulations—The sacral vertebre being fused into one 
piece—the os sacrum—there is no occasion to study the true articulations in 
this region. It may be remarked, however, that the superspinous dorso- 
lumbar ligament is continued on the sacral spine, and that there exist be- 
tween the processes formed by this spine veritable interspinous ligaments. 

3. Sacro-lumbar articulation.—In this articulation, the great thickness of 
the fibro-cartilage is to be remarked; and, in addition, that the last lumbar 
vertebra corresponds with the sacrum not only by its body and articular 
processes, but also by the oval and slightly concave facets shown on the 
posterior border of its transverse processes, which are adapted to analogous 
slightly-convex facets on the sides of the base of the sacrum. The 
bundles of fibres thrown from one bone to another from around these sacro- 
transversals (real planiform diarthroses) maintain the articular surfaces in 
contact, and cover, outwardly, the synovial membrane which facilitates their 
gliding. 

4. Articulation of the two last lumbar vertebree.—This is distinguished by 
the presence, between the transverse processes, of a planiform diarthrosis 
like that of the sacro-transversal just noticed. These two articulations are 
only found in Solipeds. 

5. Atlo-axoid articulation.—This is so far removed by its conformation 
and special uses from the other intervertebral articulations, that it will be 
described as an extrinsic articulation of the head and spine. (See the 
Articulations of the Head.) 

Tux Movements or tHE SPINE IN GENERAL.—Each intervertebral articula- 
tion is the seat of very obscure movements, whose separate study offers little 
interest. But these movements, when conjoined with those of the other 
articulations, result in bending the whole spinal stalk in a somewhat 
marked manner, and producing either the flexion, extension, or lateral 
inclination of this flexuons column. 

; When flexion takes place, the spine is arched upwards, the common 
inferior ligament is relaxed, the spinous processes separate from one 


ARTICULATIONS OF THE HEAD. 135 


another, and the superspinous ligament, becoming very tense, soon imposes 
limits to this movement, 


Extension is effected by an inverse mechanism, and is checked by the 


tension of the common inferior ligament and the meeting of the spinous 
processes, 


Lateral inclination takes place when the spine bends to one side. This 
movement is very easily executed in the cervical and coceygeal regions, but 


is arrested by the ribs and the costiform processes in the dorso-lumbar 
region. 


A circumflex movement is possible at the two extremities of the vertebral 


column—neck and tail; for they pass easily from extension to lateral 
inclination, and from this to flexion, etc. 


_ Owing to the elasticity of the intervertebral fibro-cartilages, the spine 
is endowed with a very limited amount of rotation, or rather of torsion. 
For the special study of the movements of each spinal region, reference 


must be made to what has been already said (page 29) regarding the 
mobility of this column. 


In the Oz the intervertebral dises are much thicker than in the Horse. The common 
inferior vertebral ligament is very strong in the lumbar region. The superspinous 
dorso-lumbar ligament is composed of yellow elastic tissue. The cervical ligament 
is much more developed than in Solipeds, in consequence of the greater weight of 
the head ; and it presents a conformation altogether special, which M. Lecoq has made 
known in the following terms: “On leaving the withers, the superspinous ligament 
ceases to cover the head of the spinous processes, and extends from each side in a wide 
and strong band, taking points of attachment on the sides of the processes, and becoming 
separated, on leaving that of the first dorsal vertebra, into two parts—a superior and 
inferior. The first reaches the cervical tuberosity in the form of a thick cord united to 
the cord of the opposite; the other thins off into a band which is attached to the posterior 
half of the spinous process of the axis and to that of the third and fourth vertebre. A 
production of the same nature, an auxiliary to the principal portion, leaves the anterior 
border of the spinous process of the first dorsal vertebra, and is attached to that of the 
fourth, fifth, sixth, and seventh vertebra. The superior border of this auxiliary liga- 
mentous production is concealed between the two lamina of the principal ligament.”? 

The Pig, remarkable for the shortness of its neck and the limited movements of this 
region, does not show any cervical ligament, properly so called. It is replaced by a 
superficial fibrous raphé extending from the occipital bone to the spinous process of the 
first dorsal vertebra. peer . 

The Cat has no cervical ligament, and shows, instead, a raphé like the Pig. In 
the Dog the ligament is reduced to a simple cord, continued from the dorso-lumbar 
ligament, and which goes no further than behind the spinous process of the axis, In 
the Cat the interspinous ligaments are replaced by small muscular fasciculi; with the 
Dog this substitution only takes place in the cervical region. The lamine of the first 
coccygeal vertebrze possess the principal characters which distinguish perfect pee 
and are united by vestiges of the articular bands which exist in the other regions o 


the spine. 


Arriete Il.—AnrticuLations of THE Heap. 


We will first study the two extrinsic articulations which, are the centre 
of the movements of the head on the spine—the atlo-axoid and oecipito-atloid 
articulations. Afterwards, we will pass to the examination of the joints which 
unite the different bones of the head. 


1. Atlo-axoid Articulation. 


uffices to remove the soft parts from around the articulation to 


ion.—lt 8 ‘ ace : 
( Peeparaizon: the interspinous, and the inferior odontoid ligament. To examine 


expose the interannular, 


‘ Journal de Médecine Vétérinaire’ (Lyons, 1848), p. 122, 


136 THE ARTICULATIONS. 


the superior odontoid ligament and the synovial membrane, one half the atlas and axis 
must be separated by sawing longitudinally through them from one side to the other.) 


This may be considered as the type of the trochoides. ; 

Articular surfaces —To form this articulation, the axis offers its odontoid 
pivot and the undulated diarthrodial facets at its base. The atlas opposes 
to the pivot the concave semicylindrical surface hollowed on the superior 
face of its body; and for the lateral undulated facets it has analogous facets 
which are cut on the transverse processes, on each side of the vertebral canal. 

Mode of wnion.—1. An odontoid, or odonto-atloid ligament; 2. An 
inferior atlo-axcid ligament; 3. A superior ditto; 4. A fibrous capsule. 

a. Odontoid ligament (Fig. 81, 3).—Continued to the common superior 
vertebral ligament, very short and strong, flattened from above to below, 
and triangular in shape, the odontoid ligament is composed of glistening 
white fibres, fixed behind in the superior channel of the odontoid process, 
and inserted in front on the transverse ridge which separates the superior 
face from the inferior arch of the atlas, as well as on the imprints situated 
in front of this ridge. This ligament is covered, on its lower face, by the 
synovial membrane of the articulation; and by its upper surface is in 
contact with the spinal dura mater. It sends some bands within the 
condyles of the occipital bone. 

b. Inferior atlo-axoid ligament.—This is a wide, thin, and nacrous- 
looking band, extending from the inferior face of the axis to the inferior 
tubercle of the atlas, and covered by the long muscle of the neck; it is 
united to the synovial membrane by its deep face, and confounded on its 
borders with the fibrous capsule to be immediately described. 

c. Superior atlo-axoid ligament.—This exactly represents the inter- 
spinous ligaments of the other cervical articulations. Yellow, elastic, and 
formed like the two lateral bands, it is continuous, laterally, with the 
capsular ligament. 

d. Capsular ligament.—This, it may be said, is only the interlamellar 
ligament proper to the atlo-axoid articulation. It commences from the 
sides of the preceding ligament, and becomes united to the inferior atlo- 
axoid one, after contracting adhesions with the borders of the odontoid 
ligament. In this way it encloses the articulation and the spinal canal. 
Before and behind, it is attached to the anterior or posterior margin of 
the bones it unites, Its external face is in contact with the great oblique 
muscle of the head; its internal responds, in its inferior half, to the articular 
synovial membrane, and its superior moiety to the spinal dura mater. 
(Leyh describes this ligament as the interannular. 

Synovial membrane.—This lines the odontoid ligament, the atlo-axoid 
ligament, and the articular portion of the peripheral capsule. 

Movements.—Rotation, the only movement possible in the atlo-axoid 
articulation, is effected in the following manner: the axis remains fixed, 
and the first vertebra, drawn to one side chiefly by the great oblique 
muscle, rotates on the odontoid pivot, carrying the head with it. 


Tn the Dog and Cat the odontoid ligament is replaced by three particular ligaments : 
1 Two lateral cords, rising in common from the summit of the odontoid process, and 
inserted, each on its own side, within the condyles of the occipital bone; 2, A transverse 
ligament, passing over the odontoid process, which it maintains in its place against the 
inferior arch of the atlas, and is attached by its extremities to the superior face of the 
latter. A small synovial capsule facilitates the gliding of the odontoid process beneath 
this ligament. The articular synovial membrane always communicates with that of the 
Occipito-atloid articulation. 

In the P’g the disposition is nearly the same as in the Carnivora 


ARTICULATIONS OF THE HEAD. 


2. Occipito-atloid Articulation. 


137 


(Preparatton.—Dissect away all the soft parts that pass from the neck to the head 


and cover the articulation, and more particularly the flexor, 
the recti, and the small oblique muscles of the head. To 
expose the synovial membranes, open the sides of the capsular 
- ligament.) 


This is a condyloid articulation. 

Articular surfaces.—In the atlas, the two cavities 
which replace the anterior articular processes and 
the heads of the other vertebrae; in the occipital 
bone, the two condyles flanking the sides of the occi- 
pital foramen. 

Mode of union.—A single capsular ligament en- 
velopes the entire articulation ; it is attached by its 
anterior border to the margin of the occipital con- 
dyles, and by its posterior to the anterior contour of the 
atlas. Thin and slightly elastic in its inferior half, 
this ligament presents, superiorly, four reinforcing 
fasciculi: two middle, which intercross in X—from 
whence the name “ cruciform,” sometimes given to this 
ligament (Fig. 81, 1, 1); and two lateral, which pass 
from the sides of the atlas to the base of the styloid 
processes (Fig. 81, 2, 2). It is lined within by the 
synovial membranes, and is enveloped externally by a 
large number of muscles, which protect the articu- 
lation and greatly strengthen iteverywhere. Among 
these may be particularly noticed the straight muscles 
of the head, the small oblique, and the great com- 
plexus. There is also the cord of the cervical liga- 
ment. 

Synovial membranes.—These membranes are two 
in number, one for each condyle and corresponding 
atloid cavity. Sustained above, below, and outwardly 
‘by the capsular ligament, they are related inwardly 
to the dura mater and tothe fibrous tractus which, 
from the odontoid ligament, is carried to the in- 
ternal face of the occipital condyles. 

Movements.—Extension, flexion, lateral inclination, 
and circumduction, are the possible movements of the 
occipito-atloid articulation. 

In the Pig, Dog, and Cat this articulation, strengthened 


as it is by the capsular and odontoido-occipital ligaments 
already mentioned, has only one synovial capsule. 


3. Articulations of the Bones of the Head. 


If we except the articulation which unites the 
inferior jaw to the cranium—the temporo-maxillary— 
and the hyoideal articulations, it will be found that 
all the bones of the cranium and face are united to 
each other by synarthrosis, forming the different 
kinds of sutures already generally described (page 128). 
Nothing is to be gained by entering into more detail 


ATLO-OXOID AND OCCIPI- 
TO-ATLOID ARTICULA- 
Trons. The upper arch 
of the atlas has been 
removed to show the 
odontoid ligament. 

1, 1, Middle accessory fas- 
ciculi; 2, 2, Lateral 
fasciculi of the capsular 
ligament of the occipito- 
atloid articulation; 3, 
Odontoid ligament; 4, 
Interspinous ligament 
uniting the second and 
third vertebra of the 
neck ; 5, Fibrous capsule 
uniting the articular 
processes of these verte- 
bra.—a, Anterior in- 
ternal foramen of the 
atlas converted into a 
groove by the section of 
the bone; B, 3, Verte- 
bral foramina of the 
atlas; c, ¢c, Foramina 
replacing the anterior 
notches of the axis. 


138 THE ARTICULATIONS. 


with regard to these articulations, as it will be found sufficient to call to mind 
the topographical description of each piece entering into their formation. 


4. Temporo-masillary Articulation. 
(Preparation.—Remove the masseter muscle and the parotid gland. Saw through the 


head about the middle line. Open the articulation externally to exhibit the inter- 
articular meniscus.) 


The lower jaw, in its union with the cranium, constitutes a double 
condyloid articulation. 

Articular surfaces.—With the temporal bone, these are the condyle, the 
glenoid cavity, and the supracondyloid process which exists at the base of 
the zygomatic process. The glenoid cavity is not lined by cartilage, and 
appears to be merely covered by synovial membrane. With the maxillary 
bone there is the oblong condyle situated in front of the coronoid process. 

Interarticular fibro-cartilage.—The articular surfaces just named are 
far from fitting each other accurately; this is 
only accomplished by the interposition of a 
fibro-cartilaginous disc between the temporal 
and maxillary bones. This disc isa kind of 
irregular plate, flattened above and_ below, 
thicker before than behind, and moulded on 
each of the diarthrodial surfaces it separates. 
Its superior face, therefore, presents: in front, 
a cavity to receive the condyle of the temporal 
bone; behind, a boss which is lodged in the 
glenoid cavity. The inferior face is hollowed 
by an oblong fossa in which the maxillary con- 
dyle is lodged. 

Mode of union.—A fibrous envelope—a true 

; capsular ligament—surrounds the articulation, 
pec i conte a is stiabhed by its borders to the margin of 
1, Interarticular fibro-cartilage; the articular surfaces it unites. Formed, out- 
2, External fasciculus of the wardly, by a thick fasciculus of white vertical 
capsular ligament.—a, Base of fibres (Fig. 82, 2), this ligament becomes grey- 
we ce cule He ish-coloured and elastic for the remainder of 
Mastoid process; p, External its extent, and greatly diminishes in thickness, 
auditory hiatus. especially in front. Its inner face is lined by 
the synovial capsules, and adheres to the cir- 
cumference of the interarticular fibro-cartilage. Its external face responds, 
in front, to the temporal and masseter muscles; behind, to the parotid 
gland; inwardly, to the external pterygoid muscle; and outwardly, to a 
fibrous expansion which separates it from the skin. (Leyh mentions a 
lateral external and a posterior ligament for this articulation, but Chauveau 
and Rigot evidently look upon these as portions of the capsular.) 

Synovial membranes. —This articulation has two synovial sacs, one above 
the other, which are separated by the fibro-cartilaginous disc. 

Afovements.—The temporo-maxillary articulation is the centre of all the 
movements performed by the lower jaw. These are: depression, elevation, 
lateral motion, and horizontal gliding. 

The lower jaw is depressed when it separates from the superior one, and 
is elevated when it approaches this. These two opposite movements are 
executed by a mechanism of such great simplicity that it need not be 


Fig. 82. 


ARTICULATIONS OF THE HEAD. 139 


described here. Lateral movements take place when the inferior extremity of 
the jaw is carried alternately to the right and left. It then happens that 
one of the maxillary condyles, taking with it the fibro-cartilage, is brought 
into contact with the temporal condyle, while the other is imbedded in the 
glenoid cavity of the opposite side. The horizontal gliding is effected from 
behind to before, or vice versd. In the first case, the two maxillary condyles 
are carried at the same time under the temporal condyles, bearing with 
them the fibro-cartilages. In the second case, they are drawn into the 
glenoid cavities, and rest against the supracondyloid eminence, which 
prevents their going further. It will be understood, after this brief 
description, that the presence of the fibro-cartilages singularly favours the 
lateral movements and horizontal gliding of the lower jaw. 


In the Pig the temporo-maxillary articulation is formed after the same type as that 
of rodents, and allows very extensive movements from before to behind; a circumstance 
due to the complete absence of the supracondyloid eminence. 

In the Dog and Cat the maxillary condyle is exactly fitted into the temporal cavity. 
This disposition, in giving great precision to the movements of depression and elevation, 
restrains in a singular manner the lateral and horizontal gliding motions. The inter- 
articular fibro-cartilage is extremely thin in these animals. 


5. Hyoideal Articulations. 


(Preparation.—Disarticulate the lower jaw, and dissect away from the right of each 
articulation the muscles that may conceal the view.) 


These are of two kinds: eatrinsic and intrinsic. The first comprise the 
two temporohyoideal articulations ; to the second belong the joints which 
unite the different pieces of the hyoid bone—the interhyoideal articulations. 

Tremporo-HyorpEaL ARTICULATIONS.—These are two amphiarthrodial 
joints, in the formation of which cach great branch of the hyoid bone 
opposes its upper extremity to the hyoideal prolongation lodged in the 
vaginal sheath of the temporal bone. An elastic cartilage, from 4-10ths to 
6-10ths of an inch in length, unites the two bones in a solid manner; and 
it is owing to the flexibility of this cartilage that the hyoid bone can move 
entirely on the temporal bones. 

InreruyorweaL ArticuLations.—A. The great branch articulates with 
the small one by an amphiarthrosis analogous to the preceding. To form 
this articulation, these two pieces of bone are joined at an acute angle 
through the medium of a more or less thick cartilaginous band, in the 
centre of which there is often a little bony nucleus. This cartilage is elastic 
and flexible, and permits the opening and closing of the articular angle at 
the summit of which it is placed. 

B. Each small branch is united to the body of the hyoid bone by an 
arthrodial articulation. The articular surfaces are: for the hyoideal branch, 
the small cavity terminating its inferior extremity; for the body, the 
rounded lateral facet situated at the origin of the cornu. These surfaces 
are covered by cartilage, and enveloped by a small synovial sac and a 
peripheral fibrous capsule. They can glide on each other in nearly every 
direction, (Median and superior hyoideal capsular ligaments are described 
by Leyh as sometimes present. The latter unites the upper and middle 
branches, and the former the middle with the inferior branches. They are 
absent when these branches are confounded with the superior ones.) 


140 THE ARTICULATIONS. 


Articte IIJ.—AnrticuLaTions oF THE THORAX. 


These are also divided into extrinsic and intrinsic. The first, named 
costo-vertebral, unite the ribs to the spine. The second join the different 
pieces of the thorax together; they comprise: 1, ‘I'he chondro-sternal 
articulations ; 2, Chondro-costal articulations; 3, The articulations of the 
costal cartilages with each other; 4, The sternal articulation peculiar to 
the larger Ruminants and the Pig. All these joints will be first studied ina 
particular manner, then examined in a general way as to their movements. 


1. Articulations of the Ribs with the Vertebral Column, or Costo-vertebral 
Articulations. 


Each rib responds to the vertebral column by two points—its head and 
its tuberosity. The first is received into one of the intervertebral cavities 
hollowed out on the sides of the spine, and is therefore in contact with two 
dorsal vertebre; the second rests against the transverse process of the 
posterior vertebra. From this arrangement arises two particular articulations 
belonging to the arthrodial class, which are named costo-vertebral and costo- 
transverse. = 

CosT0-VERTEBRAL ARTICULATIONS.—Articular surfaces.— Pertaining to 
the rib, we have the two convex facets of the head, separated from each 
other by a groove of insertion and covered by a thin layer of cartilage. 
On the vertebra, the concave facets which by their union form the inter- 
vertebral cavity; these facets are also covered with cartilage, and separated, 
at the bottom of the cavity by the corresponding intervertebral disc. 

Mode of union.—1. An interarticular ligament (Figs. 83, 2; 84, 1), im- 
planted in the groove of insertion of the head of the rib, and attached to 


Fig. 83. 


ARTICULATIONS OF THE RIBS WITH THE VER- ARTICULATIONS OF THE RIBS WITH THE VER- 


TEBR.Z, AND OF THESE WITH EACH OTHER TEBR.Z, AND OF THESE WITH EACH OTHER 
(UPPER PLANE). (INFER“OR PLANE). 

1, Spinal canal, upper face, showing the 1, Interarticular costo-vertebral ligament 3 
common superior ligament; 2, Interar- 2, 3, 4, Fasciculi of the stellate, or in- 
ticular costo-vertebral ligament; 3, Inter- ferior costo-vertebral ligament ; 5, Common 
osseous costo-transverse ligament; 4, Pos- inferior vertebral ligament. 


terior costo-transverse ligament. 


the superior border of the intervertebral disc, which it encircles upwards 
and inwards, to unite on the median line with the ligament of the opposite 
side. 2. An inferior peripherai ligament (Fig. 84, 2, 3, 4), flat above and 
below, thin and radiating (whence it is often named the stellate ligament), 
formed of three fasciculi which are fixed in common on the inferior face of 


ARTICULATIONS OF THE THORAX. 141 


the head of the rib, and in diverging are carried over the bodies of the two 
vertebree and the intervertebral disc. Lined above by the synovial mem- 
branes, this ligament is covered below by the pleura. (Leyh includes a 
capsular ligament for the head of the rib and another for the costal 
tuberosity. He probably viewed the synovial membrane of these articula- 
tions as such.) 

Synovial membranes.—Two in number, these are distinguished into 
anterior and posterior, lying against each other, and separated in part 
by the interarticular ligament they cover. Supported below by the stellate 
ligament, above they are directly in contact with the small supercostal 
muscles, and with vessels and nerves. 

CostTo-TRANSVERSE ARTICULATIONS.—Articular surfaces.—In the rib, the 
diarthrodial facet cut on the tuberosity. In the vertebra, the analogous 
facet on the outside of the transverse process. 

Mode of union.—T wo ligaments bind this articulation: 1, The posterior 
costo-transverse ligament (Fig. 83, 4), a white fibrous band attached by its 
extremities behind the tranverse process and the costal tuberosity, lined by 
synovial membrane, and covered by the transverse insertions of several 
spinal muscles; 2, The anterior costo-transverse, or interosseous ligament 
(Fig. 83, 3), a fasciculus of short, thick, white fibres, fixed on the anterior 
surface of the transverse process near its base, and in the rugged excavation 
on the neck of the rib. This ligament is invested, posteriorly, by the 
synovial membrane, and covered in front by pads of’ adipose tissue which 
separate it from the costo-vertebral articulation. 

Synovial membrane.—This is a small particula. capsule kept apart from 
the posterior synovial membrane of the costo-vertebral articulation by the 
costo-transverse interosseous ligament. 

CHARACTERS PECULIAR TO soME CosTO-VERTEBRAL ARTICULATIONS.— 
1. The first, and sometimes the second, costo-vertebral articulation has no 
interosseous ligament, and only exhibits one synovial membrane. The 
intervertebral cavity which concurs in forming the first is often excavated 
between the last cervical and first dorsal vertebrae. 

2. The two or three last costo-transverse articulations are confounded 
with the corresponding costo-vertebral joints. They have no proper serous 
membrane, but the posterior synovial membrane of the latter is prolonged 
around their articular surfaces. 


2. The Chondro-sternal or Costo-sternal Articulations. 


(Preparation—To show the articulation of the ribs with the cartilages, these with 
the sternum, and the cartilages with each other, carefully remove the pleura, the 
triangular muscle of the sternum, the diaphragm, the transverse muscle of the abdomen, 
then the pectorals, the great oblique, the transversalis of the ribs, and the intercostal 
muscles. ) 


The first eight ribs, in resting upon the sternum by the inferior extremity 
of their cartilages, form eight similar arthrodial articulations. 

Articular surfaces.—Each sternal cartilage opposes to one of the lateral 
cavities of the sternum the convex and oblong facet at its lower extremity. 

Mode of union.—The diarthrosis resulting from the union of these two 
surfaces is enveloped everywhere by bundles of white, radiating, fibrous 
tissue, which constitute a veritable ligamentous capsule. The superior part 
of this capsule, known as the stellate or superior costo-sternal ligament, is 
covered by the triangular (sterno-costalis internus) muscle; it is joined 
to a fibrous cord lying on the superior face of the sternum, and which 


142 THE ARTICULATIONS. 


is confounded in front with that of the opposite side. The inferior 
portion, the inferior stellate or costo-sternal ligament, is in relation with the 
pectoral muscles, ay . 

Synovial capsule.—There is one for each articulation. 

Characters proper to the first costo-sternal articulation—The first costo- 
sternal articulation is not separated from its fellow of the opposite side; so 
that these two joints are, in reality, only one, and the two cartilages lying 
close to each other correspond by a small diarthrodial facet, continuous with 
that for the sternum. The two sternal facets are inclined upwards, and 
confounded with one another. Only one synovial cavity exists for this 
complex articulation, which unites the two first ribs to each other and to the 
sternum. 


3. Chrondo-costal Articulations uniting the Ribs to their Cartilages. 


These are synarthrodial articulations whose movements are very obscure. 
They are formed by the implantation of the cartilages in the rugged cavities 
the ribs present at their inferior extremities. The solidity of these articu- 
lations is assured by the adherence of the fibro-cartilage to the proper 
substance of the ribs, and by the periosteum which, in passing from the 
bone to the cartilage, plays the part of a powerful peripheral band. 


In the Ox, the sternal ribs, in uniting with their cartilages, form a veritable 
ginglymoid diarthrosis, whose movement is facilitated by a small synovial capsule. 


4, Articulations of the Costal Cartilages with each other. 


The ribs, attached to each other by means of the intercostal muscles, are 
not united by real articulations; neither are their cartilages of prolongment. 
But the asternal cartilages are bound together by a small yellow elastic 
ligament, which is carried from the free extremity of each to the posterior 
border of the preceding cartilage; the anterior border of the first asternal 
cartilage is directly united to the posterior border of the last sternal cartilage, 
through the medium of the perichondrium and very short ligamentous bands. 
This same asternal cartilage is also bound to the inferior face of the xiphoid 
appendage by a small white ligament (the chondro-xiphoid), under which 
passes the anterior abdominal artery. 


5. Sternal Articulation peculiar to the Ox and Pig. 


It has been already shown that in these animals the anterior piece of the sternum is 
not consolidated with the second portion. The two are united by a diarthrodial 
articulation ; and for this purpose the anterior presents a concave surface, the posterior 
a convex one. Bundles of peripheral fibres firmly bind them to each other, and a special 
small synovial capsule facilitates their movements, which are very limited. 


6. The Articulations of the Thorax considered in a general manner in regard to 
Movements, 


The thorax can increase or diminish in diameter in an antero-posterior 
and a transverse direction; whence arises the dilatation and contraction 
of this cavity: the inspiratory movements accompanying the entrance of the 
external air into the lungs, and the expiratory movements expelling the air 
contained in these organs. 

The variations in the antero-posterior diameter of the chest being due to 
changes in the figure of the diaphragm, need not be noticed here. But the 
transverse variations being the result of the play of the costal arches on the 


ARTICULATIONS OF THE ANTERIOR LIMBS. 143 


spine and sternum, it is advantageous to study the mechanism which presides 
in the execution of their movements. 

The costal arches being inclined backwards on the middle plane, the 
space they inclose in their concavity is not nearly so extensive as if they 
had been perpendicular to this plane. Owing to their double arthrodial 
joints, the ribs are movable on the spine, and their inferior extremity, also 
movable, rests either directly or indirectly on the sternum. Therefore it is 
that, when they are drawn forward by their middle portions, they pivot on 
their extremities, and tend to assume a perpendicular direction, which is the 
most favourable for the largest increase of the space they limit; then there 
is enlargement of the lateral diameter of the thorax, which signifies dilatation 
of its cavity. The inverse movement, by an opposite mechanism, causes 
the contraction of the chest, 

The ribs are said to be elevated during the forward movement, and 
depressed when they fall backwards. These expressions, though perfectly 
applicable to Man, who stands in a vertical position, are not correct when 
employed in veterinary anatomy. 


Articte TV.—ArticuLations oF THE ANTERIOR Liss. 


1. Scapulo-humeral Articulation. 


(Preparation.—Detach the limb from the trunk. Remove from the upper extremity 
those muscles which are inserted in the vicinity of the glenoid cavity of the scapula; 
turn down from its lower extremity those which are inserted into the superior end of 
the humerus or a little below, preserving the attachments of their tendons with the 
capsular ligament. The thin scapulo-humeralis muscle may be allowed to remain in 
order to show its relations.) 


\ 

To constitute this enarthrodial articulation, the scapula is united to the 
humerus, and forms an obtuse angle which is open behind. 

Articular surfaces.—In the scapula there is the glenoid cavity, the 
shallow, oval fossa, elongated in an antero-posterior direction, notched in- 
wardly, and excavated at its centre or near the internal notch by a small synovial 
fossette. A ligamentous band, attached to the brim of the cavity, fills up 
this notch, and is the vestige of the glenoid ligament of man. In the 
humerus, the articular head, fixed between the large and small tuberosities, 
is often excavated by a shallow synovial fossette. 

Mode of union.—One capsular ligament (Fig. 85, 1), a kind of sac having 
two openings: one inferior, embracing the head of the humerus; the 
superior, inserted into the margin of the glenoid cavity. This capsule pre- 
sents in front two supporting fasciculi, which diverge as they descend from 
the coracoid process to the great and small tuberosities. The aponeurotic 
expansion thus formed is very thin and loose, so as to allow the two bones to 
separate to the extent of from +4, to 8, of an inch; but it is far from 
being sufficiently strong to bind them firmly together. The articulation is, 
therefore, consolidated by the powerful muscles which surround it, among 
which may be noticed: 1, In front, the coraco-radial (flexor brachii), 
separated from the fibrous capsule by an adipose cushion; 2, Behind, the 
large extensor of the fore-arm and thin scapulo-humeral (teres minor) 
muscles, whose office appears to be to pull up this capsule during the move- 
ments of flexion, so as to prevent its being pinched between the articular 
surfaces; 8, Outwards, the short abductor of the arm and the subspinous 
(postea spinatus) tendon; 4, Inwards, the wide and strong tendon of the 
subscapular muscle. In addition to these powerful retaining apparatus, 


144 THE ARTICULATIONS. 


there ig the atmospheric pressure, whose influence is of a certain impor- 
tance. This may be proved by removing all the surrounding muscles, when 
it will be found that the capsule is not relaxed, nor are the articular surfaces 
separated ; to effect this, it is necessary to make an opening in the capsule, 
so as to allow the air to enter its cavity, when the surfaces immediately 
separate. : 

Synovial capsule.—This is very loose, and entirely enveloped by the 
peripheral capsule, whose internal surface it lines. 

Movements. —Like all the enarthrodial articulations, the scapulo-humeral 
permits extension, flexion, abduction, adduction, circumduction, and rotation, 
These various movements, however, are far from being so extensive as in 
Man, the arm in the domesticated animals not being detached from the 
trunk, but being, on the contrary, fixed with the shoulder against the lateral 
parietes of the thorax. Flexion and extension are the least limited and the 
most frequently repeated movements; their execution always demands a 
displacement of the two bones, which are almost equally movable. In flexion, 
the scapulo-humeral angle is closed, not only because the inferior extremity 
of the humerus is carried backwards and upwards, but also because the 
scapula pivots on its superior attachments in such a manner as to throw its 
glenoid angle forward and upward. tension is produced by an inverse 
mechanism. During the execution of the other movements, the scapula 
remains fixed, and the humerus alone is displaced, bringing with it the 
inferior rays of the limbs. If it is carried outwards, we have abduction, 
or inwards, adduction ; if the member passes successively from flexion to 
abduction, and from that to extension, etc., in describing a circle by its 
lower extremity, then there is circumduction; if it pivots from left to right, 
or right to left, we have rotation. 


In the Pig, Dog, and Cat, the synovial membrane is not exactly inclosed by the 
fibrous capsule, but forms in front a ewl-de-sac, which descends in the bicipital groove to 
favour the gliding of the coraco-radial tendon. 

In Man, the scapulo-humeral articulation is disposed as in animals, but it is also 
protected above by the coraco-acromion roof. For the reasons noted above, this 
articulation allows of more extensive motion than in animals. As remarked by 
Cruveilhier, of all the joints in the human body, the scapulo-humeral is that which has 
the most extensive motion; in movements furward and outward, the humerus can 
become horizontal; in those of circumduction it describes a complete cone, which is 
more extensive in front and laterally than behind and inwardly. 


2. Humero-radial, or Elbow Articulation. 


(Preparation—Turn down the inferior extremity of the flexors of the fore-arm, 
remove the olecranian, epicondyloid, and epitrochlean muscles, taking care not to 
damage the ligaments to which they somewhat closely adhere.) 


Three bones concur to form this articulation, which presents a remark- 
able example of an angular ginglymus: the humerus, by its inferior ex- 
tremity, and the two bones of the arm by their upper extremities. 

Articular swrfaces.—The humeral surface, already described at page 74, 
is transversely elongated, and convex from before to behind. It presents: 
1, A median groove excavated by a synovial fossette; 2, An external groove 
(humeral trochlea) not so deep as the preceding; 3, A kind of voluminous 
condyle which borders, inwardly, the internal pulley, and whose antero- 
posterior diameter is much greater than that of the external lip of the 
trochlea of the opposite side. The antibrachial surface, divided into two 
portions, is moulded to the humeral surface ; it is, therefore, concave before 
and behind, and is composed: 1, Of a double external groove; 2, Of an 


ARTICULATIONS OF THE ANTERIOR LIMBS. 145 


internal glenoid cavity, both excavated, on the superior extremity of the 


radius; 3, A middle ridge re- 
sponding to the middle groove 
of the humerus, separating the 
two preceding surfaces, and 
prolonged on the ulnar beak, 
where it forms the sygmoid 
notch. This ridge shows a 
small synovial fossette hol- 
lowed out on the radius and 
ulna. 

Mode of union—Three 
ligaments : two lateral and an 
anterior. 

a. The eaternal lateral liga- 
ment (Fig. 85, 8) is a thick, 
short, and strong funicle, at- 
tached above to the crest limit- 
ing outwardly and posteriorly 
the furrow of torsion, and in 
the small cavity placed at the 
external side of the humeral 
articular surface. Below, it is 
inserted into the supero-ex- 
ternal tuberosity of the radius. 
Its anterior border is con- 
founded with the capsular liga- 
ment, and is margined by the 
principal extensor of the pha- 
langes, which derives from it 
numerous points of attach- 
ment. By its posterior border 
it is in contact with the ex- 
ternal flexor of the metacarpus. 
Its internal face is lined by 
synovial membrane, and its 
external face is only separated 
from the skin by the anti- 
brachial aponeurosis and some 
of the fasciculi from the origin 
of the lateral extensor muscle 
of the phalanges. Its super- 
ficial fibres are vertical, and are 
continuous, behind, with the 
arciform ligamentous bands 
which stretch from the ulna to 
the radius. Its deep fibres are 
slightly oblique downwards 
and forwards. 

b. The lateral internal liga- 
ment, also funicular, is longer, 
but not so strong as the pre- 


Fig. 85, 


SCAPULO-HUMERAL AND HUMERO-RADIAL ARTICU- 


LATIONS, WITH THE MUSCLES SURROUNDING THEM 
(EXTERNAL FACE). 


1, Scapulo-humeral capsular ligament; 2, Short ab- 


ductor muscle of the arm; 3, Its insertion in the 
humerus; 4, Insertion of the subspinous muscle 
on the crest of the great tuberosity; 5, Coraco- 
radial muscle; 6, Its tendon of origin attached to 
the coracoid process; 7, Its radial insertion con- 
founded with the anterior ligament of the ulnar 
articulation; 8, 8, External lateral ligament of that 
articulation; 9, Anterior ligament; 10, Aconeus, or 
small extensor of the fore-arm; 11, Origin of the 
external flexor muscle of the metacarpus; 12, Short 
flexor muscle of the fore-arm.—aA, Tuberosity of 
the scapular spine.—s, Superspinous fossa.—c, Sub- 
spinous fossa.—D, Convexity of the small trochan- 
ter,—£, Summit of the trochanter. 


ceding. It arises from the small tuberosity on the inner side of the 


146 THE ARTICULATIONS. 


superior articular face of the humerus and, widening as it descends, reaches 
the radius. Its median fibres, which are the longest, are directed vertically 
downwards to reach the imprints situated below the bicipital tuberosity ; 
its anterior fibres, curved forwards, are united to the tendon of the coraco- 
radial muscle, or are confounded with the anterior ligament; the posterior 
are turned backwards, near their inferior extremities, to join the arciform 
fibrous fasciculi which inwardly unite the ulna to the radius. The middle 
fibres of this ligament cover the inferior insertion of the short flexor of the 
fore-arm and, in part only, that of the long flexor. It is covered by the 
ulna-plantar nerve and the posterior radial artery and vein. ; 

c. The anterior or capsular ligament (Fig. 85, 9) is a membraniform band, 
attached by its superior border above the humeral articular surface, and by 
its inferior to the anterior margin of the radial surface. By its lateral 
borders, it is confounded with the funicular ligaments. Its internal half 
is formed of vertical fibres which descend from the humerus and expand 
over the radius, where they become united with the inferior tendon of the’ 
coraco-radial muscle. In its external moiety it is extremely thin, and 
composed of fibres crossed in various directions. Lined internally by 
synovial membrane, this ligament is in contact, by its external surface, with , 
the anterior radial vessels and nerves, the two flexor muscles of the fore-arm, 
the anterior extensor of the metacarpus, and anterior extensor of the 
phalanges. The two latter muscles are even attached to it in a very evident 
manner. The elbow articulation, closed in front and on the sides by the 
three ligaments just described, has no particular ligaments posteriorly ; but 
it is powerfully consolidated: there by the olecranian insertion of the extensor 
muscles of the fore-arm, and by the tendons of origin of the five flexor 
muscles of the metacarpus or phalanges. 

Synovial membrane—This membrane is very extensive and, stretched 
out on the internal face of the before-mentioned ligaments, forms behind 
three great culs-de-sac of prolongment : a superior, occupying the olecranian 
fossa, and covered by a fatty cushion, as well as by the small extensor 
muscle of the fore-arm;1! two lateral, which descend from each side of the 
ulnar beak, and are distinguished as internal and external ; the first li, 
the tendon of the external flexor of the metacarpus ; the second facilitates 
the play on the upper radial extremity of the four flexor muscles of the foot 
or digits, and which are attached in common to the epitrochlea. This synovial 
sac also furnishes the radio-ulnar articulation with a diverticulum which 
descends between the bones of the fore-arm to below the adjacent diar- 
throdial facets. 

Movements. —Flexion and extension. 

In flexion, the two bones do not approach each other directly, the inferior 
extremity of the radius deviating a little outwards. This ig due more to 
the slight obliquity of the articular grooves than to the difference in 
thickness existing between the external and internal extremities of the 
humeral surface. 

Extension is limited by the reception of the beak of the olecranon in its 
fossa, and by the tension of the lateral ligaments; so that the two rays 
cannot be straightened on one another in a complete manner, or placed on 
the same line. 


In the Dog and Cat, the external lateral ligament is very thick, and forms in its 


1 Some grey elastic fibres which cover this cul-de-sac externally, have been wrongly 
described as @ posterior membraniform ligament. = 


ARTICULATIONS OF THE ANTERIOR LIMBS. 147 


inferior moiety a fibro-cartilaginous cap which is fixed on the ulna and radius, and united 
in front to the annular ligament of the superior radio-ulnar joint. This cap, with the last- 
named ligament, completes the osteo-fibrous ring in which the superior extremity of the 
radius turns. The internal lateral ligament is inserted by two very short fasciculi into 
the ulna and inner side of the head of the radius. A third fasciculus, deeper and median 
much more developed than the first, and covered by the inferior insertion of the flexors 
of the fore-arm, descends between the radius and ulna to the posterior face of the 
former, and is there inserted near the inferior attuchment of the external ligament, 
which it appears as if about to join. 

In Man, the elbow articulation is formed nearly on the same plan as that of the Dog 
and Cat. The radius and ulna move together when the fore-arm is flexed and extended 
on the humerus. 


8. Radio-ulnar Articulation. 


Articular surfaces—The two bones of the fore-arm correspond by 
diarthrodial and synarthrodial surfaces. 

a. The diarthrodial surfaces consist of four undulated, transversely 

elongated facets, two of which are radial and two ulnar. The first border, 
posteriorly, tho great articular surface forming the elbow joint; the second 
are situated beneath the sigmoid notch. 

b. The synarthrodial surfaces are plane and roughened, and are also two 
on each bone: one, superior, extends below the diarthrodial facets to the 
radio-ulnar arch; the other, inferior, more extensive, occupies all the 
anterior face of the ulna from this arch; on the radius it forms a very 
elongated triangular imprint which descends to the lower fourth of the bone. 
See pages 75, 76. 

Mode of wnion.—T wo interosseous and two peripheral ligaments. 

a. The interosseous ligaments, interposed between the synarthrodial 
surfaces, are composed of extremely short white fibres passing from one to 
the other surface, and which are endowed with a very remarkable power 
of resistance. The inferior always ossifies a long time before the animal 
is full grown: a circumstance which caused the older veterinary anatomists 
to describe, and with some show of reason, the radius and ulna as a single 
bone. Ossification of the superior ligament is very rare. 

b. The peripheral bands are bundles of arciform fibres which, from the 
uk of the olecranon to the radio-ulnar arch, leave the lateral faces of 
the ulna to pass, some inwards, others outwards, to the posterior face 
of the radius. The fibres of the external ligament are confounded with the 
external humero-radial ligament. The internal fibres are united to the 
internal humero-radial ligament, and to the small ulnar tendon belonging 
to the short flexor of the fore-arm. Analogous fibres are found beneath the 
radio-ulnar arch; but they are much shorter and less apparent. (This is 
the external transverse radio-ulnar ligament of Leyh.) 

Movements.—Very obscure in youth; nearly null when consolidation of 
the two bones takes place. 


In the Oz, ossification of the superior interosseous ligament is constant at adult 
age. 
‘ In the Dog and Cat, we have already seen (p. 87) that the radius and ulna are not 
fused to each other, but remain independent during life. They are united in their 
middle portion by an interosseous ligament, and join by diarthrosis at their two 
extremities. These animals therefore exhibit: 1, An dnterosseous ligament; 2, A 
superior radio-ulnar articulation ; 3, An inferior radto-ulnar articulation. 

Interosseous ligament.—lt is composed of very resisting white fibres, attached by 
their extremities to the bodies of the bones. Notwithstanding their shortness, they are 
loose enough to allow movements taking place between the radio-ulnar articulations. 

Superior radio-ulnar artic ulation.—This is a trochoid articulation, which only allows 
movements of rotation or pivoting. 


14s THE ARTICULATIONS. 


in the ulna, the small 


form this articulation are: PY ire 2RdTUs, 


fr ‘ é 
oe ee d in the lateral sense, and semicircular ; 


sigmoid cavity, a surface excavate 


indri -hi ived into the preceding cavity. 
pre ie eeecer Se anal ligament, a kind of fibrous web Jugs around 
wnenine the radius, fixed inwardly on the ulna near the inner 


the superior extremity of , s piel later 
i ict ty, attached outwardly to the exte r 
ney ee ian oul confounded superiorly with the anterior 


ligament of the elbow articulat 5 ‘ we Ben ee he Gee 

5 ticulation. This fibrous web, in uniting ; ¢ 

Fe one be of the pxtaimal humero-radial ligameut, and joining the small sigmoid 
ag z 


: F A 5 ; 
cavity by ts feanl excl. aioe, et aeabraae oak of ele 
cartilage, im its pony Pronipus portion, ‘he bead oF superior extremity of the radia 
is also incrusted over its entire contour with u layer of cartilage: a disposition which 
permits it to glide not only in the concave face of the small sigmoid cavity, but also on 
the internal face of the two ligaments which complete this cavity. 7 ; 

Inferior radio-ulnar articulation.—This is also a trochoid articulation analogous to 
the preceding, but inversely disposed. Thus, the concave articular surface is hollowed 
on the radius, outside the inferior extremity; the convex surface lies within the ulna, 
These two facets are very small, and are maintained in contact by a diminutive 
peripheral fibrous capsule. A strong interosseous ligament, situated under the 
articular facets, also consolidates this diarthrosis, and concurs by its inferior border to 
form the antibrachial surface of the radio-carpal articulation, A small synovial 
capsule is specially devoted to this articulation. 

Mechanism of the radio-ulnar joints—The play of these two articulations is 
simultaneous, and tends to the same end; that is, to the execution of the double 
rotatory movement which constitutes supination and pronation. 

Supination is when the ulna remains fixed, and the radius pivots on it in sucha 
manner as to carry its auterior face outwards. Its superior extremity then turns from 
within forwards, and even from before outwards if the movement is exaggerated, in the 
articular girdle formed by the small sigmoid cavity of the ulna and the ligaments which 
complete it. The inferior extremity also rolls on the ulnar facet in describing a similar 
movement, and the internal tuberosity of this extremity is carried forwards. 

In the movement of pronation, this tuberosity is brought inwards, and the anterior 
face of the radius comes forward by an opposite mechanism. 

The inferior ray of the anterior member being articulated in a hinge-like manner 
with the radius, it follows that bone in its rotatory movements, the anterior face of the 
metacarpus looking outwards during supination and forwards in pronation. 

The radio-ulnar articulation in Man resembles that of the Dog and Cat, the articular 
surfaces only being larger and the movements more extensive. In supination, the 
palmar face is turned forward, and the radius, situated on the outer side of the ulna, is 
in the same direction as the latter. In pronation, on the contrary, the palmar face of 
the hand looks backwards, and the radius, remaining outwards in its upper part, crosses 
the ulna in front in such a manner that its lower extremity is placed within the ulna. 


4. Articulations of the Carpus. 


(Preparation.—Remove the tendons from around th rticulati i i 
sheaths, but taking care of the ligaments.) i ac li 


These comprise: 1, The articulations uniting the carpal bones of the 
first row to each other ; 2, The analogous articulations of the second row; 
3, The radio-carpal articulation ; 4, The articulation of the two rows with 
each other; 5, The carpo-metacarpal articulation. 

ARTICULATIONS WHICH UNITE THE Bonzs or tue First Row 10 EACH 
orHrr.—These bones, four in number, are joined by the diarthrodial facets 
on their lateral faces and form small arthrodial articulations! They are 
maintained in contact by six ligaments, three anterior, and three interosseous. 
The anterior ligaments ave small flattened bands carried from the fourth pone 
to the first, from the first to the second, and from that to the third. The 
first, placed outside rather than in front of the carpus, is covered by the 


? The facet uniting the supercarpal to the first b i i i 
faces, but rather on the anterior part of its Vinenmferenng, neat ne basa 


ARTICULATIONS OF THE ANTERIOR LIMBS. 149 


_ external lateral ligament and the inferior tendon of the external flexor of 
the metacarpus; the others adhere to the capsular ligament. The inter- 
osseous ligaments are implanted in the grooves of insertion which separate 
the diarthrodial facets. One of them, derived from the common superior 
ligament, unites the first to the second bone. The two others, situated 
between the three last carpal bones, are confounded with the corresponding 
anterior ligaments. 

ARTICULATIONS UNITING THE CarpaL Bones oF THE Szconp Row.— 
These ave arthrodial articulations, like the preceding, but numbering only 
two. They are fixed by two anterior and two interosseous ligaments. One of 
the anterior ligaments joins the first bone to the second, and strongly adheres 
to the capsular ligament ; the other is entirely covered by the lateral internal 
ligament, and attaches the two last bones to each other. Of the two inter- 
osseous ligaments, the second alone is confounded with the corresponding 
anterior ligament. That which is situated between the two first bones is 
separated from the anterior ligament by one of the diarthrodial facets between 
these bones. 

Rapio-carpaL ARTICULATION.—The inferior extremity of the radius, in 
becoming united to the upper row of carpal bones, constitutes a diarthrosis 
which, from the nature of the movements it permits, may be considered as 
an imperfect hinge joint. 

Articular surfaces—The radial surface, elongated transversely and very 
irregular, presents: 1, Outwardly, a wide groove, limited in front by a 
small glenoid cavity, and bounded, posteriorly, by a non-articular excavation 
which receives a prolongation of the second bone in the movement of flexion , 
2, Inwardly, a condyle, with a more extensive curvature than that of the 
preceding groove and, like it, completed by a small anterior glenoid cavity. 
The carpal surface, moulded exactly on the radial, offers depressions corre- 
sponding to the projections on it, and vice versd. 

Mode of union—The radio-carpal articulation is bound by three liga- 
ments which entirely belong to it, and by four strong ligaments that are 
common to it and articulations which will be studied hereafter. 

Of the three ligaments proper belonging to the radio-carpal articulation, 
one forms a thick, rounded funicle, extending from the radius to the fourth 
bone in an oblique direction downwards and inwards, and concealed by the 
common posterior ligament. The second (Fig. 87. 5), much smaller, is 
carried from the supercarpal bone to the external side of the inferior 
extremity of the radius, and is partly covered by the common external 
ligament. When the synovial capsule is distended by dropsy, it may form 
a hernia at the outer side of the carpus, by passing between this small 
ligament and the common posterior ligament. The third, very delicate, but 
always present, is deeply situated beneath the last; it is inserted, for one 
part, into the radius near the first proper ligament, and for the other, into 
the second bone and the caus! fees ligament which unites the supercarpal 
to the second bone. 

Synovial membrane.—After lining these three ligaments and the four 
great ligaments yet to be described, this membrane is prolonged between 
the three first carpal bones to cover the superior face of the interosseous 
ligaments which unite them. It even more frequertly descends into the 
articulation which joins the supercarpal to the first bone; though it also 
sometimes happens that this has a particular synovial capsule of its own. 

ARTICULATION OF THE Two Rows Between Eace Oruer.—Like the 


preceding, this is an imperfect hinge articulation. 
3 


150 THE ARTICULATIONS. 


Articular surfaces—These are two, and are both transversely range 
very irregular in their configuration, and divided into three portions. e 
inferior shows: behind, three small condyles placed side by side; in front, 
two slightly concave facets. The superior corresponds to the first by three 
glenoid cavities and two convex facets. ; ; a 

Mode of union.—For this articulation, besides the common great liga- 
ments, there are three particular ligaments. Two of these are very short, 
and are situated behind the carpus, underneath the great common posterior 
ligament, They are readily perceived by removing the capsular ligament, 
and strongly flexing the carpus. “The strongest extends vertically from 
the internal bone of the superior row to the second and third bones of the 
metacarpal row ;, the other descends obliquely from the first bone of the 
antibrachial row to the second of the inferior row.”—Rigot. 'The third 
ligament proper, much stronger than the other two, reaches from the 
supercarpal to the first bone of the inferior row and the head of the external 
metacarpal bone. It is confounded, outwardly, with the great external 
lateral ligament; inwardly, with the common posterior ligament. Its 
posterior border gives attachment to the fibrous arch which completes the 
carpal sheath. This ligament has also a branch which is fixed on the 
second bone of the upper row (Fig. 87, 4). ; 

Synovial membrane.—This lines all the ligaments, and is prolonged 
above and below, between the carpal bones, to facilitate 
the gliding of their articular facets. Two upper pro- 
longations ascend between the three first bones of the 
antibrachial row to cover the inferior face of the inter- 
osseous ligaments uniting them. Two other prolong- 
ations descend between the carpal bones of the second 
row; the external, after covering the first interosscous 
ligament, passes between it and the corresponding an- 
terior ligament, and communicates with the synovial 
capsule of the carpo-metacarpal articulation. The in- 
ternal forms a cul-de-sac which rests on the inter- 
osseous ligament 

Carpo-MzracarpaL ARTICULATION.—The carpal 
bones of the second row articulate with the superior 
extremity of the metacarpal bones, constituting a plani- 
form diarthrosis. 

Articular surfaces—These are, on each side, plane 


CARPAL ARTICULA- 
TIONS; FRONT VIEW. 


1, 1, Anterior liga- 
ments uniting the 
carpal bones of each 
row; 2, 2, Anterior 
_ ligaments proper to 
the carpo-metacar- 
| pal articulation; 3, 
-Common external 
ligament; 4, Com- 
mon internal liga- 
ment. 


facets more or less inclined one on the another, and 
continued between each other The largest is in the 
middle, and is generally hollowed by a small, shallow, 
synovial fossette 

Mode of unton—There are the four great common 
ligaments, and also six special ligaments: two anterior, 
two posterior, and two intB cocous, 

Of the two anterior ligaments (Fig. 86, 2, 2), one is 
divided into two distinct bands, and unites the second 
bone to the principal metacarpal; the other, concealed 


‘by the external lateral ligament, attaches the first bone to the head of the 
external metacarpal bone. 


The two posterior ligaments described 


by Rigot do not appear to us to 


be sufficiently distinct from the great ligament to merit a special description. 


The two interosseous ligaments, 


completely overlooked by that able 


ARTICULATIONS OF THE ANTERIOR LIMBS. 151 


anatomist, start from the interstices which separate the median metacarpal 
bone from the lateral metacarpals, and join the interosseous ligaments of the 
second row; they are thick and short. We have sometimes noted one or 
other of them to be absent. 

Synovial membrane.—This communicates, as indicated above, with the 
synovial capsule of the preceding articulation. It furnishes a superior cud- 
de-sac which rests on the interosseous ligament interposed between the two 
last carpal bones of the second row. Two inferior culs-de-sac descend into 


the intermetacarpal arthrodial articulations. 


LicaAMENTs cComMoN TO THE THREE PRECEDING ARTICULATIONS, — As 


before mentioned, these are four in number two lateral, 
one anterior, and one posterior. 

a. The external lateral ligament (Figs. 86 and 87, 3) is a 
thick funicular cord composed of two orders of fibres—a deep- 
seated and a superficial order, slightly crossed. It leaves 
the external and inferior tuberosity of the radius, descends 
vertically to the side of the carpus, transmits a fasciculus 
to the first bone of the upper row, gives off another fasci- 
culus which stops at the external bone of the second row, 
and terminates on the head of the corresponding metacar- 
pal bone. Traversed obliquely by the lateral extensor of 
the phalanges, this ligament covers the external carpal 
bones. In front, it is united to the capsular ligament; 
near its inferior extremity, it is confounded with the strong 
ligament which joins the supercarpal bone to the first bone 
of the inferior row and to the head of the external meta- 
carpal bone. 

b. The internal lateral ligament (Fig. 86, 4), analogous 
to the preceding and situated on the opposite side, is wider 
and thicker than it. It commences on the internal tube- 
rosity of the radius, and terminates on the upper extremity 
of the middle and internal metacarpal bones, after being 
attached, by two distinct fasciculi, to the third carpal bone 
of the upper row, and the two last of the metacarpal row. 
In contact by its external face with the tendon of the 
oblique extensor muscle of the metacarpus, this ligament 
responds, by its deep face, to the synovial membranes of 
the carpus and to the bones to which it is attached. By 
its anterior border it is united to the capsular ligament, 
the opposite border is intimately confounded with the pos- 
terior ligament, from which it is impossible to distinguish 
it. 

c. The anterior, or capsular ligament, is a membranous 
band covering the anterior fage of the carpal articulations. 
Its superior border is attached to the radius, the inferior 
is inserted into the superior extremity of the principal 
metacarpal bone. The two right and left borders are 
united with the lateral ligaments. Its external face is in 
contact with the tendons of the anterior extensor muscles 
of the metacarpus and phalanges. The internal face is 
lined at certain points by synovial membrane, and adheres 
in others to the carpal bones and the anterior ligaments 
binding these to one another. 


Fig. 87. 


LATERAL VIEW OF 
THE CARPAL AR- 
TICULATIONS, 

1, 1, Anterior liga- 
ments uniting 
the two rows of 
carpal bones ; 2, 
2, Anterior liga- 
ments proper to 
the carpo-meta- 
carpal articula- 
tion; 3, Common 
external _ liga- 
ment; 4, One ot 
the ligaments 
proper to the 
articulation of 
the two rows 
(metacarpo - su- 
pracarpal); 5, 
One of the liga- 
ments proper to 
the radio-carpal 
articulation (ra- 
dio — supracar- 
pal).—a, Groove 
on the external 
surface of thesu- 
pracarpal bone 
for the passage 
of the external 
flexor of the me- 
tacarpus, 


This ligament is composed of transverse 


152 THE ARTICULATIONS. 


fibres more or less oblique, and arranged crosswise; by its amplitude it 
can adapt itself to the movements of flexion of the knee. ; ; 

d. The posterior ligament, one of the strongest in the animal economy, 
covers the posterior face of the carpus, fillmg up the asperities which 
roughen it, It is inserted: above, on the transverse crest surmounting the 
articular surface of the radius ; by its middle portion into all the carpal bones ; 
below, into the head of the principal metacarpal bone, Confounded inwardly 
with the internal lateral ligament, united outwardly to the band which attaches 
the supercarpal to the external metacarpal and the second carpal bone of the 
upper row, this ligament is continued, by its inferior extremity, with the 
carpal stay (or check ligament) which sustains the perforans tendon. Its 
posterior face is perfectly smooth, and is covered by the synovial membrane 
of the carpal sheath. 

Movements or THE CarpaL ArticuLaTions.—The carpus is the seat of 
two very extensive and opposite movements—flexion and extension ; to which 
are added three very limited accessory movements—adduction, abduction, and 
circumduction. 

All the carpal articulations do not take an equal part in the execu- 
tion of these movements, for it is easy to discover that they are chiefly 
performed in the radio-carpal diarthrosis, and in the imperfect hinge 
articulation uniting the two rows of carpal bones. Each of these articula- 
tions participates im the movements of the carpus in nearly the same pro- 
portions, and; both act in an identical manner. Their mechanism is most 
simple. 

is flexion, the first tier of bones rolls backwards on the radius, the inferior 
row moves in the same sense on the upper, the metacarpus is carried back- 
wards and upwards, the common posterior ligament is relaxed, the capsular 
ligament becomes tense, and the articular surfaces, particularly those of the 
second joint, separate from each other in front. In extension, the metacarpus 
is carried downwards and forwards by an inverse mechanism. This move- 
ment stops when the ray of the fore-arm and that of the metacarpus are in 
the same vertical line. In flexion, these rays never directly approach each 
other ; the inferior extremity of the metacarpus being always carried outwards. 
It may also be remarked, that the slight movements of abduction, adduction, 
and circumduction of the carpus are only possible at the moment when the 
foot is flexed on the fore-arm, 

With regard to the planiform diarthrosis articulating the carpal bones of 
the same row, they only allow a simple gliding between the surfaces in 
contact ; and with the carpo-metacarpal arthrodia it is absolutely the same. 
The restricted mobility of these various articulations has but a very secondary 
influence on the general movements of the carpus ; but it nevertheless favours 
them by permitting the carpal bones to change their reciprocal relations, 
and adapt themselves, during the play of the radio-carpal and intercarpal 
hinges, to a more exact coaptation of the articular planes which they form. 

In the other animals, the carpal articulations have the same essential characteristics 
we have noticed in Solipeds, The four principal peripheral bands differ but little in 


them; though in the Dog and Cat they are lax enough to allow somewhat extensive 
lateral movements. 


5. Intermetacarpal Articulations. 


Each lateral metacarpal bone articulates with the middle one by means 
of diarthrodial and synarthrodial surfaces, for the description of which refer 
to page 82. An interosseous ligament, composed of very short and strong 


ARTICULATIONS OF THE ANTERIOR LIMBS. 153 


fasciculi, is interposed between the synarthrodial surfaces, and binds them 
firmly together. Its ossification is not rare. The diarthrodial facets are 
maintained in contact by the preceding ligament, and by the carpal ligaments 
inserted into the head of the lateral metacarpal bones. The intermetacarpal 
articulations only allow a very obscure, vertical, gliding movement. 

In the Oz, there is only one intermetacarpal articulation, which is much simpler 
than those in the Horse. 


In the Pg, the four metacarpal bones correspond, at their upper extremity, by means 
of small diarthrodial facets on their sides. Fibrous fasciculi, derived from the great 
anterior and posterior ligaments of the carpus, protect these intermetacarpal articula- 
tions before and behind. Other fibres, situated between the adjacent faces of the 
metacarpal bones, are real interosseous ligaments. 


In the Dog and Cat, the four great metacarpal bones articulate with each’ other in 
almost the same manner as in the Pig, but their mobility is greater. 


6. Metacarpo-phalangeal Articulation. 


(Preparation Turn down the anterior and lateral extensor tendons of the phalanges, 
after carefully cutting through their attachment with the capsular ligament. Lay open 
the metacarpo-phalangeal sheath from above to below, and turn down the flexor 
tendons.) 


This is a perfect hinge-joint, formed by the inferior extremity of the 
median metacarpal bone on the one part, and the superior extremity of the 
upper phalanx and sesamoids on the other. 

Articular surfaces.—For the metacarpal bone, there are two lateral 
condyles and a median antero-posterior eminence; for the first phalanx, two 
glenoid cavities and an intermediate groove prolonged posteriorly on the 
anterior face of the two sesamoids. Divided in this manner into three por- 
tions, the digital surface is well constituted for solidity, because the pressure 
transmitted to this region is diminished and diffused by the natural elasticity 
of the bands which unite these three pieces to each other. 

Mode of union. The means of union may be divided into two categories: 
1, Those which join together the several bones of the inferior surface ; 
2, Those which maintain in contact the two opposed articular surfaces. 

A. The first have received the generic name of sesamoid ligaments, and 
are six in number: an intersesamoid ligament, which keeps together the two 
complementary bones of the digital surface; three inferior and two lateral 
sesamotd ligaments, which unite these bones to the first phalanx. 

a. The intersesamoid ligament is composed of fibro-cartilaginous substance 
which appears to be the matrix in which the two sesamoids were developed, 
as it is spread around these bones, after being solidly fixed on their internal 
face. Behind, this ligament, in common with the posterior face of the sesa- 
moids, forms the channel (Fig. 89, 5) in which the flexor tendons glide. 
In front. it occupies the bottom of the intersesamoid articular groove. 

b. The inferior sesamoid ligaments, situated at the posterior face of the 
first phalanx, are distinguished as superficial, middle, and deep. 

The superficial ligament (Fig. 89, 8), the longest of the three, is a narrow 
band flattened before and behind. It arises from the middle of the fibro- 
cartilaginous mass which completes, posteriorly, the superior articular 
surface of the second phalanx, and slightly widening, ascends to the base of 
the sesamoids, into which it is inserted by becoming confounded with the 
intersesamoid ligament. Its posterior face, lined by the synovial membrane of 
the so-called sesamoid sheath, is covered by the flexor tendons; it partly 
covers the middle ligament. 

The middle ligament, triangular and radiating, is composed of three 


154 THE ARTICULATIONS. 


particular fasciculi: two lateral (seen on each side of the superficial liga- 
ment in Fig. 89, 8), and a median which has been generally confounded 
with the superficial ligament, although it is clearly distinguished from it 
by its inferior insertion. Fixed in common to the posterior imprints of the 
first phalanx, these three fasciculi diverge in ascending to the base of the 
sesamoids, whére they have their upper insertion. 

The deep ligament is constituted by two small bands concealed beneath 
the middle ligament. Thin, short, flattened before and behind, and inter- 
crossed, these bands are fixed to the base of the sesamoids in one direction, 
and in the other to the superior extremity of the first phalanx, near the 
margin of its articular surface. This ligament is lined on its anterior face 
by the synovial membrane of the articulation.’ 

ce. The lateral sesamoid ligaments are two thin layers extending from the 
external face of each sesamoid to the tubercle of insertion on the side of 
the superior extremity of the first phalanx. They are covered by the digital 
vessels and nerves, by the fibrous stay detached from the suspensory liga- 
ment to the anterior extensor tendon of the phalanges, and by the superficial 
fasciculus of the lateral metacarpo-phalangeal ligament ; they are covered by 
synovial membrane on their internal face. 

B. The ligaments destined to unite the two articular surfaces of the meta- 
carpo-phalangeal joint are four: two lateral, one anterior, and one posterior. 

a. Each lateral ligament comprises two fasciculi, a superficial and a 
deep, firmly united by their adjacent faces. The superficial fasciculus 
commences on the button of the lateral metacarpal bone, attaches itself to 
the median metacarpal, and descends vertically to terminate at the superior 
extremity of the first phalanx. It covers the phalangeal insertion of the 
lateral sesamoid ligament and the deep fasciculus. The latter, attached 
superiorly in the lateral excavation of the infericr extremity of the principal 

metacarpal, radiates as it reaches the sesamoid and the superior extremity 
of the first phalanx, where it is fixed by mixing its fibres with those of the 
lateral sesamoid ligament. The inner face of this fasciculus is lined by the 
articular synovial membrane. 

b. The anterior ligament belongs to the class of capsular ligaments. It 
is a very resisting membraniform expansion which envelops the anterior face 
of the articulation. Attached by its upper border to the anterior margin of 
the metacarpal surface, and by its inferior border to the first phalanx, this 
expansion is confounded at its sides with the lateral ligaments. It is covered 
by the extensor tendons of the phalanges, which glide on its surface by means 
of small serous sacs. Its internal face adheres throughout its whole extent 
to the synovial capsule. 

c. The posterior ligament, very appropiately named the suspensory ligament 
of the fetlock (Figs. 88 , 89, 4), is a long and powerful brace, composed of white 
fibrous tissue, and often containing fasciculi of fleshy fibres in its texture. 
Lodged behind the median metacarpal, and between the two lateral meta- 
carpal bones, this brace is quite thin at its origin, but it soon becomes 
enlarged, and preserves its great thickness to the extent of its upper fourth. 
Examined in section, it appears to be formed of two superposed portions which 
are closely adherent to each other. The superficial portion, the thinnest, 
commences by three small branches, which are fixed to the first and second 


* The two bands described by Rigot as forming part of this ligament, belong to the 
lateral fasciculi of the middle ligament. 

* It corresponds to the two muscles which, in May, lie alongside the interosseous 
metacarpal muscles. See the Muscles of the foot. 


ARTICULATIUNS OF THE ANTERIOR LIMBS. 155 


bones of the lower carpal row; the deep portion, much thicker, is attached 
to the posterior face of the principal metacarpal for about 8-10ths of an inch. 
It has been wrongly asserted that the suspensory ligament of the fetlock is 
continuous with the common posterior ligament of the carpus; it is, on the 
contrary, quite distinct from it. The carpal stay or deep palmar aponeu- 


rosis of Man, is alone in direct continuity with the common posterior liga- 
Fig, 88, 


ment of the carpus. The suspensory ligament of 
the fetlock is bifid at its inferior extremity ; its 
two branches, after being fixed into the summits 
of the sesamoid bones, give origin to two fibrous 
bands which pass downwards and forwards to 
become united on each side to the anterior ex- 
tensor tendon of the phalanges. It is in relation, 
by its posterior face, with the perforans tendon and 
its carpal stay; by its anterior face, with the 
median metacarpal bone, and arteries and veins; 
by its borders, with two small interosseous muscles, 
the lateral metacarpal bones, and the digital 
vessels and nerves. 

Synovial membrane.—This membrane is pro- 
longed as a cul-de-sac between the terminal 
branches of the preceding ligament. It is the 
distention of this sac which causes the articular 
swellings vulgarly designated “‘ windgalls.” 

Movements——The metacarpo-phalangeal articu- 
lation permits the extension and flexion of the digit, 
and some slight lateral motion when the movable 
osseous ray is carried to the limits of flexion. 


SECTION OF THE INFERIOR: 


In the Ox, Sheep, and Goat, this articulation consti- 
tutes a double hinge which resembles the simple gin- 
glymus of monodactyles. 

They have three intersesamoid ligaments two lateral 
to unite the large sesamoids of each digit, and a median 
which unites the internal sesamoids. The inferior sesa- 
moidean ligamentous apparatus is far from showing the same 
degree of development as in the Horse; it is reduced for 
each digit to four small bands, which remind one very 
much of the deep ligament of the latter animal, as it has 
been described by Rigot: two lateral bands pass directly 
from the sesamoids to the upper extremity of the first 
phalanx; the other two, situated between the first, inter- 


ROW OF CARPAL BONES, 
THE METACARPAL, AND THE 
SUSPENSORY LIGAMENT OF 
THE FETLOCK. 


1, Os magnum; 2, Common 


posterior ligament of the 
carpus; 3, Stay, or band 
for the perforans tendon; 
4, Suspensory ligament of 
the fetlock; 5, Its super- 
ficial layer; 6, Its deep 
fasciculus, 7, Principal 
metacarpal bone. 


cross and are confounded with the latter by their ex- 
tremities.—A lateral sesamoid ligament unites the first phalanx to the external sesamoid. 
For each digit there are two lateral metacarpo-phalangeal ligaments an external, 
analogous to that of the Hor-e, but less complicated, is attached by its inferior extremity 
to the first phalanx only; the other, internal, fixed superiorly in the bottom of the inter- 
articular notch of the metacarpal bone, is inserted into the inner face of the first 
phalanx in mixing its fibres with those of the superior interdigital ligament. This 
latter is situated between the two first phalanges, and is composed of short, intererossed 
fibres, attached to the imprints which in part cover the internal face of the two first 
phalangeal bones. In the Sheep there are only traces of this interdigital ligament, and 
each internal metacarpo-phalangeal ligament gives rise, near its phalangeal insertion, to 
a fibrous branch which is directed backwards from the interdigital space, and is 
terminated in the bone of the ergot (or posterior rudimentary digit), which it sustains, 
The anterior or capsular ligament, single as in Solipeds, unites the two external lateral 
ligaments. The suspensory ligament, single superiorly, is divided inferiorly into eight 
branches, two of which are joined to the perforatus tendon to form with it the double 
Ying through which the two branches of the perforans pass. Four other branches, in 


156 


THE ARTICULATIONS. 


pairs, extend to the summits of the sesamoids. That which is sent to each external 
sesamoid gives off, on the side of the first phalanx, a reinforcing band to the proper 


Fig. 89, 


POSTERIOR VIEW OF 
THE METACARPO- 
PHALANGEAL AND 
INTER - PHALAN- 
GEAL ARTICULA- 
TIONS; RIGHT 
LIMB. 

1, 3, Outer and inner 
rudimentary me- 
tatarsal bones; 2, 
Perforans tendon 


extensor of the digit. The two last, profound and median, descend 
into the interarticular notch of the metacarpal bone, after becoming 
a single fasciculus , afterwards, they pass between the two internal 
metacarpo-phalangeal ligaments, and separate from each other in 
passing downwards and forwards on the inner side of the first 
phalanx, to join the proper extensor tendon of each digit. 

In the Pig, Dog, and Cat, for each metacarpo-phalangeal there 
is: a proper synovial membrane; an intersesamoid ligament; an 
inferior sesamvid ligament composed of two cross-bands; two small 
lateral sesamoid ligaments; two lateral metacarpo-phalangeal liga- 
ments, attached inferiorly to the first phalanx and the sesamoids; 
an anterior capsular ligument, in the centre of which is found a 
small bony nucleus, a kind of anterior sesamcid, over which glides 
one of the branches of the common extensor of the digits. The 
suspensory ligament is replaced by real palmar interosseous muscles 
(see the Muscles of the fore-foot). Some fibres situated between the 
first phalanges of the great digits in the Pig, remind one of the 
superior interdigital ligament of the Ox. 

In Man, the cavity in the upper extremity of the first phalanx 
is completed by a glenoid ligament. The glenoid ligaments of the 
four first digits are united to each other by a transverse ligament 
of the metacarpus. The articulations are consolidated by two 
lateral ligaments. The metacarpo-phalanyeal articulations allow 
flexion and extension movements, us well as those of abduction 
and adduction ; but the latter are limited by the lateral ligaments. 


7. Articulation of the First with the Second Phalanx, or 
First Interphalangeal Articulation. 


(Preparation.—Remove the extensor tendon; throw open the 
metacarpo-phalangeal sheath, and turn down the flexor tendons.) 


This is an imperfect hinge-joint. 
Articular surfaces—On the inferior extremity of the 
first phalanx, there are two lateral condyles separated by a 


- groove. On the superior surface of the second phalanx, there 


are two glenoid cavities and an antero-posterior ridge. 
The latter surface is completed behind by a glenoidal 
jibro-cartilage, very dense and thick, which also acts as 
a ligament. It is attached, in one direction, to the 
second phalanx, between the superior articular surface 
and the kind of fixed sesamoid which margins it behind ; 
in the other, it is inserted into the first phalanx by means 
of six fibrous bands: two superior, which embrace the 
inferior, middle, and superficial sesamoid ligaments; two 
middle and two inferior, which extend to the sides of the 
inferior extremity of the first phalanx. This fibro-car- 
tilage is moulded, in front, to the articular surface of the 
latter bone, and forms, by its posterior face, a gliding 


and its check ligament ; 4, Suspensory ligament; 5, Gliding surface, or sheath for the 
flexor tendons, formed by the posterior face of the sesamoid bones, and intersesamoid 
transverse, and annular ligaments; 6, Section of lateral sesamoid ligament; 7, Lateral 
fasciculus of the middle inferior sesamoid ligament; 8, Inferior superficial sesamoid 
ligament; 9, Lateral ligament of the first interphalangeal articulation; 10, Section 
of the terminal branch of the perforatus tendon; 11, Section of the lateral cartilage 
of the foot; 12, Postero-inferior surface of navicular bone; 13, Section of lateral car« 
tilage, plantar cushion, and wing of pedal bone; 14, Perforatus tendon; 15, Perforans 


tendon. 


ARTICULATIONS OF THE ANTERIOR LIMBS. 157 


surface for the perforans tendon (Fig. 89, 5). It is confounded, laterally, 
with the two branches of the perforatus, and receives in the middle of its 
superior border the insertion of the inferior superficial sesamoid ligament. 

Mode of union.—Two lateral ligaments, to which are added, behind, the 
fibro-cartilage just described, and in front the tendon of the anterior 
extensor of the phalanges. These ligaments are large and thick, and passing 
obliquely downwards and backwards, are inserted, superiorly, into the 
lateral tubercles on the inferior extremity of the first phalanx. They are 
attached, beneath, to the sides of the second phalanx. Their most inferior 
fibres are even prolonged below that point to reach the extremities of the 
navicular bone, and constitute the posterior lateral ligaments of the pedal 
articulation. 

Synovial membrane.— This covers the tendon of the anterior extensor of the 
phalanges, the lateral ligaments, and the glenoid fibro-cartilage. Behind, it 
forms a cul-de-sac which extends between the latter and the posterior face of 
the first phalanx. 

Movements. This imperfect hinge is the seat of two principal movements: 
extension and flexion. It also allows the second phalanx to pivot on the first, 
and permits some lateral movements. 


In the Ox, Sheep, and Goat, the glenoid fibro-cartilage is confounded with the per- 
foratus tendon, and is only attached to the first phalanx by two lateral bands. The 
internal lateral ligament comprises two fasciculi: one, very short, which terminates in 
the second phalanx; and another, very long, descending to the internal face of the third 
phalanx. The external is very thin, and is also prolonged to the terminal phalanx; so 
that the two last interphalangeal articulations of each digit are fixed by twc common 
lateral ligaments which correspond exactly, by their position and inferior attachments, 
to the anterior lateral ligaments of the pedal joint of Solipeds. 

In the Dog and Cat, the glenoid cartilage, also confounded by its posterior face 
with the perforatus tendon, only adheres to the first phalanx by some cellular bands, 
The two lateral ligaments pass from the inferidr extremity of the first phalanx to the 
superior extremity of the second. 

In the Pig, there is somewhat the same arrangement as in Carnivora. The external 
lateral ligament is, nevertheless, more like that of the Horse, in its most anterior fasciculi 
being prolonged to the external extremity of the navicular bone. 


8. Articulation of the Second Phalanx with the Third, Second Interphalangeal 
Articulation, or Articulation of the Foot. 


To form this imperfect hinge-joint, the second phalanx is opposed to the 
third, and to the navicular bone. 

Articular surfaces. —On the inferior face of the second phalanx there are 
two lateral condyles and a median groove. On the superior face of the 
third phalanx and the navicular bone, are two glenoid cavities separated by 
an antero-posterior ridge. The two bones which form this last surface arti- 
culate with each other by an arthrodia; the navicular bone presents for this 
purpose an elongated facet on its anterior border; the os pedis also offers 
an analogous facet on the posterior contour of the principal articular surface. 

Mode of wnion.—Five ligaments: a single interosseous one which joins 
the navicular to the pedal bone; and four lateral pairs, distinguished as 
anterior and posterior. 

a. Interosseous ligament.—This is formed of very short fibres which are 
inserted, behind, into the anterior groove of the navicular bone; and in 
front, into the posterior border and inferior face of the third phalanx. This 
ligament is lined, on its superior surface, by the synovial membrane, and on 
its inferior face is covered by the navicular sheath. 

b. Anterior lateral ligaments.—These are two thick, short, and wide 


158 THE ARTICULATIONS. 


fasciculi, attached by their superior extremities to the lateral imprints of the 
second phalanx, and by their inferior extremities into the two cavities at the 
base of the pyramidal eminence of the os pedis. Each ligament is partly 
covered by the complementary fibro-cartilage of that bone, and appears to 
form a portion of it. Its anterior border is continuous with the common 
extensor tendon of the phalanges; its internal face is covered by the 
synovial membrane, which adheres closely to it. 

c. Posterior lateral ligaments—These have been already noticed. 
Each is composed of the lowermost fibres of the lateral ligament of the first 
interphalangeal articulation ; these fibres, after being attached to the 
second phalanx, unite into a sensibly elastic fibrous cord, which is chiefly 
fixed into the extremity and superior border of the navicular bone, where the 
ligaments join each other, and in this way form a kind of complementary 
cushion which increases the navicular articular surface. It also sends off 
a short fasciculus to the retrossal process, and a small band to the internal 
face of the lateral fibro-cartilage. Partly concealed by the latter and the 
plantar cushion, this ligament is covered inwardly by the articular 
synovial membrane. 

(For full details as to the manner in which the navicular is attached to 
the pedal bone, the student is referred to the series of papers on the Horse’s 
Foot, published by me in the ‘ Veterinarian’ for 1870. It is only necessary 
to refer here to the intimate connection there exists between the lateral and 
interosseous ligaments, and the stratiform fibro-cartilage covering the pos- 
terior face of this sesamoid: a connection, or rather unification, which has 
been strangely overlooked by hippotomists and hippo-pathologists, but 
which has undoubtedly a most important bearing on the genesis of that 
very prevalent and formidable malady of the anterior foot of the Horse 
—navicularthritis.) 

Synovial membrane.—This descends below the facets which unite the 
navicular to the pedal bone. It offers, postericrly, a vast cul-de-sac which 
reaches the posterior face of the second phalanx, and lies against the two 
navicular sheaths. It also forms another much smaller, by being prolonged 
between the two lateral ligaments of the same side. This is very often dis- 
tended, and it is liable to be opened in the operation for diseased cartilages. 

Movements.—The same as those of the first interphalangeal articulation. 


In the Sheep are found: 1, An interosseous ligament to unite the navicular bone to 
the third phalanx; 2, Two anterior lateral ligaments commencing, as already stated, at 
the first phalanx ; 3, Two lateral posterior ligaments, passing to the posterior face of the 
second phalanx and the navicular bone (the internal is yellow and elastic); 4, A single, 
anterior, elastic ligament, attached above to the superior extremity of the second 
phalanx, and fixed below into the third, between the insertion of the common extensor 
of the digits and that of the internal anterior lateral ligament; an inferior interdigital 
ligament, situated between the ungueal phalanges, whose separation from each other it 
limits. This ligament is composed of parallel fibres, which extend transversely from the 
one navicular bone to the other, and is covered on its inferior face by the skin of the 
interdigital space. Its upper face is in contact with an adipose cushion. 

In the Oa, the external anterior lateral ligament, wide and expanding, is almost 
entirely covered by the long branch of the proper extensor of the digit, to which it is 
intimately adherent. The interdigital ligament has a much more complicated character 
than that of the Sheep. It is formed of fibres intercrossed on the median line, and 
divided at its extremities into two fasciculi: a superior passes over the perforans tendon, 
to which it serves as a restraining band, and is fixed tu the outside of the inferior 
extremity of the first phalanx. after contracting very close adhesions with a strong fibrous 
web which descends from the posterior metacarpal region, and which will be more fully 
noticed when describing the muscles; an inferior, shorter than the preceding, attached 
to the internal extremity of the navicular bone and the internal face of the third phalanx, 


ARTICULATIONS OF THE POSTERIOR LIMBS. 159 


becoming confounded with the perforans tendon, the plantar cushion, and the kera- 
togenous membrane. 


In the Pig, for the maintenance of the second interphalangeal articulation. -there 
are: 1, Two lateral ligaments, carried from the lateral fuces of the second phalanx to 
the external and internal faces of the third; 2, A third ligament, exactly resembling one 
of the posterior lateral ligaments of the pedal articulation of the Horse; this ligament 
descends from the inferior extremity of the first phalanx to the internal extremity of the 
navicular bone. Its analogue of the inner side appears to be altogether absent; but 
in the large digits there is an anterior yellow elastic ligament like that of Ruminants. 

In the Dog, the two last phalanges are united by two lateral ligaments, very simply 
arranged. A third ligament, formed of elastic tissue, divided into two lateral portions, 
and situated in front of the articulation, plays the part of a spring, which mechanically 
produces the retraction of the claw when the flexor muscles cease to contract. In the 
Cat, this yellow ligament is very strong; and this animal also exhibits a very striking 
obliquity of the articular pulleys by which the two phalanges correspond: an arrange- 
ment which permits the claw to be lodged between two digits when they are raised, and 
thus favour its retraction. 

The second interphalangeal articulation of the Dog and Cat is also distinguished 
by another essential arrangement. ‘The articular surface of the third phalanx is com- 
pleted by a glenoid fibro-cartilage analogous to that of the first articulation, but much 
thicker. This fibro-cartilage (see MuscLES OF THE HAND) is fixed into the posterior 
projection of the third phalanx, and serves, by its inferior face, as a pulley for the per- 
forans tendon and, with the projection just named, plays the part of the navicular bone 
in other animals. 

The interphalangeal articulations of Man are formed on the same plan as the 
metacarpo-phalangeal articulations. They are consolidated by a glenoid and lateral 
ligaments, and possess only the two movements of flexion and extension. 


ArticLe V.—ARTICULATIONS OF THE Posterior Liss. 


1. Articulations of the Pelvis, 


( Preparation—These ligaments are all exposed to view by carefully removing the soft 
parts connected with the sacrum and coxe.) 


A. Sacro-1n1a0 Articunation (Fig. 90).—This is a pair articulation 
which establishes the union of the posterior limb with the spine, and is 
formed by the sacrum and coxa. It belongs to the arthrodial class. 

Articular surfaces—On the sacrum, the irregular diarthrodial facet 
named the “auricular,” cut on the sides and near the base of the bone. For 
the coxa, the analogous facet on the internal face of the ilium. 

Mode of wnion.—By four ligaments, which, after the example of Rigot, 
we will name sacro-iliac, superior ilio-sacral, inferior ilio-sacral, and the 
sacro-ischiatic. 

a. Sacro-iliae ligament.—This is composed of thick ae fasciculi, 
which envelope the whole articulation in being firmly attachéd by their 
extremities to the imprints around the diarthrodial facets. The inferior 
moiety of this ligament is covered by the psoas-iliacus (iliacus) muscle. Its 
posterior half! is much stronger, is hidden by the ilium, and gives attach- 
ment to the ilio-spinalis (longissimus dorsi) muscle. . ; 

b. Superior ilio-sacral ligament.—A thick and short funicle which, 
rising from the internal angle of the ilium, is carried backwards to be fixed 
to the sacral spine, where its fibres are confounded with those of the super- 
spinous dorso-lumbar ligament. 

c. Inferior ilio-sacral ligament.—This is a very resisting, triangular, 
membranous band, formed of parallel fibres passing obliquely downwards 
and backwards. It is attached, by its anterior margin, to the upper half of 


" It represents the interosseous sacro-iliac ligament of Man, The inferior half corre- 
sponds to the anterior sacro-iliac ligament. 


160 THE ARTICCLATIONS. 


the ischiatic border and the internal angle of the ilium, in becoming 
confounded with the preceding ligament. Its inferior margin 1s inserted 
into the rugged lip which borders the sacrum laterally. Its posterior border 
is united to the aponeurosis covering the coccygeal muscles, and its external 
face is in contact with the principal gluteal and the long vastus muscles ; 
while the internal corresponds to the lateral sacro-coccygeal muscle. 

d. Sacro-sciatie or ischiatic ligament (Fig. 90, 2).—This is a vast mem- 
branous expansion situated on the side of the pelvis, between the sacrum 
and the coxa, and serves more as a means for inclosing this portion of the 
pelvic cavity than to assure the solidity of the sacro-iliac articulation. ; Its 
form is irregularly quadrilateral, and permits its circumference to be divided 
into four borders: a superior, attached to the rugged lateral ridge of the 
sacrum ; an inferior, fixed to the supercotyloid ridge, as well as the ischial 
tuberosity, and forming by the portion comprised between these two in- 
sertions, with the small ischiatie notch, the opening by which the internal 
obturator and pyramidal muscles leave the pelvis; an anterior, imperfectly 
limited, along with the great ischiatic notch, circumscribes the opening 
through which the gluteal vessels and nerves, and the sciatic nerves pass; a 
posterior, doubled in the form of two lamine which embrace the semi- 
membranosus muscle, and is confounded superiorly with the aponeurosis 
enveloping the coccygeal muscles. The external face of this ligament is 
traversed by the sciatic nerves, and is covered by the long vastus and the 
semitendinosus muscles, which derive numerous insertions from it. Its 
internal face is covered, in front, by the peritoneum, and posteriorly is in 
contact with the ischio-coccygeal and ischio-anal muscles, to which it gives 
attachment. 

Synovial membrane.—This lines the sacro-iliac ligament, but only 
furnishes a small quantity of synovia. 

Movements.—The two sacro-iliac articulations being the centres towards 
which all the impulsive efforts communicated to the trunk by the posterior 
limbs converge, they do not offer much mobility, as that would oppose 
the integral transmission of the quantity of movement. So that they 
permit only a very restricted gliding of the articular surfaces; and the 
union of the sacrum and coxa by diarthrosis appears to be exclusively 
designed to prevent the fractures to which these bones would be incessantly 
exposed if they were fixed together in a more intimate manner. 

B. ArvicuLation or tHE Two Cox, or Iscuto-pusic Sympuysts.—The 
two coxe are united to each other throughout the whole extent of the inner 
border of the pubis and the ischial bones. In youth, this is a veritable 
amphiarthrosis, fixed by an interosseous cartilage and bundles of peripheral 
fibres. 

The cartilage is solidly fixed to the small rugged eminences which cover 
the adjacent articular surfaces, and becomes ossified, like the sutural 
cartilages, as the animal advances in age. In adult Solipeds the coxe are 
always fused with each other. 

The peripheral fibrous fasciculi extend tranversely from one bone to 
the other, above and below the symphysis; those on the inferior face are 
incomparably stronger and more abundant than the others. 

The movements of this articulation are most restricted, and depend 
solely upon the elasticity of the interosseous cartilage. They cease after its 
ossification. 


The fusion of the two cox proceeds very slowly in the female of the Cat, Dog, Pig, 
Ox, Sheep, and Goat species. 


ARTICULATIONS OF THE POSTERIOR LIMBS. 161 


2. Coxo-femoral Articulation. 


_ (Preparation — Remove the muselcs surrounding the articulation. To view the 
interior, divide the capsular ligament by a circular incision.) 


This is an enarthrosis, formed by the reception of the head of the 
femur into the cotyloid cavity of the coxa. 

Articular surfaces—As already shown, the cotyloid cavity represents 
the segment of a hollow sphere, deeply notched on the inner side, and 


SACRO-ILIAC AND COXO-FEMORAL ARTICULATIONS, WITH THE SMALL DEEP 
MUSCLES SURROUNDING THE LATTER. 

1, Sacro-iliac ligament; 2, Sacro-ischiatic ligament; 3, Great ischiatic notch; 4, 
Anterior portion of the capsular ligament of the coxo-femoral articulation; 5, 
Internal band of cotyloid ligament; 6, Coxo-femoral ligament; 7, Pubio-femoral 
ligament; 8, Its insertion into the femur; 9, Small gluteal muscle; 10, Origin 
of the straight anterior muscle of the thigh (rectus); 11, Anterior thin muscle 
(rectus parvus); 12, Pyramidal muscle of the pelvis; 13, External obturator 
muscle; 14, Square crural muscle (quadratus femoris); 15, Inferior sacro- 
coccygeal muscle. 


provided at the bottom with a wide depression, the internal moiety of which 
is destined for the insertion of one of the interosseous ligaments, while the 
external half plays the part of a synovial fossa. This depression is not 
covered by cartilage, and communicates by the internal notch with the 
inferior furrow on the pubis. The lip of the cotyloid cavity is covered by 
a complementary fibro-cartilage—the cotyloid ligament. This fibro-cartilage 
is not interrupted at the notch just mentioned, but passes over it, forming a 
remarkable band (Fig. 90, 5) that converts it into a foramen, through which 
pass the pubio- or ilio-femoral ligament and the vessels of the articulation. 


162 THE ARTICULATIONS. 


Fixed by its adherent border to the margin of the cotyloid cavity, this 
ligament is lined by synovial membrane on its faces and free border. It is 
thickest in front and within. Pane sake, 

With regard to the head of the femur, it will be remembered that it is 
exactly moulded to the cavity, and, like it, is excavated by a rugged fossa 
which is entirely occupied by the insertion of the interarticular ligaments. 

Mode of union.—This jomt is maintained by a peripheral capsule, and 
by two interarticular bands constituting the coxo-femoral and pubio-femoral 
ligaments. es . 

a. Capsular ligament (Fig 90, 4).—This is a membranous sac, like that 
of the scapulo-humeral articulation, embracing the head of the femur by its 
inferior opening, and attached by its opposite aperture to the margin of the 
cotyloid cavity and its protecting fibro-cartilage. This ligament is com- 
posed of intercrossed fibres, and is strengthened in front by an oblique 
fasciculus which descends to the body of the femur, along with the anterior 
thin muscle, near which it is fixed. Its internal face is covered by the articular 
synovial membrane, and its external face is in contact, through the medium 
of adipose cushions, with: in front, the anterior thin muscle (crureus) and 
the straight muscle (rectus) of the thigh ; behind, to the gemini, the internal 
obturator, and the pyramidal muscles; outwards and upwards, to the small 
gluteal muscle; within and below, to the external obturator. 

b. Coxo-femoral ligament (ligamentum teres, Fig. 90, 6).—A thick and 
short funicle of a triangular shape, deeply situated between the two bony 
surfaces, which it cannot, notwithstanding its shortness, maintain exactly in 
contact without the other muscular or ligamentous structures enveloping the 
articulation. Its upper insertion occupies the internal moiety of the bottom 
of the cotyloid cavity; and its inferior extremity is confounded with the 
pubio-femoral ligament, being fixed with it into the rough fossa in the head 
of the femur. It is enveloped by the synovial membrane. 

¢. Pubio-femoral ligament (Fig. 90, 7, 8).—This ligament, longer and 
stronger than the last, originates from the pubic tendon of the abdominal 
muscles and the anterior border of the pubis. Lodged in the inferior 
channel of that bone, it passes outwards, enters the internal notch of the 
cotyloid cavity, is inflected downwards on the fibrous band which converts 
that notch into a foramen, and goes with the preceding ligament to be 
inserted into the fossa in the head of the femur. Its pubic portion lies 
between the two branches of the pectineus, while its interarticular surface 
is covered by synovial membrane. 

Synovial membrane—This membrane is very extensive; it lines the 
internal face of the capsular and cotyloid ligaments, and is reflected on the 
interarticular ligaments to form around them a serous vaginal covering. It 
is even prolonged into the synovial fossa occupying the centre of the cotyloid 
cavity. 

Movements.—The coxo-femoral articulation is one of the joints which is 
endowed with the most varied and extensive movements. It permits the 
Jlexion, extension, abduction, adduction, circumduction, and rotation of the thigh 
on the pelvis. The mechanism of these movements is so simple, that they 
need no particular consideration. 


The domesticated animals other than Solipeds, are distinguished by the complete absence 
of the pubio-femoral ligament; so that in them the movements of abduction, which are 
limited in Solipeds by tlre tension of this ligament, are much more extensive; and it is 
the absence of the ligament in question, which explains the facility with which the larger 
Ruminants are enabled to strike sideways, a movement known as a “cow’s kick,” 


ARTICULATIONS OF THE POSTERIOR LIMBS. 163 


In Man, the head of the femur is more detached than in the domesticated animals, and 
the cotyloid cavity, encircled by the cotyloid ligament, is deeper. The femur is united 
to the coxa: 1, By a capsular ligament; 2, By a triaugular ligament, fixed above, to the 
cotyloid ligament at the notch, and below, into the depression in the head of the femur. 


Also, as the brothers Weber have shown, the atmospheric pressure is a powerful adjunct 
to these means of union. 


_ The coxo-femoral articulation of Man permits more extensive movements than that of 
animals, and especially abduction and adduction, which can be carried to 90 degrees. 


3. Femoro-tibial Articulation) 


(Preparation.—Remove the soft parts surrounding the articulation, taking care not to 
wound the synovial membrane. To expose the crucial ligaments, make an antero- 
posterior vertical section of the femur in such a way as to separate the condyles.) 


This is the most complicated joint in the body, and is formed by the 
union of the femur with two of the thigh bones—the tibia and patella. It 
represents an imperfect hinge-joint. 

Articular surfaces.—To form this articulation, the femur opposes its two 
condyles to the wide, convex, and undulated facets on the superior face of 
the lateral tuberosities of the tibia, and its articular pulley to the posterior 
face of the patella. 

_ The femoral faces have already been described in detail at page 98; but 
it may be repeated that the two condyles, placed side by side, are elongated 
in an antero-posterior direction, and are separated by a non-articular notch 
called the intercondyloid ; also, that the femoral trochlea situated in front 
of these two condyles appears to continue the preceding notch, and that its 
internal border is much more elevated than the external; an arrangement 
which explains why it is so difficult, if not impossible, for the patella to be 
dislocated inwards. 

The tibial facets ascend on each side to the lateral faces of the tibial 
spine. They are separated from one another by the antero-posterior groove 
cut on the summit of that bone, and by the fosse of insertion situated at its 
base before and behind. The external facet, wider than the internal, is 
devoted in part to the gliding of the originating tendon of the popliteal 
muscle. (See page 100.) 

The patellar surface, moulded on the femoral pulley, fits it in an imper- 
fect manner. It is bordered, outwardly, by a small fibro-cartilaginous ring, 
which is united to the fibrous capsule of the femoro-patellar articulation 
(Fig. 92,1). Inwardly, it is completed by the insertion of the internal 
patellar ligament, to be noticed immediately. ; 

Interarticular menisci (semilunar Jfibro-cartilages)— (Figs. 91, No. 1, 2, 
3, 4; and 92, 5, 6,7, 8)—By this designation is known the, two fibro- 
cartilages interposed between the condyles of the femur and the tibial facets, 
to assure their coaptation. They are crescent shaped bodies, and present : 
an internal, concave, thin and_sharp border, embracing the tibial spine; an 
external, thick, and convex border ; a superior face, excavated and moulded to 
one of the condyles; an inferior face, nearly plane, gliding on the tibia; and 
two extremities terminated by ligaments, and fixed to the bones in apposition. 
The articular surfaces are not entirely separated throughout their extent by 


1 this name is understood the joint uniting the femur to the tibia, and that which 
eae it ih the patella. Following the example of anthropotomists, it has not 
been deemed necessary to describe a femoro-patellar articulation distinct from the 
femoro-tibial, properly so called. This innovation appears to be justified by the com- 

- munity of the principal articular bands which bind these two joints, and by the reciprocal 
dependence of their movements, 


164 THE ARTICULATIONS. 


these complementary meniscii, for the tibial spine rubs directly against the 
inner sides of the femoral condyles. The.internal semilunar fibro-cartilage, 
the widest and thickest, is inserted by its anterior extremity into one of the 
excavations situated in front of the spine; its posterior extremity is attached 
in the fossa behind that eminence. The eaternal semilunar Jibro-cartilage is 
fixed, in front, near the anterior insertion of the opposite fibro-cartilage ; 
its posterior extremity gives origin to two slips or cords, one superior, the 
other inferior. The first, the strongest and longest, terminates in the fossa 
near the posterior extremity of the intercondyloid notch. The second, thin 
and flat, is inserted on the posterior outline of the external tibial facet, 


Fig. 91. 


No. 2. 


FEMORO-TIBIAL ARTICULATION. 

No. 1. Posterior face; the posterior ligament has been removed.—1, External menis- 
cus; 2, Fibrous tasciculi fixing it to the femur; 3, Fibrous fascia which attaches 
it to the posterior contour of the tibial surface; 4, Internal meniscus; 5, Tibial 
insertion of the posterior crucial ligament; 6, External lateral ligament; 7, 

_ Internal lateral ligament, 

No. 2. External face: the external condyle of the femur and the meniscus have been 
removed to show the crucial ligaments,—1, Anterior crucial ligament ; 2, Posterior 
ditto ; 3, Fibular insertion of the external lateral ligament; 4, Anterior patellar 
ligaments.—a, Internal meniscus ; B, Anterior insertion of the external meniscus ; 
C, Passage for the tendinous cord common to the flexor of the metatarsus and the 
anterior extensor of the phalanges; p, Anterior and superior tuberosity of the 
tibia; 5, Tibial crest. 


The external border of this meniscus is separated from the external lateral 
ligament by the tendon of the popliteus muscle, and acts, with regard to this 
tendon, as a pulley. 

Mode of union.—The bands which bind this complicated articulation are 
very numerous. They will be successively described as: 1, Those which 
attach the patella to the tibia ; 2, Those which unite the femur with the tibia. 

A. Ligaments attaching the patella to the tébia.—The patella is bound to 
the tibia by three funicular ligaments, designated by the generic epithet of 
“patellar.” They are situated in front of the articulation, and are charged 


ARTICULATIONS OF THE POSTERIOR LIMBS. 165 


with the duty of transmitting to the leg the action of the muscles which are 
attached to the patella. They are distinguished according to their position 

as external, internal, and middle. (Fig, 92, 2, 3, 4.) ; 
_ a The external patellar ligament, the largest and most powerful, is a 
flattened band, attached, by its lower extremity, to the culminating point of 
the anterior tuberosity of the tibia. Its upper extremity is fixed to the 
anterior face of the patella, and is confounded with the patellar insertion of 
the long vastus muscle. It is joined to the internal ligament by a very 
resisting aponeurotic expansion, a dependency of the fascia lata. 

b. The internal patellar ligament also furms a flattened band, longer, but 
not so wide or thick as the preceding. Its inferior extremity is attached to 
the inner side of the anterior tuberosity of the tibia. Its superior extremity 
becomes much thickened and fibro-cartilaginous, and is inserted into a 
prominence inside the patella. This fibro-cartilaginous portion (Fig. 92, 3’) 
of the ligament glides on the internal border of the femoral trochlea, and 
may justly be considered as a complementary apparatus of the patellar 
surface. The ligament, joined to the preceding by the fibrous fascia already 
mentioned, is mixed up, inwardly, with the aponeurosis of the adductor 
muscles of the leg. 

e. The middle patellar ligament is a round cord, situated, as its name 
indicates, between the other two, concealed beneath the aponeurosis which 
unites these, and in the middle of the adipose tissue protecting the synovial 
capsules in front. It leaves the anterior face of the patella, and descends 
vertically to the tibia, to be lodged in the fossa in the middle of the anterior 
tuberosity, where a small synovial bursa facilitates its movements. 
Tts inferior extremity is inserted into the most declivitous part of this 
excavation. 

B. Ligaments which attach the thigh and leg bones.—These are six in 
number: 1, A femoro-patellar capsule maintaining the patella against the 
femoral trochlea ; 2, Five femoro-tibial ligaments, as follows: two lateral, 
faxe-external and internal; a posterior; and two interarticular, distinguished 
with reference to their inferior insertion into anterior and posterior. 

a. The femoro-patellar capsule is a membranous expansion which covers, 
above and laterally, the superior synovial membrane. This capsule is 
attached by its borders around the femoral trochlea and the periphery of the 
patellar surface. It is extremely thin in its superior part; but laterally it 
is thicker, and constitutes two wide fibrous fasciculi which bind the patella 
to the eccentric sides of the two condyles, and is described in several works 
as two special ligaments. Its external face is covered by the insertion of 
the long vastus and the crural triceps. 

b. The lateral ligaments are two ribbon-shaped cords situated at the 
extremities of the transversal axis of the articulation, more behind than 
before ; they are relaxed during flexion, and very tense in extension. 

The eaternal, the shortest and strongest, proceeds from one of the hollow 
facets on the external condyle of the femur, and is inserted into the head of 
the fibula by its inferior extremity, after gliding over the external tuberosity 
of the tibia by means of a special synovial bursa. It is covered by the 
crural or tibial aponeurosis, and covers the tendon of the popliteus, from 
which it is sometimes separated by a vesicular synovial membrane. 

The internal is attached, superiorly, to the eminence of insertion that 
surmounts the eccentric face of the internal condyle, and descends vertically 
to the tibia, gliding over the margin of its articular surface by means of a 
small facet covered with cartilage, and a cul-de-sac prolongation of the 

14 


166 THE ARTICULATIONS. 


internal synovial membrane. It is fixed by its inferior extremity to the 
imprints which cover the internal tibial tuberosity. : I 

Its fibres are disposed in two layers, which slightly intercross in X fashion ; 
those passing downwards and forwards adhere to the border of the internal 
meniscus. Covered by the aponeurosis of the adductor muscles of the leg, 
this ligament adheres by its deep face to the internal meniscus. 

c. The posterior ligament belongs to the class of membranous or capsular 
ligaments. It is formed of two aponeurotic lamine separated superiorly, 
but confounded inferiorly. The superficial lamina is composed of strong, 
fibrous, intercrossed fasciculi, perforated with vascular openings. It is fixed, 
above, to the posterior face of the femur, below the external gastrocnemius 
muscle. The deep lamina envelopes, like a cap, the femoral condyles. 
After becoming united, these two lamine are attached to the posterior face 
of the tibia, close to the superior articular face of that bone. Its external 
face is in contact with the pofliteal vessels, and the external gastrocnemius 
muscle. Its internal face is covered throughout nearly the whole of its extent 
by the lateral synovial membranes, embraces the condyles of the femur, and 
adheres to the posterior crucial ligament, as well as to the interarticular 
meniscil. 

d. The interosseous ligaments are two funicular bands lodged in the inter- 
condyloid notch. They are more commonly designated crucial ligaments, 
because they cross each other at their middle part, like the letter X, 

Fig. 91. 

: he an oblique downwards and forwards, is attached by its superior 
extremity to the bottom of the intercondyloid notch, and inwardly to the 
external condyle. Its inferior extremity is fixed in the groove on the summit 
of the tibial spine. The fibres entering into its formation are not parallel, 
but slightly twisted in a’spiral manner. 

The posterior, longer than the preceding, and oblique in the opposite 
direction, is inserted, inferiorly, into the little eminence behind the internal 
tibial facet ; whence it goes to the bottom of the intercondyloid notch, to be 
attached by its superior extremity within the internal condyle. 

Synovial membranes.—For this articulation there are three synovial 
membranes: a superior and two lateral. The first, very large and sustained 
by the femoro-patellar capsule, facilitates the gliding of the patella on the 
femoral pulley; it is prolonged in a cul-de-sac below the insertion of the 
crural triceps. The other two, which lubricate the articular surfaces of the 
proper femoro-tibial joint, include the crucial ligaments between them, and 
cover the posterior hyament, the lateral ligaments, and the fibrous fasciculi 
for the attachment of the meniscii. The external covers, in addition, the 
tendon of the popliteus muscle, and furnishes a vast cul-de-sac which descends 
in the anterior groove of the tibia to envelop the tendon common to the 
anterior extensor of the phalanges and the flexor of the metatarsus. These 
two femoro-tibial synovial membranes le against that of the femoro-patellar 
articulation, in front of the condyles and the notch which separates them, 
and if not always, at least not unfrequently, they communicate with it. The 
three are separated from the ligaments of the patella by a considerable mass 
of adipose tissue which is prolonged into the intercondyloid notch, at the 
bottom of which it appears to be fixed. 

Movements.—This imperfect hinge joint can execute the two principal and 
opposite movements of flewion and extension, and a somewhat limited acces- 
sory movement of rotation. The mechanism of these movements being 
simple enough to be readily understood without any preliminary explanation, 


ARTICULATIONS OF THE POSTERIOR LIMBS. 


167 


they will not be detailed here; but some remarks will be made with regard 
to the displacement the fibro-cartilages undergo when the articulation is in 


motion. 


During fleaion and extension, these bodies, fixed on the tibial facets, which 


they transform into glenoid cavities, 
move with them on the condyles of the 
femur, from before to behind, or behind 
to before, according to the movement 
executed. But at the same time they 
also glide in an inverse direction, and 
to a very appreciable degree, on the 
superior extremity of the tibia. There- 
fore, during flexion, they pass from 
behind forward on this extremity, and 
are drawn backwards during exten- 
sion. 

Tn rotation, which may take place 
from within to without, or from with- 
out to within, the movement is pro- 
duced not only by the pivoting of the 
condyles in their glenoid cavities, but 
also by a sensible displacement of the 
meniscii on the tibial surfaces. 


In the Dog and Cat, the meniscii are 
joined together near their anterior insertion 
y a transverse fibrous band. There is only 
one patellar ligament, and the posterior liga- 
meut shows in its thickness two small sesa- 
moid bones against which the condyles of 
the femur play inwardly, and which give 
attachment, outwardly, to the originating 
branches of the external gastrocnemius mus- 
cle. There isno femoro-patellar capsule, and 
only one synovial membrane for the whole 
articulation. 

In the Pig and Sheep, there is also only 
one ligament and one synovial capsule. 


4, Tibio-fibular Articulation. 


This articulation represents a small 
planiform diarthrosis, whose move- 
ments are very limited and obscure. 
It is formed by the union of the irre- 
gular diarthrodial facet which occupies 
the internal face of the head of the 
fibula, with the analogous facet on the 
external superior tuberosity of the 
tibia. Short and strong interosseous 
or peripheral fibres envelop these 
facets on every side, and maintain them 
firmly in contact. 


LIGAMENTS ATTACHING THE THREE BONES 
OF THE LEG, 


No. 1. Posterior face.—No. 2. Anterior face. 
—1, Complementary fibro-cartilaginous 
pad of the patellar surface; 2, External 
patellar ligament ; 2’, Insertion of the long 
vastus into this ligament; 3, Internal 
patellar ligament; 3’, Its upper insertion 
transformed into a complementary appa- 
ratus of the patellar surface; 4, Middle 
patellar ligament, 5, External meniscus 
of the tibia; 6, Its branch of insertion 
into the femur cut off at its origin: 7, Its 
posterior tibial insertion; 8, External me- 
niscuss 9, Insertion of the anterior crucial 
ligament into the fossa of the tibial spine; 
10, Tibial insertion of the posterior crucial 
ligament; 11, Inferior insertion of the ex- 
ternal femoro-tibial ligament; 12, 13, 14, 
Tibio-fibular ligaments.—a, Tibial arch; 
3B, Surface of insertion of the popliteus 
muscle; C, Surface of insertion for the 
perforans muscle. 


The fibula is also attached to the tibia: “1, Above, by two small liga- 
mentous fasciculi crossed like the letter X, which form the superior part of 
the great arch through which pass the anterior tibial artery and vein (Fig. 
92,12); 2, In the middle, by a kind of aponeurotic membrane, whose width 


168 THE ARTICULATIONS. 


diminishes from above to below, like that of the space it fills (Fig. 92, 13); 
8, Below, by a ligamentous cord (Fig. 92, 14) which prolongs the fibula to 
the external tuberosity of the inferior extremity of the tibia, where this cord 
bifurcates, and is united to the two external lateral ligaments of the tibio- 
tarsal articulation.” —Rigot. 


In the Or, Sheep, and Goat, the fibula being replaced by a ligament, there is no 
proper tibio-fibular articulation. ‘ 

In the Dog and Cat, the two principal bones of the leg are united at their extremities 
and middle part: 

1. At their superior extremity, by means of a small arthrodial articulation, analogous 
to that of the Horse, and, like it, provided with a particular synovial bursa ; 

2. At their inferior extremity, by means of a second arthrodial articulation, whose 
action is facilitated by a prolongation of the tibio-tarsal synovial membrane ; 

3. By their middle part, through the interposition, between the two bones, of an 
interosseous ligament, which is wide and membranous in its upper two-thirds, and formed 
of extremely short and strong fibres at its lower third. 

In the Pig, the arrangement is somewhat the same as in Carnivora. It may be noted, 
however, that the facet of the upper extremity of the fibula is joined to the tibia by a 
small interosseous ligament, and that the articulation which results should be looked 
upon as a small amphiarthrosis. 

In Man, as in the Dog there are two peroneo-tibial arthrodiz : a superior and inferior. 


5. Articulations of the Tarsus or Hock, 


(Preparation—Remoye the tendons from around the articulation, and incise, layer 
after layer, the superficial fibres of the lateral ligaments.) 


These comprise: 1, The tibio-tarsal articulation; 2, The articulation of 
the first row of bones—the astragalus and calcis ; 3, Those which unite the 
bones of the lower row; 4, The articulation of the two rows with each 
other ; 5, The tarso-metatarsal articulation. The first is a perfect gingly- 
moid, and the only joint really movable; all the others are arthrodial, and 
their action is so restricted that they appear to be condemned to almost 
absolute immobility. This intimate union of the tarsal and metatarsal 
bones is evidently chiefly intended to guarantee precision in the movements 
of the tibio-tarsal articulation. 

Trp10-rarsaL ARTICULATION.—T wo bones alone concur in the formation 
of this angular ginglymoid joint : these are the tibia and astragalus. 

Articular surfaces—For the tibia: 1, The two deep grooves, oblique 
forwards and outwards, channeled in the inferior extremity of the bone; 2, 
The salient tenon which separates these grooves, and on which there is often 
a small synovial fossctte.—For the astragalus, the pulley occupying its 
anterior face (see page 103). 

Mode of union.—Seven ligaments bind these articulations: two external 
lateral, three internal lateral, an anterior and a posterior. 

a. External lateral ligaments.—These are distinguished, according to their 
relative position, into superficial and deep. 

The external superficial ligament (Figs. 98, 2; 94, 2), is a thick 
funicular cord, flattened in its inferior half. It commences above on the 
external tuberosity of the tibia, behind the groove which divides this tube- 
rosity into two parts; from thence it descends almost vertically, fixing itself 
successively to the astragalus, calcaneus, cuboides, middle metatarsal bone, 
and the external rudimentary metatarsal bone. Passing in front with, and 
partly covered by, the lateral extensor of the phalanges, to which it 
supplies a retaining band (Fig. 94, 2), this ligament is confounded behind, 
and near its inferior extremity, with the calcaneo-metatarsal ligament. It 


ARTICULATIONS OF THE POSTERIOR LIMRS. 


169 


covers the external and deep ligament, the short band which constitutes the 
external calcanco-astragaloid ligament, the insertion of one of the branches 


of the flexor of the metatarsus, and the small cuboido-cunean 


ligament. 


(cuneiform) 


The external deep ligament (Figs. 93; 94, 1), much shorter than the 


preceding, is attached, superiorly, to the anterior part 
of the external tuberosity of the tibia, and is directed 
obliquely backwards and downwards, to be fixed by 
two fasciculi at the external side of the astragalus 
and calcis. This ligament, covered by the preceding, 
which crosses it like an X, is lined on its inner face 
by the synovial membrane of the articulation. 

b. Internal lateral ligaments.—These are algo three 
funicular bands superposed on one another, and are 
oy designated as superficial, middle, and 

eep. 

The internal superficial ligament (Fig. 98, 6), the 
strongest and longest of the three, proceeds trom 
the internal and inferior tuberosity of the tibia, 
diminishing as it descends on the inner side of the 
tarsus. It is fixed, in mixing with the astragalo- 
metatarsal ligament and with the posterior tarso- 
metatarsal ligamentous arrangement, to the tuberosity 
of the astragalus, the scaphoid, the two cuneiform, the 
superior extremity of the principal metatarsal, and 
that of the internal rudimentary metatarsal bones. 

The internal middle ligament (Fig. 93, 5) is com- 
posed of two funicular cords, attached in common 
beneath the preceding ligament to the internal tibial 
tuberosity. These two fasciculi, exactly resembling 
those of the external deep ligament, are directed 
downward and backward, and terminate, one at the 
astragalus, the other at the calcis. 

The internal deep ligament (Fig. 93, 4) is an ex- 
tremely slender fasciculus, enveloped by the synovial 
membrane; it is often reduced to a thin shred, 
scarcely distinct from the serous covering surround- 
ing it. It is attached, in one direction, to the tibia 
below the middle ligament; in the other to the 
astragalus, and nearly at the same point as the 
superior fasciculus of the middle ligament. 


Fig. 93. 


TARSAL ARTICULATIONS; 
RONT VIEW. 


1, External deep ligament 
of the tibio-tarsal ar- 
ticulation; 2, 2, Ex- 
ternal superficial liga- 
ment; 4, Internal deep 
ligament; 5, Internal 
middle ligament; 6, In- 
ternal superficial liga- 
ment; 7, Astragalo- 
metatarsal ligament; 8, 
Small cuboido-cunean 
ligament.—a, Pulley of 
the astragalus; B, Cu- 
boidal insertion belong- 
ing tothe tendinous cord 
of the flexor of the me- 
tatarsus; ©, Vascular 
canal of the tarsus. 


ce. Anterior ligament.—This is a membraniform band formed of inter- 


crossed fibres, stronger outwards than inwards, attached by its upper border 
above and in front of the tibial surface, fixed by its inferior border to the 
astragalus, the scaphoid and great cuneiform bones, and the astragalo- 
metatarsal ligament; it is confounded at its sides with the two superficial 
lateral ligaments. Its internal face is lined by articular synovial mem- 
brane, while the external is covered by the flexor of the metatarsus, the 
anterior extensor of the phalanges, the anterior tibial artery, and several 
large anastomosing veins from whose junction arises the anterior tibial 
vein. 

d. Posterior ligament.—This is the second membraniform or capsular 
band which protects the articulation posteriorly, It presents, in its centre, 


170 THE ARTICULATIONS. 


a fibro-cartilaginous thickening, on which glides the perforans tendon. Tt 
is attached, above, to the tibia, below, to the astragalus and calcis; at its sides 
it is mixed with the two superficial lateral ligaments, and the astragalian 
fasciculus of the middle internal ligament. Its internal face is lined b 
articular synovial membrane; the external is covered and lubricated by the 
vaginal serous membrane which facilitates the gliding of the perforans 
tendon in the tarsal sheath. 

Synovial membrane.— This membrane is developed at the internal face 
of the two capsular ligaments, nearly covers the three internal ligaments, 
and lines the external deep ligament. It communicates, in front and below, 
with the synovial membrane proper to the articulation of the two rows of 
tarsal bones. When it becomes the seat of dropsical effusion, it is always 
distended forwards and inwards, because it is only sustained at that place 
by the anterior capsular ligament. But the effusion may also raise the 
posterior ligament and produce hernia in the hollow of the hock, behind the 
lateral ligaments. It is not, therefore, absolutely correct to attribute all the 
synovial tumours in the hollow of the hock to dilatation of the tarsal 
tendinous sheath. 

Movements.—Nothing can be less complicated than the mechanism of the 
tibio-tarsal articulation ; this joint only permitting two opposite movements, 
those of flewion and extension, which are so simple and precise that we may 
dispense with a description of the manner in which they are executed. It 
may only be remarked that, in order to prevent contact between the leg 
and foot during flexion, the latter fraction of the limb deviates a little 
outwards, owing to the marked obliquity of the articular grooves. 

ARTICULATION OF THE Bones oF THE First Row, orn CAatoanzo- 
ASTRAGALOID ARTICULATION.—This is a compound arthrodial joint, resulting 
from the coaptation of the three or four articular facets of the posterior face 
of the astragalus with the analogous facets of the calcis, 

This joint is maintained by the lateral ligaments of the tibio-tarsal 
articulation, and by four calcaneo-astragaloid ligaments—a superior, external, 
internal, and the last interosseous. 

The superior calcanco-astragaloid ligament is formed of short parallel 
fibres thrown across from one bone to the other, and is situated towards the 
superior extremity of the pulley of the astragalus; it is lined superiorly by 
the synovial membrane of the tibio-tarsal articulation. 

The lateral ligaments are two very thin fasciculi concealed by the 
ligaments which bind, laterally, the tibia to the tarsal bone. 

The interosseous ligament is very strong, and occupies a great portion of 
the rugged excavation which separates the articular facets. 

This articulation does not usually possess proper synovial capsules. 
Two prolongations of the synovial membrane of the two rows, in ascending 
between the calcis and astragalus, facilitate the gliding of the two inferior 
facets. An analogous prolongation of the tibio-tarsal synovial membrane is 
effected for the superior facets, and it is not rare to find this prolongation 
form a distinct capsule. 

Movements nearly null 

ARTICULATION OF THE Bonus oF THE SxconD Row wIta EACH OTHER.— 
These bones, four in number, are brought into contact in the following 
manner :—The cuboides responds to the scaphoid by two facets, one anterior, 
the other posterior ; it articulates with the great cuneiform by two similar 
facets, the posterior of which is not always present. The scaphoid is united 
to the two cuneiforms by the large convex facet occupying its entire lower 


ARTICULATIONS OF THE POSTERIOR LIMBS. 71 


face. 
surface. 


The two cuneiforms are joined by means of a small articular 


The fibrous fasciculi which maintain the diarthrodial surfaces in contact 


are somewhat numerous. They are as follows: 


1. The astragalo-metatarsal ligament and tarso-metatarsal apparatus, 
which will be described hereafter ; these two bands do not properly belong 


to the articulations of the second row of bones. 


_2. Two anterior ligaments, named cuboido-scaphoid and cuboido-cunean 
(Figs. 93, 8; 94,5), which are carried from the cuboid to the scaphoid 


and to the great cuneiform bone, one above, 
the other below the vascular channel formed 
between these three bones. 

3. Two interosseous ligaments analogous 
to the preceding two, forming the superior and 
inferior walls of the aforesaid channel. 

4, An interosseous scaphoido-cunean liga- 
ment, passing from the scaphoid to the two 
cuneiform bones. 

5. An interosseous ligament, named the 
intercunean, is directed from one cuneiform 
bone to the other, and is confounded with the 
. preceding ligament. 

The disposition of the lubricating mem- 
branes varies with that of the articular facets. 
The following is what is most generally 
observed :—A proper synovial membrane is 
specially destined for the facets by which the 
scaphoid and great cuneiform bones correspond ; 
this synovial membrane belongs also to the two 
cuboido-scaphoid and posterior cuboido-cunean 
artkrodie. The anterior cuboido-scaphoid diar- 
throsis receives a prolongation from the syno- 
vial membrane of the two rows. The play of 
the anterior cuboido-cunean and intercunean 
facets is facilitated by two prolongations of 
the tarso-metatarsal synovial membrane. 

Movements almost null. 

ARTICULATION OF THE Two Rows WITH EACH 
oTHER.—This arthrodial joint is formed by the 
union of the calcis and the astragalus, on the 
one side, with the scaphoid and cuboid bones 
on the other. Its solidity is assured by six 
principal bands: 

1. The two lateral superficial ligaments of 
the tibio-tarsal articulation. . 

2. The calcaneo-metatarsal ligament (Fig. 
94, 3), a strong fibrous brace which unites the 


ARTICULATIONS OF THE TARSUS$ 


LATERAL VIEW. 


1, External deep ligament; 2, 


External superficial ligament ; 
2', Ring furnished by the latter 
ligament for the passage of the 
lateral extensor tendon of the 
phalanges; 3, Calcaneo-meta- 
tarsal ligament; 4, Astragalo- 
metatarsal ligament; 5, Small 
cuboido-cunean ligament.—a, 
Cuboidal insertion of the flexor 
muscle of the metatarsus; B, 
Anterior orifice of the vascular 
conduit of the tarsus; Cc, Groove 
on the external tuberosity of 
the tibia for the gliding of the 
lateral extensor of the pha- 
langes; D, Insertion of the gas- 
trocnemius tendon of the leg 
into the os calcis; E, Gliding 
surface for that tendon, 


posterior border of the calcis to the cuboides, and to the head of the external 


rudimentary metatarsal bone. 


It is confounded, outwardly, with the external 


and superficial tibio-tarsal ligament; inwardly, with the posterior tarso- 


metatarsal band. 


3. The astragalo-metatarsal ligament (Fig. 98, 7), a radiating fasciculus 
whose fibres leave the internal tuberosity of the astragalus, become mixed 


172 THE ARTICULATIONS. 


up with the internal and superficial tibio-tarsal ligaments in diverging down- 
wards to the scaphoides, the great cuneiform bone, and the upper extremity 
of the principal metatarsal bone. ; 

4. The posterior tarso-metatarsal ligament is a vast, very strong, and very 
complicated fibrous arrangement, which binds, posteriorly, all the tarsal 
bones, and also fixes them to the three portions of the metatarsus. This 
band, which is crossed by several tendons and by the artery and vein lodged 
in the cuboido-scaphoido-cunean canal, is continued below by the tarsal 
stay of the perforans tendon. It therefore closely resembles the posterior 
carpal ligament. Its posterior face is covered by the tendinous synovial 
membrane lining the tarsal sheath for the passage of the perforans tendons. 
It is confounded, on its sides, with the calcaneo-metutarsal, and the internal 
and superficial tibio-tarsal ligaments. 

5. An interosseous ligament, attached to the four bones composing this 
articulation. 

It is provided with a particular synovial membrane which always 
communicates, in front, with the tibio-tarsal capsule. This membrane is 
prolonged, superiorly, between the calcis and astragalus, to lubrify two of 
the facets by which these bones come into contact; and, in addition, it 
descends between the cuboid and scaphoid bones to form a third pro- 
longation for the anterior cuboido-scaphoid arthrodia. 

Movements almost null. 

TaRsO-METATARSAL ARTICULATION.—This joint, formed by the meeting of 
the three tarsal bones—the cuboid and the two cuneiforms—with the three 
bones of the metatarsus, is fixed by the lateral superficial ligaments of the 
tibio-tarsal articulation, the calcaneo-metatarsal ligament, those which have 
been named the astragalo-metatarsal and tarso-metatarsal, and by a strong 
interosseous ligament which naturally forms three fasciculi. 

The synovial membrane proper to this joint ascends into the small 
anterior cuboido-cunean arthrodia, and into that which unites the two 
cuneiform bones; it descends to the intermetatarsal articulations. 

Movements nearly null. 

Tn all the domesticated animals except Solipeds, the tarsal articulations offer some diffe- 
rential peculiarities whose study is without interest, as it is without utility. It is only 
necessary to remark that the immobility of the tarsal joints, properly called, is less 
absolute than in Solipeds, owing to the peculiar configuration of the articular surfaces of 
some of the bones composing them. ‘T’hus, in the Ox, Sheep, Goat, and Pig, the calcis 
is joined to the astragalus by a real trochlear articulation, and the latter bone is united 
to the seaphoid by a diarthrodial joint of the same kind; a mode of articulation much 
more favourable to motion than that of the planiform diarthrodial joint. In the Dog and 
Cat, the same result is obtained by the reception of the head of the astragalus into the 
superior cavity of\the scaphoids. 

In Ruminants and the Pig, it is also observed that the tibio-tarsal articulation is 
re o the tibia and fibula in the one direction, and by the astragalus and os calcis 
1n e other, 


* 


CHAPTER III. 


OF THE ARTICULATIONS IN BIRDS. 


Tue study of the articulations in birds will only arrest us for a few moments, as it 
will be confined to some remarks on the intervertebral occipito-atloid and temporo- 
maxillary joints, the only ones exhibiting a special conformation worthy of attention. 
Intervertebral articulations —The great mobility of the neck of birds is not only due 
to the fact of its length, relatively considered, but also to the peculiar manner in which 
the vertebre of this portion of the spinal stalk are articulated. It will be remarked that 


ARTICULATIONS IN BIRDS. 173 


these do not unite by their bodies in the form of a continuous series of amphiarthroses 
as in the domesticated mammals; but that instead of these mixed articulations there are 
veritable diarthroses, which may be included in the class created by Cruveilhier under 
the title of articulation by reciprocal ball and socket, each vertebra becoming counected 
with the adjacent vertebrae by means of facets convex in one sense and concave in the 
sense perpendicular to the first. These facets are manifestly covered by curtilage of 
incrustation ; and it appears that, instead of their being applied directly against the 
opposite facets, which present a precisely inverse conformation, they are separated by 
an extremely thin fibro-curtilaginous disc, which resembles the interosseous meniscus of 
the temporo-maxillary articulation in the Carnivora of the Cat specics. Two loose 
synovial capsules, separated by this interarticular lamina, complete the framework of 
each articulation, and favour the play of the vertebrae on one another. This arrange- 
ment has only, so far as we are aware, been observed in the swan, and that very 
imperfectly; but it probably belongs tu the entire class of birds, for until now we have 
met with it in all the individuals submitted to examination. 

In its dorso-lumbar and sacral portion, the spine is w single piece, in consequence of 
the consolidation of the vertebree, und does not show any proper articulations. 

In the coccygeal region, the mobility of the spine re-appears; but it is far from being 
so marked as in the cervical region ; the vertebrae here are united by amphiarthrosis, and 
not by reciprocal ball and socket. 

Occipito-atloid articulation.—It has been shown that there is only one more or less 
spheroidal condyle of the occipital bone, and a single cavity on the anterior margin of 
the spinal canal of the atlas. The occipito-atloid articulation is therefore a true enar- 
throsis, with varied and very extensive movements; w disposition which accounts for 
the facility with which birds can pivot their heads on the superior extremity of the 
vertebral stalk. 

Lemporo-maxillary articulation.—The play of this articulation offers one peculiarity 
in that it causes, during the separation of the mandibles, not only the depression of the 
inferior, but also the elevation of the superior mandible. The arrangement which permits 
this movement hus been already made known; but yet it is ditticult to understand, be- 
cause there is no active agent, no proper muscle to directly effect it. Nevertheless, the 
mechanism which executes it is most simple, and may be given in a few words: Tlius, 
we know that the square bone, interposed between the temporal and maxillary bones, 
like the interarticular meniscus of mammals, is united outwardly with the jugal bone, 
and inwardly with the pterygoid. We know also that the latter rests, by means of a 
diarthrodial tacet, on the body of the sphenoid, and that it abuts against the posterior 
extremity of the palate bones; while the first, the zygomaticus, is joined directly 
to the supermaxiJlary bone. The superior jaw, it is also known, is movable on 
the cranium, because of the flexibility of the cartilages or bony plates uniting these two 
portions of the head. It may then be added, that the square bone receives on its auterior 
process one or two small muscles which are attached to the base of the cranium, and that 
these bones may be pushed, or rather drawn forward, by tle contraction of these muscular 
fasciculi. It is this projecting, or pushing, transmitted to tle upper mandible through 
the medium of the jugal bone on the one side, and the pterygoid bone on the other, that 
produces the elevation of that mandible. 

Nothing is easier than to prove it; it is only necessary to take the head of a bird, 
denude it of all its soft parts, and press with the fingers behind the two square bones, 
to imitate the action of the elevator muscles; we then see the internal extremity of the 
pterygoid bone glide on the facet of the sphenoid, and push before it the palatine bone, 
during which the zygomatic bone acts in the same manner on the maxillary; and in this 
way is produced, through the influence of this postero-anterior propulsion, the ascending 
movement we undertook to explain, 


THIRD SECTION. 


Tue MuscLEs. 


Arver the study of the bony levers and their articulations, comes the 
description of the agents whose function it is to move them. These are the 
muscles, fibrous organs possessing the property of contracting under the 
influence of a stimulus. 


174 THE MUSCLES. 


They are distinguished as striated (or striped) and non-striated (or 
unstriped) muscles, according to the character of the anatomical element 
composing them. ’ 

The non-striated (or unstriped) muscles are removed from the influence of 
the will, and belong to the organs of vegetative life. They are also 
designated as internal muscles, or muscles of organic life. 

The striated (or striped) muscles, differ from the first in that, with the 
exception of the fleshy tissue of the heart, their contractile power is 
immediately placed under the influence of the will, They are more 
particularly concerned in the execution of the functions of relation, 
which causes them to be named the external muscles, or muscles of animal 
life. These muscles are nearly all attached to the skeleton, and represent 
the active agents in the movements of the osseous framework; they will, 
therefore, be the only ones referred to in this place, in studying the 
locomotory apparatus. 

But before entering upon the particular description of each muscle, we 
will allude to the general considerations relative to their history. 


CHAPTER I. 
GENERAL CONSIDERATIONS ON THE STRIATED MUSCLES, 


THE STRIATED MUSCLES IN GENERAL. 


In this first paragraph, we will survey in a general manner the volume, 
situation, form, direction, attachments, relations, and names of the muscles 
belonging to the locomotory apparatus. 

A. Votumn.—Nothing is more variable than the respective volume of 
the external muscles. What a difference there is, for example, between the 
small scapulo-humeral muscle and the long vastus or ilio-spinalis (longissimus 
dorsi)! and what a number of intermediate sizes between these three points 
of comparison! There are consequently very great, great, medium, small, 
and very small muscles. 

The weight of the total mass of these organs varies according to the. 
species, age, sex, and state of health; but taking a general average, it will 
be found that it represents nearly one-half the entire weight of the body. 

B. Srrvation.—There is no need to insist upon the fact, that a knowledge 
of the situation of the muscles is one of the first objects to be acquired with 
regard to their disposition. 

They may, like the bones, be described in two ways. 

1. In relation to the median plane of the body, from whence their division 
into pairs and single muscles. The last, very few in number, are far from 
exhibiting the symmetry which exists in the bones of this division, as may 
be seen in the diaphragm, 

2. In relation to the other organs, such as the bones and surrounding 
muscles. 

C. Form.—With regard to their absolute form, the muscles, again, like 
the bones, are classed as long, wide, and short. 

Long muscles.—These muscles are more particularly met with in the 
limbs. Provided with a principal axis, to which we may ascribe the effect 
of their contraction, they present a middle portion—usually protuberant, and 


GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 175 


two extremities of unequal thickness; the most voluminous, always turned 
upwards, is metaphorically designated the head, the other the tail. They 
are most frequently fusiform, sometimes conical, but rarely cylindrical, 
prismatic or flattened into thin bands, 

“There is a particular kind of long muscles which have no analogy with 
those of the extremities, except in their external appearance. They are 
those which lie below, but more particularly above, the spine. Although 
at the first glance they appear simple, yet they present as many distinct 
fasciculi as there are vertebre. The transverse spinous (spinalis dorsi), etc., 
is no doubt an elongated fasciculus like the sartorious, etc., but the structure 
of this fasciculus has nothing in common with that of the latter muscle : 
it is a series of small fasciculi which have each their distinct origin and 
termination, and only appear as a single muscle because they are in juxta- 
position.” —Bichat, ‘ Anatomie Générale.’ 

Wide muscles—Wide muscles are those which have two principal 
axes, and are stretched beneath the skin, or around the great cavities of the 
trunk, which they concur in inclosing and separating from one another. 
They are elliptical, quadrilateral, triangular, trapezoid, etc. 

Short muscles.—These are found chiefly around the short bones, or at 
the periphery of the articulations which are deeply buried under enormous 
muscular masses. Although their name indicates that their three axes offer 
nearly the same dimensions, yet there is most frequently one, and even two, 
which predominate. They may therefore be assimilated, in this respect, to 
the long or wide muscles. 

D. Drrection.—Cruveilhier has justly remarked, that the direction 
of a muscle is one of the most important features in its history; for 
it allows the determination of the angle of incidence of the muscle on 
its arm of the lever, the power of its action, and the nature of its uses. 

With regard to the direction of the muscles, we may observe: 1, The 
form of their principal axis; 2, The relation of this axis to the plumb- 
line; 3, Its comparison with the axis of the bony levers which the muscles 
surround or move. 

a. A muscle is termed rectilinear when its principal axis is straight; 
it is curvilinear, or circular, if this axis describes a curve more or less 
marked; it becomes inflected when it proceeds in a certain direction, and 
afterwards turns on a bony or cartilaginous pulley in another direction : 
that is to say, when its principal axis is broken into several lines. If the 
muscle offers two axes, it will be flat or concave, these being one or the 
other, or straight or curvilinear. : 

b. With regard to the direction of the muscles to that of the plumb-line, 
itis either vertical, horizontal, or oblique, expressions which carry their own 
definition and require no explanation. 

c. If the direction of the muscles be compared with that of the bony 
levers they surround and move, it will be found that they are either parallel 
to these levers, or form with them angles more or less acute. The proper 
direction of the bones being known, it is sufficient to indicate that of the 
‘inuscles to clearly establish this comparison. For instance, in saying that 
the majority of the muscles of the shoulder are oblique from above to below, 
and from before to behind, it is understood that these muscles are parallel 
to the scapula, and that their incidence on the humerus takes place at a 
right angle. Gre ¢ 

BE. Arracunents on Insurtions.—This is undoubtedly the most essential 
part of the study of the muscles; for with the knowledge of their insertions 


176 THE MUSCLES. 


we may determine their extent and direction, and even their relations and 
uses. 

By the term attachment, fied insertion, or origin, is meant the point of 
the muscle which most usually remains fixed while that organ contracts; 
the attachment, movable insertion, or termination is the name given to that 
portion which corresponds to the lever displaced by the muscular contraction. 
Muscles are frequently met with whose two insertions are alternately fixed 
or movable ; and in such cases care is taken not to give these insertions one 
or other of the designations. 

The fixed insertion is often confounded with that of other muscles; the 
movable insertion is generally free and independent. 

. The muscles are sometimes directly attached to the bones by the ex- 
tremities of their fleshy fibres; but most frequently they are fixed to these 
inert levers through the medium of a tendon or an aponeurosis, whose 
volume is less considerable than that of the fibres, Without this latter 
disposition, the surface of the skeleton would not have been sufficiently 
extensive to give insertion to all the external muscles. 

The attachment of the muscles to the bony levers is effected by a 
kind of fusion between the fleshy or tendinous fibres, and the periosteum. 

F. Revattons.—The indication of the relations of the muscles completes 
the idea of their situation, and is of great importance in a surgical point 
of view. They should, therefore, be studied with all the precision 
possible. 

The muscles entertain relations either with the skin, the bones, other 
muscles, or with vessels and nerves. 

a. It is only, properly speaking, the subcutaneous muscles, such as the 
panniculus carnosus and the muscles of the face, which are really in im- 
mediate contact with the skin. The others are separated from it by the 
aponeurotic fascia which will be described as the appendices of the muscular 
system. 

. b. The superficial muscles are only related to the bones by their ex- 
tremities. Those which are deeply situated are immediately applied by 
their bodies against the bones of the skeleton. 

c. The muscles are related to each other in a more or less intimate 
manner. Sometimes they adhere closely to one another; and at other times 
they are separated by interstices filled with fat or cellular tissue, and 
generally traversed by vessels and nerves. 

d. The connections of the muscles with the latter organs sometimes 
assume a remarkable character; this is when one of them accompanies, 
like a satellite, the vascular and nervous trunks concealed beneath its deep 
facc. There is in this circumstance an important fact with regard to 
surgical anatomy. 

G. Nomenciaturr.—Before the time of Sylvius, the muscles had not 
received particular names. Since the days of Galen they had been dis- 
tinguished by the numerical epithets of first, second, third, etc., to indicate 
their place and their order of superposition in the regions to which they, 
belonged. It is in this fashion that they are designated in the Italian work 
on the Anatomy of the Horse by Ruini. 

Sylvius was the first to give Lhe muscles real names; and his example 
being followed by succeeding rnthropotomists, the nomenclature of these 
organs was soon completed. But no general view, no methodic spirit guided 
Sylvius and his successors; it was sometimes their form, and sometimes their 
direction, position, uses, etc. to which the muscles owed their names. 


GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 177 


Bourgelat applied this nomenclature to the horse, but modified it in many 
points. 

Chaussier, struck by the imperfections of the nomenclature introduced 
into science by Sylvius, sought to substitute for it another much more philo- 
sophical. This anatomist gave to each muscle a name formed by two words 
indicating the insertions of the organ. Girard imported this ingenious 
idea into veterinary anatomy. 

Nevertheless, notwithstanding its advantages, this new nomenclature 
did not supersede the old one; because it ceased to be correct when applied 
to comparative anatomy, the same muscles not having the same insertions 
in all the species.’ 


It is not, however, that the ancient nomenclature has more advantages in ‘this 
respect than the new. What can be more improper, for example, than the names of 
deltoid, splevius, soleus, digastricus, etc.? Do the muscles which receive these desig- 
nations, considered in mammals only, offer in all species the form or the structure which 
justifies the employment of these names in the human species? Are the distinctive 
epithets of great, medium, little, etc., given to many of them, reasonably applicable in 
every case? May not the same objection be urged against the majority of the names 
derived from their uses, complications, ete. ? 

No system of myological nomenclature is really philosophical, and we are of those 
who believe it to be indispensably necessary to create one; indeed, we are inclined to think 
that it would be simple and easy to attain this result in starting from a basis whose 
fixity and invariability should be well defined. And this basis is, in our opinion, already 
discovered ; it is the principle of connections founded by E. Geoffroy Saint-Hilaire in his 
immortal ‘ Philosophie Anatomique,’ a principle to which modern science certainly owes its 
finest conquests. 

This is a subject which it is our intention to treat in a special work; but we may, 
nevertheless, indicate here the manner in which it presents itself to us. 

We are desirous that the myological nomenclature should rest entirely, in the first place, 
on the relations of the muscles with the pieces of the skeleton, or with other organs equally 
fixed and very important ; in the second place, on the reciprocal connections of the muscles. 

Such is our plan; and it is not precisely new, for the old anatomists were often 
inspired with it, though unwittingly, as the principle on which it is founded was to 
them entirely unknown; this circumstance, however, immediately leads us to an appre- 
ciation of its value. For instance, what could be happier tl,an the name of intercostals 
given to the muscles situated between the ribs. and their distinction into external and 
internal? Here we have names which indicate the relations of the muscles they desig- 
nate with the portions of the skeleton and the reciprocal connections of these muscles. It 
can also be applied in an equally rigcrous manner to every species. We may also cite 
the supracostals, the intertransverse, the transverse spinous, the subscapularis, the 
supraspinous, the subspinous, etc., as they are {ound in a greater or less marked degree 
in identical conditions. 

Other muscles have received names derived in part from their situation, and in part 
from their volume. These names are far from being as convenient as the first; as may 
be judged from the following examples : . 

In the majority of vertebrate animals, there are three important muscles situated 
above and behind the pelvis, and forming the basis of the buttock ; they have been 
designated gluteals, and this name is convenient, because it designates their situation. 
But to distinguish them from each other, regard has been had to their volume; so that 
there is a great, a medium, and a small gluteus. This isan error, however, for the volume 
of the muscles is subject to the greatest variations, and a voluminous muscle in one 
species may be a very small one in another, and vice versd. The muscle analogous to the 

«gluteus maximus in Man has been described by Bourgelat as the minimus, and by Lafosse 
and Rigot as the medius. With regard to tlie glutgus medius of Man, its representative 
in the lower animals has been designated as the maximus by the majority of veterinary 
anatomists. What confusion! And how easy it v & to evade it by distinguishing these 
muscles, not by their volume, but by their reciproeai connections, which are the same in 
every species! Is it not, indeed, more natural toxusubstitute the names of superficial, 
middle, and deep gluteals, for those of great, etc ? : : 

The same remark is applicable to the muscles which, in Man, cover the anterior 
aspect of the chest. Designated in common, and justly so, as pectorals, these muscles 
are wrongly distinguished into great and little; for the last, which is already an 


178 THE MUSCLES. 


In this work we will follow the nomenclature of Bourgelat, which will 
however, be submitted to some change. But as the names given by Girard 
are, in our opinion, of some assistance to students, care will be taken to 
include them in the synonymy. ; 

(It only remains for me to add that Chauveau’s nomenclature will 
be followed as closely as possible. It possesses advantages which are 
greatly superior to that adopted by Percivall ; and as, in my opinion, the 
names and terms imported into science should be as nearly alike in all 
languages as may be compatible with circumstances, in order to facilitate 
study, comparison, and reference, I the more readily venture to take this 
step. Percivall’s nomenclature will, however, be added in brackets to the 
synonyms, as well as that of Leyh and Gurlt when occasion appears to 
demand it.) 


STRUCTURE OF THE STRIPED MUSCLES, 


There enter into the structure of muscles: 1, Muscular tissue, properly 
so-called; 2, Conjunctival tissue in the form of delicate 
lamelle, aponeuroses, or tendons; 3, Vessels and nerves. 
A. Mouscu.ar Tissvzr.—This tissue is composed of 
prismatic fasciculi, which it is possible to divide and 
subdivide into several smaller and smaller fasciculi, 
until the muscular fibre or primitive fasciculus is rcached. 
The muscular fibre is a kind of irregular polyhedron, 
with rounded angles, and extremities terminating in a 
blunt point. It is sometimes straight, sometimes 
wrinkled, but always striped either in a longitudinal or 
transversal direction, or both at once. 
B, ULTIMATE FIBRIL This fibre is formed by an envelope and contents. 
OF MUSCLE, accord The envelope is avery delicate, structureless mem- 
ing to Bowman. : 
i; Muscular Shremans brane of an clastic nature, named the sarcolemma or 
highly magmified, its ™”yolemma. Nuclei in greater or less number can be 
myolemma being so seen on its inner face. 


Fig. 95. 


thin and transparent The contents are resolved into contractile fibrille and 
as to allow the ulti- Se targa 
i an interstitial substance. 
mate fibrille to be : F a : 
Reati. The contractile fibrilla constitutes the primary ele- 


ment of striped muscle. It is a minute column whose 
surface, according to Rouget, exhibits the alternate prominences and 
depressions of the turns of a more or less fine screw; and which, according 
to Bowman, is formed by a mass of 
small discs, named by him the sarcous 
elements. 

The znterstitial substance, granular 
and nucleated, unites the fibrille in 
the interior of the sarcolemma and, 
; ae shies ; 
MUSCULAR FIBRE BROKEN ACROSS, SHOWING hs eu ue to Dowmon's 

THE UNTORN SARCOLEMMA conNecTine “YPOthesis, the discs entering into 
THE FRAGMENTS. the composition of each fibrilJa. 

The aggregation of the fibrille 

produces the longitudinal striation: the transverse striation is the result 


Fig. 96. 


enormous muscle in the smaller Ruminants, is represented in Solipeds by two consider- 
able muscles, much more voluminous than the muscle analogous to the great pectoral. 
It is only necessary, in this case, to change their names into superficial and deep 
pectorals. 


GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 179 


either of the helicoid disposition of the fibrille, or of the fusion of the 
sarcous elements which compose the latter, according to the admitted opinion 
as to the structure of the contractile element. 

The muscular fibres are united parallel to each other to form secondary 
fasciculi, which are surrounded by a con- 
junctival sheath—the perimysium. The 
secondary fasciculi are laid together to 
constitute more voluminous  fasciculi 
which, in their turn, form the entire 
muscle. The conjunctival sheath enve- 
loping the muscle is named the eaternal 
perimysium. 

B. Trenpons anp AProngvrosEs.—The 
tendons are white, nacreous, round, or 
flattened cords fixed to the extremities of 
the long muscles. They are composed 
of fasciculi of condensed conjunctival 
tissue, affecting a parallel direction, and 
united to one another by connective 
sheaths. 

The aponeuroses belong almost ex- 
clusively to the wide muscles; they are 


Fig. 97. 


TRANSVERSE SECTION OF FROZEN MUSCLE, 
MAGNIFIED 400 DIAMETERS, 


N, Nerve; M, Muscular fibre, surrounded 


formed of several planes of parallel fibres 
which are not intercrossed in their 
middle part; at their superficies, how- 
ever, the fibrous fasciculi are matted toge- 
ther in a more or less inextricable manner. 

It is very interesting to study the 
mode of union of the muscular fibres 
with the tissue of the aponeuroses and 


by portions of six others——a, Nucleus 
of the nerve sheath; b, Nucleus of the 
sarcolemma; c, Section of nucleus of 
terminal plate of nerve; d, Transverse 
section of terminal plate, surrounded 
by granular material; e, Transverse 
section of muscle nuclei; f, Fine fat 
drops. The angular dark particles are 
sections of sarcous elements: the clear 
intervening spaces represent the fluid 


tendons, as well as the reciprocal rela- isotropal part of the muscle substance. 


tions of these two parts. 

The muscular fibre may be found passing in the same direction as the 
tendon, or it may fall upon the latter obliquely. In both cases there is no 
insensible transition between the muscular fibre and the fasciculus of the 
fibrous tissue ; on the contrary, the contractile fibre terminates by a rounded 
extremity, which is buried in a corresponding depression in the tendon or 
aponeurosis. The union of the muscular with the fibrous tissue is very 
intimate ; when the muscles are submitted toa degree of traction sufficient to 
cause a rupture, this never happens at the point of union. ; 

The tendons commence sometimes by a hollow cone, which receives on 
its internal face the insertions of its muscular fibres; and sometimes by a 
thin point, often divided, which is plunged into the substance of the muscle. 
It is worthy of remark that a muscle provided with two tendons shows the 
first-enamed arrangement at one of its extremities, and the other at its oppo- 
site extremity ; so that all the fibres which compose the muscle offer nearly 
the same length, those which leave the summit of the internal tendon being 
fixed to the bottom of the hollow cone formed by the second tendon, and so 

iprocally. 
= seca ie fibres which are continued by the fibrous fasciculi may be 
divergent or parallel. In the first case—the diaphragm, for example—the 
connective fibres run in the same direction as the muscular fibres. In the 
second case, several arrangements may be observed : 


180 THE MUSCLES. 


1. Tendons may pass in the same direction as the muscular fibres. This 
is the most simple manner. But the muscle may be divided into two bodies 
or bellies by a middle tendon ; it is then called a digastric muscle. 

2. Muscular fasciculi, passing altogether from the same side to become 
anited into a tendinous cord, constitute a semi-penniform muscle. 

3. Muscular fasciculi may be implanted to right and left of the tendon, 

m a pennated or penniform muscle. 

ae eenvennett Be a demonstrates that the length of the muscle, 
the length of its belly, and the length of its muscular fibres, should be care- 
fully distinguished. The first term is applicable to the whole of the muscle, 
the tendon included ; the second, to the fleshy body of the muscle, with the 
exception of the tendon; the third, to the muscular fasciculi constituting 
this fleshy body: the latter idea is the most important, for it alone indicates 
the amount of contraction a muscle is sus- 
ceptible of, and consequently the possible ex- 
tent of movement it is capable of effecting.”— 
Beaunis and Bouchard. 

C. Vessens anp Nerves.—The muscular 
tissue receives much blood; the fibrous tissue 
very little. The arteries are large, numerous, 
and each is acecompanied by two veins. The 
capillary vessels anastomose in such a manner 
as to form rectangular meshes, whose greatest 
diameter is directed towards the length of the 
muscle. 

The lymphatic vessels of the muscles are 
few; they sometimes penetrate their interior in 
following the capillaries; at other times they remain on the surface, in the 
external perimysium. The exist- 
ence of lymphatics has not yet been 
demonstrated in tendons, aponeu- 
roses, or synovial membranes. 

The nerves emanate from the 
cerebro-spinal centre. At their 
terminal extremity they offer a 
small enlargement, called by 
Rouget the terminal motor plate, 
and by Doyére and Kiihne the ner- 
vous colline (hillock). It is ad- 
mitted that the motor tube traverses 
the sarcolemma, losing its enve- 
lope; and that the substance of the 


DISTRIBUTION OF CAPILLARIES 
IN MUSCLE, 


Fig. 99. 


PORTION OF AN ELEMENTARY MUSCULAR FIBRE, 


a 


WITH FOUR DARK-BORDERED FIBRES (a) CROSS- 
ING ITS SURFACE; after Beale. 

Capillary blood-vessel, with fine nerve-fibres; 
a few only of the transverse markings of the 
muscle are represented; c, Two of the dark- 
bordered nerve-fibres passing over the ele- 
mentary fibre to be distributed to adjacent 
fibres. This arrangement, in which a dark- 
bordered nerve-fibre, distributed to muscle, 
divides into branches, one of which passes to 
a vessel, while the other ramifies upon a 
muscle, is frequent. Magnified 700 diameters, 


cylinder is spread over the surface 
of the muscular fibrille to form the 
motor plate or nervous colline. 


PHYSICO-CHEMICAL PROPERTIES OF 
STRIPED MUSCLES. 


Muscles are soft organs, re- 
markable for their more or less 
deep-red colour, which varies with 
the species, and even in these with 
the age and health of the animals. 


GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 181 


By desiccation, muscles become hard and brown ; by repeated washing 
they assume a straw-yellow tint. 

Muscles are extensible and elastic; they are also tenacious, and their 
tenacity is more marked during lite than after death. 

It has been remarked that the juice impregnating the muscular tissue is 
distinguished from the serum of the blood by anacid reaction. (The fluid or 
“muscle plasma” obtained by pressing flesh, is either neutral or slightly 
alkaline. It soon coagulates and separates into two portions—a semi-solid 
portion, “myosin,” and the fluid serum that at ordinary temperatures quickly 
acquires an acid reaction.) It holds in solution a variable quantity of 
albumen, casein, fat, a little creatine, creatinine, and a somewhat large 
proportion of lactic acid. The solid substance of the muscle may be partly 
transformed into gelatine by boiling in watcr; but its largest portion is a 
nitrogenous substance, soluble in dilute hydrochloric acid, called “ syntonine,” 
or muscular fibrine ; it differs but little from the fibrine of the blood. 


PHYSIOLOGICAL PROPERTIES OF THE STRIPED MUSCLES, 


In this paragraph will only be discussed the development of the muscles, 
muscular contractility, and the part the muscles assume in locomotion. 

A. DrEvELopmMENT or THE Muscies.—A muscle is derived from a mass of 
embryonic cells. Each cell becomes considerably elongated, and its nucleus 
becomes multiple, to constitute a muscular fibre. The membrane of the cell, 
enormously developed, forms the sarcolemma, while the contents of the cell, 
becoming more dense, divide longitudinally and give rise to the contractile 
fibrille. Lastly, when the muscles are formed, they grow by the augmenta- 
tion in length and thickness of the primary fasciculi or muscular fibres. 

3B. Muscutar Conrracrisitiry.—Muscles possess the property of con- 
tracting under the influence of a natural or artificial stimulus. Muscular 
contraction is the phenomenon resulting from the operation of this property. 
Muscles in a state of contraction are the seat of physical and chemical 
phenomena ; they change their form and consistency,and become the theatre 
of a relatively abundant production of carbonic acid. creatinine, and inosinic 
acid. During contraction, it has been remarked that the muscular fibres 
contract by increasing in volume, like an india-rubber tube left to itself after 
being extended : the zig-zag doubling mentioned by Prevost and Dumas has 
not been observed. 

But these physical and chemical modifications, important as they are in 


Fig. 100. 


MUSCULAR FIBRE IN A STATE OF CONTRACTION IN THE CENTRE} THE STRI@ 
APPROXIMATED$ THE BREADTH OF THE FIBRE INCREASED; AND THE MYO- 
LEMMA RAISED IN VESICLES ON ITS SURFACE. 


a physiological point of view, cannot longer be dwelt upon here. It is parti- 
cularly important to speak of muscular contraction. 

A muscle that contracts becomes shortened ; its two extremities approach 
each other if they are free ; or one draws near the other if the latter is fixed 


15 


182 THE MUSCLES. 


to an immovable point. If the extremities of a muscle are attached to two 
movable levers, its contraction will bring about the displacement of one or 
other of these; from this a movement is produced. : p 2 

The degree of shortening of a muscle varies, according to its being 
entirely free, or having a resistance to overcome. The mean limit of this 
shortening is about one-fourth the length of the muscular fibres; from this it 
will be understood that the movement produced by the contraction will be 
in proportion to the length of the fibres; though in this appreciation it will 
be necessary to keep in mind the density and energy of the fibre, as well as 
the intensity of the contractile stimulant. ran 

As each fibre represents a force independent in its action, it results that 
we may judge of the power of a muscle by the number of its fibres, or its 
volume. 

Muscles are often aided in their action by mechanical conditions: such as 
the disposition of the levers on which they act, the direction of the muscular 
fibres in connection with these levers, and, lastly, by the presence of lamelle 
or elastic cords. 

C. Uses or Muscrxs.—There are flexor, extensor, abductor, adductor, 
rotator, and other muscles, for all the movements of which the articulations 
are the centre. 

To determine the functions or uses of the muscle, it is sufficient to know 
their insertions, and the mode in which the bones furnishing these insertions 
articulate with each other. 

The result of muscular contraction. being influenced by the form of their 
principal axis, and the length and direction of their levers, it is necessary to 
briefly examine these two points; 

1. The immediate effect of the contraction of rectilinear muscles is the ap- 
proximation of the bones to which they are attached. This approximation 
is usually brought about by the displacement of a single ray: that which 
receives the movable insertion of the muscle. Sometimes, however, the two 
rays move simultaneously, or they are alternately fixed and movable. 

The first result produced by a curvilinear muscle is the straightening of 
its component fibres ; after which it may act on the bony levers as do the 
rectilinear muscles, if its contractile power be not entirely expended. When 
a muscle is quite circular, its only action is to contract the opening it circum- 
scribes. 

With regard to the inflected muscles, their action can only be estimated 
from their point of'inflexion ; they operate as if this point represented their 
origin or fixed insertion. 

2. The muscular powers are submitted to the statical and dynamical laws 
which govern the theory of levers, for the bony rays are only levers moved 
by the muscles. 

In the locomotory apparatus we find the three kinds of lever recognised 
by physicists. Thus the head, extended by the great complexus muscle, 
represents an interfixed, or lever of the first class ; the foot, extended by the 
gastrocnemii muscles, offers an example of the interresisting, or second kind, 
when this member remains fixed on the ground ; lastly, the lower jaw raised 
a aa the upper by the masseter muscle, forms an interpuissant or third 

ind. 

It is worthy of remark that the arm of resistance in the bony levers is 
always extremely long ; a circumstance which favours speed and the extent of 
movement at the expense of power. 

On the other hand, muscles are rarely perpendicular to the arm of their 


GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 183 


levers, at least at the commencement of their action ; another circumstance 
which again diminishes their energy. 


APPENDAGES OF THE MUSCLES. 


These are: 1, The enveloping or contentive aponeuroses; 2, The 
serous or mucous burse; 3, The tendinous and synovial sheaths. 

A. Cortrntive Apongvroses.—These are layers of white fibrous tissue, 
which envelop, in common, all the muscles of one or several adjoining 
regions, principally those of the inferior rays of the limbs, where they con- 
stitute a kind of hollow cylinder. 

These aponeuroses are formed by very resisting interwoven fibres, which 
are attached to the bones at numerous points. At their periphery they 
receive the insertion of one or several muscles, which keep them more or less 
tense. Their external face responds to a thin fibro-cellular layer that 
separates them from the skin. The internal face sends lamellar prolong- 
ations between the muscles, which are destined to isolate these organs in 
special sheaths. 

The aponeuroses maintain the muscles in their position, and sustain 
them during their contraction. 

B, Szrous Bursm.—The serous or mucous burse are small cavities, filled 
with a serous fluid, which are met with at those points where the muscles 
glide over resisting surfaces. They are generally orbicular or rounded, and 
their interior is often divided by fibrous bands. 

Their walls are formed by slightly condensed conjunctival tissue, and 
may be lined by a pavement epithelium; in which case it is believed that 
the serous bursa is produced by the simple dilatation of one of the con- 
junctival meshes. 

“©. Trexprnous SHearus anp SynoviaL Mempranus.—Tendinous sheaths 
is the name given to the half-bony, half-fibrous, sometimes exclusively fibrous, 
gliding grooves into which the tendons pass when they are inflected to change 
their direction. acs 

The tendinous synovial membranes are serous membranes lining the ten- 
dinous sheaths and covering the tendons at the points where these two parts 
correspond. They secrete a synovial fluid quite like that of the articulations. 

When they almost completely envelop the tendon, and are afterwards 
carried to the walls of'the sheath, they are termed vaginal. 

Their walle are composed of: 1, A very fine conjunctival membrane, con- 
founded by its external face with the tendinous sheath, by the other face with 
the tendon; 2, A simple layer composed of pavement epithelium, extended 
over the whole or a part of the internal face of the conjunctival membrane. 


MANNER OF STUDYING THE MUSCLES. 


A. Oxasstrtcation.—To facilitate the study of the muscles, two methods 
may be employed in grouping them. The first consists in classifying them 
according to their uses ; describing, for example, all the flexors, extensors, etc., 
of the same region. In the second method, the uses of the muscles are not 
taken into account, their relations only being considered; and they are 
divided into groups or regions, which comprise all the muscles situated 
around a bony ray. The latter is the method now adopted, because it is 
the most convenient, useful, and rational. ; Ensiaok, 

(Leyh describes the muscles by layers, or according to their situation, 


184 THE MUSCLES. 


which, he asserts, facilitates the study of anatomy in a surgical point of 
view). 


B. PREPARATION.—We Will limit ourselves to some general remarks on the following 
joints : 

‘ Choice of a subject.—If there is for disposal a certain number of subjects from among 
which it is possible to make a selection, the preference should be given to those that 
have the muscular system best developed; not that large, soft, lymphatic horses with 
enormous masses of muscle should be chosen, for these animals are always less 
convenient than small or middle-sized, well-bred horses. Asses and mules, when very 
emaciated, answer well for the preparation of the muscles. — 

Position of the subject.—It is necessary to place the subject, immediately after death, 
in a convenient position, in order that the cadaveric rigidity may set in while it isin that 
attitude. Without this precaution, the various parts of the body may assume an incon- 
venient shape or direction, and all attempts to amend them will prove almost unavailing, 
particularly in the larger animals. 

Three principal positions may be given to subjects: 

1. The animal is in the first position when it is placed on its back, the four ex- 
tremities in the air, and maintained in that posture by means of long cords passed 
round the pasterns and fixed to the movable rings which terminate the extremity of the 
four bars of the wheeled-table on which the subject is laid. The head should be beyond 
the end of the table and rest upon a stool. The animal should always be placed in such 
a manner that the head be opposite the fore-part of the table, so that the movements of 
the pole or shaft be not impeded during the displacement of the apparatus. In order 
that the neck be not twisted to the right or left, in attaching the fore-limbs the subject 
should be raised so that the withers rest lightly on the table. According to the bulk of 
the animal and the length of the bars, the ropes should be passed around either the 
pasterns, above the fetlocks, or even above the knees. 

2. To place the animal in the second position, it is turned on the belly, the two 
thighs flexed, the extremities carried beyond the table, and the head fixed between two 
bars by means of a rope passed under the zygomatic arches. 

3. The subject is in the third position when it rests on its side. 

Rules to be observed during the preparation.—1. By no means, if possible, remove the 
skin from the regions to be dissected until quite ready to begin the dissection. If this is 
impossible, then take the precaution of enveloping these regions in damp cloths, or in 
the animal’s skin, to prevent desiccation of the aponeuroses and the superficial muscles. 

2. To dissect a muscle, it is necessary to remove the aponeuroses or the other 
muscles which cover it, the cellular tissue enveloping it, and the fat, glands, vessels, and 
nerves lodged in the neighbouring interstices. The aponeuroses should be removed in 
shreds by making them very tense with the forceps, but without raising them, and 
causing the blade of the scalpel to glide between the fibrous and muscular surfaces, 
keeping it always parallel to these two planes. The covering muscles should not be 
entirely excised, hut ought to be cut through the middle, across their fibres, and the 
ends thrown back; in this way it is always possible to replace a muscle by bringing the 
two portions together ; the study of its relations is then much more easy. The cellular 
tissue is got rid of by removing it with the forceps, and carrying the edge of the scalpel 
in the re-entering angle formed by the cellular layer and the surface of the muscle. 
This method also suffices for removing aponeuroses when they are slightly adherent to 
the muscular fibres. But when they give attachment to these by their under face, as 
may be noticed in the external scapular aponeurosis, it is neevssary to have recourse to 
the method indicated above. To remove fat, glands, etc., scissors will be found very 
advantageous. 

Order to follow in preparing all the muscles of the same subject, and to derive mast 
advantage therefrom.—l. Place the subject in the first position, and commence by study- 
ing the muscles of the inferior abdominal region. Then excise them, leaving the posterior 
extremity of the great pectoral muscle, the prepubic tendon, and the crural arch intact. 
The abdominal cavity having been emptied of the viscera it contains, dissect and study 
successively the diaphragm, the internal crural region, except the deep muscles, the 
sublumbar region, the femoral and posterior crural regions, the superficial muscles of 
the inferior cervical region, and the pectoral region. 

2. After detaching for future use one of the anterior limbs, the animal is placed in the 
second position, and one after another may be dissected the muscles of the ear, those of 
the superior cervical region, the croup and costal regions, except the triangular muscle, 
and the spinal region of the back and loins, 


GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 185 


8. The regions of the anterior limb may be prepared at the same time, or immediately 
afterwards, 

4. Separate the two posterior limbs by sawing the femurs through their middle, and 
proceed to the dissection of the muscles of the posterior leg and foot. 

5. By means of another application of the saw across the middle of the loins, the 
pelvis is completely isolated for the preparation of the coceygeal muscles, and the deep 
cee of the internal crural region, nearly as they are represented in figures 90 
and 131. 

6. The animal being placed on its side. the pectoral cavity is opened by sawing 
through the ribs near their extremities; on the two particular portions thus obtained 
may be studied, in one part, the triangularis of the sternum, and in the other the deep 
muscles of the inferior cervical region, including the long muscle of the neck and 
the anterior and lateral straight muscles of the head. 

7. Lastly, the head is disarticulated and the muscles of this region are prepared 

The subject may afterwards serve for the study of nearly all the articulations. 

Preservation of the muscles.—The muscles may be preserved by immersing them in 
appropriate fluids, and the muscular preparations by drying them. 

A large number of liquids preserve muscles from putrefaction. We may mention 
alcohol ; a mixture of alcohol and spirits of turpentine; alcohol, water, and chloroform ; a 
solution of sulphate of iron, bichloride of mercury, or arseniousacid. The best preservative 
fluid, however, is nitric acid diluted with water, in the proportion of one of the former 
to three of the latter. The acid hardens the muscles and softens the conjunctival 
tissue; this allows all the interstices to be completely cleared out, and even permits the 
primitive muscular fasciculi which have been concealed by the white tissues to be exposed. 

Desiccation, after immersion in a bath of arsenious acid or sulphate of iron, causes 
the muscles to become hardened and deformed. It is therefore a bad procedure. 

(A careful dissection of the muscles, with regard to their origin, insertion, action, and 
relations, is of infinite importance to the student of human anatomy; to the Veterinary 
Student itis no less important, and more particularly with reference to the muscles of the 
limbs. A correct knowledge of their situation, attachments, and functions is often the 
only guide the Veterinary Surgeon can rely upon in the diagnosis of those apparently 
obscure cases of lameness which are of such comparatively frequent occurence. In the 
words of Mr. Henry Gray, we may repeat that “an accurate knowledge of the points of 
attachment of the muscles is of great importance in the determination of their action. 
By a knowledge of the action of the muscles, the surgeon is able at once to explain the 
causes of displacement in the various forms of fracture, or the causes which produce 
distortion in the various forms of deformities, and, consequently, to adopt appropriate 
treatment in each case. The relations also of some of the muscles, especially those in 
immediate apposition with the larger bloodvessels, and the surface markings they pro- 
duce, should be especially remembered, as they form most useful guides to the surgeon 
in the application of a ligature to these vessels.” —‘ Anatomy, Descriptive and Surgical. 

An accurate knowledge of the muscular system is also of great service to the 
Veterinary Surgeon in estimating the value to be placed upon the external conformation 
presented by animals intended for different kinds of labour. 

“In dissecting,” says Mr. Holden, “there are four principal objects to be constantly 
borne in mind by the student: 1st, The impression on the memory of those facts of 
general anatomy taught in the lectures. 2nd, Ihe study of those parts of the body 
more especially concerned in surgical affections and operations. 3rd, The education. of 
the sense of touch, and of the hand in the use of instruments; and 4th, The education 
of the eye in the knowledge of the several tissues of the body, in various positions, and 
varying circumstances. . . . The education of the eye is a gradual and tedious process, 
but one which is pretty certain to be satisfactorily accomplished if the student, do but 
use his hands properly, and therefore a few words on the manual part of dissection may 

- not be out of place. ’ eres ' 

“First, as to the instruments requisite for dissection. A case, containing six or eight 
scalpels, two pairs of scissors, a pair of dissecting forceps, a set of chain-hooks, a blow- 
pipe, and a probe, will enable the student to make all requisite dissections, supposing 
that he is allowed the use of a saw and chisel in the dissecting-room. Great variety 
exists in dissecting-cases, both as to form and expense, but so long as the instruments 
themselves are strong and good, the simpler the case the better. Scalpels for dissection 
are made of two principal shapes; in one, the edge is bevelled to the point, the back 
being straight; in the other, both back and edge are bevelled to a point midway 
between the two. The latter form is preferable for most purposes. The blade should 
not be more than an inch and a half long, and never double edged ; but the material of 
which the handle is constructed is a matter of indifference, 


186 THE MUSCLES. 


“For all ordinary dissection, it will be found most convenient to hold the scalpel 
like a pen; but for cleaning the fascia off museles, and following out small nerves, it is 
better to hold it reversed, so that the back of the knife may be against the tissue which 
is to be preserved. In making the first incision through the skin of a limb, or in any 
other position where a long incision is required, the knife may, with advantage, be held 
under the hand, by which the wrist has more play, and the student has the opportunity 
of practising a mode of holding the knife, which he will find very useful when operating 
on the living body. ; 

“The forceps should be broad at the extremities and coarsely serrated, so that it may 
retain a firm hold on small portions of tissue. It is very important that the forceps 
should not be too strong in the spring, for in that case it becomes so fatiguing to the 
hand that it is impossible to continue its use for any length of time. The forceps 
should be held lightly between the thumb and the first and second fingers of the left 
hand, which may be steadied by resting the little finger on a neighbouring part. 

“The chain-hooks should be strong, and bent in the direction of the thickness and 
not of the breadth of the steel, as is sometimes done. These latter are very inferior, 
being liable to be unbent under any considerable strain. Care should be taken that the 
chains are firmly linked, and that the central ring is sufficiently stout to bear any force 
that may be applied. The scissors should be large and strong, and it will be found 
advantageous to have one curved pair, which is very useful in preparing the ligaments. 

“The student will do well to bear in mind that he will probably be called upon in 
after life to operate on the living body, the only true preparation for which is careful 
dissection; he should therefore, as far as possible, conduct all his dissections as 
methodically, and with as much care, as if operating on the living body. 

“Phe student should bear in mind that his manual labour is only a part of his duty, 
and will be thrown away, unless he at the same time study the description of the part 
upon which he is engaged; he should not, therefore, carry the dissection further than he 
can learn the description on the same day, and at the subject, and should, if possible, 
re-peruse the description in the evening, and always on the next morning, before 
carrying the dissection any further.”) 


CHAPTER II. 
THE MUSCLES OF MAMMALIA. 


Articte I.—Musoies oF THE TRUNE. 


SUBCUTANEOUS REGION. 


Tus only comprises a single muscle, the fleshy panniculus (panniculus 
carnosus), destined to move the skin covering the trunk. Strictly speaking, 
however, we may describe as dermal muscles all those which are attached to 
the inner surface of the superficial integument—the muscles of the face, for 
example. : 


Fleshy Panniculus, 


Preparation.—Place the-animal on its side, and carefully remove the ski i 
the cuticular muscle to remain on the subjacent muscles. ai ee 


Situation—Form— Extent.—Situated on the inner surface of the skin cover- 

ing a am of the ees and abdomen, the fleshy panniculus is an immense 
road muscle, irregularly triangular in shape, thin i 

thicker in the middie ith pie ee a 

The upper border corresponds to a curved line, convex superiorly, and 
extending obliquely from the flank to the withers. ‘The inferior border is 
carried horizontally from the flank to the posterior border of the olecranian 
mass of muscles, passing along the upper margin of the great pectoral 
mauscle, which it covers, and to which it adheres somewhat closely. The 


MUSCLES OF THE TRUNK. 187 


anterior border descends from the superior extremity of the shoulder on to 
the muscles of the fore-arm., 

Structure—Attachments.—The fleshy fibres entering into the composition 
of this muscle are directed forward for its posterior two-thirds; but on 
arriving on the shoulder they gradually straighten and become vertical. 
They are continued, on the margins of the muscle, by aponeuroses which 
attach it either to the internal surface of the skin or to the fibrous fascia 
of the superficial muscles. 

This muscle has, besides, a very remarkable insertion into the humerus, 
which was noticed by G. Cuvier, in his ‘Lecons d’Anatomie Comparée,’ 
and which appears to have been omitted, at least so far as Solipeds are 
concerned, in every treatise on Veterinary Anatomy. The following is what 
we have often observed in this respect :—On reaching the posterior border of 
the ulnar mass of muscles, the panniculus divides into two superposed 
layers: one, superficial, is carried to the muscles of the anterior member ; 
the other, deep, soon terminates by an aponeurosis which is united to the 
great pectoral muscle, and is bordered at its upper margin by a nacrous 
aponeurotic band, which penetrates between the thorax and the muscles of 
the arm to be fixed to the small trochanter. 

Relations.—By its superficial face, with the skin, to which it closely 
adheres ; by its deep face, with the great dorsal, the dorsal portion of the 
trapezius, the abdominal tunic, the great oblique muscle of the abdomen, the 
great serratus, some external intercostals, the spur vein, and the superficial 
muscles of the shoulder and arm. 

Action.— The animal, in contracting this muscle, shakes the whole of the 
cutaneous integument which covers it; thus preventing insects from alighting 
on the surface of the body, or tormenting by their bites or stings. 


In the Dog, the panniculus carnosus is prolonged over the croup, and is united along 
the dorso-lumbar spine to that of the opposite side. It is very developed in the Cat. 


CERVICAL REGION, 


This region comprises all the muscles grouped around the cervical 
vertebre—muscles which are conspicuous by their volume and the important 
part they play in the animal economy. There are described a superior and 
an inferior cervical. 


A. Superior Cervical, or Sptnal Region of the Neck. 


This includes seventeen pairs of muscles, which are: the cervical portion 
of the trapezius, rhomboideus, angularis of the scapula, splenius, great compleaus, 
small complexus, transverse spinous of the neck, the six intertransverse muscles of 
the neck, great oblique muscle of the head, great posterior rectus, and small pos- 
terior rectus. These form four superposed layers on each side of the cervical 
ligament, and occupy the triangular space circumscribed by the upper 
border of that ligament, the transverse processes of the vertebra of the neck, 
and the spinous process of the second dorsal vertebra. 

Preparation.—Place the subject in the second position and dissect in suecession the 
four layers of the region. To study the first layer, which is formed by the cervical portion 
of the trapezius, remove the skin, cellular tissue, and the fibrous fascia covering that 
muscle (See fig. 102). The preparation and study of the second layer, composed of the 
thomboideus, angularis. and splenius, is curried out in two stages. In the first. the 
trapezium and the mastoidu-humeralis is removed, leaving only the cervical insertions 


For the description of this muscle, see the Srinat Reeton of the back and loins. 


188 THE MUSCLES, 


of the latter muscle; then the limb is removed by sawing through the scapula beneath 
the insertions of the angularis and great serrated muscles, as in figure 105. But as 
neither the cervical or dorsal insertions of the splenius are exposed, it is necessary to 
proceed to the second part of the operation by removing the rhomboideus, angularis, 
and the superior extremity of the shoulder. To prepare the third layer, which com- 
prises the great and small complexus, it is sufficient to excise the splenius, in following 
the direction of the neck, and to turn upwards and downwarus the two portions of the 
muscle (See fig. 106). Lastly, the deep layer—the transverse spinous, intertransverse, 
oblique, and posterior straight muscles, as well as the cervical ligament—is exposed by 
removing the two complexus and the ilio-spinalis muscles (See fig. 104). 


1. Rhomboideus. (Figs. 101, 6; 104, 1, 2.) 


Synonyms.—Described by Bourgelat as two muscles, the proper elevator of the 
shoulder and the rhomboideus, these were termed by Girard the cervico-subscapularis 
and dorso-subscapularis. (This is the rhomboideus longus and brevéy of Percivall, and 
the dorso-scapularis and cervico-subscapularis of Leyh.) : 


Form—Situation—Direction.—This muscle has the form of 4 very 
elongated triangle, and is situated at the inner aspect of the cervical 
trapezius and the scapular cartilage. beneath the cervical ligament, whose 
direction it follows. 


Fig. 101. 


LATERAL VIEW OF THE NECK; SUPERFICIAL MUSCLES. 

1, 1, Parotid gland; 2, Sterno-maxillaris and, 14, Its juncti ith i 
rotid : Junction with its fellow of th 
opposite side; 3, 4, Mastoido-humeralis, or levator humeri; 5, Spleniues 6, 
Rhomboideus ; 7, Funicular portion of the cervical hgament, or ligamentum 
ie ; s ig eo the scapula; 9, Supra-, or antea-spinatus; 10, Trapezius; 

nira-, or postea-spinatus ; i in; i 

ie coe Pp pinatus; 12, Jugular vein; 13, Subscapulo-hyoideus ; 


Structure—Attachments.—It is composed of thick iculi 
anterior of which are oblique downwards and ae nae 
passing directly downwards. These fasciculi are fixed by. their superior 
extremity to the funicular portion of the cervical ligament and the summits 
of the spinous processes of the four or five dorsal vertebree succeeding the 


MUSCLES OF THE TRUNK, 189 


first—fixed insertion ; by their inferior extremity, to the inner aspect of the 
scapular cartilage, where the anterior fasciculi are confounded with those of 
the angularis. 

Relations.—Covered by the cervical portion of the trapezius, the scapular 
cartilage, and the aponeurosis of the great dorsal muscle, the rhomboideus 
covers the sphenius, which is excavated near its superior border for its 
reception, as well as the aponeurosis of the anterior small serrated muscle 
through the medium of a yellow elastic lamina. 

Action.—It draws the shoulder upwards and forwards. 


“2. Angularis Muscle of the Scapula. (Figs. 102, 4; 105, 3.) 


Synonyms.—Trachelo-subscapularis—Girard, Portion of the serratus magnus 
—Bourgelat. Elevator of the scapula—Cuvier. (Anterior portion of the serratus 
magnus of Percivall. The levator anguli scapule of Man.) 


Situation—Form—Structure.—This is a very strong muscle, situated in 
front of the shoulder, triangular, flattened on both sides, thin at its superior 
border, thick behind and below, and almost entirely fleshy. 

Attachments.—It takes its origin from the transverse processes of the five 
last cervical vertebrae by five distinct portions, which are directed towards 
the scapula in converging towards each other, and soon join to form a single 
muscular body, which is inserted into the internal face of the scapula, on its 
anterior triangular surface. 

Relations—This muscle is confounded at its inferior border with the 
serratus magnus. It is covered by the cervical trapezius, the mastoido- 
humeralis, and the small pectoral muscle. It covers the splenius, the in- 
ferior branch of the ilio-spinalis, and the common intercostal muscle. Nea 
its junction with the serratus magnus, its internal face adheres very 
closely to the transverse processes of the three first dorsal vertebre. 

Action.—It draws forward the superior extremity of the scapula, while 
the humeral angle is carried backwards. If the shoulder becomes the fixed 
point, it can act in the extension or lateral inclination of the neck. 


8. Splenius. (Figs. 105, 4,5; 106, 5.) 
Synonyms.—Cervico-trachelian — Girard. 


Form—Situation—A considerable muscle, flattened on both sides, 
triangular, and comprised between the cord of the cervical ligament, the 
inferior branch of the ilio-spinalis muscle, and the transverse processes of the 
four first cervical BB: vert ebrae 

Structure—The splenius, aponeurotic only at its periphery, is composed 
of thick fleshy fasciculi which are all directed forwards and upwards, to 
reach the head and the first cervical vertebra. 

Attachments.—It is fixed, by its posterior border, to the lip of the 
cervical ligament and the summits of the spinous processes of the first 
dorsal vertebra, by means of an aponecurosis which is ccntinuous behind 
with that of the small anterior serratus, and confounded, by its inner surface, 
with that of the great complexus. Its anterior border is cut into four or 
five digitations which constitute the movable insertions of the muscle: 
a, The superior digitation is the widest and thinnest, and terminates in an 
aponeurosis (Fig. 105, 5), which unites it to the mastoid tendon of the small 
complexus, and passes to the mastoid crest. b. The second joins a very 
strong tendon common to the splenius, the small complexus, and the 
mastoido-humeralis, which tendon is attached to the transverse process of 


tay 
Np 
we 


190. THE MUSCLES. 


the atlas (Fig. 105, 9). ¢, d. The two or three others are directly inserted 
into the transverse processes of the third, fourth, and fifth cervical 
vertebre. 
Relations.—The splenius is related, outwardly, to the rhomboideus, the 
angularis, cervical trapezius, and mastoido-humeralis ; inwardly, to the two 
complexus and two oblique muscles of the head ; by its inferior border, to 
the superior margin of the inferior branch of the ilio-spinalis (longissimus 


dorsi). 
ince extends the head and neck in inclining them to one side. If 
the two act in concert, the extension is direct. c 


Fig. 102. 


SUPERFICIAL MUSCLES OF THE NECK AND SPINAL REGION OF THE BACK AND LOINS. 

1, Dorsal trapezius; 2, Great dorsal; 3, Cervical trapezius; 4, Levator anguli 
scapule; 5, Splenius; 6, Anterior, or superficial portion of the mastoido-hume- 
ralis; 7, Its humeral insertion; 7’ Its mastoid insertion ; 8, The thin aponeurosis 
uniting this insertion to the sterno-maxillary, muscle; 8‘, Posterior portion of the 
mastoido-humeralis; 9, Its inferior a att inserted into the interstice of the 
long abductor of the arm; 10, Sterfio-maxillaris; 11, Subscapulo-hyoideus; 12, 
Portion of the dermal muscle of thé neck ; 13, Portion of the’ great extensor of 
the fore-arm; 14, Posterior belly of the long abductor of the arm; 15, Great 
pectoral muscle. 


MUSCLES OF THE TRUNE. 191 


4. The Great Complexus. (Fig. 106, 6, 7.) 


Synonyms.—Dorso-occipitalis—Girard. (Complexus major—Pereivall.) 


Situation—Direction—Form.—A powerful muscle, included between the 
internal surface of the splenius and the cervical ligament, whose oblique 
direction forwards and upwards it follows; it is triangular, flattened on both 
sides, elongated from before to behind, and divided longitudinally into two 
unequal portions—a posterior and anterior. 

Structure.—The posterior portion (Fig. 106, 6), the most considerable, 
is aponeurotic at its origin, intersected by linear fibrous bands which obliquely 
cross its direction, and is formed of fleshy fibres directed forwards. Those 
which compose the anterior portion (Fig. 106, 7), intermixed with some 
tendinous fasciculi, are directed upwards, and appear to be inserted into the 
preceding. It is this difference in the direction of the fibres of the two 
portions of the great complexus which allows them to be distinguished from 
one another; the two being only really separated by an interstice near their 
inferior extremity. Superiorly, the muscle is constricted to form the 
summit of the elongated triangle it represents, and terminates by a strong 
tendon. 

Fixed insertions.—The posterior portion derives its origin: 1, From the 
summit of the spinous processes of the first dorsal vertebre, by a strong 
aponeurosis which is confounded with that of the splenius and the anterior 
small serratus; 2, From the transverse processes of the four or five dorsal 
vertebrae which follow the second, by as many aponeurotic digitations united 
by their margins. The anterior portion is fixed: 1, To the transverse 
processes of the two first dorsal vertebra, by two tendinous digitations 
analogous to those of the posterior portion; 2, To the articular tubercles of 
the cervical vertebra’, by the inferior extremity of its fleshy fasciculi. 

Movable insertion.—The movable insertion of the great complexus is 
effected through its superior tendon, which is fixed to the posterior face of 
the occipital protuberance, beside the cervical tuberosity. 

Relations.—It is covered by the splenius and the small complexus. It 
covers the cervical ligament, the upper branch of the ilio-spinalis, the trans- 
verse spinous of the neck, and the oblique and posterior straight muscles of 
the head. The aponeurotic digitations which attach it to the dorsal trans- 
verse processes are comprised between the two branches of the ilio-spinalis. 
The interstice which separates, inferiorly, the two portions of the muscle 
affords a passage to the superior cervical artery. 

Action.—It is a powerful extensor of the head. 


5. Small Complexus. (Figs. 105, 6, 7; 106, 8, 9.) 


Synonyms.—Dorso-mastoideus— Girard. (Trachelo-mastoideus—Percivall.) 


Situatton—Direction—Situated at the internal face of the splenius, in an 
oblique direction upwavdé and forwards, this muscle lies along the anterior 
border of the great complexus, and follows the inferior branch of the ilio-, 
spinalis, which it appears to continue to the head. = 

Form—Structure—The small complexus is a long muscle, divided into 
two fleshy, fusiform, and parallel portions—anterior and posterior—which we 
might strictly consider as two distinct muscles. Both are composed of 
successive fasciculi, which become longer as they are superficial, and 

‘terminate by a tendon at their superiér extremity. The tendon of the 
posterior muscle is flattened, and joins the mastoid aponeurosis of the 


192 THE MUSCLES. 


splenius. That of the anterior muscle is funicular, and receives, before its 
insertion, a digitation from the splenius (fig. 106, 10), and another from the 
mastoido-humeralis (fig. 106). ; 

Fixed attachments.—The two fleshy portions of the small complexus have 
their fixed insertion in common with the anterior portion of the great com- 
plexus: 1, On the transverse processes of the two first dorsal vertebrae, 
through the medium of aponeurotic digitations which serve as an origin to 
the last-named muscle; 2, On the articular tubercles of the cervical vertebra, 
by the inferior extremity of their component fascicili, : 

Movable attachments.—The terminal tendon of the posterior muscle 
passes to the mastoid process of the temporal bone. The anterior passes to 
the transverse process of the atlas. 


LATERAL VIEW OF THE NECK; MIDDLE LAYER OF MUSCLES. 

1, Funicular portion of the cervical ligament; 2, Complexus major; 3, Complexus 
minor; 4, Rectus capitis posticus major; 5, Rectus capitis posticus minor; 6, 
Stylo-maxillaris; 7, Carotid artery; 8, Pneumogastric nerve and branch of 
sympathetic; 9, Longus colli; 10, Recurrent nerve; 11, Inferior scalenus; 12, 
Spinalis, or transversalis colli; 13, Incision through rhomboideus and trapezius ; 
14, Trachea, 


Relations.—Outwardly, with the splenius; inwardly, with the great 
eomplexus and the oblique muscles of the head. . The tendon of the posterior 
fleshy portion is covered by the mastoid aponeurosis of the mastoido- 
humeralis. en 


Action.—The small complexus inclines to its side the head and upper 
part of the neck. It also act: 3 an extensor of the head.? 


1 Bourgelat has described, by the name of long transversal, the anterior portion of this 
muscle, and attached it to the posterior portion of the splenius. We do not know 
where to find one or other of these in the crude description of Lafosse and Vitet. Girard 
considered them, like ourselves, as a single muscle, which he designates the dorso- 
mastoideus. Rigot has united them with the anterior portion of the great complexus and 
the foremost fasciculi of the short transverse muscle Ginferior branch of the ilio-spinalis), 
to make his long transversal; in doing so he has only complicated their description. 
These two muscular fusciculi, being, to our view, exactly represented, the posterior, at 


MUSCLES OF THE TRUNK. 193 


6. Transverse Spinous Muscle of the Neck. (Fig. 104, 4.) 


Synonyms.—Short spinous—Bourgelat. Dorso-spinalis—Girard. (Spinalis colli— 
Percivall. Transversalis colli of Man.) a 


Situation —Between the great complexus and the cervical ligament, on 
the lamine of the last five vertebra of the neck. ee 

Form—Structure—Attachments.—This muscle, a continuation in: the 
cervical region of that of the back and loins, is generally formedyof five 
thick and short fasciculi, strongly aponeurotic, directed forwards, upwards, 
and inwards. ae; 

These fasciculi, attached by their posterior extremities—fized insertion—to 
the five last articular tubercles of the cervical region, are fixed by thoir 
anterior or superior extremities—movable insertion—into the sixth, fifth, fourthy” 
third, and second spinous processes of that region. 

Relations.—Outwards, with the great. complexus; inwards, with the 
superior branch of the ilio-spinalis and the cervical ligament. By its 
anterior face, with the laminew of the cervical vertebra and the interlamellar 
ligaments. 

Action.—An extensor and flexor of the cervical spine. 


7. Intertransversal Muscles of the Neck. (Fig. 104, 9.) 


Synonyms.—Intercervicals— Girard. (The intertransversales of Man. Not mentioned 
by Percivall.) 


These are six small, short, and very tendinous fasciculi, each of which 
is doubled into two secondary fasciculi, a superior and inferior. They are 
lodged in the lateral excavations comprised within the transverse and artic- 
ular processes of the cervical vertebre, and are carried from one vertebra 
to another, except from the first to the second. Covered by the cervical 
attachments of the majority of the muscles of the neck, they cover the 
vertebre to which they are attached, as well as the vertebral arteries and 
_ veins, and the intervertebral foramen. They incline the neck to the side. 


8. Great Oblique Muscle of the Head. (Fig. 104, 7.) 


Synonyms.—Axoido-atloideus—Girard. (Obliquus capitis inferior—Percivall.) 


Form—Direction—Situation—A. short, thick, and broad muscle, oblique 
forwards and outwardly, and applied to the superior face of the two first 
vertebra of the neck. 

Structure and Attachments.—Its fibres are nearly all fleshy, parallel to 
each other, and longer as they become superficial ; they are attached by their 
posterior extremity—fixed insertion—to the external face of the spinous 
process of the axis, and by their anterior extremity—movable insertion—to the 
superior surface of the transverse process of the atlas. : 

Relations. —Outwards, with the splenius, the great and little complexus ; 
inwards, with the atlas, the axis, and the ptlo-axoid articulation ; above, 


least, by the small complexus of anthropotomists, we have thought it proper to give it. 
that name. With regard to the muscle generally termed | the small complexus by 
veterinary anatomists, following the example of Meckel we will describe it as a portion 
of the great posterior straight muscle of the head. ee 3 

(Percivall names Girard’s axotdo-occipitalis longus the “ complexus minbr,” and his 
dorso-mastoideus the “ trachelo-mastoideus.” Leyh, following Girard, designates the 
latter muscle the dorso-mastoideus.) 


194 THE MUSCLES. 


with the posterior straight muscles of the head; below, with the anterior 


eat straight muscle. : aor 
i ye al pivots the atlas on the odontoid process of the axis; it is, 


therefore, the special rotator of the head. 
Fig. 104, 


CERVICAL LIGAMENT AND DEEP MUSCLES OF THE NECK, 

1, Lamellar portion of the cervical ligament; 2, Funicular portion; 3, 3, The 
transversales muscle of the back and loins; 4, 4, Transversales of the neck; 5, 
Posterior great straight muscle of the head; 6, Small ditto; 7, Great oblique 
muscle of the head; 8, Small ditto; 9, 9, Intertransversales of the neck; 
10, Anterior great straight muscle of the head; 11, Inferior scalenus muscle; 
12, Superior ditto, 


9. Small Oblique. (Fig. 104, 8.) 


Synonyms.—Atloido-mastoideus—Girard. (Obliquus capitis superior—Percivall. 
Tiateral atloido-occipitalis of Leyh. Obliquus superior of Man.) 


A short, thick, quadrilateral, and strongly aponeurotic muscle. Its 
fibres are fixed posteriorly—origin—to the lip bordering the transverse process 


MUSCLES OF THE TRUNE. 195 


of the atlas; they are carried from thence forward, upward, and inward, to 
to be attached—termination—1, To the styloid process of the occipital bones ; 
2, To the external surface of that bone, on the imprints which border the 
mastoid crest posteriorly; 3, To the mastoid crest itself. This muscle is 
covered by the mustoid tendon of the small complexus, by the superior 
aponeurosis of the splenius, and that of the mastoido-humeralis. It covers 
the occipito-atloid articulation, the occipital insertion of the posterior 
straight muscles of the head, and the origin of the occipito-styloid and 
digastric muscles. It inclines the head on the atlas, and slightly extends it. 


10. Posterior Great Straight Muscle of the Head. (Fig. 104, 5.) 


Synonyms. —Small complexus and great posterior straight muscle—Bourgelat. Long 
and short axoido-occipitalis—Girard. (Complerus minor and rectus capitis posticus 
major.—Perecivall. Leyh gives this muscle the same designations as Girard. It is the 
rectus capitis posticus major and medius of Man.) 


Form—Structure—Situation—Elongated, prismatic, easily divisible into 
two fasciculi—one superficial, the complexus minor of Bourgelat (and Per- 
civall) ; the other deep, the great posterior straight muscle of Bourgelat (and 
the rectus capitis posticus major of Percivall)—entirely fleshy, and formed of 
parallel fibres, this muscle is lodged, with the small posterior straight 
muscle, in a triangular space circumscribed by the cord of the cervical liga- 
ment and the internal border of the oblique muscles. 

Attachments.—It is attached, by its superior extremity, to the whole 
extent of the uneven lip which terminates the spinous process of the axis— 
jixed insertion. Its anterior extremity is insinuated beneath the small 
oblique muscle, and is fixed to the occipital bone, behind the superior 
insertion of the great complexus, whose tendon receives some of the fibres 
of the superficial fasciculus—morable insertion. 

Relations.—Above, with the great complexus; below, with the small 
straight muscle ; inwards, with the cord of the cervical ligament and the 
analogous muscle of the opposite side; outwards, with the oblique muscles. 

Action—This muscle, a congener of the great complexus, aids in 
extending the head. 


11. Small Posterior Straight Muscle. (Fig. 104, 6.) 


Synonyms.—Atloido-occipitalis—Girard. (Rectus capitis posticus minor—Percivall. 
. The Atloido-occipitalis superior of Leyh. The rectus capitis posticus minor of Man.) 


A very small, wide, and triangular muscle, flat above and below, and lying 
immediately upon the fibrous capsule of the occipito-atloid articulation. It 
is attached, posteriorly, to the superior face of the atlas—origin ; in front, to 
the external surface of the occipital bone, below the preceding muscle, whose 
action it shares. 


B. Inferior Cervical or Trachelian Region. 


The muscles composing this region are situated in front of the cervical 
vertebre, and are, for the most part, grouped around the trachea, which they 
envelop as in a kind of sheath. They are eleven in number : the cuticular 
muscle of the neck, the mastoido-humeralis, sterno-maaillaris, sterno-hyoideus, 
sterno-thyroideus, omo- or’ subscapulo-hyoideus, the great and small anterior 
straight muscles of the head, the small straight lateral muscle, the scalenus, and. 


the long muscle of the neck. 


196 THE MUSCLES. 


Preparation.—1. Place the animal in the first position, 2. Remove the skin of this 
region, in order to expose and study the cuticular muscle, 3. Remove that muscle 
and the parotid gland to prepare the mastoido-humeralis, the stylo-maxillaris, sterno- 
hyoideus, and sterno-thyroideus, 4. Transversely cut through the mastoido-humeralis 
near the angle of the shoulder, and isolate it from the subscapulo-hyoideus to expose 
this muscle; taking care to preserve the jugular vein and parotid gland, in order to study 
their relations with it. 5. Remove the fore limbs; open the thoracic cavity by sawing 
through the eight first ribs near their superior extremity ; take out the viscera contained 
in this cavity, as well as the trachea, cesophagus, pharynx, and larynx, to expose the 
long muscle of the neck, the scalenus, and the straight muscles of the head. 


1. Subcutaneous Muscle of the Neck. (Figs. 102,12; 114, 1.) 


Synonyms.—It has been described by Bourgelat, and the majority of veterinary 
anatomists who have followed him, as two muscles: the cuticularis of the neck and the 
face. (Percivall includes this muscle in his description of the panniculus carnosus.) 

This is a membraniform expansion, partly fleshy, partly aponeurotic, 
which covers the muscles of the neck, the intermaxillary space, and the 
face. 

The fleshy fibres form, in front of the neck,a thin band, which is united, 
through the medium of a fibrous raphé, to that of the opposite side. This 
band is in contact with the sterno-maxillary, sterno-hyoid, subscapulo-hyoid, 
and sterno-thyroid muscles, as well as the jugular vein: enveloping them 
all as in a sort of gutter. It gradually thins from below upwards, in such a 
manner that around the upper part of the throat itis only composed of some 
scattered fibres. In the intermaxillary space, and on the expanding borders 
of the maxillary branches, the fleshy fibres appear again of a certain 
thickness, but only to become attenuated on the external surface of the 
cheeks. 

These fleshy fibres leave the anterior prolongment of the sternum? and 
intermediate middle raphé of the two muscles, and directing their course 
outwards and upwards, soon become confounded with the aponeurosis. The 
latter, extremely thin, is spread over the mastoido-humeralis, the superior 
cervical muscles, parotid region, and the cheeks, and is finally attached to 
the zygomatic crest. On arriving near the commissure of the lips, the 
cuticular muscle is united to the alveolo-labialis (or buccinator muscle) by 
a fleshy fasciculus named, in Man, the risorius santorini (Fig. 110, 24). 

The cuticularis colli braces the muscles it covers during their contraction 
and pulls backwards the commissures of the lips. We doubt very much 
whether it has, in the cervical region at least, any action on the skin, for it 
adheres but very slightly to its inner surface. 


2. Mastoido-humeralis. (Figs. 102, 105, 106, 114.) 


Synonyms.—The muscle common to the arm, neck, and head—Bourgelat. Repre- 
senting the cleido-mastoid, and the clavicular portions of the trapezius and deltoid of 


' The mastoido-humeralis may be dissected at the same time as the trapezius, the 
subject being placed in the second position. This conveniently permits the superior 
insertions of the muscle to be studied. (See fig. 102). 

* It will be seen, on referring to figure 114 and its legend, that we restore to the 
cuticular muscle of the neck the sternal band attributed until now to the mastoido- 
humeralis. These are the considerations which induce us to make this modification : 
1, This band is not distinct from the cuticularis of the neck; a separation between the 
two muscles can only be artificially obtained. 2, In dissecting this band with care, we 
can see that its fibres, like those of the cuticularis, are not mixed with those of the 
mastoido-humeralis (superficial portion); they pass along the external surface of that 
muscle, to which they intimately adhere, it is true, but they can easily be separated, aid 
are continuous with the aponeurosis of the first, 


MUSCLES OF THE TRUNK. 197 


Man, and the trachelo-acromialis peculiar to quadruped mammals'—G. Cuvier, ‘Lecons 
d' Anatomie Comparée,’ 2nd edition. (This is the muscle which Percivall names the 
levator humert. ‘The above is the designation given to it by Girard and Chauveau, 
Leyh gives it the same designation as Bourgelat.) 


Extent—Situation—Direction—Composition—This muscle extends from 
the summit of the head to the inferior part of the arm, and is applied to the 
scapulo-humeral angle at the side of the neck, in an oblique direction down- 
wards and backwards. It is composed of two portions lying longitudi- 
nally and somewhat intimately united, and distinguished into anterior and 
postertor. 

Form—Structure—Attachments.—A. The anterior or superficial portion 
(Fig. 106, 6) constitutes a long fleshy band, which appears to be united, by 
its anterior border, to the cuticular muscle of the neck. Its superior 
extremity, thin and wide, is attached to the mastoid process and crest by an 
aponeurosis (Fig. 102, 7), which is united, in froni, to the tendon of the 
sterno-maxillaris by a very thin cellulo-aponeurotic fascia. Its inferior ex- 
tremity, thicker than the superior, is inserted by means of a very short 
aponeurosis into the humerus, on the salient border descending from the 
deltoid imprint, and which limits, in front, the furrow of torsion on the 
body of that bone (Fig. 102, 7). 

B. The posterior or deep portion (Fig. 102, 9) is 9 second muscular band, 
shorter and stronger than the preceding. It is attached, above, to the 
transverse processes of the first four cervical vertebrae by as many fleshy bands 
(Fig. 102, 8’), which cover the superficial portion. The upper digitation, 
given off to tue atlas. is united to the tendon common to the small complexus 
and splenius (Figs. 105, 9; 106, 9', 10,11). The inferior extremity of this 
portion of the muscle widens on the scapulo-humeral angle, which it 

‘envelops in becoming closely united to the anterior portion, terminating 
with it on the humerus. An aponeurosis, which is confounded with that of 
the trapezius, and sends off a septum into the interstice between the two 
portions of the long abductor of the arm, concurs to fix this extremity by 
spreading over the muscles of the arm. 

Relations.—It is covered, near its mastoid insertién, by the.parotid gland 
and the cervico-auricularis muscles; for the remainder of its extent, by the 
aponeurosis of the cuticularis colli, from which it isjseparated by a thin 
fascia continuous with that which extends over the trapezius. It covers the 
splenius, the small complexus, the oblique muscles of the head, subscapulo- 
hyoideus (to which it adheres intimately), the digastricus, long flexor of the 
head. the angularis, scalenus, small pectoral, supra- and infraspinatus, the 
long abductor of the arm, and the coraco-radialis. i 


1 At first sight we might hesitate to admit that this muscle is formed of such varied 
and complicated elements as are enumerated above. Nevertheless, it is a scientific fact; 
and we will give a demonstration, as simple as it is clear, that such is the case—the 
idea we owe to J. F. Meckel. If we take the Dog, for example, and suppose it to be 
possessed of a clavicle extending from the anterior extremity of the sternum to the 
acromion; this clavicle would cut, transversely, the inferior portion of the mastoido- 
humeralis, which would thus be divided into two portions, a superior and an inferior. 
The first, extending from the clavicle to the mastoid process, on this side, and on the 
other to the mastoid crest, as well as to the cervical ligament, where it is confounded with 
the trapezius, would exactly represent the elavicular portion of the latter muscle, and 
the cleido-mastoideus. With resyect to the inferior portion, it perfectly resembles, by its 
attachments, the clavicular portion of the deltoid. But, on the contrary, if we suppose 
Man deprived of a clavicle, the three muscular fasciculi indicated, in becoming con- 
founded with each other, would form the mastoido-humeralis of the Dog, minus the 
posterior portion, or the trachelo-acromialis, which is not represented in Man. 


+ 


198 THE MUSCLES. 


Action.—When the superior is the fixed point, it carries the entire 
anterior limb forward. This muscle, therefore, plays a very Important 
part in locomotion; as it is called into action when the animal raises the 
fore-limb in getting over the ground. If the fixed point éf the muscle 
is the limb, it inclines the head and neck to one side. 


3. Sterno-mawillaris. (Figs. 102, 10; 114, 4.) 


Symonym.—The sterno-mastoideus of Man and a large number of the lower animals. 


Form—Structure—Situation—Direction—Attachments.—A long narrow 
muscle, almost entirely fleshy, and terminated at its upper extremity by a flat- 
tened tendon; situated in front of the neck, beneath the cuticularis, and 
parallel to the anterior border of the superficial portion of the mastoido- 
humeralis, from which it is separated by a space that lodges the jugular 
vein ; attached, inferiorly, to the cariniform cartilage of the sternum—fixed 
insertion ; and superiorly—movable insertion—to the curved portion of the 
posterior border of the maxillary bone by its terminal tendon. 

Relations.—The muscle is covered by the cuticularis colli, and the 
parotid gland. It covers the trachea, the subscapulo-hyoideus, sterno- 
hyoideus, sterno-thyroideus, and the maxillary gland. Its external border, 
parallel to the anterior border of the mastoido-humeralis, forms with it a 
longitudinal depression termed the jugular furrow, because it lodges the 
vein of that name. Its inner border is intimately united, in its lower third, 
to that of the opposite muscle. 

Action.—It directly flexes the head, when acting in concert with its 
congener; but alone it turns it to one side. Lafosse and Rigot have wrongly 
eonsidered this muscle as a depressor of the lower jaw. Bourgelat has 
correctly stated that it cannot move this jaw independently. (Percivall says 
that the pair will assist in opening the mouth; and Leyh asserts that when 
the mouth is closed, each muscle will act as a flexor to the head.) - 


4, Sterno-hyoideus.—5. Sterno-thyroideus. (Fig. 114, 6, 7.) 
i (Synonym.—The sterno-thyro-hyoideus of Percivall.) 


Form—Structure—Situation—Attachments——Small, ribbon-shaped, long, 
and slender muscles ; digastric ; situated in front of the trachea ; confounded 
at their inferior extremity and united to those of the opposite side, so as to 
form a single fasciculus which is attached to the cariniform cartilage of the 
sternum—fiwed insertion ; isolated from each other above the tendon which 
makes them digastric, and terminating by their superior extremity-—movable 
insertion : the first, on the inferior surface of the body of the hyoid bone in 
common with the subscapulo-hyoideus ; the second, on the posterior border 
of the thyroid cartilage. 

Relations.—Covered by the sterno-maxillaris and the cuticularis muscle, 
they cover the anterior face of the trachea. 

Aclion.—Depressors of the hyoid bone and larynx, 


6. Omo-hyoideus or Subscapulo-hyoideus. (Figs. 102,11; 114, 5.) 
Synonyms.—Hyoideus—Bourgelat. (Subscapulo-hyoideus—Perctvall.) 
Form—Structure —Situation—Direction—This muscle forms a thin and 

wide band, almost entirely fleshy, oblique forwards and upwards, extending 


from the scapulo-humeral angle to the intermaxillary space, and applied to 
sthe side of the trachea, whose direction it slightly crosses. 


MUSCLES OF THE TRUNK. 199 


Attachments.—It derives its fixed insertion from the inner surface of the 
subscapularis, by an aponeurosis which is detached from that covering the 
latter muscle. Its movable insertion is into the body of the hyoid bone, in 
becoming confounded with the sterno-hyoideus, and in being intimately 
united to the muscles of the opposite side. 

Relation—Outwardly, with the «subscapularis, supraspinatus, small 
pectoral, mastoido-humeralis—which closely adheres to it, the jugular vein, 
the sterno-maxillaris, and the cuticularis. Inwardly, with the scalenus, the 
large anterior straight muscle of the head, the main trunk of the carotid 
artery and the nerves accompanying it, the trachea, thyroid gland, and the 
inferior face of the larynx. The jugular vein is entirely separated from 
the carotid artery by this muscle in the upper half of the neck. 

Action,—It is a depressor of the hyvid bone and its appendages. 


7. Great Anterior Straight Muscle of the Head. (Figs. 104 and 105, 10 5 
106, 13.) 

Synonyms.—Long flexor of the head—Bourgelat. Trachelo-suboccipitalis— Girard. 
(Rectus capitis anticis major—Percivall. Trachelo-occipitalis—Leyh.) 

Form—Structure—Situation —Direction.— A long, flat muscle, fascicu- 
lated in its posterior half, terminated in a tendinous cone at its anterior. 
extremity, and passing along the first cervical vertebre in front. 

Attachments.—Behind, to the transverse processes of the third, fourth, 
and fifth cervical vertebre by as many fleshy digitations, the most inferior 
of which are the longest—fixed insertion. In front, into the imprints on the 
body of the sphenoid bone and the basilar process, by its terminal tendon— 
movable insertion. 

Relations—Outwardly, with the mastoido-humeralis, the subscapulo- 
hyoideus, and the small anterior straight muscle. Inwardly, with the long 
muscle of the neck and the muscle of the opposite side. In front, with the 
common carotid, the nerves accompanying this artery, and the guttural 
pouch, which lines it near its movable insertion. Behind, with the great 
oblique muscle of the head and the occipito-atloid articulation. 

Action.—It either directly flexes the head or carries it to one side, 
according as it acts alone or with its fellow of the opposite side. 


8. Small Anterior Straight Muscle of the Head. 


“Bynonyms.—Flexor capitis brevis—Bourgelat. — Atlvido-suboccipitalis— Girard. 
(Rectus capitis anticus minor—Percivall. Atloido-oceipitalis inferior—Leyh.) 


A small, entirely fleshy, prismatic fasciculus, lying to the external side 
of the preceding muscle; attached, posteriorly, to the inferior face of the 
body of the atlas ; in front, to the body of the sphenoid bone and the basilar 
process, beside the great anterior straight muscle. It is covered by the 
guttural pouch, and covers the occipito-atloid articulation. It concurs in 
flexing the head. 


9. Small Lateral Straight Muscle. 


Synonyms.—Flexor capitis parvus—Bourgelat. Atloido-styloideus—Girard, (Obli- 
quus capitis anticus—Percivall. The rectus capitis lateralis of Man.) 


Yet smaller than the preceding, and prismatic and entirely fleshy, like it 
this muscle lies on the side of the occipito-atloid articulation ; it is attached 
to the atlas, outside the small anterior straight muscle—fixed insertion ; and 
to the inner face of the styloid process of the occipital bone—movable insertion. 
It is the congener of the two anterior straight muscles of the head. 


200 THE MUSCLES, 


10. Scalenus. (Figs. 104, 105, 106.) 


Synonyms.—Costo-tracheleus—Girard. (Scalenus anticus and posticus of Man.) 


Sttuation — Direction—Composition.—Deeply situated at the inferior 
part of the neck, in an oblique direction downwards and backwards, this 
muscle comprises two portions of unequal dimensions, placed one above 
another. . 

Form—Structure—Attachments.— A. The superior portion (scalenus posti- 
cus of Man), the smallest, is composed of three or four fleshy fasciculi, attached 
by their extremities to the transverse processes of the last three or four 
cervical vertebre. The last terminates at the superior extremity of the 
first rib. 

B. The inferior (scalenus anticus of Man), the most considerable, is 
flattened on both sides, thick and wide posteriorly, thin and narrow 
anteriorly, and is composed almost entirely of fleshy fibres which are longest 
as they are inferior. It is attached: 1, To the transverse processes of the 
last four cervical vertebre by short fasciculi scarcely distinct from one 
another, the first of which is crossed by the last digitation of the great 
anterior straight muscle; 2, To the anterior border and external face of the 
first rib, where all its fibres end. 

Relations.—The scalenus responds: by its external face, to the sub- 
scapulo-hyoideus, mastoido-humeralis, and the sterno-prescapularis; by its 
internal face, to the longus colli, trachea, common carotid artery and its 
accompanying nerves, and—on the left side only—to the cesophagus; by its 
inferior border, to the jugular.vein. The two portions of the scalenus are 
separated from one another, in front of the first rib, by an interspace 
traversed Ly the nerves of the brachial pléxus. 

Action.— When the first rib is the fixed point, this muscle either directly 
flexes the neck or inclines it to one side. When the neck is the fixed point, 
it draws forward the first rib and fixes it in this position during the 
dilatation of the chest, in order to aid the inspiratory action of the external 
intercostal muscles. € 


11. Long Muscle of the Neck. 


Synonyms.—Flexor longus colli—Bourgelat. Subdorso-atloideus—Girard. (Longus 
collig- Percival, Dorso-atloideus—Leyh.) 


/ Situation—Composition—A single and considerable muscle, immediately 
covering the inferior aspect of all the cervical and the first six dorsal 
vertebrae, and composed of two lateral portions which are united on the 
median line, and constitute, in certain animals, two distinct muscles. 

Structure—Attachments.—Kach lateral portion of the longus colli is 
composed of a succession of very tendinous fasciculi. The most posterior of 
these is attached to the inferior face of the bodies of the first six dorsal 
vertebre, and proceeds directly forward to reach the inferior tubercle of the 
sixth cervical vertebra, into which it is inserted by a strong tendon. The 
other fasciculi, less considerable, and confounded outwardly with the inter- 
transversales of the neck, are carried from one cervical vertebra to another, 
and are directed forwards, upwards, and inwards, in converging towards those 
of the opposite side. They are attached successively : outwardly, to the 
transverse processes of the last six cervical vertebra; inwardly, to the 
inferior ridge on the bodies of the first six. The most anterior fasciculus 
passes to the inferior tubercle of the atlas, into which it is inserted by a 


MUSCLES OF THE TRUNE. 201 


tendon common to it and the fasciculus of the opposite side, and which 
receives the most superficial fibres of the three or four preceding fasciculi. 

Relations——Above and behind, with the vertebree which it covers, as 
well as their intervertebral discs; below and in front, with the trachea 
and cesophagus, and the vessels and nerves accompanying these two tubes; 
on the sides, with the great anterior straight and the scalenus muscles in its 
cervical portion, and in its intrathoracic portion, with the pleurw, and 
important vessels and nerves. 


Action.—It flexes the whole neck, and the cervical vertebra on one 
another. 


DIFFERENTIAL CHARACTERS OF THE MUSOLES OF THE CERVICAL REGION IN OTHER THAN 
SOLIPED ANIMALS, 


A. Superior Cervical Region. 


1. Buminants.—In the Oz, the angularis arises by six digitations from all the cervical 
vertebrae except the first; the eg is little developed, and is not attached to either 
the third or fourth cervical vertebra. 

2. Pic.—The muscles of the superior cervical region in this animal are generally 
very developed. The rhomboideus is divided into two fleshy bodies, one of which proceeds 
to the occipital protuberance, and the other to the rudimentary cervical ligament and 
the first dorsal vertebre. The angularis is attached, as in Ruminants, to the six cervical 
vertebre ; sometimes it even shows a digitation that descends to the atlas. The splenius 
only terminates anteriorly by three fleshy bodies; but they are voluminous, and are 
inserted, one into the atlas, another into the mastoid crest, and the third into the occipital 
protuberance. In the great complexus, the two portions are completely separated from 
each other, except at their upper extremity, by the interspace lodging the superior 
cervical artery. The aponeurosis attaching the muscle to the spinous processes of the 
first dorsal vertebrae is not confounded with that of the splenius or the small anterior 
serrated respiratory muscle. The atloidean fleshy body of the small complexus is scarcely 
distinct from the superior branch of the ilio-spinalis and the intertransversales. Lastly, 
it is difficult to distinguish the small posterior straight muscle from the deep fasciculus 
of the great straight muscle. 

3. Garnivora—In these animals the muscles of the superior cervical region are 
nearly all voluminous, as in the Pig. The rhomboideus is bifid at its origin, and its 
anterior branch arises from the mastqid crest. The angularis is also attached to the last 
six cervical vertebre. Very thick and bread, the splenius only passes to the atlas and 
ee crest. The oblique and straight posterior muscles of the head are also remarkably 
thick. 


B. Inferior Cervical or Trachelian Region. 


1, Rummwants—In the Ox and Sheep, the disposition of the cuticularis colli offers 2, 
very considerable difference from that observed in Solipeds. The fleshy portion is 
absent, or appears to be absent, in the cervical region; the anterior muscles of the neck 
are only covered by a thin fascia developed on the sides of the neck. When this 
fascia reaches the face, it becomes continuous with the fleshy fibres; a fasciculus of 
these fibres comports itself as in the Horse, and goes to join the alveo-labialis; another 
is intercrossed in the maxillary space by the analogous fasciculus of the opposite 
side. 

The cervical cuticularis muscle of the Ox is also distinguished by an extremely 
remarkable peculiarity which it is necessary to allude to here :—The fleshy cervical band, 
altogether absent in the Sheep, is not so in the Ox; we have found it forming, beneath 
the above-mentioned aponeurotic.fascia, the long, thick strip which has been described 
by veterinary anatomists a3 the analogue of the sterno-maxillaris in the Horse. This 
strip is attached, like the muscular band which represents it in Solipeds, to the anterior 
point of the sternum. But its fibres, instead of being spread outwards over the mastoido- 
humeralis, ascend, perfectly isolated from that muscle, to the posterior border of the 
mavxillaris. There it terminates (Fig. 112, 18) by a flattened tendon which, after reaching 
the anterior border of the masseter, is confounded with the apoueurosis of that muscle, 
and sends some fibrous bands over the muscles of the face. 

The two portions of the mastoido-humeralis of Ruminantsare better defined, and more 
oblique on one another, than in the Horse, The superyicial portion receives on its inner 


202 THE MUSCLES. 


face a small, bright-red, funicular fasciculus, which proceeds from the cartilage of the 
first rib, and which Meckel is inclined to consider as the vestige of the subclavius. It 
is divided, superiorly, into two branches: one, the clavicular portion of the trapezius, 
very wide, passes to the mastoid process, the curved line of the occipital bone, and to the 
cervical ligament, in becoming confounded with the trapezium (Fig. 112, 22); the other, 
the eleido-mastoideus, terminates in a tendon that joins the sterno-suboccipitalis, and is 
inserted into the basilar process, after receiving the fibres of the long flexor of the head 
(Fig. 112, 21), The upper extremity of the deep portion of the mastoido-humeralis is 
inserted into the atlas by a flattened tendon alone, which is quite distinct from the atloid 
insertions of the splenius and the small complexus, : 

In the Sheep and Goat, the costal band that joins the superficial portion is absent. 
"The latter is divided at its inferior extremity into two branches, between which pass the 
biceps. The upper branch passes to the epitrochlea, 

The sterno-maxillary muscle, instead of being inserted into the inferior maxilla, is 
united to the suboccipital branch of the mastoido-humeralis, to be attached to the basilar 
process. At another time we will discuss the determination of this muscle, and that of 
the fleshy band here considered as belonging to the first (see Spinal Nerve). 

a Ze sterno-hyoid and sterno-thyroid muscles are thicker than in the Horse, and not 
gastric. 

The subscapulo-hyoideus of Ruminants ig but slightly developed, and might be termed 
the trachelo-hyoideus ; as it proceeds to the tiansverse process of the third or fourth 
cervical vertebra. In its passage beneath the basilar branch of the mastoido-humeralis 
on Seas (sterno-maxillaris), it contracts adhesions with the fibres of these 

wo muscles. 

The great anterior straight muscle of the head descends to the sixth cervical vertebra 
Tts cervical insertions are covered by a very strong muscular fasciculus, which is annexed 
to it. Like it, this fasciculus leaves the sixth cervical vertebra, and’ is attached to the 
transverse processes of the four vertebra preceding the last, by becoming confounded 
with the intertransversales, and finally terminating at the tracheal process of the atlas by 
fleshy and aponeurotic fibres. This muscular fasciculus singularly strengthens the neck 
when it is inclined to one side. In consequence of its attachments, it might be named the 
trachelo-atloideus (Fig. 112, 24). 

Lastly, in Ruminants the superior scalenus is very developed, being a flattened band 
which, gradually expanding, is prolonged to the surface of the serratus magnus. 

2. Pra.—In this animal, the cuticularis colli is in two portions: an inferior, which 
comes from the point of the sternum ; and a superior, from the external scapular region, 
They unite in front, and are prolgmged in common on th 1 f a 
tracting adhesions with the external + of th ee 
pene alagpect of the body and the branches of the maxillary 

The other muscles of the inferior cervical regi : ik i 

Of the two portions of the Ca nacaat Me oe ee genre 
extremity. The posterior branch, the clavicular ‘portion of the tr nl att a e 
the side of the occipital protuberance; the anterior branch, th ces eietias He 
beneath the external auditory hiatus, to the crest that re lace: th nen ere te enn 
= pings is attached above to the atlas only. ab iaat oy es cial 

n the Pig, the sterno-maxillaris exact. y i i 
tendon passes directly to the mastoid Rae a Cae 
a a - ee a aca is double; the supplementary branch going to the inferior face 

The subscapulo-hyoideus and great anteri i 
piace lean WY acid hha! Sul ia ag Sas muscle of the head, resemble those 
ad ; : is scarcely distinct from the small oblique. 

he supertor scalenus extends to the third rib, The two lateral porti f the l 
re Gt the neck are separate, and form two distinct muscles ies ae 
_ 3 ARNIVORA.—In the Dog, each cuticularis i in i i 
Pig. The fibres from the beat are directed in a ae eee aa a eee ciety 
maxillary space, and the parotid gland, where they form th otters ci ae 
The portion coming from the external scapular region i nee : aged epee pat 
the st ates ene of the neck, the parotid gland, ee cecae un i oS ea 
receding, an rmi i f ‘ ‘ 
joi those i rik gree ese Os the face and in the submaxillary space, where its fibres 
he mastotdo-humeralis comports itself s i i i 
Helga ss is bifid snperierly ; one of sak Re eee dies velar ap feed 
e cleido-mastoideus ; the other into the mastoid crest a ical li i iting 
by aponeurosis with the trapezius— y in eae eae Pt eee 
portion passes from the atta’ to the ee BO Ce eer eee 


MUSCLES OF THE TRUNK. 203 


The tendon of the sterno-mazillaris goes to the mastoid process. The sterno-hyoideus 


net thyroideus axe thick and not digastric, and commence from the cartilage of the first 
ri 


The Carnivora have no subscapulo-hyotdeus ; but they possess a very long scalenus, 


which passes to the eighth rib, and a long muscle of the neck, which tend 
divided into two lateral portions, : . ss a ee 


SPINAL REGION OF THE BACK AND LOINS. 


This offers for study eight pairs of muscles, nearly all of which have 
their insertions extended over the dorso-lumbar spine, and are disposed in 
several layers on each side of this long multifidious crest. These muscles 
are, enumerating them according to their order of superposition: 1, The 
trapezius; 2, Great dorsal ; 3, Small anterior respiratory serratus ; 4, Small 
posterior serratus ; 5, Ilio-spinalis (longissimus dorsi); 6, Common intercostal ; 
7, Transversales of the back and loins (semispinalis dorsi and lwmborum). 


Preparation.—1. Place the animal in the second position. 2. Remove the skin 
with the panniculus and the mass of olecranian muscles, to show, in a first operation, the 
trapezius and great dorsal muscles (Fig. 102). 3. In a second operation, remove the 
entire fore-limb, wita the great dorsal muscle, whose mode of termination may then be 
studied ; then prepare the two small serrated muscles. 4. Remove these two muscles, as 
well as the angularis of the scapula and the splenius, to expose the common intercostal 
and ilio-spinalis (Fig. 106). The superior branch of the latter remaining covered by the 
great complexus, excise this muscle, leaving only its insertions into the transverse 
processes of the dorsal vertebre, to show how tiey are fixed between the two branches 
of the ilio-spinalis (longissimus dorsi). 5. Dissect the transversales (semispinalis) by 
removing the ilio-spinalis and the internal angle of the ilium. 


1. Trapezius. (Fig. 102, 1, 3.) 
Synonym.—Dorso- and cervico-acromialis—Girard. 


Situation—Form—Structure-—This is a superficial membranous muscle, 
situated on the sides of the neck and withers, Its shape is that of a triangle 
whose base is upwards. It is aponeurotic, rt its upper border and in its 
centre, which allows it to be distinguished, especially in emaciated subjects, 
into a cervical and a dorsal portion. The fleshy fibres of the first are 
directed downwards and backwards; those of the second are oblique 
forwards. 

Attachments —By its superior aponeurosis, it is fixed to the cervical cord 
and to the summits of the teammrexse-processes of the first dorsal vertebra, ¢ 
where it adheres to the external face of the great dorsal muscle. By~ 
its central aponeurosis and that of its summit, it is attached to the tuberosity _, 
of the @keemamiaar spine and the external scapular aponeurosis. ©) 

Relations.—This muscle is covered by two aponeurotic planes, whose « 
fibres cross its own at aright angle. Inwardly, it responds to the rhom- 
boideus, splenius, angularis, sterno-prescapularis, the supra- and infra- 
spinatus, and the great dorsal. 

‘Action.—It raises the shoulder, and carries it forward or backward, 
according as one or other of its muscular portions contract. 


2. Great Dorsal. (Fig. 102, 2.) 
~ synonyms.—Dorso-humeralis— Girard. (Latissimus dorsi—Pereivall.) 
Form—Situation—Structure—Attachments—A very broad triangular 
muscle, extended over the loins, back, and side of the thorax, and formed of . 


an aponeurotic and a muscular portion. ; 
The aponeurosis is attached, by its superior border, to the summits 


204 THE MUSCLES, 


of the spinous processes of all the lumbar and the last fourteen or fifteen 
dorsal vertebrae—fived insertion of the muscle, : : 

The fibres of the fleshy portion are detached from the inferior border 
of the aponeurosis, at the twelth or thirteenth ribs, to the cartilage of 
the scapula. They are directed forwards and downwards, and all converge 
into a flat tendon which is inserted into the internal tuberosity on the 
body of the humerus—movable insertion. This tendon is remarkable, at its 
termination, for being placed at the external face of the teres magmis or 
adductor of the arm, from which it receives fibres, and between it and the 
long extensor of the fore-arm ; it then turns inwards, on the inferior 
extremity of the first, in such a manner that this extremity is comprised 


Fig. 105. 


MUSCLES OF THE SPINAL REGION OF THE NECK, BACK, AND LOINS, MIDDLE LAYER; 
AND OF THE COSTAL AND ABDOMINAL REGION, SUPERFICIAL LAYER. 

1, 2, Rhomboideus ; 3, Angular muscle of the scapula; 4, Splenius; 5, Its mastoid 
aponeurosis ; 6, Mastoid portion of the small complexus; 7, Its tendon; 8, Cer- 
vical insertions of the mastoido-humeralis; 9, Atloidean tendon common to the 
mastoido-humeralis, splenius, and small complexus; 10, Great anterior straight 
muscle of the head; 11, Inferior scalenus; 12, Superior scalenus; 13, Small 
anterior serratus; 14, Posterior ditto; 15, Great serratus; 16, Transverse 
muscle of the ribs; 17, One of the external intercostals; 18, Great oblique - 
muscle of the abdomen; 20, Straight muscle of the abdomen; 21, Stylo-maxil- 
lary portion of the digastric muscle. 


within a duplicature of the membranous tendon of the latissimus dorsi 
(Fig. 121). 

Relations—This muscle is covered by the skin, panniculus carnosus, 
dorsal portion of the trapezius, and the mass of olecranian muscles. It 
covers the infraspinatus; the cartilage of the scapula; the rhomboideus; 
the small anterior and posterior serrated muscles, whose aponeurosis is 
directly joined to its own; the ilio-spinalis; the principal gluteal ; a portion 
of the external surface of the last ribs, to which its aponeurosis strongly 
adheres; as well as the corresponding external intercostals, and the great 
serrated muscle. Between the last rib and the external angle of the ilium, 


MUSCLES OF THE TRUNK. 205 


the aponeurosis unites with the small oblique, but more particularly with 
the great oblique, muscle of the abdomen ; it is prolonged, posteriorly, on 
the muscles of the croup to constitute the gluteal aponeurosis. 

Action.—It carries the arm backwards and upwards; and it may, 
cecording to & great number of authors, serve as an auxiliary in inspiration 
when its fixed point is the humerus. According to others, but in whose 
opinion we do not share, it is an expiratory muscle. 


3. Small Anterior Serrated Muscle. (Fig. 105, 18.) 


Synonyms.—Dorso-costalis—Girard, Anterior portion of the long serrated muscle 


—Bourgelat. (Superficialis costarum—Percivall. Anterior serrated muscle of Leyh. 
Serratus posticus superior of Man.) 


Form—Situation.—This is a flat, thin, and quadrilateral muscle, situated 
beneath the rhomboideus and the great dorsal muscle. 

Structure.—It is composed of an aponeurotic and a fleshy portion. The 
first is confounded, in front, with the aponeurosis of the splenius, and is 
insinuated, behind, underneath that of the posterior small serratus, with 
which it soon becomes united. Its inferior border gives origin to the muscular 
portion, a little above the interval which separates the common intercostal 
and the ilio-spinalis. Narrow and elongated antero-posteriorly, the muscular 
portion is composed of bright-red fibres directed obliquely backwards and 
downwards, and which form at the inferior border irregular, and sometimes 
but faintly marked, festoons. 

Aitachments.—It takes its fixed insertion, by the superior border of its 
aponeurosis, from the summits of the antericr dorsal spines, with the 
exception of the first, to the thirteenth inclusive. The movable insertion 
takes place on the external surface and anterior border of the nine ribs 
succeeding the fourth, by means of the digitations of the fleshy portion. 
This muscle is also attached to the external surface of these ribs by a short 
fibrous band, which is detached from the internal face of the aponeurosis, 
near its inferior border, and penetrates the space between the ilio-spinalis 
and the common intercostal muscle. 

Relations —Outwards, with the rhomboideus, great serratus, great dorsal, 
and the posterior small serratus, which covers its three last festoons ; 
inwards, with the ilio-spinalis, the common intercostal, and the external 
intercostals. 

Action.—This is an inspiratory muscle, and it also serves as a check to 
the deep spinal muscles. 


4, Small Posterior Serrated Muscle. (Fig 105, 14.) 


‘Synonyms.—Lumbo-costalis— Girard. Posterior portion of the long serrated muscle 
—Bourgelat. (Superficialis costarum—Pereivall. The posterior serrated muscle of Leyh, 
The serratus posticus inferior of Map.) 

Situation Situated behind the preceding, which it follows, and present- 
ing the same form and arrangement, this muscle also offers the following 
particular features for study : aoe 

1. Structure—Its muscular portion, which is thicker and of a deep-red 
colour, is cut into nine well-defined digitations.' The fibres which compose 
it run in an almost vertical direction. 

9, Attachments.—Its aponeurosis, closely united to that of the great dorsal 
muscle, which covers it, is attached to the spinous processes of the dorsal 


1 It frequently happens that only eight digitations are found. 


206 THE MUSCLES. 


vertebre after the tenth, and to some lumbar vertebre. Its digitations 
are fixed to the posterior border and external face of the nine last ribs. 

3. Relations. —Outwards, with the great dorsal; inwards, with the 
small anterior serratus, the ilio-spinalis, common intercostal, and the 
external intercostals. Some of its posterior digitations are partly con- 
cealed by those of the great oblique muscle of the abdomen; the last, 
indeed, is entirely covered by that muscle. ; ; 

4, Action.—This is an expiratory muscle, in consequence of its drawing 
the ribs backwards and upwards. 


5. The Ilio-spinalis Muscle. (Fig. 106.) 


Synonyms.—It represents the long dorsal, short transversal, and long spinous of 
Bourgelat. Cuvier and others have described it as consisting generally, in mammalia, 
of five particular muscles, designated as longissimus dorsi, transversalis cervicis, semi- 
spinalis dorsi, and semispinalis colli. It corresponds to the longissimus dorsi, and trans- 
versalis cervicis of Man. 

(Percivall designates this important muscle the longissimus-dorsi—the name given to 
its analogue in Man. By Girard, Leyh, and Chauveau, it is styled the éléo-spinalis.) 


Extent—Situation.—This, the most powerful and complex of all the 
muscles in the body, extends along the dorso-lumbar spine, above the 
costal arches, from the anterior border of the ilium to the middle of the 
cervical stalk. 

Form.—tlt is elongated from before to behind, and flattened above 
and below in its posterior half, which represents the common mass in Man; 
this mass is prismatic in form, thick inwards, and thin outwards. Anteriorly, 
it is flat on both sides, and bifurcates into two voluminous branches, a 
superior and inferior, between which pass the insertions of the complexus 
to be fixed into the transverse processes of the first dorsal vertebree. 

Attachments.—1, Upon the lumbar border, the external anglo and 
internal surface of the ilium, the sacro-iliac ligament, and the sacrum; 
2, To the spinous processes of all the lumbar and dorsal, and last four 
cervical vertebra ; 3, To the articular tubercles of the lumbar vertebre and 
the transverse processes of all the dorsal, and the last four cervical vertebra ; 
4, To the costiform processes of the lumbar vertebra, and the external 
surface of the fifteen or sixteen last ribs. : 

Structure.—If this muscle is examined posteriorly, in the part which 
forms the common mass, it will be found to be composed of very compact 
fleshy fibres, covered in common by a thick aponeurosis. These fibres 
commence at the posterior.extremity of the muscle, and all proceed forward, 
stopping to take successive insertions on the various bony eminences 
in its track, and forming three different orders of fasciculi, which are 
more or less tendinous at their anterior or terminal extremity. These 
fasciculi are internal and superficial, internal and deep, and external, 

The internal and superficial, or spinal fasciculi, pass to the summits of 
the spinous processes already noticed when speaking of the attachments. 
These fasciculi are little, if at all distinct posteriorly ; but they become 
more so anteriorly. About the sixth dorsal vertebra, they separate from 
the other fasciculi to form the superior branch of the muscle (Fig. 106, 3). 

The internal and profound, or transverse fasciculi, are those which attach 
the muscle to the articular tubercles of the lumbar vertebree and transverse 
processes of the back and neck. They are well detached from each 
other, cven posteriorly, and are very tendinous. Anteriorly, they pass 
into the inferior branch of the ilio-spinalis, which they, in common with 


Uy 


A 


Pnsias OF THE TRUNK, 207 
Fig. 106. 


1, 2, 3, 4, Ilio-spinalis; 5, Com- 
mon intercostal; 6, Principal 
portion of the great complexus ; 
7, Anterior portion of the same ; 
8, Mastoid fasciculus of the 
small complexus; 8’, Its ten- 
don; 9, Atloid fasciculus of that 
muscle; 9’, Its tendon; 10, At- 
loid insertion of the splenius 
turned forward; 11, Ditto of 
the mastoido-humeralis; 12, 
Intertransversales of the neck; 
13, Long flexor of the head; 14, 
Inferior scalenus; 15, Superior 
scalenus; 16, Internal inter- 
costals; 17, Dependent fasci- 
culus of the small oblique, form- 
ing the retractor of the last. rib, 
according to German anatom- 
ists; 17’, Small oblique muscle 
of the abdomen; 18, Transverse 
muscle of the abdomen, 


/ 


DEEP MUSCLES OF THE SPINAL REGION OF THE NECK, BACK, AND LOINS, AND 
THE COSTAL AND INFERIOR ABDOMINAL REGIONS, 


= Some ene gS wie a ae 
208 THE MUSCLER® a 


the external fasciculi, go to form. From profound, they now become 
superficial ; and they are seen springing up betwéen the others, which 
appear to separate to allow them to pass (Fig. 106, 4, 4)... ; 
The external, or costal fasciculi, turn a little outwards to reach the ribs 
and costiform processes of the lumbar region ; they are no} very apparent 
in this direction (Fig 106, 2, 2). 4 
It will be easily understood that all these fasciculi do no! come from 
the common mass, which would be expended long before its termination at 
the neck, in consequence of the successive emissions of the fasciculi 
composing it. To prevent this expenditure, there are continually added to 
it numerous reinforcing bundles of fibres, which arise either|from its 
aponeurotic envelope, or from the bones on which the primary’ fasciculi 
terminate, and comport themselves absolutely like these, which {hey are 
charged to continue to the neck. 
Relations.—The ilio-spinalis is covered by the pyramidal point} of the « 
principal gluteal muscle, which it receives in a particular excavation,‘and by 
the: aponeurosis of the great dorsal and the small serrated muscles. It 
covers the intertransyersales of the lumbar region, the transversales of the 
back and loins, the supercostals (levatores costarwm) and the external,” 
intercostals. Outwards, it is bordered by the common intercostal. ‘, 
The superior branch is covered by the great complexus and the t 
versales colli. Inwardly, it responds to the cervical ligament and the anal 
gous branch of the opposite muscle. 
The inferior branch responds, outwardly, to the angularis of the scapula. 
it covers some intertransversales colli, and the aponeurotic digitations whic: 
attach the great complexus to the transverse processes of the first dorsal 
vertebre. From these digitations it even detaches a number of musculay 
fasciculi, which go to strengthen this branch of the ilio-spinalis. 
Action.—It is a powerful extensor of the vertebral column, which, wh 
it acts singly, it inclines to one side. It may also take part in expiration. 


é 6. Common Intercostal Muscle. (Fig. 106, 5.) 
Synonyms.—Trachelo-costalis— Girard. The sacro-lumbulis of Man. (Transversalis 
costarum—Percivall.) ody 


Form—Situation.—A long, narrow, and thin muscle—particularly at its 
extremities—situated along the external border of the preceding muscle, 
with which it is confounded behind the last rib. ee 

Structure—Attachments.—This muscle, whose structure has been com 
plicated at will by so many anatomists, is yet extremely simple. It is formed 
of a series of fasciculi, directed obliquely forwards, downwards, and out- 
wards, tendinous at their extremities, and originating and terminating 
successively on the external surface of the ribs. The most posterior leave 
the external border and inferior face of the common mass. The tendinous 
digitation of the anterior fasciculus is inserted into the transverse process 
of hes last cervical vertebra, in common with the inferior branch of the ilio- 
spinalis. ‘ 

Felations.—Outwards, with the great and small serratus: inwards, with 
the external intercostals, , ie, 


re depresses the ribs, and may extend the dorsal portion of the 


MUSCLES OF THE TRUNK. - 209 


7. Transverse Spinous Muscle of the Back and Loins. (Fig. 106, 3.) 


Synonyms.—Transverso-spinous—Girard. Dorso-lumbar portion of the semispinali 
of Man. (The spinalis and semispinalis dorsi—Percivall.) as ene 


Situation—Extent.—This is a very long muscle, directly applied to the 
supersacral and dorso-lumbar spine, and continuous, in front, with the 
transversales colli; these two muscles, therefore, measure nearly the whole 
length-of the spine. 

Structure.—It is formed of an assemblage of short fasciculi, which are 
flattened on both sides, tendinous at their extremities, directed obliquely 
forwards and downwards, and a little inwards, thus crossing at a right angle 
the spinous processes they cover. 

Attachments—These fasciculi are attached, below, to the lateral lip of 
the sacrum, the articular tubercles of the lumbar vertebra, and the trans- 
verse processes of the dorsal vertebre—origin. They are fixed, above, to the 
spinous processes of the sacral, lumbar, and dorsal vertebra, and into that of 
the last cervical vertebra—termination. It is to be remarked that they do 
not attain the summits of these spinous processes in the first half of the 
dorsal region. 

Relations.—Outwards, with the lateral sacro-coccygeal and ilio-spinalis 
muscles, which are confounded with it near its posterior extremity ; inwards, 
with the sacral spine and the spines of the lumbar and dorsal vertebre, and 
with the interspinous ligaments of these three regions. 

Action.—It is an extensor of the spine. 


DIFFERENTIAL CHARACTERS OF THE MUSCLES IN THE SPINAL REGION OF THE BACK AND 
LOINS IN OTHER THAN SOLIPED ANIMALS. 


1. Ruminants.—In the Ox, Sheep, and Goat, the trapezius is thick and very broad. 
The anterior small serrated muscle is inserted, by its last digitation, into the ninth rib, 
The posterior serrated is fixed into the four last ribs. 

2. Pia.—Its trapezius is well developed. The great dorsal is voluminous, and ig 
attached to the surface of the ribs, which it covers by digitations from its fleshy portion. 
It is fixed near the small trochanter to the lip of the bicipital groove. The inferior 
branch of the ilio-spinalis of this animal is easily divided into two portions, traces of 
which are found in the Horse: one is formed by the costal fasciculi, the other by the 
transversal fasciculi. The latter constitutes the muscle to which Bourgelat has given the 
name of short transversal. . 

3. Carnivora.—Several of the spinal muscles in the Dog resemble those of the Pig; 
such are the trapezium, the great dorsal, and the ilio-spinalis. In animals of this group, 
it is remarked that the anterior serrated is very thick and very developed, and that it is 
attached to the eight ribs succeeding the second by as many well-marked festoons. The 
posterior has only three digitations, which are attached to the three last ribs. The common 
intercostal exactly resembles the sacro-lumbalis of Man ; behind the last rib, it constitutes 
a thick fleshy body, separated by a fissure from the ilio-spinalis, with which it is attached 
to the coxa. Lastly, the transverse spinal muscle of the hack and loins is very strong in 
the lumbar region, and is prolonged on the coccygeal vertebrz. ) 

(According to Leyh, the interspinales muscles are absent in the Horse and Ruminants; 
they are found in the Pig between the spinous processes of the dorsal and lumbar 
vertebr, and in Carnivora between the spinous processes of the cervical vertebrae.) 


COMPARISON OF THE MUSCLES OF THE BACK AND NECK IN MAN WITH THE ANALOGOUS 
MUSCLES IN THE DOMESTICATED ANIMALS, 


It is usual, in human anatomy, to describe by the name of muscles of the back and 
neck those which correspond to the superior cervical region, and those of the spinal region 
“of the back and loins of the domesticated animals. The muscles of the inferior cervical 
region are described in Man as muscles of the neck, with the hyoid muscles and the 


scalenus. 


210 THE MUSCLES. 


A. Muscles of the Back and Cervix. 
; ; : ‘stiipnished, 
In the trapezius of Man, a cervical and a dorsal portion can no longer be distinguis 
Rove, it is atlenhed to the superior occipital curved line ; below, it is fixed to the 
external third of the upper border of the clavicle, and to the acromion and scapular spine, 


Fig. 107. 


FIRST, SECOND, AND PART OF THIRD LAYER OF MUSCLES OF THE BACK OF MAN} 
THE FIRST LAYER OCCUPIES THE RIGHT, THE SECOND THE LEFT SIDE. 

1, Trapezius; 2, Tendinous portion, forming, with a corresponding part of the 
opposite muscle, the tendinous ellipse on the back of the neck; 3, Acromion 
process and spine of scapula; 4, Latissimus dorsi; 5, Deltoid; 6, Muscles of 
dorsum of the scapula: infraspinatus, teres minor, and teres major; 7, Obliquus 
externus; 8, Gluteus medius; 9, Glutei maximi; 10, Levator anguli scapule; 
11, Rhomboideus minor; 12, Rhomboideus major; 13, Splenius capitis, overlying 
the splenius, above; 14, Splenius colli, partially seen: the common origin of the 
splenius is attached to the spinous processes below the origin of the rhomboideus 
major; 15, Vertebral aponeurosis; 16, Serratus posticus inferior; 17, Supra- 
spinatus; 18, Infraspinatus; 19, Teres minor; 20, Teres major; 21, Long head 
of triceps, passing between teres minor and maior to the arm; 22, Serratus 
magnus, proceeding forwards from its origin at the base of the scapula; 23, 
Obliquus internus abdominis. 


The fibres of the trapezius which are fixed into the clavicle, represent a portion of the 
mastoido-humeralis of quadrupeds. 

The great dorsal resembles that of the Dog and Pig, its fleshy portion being very 
developed ; itis attached to the external face of the four last ribs by muscular digitations, 
and tcrminates on the border of the bicipital groove, 


MUSCLES OF THE TRUNK. 211 


_ The rhomboideus is bifid, as in the smaller quadrupeds. Less developed than in these 
animals, the angularis is only fixed in front to the four first cervical vertebra. 

In Man, the splenius is large, but by its insertions it resembles that of Solipeds. The 
great complexus, thick and broad above, is incompletely divided into two fleshy bodies, 
which are attached, superiorly, to the sides of the external occipital crest. The small 
compleaus is not fixed into the axis and atlas, its superior extremity passing directly to 
the oe brovete: 

ere is nothing particular to note regarding the straight posterior and oblique muscles 
of the head ; the differences they offer in their form are allied to the Cantons ten of the 
bones in this region. 

_Of the two small serrated muscles, that which corresponds to the anterior serrated of 
animals rises very high; for it is attached by an aponeurosis to the spinous processes of 
the three first dorsal vertebree, the seventh cervical, and the cervical ligament. 

There are found in Man, lying along the vertebral furrows, several muscles which 
represent the ¢lio-spinalis and the common intercostal of Solipeds. Thus the common 
masz covering the lumbar vertebre behind, is prolonged by two series of fleshy and ten- 
dinous fasciculi: one forms the sacro-lumbalis, which resembles the common intercostal 
of animals; the other, the long dorsal, represents the inferior branch of the ilio-spinalis. 
The superior branch of the latter is found in the transversalis colli. 

Lastly, there are also seen in Man w transverse spinal and intertransverse muscles, 
which correspond: the first, to the transverse spinous of the back and loins and transverse 
spinous of the neck ; the second, to the intertransversales of the loins of the domesticated 
species, : 

B. Muscles of the Neck. 


The mastotdo-humeralis is not present in Man, being peculiar to quadrupeds; but we 
should see a portion of its fasciculi in the cleido-mastoideus muscle, and in the clavicular 
portions of the trapezius and deltoid. 

The sterno-mastoideus corresponds to the sterno-mazillaris of animals: as in the Dog, 
it is inserted into the external face of the mastoid process and the external two-thirds of 
the superior occipital curved line. Below, it commences by two fasciculi—one from the 
sternum, the other from the clavicle. We have already alluded to this clavicular 
fasciculus. 

The sterno-hyotdeus and sterno-thyroideus are large and well developed, resembling in 
their disposition those of the smaller animals. It is to be noted that the sterno-hyoideus 
leaves the sternum, the first costal cartilage, and the internal extremity of the clavicle. 
The scapulo-hyoideus is digastric. The anterior great straight muscle of the head is 
attached to four cervical vertebra, as in Ruminants and the Pig. The anterior small 
straight, the lateral small straight, and the long muscle of the neck, comport themselves as 
in the smaller animals. The anterior sealenus is very developed, for it is attached to the 
six last cervical vertebrae. 


SUBLUMBAR, OR INFERIOR LUMBAR REGION. 


The muscles of this region are deeply situated at the inferior face of the 
lumbar vertebre and the ilium, concurring to form the roof of the abdominal 
cavity, and are in more or less direct contact with the viscera contained in 
that cavity. They are nine pairs. Three have received the generic name of 
psoas, and are of large volume; they are maintained by a strong aponeurosis. 
the iliac fascia, and are distinguished as the great psoas, iliac psoas, and small 
psoas. A fourth is named the square muscle of the loins (quadratus lumborum), 
The other five, placed between the transverse processes of the lumbar vertebra, 
represent, in consequence of their connection with these kind of fixed ribs, 
veritable intercostal muscles; these are the intertransverse muscles of the loins. 

Preparation.—1. Place the subject in the first position ; open the abdominal cavity by 
completely removing its inferior walls; empty the cavity of the viscera it contains, and 
excise the diaphragm, as that muscle prevents the anterior extremity of the great and 
small psoas muscles being seen, 2. First study the iliac fascia, its form, relations with 
the long abductor of the leg, its attachments, its continuity with the tendon of the small 
psoas, and the expansion reflected from the aponeurosis of the great abdominal oblique 
muscle. 3. Expose the three psoas muscles by removing the iliac fascia, the two adduc- 
torg of the leg, and the three adductors of the thigh. 4. Remove the psoas muscles for 
the dissection of the quadratus and intertransversales. 


212 THE MUSCLES 


1. Iiae Fascia or Lumbo-iliac Aponeurosis. (Fig. 108, a.) 


This is a very resisting fibrous expansion, covering the great and iliac 
psoas muscles. Attached, inwardly, to the tendon of the small psoas, out- 
wardly to the angle and external border of the ilium, this aponeurosis, as it 
extends forwards over the great psoas, degenerates into cellular tissue, 
Behind, it also becomes attenuated in accompanying the two muscles it 
eovers until near their insertion into the internal trochanter of the femur. 
Its external or inferior face receives, posteriorly, the insertion of the crural 
arch, and gives attachment to the long adductor of the leg; for the re- 
mainder of its extent, it is covered by the peritoneum. 


2. Great Psoas Muscle. (Fig. 108, 1.) 


Synonyms.—Sublumbo-trochantineus—Girard, Psoas—Bourgelat. (Lumbo-femoral- 
Leyh. Psoas magnus—Percivall.) 


Form—Situation.—This is a long muscle, flattened above and below at its i. 


anterior extremity, prismatic in its middle, and terminated in a cone at its 
posterior extremity. It lies beneath the transverse processes of the lumbar 
vertebrae. 

Structure-—Almost entirely fleshy, this muscle is formed of fasciculi, 
very delicate in texture, directed backwards, and long in proportion to their 
superficial and deep situation. They all converge to a tendon which is 
enveloped by the iliac muscle, and is confounded with it. 

Aitachments.—The great psoas is attached: 1, By the anterior extremity 
of its fleshy fasciculi to the bodies of the last two dorsal and the lumbar 
vertebra, except the hindermost, and t6-the inferior face of the two last ribs 
and the transverse processes of the lumbar vertebre; 2, By its posterior 
tendon to the internal trochanter, in common with the psoas iliacus. 

Relations.—Below, with the pleura, the superior border of the diaphragm, 
the lumbo-iliac aponeurosis, which separates it from the peritoneum and 
the abdominal viscera situated in the sublumbar region; above, with the 
two last internal intercostals, the quadratus, and the intertransversales 
muscles; inwardly, with the small psoas and the internal branch of the 
iliac psoas; outwardly, for its posterior third, with the principal branch of 
the latter muscle. aes 

Action.—A flexor and rotator of the thigh outwards when its fixed point 
is the loins, this muscle also flexes the lumbar region when the thigh is 
a fixed point. It is, therefore, one of the agents which determine the-arching 
of the loins, and which operate, during exaggerated rearing or prancing, in 
bringing the animal into a quadrupedal position again. 


3. Iliac Psoas Muscle. (Fig. 108, 8, 4.) 


Synonyms.—Ilio-trochantineus—Girard. (Leyh divides this muscle into two por- 
tions. which he describes as the great and middle ilio-femoralis, Iliacus—Percivail.) 


Form—Situation—Direction.—This is a very strong, thick, and prismatic 
muscle, incompletely divided into two unequal portions by the groove for 
the reception of the tendon of the great psoas: an external portion, somewhat 
considerable in size; and an internal, small, These two muscular portions 
lie at the entrance to the pelvis, on the inner face of the ilium, in an oblique 
direction downwards, backwards, and inwards. 

Structure.—It is almost entirely fleshy. The fasciculi forming it are 


MUSCLES OF THE TRUNK, 213 


spread out in front, and collected behind, where they b i ibr 
and unite with the tendon of the iat aa Pree ea se 


Attachments.—It has its fixed insertion on the whole of the iliac surface, 


on the external angle of the ilium, the sacro-iliac ligament, and the ilio- 


Fig. 108. 


MUSCLES OF THE SUBLUMBAR, PATELLAR, AND INTERNAL CRURAL REGIONS 

1, Psoas magnus; 1’, Its terminal tendon; 2, Psoas parvus; 3, Iliac psoas; 4, Its 
small internal portion; 5, Muscle of the fascia lata; 6, Anterior straight muscle 
of the thigh; 7, Vastus internus; 8, Long adductor of the leg; 9, Short adductor 
of the leg; 11, Pectineus; 12, Great adductor of the thigh; 12’, Small adductor 
of the thigh; 13, Semimembranosis; 14, Semitendinosis.—a, Portion of the 
fascia iliaca; B, Portion of the membrane reflected from the aponeurosis of the 
abdominal great oblique muscle, forming the crural arch (Poupart’s ligament); 
c, Pubic tendon of the abdominal muscles; D, Origin of the pubio-femoral 
ligament. 


pectineal crest. Its movable insertion is into the small internal trochanter, 


in common with the great psoas. 
Relations.—Above, with the ilium; below, with the iliac fascia and the 
long adductor of the leg; outwardly, with the muscle of the fascia lata and 


17 


214 THE MUSCLES. 


the origin of the anterior straight muscle of the thigh, from which it is 
separated by a space filled with fat; inwardly, with the crural vessels. It 
passes between the vastus internus and the pectineus, to reach the 


trochanter. . 
Actions.—It is a flexor and rotator outwards of the thigh. 


4, Small Psoas Muscle. (Fig. 108, 2.) 


as ins—Bourgelat. Sublumbo-pubialis, or sublumbo-iliacus. 
ioe ePwes een eal The Tanba-thiaous of Leyh.) : 

Situation—Form—Structure.— Placed at the inner side of the great psoas, 
very much elongated, and semipenniform in shape, this muscle is terminated 
behind by a flattened tendon, and is composed of fleshy fibres, the longest of 
which are anterior. These fasciculi are all directed backwards and outwards 
to gain the tendon. 

Attachments.—1, To the bodies of the three or four last dorsal, and to all 
the lumbar vertebra, by the anterior extremity of its fleshy fibres; 2, To 
the ilio-pectineal eminence and the lumbo-iliac aponeurosis, by the posterior 
extremity of its tendon. 

Relations.—By its inferior face with the pleura, the superior border of the 
diaphragm, the aorta or posterior vena cava, and the great sympathetic 
nerve; by its upper face, with the psoas magnus. It is traversed, near its 
vertebral insertions, by numerous vascular and nervous branches. 

Actions.—It flexes the pelvis on the spine, when the loins are the fixed 
point ; but should the pelvis be fixed, it arches or laterally inclines the lumbar 
region. It is also the tensor muscle of the lumbo-iliac aponeurosis. 


Fig. 109. 5. Square Muscle of the Loins. 
(Fig. 109, 1.) 
Synonyms. — Sacro-costalis — 
Girard. (Sacro-lumbalis— Pereivall. 
Quadratus lumborum of Man.) 
Situation — Form — Structure 
—Attachments—This muscle is 
comprised between the trans- 
verse processes of the lumbar 
region and the great psoas, and 
is elongated from before to be- 
hind, flattened above and below, 
and divided into several very 
tendinous fasciculi. The prin- 
cipal fasciculus, situated out- 
wardly, takes its origin from 
the sacro-iliac ligament, near 
the angle of the sacrum, and ex- 
tends directly forward to gain 
the posterior border of the last 
rib, after being attached by its 
upper face to the summits of the 
transverse processes of the lum- 


DEEP MUSCLES OF THE SUBLUMBAR REGION. 


Quadratus lumborum; 2, 2, Intertransversales : a 
8, Small retractor muscle of the last rib—a de- bar vertebre, The other fasei 


pendent of the small oblique of the abdomen. culi are: longer as they are an- 


terior; they leave the internal 
border of the first, and are directed obliquely forward and inward, to be 


MUSCLES OF THE TRUNK 215 


fixed into the transverse processes of the majority of the lumbar vertebra, 
and the inner face of the two or three last ribs. 
Relations.—By its upper face, with the intertransversales, the small 
retractor of the last rib, and the fibrous fascia which unites that muscle to 
the small oblique of the abdomen. By its inferior face, to the great psoas. 


Actions.—It draws the last ribs backwards, and inclines the lumbar spine 
to one side. 


6. Intertransverse Muscles of the Loins. (Fig. 109, 2, 2.) 


(Synonym—Intertransversales lumborum—Percivall.) 


These are very small flat muscles which fill the intervals between the 
transverse processes of the lumbar vertebre. The muscular fibres entering 
into their composition are mixed with tendinous fibres, and are carried from 
We anterior border of one transverse process to the posterior border of the 
other. 

They respond, by their superior face, to the ilio-spinalis (longissimus 
dorsi), and by their inferior face to the quadratus, as well as the psoas 
magnus. They act by inclining the lumbar region to one side. 


DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE SUBLUMBAR REGION IN OTHER 
‘ THAN SOLIPED ANIMALS. 


In Ruminants and the Pig, the muscles of this region so closely resemble those of 
Solipeds, that a special description is unnecessary. 

In the Dog, the great psoas is little developed, and only commences at the third, or 
even the fourth lumbar vertebra; the iliac psoas is very slender, particularly in its 
external portion ; otherwise it is scarcely distinct from the great psoas, with which it may 
be said to form one muscle; the small psoas is relatively larger than the great; it is not 

- prolonged into the pectoral cavity, and its anterior extremity is confounded with the 
quadratus lumborum, which is longer and stronger than in all the other animiuls. 


COMPARISON OF THE SUBLUMBAR MUSCLES OF MAN WITH THOSE OF ANIMALS. 


In human anatomy, by the names of psoas and iliacus are described the greut psoas 
and iiiae psoas of animals. The psoas magnus of May is distinguished from that of 
£olipeds by its superior insertions, which do not go beyond the last dorsal vertebrae. 

The small psoas is often absent; when present, it is attached, above, to the bodies of 
the twelve dorsal vertebrae. below, to the ilio-pectineal crest. 

The intertransversales have been studied with the muscles of the back. The 
quadratus of the loins, classed by anthropotomists with the abdominal muscles, is 
distinctly divided into three series of fasciculi: ¢dio-costul fasciculi, which pass from the 
upper border of the ilium to the twelfth rib; lwmbo-costal fasiculi, passing from the 
transverse processes of the three or four last lumbar vertebrae to the twelfth rib, and ilio- 
lumbar fasciculi, going from the iliac crest to the posterior face of the transverse processes 
of all the Jumbar vertebra. 


COCCYGEAL REGION. 


This region is composed of four pairs of muscles destined for the 
movements of the tail: three, named the sacro-coccygeal, are disposed 
longitudinally around the coccygeal vertebrae, which they completely 
envelop; the fourth is designated the ischio-coccygeus. 


1. Sacro-coccygeal Muscles. (Fig. 181, 1, 2, 3.) 


These three muscles are inclosed, with those of the opposite side, in a 
common aponeurctic sheath which is continuous with the inferior ilio-sacral 
and sacro-ischiatic ligaments. They commence on the sacrum, are directed 
backwards and parallel with the coccyx, gradually diminishing in thickness, 
and are decomposed into several successive fasciculi terminated by small 


216 THE MUSCLES, 


tendons, which are inserted into each of the coceygeal bones. With regard 
to their situation, these muscles are distinguished as sacro-coccygeus superior, 
sacro-coccygeus inferior, and sacro-coccygeus lateralis. 


a. Sacro-coccygeus Superior. 
(Synonym.—Erector coceygis— Percivall.) 


The fasciculi which form this muscle take their fixed insertion either 
from the summits and sides of the three or four last processes of the super- 
sacral spine, or from the coccygeal vertebre themselves. ‘The tendons 
through which they effect their movable insertion into these vertebre are 
always very short. 

This muscle, covered by the coccygeal aponeurosis, in turn covers the 
vertebra it is designed to move. It responds: inwardly, to the analogous 
muscle of the opposite side ; outwardly, to the lateral sacra-coccygeus, and, 
near its anterior extremity, to a very strong aponeurotic expansion which 
separates it from the transverse spinous muscle. It directly elevates the tail, 
or pulls it to one side, according as it acts in concert with its fellow or 
singly. 

b. Sacro-coccygeus Inferior. 

(Synonym.—Depressor coccygis—Percivall.) 


This muscle is thicker than the preceding; its constituent fasciculi 
take their origin from the inferior surface of the sacrum, towards the third 
vertebra, and from the internal face of the sacro-ischiatic ligament and the 
coccygeal bones. It readily divides into two parallel portions, which 
Bourgelat has described as two separate muscles. The fasciculi of the 
internal portion are inserted, by their posterior extremity, into the inferior 
face of the first coccygeal vertebra. Those of the external portion are all 
furnished with strong superficial tendcns, néi.rly all of which are for the 
bones of the tail. 

This muscle responds : outwardly, to the ischiatic ligament, the ischio- 
coccygeus and coccygeal aponeurosis ; inwardly, to the muscle of the opposite 
side, and to the coccygeal attachment of the rectum; above, to the sacrum, 
the bones of the tail, and the lateral muscle; below, to the rectum and the 
coccygeal aponeurosis. 

It either directly depresses the tail or inclines it to one side. 


ce. Sacro-coccygeus Lateralis. 
(Synonym.—COurvator coccygis—Percivall.) 


This muscle may be considered as the transverse spinous of the coccygeal 
region; indeed, it is confounded with that muscle of the back and loins 
by its anterior extremity, and appears to continue it to the inferior 
extremity of the tail. 

The fasciculi composing it have their origin from the spinous processes 
of the last lumbar vertebra, through the medium of the transverse spinous, and 
from the coceygeal bones. The tendons terminating these fasciculi are deep 
and not very distinct. 

It responds; outwardly, at the posterior extremity of the ilio-spinalis, to 
the inferior ilio-sacral ligament and the coccygeal aponeurosis; inwardly, 
to the transverse spinous and the coccygeal vertebra ; above, to the superior 
muscle; below to the inferior muscle, from which it is nevertheless 


MUSCLES OF THE HEAD, 217 


separated by several small independent muscular fasciculi, which are carried 
from one coccygeal vertebra to another. (Leyh designates these the inter. 
transversales of the tail.) It inclines the tail to one side. 


2. Ischio-coceygeus. (Fig 181, 41.) 


Synonym.—Compressor coccygis—Percivall.) 


A small, thin, wide, and triangular muscle, situated against the lateral 
wall of the pelvis, at the internal face of the sacro-ischiatic ligament. 

It is attached, by an aponeurosis, to that ligament and to the ischiatic 
crest; it is then directed upwards to be fixed, by its muscular fibres, to the 
side of the last sacral vertebra and the first two coccygeal bones. 

It is related, outwardly, with the sacro-ischiatic ligament, and inwardly to 
the lateral sacro-coccygeus and the rectum. 

It depresses the entire caudal appendage. 


REGION OF THE HEAD. 


The head comprises a large number of muscles, of which only those 
covering the bones of the face, and those which move the lower jaw and os 
hyoides, will be described. The others will be studied with the apparatus 
to which they belong. 


A. Facial Region. 


This region includes those muscles of the head which form a part of the 
framework of the lips, cheeks, and nostrils: that is, all those which are 
grouped around the face, properly called. Authors are far from being 
unanimous with regard to the nomenclature and description of these muscles. 
Girard recognised eleven, to which he gave the following names: labialis, 
alveolo-labialis, zygomatico-labialis, lachrymo-labialis, supernaso-labialis, super- 
mawillo-labialis, supermamill.-nasalis magnus, supermasxillo-nasalis parvus, 
transversalis nasi, maxillo-labialis, mento-labialis. To these eleven muscles, 
three of which are single, two others are added; these were described by 
Bourgelat as the middle (intermediate) anterior and middle (intermediate) pos- 
terior muscles, which Girard wrongly considered as belonging to the labial. ' 


1. Labialis, or Orbicularis of the Tips. (Fig. 110, 27.) 


(Synonym.—Orbicularis oris—Percivall.) 


Preparation.—Remove with scissors the skin covering the two portions of this 
muscle; afterwards the buccal mucous membrane and subjacent glands within the lips, to 
expose its internal face. 


The labialis, disposed as a sphincter around the anterior opening of the 
mouth, is regarded as the intrinsic muscle of the lips, and is composed of 
two portions or fasciculi, one for the upper, the other for the lower lip. 
United to each other at the commissures of the mouth, and confounded with 
the superficial layer of the alveolo-labialis, which they appear to continue, 
these two muscular portions also receive a large portion of the fibres 
belonging to the majority of the extrinsic muscles, such as the supermaxillo- 
nasalis magnus and supernaso-labialis. 

The orbicularis is not attached to the neighbouring bone ; its component 
fibres affecting a circular form, have, consequently, neither peginning nor 
ending, except in being continuous with other fibres. 

The internal face of the superior fasciculus responds to a layer of salivary 


218 THE MUSCLES. 


glands, which in part separate it from the buccal mucous membrane. The 
external, covered by the skin, adheres to it in the most intimate manner, and. 
is found isolated from it only on the median line, at first by the aponeurotic 
expansion of the supermaxillo-labialis, then by a musculo-fibrous layer 
analogous to that which forms the mento-labialis. _ 

By its internal face, the inferior fasciculus likewise responds to the buccal 
mucous membrane, and to some salivary glands. By its external face, it 


Fig, 110. 


SUPERFICIAL MUSCLES OF THE FACE AND HEAD. 

1, Temporo-auricularis externus, or attollens maximus; 2, Levator palpebra, or 
corrugator supercilii; 3, Temporo-auricularis internus, or attollens posterior ; 
4, 5, Zygomatico-auricularis, or attollens anterior; 6, Orbicularis palpebrarum; 
7, Parotido-auricularis, or deprimens aurem; 8, Parotid gland; 9, Temporal, or 
subzygomatic vein; 10, Ditto, artery; 11, 12, Superior and inferior maxillary 
nerves; 13, Fascia of the masseter muscle; 14, Nasal bones; 15, Supernaso- 
labialis, or levator labii superioris alzeque nasi; 16, Supermaxillo-labialis, or 
nasalis longus labii superioris; 17, External maxillary or facial artery; 18, 
Facial vein; 19, Supermaxillo-nasalis magnus, or dilatator naris lateralis; 20, 
Superior maxillary nerve; 21, Zygomatico-labialis, or zygomaticus; 22, Parotid, 
or Stenon’s duct; 23, Masseter; 24, Alveolo-labialis, or buccinator ; 25, Super- 
maxillo-nasalis parvus, or nasalis brevis labii superioris; 27, Labialis, or orbicu- 
laris oris; 28, Maxillo-labialis, or depressor labii inferioris; 29, Mento-labialis, 
or levator menti. 


forms an intimate union with the cutaneous integument, like the superior 
fasciculus. 

This muscle plays the part of a constrictor of the anterior opening of the 
mouth, and has complex functions to perform in suction, the prehension of 
food, and in mastication. 


2. Alveolo-labialis. (Fig. 110, 24.): 


Synonyms,—Molaris externus et internus—Bourgelut. (Buceinator—Percivall. Leyh 
divides this muscle into two portions; its superficial plane he designates the buccinator, 
and the deep plane the molaris.) 


Preparation.—Proceed to the ablation of the masseter; dissect the external surface of 
the muscle, taking care of the risorius Santorini and zygomaticus, which are confounded 
with it. Then divide-it in the middle, as far as the commissure of the lips; turn 
down each strip on the jaws, and remove the mucous membrane, in order to study the 
ete face of the muscle and the attachments of the superficial plane to the maxillary 

ones, 


MUSCLES OF THE HEAD. 219 


Situation—Form.—Situated on the sides of the face, partly concealed by 
the masseter muscle, and applied to the mucous membrane of the cheeks, the 
alveolo-labialis is a flat, thin muscle, elongated in the direction of the head 
and formed of two superposed planes. 

__Extent—Structure—Attachments.—The deep plane, the longest and least 
wide, is narrower at its extremities than its middle, and is formed of strongly 
aponeurotic muscular fasciculi, which are attached, posteriorly: 1, To the 
alveolar tuberosity ; 2, To the external surface of the superior maxillary 
bone, above the last three molar teeth; 8, To the anterior border of the 
inferior maxillary bone, behind the sixth molar, in common with the maxillo- 
labialis. On reaching the commissure of the lips, this muscular layer 
appears to be continued by small tendons with the fibres of the orbicularis. 

The superficial plane only begins about the middle of the deep one, whose 
anterior half it entirely covers. Its fibres, less tendinous than those of the 
latter, extend from a median raphé which also divides the deep layer in its 
length, and are directed, some forwards, some backwards, to terminate in the 
following manner : the first are inserted into the external face of the super- 
maxillary bone, above the first molar tooth and the superior interdental 
space ; the second are attached to the inferior interdental space alone. 

Relations.—Externally, with the masseter, zygomatico-labialis, cuticularis, 
great supermaxillo-nasalis, supernaso-labialis, the parotid duct, which crosses 
it to enter the mouth, and the facial artery and veins; internally, with the 
buccal mucous membrane. The deep plane is accompanied and covered at its 
anterior border by the upper molar glands; its posterior border is margined 
by the inferior molar teeth, which it partially covers. The superficial layer 
is distinctly separated from the deep one in its anterior part, which is attached 
to the superior maxillary bone. Behind, these two planes adhere more 
intimately to one another, though they are found completely isolated by an 
interstice in which one or two large veins pass. 

Actions —The function of the alveolo-labialis is particularly related to 
mastication : this muscle, in fact, pushes between the molar teeth the portions 
of food which fall outside the alveolar arches ; but it cannot aid in bringing 
the two jaws together, as M. Lecoq has correctly observed. 


3. Zygomatico-labialis. (Fig. 110, 21.) 


Synonyms.—Portion of the cuticularis of Bourgelat. The zygomatecus major of Man. 
(Zygomaticus—Percivall.) 


A very small, pale, and thin ribbon-like muscle, arising from the surface 
of the masseter, near the maxillary spine, by an aponeurosis which is con- 
founded with the cuticularis; it terminates on the surface of the alveolo- 
labialis, at a short distance from the commissure of the lips. Covered by 
the skin, it covers the alveolo-labialis muscle, and some of the superior molar 
glands, vessels, and nerves. . 

This muscle pulls backwards the commissure of the lips when it is in a 
state of contraction. 7 

In Solipeds there is also sometimes found a muscle resembling the 
zygomaticus minor of Man. It is a very small fasciculus situated under the 
preceding muscle, near its superior extremity. It appears that this fasciculus 
is continued, above, by the fibres of the lachrymo-labialis, and is lost, below, 
on the alveolo-labial surface, a little beneath the carotid canal. 


220 THE MUSCLES. 


4, Lachrymo-labial, or Lachrymal Muscle. 
(Synonym.—Not mentioned by Percivall. It is the énferior palpebral muscle of Leyh.) 


A wide and very thin muscle, situated superficially below the eye: it is 
continuous, in front, with the supernaso-labialis; behind, with the cu- 
ticularis; above, with the orbicularis of the eyelids. Its fibres, partly 
muscular and partly aponeurotic, leave the external surface of the lachrymal 
and zygomatic bones, are directed downwards, and become lost in a cellular 
fascia which covers the alveolo-labialis ; some pass beneath the zygomatico- 
labialis and form the zygomaticus minor, when this is present. 

This muscle is supposed to corrugaterand twitch the skin below the 
eye. ; 
ui 5. Supernaso-labialis. (Fig. 110, 15.) 

Synonyms.—The maxillaris of Bourgelat. The levator labii superioris aleque nasi of 
Man. (Levator labii superioris aleque nasi—Percivall. Fronto-labialis—Leyh.) 


Sitwation— Direction—Form—Structure.—Situated on the side of the 
face, in an oblique direction downwards and backwards,! the supernaso- 
labialis is a wide muscle, flattened on both sides, elongated from below to 
above, aponeurotic at its superior extremity, and divided inferiorly into two 
unequal branches, between which passes the great supermaxillo-nasalis, 

Attachments.—It has its origin, by its superior aponeurosis, from the 
frontal and nasal bones, and unites on the median line with the muscle of 
the opposite side. Its anterior branch, the widest and thickest, goes to the 
external ala of the nose and to the upper lip, where its fibres are confounded 
with those of the orbicularis. The posterior branch terminates at the 
commissure of the lips. 

Relations.—Outwards, with the skin; inwards, with the supermaxillo- 
labialis, the posterior portion of the small supermaxillo-nasalis, and vessels 
and nerves. Its posterior branch covers the great supermaxillo-nasalis, 
and the anterior is covered by that muscle. 

Actions.—It elevates the external ala of the nose, the upper lip, and the 
commissure of the lips. 


6. Supermawillo-labialis. (Fig. 110, 16.) 


Synonyms.—Levator labii superioris of Bourgelat. The levator labii superioris proprit of 
Man. (Nasalis longus labii superioris—Percivall.) 


Sitwation—Direction—Form— Structure.—Lying vertically on the side 
of the face, below the supernaso-labialis, this muscle is a thick and conical 
fleshy mass, terminated inferiorly by a tendon. 

Attachments.—It is attached, by the upper extremity of its fleshy body, 
to the external surface of the supermaxillary and zygomatic bones—origin. 
Its terminal tendon passes over the transverse muscle of the nose, to unite 
with that of the opposite side, and with it to form a single aponeurotic 
expansion, which dips by small fibres into the subcutaneous musculo-fibrous 
tissue of the upper lip. 

Relations.—Covered by the lachrymal and supernaso-labialis muscles, 
this muscle in turn covers the supermaxillary bone, the bottom of the false 
nostril, the small supermaxillo-nasalis, and the transversalis nasi. 

Actions.—It raises the upper lip, either directly or to one side, as it acts 
singly or in concert with its congener. 


" It is to be remembered that we suppose the head maintained in a vertical position, 


f MUSCLES OF THE HEAD. 221 


7. Great Supermawillo-nasalis. (Fig. 110, 19.) 


Synonyms.—The pyramidalis-nasi of Bourgelat, The cuninusof Man. (Dilatator naris 
lateralis—Percivall.) 


Situation—Direction—Form—Structure.—This muscle, situated on the 
side of the face, between the two branches of the supernaso-labialis, in an 
almost vertical direction, is of a triangular form, and slightly tendinous at its 
summit. 

Aitachments.—It has its origin, by the aponeurotic fibres of its summit, 
from the external face of the supermaxillary bone, below its ridge.—It 
terminates, by its base, on the skin covering the external wing of the nostril, 
ie a posterior fibres being confounded with those of the orbicularis of 
the lips. 

Relations.—Outwardly, with the skin and the inferior branch of the 
supernaso-labialis ; inwardly, with the anterior branch of that muscle, and 
with vessels and nerves. 

Actions.—It dilates the external orifice of the nasal cavity, by pulling 
outwards the external wing of the nostril. 


‘ { 8. Small Supermawillo-nasalis, (Fig. 110, 25.) 


Synonyms.—The nasalis brevis, and portion of the subcutaneous muscle of Bourgelat. 
(Nasalis brevis labit superioris—Percivall.) 


Girard has described, by the above name, a small, thick, and short 
muscular fasciculus which covers the external process of the premaxillary 
bone, and whose fibres, either originating from that, the supermaxillary 
bone, or the internal face of the supernaso-labialis muscle, terminate in the 
skin of the false nostril, and the appendix of the inferior turbinated bone. 

Rigot has attached to this muscle that described by Bourgelat as the 
short muscle. The latter is composed of short, transverse fibres, applied to 
the expansion of the cartilaginous septum of the nose which projects 
laterally beyond the nasal spine. These fibres abut, by their most eccentric 
extremities, against the skin of the false nostril and the appendix of the 
superior turbinated bone. 

In adopting Rigot’s description, it is found that the small supermaxillo- 
nasalis is composed of two portions, which border the re-entering angle 
formed by the large process of the premaxillary bone and the nasal spine. 
These two portions, posterior and anterior, unite at their upper extremities. 
The first appears to be confounded, below, with the middle anterior 
(depressor ale nasi), the second is continuous with the transversalis nasi. 
When they contract, they concur in the dilatation of the false nostril and 


the proper nasal cavity. 
JY 9. Transversalis Nasi. 


Synonym.—{ Dilatator naris anterior—Pereivall.) 


A single, short, and quadrilateral muscle, flattened before and behind, 
applied to the widened portion of the nasal cartilages, and composed of 
transverse fibres proceeding from one cartilage to the other. Covered by the 
skin and the aponeurotic expansion of the two elevator muscles of the upper 
lip, the transverse muscle of the nose covers the cartilages to which it is 
attached, and is confounded below with the orbicularis of the lips. 

Designed to bring together the internal alee of the nose, this muscle 
ought to be considered more particularly as the dilator of the nostrils. 


222 THE MUSCLES. 


\ 10. The Middle (Intermediate) Anterior Muscle. 


Synonyms —Medius anterior—Bourgelat. Myrtiformis of Man. (Depressor labii 


supertori—Percivall. Incisive muscle of the upper lip—Leyh. A portion of the ..« 


orbicularis, according to Rigot.) 


Bourgelat thus names a deeply-situated muscle which is fixed to the 
inner face of the premaxillary bone, above the incisor teeth, and whose 
fibres ascend to meet those of the posterior portion of the small super- 
maxillo-nasalis muscle, to terminate with them on the anterior appendix of 
the inferior turbinated bone; some fibres become lost in the lip. Itis 
regarded as a dilator of the entrance to the nasal fossa. 


To study this muscle, it is necessary to raise the upper lip and remove the mucous 
membrane covering it. It may be dissected at the same time as the bony attachments of 
the superficial plane of the alveolo-labialis muscle. 


11. Mazillo-labialis. (Fig. 110, 28.) 
Synonyms.—Depressor labii inferioris—Rigot. A dependency of the buccinator of 
Man. (Depressor labii inferioris—Percivall. Inferior maxillo-labtalis—Leyh. Depressor 
angult oris of Man.) 


Situation—Direction—Form—Structure.—Situated along the inferior 
border of the alveolo-labialis, whose direction it follows, this muscle forms a 
long narrow fasciculus, terminating inferiorly by an expanded tendon. 

‘Attachments —1, By its superior extremity, to the anterior border of 
the lower jaw, in common with the deep plane of the alveolo.labialis—fixed 
origin ; 2, By its terminal tendon, to the skin of the lower lip—movable 
insertion. 

Relations.—Outwardly, with the masseter and the facial portion of 
cuticularis of the neck; inwardly, with the maxillary bone; in front, with 
the alveolo-labialis muscle, with which it is directly united in its upper two- 
thirds. 

Actions.—It separates the lower from the upper lip, and pulls it to the 
side if one alone acts. in 


12. Mento-labialis or Muscle of the Chin. (Fig. 110, 29.) 


(Synonyms.—Percivall appears to describe this and the next muscle as one. It is the 
quadratus menti of Man.) 


This name is given to a musculo-fibrous nucleus, forming the base of the 
rounded protuberance beneath the lower lip in front of the beard. This 
single nucleus is confounded, in front, with the orbicularis of the lips, and 
receives into its upper face the insertion of the two posterior middle muscles 
(levatores menti). 


13. Middle (Intermediate) Posterior Muscle. 


Synonyms.~- Medius posterior—Bourgelat. (Levator menti—Percivall. Incisive muscle 
of the lower lip—Leyh.) 


Bourgelat describes, by this name, a small muscular fasciculus, analogous 
in every respect to the medius anterior. This little muscle takes its origin 
from the external surface of the body of the lower jaw, beneath the inter- 
mediate and corner incisors; from thence it descends into the texture of the 
lip, to unite with that of the opposite side on the upper face of the,amento- 
labialis. Several authors have described it as a dependent of the last miigcle. 


MUSCLES OF THE HEAD. 223 


It is an energetic elevator of the lower lip. 


To dissect this muscle, the directions given for the preparation of the anterior medius 
will suffice. 


B. Masseteric or Temporo-maxillary Region. 


_ ‘This pair region comprises five muscles for the movement of the lower. 
Jaw. These are: the masseter, temporal, internal pterygoid, external pterygoid, 
and digastricus. 


Preparation.—1. First study the digastricus and its stylo maxillary portion, with the 
internal pterygoid, in preparing the hyoid muscles as they are represented in fig. 111. 
2, Expose the pterygoideus externus, by removing in this preparation the hyoid bone and 
its dependencies, as well as the two preceding muscles. 3. To dissect the temporalis, 
excise the external pterygoideus from its inferior border, an operation which exposes the 
orbital fasciculus of the temporalis; then turn over the piece, saw off the orbital process 
at each end, and remove the eye and auricular muscles. 4. Dissect the masseter in 
clearing away from its external surface the cuticularis and the vessels and nerves which 
cover it. 


1. Masseter, (Fig. 110, 23.) 


Synonyms.—Zygomatico-maxillaris—Girard, (The zygomatico mazillaris of Leyh.) 


Situation—Form —Structure.— Applied against the external face of the 
lower jaw, the masseter is a short, wide, and very thick muscle, flattened on 
both sides, irregularly quadrilateral, and formed of several superposed planes, 
two of which are perfectly distinct towards the temporo-maxillary articula- 
tion, by the somewhat different direction of their fibres. These are divided 
by a considerable number of intersections, and are covered by a strong 
aponeurotic layer, which becomes gradually thinner backwards and down- 
wards. 

Attachments.—The fasciculi of the masseter have their fixed insertion on 
the zygomatic crest.—Their movable insertion is on the imprints which 
cover the upper half of the inferior maxillary branch. 

Relations—It responds, by its superficial face, to the facial portion of 
cuticularis colli, to the nerves of the zygomatic plexus, and several venous 
and arterial vessels; by its deep face, to the inferior maxillary bone, the 
alveolo-labialis and maxillo-labialis muscles, the superior molar glands, and 
two large venous branches; by its inferior border, with the parotid canal, 
and the glosso-facial artery and vein; by its superior and posterior border, 
to the parotid gland. Its deep plane responds, anteriorly, with the temporo- 
maxillary articulation, and is so intimately confounded with the temporalis, 
that it is impossible to define the respective limits of the two muscies. 

Action.—This muscle, the special elevator of the lower jaw, plays an 
important part in mastication. It always acts as a lever of the third class, 
the middle line, which represents the resultant of all its constituent fibres, 
passing behind the last molar. 


2. Temporal or Crotaphitic Muscle. 
Synonyms.—Temporo-maxillaris—Girard. (The temporo-maxillaris of Leyh.) 


Situation— Form— Structure—Situated in the temporal fossa, to which 
it is moulded, and which it fills, this muscle is flattened from above to 
below, divided by strong tendinous intersections, and covered by a nacrous 


aponeygotic layer. 
Give takes its origin: 1, In the temporal fossa and on the 


224 THE MUSCLES. 


bony crests which margin it; 2, By a wide fasciculus, paler than the other 
portion of the muscle, but not unconnected with it, from the imprints 
situated behind the crest surmounting the orbital hiatus. It terminates on 
the coronoid process and the anterior border of the branch of the lower 
anv. 
: Relations.—This muscle covers the temporal fossa, and is covered by the 
temporo-auricularis muscles, scutiform cartilage, internal scuto-auricularis, 
the fatty cushion at the base of the ear, and by another adipose mass which 
separates it from the ocular sheath. Its deep fasciculus responds, by its 
internal face, to the two pterygoid muscles. 

Action.—It brings the lower jaw in contact with the upper, by acting as 
a lever of the first kind; but the orbital portion of the muscle elevates tho 
inferior maxilla and moves it laterally by a lever of the third class. 


3. Internal Pterygoid. 


Synonyms.—Portion of the spheno-maxillaris of Bourgelat. (The pterygoideus internus 
of Percival]. Leyh designates the pterygoideus internus and externus as one muscle, tha 
spheno-maxillaris or internal masseter.) 


Situation—Form—Structure—Situated in the intermaxillary space, 
opposite the masseter, the pterygoideus internus, although not so strong as 
that muscle, yet so closely resembles it in form and structure as to be 
named by Winslow the internal masseter. 

Attachments—1. To the palatine crest and subsphenoidal process—fixed 
insertion: 2. In the hollow excavated on the inner face of the branch of the 
lower jaw—movable insertion. 

Relations—Outwardly, with the pterygoideus-externus, the orbital 
fasciculus of the temporal, the maxillo-dental nerves, mylo-hyoideal, and 
lingual muscles, arteries and veins, and the inner surface of the bone which 
receives its movable insertion. Inwardly, with the tensors palati—external 
and internal, the guttural pouch, the hyoideus magnus, hyoid bone, digastricus, 
the hypoglossal and glosso-pharyngeal nerves, glosso-facial artery and vein, 
the hyoglossus longus and brevis muscles, the laryngo-pharyngeal apparatus, 
the Stenonian duct, and the submaxillary glands. 

Action.—It is an elevator of the lower jaw, and also gives it a very 
marked lateral or deductive motion. If the left muscle acts, this movement 
carries the inferior extremity of the lower jaw to the right; and if it be 
the right muscle, then in the contrary direction. 


4, Haternal Pterygoid. 


Synonym.—Portion of the spheno-maxillaris of Bourgelat. 


Form—Situation—Structure—Attachments—A small, short, and very 
thick muscle, situated within and in front of the temporo-maxillary 
articulation, formed of slightly tendinous fasciculi which leave the inferior 
face of the sphenoid bone and the subsphenoidal process, and are directed 
backwards and upwards to be fixed to the neck of the inferior maxilliry 
condyle. 

Relations.—Outwardly, with the orbital fasciculus of the temporal 
muscle, and the temporo-maxillary articulation. Inwardly, with the 
numerous nerves emanating from the inferior maxillary branch, and with 
the internal pterygoid and tensors palati. 

Action.—When the two external pterygoids act in concert, oo 


maxilla is pulled forward; but if only one contract, the propu is 


MUSCLES OF THE HEAD. 225 


accompanied by a lateral movement, during which the extremity of the jaw 
is carried to the opposite side. 


5. Digastricus. 


Synonyms.—Bourgelat has made two disti is— i i 
etylomasilass, gee ee described AE igre Ba ig et tne 
ev. ollowe: ourgelat's ex ivi i igastré 
to paler, Leyh ae sak tien ne the muscle into digastricus and 

Form—Structure—Situation—Direction—Composed of two fleshy bodies 
more or less divided by intersections, and united at their extremities by a 
median tendon, this muscle is situated in the intermaxillary space, and 
extends from the occiput to near the symphysis of the chin, describing a 
curve upwards. 

Aittachments.—It takes its origin from the styloid process of the occipital 
bone, by its superior fleshy body. It terminates: 1, On the curved portion 
of the posterior border of the lower jaw by a considerable fasciculus, which 
is detached from the superior fleshy body ;! 2, On the internal face of the 
same bone and the straight portion of its posterior border, by aponeurotic 
digitations which succeed the muscular fibres of the inferior fleshy body. 

Relations.—The superior belly of the muscle responds, superficially, to 
the parotid gland and the tendon of insertion of the sterno-maxillaris; 
deeply, to the guttural pouch, the submaxillary gland, and the larynx and 
pharynx. The median tendon passes through the ring of the hyoideus 
magnus. The lower belly is in contact, outwards, with the ramus of the 
inferior maxilla; inwards, with the mylo-hyoideus muscle. 

Action.—When this muscle contracts, it acts at the same time on the 
hyoid bone, which it raises in becoming straight, and on the lower jaw, 
which it pulls backwards and depresses at the same time. 


C. Hyoideal Region. 


This region includes six muscles grouped around the os hyoides, which 
they move. Five of these are pairs: the mylo-hyoideus, genio-hyoideus, stylo- 
hyoideus, kerato-hyoideus, and the occipito-styloideus. ‘The single one is the 
transversalis hyoidei. 


Preparation.—Separate ‘the head from the trunk, and remove the muscles of the 
cheeks on one side, with the parotid gland. 2. The branch of the inferior maxilla being 
thus exposed, it is sawn through in two places; at first behind the last molar, then in 
front of the first. 3. After having separated the pterygoids and the stylo-maxillaris 
from the upper fragment or condyle, and the coronoid process, it is torn off by pulling 
it backwards ; then the pterygoids and the digastricus are excised. 4. The inferior fragment 
of the jaw bearing the molar teeth is turned down by isolating the mylo-hyoideus from the 
mucous membrane. 5. Carefully remove the tongue by separating its extrinsic muscles 
from the genio-hyoideus, the anterior appendix of the hyoid bone, the transverse muscle, 
and the small hyoideus, ‘ 

The dissection having been performed in this manner, the large hyoideal branch may 
be separated from the small, by sawing through the head longitudinally, leaving the 
symphysis menti intact, and turning down the corresponding half to the side already 
dissected, as well as the great hyoid branch, the pharynx, larynx, and soft palate. 


1. Mylo-hyoideus. 


Form—Situation—Structure—A membranous muscle situated in the 
intermaxillary space, flattened from side to side, elongated in the direction 


Lgmis is the fasciculus which Bourgelat has described as a distinct muscle, and 
na the stylo-maxillaris. 


226 THE MUSCLES. 


of the head, thinner and narrower below than above, and formed entirely of 
fleshy fibres which extend transversely from its anterior to its posterior 
border, Inferiorly, it is composed of a small fasciculus, which is 
distinguished from the principal portion by the slightly. different direction 
of its fibres, and which covers in part the external surface of the muscle, 


Fig. 11 


HYOIDEAL AND PHARYNGEAL REGIONS. 

1, Neck of inferior maxilla; 2, Hard palate; 3, Molar teeth ; 4, Buccal membrane; 5, 
Submaxillary glands; 6, Soft palate; 7, Tendon of hyoideus magnus through 
which the tendon, 8, of she digastricus passes; 9, Lower portion of digastricus; 
10, Stylo-hyoideus; 11, Buccal nerve; 12, Zygomatic arch, 13, Orbital branch 
of fifth pair of nerves; 14, Articular process of temporal bone; 15, Right cornu of 
hyoid bone; 16, Hyo-glossus longus, or Kerato-glossus; 17, Lingual nerve; 18, 18, 
Tongue; 19, Angle of left branch of inferior maxilla; 20, Submaxillary gland, 
left side; 21, Subscapulo-hyoideus; 22, Great hypoglossal nerve; 23, Hyo- 
thyroideus; 24, Sterno-hyoideus; 25, Sterno-thyroideus; 26, Subscapulo hyoi- 
deus; 27, Thyroid gland; 28, External carotid artery ; 29, Pneumogastiic nerve; 
30, Stylo-hyoideus ; 31, Genio-hyoideus, 


Attachments.—It originates from the mylo-hyoid line by the anterior 
extremities of its fibres. Its movable insertion takes place on the inferior 
face of the hyoid body, on its anterior appendix, and on a fibrous raphé which 
extends from the free extremity of this appendix to near the genial surface, 
and which unites, on the median line, the two mylo-hyoidean muscles. 

Relations.—By its external face, with the inferior maxilla, the digastric 
muscle, and the submaxillary lymphatic glands. By its internal face, with 
the sublingual gland, the Whartonian duct, the hypoglossal and lingual 
nerves, the genio-glossus, hyo-tlossus longus and brevis, and genio-hyoideus. 
Its superior border responds to the internal pterygoid. 

Action.—In uniting on the median line with that of the opposite side, 
this muscle forms a kind of wide band or brace on which the tongue rests. 
When it contracts, it elevates this organ, or rather applies it against the 
palate. 


2. Genio-hyoideus. 
Form—Structure—Situation.—A. fleshy, elongated, and a i. 


tendinous at its extremities, but especially at the inferior one, and ap , 
with its fellow of the opposite side, to the mylo-hyoidean brace. 


MUSCLES OF THE HEAD, 227 


: Attachments— By its inferior extremity it is fixed to the genial surface— 
origin ; by its superior, it reaches the free extremity of the anterior appendix 
of the hyoid body—-termination. 

Relations.—Outwards und downwards, with the mylo-hyoideus ; inwards, 
with its fellow, which is parallel to it; above, with the genio-glossus. 


Action.—It draws the hyoid bone towards the anterior and inferior part 
of the intermaxillary space. 


8. Stylo-hyoideus. 
(Synonyms.—The hyoideus magnus of Percivall. The kerato-hyoideus magnus of Leyh.) 


Form — Structure — Situation — Direction —Thin and fusiform, this 
muscle, smaller than the preceding, and, like it, tendinous at both its 
extremities, is situated on the side of the laryngo-pharyngeal apparatus and 
the guttural pouch, behind the large branch of the hyoid bone, whose 
direction it follows. 

Attachments.—Above, to the superior and posterior angle of the styloid 
bone—fiwed insertion; below, to the base of the cornu of the os hyoides 
—movable insertion. 

Relations—Outwards, with the pterygoideus internus; inwards, with 
the guttural pouch, the pharynx, and hypoglossal nerve. Its anterior 
border is separated from the posterior border of the styloid bone by the 
glosso-facial artery and glosso-pharyngeal nerve; along the posterior 
border lies the upper belly of the digastricus, Its inferior tendon is 
perforated by a ring for the passage of the cord intermediate to the two 
portions of the latter muscle. 

Action.—It is antagonistic to the preceding muscle, drawing the body of 
the hyoid bone backwards and upwards. 


4. Kerato-hyotdeus. 


‘; ae is the hyoideus parvus of Percivall, and the small kerato-hyoideus of 
eyh ) 

A very small fasciculus, triangular in shape, and flattened on both sides. 
Inserted, on one side, into the posterior border of the styloid cornu and the 
inferior extremity of the styloid bone; and on the other, to the superior 
border of the thyroid cornu. It responds, outwardly, to the basio-glossus 
and the lingual artery; inwardly, to the buccal mucous membrane. 

It approximates the cornua of the os hyoides to each other. 


5. Occipito-styloideus. 


Synonyms.—This is the muscle which, up to the present time, has been described by 
veterinary anatomists as the stylo-hyoideus. This name has been given to the muscle 
named by Girard the kerato-hyoideus magnus. 


A small, flat, and triangular muscle like the preceding, yet thicker and 
more spread, filling the space comprised between the styloid process of the 
occipital and the horizontal portion of the posterior border of the styloid 
bone. Its fasciculi become longer as they are situated posteriorly, are 
rather tendinous, and are carried from one of these bones to the other. 
Outwardly, it responds to the parotid gland; inwardly, to the guttural 
pouch, which it covers for its whole extent; its posterior border is largely 
confounded with the superior insertion of the digastricus. When this 
muscle*acts, it causes the os hyoides to swing, carrying its inferior extremity 
backwards and downwards. 


228 THE MUSCLE 


6. Transversalis Hyoidet. 


By this name Bourgelat has described a short riband of parallel muscular 
fibres, which unites the superior extremities of the styloid cornua, and 
approximates them to each other. : 


DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE HEAD IN OTHER THAN SOLIPED 
ANIMALS. : 


A. Facial Region. 


Rominants.—There are found in the Oz. 


1. An orbicular muscle of the lips, analogous to that in the Horse. 

2. An alveolo-labialis of the same kind (fig. 112, 5). 

3. A zyqomaticus or zygomatico-labialis, stronger and redder than in Solipeds. 
Its aponeurosis of origin, covered by the cuticularis muscle of the face, extends upon. 
the surface of the masseter muscle as far back as the zygomatic arch, to which it ig 
attached (fig. 112, 7). 


Fig. 112. 


SUPERFICIAL MUSCLES OF THE OX’S HEAD. 

1, Supermazillo-labialis; 1, 1’, Accessory fasciculi of the supermaxillo-labialis ; 
2, Supermaxillo-nasalis magnus; 3, Supernaso-labialis; 4 Lachrymalis; 5, 
Alveolo-labialis; 6, Maxillo-labialis confounded with the preceding; 7, Zygo- 
matico-labialis; 8, Frontal, or cuticularis muscle of the forehead; 9, Orbicular 
muscle of the eyelids; 10, Zygomatico-auricularis; 11, External temporo-auricu- 
laris; 12, Scutiform cartilage; 13, External scuto-auricularis; 14, Mastoid 
process; 15, Masseter; 16, Stylo-hyoideus; 17, Digastricus; 18, Sterno-maxil- 
lary fasciculus belonging to the cuticularis muscle of the neck; 19, Trachelo- 
hyoideus (subscapulo-hyoideus); 20, Sterno-suboccipitalis (sterno-maxillaris, 
or mastoideus); 21, Anterior branch of the superficial portion of the mastoido- 
humeralis (levator humeri); 22, Superior branch of ditto; 23, Deep portion of 
same muscle; 24, Trachelo-atloideus, peculiar to Ruminants and Pachyderms ; 
25, Great anterior straight muscle of the head, 


MUSCLES OF THE HEAD. 229 


4. A lachrymalis, thicker and more developed than in the Horse. Its most anterior 
fibres glide beneath the zygomaticus, and are lost on the alveolo-labialis surface: the 
most posterior pass over the aponeurotic tendon of the zygomatico-labialis, and are 
confounded witb those of the cuticularis. Above, it joins the orbicularis of the eyelids 
in a still more intimate manner than in the Horse; go that it is almost impossible to 
distinguish the limits of the two muscles (fig. 112, 4). 

5. A supernaso-labialis continued, above, with the inferior border of the frontal or 
fronto-cuticularis muscle; and divided, inferiorly, into two branches, which comprise 
between them the supermaxillo-labialis and the pyramidalis-nasalis. These two 
branches, however, are not disposed as in Solipeds, the anterior covering the preceding 
muscles, and the posterior, of but little importance, passing beneath them to lose itself 
in the substance of the upper lip (fig. 112, 3). 

6. A supermaxillo-labialis, which gains the middle of the muzzle by passing along 
the inner side of the nostrils (fig. 112, 1). 

7. Two additional supermazillo-labialis muscles, considered as accessories to the 
first, and which originate with it. Each terminates by a ramifying tendon that passes 
under the nostril to mix in the tissue of the upper lip (fig. 112, 1’,1'). 

8. A pyramidalis or great supermasxillo-nasulis, situated between the supermaxillo- 
labialis and its two accessory muscles, and deriving its origin, in common with these 
three muscles, in front of the maxillary spine (fig. 112, 2). 

, 9. A mazillo-labialis, confounded with the alveolo-labialis, and having no terminal 
endon. 

10. A mento-labialis, attached to the body of the inferior maxillary bone, as in the 
Horse, by two middle posterior muscles. No anterior middle muscle has been found by 
us; and it is certain that there is no naso-transversalis or small supermazillo-nasalis 
present. 

In the Sheep, the supernaso-labialis does not exist; apart from this peculiarity, 
there is no difference between the facial muscles of this animal and the Ox. 

Pic.—This animal has neither the lachrymalis, supernaso-labialis, or naso-transver- 
salis muscles. The small supermaxillo-nasalis is present ; it is short, very thick, and 
situated near the margin of the nostrils. The supermazillo-labialis and the great 
supermaxillo-nasalis are replaced by three fleshy bodies, nearly parallel, lying on the 
side of the face. The superior originates in the lachrymal fossa, and terminates by a 
tendon in the middle of the snout. The inferior, with the middle, leaves the imprints 
in front of the zygomatic ridge, and is continued at its inferior extremity by a tendon 
divided into several fibrille, which pass below the nostril to be united to the tendon of 
the superior portion : this is done in such a manner that the external opening of the 
nose is encircled on the inner side by a kind of fibrous cravat which, when these two 
muscles contract, carries this opening outwards, It will also be understood that the 
superior fleshy body, acting alone, ought to elevate the snout, while the inferior 
depresses it in drawing it to one side. With regard to the intermediate fleshy mass, it 
is the representative of the pyramidalis of the Ox, and terminates in a great quantity of 
tendinous fibrillz at the internal ala of the nose. 

Caryivora.—In the Dog and Cat the following peculiarities are found :— 

The labialis (or orbicularis) is quite rudimentary. 

The buccinator is very thin and formed of only one muscular plane. 

The zygomatico-labialis is continued, superiorly, with the zygomato-auricuralis. 

The supernaso-labialis represents a wide, undivided, muscular expansion, united 
superiorly to the cuticularis of the forehead, and terminating inferiorly on the upper 
lip. 
The supermazillo-labialis and the supermazillo-nasalis magnus constitute a single 
fleshy body formed of several parallel fasciculi, which take their origin above the supra- 
orbital foramen, and terminate together at the external wing of the nose and in the 
upper lip. 

There is no supermaxillo-nasalis parvus, or naso-transversalis. 

The middle anterior (depressor alz nasi) is perfectly developed. 

The mento-labialis and its suspensory muscle. the middle posterior, are scarcely 
apparent. 


B. Masseteric or Temporo-mazillary Region. 


In Ruminants, the masseler and temporal are not so large as in Solipeds. In the 
Carnivora, however, they offer a remarkable development. The origin of the ptery- 
goideus internus in Ruminants is nearer the middle line than in the Horse. Its obliquity 
si also greater, and the movements of diduction it gives the lower jaw are more 


18 


230 THE MUSCLES. 


extensive. In all the animals, the stylo-masillaris fasciculus of the digastricus is 
entirely absent, and the muscle has only a single belly extending directly from the 
occipital to the maxillary bone. In the Ox is found a small square muscle, formed of 
transverse fibres, which unites the two digastric muscles by passing beneath the base of 
the tongue. This muscle, in contracting, may raise the hyoideal apparatus, and in this 
way supplements the tendon of the digastricus and the inferior ring of the stylo- 
hyoideus. 


C. Hyoid Region. 


The two fleshy planes composing the mylo-hyoideus are more distinct in Ruminants 
than in the Horse. The stylo-hyoideus of these animals commences by « long thin 
tendon. The muscle has no ring for the passage of the digastricus, a feature observed 
in all the domesticated animals except Solipeds. 

In the Carnivora, the stylo-hyoideus, formed by a narrow, very thin, and pale 
fleshy band, commences on the mastoid portion of the temporal bone by a small tendon; 
the kerato-hyoideus is remarkable for its relatively considerable volume ; the oceipito- 
styloideus and the transversalis hyoideus are absent. 


COMPARISON OF THE MUSCLES OF THE HUMAN HEAD WITH THOSE OF THE DOMESTICATED 
ANIMALS, 


In Man, there are described as muscles of the head, the epicranial muscles, muscles of 
the face, and those of the lower jaw, The hyoid and digastric muscles are reckoned in 
the region of the neck. Here they will be placed in the region of the head. 


A. Epicranial Muscles. 


The middle portion of the human cranium is covered by an aponeurosis that adheres 
closely to the hairy scalp, but glides easily on the surface of the bones. To the circum- 
ference of this epicranial aponeurosis are attached four muscles which move it. One 
of them, attached behind to the superior occipital curved line, is named the occipital 
muscle ; another, fixed in front of the forehead, is called the frontal muscle ; the other two, 
double and lateral, are inserted on the face of the temporal bone or the external ear, 
and are designated auricular muscles. These epicranial muscles move the scalp for- 
wards, backwards, and sideways. 


B. Museles of the Face. 


These are fourteen in number, ten of which are found in the domesticated animals, 
We commence by describing these common muscles (fig. 113). 

1. The orbicularis of the lips, which has a fasciculus that passes to the skin from the 
columna of the nose; this fasciculus is termed the depressor of the columna, or 
moustache muscle (naso labialis). 

2. The buccinator, corresponding to the alveolo-labialis of animals. Besides its office 
in mastication, it takes an important part in the blowing of wind instruments. 

3. The superficial elevator of the wing of the nose and the upper lip. It resembles the 
supernaso-labialis, descends from the orbital margin of the supermaxilla, passes along 
the wing of the nose, and is lost in the upper lip. 

4. The deep elevator of the wing of the nose and the upper lip, whose analogue is 
found in the supermaxillo-labialis of animals. 

5. The great zygomaticus, whose presence is constant in all species. 

6. The small zygomaticus. represented in the Horse by only the small oblique 
fasciculus sometimes found beneath the great zygomaticus. 

The small zygomaticus and the two elevators of the lips are lachrymal muscles; by 
their simultaneous contraction they express discontent and melancholy. The great 
zygomaticus, on the coutrary, is the muscle of laughter; it draws the commissures of 
the lips outwards. 

7. The canine, or great supermaxillo-nasal of animals, is attached beneath the infra- 
orbital foramen, and terminates in the skin of the upper lip. 

8. The risorius of Santorini. 

9. The muscle of the chin (mento-lalialis). 

10. ‘The myrtiformis, or middle anterior of Bourgelat. 

The other facial muscles of Man, whose analogues it is difficult or impossible to find 
in animals, are :— 


MUSCLES OF THE TRUNK. 231 


11. The triangularis of the lips, which is inserted into the anterior face of the 


inferior maxilla, and is carried upwards to the 
commissure of the lips. By its contraction it 
gives the face an expression of melancholy or 
contempt. 

12. The quadratus menti, which, after being 
attached to the maxilla within the mental fora. 
men, passes upwards on the skin of the lower 
lip, which it depresses, and thus contributes to 
the expression of fear or dismay. 

13. The transversalis nasi (compressor nas’), 
a muscle which is fixed into the supermaxilla 
and on the bridge of the nose, where it is con- 
founded with the opposite muscle. 

14. The dilator of the ala of the nostril, a 
very small triangular fasciculus applied to the 
external part of the nostril, which, by contract- 
ing, it elevates. 


C. Muscles of the Lower Jaw. 


There is nothing remarkable to be noted in 
the masseter, temporal, or pterygoid muscles, 
The upper belly of the digastricus is not at- 
tached directly to the inferior maxilla. 


D. Hyoid Muscles. 


These are only three in number :— 

1. The mylo-hyoideus. 

2. The stylo-hyoideus, which commences at 
the styloid process of the temporal bone, and 
shows a ring for the tendon of the digastricus, 

3. The genio-hyoideus. 

We do not find in Man the occipito-styloideus, 
kerato-hyoideus, or the transversalis-byoideus. 


Axillary Region. 

This comprises two muscles, pairs, 
placed beneath the sternum, in the arm- 
pit, which terminate on the anterior limb. 
These are the superficial and deep pec- 
torals.+ 


Preparation—i. Place the animal in the 
first position. 2. Unfasten one of the fore-limbs, 
and allow it to hang, so as to separate it from 
the opposite one. 3. Remove the skin with 
care, and dissect, on the side corresponding to 
the detached limb, the two muscles which form 
the superficial pectoral, 4, Prepare the deep 
pectoral on the opposite side. To do this, 


Fig. 113. 


MUSCLES OF THE HUMAN HEAD, 
SUPERFICIAL LAYER, 


1, Frontal portion of the occipito-fronta- 


lis; 2, Its occipital portion; 3, Its 
aponeurosis; 4, Orbicularis palpebra- 
rum; 5, Pyramidalis nasi; 6, Com- 
pressor nasi; 7, Orbicularis oris; 8, 
Levator labii superioris aleque nasi; 
9, Levator labii superioris proprius ; 
10, Zygomaticus minor; 11, Zygo- 
maticus major; 12, Depressor labii 
inferioris; 13, Depressor anguli oris; 
14, Levator labii inferioris; 15, Super- 
ficial portion of masseter; 16, Its deep 
portion; 17, Attrahens aurem; 18, 
Buccinator; 19, Attollens aurem; 20, 
Temporal fascia covering temporal 
muscle; 21, Retrahens aurem; 22, 
Anterior belly of the digastricus, with 
tendon passing through pulley; 23, 
Stylo-hyoid muscle; 24, Mylo-hyoi- 
deus; 25, Upper part of sterno-mas- 
toid; 26, Upper part of trapezius— 
the muscle between 25 and 26 is the 
splenius. 


remove the panniculus cautiously, so as not to injure the muscle about to be examined ; 
divide the superficial pectoral transversely, and turn back the ent portions to the right and 
left: divide also the mastoido-humeralis (levator humeri) and cervical trapezius near 
their insertion into the limb, and reflect them upon the neck. 


1. Superficial Pectoral. (Fig. 114, 9, 10.) 


Symonyms.~-Muscle common to the arm and fore-arm—Bourgelat. Pectoralis magnus 
of Men. t pestoralis transversus—Percivall. Leyh divides this muscle into two portions, 
which he designates the sterno-radialis and small sterno-humeralis). 


F.r a justification of the employment of these uew denominations, see the note 


at p. 177. 


232 


— 


\ 


( Mi) 
Wl 


MUSCLES OF THE AXILLARY AND 
CERVICAL REGIONS. 


Portion of the cuticularis colli; 2, An- 
terior portion of the mastoido-hume- 
ralis; 3, Posterior portion of ditto; 4, 
Sterno-maxillaris ; 5, Subscapulo-hyoi- 
deus; 6, Sterno-hyoideus; 7, Sterno- 
thyroideus; 8, Scalenus; 9, Sterno- 
humeralis; 10, Sterno-aponeuroticus ; 
11, Sterno-trochineus (pectoralis mag- 
nus); 12, Portion of the fascia en- 
veloping the coraco-radialis, receiving 
part of the fibres of the sterno-trochi- 
neus; 13, Sterno-prescapularis; 14, 
{ts terminal aponeurosis, 


THE MUSCLES. 


Situation—Composition.—This muscle 
is situated between the two anterior 
limbs, occupies the inferior surface of 
the chest, and is formed by two por- 
tions which adhere closely to each other, 
but are yet perfectly distinct. Following 
the example of Girard, we will describe 
these as two particular muscles by the 
names of sterno-humeralis, and sterno- 
aponeuroticus. 

A. Srervo-HumeRatis. — Form — 
Structure.— This is a short, bulky muscle, 
flattened above and below, contracted at 
its termination, and composed almost 
entirely of thick parallel fibres. 

Direction and Attachments.—It com- 
mences on the anterior appendage and the 
inferior border of the sternum, and is 
directed obliquely backwards, downwards, 
and inwards, to reach the anterior ridge 
of the humerus, where it terminates by 
an aponeurosis common to it, the mas- 
toido humeralis, and the sterno-aponeuro- 
ticus. 

Relations—It responds, by its ex- 
ternal face, to the skin, from which it is 
separated by a cellular layer, and to the 
inferior extremity of the cuticularis 
colli; by its internal face, to the sterno- 
aponeuroticus and sterno-prescapularis. 
Its anterior border forms, with the mas- 
toido-humeralis, a triangular space occn- 
pied by the subcutaneous, or “ plate,” vein 
of the arm. 

Action—It acts principally as an 
adductor of the anterior limb. 

B. Srervo-aponevrotricus.—Form— 
Structure — Direction — Attachments. —A 
very wide, thin, and pale quadrilateral 
muscle formed of parallel fleshy fibres, 
which arise from the entire inferior 
border of the sternum, to pass at first 
outwards, then downwards, and terminate 
in the following manner: the anterior 
fibres go to the aponeurosis which attaches 
the mastoido-humeralis and sterno-hu- 
meralis to the anterior ridge of the 
humerus; the posterior fibres are also 
continued by a very thin fascia, which is 
spread inside the limb to the external 
face of the antibrachial aponeurosis. 

Relations—By its superficial face, 


MUSCLES OF THE TRUNK. 233 


with the skin, which adheres intimately to it by means of a dense cellular 
tissue, and with the sterno-humeralis, which covers its anterior border. 
By its deep face, with the two portions of the deep pectoral, the coraco- 
radialis (flexor brachii), and the long extensor of the fore-arm; it 
also responds, by this face, to the antibrachial aponeurosis and the sub- 
cutaneous vein of the fore-arm, which it maintains applied against that 
aponeurosis, 

Action—It is an adductor of the anterior limb, and a tensor of the 
antibrachial aponeurosis. 


2. Deep Pectoral. (Figs. 114, 11, 18; 115, 1.) 


Synonym.—The pectoralis parvus of Man. 


Volume—Situation—Composition—An enormous muscle, situated be- 
neath the thorax, and composed, like the preceding, of two perfectly distinct 
portions, described by Girard as two muscles, and designated by him as the 
sterno-trochineus and sterno-prescapularis. 

A. Srerno-rrocuineus.—Pectoralis magnus of (Percivall, Rigot, and) 
Bourgelat. (The great sterno-humeralis of Leyh.) 

Volume—Extent.—This muscle, the largest of the two, offers a con- 
siderable volume. Extending from the ninth or tenth rib to the upper 
extremity of the arm, it at first lies beneath and against the abdomen, then 
beneath the chest, and at last is comprised between the walls of the latter 
cavity, and the internal face of the anterior limb. 

Form.—It is thin and flat above and below in its posterior third, thicker 
and depressed from side to side in its middle third, and narrow and pris- 
matic in its anterior third. Its general form may be compared to that of a 
somewhat irregular triangle, elongated from before to behind, which would 
have a very short posterior border, a longer internal or infcrior border, and 
an external or superior still more extensive. 

Structure.—It is entirely composed of thick, parallel, fleshy fasciculi, all 
of which leave the posterior or internal border of the muscle to gain its 
narrow or anterior extremity. These fasciculi, as they approach the superior 
border, become longer, and those which proceed from the posterior border com- 
mence by aponeurotic fibres. Unfrequent intersections of fibrous tissue 
exist towards the anterior extremity of the muscle. 

Attachments.—It originates: 1, From the tunica abdominalis by the apo- 
neurotic fasciculi of its posterior border; 2, By its internal border, from the 
posterior two-thirds of the inferior border of the sternum. It terminates, by 
its anterior extremity, on the internal tubercle at the head of the humerus, 
the tendon of origin of the coraco-humeralis, and the fascia enveloping the 
coraco-radialis. Through the medium of this fascia, it is inserted into the 
external lip of the bicipital groove formed by the great trochanter, and is 
united to the two terminal branches of the supraspinatus muscles. (See 
Fig. 114, 12.) oes . ; 

Relations.—Its deep face, which is successively superior and internal, 
covers the external oblique and the straight muscle of the abdomen, the 
serratus magnus, costo-sternalis, and sterno-prescapularis, as well as some 
thoraco-muscular nerves; all these relations are maintained by means of a 
loose and abundant cellular tissue. Its superior face, which alternately 
looks downwards and outwards, responds: to the skin, from which it is 
separated by a slight cellulo-fibrous fascia; to the sterno-aponeuroticus ; 
and to the muscles, vessels, and nerves of the inner aspect of the arm, through. 


234 THE MUSCLES. 


the medium of the subbrachial aponeurosis of the panniculus and a con- 
siderable quantity of cellular tissue. Its upper border adheres in an intimate 
manner to the last-named muscle, and is bordered by the spur (external 
thoracic) vein. The large vascular trunks which leave the chest to reach 


Their attachment to the sternum; 5, 
16, Panniculus; 8, 19, Levator humeri, 


ctoral muscle; 11, Sterno-thyroideus; 12, 
15, Rhomboideus; 17, Point of sternum ; 


alis parvus; 3, Superficial pectoral, or pectoralis trans- 


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the anterior limb, pass above its anterior extremity, by crossing its 
direction. 


Action.—It pulls the whole limb backwards, in pressing on the angle of 
the shoulder. ; 


B. Srerno-prescarutarts.—(The pectoralis parvus of Percivall and 
Bourgelat.)—Form—Situation—Direction.—A long prismatic muscle, con- 


MUSCLES OF THE TRUNK. 235 


tracted at its two extremities, situated in front of the preceding, arising 
from the sternum, directed forwards and outwards towards the scapulo- 
humeral angle, and afterwards reflected upwards and backwards on the 
anterior border of the shoulder, which it follows to near the cervical angle 
of the scapula. 

Structure and Attachments.—It is formed of very large fleshy fasciculi, 
analogous to those of the sterno-trochineus, which originate, by their 
inferior extremities, from the sides of the sternal keel and the cartilages of 
the first three or four ribs. They follow the direction of the muscle, and 
terminate, one above the other, on a short aponeurosis which covers the 
supraspinatus, and is confounded with the external aponeurosis of the 
scapula (Fig. 114, 14). 

Relations.—In its axillary portion, this muscle responds, inwardly, to 
the costo-sternalis, the first sternal cartilages, and the corresponding inter- 
costal muscles: outwards, to the sterno-trochineus and sterno-aponeuroticus. 
In its prescapular portion, it is in relation, outwardly, with the mastoido- 
humeralis and trapezius; inwardly, with the subscapulo-hyoideus, the 
scalenus, and the angularis of the scapula; behind, with the supraspinatus 
which is separated from it by the external scapular aponeurosis. 

Action.—This muscle is a congener of the sterno-trochineus, and pulls 
the scapula backwards and downwards. It is also a tensor of the scapular 
aponeurosis. 


DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE AXILLARY REGION IN OTHER 
THAN SOLIPED ANIMALS, 


With regard to the superficial pectoral, it is remarked that in the Ox, Sheep, and 
Pig, the sterno-humeralis is small and less distinct from the sterno-aponeuroticus than in 
Solipeds; and that in the Dog and Cat, the sternc-aponeuroticus is very thin and 
narrow. . 

In the deep pectoral there is found, in the Oz, a sterno-prescapularis scarcely distinct 
from the sterno-trochineus, and which does not extend beyond the inferior extremity of 
tle supraspinatus. In the Sheep, this muscle is quite confounded with the sterno- 
trochineus. In the Pg, the sterno-prescapularis somewhat resembles that of the Horse. 
Ita inferior extremity only covers the first chondro-sternal articulation; the superior 
extremity is more voluminous.’ With regard to the sterno-trochineus, it terminates on 
the summit of the great trochanter, after detaching a short branch t» the tendon of the 
coraco-humeralis. The sterno-prescapularis of the Dog is very feeble, and terminates 
with the principal muscle on the Lumerus. 


COSTAL REGION. 


In each costal region we find fifty-four muscles, which concur, more or 
less directly, in the respiratory movements. These muscles are: 1, The 
great serratus ; 2, The costo-transversalis ; 8, Seventeen external intercostals ; 
4, Seventeen internal intercostals; 5, Seventeen supercostals; 6, The 
triangularis sternt. . 


Preparation.—1. Place the subject in the second position. 2. Remove the fore- 
limb and all the muscles attaching it to the trunk, by sawing through the scapula as 
shown in figure 108, inorder to expose the great serratus and costo-transversalis muscles ; 
finish the dissection of the former by taking away all the yellow fibrous tissue which 
covers its posterior dentations. 3, Study the external intercostals and the supercostals, 
afier removing the great oblique muscle of the abdomen, the serrati muscles, the 
common intercostal (ilio-costalis), and the ilio-spinalis, 4, Excise some external inter- 
costals in order to*show the corresponding internal ones. 5. The triangularis is dis- 
sected on another portion, which is obtained in separating the sternum from the thorax 
by sawing through the sternal ribs a little above their inferior extremity. 


236 THE MUSCLES. 


1. Great Serratus, (Fig. 105, 15.) 


Synonyms.—Costo-subscapularis—Girard. Posterior portion of the serratus magnus of 
Bourgelat. (A portion of Percivall'’s serratus magnus.) 


Form—Situation—A very wide muscle, disposed like a fan, split up 
into digitations at its inferior border, applied against the thoracic walls, and 
partly concealed by the shoulder. 

Structure—It is composed of divergent fleshy fibres, all of which con- 
verge towards the superior extremity of the scapula, and are covered by 
a very strong aponeurosis that gradually diminishes from above to below, 
and only adheres to the muscle in its inferior part. 

Attachments.—1, To the external face of the eight sternal ribs; 2, To 
the anterior triangular surface of the internal face of the scapula, behind the 
angularis, with which it is confounded; 8, To the whole extent of the 
posterior triangular surface of that bone. 

On reaching the scapula, the aponeurosis separates from the fleshy 
fibres, and is inserted alone into the fibrous plane which covers the muscular 
fasciculi of the subscapularis. 

Relations.—The great serratus responds: outwardly, and through the 
medium of an abundant supply of cellular tissue, which facilitates the play 
of the limb against the lateral wall of the thorax, to the subscapularis, 
supraspinatus, the adductor of the arm, great dorsal (latissimus dorsi), and 
the mass of olecranian muscles; inwardly, to the first seven external inter- 
costals, to the sides of the sternum, and the anterior small serratus. Its four 
posterior digitations cross the first five of the great oblique muscle of the 
abdomen, and are covered by a prolongation of the abdominal tunic. 

Action.—With that of the opposite side, this muscle constitutes a vast 
brace or girth on which the thorax rests when the animal is supported on 
its limbs; it therefore acts, in relation to the trunk, like a suspensory 
ligament. When it.contracts, its fixed point being the thoracic walls, it 
pulls the superior extremity of the scapula downward and backward, and 
causes this portion of the limb ‘to perform a swinging movement which 
carries the inferior angle upwards and forwards. If the limb is the fixed 
point, then it raises the thorax between the two anterior members, and 
assists in the respiratory movements by elevating the ribs. 


2. Transverse Muscle of the Ribs. (Fig. 105, 16.) 
Synonyms,—Costo-sternalis—Girard. (Lateralis sterni—Percivall.) 


Form — Structure — Direction — Situation. This is a flattened band, 
aponeurotic at its extremities, oblique from upwards and forwards, and 
situated under the preceding muscle, at the inner aspect of the deep pectoral. 

Attachments.—Its posterior extremity is fixed to the sternum and the 
fourth sternal cartilage; the anterior to the external face of the first rib. 

Relations—Inwardly, with the second and third ribs, into which are 
often inserted some of its fasciculi, and with the three first intercostal 
muscles. Outwardly, with the two portions of the deep pectoral muscle. 

Action.—This is an auxiliary to the expiratory muscles. (Leyh says its 
action is to raise the ribs and their cartilages, and thus to enlarge the 
anterior portion of the thorax during inspiration.) 


THE MUSCLES. 237 


3. External Intercostals. (Fig. 104, 68.) 


Situation—Form.—These muscles fill the spaces between the ribs, but 
do not descend beyond their inferior extremities; they, therefore, do not 
occupy the intervals between the cartilages. They are flattened, fleshy 
bands, gradually diminishing in thickness from above to below. 

Structure — Attachments.—Each intercostal muscle is composed of a 
series of muscular fasciculi, intermixed with numerous aponeurotic fibres, 
both of which pass obliquely backwards and downwards, from the posterior 
border of the preceding to the external face of the succeeding rib. 

Relations.—They respond, outwardly, to the different muscles applied 
against the thoracic walls; inwardly, to the internal intercostals. 


4, Internal Intercostals. (Fig. 106, 16.) 


These are placed at the internal face of the preceding, which they exactly 
repeat with regard to their general form, but from which they differ in the 
following points : 

1. Very thick between the costal cartilages, these muscles are reduced 
at the upper part of the intercostal spaces to a thin aponeurotic layer, 
supported only by some fleshy fibres. They therefore gradually diminish 
in thickness from below upwards. 

2. Their fasciculi are less tendinous than those of the external inter- 
costals, and are carried obliquely forward and downward, from the anterior 
border of the posterior rib to the posterior border and internal face of the 
rib in front; so that the fibres of the external and internal intercostals cross 
each other like the letter X. 

3. Outwardly, they respond to the external intercostals; inwardly, to 
the costal pleura. 

Action of the intercostal muscles—The function of these muscles has been 
for a long time, and is even now, much discussed; and it may be said that 
there were never, perhaps, more diverse or contrary opinions given on any 
subject than on this. M. Bérard, who has summed up the elements of the 
discussion with the greatest judgment, considers the external intercostals as 
inspiratory muscles, and the internal ones also as inspiratory by those 
fasciculi which occupy the spaces between the costal cartilages; the 
remainder, the majority, are expiratory. 


5. Supercostals. 
Synonyms.—Transverso-costales—Girard. (Levatores costarum—Percivail.) 


Small, flat, triangular, muscular and tendinous fasciculi, constituting, 
. it might be said, the heads of the external intercostals, from which they are 
scarcely distinguishable in the first and last costal intervals. 

They arise from the transverse processes of the dorsal vertebre, and are 
directed backwards and outwards, gradually expanding, to terminate on the 
external face of the one or two ribs which succced their fixed insertion. 
Outwardly, they respond to the ilio-spinalis; inwardly, to the external 
intercostals. ; 

The supercostals draw the ribs forward, and are consequently inspiratory 
muscles. 

6. Triangularis of the Sternum. 


Synonyms.—Sternalis—Bourgelat. Sterno-costalis—Girard. ‘The sterno-costales of 
Percivall, and sterno-costalis of Leyh.) 


238 THE MUSCLES. 


Form—Situation—This muscle, flattened above and below, elongated 
from ‘before to behind, and dentated at its external or superior border, is 
situated in the thoracic cavity, above the sternum and the cartilages of the 
true ribs. 

Attachments—It is fixed, by its internal border, on the superior face 
of the sternum, to the ligamentous cord which circumscribes it outwardly. 
It has its movable insertion on the cartilages of the sternal ribs, the first 
excepted, by means of digitations from its external border. 

Structure.—It is formed of strongly aponeurotic muscular fasciculi, which 
are directed from the internal to the external border. 

Relations.—Inwardly, with the pleura; outwardly, with the cartilages to 
which it is attached, the internal intercostals, and the internal thoracic vein 
and artery. 

Action—The triangularis of the sternum concurs in expiration by 
depressing the costal cartilages. (Leyh asserts that if the fixed point 
be the sternum, this muscle pulls the ribs forwards, and so widens the 
thoracic cage ; but if the fixed point is the ribs, the sternum will be raised 
and the thoracic space diminished.) 


DIFFERENTIAL CHARACTERS IN THE MUSCLES OF THE COSTAL REGION IN OTHER 
THAN SOLIPED ANIMALS. 


The muscles of the costal region cannot be the same in number in all the domes- 
ticated animals; the intercostals and supercostals, for instance, must vary in number 
with that of the ribs. Beyond this, the differences are slight. In the (x, the great 
serratus is very extensive, and the portion which passes to the posterior triangular 
surface of the scapula is readily distinguished from the anterior by its diminished 
thickness, the larger proportion of aponeurotic fibres it contains, and the flattened 
tendon by means of which it is inserted. In the Pig, it is remarked that the intertial 
intercostals are prolonged, maintaining a certain thickness, to near the vertebral column. 


COMPARISON OF THE THORACIC MUSCLES OF MAN WITH THOSE OF THE DOMESTICATED 
ANIMALS, 


The muscles of the axillary region, the costal region, and the diaphragm are desig- 
nated in Man as the thoracic muscles. 

The pectoral muscles are distinguished into great and small. The great pectoral 
corresponds to the superficial pectoral of the Horse. It is attached, on one side, to the 
inner two-thirds of the clavicle, the anterior face of the sternum, and the cartilages of 
the first six ribs; on the other, to the anterior border of the bicipital groove and, by a 
fibrous expansion, to the aponeurosis of the arm. The costal fasciculi are distinctly 
separated from the clavicular and sternal fasciculi. 

The small pectoral, which corresponds to the deep pectoral of animals, is inserted, on 
the one part, into the external face of the third, fourth, and fifth ribs, on the other part 
by a tendon to the anterior border of the coracoid process. 

In Man, there is found a muscle which does not exist in animals; this is the sub- 
clavius, a very slender fasciculus situated beneath the clavicle, and attached to the 
eee a the first rib and the external portion of the lower face of the clavicle (see 

ig. 117, 5). 

The great serratus does not show any distinct aponeurosis on its surface; it arises 
from the eight first ribs, and ils digitations are grouped into three principal fasciculi. 

Lastly, in Man the internal intercostals are prolonged to the vertebral column by 
small muscles, named the subcostals (or tntracostals). ‘ 


INFERIOR ABDOMINAL REGION. 


The lateral and inferior walls of the abdominal cavity are formed by a 
wide musculo-aponeurotic envelope, which rests, by its periphery, on the 
sternum, ribs, lumbar vertebree, ilium, lumbo-iliac aponeurosis, and the 
pubis. This envelope is concave on its superior surface, and results from 
the assemblage of four pairs of large membranous muscles arranged in 


MUSCLES OF THE TRUNE. 239 


superposed layers. Reckoning them from without inwards, these are 
designated the great, or external oblique, the small, or internal oblique, the 
great straight, and the transverse muscle. Covered outwardly by an expan- 
sion of yellow fibrous tissue, the tunica abdominalis, and separated from 
those of the opposite side by the white line (linea alba), a medium raphé ex- 
tending from the sternum to the pubis, these muscles support the intestinal 
mass, and by their relaxation or contraction adapt themselves to the varia-~ 
tions in volume these viscera may experience. 

Preparation.—After placing the animal in the first position, a wide opening is to be 
made in the pectoral cavity by the ablation of a certain number of ribs, which should be 
divided inferiorly, above the costal attachments of the great oblique muscle. The heart 
and lungs are removed; then an incision is made in the diaphragm, to allow the 
digestive viscera contained in the abdominal cavity to be taken away. It is not abso- 
lutely necessary, however, to empty that cavity, and if its contents be allowed to remain, 
several punctures should be made in the large intestine to prevent the accumulation of 
gas, and the too great distention of the abdominal parictes. 

These preliminary precautions having been adopted, then proceed in the following 
manner: 

1. Remove the skin from this region, and with it the panniculus carnosus, in order to 
study the external surface of the abdominal tunic. 2. The dissection of the great 
oblique muscle is accomplished by removing the yellow fibrous envelope from the fleshy 
portion of the muscle, together with the sterno-trochineus, The inguinal ring should 
be exposed by the ablation of the dartos muscle, the sheath and penis, or the mamme. 
8. On the opposite side, the small oblique is uncovered by excising the great oblique, 
leaving, however, that portion of the aponeurosis which is mixed up wit! that of the first 
muscle. 4. The latter having been studied, dissect the great straight muscle of the 
abdomen on the same side, in separating from the white line, by a longitudinal incision, 
the aponeurosis common to the two eblique muscles, dividing this aponeurosis and the 
fleshy portion of the internal oblique by another incision exteuding transversely from the 
umbilicus to the middle of the lumbar region, and laying back one of the musculo- 
aponeurotic sections on the thigh, the other on the ribs. 5. The transverse muscle is 
dissected on the same side as the external oblique has been. To expose it, nothing more 
is necessary than to make two incisions similar to the foregoing, but including the two 
oblique and the straight muscle, throwing back the two portions as above. 6. Lastly, 
open the entire abdominal cavity by cutting through the transverse muscle in the sanie 
way; then study the muscular digitations of that muscle, the internal orifice of the 
inguinal canal, and the leaf reflected from the apuneurosis of the great oblique muscle. 


1. Abdominal Tunic. 


The vast expansion of yellow elastic fibrous tissue spread over the two 
external oblique muscles of the abdomen is so named. 

Very thick towards the prepubic tendon of the abdominal muscles and 
in the vicinity of the linea alba, this expansion gradually thins as it ap- 
proaches the sternum, and disappears near the abdominal insertion of the 
sterno-trochineus muscles. It also diminishes in thickness as it extends 
from the linea alba; and when it reaches the fleshy portion of the great 
oblique muscle it becomes reduced to an extremely thin leaf, whose fasciculi 
separate more and more from one another, until they completely disappear. 
Anteriorly, however, it is seen to be prolonged on each side to the posterior 
digitations of the serratus magnus. Posteriorly, it furnishes some bundles 
of fibres, which are detached from the surface of the common tendon, and - 
are carried between the thighs to be lost on the internal crural muscles. 

The abdominal tunic is covered by the skin and the panniculus 
carnosus, from which it is separated by an abundance of cellular tissue. In 
the male, its external surface gives attachment to the suspensory ligaments 
of the sheath, and to the dartos; and in the female,-to the elastic capsule 
which envelops each mammary gland. By its internal face, it closely 
adheres to the aponeurosis of the great oblique muscle ; though it is easily 


240 THE MUSCLES. 


separated from the fleshy portion. It is traversed by several openings which 
afford passage to the subcutaneous vessels and nerves of the abdominal 
region. : ie 65 . 

The abdominal tunic acts as an immense elastic girth or bandage, which 
aids the muscles in sustaining the weight of the intestines. As the digestive 
organs increase in volume this tunic increases in thickness. 

In the Pig, Dog, and Cat, it is reduced to a simple cellulo-aponeurotic lamina, owing 
to the stomach and intestines in these animals exercising but a small amount of pressure 
on the abdominal parietes. 


Wie Tine.” 


The white line (linea alba) is a fibrous cord comprised between the 
internal border of the two great straight muscles, and is considered as being 
formed by the intercrossing, on the median-line, of the aponeuroses belonging 
to the oblique and transverse muscles. Attached, in front, to the inferior 
surface of the xiphoid appendage, this cord is confounded, behind, with a 
large tendon, the prepubic or common tendon of the abdominal muscles, which 
is fixed to the anterior border of the pubes (Figs. 90, a; 108, c; 116, 4), 
This tendon, covered by the abdominal tunic, contributes to form the 
internal commissure of the inguinal ring, and gives origin to the pubio-femoral 
ligament. 

Towards the union of its posterior third with its two anterior thirds, 
the white line widens, so as to form a lozenge-shaped space, in the centre 
of which is found the remains of the umbilicus and the umbilical cord 
(Fig. 116, 14). 


3. Great Oblique, or External Oblique of the Abdomen. (Figs. 105, 18; 116, 5.) 


Synonyms.—Costo-abdominalis—Girard. (Obliquus externus abdominis—Pereivall,) 


Situation—Composition—This muscle, the largest and the most super- 
ficial of the four, is composed of a fleshy and an aponeurotic portion. 

Form, Structure and Attachments of the fleshy portion—This is composed 
of fibres directed obliquely downwards and backwards, and presents itself as 
a wide muscular band, narrower before than behind, applied to the inferior 
surface of the last thirteen or fourteen ribs. Its superior border is concave, 
and attached: 1, To the external surface of the ribs just mentioned by as 
many slightly aponeurotic digitations, the first four of which cross the denta- 
tions of the great serratus ; 2, To the aponeurosis of the great dorsal muscle, 
from the last rib to the external angle of the ilium (Fig. 105, 18). Its inferior 
border, convex and sinuous, is continuous with the aponeurosis ; it descends, 
in front, to the cartilaginous circle of the false ribs, which it projects beyond 
posteriorly, increasing in this as it nears the lumbar region. 

Form, Structure, and Attachments of the aponeurosis.—This is narrow and 
thin in front, wide and thick behind, of a triangular form, and composed 
of white, nacrous-looking fibres passing in the same direction as the fibres 
of the fleshy portion, with whose inferior border it is continuous by its 
external border. Its internal border is inserted into the white line and the 
prepubic tendon; and its posterior border, extending from the external 
angle of the ilium to the anterior border of the pubis, responds to the 
plicature of the flank, embraces the corresponding crural muscles, and 
establishes the line of demarcation between the trunk and the abdominal 
limb (Fig. 116, 10). . : 

The aponeurosis of the great oblique gives rise, at its posterior border, 
to two very remarkable fibrous leaves which appear to be produced by the 


MUSCLES OF THE TRUNK, 241 


doubling of this aponeurosis into two layers. One of these leaves descends on 
the internal muscles of the thigh to constitute the crural aponeurosis 
(Fig. 116, 11); while the other is reflected upwards and forwards, to enter 
the abdominal cavity ; this reflected leaf of the great oblique aponcurosis is 
named the crural arch (ligament of Poupart or Fallopius). (Fig. 108, .) 

Near. the prepubic tendon of the abdominal muscles, and immediately 
before its division into two leaves, the aponeurosis of the external oblique is 
pierced by a large oval aperture (Fig. 116, 5), the inferior orifice of the 
canal through which passes the cord of the testicle in the male, and the 
mammary vessels in the female. This channel has been named the ingwinal 
canal. 

The description of the femoral aponeurosis, the crural arch, and the 
inguinal ring—a necessary complement of the great oblique muscle—will be 
given hereafter. 

Relations of the Great Oblique Muscle——By its superficial face, the 
external oblique responds to the sterno-trochineus and the abdominal tunic, 
which latter separates it from the skin and the panniculus. By its deep face, 
it is related to the ribs, into which it is inserted, as well as with their carti- 
lages, the corresponding intercostal muscles, the small oblique, and the great 
straight muscle. The latter even appears to be attached, through the 
anterior moiety of its external border, to the fleshy portion of the great 
oblique, by means of a slight lamina of yellow elastic tissue, which covers, 
to a small extent, the deep face of the two muscles. 

Action.—The external oblique, in contracting, compresses the abdominal 
viscera, flexes the vertebral column, and acts as an expiratory muscle. (By 
its compression on the abdominal viscera it concurs in the acts of defecation, 
micturation, and parturition.) 

Inrernat Crurat AponEvrosis.—This fibrous lamina descends from the 
plicature of the flank on the patella and the inner surface of the leg. 
Outwardly, it is confounded with the aponeurosis of the fascia lata; in- 
wardly, it degenerates into cellular tissue. It covers the long adductor of 
- the leg, part of the short adductor, the vastus internus, and the crural vessels 
at their exit from the abdominal cavity. 

Crurat Arco.—As already mentioned, this is the reflected leaf of the 
great oblique aponeurosis, and is also named the ligament of Fallopius and 
Poupari’s ligament. It is a wide, flat band, attached by its extremities to the 
external angle of the ilium and the anterior border of the pubis. Its 
anterior face (Fig. 108, 8) forms, inwardly, the posterior wall of the inguinal 
canal; it gives attachment, outwardly, to the posterior fibres of the small 
oblique muscle. Its posterior face, applied against the superior extremity of 
the patellar muscles, the long adductor of the leg, the pectineus, and the 
crural vessels on their leaving the abdomen, embraces all these parts as in a 
vast arch, and from this peculiarity it derives its name. ts superior border 
is inserted, for its external half, into the lumbo-iliac aponeurosis. In its 
middle part it is much thinner, and is prolonged to the external surface of 
the long adductor muscle of the leg and the iliac fascia, to be at last mixed 
up with the latter. Within the pectineal insertion of the small psoas 
muscle, it forms the anterior margin of the crural ring: a triangular orifice 
circumscribed on the other side by the anterior border of the pubis, the 
iliacus, and the long adductor of the leg, and through which pass the crural 
vessels as they leave the abdomen by the crural arch.! The inferior border 


1 This orifice is covered by a very thin aponeurotic layer, which is prolonged, above, 
on the crural vessels, behind, into the pelvic cavity, and which appears to be continuous, 


ae 
4 


- 


242 THE MUSCLES. 


is continuous with the femoral aponeurosis and that of the great oblique 
muscle. 

IneurnaL Canat.—This is an infundibuliform canal compressed on each 
side, through which the spermatic cord and scrotal artery pass from the 
abdomen in the male, and the external mammary vessels in the female. 

Situated on the side of thé prepubic region, in an oblique direction 
downwards, backwards, and inwards, and measuring from two to two-and- 
a-half inches in length, this canal lies between the crural arch, which con- 
stitutes its posterior wall, and the fleshy portion of the small oblique 
muscle, which forms the anterior wall. 

Its inferior (external) or cutaneous orifice, also named the inguinal ring, 
is much larger than the superior (internal), Pierced in the aponeurosis of 
the great oblique, in the angle formed by the union of the internal border 
with the posterior border of the aponeurosis, this opening is of an oval form, 
directed obliquely backwards and inwards, which permits it to be described 
as having two lips or pillars, and two extremities or commissures. 

The pillars, distinguished into anterior and posterior, are composed of the 
arciform fibres from the aponeurosis of the great oblique muscle. 

The commissures, internal and external, result from the union of the two 
pillars at their extremities. The internal is limited by the prepubic tendon 
of the abdominal muscles. 

The superior (internal) or peritoneal orifice of the inguinal canal is situated 
in front of, and directly opposite to, the crural ring. 1t is a simple dilatable 
slit, comprised, like the canal itself, between the crural arch and the small 
oblique muscle. Not well defined at its extremities, this opening includes 
the neck of the vaginal sheath. 


4. Small or Internal Oblique Muscle of the Abdomen. 
(Figs. 106, 17’; 116, 2.) 


Synonyms.—Ilio-abdominalis—Girard. (Obliquus internus abdominis—Peretvall.) 


Sitwation—Composition.—Situated beneath the preceding, which exactly 
covers it, this muscle is, like it, composed of a fleshy and aponeurotic 
portion. 

Form, Structure, Position, and Attachments of the muscular portion—The 
muscular portion is very thick, triangular, and flabelliform, and occupies the 
region of the flank. Its superior border is united, by a thick, yellow, elastic 
production, to the aponeurosis of the great dorsal (latissimus dorsi), and a 
peculiar small muscle, named by the Germans the retractor costee (retractor of 
the last rib), which we consider as a dependency of the small oblique muscle. 
Its posterior border is slightly raised and lies against the crural arch, from 
which it separates, inwardly, to form the inguinal canal. Its anterior and 
inferior border is convex, irregular, and thinner than the other portions of 
the muscle, and is continuous with the aponeurosis. All the fibres entering 


into the composition of this muscular portion are spread like a fan, and .... 


leave the external angle of the ilium and the external fourth of the crural 
arch to be directed, the posterior fibres backwards and inwards, the middle 
fibres downwards, and the anterior fibres forwards to reach the antero- 
inferior border of the muscle. 


‘ : 
inferiorly, with the upper border of Poupart’s ligament, This lamina is perhaps only a 
dependency of the subperitoneal aponeurosis; and if so, it represents the only vestige 
of the fascia transversalts it has been p ssible to discover in Solipeds. 


MUSCLES OF THE TRUNE. 245 


: Form, Structure, and Attachments of the aponeurosis——The aponeurosis is 
irregularly triangular, and formed of nacrous-looking fibres, which are 


directed like the muscular fibres, and cross 
in X fashion the aponeurotic fibres of 
the external oblique. It succeeds the an- 
tero-inferior border of the muscular por- 
tion, and is separated, superiorly, into 
several digitations which reach the in- 
ternal face of the last asternal cartilages. 
Throughout the whole extent of its in- 
ternal border it is fixed to the white line, 

Relations—This muscle is covered 
by the external oblique. The aponeuroses 
of the two muscles, which are merely 
superposed outwardly, are blended in- 
wardly in so intimate a manner that it 
might be thought their respective fasci- 
culi were woven into each other. The 
small oblique covers the great straight 
and the transverse muscles. 

Action.—This muscle, a congener of 
the preceding, compresses the abdominal 
viscera, depresses the last ribs, and causes 
the flexion, either direct or lateral, of the 
vertebral column. 

The retractor muscle of the last rib— 
This small muscle, flattened on each side, 
and triangular in form, originates by 
aponeurotic fibres from the summits of 
the first two or three transverse processes 
of the lumbar region. It terminates on 
the posterior border of the last rib. 
Covered by the last digitation of the pos- 
terior serratus and by the great oblique, 
it covers in turn the transverse muscle of 
the abdomen. In contracting, it draws 
the last rib backwards, and fixes it in 
that position, in order to permit the ex- 
piratory action of the internal intercostal 
muscles. It therefore plays the same 
part, in regard to these muscles, that the 
scalenus does to the external intercostal 
muscles (Fig. 106, 17). 


5. Great Rectus Muscle of the Abdomen. 
(Figs. 105, 20; 116, 3.) 


Synonyms.—Sterno-pubialis— Girard. (Rec- 
tus abdominis—Percivall.) 


Situation— Extent — Form—Structure. 


Fig. 116, 


WHIZ N 
WH 


MUSCLES OF THE INFERIOR ABDOMINAL 


REGION. 


1, Aponcurosis of the great oblique; 2, 


Muscular portion of the small oblique ; 
3, Rectus abdominis; 3’, Transverse 
muscle; 4, Flat tendon by which the 
four abdominal muscles are inserted 
into the pubis; 5, Inguinal ring; 6, 
Its anterior pillar; 7, Its posterior 
pillar; 8, Its external commissure; 9, 
Internal commissure; 10, Posterior 
border of the great oblique aponeu- 
rosis,; 11, Internal crural aponeurosis ; 
12, Strip of the great oblique aponeu- 
rosis turned downwards to show the 
origin of Poupart’s hgament, 14, 
Traces of the umbilicus. 


—This is a wide and powerful muscular band, extending from the sternum 
to the pubis, included between the aponeurosis of the internal oblique and 
that of the transverse muscle, narrower at its extremities than in its middle 
portion, and divided by numerous transverse and zig-zag fibrous inter- 


244 THE MUSCLES. 


sections. These strongly adhere to the aponeurosis of the small oblique 
muscle, are nearer to each other, and more distinct, in front than behind, 
and are produced by small tendons which are.placed at certain distances on 
the track of the muscular fasciculi, making it somewhat of a polygastric 
muscle. 

Attachments.—In front: 1, To the prolonging cartilages of the last 
four sternal, and the first asternal ribs; 2, ‘Io the inferior face of the 
sternum. Outwardly, by the anterior moiety of its external border, to the 
internal face of the great oblique. 

Behind, to the anterior border of the pubis through the medium of the 
common tendon, which is a direct continuation of the great straight 
muscle. , 

Relations. —By its inferior face, and in front, with the sterno-trochineus 
and great oblique; for the remainder of its extent, with the aponeurosis of 
the small oblique. By its superior face, with the transverse muscle and 
the cartilages of several ribs. By its internal border, with the white line, 
which separates it from the opposite muscle. 

Action.—It draws the thorax backwards, and compresses the abdominal 
viscera, It is also the principal flexor of the spine. (Leyh, remarking that 
it shares in the functions of the preceding muscles, adds that it draws the 
pelvis forwards during copulation.) 


6. Transverse Muscle of the Abdomen. (Figs. 106, 18; 116, 3'.) 


Synonyms. — Lumbo-abdominalis — Girard. (Transversalis abdominis — Pereivall. 
The costo-abdominalis internus of Leyh.) 


Situation—Composition.— This muscle is situated immediately without 
the peritoneum, and forms the deep layer of the abdominal parietes. It is 
muscular outwardly, and aponeurotic for the remainder of its extent. 

Form, Structure, and Attachments of the muscular portion.—It presents a 
band elongated from before to behind, extending from the sternum to the 
transverse processes of the last-lumbar vertebra, following in its course the 
direction of the cartilages of the ribs, and formed of parallel fibres passing 
from one border to the other. 

Its superior border, concave, is attached: 1, To the internal surface of 
the asternal ribs by digitations placed opposite those of the diaphragm, but 
the majority of which do not mix with them; 2, To the extremity of the 
transverse processes of the lumbar region by a thin fibrous lamina. Its 
inferior border is convex and continuous with the aponeurosis. 

Form, Structure, and Attachments of the aponeurosis.—This is triangular- 
shaped, with the base behind, and with its fibres running in a transverse 
direction to the median line. Closely laid one against another in front, 
these fibres separate behind, and form only a very thin and incomplete 
lamina. 

By its external border, the aponeurosis is joined to the inferior margin 
of the muscular portion. Its internal border is fixed to the xiphoid cartilage 
and the white line. Its posterior border, badly defined, appears to join the 
crural arch only on its outcr aspect. 

Relations.—Outwards, with the inferior extremity of the asternal ribs 
and their cartilages, with the rectus abdominalis, the small oblique, and the 
depressor muscle of the last rib ; inwardly, with the peritoneum, from which 
it is separated by the subperitoneal aponeurosis: an extremely fibrous layer 
which, in Man and some animals, becomes much thickened towards the crural 


MUSCLES OF THE TRUNK. 245 


arch, where it forms adhesions. It has been described, in human anatomy, 
as the fascia transversalis. 


Action.—It compresses the abdominal viscera when it contracts, and 
presses them against the vertebral column. 


DIFFERENTIAL CHARACTERS . Fig. 117. 
OF THE MUSCLES OF THE 
ABDOMINAL REGION IN 
OTHER THAN SOLIPED 
ANIMALS, 


As has been already 
said, the development of the 
abdominal tunic is in pro- 
portion to the volume of 
the digestive viscera. This 
membrane is, therefore, 
very wide and thick in 
Ruminants, while it is re- 
duced to an insignificant 
leaf in the Pig and Car- 
nivora, In these animals 
the internal crural aponeu- 
rosis does not exist, and 
is replaced by a cellular 
layer. The aponeurosis of 
the great oblique, instead of 
being doubled into two 
lamine at its posterior 
border, is entirely reflected 
to form the crural. arch. 
In the latter animals, the 
great oblique is also dis- 
tinguished by the extensive 
development of its mus- 
cular part, and the narrow- 
ness of its aponeurosis. 

The muscular portion 
of the small oblique of Ru- 
minants occupies the entire 
space comprised between 
the posterior border of the 
last rib, the extremity of MUSCLES OF THE ANTERIOR ASPECT OF THE BODY OF MAN; 
the transverse processes of ON THE LEFT SIDE THE SUPERFICIAL LAYER IS SEEN, ON 
the lumbar vertebre, and THE RIGHT THE DEEPER LAYER. 
the external angle of the 1, Pectoralis major; 2, Deltoid; 3, Anterior border of the 
ilium. Thesmall retractor  Jatissimus dorsi; 4, Serratus magnus; 5, Subclavius, right 
of the Jast rib is not distinct side; 6, Pectoralis minor; 7, Coraco-brachialis; 8, Biceps, 
from the principal muscle. with its two heads; 9, Coracoid process of the scapula; 10, 
This arrangement is like- Serratus magnus, right side; 11, External intercostal muscle 
wise present in the smaller of the fifth intercostal space; 12, External oblique; 13, Its 
domesticated animals. It  aponeurosis with the linea alba; 14, Poupart’s ligament; 
is also to be remarked that, 15, External abdominal ring; “16, Rectus muscle of right 
inRuminants, thetendinous side;_ 17, Pyramidalis muscle; 18, Internal oblique; 19, 
intersections of the great Conjoined tendon of internal oblique muscle and Pouparit’s 
rectus muscle of the abdomen _ ligament. 
are more marked at its : ‘ ‘ 
superior than its inferior face; and that the aponeurosis of the transverse is much thicker 
and more resisting than in Solipeds. 


COMPARISON OF THE ABDOMINAL MUSCLES OF MAN WITH THOSE OF ANIMALS. 


With the exception of some slight differences, fhe abdominal muscles of Man present 
isposition as those of the smaller animals, ; 
ee fama is not present, but is replaced by a cellular layer which 


19 


. 


246 THE MUSCLES. 


separates the skin from the aponeurosis of the great oblique. The muscular portion of 


this muscle has no attachment to the aponeurosis of the great dorsal. 
The aponeurosis of the smail oblique is divided into two lamelle at the external 


border of the great straight muscle; the anterior is consolidated with the great oblique, 
and passes in front of the great straight; the posterior is united to the transverse, and 


passes behind that muscle. aa : : ; 
The aponeurosis of the transverse is divided into two leaves, only one of which remains 


behind the great straight muscle; this is named the semilunar fold of Douglas. _ : 

The great rectus muscle of the abdomen offers three transverse fibrous intersections in 
its length (line transverse). At its upper extremity, it divides into three branches; 
the internal is attached to the xiphoid appendage and the cartilage of the seventh rib; 
the middle, to that of the sixth rib; the external, to the cartilage of the fifth rib. 

“To the great rectus is annexed a small triangular muscle, the pyramidal, which ig 
not found in animals. This muscle is about 2) inches long ; is sometimes absent; most 
developed in children ; is attached by its base to the pubis, between the spine and the 
symphysis; and by its summit is continuous with a tendon which is lost in the white 
line, and constitutes, with that of the opposite side, a fibrous cord which may be followed 
to the umbilicus.”—Beaunis and Bouchard. 

Lastly, at the inner aspect of all the abdominal muscles, beneath the peritoneum, is 
a fibrous lamella—the fascia transversalis, This fascia is not distinctly limited upwards 
or outwards; below, it is fixed to the crural arch, in the vicinity of the inguinal canal, 
and sends a layer to the surface of the cord spermatic. 


DIAPHRAGMATIC REGION. 


This is composed of a single muscle, the diaphragm. 


Diaphragm. 


Preparation.—Place the subject in the first position; open the abdomen and remove 
the viscera it contains, as well as the large vascular trunks lying upon the sublumbar 
region ; detach the peritoneum from the fleshy portion of the muscle, in order to show 
the digitations of the latter more distinctly, taking care not te allow the air to enter the 
thoracic cavity, as it would destroy the tense and concave form of the diaphragm. 


Situation—Direction.—The diaphragm is a vast musculo-aponeurotic 
partition separating the thoracic from the abdominal cavity, between which 
it is placed in an oblique direction downwards and forwards. 

Form.—tIt is flattened before and bebind, elliptical, wider above than 
below, concave posteriorly, and convex anteriorly. 

Structure—This muscle comprises: 1, A central aponeurotic portion 
designated the phrenic centre, which is incompletely divided into two folioles 
(leaflets) by the pillars—fleshy columns which descend from the sublumbar 
region; 2, A peripheral (or circumferential) portion forming a wide 
muscular band around the phrenic centre. 

The phrenic centre (also named the speculum Helmontii or mirror of 
Helmont) is composed of white, glistening, radiating fibres which, originating 
from the pillars, extend in every direction to join the muscular fibres of the 
peripheral portion. It is pierced, in its right leaflet, by a large opening for 
the posterior vena cava. 

The pillars are two in number, a right and left. The right pillar, the 
most considerable, is a very thick, fleshy fasciculus which commences under 
the loins by a strong tendon, united to the inferior common vertebral liga- 
ment. It descends to the phrenic centre, to which it gives a heart-shaped 
appearance. Near its inferior extremity, it presents an opening for the pas- 
sage of the cesophagus into the abdominal cavity —The left pillar is a small 
triangular fasciculus, partly separated from the preceding by an orifice for 
the transmission of the posterior aorta and the thoracic duct. It also arises 


MUSCLES OF THE TRUNK. 247 


pee suitaias region by a tendon, which is confounded with that of its 
The peripheral muscular portion is continuous, by its concentric border, 


Fig. 118, 


DIAPHRAGM OF THE HORSE; POSTERIOR FACE. 

1, 1’, The two portions of the right pillar; 2, Left pillar; 3, Tendons of the pillars, 
4, 4', Peripheral muscular portion; 5, Left leaflet of the aponeurotic portion ; 
5, 5', Right leaflet of the same; 6, Posterior vena cava; 7, Esophagus pas$ng 
through the opening in the right pillar; 8, Posterior aorta between the two 
pillars; 9, Cartilaginous circle of the ribs; 10, 11, Section of the psoas muscle ; 
12, Section of a lumbar vertebra; 13, Section of the common mass 714, Retractor 
muscle of the last rib; 15, Xiphoid appendage of the sternum. 


with the central aponeurosis. Its excentric border is divided into dentations. 
Above, and on the left side, it nearly always joins the left pillar; but on 
the right side it stops at a certain distance from the corresponding pillar, 


248 THE MUSCLES. 


so that towards this point the phrenic centre is not enveloped by the 
peripheral portion, and is in contact with the sublumbar region. 

Attachments.—1, To the bodies of the lumbar vertebre by the tendons 
of its two pillars, which tendons are confounded with the inferior common 
vertebral ligament; 2, By the external contour of its muscular portion, to 
the superior face of the xiphoid appendage and the inner face of the last 
twelve ribs, near their inferior extremities or cartilages. The digitations 
forming the last insertions do not intercross, in Solipeds, with those of the 
transverse muscle of the abdomen, being separated by an interval which is 
wider behind than before. 

Relations —The anterior face of the diaphragm is covered by the pleura, 
and responds, mediately, to the base of the lung. The posterior aspect, 
covered by the peritoneum, is in contact with the greater part of the viscera 
contained in the abdominal cavity—the stomach, colon, spleen, and liver; the 
latter is even attached to this surface for a portion of its extent. 

On each side of the pillars, the circumference of the muscle forms an 
arch which passes over the great and small psoas muscles. 

Action —The diaphragm, in contracting, tends to become an inclined 
plane; its central portion is carried backwards, and the antero-posterior 
diameter of the chest is increased. It is, therefore, essentially an inspiratory 
muscle. It may also raise the ribs by making the mass of abdominal viscera 
its fixed point; it then actsasa reflected muscle, to which these viscera serve 
asa pulley. (The diaphragm also aids the other abdominal muscles in 
expulsive efforts and, when affected with irregular spasmodic contractions, 
produces the peculiar phenomenon in Man and some of the lower animals, 
known as hiccough.) 


DIFFERENTIAL CHARACTERS OF THE DIAPHRAGM IN OTHFR THAN SOLIPED ANIMALS. 


In the Ox, the pillars of the diaphragm are very long and voluminous. “The 
attachments of the muscular portion are much farther distant from the cartilagiaous 
circle than in the Horse, particularly at the superior part; this disposition explains the 
innocuousness of puncture of the paunch in the middle of the last intercostal space; 
for with the Horse, when the instrument is passed through this part, it penetrates the 
thorax.— Cummunicated to M. Lecog by M. Tabourin. 

In the Sheep we have not remarked that the costal attachments were more forward 
than in the Horse. 

Rigot erroneously states that, in the Pig and Dog, the oesophagus passes between the 
two pillars of the diaphragm ; on several occasions we have convinced ourselves that this 
conduit traverses the right pillar, as in the other animals. 


COMPARISON OF THE DIAPHRAGM OF MAN WITH THAT OF ANIMALS. 


In the human diaphragm, the aponeurotic portion is divided into three leaflets, which 
has caused it to be termed the aponeurotic trefoil. Between the middle and right 
leaflet is the orifice through which the inferior vena cava passes. The openings for the 
passage of the cesophagus and the aorta are situated between the two pillars. ‘There are 
frequently met with in Man one or two small accessory pillars, separated from the large 
pillars by an aperture that affords a passage, on the right side, to the vena azygos and the 
sympathetic nerve, and on the left side, to one of the lumbar veins and the other 
sympathetic nerve. 

The peripheric muscular portion always joins, posteriorly, the central muscular portion. 


Article IJ.—Mouscizs or tae Anterior Lips. 


These are divided into four principal groups: the muscles of the 
shoulder, arm, fore-arm, and foot. 


MUSCLES OF THE ANTERIOR LIMBS. 249 


MUSULES OF THE SHOULDER. 


These muscles are grouped around the scapula, and all act upon the arm, 
which they extend, flex, abduct, adduct, etc. They form two regions: an 
external or suprascapular, and an internal or subscapular, 


A. External Scapular Region. 


This comprises four muscles: the long abductor of the arm, the short 
abductor, the super- (or supra-) spinatus, and sub- (or infra-) spinatus. These 
muscles are applied to the external surface of the scapula, and are covered 
by an.aponeurotic lamella. 


Preparation of the external ae region.—Separate the limb from the trunk; 
remove the trapezius and mastoido-humeralis, to expose the external surface of the 
aponeurosis; take away, also, the small pectoral muscle, after studying its mode of 
insertion into this fascia. 

This being accomplished, next remove the latter muscle to show the supraspinatus, 
the subspinatus, and long abductor muscle of the arm; leaving only the strip which 
attaches the anterior portion of the latter to the tuberosity of the scapular spine. 

To study the short abductor muscle, it is only necessary to cut the long abductor and 
superspinatus across, and to throw back the sections: an operation requiring some care, 
because of the intimate adherence of the short abductor to the infraspinatus, 


1. External Scapular Aponeurosis, 


This aponeurosis, to which the sterno-prescapularis and long adductor of 
the arm act as tensors, gives origin, by its internal face, to several septa 
which penetrate between the scapular muscles, and form around them more 
or less complete contentive sheaths. Its external face is separated from the 
skin by the panniculus carnosus, trapezius, mastoido-humeralis, and the 
aponeurotic fascia which unites the last two muscles. It is continuous, in 
front, with the thin fibrous expansion extended over the internal scapular 
muscles ; behind and downwards, it is prolonged over the muscles of the arm 
and insensibly degenerates into conjunctival tissue; above, it is attached 
to the fibro-cartilaginous prolongation of the scapula. 


2. Long Abductor of the Arm, ov Scapular Portion of the Deltoid. 
(Fig. 119, 1, 1.) 


Synonyms.—Scapulo-humeralis magnus—Girard. (Teres major—Percivall. Great 
scapulo-trochiterius—Leyh.) 


Situation—Composition—Form—Direction—This muscle is situated 
beneath the scapular aponeurosis, behind the subspinatus, and is composed 
of two portions placed one above the other, separated by a superficial inter- 
space. The posterior portion, the most considerable, is elongated from 
above to below, bulging in its middle, narrow at its extremities, plane on its 
external, and convex on its internal surface. It accompanies the posterior | 
border of the subspinatus, and is lodged in a depression in the thick 
extensor muscle of the fore-arm. 

The anterior portion, much shorter than the preceding, extends over the 
subspinatus and short abductor, by slightly crossing the direction of these 
two muscles. Thick inferiorly, this portion diminishes considerably towards 
its superior extremity. 


250 THE MUSCLES. 


Fig. 119. Structure and Attachments.—The first 
portion is generally paler than the second, 
and is composed of longitudinal fleshy fibres 
deeply intersected by tendinous strips. It 
takes its origin, by its superior extremity, 
from the dorsal angle of the scapula. The 
wnterior portion is deeper-coloured and more 
tendinous than the other. Its superior ex~ 
tremity, included within two fibrous folds 
resulting from the duplicature of the scapular 
aponeurosis, is fixed, through the medium of 
these, to the tuberosity of the scapular spine. 

These two muscular bodies unite in- 
feriorly, and terminate together on the del- 
toid imprint or subtrochiterian crest by 
tendinous and muscular fasciculi. 

Relations —This muscle responds: out- 
wardly, to the scapular aponeurosis, with 
which it may be said to form one body; 
inwardly, to the subspinatus, the short ab- 
ductor of the arm, and the large and short 
extensors of the fore-arm. 

Action.—It gives a very marked abduc- 
tion movement to the humerus, and also 
makes it pivot outwards. It acts, besides, 
as a flexor of that bone, when its action is 
combined with that of the adductor of the 
arm. It should also be considered as a 
‘powerful tensor of the scapular aponeurosis. 


3. Short Abductor of the Arm, or Teres 
“Minor. (Fig. 85, 2, 3.) 


Synonyms.—Scapulo-humeralis minor—Girard. 
(Teres minor — Percivall. Scapulo-trochiterius, 
medium and parvum —Leyh.) 


Volume—Situation—Direction—A small 
elongated muscle, situated below the pre- 
ceding and the subspinatus, along the pos- 
terior border of the scapula, whese direction 
it follows. 

Form—Structure.—In its inferior half it 


1, 1, Long abductor of the arm; 1’, Its humeral 
insertion; 2, Superspinatus; 3, Subspinatus ; 
3’, Its tendon of insertion; 4, Short abductor 
EXTERNAL MUSCLES OF THE of the arm; 5, Biceps; 6, Anterior brachialis ; 

RIGHT ANTERIOR LIMB. 7, Large extensor of the fore-arm; 8, Short 

extensor of the fore-arm; 9, Anconeus; 11, Anterior extensor of the metacarpus; 11’, 

Its tendon; 12, Aponeurosis separating that muscle from the anterior brachialis ; 13, 

Oblique extensor of the metacarpus; 14, Anterior extensor of the phalanges; 14’, Its 

principal tendon; 15, The small tendinous branch it furnishes to the lateral extensor 5 

16, Lateral extensor of the phalanges; 16’, Its tendon; 17, The fibrous band it 

receives from the carpus; 18, External flexor of the metacarpus; 19, Its metacarpal 

tendon; 20, Its supracarpal tendon ; 21, Ulnar portion of the perforans; 22, Tendon 
of the perforans; 23, Its carpa lligament; 24, Its reinforcing phalangeal sheath; 

25, Tendon of the perforatus. 


MUSCLES OF THE ANTERIOR LIMBS. 251 


is prismatic, muscular, divided by fibrous intersections, and easily separated 
into several irregular fasciculi. In its superior half it is flattened, entirely 
tendinous, and split into several digitations, the longest of which are behind. 

Attachments.—It originates 1, Through the medium of its tendinous 
digitations, from the posterior border of the scapula and the linear imprints 
in the posterior spinous fossa; 2, From the small tubercle situated on the 
external side of the margin of the glenoid cavity, by a short tendon. It 
terminates on the humerus, between the crest of the external tubercle and 
the deltoid imprint. 

Relations.—Outwardly, with the subspinatus and the long abductor ; 
inwardly, with the large extensor of the fore-arm,’the short extensor, and the 
capsule of the scapulo-humeral articulation. 

Action.—Like the preceding, this muscle is an abductor and outward 
rotator of the humerus. 


4, Superspinatus. (Figs. 119, 2; 121, 5.) 


Synonyms.—Superacroiio-trochiterius—Girard. (Antea spinatus—Percivall. An- 
terior sponatus—Leyh.) 


Form—Situation—This muscle is thick and prismatic, stronger below 
than above, representing a very elongated pyramid, and completely filling, 
and even projecting beyond, the super-scapular fossa. 

Structure—Attachments.—It is almost entirely formed of fleshy fibres, 
which are attached, by their superior extremities, to the cartilage of prolong- 
ment of the scapula, the inner face of the scapular aponeurosis, the super- 
scapular fossa, and the anterior border and cervical angle of the scapula— 
fixed insertion. These fibres, on reaching the inferior extremity of the 
muscle, form two very thick, short, and slightly tendinous branches, united 
to each other by the enveloping coracoradial or biceps aponeurosis. The 
external branch reaches the summit of the external tubercle : the internal is 
inserted into the corresponding part of the internal tuberosity—movable 
insertion. 

Relations.—Outwards, with the scapular aponeurosis, to which its fibres 
adhere in the mest intimate manner, inwards, with the scapula and the sub- 
scapularis muscle ; forwards, with the small pectoral ; and behind, with the 
acromioa spine and the subspinatus. The two terminal branches cover and 
embrace the coraco-radialis tendon, and the capsule of the scapulo-humeral 
articulation. 

Action.—This muscle is an extensor of the humerus, and a tensor of the 
enveloping coraco-radial aponeurosis. With regard to the articulation of the 
shoulder, it plays the part of a powerful ligament: a function it shares with 
the majority of the other scapular muscles. 


5. Subspinatus. (Fig. 119, 3, 3’.) 

Synonyms, —Sub-acromio-trochiterius—Girard. (Postea spinatus—Percivall. Pos- 
terior spinatus—Leyh.) 

Situation—Form.—Situated, as its name indicates, in the subspinatus 
fossa, this muscle is wide, thin, and flattened on both sides at its superior 
extremity, thick and prismatic in its middle, and conoid at its inferior 
extremity, which is terminated by two short branches—an external and 
internal. 


252 THE MUSCLES, 


Structure-—The muscular fibres entering into its composition are directed, 
like the muscle itself, forward and downward; they are deeply mixed with 
strong aponeurotic lamelle. Of the two branches which terminate it 
inferiorly the external is the strongest, and is entirely constituted by a 
powerful tendon; the internal is both muscular and aponeurotic. : 

Attachments.—All the fleshy fasciculi of this muscle are fixed, either 
directly, or through the medium of the internal aponeurotic lamelle: 1, To 
the whole extent of the subspinatus fossa ; 2, To the acromion spine and its 
tuberosity ; 3, To the cartilage of prolongment of the scapula; 4, To the 
internal face of the scapular aponeurosis—fixed gnsertion. The movable 
insertion of the muscle takes place, on the external tuberosity, by its two 
terminal branches, the internal passing within the convexity : and the strong 
tendon constituting the external branch (Fig. 119, 3') gliding, by means of 
a synovial bursa, over the surface of this convexity, and attaching itself to 
the roughened facet which forms the crest of the external tubercle. 

Relations —This muscle is covered by the anterior portion of the long 
abductor of the arm, and by the scapular aponeurosis. It covers the scapula, 
its cartilage, the fixed insertion of the large extensor of the fore-arm, and the 
short abductor, which adheres to it in the most intimate manner at its 
superior or aponeurotic portion. Its anterior border responds to the 
acromion spine and superspinatus; the posterior is« bordered by the long 
abductor of the arm. Its inferior extremity protects, outwardly, the capsule 
of the scapulo-humeral articulation, and is concealed beneath the mastoido- 
humeralis. 

Action.-—The subspinatus acts on the humerus as an abductor and out- 
ward rotator. 


B. Internal Scapular Region. 


This is composed of four muséles: three principal, the subscapularis, 
adductor of the arm or teres major, and the coraco-brachialis, are situated at 
the internal face of the scapula, and are covered by a very small fibrous 
fascia which is formed of some scattered parallel fibres that run in a trans- 
verse direction. The last, named the small scapulo-humeralis, is a very 
slender fasciculus deeply lodged behind the articulation of the shoulder. 


Preparation.—Turn over the limb which has served for the dissection of tle preceding 
region, and take away the slight internal scapular fascia. Be careful to preserve the ter- 
mination of the great dorsal muscle, in order that its relations and adhesions with the 
adductor of the arm may be studied; leave also the humeral insertion of the sterno- 
trochineus, so that its union with the tendon of the coraco humeralis may be noted; in 
a word, prepare the region as it is represented in figure 121. With regard to the small 
scapulo-humeral muscle, which is not shown in this preparation, it ought to be dissected 
ut the same time as the short flexor of the fore-arm. 


Subscapularis. (Fig. 121, 3). 


Synonym—Subscapulo-trochineus— Girard. 


Sttuation—Direction—Form.—This muscle, lodged in the subscapular 
fossa whose name it bears, affects the same oblique direction as the scapula. 
It is wider above than below, and divides superiorly into three portions ; 
so that its form exactly repeats that of the excavated surface it covers. 

Structure—The muscular fibres of the subscapularis slightly converge 
towards its inferior extremity, and all end in a very strong, wide, and short 
tendon, They are intermixed with deep and superficial.tendinous fibres, 


MUSCLES OF THE ANTERIOR LIMBS. 253 


which singularly augment the tenacity of the muscle; the superficial fibres 
are spread over the internal surface in glistening, nacrous layers. 

Attachments.—The subscapularis takes its origin from the whole extent 
of the fossa whose name it bears. Its movable insertion takes place on the 
internal tubercle, by means of a voluminous tendon it offers at its inferior 
extremity. A particular small synovial’ bursa facilitates the gliding of this 
tendon over the.eminence into which it is inserted. 

Relations.—The external face of the muscle is in contact with the scapula. 
Tis internal face is applied against the great serratus, from which it is 
separated by a thick layer of cellular tissue, as well as by the rudimentary 
fascia covering the three muscles of the internal scapular region in common. 
Its anterior border, margined by the superspinatus, adheres closely to that 
muscle in its upper two-thirds, and forms with it, by its inferior third, the 
intermuscular space that lodges the subscapular vessels and nerves. Its 
posterior border responds to the adductor of the arm, with which it also 
unites for the greater part of its extent; it is isolated from this muscle, in 
its inferior third, by the interspace lodging the subscapular vessels and 
nerves. Its terminal tendon covers the capsule of the scapulo-humeral 
articulation, which it powerfully binds; it is in part covered, by the tendon 
of origin of the coraco-humeralis muscle, which glides over it» surface as on 
a pulley, by means of a synovial bursa. 

Action.—This muscle is pyincipally, and perhaps exclusively, an adductor 
of the arm. It may be admitted, however, that it rotates the humerus 
inwards. 


Adductor of the Arm, or Teres Major. (Fig. 121, 4.) 


Synonyms.—Subscapulo-humeralis— Girard. @eres major—Percivall. Great 


scapulo-humeralis—Leyh.). , 


Form—Situation—Direction—A long muscle, flattened on both sides, 
bulging in its middle, contracted at its extremities, thick at its anterior, and 
thin at its posterior border. It is situated behind the preceding, in the 
same oblique direction, and is parallel with the posterior. portion of the 
long abductor, which it appears to repeat in the internal scapular region. 

Structure.—It is almost entirely muscular, showing only some tendinous 
fibres at its external surface and upper extremity. Its inferior extremity is 
terminated by a flat tendon, which also belongs to the great dorsal, and 
which has been already described (see page 203). ‘ 

Attachments.—It arises from the dorsal angle of the scapula, and the 
posterior border of the ‘subscapular muscle—origin ; it passes to the circular 
imprint on the body of the humerus, to be attached by its inferior tendon—. 
termination. 

Relations.—Outwards, with the aponeurosis of the great dorsal and that 
of the long extensor of the fore-arm, which isolates it from the large 
extensor muscle ; inwards, with the great serratus, from which it is separated 
by the fibrous and cellular layers mentioned in the description of the sub- 
scapularis. Itsinferior extremity covers the short flexor and middle extensor 
of the fore-arm ; it is covered by the long branch of the coraco-humeralis, 
and by the vascular and nervous trunks which send their ramifications to 
the arm, fore-arm, and foot. 

Action.—This muscle adducts the arm, and causes it to rotate inwards. 
Tf it contracts at the same time as the long abductor, it directly flexes the 
humerus. .) 


254 THE MUSCLES. 


3. Coraco-humeralis, Coraco-brachialis, or Omo-brachialis. (Fig. 121, 19.) 
(Synonyms.—Coraco-humeralis—Percivall. Middle scapulo-humeralis—Leyh., 


Volume—Situation—Direction—A small elongated muscle, which ap- 
pears to belong to the arm rather than the shoulder, as it is situated at the 
internal face of the humerus, whose direction it slightly crosses. If it is 
described as in the subscapular region, it is because of its attachments and 
action, which are, in every respect, analogous to those of the other muscles 
of the shoulder. 

Attachments—Form—Structure.—It commences on the beak of the 
coracoid process by a small flat tendon, which is at first included between the 
supraspinatus and subscapularis, but afterwards leaves the Anterstice formed 
by these two muscles, to glide and be inflected over the terminal tendon of the 
latter. This small tendon is succeeded by two muscular branches, one deep, 
the other superficial. The first is a wide, thin, and short band, almost 
entirely muscular, attached to the body of the humerus above the internal 
tuberosity. The second forms a fleshy body of a certain thickness, flattened 
on both sides, and strongly aponeurotic; the fasciculi composing it are 
longer as they are more posterior, and are inserted, by their inferior extre- 
mities, into the imprints on the anterior face of the humerus. 

Relations—This muscle is covered by the coraco-radialis, and by the 
sterno-trochineus, which is partly attached to its tendon. It covers the 
internal insertion of the subscapularis, the humerus, the common tendon of 
the great dorsal, and the adductor of the arm, and a small portion of the 
short flexor and middle extensor of the fore-arm. Its posterior border is 
margined by the vascular and nervous trunks on the inner aspect of the arm. 
The anterior humeral nerve passes between its two branches, along with an 
arterial and venous ramification. 

Action.—It is an adductor of the arm, and makes it also pivot inwards. 
Its direction and the disposition of its attachments do not permit it to 
produce rotation outwards, though it has been stated to do so by several 
authors, 


4, Small Scapulo-humeralis. 


(Synonyms.—Not mentioned by Percivall. Leyh, in addition to the above designation, 
names it the tensor of the capsular ligament.) 


The scapulo-humeralis gracilis is a very small cylindrical fasciculus, 
comprised between the large extensor of the fore-arm and the capsule of the 
scapulo-humeral articulation ; deriving its origin above the margin of the 
glenoid cavity of the scapula, and terminating below the head of the humerus 
by a thin tendon, which insinuates itself between the fibres of the short 
flexor of the fore-arm. This muscle appears to be peculiar to Solipeds, and 
has been regarded by Rigot as intended to raise the capsule of the scapulo- 
humeral articulation during flexion, so as to prevent its being pinched 
between the articular surfaces. 


DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE SHOULDER IN OTHER THAN SOLIPED 
ANIMALS, 


The Carnivora are the only animals which offer somewhat notable differences in 
the muscles of the shoulder. ; 

Thus, the long abductor of the arm, very developed, has an anterior portion arising 
directly from the acromion, and a posterior portion which springs from the whole extent 


MUSCLES OF THE ANTERIOR LIMBS. 255 


of the scapular spine, by a short aponeurosis. The swperspinatus is considerable, and 
terminates in a single branch that goes to the great trochanter. 

The subspinatus is not so large as the preceding, and is also undivided at its inferior 
extremity: it is the inferior branch which is absent. 

The coraco-brachialis is very short, and composed of a single fasciculus, which 
terminates above the humeral insertion of the adductor of the arm. 

In the Pég, the disposition of this muscle is the same; it is, besides, very tendinous. 


COMPARISON OF THE MUSCLES OF THE SHOULDER OF MAN WITH THOSE OF ANIMALS. 


As muscles of the shoulder, there are only described the deltoid, subspinatus, teres 
minor and major, and the subscapularis; the coraco-brachialis being included in the 
region of the arm, and the small scapulo-humeralis is absent (see Fig. 120). 

The deltoid, represented in part by the long abductor 
of the arm of Solipeds, is a large, triangular, flat muscle, Fig. 120. 
that covers the articulation of the shoulder. Its fibres are 
inserted into the external third of the anterior border } 
of the clavicle, the external border of the acromion, and 
the inferior hordegot the scapular spine for the whole of f WZ \ 

is attached, through the medium of a fy)" " = 
tendon, to the deltoid imprint. | 


its width; below, 1 

By their disposition, the superspinatus, subspinatus, 
and subscapularis resemble the muscles of Carnivora. 
The teres major, after establishing relations with the great 
dorsal, as in Solipeds, is fixed into the inner lip of the 
bicipital groove. 


MUSCLES OF THE ARM. 


These muscles, grouped around the humerus, 
are attached to the fore-arm by their inferior ex- 
tremities. Those situated in front flex this por- 
tion of the limb, while those behind extend it. 
The first form the anterior brachial region, the 
second the posterior brachial region. 


A. Anterior Brachial Region. 


This region is composed of only two muscles, 
the long and short flexors of the fore-arm. 


1. Long Flexor of the Fore-arm or Brachial 


: : MUSCLES OF ANTERIOR ASPECT 
Biceps. (Figs. 85, 119, 121.) earls ESE 


: Synonyms.—Coraco-cubitalis, or coraco-radialis, accord- 1, Coracoid process of scapula; 
ing to Girard. (Fleaor brachti—Percivall. Scapulo- or 2, Coraco-clavicular liga- 
coraco-radialis—Leyh.) ues ment (trapezoid) passing up- 
Prey.uration.—Place the limb on its internal face, throw ward to clavicle; 3, Coraco 
back the brachial insertion of the mastoido-humeralis,  2cromial ligament, passing 
sterno-humeralis, and sterno-aponeuroticus, over the ex-  #° acromion; 4, Subscapu- 
ternal muscles of the fore-arm; excise, lengthways, the aris; 5, Teres major; 6, 
inferior extremity of the. superspinatus, to show the Coraco-brachialis; 7, Bi- 
originating tendon of the muscle. The inferior insertion  C€PS3 8, Upper end of ra- 
may be studied with that of the short flexor muscle. dius; 9, Brachialis anticus ; 
‘ . “ i. 10, Internal head of triceps. 
Form — Situation — Direction — Structure—A 
long, cylindrical muscle, thick in its middle portion, bifid inferiorly, situated 
in front of the humerus, in an oblique direction downwards and backwards, 
tendinous at its two extremities, divided by a great number of strong fibrous 
intersections, one of which, nearly central and much more considerable than 
the others, is a very resisting cord that traverses the muscle throughout its 
length, and becomes continuous with the tendons at its extremities. 
‘Atiachments.—This muscle has its origin at the base of the coracoid 


256 THE MUSCLES. 


process by a superior, round, and thick tendon (Fig. 85, 6) that reaches the 
bicipital groove, on which it is moulded in becoming fibro-cartilaginous, and 
over which it glides by means of a synovial sac, to be inflected backwards 
and confounded with the body of the muscle. Its inferior tendon, extremely 
short and strong, terminates on the superior and internal tuberosity of the 
radius—the bicipital tuberosity—in uniting itself to the capsular ligament of 
the elbow joint, and insinuating itself beneath the internal ligament of this 
articulation.” At its origin, this tendon gives off a somewhat resisting 
fibrous band, which is spread over the surface of the anterior extensor of 
the metacarpus, and is confounded with the antibrachial aponeurosis. 

Relations.—The coraco-radialis covers an adipose cushion which sepa- 
rates it from the capsule of the scapulo-humeral articulation, the anterior 
face of the humerus, the coraco-humeralis, and the articulation of the elbow. 
It is covered : 1, By the superspinatus, between the two branches of which 
it passes; 2, By a special aponeurotic sheath, whose tensor is the above- 
named muscle, with the sterno-trochineus (see Fig. 114, 12, in which this 
aponeurosis has been partly preserved). This sheath separates the coraco- 
radialis from the mastoido-humeralis, the sterno-aponeuroticus, and from its 
congener, the short flexor. 

Action.—This muscle is a flexor of the fore-arm, and a tensor of the 
antibrachial aponeurosis. It acts, besides, through the cord which traverses 
its entire length, as an inextensible band that mechanically opposes the 
flexion of the scapulo-humeral angle while the animal is standing, and when 
the fore-arm is maintained fixed by the contraction of the humero-olecranian 
muscles. : 

2. Short Flexor of the Fore-arm. (Fig. 85, 12.) 

Synonyms.—Humero-cubitalis obliquus, or humero-radialis—Girard, (Humeralis 
externus—Percivall. Humero-radialis—Leyh.) 


Preparation—Lay the limb on its internal face, and remove the abductors of the 
arm, the subspinatus, and the large and short extensors of the fore-arm, in order to 
expose the middle and upper extremity of this muscle. Then turn the limb on its 
external fuce to dissect the inferior extremity. To study it in all its details, it is a good 
plan to cut through the interna] ligament of the ulnar articulation, and those muscles of 
the fore-arm which are attached to the epicondyle. 


Form—Structure—Situation—Direction.—This is a very thick muscle, 
almost entirely fleshy, voluminous in its superior part, and constricted 
inferiorly. It is lodged in the twisted furrow of the humerus, the direction 
of which it exactly follows as it turns round the bone to cover, successively, 
its posterior face, external face, anterior face, and the capsule belonging to 
the elbow articulation, until it finally reaches the inner side of the radius.* 

Attachments.—The muscular fibres entering into its composition have 
their fixed insertion on the posterior face of the humerus, below the articular 
head. They terminate, inferiorly, on a flat tendon, which they almost 
entirely cover. This tendon glides in a transverse groove situated on the 
inner face of the radius, below the bicipital tuberosity, and afterwards 
passing under the internal ligament of the elbow joint, it divides into two 
very short fasciculi; one of these goes to the radius, and the other to the 
ulna, where it is mixed up with the bundles of arciform fibres, which unite, 
on the inner side, the two bones of the fore-arm. 

Relations— We already know the parts this muscle covers. Itis covered, 

_ inwardly, bythe adductor of the arm and the middle extensor of the fore- 
arm; posteriorly and externally, by the large and short extensors of that 
ray. - Jis inferior extremity, comprised between the anterior extensor of the 


MUSCLES OF THE ANTERIOR LIMBS. 257 
metacarpus and the coraco-radialis, passes below the antibrachial band of the 
latter, as under a fibrous bridge. 

Action.—It is simply a flexor of the fore-arm. 


- 


Fig, 121. 


INTERNAL ASPECT OF LEFT ANTERIOR LIMB. 


1, Prolonging cartilage of scapula; %, Inner surface of scapula; 3, Subscapularis; 
4, Adductor of the arm, or teres major; 5, Supra- or antea-spinatus; 6, Long 
extensor of the fore-arm, or portion of the caput magnum; 7, Large extensor 
of the fore-arm, the other portion of the caput magnum; 8, Middle extensor, or 
caput medium; 9, Humeralis externus, or short flexor of the fore-arm; 10, 
Coraco-humeralis; 11, Upper extremity of humerus; 12, Coraco-radialis, or 
flexor brachii; 13, Lower extremity of humerus; 14, Brachial fascia; 15, 
Anterior extensor of the metacarpus, or extensor metacarpi magnus; 16, Belly 
and aponeurotic termination of the flexor brachii; 17, Ulna; 18, Ulnaris acces- 
sorius, or oblique flexor of the metacarpeus; 19, Internal flexor of the meta- 
carpus, or epicondylo-metacarpeus; 20, Radius; 21, Tendon of the oblique 
extensor; 22, Large metacarpal bone; 23, Flexor tendons of the foot; 24, Sus- 
pensory ligament; 25, Internal rudimentary metacarpal bone; 26, Extensor 
tendon of the foot; 27, Metacarpo-phalangeal sheath; 28, Lateral cartilages of 
the foot; 29, Podophylle. 


258 THE MUSCLES. 


B. Posterior Brachial Region. 


This is composed of five muscles, which have their movable insertion in 
common on the summit of the olecranon, and are consequently designated 
olecranian muscles. With reference to their action, they are also designated 
extensors of the fore-arm, and are distinguished into long, short, middle, and 


small. 


Preparation.—The muscles of this region ought to be studied before those of the 
preceding region. To dissect the large and short extensors, it is necessary to lay the 
limb on its inner face, remove the slight fibrous layer which covers these two muscles, 
and raise the abductors of the arm, which in great part conceal their origin. The limb 
is kept in the same position for the dissection of the small extensor, which is not easily 
accomplished, as it is almost entirely concealed by the short extensors which, besides, 
closely adhere to it. To dissect the long and middle extensors, it suffices to turn the 
limb on its external surface and cut away the vessels, nerves, and lymphatics which 
partly cover the latter. The first, lying closely to the internal face of the large extensor, 
requires some care in order to free it from its aponeurosis, 


1. Long Extensor of the Fore-arm. (Fig. 121, 6.) 


Synonyms.—Scapulo-olecranius—Girard. (A portion of the caput magnum of the 
triceps extensor brachit—Percivall. Long scapulo-olecranius—Leyh.) 


Form—Situation.—This is a wide muscle, flattened within and without, 
and applied against the inner face of the large extensor, to which it closely 
adheres. 

Structure and Attachments.—It is composed of an aponeurosis, attached 
to the posterior border of the scapula—jixed insertion: and a muscular 
portion, easily divisible into two fasciculi, one anterior, the other posterior. 
These two fasciculi are formed of vertical fibres, the longest of which are 
posterior, and terminate at the posterior border of the ulna, as well as on 
the antibrachial aponeurosis—movable insertion. 

Relations.—Outwards, with the large and middle extensors; inwards, 
with the sterno-trochineus, the adductor of the arm, and the great dorsal. 
Its aponeurosis adheres closely to the tendinous portion which terminates 
the last-named muscle, and its anterior border is united to the aponeurotic 
sheath of the coraco-radialis by a particular fibrous fascia, which covers the 
vessels and nerves on the inner aspect of the arm. 

Action.—It extends the fore-arm, and renders the antibrachial aponeurosis 
tense. 


2. Large Extensor of the Fore-arm. (Figs. 119, 7; 121, 7.) 


Synonyms.—Scapulo-olecranius major—Girard. The long portion of the triceps 
brachialis of Man. (Portion of the caput magnum of the triceps extensor brachti— 
Percival.) 


Volume —Form—Situation.—An enormous, short, and triangular muscle, 
occupying, with the short extensor, the space comprised between the 
posterior border of the scapula and the humerus. 

Structure and Attachments.—The fleshy mass constituting this muscle is 
formed of very thick fasciculi, among which are found some aponeurotic 
bands. These fasciculi have their origin on the dorsal angle and the axillary 
border of the scapula, either directly, or through the medium of two strong. 
fibrous layers, between which they are at first included. They are afterwards 
directed backwards and downwards, and converge towards a thick tendon 
which occupies the posterior and inferior angle of the triangle represented 
by this muscle. The tendon terminates by attaching itself to the summit of 


MUSCLES OF THE ANTERIOR LIMBS. 259 


the olecranon, after receiving a great number of fibres from the short extensor, 
and after gliding, by means of a synovial capsule, over the eminence which 
serves for its insertion. 

Relations.—The external surface is covered by a thin, fibrous, white-and- 
yellow elastic layer, which separates it from the panniculus; it is hollowed, 
near the upper border of the muscle, by an excavation into which is received 
the posterior portion of the long abductor. Its internal face responds to 
the great dorsal, the adductor of the arm, and to the long extensor. Its posterior 
border is margined by the latter muscle; the superior follows the axillary 
border of the scapula, and is attached to it to constitute the fixed insertion 
of the muscle; the inferior responds to the short and middle extensors. 

Action.—It is an extensor of the fore-arm. 


38. Short Extensor of the Fore-arm. (Fig. 119, 8.) 


Synonyms.—Humero-olecranius externus—Girard. The vastus externus of the 
triceps brachialis of Man. (Caput medium—Percivall.) 

Situation — Direction — Form — Structure. — This muscle is situated 
between the humerus and the inferior border of the preceding, and is 
directed obliquely downwards and backwards. It is thick and short, 
flattened and aponeurotic at its upper extremity, prismatic, and entirely 
formed of thick parallel muscular fasciculi for the remainder of its extent. 

Attachments.—One of its attachments is on the humerus, to the curved 
line extending from the deltoid imprint to the base of the articular head 
(see for this line Fig. 41, above 4), by the short aponeurosis of its superior 
extremity—fixed insertion ; the other is to the olecranon, either directly, or 
through the tendon of the large extensor—movable insertion. 

Relations—The prismatic shape of this muscle offers three faces, which 
respond: externally, to the two abductors of the arm and to a slight fibrous 
layer continuous, above, with that which covers the large extensor, and below, 
with the antibrachial aponeurosis; internally, to the small extensor, from 
which it is difficult to separate it, to the short flexor of the fore-arm, and to 
the anterior extensor of the metacarpus; superiorly, to the large extensor, 
which closely adheres to it. 

Action.—An extensor of the fore-arm. 


4. Middle Extensor of the Fore-arm. . (Figs. 119, 17; 121, 8.) 


Synonyms.—Humero-olecranius internus—Girard. The vastus internus of the 
triceps brachialis of Man. (Caput parvum—Perctvall.) 


Situation — Direction —Form—Structure— This muscle is situated at 
the internal face of the humerus, along the inferior border of the large 
extensor. It is oblique downwards and backwards, pyriform, bulging at its 
superior extremity, contracted inferiorly, where it terminates by two smail 
flat tendons. 

Attachments.—It originates, by its superior extremity, from the inner 
aspect of the humerus, behind and above the tuberosity on its body. One 
of its terminal tendons is attached to the summit of the olecranon ; the 
other glides over a small convexity on the inner side of that eminence, and 
goes to be inserted a little lower than the first. 

Relations.—Above, with the inferior border of the large extensor; out- 
wards, with the humerus, the short flexor, and short extensor of the fore- 
arm; inwards, with the humeral insertion of the great dorsal and the 
adductor of the arm, the long branch of the coraco-brachialis, the vessels 


260 THE MUSCLES. 


and nerves on the inner side of the arm, and 
the long extensor of the fore-arm. | 
Action.—An extensor of the fore-arm. 


5. Small Hatensor of the Fore-arm or Anconeus. 
(Fig. 85, 10.) 


Synonym.—Humero-clecranius minor—Girard. 


Form —. Structure — Situation—Relations— 
This is a small, thick, and prismatic muscle, 
almost entirely fleshy, situated behind the elbow 
articulation. It is applied against the synovial 
cul-de-sac which ascends into the olecranian 
fossa, and to which it is strongly attached; it 
is hidden by the short extensor, from which it is 
not easily distinguished. 

Attachments.—It originates from the margin 
of the olecranian fossa, chiefly above and out- 
wards. It terminates by being inserted: into the 
anterior and external part of the olecranon. 

Action.—This little muscle, a congener of the 
preceding, raises the articular capsule it covers, 
and prevents its being pinched between the bony 
surfaces. 


DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE 
ARM IN OTHER THAN SOLIPED ANIMALS. 


In all animals, the long flexor of the fore-arm, or 
coraco-radialis, is less thick and tendinous than in Soli- 
peds, 

In the Pig, Dog, and Cut, it comports itself in a 
special manner at its inferior extremity; it is attached 
at first to the bicipital tuberosity, and also furnishes a 
small tendinous branch which glides over the inner side 
of the radius by means of a synovial bursa, and is fixed 
within the ulna, towards the base of the olecranon. 

The short flexor of the fore-arm, or anterior brachial, 
is terminated, in the Pig, Dog, and Cat, by a small 
tendon which is fixed in the ulna, below the ulnar 
branch of the coraco-radialis. 

The long eatensor of the fore-arm, which is found in 
all the domesticated animals, arises from the external face 
of the great dorsal in the Pig and Dog. The middle 


are remarkable for their volume. 


DEEP MUSCLES ON EXTERNAL 
ASPECT OF RIGHT ANTERIOR 
LIMB. 

1, Scapula; 2, Coracoid process In Man, three muscles are situated in front of the 
of scapula; 3, Flexor brachii; 

4, Superior extremity of humerus; 5, External tuberosity of humerus; 6, Humeralis 
externus; 7, Body of humerus; 8, Biceps; 9, Anterior, or great extensor of the meta-. 
carpus; 10, Ulna, 11, Extensor pedis, or anterior extensor of the phalanges ; 12, Ulnaris 
accessorius, or ulnar portion of the perforans; 13, Lateral extensor of the metacar- 
pus, or extensor suffraginis, 14, Oblique extensor of the metacarpus; 15, Flexors of 
the foot; 16, Trapezum,17, Annular ligament; 18, Carpal ligament of perforans 
tendon, 20; 19, Perforatus; 21, Tendon of anterior extensor of metacarpus; 22, Small 
metacarpal bone; 23, Suspensory ligament, 24, Lateral band of metacarpo-phalangeal 
sheath , 25, Perforans tendon, 26, Branch of the suspensory ligament joining the 
' extensor pedis, 27, 


COMPARISON OF THE MUSCLES OF THE ARM OF MAN 
WITH THOSE OF ANIMALS, 


extensor of the fore-arm and anconeus of these animals 


MUSCLES OF THE ANTERIOR LIMBS. 261 


humerus: the biceps, coraco-brachialis, and the anterior brachialis; behind are found 
the triceps brachialts and the anconeus. 

The biceps, which corresponds to the coraco-radialis of animals, commences on the 
capula by two heads, which unite towards the upper part of the humerus. The lon 
or tion is detached from the upper part of the rim of the glenoid cavity; the shortest 
commences from the summit of the coracoid process. The inferior tendon of the biceps 
gives off, before fixing itself on the bicipital tuberosity, a fibrous lamella which is con- 

founded with the antibrachial aponeurosis. 

The coraco-brachialis has only one fleshy body. 

As in the Carnivora and Pig, the anterior brachiahs terminates on the ulna, below 
the coronoid process. 

The triceps brachialis exactly represents, by its three heads, the large, middle, and 
short extensors of the fore-arm of animals (See Fig. 120) 

There is nothing particular with regard to the anconeus. The long extensor of the 
fore-arm of the Horse has no representative in Man. 


MUSCLES OF THE FORE-ARM. 


These muscles, nine in number, distributed in two regions—anterior and 
posterior—envelop the bones of the fore-arm on every side except the 
internal, where the radius is in mediate contact with the skin. They all 
terminate on the different sections of the foot, which they flex or extend, 
and are contained in a common fibrous sheath, which constitutes the anti- 
brachial aponeurosis. 

Antibrachial Aponeurosis. 

This retaining fascia forms a very strong and resisting envelope, which 
is firmly fixed around the antibrachial muscles by the insertions it has on 
the bones of the fore-arm, being attached to the olecranon, the internal aspect 
of the radius, and to the inferior extremity of that bone, both inwards and 
outwards. 

Its external face is covered by superficial vessels and nerves, that are 
separated from the skin by a very thin fibrous layer, which is more 
particularly observable on the inner side, where it covers the antibrachial 
aponeurosis in a very evident manner; it is rendered tense by the sterno- 
aponeuroticus. Up to the present time, this fibrous layer has not been 
distinguished from the aponeurosis it covers, The inner face of the latter 
gives rise to several septa, which penetrate the interstices of the muscles to 
form around some of them special retentive sheaths; it adheres to several 
of them very intimately. At its upper border, this aponeurosis receives, 
inwardly, the insertion of the long extensor of the fore-arm; in front, the 
accessory band of the coraco-radialis ; outwardly, it is continuous with the 
fibrous fascia covering the external face of the olecranian muscles. Inferiorly, 
it is prolonged around the knee to form the tendinous sheaths in that 

“ region. 

The antibrachial aponeurosis is made tense by the contraction of the 
long extensor of the fore-arm and the coraco-radialis. With reference to 
the sterno-aponeuroticus, which has hitherto been regarded as intended to 
play the same part, it can only act on the fibrous fascia which covers, 
externally, the antibrachial aponeurosis. 

Preparation of the muscles of the fore-arm.—The preparation of these muscles is 
extremely simple, as it suffices to remove the antibrachial aponeurosis and the interstitial 
cellulo-adipose tissue, to expose and to isolate them from each other. No special 
recommendations need, therefore, be given, asa glince at figures 89, 119, 121, and 122 
will guide the student in his dissection, and supplement the manual details which would 
be superfluous here. 

Nevertheless, as the terminal insertions of some of these muscles are inclosed within 


the hoof, and as it is indispensable, in order to expose them, to remove this horny case, 
some explanation will be given as to the manner in which this should be effected, 


20 


262 THE MUSCLES. 


particularly as the apparent difficulty and labour too frequently cause this part to be 


omitted in the dissecting rooms. : 
1. The instruments necessary to remove the hoof are~. a scalpel, toe-knife, hammer, 


and a pair of pincers. ; 
2. The tint should be in « vertical position, held by one or two assistants, and the 


foot placed on a table, stool, or very solid block of wood. 
3. Pass the scalpel as deeply as possible around the coronet, to separate the wall of 


the hoof from the organised tissues. ; : ; 
4. With the knife and hammer, split the wall into four or five pieces by vertical 


incisions. 

5. When the wall is thus divided, it is sufficient to insert the knife under the frag- 
ments, and making it serve as a lever, tear them off; pincers may also be used for this 
purpose, each of the pieces being twisted from the sole. 

6. To remove the sole, the blade of the scalpel should be passed between its upper 
face and the plantar surface of the third phalanx; afterwards the toe-knife may be 
inserted in the interval at the bulbs of the frog, so as to slightly raise the external 
border of the sole. This is then seized by the pincers and pulled off, along with the 
frog, in a single piece, by a powerful twisting movement, aided by the assistants, who 
press on the limb in a contrary direction. 


A. Anterior Antibrachial Region. 


In Solipeds, this region includes four extensor muscles. ‘T'wo act on the 
entire foot; these are the anterior extensor and the oblique extensor of the 
metacarpus. Two others, the anterior and lateral extensor of the phalanges, 
terminate in the digital region. 


1. Anterior Extensor of the Metacarpus. (Figs. 119,11; 121,15; 122, 9.) 


Synonyms.—Epicondylo-premetacarpeus—Girard. Jt represents the two external 
Fat of Man. (Extensor metacarpi magnus— Percivall. Humero-metacarpeus — 

eylt. 

Situation—Direction—Form—Sitructure.—The anterior extensor of the 
metacarpus, situated in front of the radius, in an almost vertical direction, 
is composed of a muscular body anda tendon. The first has the form of an 
inverted cone, is intersected by some aponeurotic lamelle, and is composed 
of muscular fibres slightly arciform at their superior extremities. The 
second, at first rounded, then flattened, commences below the middle third 
of the radius, and succeeds the inferior extremity of the muscular portion. 

Attachments—-This muscle has its fixed insertion: 1, By the upper ex- 
tremity of its fleshy fibres, on the crest that limits, behind and below, the 
furrow of torsion of the humerus; 2, Above and in front of the inferior 
articular surface of the humerus, by means of a strong fibrous band common 
to it and the anterior extensor of the phalanges, and which expands on the 
deep face of these two muscles in becoming intimately united with the 
capsular ligament of the elbow articulation. Its movable insertion takes 
place on the anterior and superior tuberosity of the large metacarpal bone, 
by the inferior extremity of its tendon. 

Relations The muscular portion is covered by the antibrachial 
aponeurosis and the short extensor of the fore-arm. It covers the anterior 
face of the radius, as well as the elbow articulation; outwards and behind, 
it is in contact with the inferior extremity of the short flexor of the fore- 
arm or brachialis anticus, whose aponeurosis adheres intimately to the 
arciform portion of the fibres of the anterior extensor of the metacarpus, 
and appears to attach this muscle to the deltoid imprint. Its tendon 
covers a small portion of the anterior aspect of the radius, and ‘enters the 
internal vertical groove channeled in front of the inferior extremity of that 
bone ; afterwards it passes over the capsular ligament of the carpus, and is 


MUSCLES OF THE ANTERIOR LIMBS. 263 


maintained against that membranous expansion by a wide fibrous sheath, 
through which it glides by the aid of two synovial membranes. This 
tendon is crossed above the knee by that of the oblique extensor, which 
passes to its surface. 

Action.—The name of this muscle indicates its function; it extends the 
metacarpus on the fore-arm. 


2. Oblique Hatensor of the Metacarpus. (Figs. 119, 13; 121, 21; 122, 14.) 


Synonyms.—Cubito-premetacarpeus, or radio-premetacarpeus—Girard. It is the 
representative of the long abductor and short extensor of the thumb in Man. (Extensor 
metacarpt obliquus vel parvus—Percivall. Radio-metacarpeue—Leyh.) 


Situation—Form—Structure—Direction.—A small muscle situated at the 
internal side of the radius, beneath the anterior extensor of the phalanges, 
penniform in shape, strongly aponeurotic, and terminated by a tendon which 
turns obliquely round the anterior aspect of the radius in passing 
downwards and inwards, to reach the oblique channel on the inferior 
extremity of that bone, and to pass from thence to the inside of the knee. 

Attachments.—It has its origin on the external side of the radius ; its 
terminal tendon is fixed into the head of the internal metacarpal bone, by 
its fibres becoming confounded with those of the internal ligament of the 
carpus. 

Relations—This muscle is covered by the anterior extensor of the 
phalanges and the antibrachial aponeurosis. It successively covers the 
anterior face of the radius, the tendon of the anterior extensor of the 
metacarpus, the radial groove lodging its tendon, and in which it glides 
by means of a small synovial bursa, as well as the internal ligament of the 
carpus. 

Action.—It extends the metacarpus, and may make it pivot from within 
forwards. 


8. Anterior Extensor of the Phalanges. (Figs. 119, 14; 121, 15; 122, 9.) 


Synonyms.— Epicondylo-prephalangeus—Girard. The extensor communis digilorum 
of Man. (Extensor pedis—Percivall. Humero-prephalangeus—Leyh.) 


Situation—Direction—Extent—Form—Structure.—This is a long vertical 
muscle, situated external to, and behind the anterior extensor of the metacarpus, 
which it resembles in being composed of a fleshy and a tendinous portion. 
The muscular portion extends from the inferior extremity of the humerus to 
above the lower third of the radius; it is fusiform in shape, intersected by 
aponeurotic lamelle, and bifid at its superior extremity.1 The tendinous 
portion forms two unequal cords, which succeed the two terminal branches 
of the muscular part, and lie close to each other. These two cords enter 
the most external of the three grooves in front of the inferior extremity of 
the radius, and reach the anterior face of the carpal capsular ligament, 
against which they are maintained by an annular ligamentous apparatus. 
After passing from beneath this ring, the smallest, which is the most external, 
joins the tendon of the lateral extensor (Fig. 119,15). The principal branch 
(Fig. 119, 14’) continues its course on the anterior aspect of the middie 
metacarpal bone and articulation of the fetlock, until it arrives in front of 
the digit; here it terminates on the os pedis, after widening in a remarkable 
manner, and after receiving, laterally, at the middle of the first phalanx, a 


1 This division, which has been noticed by several writers, has nut been shown in 
figure 119. ‘Chis is a mistake, as it is constantly present. 


264 THE MUSCLES. 


reinforcing band which appears to be given off from the inferior extremity 
of the suspensory ligament of the fetlock. ; 

Attachments—The anterior extensor of the phalanges has its fixed attach- 
ment by the superior extremity of its muscular body: 1, Below the crest 
that limits, posteriorly, the furrow of torsion of the humerus; 2, In front 
of the inferior extremity of the humerus; 3, To the anterior border of the 
external ligament of the elbow joint; 4, To the external and superior 
tuberosity of the radius; 5, To the external border of that bone. Its 
principal tendon is inserted into the pyramidal eminence of the third phalanx, 
after being successively attached to the capsular ligament of the fetlock 
joint and the anterior surfaces of the first two phalanges. . 

Relations—The muscular portion, covered by the antibrachial aponeu- 
rosis, covers the articulation of the elbow, the anterior face of the radius, 
and the oblique extensor of the metacarpus; it responds, in front, to the 
anterior extensor of the same ray, to which it is intimately attached by its 
upper half; behind, to the lateral extensor of the phalanges. The tendinous 
cords cover the different parts already enumerated in describing the course 
of the muscle—that is, the anterior face of the radius, the carpal joints, the 
principal metacarpal bone, the articulation of the fetlock, and the first two 
pbalanges. A vaginal synovial membrane envelops them at the knee, to 
facilitate their gliding in the radial groove and on the anterior aspect of 
the capsular ligament of the carpus; while the inner surface of the prin- 
cipal tendon is covered, in front of the fetlock, by a small vesicular 
capsule, and still lower by the synovial membranes of ‘the two inter- 
phalangeal articulations. 

Action.—This muscle extends the third phalanx on the second, that on 
the first, and this again on the metacarpal bone. It may also concur in the 
extension of the entire foot on the fore-arm. 

(Two small muscles, which should be only considered as heads of this 
anterior extensor, have been particularly described by Thiernesse and 
Phillips, and named after these authors. 

The muscle of Phillips, according to Leyh, is long and thin; it commences 
on the lateral external ligament of the ulnar articulation and the external, 
superior tuberosity of the radius; it is directed obliquely downwards and 
forwards, lying beside the muscular portion of the common extensor. 
Towards the middle and outer aspect of the radius, it gives off a small 
tendon, which passes in the same sheath as the preceding, in front of the 
carpus, and continues its course between the two tendons of the extensors 
of the phalanges to near the fetlock, where it becomes confounded with that 
of the lateral extensor, a little above the first phalanx. 

The muscle of Thiernesse is smaller than that of Phillips, and situated at 
its inner side. It arises in front of the transverse ligament of the ulna by a 
muscular portion, becomes thinner as it descends, and terminates by a fine 
tendon which is confounded with that of the common extensor, towards the 
lower third of the fore-arm.) 


4. Lateral Extensor of the Phalanges. (Figs. 119, 16; 122, 18.) 
_ Synonyms.—Cubito or radialis-prephalangeus, according to Girard. The extensor 
minimi digiti of Man. (Extensor suffraginis—Percivall.) 


__ Direction—Situation—Extent--Form—Structure.—A small vertical muscle, 
situated at the external side of the fore-arm, between the preceding and 
the external flexor of the metacarpus, and formed of a fleshy body and a 


MUSCLES OF THE ANTERIOR LIMBS. 265 


tendon. The fleshy body, not very considerable, and flattened from 
before backwards, extends. from the upper extremity of the radius tu 
the lower fourth of the same bone. The tendon (Fig. 119, 16’), at first 
rounded, then flattened, reaches the gliding groove which divides the 
external inferior tuberosity of the radius into two portions, passes to the 
external side of the carpus, crossing the lateral ligament common to the articu- 
lations of this region, and arrives at the anterior surface of the principal meta- 
carpal bone, where it receives the small tendinous branch detached from the 
anterior extensor, as well as a strong fibrous band coming from the external 
side of the carpus (Fig. 119,17). Afterwards, descending alongside the 
external border of the principal tendon of its congener, and united to it by a 
fibrous fascia, it gains the articulation of the fetlock, and expanding, ter- 
minates at the upper extremity of the first phalanx. 

Attachments.—1, By its muscular body, to the external tuberosity of the 
radius, the external ligament of the elbow articulation, and to the bodies of the 
two bones of the fore-arm—origin ; 2, By the inferior extremity of its tendon, 
to the capsule of the metacarpo-phalangeal articulation, and in front of the 
superior extremity of the first phalanx—termination. 

Relations—lIts muscular portion, enveloped in a special aponeurotic 
sheath, responds: in front, to the anterior extensor of the phalanges ; behind, 
to the external flexor of the metacarpus and the perforatus and perforans 
muscles; outwards, to the antibrachial aponeurosis. The tendon, surrounded 
by a vaginal synovial sheath, in passing over the carpus, covers, beyond the 
knee, the anterior aspect of the metacarpus, and the anterior ligament of the 
metacarpo-phalangeal articulation, over which it glides by means of a small 
vesicular synovial bursa. It is covered by a slight fibrous fascia, which 
separates it from the skin, and which is also spread over the tendon of the 
anterior extensor. 

Action.—This muscle is an extensor of the digit, and also concurs in the 
extension of the entire foot on the fore-arm. / 


B. Posterior Antibrachial Region. 


This is composed of five flexor muscles grouped vertically behind the 
bones of the fore-arm. Three are situated superficially, and act on the whole 
foot; these are the external flexor, oblique jfleaor, and the internal flexor of 
the metacarpus. The other two, fixed to the digit by their inferior extremity, 
and covered by the preceding, are designated the superficial and deep flexors 
of the phalanges. ‘ 


i 


1. External Flexor of the Metacarpus, or Posterior Ulnaris' (Fig. 119, 18.) 


Synonyms.—Epicondylo-supercarpeus—Girard. (Flexor metacarpi  externus— 
Percivall. Humero-supercarpeus externus—Leyh.) 


Situation.—The external flexor of the metacarpus is situated at the ex- 
ternal side of the fore-arm, between the lateral extensor of the phalanges 
and the oblique flexor. 

Form—Structure— Attachments.—This muscle is elongated from above to 
below, flattened from one side to the other, thick in its middle part, and 
intersected by very strong aponeurotic bands. It commences on the summit 


- It is known that the bony eminences, hithertc termed in veterinary anatomy 
“ epitrochlea ” and “ epicondyle,” correspond: the first, to the epicondyle of Man, the second, 
to the epitrochlea. It need excite no surprise, therefore, to see the denominations given 
by Girard to the muscles of the posterior antibrachial region changed as above, 


266 THE MUSCLES. 


of the epivendyle by a very powerful, but extremely short tendon. In- & 
feriorly, it terminates by a second tendon longer than the preceding, and 
divides into two branches, an anterior and a posterior. The latter (Fig. 119, 
20), short and wide, is inserted into the supercarpal bone in becoming mixed 
up with the oblique flexor. The former (Fig. 119, 19), rounded and funicular 
in shape, glides by means of a synovial bursa in the channel excavated on 
the external aspect of the supercarpal bone, and which is converted into 
a canal by a little fibrous apparatus; this branch is afterwards fixed on the 
head of the external metacarpal bone by being confounded with the external 
ligament of the carpus. 

Relations. —Covered by the antibrachial aponeurosis, this muscle covers 
the two flexors of the digit. Its anterior border responds to the lateral 
extensor of the phalanges; the posterior to the oblique flexor. Its superior 
tendon lies behind the external ligament of the elbow joint, and is covered 
deeply by the external cul-de-sac of the synovial capsule belonging to that 
articulation. 

Action.—It flexes the foot on the fore-arm. (Leyh observes that it is 
more particularly concerned in what is known as “ high action.”) 


2. Oblique Flexor of the Metacarpus, or Anterior Ulnaris. (Fig. 121, 19.) 


Synonyms.—Epitrochlea supercarpeus—Girard. (Flexor metacarpt medius—Percivall. 
Humero-metacarpeus internus—Leyh.) 


Situation—Form—Structure.—This muscle, situated behind and within 
the fore-arm, is an exact counterpart of the preceding in form and structure. 

Direction.—Bourgelat has improperly named it an oblique flexor, for its 
direction is vertical like that of the other muscles of this region. 

Aitachments.—It has its origin: 1, On the base of the epitreehiea by the 
tendinous fibres of its superior extremity; 2, On the olecranon, by a small, © 
very thin, and very pale fleshy band, which is annexed to the principal 
muscular body, and soon unites with its posterior border. Its inferior tendon 
is undivided, and terminates on the supercarpal bone, along with the ex- 
ternal flexor, to which it is intimately attached. 

Relations.—By its superficial face, with the antibrachial aponeurosis, 
which strongly adheres to its tendon; by its deep face, with the flexors of 
the phalanges. Its anterior border is covered by the internal flexor; the 
posterior responds to the external flexor. 

Action.—It is a congener of the preceding. 


3. Internal Flexor of the Metacarpus, or Palmaris Magnus. (Fig. 121, 19.) 


Synonyms.—Epitrochlea metacarpeus—Girard. (Flexor metacarpi internus—Peret- 
vall. Humero-metacarpeus internus— Leyh.) 


Situation —Form — Structure —Attachments—This muscle is situated 
within the fore-arm, against the posterior face of the radius, and in its 
general features resembles its congeners, the two preceding muscles. It is, 
however, not so wide, is thinner, and less aponeurotic. Its upper extremity 
is fixed, by tendinous fibres, to the base of the eypidmpelskm at the same point 
as the oblique flexor, with which it is confounded—origin. Its inferior © 
extremity terminates in a long, thin, funicular tendon which passes through 
a fibrous sheath at the inner side of the knee, and is inserted into the head 
of the internal metacarpal bone—movable insertion. 

Relations.—It is covered by the antibrachial aponeurosis, and covers the 
oblique flexor, the perforatus and perforans, as well as important blood- 


MUSCLES OF THE ANTERIOR LIMBS. 267 


vessels and nerves. Its anterior border responds to the radius. A synovial 
sheath envelops its terminal tendon, and facilitates its movements in the 
fibrous canal through which it passes. 

Action —It is a congener of the preceding. 


4. Superficial Flexor, Sublimis of the Phalanges, or Perforatus. (Figs. 
89, 119, 121, 122.) 


Synonyms.—Epitrochlo-phalangeus— Girard. (Flexor pedis perforatus—Pereivall 
Humero-coronaris or humero-phalangeus— Leyh.) . 


Situation.—The superficial flexor of the phalanges is situated, with its 
fellow, the perforans, beneath the flexors of the metacarpus, which form around 
them a kind of muscular envelope. 

Form—Structure—HEatent.—It is composed of a muscular and tendinous 
portion. The first, long, thin, prismatic, and divided by a great number of 
aponeurotic intersections, extends from the inferior extremity of the arm 
nearly to the carpus. The tendon, continuous with the inferior extremity of 
the muscular portion, receives at its origin an enormous fibrous production 
that arises from the eminence of insertion situated at the posterior face of 
the end of the radius, and which contracts somewhat intimate adhesions 
with the antibrachial aponeurosis, as well as with the perforans, 

After being thus reinforced, this tendon passes through the carpal sheath 
and arrives behind the fetlock, where it forms a ring (Fig. 89, 14) for the 
passage of the tendon of the deep flexor. To this peculiarity is owing the 
designations of perforatus and perforans, given to the two flexors of the * 
phalanges. Afterwards it is inflected forwards over the sesamoid groove, 
and terminates by two branches towards the middle of the digital region. 

Attachments.—It takes its origin, in common wigh the perforans, at the 
summit of the epitpeshiea, and is inserted, by the bifurcations of its tendon, 
into the extremities of the pulley formed behind the superior extremity of the ~ 
second phalanx. 

Relations—The muscular portion, covered by the external and the 
oblique flexors of the metacarpus, may be said to be incrusted in the perforans, 
to which it adheres in the most intimate manner, The tendon covers that 
of the latter muscle, and is in turn covered by the fibrous expausions of the 
two metacarpal and metacarpo-phalangeal sheaths which are now to be 
described. 

The Carpal sheath is the name given to a very remarkable annular 
apparatus, formed by the superficial face of the common posterior ligament of 
the carpus, and by a thick expansion of inelastic white fibrous tissue, together 
constituting a perfect arch thrown across like a bridge, from the supercarpal 
bone to the inner side of the carpus. This arch is continuous, above, with 
the antibrachial aponeurosis, and is prolonged, below, over the metacarpal 
portion of the flexor tendons. An extensive synovial membrane covers the 
internal aspect of the carpal sheath, envelops the perforatus and perforans 
in their passage through this canal, ascends above the carpus, and descends 
as far as the lower third of the metacarpal region. 

The Metacarpo-phalangeal sheath is formed by the sesamoid groove, the 
posterior face of the principal navicular ligaments, that of the glenoid fibro- 
cartilage of the first interphalangeal articulation, and by the posterior pulley 
of the second phalanx. It is completed by a very wide membranous expansion 
applied against the flexor tendons, closely adherent to the perforatus on the 
median line of the digit, and fixed, laterally, to the phalangeal bones by the 


268 THE MUSCLES. 


aid of three special fibrous bands. A very extensive vaginal synovial mem- 
brane covers the internal walls of this passage, and is reflected on the flexor 
tendons; it ascends along these tendons to the inferior extremities of the 
lateral metacarpals, and forms, inferiorly, 2 somewhat large cul-de-sac which, 
behind the second phalanx, lies against the posterior cul-de-sac of the 
articular synovial membrane of the foot, and also against the superior cul-de- 
sac of the navicular sheath. The metacarpo-phalangeal sheath is also named 
the great sesamoid sheath ; but this designation is more frequently applied 
to the synovial membrane lining its walls. 

Action.—This muscle flexes the second phalanx on the first, that on the 
metacarpus, and the entire foot on the fore-arm. Its tendon, through the 
influence of the fibrous band which attaches it to the posterior face of the 
radius, acts mechanically as a stay while the animal is standing, by maintain- 
ing the metacarpo-phalangeal angle. 


5. Deep Flexor of the Phalanges or Perforans. (Figs. 119, 121, 122.) 


Synonyms.—Cubito-phalangeus, or radio-phalangeus—Gitrard. (Flexor pedis perforans 
—Pereivall. Humero-radio-phalangeus—Leyh.) 


Situation— Composition—Eatent—This muscle is situated immediately 
behind the radius, and is composed of three portions which unite at the 
carpus, to be continued to the inferior extremity of the digit by a long 
powerful tendon. 

Form, Structure, and Attachments of the muscular portion of the perforans.— 
“The three muscular portions may be distinguished, in regard to their origin, 
—~into opit-eehtean, ulnar, and radial. 

The epitrochlean portion is the most considerable, and lies beside the 
Ws coturatns ; being three or four times the volume of that muscle, it is easily 

divided into several very tendinous fasciculi, which leave the summit of the 
epitrochlea along with the superficial flexor. The ulnar portion, situated 
between the external flexor and the oblique flexor of the metacarpus, is very 
short and conoid, thick at its superior extremity, contracted at its inferior, 
to which succeeds a long flat tendon, united below to the principal tendon; 
it has its origin on the summit and the posterior border of the olecranon. 
The radial portion, representing the flexor longus pollicis of Man, is the 
smallest, and is deeply concealed beneath the epitrochlean muscular portion. 
The fibres composing it are fixed to the posterior surface of the radius, 
where they are slightly divergent, and collect upon a small particular tendon, 
which is confounded with the common tendon after contracting adhesions 
with the radial band of the perforatus. 

Course and Attachments of the tendon—The tendon which succeeds these 
three portions enters the carpal sheath with that of the superficial flexor. 
Towards the middle of the metacarpal region, it receives a strong fibrous 
band from the great posterior ligament of the carpus (Figs. 119, 23 ; 122, 18), 
traverses the sesamoid annular apparatus of the perforatus tendon, passes 
between the two terminal branches of that tendon, over the pulley on the 
posterior face of the second phalanx, and afterwards widens to form a large 
expansion designated the plantar aponeurosis. 

This aponeurosis glides, by its anterior face, over the inferior surface of 
the navicular bone, by means of a particular synovial membrane, the 
small navicular sheath, and is covered, posteriorly, by a fibrous layer, noticed 
for the first time by M H. Bouley, who considers it as a reinforcing 
sheath for the perforans tendon. It is finally inserted into the semilunar 


MUSCLES OF THE ANTERIOR LIMBS. 269 


crest of the os pedis, and the median imprints situated behind this crest, 
in becoming confounded at its sides with the tissue of the lateral fibro- 
cartilages. 

The navicular sheath is vesicular in form; it covers the navicular bone 
and the single ligament of the pedal articulation, becomes reflected on the 
plantar aponeurosis in front of this ligament, and ascends to the inferior 
cul-de-sac of the sesamoid sheath, where it is again reflected and continued 
by itself. It therefore forms two culs-de-sac, one superior, the other inferior, 
which are readily perceived in a longitudinal and vertical section of the 
digital region. The first is in contact with the posterior cul-de-sac of the 
synovial membrane of the pedal articulation, and is separated from the 
inferior sac of the sesamoid sheath by a transverse layer of yellow fibrous 
tissue which attaches the perforans tendon to the posterior face of the second 
phalanx. The second is situated beneath the interosseous ligament which 
unites the navicular bone to the third phalanx. 

The reinforcing sheath of the perforans tendon is formed by a fibrous 
membrane applied against the posterior face of the plantar aponeurosis. 
This membrane adheres intimately below, to the expansion it covers, and 
ends in becoming entirely confounded with it. It is fixed, at its borders, to 
the inferior extremity of the first phalanx, by means of two lateral bands. 

Relations.—The epitrochlean muscular portion is covered, at its origin, 
by the external cul-de-sac of the elbow joint, which sac also covers the other 
muscles attached to the epitrochlea—the external and oblique flexors of the 
metacarpus. It responds, anteriorly, with the radius and radial portion of 
the muscle; posteriorly, with the perforatus; externally, with the external 
flexor of the metacarpus; inwardly, with the internal and oblique flexors 
of the same ray. 

The ulnar -portion, covered by the antibrachial aponeurosis, covers the 
epitrochlean portion. 

The radial division is comprised between the latter and the posterior face 
of the radius. ; 

The tendon is in contact, posteriorly, with that of the perforatus ; 
anteriorly, with the posterior ligament of the carpus, the suspensory ligament 
of the fetlock, and the sesamoid groove ; by its sides, with the vessels and 
nerves of the digit. Its terminal expansion is covered by the plantar cushion, 
which adheres to it, in front, in the most intimate manner; it covers the 
navicular bone. 

Action.—This muscle flexes the phalanges on one another and on the 
metacarpus. Jt also concurs in the flexion of the entire foot on the fore-arm. 
The band which attaches its tendon behind the carpus, as well as its phalan- 
geal reinforcing sheath, gives it the mechanical power necessary to support 
the angle of the metacarpo-phalangeal articulation and the digital region, 
while the animal is in a standing posture. ; 

(In the “ Deep Flexor,” of M. Chauvean’s description, we find included 
two portions which are separately named and described by Mr. Percivall 
and Professor Gurlt. These are the ulnaris accessorius and radialis accessorius 
of the former, and the cubito-ulnar and radial branches of the latter. These, 
in reality, are portions of the perforans, and have been so designated in this 
treatise. Though arising independently, they terminate in the perforans 
tendon before it leaves the carpal sheath, and join with it in flexing the 
metacarpus and phalanges.) 


270 


Fig. 123. 


MUSCLES OF THE FORE-ARM 
OF THE OX; EXTERNAL FACE. 
1, Anterior extensor of the 
metacarpus; 1’, Insertion of 
its tendon; 2, Oblique ex- 
tensor ; 3, Common extensor 
of the digits; 3’, Its tendon; 
3”, Terminal bifurcation of 
that tendon; 4, Proper ex- 
tensor of the internal digit ; 
4’, Its tendon; 5, Proper 
extensor of the external 
digit; 5’, Its tendon; 6, Its 
branch of insertion into the 
second phalanx; 7, Branch 
to the third phalanx; 8, 
External flexor of the meta- 
carpus; 9, Olecranian por- 
tion of the perforans; 10, 
Tendon of the perforans; 
11, Tendon of the perfo- 
ratus ; 12, Suspensory liga- 
ment of the fetlock; 13, 


THE MUSCLES. 


DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE FORE- 
ARM IN OTHER THAN SOLIPED ANIMALS, 


Ruminants.—In the Ox and Sheep, the anterior ex- 
tensor of the metacarpus comports itself as in Solipeds. 

The oblique extensor of the metacarpus of the same 
region terminates inside the upper extremity of the prin- 
cipal metacarpus. 

The anterior extensor of the phalanges offers a remark- 
able disposition. This muscle is divided throughout its 
length into two parallel portions: an external, which forms 
the common extensor of the digits; and an internal, th 
proper extensor of the internal digit. , 

a. The fleshy body of the common extensor (fig. 123, 3) 
is a little more voluminous than that of the second muscle. 
Its tendon (3’) commences near the inferior third of the 
radius, passes over the knee, the metacarpal bone, and the 
metacarpo-phalangeal articulation. On arriving at the 
origin of the digits it bifurcates, and each of its branches 
goes to be inserted into the pyramidal eminence of the 
third phalanx (3”),, This muscle, in extending the digits, 
brings them togefher, as M. Lecoq has judiciously re- 
marked. 

b. The proper extensor of the internal digit (fig. 123, 4) 
much resembles the common extensor in volume, form, 
and direction. Its tendon (4') passes, with that termi- 
nating the latter muscle, into one of the inferior grooves 
of the radius and over the capsular ligament of the carpus, 
where the two cords are enveloped by a common synovial 
sheath. Arrived at the metacarpo-phalangeal articulation, 
this tendon is placed at the excentric side of the internal 
digit, and descends, gradually expanding, until it reaches 
the inferior extremity of this bone; towards the middle of 
the first phalanx, it receives from the suspensory ligament 
of the fetlock two constraining bands similar to those 
which, in Solipeds, bind the anterior extensor of the pha- 
langes on the same bone. This tendon bifurcates infe- 
riorly ; one of its branches is attached to the anterior face 
of the second phalanx; the other, much wider than the 
first, covers the common external lateral ligament of the 
two inter-phalangeal articulations, and terminates on the 
whole external side of the third phalanx. In the Sheep, 
this second branch is feeble, and is directed towards the 
heel, which it envelopes by uniting its fibres with the per- 
forans tendon and the plantar cushion. 

The lateral extensor of the phalanges of Ruminants is 
thicker than in the Horse, and constitutes the proper ex- 
tensor of the external digit (fig. 123, 5). Its terminal 
tendon (4’, 6, 7) comports itself exactly the same as that 
of the proper extensor of the internal digit, and conse- 
quently does not merit a special description. We may 
remark, with M. Lecoy, that these two muscles separate 
the digits from each other in extending them; they are, 
therefore, to a certain point, antagonists of the common 
extensor. 

The perforatus of the Ox and Sheep is composed of 
two portions, whose tendons unite towards the middle of 
the metacarpal region. The single tendon (fig. 124, 1, 2,3) 
which results from this union afterwards divides into two 
branches, each of which comports itself, in regard to the 


The band it furnishes to the perforatus to form the ring through which the perforans 
passes ; 14, The external band it gives off to the proper extensor of the external digit 5 
15, Coraco-radialis; 16, Anterior brachial; 17, Anconeus, 


& 


MUSCLES OF THE ANTERIOR LIMBS. 271 


digits, as the single perforatus tendon does in the Horse, except that they receive from 
the suspensory ligament a fibrous band analogous to that which, in Solipeds, goes to 
the perforans tendon. This band (fig. 123, 13) concurs in the formation of the annular 
ligament through which the latter tendon passes. 

In the Ox, the terminal tendon of the perforans does not receive any carpal band; 
this goes to the perforatus. Above the fetlock, it divides into two branches, one for each 
digit, which, after traversing the perforatus, terminates behind the inferior face of 
the third phalanx. There it is blended with the plantar cushion, 
the inferior interdigital ligament, and a fibrous fascia already 
noticed in the description of that ligament. This layer arises 
from the aponeurosis covering the flexor tendons in the meta- 
carpal region; it descends on the heels, behind and outside the 
digits, remains united to that of the other digit by an inter- 
mediate fibrous fascia, and is attached to the enveloping sheaths 
of the flexor tendons, as well as to the superior interdigital liga- 
ment. Each terminates inferiorly, in becoming united to the 
proper extensor of the digit, the plantar cushion, the inferior 
digital ligament, and the deep flexor of the phalanges. 

There is not, properly speaking, w phalangeal reinforcing 
sheath; though we may consider as such the superior fasciculi 
of the inferior interdigital ligament (fig. 124, 6). 

Pic.—In this animal, the anterior extensor tendon of the 
phalanges passes to the superior extremity of the inner large 
metacarpal bone, and that of the oblique extensor to the small 
internal metacarpal. 

Instead of the anterior extensor of the phalanges, two muscles 
are found analogous to those described as existing in Ruminants. 
The external, or common extensor of the digits, is easily divided 
into several fasciculi, and is terminated by four tendinous branches 
which reach the pyramidal eminence of the third phalanx of the 
four digits. The tendon of the small external digit often gives 
off a thin bifid ramification, destined to supplement the tendons of 
the two large digits. The internal muscle, or proper eatensor of 
the two internal digits, possesses a bifurcated tendon; each branch rxprnous AND LIGA- 
goes to the excentric side of the third phalanx of the digit it is  yEnrous APPARA- 
charged to move. TUS OF THE POSTE- 

With regard to the muscles of the posterior antibrachial yor FACE OF THE 
region, it is remarked: 1, That the anterior branch of the ter-  pigrraz REGION IN 
minal tendon of the external flexor of the metacarpus passes to tHE OX; POSTERIOR 
the head of the outer metacarpal be 2, That the pee flexor tmp. 
terminates on the metacarpal of the great external digit ; 3, 54 5 
That the perforatus is formed by two muscular bodies, each 4 e oe i Side tee 
terminated by a tendon inserted, inferiorly, into the second pha- branches 323 Thetk 
lanx of one of the great digits. 4, That the perforans is divided det 
into four terminal branches which arrive at the large phalanx of 
the digits. erior bands of the 

Carnivora.—In the Dog and Cat, the anterior extensor of the LAr ied nek digital liga- 
metacarpus divides, at its lower extremity, into two branches, went attached tothe 
which resemble those of the two external radial muscles of Man: 
one is inserted into the metacarpus of the index, the other into 
the metacarpus of the medius (fig. 125, a, 5, 6, 7). ligament ; 8, 8, Sus- 

The oblique extensor passes to the metacarpus of the thumb; pensory ligament of 
it furnishes, besides, a small particular branch that glides, by {p, fetlock. 
means of a sesamoid, over the third bone of the inferior row of 
the carpus, and is blended with the posterior ligament of the ie 
carpus (fig. 125, 4, 8; B, 4; Dp, 8); it separates the thumb fiom the other digits, but we 
think it scarcely adapted for the function of extensor. — ; 

The anterior extensor of the phalanges of solipeds is replaced by a single muscle, the 
common extensor of the digits, terminated by a quadrifurcated tendon, whose branches 
are distributed to the four great digits fig. 125, a, 9, 9"). : i 

The tendon of the lateral extensor is divided into three branches, which are inserted 
on the anterior face of the three outer digits, and are blended with the tendons of the 
common extensor, or with the fibrous bands furnished to these tendons by the inter- 
osseous metacarpal muscles. ; . ; . 

: The anernal flinor of the metacarpus comports itself as in the Pig, But the oblique 


bifurcation; 4, 4, 
Perforans; 6, 6, Su- 


first phalanx; 7, In- 
ferior _interdigital 


~ 


272 THE MUSCLES. 


flexor is covered by the perforatus, and its olecranian portion, thicker than in the other 
animals, is only united to the principal tleshy body altogether inferiorly. The internal 
jlecor is feeble and conoid; its tendon, thin and long, reaches the metacarpus of the 
index. 

The perforatus of the Dog and Cat offers a long, wide, and superficial body, 
separated from the perforans by the oblique flexor of the metacarpus. Its tendon 
passes outside the carpal sheath, and is divided into four branches, attached by their 
inferior extremity to the second phalanx of the four principal digits. 

For the perforans, it is noted : ; 

1, That the radial portion of the muscle (the long flecor of the thumb in Man) com- 
mences towards the superior extremity of the radius (fig. 125, c, 4). 

2. That the ulnar division is w semi-penniform muscle, attached by the superior 
extremities of its fibres to nearly the whole extent of the posterior face of the ulnar (fig. 
125, c, 3). 

3. That the epitrochlean portion sends off, above the knee, a small particular 
fasciculus terminating in a very thin tendon, which becomes lost in ihe fibrous arch of 
the carpal sheath (fig. 125, c, 6). This small muscle represents the palmaris brevis of 
Man. 

The terminal tendon divides into five branches, one for each digit (fig. 125, p, 4, &c.). 

There have been already described in these animals: 

1. Two external radial muscles, only distinct at their terminal extremity, and con- 
founded for the remainder of their extent. This is the anterior extensor of the meta- 
carpus in Solipeds (fig. 125, a, 5, 6, 7). 

2. A long abductor of the thumb, which appears to be the representative of the 
analogous muscle, and the short extensor of the same digit in Man. It is the oblique 
extensor of the metacarpus in the Horse (fig. 125, a, 8). 

3. A common eatensor of the digits; the anterior extensor of the phalanges in the 
Horse (fig. 125, a, 10). 

4. A proper extensor of the three external digits, the proper extensor of the little 
finger in Man, or lateral extensor of the phalanges in the Horse (fig. 125, a, 10). : 

5. A posterior ulnar, or external flexor of the metacarpus in the Horse (fig. 125, 
A, 14). 

6. An anterior ulnar, or oblique flexor of the metacarpus in the Horse (fig. 125, 
D, 6). 

7. A great palmar, corresponding to the internal flexor of the metacarpus in the 
Horse (fig. 125, B, 8). 

8. A small palmar, a dependency of the deep flexor of the phalanges (fig. 125, c, 6). 

9. A flexor sublimis of the phalanges (fig. 125, D, 1). 

10. A deep flexor of the phalanges (fig. 125, c, 5, D, 3). 

11. A long flexor of the thumb, united to the preceding muscle, the radial portion of 
the perforans (fig. 125, ©, 4). 

But in Carnivora there are five additional muscles, which are not generally found in 
the other animals. These are: the proper extensor of the thumb and index, long 
supinator, short supinator, round pronator, and the square pronator. A special descrip- 
tion will be given of these. 


MUSCLES PROPER TO THE FORE-ARM OF CARNIVORA, 


1. Proper Extensor of the Thumb and Index. (Fig. 125, a, 11; B, 8.) 


Synonyms.—The extensor secundi tnternodit pollicis and extensor indicis of Man. 

This is a very small muscle, composed of a fleshy body and a tendon. The first is 
thin and fusiform, and is situated under the lateral extensor ; it has its origin with the 
oblique extensor of the metacarpus at the external side of the radius. The tendon 
crosses the anterior aspect of the knee, enveloped by the synovial sheath of the common 
extensor of the digits, under which it passes. It divides into two branches, one of 
which goes to the thumb, the other to the index.! f 


2. Long Supinator. (Fig. 125, a, 12; c, 8.) 


This muscle only exists in the rudimentary state in Carnivora. Its existence in the 
Dog has even been denied, but this is an error; our researches’ have demonstrated that 
it is present, in a more or less evident manner, in all breeds, 


’ Jn very powerful Horses, and more frequently in the Ox, we have met with traces 
of this muscle in the form of a deep fasciculus situated in front of the lateral extensor. 


MUSCLES OF THE ANTERIOR LIMBS. 


Fig. 125. 


( MUSCLES OF THE FORE-ARM AND PAW OF THE DOG. 

A. Anterior superficial region.—1, Short flexor of the fore-arm (anterior brachial) ; 
2, Long flexor of the fore-arm (brachial biceps) ; 3, Anconeus; 4, Round pronator ; 
5, Anterior extensor of the metacarpus (external radial); 6, Its tendon of inser- 
tion, destined for the fourth metacarpal bone; 7, That which goes to the third ; 
8, External oblique of the metacarpus (long abductor and short extensor of the 
thumb); 9, Common extensor of the digits; 9’, Its terminal tendon at the point 
where it divides into four branches; 10, Proper extensor of the three external 
digits, or lateral extensor of the phalanges in the Horse; 10’, Its terminal tendon 
at the commencement of its trifurcation; 11, Proper extensor of the thumb and 
index; 11', Its terminal tendon; 12, 12, Long supinator; 13, External flexor of 
the metacarpus (posterior ulnar). 

B. Deep anterior region.—1, Round pronator ; 2, Sbort supinator ; 3, Proper extensor 
of the thumb and index; 4, Oblique extensor of the metacarpus; 5, Superior 
insertion of the anterior extensor of the metacarpus; 6, Ditto of the anterior 
extensor of the phalanges; 7, Proper extensor of the three external digits; 8, 
Internal flexor of the metacarpus (great palmar); 9, Levator humeri; 10, 11, 
Long and short flexors of the fore-arm. 

C. Deep posterior region.-1, Round pronator ; 2, Square pronator ; 3, Ulnar portion 
of the perforans; 4, Radial portion of the same (long flexor of the thumb); 5, 
Terminal tendon of the same; 6, Tendon of the small palmar (division of the 
perforans); 7, Anterior extensor of the metacarpus; 8, Long supinator; 9, 
Epicondyloid insertion of the perforatus, perforans, and oblique and internal 
flexors of the metacarpus; 10, Olecranian insertion of the oblique flexor; 11, 
Supercarpal insertion of the same; 12, Terminal tendon of the internal flexor ; 
13, Proper extensor of the external digits; 14, Coraco-radialis; 15, Tendon of 
the extensors of the fore-arm. 

D. Superficial posterior region, and the special muscles of the foot or hand.—1, Perfo- 


273 


27 THE MUSCLES. 


It is a very delicate band, situated in front, and on the inner side of the anterior 
extensor of the metacarpus, taking its origin, along with that muscle, from the crest 
limiting the furrow of torsion of the humerus, behind the ridge; and terminating 
within the inferior extremity of the radius by fleshy and aponeurotic fibres. This small 
muscle can have but a very limited influence on the movements of the bones of the 
fore-arm, because of its trifling volume. As its name indicates, it acts in supination. 


3. Short Supinator (Fig. 125, B, 2.) 


A triangular and slightly divergent muscle, covered by the anterior extensor of the 
metacarpus and the common extensor of the digits. It has its origin in the small fossa 
situated outside the humeral trochlea, by a flat tendon which is confounded with the 
external lateral ligament of the elbow joint. It terminates above the anterior face and 
the inner side of the radius, by the inferior extremities of its fleshy fibres. Covered by 
the two preceding muscles, it covers the elbow articulation and the bone receiving its 
insertion. It ought to be considered, in Carnivora, as the principal supinator; it pivots 
the radius on the ulna, so as to turn the anterior face of the first bone outwards, 


4, Round Pronator. (Fig. 125, 8, 1; ©, 1.) 


Situated on the inner and upper part of the fore-arm, between the great palmar or 
internal flexor of the metacarpus and the interior extensor of the same ray, the round 
pronator is a thick and short muscle, which originates on the small epicondyloid 
tuberosity of the humerus, and terminates at the internal side of the radius by aponeu- 
rotic fibres. 

5. Square Pronator. (Fig. 125, c, 2.) 


This muscle is situated immediately behind the bones of the fore-arm, beneath the 
muscular masses of the posterior antibrachial region, It extends from the insertion of the 
flexors of the fore-arm to near the carpus, and is formed of. transverse fibres which pass 
directly from the ulna to the radius. It is, then, no longer, as in Man, a square muscle 
attached only to the lower fourth of these two bones, The two pronators are antagonists 
of the short supinator, turning forwards the anterior face of the radius and metacarpus. 


COMPARISON OF THE MUSCLES OF THE FORE-ARM OF MAN WITH THOSE OF ANIMALS. 


All the muscles of the fore-arm of Man are more or less perfectly represented in the 
fore-arm of Carnivora. 

In Man, these muscles are described in placing the fore-arm in a state of supination, 
and are divided into three regions: anterior, external, and posterior. 


A. Anterior Region. 


This comprises eight muscles -— 

1. The round pronator, absent in animals except the Carnivora. This muscle forms 
the internal oblique prominence in the bend of the elbow. It leaves the epitruchlea and 
the coronoid process of the ulna, terminating on the middle third of the external face of 
the radius. 

2, The great palmaris, which corresponds to the internal flexor of the metacarpus of 
the Horse. Situated within the preceding, it is attached, above, to the epitrochlea; 
below, to the base of the second metacarpal. It is more especially a flexor of the 
hand. 

3. The small palmaris, whose presence is not constant, and which is represented in 
the Dog by a portion of the deep flexor of the phalanges. 


ratus ; 1’, Its tendon divided at its passage behind the carpal sheath; 2, Do., Its 
terminal branches; 3, Perforans; 3’, Its tendon divided after its exit from the 
carpal sheath ; 4, Do., Its terminal branches; 5, Tendon of the internal flexor of the 
metacarpus; 6, Oblique flexor (anterior ulnar); 7, Inferior extremity of the long 
supinator; 8, Terminal tendon of the oblique extensor of the metacarpus ; 9, 
Short abductor of the thumb; 10, Opponent of the thumb; 11, Short flexor of 
the thumb; 12, Adductor of the thumb, transformed, in the Dog, into the adduc- 
tor of the index; 13, Short flexor of the small digit; 14, Adductor of the small 
digit; 15, Opponent of the small digit; 16,16, Metacarpal interosseous muscles $ 
a, a, a, Bands which maintain the flexor tendons on the metacarpo-phalangean 
articulations, and limit the separation of the digits; collectively, they represent, 
in a rudimentary state, the palmar aponeurosis of Man, : 


MUSCLES OF THE ANTERIOR LIMBS. 


4, The superficial flexor or perforatus has two planes of muscular fib 
ficial plane is destined to the tendons of the edie aud i. ee 


tendons of the index and little finger. 
phalanges of the above-named digits, 
gits, 


275 


The super- 
annularis ; the deep plane to the 


These tendons are fixed into the secondary 


it 5 The anterior ulnar resembles the oblique flexor of the metacarpus of the Horse. 
; 18 inserted, above, into the epitrochlea and the olecranon; below, in the pisiform bone. 
ts action is transmitted, by a fibrous band, from this bone to the fifth metacarpal. 


It flexes the hand by inclining it inwards, 


Fig. 126. 


Fig. 127. 


SUPERFICIAL MUSCLES OF HUMAN FORE-ARM. 

1, Biceps, with its tendon; 2, Brachialis an- 
ticus; 3, Triceps; 4, Pronator radii teres; 
5, Flexor carpi radialis; 6, Palmaris lon- 
gus; 7, A fasciculus of flexor sublimis 
digitorum; 8, Flexor carpi ulnaris; 9, 
Palmar fascia; 10, Palmaris brevis; 11, 
Abductor pollicis; 12, Flexor brevis pol- 
licis; 13, Supinator longus; 14, Extensor 
ossis metacarpi, and extensor primi inter- 
nodii pollicis. 


DEEP LAYER OF SUPERFICIAL MUSCLES OF 
HUMAN FORE-ARM. 

1, Internal lateral ligament of elbow joint; 
2, Anterior ligament; 3, Orbicular ligament 
of radius; 4, Flexor profundus digitorum ; 
5, Flexor longus pollicis; 6, Pronator quad- 
ratus; 7, Adductor pollicis; 8, Dorsal in- 
terosseous of middle, and palmar inter- 
osseous of ring finger; 9, Dorsal inter- 
osseous muscle of ring-finger, and palmar 
interosseous of little finger. 


6. The deep flexor or perforans is resolved into two fasciculi: one, the internal, for 
the little finger, the annularis, and the medius the other, the external, for the index. 
The three first tendons are at first united to each other by fibrous bands, and together 
pass through a sheath formed by the perforatus. ; 

7. The proper flexor of the thumb, represented in the Dog by the radial portion of the 


perforans. 


It is attached, for one part, to the upper three-fourths of the anterior face of 


276 THE MUSCLES. 


the radius, the interosseous aponeurosis, and the coronoid process of the ulna; on the 
other part, to the second phalanx of the thumb. . ; 

8. The square pronator, a thick, quadrilateral muscle with transverse fibres, situated 
at the deep and inferior portion of the fore-arm. This muscle in the Dog is much more 
extensive in length. 

B. External Region. 


The muscles of this region are four in number, two of which, the swpinators, are only 
represented in Carnivorous animals:— ; 

1. The long supinator forms a prominent mass at the bend of the elbow. It is 
attached to the inferior third of the external border of the humerus, and to the base of 
the styloid process of the radius. It is a flexor of the fore-arm, not a supinator, as its 
name indicates. ; 

2. The first external radial is represented by a portion of the anterior extensor of the 
metacarpus of animals. It commences at the inferior part of the external border of the 
humerus, and terminates at the posterior part of the base of the second metacarpal. 

3. The second external radial, also represented by a portion of the anterior extensor 
of the metacarpus, terminates at the base of the third metacarpal. ee 

4. The short swpinator, a muscle bending round the upper third of the radius, is the 
essential agent in supination. 


c. Posterior Region. 


The muscles of this region, divisible into two layers, are :— 

1. The common extensor of the digits—anterior extensor of the phalanges of the Horse 
—divided into four tendinous branches which pass to all the fingers, except the thumb. 

2. The proper extensor of the litile finger, whose tendon is joined to the branch of the 
common extensor that passes to the auricularis—the lateral extensor of animals. 

3. The posterior ulnar, corresponding to the external flexor of the metacarpus of the 
Horse. It goes to the epicondyle at the upper extremity of the fifth metacarpal. 

4. The long abductor of the thumb, resembling a portion of the oblique extensor of 
the metacarpus of animals. This muscle is attached to ihe posterior face of the ulna 
and radius, and the upper extremity of the first metacarpal. 

5. The short extensor of the thumb, which is also represented in animals by a portion 
of the oblique extensor of the metacarpus. 

6. The long extensor of the thumb, arising from the ulna, and inserted into the second 
phalanx of the thumb, ‘This muscle limits, inwardly, the excavation termed the 
anatomical snuff-box. 

7. The proper extensor of the index, whose tendon is confounded with the branch of 
the common extensor passing to this digit. 

These two latter muscles, blended in the Dog, exist only in a rudimentary state in 
the other animals. 

We say nothing of the anconeus, placed in the antibrachial region by anthropoto- 
mists, and which has been described in the posterior brachial region. 


MUSCLES OF THE ANTERIOR FOOT OR HAND. 
These will be studied successively in Carnivora, the Pig, Solipeds, and Ruminants. 


A. Muscles of the Anterior Foot or Hand of Carnivora. 


All the muscles of the human hand are found in that of Carnivora, some perfectly 
developed, others quite rudimentary. These muscles are: 1, The short abductor of the 
thumb ; 2, The opponent of the thumb; 3, The short flexor of the thumb; 4, An adductor 
of the index—adductor of the thumb in Man; 5, The cutaneous palmar ; 6, The adductor 
of the small digit ; 7, The short flecor of the small digit; 8, ‘The opponent of the small 
digit; 9, The three lumbrict ; 10, Four interosseous metacarpals. 


1. Short Abductor of the Thumb. (Fig. 125, p, 9.) 


This is rudimentary, like the digit it is intended to move, and is situated behind 
the metacarpal bone of the thumb; it is composed of very pale fleshy fasciculi, which 
are continued inferiorly by rome tendinous fibres, It has its origin at the carpal arch, 
and terminates on the metacarpal bone of the thumb, as well as at the external side of 
the superior extremity! of the first phalanx. It is a flexor and abductor of the thumb. 


1 It is necessary to remember that the position of the digits is considered in relation to 
the axis of the hand—that is, the median line separating the medius from the annularis 


MUSCLES OF THE ANTERIOR LIMBS. 277 


2. Opponent of the Thumb. (Fig. 125, p, 10.) 


This vestige of the thick short muscle which bears the same name in Man is situated 
beneath and within the preceding, in a slightly oblique direction downwards and 
outwards. Pale and almost entirely muscular, it is attached to the posterior ligament 
of the carpus and the metacarpal bone of the thumb. Owing to the conformation of this 
digit in Carnivora, this muscle cannot act as it does in Man in producing the opposition 
of the thumb; it only draws it towards the axis of the hand, and is therefore merely an 
adductor of the thumb. 


3. Short Flexor of the Thumb. (Fig. 125, p, 11.) 


A very small muscle, deeper in colour than the other two, and situated between 
them, the adductor of the index, and the fourth interosseous muscle. It is fixed, by its 
superior extremity, in the mass of the posterior carpal ligament, and attached, below, to 
the internal side of the first phalanx. It is a somewhat extensive flexor of the thumb. 


4, Adductor of the Index, (Fig. 125, p, 12.) 
Synonym.—The adductor of the thumb in Man. 


Elongated, prismatic, compressed on each side, included between the third and 
fourth interosseous muscles, and concealed by the tendinous portion of the common 
flexor of the digits, this muscle is attached, superiorly, to the posterior carpal ligament 
with the third interosseous muscle. It is fixed, inferiorly, by means of a small flattened 
tendon, along the superior and internal side of the first phalanx of the index. It is 
regarded as the adductor of the thumb in Man transformed into an adductor of the index, 
in conseyuence of the atrophy of the fifth digit. 


5. Cutaneous Palmar (Palmaris Brevis). 


A thick, hemispherical, musculo-adipose body, forming the base of the exterior 
tubercle placed behind the carpus. It adheres intimately tv the skin by its superficial 
face, and deeply to the aponeurosis covering the muscles of the hand. 


6. Adductor of the Small Digit. (Fig. 125, p, 14.) 


This muscle is superficially situated, external to, and behind the outer metacarpal 
bone, and is composed of a thick, conical fleshy body, concave on its anterior surface, 
convex posteriorly, and of a long, thin, and flat tendon, which succeeds the inferior 
cxtremity of the muscular portion. 

It is attached, by the superior extremity of the latter, to the pisiform bone; the 
tendon terminates outside the superior extremity of the first phalanx of the small digit. 

This muscle separates that digit from the axis of the hand, and is therefore an 
abductor and not an adductor, as its name would indicate. That name has been given 
to it in Man, because the hand has been considered in a state of supination, a position in 
which it is effectively an adductor in regard to the median plane of the body. If this 
name has been preserved here, it is owing to a desire not to import any new element of 
confusion into a nomenclature already too complicated. 


7. Short Flexor of the Small Digit. (Fig. 125, p, 13.) 


Situated within the preceding, in a slightly oblique direction downwards and out- 
wards, flattened before and behind, triangular, and almcst entirely muscular, this muscle 
derives its origin from a ligament which unites the pisiform bone to the metacarpal 
region, and terminates inferiorly on the tendon of the adductor, whose congener it is. 
It may also concur in the flexion of the small digit, though to a very limited degree. 


8. Opponent of the Small Digit. (Fig. 125, p, 15.) 


A muscle elongated from above downwards, flattened before and behind, situated 
under the perforans tendons, behind the second interosseous muscle, in a direction 
slightly downwards and outwards. It originates from the posterior ligament of the 
carpus, and terminates within the superior extremity of the first phalanx of the external 


digit by a small tendon. It acts as an adductor by drawing the small digit towards the 
axis of the hand. 
21 


a” 


278 THE MUSCLES. 


9, Lumbrict. 


These small muscles, which owe their name to the resemblauce they bear to the 
lumbricales or earthworms, are only three in number in Carnivora. They occupy the 
interval between the four chief branches of the perforans tendon, from which they have 
their origin; they terminate, by a small fibrous digitation, on the extensor tendons of 
the three external digits. It is often impossible to trace them so fur; for they are 
frequently observed to stop within and above the first phalanx of the digits for which 
they are destined, Their functions cannot be rigorously defined in Carnivora. 


10. Metacarpal Interosseous Muscles. (Fig. 125, p, 16, 16.) 


These are four thick and prismatic muscular fasciculi, elongated from above to 
below, bifid et their inferior extremity, placed parallel to one another, in front of the 
flexor tendons, from which they are separated by a thin aponeurotic layer, and behind 
the four large metacarpals. 

They have their origin on the posterior and lateral faces of these bones, as well as on 
the posterior carpal and intermetacarpal ligaments. Mach terminates, by the two 
branches of its inferior extremity, on the great sesamoids of the digit to which it corres- 
pouds. There they are continued by a small tendon, which joins the chief extensor of 
the digit. These muscles oppose undue extension of the digits while the animal is stand- 
ing, flex them on the metacarpal bones, and maintain the extensor tendons on the anterior 
aspect of the phalanges. 


B. Muscles of the Anterior Foot in the Pig. 


In our notes on the myology of this animal, we find . 

1. A muscle which originates in the substance of the metacarpo-supercarpal 
ligament, and terminates on the proper extensor of the small external digit by a fibrous 
strip joined to the external faxciculus of the first Interosseous muscle ; it is also attached 
to the external sesamoid. This is, no doubt, the representative of the short flexor of the 
small digit in Man and the Carnivora. 

2. A single, but very voluminous lumbricus, fixed, at the one part, to the perforans 
tendon, and at the other, to the proper extensor tendon of the small internal digit 
(index), as in the preceding muscle. 

3 Four interosseous metacarpal muscles, similar to those in the Dog, and whose 
terminal digitations join the proper extensor tendons. The interosseous muscles of the 
two small digits are not only divided at their inferior extremity, but throughout their 


. whole length are observed to be two very distinct fasciculi, one superficial and external, 


the other deep and internal. The fibrous membrane covering these muscles, and which 
separates them from the perforans tendons, is much thicker than in the Carnivora. 


C. Muscles of the Anterior Foot in Solipeds. 


In Solipeds only two lumbrici and two interosseous metacarpal muscles have 
to be described. 

1. The lumbrici originate at the right and the left of the perforans 
tendon, above the sesamoid annular band cf the perforatus. They each 
terminate by a thin tendon, which is lost in the fibrous lamina enveloping 
the elastic cushion of the ergot of the fetlock. 

2. The interosseous muscles (anterior lumbrici—Percivall) have been 
wrongly considered by French veterinary anatomists as lumbrici muscles, 
and are described by them as the superior, or great lumbrici. Situated within 
the rudimentary metacarpal bones, these two little muscles are formed of a 
very delicate fleshy mass imbedded in the fibrous tissue surrounding the head 
of the metacarpal bones, and of a long tendon which descends to the metacarpo- 
phalangeal articulation, to be confounded with the band furnished to the 
anterior extensor of the phalanges by the suspensory ligament. Sometimes 
this tendon is directly united to one of the extensors of the phalanges. 

These two muscles represent the interossei of the lateral digits. With 
regard to those of the median digit, they are transformed, as we have 
already seen, into a fibrous brace which constitutes the suspensory ligament 
of the fetlock. 


sgt 


MUSCLES OF THE ANTERIOR LIMBS. 279 


D. Muscles of the Anterior Foot in Ruminants. 


These animals have no muscles, properly speaking, in the region of the foot; in fact, 


we only find in them the supensory ligament of the fetlock, which is the imterosseous of 
the two complete digits. 


COMPARISON OF THE HAND OF MAN WITH THAT OF ANIMALS, 


The muscles of Man’s hand are numerous and well-developed, in consequence of the 
extent and variety of the movements of its various parts. They are divided into three 
groups: the external, or group of the thenar eminence, induce the movements of the 
thumb ; the internal, or group of the hypothenar eminence, those of the little finger; and 
the middle group, occupying the metacarpal spaces, comprising the interosseous muscles, 


In addition, there is found in the hand a cuticularis muscle, the cutaneous palmaris 


(palmaris brevis). 


The cutaneous palmaris occupies two-thirds of the hypothenar eminence; its fibres 


are directed downwards and inwards. 
hand. 


A. Muscles of the Thenar Eminence. 


These muscles, nearly all present in the Dog, 

are: 
1. The short adductor of the thumb, whose 
fibres, leaving the lower portion of the anti- 
brachial aponeurosis, the process of the trape- 
zius and the seaphoides, are succeeded by a ten- 
don which is inserted into the upper extremity 
of the first phalanx of the thumb. 

2. The opponent (opponens) of the thumb, 
which passes trom the anterior part of the tra- 
pezium to the external border, and near the 
anterior face of the first metacarpal. 

8. The short flexor of the thumb, a muscle 
adjoining the preceding, and which is resolved 
into two series of fibres—a deep and a super- 
ficial. : 

4. The short adductor of the thumb, a trian- 
gular muscle, occupying the outer half of the 
hollow of the palm. It is attached to the os 
magnum, along the entire length of the third 
metacarpal bone and, by a tendon, to the sesa- 
moid and supero-internal tuberosity of the first 
phalanx of the thumb, 


B. Muscles of the Hypothenar Eminence. 


These muscles are: 1. The abductor of the 
little finger, a small fusiform muscular body, 
which is attached, above, to the pisiform bone, 
and below to the supero-internal part of the 
first phalanx. 

2. The short flexor of the little finger, situ- 
ated without the preceding, fixed in one part 
to the process of the unciform bone, and in the 
other to the inner part of the first phalanx. 

3. The opponent (opponens) of the little finger, 
a triangular muscle, situated below the pre- 
ceding. It is inserted into the process of the 
unciform bone, then into the inner border of 


It corrugates the skin on the ulnar border of the 


MUSCLES OF HUMAN HAND. 


1, Annular ligament; 2, 2, Origin and in- 


sertion of the abductor pollicis muscle ; 
8, Flexor ossis metacarpi, or opponens 
pollicis; 5, Deep portion of flexor brevis 
pollicis; 6, Adductor pollicis; 7, 7, Lum- 
bricales muscles arising from the deep 
flexor tendons, upon which the figures 
are placed; 8, A tendon of deep flexor ; 
9, Tendon of flexor longus pollicis; 10, 
Abductor minimi digitii; 11, Flexor 
brevis minimi digitii; 12, Pisiform 
bone; 13, First dorsal interosseous 
muscle, the abductor indicis. 


the fifth metacarpal and the adjacent portion of its anterior face. 


C. Interosseous Muscles. 
«The interosseous muscles are situated in each interosseous space, two for each space, 


and are divided into dorsal and palmar. 


As there are four interosseous spaces, there ought 


to be eight muscles ; but it is usual to exclude the short adductor of the thumb, because 


© 


280 THE MUSCLES, 


of its special insertions; this reduces the total number of interosseous muscles to seven— 
four dorsal and three palmar. 

“These small muscles arise from the lateral faces of the metacarpals to the lateral 
and upper portions of the first phalanges. By their contraction, they incline these 
phalanges laterally, and consequently carry the corresponding digit inwards and 


outwards.” . ; 

It may be added that the lumbrici muscles are small muscular and tendinous 
fasciculi annexed to the *endons of the deep flexor of the phalanges, and whose tendons 
terminate on the extern... side of the four last digits in becoming blended with the 


interossei. 


Artiote III].—Muscies or tHe Posterior Limes. 


These form four principal groups: the muscles of the croup, thigh, leg, 
and foot. 


MUSCLES OF THE GLUTEAL REGION OR CROUP. 


This region is composed of three superposed muscles, which are applied 
to the ilium, and are distinguished according to their relative situation as 
the superficial, median, and deep gluteus.’ . 

They are covered by a thick fibrous fascia, a prolongation of the aponeu- 
rosis of the great dorsal, and which is continued backwards over the muscles 
of the posterior crural region, where it is confounded with the superficial 
lamella of the fascia lata. This gluteal aponeurosis is fixed to the external 
angle of the ilium and the supersacral spine. By its deep face it gives 
attachment to several fasciculi of the superficial and middle glutei. y 


Preparation.—1. Place the animal on its side, or, better, in the second. position. 
2. Remove the skin from this region in order to show the gluteal aponeurosis, and to 
study its extent, attachments, and relations. 3. Cut away this aponeurosis to expose 
the anterior point of the middle gluteus and the muscular portion of the superficial. 
To prepare the aponeurotic portion of the latter muscle, the sacro-sciatig.insertion of the 
long vastus must be detached by the scalpel and thrown. downwards. 4. Incise the 
superficial gluteus near its femoral insertion, and reverse it on the sacral spine, so as to 
lay bare the external face of the middle or principal gluteus. 5. Divide this muscle near 
its femoral insertions, taking care not to injure these,-and remove the whole of its mass, 
studying meanwhile the nature of its relations ¢o the parts it covers; the deep or small 
gluteus then becomes apparent, and may be conveniently examined. 


1. Superficial Gliteus. (Fig. 129, 4.) 


Synonyms.—Ilio-trochanterius medius—Girard. Gluteus minor—Bourgelat. Gluteus 


Ee 


medius—Figot and Lafosse. The gluteus magnus of Man. (Gluteus externus—Percivall. 
Tlio-trochanterius externus—Leyh.) 


ae 

Composition—Situation.—This muscle is composed of fleshy portion, 
situated beneath the gluteal aponeurosis, and an aponeurotic portion entirely 
concealed by the anterior portion of the long vastus (abductor magnus 
—Percivall). ; 

Form and Structure—The muscular por on is triangular, and most 
frequently divided into two branches, an external and internal, by an ex- 
cavation which deeply indents its superior border. Its constituent fasciculi 
are very thick, loosely attached to each other, and are all directed back- 
wards and downwards to converge into a flat tendon, which terminates the 
inferior angle of the muscle. The aponeurosis likewise terminates the in- 
ferior angle of the muscle. This aponeurosis, also triangular, is con- 


1 For the justification of the employment of these new denominations see note, 
page 177 


ra 1% 


MUSCLES OF THE POSTERIOR LIMBS, 281 


founded, anteriorly, with-the posterior border of the muscular portion of its 
terminal tendon; at its inner and superior border it degencrates into 
cellular tissue. ‘ 

_Attachments.—This muscle has its fixed insertion: 1, On the internal 
aspect of the gluteal aponeurosis, by the superior extremity of its muscular 
fasciculi ;+ 2, On the postéro-external angle of the ischitim; and the ischiatic 
ligament, by the internal border of its aponeuroticy portion. It has its 
movable insertion, by means of its terminal tendon, on the small external or 
third trochanter of the femur. 

Relations.—Outwardly, with the gluteal aponeurosis and the anterior 
portion of the long vastus. Inwardly, with the middle gluteus; by its 
anterior border, with the fascia lata, to which it is closely united. 

Action.—This muscle has been ju«tly considered by Lafosse a~.an abductor 
of the thigh. Bourgelat wrongly regarded it as an extensor, and Girard 
and Rigot have repeated his error. Lecoq has proved that it rather produces 
flexion than extension. (Leyh states that it is an extensor and a rotator of 
the thigh outwards. ) 


* 


2. Middlé Gluteus. (Fig. 129, 1.) 


Synonyms.—Hlio-trochanterius magnus—Girard. +Gluteus maximus—Bourgelat, 
Lafosse, Risotyetc. Gluteus medius ofMan. (Gluteus maximus—Percivall. Superior 
portion of the great tlio-trochanterius—Leyh.) a 

Volume—Situatiop:—This muscle, the largest of the glutei, presents a 
considerable volume, and is applied against the iliac fossa, the sacro-ischiatic 
ligament, and the ilio-spinalis muscle. : 

Fr + and Structure.—It is elongated from before to behind, wide and 
very thick in its middie, prolonged forward by a thin point, and terminated 
behind by three branches of insertion—two tendinous and one muscular. 
The muscular ‘fasciculi entering into its composition are generally very 
thick and more-or less long; all converge towards the posterior insertions 
of the muscle. ; 

Attachments.—1, By the superior or anterior extremities ‘of the muscular 
fasciculi, on the internal aspect. of ‘the gluteal aponeurosis, the aponeurosis 
of the common mass, the superior face and the two anterior angles of the 
ilium, the two sacro-iliac ligaments, and a small portion of the sacro-ischiatic 
ligament. 2, On the trochanter (major) by its three posterior branches: 
the first, or median, is a thick, round tendon fixed on the summit; the 
anterior is formed by a second wide, thin, and flat tendon, which is inserted 
into the crest, »fter gliding over the convexity; the posterior is a small, 
triangular, fleswy slip, aponeurotic at its anterior border, by means of which 
it is attached behind the trochanter. This slip corresponds to the pyramidal 
muscle of Man. ae 

Relations.—Covered by the gluteal aponeurosis and the superficial gluteal 
muscle, it covers the ilio-spinalis, which receives its anterior point, the 
iliac fossa, the small gluteal, the ilio-sacral, and sacro-ischiatic ligaments, the 
sciatic nerves, and the gluteal nerves and vessels. Near the external angle 
of the ilium it is bordered by the fascia lata and the iliacus, which are 
closely united to it. : 

Action — When its fixed point is superior, this muscle extends and abducts 
the thigh; but when the femur is fixed, it causes the pelvis to rock on the 

® 


1 We have been frequently able to convince ourselves that none of the fasciculi of 
the superficial gluteus proceed direct from the ilium or the sacral spine. 


fe 
& 


282 THE MUSCLES. 


superior extremity of that bone, and assists in rearing. In the first instance 
it acts as a lever of the first order; in the second, as one of the third order. 


Fig. 129. 


Wi 


SUPERFICIAL MUSCLES OF THE CROUP AND THIGH. 


1, Middle gluteus, or gluteus maximus; 2, Anterior spinous process of ilium; 3, 
Muscle of the fascia lata, or tensor vagine; 4, Superficial gluteus, or gluteus 
externus ; *, Great trochanter of femur; 5, Fascia lata; 6, Patella, with insertion 
of rectus; 7, Long vastus, or adductor magnus; 8, Superior.and, 9, lateral coccy- 
geal muscles; 10, Semitendinosus and semimembranosus; 11, 12, Inferior 
portions of long vastus; 13, Fascia of the thigh; 14, Vastus externus. 


3. Deep Gluteus. (Fig. 181, 5.) 


Synonyms.—Tlio-trochanterius parvus—Girard. Gluteus medius—Bourgelat. Glu- 


teus minimus—Lafosse and Rigot. The gluteus minimus of anthropotomists. (Gluteus 
internus—Percivall.) 7 


Form—Situation.—A small, short, thick. and quadilateral muscle, 
flattened above and below, situated beneath the preceding, and above the 
coxo-femoral articulation. 


Structure and Attachments—It is composed of voluminous muscular and 


MUSCLES OF THE POSTERIOR LIMBS. 283 


tendinous fasciculi, which arise from the neck of the ilium and the supra- 


cotyloid ridge, to be directed outwards and backwards, and terminate within 
the convexity of the trochanter. 


Relations —Its upper face responds to the middle gluteus ; the inferior 
covers the coxo-femoral articulation, and strongly adheres to the fibrous 
capsule of that joint; this face is also separated from the anterior gracilis 
(ilio-femoralis) of the thigh and the origin of the anterior rectus (rectus 
femoris), by a very strong fibrous layer, which extends from the external 
border of the ilium to the base of the trochanter. Its posterior border is in 
relation with the anterior gemellus of the pelvis. 

Action.—It is the special abductor of the thigh, and is also an 
accessory rotator of the femur inwards. (Leyh says it is a congener of the 
preceding muscle, and therefore an extensor of the thigh. It may also 
maintain the capsular ligament tense.) 


DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE GLUTEAL REGION IN OTHER THAN 
SOLIPED ANIMALS. 


In Ruminants and the Pig, the gluteal muscles much resemble, though they sensibly 
differ from, those of Solipeds, In fact, the superficial gluteus and the long vastus form 
but one and the same muscle: the mi/dle gluteus, thinner than in the Horse, is not so 
much prolonged in front on the ilio-spinalis; and, on the contrary, the deep gluteus, 
more developed than in the Horse, is easily divided into two portions, which Rigot has 
designated as two distinct gluteals. : 

In Carnivora, the superficial gluteus is voluminous; it proceeds from the sacrum, 
and terminates by an aponeurosis below and behind the trochanter. This aponeurosis 
receives, in front, a small muscular band which arises by tendinous tibres from the 
surface of the middle gluteus, near the external angle of the ilium, and which resembles 
the external branch of the superficial gluteus of the Horse. In these animals, also, the 
middle gluteus does not extend beyond the lumbar border of the ilium in front, and 
terminates behind by a single branch. 


COMPARISON OF THE GLUTEAL MUSCLES OF MAN WITH THOSE OF ANIMALS.. 


The gluteal muscles are distinguished, in regard to their volume, into great, medium, 
and small (see note, p. 177). 

The great gluteus (gluteus maximus) corresponds to the superficial gluteal of animals. 

The medium gluteus (gluteus medius) to the middle gluteus of Solipeds. 

The small gluteus (gluteus minimus) to the deep gluteus. 

The medium gluteus does not extend beyond the crest of the ilium im front (see 
Figs. 133, 134). 

With regard to the great gluteus, it is inserted inwardly into the sacrum and the 
coccyx; below, into the external bifurcation of the linea aspera, from the trochanter to 
the middle third of the femur. 


MUSCLES OF THE THIGH. 


These have been divided into three secondary regious, which are: the 
anterior crural (or femoral) or patellar, the posterior crural (or femoral), and the 
internal crural (or femoral) region. 


A, Anterior Crural or Femoral Region. 


This region comprises three muscles situated in front of the femur: the 
muscle of the fascia lata, the crural triceps, and the anterior gracilis of the 
thigh. 


Preparation.—1. Place the subject in the first posit’on. 2. Study the fascia lata 
muscle immediately after removing the skin from this region. 3. Take away ths 
muscle and the superficial gluteus, the long vastus, the semitendinosis and semimem- 
branosis, the two adductors of the leg, the pectineus, and the two adductors of the thigh, 
to expose the three portions of the triceps. Separate these three muscular divisions from 
one another, commencing above where they are scarcely adherent. Dissect’ the anterior 
gracilis at the same time. 


284 THE MUSCLES. 


1. Muscle of the Fascia Lata. (Fig. 129, 3.) 
Synonyms,—Ilio-aponeuroticus— Girard. (Tensor vagine—Percivall. Ischio rotu- 
leus externus—Leyh.) f 

Form—sSituation.—A flat and triangular muscle, situated in front of the 
superficial gluteus, and outside the external vastus. ; 

Structure—Attachments.—It comprises: 1, A flabelliform muscular 
portion covered on its faces by tendinous fibres, and attached, superiorly, to 
the external angle of the ilium; 2, An aponeurosis named the fascia lata, 
continuous with the inferior border of the muscular portion, and soon divided 
into two superposed layers, one superficial, the other deep. ‘The latter is 
insinuated between the long vastus and the external vastus, joins the terminal 
tendon of the superficial gluteus, and is inserted into the external border of 
the femur. The first, which also appears to divide into two layers, is spread 
outwardly over the long vastus, where it is confounded with the gluteal 
aponeurosis; and inwardly, over the internal crural muscles, to become 
united to the femoral aponeurosis. Below, it is prolonged to the patella, 
into which it is fixed ; it is even continued below that bone, to join the terminal 
aponeurosis of the posterior branch of the long vastus. 

Relations —Outwards, with the skin; inwards, with the external vastus, 
the anterior rectus, and the iliacus; behind, with the superficial and middle 
glutei. In front, it responds to a cluster of lymphatic glands, and receives 
on its aponeurosis the insertion of the panniculus carnosus. 

Action.—It flexes the femur by raising the entire limb, and renders tense 
its own terminal aponeurosis. 

(In speaking of the uses of this muscle, Leyh states that, in addition to 
its being a flexor of the thigh and an extensor of the leg through its action 
on its aponeurosis, it maintains the position of the limb while the animal is 
standing, and allows the other muscles to become relaxed.) 


2. Crural Triceps. 


An enormous muscle lying against the anterior and lateral aspects of the 
femur, composed of three portions which are not very distinct from each 
other for the greater part of their extent, and which are separately described 
as the anterior rectus or straight muscle, and the vastus externus and internus. 


A. Antsrion Strateut Muscoiz or tan Tuicu, on Mippie Portion or 
THE TRICEPS. 

The ilio-rotuleus of Girard. (Rectus—Percivall. Anterior ilio-rotuleus—Leyh.) 
(Fig. 137, 16.) 

This muscle is imbedded between the two lateral portions of the triceps, 
and extends from the cotyloid angle of the ilium to the patella, in a direction 
slightly oblique forwards and downwards. 

Form—Structure.—EHlongated, thick, and fusiform, the anterior rectus 
offers, at its superior extremity, two short and flattened tendinous branches ; 
its middle portion is formed of pale-red muscular fibres lying close to each 
other, and marked by tendinous intersections; its inferior extremity is 
enveloped by a vast aponeurotic cone. 

_ Attachments.<-It originates, by its two superior branches, from the 
imprints which ‘surmount, forwards and outwards, the lip of the catia 


’ Following the example of M. Cruveilhier, we will describe by this name the triceps 
cruris of the older anatomists, and the anterior rectus of the thigh. 


MUSCLES OF THE POSTERIOR LIMBS. 285 


oak It terminates, by its inferior extremity, on the anterior face of the 
patella. 

Relations Externally, internally, and posteriorly, with the two other 
portions of the triceps; anteriorly, with the muscle of the fascia lata. Its 
superior extremity, included between the iliacus and the deep gluteus, is 
separated from the coxo-femoral capsule by a little adipose cushion which is 
insinuated between its two branches. 

Action.—An extensor of the leg and flexor of the thigh. 

B. Exrernan Vastus (Fig. 129, 4).—Form+EHatent—Situation.—This 
is a thick and wide muscular mass, flattened on each side, extending from 
the superior extremity of the femur to the patella, and situated to the 
outer side of the anterior rectus. 

Structure and Attachments—The fasciculi composing this muscle are 
intermixed with strong aponeurotic layers, and originate from the whole 
outer surface of the femur and the external half of its anterior face; they 
are directed forwards and downwards, to terminate either on the anterior 
rectus, or on the superior face and external side of the patella. 

Relations—Outwardly, with the fascia lata and superficial gluteus; 
inwardly, with the anterior rectus and the vastus internus, which is inti- 
mately confounded with it except towards the superior extremity of the 
femur, where the two muscles are distinctly separate; behind, with the 
femur and the long vastus. 

Action.—It is an extensor of the leg. 

C. Vasrus Inrernus (Figs. 131, 7; 187, 17)—This muscle is not very 
distinct from the preceding for the greater part of its extent, and forms with 
it a deep and wide channel, in which the anterior rectus is lodged. It isa 
repetition of the vastus externus in so far as its form, structure, extent, 
attachments, and action are concerned; but it possesses the following 
peculiarities : 

The fibres entering into its composition arise from the whole internal 
face and the inner half of the anterior face of the femur, and go to be 
inserted, some on the aponeurosis of the rectus, others on the internal 
patellar ligament, the corresponding side of the patella, and on the superior 
face of the same bone, in common with the vastus externus. 

Relations.—By its external face, it responds to the latter musele and 
the rectus; by its internal face, to the internal crural aponeurosis, the long 
adductor of the leg, the iliacus, pectineus, and to the long branch of the 
great adductor of the thigh. 


3. Anterior Gracilis, (Figs. 90,11; 181, 6.) 


Synonyms.—Gracilis anterius—Rigot. Ilio-femoral gracilis—Girard. (Crureus vel 
cruralis—Percivall.) 


A small cylindrical muscle, situated in front of the capsule of the coxo- 
femoral articulation, alongside the fibrous fasciculus that strengthens the 
anterior portion of this membranous ligament. : 

Attachments.—It originates from the ilium, very near, and to the outside 
of, the external branch of the anterior rectus; it afterwards insinuates itself 
between the two vasti, and terminates on the anterior aspect of the femur 
by aponeurotic fasciculi. 

Relations.—This muscle is included between the three portions of the 
triceps and the capsular ligament of the coxo-femoral articulation, to which 
it strongly adheres. 


286 THE MUSCLES. 


Action.—It appears to raise (or render tense) the capsular ligament 
during flexion of the femur. 


B. Posterior Crural Region. 


This region is constituted by three muscles situated behind the thigh. 
These are the long vastus, the semitendinosus, and the semimembranosus. 


Preparation.—Place the subject in the first position, allow one hind leg to lie 
unfastened, and incline the body to the corresponding side, leaving the other limb 
attached to the supporting bar, with the thigh slightly flexed to make these muscles 
tense. These preliminary arrangements being adopted, proceed in the flllowing 
manner: 1, Make w transverse incision through the short adductor of the thigh, and 
turn back the two portions to the right and left, so as to expose the whole of the 
semimembranosus, which is to be afterwards dissected from the semitendinosus and the 
great adductor of the thigh. 2. After removing the aponeurosis covering the long vastus 
and semitendinosus, the latter is to be dissected by circumscribing as carefully as 
possible its two superior insertions. 3. The long vastus is then to be prepared by 
isolating the two component portions, whose sacro-sciatic insertion is revealed by 
dividing the analogous insertion of the semitendinosus; after which, reflect the entire 
muscle in order to study its deep face, its femoral insertion, and its relations with the 
subjacent organs. 


1. Long Vastus. (Fig. 129, 7.) 


Synonyms.—Ischio-tibialis externus—Girard. The biceps femoris and part of the 
gluteus maximus of Man. (The biceps abductor femoris of Percivall. Anterior pubio- 
aschio-tibialis—Leyh.) 


Volume—Sttuation—Extent—Direction.—This muscle offers an enor- 
mous volume, as its name indicates; it is situated behind the thigh and 
the glutei muscles, and forming a curve with its concavity forwards, it 
extends from the sacral spine to the superior extremity of the leg. 

Form and Structure.— It is composed of two prismatic portions perfectly 
distinct from each other for nearly the whole of their extent, lying side by 
side, and designated as anterior and posterior. 

The anterior portion, the most considerable of the two, is very wide at 
its upper extremity, and singularly contracted below. It is covered, on the 
inferior half of its deep face, by a broad and strong tendinous band, which 
becomes aponeurotic in ascending towards the superior extremity of the 
muscle. Its component fibres are longest posteriorly, and all arise from the 
superior extremity to be inserted into the tendinous layer. 

The posterior portion, much shorter than the preceding, presents an 
inverse disposition, being contracted at its upper extremity and very 
wide below. Its muscular fibres are partly attached, by their superior 
extremities, to a longitudinal aponeurotic layer, which gives the muscle a 
penniform appearance ; they terminate, inferiorly, in a strong aponeurosis 
united to that of the fascia lata. 

Attachments.—The anterior portion arises, by its superior extremity, from 

the sacral spine, the sacro-ischiatic ligament, the aponeurosis enveloping the 
coccygeal muscles, and the ischial tuberosity. It terminates: 1, On the 
circular imprint situated behind the subtrochanterian crest, by a fibrous 
branch detached from the deep tendon; 2, On the anterior face of the 
patella, by the inferior extremity of that tendon, 
_ _The posterior portion commences on the spine and tuberosity of the 
ischium, where it joins the anterior division. Its terminal aponcurosis is 
spread over the tibial muscles to constitute the fascia of the leg, and is 
inserted into the tibial crest. 


MUSCLES OF THE POSTERIOR LIMBS. 287 


Relations.—The gluteal aponeurosis is prolonged over the extcrnal 
surface of the long vastus, becomes increased in thickness, and is more or less 
elastic ; it strongly adheres to this muscle, and superiorly gives attachment 
to a great number of its muscular fasciculi, Inwards, the long vastus 
responds: To the aponeurosis of the superficial gluteus, which separates it, 
for the most part, from the principal gluteus and the trochanter ; to the deep 
layer of the fascia lata, which isolates it from the external vastus; to the 
anterior face of the patella, over which it glides by means of a small 
synovial bursa, before becoming inserted; to the external muscles of the 
leg; to the sciatic nerves; to the great adductor of the thigh, and to the 
semimembranosus. Inferiorly, the semitendinosus is related to its internal 
face, and more superiorly, it is in contact with the posterior border of this 
muscle, whose sacro-ischiatic insertions it covers by its upper extremity. 

Action.—The two portions of the long vastus do not act in the same 
manner, and in this respect they are essentially distinct. The principal 
division, pulling the patella outwards and the femur backwards, is an 
abductor of the entire limb, and an extensor of the thigh ; while the posterior 
portion merely determines the flexion of the leg and the tension of the tibial 
aponeurosis.' 

If the leg be the fixed point, this muscle, in contracting, causes the 
pelvis to swing on the head of the femur, and in this way it plays an 
important part in rearing. 


2. Semitendinosus. (Figs. 129, 10; 130, 14.) 

Synonyms.—Ischio-tibialis medius or posticus—Girard. (Posterior sacro-ischio- 
tibialis—Leyh. Percivall describes this and the next muscle by the name of adductor 
tibialis.) 

Situation—LHatent—Direction.—This muscle is situated behind the pre- 
ceding, and, like it, extends from the sacral spine to the leg, describing a 
curve whose convexity is posterior. 

Volume—Form—Structure.—Less considerable than the long vastus, it 
is elongated from above to below, bifid at its superior extremity, thick and 
prismatic, but nevertheless compressed on both sides. Its muscular fibres 
are of a pale-red colour, are parallel to each other, and follow the general 
direction of the muscle ; they terminate, inferiorly, on an aponeurosis and on 
a flattened tendon. 

Attachments.—This muscle arises, above, by one of its branches from the 
sacral spine and the sacro-ischiatic ligament, in common with the long vastus ; 
by the other branch, which is the shortest, from the ischiatic tuberosity. 
Its inferior aponeurosis is confounded with that of the tibia; the tendon 
glides over the internal surface of the tibia, and is inserted into its anterior 
crest. 

Relations.—Its sacro-ischiatic branch is covered by the gluteal aponeurosis, 
and covers the long vastus. For the remainder of its extent, it responds: 
posteriorly, to that aponeurosis; anteriorly, to the sciatic nerves ; externally, 
to the long vastus and gastrocnemius ; internally, to the semimembranosus 
and the long adductor of the thigh. 

Action.—It is a flexor of the leg, and tensor of the tibial aponeurosis, 


1 If it were wished to establish a comparison between the nature of the action of the 
two portions of the long vastus, and their relations and attachments, their analogues in 
Man could be easily determined. ‘The anterior is undoubtedly a considerable portion of 
the gluteus maximus, prolonged to the patella; the posterior represents the biceps 
femoralis, 


288 THE MUSCLES. 


when its fixed point is above ; when the leg is fixed, it becomes one of the 
active agents in rearing 


3. Semimembranosus. (Figs. 129, 10; 180, 13.) 
Synonyms.—Ischio-tibialis internus—Girard. (Great ischio-femoralis—Leyh.) 


Situation— Volume—Extent—Direction._Situated within the semiten- 
dinosus, and shorter and thinner than it, the semimembranosus extends from 
the ischium to the inferior extremity of the femur, and follows an oblique 
direction downwards and forwards. 

Form—Structuwre—Elongated vertically, depressed on each side, pris- 
matic, thick at its anterior, and very thin at its posterior borders. It is also 
voluminous at its upper extremity, which has a small prolongation whose 
point ascends to the base of the tail; contracted, and terminated by a short 
tendon at its inferior extremity. Itis formed of thick muscular fasciculi, 
which all terminate, below, on the tendon. 

Attachments—Above: 1, To the aponeurosis of the coccygeal muscles, 
by the thin prolongation from its superior extremity; 2, To the ischiatic 
tuberosity, and on the inferior face of the ischium. Below, to the small 
eminence situated within the internal condyle of the femur. 

Relations—Inwards, with a very thin prolongation from the gluteal 
aponeurosis, and with the ischio-cavernous muscle and short adductor of the 
leg; outwards, with the semitendinosus, the long vastus, and the sciatic 
nerves; in front, with the great adductor of the thigh, which is so intimately 
united to it that some difficulty is experienced in separating their fibres. 

Action.—It is an adductor of the limb and an extensor of the thigh, when 
its fixed point is above; but when the femur is fixed, it is an auxiliary in 
rearing. 


C. Internal Crural Region. 


This region comprises nine muscles, applied in three superposed layers 
against the inner aspect of the thigh. These are: the long and short ad- 
ductor of the leg, forming the superficial layer; the pectineus and the small 
and great adductors of the thigh, forming the middle layer. Those of the 
deep layer—that is, the square crureus, external obturator, internal obturator, 
and gemini of the pelvis, are not all situated on the inner face of the femur, 
one of them being contained within the pelvic cavity. With these muscles, 
which do not present a very considerable volume, another region might be 
formed and designated the deep pelvi-crural, or coxo-femoral region. 


Preparation—1. Place the subject in the first position. 2. Prepare on one side the 
two muscles of the superficial layer, by removing the slight fibrous layer covering them, 
the internal crural aponeurosis, and the inferior parietes of the abdomen. 3. To expose, 
on the opposite side, the three muscles of the middle layer, cut through the two 
adductors of the leg, and turn them back to the right and left; separate the semi- 
membranosus from the great adductor of the thigh; it may be even useful, in order to 
study. the latter muscle, to remove the entire mass of the three ischio-tibial muscles. 
4. Dissect the small deep muscles on a separate piece, as shown in figures 90 and 181. 


1. Long Adductor of the Leg. (Fig. 180, 8.) 


Synonyms.—Sublumbo-tibialis—Gérard. (Sartorius—Percivall. Internal ilio-rotu- 
leus—Leyh.) 


Form—Situation—Direction.—This muscle is long, thin, and flattened, 
narrow at its inferior extremity, and situated at first within the abdominal. 


MUSCLES OF THE POSTERIOR LIMBS. 289 


cavity, at the entrance to the pelvis; afterwards, inside the thigh; it is 
oblique from above to below, behind to before, and within to without. 

Structure.—It is formed of parallel muscular fibres, and terminates, 
inferiorly, by an aponeurosis which is confounded with that of the short 
adductor. 

Attachments.—It originates, superiorly, from the inferior face of the iliac 
fascia near the tendon of the psoas parvus, and is inserted, by means of its 
terminal aponeurosis, not on the supero-intemal tuberosity of the tibia, 
but on the internal patellar ligament, in common with the short adductor. 

Relations.—It is covered by the crural aponeurosis and Poupart’s liga- 
ment, and covers the iliacus, psoas magnus, the anterior femoral nerve, and 
the internal vastus. Superiorly, its inner border forms the limit, with the 
pectineus and the anterior border of the short adductor, to a triangular space 
-occupied by the crural vessels; below this space the two adductors of the 
leg are closely adherent to each other. 

Action.—It adducts the leg, and flexes the femur. 


2. Short Adductor of the Leg. (Fig. 130, 9.) 
Synonyms.—Subpubio-tibialis—Girard. (Gractilis—Percivall. Pubio-tibialis—Leyh.) 


Form—Situation—Direction.—A large quadrilateral muscle, thin at its 
borders, situated inside the thigh in an oblique direction downwards and 
outwards. It forms the base of what is called the flat of the thigh. 

Structure—Formed of parallel muscular fibres, which extend from its 
superior to its inferior border, this muscle is tendinous at its origin, is 
covered by an albugineous layer, and terminates inferiorly in a wide 
aponeurosis. 

Attachments.—It originates, by the whole extent of its superior border, 
from the ischio-pubie symphysis, and is confounded with the muscle of the 
opposite side—origin. Its terminal aponeurosis, united with that of the 
long adductor, is inserted on the internal patellar ligament and the internal 
face of the tibia— movable insertion; posteriorly, it is confounded with the 
aponeurosis of the semitendinosus, and with it forms the tibial aponeurosis 
enveloping the tibial muscles. 

Relations.—Its superficial face is covered by a cellulo-fibrous layer, and 
by the saphena vessels and nerves. It covers, by its deep face, the pectineus, 
the adductors of the thigh, the semimembranosus’ and semitendinosus, and 
the 4nternal femoro-tibial ligament. It is traversed at its origin, and 
altogether in front, by a very large venous branch. 

Action.— Aun. adductor of the limb and a tensor of the tibial aponeu- 
Trosis. 


3. Pectineus. (Fig. 130, 11.) 


Synonyms.—Superpubio-femoralis—Girard. Its anterior branch corresponds to the 
pectineus, and the posterior to the middle adductor in Man. (Anterior pubio-femoralis 
—Leyh.) 

Situation—Direction—Form.—Situated beneath the preceding, in an 
oblique direction downwards, forwards, and outwards, this muscle is conoid, 
thick, and bifid at its superior extremity, contracted at its inferior extremity. 

Structure and Attachments.—Its fasciculi arise either from the anterior 
border and inferior surface of the pubis, or from the surface of the pubio- 
femoral ligament, which passes between its two branches—fixed insertion. 
They are enveloped, at their inferior extremity, by a tendinous cone, which 


290 THE MUSCLES. 


is attached, on the inner aspect of the femur, to the imprints surrounding 


the nutrient foramen—movable insertion. : 
" Action. —The pectineus is an adductor and flexor of the thigh, and also 


rotates it inwardly. 


MUSCLES OF THE SUBLUMBAR, PATELLAR, AND INTEKNAL CRURAL REGIONS. 

1, Psoas magnus; 1’, Its terminal tendon; 2, Psoas parvus; 3, Iliacus; 4, Its small 
internal portion; 5, Muscle of the fascia lata; 6, Rectus of the thigh; 7, Vastus 
internus; 8, Long adductor of the leg; 9, Short adductor of the leg; 11, Pecti- 
neus; 12, Great adductor of the thigh; 12’, Small adductor of the thigh; 13, 
Semimembranosus; 14, Semitendinosus.—a, Portion of the iliac fascia; B, 
Portion of the layer reflected from the aponeurosis of the abdominal great 
oblique, forming Poupart’s ligament; c, Pubic tendon of the abdominal muscles ; 
D, Origin of the pubio-femoral ligament. 


Relations.—Inwards, with the short adductor of the leg; outwards and 
forwards, with the femoral insertion of the psoas magnus and iliacus, the 
vastus internus, the crural vessels, and the long adductor of the leg; behind, 
with the small adductor of the thigh, and, near its superior extremity, with 
the external obturator. 


MUSCLES OF THE POSTERIOR LIMBS. 291 


Action.—This muscle is an adductor and flexor of the thigh, and more 
particularly a rotator inwards of the same ray. 


4. Small Adductor of the Thigh. (Figs. 180, 12; 187, 14.) 


Synonyms.—The anterior portion of the biceps femoralis of Bourgelat, and of the 
subpubio-femoralis of Girard! (Middle pubio-femoralis of Leyh. A portion of the 
adductores femoris of Percivall, and which he has named the adductor brevis.) 


Situation—Direction—This muscle is situated beneath the short ad- 
ductor of the leg, between the pectineus and the great adductor of the thigh, 
in an oblique direction downwards and outwards. 

Form—Structure.—lt is flat from before backwards, thick and narrow at 
its upper extremity, thin and wide inferiorly. Its muscular fibres are of a 
pale-red colour, nearly parallel to each other, and sometimes very indistinct 
—superficially, at least—from those belonging to the great adductor ; infe- 
riorly, they become aponeurotic. 

Attachments.—Above, to the inferior face of the pubis—ortgin ; below, 
to the roughened quadrilateral surface on the posterior aspect of the femur, 
in common with the short branch of the great adductor—termination. 

Relations.—Inwards, with the short adductor of the leg; outwards, with 
the obturator externus: in front, with the pectineus; behind, with the great 
adductor of the thigh. 


5. Great Adductor of the Thigh. (Figs. 180, 12.) 


Synonyms.—Posterior portion of the biceps femoralis of Bourgelat, and of the sub- 
pubio-femoralis of Girard. (The adductor longus, of Percivall. Posterior pubto-femoralis 
—Leyh.) 


Situation—Direction—The great adductor is situated beneath the 
preceding muscle, between the small adductor and the semimembranosus, 
proceeding obliquely downwards and outwards. 

Form—Structure.—It is a long, thick, prismatic muscle, depressed from 

" before to behind, terminating, inferiorly, by two branches of unequal length, 
and almost entirely composed of parallel muscular fibres, which are generally 
distinguished from the fasciculi of the small adductor by their deeper 
colour. 

Attachments.—Above, to the lower_face of the ischium and to the single 
tendinous band which attaches the two muscles of the flat of the thigh to 
the pelvic symphysis—origin. Below: 1, By its external branch, the 
thickest and shortest, to the quadrilateral scabrous surface on the posterior 
face of the femur, outside the small adductor; 2, By its internal branch, 
the longest and thinnest, to the supero-internal condyle of the femur, in 
common with the semimembranosus and the internal femoro-tibial hgament 
—termination. 

Relations.—Inwards, with the short adductor of the leg; behind, with 
the semimembranosus; in front, with the small adductor, the external 
obturator, and the inferior extremity of the square crural muscle. Its 
external border, thinner than the internal, partly covers the superior 


1 After mature deliberation, we have decided on describing as two muscles the biceps 
femoralis of Bourgelat, and to give to them the names of small and great adductors of 
the thigh, by which Bichat has designated the corresponding muscles in the lower 
extremity of Man. We have thought it our duty, in this instance, to follow the example 
given us by several German authors. 


292 THE MUSCLES. 


extremity of the latter muscle, and is separated from the sciatic nerves and 
the long vastus by an aponeurotic lamina. The crural vessels pass 
between its two branches, one of which, the internal, responds anteriorly and 
near its insertion to the internal vastus muscle. 

Action.—This muscle is an adductor and extensor, as well as a rotator 


outwards of the femoral ray. 
6. Square Crural. (Figs. 90, 14; 181, 10.) 


Synonyms.—The gracilis internus of Bourgelat, and the ischio-femoral gracilis of 


Girard. (Not described by Percivall. Small ischio-femoralis of Leyh. The quadratus 
Jemoris of Man.) 


Situation —Direction—Form—Structure.—Situated on the posterior face 
of the femur, between the great adductor and external obturator, and oblique 
downwards and outwards, the quadratus cruralis is a small band flattened 
from before to behind, and formed of parallel muscular fibres, slightly tendi- 
nous at their inferior extremity. 

Attachments.—Above, to the inferior surface of the ischium, in front of 
the ischiatic tuberosity—origin ; terminating, below, on the linear imprint 
on the posterior face of the femur, a little below the trochanter. 

Relations.—In front with the posterior face of the femur and external 
obturator. Behind, and inwardly, with the great adductor of the thigh. 
Outwards, with the sciatic nerves and the posterior gemellus of the pelvis. 

Action.—It is an extensor and adductor of the femur. In our opinion, 
its mode of attachment will not permit it to rotate this bone either inwards 
or outwards—at least in Solipeds. 


7. External Obturator. (Fig. 90, 18.) 


Synonym.—Subpubio-trochanterius externus—Girard. 


Form — Structure — Situation — Direction.— A short, thick muscle, 
flattened on both sides, triangular, fasciculated, fleshy and aponeurotic, 
very delicate in texture, and placed almost horizontally beneath the pelvis, 
at the margin of the oval foramen, which it appears destined to close, and 
from which it derives its name of obturator. 

Attachments.—1. To the inferior surface of the pubis and ischium, by 
the internal extremities of its fasciculi—fixed insertion; 2. To the 
trochanterian fossa, by the external extremities of these fasciculi—movable 
insertion. 

Relations Its inferior face is covered by the pectineus, the two 
adductors of the thigh, and the square crural; the superior covers the’ 
capsule of the hip-joint, and is related to the internal obturator. 

Actioy.—An adductor and rotator outwards of the thigh. 


8. Internal Obturator. (Figs. 90; 131.) 


Synonym.—Subpubio-trochanterius internus— Girard. 


Sttuation—This muscle is situated in the pelvic cavity, above the oval 
foramen, and is, consequently, opposite the external obturator. 

Form—Structure—Atiachments.— It is formed of two portions. One is 
very thin, and composed of slightly tendinous divergent muscular fasciculi, 
which arise from around the oval foramen, are directed outwards, and 
terminate in a tendon belonging to the other portion. The latter, elongated 
and penniform, is situated in the pelvis, and extends from the anterior angle 


MUSCLES OF THE POSTERIOR LIMBS. 293 


of the sacrum to the inferior extremity of the femur, following the direction 
of the ischiatic border of the ilium, into which it is inserted. The tendon 
to which it owes its penniform shape is inflected outwards, behind the supra- 
cotyloid crest or sciatic ridge, joins the gemelli, and terminates in the 
bottom of the trochanterian fossa. 

Relations.—In its intrapelvic portion, this muscle responds: outwards 


Fig. 131. = 


COCCYGEAL AND DEEP MUSCLES SURROUNDING THE COXO-FEMORAL ARTICULATION. 

1, Superior sacro-coccygeus ; 2, Lateral sacro-coccygeus; 3, Inferior sacro-coccygeus ; 
4, Ischio-coccygeus; 5, Small gluteus; 6, Anterior gracilis; 7, Tendon of the 
internal obturator; 8, 8, Gemelli of the pelvis; 9, Accessory fasciculus of the 
gemelli; 10, Quadratus cruralis; 11, Sacro-sciatic ligament; 12, Great sciatic 
notch; 13, Superior ilio-sacral ligament; 14, Inferior ilio-sacral ligament. 


and downwards, to the ilium, pubis, ischium, and external obturator; inwards 
and upwards, to the peritoneum, important vessels and nerves, and to a 
fibrous lamina that separates it from the bladder. In its extra-pelvic 
portion, it is in relation with: behind, the middle gluteal muscle and the 
sciatic nerves; in front, with the gemelli. A synovial sheath facilitates the 
gliding of its tendon in the groove in which it turns. 

Action—It is a rotator of the thigh outwards, and, coutrary to the 
opinion of the majority of authors, we believe it to produce abduction rather 
than adduction, if at any time its position allows it to execute either of these 
two movements. 

9. Gemelli of the Pelvis (Fig. 131, 8, 8, 9). 
Synonyms.—Ischio-trochanterius—Girard. (Gemini—Percivall. Bifemoro-caleaneus 
—Leyh.) 

The two small muscles which receive this name are far from presenting 
the same disposition in every subject; but we will describe that which 
appears to be the most frequent. Two little elongated muscular fasciculi 
are usually found, one above, the other below the tendon common to the two 
portions of the internal obturator. These two fasciculi (Fig. 131, 8, 8), 
arise from the external border of the ischium, follow the direction of the 
above-mentioned tendon, and are inserted into it by the external extremities 
of their fibres, exactly representing the gemelli of Man. But there is also 

22 


294 THE MUSCLES. 


a third (Fig. 131, 9), wide, flat, and often very voluminous, situated between 
the preceding and the external obturator ; it is attached, by its inner border, 
to the external border of the ischium, contracting intimate adhesions with the 
other two and with the tendon of the internal obturator, and becoming 
inserted by the whole extent of its external border into the digital fossa. 

Relations—The gemelli respond posteriorly, to the sciatic nerves; 
anteriorly, to the capsule of the hip-joint and the external obturator, 
through the medium of an adipose cushion. : 

Action.—-Like the preceding muscle, these rotate the thigh outwards, 
and perhaps tend to produce the abduction of this ray. 


DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE THIGH IN OTHER THAN SOLIPED 
ANIMALS. 


A, Anterior Crural Region. 


In the Ox, Sheep, and Goat, the muscle of the fascia lata is much wider than in 
Solipeds. In the Dog and Cat, this muscle offers in front a supernumerary fasciculus— 
a long thick band, confounded inwardly with tue long abductor of the leg, and. extending 
vertically from the external angle of the ilium to the patella, into which it is inserted by 
a short aponeurosis. res 

The anterior rectus of the thigh in the Dog and Sheep has only one originating branch, 

The anterior gracilis, the very small muscular fasciculus, is only present in Solipeds 
-. and Carnivores. 


B. Posterior Crural Region. 


Rumrnants.—In the Ox, Sheep, and Goat, the two portions of the long vastus are 
but little distinct from each other, and the anterior is reinforced superiorly by the 
superficial gluteus, which, with the long vastus, forms but one remarkably developed 
muscle. 

Fic. 132 The internal face of this muscle has 

Poste no point of attachment on the femur; it 

glides behind the trochanter by means of 
a vast mucous bursa, which is often the 
seat of pati ological alterations—synovial 
tumours which constitute the swellings or 
gout of the larger Ruminunts. Another 
synovial bursa, liable to the game 
maladies, covers the patellar tendon of the 
muscle on its passage over the external 
condyle of the femur, and facilitates its 
gliding on that bony eminence. Before 
Joining the external patellar ligament, 
this tendon shows a very thick, fibro- 
cartilaginous enlargement, and receives 
some of the fibres of the external vastus. 

Another arrangement in this muscle, 
which it is essential to recognise in a 
surgical point of view, is the union of the 
anterior border of the long vastus of the 
Ox with the fascia lata, whose two 
lamellz comprise that muscle between 
them, and closely adhere to each of its 
jJaces. It very frequently happens that 
in emaciated beasts, this fascia is ruptured 
at the trochanter, and the latter, instead 
of gliding on the inner face of the long 
vastus, slips before its anterior border to 
pass through the solution of continuity, 
where it is fixed so firmly that it is some- 
1, Middle gluteal; 2, 2, Long vastus; anterior times necessary to cut across the fibres of 

portion; 3, Ditto, posterior portion; 4, Semi- the long vastus in order to give the limb 
tendinosus; 5, Muscle of the fascia lata, liberty of movement, 


SUPERFICIAL MUSCLES OF THE CROUP AND 
THIGH IN THE COW. 


MUSCLES OF THE POSTERIOR LIMBS, 295 


The semitendinosus has no sacral prolongation ; it arises only from the ischium. 

The semimembranosus is divided, inferiorly, into two branches: one, very thick 
passes to the femur; the other, much smaller, terminates by a tendon which ig in- 
sinuated beneath the internal lateral ligament of the femoro-tibial articulation, to gain 
the superior extremity of the tibia. 

Carnivora.—lIn these animals it is somewhat difficult to isolate the two portions of 
the long vastus from cach other. The anterior only proceeds from the ischium. Infe- 
riorly, they terminate in commun by an aponeurosis which passes to the tibial crest and 
the «xternal patellar ligament. 

The semitendinosus and semimembranosus comport themselves as in the smaller 
Rumiuants. 


C. Internal Crural Region. 


Remrinants.—The long adductor of the leg in the Ox and Sheep is traversed, near its 
origin, by the femoral artery. Tlie pectineus of the Oz, single at its upper extremity, is 
divided into two branches at its inferior -xtremity. One of these branches, tlin and 
pale, is prolonged to ncar the internal condyle of the femur, while the principal stops, as 
in the Horse, on the posterior face of the bone. 

The small adductor of the thigh is scarcely distinct from the great adductor. The 
latter is undivided at its inferior extremity, which stops at the posterior face of the 
femur without going to the inner condyle of that bone. 

The internal obturator has no upper portion ; it is united to the external obturator in 
passing through the oval foramen. 

Pic.—lIn this animal, the internal crural muscles offer somewhat the same disposition 
as in the Ox. 

Cannivora.—In the Dog and Cat, the long adductor of the leg arises from the 
external anzle of the ilium, and by its muscular portion is prolonged to the inner face of 
the tibia. The short adductor is much thinner and narrower than in the other animals. 
The small adductor of the thigh isa little, dist nctly-isolated, muscle, which begins on the 
inferior face of the pubis, and terminates at the posterior face of the feraur, below the 
square crural. The great adductor is, on the contrary, a wide, thick, undivided muscle, 
attached to nearly the whole extent of the linea aspera of the femur. 

There is nothing particular to note with regurd to the square crural and the 
obturators ; the gemellé of the pelvis are always composed of two small, distinctly-isolated, 
fasciculi, which comport themselves as in Man. 


COMPARISON OF THE MUSCLES OF MAN’S THIGH WITH THOSE OF THE THIGH OF ANIMALS. 
A, Anterior Muscles. 


The anterior gracilis is not found in Man ; nevertheless, there are reckoned three 
anterior muscles of the thigh, as the sarfordus, which corresponds to the long adductor 
of the leg of animals, is included in this region. 

The surtorius is a very long muscle, whose width at most is about two fingers’ breadth. 
It is attached above, not to the lumbo-iliac aponeurosis, but to the anterior and superior 
iliac spine : it is afterwards directed downwards and inwards, to pass round the internal 
condyle of the femur, and terminate by an expanding tendon at the crest of the tibia. 

The tensor of the fascia lata (tensor vagine femoris) shows the same general dis- 
position observed in animals. It is the same with the femoral triceps. The anterior 
rectus arises hy two tendinous branclies: one is detached from the anterior and inferior 
iliac spine; the other from the brim of the cotyloid cavity. 


B. Muscles of the Posterior Region. 


These are three in number: the femoral or crural biceps, semitendinosus, and 
semimembranosus. : ; Ff : 

The femoral biceps is represented in Solipeds by the posterior portion of the long 
vastus, It is an elongated muscle arising by two heads: the long hea:l comes from the 
ischiatic tuberosity ; the shortest from the middle of the linea aspera, After their 
union, these two heads give rise to a tendon which is fixed into the head of the fibula, 
and sends an expansion over the tibial aponenrosis. . corpb an 

The semilendinosus arises in common with the long head of the biceps; its inferior 
tendon is reflected beneath the internal tuberosity of the tibia, to be fixed into the crest 


296 THE MUSCLES. 


of that bone. This tendon, with that of the sartorius, forms the aponeurotic expansion 


called the goose’s foot. . : 

The ae is voluminous in its lower portion, and arises, like the other 
two, from the tuberosity of the ischium; its fibres pass to a tendon which, on reaching 
the inner side of the knee, terminates in the three pieces composing that articulation (see 


fig, 134). 


Fig. 134. 


MUSCLES OF THE ANTERIOR FEMORAL 
REGION IN MAN. 


1, Crest of the ilium; 2, Its antero-superior 

~. spinous process; 3, Gluteus medius; 4, 
Tensor vagine femoris; 5, Sartorius; 6, 
Rectus; 7, Vastus externus; 8, Vastus 
internus; 9, Patella; 10, Hiacus internus ; 
11, Psoas magnus; 12, Pectineus; 13, 
Adductor longus; 14, Portion of adductor 
magnus; 15, Gracilis. 


MUSCLES OF THE POSTERIOR FEMORAL AND 
GLUTEAL REGION IN MAN. 


1, Gluteus medius; 2, Gluteus maximus; 3, 
Vastus externus, covered by fascia lata; 
4, Long head of biceps; 5, Short head; 6, 
Semitendinosus; 7, 7, Semimembrano- 
sus; 8, Gracilis; 9, Portion of inner 
border of adductor magnus; 10, Edge of 
sartorius ; 11, Popliteal space ; 12, Gastroc- 
nemius, with its two heads. 


C. Muscles of the Internal Region. 


In books on human anatomy, these muscles are sometimes designated, from their 
action, by the generic name of adductors. They comprise: the internal rectus, pectineus, 
first or middle adductor, second or small adductor, and third or great adductor. The 
square crural, the obturators, and the gemelli are described among the posterior muscles 
of the pelvis. They will, however, be briefly alluded to here. 

The internal rectus corresponds to the short adductor of the leg of animals. It is 
a thin muscle, bordering the inner. side of the thigh. It is attached, above, to the 
symphysis pubis; below, to the crest of the tibia, in common with the sartorius tendon. 


MUSCLES OF THE POSTERIOR LIMBS. 297 


The pectineus repeats the anterior branch of the pectineus of the Horse. It is inserted, 
below, into the internal bifurcation of the linea aspera of the femur. 

The first adductor corresponds to the posterior branch of the pectineus of Solipeds, 
It is represented by a voluminous muscular mass, which arises from the spine of the 
pubis and terminates on the middle third of the linea aspera. 

‘The second or small adductor corresponds to the muscle of the same name in animals. 
It is inserti.d into the same points as the preceding. 

The third or great adductor is attanhed, above, to the ischiatic tuberosity and to the 
whole of the lower branch of the ischium by aponeurotic fibres. It afterwards divides 
into two branches: the external branch, entirely muscular, is fixed into the entire 
interspace of the linea aspera; the internal branch gives rise to a tendon which goes to 
the inner condyle of the femur. Between these two branches is found, as in the Horse, 
the ring of the adductors, in which pass the large vessels of the thigh. 

The square crural of Man is nearly horizontal, as it is attached, inwardly, to the 
external border of the ischium, and outwardly, between the great and small trochanters. 

The internal obturator and gemelli resemble those of the Dog. 


MUSCLES OF THE LEG. 


These muscles, nine in number, are grouped around the two principal 
bones of the leg, so as almost to completely envelop them, leaving only the 
internal face of the tibia uncovered. Like those of the fore-arm, they form 
two particular regions: an anterior and a posterior ; and they are sheathed in 
common by the tibial aponeurosis, a very solid fibrous covering which in every 
respect corresponds to the antibrachial aponeurosis. 


TIBIAL APONEUROSIS. 


This aponeurosis is formed of several superposed layers which are 
intjmately united, and receives, superiorly, the insertion of the long vastus, 
the semitendinosus, and the short adductor of the leg, which may be con- 
sidered as its tensor muscles. 

It is continued, inferiorly, over the tarsus and the metatarsal region, in 
becoming singularly attenuated, and in covering the fibrous bands which 
bind and retain the anterior tibial muscles in the bend of the hock. Its 
external surface is separated from the skin by a very thin cellulo-fibrous 
expansion ; its internal face furnishes special and very firm sheaths around 
the majority of the tibial muscles. 

The tibial aponeurosis is attached to the internal surface and crest of the 
tibia, as well as to the summit of the calcis. The latter attachment takes place 
by a thick fibrous band, whose singular and complicated disposition has not 
yet been exactly described. It is situated in front of the tendon of the 
hock, or between that tendon and the deep layer of the posterior tibial 
muscles. By its borders, it is continuous with the tibial aponeurosis or 
fascia. Superiorly, it adheres most intimately to the perforatus tendon, near 
the point where the latter originates ; there it sends off a thick fasciculus which 
descends to the gastrocnemius tendon. Below this, it appears to divide into 
two branches, an external and internal, which are united to the calcanean cap 
of the perforatus tendon, and are attached to the sides of the calcis in such a 
manner, that near its insertion the gastrocnemius tendon is found to be 
enveloped by a complete fibrous sheath, formed partly by the perforatus 
tendon and partly by the band just described. This latter, therefore, con- 
stitutes a strengthening apparatus for the tendon of the hock: a structure 
noticed by Girard, who made it a branch of insertion of the semitendinosus ; 
and not without reason, perhaps, because it arises from the tibial aponeurosis, 
which, in part at least, is itself derived from the semitendinosus muscle. 


Preparation of the Muscles of the Leg.—Separate the limb from the trunk by sawing 


298 THE MUSCLES. 


through the femur at its middle. Dissect the insertions of the long vastus, the short 
adductor of the leg, and the semitendinosus, to observe the continuity of ti ese muscles 
with the tibial aponeurosis; study the insertions of this aponeurosis, particularly that 
which it has on the summit of the calcis. To expose the muscles, remove their 
aponeurotic envelope, leaving, however, the band it forms in front of the tenilon of the 
hock, as well as the bands which retain the tendons. Remove the hoof in the manner 
already indicated for the anterior extremity, and, finally, separate the muscles from one 
apother—an operation so very simple as not to require any special directions, 


A. Anterior Tibial Region. 


This is composed of three muscles: the flexor of the metatarsus, the 
anterior extensor, and the lateral extensor of the phalanges. The first is 
deep-seated, the other two are superficial. 


1. Anterior Extensor of the Phalanges. (Fig. 135, 20.) 


Synonyms.—Femoro-prephalangeus— Girard. The extensor longus digitorum pedis 
of Man. (Extensor pedis—Percivull.) 


Situation—Direction—Eatent.—This muscle, situated in front of the 
leg and foot, follows the direction of these two rays for their whole extent, 

Form—Structure.—It is formed of a muscular body and a tendon. The 
first is fusiform, depressed from before to behind, aponeurotic at its superficies 
in its superior moiety, and tendinous internally in its inferior moiety. The 
tendon, at first round, then flat, commences a little above the inferior fourth 
of the tibia, and reaches the anterior face of the principal metatarsus, where 
it receives the pedal (extensor brevis digitorum) muscle, the tendon of the 
lateral extensor, and a funicular prolongation of the tibial aponeurosis. It 
afterwards descends on the fetlock, where it comports itself exactly as the 
corresponding tendon in the anterior extremity. (See the anterior extensor 
of the phalanges in the fore-limb, page 262.) 

Aittachments.—Above, in the digital fossa placed between the trochlea and 
external condyle of the femur, through the medium of the tendinous portion 
of the flexor of the metatarsus—fixed insertion. Below, on the capsular liga- 
ment of the metatarso-phalangeal articulation, the anterior face of the two 
first phalanges, and the pyramidal eminence of the os pedis. 

Relations.—The muscular portion responds: outwardly, with the tibial 
aponeurosis; inwardly, to the flexor of the metatarsus; posteriorly, to the 
lateral extensor of the phalanges. The tendon successively covers: the 
anterior aspect of the tibia, the anterior capsular ligament of the tarsus, the 
pedal muscle, the anterior face of the principal metatarsal, the articulation of 
the fetlock, and the two first phalanges. It is covered by the tibial aponeu- 
rosis, and by three annular fibrous bands destined to maintain the tendon in 
the bend of the hock. One of these bands, the superior, is fixed by its ex- 
tremities to the tibia, a little above the tibio-tarsal articulation ; it is common 
to the muscle we are describing, and to the flexor of the metatarsus. The 
middle band, attached to the cuboid branch of the latter muscle and the 
inferior extremity of the calcis, is exclusively intended for the anterior ex- 
tensor of the phalanges. The inferior maintains the two extensors against 
the superior extremity of the principal metatarsal. 

Action —This muscle extends the digit and flexes the entire foot. 


2. Lateral Extensor of the Phalanges. (Fig. 185, 28.) 


Synonyms,— Peroneo-prephalangeus—Girard. The peroneus brevis of Man. (Peroneus 
Pereivall. Tibio-prephalangeus—Leyh.) 


Situation—Form—Structure—Extent—Direction—This muscle, situated 


*MUSCLES OF THE POSTERIOR LIMBS. 299 


on the external side of the leg, between the di 
: y preceding and the deep ff 
the phalanges, is composed of a muscular portion and a tendon, The fiat 
2 


Fig. 135, 


EXTERNAL DEEP MUSCLES OF RIGHT POSTERIOR LIMB. 

1, Crest of the ilium; 2, Inferior sacro-sciatic ligament ; 3, Sacro-ischiatic ligament ; 
4, Obturator ligament; 5, Tuberosity of the ischium ; 6, Anterior tuberosity of 
the ilium; 7, Small gluteus, or gluteus internus; 8, Its insertion into the great 
trochanter, 9; 10, Iliacus, or iliac psoas; 11, Vastus externus; 12, Rectus; 13, 
Great sciatic nerve; 14, Gracilis; 15, Sartorius; 16, Patella; 17, Lateral liga- 
ment; 18, Oblique flexor of the phalanges, or flexor pedis accessorius; 19, Pero- 
neus; 20, Extensor pedis; 21, Solearis, or plantaris; 22, Gastrocnemius externus ; 
23, Flexor pedis; 24, Tendon of oblique flexor of the phalanges; 25, Perforatus 
tendon; 26, Lateral ligament of gastrocnemius; 27, 28, Annular ligament; 29, 
Tendon of lateral extensor of the phalanges, or peroneus; 30, External rudi- 


mentary metatarsal bone. 


elongated, prismatic, and slightly penniform, extends in the direction of the 
leg, from the superior extremity of that region to beyond its inferior extre- 
mity. The tendon succeeds the lower end of the muscular portion, and 
traverses the groove on the middle of the infero-external tuberosity of the 


300 THE MUSCLES. * 


tibia, passing to the external side of the tarsus, where it is enclosed in a very 
firm sheath, and is inflected forwards to become united to the tendon of the 
anterior extensor, near the middle of the metatarsal region. 

Attachments.—The lateral extensor is attached, by the superior extremity 
of its muscular fibres, to the external femoro-tibial ligament, to the whole 
extent of the fibula, and to the fibrous partition which separates this muscle 
from the perforans—origin. It terminates in the tendon of the anterior 
extensor. 

Relations—Its muscular body is enveloped in a special containing 
aponeurosis, which separates it, in front, from the anterior extensor, and 
behind from the perforans. The tendon covers the tibia, and margins the 
external and superficial ligament of the tibio-tarsal articulation ; which liga- 
ment supplies a fibrous ring destined for the formation of its reflected sheath. 
A vaginal synovial membrane facilitates its motion in the interior of this 
sheath. 

Action.—It acts like the preceding. 


3. Flexor of the Metatarsus. (Fig. 136.) 


Synonyms.—Tibio-premetatarsus—Girard. Its muscular portion represents the 
tibialis anticus of anthropotowists. .( Flexor Metatarsi—Percivall.) 


This muscle is situated beneath the anterior extensor of the phalanges, on 
che external surface of the tibia, and is composed of two distinct portions: one 
: muscular, the other aponeurotic, not united from end to 
end, but placed parallel one before the other. 

A. Tzwprnovus Portion (Fig. 136, 1).— Cowrse—Attach- 
ments.—This is a strong, pearly-white cord, comprised 
between the muscular portion and the anterior extensor of 
the phalanges. It commences at the inferior extremity of 
the femur, in the fossa excavated between the trochlea 
and the external condyle; it afterwards passes through the 
superior groove of the tibia, where it is enveloped by 
a prolongation from one of the synovial membranes of 
the femoro-tibial articulation, giving origin, below this 
groove, to the muscular fibres of the anterior extensor 
of the phalanges. Lower, it receives some of the fasciculi 
from the muscular portion, to which it sends in exchange 
several aponeurotic layers; it passes under the superior 
annular band in front of the hock, in company with the 
anterior extensor, and reaches the level of the trochlea of 
the astragalus, where it is perforated to form a ring for 
the passage of the inferior extremity of the muscular 
portion. It finally terminates in two branches: a large 
one, inserted in front of the superior extremity of the 
principal metatarsus (Fig. 136, 4); the other, narrower, 
deviates outwards to reach the anterior surface of the 
cuboid bone (Fig. 136, 3). 


1, Tendinous portion; 2, Its attachment to the femur; 3, Its 
cuboid branch ; 4, Its metatarsal branch; 5, Muscular portion; 
6, Its succeeding tendon passing through the ving of the tendi- 
FLEXOR MUSCLE OF nous portion; 7, Cuneiform portion of this tendon; 8, Its meta- 
THE METATARSUS. tarsal branch; 9, Anterior extensor of the phalanges drawn 

outwards by a hook.—a, Lateral extensor; B, Tibial insertion of the middle patellar 

ligament ; c, Femoral trochlea, 


it Fig, 136. 
la’ 

aft. 
cor 
of 


MUSCLES OF THE POSTERIOR LIMBS. 301 


_ Relations—In front, with the anterior extensor of the phalanges; 
behind, with the muscular portion, and the anterior capsular ligament of 
the tarsus. 

Action.—This tendon enjoys the curious property of bending the hock 
by an action altogether mechanical, whenever flexion of the superior bones 
of the limb takes place. It is, therefore, a conducting cord, whose office it 
is to regulate the movements of flexion in the hock, and conform them to 
those taking place in the other joints, without requiring the intervention of 
an active agency for the execution of these movements. 

Another function has also been attributed to it: that of passively opposing 
the flexion of the femur on the tibia while the animal is standing, and in 
this way serving as an adjunct to the muscular powers which support the 
weight of the body. But, in our opinion, this is incorrect; as in order that 
it may perform this task, it would be necessary for the foot to be maintained 
in a fixed position by the contraction of its extensor muscles. But these 
muscles are really the gastrocnemii, which have their origin behind the 
femur, and which undoubtedly tend to flex that bone on the tibia—that is, to 
determine the movement it is supposed to prevent. And experiment clearly 
shows that we are justified in this opinion ; for division of this tendinous cord 
in the living animal does not interfere in the slightest degree with its 
natural attitude, either when standing at liberty or when forced to stand.t 

B. Muscutar Portion. —Situation—Form—Structure.—Situated between 
the tendinous cord and the tibia, this portion is elongated from above to 
below, very wide at its superior part and narrow inferiorly, where it termi- 
nates in a bifid tendon. 

Attachments.—It originates, by the upper extremity of its muscular fibres, 
from the tibia, below and on the sides of the groove through which the 
tendinous cord passes; its most superficial fibres are even attached to the 
aponeurotic sheath which envelops the lateral extensor. Its terminal tendon 
(Fig. 136, 6) traverses the annular ligament which the tendinous portion 
forms at its inferior extremity, and becomes inserted, by one of its branches, 


1 J. F. Meckel rightly considers this tendinous cord, not as a portion of the anterior 
tibial, but as a dependency of the extensor longus digitorum. It would be wrong, 
however, to describe it apart from the anterior tibial, properly so-called—that is, the 
muscular portion of our flexor of the metatarsus, the two being, in their action, 
essentially one. 

Is there anything in the human species analogous to this fibrous cord? After much 

. hesitation, we answer in the affirmative, and give it as our opinion that this tendon repre- 
sents the anterior peroneus (peroneus tertius) in Man. These are our reasons for making 
this assertion, hazardous as it certainly is at first sight: In Man, the peroneus tertius 
cannot always be easily distinguished from the extensor longus digitorum; so that these 
two muscles may be regarded as a single one until reaching the instep, where it ex- 
tends to the phalanges of the toes on the one part, and the metatarsus on the other. 
Precisely the same arrangement is found in Solipeds; the single muscle divides into two 
fasciculi, one for the digital region (anterior extensor of the phalanges), the other to the 
metatarsal region (tendinous cord of our flexor metatars?). ‘This tendinous cord, then, 
exactly represents the fasciculus of the long common extensor of the toes (in Man), which 
goes to the metatarsus, and is designated the peroneus tertius. ; 

But to this it may be said: your peroneus tertius in the Horse hag no relation whatever 
to the peroneus, and does not this prove that you are in error? No; for if this muscle 
is attached to the fibula in Man, it is because the principal muscle on which it depends 
is inserted there itself. But as the anterior extensor of the phalanges of the Horse— 
that is, the common extensor of the toes—is not inserted into the fibula, and has no 
connection with it in any way, its metatarsal fasciculus, or rather its tendinous cord or 
peroneus tertius, ought to be absolutely in the same condition. We repeat, however, 
that this opinion may be, perhaps, a little hazardous; and we give it with reserve, 
though we have some reasons for sonsidering it to be correct, 


302 THE MUSCLES. 


in front of the superior extremity of the principal metatarsal bone, along 
with the analogous branch of the tendinous division (Fig. 136, 8). The 
other ramification is directed to the inside of the tarsus, to be attached to 
the second cuneiform bone (Fig. 136, 7). 

Relations.—In front, with the tendinous portion of the muscle and the 
anterior extensor of the phalanges; behind, with the external face of the 
tibia. The tendon, after traversing the annular ligament of the cord, covers 
the metatarsal branch of the latter, and is in turn covered by the anterior 


extensor. : : 
Action.—It is an active agent in flexing the foot on the leg. 


B. Posterior Tibial Region. 


This region comprises six muscles, which are arranged in two super- 
posed layers behind the tibia. The superficial layer is formed by the 
gastrocnemit, soleus, and the superficial flecor of the phalanges. The deep 
layer is composed of the popliteus, the deep flecor, and the oblique flexor of 
the phalanges. 


1. Gastrocnemit, or Gemelli of the Tibia. (Figs. 185, 22; 187, 20.) 
Synonyms.— Bifemoro-calcaneus—Girard, (Gastrocnemius externus—Perctvall.) 


Situation—Composition—LHatent.—The gemelli of the leg,,situated behind 
the femoro-tibial articulation, below the ischio-tibial muscles, constitute 
two thick fleshy fasciculi distinct from one another only at their superior 
extremity, being confounded for the remainder of their extent, and continued 
inferiorly by a single tendon which extends to the point of the calcis. 

Form—Structure.—Both of these muscular masses are flattened on both 
sides, thick in the middle, narrow at the extremities, »nd intersected by 
strong tendinous bands. By their union they form a wide channel, open 
in front, which embraces the femoro-tibial articulation and the muscles of 
the deep layer. , 

The tendon, at first fasciculated, then single and funicular, receives that of 
the soleus, and is reinforced by a fasciculus from the fibrous band annexed in 
front to the tendon of the perforatus (see the description of the tibial aponeu- 
rosis, p. 297). An aponeurotic lamina which covers the external gemellus, 
is continued downwards, partly with this fibrous band, and partly with the 
tendon of the muscle itself. 

Attachments.—The external gemellus arises on the femur, from the 
rugged lip which margins in front the supracondyloid fossa; the internal, 
from the collection of tubercles which constitutes the crest of the same 
name. The terminal tendon of the two bellies is fixed on the summit of 
the calcis, not at its anterior part, but posteriorly, this being lubricated by a 
vesicular synovial membrane forming a gliding surface on which the tendon 
rests during extreme flexion of the foot (Fig. 67, 1). 

Relations—The gemelli respond: by their superficial face, to the three 
ischio-tibial muscles, and the tibial aponeurosis; by their deep face, to 
the perforatus, which contracts intimate adhesions with the vastus 
externus, to the posterior ligament of the femoro-tibial articulation, the 
popliteal muscle and vessels, the great sciatic nerve, and the oblique and deep 
flexor muscles of the phalanges. The tendon lies beside that of the per- 
foratus, which is twisted around and completely envelopes it at its inferior 
extremity, in common with the fibrous band from the tibial aponeurosis. 
The two tendons form what is usually termed the tendon of the hock, or 
tendon of Achilles. 


MUSCLES OF THE POSTERIOR LIMBS. 303 


Action.—The gastrocnemii extend the foot u ibi 
pon the tibia. They act 
a lever of the first order when the limb is raised from the eine, and = 


Fig. 137. 


MUSCLES ON INNER ASPECT OF LEFT POSTERIOR LIMB. 

1, Crest of the ilium; 2, Section through it; 3, Sacro-ischiatic ligament; 4, Pyri- 
formis ; 5, Posterior portion of sacro-ischiatic ligament; 6, Tuberosity of ischium ; 
7, Anterior portion of ischium, sawn through; 8, Pubis; 9, Obturator foramen ; 
10, External iliac artery and vein, 11; 12, Obturator artery and vein; the figures 
are placed on the internal obturator muscle; 13, Long adductor of the leg, or 
sartorius; 14, Small adductor of the thigh, or adductor brevis; 15, Short 
adductor of the leg, or gracilis; 16, Rectus of the thigh; 17, Vastus internus ;’ 
18, Patella, with insertion of rectus; 19, Upper .extremity of tibia; 20, Gas- 
trocnemius; 21, Popliteus; 22, Oblique flexor of the phalanges, or flexor pedis 
accessorius, with its tendon, 34; 23, Perforans muscle, with its tendon, 35; 24, 
Flexor metatarsi; 25, Anterior extensor of the phalanges, or extensor pedis; 
26, Annular ligament; 27, Tendon of flexor metatarsi, and its cunean branch, 
28; 29, Tendon of superficial flexor or internal gastrocnemius; 30, Tendon of 
gemelli or external gastrocnemius; 31, Os calcis; 32, Astragalus; 33, Perforatus 
tendon; 34, Tendon of oblique flexor joining the perforans tendon, 35; 36, Latge 
metatarsal bone; 37, Extensor pedis tendon; 38, Terminal knob of small meta- 


tarsal bone, 


304 THE MUSCLES. 


one of the second order when the hoof is placed on the ground. They 
maintain the tibio-tarsal angle while the animal is standing, and in pro- 
gression give to the hock that spring which carries the body forward. 


2. Soleus (or Solearis). (Fig. 138, 21.) 


Synonyins.—Bourgelat and his successors have erroneously assimilated it to the 
plantaris of Man. In regarding this little muscle as the soleus, we conform to the 
well-founded opinion of Cuvier. It is the peroneo-calcaneus of Girard. (Plantaris— 


Percivall.) 


Form—Situation—This is a thin, long, and riband-shaped rudimentary 
muscle, situated at the external side of the leg, between the tibial aponeu- 
rosis and the muscular portion of the perforans. 

Attachments.—It is fixed, by its superior extremity, behind the supero- 
external tuberosity of the tibia; and terminates, inferiorly, by a small tendon, 
which jos that of the gastrocnemii. 

Action.—It is a feeble auxiliary of the last-named muscles. 


8. Superficial Fleaor of the Phalanges, or Perforatus. (Figs. 185, 25; 187, 30.) 


Synonyms.—Femoro-phalangeus—Girard. It is represented in Man by the plantaris 
and flexor brevis digitorum, or perforatus. These two, in the majority of mammalia, 
are united from end to end to form w single muscle. (The gastrocnemius internus of 
Percivall.) 


Form—Structure.—The perforatus of the posterior limb is only repre- 
sented, in reality, by a long tendinous cord, that is somewhat muscular, 
slightly thickened, and fusiform in its upper fifth, which forms the body 
of the muscle. 

Origin—Direction and Relations—Termination.—It originates, by its 
upper extremity, in the supercondyloid fossa, descends between the two 
portions of the gastrocnemii, to the external of which it is intimately related, 
ou the posterior face of the femoro-tibial articulation and the three posterior 
deep tibial muscles. On reaching the inferior extremities of the muscular 
bellies of the gastrocnemii, it becomes exclusively tendinous, and is directly 
united to the fibrous band which reinforces the tendon of the hock. It 
afterwards disengages itself below the gastrocnemius, and is placed at the 
internal side of its tendon, then on its posterior surface, and in this position 
gains the summit of the os calcis. There it becomes widened to form 
a fibrous cap, which is covered by a large vesicular synovial membrane; 
it is moulded to the posterior region of this bony eminence, which it com- 
pletely envelops in order to be fixed on its lateral portions, and is united 
to the caleanean band from tke tibial aponeurosis. " From this point the 
tendon of the perforatus is prolonged behind that of the perforans to 
the posterior face of the second phalanx, where it terminates in exactly the 
same manner as the analogous muscle of the anterior limb. 

Action.—It flexes the second phalanx on the first, and this on the meta- 
carpus. It also concurs in the extension of the foot. Its principal office, 
however, is that of a mechanical stay, destined to sustain the equilibrium of 
the body while the animal is in a standing posture, by preventing the 
diminution of the angle of the hock and that of the fetlock, the femur being 
fixed by the contraction of the crural triceps and the gluteal muscles. 


‘ 4, Popliteus. (Fig. 187, 21.) 


a, hier Ths abductor tibialis of Bourgelat, and femoro-tibialis obliquus of 
‘tirard. 


' MUSCLES OF THE POSTERIOR LIMBS. 305 


_ Situation — Direction — Form— Structure—Situated behind the tibia, 
below the femoro-tibial articulation, this muscle is oblique downwards and 
inwards, short and triangular, tendinous at its supero-external angle, and ~ 
formed, for the remainder of its extent, of divergent fleshy fibres, the longest 
of which are the most inferior. 

Attachments.—1. In the lowest of the two fosse excavated on the outside 
of the external condyle of the femur, by its tendon—origin. 2. On the 
supero-posterior triangular surface of the body of the tibia, by the inferior 
extremity of its muscular fibres—termination. 

Relations.—Posteriorly, with the gastrocnemii and the perforatus. In 
front, with the posterior ligament of the femoro-tibial articulation, and the 
popliteal vessels. Outwards, with the oblique and deep flexors of the 
phalanges. Inwards, with the semitendinosus and tibial aponeurosis. The 
tendon, concealed at its origin beneath the external femoro-tibial ligament, 
glides, by its deep face, over the contour of the external semilunar cartilage 
and the posterior portion of the external facet on the tibia. 

Action.—It flexes the tibia, and gives it a slight rotatory movement out- 
wards. 


5. Deep Flexor of the Phalanges or Perforans. (Figs. 185, 23 ; 187, 23.) 


Synonyms.—Tibio-phalangeus—Girard. The flexor perforans and flexor longus 
pollicis pedis of Man. (Fleaor pedis—Percivall. Great tibio-phulangeus—Leyh.) 


Extent—Situation—Direction—Composition.—Extending from the supe- 
rior extremity of the leg to the third phalans, and situated behind the tibia 
and foot, whose direction it follows, this muscle is compused of a muscular 
body and a tendon. 

Form, Structure, and Attachments of the muscular portion.—This is thick 
and prismatic, and incompletely divided into two portions—an internal,! 
and an external,’ which is the most voluminous. It is attached: 1, To the 
posterior face of the tibia, on the linear imprints which occupy the inferior 
triangular surface; 2, To the supero-external tuberosity of the same bone; 
3, To the peroneus; 4, To the interosseous ligament uniting that bone to 
the tibia. 

Direction and Attachments of the tendon—The tendon commences above 
the inferior extremity of the tibia, where it is most usually double, each 
muscular portion being succeeded by a tendinous cord whose volume is in 
harmony with the size of the muscle from which it proceeds. The single 
tendon resulting from tle union of these two primary ones enters the groove 
formed by the inner face of the os calcis, where it is retained by a fibrous 
arch which transforms this channel into a perfect sheath, designated the 
tarsal sheath; it glides in the interior of this canal by means of a very 
extensive vaginal synovial membrane, which extends upwards on the 
posterior ligament of the tibio-tarsal articulation. and is prolonged inferiorly 
to the middle third of the metatarsal region. The tendon of the perforans 
afterwards descends vertically behind the suspensory ligament, receiving 
from it a strong fibrous band analogous to that of the fore-limb, but less 
voluminous; it then passes through the annular portion of the perforatus, 
is inflected with that muscle over the great sesamoid groove, glides on the 
posterior articulating surface of the second phalanx and that on the small 
sesamoid bone, thinning out into a plantar aponeurosis which is provided with 


1 The tibialis posticus of Man. 2 The flexor longus pollicis of Man. 


306 THE MUSCLES. 


a phalangeal reinforcing sheath, and finally terminates on the semilunar 
crest of the os pedis. This tendon, therefore, on leaving the tarsus, com- 
ports itself exactly like that of the anterior limb. 

Relations,—Outwards, with the lateral extensor of the phalanges, the 
soleus, and the tibial aponeurosis. Inwards, with this aponeurosis and the 
oblique flexor Behind, with the gastrocnemii, the perforatus, and the 
fibrous band of the tendon of the hock. In front, with the tibia. 

Action.—This muscle flexes the phalanges on one another and on the 
metatarsus. It may also extend the foot in pressing, during its contraction, 
behind the tibio-tarsal articulation. In addition to this, its tendon acts, 
while the animal is standing, as a mechanical support to the phalanges and 
the articular angle of the fetlock. 


6. Oblique Flexor of the Phalanges. (Fig. 187, 22.) 


Synonyms.—Peroneo-phalangeus— Girard. The tibialis posticus of Man. (Flexor 
pedis accessorius—Percivall. Small tibio-phalangeus—Leyh.) 


Situation—Direction—A muscle situated behind the tibia, between 
the popliteus and the perforans, in a direction slightly oblique downwards 
and inwards. 

Form—Structure.—It is composed of a fleshy fusiform body, intersected 
by numerous fibrous bands, and provided with a funicular tendon inferiorly. 

Attachments.—The superior extremity is fixed behind the external 
tuberosity of the tibia—origin. The tendon is united, by its inferior 
extremity, to that of the perforans towards the upper third of the meta- 
tarsal region—termination. 

Relations—The muscular portion responds: in front, to the perforans, 
the popliteus, and the posterior tibial artery; behind, to the gastrocnemii 
and the perforatus. The tendon, at first lodged in a muscular channel 
in the perforans and covered by the tibial aponeurosis, afterwards enters a 
tortuous sheath at the inner side of the tarsus, and which is formed by the 
groove that bends behind the infero-internal tuberosity of the tibia. 

Action.—It is a congener of the deep flexor. 


DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE LEG IN OTHER THAN SOLIPED 
ANIMALS, 


A. Anterior Tibial Region. 


Rouminants.—Among these animals, the Ox presents: 

1. A complex muscle, which is represented in the Horse by the anterior extensor of 
the phalanges, and the tendinous cord of the flexor metatarsi. Single at its superior 
extremity, which begins by a tendon arising from the digital fossa situated between the 
trochlea and the external condyle of the femur (Fig. 138, 1), this muscle comprises in 
its mididle part three fleshy divisions which are terminated inferiorly by tendons. 

One of these divisions, situated in front of, and within the other two, has its tendon 
prolonged to the superior extremity of the principal metatarsal bone, and is also inserted 
into the cuneiform bones. It is a flexor of the metatarsal region, and replaces the 
tendinous cord which performs this function in Solipeds (Fig. 138, 2). 

The second, placed without the preceding, constitutes a common extensor of the 
digits, whose t:ndon comports itself exactly like that of the anterior limb (Fig. 138, 5, 
5’, 6) (see p. 270). 

Yhe third, concealed by the other two, forms the proper extensor of the internal digit, 
and resembles its fellow in the fore extremity see p. 270), 

2. An anterior tibial muscle (muscular portion of the flexor of the metatarsal of 
the Horse). It is a triangular, muscular body, lodged in the antero-external fossa of 
the tibia. into the upper part of which it is inserted, and is succeeded by a tendon that 


MUSCLES OF THE POSTERIOR LIMBS. 


307 


commences towards the middle of the tibia. This tendon passes through a ring pierced 
in the tendon of the muscle that represents the tendinous portion of the flexor of the 
metatarsus; it then deviates inwards, and is fixed into the cuneiforms and the superior 
extremity of the principal metatarsal bone (Fig. 138, 4). 


3. A proper extensor of the external digit 
Qateral extensor of the phalanges in Solipeds, 
the peroneus brevis lateralis in Man), whose 
fleshy body is altogether similar to that of the 
analogous muscle in the Horse, and iy termi- 
nated by a long tendon which resembles that of 
the proper extensor of the internal digit (Fig. 
138, 7, 8, 9, 10). 

4. A muscle which represents the peroneous 
longus in Man, and of which in Solipeds there 
is not a trace. This muscle commences by a 
short, conical, muscular body in front of ‘the 
supero-external tuberosity of the tibia; and it 
terminates by a long tendon whose direction is 
as follows: included at first, like the muscular 
portion, between the proper extensor of the ex- 
ternal digit and the triple muscular fasciculus 
already described, it arrives on the outside of 
the tarsus, passes through the fibrous groove of 
the proper extensor, where it is enveloped by a 
special synovial membrane, passes over the 
latter in slightly crossing its direction, and is 
inflected at first backwards, then outwards, in 
insinuating itself underneath the external tibio- 
tarsal ligament, and the caleaneo-metatarsal 
and the posterior tarso-metatarsal ligaments, 
which retain it in a channel on the inferior 
face of the cuboido-scaphoid bone. It is finally 
inserted into the deep face of the second cunei- 
form one, and the external side of the superior 
extremity of the metatarsus. by a small branch 
detached from the outer side of the principal 
tendon. 

All these muscles are similarly disposed in 
the Sheep anil Guat. 

Pic.—The anterior tibial muscles of this 
animal resemble those of Kuminants, with the 
exception of some peculiarities of secondary im- 
portance, among which the following may be 
cited : 

The muscular fasciculus which replaces the 
cord of the flexor metatarsi in the Horse termi- 
nates on the scaphoid and the second cuneiform 
bone. The common extensor of the diyits has 
four tendons, one for each digit. The proper 
extensors have two each, one for the small digit, 
the other for the great. The anterior tibial 
passes to the second cuneiform bone. The 
peroneus longus lateralis is inserted by its ten- 
don into the upper extremity of the internal 
metatarsus. 

Car\1vora.—Four muscles are described in 
these animals: 1, An anterior tibial; 2, A 


EXTERNAL MUSCLES OF THE LEG OF 
THE OX. 


1, Originating tendon cf the muscle which 


represents the anterior extensor of the 
phalanges and the tendinous cord of the 
flexor metatarsi in the Horse; 2, Its 
flexor fasciculus; 5, That which forms 
the common extensor of the digits; 5’, 
The tendon of this fasciculus; 6, Its 
terminal bifurcation; 3, The long la- 
teral peroneus; 3’, Its tendon; 4, Origin 
of the anterior tibial (the muscular por- 
tion of the flexor metatarsi in the 
Horse); 7, Proper extensor of the 


external digit (short lateral peroneus); 8, Its tendon; 9, Its insertion into the second 
phalanx; 10, Its insertion into the third phalanx; 11, External belly of the gas- 
trocnemii; 11’, Their tendon; 12, Solearis; 13, Tendon of the perforatus; 14, Perforans; 
14’, Its tendon; 15, Suspensory ligament of the fetlock; 16, The band it gives off to 
the perforatus tendon; 17, That which it sends to the proper extensor of the external 
digit ; 18, The pedal muscle- 19, The insertion of the long vastus on the patella and its 


external ligament. 


7 


308 THE MUSCLES. 


long common extensor of the digits; 3, A long lateral peroneus; 4, A. short Jateral 

roneus. : 
nas 2 Anterior tibial—Situated in front of the tibia, and more voluminous than the 
common extensor of the digits, whose superior extremity it covers, this muscle has its 
oricin op the crest and external tuberosity uf the tibia. It receives, near the inferior 
third of this bone, an extremely thin muscular band which proceeds from the fibula, 
and which we may with justice compare to the proper extensor of the big toe in Man, 
Then it terminates by a tendon on the metatarsal bone of the internal digit; when this 
bone is connected with a digital region, the third phalanx receives a particular bianch 
from this tendon, which represents the tendinous portion of the small proper extensor 
fasciculus unnexed to the anterior tibial. This muscle responds: in front to the tibial 
aponeurosis; inwards and backwards, to the tibia; outwards, to the common ex- 
tensor of the digits. Its tendon is fixed in the bend of the hock by a fibrous band, 
whose arrangement is singular enough to deserve mention here. Attached in front 
of the inferior extremity of the tibia, this band gives origin, by its internal extremity, 
to a strong ligamentous cord which passes undcr the tendon of the anterior tibial 
muscle to reach the anterior face of the tarsus, where it contracts intimate adhesions 
with the capsular ligament of this region, and terminates on the superior extremity 
of the metatarsal bone of the middle digit, This cord binds the inferior extremity of 
the tibia to the metatarsus, and prevents undue extension of the tibio-tarsal articula- 
tion. It is, perhaps, the representative of the tendinous cord of the anterior tibial region 
in the Horse. 

2. Long common extensor of the digits—This muscle is composed of a fusiform fleshy 
body, and a quadrifureated tendon. The fleshy body, situated beneath the tibial 
aponeurosis, between the anterior tibial and the lateral peroneal muscles, covers the 
external face of the tibia and the small fasciculus of the proper extensor of the thumb; 
it originates by a short and strong tendinous cord, from the inferior extremity of the 
femur, between the external condyle and the trochlea. The tendon is continuous with 
the inferior extremity of the fleshy portion, passes beneath the band of the anterior 
tibial, through another fibrous ring at the cuboid bone, and is inserted, by its four 
terminal branches into the four large digits, in the same manner as the analogous tendon 
in the fore-limb, 

3. Long lateral peroneus—This muscle is composed of a very short conical fleshy 
portion, succeeded by a long tendon. The former originates in front of the tuberosity of 
the supero-external tuberosity of the tibia, and-does not appear to have any connection 
with the fibula. Included between the common extensor of the digits and the short 
lateral peroneus, it is covered by the tibial aponeurosis, and covers the anterior tibial 
vessels. The tendon descends parallel with the fibula to its inferior extremity, over which 
it glides in becoming inflected. On reaching the cuboides, it enters a groove excavated 
on its external surface, gives off a short isvlated branch to the superior extremity of the 
first metatarsal bone, afterwards crosses transversely the direction of the tarsus in 
passing behind the inferior row of bones, and terminates on the metatarsus of the 
thumb. On its way behind the cuboides, this tendon gives off another branch which 
we have every reason to believe is constantly present; it is a short, interosseous fasci- 
culus, which at first penetrates between the cuboides and the external metatargul bone, 
then between tlie latter and the second metatarsal. 

This muscle carries the inferior extremity of the limb outwards, and when the 
foot is much extended it, may act as a flexor. j 

4. Short lateral peroneus.—In Carnivora, this muscle is formed of two fasciculi, o 
superior and inferior, which may be described as two distinct muscles. 

The superior fasciculus comprises a very weak muscular portion attached to the 
upper third of the anterior border of the fibula, and a funicular tendon succeeding its 
inferior extremity wbout the midile of the tibia. This tendon glides over the inferior 
extremity of the fibula, behind the long lateral peroneus, which it passes under and 
crosses in descending to the phalanges of the external digit, where it is united to the 
tendinous branch of the common extensor belonging to this digit. 

The inferior fasciculus has its origin on the anterior border and external aspect of 
the peroneus, by penniform fibres which join a short, but more voluminous teudon than 
that of the preceding fasciculus. This tendon, with the last, enters the posterior 
groove in the fibula, and is attached, by its inferior extremity, to the upper end of the 
rcecies metatarsus, outside the branch furnished by the long lateral peroneus to that 

one. 

The superior fasciculus acts as a proper extensor of the external digit, The inferior 
is an abductor of tlie foot. 


MUSCLES OF THE POSTERIOR LIMBS, 309 


B. Posterior Tibial Region. 


» _Roumrnants.—In the Oz, Sheep, and Goat, the muscular ortion of the perforatus i 
thicker than in Solipeds. The portion of the perforans is better defined thats ee 
and is lodged in a depression on the principal portion; it can easily be traced from the 
supero-external surface of the tibia, where it originates, The tendon does not differ from 
that in the fore-limb; but the bands which descend from the metatarsus to the heels, to 
be united with the two terminal branches of this tendon, are much smaller than those in 
the metacarpal region. 

Carnivora.—The soleus is absent in the Dog and Cat. The muscular body of the 
perforatus is prismatic, voluminous, and entirely blended, in its upper two-thirds at least 
with the external gastrocnemius; these two muscles have therefore a common origin. The 
tendon is quadrifurcated, as in the anterior limb; it offers on its surface, shortly before 
its division, several thin muscular bands, traces of the fleshy portion of the common short 
muscle of Man. Several of these bands come from the perforans tendon, and all pass to 
the four terminal branches of the muscle. The terminal tendon of the perforans is divided 
into four or five branches, one for each digit. 

The posterior tdbial is not united inferiorly to this tendon, but constitutes a perfectly 
distinct muscle situated between the deep and oblique flexors of the phalanges, Formed 
by a very smal] fleshy body and a long thin tendon, this muscle originates above the 
peroneus, from the posterior surface of the tibia. Its tendon lies beside that of the 
oblique flexor, and with it enters the groove behind and within the inferior extremity of 
the tibia. Enveloped by a synovial membrane proper to its passage through this groove, 
this tendon soon leaves it to pass to the free surface of the posterior tarso-metatarsal 
ligament, with which it is blended towards the middle of the tarsus. 


COMPARISON OF THE MUSCLES OF THE LEG OF MAN WITH THOSE OF ANIMALS, 


In Man, the muscles of the leg are divided into three regions: an anterior, external, 
and posterior 


A, Anterior Region. 


This includes three muscles : 

1, The anterior tibial, which corresponds to the fleshy portion of the flexor of the 
metatarsus, and whose imperforate tendon is fixed into the first cuneiform. 

2. The common long extensor of the toes, which represents the anterior extensor 0 the 
phalanges of the Horse. This muscle is attached, above, to the external tuberosity of the 
tibia and the upper three-fourths of the inuer face of the fibula; its tendon divides into 
two fasciculi, the internal of which furnishes a branch to the second, third, and fourth 
toes, and the external goes to the fifth. 

8. The proper extensor of the large toe, represented in the Dog by a small fasciculus 
blended with the anterior tibial, is an elongated semi-penniform muscle which arises 
from the inner face of the fibula and the interosseous ligament, and terminates on the 
second phalanx of the great toe, after receiving the pedal tendon (extensor brevis 
digitorum). 


B. External Region. 


This region is only composed of two muscles: the long and short peroneus. 

The first, which does not exist in Solipeds, is a penniform muscle attached to the 
upper third of the fibula, the external tuberosity of the tibia, and the internal face of the 
tibial aponeurosis, by the superior extremities of its muscular fibres. The flat tendon 
which terminates it is fixed to the outer portion of the base of the first metatarsal. 

The second corresponds to the lateral extensor of the phalanges of the Horse, and is 
found in all animals. It is penniform, and is attached above, by its fleshy fibres, to the 
lower two-thirds of the external face of the fibula; below, by its tendon, to the upper 
extremity of the fifth metatarsal. : : 

These two muscles determine very complicated movements in the region of the foct. 


C. Posterior Region. 


The posterior tibial muscles form two layers: a superficial and a dee ; 
The first comprises the crural triceps and the plantaris, The triceps itself 1s 


23 


310 THE MUSCLES. 


osed of the gastroenemit, of which we will say nothing, and the soleus. The latter 
iD daitened frome belie to behind, attached to the upper third of the fibula, the oblique 
line of the tibia, and the middle third of the inner border of this bone, and terminated. 


b tic lamina which is blended with the tendo-Achilles. 
formed bye ‘ama fusiform muscular body, situated beneath the external g 


MUSCLES OF THE HUMAN LEG; ANTERIOR 
TIBIAL REGION. 


1, Quadriceps extensor inserted into the pa- 
tella—the figure is on the tendon of the 
rectus, the vastus internus and externus 
being on each side; 2, Subcutaneous sur- 
face of the tibia; 3, Tibialis anticus; 4, 
Extensor longus digitorum; 5, Extensor 
proprius pollicis, 6, Peroneus tertius; 7, 
Peroneus longus ; 8, Peroneus brevis; 9, 9, 
Borders of the soleus muscle; 10, Part of 
the inner belly of the gastrocnemius; 11, 
Extensor brevis digitorum—the tendon in 
front of the cipher is that of the peroneus 
tertius, that behind it the peroneus brevis. 


The plantaris is 
emellus, then 


Fig. 140. 


SUPERFICIAL POSTERIOR MUSCLES OF 
THE HUMAN LEG. 

1, Biceps forming outer ham-string; 2, Ten- 
dons forming inner ham-string; 3, Popli- 
teal space; 4, Gastrocnemius ; 5, 5, Soleus; 
6, Tendo-Achilles ; 7, Posterior tuberosity 
of os calcis; 8, Tendons of peroneus longus 
and brevis passing behind the outer ankle; 
9, Tendons of tibialis posticus and flexor 
longus digitorum passing into the foot 
behind the inner ankle. 


by a long slender tendon, which is confounded with the inner border of the tendo- 


Achilles, or is inserted into the os calcis. 


The deep layer is composed of four muscles: 
1. The popliteus, which in its attachments and position resembles that of animals. 
2, The common long flexor of the toes,corresponding to the oblique flexor of animals, 


MUSCLES OF THE POSTERIOR LIMBS. 311 


It is an elongated penniform muscle, fixed above to the oblique line and middle third of 

the posterior face of the tibia. Its tendon is inflected beneath the external malleolus, 
asses in front below the astragalus, receives the accessory of the long flexor, and then 
ivides into four branches for the four lesser toes. 

3. The posterior tibial, represented by a portion of the perforans of animals; its 
tendon is reflected beneath the internal malleolus of the tibia, and is attached to the 
scaphoid process, 

4, The proper long flexor of the great toe, also represented by a portion of the perforans, 
This muscle is voluminous and prismatic, and is attached above to the lower two-thirds 
of the posterior face of the fibula. Its tendon is reflected inwards on the astragalus and 
the groove in the os calcis, crosses the tendon of the common long flexor, and terminates 
on the posterior extremity of the third phalanx of the great toe. 


MUSCLES OF THE POSTERIOR FOOT. 


Sourpeps.—In these animals are found: 1, Two lumbrici and two 
nines muscles, corresponding to those of the anterior limb; 2, A pedal 
muscle. 

Pedal muscle-—The tarso-prephalangeus of Girard. (The flexor meta- 
tarsi parvus. Not mentioned by Percivall.) This is a small riband-shaped 
fasciculus, situated in front of the principal metatarsal bone, beneath the 
extensors of the phalanges. It is attached, by its inferior extremity, to 
the internal surface of the tendon common to these two muscles, and by its 
upper extremity to the lower end of the os calcis (and astragalus). It aids 
in oc the digit (flexing the hock, and probably keeping the tendons 
tense. 


Ruminants.—The pedal is the only muscle in the region of the foot met with in 
Ruminants. It is attached, inferiorly, to the tendon of the common extensor and that of 
the proper extensor of the internal digit. 

Pic.—This animal possesses: 1, A pedal muscle attached, below, to the two branches 
of the common extensor of the large digits : 2, Four interosscous metatarsal muscles, which 
do not appear to differ in their general arrangement from the metacarpal interosseous 
muscles. 

Carnrvora.—In the Dog and Cat there exist in the region of the posterior foot : 

1. A pedal muscle, composed of three fasciculi which have their origin either from the 
inferior extremity of the os calcis, or from the tendinous sheaths in the bend of the hock ; 
they terminate on the second, third, and fourth digits by small tendons joined to the 
branches of the common extensor. 

2. The muscular digitations annexed to the tendon of the perforatus, traces of the 
fleshy portion of the flexor brevis digitorum of Man. 

3. A flexor pedis accessorius, or perforans, a small undeveloped muscle commencing 
outside the tarsus, and terminating by a very delicate aponeurosis on the posterior face of 
the perforans tendon. 

4. Two or three pale and rudimentary bands, situated inside the tarsus and near the 
internal digit. These are the vestiges of the muscles proper to the great toe in Man. 

5. An adductor of the little toe (abductor minimi digit) is a thin, elongated muscle, 
carried obliquely from the posterior tarso-metatarsal ligament to the internal side of the 
first phalanx of that digit. 

6. Four interosseous metatarsal muscles, resembling the analogous muscles of the 
metacarpal region. eee 

7. Lumbrici, similar to those of the anterior limb. 


COMPARISON OF THE MUSCLES OF THE FOOT IN MAN WITH THOSE OF ANIMALS. 


In Man, there are distinguished the muscles of the dorsal region, the plantar region, 
and the interosseous muscles. 


A. Dorsal Region. 


This only contains one muscle, the pedal (extensor brevis digitorum). It is attached, 
behind, to the antero-external part of the upper face of the os calcis by several aponeurotic 
lamine ; its fleshy fasciculi, four in number, are prolonged by as many tendons destined 
to the first four toes; three of them pass along with the tendons of the common extensor. 


. 


312 THE MUSCLES. 


B. Plantar Region. 


This is subdivided into three regions: a middle, internal, and external. : 

The first comprises: 1. The common short flexor of the toes which is represented in 
Solipeds by a portion of the perforatus. Itis attached to the infero-internal tuberosity of 
the os calcis, and to the upper face of the middle plantar aponeurosis. It is followed hy 
four tendons, which arte inserted into the second phalanges of the first four toes, after 
forming rings through which pass the tendons of the common long flexor. 

2. The accessory of the long flexor, whose fibres pass to the tendons of the common 
flexor. 

3. The lumbrici, four in number, and analogous to those of the hand. : 

The internal plantar region is composed of three muscles, which are found in a 
rudimentary condition in the Dog. 


Fig. 142, 


‘FIRST LAYER OF PLANTAR MUSCLES OF THIRD AND PART OF SECOND LAYER OF 
HUMAN FOOT. PLANTAR MUSCLES OF HUMAN FOOT. 

1, Os calcis; 2, Posterior part of plantar ‘ 1, Incised plantar fascia; 2,@Mfusculus acces- 
fascia divided transversely; 3, Abductor sorius; 3, Tendon of a ie digi- 
pollicis; 4, Abductor minimi digitii; 5, torum ; 4, Tendon of flexommmgus pollicis; 
Flexor brevis digitorum; 6, Tendon of 5, Flexor brevis pollicis; 6, Adductor pol- 
flexor longus pollicis ; 7, 7, Lumbricales. licis; 7, Flexor brevis mini digitii; 8, 


Transversus pedis; 9, Interossei muscles, 
plantar and dorsal; 10, Convex ridge 
formed by tendon of peroneus longus in its 
oblique course across the foot. 


1. The short adductor of the great toe, which extends from the internal tuberosity of 
the os calcis to the internal sesamoid and the first phalanx of the great toe. 

2. The short flexor of the great toe, which arises from the third cuneiform and the 
tendon of the posterior tibial, and terminates by two branches on the external sesamoid 
and the internal sesamoid of the great toe. 

3. The short adductor of the great toe, a muscf formed by two fasciculi, and having a 
common termination on the external sesamoid. One of these fasciculi arises from the 
inferior face of the cuboides, the third cuneiform, and the base of the third and fourth 
metatarsal ; it has been formerly described as the oblique adductor. ‘Uhe other has its 
origin from the inferior face of the three last metatarso-phalangeal articulations: this 
has also been called the transverse adductor. 


MUSCLES IN BIRDS, 312 


The external plantar region likewise comprises three muscles, which ave: 
1, The short abductor of the little toe, which is detached from the internal tuberosity 
of the os calcis, and is inserted into the external portion of the first phalanx of the little 


oe. 

2. The short flexor of the little toe is attached, behind, to the sheath of the long 
peroneus and to the process of the fifth metatarsal; in front, to the external part of the 
first phalanx of the little toe. 

8. The opponens of the little toe, concealed beneath the preceding, is inserted at 
one end to the sheath of the long peroneus, and at the other to the external border of 
the fifth metatarsal. 


C. Interosseous Muscles. 


These are divided into dorsal and plantar interosseé. Their disposition is nearly 
the same as in the hand. 


CHAPTER III. 


THE MUSCLES IN BIRDS. 


In birds we find the majority of the muscles already described ; though they are appro- 
priate by their form, volume, arrangement, etc., to the particular conformation of the 
skeleton in these animals. 

To undertake, j as essentially practical work, w special description of all these 
organs, would be from the object aimed at : and we therefore confine ourselves 
to those points int most interest inan animal mechanic point of view. 

1. birds present in the inferior limbs and at the extremity 
of the win of ication more or less extensive along their course. This 
transformation fibrous*tigsue of the muscles is not the effect of senility, for it is 


The tendons, in er part of their elasticity, doubtless gain in tenacity ; 
and this allows them“ transmit to the bony levers the muscular efforts in a more 
integral manner. 

It is also observed that the partial ossification of the tendons does not exclusively 
belong to the limbs; for it is not rare to meet with this change in other regions, as in 
the neck of wading birds, In the museum of the Veterinary School at Lyons is the 
skeleton of a heron which shows this peculiarity in the highest degree; the cervical 
vertebree are roughened by a multitude of filiform bony stylets, all directed backwards, 
and which have originated from the ossification of the tendinous fibrillee annexed to the 
muscles of cervical region. 

2. The Pectoral Muscles—The two alternative movements which produce flight—the 
elevation and depression of the wings—being due to the action of the pectoral muscles, 
these merit special notice. : 

The superficial or great pectoral, “ which alone weighs heavier than all the other 
muscles of the bird put together, is attached to the furculum, to the great ridge of the 
sternum, and to the last ribs; it is inserted into the very salient rugged outline of the 
humerus. It is by this muscle that birds are able to give those powerful strokes of the 
wings which are necessary in flight.” 

The deep or small pectoral is “ placed in the angle formed by the body of the sternum 
and its crest, and in the interval betwecn the furculum and the coracoid bone. 
Its tendon passes through the foramen formed by the union of the fureulum, the coracoid 
bone, and the scapula, as over a pulley; it is inserted above the head of the humerus, 
which it raises. It is by means of this arrangement that nature has been able to place 
an elevator and depressor at the inferior surface of the trunk so far from the centre of 
gravity, without which the bird would have been liable to lose its equilibrium and tumble 
over head foremost in the air." 

Cuvier, adopting the nomenclature of Viceq-d’Azyr, ealled this muscle the middle 
pectoral, and he gave the name of small pectoral to » triangular fasciculus which leaves 
the lateral angle of the sternum and the base of the coracoid bone, to be inserted under 


1 Cuvier, ‘ Legons d’ Anatomie Comparée,’ 


314 THE MUSCLES. 


the head of the humerus. In our opinion, this tendon does not belong to the pectoral 
region, but to that of the shoulder; and with J. F. Meckel we are inclined to consider it 
as tle coiaco-humeralis, which has followed the coracoid process in its development." 

3. The Diaphragm.— In birds, the diaphragm is so differently disposed from what 
it is in the higher vertebrata, that its existence has been successively described and mis- 
understood, admitted and refuted, and is still looked upon as problematical by a large 
number of anatomists. Nevertheless, this muscle exists, and its development is in 
perfect harmony with the importance of its functions. It is composed of two planes, 
which at their origin are confounded with each other, but soon become separated and 
pursue, one a transverse, the other an oblique direction. The transverse plane is 
triangular in form, and is carried horizontally from the right to the left ribs against the 
inferior surface of the lungs. The oblique plane is convex in front, concave behind, and 
extends from the dorsal aspect of the spine to the sternum, dividing the cavity of the 
trunk into two secondary cavities—the thorax and abdomen. 

“Tn birds, as in mammals, the diaphragm is therefore intended to perform two principal 
functions; but to do this perfectly in the former, it is doubled. So far, then, from this 
inspiratory muscle being absent in birds, or from its existing in a rudimentary degree, 
they are really provided with two diaphragms: 1, A pulmonary diaphragm, which 
presides in the dilatation of the lungs; 2, A thoracic abdominal diaphragm, which par- 
titions the great cavity of the trunk, and concurs in the inspiration of the air by dilating 
the large serial reservoirs lying at its posterior surface. Of these two muscular planes, 
the first is analogous to that portion of the diaphragm which, in Man and the mammalia, 
is inserted into the sternum and the ribs; the second manifestly represents the pillars 
of the diaphragm.” 

This description, taken from the work of M. Sappey, an observer who is as conscien- 
tious as he is talented, gives a perfectly exact idea of this muscle. 


1 E. Geoffroy Saint-Hilaire, in his memoir on the bones of the sternum (‘ Philosophie 
Anatomique,’ vol, i. p. 89), in comparing the pectoral muscles of fish to those of birds, 
also employs the nomenclature of Vicq-d’Azyr, and recognises three pectorals as well. 
We are, however, obliged to confess ourselves as in opposition to the great master who 
has established rules to follow in the classification of organs, in consequence of his 
having limited his comparisons to the two classes of vertebrata he had principally in 
view. If he had extended his observations to the mammalia, and, in them sought for the 
analogue of the pectoralis parvus, he would have discovered it, as we have done, in the 
region of the shoulder, and not in that of the sternum. 


CHAPTER IV. 


GENERAL TABLE OF THE INSERTIONS OF THE MUSCLES IN 
3 SOLIPEDS. 


1. VeRTEsraL CoLumn. 


A. CERVICAL VERTEBRA 


I. Atlas. 
The atlas gives insertion to nine pairs of muscles :— 


a, By the surface representing the spinous process, to the— 
Small posterior recti muscles of the head. 


b. By its transverse processes, to the— 
1. Splenius muscles. 
2. Small complexus muscles. 
8. Great oblique muscles of the head. 
4, Small oblique muscles of the head, 
5. Mastoido-humeralis muscles. 


c, By its body, to the— 
1. Small anterior recti muscles of the head, 


2. Small lateral recti muscles, 
3. Long muscle of the neck. 


Il. Axis. 
The axis gives insertion to six pairs of muscles :— 

a. By its spinous process, to the— 

1. Transverse spinous muscles of the neck. 

2. Great oblique muscles of the head. 

8. Great posterior recti muscles of the head, 
b. By its transverse processes, to the— 

1. Intertransverse muscles of the neck. 

2. Mastoido-humeralis muscles, 

And by the inferior face of its body, to the— 
8. Long muscle of the neck. 


III. Third, Fourth, Fifth, Sixth, and Seventh Cervical Vertebre. 
These vertebre give insertion to the following muscles :— 


a. By their spinous processes, to the— 
1, Transverse spinous muscles of the neck. 
2. Tlio-spinalis muscles (4th to the 7th). 


b. By their articular tubercles, to the— 
1, Great complexus muscles, 
2. Small complexus muscles. 
3. Transverse spinous muscles of the neck. 
4. Intertransverse muscles of the neck. 


c. By their transverse processes, to he— 
1, Angular muscles of the scapula. 
2. Splenius muscles (3rd and 4th). 
3. Mastoido-humeralis muscles (3rd and 4th). 
4. Common intercostal muscles (7th). 
5. Intertransverse muscles of the neck. 
6. Llio-spinalis muscles (inferior branch). — 


316 THE MUSCLES. 


And by the inferior faces of their bodies, to the— 
1. Great anterior recti muscles of the head, 
2. Long muscle of the neck. 


B. DORSAL VERTEBRA. 


The dorsal vertebre give insertion :— 


a. By their spinous processes, to the— 

. Splenius muscles (Ist to 5th or 6th), 

. Great complexus muscles (1st to 6th). 

. Small complexus muscles (1st and 2nd), 

. Trapezius muscles. 

Great dorsal muscles (4th to 18th). 

Rhomboid muscles (2nd to 7th). 

. Small anterior serrated muscles (2nd to 13th). 

. Small posterior serrated muscles (10th to 18th). 
. Ilio-spinalis muscles. 

. Transverse spinous muscles of the back and loins. 


b. By their transverse processes, to the— 
1. Great complexus muscles. 
2. Small complexus muscles. 
38. Ilio-spinalis muscles. 
4, Transverse spinous muscles of the back and loins, 
5, Supercostal muscles, 


ce. By their bodies, to the— 
1. Long muscle of the neck (1st to 6th). 
2. Great psoas muscles (17th to 18th). 
3. Small psoas muscles (16th to 18th). 


ai 
SOOM OPO Poe 


C. LUMBAR VERTEBRE. 
The lumbar vertebrae give insertion :— 


a. By their spinous processes, to the— 
1. Great dorsal muscles. 
2. Small posterior serrated muscles (Ist to 3rd). 
3. Ilio-spinalis muscles. 
4, Transverse spinous muscles of the back and loins. 


b. By their articular tubercles, to the— 


1, Ilio-spinal muscles. 
2. Transverse spinous muscles of the back and loins, 


ce. By their transverse processes, to the— 
1. Great psoas muscles. 
2. Square muscles of the loins. 
3. Intertransverse muscles of the loins. 
4, Transverse muscles of the abdomen, 
5. Ilio-spinalis muscles, 


d. By their bodies, to the— 
1. Great psoas muscles. 


2. Small psoas muscles. 
3. Pillars of the diaphragm. 


D, SACRUM, 
The sacrum gives insertion to the— 


. Ilio-spinalis muscles. 

. Transverse spinous muscles of the back and loins. 
. Superior sacro-coccygeal muscles, 

. Lateral sacro-eoccygeal muscles. 

. Inferior sacro-coccygeal muscles. 


Or Oe 


GENERAL TABLE OF MUSCULAR INSERTIONS. 


6. Ischio-coccygeal muscles, 
7. Long vasti muscles. 

8. Semitendinosus muscles. 
9, Internal obturator muscles. 


E. COCCYX. 
The coccyx gives insertion to the— 


1. Superior sacro-coecygeal muscles. 

2. Inferior sacro-coccygeal muscles, 

3. Lateral sacro-coccygeal muscles. 

4, Ischio-coccygeal muscles (1st and 2nd coccygeal vertebrx), 


2. Heap. 


A, BONES OF THE CRANIUM. 


I. Occipital. 
The occipital gives insertion to nine pairs of muscles :— 


1, Great complexus muscles. 

2. Small oblique muscles of the head. 

3. Great posterior recti muscles of the head. 
4, Small posterior recti muscles of the head. 
5. Great anterior recti muscles of the head. 
6. Small anterior recti muscles of the head. 
7. Small-lateral recti muscles. 

8. Digastric muscles. 

9, Occipito-styloid muscles. 


II. Parietal. 


The parietal gives attachment to one muscle :— 
The temporal. 


III. Frontal. 
The frontal gives insertion to the— 
Supernaso-labialis. 


IV_ Sphenoid. 
The sphenoid gives attachment to four muscles :— 


1. Great anterior recti muscles of the head. 
2. Small anterior recti muscles of the head. 
3. Internal pterygoid muscles. 
4, External pterygoid muscles. 


V. Temporal. 
The temporal gives insertion to five muscles :— 


. Splenius. 

. Small complexus. 

. Small oblique muscle of the head. 
. Mastoido-humeralis. 

. Temporal. 


Cue oboe 


B. BONES OF THE FACE. 
L. Superior Maxillary. 
The supermaxillary gives insertion to the following muscles :— 


1. Cuticularis of the neck. 
2. Alveoli-labialis. 


317 


318 THE MUSCLES. 


3. Supermaxillo-nasalis. 
4. Great supermaxillo-nasalis. 
5. Masseter. 


II. Premazillary Bone. 


The premaxillary bone gives insertion to the— 


1, Small supermaxillo-nasalis. 
2, Anterior middle or intermediate muscle. 


Ill. Palatine Bone. 


The palatine bone gives insertion to the— 
Internal pterygoid muscle. 


IV. Zygomatic. 
The zygomatic bone gives insertion to one muscle, the— 
Supermaxillo-labialis. 


V. Lachrymal. 
The lachrymal bone gives insertion to one muscle, the— 
Lachrymo-labialis. 


VI. Nasal Bone. 
The nasal bone gives insertion to one muscle, the— 
Supernaso-labialis. 


VII. Inferior Maxilia. 
The inferior maxilla gives insertion to the following muscles :— 


1, Sterno-maxillaris. 

2. Alveolo-labialis. 

8. Maxillo-labialis. 

4, Posterior middle or intermediate muscles. 
5. Masseter muscles. 

6. Temporal muscles, 

7. Internal pterygoid muscles, 
8. External pterygoid muscles. 
9. Digastric muscles. 
10. Mylo-hyoid muscle. 
11. Genio-hyoid muscles. 


C. HYOID BONE. 
The hyoid bone gives insertion to the following muscles :— 


a. By tts body and its thyroid cornua— 

. Sterno-hyoid muscles. 

. Scapulo-hyoid muscles. 

. Mylo-hyoid muscles. 

. Genio-hyoid muscles, 

. Stylo-hyoid muscles. 

. Kerato-hyoid muscles, 

. Transverse muscle of the hyoid bone. 


b, By its branches (styloid cornua and styloid bones)— 


1. Stylo-hyoid muscles. 
2. Kerato-hyoid muscles. 
3. Occipito-styloid muscles. 


NHOoPONe 


GENERAL TABLE OF MUSCULAR INSERTIONS. 


3. Bones or tox THorax,. 


A. THE RIBS AND THEIR CARTILAGES, 


The ribs and costal cartilages give insertion to the— 


1. 


Scalenus (Ist), 


. Small anterior serrated muscle (5th to 9th). 
. Small posterior serrated muscle (9th to 18th). 


Tlio-spinalis muscle (3rd to 18th). 


. Common intercostal muscle, 
. Great psoas (17th to 18th), 


Square muscle of the loins (16th to 18th), 


. Great serrated muscle (1st to 8th). 

. Transverse muscle of the ribs (1st). 

. External intercostal muscles. 

. Internal intercostal muscles. 

. Supercostal muscles. 

. Triangular muscle of the sternum (2nd to 8th) 

. Great oblique muscle of the abdomen (Sth to 18th). 
. Small oblique muscle of the abdomen (asternal cartilages), 
. Great rectus muscle of the abdomen (asternal cartilages), 

. Transverse muscle of the abdomen. 
. Diaphragm (7th to 18th). 


STERNUM, 


The sternum gives insertion to the— 


£9 CNIS: Or OO DD et 


10. 
11, 


. Cuticularis of the neck. 

. Sterno-maxillary muscles, 

. Sterno-thyroid muscles, 

. Sterno-hyoid muscles. 

. Superficial pectoral muscles. 
. Deep pectoral muscles. 


Transverse muscles of the ribs. 


. Triangular muscle of the sternum. 
. Great recti muscles of the abdomen. 


Transverse muscles of the abdomen, 
Diaphragm. 
4, THoracic Lime. 


A. BONES OF THE SHOULDER. 


Scapula. 


The scapula gives insertion to seventeen muscles :— 
a, By its external face to the— 


D rp C9 DO 


. Supraspinatus. 

. Subspinatus. 

. Short abductor of the arm, or teres minor. 
. Long abductor of the arm. 

. Trapezius. 

. Mastoido-humeralis. 


b. By its internal face, to the— 
1. Rhomboid muscle. 
2. Angular muscle of the scapula. 
3. Great serrated muscle. 
4. Subscapularis. 
5. Small scapulo-humeral muscle. 


c. By its anterior border, comprised between the cervical angle and the coracotd 
process, to the— 


1, Sterno-prescapularis, or small pectoral muscle. 


319 


THE MUSCLES. 


2. Long flexor of the fore-arm, or brachial biceps. 
3. Coraco-brachial muscle. 
4, Supraspinatus muscle. 


d. By its posterior border, comprised between the dorsal angle and the corre- 
sponding portion of the humeral angle, to the— 
1. Long extensor of the fore-arm. 
2. Large extensor of the fore-arm. 
3. Adductor of the arm, or teres major. 
4, Long abductor of the arm. 
5. Short abductor of the arm. 


B, BONES OF THE ARM. 
Humerus. 
The humerus gives insertion to twenty-four muscles :— 


a, By its superior extremity, to the— 

. Supraspinatus. 

. Subspinatus, 

. Subscapularis. 

. Small scapulo-humeralis. 

. Sterno-trochineus, or deep pectoral. 
Panniculus carnosus, 


3 body, to the— 

. Long abductor of the arm. 

. Short abductor of the arm. 

Coraco-brachial muscle by two points. 

Adductor of the arm, or teres major. 

Short flexor of the fore-arm, or anterior brachial muscle. 
. Short extensor of the fore-arm. 

. Middle extensor of the fore-arm. 

Small extensor of the fore-arm, or anconeus muscle. 
. Anterior extensor of the metacarpus. 

10. Anterior extensor of the phalanges. 

11. Great dorsal muscle. 

12. Mastoido-humeralis muscle. 

13. Sterno-humeralis, or superficial pectoral muscle. 


Oomowpr 


b. By i 


Ss 


WONAID OP we 


e. By its inferior extremity, to the— 

. Anterior extensor of the phalanges. 

. External flexor of the metacarpus. 

. Oblique flexor of the metacarpus. 

. Internal flexor of the metacarpus. 

. Superficial flexor of the phalanges, or perforatus. 
. Deep flexor of the phalanges, or perforans. 


o> OUP 09 bo 


C. BONES OF THE FORE-ARM. 
I. Radius. 
The radius gives insertion :— 


a. By its upper extremity, to the— 
1. Long flexor of the fore-arm, or brachial biceps. 
2, Anterior extensor of the phalanges. 
3. Lateral extensor of the phalanges, 
b. By its body, to the— 
. Short flexor of the fore-arm. or anterior brachial muscle. 
. Oblique extensor of the metacarpus 
. Anterior extensor of the phalanges. 
. Lateral extensor of the phalanges. 
. Deep flexor of the phalanges, or perforans. 


GPwh = 


GENERAL TABLE OF MUSCULAR INSERTIONS. 321 


IL. Ulna. 
The ulna gives insertion :— 


a. By its upper extremity (olecranon) to the—- 

. Long extensor of the fore-arm. 

. Large extensor of the fore-arm. 

. Short extensor of the fore-arm. 

. Middle extensor of the fore-arm. 

. Small extensor of the fore-arm, or anconeus muscle. 
. Oblique flexor of the metacarpus. 

. Deep flexor of the phalanges, or perforans, 


b. By its body, to the— 


1. Short flexor of the fore-arm, or anterior brachial muscle. 
2. Lateral extensor of the phalanges. 


NAR ODe 


D. BONES OF THE CARPUS. 
Supercarpal Bone. 


The supercarpal bone, the only bone of the carpus which has muscular 
attachments, gives insertion to two muscles :— 


1. External flexor of the metacarpus, or posterior ulnar. 
2. Oblique flexor of the metacarpus. 


E, BONES OF THE METACARPUS. 
I. Principal Metacarpal. 
The principal metacarpal gives insertion to a single muscle :— 
By its superior extremity, to the— 
Anterior extensor of the metacarpus. 
Il. External Rudimentary Metacarpal. 


This gives insertion to a single muscle :— 
External flexor of the metacarpus, or posterior ulnar. 


Tl. Internal Rudimentary Metacarpal. 


This gives insertion to two muscles :— 
1. Oblique extensor of the metacarpus. 
2. Internal flexor of the metacarpus, or great palmar muscle. 


F, BONES OF THE DIGITAL REGION. 
I. First Phalane. 
This gives insertion to two muscles :— 
1. Anterior extensor of the phalanges. 
2. Lateral extensor of the phalanges. 
II. Second Phalanx. 
This gives insertion to two muscles :— 
J. Anterior extensor of the phalanges. 
2. Superficial flexor of the phalanges. 
Ill. Third Phalansx. 
The third phalanx, or os pedis, gives insertion to two muscles :— 


1, Anterior extensor of the phalanges. 
2, Deep flexor of the phalanges. 


822 THE MUSCLES. 
5. ABpomMINAL Lime. 


A, BONES OF THE HAUNCH. 
Cowa. 


The coxa gives insertion :— 


a, By the ilium, to the— 
. Ilio-spinalis muscle. 
Iliac (psoas) muscle. 
Small psoas muscle. 
Square muscle of the loins, 
Ischio-coceygeal muscle. 
. Great oblique muscle of the abdomen, 
. Small oblique muscle of the abdomen. : 
. Transverse muscle of the abdomen (through the medium of the crural 
arch). 
9. Mille ztutoal muscle, 
10. Deep gluteal muscle. 
11. Muscle of the fascia lata. 
12. Anterior rectus muscle of the thigh, 
13, Anterior gracilis muscle. 
14, Internal obturator, 


b. By the pubis, to the— 

. Great oblique muscle of the abdomen. 

. Small oblique muscle of the abdomen. 

. Great rectus muscle of the abdomen, 

. Transverse muscle of the abdomen (through the medium of the crural 
arch). 

. Short adductor of the leg. 

. Pectineus muscle. 

. Small adductor of the thigh. 

. External obturator muscle. 

. Internal obturator muscle, 


OWI or Oo bo 


OM IMPMN Pope 


c. By the ischium, to the— 

. Superficial gluteus muscle, 

. Long vastus muscle, 

. Semitendinous muscle. 

. Semimembranous muscle, 
Short adductor of the leg. 

. Great adductor of the thigh, 
. Square crural muscle. 

. External obturator muscle, 

. Internal obturator muscle. 

. Gemelli muscles of the pelvis, 


SOMN Sood 


B, BONES OF THE THIGH, 
Femur, 
The femur gives insertion :— 


a. By its upper extremity, to the— 

. Great psoas muscle. 

. Tliac psoas muscle. 

- Middle gluteus muscle, 

. Deep gluteus muscle, 

. External obturator muscle, 

. Internal obturator muscle. 

» Gemelli muscles of the pelvis. 


b, By its body, to the— 


1. Superficial gluteus muscle, 
2. Fascia lata, 


NDP ON 


GENERAL TABLE OF MUSCULAR INSERTIONS. 


3. External vastus muscle (crural triceps). 
4. Internal vastus muscle (crural triceps). 
5. Anterior gracilis muscle. 
6. Long vastus muscle. 
7. Pectineus muscle. 
8. Small adductor of the thigh. 
9, Great adductor of the thigh. 
10. Square crural muscle. 
11. Gastrocnemii muscles. 


12. Superficial flexor of the phalanges, or perforatus. 


c. By its inferior extremity, to the— 

. Semimembranous muscle. 

. Great adductor of the thigh. 

. Anterior extcusor of the phalanges. 
. Flexor of the metatarsus, 

. Popliteus muscle. 


Our 09 bo 


C, BONES OF THE LEG. 
I. Tibia. 
The tibia gives insertion :— 

u, By its upper extremity, to the— 
1. Flexor of the metatarsus. 
2. Soleus muscle. 
3. Deep flexor of the phalanges, or perforans. 
4. Oblique flexor of the phalanges. 


323 


5. Long adductor of the leg (through the medium of the internal patellar 


ligament). 
b. By tts body, to the— 


. Long vastus muscle. 
. Semitendinous muscle. 


. Flexor of the metatarsus. 
. Popliteus muscle. 
. Deep flexor of the phalanges or perforans, 


DoPohd 


Il. Fibula. 
The fibula gives insertion to two muscles :— 
1. Lateral extensor of the phalanges. 
2. Deep flexor of the phalanges ur perforans, 
Ill. Patella. 
The patella gives insertion to five muscles :— 


. Fascia lata muscle (or tensor vaging). 
. Anterior rectus of the thigh. 

. External vastus (crural triceps). 

. Internal vastus (crural triceps). 

. Long vastus muscle. 


orn 


D. BONES OF THE TARSUS. 
Calcis. 


The calcis gives insertion to the :— 
Gastrocnemii muscles. 


Cuboides. 


The cuboides gives insertion to the— 
Flexor of the metatarsus. 


. Short adductor of the leg (in common with the long adductor) 


324 THE MUSCLES. 


Second Cuneiform. 
This gives attachment to the— 
Flexor of the metatarsus. 


E. BONES OF THE METATARSUS, 
The principal metatarsal gives insertion to the— 
Flexor of the metatarsus. 


F, BONES OF THE FOOT, 
I. First Phalanx. 


The first phalanx gives insertion to one muscle, the— 
Anterior extensor of the phalanges. 


II. Second Phalanx. 
The second phalanx gives insertion to two muscles :— 
1. Anterior extensor of the phalanges. 
2, Superficial flexor of the phalanges, or perforatus. 
III. Third Phalanx. 
The third phalanx gives insertion to two muscles :— 


1, Anterior extensor of the phalanges. 
2. Deep flexor of the phalanges, or perforans. 


BOOK II. 
THE Digestive APPARATUS. 


CHAPTER I. 
GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS. 


We have considered the animal as a machine composed of various 
levers and susceptible of various movements; but it will be easily under- 
stood that the working of this machine will cause the wear or decomposition 
of the molecules which enter into the construction of its organs, and 
that these springs or animated wheels demand for their maintenance an 
incessant supply of new materials, destined to repair their continual losses. 
Animals, therefore, are under the necessity of taking aliment, from which 
they extract those reparative principles which, distributed to all the organs, 
are assimilated into their proper substance. 

The organs in which this work of preparation and absorption of the 
organisable material is carried on are collectively named the digestive 
apparatus: one of the most important of those which, as we will see, suc- 
cessively complicate and perfect the animal machine. This apparatus does not, 
properly speaking, constitute an essentially distinctive characteristic of 
animality, as there are animals without a digestive cavity ; but it is yet one 
of the most salient attributes, for the exceptions just mentioned are ex- 
tremely rare. Considered in the vertebrata, this apparatus appears as a 
long tube, most frequently doubled on itself many times, bulging at intervals, 
and provided along its course with several supplementary organs, the 
majority of which are of a glandular nature. This tube extends the whole 
length of the animal’s body, and opens externally by two orifices, one of 
these serving for the introduction of aliment, the other for the expulsion of 
the residue of digestion. These openings are at the extremities of the 
alimentary canal. : Se, fa ' 

The conformation of this apparatus is not identically the same in all 
the individuals composing the sub-kingdom of vertebrata; on the contrary, 
it presents very numerous varieties, according to the habits and mode of 
life of these individuals, and this makes its study interesting from two 
points of view ; in relation to the science of zoology, and to that of veterinary 
hygiene, which derives from this study valuable indications concerning the 
régime of the domesticated animals. : 

But this diversity of characters does not suffice to establish sharply- 
defined limits between the conformations that are distinguished by it. There 
is, in reality, but one typical form for the digestive apparatus, and the same 
principle prevails in its construction throughout the entire series. Thus, 
whichever of the vertebrata we may be studying, its alimentary tabe will 
be found composed of a collection of bulging or tubuliform cavities, which 
succeed each other from before to behind in the following order: the mouth, 


pharynzx, esophagus, stomach, and intestine. 
24 


826 GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS. 


This system of cavities is divided, physiologically, into two principal sec- 
tions: the first comprises the mouth, pharynx, and cesophagus, or the compart- 
ments in which are carried on those digestive operations termed “ preparatory,” 
because they prepare the aliment for the subsequent modifications which 
constitute the essential phenomena of digestion; the second section is 
formed by the stomach and intestine, where these phenomena take place. 

Each of these two sections is furnished in its course with annexed organs, 
which are present in the majority of vertcbrata; these are the salivary glands 
for the cavities of the first category, and the liver, pancreas, and spleen for 
those of the second. —_ 

In considering the general position of these various parts, principally 
in mammals and birds, it is found that the first section of the digestive 
canal and its appended organs is lodged beneath the upper jaw and the 
base of the cranium, and under the cervico-thoracic portion of the vertebral 
column. The second section, with its annexes, occupies the great abdominal 
cavity. 

a Man, these two sections are divided into supra-diaphragmatic and 
infra-diaphragmatic, because of their relations to the diaphragm. 

The constituent parts of the first category might be termed, by reason 
of their functions, the preparatory organs of the digestive apparatus ; and 
those of the second, or abdominal portion, the essential organs of digestion. 

These various organs, with those composing the respiratory and genito- 
urinary apparatus, have received the name of viscera, and the term splanch- 
nology is often given to that branch of anatomy devoted to their study. 

These new organs differ so notably from those already described, that it 
is necessary to enter into some generalities as to their nomenclature, dis- 
position, form, structure, and physical or chemical characteristics. 

Nomenclature in splanchnology does not rest on any scientific basis ; the 
name of organs being sometimes derived from their form—as the amygdale ; 
sometimes from their direction—rectum ; sometimes also from their uses—the 
esophagus, salivary glands ; their length—duodenum ; the names of the anato- 
mists who have described them—the duct of Stenon, Fallopian tube; and 
at times these names are purely conventional, as the spleen, 

They are distinguished as hollow and solid organs. 

1. The hollow organs have a more or less considerable cavity, capable of 
being increased or diminished, but they are not of a definite shape or 
volume. Their consistency varies with their state of plenitude or vacuity, 
and they are single or double, symmetrical or asymmetrical. 

In all cases, the walls of the hollow organs are composed of two or more 
membranes which we will now describe in a general manner. 

a. The innermost is called the mucous MEMBRANE, because of the mucus 
with which its free surface is always covered. It is made continuous with the 
skin at the natural openings; and from its similarity of organisation it has 
been named the internal or re-entering skin, or internal tegumentary membrane. 


' The name of viscera (from vescor, I nourish) has been given to the organs which aid in 
nutrition, and the term Splanchnology (from omydéhxvov, a viscus or intestine) has been 
bestowed on that division of anatomy which treats of these organs. Splanchnology, thus 
understood, comprises the study of the digestive, respiratory, urinary, and circulatory 
apparatus. But the description of the latter forms a separate category, designated in the 
language of the schools by the name of Angiology. On the other hand, however, several 
authorities include in Splanchnology the organs of generation, and others even add the 
organs of sense. There is, therefore, no accord in the limits given to the definition of 
Splanchnology ; and this being the case, we have thought it best to omit this expression 
and the distinction it seeks to establish. 


GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS. 327 


A mucous membrane comprises a superficial or epitheli 
deep portion which conctihtes te derm es chorion oa” ae ae 

The epithelium is a very thin, inert pellicle, entirely composed of 
epithelial cells united by an almost insignificant quantity of amorphuus 
matter (blastema). The cells are flat or polygonal, 
round or cylindrical, polyhedral, or very irregular Fig. 143. 
in shape. In consequence of these diverse forms, 
there is pavement (or squamous), spherical (or 
spheroidal), and cylindrical or conical (or columnar) 
epithelium. If the cells are furnished with small 
filiform appendages, named vibratile cilia, the 
epithelium is then designated ciliated. When the 
cells are arranged in a single layer on the surface 
of the corium, the spihetinn is nad to be simple ; ee OEE | goes 
it is stratified when the cells are arranged in strata The large scale is magnified 
upon each other. In stratified epithelium, the 310 diameters, and exhibits 
shape of the cells is not the same on the surface 4 nucleus with nucleolus in 
and beneath it, and it is named efter the form of *h®, centre, and secon lary 
the superficial layer. Peet teenie ia 

The mucous derm or corium corresponds to that ; 
of the skin, as the epithelium corresponds to the Fig. 144, 
epidermis. It is composed of connective (or areolar) 5 
tissue, whose thickness, elasticity, vascularity, and 
sensibility varies with the situation and the func- 
tion of organs. The corium is thin aud almost 
destitute of elastic fibres when applied to the bony 
walls of a cavity; on the contrary, it is thick, coLumNar EPrrnetiom. 
elastic, and slightly adherent when it lines organs 1, Nucleus of the cell; 2, 
which, like the stomach, cesophagus, and intestines, | Membrane of the cell raised 
are capable of increasing or diminishing in capacity. st = pears hy ihe 
The fasciculi of the connective tissue in the aeiidiancon 
deeper layers of the corium are loosely united, 
but nearer the surface they lie closer; some- 
times they form, under the epithelium, an 
amorphous surfave-layer, the basement (or 
limitary) membrane. ‘I'he sub-epithelial face 
of the corium is scarcely ever smooth, but 
offers minute prolongationsnamed villosities or 
papille, which are very varied in their form coLuMNAR CILIATED EPITHELIUM, 
and volume, and is more or less marked by Se ee 
depressions designated follicles. The villi “% Sate as : Cilia, 
are obyerved on the deep-seated mucous mem- 
branes ; they are more particularly the vascular and absorbent organs. The 
papille are found towards the natural apertures, and are rich innerves; they 
are more especially the organs of sensibility. The follicles, lined by one 
or other form of cell, are exclusively organs of secretion. 

b. The second membrane met with in the walls of the hollow organs is of 
a muscular, and sometimes of a cartilaginous nature. The muscular mem- 
brane is formed of unstriped fibres whose slow contraction is involuntary. 
In certain organs—those adjoining the natural apertures—the unstriped 
fibres are replaced by striped, which are under the influence of the will, 
or have the same physiological properties as the smooth fibres, as in the 


cesophagus. 


328 GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS, 


(Unstriped or smooth bands of muscles are composed of long fusiform cells 
with stafi-shaped, elongated nuclei, the cells varying from 1-1125th to 1-50th 
of an inch in length, and from 1-5625th to 1-1125th of an inch in breadth.) 


Fig. 146. 


CONICAL VILLI ON MUCOUS MEM- 
BRANE OF SMALL INTESTINE; 
MAGNIFIED 19 DIAMETERS. 


a, Zone of follicles surrounding a soli- 
tary gland; 6, Apertures of simple 
follicles. 


Fig. 147, 


FUSIFORM CELLS OF SMOOTH 
MUSCULAR FIBRE, 


c., When the organs are lodged in one of 
the great splanchnic cavities, such as the 
chest or abdomen, they have a third mem- 
brane—a serous layer, which lines the cavity, 
and is reflected around the viscera contained 
in it, s0 as to envelop them more or less 
completely. This layer has, therefore, an 
adherent face, applied either against the walls 
of the cavity or the external surface of the 
splanchnic organs; and a free face always in 
contact with itself. 

A serous membrane is composed of two 
layers : a deep, connective portion, analogous to 
the mucous corium ; and a superficial, which is 
only pavement epithelium. The free surface 
of this epithelium is perfectly smooth, and 
lubricated by a limpid serosity to facilitate the 
gliding of the parts the membrane covers. 
(The epithelium is a simple tesselated layer 
of flattened and polygonal nucleated cells, 
about 1-1200th of an inch in diameter). 

2. The solid organs are either contained 
in the splanchnic cavities or situated outside 
them, in the midst of connective tissue, which, 
in condensing around them, often forms a 
fibrous covering. 

Like the hollow organs, they are single— 
spleen, liver; or in pairs—kidneys; and 
symmetrical or asymmetrical. They are 
retained in their situation by their vessels 
and nerves, by adherence to the neighbouring 
organs, or by particular serous attachments. 

With the exception of the lungs of animals 
that have respired, all the solid organs have a 
density greater than water. Their weight and 
volume offer numerous differences, which are 
individual or relating to the species to which 
they belong. Nevertheless, each organ pos- 
sesses a certain volume and weight which 
might be termed physiologic ; when the organ 
is above or below this average, we are 
authorized in saying that it is in a patho- 
logical condition. 

Organs are more or less round in form, 
and their surface is traversed by a variable 
number of furrows which indicate their 
division into lobes or lobules. 


a, Two cells in their natural state, one showing the staff-shaped nucleus; b, A cell 
with its nucleus, v, brought distinctly into view by acetic acid. 


GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS. 329 


Their colour is diverse 3 they may be very pale—parotid gland ; or very 
dark—liver, spleen ; or uniform, or of different shades : varieties which are 
most frequently due to the mode of distribution of the vessels, or to the 
presence of certain anatomical elements. The colour of organs is not always 
the same in the deeper parts and at the surface, especially when they are 
enveloped by a thick, opaque membrane ; for instance, the testicle. Lastly. 
the coloration is less intense after death than during life, and particu. 
a if oe animal to which the organs belonged has been killed by effusion 
of blood. 

The consistence of organs depends on their internal formation and the 
nature of their constituent elements; there are sott organs, such as the 
lungs, and resisting organs, as the testicles. Asa general rule, the consistence 
of organs diminishes after putrefaction has set in. 

Cohesion is the resistance that organs offer to the forces which tend to 
tear them ; it depends upon the texture of the organs, and the more or less 
abundance in their interior of fibrous and elastic tissue. Cohesion is very 
different from consistency ; thus, such an organ as the lung may be easily 
compressed, but may be very difficult to tear. 

If organs are examined with regard to their structure, it will be observed 
that all have a thin or thick fibrous casing which throws septa into their 
interior, and which support their proper tissue; this tissue varies with the 
nature of the organs. It will also be found that they are traversed by a 
more or less considerable number of blood-vessels-—arteries and veins. These 
vessels expand into a capillary network, whose meshes have a shape closely 
allied to that of the elements of the proper tissue. The number and volume 
of the vessels of an organ give an exact idea of its importance, and of the 
activity of the physiological phenomena taking place in it. Finally, into 
the composition of organs enter superficial and deep lymphatic vessels and 
nerves, which generally follow the arteries. The nerves show in their course 
small ganglionic enlargements ; their mode of termination is most frequently 
unknown. 

Glands are organs of a particular construction, whose function it is to 
eliminate certain fluid or solid products of the economy. 

The very simple (or tubular) glands consist of a straight or convoluted 
tube, or of a small vesicular cavity opening on a tegumentary membrane, and 
are lined on their inner face by one or more layers of cells. As examples, 
there may be cited the tubular glands of the intestines and stomach, the 
racemose (or lobulated) glands of Briimner, and the solitary follicles of 
the intestine. 

But there are also conglomerate glands, organs more complex, though 
belonging to the same groups as the simple glands. These are glands 
composed of tubes, like the kidneys and testicles ; racemose glands, such as 
the salivary glands and pancreas; a network of glands, like the liver; or 
glands with closed follicles, such as the thyroid. In these the essential 
anatomical element—the polygonal, cylindrical, or spherical gland-cell— 
is situated on the inner face of a tube, as in the kidney, or a demi-vesicle, 
as is seen in the pancreas, or deposited without any order in the meshes of 
a plexus of canaliculi, as occurs in the liver. 

The conglomerate glands arc provided with a common excretory canal, 
that commences in their mass by a great number of arborescent ramifications. 

The walls of this canal are composed of an elastic, and sometimes con- 
tractile, conjunctival membrane, covered on its inner face by an epithelium, 
which may or may not be of the same character as that of the gland. 


330 THE DIGESTIVE APPARATUS IN MAMMALIA. 


For a long time there have been classed as glands certain organs—such 
as the spleen and thymus body-—without excretory ducts, and having only 
remote analogies to glands. The function of these organs is but little known ; 
though as they are always abundantly supplied with blood-vessels, and as 
they are therefore believed to have connections with the vascular system, 
they have been named vascular blood-glands. 

This is the limit to which the generalities relating to the viscera that 
form the object of splanchnology must be confined. We will now pass to 
the description of the digestive apparatus in mammals, and which consists, 
as mentioned above, of a series of enlarged cr tubuliform cavities, to which 
are annexed the glandular organs designated the liver pancreas, and spleen. 


CHAPTER II. 


THE DIGESTIVE APPARATUS IN MAMMALIA. 


We will study, successively: 1, The preparatory organs, which include 
the mouth, the salivary glands annexed to that cavity, the pharynx, and 
the esophagus ; 2, The essential organs, comprising the stomach and intestine, 
and their annexes—the liver, pancreas, and spleen ; with the abdominal cavity, 
which contains and protects these organs. 


Anticte I.—Preparatory OrcaNns or THE DicEstTivE APPARATUS. 
THE MOUTH. 


The mouth, the first vestibule of the alimentary canal, is a cavity 
situated between the two jaws, elongated in the direction of the larger axis 
of the head, and pierced by two openings: an anterior, for the introduction 
of food, and a posterior, by which the aliment passes into the pharynx. 

The mouth should be studied in six principal regions: 1, The lips, 
which circumscribe its anterior opening; 2, The cheeks, forming its lateral 
walls; 8, The palate, which constitutes its roof or superior wall; 4, The 
tongue, a muscular appendage, occupying its inferior wall; 5, The soft palate 
(velum pendulum palati), ® membranous partition situated at the posterior 
extremity of the buccal cavity, which it separates from the pharynx, and 
concurs in the formation, by its inferior border, of the isthmus of the fauces, 
or posterior opening of the mouth; 6, The dental arches fixed on each jaw. 

We will study each of these regions in particular, before passing to the 
examination of the mouth in general. 


Preparation —The whole of the mouth ought to be examined in an antero-posterior 
and vertical section of the head, as in figure 152. 


1. The Lips. (Fig. 110.) 


These are two membranous movable folds, placed one above, the ‘other 
below, the anterior opening of the mouth, which they circumscribe. There 
is, consequently, a SUPERIOR and an INFERIOR LIP, united at each side by a 
commissure. 

Each lip offers for study an external and internal face, and a free and 
an adherent border. 

The external face is convex, and presents, on the median line: in the 
upper lip, a slight projection which divides it into two lateral lobes; in the 


THE MOUTH. 831 


inferior lip, and altogether posteriorly, the single prominence named the 
tuft of the chin. This face, formed by the skin, is garnished with fine, short 
hairs, amongst which may be remarked long, coarse bristles, whose bulbs 
are implanted perpendicularly in the integument, and pass beyond its deep 
surface, to be lodged in the subjacent muscular tissue. These pilous 
tentacles ought to be considered as veritable tactile organs, as several 
sensitive nervous twigs penetrate to the bottom of their follicles. 

The internal face, constituted by the buccal mucous membrane, and 
moulded on the incisor teeth, is concave, smooth, rose-coloured, and often 
stained with black spots. In the superior lip, particularly, may be remarked 
numerous orifices opening on the summits of three small papille; these are 
the openings of the excretory canals by which the labial glands discharge 
their fluid into the interior of the mouth, , 

The free border, thin and sharp, bears the line of demarcation, which 
separates the two teguments. 

The adherent border is limited, in the buccal cavity, by a groove formed 
by the mucous membrane in its passage from the dental arches to the inner 
side of the lips. Beyond the mouth it is not indicated by any peculiarity 
of structure or arrangement, the skin being continued directly from the 
neighbouring parts on the lips. 

The commissures mark, on each side, the point of reunion between the 
free border of the two lips. They are rounded in Solipeds, and offer 
nothing remarkable otherwise. 

Srructure.—-Each lip is composed of two tegumentary layers: one 
cutaneous, the other mucous, between which is found muscular tissue and 
glands, and the general elements of every organisation—vessels and nerves. 

1. Tegumentary layers.—The skin adheres closely to the subjacent tissues, 
and apart from the characters already indicated, there is nothing more to be 
said at present, with regard to its disposition, as it will be studied more 
completely with the organs of sense. With regard to the mucous membrane, 
it may be remarked that its derm is thick and dense, and lies on a layer of 
salivary glands; that it is provided with simple conical papille, and is 
covered by stratified pavement epithelium. (It is sometimes streaked with 

igment. 
ar Wt cea tees are: the labial or orbicularis, the sphincter of the 
buccal aperture, and common to the two lips; in the upper lip, the aponeu- 
rotic expansion of the supermazillo-labialis, the musculo-fibrous tissue 
which separates this expansion from the cutaneous integument, and the 
terminal insertion of the supernasalis-labialis and_ the great supermaaillo- 
nasalis ; in the inferior lip, the tuft of the chin and its suspensory muscles— 
the posterior intermediates (levatores menti). All these muscles having been 
studied in detail in the Myology (page 217), there is no necessity for their 
i i ribed. 
sie Na teats Me form an almost continuous laver between 
the mucous membrane and the labial muscle. They are little secretory 
organs, similar in their structure an to the salivary glands, and will - 
i n these come under notice. : 

‘a Tee a nerves.—The blood is carried to the lips by the palato- 
labial, and the superior and inferior coronary arteries. It is returned a ihe 
heart by the satellite veins of the two last vessels. The lymphatics are very 

he glands between the branches of the lower jaw. 
numerous, and pass to the g . } he ficial 
The nerves are of two kinds: the motor, which are given off from the aoe 
nerve, and are distributed in the muscular tissue of the lips to cause its 


332 THE DIGESTIVE APPARATUS IN MAMMALIA. 


contraction; the sensitive nerves, which are furnished by the maxillary 
branches of the fifth encephalic pair, are distinguished by their number and 
considerable volume, and are nearly all buried in the cutaneous integument, 
to which they communicate an exquisite sensibility. 

Funorrons.—The lips serve for the prehension of solid and liquid food ; 
they retain it in the mouth after its introduction thereto, and likewise pre- 
vent the escape of the saliva. They ought also to be regarded, especially 
the upper lip, as very delicate organs of touch. 


2. The Cheeks. (Fig. 110.) 


These are two membranous walls, which inclose the mouth laterally. 
In the interior of the buccal cavity they are limited: behind, by the 
posterior pillars of the tongue; in front, by the lips, with which they are 
confounded around the commissures; above and below, by the groove 
formed by the gingival mucous membrane, where it is reflected from the 
molar arches on to the cheeks. 

The greatest diameter of the cheeks is antero-posterior, like that of the 
cavity it incloses. Their vertical diameter is very narrow, especially 
behind ; in the anterior region, however, it can assume a certain amplitude 
by the separation of the jaws. 

Srrucrure.—The cheeks are formed by the buccal mucous membrane, 
external to which we find muscular tissue and glands. Vessels and nerves 
pass through these parts for the conveyance of nutritive fluids, sensibility, or 
the stimulus to contractility. 

1. Mucous membrane.—The external face of this membrane is united in an 
intimate manner to the buccinator muscle, and to the inferior molar glands. 
Its free face presents, at the level of the third superior molar tooth, the 
buecal opening of the parotid duct, pierced at the summit of a variable- 
sized tuber On the face of each dental arcade there is also remarked a 
linear series of little salient points, analogous in their constitution to the 
large parotideal tubercle; these are the excretory orifices of the molar glands. 
Its structure is the same as the mucous membrane of the lips, (It is of a 
pale colour, and sometimes stained in patches with pigment.) 

2. Muscular tissue-—This 1s the buccinator or alveolo-labialis muscle 
already described. It may be remembered that the external face of this muscle 
is covered by the masseter, the superior molar glands, and the skin; while the 
internal responds to the mucous membrane and the inferior molar glands. 

3. Glands.—These are two masses of glandular lobules, known as the 
molar glands. They will be described with the salivary glands. 

Vessels and nerves.—The external maxillary, coronary, and buccal arteries 
carry blood to the cheeks. The veins empty themselves into the satellite 
branches of these arteries. 

The lymphatics proceed to the submaxillary glands. The nerves are of 
the same kind, and proceed from the same source, as those supplying the lips: 
being the seventh pair of encephalic or facial nerves for the muscular layer, 
and the fifth pair for the integuments (with filaments of the sympathetic for 
the circulation and the labial glandules). 

Funcrrons.—The cheeks are very active agents in mastication, by con- 
stantly pushing the aliment, through the action of the buccinator, between the 
dental grinding surfaces. 


3. The Palate. (Fig. 148.) 


Preparation.—Separate the head from the trunk; saw through the branches of the 


THE MOUTH. 333 


maxilla above the angle of the jaw, and from the crown of the last molar tooth, so as to 
pass between the curtain of the soft palate on the one part, and the base of the tongue on 
the other, leaving the latter organ adherent to the lower jaw. This last should bo 


removed from the upper jaw by cutting through the masseter and alveolo-lubial muscles, 
and so exposing the hard and soft palates in such 


amanner as to render easy the special dissections Fig. 148. 
necessary for their study. These dissections are 7 
limited to the removal of the mucous layer 
covering the deep venous network, and to 
the partial excision of this, which allows the 
artery and palatine nerves to be seen. (See 
figure 148.) 


The palate (hard palate), palatine arch, 
or upper wall of the mouth, is circum- 
scribed, in front and on the sides, by the 
superior dental arcade, and limited, behind, 
by the anterior border of the soft palate. 
It is a parabolic surface, exactly repre- 
senting, in its configuration, the bony 
palate (Fig. 21). 

On its face is remarked a median 
groove, which partitions it into two equal 
divisions, and which commences quite in 
front, at the base of a small tubercle. 
Curved transverse furrows, twenty in 
number (Leyh gives from sixteen to 
eighteen), divide each of these halves 
into an equal number of salient arches, 
whose concavities are turned backwards, 
and which become narrower and less 
marked as they are more posterior. 
(These arches and furrows aid in retain- 
ing the aliment which the tongue carries 
towards the palate during deglutition). 

Srructurz.—The palatine lies on the 
bony vault formed by the palatine and 
supermaxillary bones. It includes in its 
structure: | 

1. A fibrous membrane, applied to the 
bone just mentioned, which sustains a re- 
markably-developed venous network con- 
stituting a veritable erectile tissue, and 
gives to the palate a greater or less 
degree of thickness, according to its state 
of turgescence (Fig. 148, 1). 

2. A mucous layer, extremely adherent, THE HARD AND SOFT PALATE. 
by its deep face, to the preceding tissue, The mucous membrane has been removed 
and of a whitish aspect in the horse. The from the right side, and, with the 


corium, formed entirely of connective glandular layer, from the soft palate — 
: ‘1, The ridges of the palatine mucous 
membrane; 2, Venous network of the deep layer, which is cut through at the 
external side to show the palatine artery, 3, accompanied by the filaments of the 
palatine nerve; 4, Cartilaginous digitation, over which passes and is inflected the palatine 
artery; 5, Aponeurosis of the soft palate; 5’, Terminal extremity of the tendon of the 
external tensor palati, forming by its expansion the staphylin aponeurosis; 6, The 
palato-pharyngeus ; 7, Circumflexus palati; 8, Staphylin nerves. 


Boe 


a 
8 


334 THE DIGESTIVE APPARATUS IN MAMMALIA. 


tissue, shows numerous conical papille, especially at the posterior part of 
the palate. The epithelium fills up the depressions between the papilla ; it 
is stratified and squamous, and remarkable for the great thickness of its 
horny layer. ° . 

3. Two voluminous arteries —the palatine or palato-labials—lodged in the 
bony fissures of the palatine roof. ‘Lhese arteries proceed parallel to one 
another, and unite in front by anastomosing to form a single trunk, which 
enters the incisive foramen. It is of importance to know their disposition in 
a surgical point of view, as care ought to be taken not to wound them when 
abstracting blood from the palate. The blood carried by these arteries 
arrives in the deep-seated erectile membrane, and is finally removed by two 
very short venous trunks, which do not pass with the palato-labial arteries into 
the palatine canal, but only into the palatine fissure. 

4, Sensory nerves which accompany the arteries, and are derived from the 
superior maxillary branch of the fifth pair of cranial nerves. 

Functions.—The palate has a passive, but important, share in mastica- 
tion and deglutition; furnishing the tongue, as it does, with a firm basis in 
the movements it executes when passing the food between the molar teeth, 
and in carrying the alimentary mass backwards to the pharynx. 


4. The Tongue. (Figs. 149, 152.) 


Preparation.—1. By means of a strong saw without a back, make an antero-posterior 
and vertical section of the head, in order to study the general disposition of the tongue. 
2. From another head remove the lower jaw, leaving the tongue in the intermaxillary 
space, to examine the external conformation of the organ (see the dissection of the 
palate). On a third head, kept for the study of the muscles, these parts are exposed in the 
following manner: The masseter is entirely removed, and the cheek is detached from the 
lower jaw and folded back on the upper jaw ; then the branch of the inferior maxilla is sawn 
through transversely, at first behind, next in front of the molar teeth : the upper piece of 
bone should be detached by luxating it behind the temporo-maxillary articulation, after des- 
troying the capsular ligament and dividing the insertions of the pterygoid muscles. With 
regard to the inferior piece, it is reversed in such a way as to put the line of the molars 
downwards, and the inferior border of the bone upwards in the bottom of the inter- 
maxillary space. ‘lo do this it is sufficient to separate the buccal mucous membrane from 
the mylo-hyoideus muscle, proceeding from above to below. The dissection thus 
prepared, serves not only for the study of the muscles of the tongue, but also for those of 
the deep salivary glands, the pharynx, larynx, guttural pouches, the nerves and arteries 
of the head, ete. It is always better, in order to facilitate this dissection, to keep the 
jaws apart by fixing a piece of wood or bone between the incisor teeth immediately after 
the death of the animal. 


The lingual canal.—The inferior wall of the mouth (or floor), circum- 
scribed by the lower alveolar arches, forms an elongated cavity named the 
lingual canal (or space), which lodges the organ designated the tongue. This 
canal occupies, in its anterior third, the superior face of the body of the lower 
maxilla. For the remainder of its extent, it is formed by a double groove, 
which is directed to the bottom of the mouth, at the sides of the tongue. It 
exhibits the sublingual crest and the barbs, of which we will speak when 
describing the sublingual and maxillary glands. 

Situation of the tongue—The tongue occupies the whole length of this 
elongated cavity, and thus extends from the back part of the mouth to the 
incisor teeth, lying in the intermaxillary space, where it rests on a species of 
wide sling formed by the union of the two mylo-hyoidean muscles. 

External conformation.—It is a fleshy organ, movable in the interior of 
the buccal cavity, and almost entirely enveloped by the mucous membrane 
which lines that cavity. In Solipeds, it forms a kind of triangular pyramid, 


oe eae ee 


+s ses a ll abla ba ag 


THE MOUTH 835 


depressed from side to side, fixed to the os hyoides and the inferior maxilla 
by the muscles which form the basis of its structure, or by the tegumentary 
membrane which covers the organ. 


_ Its form permits it to be divided, for the study of its external disposition, 
into three faces, three borders, and two extremities. 

The superior face or dorsum of the tongue, narrower in front than behind, 
is roughened by numerous papille which give it a downy aspect. Two of 
these papille are remarkable for their enormous volume, their lobulated 
appearance, and the situation they occupy at the bottom of two excavations 
placed side by side, near the base of the organ; they are named the lingual 
lacunse, or foramen csecum of Morgagni. This face responds to the palatine 
arch or roof, when the jaws are together. The lateral faces, wider in the 
middle of the tongue than at its extremities, are limited by the internal 
surfaces of the maxillary branches. Onthem are seen several large papille, 
and the orifices of some lingual glandule. 

These two faces are separated from the former by two lateral borders, 
which correspond to the superior alveolar arches when the mouth is exactly 
closed. With regard to the third or inferior border, its existence may be 
said to be fictitious; by it enter the muscles which constitute the substance 
of the tongue, and it is by it, also, that the organ is fixed at the bottom of the 
intermaxillary space. 

The posterior extremity, or base of the tongue, is limited, in the interior of 
the mouth, by a furrow which borders the base of the epiglottis. It presents 
a thick, median, mucous fold, plaited in different ways, and carried over the 
anterior aspect of the epiglottic cartilage. Two other folds, more anterior, 
also formed by the buccal membrane, unite with the soft palate on each 
side the base of the tongue; these are the posterior pillars of the organ 
(or the glosso-epiglottic ligaments of Man), and comprise in their thick- 
ness a voluminous collection of glands. Behind these pillars are two 
triangular spaces, included between the velum pendulum palati and the 
base of the tongue, each of which has an excavation perforated with open- 
ings, a veritable amygdaloid cavity, which represents the amygdalz (tonsils) 
of Man and the Carnivora; it is a kind of common confluent for the 
numerous glandule accumulated outside the mucous membrane which lines 
this excavation. 

The anterior extremity of the tongue is quite independent from the 
middle of the interdental space, and moves freely in the interior of the buccal 
cavity: it is also termed the free portion of the tongue, in opposition to the 
remainder of the organ, which is named the fixed portion. This free portion 
is flattened above and below, and slightly widened or spatulated. Its 
superior face is plane, or nearly so, and prolongs that of the fixed portion. 
The inferior, slightly convex, and perfectly smooth, is continuous with the 
lateral faces of the organ, and rests on the body of the maxillary bone ; it is 
fixed to that bone by a median fold of mucous membrane, the anterior pillar, 
or freenum lingue. The borders, in joining each other in front, describe a 
parabolic curve which is in contact with the incisive arches. _ 

Srructurr.—The tongue offers for study, in regard to its structure : 
1, The mucous membrane enveloping the organ; 2, The muscular tissue which, 
in reality, forms its mass; 3, The vessels and nerves distributed to it. 

1. Mucous membrane.—This membrane, a continuation of that lining the 
mouth, is folded at the bottom of the canal on the sides of the tongue, covers 
the upper surface of the organ, and envelops the whole of its free portion. 
Its derm or corium has not the same thickness throughout, but is incom- 


336 THE DIGESTIVE APPARATUS IN MAMMALIA. 


parably thinner and less dense on the sides of the fixed portion and the 
inferior plane of the free part; on the dorsum of the tongue it is difficult to 
cut it. Its deep face receives the insertion of a large number of the muscular 
fibres of the organ, and for the greater part of its extent it adheres in the 
most intimate manner to these fibres; though its adherence is not so close 
at those points where it is in contact with the labial glandules. 

Its superficial face is not smooth, but shows a prodigious quantity of 
minute prolongations or papille, which, according to their shape, are dis- 
tinguished as filiform, fungiform, and calyciform papille. 

The filiform papille are formed by thin prolongations terminating in a 
point, each being covered by an epithelial sheath which greatly increases its 
dimensions. They are simple or composite, having at their summit 
secondary prolongations, much smaller, and provided also with an epithelial 
covering. These filiform papille are largest on the middle part of the 
dorsum of the tongue, where they present a tufty appearance; towards the 
point of the organ they are imbedded in epithelium, and are scarcely 
apparent in the minute elevations on its surface. 

The fungiform papille (p. capitate) are club or sponge-shaped elevations 
of the derm, attached to the membrane by a short pedicle. Their surface is 
convex and smooth, or studded with filiform papillae. They are scattered 
irregularly over the dorsum of the tongue, among the filiform papille, and 
are most numerous on the posterior third of its surface. 

The calyciform papille (fossulate, circumvallate, or lenticular papille) are 
really fungiform, but instead of projecting above the free surface of the derm, 
they are placed in a depression of this membrane. They are surrounded 
by a slightly-elevated ring, within which is a narrow fossa around the 
pedicle of the papilla; several papille may be contained within one cup- 
shaped cavity. They only exist at the base of the tongue, where two of 
their number, very developed and composite, correspond to the blind holes of 
Morgagni (foramen cecum). At the base of a certain number of the fungi- 
form and calyciform papille is a band of adenoid tissue. 

It is generally believed that these three kinds of papillae have each a 
distinct function; the filiform are to retain the alimentary and sapid sub- 
stances on the surface of the tongue; the fungiform are tactile organs, and 
the calyciform are gustatory. 

2. Muscles—Beneath the mucous membrane, on the dorsal surface of 
the tongue, is a cylindrical fibrous cord which sometimes attains the thick- 
ness of a large goose-quill. This cord is situated in the median plane, 
near the middle part of the organ, and is from 2 to 3 inches long. It may 
be considered as a fibrous support to the muscular tissue, and it sometimes 
directly adheres to the deep surface of the tegument. At other times, it is 
only connected with that membrane by a very short lamellar prolonga- 
tion, and is then buried a little deeper among the fibres of the superior 
muscular layer. 

(The German hippotomists designate this the cartilage of the tongue. Tt 
is only found in Solipeds, and was first described by Brith], who gave it this 
designation. Leyh states that it is composed of dense fibro-cartilage, 
‘surrounded by cellular and adipose tissue; that it is from 4 to 7 inches 
long, and 3ths to 1 inch in thickness; and that it commences about an inch 
from the anterior appendix of the hyoid bone.) 

A similar cord, but not so strong or well defined, is sometimes found at 
the inferior surface of the free portion of the tongue. 

Intrinsic muscles—In studying the proper substance of the tongue in 


THE MOUTH, 327 


te 


two sections, one vertical and longitudinal, the other transverse, there is 
seen, under the dorsal mucous membrane, a layer of red fibres, very close in 
their texture, and very adherent to that membrane. Amongst these fibres 
there are some which affect a longitudinal direction, but the majority are 
vertical or transverse, and all are interlaced in the most intimate manner. 
It appears as if this layer (the lingualis superficialis of Man) was perfectly 
independent of the other muscular fibres, whose insertion it receives. It 
also forms a portion of those which writers have named the intrinsic muscles 
of the tongue, and which comprise a superior and inferior, a transverse and a 
vertical lingualis muscle. An attentive examination, however, readily shows that 
the fibres proper to this submucous layer are continuous with those which, 
coming from a point situated beyond the tongue, form the muscles named, in 
consequence, extrinsic, and that they are only the prolongations of these. 
This division of the tongue into two orders of muscular fasciculi does not, 
for this reason, possess the importance generally accorded to it, 

Extrinsic muscles——If the muscular fibres of the tongue appear to be one 
mass in the superior layer just referred to, it is not so when they are 
followed beyond. this layer; on the contrary, we see them separate from one 
another, and even admit between them—at least in the fixed portion—a 
certain amount of adipose tissue, which is particularly abundant towards the 
base, where it forms a mass called the fatty nucleus of Baur; then they 
collect into fasciculi, or perfectly distinct muscles. 

In Solipeds, these muscles number five pairs; 1, The stylo- or Kérato- 
glossus ; 2, The great hyo- or basio-glossus; 8, The genio-glossus; 4, The 
an hyo-glossus (the superior lingual of some authorities); 5, The pharyngo- 
glossus 


STYLO-GLOSSUS. 


(Synonyms.—The hyo-glossus longus of Percivall. Kerato-glossus externus—Leyh. 
The stylo-glossus of Man.) 


This is a very long riband-shaped band, formed of bright-red parallel 
fibres, and extending from the styloid bone, or large branch of the os hyoides, 
to each side of the free extremity of the tongue. 

It originates on the external surface of the large hyoideal branch, near 
its inferior extremity, by a very thin aponeurosis; and terminates near the 
tip of the tongue in expanding over the inferior surface and borders of the 
organ, and confounding its fibres with those of the opposite muscle. 

In the fixed portion of the tongue, this muscle responds: outwardly, to 
the mylo-hyoideus, sublingual gland, lingual nerve, and the Whartonian 
duct; inwardly, to the genio-glossus and great hyo-glossus muscles, The 
whole of its free portion is covered by the buccal membrane. 

In contracting, this muscle pulls the tongue towards the back of the 
mouth, and inclines it to. one side when acting independently of its fellow 
on the opposite side (Fig. 149, 1.) 


GREAT HYO-GLOSSUS OF BASIO-GLOSSUS. 
(Synonyms.— Hyo-glossus brevis—Percivall. Hyo-glossus—Leyh.) 
A wide muscle, flattened on both sides, thicker than the preceding, and 
composed of fibres passing obliquely forward and upward, the longest of which 


are anterior. . 
Its origin occupies the whole side of the body of the os hyoides, from the 


extremity of the cornu to that of the anterior appendix. Its fibres, after 


338 THE DIGESTIVE APPARATUS IN MAMMALIA, 


becoming detached from this point of insertion, are insinuated beneath the 
preceding muscle, spread out under the mucous membrane covering the 
lateral aspect of the tongue, and for the most part are reflected inwards, nearly 
so the superior face, to constitute the transverse fibres of the organ. 

It is in relation, outwardly, with the mylo-hyoideus, stylo-glossus, the 
great hypo-glossal nerve, Wharton’s duct, and the lingual mucous membrane ; 
inwardly, with the small hyo-glossus, the small branch of the os hyoides, the 
pharyngo-glossus, genio-glossus, lingual artery, the terminal divisions of the 
glosso-pharyngeal nerves, and great and small hypo-glossals. (Fig. 149, 2.) 

It retracts the tongue in depressing its base, according as it acts singly 
or simultaneously with its fellow. 

(In 1850, Brith] described as the middle descending stylo-glossus, a long, 
narrow muscle arising from the lower éxtremity.of the inner face of the 
styloid bone, or large branch of the os hyoides, and terminating near the 
tip of the tongue, where it is covered by the hyo-glossus. It has since been 
described as the internal or small Kérato-glossus. Its action is the same as 
the stylo-glossus. ) 


GENIO-GLOSSUS. 
(Synonym.— Genio-hyo-glossus—Percivall.) 


This is a beautiful muscle, whose fibres are disposed like a fan in 
the vertical and median plane of the tongue. 

It originates from the inner surface of the lower jaw, near the symphysis, 
by a tendon parallel to that of the genio-hyoidous. From this tendon are 
detached a multitude of divergent fibres which pass backwards, upwards, and 
forwards, to reach the upper surface of the tongue and become continuous 
with the vertical fibres of the submucous layer. 


Fig. 149. 


MUSCLES OF THE TONGUE, SOFT PALATE, AND PHARYNX. 


1, Stylo-glossus; 2, Great hyo-glossus; 3, The same, covered by the submucous 
layer formed by the expansion of the small hyo-glossus; 4, Genio-glossus; 5, 
Pharyngo-glossus ; 6, Pterygo-pharyngeus; 7, Hyo-pharyngeus; 8, Thyro-pha- 
Heaney, Ce ia esis 10, @sophagus; 11, 12, Tensors palati; 13, 

ylo-hyoideus ; yoideus magnus; 15, Genio-hyoideus; 16, Hyo-thyroideus : 
17, Sterno-thyroideus : 18, Crico-thyroideus. ‘i Ceres 


THE MOUTH. 


The two genio-glossi lie together on the median 


339 


plane of the tongue, 


except towards their origin, where they are constantly kept apart by adipose 
tissue. Their inferior border responds to the genio-hyoid muscles, and their 


anterior fibres are partly included between the two 
mucous layers of the franum lingue. They are re- 
lated, by their external face, to the basio- or great 
hyo-glossus, the stylo-glossus, the sublingual gland, the 
lingual artery, and the terminal branches of the three 
lingual nerves. 

The action of the genio-glossus is complex; accord- 
ing to the portion of its fibres which contract, it will 
carry the tongue forwards, pull it into the buccal 
cavity, or draw it downwards into the floor of the mouth. 
(Fig. 149, 4.) 

SMALL HYO-GLOsSUS. 
‘ eee superior of Man. (Lingualis of Perci- 
vat. 

Under this name is described a thin band, formed of 
parallel fibres, which is exposed immediately on remov- 
ing the mucous membrane, with the subjacent glands, 
from the base of the tongue. This band arises from the 
inner side of the articulation uniting the body of the os 
hyoides to its small branch. It passes above the trans- 
verse muscle of that bone, which it crosses perpendi- 
cularly, is surrounded at this point by a great mass of 
adipose tissue, and is prolonged directly forward, be- 
neath the lingual mucous membrane. Its fibres then 
vanish, either on the superior aspect of the tongue or 
on its sides, or they descend obliquely in crossing the 
direction of the hyo-glossus, to jom the superior border 
of the stylo-glossus (Fig. 149, 3). 

(This muscle contracts and retracts the tongne.) 


PHARYNGO-GLOSSUS. 
(Synonym.— The palato-glossus of Man.) 


A rudimentary muscle formed of parallel fibres, 
which, from their origin on the lateral wall of the 
pharynx, pass outside the articular angle of the branches 
of the os hyoides, and between the hyo-glossus and genio- 
glossus, mixing with, and intercrossing their fibres. 

3. Labial glands—The numerous glands of the 
tongue may be divided into racemose (or lobulated) 
‘glands, and closed follicles (or follicular glands.) 

The racemose glands are spread on the sides and base 
of the tongue. Near its upper border they form two 
rows, which are rendered visible by the presence of a 
small tubercle placed beside each of them. At the base 
of the tongue they are found beneath the fungiform and 
calyciform papilla, as well as beneath the layer of 
incloged follicles which lines the isthmus of the fauces. 

At the entrance to this passage, the Imguai mucous 
membrane is mammillated, and each elevation has an 


Fig. 150. 


4 
Pe cteees (9 


Ey 


ONE LOBE OF A RACE- 


MOSE GLAND, 


1, Casing of connective 


tissue; 2, Excretory 
duct; 3, Glandular 
vesicle, or acini. 


Fig. 151. 


FOLLICULAR GLAND 
FROM THE ROOT OF 
THE TONGUE, 


1, Epithelium; 2, Pa- 


pillaof mucous mem- 
brane; 3, Cavity of 
the follicle; 4, In- 
vesting coat of the 
gland composed of 
connective tissue; 5, 
Fibro- vascular ma- 
trix, forming its pare 
enchyma, and con- 


taining, 6, 6, the 
closed capsules or 
follicles. 


340 THE DIGESTIVE APPARATUS IN MAMMALIA. 


orifice. This arrangement is connected with the presence, at this part of 
the tongue, of the closed follicles, which are more or less voluminous and 
aggregated, and separated from the muscles by a continuous layer of race- 
mose glands. They are composed of a casing of condensed connective, and a 
mass of adenoid tissue, which has in its centre a cavity that communicates 
with the orifice above the follicle, and is lined by the lingual epithelium 
minus its horny layer. . 

4, Vessels and nerves—The tongue is supplied with blood by two 
arteries, the lingual and sublingual; the blood is removed by three large 
veins, two of which enter the external maxillary, and the third the internal 
maaillary vein. The lymphatics constitute a very fine superficial network, 
whose emergent branches pass to the submaxillary glands. The nerves 
are the lingual, the glosso-pharyngeal, and the great hypo-glossal ; the latter 
is a motor nerve, and consequently supplies the muscles; the others are 
exclusively sensitive, and are distributed more particularly to the mucous 
membrane. 

Founctions.—The tongue serves for the prehension of liquids in all 
animals, and for solid aliment in the Ox. It concurs, with the jaws, in pro- 
pelling the substances to be crushed between the molar teeth during masti- 
cation; and it is, besides, one of the essential organs of deglutition. It is 
able to play this important and complex part through the varied movements 
it can execute in the interior of the mouth; and the extent of these move- 
ments demands a moment’s notice. They are of two kinds: those which 
influence only the form of the organ, and those which cause it to submit to 
various displacements. They result in either compressing it from side to 
side, above to below, or curving it longitudinally, and even transversely. 
These movements are principally, but not exclusively, due to the action of 
the intrinsic fibres ; they are perfectly independent of the movements which, 
as a whole, produce the total displacement of the tongue. With regard to 
these latter, they may result in carrying the tongue beyond the mouth, or 
withdrawing it into that cavity, inclining it to one side, raising it against 
the palate, depressing it on the floor of the intermazillary space or, finally, 
lifting it towards the pharynx. It is worthy of remark that these move- 
ments do not alone result from the action of the proper lingual muscles 
above described ; those belonging to the os hyoides, to which is attached 
the lingual appendix, concur also in producing them. But this appendix is 
not the only organ thus attached to the hyoidea! apparatus; the larynx and, 
through its intermediation, the pharynx, are placed in the same conditions, 
and are obliged to follow, like the tongue, the movements of the bony frame- 
work supporting them. 

There consequently results between these three organs a remarkable 
unity of action, which is readily explained by the part they all take in the 
one common act of deglutition. 


5. Soft Palate. (Figs. 148, 152.) 


Preparation—The soft palate is studied: I, On the antero-posterior and vertical 
section of the head (fig. 152); 2, On the portion intended to show the interior of the 
pharynx (see the preparation of this region); 3, On the portion represented in fig. 148, 
the mode of dissecting which has been indicated at page 333; in removing the mucous 
membrane and glandular layer, the fibrous membrane and the two intrinsic muscles are 
exposed. The extrinsic muscles should be studied with those of the pharynx. 


_ Sttuatton—Form.—The soft palate (palatum molle, velum pendulum palati) 
is suspended like a partition between the mouth and the pharynx, and by its 


THE MOUTH. 311 


posterior border cireumscribes the orifice which establish i 
tion between these two cavities, ee a 
* This partition, which continues the palate i in j 
posteriorly, represent 

— cian . Tee valve, oblique from above ni ie sea ion 
o behind, much longer than it is wide, and exhibiting f, dy te 
ae ee g A ibiting lor study two faces 

The inferior or anterior Jace, turned towards the mouth, shows longi- 
tudinal folds and transverse ridges, with multitudes of orifices belonging to 
the submucous glandule. On its sides it is united to the base of the tongue 
by means of two thick mucous columns, designated the posterior pillars 
of the tongue. The Superior or posterior face constitutes the anterior wall 
of the pharynx ; it only exhibits some very slight longitudinal ridges. 


Fig, 152. 


MEDIAN LONGITUDINAL SECTION OF THE HEAD AND UPPER PART OF NECK. 

1, Upper lip; 2, Premaxilla; 3, Hard palate; 4, Tongue; 5, Septum nasi; 6, Nasal 
bone; 7, Palatine arch; 9, Pterygoid bone; 10, Epiglottis; 11, Entrance to the 
Eustachian tube; 12, Arytenoid cartilage, 13, Cricoid cartilage; 14, Esophagus ; 
15, Frontal bone and sinus; 16, Cerebrum; 17, Corpus callosum ; 18, Cerebellum ; 
19, Sphenoid bone; 20, Medulla oblongata; 21, Cervical ligament ; 22, Spinal 
cord; 23, Occipital bone; 24, 24, Atlas; 25, 25, Dentata; 26, Trachea, 


The two lateral borders are inserted into the walls of the two cavities 
which the soft palate separates. The anterior border, continuous with the 
palate, is attached to the palatine arch, and follows the curve described by 
it. The posterior border, the only free one, has a concave form, and 
closely embraces the base of the epiglottis, which is most usually found 
reversed on the pcsterior surface of this curtain. This border is continued 
at its extremites by two thin prolongations, which can be followed on the 
lateral walls of the pharynx to the cesophageal infundibulum, above which 
they unite in the form of an arch. These prolongments are named the 
posterior pillars of the soft palate, in contradistinction to the two mucous 
folds at the base of the tongue, which constitute, by their relation to this 
partition, veritable anterior pillars. This posterior border concurs to cir- 

25 


342 THE DIGESTIVE APPARATUS IN MAMMALIA. 


cumscribe what is named the isthmus of the fauces, an aperture constantly 
closed, in consequence of the great development of the soft palate ; it is only 
dilated for the passage of the alimentary substances passing into the pharynk. 
The isthmus of the fauces is, therefore, not merely an opening; it is a 
passage which has for its inferior wall the base of the tongue as far as the 
epiglottis ; for its upper wall the anterior face of the soft palate; and for 
its sides the posterior pillars of the latter. 

Srructurz.—To give the most simple idea of the structure of the soft 
palate, it might be said that the mucous membrane of the palate and that of 
the floor of the nasal cavities are prolonged behind the palatine arch, 
parallel to one another, and become joined towards the free border of this 
curtain; and it might be further shown that, in the space between these two 
mucous membranes, there is a fibrous membrane, muscles, a glandular layer, 
vessels, and nerves; besides these, there are no other elements in the organi- 
sation of the soft palate. They may te studied in the following order: 1, 
Fibrous membrane ; 2, Muscles; 3, Mucous membranes ; 4, Vessels and nerves. 

1. Fibrous membrane (Fig. 148, 5).—This membrane, remarkable for its 
power of resistance, forms #rcal framework for the soft palate, of which it only 
occupies the anterior moiety. Itis attached in front of the palatine arch, 
and is prolonged posteriorly by a particular musclo, the palato-pharyngeus. 

2. Muscl:s.—Of these muscles, which are all pairs, there are those which 
constitute a layer situated in the middle of the soft palate itself, and 
representing the intrinsic muscles ; these are the pharyngo-staphyleus (palato- 
pharyngeus) and the palato-staphyleus (circumfleaus palati). The others, the 
peristaphyleus,—external and internal (tensors palati, external and internal), 
are only inserted into the organ by their terminal extremities and therefore 
act as extrinsic muscles. 


PHARYNGO-STAPHYLEUS. (Tig, 148, 6). 
(Synonym.—Palato-pharyngeus—Percivall.) 


In removing the mucous and glandular layers which cover the anterior 
face of the soft palate, there is exposed a wide and thin muscular fasciculus 
succeeding the fibrous layer behind, and occupying the posterior half of the 
entire organ. The fibres of which this muscle is composed, confounded on 
the median line with those of the muscle on the opposite side, are directed 
backwards and outwards, the most posterior following the curve of the free 
border of the curtain. Arriving near the lateral border, they are re- 
flected upwards, passing between the pharyngeal mucous membrane and 
the middle constrictor of the pharynx, with which it appears to be con- 
founded posteriorly ; but with a little attention it can be followed to the 
superior border of the thyroid cartilage, into which it is inserted after 
making a somewhat long track under the mucous membrane of the pharynx. 

This muscle stretches the curtain, and draws its free border from the 
cesophageal infundibulum during pharyngeal deglutition. 


PALATO-STAPHYLEUS. 
re iy chine Stephylem— Girard, Circumflexus palati—Percivall. The azygos uvule 
Man. 

A small, elongated, cylindrical, bright-red muscle, in opposition, on the 
median line, to that of the other side, and extending over the inferior surface 
of the preceding, from the palatine arch to the free border of the soft palate, 
which it pulls forward and upward to dilate the isthmus of the fauces, It 


THE MOUTH. 343 


originates by a small glistening tendon, not from the palatine, but from the 
uvular aponeurosis (Fig. 148, 7). The fascia which the two muscles form 
is for the most part covered, in its middle portion, by the fibres of the 
tensores palati. : . 


PERISTAPHYLEUS EXTERNUS. 
(Synonyms.—Tensor palati—Percivall. The circwmflexus of Man.) 


. 


This is a small, elongated muscle, depressed on both sides, bulging in its 
middle, thin and tendinous at its extremities, and extending obliquely for- 
ward and downward from the styloid process of the temporal bone, where 
it has its origin, to the pterygoid trochlea. Its terminal tendon glides 
and is inflected inwards on this pulley, to be afterwards spread out and 
confounded with the fibrous framework of the soft palate, which causes this 
framework to represent an expansion of the tendon. 

The muscle is covered outwardly by the pterygoidei muscles; it 
responds, internally, to the next muscle, which separates it from the 
Eustachian tube. 


It is atensor and depressor of the aponeurosis of the soft palate 
(Fig. 149, 11). 


PERISTAPHYLEUS INTERNUS. 
(Synonyms.—Stylo-pharyngeus—Percivall. The levator palati of Man., 


This is formed by a pale and thin band, which originates with the 
preceding muscle, descends between it and the Eustachian tube, passes 
beneath the superior constrictor of the pharynx, then below the mucous 
membrane of the pharynx to reach the soft palate, where it expands on the 
anterior or posterior surface of the palato-pharyngeus, beneath the glandular 
layer, its fibres becoming mixed, on the median line, with those of its fellow. 

This is an elevator of the soft palate (Fig. 149, 12). 

3. Glandular layer.— This layer is comprised between the fibrous 
membrane and the anterior mucous layer, becoming thinner as it is pro- 
longed over the intrinsic muscles ; it does not extend to the free border of the 
organ. It is thickest on each side of the median plane, where it forms two 
lobes which appear on the anterior aspect of the soft palate as an elongated 
ridge, much more marked in the Ass than the Horse. It is worthy of notice, 
that the glandular granulations composing this layer throw all their secre- 
tion into the mouth—that is, on the anterior face of the septum. — 

4, Mucous membranes.—The soft palate is covered on both its surfaces 
by two mucous layers, one anterior, the other posterior, united, as has been 
remarked, at the free border of the organ. The anterior is continuous, 
above, with the mucous membrane of the hard palate; on its sides, with 
that which covers the base of the tongue. In structure it is the same as 
the buccal membrane; its epithelium is stratified pavement. The other 
layer is nothing more than the pituitary membrane extended over the 
posterior surface of the septum, and thence to the lateral surfaces of the 
pharynx. It will be more fully described with the latter. 

5. Vessels and nerves.—The soft palate is supplicd with blood by the 
accending pharyngeal and internal maaillary arteries. The nervous filaments 
this partition receives emanate from the fitth pair of cranial nerves (superior 
maxillary branch), and from Meckel’s ganglion; they form the posterior 


alate ve (Fig. 148, 8). ; 
ss said ae Pee ie act of deglutition, the soft palate is raised to 


344 THE DIGESTIVE APPARATUS IN MAMMALIA. 


enlarge the isthmus and allow solids or liquids to pass through. The descrip- 
tion given of this septum permits us to understand how it plays the part of a 
valve in rising freely while the alimentary bolus or mouthful of fluid passes 
from the mouth into the cesophagus, across the pharyngeal vestibule, but 
never allows the matters which have once entered the cesophageal canal to 
return into the buccal cavity. Also why, when any obstacle is opposed to the 
descent of aliment into the cesophagus, after it has cleared the isthmus of 
the fauces, or even when the animal vomits, the matters arrested in their 
passage or expelled from the stomach are ejected by the nasal cavities, 
after flowing over the posterior surface of the soft palate. This disposition 
of the pendulous curtain, in forming a complete partition which hermeti- 
cally seals the orifice of communication between the mouth and pharynx, 
likewise sufficiently explains why, in normal circumstances, Solipeds respire 
exclusively by the nostrils. 


6. The Teeth. 


Passive agents in mastication, the teeth are hard organs, bony in 
appearance, implanted in the jaws, and projecting into the interior of the 
mouth to bruise or lacerate the solid alimentary substances. 

Identical in all our domesticated animals, by their general disposition, 
their mode of development, and their structure, in their external con- 
formation these organs present notable differences, the study of which offers 
the greatest interest to the naturalist. For it is on the form of its teeth 
that an animal depends for its mode of alimentation; it is the régime, in 
its turn, which dominates the instincts, and commands the diverse modifica- 
tions in the apparatus of the economy; and there results from this law of 
harmony so striking a correlation between the arrangement of the teeth 
and the conformation of the other organs, that an anatomist may truly say, 
“Give me the tooth of an animal, and I will tell you its habits and 
structure.” 

Compelled by the limits of our task to confine ourselves to the purely 
descriptive part of the dental apparatus, we cannot stop to notice the 
interesting physiological considerations on which this principle is founded; 
but will begin at once the anatomical study of the teeth by indicating their 
general characters, before examining them successively in all the domestic- 
ated species. 

A. GENERAL CHARACTERS OF THE TEETH —-GENERAL Disposition.—The 
teeth are fixed in the jaws, and ranged one against the other in such a way 
as to form two parabolic arches opening behind, and interrupted on each 
side by what is called the interdental space. Distinguished into superior 
and inferior, like the jaws to which they belong, these arches come in contact 
with one another in a more or less exact manner when the mouth is perfectly 
closed. 

Those teeth which are placed altogether in front, at the middle of the dental 
arches, are named incisors or incisive teeth ; the others, situated behind these, 
and always numbering two for each jaw, are called the canine teeth or tusks ; 
while the designation of molars is given to those which occupy, in the more 
retired portion of the buccal cavity, the lateral parts and extremities of the 
dental arches. 

Exrernan Conrormation.—Each tooth represents, when completely 
developed, an elongated polyhedron, which has sometimes a pyramidal 
form, and at others that of a cone or a parallelopiped. 


THE MOUTH. 345 


A portion of the tooth is buried and solidly implanted in one of the 
alveolar cavities of the maxillary bones; this is the root or imbedded portion, 
(or fang). The other portion, circumscribed at its base by the gum, leaves 
the alveolus to project into the interior of the mouth, forming the crown 
o free pon The narrow constriction between the crown and root is named 
the neck. 

The fang is perforated at its inferior extremity by one or more excavations 
(cavitas pulp) which penetrate deeply into the substance of the tooth, and 
admit into their interior the vasculo-nervous papilla, simple or ramified, 
known by the name of the bulb or dental pulp. 

The crown, the portion submitted to friction during mastication and, 
consequently, to wear, offers the most varied forms: sometimes it is shaped 
like a very acute cone; at others, it is divided into several tubercles more 
or less salient; and sometimes, again, it carries at the extremity of the tooth 
a wearing surface more or less plane and regular. 

Srrvcture.—Three essentially different substances enter into the structure 
of all the teeth: the zvory, enamel, and cement; to which ought to be added 
the soft parts. the pulp, gum, and alveolo-dental periosteum. 

lvory.—The ivory, or dentine, has the harduess of bone, is of a whitish- 
yellow colour, and is rendered brilliant in places by its nacrous reflection. It 
forms the principal mass of the tooth, enveloping everywhere the pulp cavity. 

Examined by aid of the microscope, this substance is found to be 
channeled by a multitude of minute, undulating, and branching canals 
(dental tubulz) imbedded in amorphous matter—the fundamental eubstance. 


SS 
Ne 


: —s 


SECTION THROUGH THE FANG OF A MOLAR TOOTH. 


a, u, Dentine traversed by its tubuli; 6, b, Interglobular, or nodular layer; 
c, c, Cementum. 


The tubuli, or canaliculi, extend from the dental cavity to the inner face 
of the enamel; single at their origin. they soon bifurcate, and again anasto- 
mose several times during their slightly-undulating course. They terminate 
in a cul-de-sac, or in irregular cavities situated beneath the enamel, and 
named the interglobular spaces of Czermak (forming the interglobular or 
nodular layer). These canals have a thin proper wall, and contain a dental 
fibre, which very probably is a continuation of the pulp-cells. The 
fundamental substance (or matrix) is amorphous, and nof very abundant ; in 


346 THE DIGESTIVE APPARATUS IN MAMMALIA. 


its mass are deposited the saline molecules which give the dentine its bony 


consistency. (These molecules are deposited in lamella, concentric with 
the pulp cavity. Nasmyth considcrs the fibres to be rows of minute opaque 
points arranged in a linear series (baccated fibres), and to be merely the 
nuclei of the ivory cells, the interfibrous substance being the remainder of 
the cell filled with calcareous matter.) 

Its chemical composition much resembles that of bones. After remaining 
in dilute hydrochloric acid for several weeks, it comports itself like them, by 
giving up the calcareous salts with which it is impregnated to the acid 
solution, and becoming soft like cartiluge; submitted to the action of boiling 
water it yields gelatine. 

Enamet.—The enamel extends in a layer over the bony substance of the 
free portion of the tooth, whose exterior it entirely envelops; it is prolonged 
over the fang in some animals, and in several kinds of teeth it dips by the 
crown into the interior of the organ to a very great depth. It is brilliantly 
white, and so hard that it strikes fire like steel. 

Its microscopic structure is very interesting, the enamel being composed 
of small prismatic hexagonal rods, 1-5000th of an inch in diameter, and 
notched on their faces. (wing to this notching, the prisms are intimately 
united to each other. They form several layers which cross each other at 


Fig. 154. 


A. TRANSVERSE SECTION OF ENAMEL, SHOWING ITS HEXAGONAL PRISMS 5 
B. SEPARATED PRISMS. 


an acute angle, though in each layer they are exactly parallel to oe another. 
By immersing the enamel in dilute hydrochloric acid, there is detached from 
its surface a fine amorphous membrane or cuticle of the enamel. 

(The chemical composition of enamel appears to be 96-5 per cent. of 
earthy matter, and 35 of animal substance. The first consists of 
phosphate of lime, with traces of fluoride of calcium, carbonate of lime, 
phosphate of magnesia, and other salts. The rods are directed vertically 
on the summit of the crown of the tooth, and horizontally at the sides.) 

Crmunt.—(Cementum, substantia ostoidea, cortical substance, or crusta 
petrosa).—The cement is spread in a non-continuous layer over the external 
surface of the cnamel and dentine. It is accumulated in large quantity 
in the substance of some tecth, as will be noticed when speaking of the 
incisors in the Horse and the molars of the Herbivora. 

The structure and properties of this substance differ in nothing from 
the structure and properties of the spongy tissue of bone. In a physio- 
logical state, the cement does not contain any Haversian canals, (It 


THE MOUTH. 347 


contains, sparingly, the lacune and canaliculi which characterise true 
bone: those placed near the surface have the canaliculi radiating from the 
side of the lacune towards the periodontal membrane; and those moro 
deeply placed join with the adjacent dental tubuli. In the thicker portions 
of the crusta petrosa, the lamelle and Haversian canals peculiar to bone 
are also found. As age advances, the cementum increases in thickness, 
and gives rise to those bony growths, or exostoses, so common in the tecth 
of the aged; the pulp cavity also becomes partially filled up by a hard 
substance, intermediate between dentine and bone (osteo-dentine—Owen ; 
secondary dentine—Tomes). It appears to be formed by a slow conversion 
of the dental pulp, which shrinks or even disappears— Gray.) 

Dental pulp.—Vhe pulp, or papilla, is formed by a 
fibrillar and nuclear mass that fills the internal dental 
cavity. It receives blood-vessels and nerves, and is 
enveloped in a very thin membrane which is entirely 
composed of several layers of beautiful cylindrical or 
prismatic cells, the most superficial of which send 
fibrillar prolongations into the dental tubuli. Towards 
the base of the papilla, this membrane assumes thu 
texture of connective tissue, and is reflected upwards on 
the fang of the tooth to line the alveolus, and join the 
gum at the origin of the crown. 

Gum.—The gum is a portion of the buecal mucous 
membrane surrounding the neck of the tooth, and con-  * 
curs in consolidating it in the alveolar cavity. Its 
structure is that of the membrane to which it belongs, 
being a thick dermis furnished with papille and tesselat.d 
epithelium. It does not contain any glands. 

Alveolo-dental periostewm.—This scarcely differs from 
the ordinary periosteum except in being a little softer. 
Tt lines the alveolus and covers the cementum of the fang. 

DeveLopmenT.—Each tooth is developed in the 
interior of a closed sac named the dental follicle, and 
lodged in an excavation in the maxillary kones. The 
sac presents, according to the species of animal and kind 
of teeth, numerous variations, which we cannot stay to 
consider here; but must confine ourselves merely to BL AGNIVIED SECTIONOF 
brief sketch of the general and constant characteristics “4 canine TOOTH, 
of its organisation. SIIOWING ITS INTI- 

The dental follicle is constituted by an external en- mare srructuru. 
veloping membrane of a cellulo-vascular nature (Fig. 1, Crown; 2, 2, Neck; 
156, a). It shows at bottom the simple or compound oe Eene, or pe 
papilla which at a later period is termed the dental Deve ene ee 
pulp (B); this organ, destined for the seerction of the th. Vessels and 
dentine, then fills nearly the whole of the follicle. nerves communicate 
In its upper part is observed the enamel organ, or germ arith fe pulp 6, 6, 
(enamel membrane), formed by a prolongation of the rea oe 
gingival epithelium, and connected with the latter by a 7, 7, Enamel; 8, 8 
small mass of cells named the gubernaculum dentis. Coment: 

Most frequently there is, opposite the bottom of the ; 
follicle, one or more papille which, in some cases, adhere by their 
whole length to one of the lateral walls of the follicular sac, and the free 


extremitics of which cross those of the dentine papille, or are buried in 


348 THE DIGESTIVE APPARATUS IN MAMMALIA. 
a kind of cup hollowed on the summit of the latter appendages (c). These 
are covered by the membrane of cylindrical cells mentioned above (p). 

With regard to the enamel organ, its internal face also presents a layer 
of cylindrical cells. 

Tt is in the interval between these two papillary systems, that the dental 
substance is deposited as ina mould, consequent on a process of secretion 
and transformation, the mechanism and progress of which are somewhat 
complicated. The dentine is produced by the metamorphosis of the super- 
ficial cells of the dental germ. These cells send out ramifying prolongations 
which constitute the tubuli of the dentine, and those of the middle layer 
secrete an intertubular amorphous substance in which the earthy salts are 
deposited from without inwards. The enamel is deposited on the dentine, 
and results from the transformation of the cylindrical 
cells of the germ into enamel prisms. The cement is, 
in its turn, deposited either on the enamel or the 
dentine after their formation, and is produced, like 
the bony tissue, by the internal face of this (perio- 
dontal) sac, which has become alveolar periosteum. 
This development will be alluded to in the chapter on 
the foetus. 

When formed by the process above indicated, the 
tooth pierces its follicle and appears in the interior of 
the mouth, after having traversed the table of the 
maxillary bones, if there is any, and the gingival 
membrane. (When the calcification of the different 
tissues of the tooth is sufficiently advanced to enable 
it to bear the pressure to which it will be afterwards 
subjected, its eruption takes place, the tooth making 
its way through the gum. The gum is absorbed by 
the pressure of the crown of the tooth against it, 
which is itself pressed up by the increasing size of 
the fang. Concurrent with this, the septa between 


Fig. 156. 


THEORETICAL SECTION OF 
THE DENTAL SAC OF A 
PERMANENT INCISOR IN 
THE HORSE. 

A, Proper membrane of the 
sac; B, Dental pulp; c, 
Papilla of the external 


cavity (pit) of the tooth, 
a dependency of the ena- 
mel membrane ; D, Epi- 
thelial layer of the den- 
tine membrane; E, Cy- 
lindrical cells of the 
enamel membrane; F. 
Dentine; G, Enamel. 
The secretion of the ce- 
ment is not supposed to 
have commenced. 


the dental sa¢s, at first fibrous in structure, soon ossify, 
and constitute the alveoli; these firmly embrace the 
necks of the teeth, and afford them a solid basis of 
support—Gray.) Though it has so far become esta- 
blished in its functions, the process of growth in the 
tooth has not yet ceased. The pulp lodged in the 
internal dental cavity, and charged with the formation 
of the ivory or dentine, continues its functions: inces- 
santly depositing new layers on those which were 


originally secreted. The dental cavity gradually 
diminishes in extent; the papilla becomes atrophied, and finishes by disap- 
pearing altogether at a period of life more or less advanced, according to 
the kind of teeth and species of the animal. 

In considering the entire dental apparatus, with regard to its develop- 
ment, very interesting differences are remarked in the progress and period 
of evolution ; differences which have been made available for ascertaining 
the age of animals, but the details of which would be out of place here. 
It may only be noted, that all animals have two successive dentitions: the 
first, composed of a certain number of tecth designated the caducous (tem- 
porary, deciduous, or milk-teeth—caduques, decaying or frail), because they 
are soon shed and give place to others which are stronger and more solid 


THE MOUTH. 349 


(and also because they appear while the animal is yet sucking); the second, 
comprising the latter, are named replacing teeth (remplagantes), with new, 
non-deciduous teeth which are not replaced, and are therefore named 
persistent teeth. (The replacing and persistent teeth are generally included 
by us in the term permanent.) 

B. TreetH oF So.rpeps.—The dentition of adult Solipeds is composed 
of from 386 to 40 teeth, thus distributed in each jaw: male, 6 incisors, 2 
canines, 12 molars; female, 6 incisors, 12 molars. With regard to the 
first dentition, it comprises the incisors and three anterior molars only, the 
canine teeth and the three posterior molars being persistent. 

The latter teeth—those of the second dentition—offer in their develop- 
ment a common, but very remarkable character, rarely met with in the other 
animals. They are thrust up from the alveoli during the entire life of 
the animal, to replace the surfaces worn off by friction ; so that the crown 
is formed successively by the various portions of the fang, each of which 
issues in its turn from the alveolar cavity. 

Incisors.—These are so named because they serve, particularly in the 


Fig. 157. 
b 


THIN SECTION OF THE INNER PORTION OF THE DENTINE AND OF THB SURFACE 
OF THE PULP OF AN INCISOR TOOTH. 
Portion in which calcification is complete, showing separate globular masses at 
the line of junction with the uncalcified substance, 6; at care seen oval masses 
of germinal matter (cells), with formed material on their outer surface; 4d, 
Terminal portions of nerve fibres. 


Herbivora, for the incision (incido, to cut) of the food. They are arranged 
in the segment of a circle, at the extremity of the jaw, and are distinguished 
by the names of pincer, intermediate or lateral (mitoyennes), and corner 
teeth. The pincers are the two middle tceth, the intermediates the next, 
and the corners occupy the extremities of the incisive semicircle. ; 

The general form of these teeth is that of a trifacial pyramid, presenting 
an incurvation whose concavity is towards the mouth. The base of this 
pyramid, formed by the crown, is flattened before and behind; the 
summit, or extremity of the fang, is, on the contrary, depressed on both 
sides; the shaft of the pyramid offers. at different points of its height, a 
series of intermediate conformations which are utilised as characteristics 
of age, the continual pushing outwards of the teeth bringing each of them 
in succession to the frictional surface of the crown (Fig. 159, 1). 

Examined in a young tooth which has completed its evolution, the free 
portion exhibits: an anterior face, indented by a slight longitudinal groove, 
which is prolonged to the root; a posterior face, rounded from side to side; 


350 THE DIGESTIVE APPARATUS IN MAMMALIA. 


two borders, of which the internal is always thicker than the external ; 
lastly, the surface of friction (table). The latter does not exist in the tooth 
which has not been used; but in its stead is found two sharp margins 
circumscribing a cavity named the eaternal dental cavity (or better, i- 
fundibulum). This cavity terminates by a conical cul-de-sac, which 
descends more or less deeply into the sub- 
stance of the tooth. The margins are dis- 
tinguished into anterior and posterior; the 
last, less elevated than the first, is cut by one 
or more notches which are always deepest in 
the corner teeth, It is by the wear of these 
margins that the surface of friction is formed, 
and in the centre of which the infundibulum 
persists during a certain period of time 
(Fig. 159, 2). 

The fang is perforated by a single aper- 
ture, through which the pulp of the tooth 
penetrates into the internal cavity (Fig. 
159, 3, ¢). 

In the composition of the incisor teeth is 
found the three fundamental substances of 
the dental organ. The dentine (Fig. 159, 3, b) 
envelops, as has been shown, the pulp cavity. 
That which is deposited in this cavity after 
the complete evolution of the tooth, to replace 
the atrophied pulp, has always a yellower 
tint than the dentine of the first forma- 
tion ; it forms on the table of the tooth the 
mark designated by Girard the dental star 
(Fig. 159, 4, ¢). The enamel covers the 
dentine, not only on its free portion, but 
also on the roots of the incisors; it is not 
prolonged, however, to their extremities. It 
is doubled into the external dental cavity, 
lining it throughout (Fig. 159, 3, a); and 
when the surface of friction is established, 
there can be perceived a ring of enamel 
surrounding that surface, and an internal ring 
circumscribing the infundibulum: the first 
circle forms what is called the encircling 
enamel ; the second, the central enamel (Fig. 
159, 4, a, 6). 

In the virgin tooth, the latter is con- 
tinuous with the external enamel, and passes 

Neent0® over the border which circumscribes the 

ee < eee Shed tee7% entrance to the infundibulum. 'The cement 
Consult figure 21 for the dentition of is applied over the enamel like a protecting 
the upper jaw. varnish; but it does not exhibit the same 
thickness everywhere: on the salient portions 

it is extremely thin, and does not even exist when the tooth has been 
submitted for some time to the friction arising from the contact of 
the aliment, the lips, and the tongue. It is more abundant in depressed 
situations, as in the longitudinal groove on the anterior face, and particularly 


THE DENTITION OF THE INFERIOR 


THE MOUTH. 


at the bottom of the infundibulum. Nevertheless 
in this cul-de-sac is not always the same; we have seen it sometimes almost 
null, and on the other hand we possess inci 


351 


are not aware that, up to the present time 
these differences when calculating the progress of wear ; 


but it may be 
er the period at 


INCISOR TEETH OF THE HORSE. DETAILS OF STRUCTURE. 


i ich is indicated the general shape of a permanent incisor, and the 
» eg ers shaeansiale asnmiad by the dental table in consequence of 
Friction and the continued pushing outwards of these teeth ; 2, A virgin oe 
anterior and posterior faces; 3, Longitudinal seabion of a virgin tooth, ne 2 
to show the internal conformation and structure. Not to comple the en 
the external cement, and that amassed in the infundibulum, ne not ee 
exhibited. 4, Transverse section for the same purpose; «, ee ing enamel; 
6, Central enamel; ¢, Dental star; d, Dentine; 5, Deciduous tooth. 


acteristics just indicated belong to the deciduous teeth 

aig. eee that ae are smaller than the permanent; that Rats 

of a ‘shining milky-white colour, due to the thinness or absence of the 

ee trosa; that they show at the point of union between the free 

i Fad the Toot a constriction named the neck ; that their crown is finely 

Este one not cannular, on the anterior face; that the external cul-de-sac 
y 


352 THE DIGESTIVE APPARATUS IN MAMMALIA. 


(infundibulum) is shallow; and that they are not constantly pushed out- 
wards from their cavities, their growth ceasing when they begin to be used. 
When the replacing teeth appear, they do so a little behind the temporary 
ones, whose shedding they cause by gradually destroying their roots, which 
at last become only a long and very thin shell of dentine. 

The follicle in which the incisor teeth are developed shows only two 
papille ; one for the secretion of the dentine, lodged in the internal cavity 
of the tooth, and hollowed into a cup-shape at its free extremity; the other 
is contained in the external cul-de-sac (Fig. 156, a. B. c). 

Tusxs, Faves, or Caninr Terru.1— The tusks of Solipeds only exist in 
the male; it being quite exceptional to meet with them in the female, and 
even then they are rarely so strong as in the male. 

“These teeth are four in number, and are placed one at each side of the 
jaws, a little behind the incisors, to which the lower canines are much 
nearer than the upper. Between them and the first molar there is left a 
considerable space, which constitutes the bar of the inferior jaw. 

“The free portion of the tusk, slightly curved and thrown outwards, 
particularly in the lower jaw, offers two faces: an external and an internal, 
separated from one another by two sharp borders inclined to the inner side, 
and meeting in a point at the extremity of the tooth. The external face, 
slightly rounded, presents a series of fine strie, longitudinal and parallel. 

“The internal face has a conical eminence in its middle, whose point 
is directed towards that of the tooth, and is separated from each border 
by a deep groove. 

“The fang of the tusk, more curved than the free portion, bears 
internally a cavity analogous to that of the root of the incisors, and 
like it, this diminishes and finally disappears as it advances in age; but it 
is always relatively larger, because of the absence of the infundibulum in 
the canine teeth. 

“The form we have described for the tusks is that which they present 
while still young. As the Horse grows older they lose their whiteness, 
and become worn in an irregular manner, and this most frequently by the 
action of the bit or snaffle; for the difference in position of these teeth in 
the two jaws doves not allow of friction between them. 

“The canine tecth are not shed, and grow but once. Some veterinarians, 
and among them Forthomme and Rigot, have witnessed instances in which 
they were replaced ; but the very rare exceptions cannot make us look upon 
these teeth as liable to be renewed. We must not, however, confound with 
these exceptional cases the shedding of a small spicula or point, which, in 
the majority of Horses, precedes the eruption of the real tusks.” 

“The structure of these teeth is much simpler than that of the incisors; 
consisting, as they do, of a central mass of dentine hollowed by the pulp 
cavity, and covered by an external layer of enamel, on which is deposited a 
little cement. 

“The disposition of the developing follicle is in harmony with the 
simplicity of structure of the tusks; at the bottom there is a simple and 
conical papilla for the internal cavity; on the inner wall, a double longi- 
tudinal ridge, on which are moulded the ridge and grooves oh the internal 
face of the tooth.” 

Motar Trera.— The molars are twenty-four in number—six in each 
side of each jaw. There are also sometimes supplementary molars met with 


1 The quotations included within inverted commas are from M. Lecoq’s ‘Traité de 
PExtérieur du Cheval et des Principaux Animaux Domestiques,’ : 


THE MOUTH. 353 


in front of the true ones, and which may be four in number; 
small teeth, having but little cee to the others, are en, sate 
shed with the first deciduous molar, and are not replaced. ? 
f 8 Generally considered, the molar arcades have not the same disposition 
in both jaws. Wider apart in the superior one, they form » slight curve 
whose convexity is outwards. In the inferior jaw, on the contrary, the iw 
arcades separate in the form of 2 V towards the back of the mouth: Instead 
of coming in contact by level surfaces, the molars meet by inclined planes 
and in such a way that the internal border is higher than the external 
in the inferior molars, while the opposite takes place in the superior. 

. Like the incisors, each molar presents for study a free and a fixed 
portion. 
pete The free portion, nearly square in the upper molars, longer than wide 
in the lower, shows at the external surface of the former two longitudinal 
grooves, the anterior of which is the deepest, and which are continued on 
the encased portion. This is not the case with the inferior molars, which 
have but one narrow, and frequently an indistinct, groove. 


Fig. 160. 


PROFILE OF THE UPPER TEETH OF THE HORSE, MORE ESPECIALLY INTENDED TO 
SHOW THE MOLARS; THE FANGS HAVE BEEN EXPOSED. 


a, Molar teeth; 6, Supplementary molar; ¢, Tusk; d, Incisors. 


“The internal face in both jaws only shows one groove, and that but 
little marked; it is placed backwards in the upper molars, and is most 
apparent towards the root. 

“The anterior and posterior faces are in contact with the corresponding 
faces of the adjoining molars, except at the extremities of the arcades, where 
the isolated face is converted into a narrow border. 

«With regard to the table of the tooth, it inclines, as we have already 
mentioned, outwards in the lower jaw, and inwards in the upper; a circum- 
stance which prevents the lateral movements of the jaws taking place with- 
out separation of the incisors, which separation removes them from friction.” 
In the virgin molar this face is completely covered with enamel, and 
irregularly undulated. In it may be recognised the entrance to the two 
infundibular openings, which are prolonged in the interior of the organ to 
the extremity of the root, and which are almost entirely filled with cement 
at the period when the tooth has completed its evolution; they are only 
vacant before the secretion of this crusta petrosa. In the tooth which has 


354 THE DIGESTIVE APPARATUS IN MAMMALIA 


been worn, this frictional surface assumes a particular aspect, which will bo 
indicated with most advantage to the student by examining the structure of 
the molar. . 

“The root, if examined a short time after the eruption of the free 
portion, looks only like the shaft of the latter, without any appear- 
ance of*fangs, and has internally a wide cavity. It is not until the tooth 
begins to be pushed from the alveolus and its crown to become worn, that 
its fangs are formed; these are at first hollow, and afterwards filled, as well 
as the cavity of the tooth, by the formation of a new quantity of dentine. 
From this time the fangs cease to grow; but the tooth, constantly projected 
beyond the alveolar cavity, allows the walls which inclose it to contract; so 
that, in extreme old age, it happens that the shaft, completely worn away, 
instead of the tooth, leaves several stumps formed by the fangs. ; 

“The molars of the two jaws exhibit a variety of roots. In the molars 
terminating the arcades, either above or below, or at the extremities of these, 
there are three; while the intermediate molars have four fangs in the upper 
jaw, and only two in the lower. 

‘‘The molars are separated from each other by their imbedded portion, 

particularly at the two extremities of the arcade; an arrangement which 
strengthens them by throwing the strain put upon the terminal teeth towards 
the middle of the line.” 
' The structure of the molars resembles that of the incisors, though it is 
much more complicated. The internal cavity is extremely diverticulated, 
and enveloped by the dentine. The enamel is applied in a layer over it, and is 
doubled in its external culs-de-sac exactly as in the incisors. There is also 
on the table of the tooth which has been worn, an external covering of 
enamel, and two circles, or rather two irregular polygons, of central enamel 
circumscribing the two cavities. In the superior molars, these bands of 
enamel represent a Gothic B, having a small appendix on the loop nearest 
the entrance to the mouth. This figure is modified in the teéth of the 
lower jaw, the enamel of the infundibuli being continuous, on the inner side, 
with the external enamel. The cement is extremely abundant, and in the 
upper molars its total quantity nearly equals that of the dentine; it 
accumulates in the culs-de-sac and on the external 
covering of enamel, where it partially fills up the 
flutings on the faces of the crown. Prolonged 
steeping of a molar tooth in hydrochloric acid 
easily permits the isolation of these elements. 

Owing to the arrangement above described, the 
section of an adult molar tooth, naturally repre- 
sented by the surface of friction (Fig. 161), 
exhibits, outwardly, a layer of cement; next, the 
external enamel; between this and the central 
enamel, the dentine, always yellower, and sometimes 
euicoumnpels Bernier even black in the middle; lastly, the enamel 

see a on Rts bands of the infundibuli, and the crusta petrosa 
TOOTH. filling them. As these enamel bands are much 
A, pean Baal Ren harder than the other substances, they are worn 
nternal enanls ne} more slowly and stand out in relief on them. 
oe — en ™ ‘The table of the tooth has also, for this reason, the 
appearance of a veritable mill-stone, and is admi- 
rably disposed for the trituration of those fibrous substances on which the 
animal usually feeds, 


Fig. 161. 


THE MOUTH. 355 


The follicle which develops these three elements of the molar tooth, 
offers at the bottom an enormous papilla divided into several lobes, which 
lie together for their whole length; lodged in the internal dental cavity, it 
gradually decreasss, like the papilla in the other kinds of teeth, as the 
cavity becomes diminished by the formation of new dentine. Opposite to 
it are two long papille, which occupy the enamelled infundibuli. 

“Tt was believed for a long time that the molars of Solipeds were all 
persistent teeth. This error, founded on the authority of Aristotle, was so 
deeply rooted, that although Ruini, towards the end of the sixteenth century, 
had discovered the existence of two temporary molars, Bourgelat did not 
believe it when he founded the French Veterinary Schools, and was only con- 
vineed when Tenon had proved by specimens, in 1770, that the first three 
of each arcade are deciduous. 

“The replacement of these twelve molars is not at all like what happens 
with the incisors. The molar of the adult grows immediately beneath the tem- 
porary one, and divides its two fangs into four, until its body is reduced toa 
simple plate and falls off, allowing the contracted summit of the permanent to 
appear ; and this grows up until it is soon on a level with the others in the row. 

“The first replacing molar is always a little more elongated than that 
which it succeeds, and it most frequently expels at the same time the sup- 
plementary molar; so that if forty-four teeth be developed in the male 
Horse, it is very rare that they are all present at the same time.” 


7. The Mouth in General. 


We will now consider, as a whole, the cavity whose various parts have 
been studied in detail, and examine, successively, its general disposition, 
capacity, and mucous membrane. ; 

General disposition and capacity of the mouth.—The mouth being eclon- 
gated in the direction of the head, offers a great antero-posterior diameter, 
and two small diameters—one vertical, the other transverse. The first 
extends from the base of the epiglottis to the anterior opening of the mouth ; 
the second, from the palate to the floor of the mouth; and the third, from 
one jaw to the other. When the jaws are in contact, the space included 
between these limits is divided into two regions: one central, the other 
peripheral. The first is circumscribed by the dental arches; the second 
is comprised between these arches on the one side, and the cheeks and 
inner aspect of the lips on the other. It may, therefore, be remarked, 
that the capacity of the mouth is almost null in these regions. The cheeks 
and lips, in reality, le almost exactly against the alveolar arches, and the 
tongue, in contact with the palate by its superior surface, almost entirely 
fills the central region. If the jaws separate from one another, and the 
cheeks recede from the dental arcades, the cavity of the mouth becomes 
enlarged in proportion as these movements are extensive. It must be 
remembered that the separation of the jaws is effected in an angular manner, 
and that the dilatation produced in the mouth by this. movement is greater 
before than behind, the opening of the angle comprised between the two 
jaws being directed towards the entrance of the cavity. 

Mucous membrane.—The walls of the buccal cavity are covered by a 
tegumentary membrane, which we have hitherto only examined in parts in 
the different regions it ous but which, ; 1s ee i aia here a 

i inuous layer, the mucous membrane of the mouth. 
ee anal is etna with the external skin at the margin of the 


356 THE DIGESTIVE APPARATUS IN MAMMALIA. 


buccal opening ; followed from this point into the interior of the cavity it 
lines, it is seen to spread itself at first over the internal surface of the lips, 
then to be prolonged backwards on the cheeks as far as the posterior pillars 
of the tongue. lf it is examined above and below, to the bottom of the 
groove which corresponds to the point of insertion of the lips and cheeks, 
it is seen to cover the maxillary bones and envelop the base of the teeth, 
where it constitutes the gums. From the superior dental arcade, it extends 
over the palatine arch and the soft palate. And from the inferior arcade, 
jt descends to the floor of the mouth, and is reflected over the tongue to form 
a covering for that organ. At the isthmus of the fauces it is continuous 
with the pharyngeal mucous membrane. 

The organisation of the mucous membrane of the mouth is perfectly in 
harmony with the digestive acts performed in that cavity. It is there 
where the alimentary substances, which are sometimes very hard, very 
resisting, and covered with asperities, are crushed ; and to escape inevitable 
injury, this membrane is protected by a very thick epidermis in those places 
which are most particularly exposed to the contact of these substances, such 
as the upper surface of the tongue, the palate, and the cheeks; even the 
corium or sub-epidermic layer, is also greatly thickened. But nature has 
not made this provision for the parts which are removed from the direct 
contact of alimentary matters; as, for example, on the lateral aspects of 
the tongue, where the buccal membrane is delicately organised. 

This membrane also shows, in its lingual portion, small organs for the 
gustation of savours, the perception of which is one of the most important 
preparatory acts of the digestive functions; as the sensation resulting from 
this appreciation constitutes an excitant to the desire for food, and also 
informs the animal of the good or bad properties of the substance introduced 
into the mouth. 


DIFFERENTIAL CHARACTERS IN THE MOUTH OF OTHER THAN SOLIPED ANIMALS, 


That the different regions of the mouth in the domesticated animals should offer some 
diversities will be readily conceived, as all are not submitted to the same régime, nor do 
they all live in the same manner. 

Ruminanrs. 1, Lips—The lips of the Ox are remarkably thick and rigid, and 
possessed of but little mobility, notwithstanding the great development of the muscles 
that move them; so that they only concur indirectly in the prehension of food, the 
tongue being charged with the largest share in this important task. The upper lip 
offers in the middle of its external surface a large patch destitute of hair, variously 
coloured in different animals, always humid in health, covered by small depressed 
eminences, and perforated by minute apertures, through which the secretion of numerous 
thick, yellow, subcutaneous glandules passes to the surface. This space, situated 
between the two nostrils, constitutes the muffle. (Around the muffle are a few hairs 
somctimes, of the nature of tentacule.) 

In the Sheep and Goat the lips are thin and very mobile, and take an active part in 
the prehension of food. The upper lip does not show any muffle, and is divided into 
two portions by a median groove. In the Sheep this groove is in reality a fissure; so 
that each half of the lip can be readily moved independently of the other. (The upper 
lip is covered with hair in both animals. The Goat has a long tuft of hair appended to 
its lower lip, the beard.) 

2. Cheeks—On the inner surface of the cheeks in the Oz, Sheep, and Goat, from the 
commissure of the lips to the first molar tooth, is a multitude of long, thick, conical 
papilla directed hackwards, Beyond, there are only small round elevations and a single 
row of large papille similar to the preceding, in a line with the upper molars, In the 
Sheep the mucous membrane is sometimes spotted black. 

3. Palute.—In the Ox, the palate is most extensive. Its posterior third is quite 
smooth, and the transverse ridges (bars) only occupy the anterior two-thirds. (They are 
usually sixteen in number.) They are not curved, but are cut into notches on their 
summit, which is inclined backwards. In the Sheep and Goat, as also in the Oz, is 


THE MOUTH, 357 
remarked, in front and in the middle, near the pad that replaces th inci 
a °. tbs A eu : ‘ 3 
eth e Te the stem of beers is ves forwards, al at the extemihy oF a ee 
8 @ very narrow aperture, the buccal i is wil 
be described with the nasal ey Sen een Hea onieoms easteks Diese 


be carried into the nostrils with ease. (Th f i i 
finer than in the Horse The valle fine ea he eee he ee a 
surface ; and at the root, on the middle line, is a somewhat deep groove. of its dorsal 

Hes aft Pelle de cee ts Goat is smaller, proportionally, than that of Solipeds. 
said, in a general manner, that Fis. 169 
the palatine prolongment is een 
sherter than in Solipeds. (The 
isthmus of the fauces is wider, 
however, and the amygdala, very 
developed, are situated in the 
two large depressions formed on 
the sides of the soft palate by 
the folding of the mucous mem- 
brane.) 

6. Teeth—The teeth of the 
Ox are thirty-two in number, 
twenty-four of which are molars, 
arranged as in the Horse, and 
eight incisors belonging to the 
lower jaw. The latter are re- 
placed in the upper jaw by a 
thick cartilaginous pad, covered 
by the mucous membrane of the 
mouth ; this pad forms the gum, 
and furnishes a bearing for the 
incisors of the lower jaw. Some- 
times, as in the Horse, there are 
found supplementary molars, 
which, if four in number, will 
make up the whole to thirty-six ; 
though they are never all present 
at one time, as the supplementary 
ones are shed before the molar 
dentition is completed. 

The composition of the Ox’s 
teeth is the same as those of the 
Horse, the only difference being 
in the arrangement of the several 
substances. 

Incisors. — “The _ incisors, 
eight in number, are placed en 
clavier (like a key-board) at the 
extremity of the kind of rounded 
shoulder-bone by which the max- 
illary bone terminates, forming 
around this point a perfect circle 
when they have acquired their 
full development. 1, Upper jaw, with a, the friction surface, and }, the 

“Instead of being fixed in external surface; 2, Lower jaw, with u, the dental 
the alveoli, as in Solipeds, they tables, and, 6, the external face. 
possess a certain degree of mo- oe ae : 
bility, sometimes mistaken for a diseased condition; this is necessary in order to 
prevent their wounding the cartilaginous pad of the upper jaw against which they 
press. They are divided, according to their position, into two pincers, two first inter- 
mediates, two second intermediates, and two corner incisors. 

“ach incisor offers for consideration two parts: one free, the other encased, con- 


26 


THE TEETH OF THE OX. 


358 THE DIGESTIVE APPARATUS IN MAMMALIA. 


stituting the root, and separated from one another by a very marked constriction—the. 
neck, This arrangement gives to the tooth the form of a shovel, the root representing 
the handle (fig. 163). . ; 

“The free portion, flattened above and below, and thinnest and widest towards its 
anterior extremity, presents two faces—an inferior or external, the other superior or 
internal; with three borders, an anterior and two lateral. 

“The external face, slightly convex, and milk-white in colour, is covered with fine, 

Fis. 163 undulating, longitudinal strie, which disappear 
g A with age, and leave the surface beautifully 
polished (fig. 163, a). 

“The internal face, flatter than the pre- 
ceding, presents in its middle a slight conical 
eminence, whose base widens an is terminated 
near the free extremity of the tooth, while its 
sides are circumscribed towards each border by 
a well-defined groove (fig. 163, a’). 

“The two lateral borders (the internal 
slightly convex in its length, the external 
slightly concave in the same direction) make 
the free portion appear as if thrown outwards. 
The anterior border is sharp, and slightly con- 
vex from one side to the other; it is the first 
part of the tooth destroyed by wear. 

“The root is rounded, slightly conical, and 
implanted in an alveolus of the same form; in 
youth, it shows at its extremity an opening 
communicating with an internal cavity analo- 
gous to that in the teeth of Solipeds, and pro- 


Free portion, external face, outer : the interior of tlie fi ar 
border; a’, Lid, internal face, outer oe es a 8 te Tree portion 
g. 163, b). 


border; b, Root; v, Neck; f, Anterior 
border; g, g’ Inner border. 


OX’S INCISOR TOOTH. 


Bs 


“Tn the virgin tooth, the enamel forms around 
: the free portion a continuous layer, thinnest on 
the internal surface, and extending very scantily over a part of the root. ; ; 

“The dentine composes the remainder of the organ, and the (pulp) cavity, which 
is originally a large space of the same form as the tooth, is filled, as the animal grows 
old, by new dentine, which, as in the Horse, hasa yellower tint than the primitive ivory. 

“When the cavity is completely filled, the tooth ceases to grow, and is not pushed 
beyond the alveolus during wear, like the teeth of the Horse. 

“ The incisor tooth has scarcely arrived at its perfect development before it begins to 
‘be worn. Its horizontal position, and its coming in contact with the pad on the upper 
jaw, exposes the anterior border and superior tace to friction, and consequent wear 

from before to behind. The wear, therefore, chiefly aftects this upper face, which really 
.forms the table of the tooth, and which Girard designated the avale. When use has 
- worn away the conical eminence and the grooves bordering it, the tooth is levelled. 

“ As wear goes on, there appears at first, and at the extremity of the tooth, a yellow 
“band, which is the dentine denuded of its enamel; and later, in this ivory a yellower 
transverse band shows itsclf. With increase of wear, this contracts, then widens, and 

finishes by forming a mark nearly square, and then round, which is nothing else than 
the recently-formed dentine that fills the pulp cavity of the tooth. It is a veritable 
‘dental star, analogous to that in the Horse’s tooth, and varying in form according to the 
incisor in which it appears. 

“In proportion as the teeth are used, they seem to separate from one another, 
although they still remain in the same places. This is becauve these teeth, in youth, 
only touched each other by their extremities, and as they became worn they decreased in 
width, and necessarily became separated to an extent varying with their degree of wear. 

“Finally, when the tooth has reached its last stage of wear, there only remains the 
root, the upper portion of which, becoming apparent by the retreat of the gum, stands as 
a es stump, very distant from those which form with it the remains of the incisive 
arcade. 

* The first incisors (or milk-teeth) of the Ox, like those of the Horse, are all deciduous, 
and differ from those which replace them by their smaller volume, less width, the 
transparency of their enamel, and their being more curved outwards. Their roots are 
much shorter, and are destroyed by the succeeding teeth. The two temporary pincers 
are always separated by a marked interval, depending on the thickness of the fibro- 
cartilage-in the maxillary symphysis during youth.” 


THE MOUTH. 359 


Motars.—“ As in Solipeds, the molars are six in each sine of the ja 
much smaller, and form a much shorter arcade, Their | ee ee 
being as uniform as in the Horse, but goes on augmenting from the first to the sixth - and 
to such a degree, that the space occupied by the three anterior molars is only about one- 
half of that required for the three posterior ones ; the last molar alone occupies near] 
four times as much space, lengthwise, as the first, y 

“Their wearing surface, constructed on the same system as that of the Horse’s molars 
presents eminences a little more acute.” 
aon arrangement of their three constituents is in principle the same as in the latter 

‘“ As in the Horse, the three front molars are deciduous, 

“The teeth of the Sheep and Goat are, like those of the Ox, thirty-two in number, 
divided into eight incisors and twenty-four molars, to which are sometimes added 
supplementary molars. 

“The incisors of the smaller Ruminants are not disposed like a key-board, as in the 
Ox, but stand up to furm a grip, resting against the pad on the upper jaw much more 
by their extremity than by their inner surface. 

“They are, besides, narrow, have scarcely any neck, and are fixed more solidly in the 
alveoli (fig. 164). 

“Their external face is white and polished, and is encased towards the gumina 
kind of black cement. 

“The internal face has two wide, longitudinal grooves, separated towards tle middle 
of the table by a simple ridge, which replaces the conical eminence of the Ox’s incisor. 
These grooves are nearly always lined with the black cement-like substance. 

“The incisors of the Sheep are, like the Ox’s, distinguished into temporary and 
replacing teeth; the first are known from the others by 
their smallness, and particularly by their narrowness. 

“The wear of the incisors in the Sheep, from their 
position, ought to take place nearer the anterior border 
than in the Ox; the dental star is observed more 
promptly, and always forms a narrower line from before to 
behind. 

“The absence of a neck in these teeth is the reason 
why they never appear to separate with wear, as has been 
remarked in the Ox. 

“The molars have the greatest resemblance, in their rNcISOR TEETH OF A SHEEP 
general form and relative proportions, to those of the Ox.” TWO YEARS OLD. 

Pig.—“1, Lips—In this animal the lips are widely The second intermediates and 
cleft. The lower is pointed and little developed; the upper dhe. comer incisors havenct 
is confounded with the snout, which will be described yet been replaced. 

‘with the nostrils.” (The upper lip las but little mobility.) 

“2. Cheeks.—These are small and thin, and the mucous membrane smooth. 

“3. Palate—Narrow and elongated, it is disposed as in the Horse. In front is seen 
the orifices of Jacobson’s canals.” (The transverse rilges are twenty to twenty-two in 
number, the anterior being larger than the posterior, and their free borders are united), 

“4, Tongue.—5. Soft Palaite—These two organs are the same as in the smaller 
Ruminants, except that the filiform papille are perhaps less developed.” (The isthmus 

"of the fauces is circular, and the posterior pillars are confounded with the mucous 
membrane at the upper part of the cesophagus. Its anterior surface has several conical 
eminences in the middle, and the amygdalie are little rounded elevations.) ae 

“6, Teeth—The Pig has forty-four teeth, which are divided into twelve incisors, 
four canines and twenty-eight molars” (fiz. 165). : 

“The incisors, six in each jaw, exhibit very remarkable differences between each 
other. ‘lhe pincers and the intermediates of the upper jaw offer, by their form and the 
cavity they show on their table, some analogy to those of the Horse. In the lower 
jaw, these teeth are straight. directed forwards, and bear some resemblance to the 
incisors of rodent animals, The gorner incisors of both jaws are isolated between the 
intermediate and canine teeth, and are not nearly so voluminous as the other incisors. 

“The tusks are very developed, particularly in the male, and cross each other during 
the life of the animal; they project from the mouth, and form a very dangerous weapon 
in the wild boar. The primary canines are deciduous like the incisors, : 

“The molars, seven in each row, increase in volume from the first to the last, which 
is very strong. Their tables hold a middle place, with regard to disposition, between 


Jarnivora and Herbivora. eee 
ba coe Lips-—The Carnivora, like the Pig, do not use their lips to grasp 


360 THE DIGESTIVE APPARATUS IN MAMMALIA. 


their food, and they are therefore thin, though movable. The upper lip of the Dog has 
a groove in the middle line, and it covers the lower lip more or less at the sides 
according to the breed. The lower lip is always scalloped on its free border near the 
commissures, which are very high. In the Cat, the hairy tentacule are collected on 
the upper lip into two long lateral tufts, the moustaches; they are very sensitive and 
EE athe Palate-—The cheeks resemble those of the Pig; the palate that of 
Ruminants. The mucous membrane is often stained by patches of pigment, especially on 
the palate.” (The latter is frequently quite black. The number of ridges varies from 
seven to nine. Jacobson’s canal opens behind the incisors.) _ 2 

“4, Tongue—This is thin and very movable. The papillae on its upper face vary 
somewhat in the Cat and Vog. In the former, the filiform papille on the anterior two- 


Fig. 165. 


THE TEETH OF THE PIG. 
1, Upper teeth, table surface ; 2, Lower teeth, table aspect; 3, Lateral view of the jaws. 


thirds of the tongue are covered by a very strong horny sheath, whose point is directed 
backwards. In the Dog these papille are less developed, and there are observed, more 
particularly, a number of composite filiform papilla whose divisions are very flexible. 
There also are found regularly disposed among these, white shining epithelial particles 
which correspond to the fungiform papilla. 

“ At the base of the tongue of Carnivora, and within the anterior pillars of the soft 
palate, are two elongated bodies with rounded extremities and a bosselated slippery 
surface; these are veritable amygdale, formed by an agglomeration of closed follicles. 

“5. Soft Palate.—In the Dog and Cat, the soft palate is very short, and the 
isthmus of the fauces wide. Consequently, these creatures breathe easily by the mouth, 
and expel matters by it from the stomach during vomiting. At its free border the soft 
palate shows a small prolongation, something like the uvula. 


THE MOUTH. 361 


_ “6. Teeth—The teeth of the D - i : inci 
canine acd daerke de nislee og are forty-two in number: twelve incisors, four 
. he incisors, six in each side of the jaws, are more developed in th i 
ane pres i ee ne as in the Horse, into pincer, intowmcliates a 
e cisors; the last being much st: in oa 
sella A ee el ig ronger than the preceding, and these again 
“Their free part presents, in the virgin tooth, three tubercles : i ich i 
» : a midd) 

strongest, and two lateral; these, together, are not unlike a trefoil or the ee 
fleur-de-lis, especially those in the upper jaw. On the internal face is remarked a table 
- slope, ee that of the Ox and Sheep, and separated from the root 

y a very distinct border whose extremities mark th i i 
Fak aerate A ee ar. e lateral lobes. This table is of no 


“The root, very developed, flattened on both sides, and separated from the free 


Fig. 166, 


GENERAL AND LATERAL VIEW OF THE pDoG’s TEETH. 


portion by a well-defined neck, is solidly encased in adeep alveolus. Its internal cavity 
is very promptly obliterated. 

“When the tooth is submitted to wear, the middle lobe is the first to disappear; so 
that it no longer resembles a trefoil (fig. 167). 

“The caducous incisors are much smaller and more pointed than the permanent 
ones; yet, like them, they show lateral lobes. At the period of their eruption these 
teeth are somewhat widely apart. 

“The fangs, or canine teeth, two in each Fig. 167. 
jaw, are very strong, elongated organs, conical 
in form, curved backwards and outwards, and 
placed immediately after the incisors. 

“The upper fangs are the thickest, and 
havea small space between them and the corner 
incisors, in which the inferior canines are lodged. 

“These teeth are deciduous, like the incisors, 
and are distinguished from the replacing ones 
by their being thinner and more elongated. 

“They are worn more or less quickly, ac- 
cording to the kind of food the animal obtains, 
and are sometimes broken in fighting. 

“The molars are distributed in the two ANTERIOR VIEW OF THE INCISORS AND 
jaws, twelve being fixed in the upper and four- CANINE TEETH IN A YEAR-OLD DOG. 
teen in the lower. Nearly all of them are ; 
terminated by somewhat acute lobes, proper for tearing animal food. The strongest 
in each jaw is, for the upper, the first back-molar or fourth in the row, and in the lower, 
the fifth: All in front of these are deciduous.” 


362 THE DIGESTIVE APPARATUS IN MAMMALIA, 


After their complete eruption from the alveolar cavities, the Dog’s teeth are no longer 
pushed outwards. They are remarkable for their brilliant whiteness, which they owe 
to the absence of cement on their covering of enamel. 

The Cat has thirty teeth: twelve incisors, four tusks, and fourteen molars, eight of 
which are in the upper, and six in the lower jaw. 

All these teeth are constructed on the same type as those of the Dog. The tusks are 
deeply striated on their external surface, instead of being smooth. 

(The importance of a correct knowledge of the period of eruption, shedding, replacing, 
and general wear of the teeth of the domesticated animals, as a guide to their age, 
induces me tc give the table on page 363 (from Leyh), as indicating at a glance the age 
at which the teeth appear, are shed, and replaced in the different creatures: 

Baumeister divides the successive evolutions in the wear of the tables of the Horse’s 
incisor teeth into four periods—from six years to extreme old age. ‘he first, the trans- 
versely-oval period, extends from six to twelve years; the round, from twelve to 
eighteen years; the triangular, from eighteen to twenty-four years, and the antero- 
posterior oval or triangular, from twenty-four years and upwards. Girard and other 
French authorities shorten these periods somewhat. The triangular period, for instance, 
only lasts from fourteen to seventeen years.) 


COMPARISON OF THE MOUTH OF MAN WITH THAT OF ANIMALS, 


The brevity of Man’s face influences the shape of the mouth; therefore it is propor- 
tionally shorter and wider than in the domesticated mammals. 


Fig. 168. 


MEDIAN ANTERO-POSTERIOR SECTION OF THE HUMAN FACE. 

a, Septum of nose, with section of hard palate below it; 6, Tongue; c, Section of 
soft palate; d, d, Lips ; u, Uvula; r, Anterior arch, or pillar of fauces; 7, Pos- 
terior arch ; ¢, Tonsil; p, Pharynx ; h, Hyoid bone; 2, Thyroid cartilage , n, Cricoid 
ee eles v, Glottis ; 1, Posterior opening of nares; 3, Isthmus 
aucium ; 4, Superior opening of larynx; 5, Passage into esophagus; 6, Orifice 
of right Eustachian tube, oe ears 


263 


THE MOUTH. 


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364 THE DIGESTIVE APPARATUS IN MAMMALIA. 


I. Lips.—The lips have a thick, free, everted border, They are lined by a rosy 
mucous membrane, which is insensibly continued inwards by the buccal membrane. 
The upper lip is limited by the nose and the naso-labial furrow; the lower is limited by 
the mento-labial groove. The first a in its middle the subnasal furrow. ‘Their 

is analogous to those of animals. 
a phate he cheeks are limited by the inferior border of the maxilla, the root of 
the ear, the prominence of the chin, and the naso-labial furrow. Between the skin and 
the mucous membrane, there is found, as in brutes, a glandular layer and muscles, 
chiefly the buccinator. An adipose ball is always found near the anterior border of the 
masseter. 

i 3. Palate.—It does not possess a vascular membrane, as in the Horse, and its mucous 
membrane shows a longitudinal and transverse furrows in its anterior two-thirds. It 
is pale and resisting. . i F : 

4. Tongue.—This is thick, short, and broad ; its base is almost vertical, and in the 
middle is a perpendicular, fibrous, and semilunar lamina, the lingual septum which gives 
insertion to muscular fibres. 

Anthropotomists distinguish intrinsic and extrinsic muscles. The first are: the 
lingualis superior and inferior, transversus, and longitudinalis. The second are, as in 
Solipeds, the stylo-glossus, genio-glossus, hyo-glossus, and pharyngo-glossus. There is 
also described a palato-glossus, which partly belongs to the soft palate. 

The mucous membrane shows the different characters recognised in that of animals, 
That of the dorsil face is divided into two portions by two A-shaped rows of papille, 
whose summit abuts on the deep mucous follicle named the foramen cecum. The 
posterior portion presents depressions which correspond to the closed follicles, and the 
fungiform and calyciform papille; the anterior portion Las a villous aspect, due to the 
great number of filiform papille covering it. 

5. Soft Palate—In Man, the soft palate is short and divided into two portions: an 
anterior, horizontal, attached to the base of the tongue by the anterior pillars of the 
curtain; a posterior, movable and oblique, having a free portion, the uvula, and fixed to 
the lateral walls of the pharynx by the posterior pillars. The amygdale, or mass of 
closed follicles, are lodged in the triangular space between the anterior and posterior 
pillars. The fibrous structure is not present, unless the small expansion of the 
external tensor of the palate represents it. The muscles are:the same as in animals, 
and, in addition, there are described two palato-glossal muscles, included between the 
mucous folds that form the anterior pillars. The palato-pharyngeus extends to the 
posterior nasal spine. The isthmus of the fauces is wider than in the Carnivora. 

6. Teeth—The teeth are thirty-two in number, sixteen in each jaw. They are 
distributed in the following manner: four incisors, two canines, two small molars 
(bicuspidati), and three large molars (muit?-cuspicat?). 

The incisors, when viewed in profile or longitudinal section, have a wedge-shape, and 
their free border is more or less sharp. The canines ‘are irregularly conical; the molars 
have a multiple fang, and the crown is studded with a variable number of tubercles: two 
on each small molar and four on the large. In youth, there are only twenty teeth, ten 
in each jaw. 


THE SALIVARY GLANDS. 


The salivary glands are secretory organs annexed to the buccal cavity, 
into which they pour saliva: a recrementitious fluid that softens the food, 
favours its mastication and deglutition, and has a chemical action upon it 
after its arrival in the abdominal portion of the digestive canal. 

Though very diversified in form, yet they present in their structure such 
common characters, that, to obviate a recurrence to their organisation when 
speaking of each gland, we will describe it here. 

The salivary glands are constituted by a red or yellow spongy tissue, 
which is divided into small, rounded, or polyhedral masses, called salivary 
lobules. These extend in a layer beneath the adherent faco of the mucous 
membrane, and remain isolated from each other, or are agglomerated in a 
body to form a single gland. In the latter case they are united by condensed 
connective tissue, which is disposed over the surface of the organ as a very 


thin enveloping membrane, and into the lobular interstices in lamellar 
prolongations. 


THE SALIVARY GLANDS. 365 


In studying the organisation of one of these lobules, it will 
that it is made up of many very small secondary lobules or Toit, eh cae 
themselves due to the agglomeration of minute elementary vesicles or 
follicles, whose average diameter is from 1-500th to 1-1200th of an inch; 
nate pe into the little canal belonging to each of the secondary lobules, 
ae Oa joins those of the other acini of the primary lobule, to form 

‘The minute elementary vesicles or follicles, the glandular culs-de-sac (or 
ultimate follicles) consist of a thin amorphous membrane (membrana propria) 
lined by a layer of polygonal epithelium cells. (They are closely sur- 
rounded by a plexus of capillary blood-vessels), 

When the salivary lobules remain isolated, this canal, which is designated 
as excretory, because it carries from the lobule the saliva secreted within the 
elementary follicles, opens directly into the mouth. But when, on the 
contrary, they all unite and form a single gland, their excretory canals 
finally converge into one or more principal ducts, whose termination in 
every case takes place in the same manner—by opening into the mouth 
from the summit of a more or less salient tubercle, an arrangement which 


Fig. 170. 


LOBULE OF PAROTID GLAND, INJECTED WITH CAPILLARY NETWORK AROUND THE FOLLI- 
MERCURY, AND MAGNIFIED 50 DIAMETERS. CLES OF THE PAROTID GLAND. 


renders the introduction of particles of food into these excretory orifices 
somewhat difficult. The fibrous and elastic walls of these ducts are lined 
internally by columnar epithelium. 

Tf to the fundamental tissue just described, be added arteries, veins, and 
lymphatics, which convey the materials of secretion and nutrition, as well as 
the nerves which regulate the secretory and nutritive acts, all the elements 
entering into the organisation of the salivary glands are made known. 

The most voluminous of these glands—or those which comprise a very 
great number of agglomerated lobules, will be first noticed. They are 
the parotid, maaillary, sublingual, and molar glands, which are all pairs, and 
are placed in proximity to the mouth when they do not lie immediately 
beneath the adherent face of its mucous membrane. Secondly, the less im- 
portant glands—those which are spread in layers under that membrane, and 
including the labial, lingual, and palatine glands, will be examined. 


1. Parotid Gland. (Figs. 110; 172, 8). 


Preparation—This gland, with its excretory canal, is seen after the removal of the 
cervico-facial subcutaneous and parotido-auricularis muscles. 


The parotid gland is situated in the space included between the posterior 


366 THE DIGESTIVE APPARATUS IN MAMMALIA, 


border of the inferior maxilla and the transverse process of the atlas. It is 
elongated from above to below, flattened on both sides, and divided into 
two faces, two borders, and two extremities. ba ic } 

The external face, nearly plane, is hollowed in its inferior part into a 
longitudinal channel, which is sometimes transformed into a complete canal, 
and lodges the jugular vein after it has traversed the gland from, below 
to its superficies. This external face responds to the parotido-auricularis 
muscle, the subcutaneous muscle, the atloidean loop, a cervical ramification 
of the facial nerve, and the posterior auricular vein. The internal face ig 
very uneven and moulded on the subjacent parts. It covers the guttural 
pouch, the ‘mastoid insertion of the small oblique muscle of the head, 
levator humeri, stylo-hyoideus, the tuberosity on the posterior border of 
the os hyoides, the digastricus, the tendon of the sterno-maxillaris, and 
the submaxillary gland, which is separated from it by the thin cellulo- 
aponeurotic layer uniting the latter muscle to the levator humeri; also to 


MODES OF TERMINATION OF THE NERVES IN THE SALIVARY GLANDS. 


1, 2, Branching of the nerves between the salivary cells; 3, Termination of the 
nerve in the nucleus; 4, Union of a ganglion cell with a salivary cell; 5, Varicose 
nerve-fibres entering the cylindrical cells of the excretory ducts. 


the external carotid artery and its two terminal branches, the posterior 
auricularis, the muscles of the jaw, and, lastly, the facial nerve, which often 
passes through the substance of the gland. 

The anterior border of the gland is intimately united to the posterior 
border of the maxilla; it is related to the tempero-maxillary articulation, 
the subzygomatie vessels and nerves, and the maxillo-muscular vessels. 
The posterior border is thicker than the preceding, and is separated from the 
transverse process of the atlas by the terminal aponeurosis of the levator 
humeri, to which it is only fecbly adherent: it can also be easily separated 
from it, in order to raise the parotid and pass through the stylo-hyoideus 
muscle, in the operation of hyo-vertebrotomy. 

The superior extremity is bifurcated, and embraces the base of the concha 
of the ear. The inferior extremity is comprised in the angle formed by the 
union of the jugular and glosso-facial veins. 


THE SALIVARY GLANDS. 367 


Vessels and nerves of the parotid gland.—This gland receives its blood 
by a multitude of arterial branches from the large vessels it covers. Its 
nerves are very numerous, and are derived from the facial and inferior 
maxillary nerves, and the carotid plexus, 

Excretory canal.—The parotid gland is provided with a single excretory 
canal, the duct of Stenon, so named from the anatomist who gave the first 
good description of it. It is 
detached from the anterior Fig. 172 
border of the gland, near its 
inferior extremity, where the 
eye may readily follow it be- 
tween the lobules to the three 
or four principal branches 
from which it originates (Fig. 
172). At first in contact 
with the terminal tendon of 
the sterno-maxillaris, it after- 
wards turns round the pos- 
terior border of the digastric 
muscle (stylo-maxillaris por- 
tion), advances into the sub- 
maxillary space, creeps over 
the internal masseter muscle 
(pterygoid), beneath the 
glosso-facial vein, and arrives 
at the maxillary fissure, into 
which it enters with the 
aforesaid vein and _ corre- 
sponding artery, but behind 
both. It then ascends ex- 
ternally along the anterior 
border of the masseter 
muscle to the level of the 
inferior molars, when it 
passes beneath its two satel- 
lite vessels, obliquely crosses 
their direction, and pierces 
the cheek towards the third 


upper molar tooth, opening ae 
into the mouth by a large INFERIOR ASPECT OF HEAD AND NECK. 
tubercle. 1, Inferior border of lower jaw; 2, Genio-hyoideus; 3, 


. . Mylo-hyoideus; 4, Submaxillary artery ; 5, Ditto 
The parotid duct is com- vein; 6, Parotid duct ; a Sterno-maxillaris tendon ; 
posed of two membranes: 8, Parotid gland; 9, Sterno-maxillaris muscle; 10, 
the internal, mucous, With 11, 12, Submaxillary glands; 13, Sterno-thyro- 
columnar epithelium ; and _ hyoideus and subscapulo-hyoideus muscles; 14, Thy- 
id gland; 15, Pterygoideus internus. 
the external, made up of con- "S883 °" 


nective tissue, and circular and longitudinal elastic fibres. 
2, Maxillary or Submazillary Gland. (Figs. 172, 173.) 


Preparation.—To expose this eland, as well as the sublingual, divide the maxilla, as 
in preparing the muscles of the tongue for dissection (see p. 334). 

This gland, smaller than the preceding, is situated in the intermaxillary 
space, on the lateral plane of the larynx, and within the parotid gland. 


368 THE DIGESTIVE APPARATUS IN MAMMALIA. 


It is long and narrow, flattened on both sides, and describes a slight 
curve with the concavity turned upwards: a form which allows it to be 
studied, with regard to relations, on two faces, two borders, and two 
extremities. : ; 

By its external face, it responds to the internal pterygoid muscle, the 
digastricus, the sterno-maxillaris tendon, and the cellulo-aponeurotic layer 
separating it from the parotid. Its internal face, applied to the side of the 
larynx, responds, superiorly, to the guttural pouch, to the carotid artery, 
and to the nerves which accompany that vessel in the upper part of the 
neck. 

The superior border, thin and concave, is margined by the middle part of 
the digastricus. The inferior, thick and concave, is in contact with the 
glosso-facial vein. ; 

The posterior extremity is maintained beneath the transverse process of 


Fig. 173. 


sie 


WA Why 
a IRD SOT 


i 


MAXILLARY AND SUBLINGUAL GLANDS. 
R, Maxillary gland; s, Wharton’s duct; T, Sublingual gland. 


the atlas, by an extremely loose and abundant cellular tissue; the anterior is 
insinuated between the internal pterygoid and the thyro-hyoideus muscle. 

Vessels and nerves.—The blood is distributed to the maxillary gland by 
various small innominate arteries, like those of the parotid gland, and which 
are most frequently derived from the external carotid and the glosso-facial. 
The nerves are principally furnished by the carotid plexus. 


THE SALIVARY GLANDS. 369 


Excretory Canal.—Wharton’s duct, as it is termed, is long and narrow: 
has very attenuated walls, and exists for nearly the whole length of the 
superior border of the gland : sometimes on its internal face, where it receives 
the ramifications from various lobules. At the anterior extremity of the 
organ it becomes free, and passes forward between the mylo-hyoideus and 
basio- (hyo-) glossus muscles. After crossing, outwardly, the glosso-facial 
artery and great hypoglossal nerve, and, inwardly, the tendon of the di gas- 
tricus and the lingual nerve, it passes between the hyo-glossus longus and 
the sublingual gland, lying closely to the inner side of the latter ; thus it 
extends parallel to the lateral groove (or channel) of the lingual canal (on 
the floor of the mouth). It finally arrives near the frenum of the tongue. 
but underneath the buccal membrane, and opens into the mouth by a small, 
but very salient, floating tubercle, situated a little in advance of the frenum, 
and vulgarly named the barb (barbillon). 

The structure of Wharton’s duct is identical with that of Stenon, but its 
external tunic is extremely thin, and has not any circular elastic fibres. 


3. Sublingual Gland. (Fig. 173.) 


This is less in volume than the preceding, and is situated under the 
tongue, in the intermaxillary space. 

Elongated from before to behind, and very flat laterally, it has, like 
the submaxillary gland, two faces, two borders, and two extremities, whose 
relations we will briefly indicate. 

The external face is covered by the mylo-hyoideus muscle; the internal 
responds to Wharton’s duct and the genio-glossus and hyo-glossus longus 
muscles. The upper border projects beneath the mucous membrane on the 
floor of the mouth, where it forms the sublingual ridge ; the inferior, thin 
and sharp, is comprised between the mylo-hyoideus and the genio-glossus 
muscles. The two extremities are thin and tapering; the posterior contains 
a branch of the lingual nerve; the anterior extends to the bottom of the 
angle formed by the union of the two branches of the inferior maxilla, 

Vessels and nerves.—This gland possesses a special, but small artery—the 
sublingual. Its nerves come from the lingual nerve, and even from the 
carotid plexus. 

Excretory canals.—These number fifteen or twenty, and are named the 
ductus Riviniani. Flexuous and very slender, they are detached from the 
superior border or internal face of the gland, ascend perpendicularly, and 
open into the mouth on the sublingual crest or ridge by a linear series 
of small orifices pierced, as usual, in the centre of a tubercle. 


4, Molar Glands. 


These are so named because they are disposed parallel to the molar arches. 
There are two on each side. 

The superior molar gland, the most considerable, represents a narrow 
line of salivary lobules placed outside, and along the upper border of, the 
alveolo-labialis muscle. In its posterior part, where it is concealed beneath 
the masseter muscle, this gland is thicker and more compact than in front, 
where the few lobules which compose it scarcely come in contact with each 
other. ‘ 

The inferior molar gland, less lobulated and voluminous, and not so 
wide as the preceding, is placed at the inferior border of the buccinator, 
immediately beneath the mucous membrane of the mouth, and near the 


370 THE DIGESTIVE APPARATUS IN MAMMALIA. 


point where it is reflected from the side of the cheek on to the inferior 
maxillary bone. It is bordered, for the whole of its extent, by the buccal 
nerve. 

Both glands pour their secretion into the mouth by numerous salient 
orifices, which can be seen arranged in line on the buccal membrane, parallel 
to each molar arcade. _ 

It may be remarked that these glands establish a transition between the 
preceding and those yet to be mentioned. Their lobules are far from 
representing so compact an agglomeration as that formed by the parotid or 
sublingual lobules; and they tend to separate from each other to become 
more independent. Therefore it is that many writers regard them as distinct, 
and describe them as superior and inferior molar glands. 


5. Labial, Lingual, and Palatine Glands. 


The lobules composing these glands are spread in layers more or less 
thick on the inner face of the mucous membrane, instead of being 
agglomerated in masses, as in the previous glands. Sometimes they are 
scattered, in consequence of their small number. In general, the excretory 
duct of each glandule opens independently into the mouth, without com- 
municating with those of the neighbouring lobules. 

Labial Glandule.—These are more abundant in the upper than in the 
lower lip, and pass beyond the commissures to be spread for a short distance 
over the inner aspect of the cheeks. It is easy, in the living Horse, after 
turning up the lip and carefully wiping it, to see the salivary fluid secreted 
by these small organs escape by their excretory ducts. 

Lingual Glandule.—They form a layer under the mucous membrane at 
the base of the tongue, and adhere very closely to the fibres of the small 
hyo-glossus muscle, and, laterally, are continuous with the layer which 
covers the external face of the amygdaloid mucous membrane. They are 
also found on the side of the tongue, above the superior border of the hyo- 
glossus longus muscle; though these are few and scattered, and look as if 
incrusted in the substance of the hyo-glossus muscle. 

Staphyline (or Palatine) glandule.—The thick layer these form under the 
anterior mucous covering of the soft palate has been described with that 
organ. We have only to observe here, that it is continuous, laterally, with 
the glands at the base of the tongue, through the medium of the glandule of 
the amygdaloid cavity; and in such a manner, that the part of the mouth 
immediately in front of.the isthmus of the fauces, and which might be 
justly considered as the isthmus itself, is enveloped in a complete glandular 
zone. In the dead body, we always find in this compartment a greater or 
less quantity of viscid fluid, which is certainly secreted by this zone. It is 
here, then, that the alimentary bolus is enveloped in the glutinous matters 
intended to favour its passage in the pharynx and cesophagus; and it is 
worthy of notice that the constricted passage where this secretion is poured 
out in the living animal, immediately precedes the canal traversed by the 
bolus of food in the act of deglutition. 


DIFFERENTIAL CHARACTERS IN THE SALIVARY GLANDS OF OTHER THAN SOLIPED 
ANIMALS, 


The salivary system of the Herbivora is more cxtensive than that of the Omnivora, 
and especially the Carnivora. 


Rominants.—l. Parotid gland.—The parotid glands of the Ox are distinguished by 


THE SALIVARY GLANDS. 371 


their meagre development and red colour, which contrasts markedly with the pale yellow 
hue of the maxillary glands. In the Sheep and Goat, Stenon’s duct 


3. Sublingual gland—In the Ox, Sheep, and Goat, this gland comprises two 
portions: a posterior, somewhat voluminous and lobulated, provided with a special 
excretory duct which follows and opens near Wharton's duct (by the ductus Bartho- 
Unianus) ; and an anterior, pouring out its secretion by many canals, and representing 
the gland proper. This arrangement allows the saliva to be collected separately from 
this gland. 

He Molar glands—These are more developed in Ruminants than in Solipeds. The 
upper one is enlarged at its posterior extremity. 

Pic.—The parotid gland of this animal is little developed, as in Ruminants, and 
Stenon’s duct follows the posterior border of the lower jaw. (Leyh says that it is, pro- 
portionately, largely developed ; that its upper end does not reach the conch of the ear, 
and that Stenon’s duct opens at the sixth molar.) ene 

The sublingual gland is analogous in its disposition to that of the Ox. Cuvier, in his 
‘Legons d’Anatomie Comparée,’ indicates this :— “The Pig has two sublingual glands. 
One, very long and narrow, accompanies, outwardly, the excretory canal of the sub- 
maxillary gland, from the angle of the jaw to the second sublingual. It is composed of 
small lobules of a pale red colour. Its excretory duct arises near the posterior third, and 
passes along with, but to the outside of, the submaxillary duct. It terminates near tlic 
orifice of the latter by a small opening; its diameter is equally small. The second sub- 
lingual gland is placed before the first; its form is square and flattened, and the lobes of 
which it is composed are larger and redder. It has from eight to ten excretory ducts.” (In 
this animal tle duct of Wharton does not open into the mouth by a papilla ; consequently 

here is no barb. 
, Preenban ike parotid of the Dog and Cat is emall, and Stenon’s duct always 
passes through the masseter. (It opens at the fourth molar in the Dog, and the third in 
he Cat. : 
i In tive Dog the submaxillary glands are larger than the parotids. “They even have 
in front, along Wharton’s duct, a small accessory gland, with a distinct excretory canal 
opening into the same papilla as Wharton’s.’ (Leyh states that the submaxillary duct 
does not project into the mouth). The supplementary gland is absent in the Cat. 

The sublingual gland is not present in the Dog: it is very small in the Cat, and 
earried further back than in the other animals. (Leyh describes a sublingual gland as 
present in the Carnivora, and which is divided into two portions, asin the Pig: the 
anterior being formed of detached lobules that open into the mouth by several ducts ; 
and the posterior, larger above rae pele aan ducts, the smaller pening into 

rton’ nd the larger a little in front of it. ' 
bila erie nee ce gs: the Dog, scarcely noticeable for the greater part e ey 
extent, forms posteriorly, under the zygomatic arch, near the eye, an eae z sc) 
remarkable for its large size and its single excretory duct. Duvernoy, igi a 
described it, proposed to name itthe subzygomatic gland. It is not aes 7 e Cat. 
(This is doubtless the organ described by Leyh as the orbital gland, whic h, he aad 7 
only found in the Dog; the superior molar gland, according to him, not existing su : at 
animal. This orbital gland is external to the ocular muscles, has three or four Cosi on 
canals (the ductus Nuckiant) which converge into one duct that opens into the mow 

T. . : 
ae oe a and palatine glandule are much less developed fet ees 
than the Herbivora. This predominance of the salivary system in the latter is suffi- 
ciently cavemen for, when we consider the hard, fibrous, and Reet ieee 
2 a ‘ 

i i d which must be ingested in large quantity, because of the sma 

aes oer os contains, For its mastication and cdeglutition w great amount of 


saliva is absolutely necessary, 


372 THE DIGESTIVE APPARATUS IN MAMMALIA. 


COMPARISON OF THE SALIVARY GLANDS OF MAN WITH THOSE OF ANIMALS. 


i imals, the parotid is the most voluminous of the salivary glands. Its tissue 
is eae and ioUulated, the lobules adhering closely to each other, Its shape is 
irregular, and it is moulded to the excavation behind the angle of the jaw. Stenon’s 
duct passes across the masseter, and shows on its course some salivary lobules, forming 
what is named the accessory parotid (or socia parotidis); it opens opposite the third 
upper molar. 4 ‘ : 

The submaxillary gland weighs about half-an-ounce. It is partly situated beneath 
the deep cervical fascia, and partly within the body of the lower jaw, between the mylo- 
hyoideus and hyo-glossus muscles. Its lobules are more loosely united than those of the 
parotid. Wharton’s duct opens on the sides of the frenum lingue by a small opening at 
the apex of a round papilla (caruncula sublingualis). ; : 

The sublingual gland is analogous to that of the Ox and Pig. There are, in fact, two 
sublinguals ; an anterior about the size of an almond, and furnished with a single 
excretory canal—the ductus Bartholini, that terminates near Wharton’s duct; the other, 
posterior, formed by several isolated lobules with multiple excretory ducts, the ductus 
iviniant, 

There are also labial, palatine, and lingual glands; with, besides, near the freenum, 
a small conglomerate gland, the gland of Nuhn, which has a special duct. 


Fig. 174, THE PHARyNX. (Figs. 174, 175.) 

Preparation.—1. Study the general disposition 
and situation of this vestibule in the antero- 
posterior vertical section of the head (fig. 175), 
2. In order to examine the interior conveniently, 
the head should be. separated from the neck, 
leaving attached to it a certain portion of the 
trachea and cesophagus; then by sawing across, 
either through or behind the temporo-maxillary 
articulations, all that portion of the cranium is re- 
moved, and the posterior parietes of the pharynx is 
exposed, and may be dissected to study the muscles 
(Fig. 178), or opened in the middle line to reach 
the interior of the cavity (Fig. 174). 3. The muscles 
should be dissected with those of the tongue, and 
in the same manner. 


The pharynx is a membranous vestibule 
common to the digestive and air passages, 
and situated behind the soft palate, which 
separates it from the mouth; above, it is at- 
tached to the base of the cranium, and, below, 
to the laryngeal apparatus. 

Form and internal disposition—In con- 
sequence of the conformation of the soft 
palate, which, in the domesticated animals, 
and particularly in Solipeds, is prolonged to 
PHARYNGEAL AND LaryNeraL Re- the base of the epiglottis, the pharynx forms 

GION; THE POSTERIOR part or acylindrical cavity elongated from before to 
THE HEAD INCISED AND THROWN behind, enclosed laterally and posteriorly 
FORWARDS by wide thin muscles, and with the soft 
1, Base of the cranium ; 2, Roof of palate for an anterior wall. At the two 
oe ae sp eon = extremities of this cavity are openings which 
6, Septum nasi; 7, een allow the pharynx to communicate with the 
openings of nostrils; 8, Entrance other passages or cavities, and whose dis- 
to the mouth; 9, Epiglottis; 10, position we will at once begin to study. 
Posterior pillars of soft palate; 11, At the upper extremity of the large 
Arytenoid cartilages ; 12, Opening is of theo r : Aa 
of the esophagus ; 13, Esophagus; 9X18 of the pharyngcal cavity is to be re 
14, Trachea. marked: 1, In front, the two posterior 


THE PHARYNX. _ 
oO 


openings of the nasal cavities; 2, Behind, and directly opposit 
A ’ ’ the — 
ceding, the two pharyngeal o enings of the Eustachi te whe 
closed by a cartilaginous kind Of alge ule: fan ig ee 
At the inferior extremity of this axis is found: 1, In the centre, a vast 
gaping orifice projecting into the anterior of the pharyngeal cavity, like a tap 
into a cask: this is the entrance to the larynx, the salient portions of which 
form, on the walls of the pharynx, two lateral gutters limited superiorly by 
the posterior pillars of the soft palate; 2, In front of, and beneath this, is 
ened of es eee Behind and above, the esophageal opening at the 
ae San undibulum, which may be considered as a special region of 
These seven openings of the pharyngeal cavity give it the 
. . : et 
a cross road, into which abut different cnet It is penn 
note that the air and digestive passages intersect each other here, and in 
ee es ee sgolisicd camer the bolus of food passes over the entrance 
of the larynx to reach the cesophageal opening. This peculiarity i i 
seen by referring to figure 175. i one ce ae 
Fig. 175. 


MEDIAN LONGITUDINAL SECTION OF HEAD AND UPPER PART OF NECK. 

1, Upper lip; 2, Premaxilla; 3, Hard palate; 4, Tongue; 5, Septum nasi; 6, Nasal 
bone; 7, Palate bone; 8, Soft palate; 9, Pterygoid bone; 10, Epiglottis; 11, 
Entrance to Eustachian tube; 12, Arytenoid cartilage; 13, Cricoid cartilage ; 
14, Esophagus; 15, Frontal bone and sinus; 16, Cerebrum; 17, Corpus cal- 
losum ; 18, Cerebellum; 19, Sphenoid bone; 20, Medulla oblongata ; 21, Cervical 
ligament ; 22, Spinal cord ; 23, Occipital bone; 24, 24, Atlas ; 25, 25, Dentata ; 
26, Trachea. 


Relations. Viewed externally, for the study of its connections, it will be 
found that the pharynx responds, posteriorly, to the guttural pouches and 
guttural lymphatics ; laterally, to the large branch of the os hyoides, the 

1 This region corresponds to the posterior nares (arriére fond) of Man, a diverticulum 
which cannot be distinguished from the pharynx in the domesticated animals. Under 
the designation of the posterior nares of the nasal fosse, it will be understood that we 


mean the posterior extremities of these cavities. 
(In the ‘ Annales de Medecine Vétérinaire? of Brussels, for 1871 (p. 244), M. Lorge 
describes a pharyngeal cecum as existing in Solipeds, which he states corresponds to the 


naso-pharyngeal region, or posterior nares, of Man.) 
2 


374 THE DIGESTIVE APPARATUS IN MAMMALIA. 


internal pterygoid and stylo-hyoid muscles, the glosso-pharyngeal, great 
hypoglossal, and superior laryngeal nerves, and the glosso-facial artery. 

Srructurs.—The walls of the pharynx are composed of a mucous mem- 
brane, external to which is a muscular layer. 

1. Mucous membrane.-—This membrane is covered, externally, by a thin 
layer of yellow elastic fibres, and is much more delicate and less protected 
by its epidermis than the buccal mucous membrane, of which it is a con- 
tinuation; it also communicates with that of the cesophagus, the larynx, the 
nasal fosse, and the Eustachian tubes. 

Its epithelium is stratified throughout; but it is thin and ciliated in the 
upper part, thicker and tesselated on the inferior moiety, which more 
particularly belongs to the digestive apparatus. 

Everywhere there are racemose glands, though they are most numerous 
towards the roof of the pharynx. There are also some follicular glands 
beneath the mucous membrane, in the neighbourhood of the guttural opening, 
the nasal cavities, and the Eustachian tubes. 

2. Muscular layer—This is composed of seven pairs of muscles, indicated 
in the following enumeration: the palato-pharyngeus, pterygo-pharyngeus, 
hyo-pharyngeus, thyro-pharyngeus, crico-pharyngeus, aryteno-pharyngeus, stylo- 
pharyngeus. 

Patato-PHARYNGEUSs (Pharyngo-staphylinus)—This muscle, which has 
already been described as belonging to the soft palate, is prolonged back- 
wards on the lateral wall of the pharynx, where its fibres are mixed with 
those of the pterygo-pharyngeus, and go to be attached to the superior 
border of the thyroid cartilage by passing beneath the hyo-pharyngeal 
and thyro-pharyngeal muscles. It therefore also belongs to the pharynx. 

PTrERYGO-PHARYNGEUS, OR SuPERIOR ConstRictor (the palato-pharyngeus of 
Percivall).—This muscle is thin, wide, flat, and triangular. It originates 
from the pterygoid process, whence its fibres diverge, some posteriorly, 
others inwardly. The former mix with those of the palato-pharyngeus, 
and comport themselves like that muscle; and the latter are united, on 
the median line, with the analogous fibres of the opposite muscle, form- 
ing a kind of zone around the origin of the Eustachian tube. This 
muscle is covered, externally, by a layer of yellow elastic tissue, which is 
attached with it to the pterygoid bone; afterwards it is fixed to the superior 
border of the great branch of the os hyoides, and is even prolonged on the 
external surface of the muscle it covers to the thyroid cartilage. 

The elasticity of this fibrous covering plays a certain part in the move- 
ments of the hyo-laryngeal apparatus, in acting as a passive antagonist of its 
depressors. , 

This muscle is, and can only be, a perfect constrictor of the pharynx, 
as it diminishes the diameter of that cavity in every direction: the longi- 
tudinal diameter, by means of its posterior fibres, which draw the thyroid 
cartilage forward; and its transverse diameter, by the circle thrown around 
the orifice of the Eustachian tubes (Figs. 149 ; 176, 8). 

Hyo-pHaryrneeus, on First Mipp.e Consrrictor ; THyRO-PHARYNGEUS, 
or SeconD Mippiz Consrricrorn; anp (‘r1co-PHARYNGEUS, oR INFERIOR 
Constricror.—The two first of these muscles only form one in Man, the 
middle constrictor of the pharynx. They are three muscular bands which 
terminate above the pharynx, on a median fibrous fold sometimes wide 
enough to look like an aponeurosis. The first band arises from the cornu of 
the os hyoides; the second, from the external surface of the thyroid carti- 
lage; the third, from the superficial face of the er‘coid cartilage, 


THE PHARYNX. 375 


These are universally regarded as constrictors. 

Sometimes two fasciculi are observed in the crico-pharyngeus. The 
supplementary fasciculus is somewhat thin, and arises from the posterior 
border of the bezil of the cricoid cartilage, ascending parallel to the ceso- 
phagus to terminate with the principal fasciculus. 

ARYTENO-PHARYNGEUS.—By this name has been described a small fasci- 
culus, extremely thin in Solipeds, which extends from the posterior border 
of the arytenoid cartilage to the origin of the esophagus. To expose this 
muscle, which we do not look upon as constant, it is necessary to turn the 
cesophagus forward on the superior surface of the pharynx. 

SryLo-pHaRYNGEUs.— A narrow band which descends from the great 
hyoideal branch to the side of the pharynx, where it is confounded with 
the pterygo-pharyngeus. It elevates the pharynx in contracting, and it is 
also regarded as a dilator; though the disposition of the parietes of the 
pharynx, and the feeble volume of this muscle, scarcely allows it to play 
any efficacious part in the dilatation of that cavity. It may only produce 
a very slight infundibulum where it is inserted. The real dilating agent 
of the pharyngeal cavity is the alimentary bolus, which is pushed into it by 
the action of the tongue (Fig. 149, 5). 


Fig. 176. 


MUSCLES OF THE PHARYNGEAL AND HYOIDEAL REGIONS. 


lenoid cavity of temporal bone; 2, Superior extremity of styloid bone; 3, 

: Tenwor palati with its pelle 53 4, Stylo-pharyngeus; 6, Palato-pharyngeus 5. 7, 

Circumflexus palati; 8, Pterygo-pharyngeus ; 9, Sublingual gland ; ae ieee 

of hyoid bone; 11, Hyo-pharyngeus ; 12, Thyro-pharyngeus ; 13, oy See 

geus; 14, Portion of stylo-pharyngeus ; 15, Hyo-thyroideus ; 16, Sty] Hone ; 
17, Crico-arytenoideus lateralis; 18, Esophagus; 19, Sterno-maxi ae an 
hyoideus, and subscapulo hyoideus; 20, Trachea; 21, Hard palate; 22, Tongue. 


i : le terminating on 
It is not rare to meet a second stylo pharyngeus muse 
the aac point as the first, but proceeding from the inferior extremity of the 


7 : ‘ 
‘ve branch of the os hyoides, instead of its upper part. 

re anatomists dpeienats it the inferior kerato-pharyngeus, and con- 

sider it as a constrictor of the pharynx. Tt sometimes exists only on one side. 


3. Vessels and nerves.—The blood sent to the pharynx comes from the 


376 THE DIGESTIVE APPARATUS IN MAMMALIA. 


pharyngeal and thyroideal arteries. The nerves are supplied by the glosso- 
pharyngeus, pneumogastric, and great sympathetic. al 

Funcrions.—The pharynx plays a passive part in respiration, by serving 
ag an intermediate canal between the nasal passages and the larynx. 

Its principal function, however, is connected with the digestive pheno- 
mena, by its being an active agent in the first stage of deglutition—a complex 
and rapid movement, which is executed in the following manner: The bolus of 
food, propelled by the tongue into the pharynx, is seized by the constrictor 
muscles, which come into action successively from before to behind, in a 
peristaltic and involuntary manner, to carry the mass to the entrance of 
the esophagus. The food thus passes over the opening of the larynx during 
pharyngeal deglutition, but it cannot enter it, because the bolus forces back 
the opiglottis on this aperture, which it almost exactly closes “ because, also, 
the passage of the food prevents pulmonary inspiration, which might, if 
allowed to take place, divert it from its natural course, and throw it into 
the nasal air-passages; the application of the walls of the pharynx to the 
pellet of food during its momentary passage over the larynx, intercepts all 
communication between the external air and the lungs, and only permits 
the elevation of the ribs with the utmost difficulty. The extreme rapidity 
of the act of deglutition is another reason for the food escaping the larynx. 

(Gray concisely remarks: When deglutition is about to be performed, 
the pharynx is drawn upwards and dilated in different directions to receive 
the morsel propelled into it from the mouth. The stylo-pharyngei, which 
are much further removed from one another at their origin than at their 
insertion, draw upwards and outwards the sides of this cavity, the breadth 
of the pharynx, in the antero-posterior direction, being increased by the 
larynx and tongue being carried forwards in their ascent.. As soon as the 
morsel is received in the pharynx, the elevator muscles relax, the bag 
descends, and the constrictors contract upon the morsel and convey it 
gradually downwards into the cesophagus. ) 

The deglutition of liquids is carried on in a similar manner. 

It is curious to remark that, in Solipeds, the food does not come into 
direct contact with the greater portion of the superior wall of the pharynx 
during its passage through that cavity. When the alimentary mass is 
carried back by the tongue, it raises the soft palate and bears its posterior 
border backwards to the entrance of the cesophagus. The extreme develop- 
ment of this palatine curtain, therefore, quite prevents this surface of the 
pharynx from being directly applied to the food, and it is through the medium 
of this partition that the constrictors exercise their peristaltic action on the 
morsel of aliment until it reaches the cesophageal infundibulum. 


DIFFERENTIAL CHARACTERS OF THE PHARYNX IN OTHER THAN SOLIPED ANIMALS. 


The pharynx of Ruminants is long and very spacious. The hyo-, thyro-, and crico- 
pharyngeal muscles—the first and second of the two middle constrictors, and the inferior 
constrictor—are less distinct from each other than in the Horse; the last-named muscle 
is very small, and the fibrous raphé on which the constrictors unite is little developed. 
In the pharynx of the Sheep is noticed a mucous duplicature that descends to the middle 
of the posterior wall, and appears to be a continuation, posteriorly and inferiorly, of the 
nasal septum. j 

In the Pig, the posterior part of the pharynx is narrow, and hasa pouch immediately 
above the glottis, between the thyro- and crico-pharyngeal muscles. 

In the Dog, the infundibulum is very spacious, and the pharyngeal mucous membrane, 
much finer than that of the cesophagus, is distinguished from it by a well-marked line 
of demarcation. The crico-pharyngeal is not very distinct from the thyro-pharyngeal 
muscle ; so that, in reality, only three constrictors can be distinguished. 


THE GSOPHAGUS. 


377 


COMPARI3ON OF THE PHARYNX OF MAN WITH THAT OF ANIMALS. 
In consequence of the smallness of the soft palate, the pharynx of Man is only a 


kind of channel between the mouth and the larynx and cesuphagus. 


It is usually 


divided into three portions: a superior, the posterior nares, covered by ciliated epithelium ; 
a middle, or guttural, and an inferior, or esophageal; the two latter are covered with 


tesselated epithelium. 


The muscles are almost the same as in the Dog, being a portion of the palato-pharyn- 
geus, the superior, middle, and inferior constrictors, and a stylo-pharyngeal muscle. 

Below the sides of the pharynx, and between the pillars of the sott palate, are the 
amygdale : almond-shaped organs, whose surface slows the openings of the follicles that 
with the vessels and a little connective tissue, compose their substance. , 


THE CGSOPHAGUS, 


(Figs. 178, 179.) 


Preparation.—Place the subject in the first or second position ; remove the subcu- 


taneous cervical muscle from the left side; take away 
the corresponding anterior limb, and proceed to the 
excision of the ribs of this side, with the exception of the 
first. Afterwards dissect the vessels and nerves in the 
neighbourhood of the cesophageal canal, taking care to 
preserve their relations to each other. 


Form.—The cesophagus is a long, cylindrical, 
narrow, membranous canal, easily dilated for the 
greater part of its extent, and destined to convey 
the food from the pharynx to the stomach, and to 
complete the act of deglutition. 

Course-—This canal begins at the pharynx, 
and communicates with it by means of the pos- 
terior opening situated above the glottis. It 
afterwards descends behind the trachea to the 
middle of the neck, where it commences to 
deviate towards the left side of that tube, and 
enters the thoracic cavity by inclining towards 
the inner aspect of the first left rib. It soon 
after regains its situation above the trachea, passes 
over the base of the heart, and reaches the open- 
ing of the right pillar of the diaphragm, in 
passing between the two layers of the posterior 

mediastinum. Traversing this opening, it pene- 
trates the abdominal cavity, and immediately 
afterwards is inserted into the smaller curvature 
of the stomach by an orifice designated the cardiac, 
which will be studied at the same time as that 
viscus. 

Relations. —The cesophagus in its course has 
the following numerous relations : 

At its origin, it is comprised between the 
guttural pouch and the posterior crico-arytenoid 
muscles. 

In the cervical region, 
thick layer of cellular tissue, 


it is enveloped in a 


Fig. 177. 


HUMAN PHARYNX LAID OPEN 
FROM BEHIND. 


1, Section through base of 
skull; 2, 2, Walls of pha- 
rynx drawn aside; 3, 3, 
Posterior nares, separated 
by the vomer ; 4, Extremity 
of one Eustachian tube; 5, 
Soft palate; 6, Posterior 
pillar of soft palate; 7, An- 
terior pillar; 8, Root of the 
tongue, partly concealed by 
the uvula; 9, Epiglottis 
overhanging (10) the cordi- 
form opening of the larynx; 
11, Posterior part of larynx ; 
12, Opening of esophagus, 
13; 14, Trachea. 


which unites it in a loose manner to the 


surrounding organs, its relations with these varying as we consider them 
superiorly or inferiorly. Superiorly, and in the median plane, 1t occupies 
the space included between the trachea and the longus-colli, being bordered 
on each side by the common carotid artery, with its satellite nerves—the 


378 THE DIGESTIVE APPARATUS IN MAMMALIA. 


trunk common to the great sympathetic and pneumogastric, and the inferior 
laryngeal. : 

Inferiorly, it is related to the trachea internally ; and, externally, to 
the inferior scalenus muscle, and the vessels and nerves of the left cervical 
channel, which also includes the jugular vein.* ; - 

At its entrance into the thoracic cavity, the cesophagus, still deviating to 
the left, and lying on the side of the trachea, responds, externally, to the 
inferior cervical ganglion, the afferent and emergent nervous branches of 
that ganglion, the vertebral arteries and veins, and the superior cervical and 
dorso-muscular vessels, which obliquely cross its direction. Beyond this 


Fig. 178. 


TRANSVERSE VERTICAL SECTION OF HEAD AND NECK IMMEDIATELY IN FRONT OF THE 
STYLOID PROCESSES, AND BEHIND THE CSOPHAGUS. 

1, Esophagus; 2, Inner surface of trachea; 3, Common carotid artery; 4, Recur- 
rent nerve; 5, Thyroid gland; 6, Exterior of pharynx; 7, Crico-pharyngeal - 
muscle; 8,9, 10, 11, Guttural pouch and objects in its interior; 12, Stylo- 
pharyngeus muscle; 13, Sphenoid bone; 14, Jugnlar ganglia; 15, Internal 
carotid; 16, 17, Pneumogastric nerve; 18, Parotid gland; 19, Great hypoglossal 
nerve; 20, Jugular vein, 21, Subscapulo-hyoideus; 22, Stylo-maxillaris. 


it regains its position between the trachea and the longus colli, passes 
above the left bronchus, to the right of the thoracic aorta, until it reaches 
between the layers of the posterior mediastinum, which bring it into relation 
with the internal face of the lungs; these are channeled for its reception, 
and here it is accompanied by the cesophageal artery, and the cesophageal 
branches of the pneumogastric nerve. 

The very short portion lodged in the abdominal cavity responds, on the 


' It is not rare to find the @sophagus deviate to the right below the neck; in this 
case its relations will be inverted. We have never scen this canal enter the thorax in the 
median plane of the body. 


THE ESOPHAGUS. 379 


right, to a fissure in the superior border of the liver, and is enveloped by the 
peritoneum. 

Interior.—Internally, the canal whose course and relations we have just 
studied presents nothing of interest; and it only requires to be remarked, 
that its walls are always shrunken and in contact when food is not passing 
between them. 

Strucrurs.—The cesophagus has two tunics: a mucous and a muscular. 

The mucous membrane is continuous with that of the pharynx and the 
stomach ; it is white, and shows numerous longitudinal folds which allow 
the canal to dilate. It adheres but loosely to the muscular coat, on which 
it can glide with the greatest facility. It has a thick, resisting, stratified, 


tesselated epithelium, an unstriped muscular layer, and some racemose 
glands. 


Fig. 179. 


SS) 
SC. 


i 


PECTORAL CAVITY AND MEDIASTINUM, SHOWING THE COURSE OF THE TRACHEZ 
AND GSOPHAGUS. 


(A third or middle coat is sometimes mentioned by anatomists; it is 
composed of the tissue connecting the latter tunic with the one to be next 
ve The Siete coat commences at the posterior part of the pharynx by 
the aryteno-pharyngei muscles, and by two small superficial bands which 
are detached from the posterior portion of the crico-pharyngei muscles. 
This tunic is formed of superficial longitudinal fibres, often assembled in 
fasciculi; and of a deeper series of spiral or circular fibres, which, towards 
the inferior extremity of the canal, intercross in an almost inextricable 
manner. This muscular layer in the cervical, and for a great part of the 
thoracic portion of the esophagus, has the red colour of voluntary muscles ; 
but it becomes white, like the involuntary fibres, after the conduit enters 
the mediastinum, and acquires considerable thickness and marked Sas 
It is to be noted that this arrangement of the muscular tunic is especially 


380 THE DIGESTIVE APPARATUS IN MAMMALIA. 


evident towards the insertion of the cesophagus into the stomach, and that 
the muscular tube is at this point so narrow, that it is almost exactly filled 
by the folds of mucous membrane it contains. For this reason it is that 
we may inflate a stomach by the pylorus, without applying a ligature to 
the esophagus; the aperture of the canal being so perfectly closed that it 
does not allow a bubble of air to escape. In describing the interior of the 
stomach, we will refer to the consequences resulting from this interesting 
anatomical fact. 

Vessels and nerves.—The cesophagus is supplied with blood by the 
divisions given off by the common carotid artery, as well as the bronchial 
and cesophagedl arteries. The nerves are almost exclusively derived 
from the pneumogastric; the motor nerves are the superior cesophageal 
filaments, branches of the external pharyngeal and laryngeal; the sensitive 
filaments are derived from the recurrent. 

Functions.—This canal conveys nutriment from the pharynx to the 
stomach ; it has no other uses.. 


DIFFERENTIAL CHARACTERS OF THE CGSOPHAGUS IN OTHER THAN SOLIPED ANIMALS, 


In all the other domesticated animals, the muscular coat is red-coloured throughout 
its whole extent, and everywhere offers the same degree of thickness and the same 
fluecidity, The canal is also as wide towards the stomach as at the pharynx. In 
Ruminants and the Carnivora, it enters the stomach as a funnel-shaped (infundi- 
buliform) tube. « 

The dilatability of the cesophagus is very remarkable in these animals: Dogs swallow 
large pieces of flesh; and Cows and Oxen are-able to injest large turnips, or such 
voluminous foreign bodies as shves. 

(In Ruminanis and the Carnivora the cesophagus is, proportionally, wider than in the 
Horse and Pig.) 


COMPARISON OF THE G&SOPHAGUS OF MAN WITH THAT OF ANIMALS. 


The cesophagus of Man resembles that of Carnivora; its diameter is almost uniform. 
I¢ also inclines to the left below the neck, but in the thorax is in the median line, though 
it again deviates to the left as it joins the stomach. As the thyroid in Man is very 
voluminous, it is related to the cesophagus in the upper part of the neck. Two small 
accessory fasciculi, belonging to the muscular tunic of the cesophagus, have been 
described : one is the broncho-esophageal muscle, which is detached from the left bronchus; 
and the other the pleuro-csophageal muscle, detached from the left layer of the posterior 
mediastinum. 


Articte II.—Tue Essentian Oreans or Digestion. : 


These organs being all contained in the abdominal cavity, this common 
receptacle will first be studied; afterwards the stomach, intestines, and their 
annexed organs—the liver, pancreas, and spleen—will be described. 


THE ABDOMINAL CAVITY, 


In mammalia, the interior of the trunk is partitioned by the diaphragm 
into two great cavities, that lodge the majority of the organs so vaguely 
termed the viscera. The anterior, the smallest, is the pectoral or thoracic . 
cavity ; the posterior is named the abdomen, or abdominal cavity. The latter, 
the only one we have now to study, is a vast oval-shaped reservoir, elongated 
from before to behind, having for its upper wall the muscles of the sub- 
lumbar region, inclosed_ below and laterally by the muscles of the inferior 
abdominal region, bounded in front by the diaphragm, and prolonged behind 
between the bones and membranous ligaments of the pelvis. 

The elements composing the parietes of this cavity having been already 
described, we will confine ourselves to an examination of its interior, in 


THE ABDOMINAL CAVITY. 381 


order to determine the various regions into which it is possible to divide it: 
a matter of some importance, as it singularly facilitates the topographical 
study of the contained viscera; for to say that an organ is situated in 
the abdomen, is a very vague reference to its precise situation, in conse- 
quence of the great extent of this cavity. It is necessary, therefore, to 
divide the abdomen into a certain number of peripheral regions which corre- 
spond to the different parts of its wall, with a view to define the situation 
of the organs lodged therein, yet without complicating anatomical de- 
scription. Six principal regions are recognised in the abdominal cavity. 

A. The superior, or sublumbar region, corresponds to the superior wall of 
the abdomen: that is, to the psoas muscles and the bodies of the lumbar 
vertebrae. It extends from the opening between the two pillars of the 
diaphragm to the entrance to the pelvis. 

B. The inferior region, limited, laterally, by the hypochondriacs and 
the flanks, commences, in front, at the xiphoid cartilage, and is prolonged 
to the pubis; it comprises all that portion of the abdomen which corre- 
sponds to the linea alba and the two recti muscles. Its great extent 
necessitates its subdivision into five secondary regions: The suprasternal 
region, named the epigastric in Man, placed above the xiphoid cartilage of the 
sternum; the wmbilical region, situated behind the preceding, and so named 
in consequence of its including that part of the wall which is pierced by the 
umbilicus; the prepubic region—the hypogastric or pubic of Man—occupies 
the space in front of the anterior border of the pubis; the two inguinal 
regions, diverticuli of the abdominal cavity, located in the inguinal tracts, 
where they form the special reservoirs to be hereafter described as the 
vaginal sheaths (or canals). 

CO. The lateral regions (right and left lumbar of Man) are limited : in front, 
by the costal attachments of the diaphragm ; behind, by the entrance to the 
pelvic cavity ; above, by the superior border of the small oblique muscle ; 
below, by the interval comprised between the inferior border of that muscle 
and the external border of the great rectus muscle. The designation of 
hypochondriac is given to the subregion which corresponds to the cartila- 
ginous circle of the false ribs. The flank is that section covered by the 
muscular portion of the small oblique muscle. 

D. The anterior, or diaphragmatic region, comprises the cavity formed by 
the posterior face of the diaphragm. Like that muscle, it is divided into 
two regions, a central and peripheral. 

E. The posterior, or pelvic region, is a special diverticulum of the abdomen 
described as the pelvic cavity. It is bounded, above, by the sacrum ; below, 
ly the superior face of the pubes, the ischia, and the internal obturator 
muscle; on the sides, by the constricted portions of the ossa innominata 
and the sacro-ischiatic ligaments. The entrance to this diverticulum is 
situated above the pubes, and is of an oval form. Posteriorly, it is narrower, 
and is traversed by the rectum and the genito-urinary organs, which open 
extérnally. 

THE Penrronzum.—The abdominal cavity is covered, internally, by a 
serous membrane, the peritoneum, which will now be briefly described. 

Like all the splanchnic serous membranes, the peritoneum is composed ot 
a parietal and a visceral layer, which together form a closed sac, so arranged 
that the organs contained in the abdomen are situated external to this sac. 
The adjoining theoretical figure (180), representing a transverse section of the 

abdominal cavity, will show at a glance this arrangement. Let A represent 
the section of the small intestines floating at liberty in the interior of the 


382 THE DIGESTIVE APPARATUS IN MAMMALIA. 


cavity, B that of the aorta, at the level of the great mesenteric artery: the 
peritoneal membrane, oc, covers the walls of the abdomen, and at the points 
pp (not inserted, but intended to be placed within the cavity below, and on 
each side of B, the aorta) is folded around the great mesenteric artery in such 
a manner as to form two layers, FF, which 
Fig. 180. come in contact by their adherent face, 
reach the intestine, and then separate to 
envelop it. We then see in this figure the 
parietal layer of the peritoneum, co, the 
visceral layer, Gc, and the two layers, rr, 
which establish the continuity of the parie- 
tal and visceral portions; the complete 
sac formed by these is apparent, and it 
could be rendered more so by the further 
separation and development of the layers 
FF; so that there is no difficulty in under- 
standing how the small intestine may be 
at the same time in the interior of the 
abdominal cavity, and outside the sac 
formed by the serous membrane which 
lines that cavity. 


THEORETICAL TRANSVERSE SECTION 


OF THE ABDOMINAL CAVITY, TO This arrangement is common to all the 
SHOW THE DISPOSITION OF THE Organs freely suspended in the abdomen. 
PERITONEUM, The serous folds which suspend them, in 


joining their peritoneal layer to that which 
covers the parietes of the cavity, will be studied under the names of 
ligaments, mesenteries, and omenta, Some organs—the kidneys, for example 
—have no proper visceral layer, being comprised between the abdominal 
wall and the external face of the parietal peritoneum, and are invested 
with none of the duplicatures just mentioned. 

We will briefly stndy the duplicatures, ligaments, mesenteries, and 
omenta that the peritoneum forms, starting from the umbilicus and passing 
forwards and backwards (Fig. 181). 

On reaching the suprasternal region, the peritoneum forms a faleiform 
duplicature, extending from the umbilicus to the middle lobe of the liver, 
and which is even prolonged between that lobe and the posterior face of the 
diaphragm ; at the free border of this fold is a thickening which is regarded 
as the remains of the obliterated umbilical vein. In becoming doubled over 
the neighbouring organs, the diaphragmatic portion constitutes: 1, The 
ligaments of the right and left lobes of the liver ; 2, The common ligament 
of that gland, which surrounds the posterior vena cava: 3, The cardiac 
ligament that envelops the termination of the cesophagus. Behind the 
liver is found the hepato gastric ligament, which fixes the stomach in the 
posterior fissure of the liver and is, to the right and backwards, attached to 
the duodenum at the lower face of the right kidney ; it is then directed from 
right to left, and becomes continuous with the parietal peritoneum of the 
sublumbar region and the mesentery proper. 

The two lamine of the hepato-gastric ligament separate at the lesser 
curvature of the stomach to cover that viscus; then join at its greater cur- 
vature, and pass to the interior of the abdominal cavity. This fold receives 
the name of the great or gastro-colic omentum ; it leaves the left tuberosity 
of the ventriculus, which it suspends to the sublumbar region from the 
whole extent of the great curvature ; to the right it goes beyond the pylorus, 


THE ABDOMINAL CAVITY. 383 


to be continued on the concave curvature of the duodenum as far as the 
cecum. By its posterior border, the great omentum is spread around the 
termination of the large colon and the origin of the floating colon, where it is 
confounded with the visceral peritoneum of these organs, as well as with tho 
parietal peritoneum. It results from this arrangement that the great omentum 
forms behind the stomach, and in front of the adherent portion of the large 
colon, a space that communicates with the great peritoneal cavity by a very 
narrow opening, the foramen of Winslow. This aperture is included between 
the vena porte, posterior vena cava, anterior extremity of the pancreas, and 
the lesser curvature of the stomach. To the left of the latter viscus, on the 
external face of the great omentum, the spleen is suspended ; consequently, 
that portion extending from the spleen to the ventriculus is named the 
gastro-splenic omentum. 

The two layers composing the great omentum are very thin for the 
greater part of their extent, and include the blood-vessels between them. 
In emaciated animals these vessels are distinctly seen, owing to the trans- 
parency of the membranes, and they give the omentum a lace-work appear- 
ance; but in fat subjects they are concealed by the adipose tissue deposited 
along their course, and which may accumulate in considerable quantity. 

In the sublumbar region, the parietal peritoneum forms several folds ; 
these are: the hepatico-renal ligament, extending from the right lobe of the 
liver to the anterior border of the right kidney; the ligament of the lobus 
Spigelii, the mesentery proper, the colic mesentery; lastly, the greatly de- 
veloped laminz surrounding the czecum and the second flexure of the colon, 
which constitute the meso-ceecum and meso-colon. 


Fig. 181. 
Pp Pp 
Titer, 


PP 


THEORETICAL LONGITUDINAL AND MEDIAN SECTION OF THE ABDOMINAL CAVITY, 
TO SHOW THE REFLEXIONS OF THE PERITONEUM. 

1, Liver: 2, Stomach; 3, Small intestine; 4, Origin of the floating colon; 5, 
: Rectum; 6, Vagina and uterus; 7, Bladder; 9, Posterior aorta; 10, Diaphragm ; 
11 Posterior vena cava; 12, Inferior abdominal wall.—Pp, Pp, Parietal perito- 
neum ; Pv, Pv, Visceral peritoneum.—L, Hepato-gastric ligament ; m, Mesentery. 

? 

—Ge, Great omentum. 


# mesentery is detached from the border of the large mesenteric 
Pee eel reject ite the abdominal cavity to reach the small intestine 
u . 
at its lesser curvature, and envelop that viscus. 


384 THE DIGESTIVE APPARATUS IN MAMMALIA. 


Its shape is that of an irregular triangle, whose summit corresponds to the 
mesenteric artery, the very short anterior border being continuous with the 
ducdenal frenum, and the posterior border, tke longest, with the meso-colon, 
its convex festooned base being as long as the intestine itself. Between the 
two lamine that compose it are the blood-vessels and lymphatics, as well as 
the nerves, of the small intestine. 

The colic mesentery is constituted like the great mesentery. Its inferior 
border, plane or plicated, is fixed to the small curvature of the floating colon 
and the commencement of the rectum; its upper border extends from the 
great mesenteric artery as far as the entrance to the pelvic cavity. 

Around the cross of the cecum, from the origin and the termina- 
tion of the great colon, the peritoneum is reflected to cover these viscera; 
a layer passes from the anterior border of the ca#cum on to the ileum 
and the second flexure of the colon: this is the meso-ccecum ; another layer, 
comprised between the second and third portion of the colon, and whose 
shape is that of a battledore, is named the meso-colon. 

If, again, the peritoneum is taken at the umbilical region and followed 
backwards, it will be found to insinuate itself into the inguinal canals, cover 
the organs contained in the pelvis, and become reflected at the bottom of 
that cavity, to be continued either with the peritoneum of the sublumbar 
region, or with that on the abdominal walls. 

This serous membrane covers the anterior cul-de-sac of the bladder, and 
at this point has three ligaments. The middle ligament, faleiform in shape, 
leaves the large extremity of the bladder, is attached to the anterior border 
of the pubis, and insensibly disappears on the inferior abdominal wall; on 
its free border is a small fibrous cord, which is supposed to be the remains 
of the urachus. The two lateral ligaments are more developed, and extend 
from the entrance to the pelvic cavity to the vesical cul-de-sac; they have on 
their free border the obliterated umbilical arteries. In the male, the peri- 
toneum is prolonged from the upper face of the bladder to the enlargement of 
the deferent ducts, between which it sends a transverse fold to the anterior 
extremity of the vesicule seminales, and is then reflected around the 
rectum. 

In the female, it is carried from the bladder to the terminal portion 
of the vagina, to the uterus, and to the cornua of that organ, where it 
forms three folds named the broad ligaments, ligaments of the ovary, and the 
round ligament ; then it re-descends on the upper face of the vagina, and 
thence envelops the rectum, around which it is reflected from behind forwards. 

According to this arrangement, we see that the termination of the 
digestive canal, and the parts of the genito-urinary organs situated altogether 
at the posterior portion of the pelvic cavity, are placed outside the peri- 
toneal serous membrane. 

Srrvorvre.—Like all the serous membranes, the peritoneum is formed 
by a membrane of connective tissue, rich in elastic fibres, and covered on its 
free face by a simple tesselated layer of epithelium (the cells of which are flat 
and polygonal, and about ys); of an inch in diameter). Many blood-vessels 
are found on the adherent surface, while ymphatics are abundant in the 
visceral layer. Its nerves come from the diaphragmatic, lumbar, and inter- 
costal branches, and the great sympathetic. 


DIFFERENTIAL CHARACTERS IN THE ABDOMINAL CAVITY OF OTHER THAN SOLIPED 
ANIMALS. : 
In the Carnivora, the abdominal cavity is very narrow; while in Rumincnts it is 
very vast, its capacity being in direct relation to the volume of the viscera it contains, 


THE STOMACH. 


The general disposition of the peri 
only notable diversities being remark. 


385 


toneum varies but little in the different species, the 


0 abl ed in the great omentum. In the Oa, Shee p, and 
Goat, this is detached from the middle of the lower face of the rumen, and dnvalaps tho 


right sac of that organ, fixing the fourth compartment to its great curvature, and thcn 
passing upwards to become continuous with the mesentery. In the Dog and Pig, this 
fold descends in front of the intestinal mass until near the pelvis ; then it ascends in 
gathering on itself, and ultimately spreads over the colon: in the middle portion of the 
great omentum there are, consequently, four layers placed against each other. 


COMPARISON OF THE ABDOMINAL CAVITY OF MAN WITH THAT OF ANIMALS, 


The abdominal cavity of Man is elongated vertically, and has an inferior cavity 
occupying the entrance to the pelvis. There is nothing particular to note in its disposi- 
tion, the differences observed in it being allied to the external shape of the body. The 
peritoneum is spread over its parietes nearly in the same manner as in the Carnivora ; 
ihe great omentum is constituted by four layers, and covers the intestines like an apron: 
between its two lamine is the lesser cavity of the omentum, Virtually in the adult. 


THE STOMACH. 


The stomach is a membranous sac comprised between the cesophagus 
and intestines, and in which are commenced the essential phenomena of 
digestion. 


1. The Stomach in Solipeds. (Figs. 182, 183, 184, 185, 186.) 


Preparation.—In order to study the relations of this organ, it suffices to open the 
abdomen and remove the intestinal mass in the following manner :—Place the animal in 
the first position, and very slightly inclined to the left side; make an incision through 
the inferior abdominal wall, or, still better, carry it away entirely by a circular incision, 
taking care not to wound any part of the intestine. The entire viscera should then be 
withdrawn from the abdominal cavity, and laid on the table which supports the subject ; 
for this mass cannot be allowed to fall on the ground without risk of being pulled and 
torn, either in the intestine itself, or those parts which it is desired to preserve intact in 
the abdomen. Incise the fleating colon where it joins the rectum, and the duodenum 
where it passes behind the great mesenteric artery; the base of the cecum should now 
be detached from the sublumbar surface by the rupture of the cellular tissue which 
connects it to the right kidney and the pancreas; the cellular connection between the 
latter gland and the terminal extremity of the fourth portion of the large colon should 
also be broken; after this, it is only necessary to divide the attachment uf the mesenteric 
bands to the sublumbar region, with the vessels contained between them. The intestinal 
mass is then definitively expelled from the abdominal cavity. In this way it is possible to 
expose, and conveniently prepare, not only the stomach, but also the spleen, liver, pancreas, 
kidneys, ureters, etc. Nothing more remains than to make known the procedure to be 
adopted in everting the stomach, in order to study its internal surface, or dissect its deep 
muscular layer. It is recommended, first, to excise the stomach with at least three inches 
of the cesopnagus, and eight inches of the duodenum, and cleanse the interior of the organ. 
This may be done in several ways, but the following is the simplest :—2 certain quantity 
of water is introduced into the stomach by fixing the duodenum to a water-tap, the 
right hand manipulating the organ while the left closes the duodenum to prevent the 
escape of the liquid. The alimentary substances contained in if are in this way mixed 
with the water, and may be expelled from the duodenum by pressing the stomach; this 
operation being repeated four or five times, thoroughly cleanses the cavity of the organ. 
To evert the inner surface, it is only necessary to introduce by the duodenum a loop cf 
wire, and make it pass through the cesophagus; a strong waxed thread is fastened in 
the loop and firmly fixed around the cesophagus, when, in pulling back the wire, this 
extremity is drawn towards the pylorus, and by caroful traction the latter is so dilated 
as to allow the passage of the cardiac end, and complete eversion of the stomach. Inflation 
will then give it its ‘hormal form and at a : mal this difference, that the mucous 

i erous tunic internal. 
oe . eee Pepa al layers of the stomach more evident, it is advisable to 
ae . sa into boiling water for some minutes, after which it should be put into 
re es feat “Th it is desired to study the external and middle layers, the stomach should 
i inflated and its serous covering removed by strips with forceps and the fingers; if the 
sem layer is to be examined, the mucous membrane must be removed by means of the 


forceps and scalpel from a stomach previously everted. 


386 THE DIGESTIVE APPARATUS IN MAMMALIA. 


Situation.—The stomack, also designated the ventriculus, is situated in the 
diaphragmatic region of the abdomen, where it affects a direction transverse 
to the median plane of the body. 

Dimensions.—lts average capacity, in an ordinary-sized Horse, is from 
3 to 34 gallons; but it varies greatly according to the bulk of the animal, 
its breed, and the nature of its food. Relatively, it is more considerable 


\ f= 


; 15, External iliac artery ; 


or ventriculus of stomach; 4, Left 
Posterior vena cava; 10, Posterior 


Fig. 182. 
, Supra-renal capsule; 8, Ureter; 9, 


d magnus + 13, Iliac psoas; 14, Tensor vaginz 


Middle lobe; 3, Right extremity, 


6, Left kidney; 7 
aorta; 11, 12, Psoas parvus an 


THE ABDOMINAL CAVITY WITH THE STOMACH AND OTHER ORGANS. 
16, Internal iliac artery. 


1, Right lobe of liver; 2, 
extremity ; 


in common-bred Horses, and in the Ass and Mule. When empty, its average 
weight is between 3 and 4 pounds. 

. Form.—Elongated laterally, curved on itself, often constricted in 
its middle, and slightly depressed from before to behind, this reservoir 
presents, externally : 1, Two faces—an anterior and posterior, smooth and 
rounded; 2, A great or convex curvature, forming the inferior border of the 


15 tea lati ace ad 


THE STOMACH. 387 


organ, and giving attachment, throughout its extent, to the great omentum— 


. a membranous fold which has been described as a dependency of the serous 


membrane; a lesser or concave curvature, into which the cesophagus is 
inserted, and which is united, to the right of that canal, to the liver, by 
means of a frenum known as the hepato-gastric ligament; 4, A left ex- 
tremity, dilated in the form of a large conical tuberosity, and constituting 
the left cul-de-sac (or fundus) of the stomach ; 5, A right extremity, narrower, 
curved upwards, and continued by the duodenum, from which it is separated 
by a marked constriction: this is named the right cul-de-sac of the 
stomach. 

Relations.—Studied in its connections with the neighbouring organs, the 
stomach is related: by its anterior face, with the diaphragm and liver; by 


Fig. 183, 


SK, 
Agee 


(ih | i). 
7 
oy 
nl ’ Ow 


STOMACH OF THE HORSE. 
A, Cardiac extremity of the esophagus; B, Pyloric ring. 


i i ith the diaphragmatic curvature of the colon. Its 
eS ance to the Tet "0 the spleen, which is suspended from 
it by means of "the great omentum, is separated from the inferior abdominal 
iL by the large anterior curvatures of the colon; its distance from this 
wil ay ends upon the fulness of the organ. The left extremity, suspended 
forth caplumbar region by the aid of a very short serous ligament, a portion 
f the ee omentum, responds to the base of the spleen, the left extremity 
of ‘te eee and, less directly, to the anterior border of the left kidney. 


888 THE DIGESTIVE APPARATUS IN MAMMALIA, 


The right extremity, lower than the left, touches the right lobe of the liver 
and the above-mentioned intestinal curvatures. 

Interior.—When a stomach is opened to study its interior, one is at first 
struck by the different aspect its internal membrane presents, according as 
it is examined to the right or left. To the left, it has all the characters of 
the cesophageal mucous membrane, in being white, harsh, and even resisting ; 
it is covered by a thick layer of epithelium. To the right, it is thick, 
wrinkled, spongy, very vascular and follicular, has a reddish-brown tint 
which is speckled by darker patches, loses its consistency, and is deprived 
of the remarkable epidermis it exhibits on the left side, to be covered by 
a very thin epithelial pellicle. It is not by an insensible, but a sudden 
transition that the mucous membrane of the stomach is thus divided into 
two portions; and their separation is in- 
dicated by a salient, more or less sinuous, 
and sharply-marked ridge. This crest, 
then, divides the stomach into two com- 
partments: a division already indicated 
externally by the circular depression 
observed in the majority of subjects. 
The left sac or compartment is considered 
as a dilatation of the esophagus. The 
right sac constitutes the true stomach of 
Solipeds; as on it alone devolves the 
secretory function which elaborates the 
gastric juice, the essential agent of diges- 
tion in this organ. 

The interior of the stomach (Fig. 
184) offers for study two apertures: the 

INTERIOR OF THE HORSE’S STOMACH, cardiac and pyloric. The cardiac, or 
A, Left. sac; B, Right sacs ¢, Duodenal esophageal orifice, is in the lesser curva- 
dilatation. , ture of the left sac of the stomach. Its 
disposition has given rise to numerous 
discussions, as in it has generally been sought the reason why Solipeds 
vomit with such extreme difficulty. At one time there has been des- 
cribed a semilunar or spiroidal valve, which is opposed to the retrograde 
movement of the food; and at another time it was the oblique insertion of 
the cesophageal canal, resembling that of the ureters into the bladder, and 
which, by a mechanism analogous to these, proved an obstacle to the return 
of aliment into the cesophagus. Both suppositions are wrong. When we 
attentively observe the manner in which the cesophagus comports itself at 
its termination, it will be noticed that it is inflected downwards, after travers- 
ing the right pillar of the diaphragm, and is inserted almost perpendicularly 
into the lesser curvature of the stomach. In opening into this viscus, 
the cesophagus does not widen into an infundibulum, as in other animals; 
on the contrary, its calibre is here narrower than elsewhere, and its cardiac 
or stomachal orifice, completely obstructed by the folds of mucous membrane, 
only occupies an infinitely small portion of the internal surface of the 
stomach. 

With regard to the pylorus, it represents a large aperture formed at the 
bottom of the right sac, and furnished with a thick circular ring; this 
opening can be completely closed through the action of the powerful 
sphincter surrounding it. 

Srrucrure.—The parietes of the stomach are composed of three 


Fig. 184, 


THE STOMACH, ; 389 


pen an external, or serous ; a middle, or muscular ; and an internal, 

1. Serous membrane.—This membrane, derived from the peritoneum, 
adheres closely to the muscular layer, except towards the lesser curvature, 
where it is constantly covered by an expansion of yellow elastic tissue, 
whose use appears to be to maintain the two extremities of the stomach 
near each other; for when this is destroyed the lesser curvature becomes 
considerably elongated. Along the whole of thé greater curvature is 
a triangular space occupied by connective tissue; this space disappears 
more or less completely as the organ becomes distended. 

Tt has three folds, which are detached from the stomach and carried on 
to the adjacent parts, and which are formed in the manner indicated 
in the general description of the peritoneum. These folds constitute 
the cardiac ligament, the gastro-hepatic ligament or omentum, and the great 
omentum, 

The cardiac ligament is a short, serous band developed around the 
terminal extremity of the cesophagus, and strengthened by fibres of yellow 
fibrous tissue. It attaches the stomach to the posterior face of the 
diaphragm, and is continuous, on each side, with the two folds about to be 
described. 

The gastro-hepatic (or lesser) ligament is a band composed of two layers, 
which leave the lesser curvature of the stomach, and are inserted into the 
posterior fissure of the liver. It is prolonged posteriorly, and to the right, 
along the duodenum, where it constitutes a peculiar serous frenum which 
will be studied with the small intestine. 

The great, or gastro-colic omentum, is detached from the whole extent 
of the great curvature, from the cardia to the pylorus, beyond which it 
extends to the duodenum. The portion surrounding the left cul-de-sac is 
excessively short, and is carried to the sublumbar wall of the abdomen, to 
which the stomach is fixed. For the remainder of its extent, this omentum 
is greatly developed, and hangs freely in the abdominal cavity, among the 
intestinal convolutions. The border opposed to the stomach is attached 
to the terminal portion of the large colon, and to the origin of the lesser 
colon. For further details, see the description of the peritoneum. These 
three ligaments fix the stomach in the abdominal cavity, in addition to the 
cesophagus and duodenum, which are continuous with it. : 

9. Muscular membrane.—This tunic, comprised between the serous and 
mucous layers, is lined internally by a covering of condensed connective 
tissue which adheres intimately to it, and which may be regarded as the 
fibrous membrane of the stomach. Dissection shows this muscular tunic to 
be composed of three superposed planes. _ ae. 

The superficial plane envelops all the right sac, and the majority of the 
fibres composing it are spread in loops around the left cul-de-sac, their 
extremities being lost on the surfaces of the organ. Some of them even 
extend over the great curvature, to the surface of the right sac; while 
others are evidently continuous with the superficial fibres of the oesophagus 
Oe oe cn plane (Fig. 185, 8) is formed of circular fibres spread 
over the whole of the organ. In the right sac, they are placed immediately 
below the serous membrane; in the left sac, they pass beneath the fibres 
of the superficial plane, and finish by becoming confounded so intimately 
with these, that towards the tuberosity formed by the left extremity it is 
impossible to distinguish them. By their aggregation around the pylorus, 

28 


350 THE DIGESTIVE APPARATUS IN MAMMALIA. 


they constitute the sphincter (or pyloric valve) which envelops that 
orifice. . : . 

The deep plane (Fig. 186, a), like the first, is specially destined for 
the left sac, and cannot be properly studied except in an everted stomach 
deprived of its mucous membrane. Much thicker than the superficial plane, 
it yet, in its general arrangement, much resembles it. Thus, its fasciculi 
present loops which embrace the left cul-de-sac, and whose extremities are 
lost on the faces of the organ, where some of them become continuous with 


Fig. 185, Fig. 186. 


MUSCULAR FIBRES OF THE STOMACH 5 DEEP AND MIDDLE MUSCULAR LAYERS EX- 


EXTERNAL AND MIDDLE LAYERS, POSED BY REMOVING THE MUCOUS MEM- 

A, Fibres of the external layer enveloping BRANE FROM AN EVERTED STOMACH. 
the left sac; B, Fibres of the middle plane A, Deep layer of fibres enveloping the left sac ; 
in the right sac; c, Fibres of the cso- B, Fibres of the middle plane which alone 
phagus. form the muscular layer of the right sac; 


C, Fibres of the esophagus. 


the circular fibres. The loops nearest the cesophagus embrace the stomachal 
opening of that canal like a cravat. It is to be remarked that the fibres 
-of this deep layer intersect those of the superficial plane; the former 
passing from the left to the right sac, in inclining downwards towards 
the great curvature, while the latter are directed to the right and slightly 
- upwards. F 
From this arrangement it results, as a glance at Figs. 185, 186 will show: 
1, That the right sac has only a single muscular plane; 2, That, on the 
contrary, the left sac has three, all of which concur in propelling the 
aliment that has accumulated in the left or cesophageal compartment into 
the right, or true stomach. 
__ 3+ Mucous membrane.— Independently of the general characters notified 
in the interior of the stomach, it has to be remarked that the gastric mucous 
membrane is united to the preceding tunic by an expansion of connective 
tissue ; though it adheres but feebly throughout the right sac, especially 
towards the greater curvature, where it is thickest; and that it has no ridges 
in the left sac, though in the right they are always present, even when the 
organ is inflated. 5 
On the surface of this membrane are seen microscopical apertures (alveoli), 
the orifices of the excretory ducts of glands; these are rare in the left sac, 


THE STOMACH, 391 


but extremely numerous in the right. In this region they are separated 
from each other by minute processes resembliag papille ; but the latter are 
only met in the vicinity of the pylorus. 

The gastric mucous membrane is composed of an epithelial layer and a 
corium, in which is distinguished a glandular and a muscular layer. The 
epithelium is stratified and tesselated in the left compartment, simple and 
cylindrical in the right sac, where it covers the little mucous processes 
that separate the glandule, and penetrates more or less deeply into the 
interior of these. 

In the left side there are found some glandular organs analogous to 
those of the msophagus, but the real glandular layer belongs only to the 


Fig. 187. Fig. 188, 


PORTIONS OF ONE OF THE CACA MORE 
HIGHLY MAGNIFIED, AS SEEN LONGITUDI- 
NALLY (A), AND IN TRANSVERSE SEC- 


PEPTIC GASTRIC GLAND. TION (B). 

u, Common trunk; 6,5, Its chief branches; 4, Basement membrane ; pe Ee 

: c, c, Terminal ceca, with spheroidal gland- cell; c, Small epithelial cells surrounding 
cells the cavity 


i ide. here are found multitudes of parallel tubular glands, united 
ey ol ae of delicate connective tissue which is very rich in a 
They secrete the gastric fluid, or furnish the mucus that covers the surface 
of the epithelium ; they are consequently distinguished as pepsine (or peptic), 
and mucous glands, the former being much more numerous than the latter. 

They are composed of a simple straight tube at their, origin Sener 
duct), which frequently divides into two or more flexuous tubes thai 


392 THE DIGESTIVE APPARATUS IN MAMMALIA. 


terminate in culs-de-sac (or glandular ceca). The epithelium is not the 
same in the two kinds of glands: the mucous glands (Fig. 189, a, ) are lined 


Fig. 189. 


MUCOUS GASTRIC GLAND WITH 


CYLINDER. EPITHELIUM. 


with cylinder-epithelium throughout their extent ; 
the peptic glands (Figs. 187,188) are lined with 
cylinder-epithelium at their origin (Fig. 187, a), 
but the secretory tubes contain round peptic cells, 
(Each ceca, when highly magnified, is found to 
consist of a delicate basement membrane (Fig. 
188, a) inflected over a series of nearly globular 
cells (6), which occupy almost the whole cavity 
_of the tube, and contain a finely-granular matter ; 
the narrow passage left vacant in the centre is, 
however, still surrounded by a layer of epithelial 
cells (c), whose small size is in striking contrast 
to the large dimensions of the gland cells.) 

The muscular layer (of the mucous membrane) 
is immediately beneath the glandular structure, 
and contains two planes of intersecting fibres. 
Lastly, the connective layer of the corium is thick 
and loose, sustains the vessels (and nerves), and 
unites the mucous to the muscular tunic of the 
stomach. 

4. Vessels and nerves.—The stomach receives its 
blood by the two branches of the gastric artery, the 
splente and its terminal branch—the left epiploic 
artery, and by the pyloric and right epiploic arteries. 
The principal arterial ramifications extend be- 
tween the mucous and muscular layers, where 
they furnish two capillary reticulations to the 


a, Wide trunk; b, b, Its cecal Glandular layer: a deep network that ‘surrounds 


appendage. 


the secretory tubes, and a superficial placed be- 
tween the alveoli. The blood is carried from the 


organ to the vena porte by the satellite venous branches. The lymphatics 


APPEARANCE OF THE PROPER GASTRIC MEMBRANE OF THE STOMACH IN AN 

INJECTED PREPARATION (HUMAN). 

A, From the convex surface of the folds or rug@ ; B, From the neighbourhood of 
the pylorus, where the orifices of the gastric follicles occupy the interspaces of 
the deepest portions of the vascular network. 


form a subserous and two deep networks at the base of the glandular 
layer and in the fibrous membrane. They enter small ganglia (or glands) 
situated along the curvatures, and from these to Pecquet’s reservoir. ‘The 


THE STOMACH. 393 


nerves are derived from the pneumogastrics and solar plexus, and in accom- 


panying the vessels show microscopic ganglia in their course; their mode 
of termination is not known. 


Funcrions.—In the stomach is begun those transformations by which 
alimentary matters are rendered capable of being assimilated. There the 
food comes into contact with the gastric fluid, by whose action its principal 
elements, and particularly the albuminoid substances, become soluble and 
absorbable, after undergoing some isomeric changes. 


DIFFERENTIAL CHARACTERS IN THE STOMACH OF OTHER THAN SOLIPED ANIMALS. 


_The stomach is an organ that exhibits great differences in the various domesticated 
animals, In the study of these differences, we will proceed from the simple to the 
complex. ; 

1. The Stomach of the Pig. 


The Pég’s stomach is simple, like that of the Horse, but it is less curved on itself, and the 
cardia is nearer the left extremity ; the latter has also a small conical dilatation, which 
has been compared to a cowl curved backwards. The cesophagus opens into the stomach 
by a wide infundibulum, and the mucous membrane of that conduit is prolonged over 
the gastric surface in a radius of from two to three inches around the cardia. Here 
again we find a “trace of the division into two sacs,” common to Solipeds. 

The capacity of the Pic’s stomach averages from one and a half to two gallons. 
(The muscular tunic is thicker in the right than the left extremity; near the cesa- 
plagus the serous tunic shows some transverse folds.) 


2. The Stomach of Carnivora, (Fig. 191.) 


In the Dog and Cat the ventriculus is but little curved, and is pear-shaped, the 
small extremity corresponding to the : 
pylorus. The cardia is dilated like a Fig. 191. 
funnel, and is nearer the left extremity 
of the organ than in other animals. The 
cesophageal mucous membrane is not con- 
tinued beyond the margin of that orifice, 
The simple stomach of Carnivora forms 
only a single sac, whose internal mucous 
membrane presents, throughout its whole 
extent, the same organisation as the 
membrane lining the right sac of Soli- 
peds. This membrane is remarkable for 
the regular and undulated folds it forms 
when the stomach is empty. Nothing 
is more variable than the capacity of the 
Dog’s stomach, because of the great dif- 
ferences in the size of this animal, accord- 
ing to breed. M. Colin has found the 
minimum to be 1} pints, and the maxi- 
mum 12 gallons; he calculates the aver- 
age to be about 24 quarts. In the Cat, 
the average is from 2 to 2% gills. 


3. The Stomach of Ruminants. 


These animals are distinguised from 
the others by the fuculty they possess 
of swallowing their food after imperfect 
comminution, and causing it to return 
again into the mouth to submit it toa 
second mastication, previous tedinel on 

lutition. The gastric apparatus is ad- 
eitably Pavits to effect this physio- A, Esophagus; B, Pylorus. 

i lity, and is remarkable forits : 
pi Snag oe kaa as well as its division into four separate pouches, which are 


regarded as so many stomachs, 


“STOMACH OF THE DOG. 


394 THE DIGESTIVE APPARATUS IN MAMMALIA. 


iti i + of the 
These cavities represent a considerable mass that fills the greater par 

sidoriun cavity, ard the medium capacity of which is not less than fifty-five gallons! 
One of them, the rumen, into which the cesophagus is inserted, constitutes nine-tenths 
of the total mass. The other three, the reticulum, omasum, and abomasum, form a short 
chain, continuous with the left and anterior portion of the rumen. The abomasum alone 
should be considered as a true stomach, analogous to that of the Dog, or the right sac of 
the ventriculum of Solipeds. The other three compartments only represent, like the 

‘ in the latter animals, cesophageal dilatations, ; : 
“ae dacatiption about to be piven of each of these divisions more particularly applies 
to the Ox ; eare will be taken, in the proper place, tv note the special peculiarities in the 

f the Sheep and Goat. ; . 
ee (Fig. 192)._This reservoir, vulgarly designated tle paunch, alone occupies 
three-fourths of the abdominal cavity, in which it affects a direction inclined from above 

to below, and from left to right. 


STOMACH OF THE OX, SEEN ON ITS RIGHT UPPER FACE, THE ABOMASUM BEING DEPRESSED. 


A, Rumen, left hemisphere; B, Rumen, right hemisphere; c, Termination of the 
cesophagus ; D, Reticulum; &£, Omasum; F, Abomasum. 


External conformation.—Elongated from before to behind, and depressed from above 
to below, it offers for study: 1, An inferior anda superior face, nearly plane, smooth, 
and divided into two lateral regions by traces of fissures, which are only sensible at the 
extremities of the organ; 2, A left and right border, smooth, thick, and rounded; 
3, A posterior extremity, divided by a deep notch into two lobes, described by Chabert 
by the name of conical cysts; 4, An anterior extremity, offering an analogous 
arrangement, and concealed, at first sight, by the stomachs (or compartments) superadded 
to the rumen; the notch on the right of this extremity divides it into two unequal 
pouches, which will be yeferred to presently, 

It is to be remarked that these two notches, which are prolonged on the surface by 
furrows that separate these into two lateral regions, divide the rumen into two sacs, & 
right and left; this division we will find more manifest in the interior of the viseus. The 
right sac, the shortest, is in great part enveloped by the serous covering which 
constitutes the reat omentum. The left sae surpasses the other by its two extremities, 
except in the Sheep and Goat, in which the right conical cyst is longer than the 
lft. The anterior extremity of this left sac is thruwn backwards on the corresponding 


THE STOMACH. 395 


lobe of the right sac; above, it receives the insertion of the cesophagus, and is continuous, 
in front, with the reticulum. 

Relations.—The external form of the rumen being determined, the study of its 
relations becomes easy. By its superior surface, it is in contact with the intestinal 
mass ; its opposite face rests on the inferior abdominal wall. Its left border, supporting 
the spleen, touches the most elevated part of the flank and the sublumbar region, to 
which it adheres by cellular tissue, as well as the vicinity of the coeliac trunk and the great 
mesenteric artery; the right border, margined by the abomasum, responds to the most 
declivitous portion of the right hypochondriac and flank, as well as to the intestinal 
cireumvolutions. The anterior extremity, bounded by the reticulum and omasum, 
advances close to the diaphragm; the posterior occupies the entrance to the pelvic 
cavity, where it is more or less in contact with the genito-urinary o1gans lodged there. 
In the pregnant female, the uterus is prolonged forwards on the“upper face of the viscus 
just described. 

Interior (Fig. 193).—In the interior of the rumen are found incomplete septa, which 
repeat the division into two sacs already so marked externally. These septa are two in 


INTERIOR OF THE STOMACH IN RUMINANTS; THE UPPER PLANE OF THE RUMEN 
AND RETICULUM, WITH THE @SOPHAGEAL FURROW. - 

A, Left sac of the rumen; 8, Anterior extremity of that sac vena back - S 

"right sac; €, Its posterior extremity, or left conical cyst; @, oe ° a e 

anterior pillar of the rumen; 9, 9, Its two superior branches ; e soak pil . 

of the same; A, A; h, Its three inferior branches; 1, Cells of the reticulum; J, 


Csophageal furrow; &, Csophagus ; L, Abomasum, : 


e muscular pillars, which correspond i iferiorly to the 
aie eens ae ane ee te the organ. The anterior wile (Fig. 193,°@) 
re a i the inferior wall of the rumen a strong prolongation, directed backwards, and 
to t = left : ‘t js continued on the superior wall by two branches, which separate at an 
one le : The posterior pillar (Fig. 193, H), more voluminous than the preceding, 
ena bi ches at each of its extremities—a middle and two lateral. The middle 
heh amne ante forwards on the limit of the two sacs, which they separate from one 


another; that from above meets the corresponding branch from the anterior pillar The 


396 THE DIGESTIVE APPARATUS IN MAMMALIA. 


lateral branches diverge to the right and left in describing a curve, and in cireumscrib- 
iny the entrance to the conical cysts, which they transform into two compartments 
distinct from the middle portion of the sacs of the rumen; the inferior go to meet the 
superior branches, but do not altogether join them. ; ; ; 

‘he internal surface of the rumen is covered by a multitude of papillary prolongations, 
dependencies of the mucous membrane. ‘To the right, and in the culs-de-sac, these 
papille are remarkable for their number, their enormous development, and their general 
foliated shape. On the left side they are more rare, particularly on the superior wall, 
and only form very small mammiform tubercles; they are absent on the muscular 
columns. This papillary arrangement is still more developed in certain wild Ruminants, 
and it is scarcely possible to give an idea of their richness in the stomach of the 

zelle. 
oe The interior of the rumen offers for study two openings, situated at the anterior 
extremity of the left sac: one is the cesophageal orifice, pierced in the superior wall, 
dilated into an infundibulum, and prolonged into the small curvature of the reticulum 
by a particular furrow (or channel), which will be described after the latter compart- 
ment; the other, placed below, and opposite the preceding, traverses the bottom of 
the cul-de-sac from before to behind, and forms the communication between the paunch 
and reticulum: it is a very Jarge opening, circumscribed below and on the sides by a 
septum or semilunar valve, resulting from the junction of the parietes of the rumen with 
those of the reticulum. ; 

Structure.—Like all the hollow organs in the abdomen, the rumen has three tunics: 
a serous, a muscular, and a mucous. 

The serous envelops the organ throughout, except above, in front, and to the left, 
the point which touches the sublumbar region, and the pillars of the diaphragm, as well 
as the bottom of the notches which separate the culs-de-sac from the extremities. This 
membrane gives origin, like that of the stomach of the Horse, to a vast duplicature— 
the great omentum. ‘The arrangement of this, which is somewhat difficult to observe 
in the Ox, in consequence of the enormous weight of the gastric mass, is readily seen 
in the smaller Ruminants. It begins at the middle of the faces of the paunch and the 
fissure intermediate to the two conical cysts, forming a wide envelope that contains 
the right sac and the abomasum; it becomes attached in passing over the great 
curvature of the last-named cavity, and is confounded, superiorly and posteriorly, with 
the great mesentery. 

The muscular coat is very thick, and forms the internal columns of the viscus. Its 
fibres are disposed in several layers, whose urrangement is simple, and offers nothing 
really interesting to study, except in the points where the serous tunic passes from one 
cul-de-sac to another, or from the rumen to the reticulum; there it is often accompanied 
by thin and wide muscular fasciculi which, like the latter membrane, stretch over the 
intermediate fissures, and thus become real unitive or common fibres. 

The muscular fibres of the rumen present an unmistakable transverse striation—a 
very rare physical characteristic in the muscular tissue of orgunic life. 

The inucous membrane offers some peculiarities, which deserve a few words. The 
corium is very thick, and probably contains some glands, but they must be extremely 
few. The free face of the membrane is excessively uneven, in consequence of the 
papillary apparatus mentioned above. 

The papillz of the rumen are foliaceous, conical, or fungiform. Those of the first 
description are much more numerous than the others; they have the shape of an oval, 
elongated leaf, their summit is wile and rounded, and the base narrow and apparently 
implanted in the corium, On one face is a little rib that springs from the base and 
disappears on the widened portion, resembling the principal vein or nervule of a leaf. 
On the other face, opposite the vein, is a faint longitudinal groove. 

_ These papille are constituted by a layer of nucleated connective tissue, covered by 
epithelium ; the former, in the principal papille, has on its faces and extremities minute 
prolongations, resembling on a small scale the secondary papillw described as existing 
on the lingual mucous membrane. In the centre of the papillm are one or two main 
arteries, derived from the network of the corium. These pass, in a slightly flexuous 
manner, to the summit, and break up into several branchlets, succeeded by veins, that 
descend along the surface of the papilla into each of its secondary prolongations. 

The conical and fungifurm papille are few in the left sac, and resemble the papilla 
of the same name described on the tongue. 

The epithelium of the mucous membrane of the rumen is remarkable for its strength 
and cohesiveness, It belongs to the category of stratified tesselated epithelium, and 
forms a sheath to each papilla, covering the corium in the interpapillary spaces. 

There are frequently found, in opening the rumen of animals just killed, large 


} 


THE STOMACH. 307 


exfoliated patches on the surface of this layer. This is a sufficient indication of the 
activity of the secretion of the epithelium, and the rapidity of its renovation. 

Rericutum (Hoxrycoms) (Figs. 192, 193).—Sttuution—Form—Kelations.—This, the 
smallest compartment, is elongated from one side to the other, slightly curved on itself, 
and placed transversely between the posterior face of the diaphragm, in one directiun, 
and the anterior extremity of the left sac of the rumen in the other; the latter only 
appearing, externally, to be a prolongation, or a diverticulum of the rumen. 

It has two fuces, two curvatures, and two eatrenities. The anterior face adheres to 
the phrenic centre of the diaphragm by cellular tissue. The postertor face lies against 
the anterior extremity of the rumen. The greut inferior or convex curvature occupies 
the suprasternal region. The lesser, superior, or concave curvature partly responds to 
the lesser curvature of the omasum. The left extremity is only separated from the rumen 
by a fissure, which lodges the inferior artery of the reticulum. The right eatremity forms 
a globular cul-de-sac, in relation with the base of the abomasum. 

Interior (Fig. 193).—The internal surface of the reticulum is divided by ridges of 
the mucous membrane into polyhedral cells, which, in their regular arrangement, look 
like a honeycomb; tliey are widest and deepest in the cul-de-sac, and become gradually 
smaller in approaching the superior curvature. The interior of these cells is divided 
into smaller spaces, included one within the other, by secondary and successively-decreas- 
ing septa. The principal septa offer on their free border a series of conical prolonga- 
tions, with a rough hard summit; while their faces are studded with minute, blunt, or 
pointed papille. The secondary septa also show similar prolongations; and those on 
their free margin are even more developed than on the chief septa. Lastly, from the 
bottom of the cells spring up a crowd of long, conical, and very pointed papillz, resem- 
bling stalagmites in their arrangement. 5 

It may be noted that the foreign bodies so frequently swallowed by Ruminants, are 
usually lodged in the reticulum ; therefore it is that at the bottom of the cells are found 
either small stones, and needles or pins, often fixed in the intermediate septa, or nails, 
scraps of iron, etc. ‘The interior of the reticulum communicates with the left sac of the 
rumen by the orifice already described, aud with the omasum by particular open- 
ing, placed near the middle of the small curvature, though a little more to the right 
than the left. “This opening, cight or ten times smaller than the preceding, is 
connectel with the infundibulum of the cardia by a remarkable groove (or channel), 
the esophageal, which will be described separately, as it does not properly belong to the 
aay Se serous membrane does not cover all the anterior surface of the organ, 
as the latter adheres to the posterior face of the diaphragm. The muscular tunic is much 
thinner than that of the paunch, and more fasciculated. The fibres pass in the same 
direction. The coréum-+of the mucous membrane sends a prolongation into each of the 
septa of the alveoli, and into each of the conical papill on these septa, or to the bottom 
of these alveoli. The stratified emer pala is very thick, and its horny layer 
i the summit of the papille. : 

‘i pS Ree ae aie (Fig. 198).-— This gutter is so named because it appears to 
continue the cesophagus to the interior of the stomach. It extends on the lesser 
curvature of the reticulum from the cardia to the entrance of the omasum ; commencing 
in the rumen, it belongs to the reticulum for the remainder of its extent. Measuring 
from six to eight inches in length, this demi-canal is directed from above downwards, 
and from left to right, between two movable lips, which are fixed by their ora 
border to the superior wall of the reticulum. These two lips are thickened at a i 

i hich look downwards and to the left. . At their origin at the cesophagea 
F aciicahin they are thine and but slightly élevated; but they . become thick and 
salient on arriving near the orifice of the omasum, which orifice they surround, though 
they neither meet nor become confounded with each other. r a 

The mucous membrane covering these two lips is much corrugated outwardly an 
on the free border; but in the interior of the groove it possesses all the caer eics of the 
cesophageal mucous membrane in being smooth, pate in ridged longitudinally ; near. 

= i q onical papille : “ 2 
the orifice of the omaéum a acre oeea avec tissue, the following arrangement 

If this membrane be cee th channel, and in the space comprised between its two 
is observed: At the Lasse : Gyhich belong to the rumen or reticulum. The lips 
lips, are transvers®, see ene mel of longitudinal muscular fasciculi, particularly abun- 
Fy paleo oS a aes + these fusciculi are confounded with the proper fibres of the 


remiti é ried from one lip to the other 
y xtiemities of the canal, and_are carried 1 
ee ant che the orifices which communicate ‘by this canal. 


~ Omasum (Psalterium, ManyY-PLigs, MANY-LEAVES, Or Manyeuvs. Fig. 192)—In the 


398 THE DIGESTIVE APPARATUS IN MAMMALIA 


Ox, this compartment is larger than the reticulum, but in the Sheep and Goat it is 
nar ee ee rec above the cul-de-sac of the reticulum and the 
anterior extremity of the right sac of the rumen, this compartment, when distended, has an 
oval form, is slightly curved in an opposite direction to the honeycomb division, and 
depressed from befure to behind. It has, therefore, an anterior face, applied against the 
diaphragm, to which it is sometimes attached by connective tissue; a posterior face lying 
towards the paunch: a great curvature, turned upwards, and fixed in the posterior fissure 
of the liver by an omental frenum which is continued on the lesser curvature of the 
abomasum and duodenum; a lesser curvature, which looks downwards and responds to 
the reticulum; a left extremity, exhibiting the neck, which corresponds to the orifice of 
communication between the reticulum and many-plies; a right extremity, continuous 
with the base of the abomasum, from which it is separated by a constriction analogous to 
that of the anterior extremity, but much less marked. : 
Interior —This compartment shows in its interior the two apertures placed at its extre- 
mities. The right orifice, opening into the ubomasum, is much wider than the left, which 


SECTION OF THE WALL OF THE OMASUM OF THE SHEEP: FROM THE GREAT CURVATURE, 
SHOWING THE ORIGIN OF THE LEAVES. 
P, Peritoneum; M, The two muscular layers; §, Epithelium; 1, 1, Principal leaves 
at their origin; 2, Secondary leaf; 3, 3, Leaves of the third order; 4, Denticu- 
lated lamina; 5, 5, Two planes of muscular fibres ascending into the principal 
leaves, some issuing from the muscular layer of the organ. 


communicates with the reticulum. 'The cavity which these orifices bring into communica- 
tion with the adjoining compartments, offers one of the most curious arrangements met with 
in the viscera; it being filled by unequally-developed leaves of mucous membrane, which 
follow the length of the cavity. These laminzw have an adherent border attached either 
to the great curvature or to the faces of the organ, and a free concave border turned 
towards the lesser curvature. They commence at the side of the orifice of the reticulum 
by denticulated ridges, between which are furrows, and which are prolonged from the 
base of the leaves tc the entrance of the abomasum. Af the latter aperture they 
disappear altogether, after rapidly diminishing in height. Their faces are studded by a 
multitude of very hard mamillary papilie, resembling grains of millet, which are more 
developed and conical on some of the leaves than others, Ail these lamellar prolongations 
are far from being of the same extent: twelve to fifteen are so wide that their free border 
nearly reaches the lesser curvature of the viscus, and between these principal leaves are 
others which, though regularly enough arranged, are more or less narrower. At first 
there is remarked a secondary leaf, half the width of the chief ones, between which it is 
placed; then, on each of its sides, another, one-half narrower; and, lastly, at the base of 
these, two denticulated lamin more or less salient. In a general way, the lamina which 
are inserted into the great curvature are the longest and widest; and those attached to 
the faces of the viscus become shorter and narrower as they draw nearer the lesser 
curvature. The space comprised between these prolongations is always filled by very 
attenuated alimentary matters, which are usually impregnated by a very small quantity 
of fluid, but are also often dry, and sometimes even hardened into compact flakes. 


THE STOMACH. 399 


Structure—The serous layer is a dependency of the peritoneum, and offers nothing 
particular; it does not completely cover the anterior face. 

The muscular tunic is much fasciculated, and thin. 

The mucous membrane is remarkable for the thickness of its stratified pavement 
epithelium ; all the leaves are formed by two layers of this membrane, laid one against the 
other; and as their structure is interesting, we will notice it. 

The principal leaves are composed of this duplicature of mucous membrane, and two 
layers of muscular fibres between ; these layers are opposite each other at the commence- 
ment of the leaf, and separated by a transverse vessel; in the remainder of their extent 
they are kept apart by the vessels that pass towards the border of the leaf. Their fibr:s 
are detached from the surface of the muscular tunic and, at certain points, from its deep 
layer. In the smaller leaves there appears to be only one layer of muscular fibres; on 
all the leaves are various-sized papille, the smallest of which are like a grain of millet, 


Fig. 195, Fig. 196, 


SECTION OF A LEAF OF THE OMASUM. LONGITUDINAL SECTION OF A LARGE PaA- 
1, 1, Muscular planes; v, vessel; 2, Epithe- FILLA FROM Gack i diame SHOWING 

lium; 3, 3, Small-sized papille, round NERVE-CELLS IN i 

and hard. 


for base a mass of condensed. connective tissue, whose superficial fibres form a 
Gador thal (Fig. 195); the largest are club-shaped. They receive blood-vessels. and 
we have found in the connective tissue, elements witha somewhat irregular outline. pro- 
vided with nuclei, which we considered to be nerve-cells (Fig. 196.) : 
ApomasuM (REED or Rexnev. Figs. 192, 193).—Situation— Form— Relations.—The 
abomasum stands next to the rumen for capacity. It isa pyriform reservoir, curved on 
itself, elongated from before to behind, and situated behind the omasum, above the right 
sac of the rumen. On the right it touches tlhe diaphragm and the hypochondriac; on 
the left it is related to the rumen. The greater curvature, turned downwards, receives 
the insertion of the great omentum. The lesser curvature, inclined upwards, gives 
attachment to the serous band already noticed when speaking of the great curvature a 
the omasum, Its base is in contact with the cul-de-sac of the reticulum, and is separated 
from the omasum by the constriction in the form of a thick neck, which corresponds te 
the communicating orifice of the two stomachs. Its point, directed upwards and back- 
i inue denum. an 
eo Bee ee <Hre stumach of Ruminants, the mucous membrane lining 
its interior acquires all the characters which distinguish that of the stomach Ss pt 
Carnivora, or that of the right sac of the Horse’s stomach. — It is soft, spongy, ae Aa 
the touch, vascular, red-coloured, covered by a thin epithelium, and provide t a 4 
nese glands for the secretion of the gastric juice. Thinner pre 2 mercies tic 
animals, this tenuity is compensated for by a much greater extent 0 glee: which is 
ill further increased by numerous lamellar folds. These latter are analogous pula 
stitution to those of the omasum, cross in a very oblique manner the great axis of the 
abomasum, and altogether affect a kind of spiral ated aineanaian 
bomasum has two apertures : one, situated at its base, opens ' eh 15 
ing othe placed opposite to the first, and eet narrower, is the pylorus, which is 
: i i i by a muscular ring. 
ee "The ae peal contgnatoTlé with ihe omenta which abut on the 
Se ae urvatures of the viscus. The muscular layer is of the same thickness 
Seal a ers The internal tunic has already been noticed. , 
sa a er ge STOMACH IN ReuminanTs.—We cannot pretend to give here a 
Peat Por the phenomena of rumination, but must confine ourselves to describe 


Saat verag wind are the principal attributes of each gastric dilatation. 


400 THE DIGESTIVE APPARATUS IN MAMMALIA. 


The rumen is a sac where the aliment taken during feeding-time is kept in reserve, 
and whence it is again carried into the mouth during rumination, after having been 
more or less softened. ears : 

The reticulum participates in the functions of the rumen, to which it is only a kind 
of diverticulum. But it is particularly with regard to liquids that it plays the part of a 
reservoir; the solid substances contained in it being always diluted by a larger quantity 
of water. 

The wsophageal groove carries into the omasum the substances swallowed a second 
time after rumination, or even those which the animal ingests in very small quantity for 


the first time. b As ee ites! 
The omasum completes the trituration and attenuation of the food, by pressing it 
between its leaves. : : Soh 
The abomasum acts as a true stomach charged with the secretion of the gastric juice ; 
in this reservoir occur the essential phenomena of gastric digestion, 


COMPARISON OF THE STOMACH OF MAN WITH THAT OF ANIMALS, 


In its form, the stomach of Man much resembles that of the Carnivora. 

The insertion of the esophagus, however, does not offer so large an infundibulum. 
The organ is situated in the left hypochondriac, and is nearly horizontal. 

Everywhere the mucous membrane is red and glandular; the muscular fibres are 
disposed in three planes, as in Solipeds; but the superficial and deep are particularly 
directed towards the left sac. 


THE INTESTINES. (Figs. 204, 205, 206.) 


The alimentary canal is continued from the stomach, in the abdominal 
cavity, by a long tube doubled on itself a great number of times, and 
which terminates at the posterior opening of the digestive apparatus, 
This tube is the intestine. Narrow and uniform in diameter in its ante- 
rior portion, which is named the small intestine, it is irregularly dilated 
and sacculated in its posterior part, the large intestine. These two por- 
tions, so markedly defined in all the domesticated mammals, are but im- 
perfectly distinguished from one another with regard to the digestive 
phenomena occurring in their anterior. We will study them in all the 
animals which interest us, and conclude by a general and comparative 
examination of the entire abdominal portion of the digestive canal. 


Preparation.—The study of the intestines does not demand, properly speaking, any 
special preparation; it being sufficient to incise the inferior wall of the abdomen to 
expose these viscera. As their mass, however, is heavy and unmanageable, it is 
advisable to expel their contents in a manner similar to that recommended for the 
preparation of the stomach; a puncture at the point of the cecum allows the escape of 
the substances accumulated in that reservoir—those which fill the large colon may be 
removed by an incision made toward the pelvic curvature, and those in the floating colon 
by the rectum. The small intestine may be evacuated by three or four openings at 
about equal distances in the length of the viscus. Having done this, inflate the 
intestines to somewhat of their natural volume; this preparation then permits the gen- 
eral arrangement of the intestinal mass in the interior of the abdomen to be easily studied. 

It would be well to remove the entire mass altogether from the body, and lay it out on 
a table, so as to isolate the various parts, study them in succession, and note their form. 


1. The Small Intestine. (Figs. 204, 205, 206.) 


Length—Diameter.—The small intestine is a long tube, which, in a 
horse of ordinary height, may average about 24 yards in length, and from 
1 to 17 inches in diameter. This diameter is susceptible of variation, 
according to the state of contraction of the muscular tunic of the viscus, 

Form.—This tube is cylindrical, doubled on itself, presenting two cur- 
vatures: one convem, perfectly free; the other concave, called the small cur- 
vature, which serves as a point of insertion to the mesentery that sustains’ 


THE INTESTINES. 401 


the organ. Removed from the abdominal cavity, freed from the serous folds 
which suspend it, and distended by air or water, this disposition of the 
small intestine naturally causes it to twist in a spiral manner. 

Course and Relations.—The small intestine commences at the right cul- 
de-sac of the stomach, from which it is separated by the pyloric constriction. 
At its origin it presents a dilatation which, in form, closely simulates a small 
stomach, whose curvatures are the inverse of those of the proper stomach. 
Placed at the posterior face of the liver, this expansion, or head, of the small 
intestine begins the narrower portion, which at first is directed forward, 
then bends suddenly backward : thus forming a loop investing the base of 
the cecum on the right side; then it is carried to the left in crossing, trans- 
versely, the sublumbar region, behind the great mesenteric artery; here it is 
joined to the origin of the floating colon by a very short serous frenum. It 
then reaches the left flank; where it is lodged, and where it forms numerous 
folds that are freely suspended in the abdominal cavity among the convolu- 
tions of the small colon. The terminal portion of this conduit, which is 
easily recognised by the greater thickness of its walls and its smaller 
diameter, disengages itself from these convolutions to return to the right, 
and opens into the concavity of the cecum, below, and a little tothe inside 
of, the point where the large colon has its commencement. 

In the language of the schools, this terminal portion is named the ileum 
(ciAetv, to twist); the part which is suspended in the left flank, and which 
forms the principal mass of the intestine, is designated the jefunum (jejunus, 
empty); and the curvature formed by this viscera at its origin, from the 
pylorus to the great mesenteric artery, is termed the duodenum (twelve 
fingers’ breadth). 

This classical division is, however, altogether arbitrary, and scarcely 
deserves to be retained, It would be better to divide the intestine into a 
fixed or duodenal, and a free or floating portion. * 

Mode of attachment—The small intestine is maintained in its position, 
st its extremities, by the stomach and the cecum. But its principal means 
of fixation consists in a vast peritoneal fold, which, from its use, is named 
the mesentery (pécor, évtepov). : ; ; 

This serous layer presents a very narrow anterior part which sustains 
the duodenum, and fixes it in such a manner as to prevent its experiencing 
any considerable displacement, Continuous, in front, with the gastro-hepatic 
omentum, this portion of the mesentery is successively detached from the 
base of the liver, the inferior aspect of the right kidney, or even from the 
external contour of the base of the cecum, and, lastly, from the sublumbar 
region, to be soon confounded with the principal mesentery. This becomes 
wider as it approaches the cecal extremity, and arises, as from a centre, from 
the outline of the great mesenteric artery, to spread in every direction, and 
is inserted into the small curvature of the floating portion of the viscus. 
The great length of this insertion causes it to become extended in a spiral 
or screw-like manner, around its point of origin. It may be remarked that 
the terminal extremity of the intestine is retained between the two serous 
layers of the mesentery, to a certain distance from its free border. This 
peritoneal fold consequently forms at this point, at the side opposite to 
its insertion into the intestinal tube, : particular frenum, which is observed 

i the anterior face of the cecum. 
. paar interior of the cylindrical tube formed by the small 
intestine offers longitudinal folds, which are effaced by distention, except 
towards the origin of the duodenal portion. Those met with in this situation 


Y 


402 THE DIGESTIVE APPARATUS IN MAMMALIA. 


possess all the characters of the valvulee conniventes (valves of Kerkring) of 
Man ; they resist the effects of traction exercised on the intestinal membranes, 
and are formed by two mucous layers laid together, with a plentiful supply 
of connective tissue between them. 

The internal surface of the small intestine also offers for study a mul- 
titude of villosities and glandular orifices, or follicles, which will be noticed 
hereafter. It communicates with the inner surface of the stomach by the 
pyloric orifice, and with that of the cecum by means of an opening which 
projects into the interior of that reservoir, like a tap into a barrel. This 
projection, which is not very marked, is formed by a circular mucous fold, 
strengthened externally by muscular fibres, and is named the ilio-cecal 
valve or valvula Bauhini. 'Two additional orifices open on the surface of the 
small intestine in its duodenal portion, from 5 to 8 inches from the pylorus: 
one is the orifice common to the biliary and principal pancreatic duct, the 
other that of the accessory pancreatic duct. 

Srructure.—The wall of the small intestine, like that of the other 
hollow viscera in the abdominal cavity, is composed of three tunics : 

1. Serous membrane.—This envelups the organ everywhere, except at its 
small curvature, which receives the insertion of the mesentery. 

2. Muscular coat.—Covered internally by a layer of condensed connective 
tissue (which is sometimes designated as a fourth tunic) this middle mem- 
brane has two planes of fibres: one, superficial, is formed of longitudinal 
fibres uniformly spread over the whole surface of the viscus; the other, 
deep-seated, is composed of circular fibres, which are a continuation of those 
of the pyloric ring. 

3. Mucous membrane.—Tbis tunic, extremely interesting to study, is soft, 
spongy, highly vascular, very delicate, and of a reddish-yellow colour. Its 
external face is loosely adherent to the muscular layer, and its free 
aspect exhibits the villi, and the glandular or follicular orifices already 
noticed. 

It comprises, in its structure, an epithelial covering, and a mucous 
derm or corium. 

The epithelial layer is formed by a single row of cylindrical (or columnar) 
cells, implanted, by their summit, on the surface of the derm, and lining the 
interior of the orifices which open on the inner face of the membrane. . The 
base of these cells has an amorphous cushion, which, when they are all 
united, appears like a thin layer spread on the inner surface of the 
intestine. 

The mucous derm is thick and loose in its deeper portion, and is con- 
stituted by fasciculi of connective tissue mixed with elastic fibres, and 
lymphoid elements. On its free surface it exhibits villosities and depressions, 
which correspond to the glands. It has a muscular layer, whose unstriped 
fibres are arranged in a similar manner to those of the muscular coat of the 
intestine. Lastly, it contains follicles, and vascular and nervous reticulations. 
We will study each of these. 

The villi are the foliated or conical appendages which are found to be 
most developed in the shortest portions of the intestine. In Birds and the 
Carnivora they attain their maximum length; while in Ruminants they 
are in a rudimentary state, though, whatever may be their dimensions, 
they are always visible to the naked eye. Their number is considerable, 
and they have been justly compared to the pile of velvet. In structure, they 
are formed of a small spongy mass of embryonic connective tissue, in the 
centre of which are one or more lymphatic (or lacteal) vessels, with a 


¢ 


THE INTESTINES. 403 


magnificent network of peripheral capill - ; i 
inclosed in a complete epiliclial cee aera pains Waseunte 


Fig. 197. 


A. VILLI OF MAN, SHOWING THE BLOOD-VESSELS AND LACTEALS.—B, VILLUS 
‘ OF A SHEEP, 


The orifices opening on the intestinal mucous membrane belong either to 
Brunner’s (duodenal) glands, or to those of Lieberkiihn (simple follicles). 

Brunner’s glands form a continuous ; 
layer beneath the duodenal mucous mem- 
brane. In their organisation, these small 
granular bodies are exactly like the acini 
of the salivary glands; each acinus pos- 
sesses an extremely short excretory duct, 
that passes through the mucous mem- 
brane. (These racemose glands secrete 
a clear alkaline mucus, which contains 
no formed elements, such as cells or 
nuclei.) 

The glands (or crypts mucosee) of 
Lieberkiihn or Galeati.are placed in the 
substance of the mucous membrane, and 
are distinguished by their microscopical 
dimensions, their considerable number, 
and their tubular form, which has caused 
each of them to be compared to the finger 
of a glove; they are implanted perpen- 


Fig. 198. 


PORTION OF ONE OF BRUNNER’S GLANDS, 


404 THE DIGESTIVE APPARATUS IN MAMMALIA. 


dicularly in the mucous membrane, and open on its free surface. They 
are found throughout the whole extent of the intestine, and are lined with 
ithelium. 

ote ee glands (glandule solitaris, or lenticular glands) are round, 
salient bodies, visible to the naked eye. They are somewhat rare in the 
small intestine, but are more abundant at the posterior portion of the large 
intestine. They are formed by a mass of lymphoid elements enveloped by 
some condensed fasciculi of connective tissue. Above them the mucous 
membrane is slightly umbilicated, and is destitute of villi and tubular glands, 
though these are arranged in a circle around the follicles, to form the 
corone tubulorum. (The solitary glands usually contain. a cream-like 
seeretion, which covers the villi on their free surface. ) 


Fig. 199 


PERPENDICULAR SECTION THROUGH ONE OF PEYER’S PATCHES IN THE LOWER PART 
OF THE ILEUM OF THE SHEEP 
u, u, Lacteal vessels in the villi: 6. 6, Superficial layer of the lacteal vessels (rete 
angustum); c, c, Deep layer of the Jacteals (rete amplum); d, d, Efferent vessels 
provided with valves; ¢, Lieberkiihn’s glands; f, Peyer’s glands; g, Circular 
muscular layer of the wall of intestine; 2, Longitudinal layer ; i, Peritoneal layer. 


The aggregated follicles (glandulsee agminate) are nothing more than 
solitary glands collected together in a limited space, where they constitute 
what are known as the glands of Peyer or of Pecklin, or the honeycomb 
glands. Absent in the duodenum, and even at the commencement of the 
jejunum, these glands, about a hundred in number, are very irregularly 
placed on the internal surface of the intestine at its great curvature, on the 
side opposite to the mesentery. Their form is oval or circular, and the 


THE INTESTINES. 


405 


smallest scarcely measure more than some few hundredths of an inch square ; 
while the diameter of the largest increases to 13 inch. ; 

(Each of these patches is composed of a group of small, round, whitish 
vesicles, covered with mucous membrane; these vesicles consist of a 


Fig. 200, 


Sys 
Gees 


Gt 
Ny 

hay analy agg aeo 
Ree tats 


pata 
ita ah 
a 


aul eae 


PERPENDICULAR SECTION THROUGH THE INTESTINAL WALL TO SHOW A SOLITARY FOLLICLE, 


uv, Lieberkiihnian glands; b, Solitary follicle; c, Lacteal vessels surrounding, but 
not penetrating, the follicles; d, Large efferent vessels, provided with valves. 


moderately-thick external capsule, having no excretory canal, and containing 
a similar secretion to that in the solitary follicles. ‘They are surrounded 


by a zone or band of simple follicles, and the 
spaces between them are covered with villi. The 
vesicles are usually closed; though it is supposed 
they open at intervals to discharge their secretion. 
The mucous and submucous coats of the intestine 
are intimately adherent and highly vascular, oppo- 
site the Peyerian glands.) 

4, Vessels and nerves.—The small intestine 
receives its arteries almost exclusively from the 
great mesenteric artery. One, which goes to the 
duodenum, comes from the celiac trunk. These 
arteries form a submucous network, from which 
branches pass inwards and outwards, the first to 
the muscular and serous tunics, the second to the 
glands and the villi. A tubular network sur- 
rounds each Lieberkiihnian gland, and is observed 
in each villus; while a spherical reticulation sur- 
rounds each solitary follicle, loops being given off 
which penetrate nearly to the centre of the 


follicle. 


VILLI OF INTESTINE, WITIL 
THEIR CAPILLARY PLEXUS 
INJECTED, 


Tho veins have the same arrangement, and finally enter the vena porta. 


2 


406 


THE DIGESTIVE APPARATUS IN MAMMALIA. 


The lymphatics constitute three superposed networks in the mucous 


membrane. 


The first is situated around the glandular orifices; it receives 


Fig. 202. 


4) 
M4 
i) 


KA 
if 


HORIZONTAL SECTION THROUGH THE MIDDLE PLANE OF THREE PEYERIAN GLANDS, 
SHOWING THE DISTRIBUTION OF THE BLOOD-VESSELS IN THEIR INTERIOR. 


the central lacteal from each villus; the second is placed between the 


DIAGRAMMATIC REPRESENTA- 
TION OF THE ORIGIN OF 
THE LACTEALS IN A VILLUS. 


e, Central lacteal; d, Connec- 
tive-tissue corpuscles with 
communicating branches ; 
¢, Ciliated columnar epithe- 
lial cells, the attached ex- 
tremities of which are di- 
rectly contiguous with the 
connective tissue corpuscles, 


glandular and the muscular layer of the mucous 
membrane ; finally, the third exists in the deep 
portion of the membrane, and communicates with 
the meshes encircling the closed follicles. The 
most voluminous emergent vessels pass through 
the wall of the intestine and accompany the blood- 
vessels between the layers of the mesentery, enter- 
ing the mesenteric glands, and terminating in the 
reservoir of Pecquet (receptaculum chyli). 

The nerves are from the solar plexus; they 
form a submucous reticulation and a myenteric 
pleaus, comprised between the two planes of the 
muscular tunic. 

Microscopic ganglia are found on their course. 

Devetorment.—The small intestine shows it- 
self at an early period in the fatus, and during 
the foetal existence of Ruminants preserves a very 
remarkable predominance over the large intestine : 
a predominance equally marked in the vessels it 
receives, for, in a foetus of five months, we have 
found the collective arteries of the small intes- 
tine equivalent to about ten times the volume of 
those of the cecum and colon. 

Founcrions.—It is in this tube, and under the 


THE INTESTINES, 407 


influence of the hepatic, pancreatic, and intestinal secretions, that are 
carried on those molecular transformations which properly constitute the 
digestive function. It is also in this intestine that the absorption of the 


nutritive principles and fluids commences, and in which the villi are the 
essential organs, 


2. The Large Intestine. 


The large intestine commences by a vast reservoir in the form of a cul- 
de-sac, named the cecum. It is continued by the colon, whose posterior 
extremity is succeeded by the rectum. It is separated from the small 
intestine by the dleo-cecal valve. 


A. Cocum. (Figs. 204, 205, 206.) 


Situation —Direction.—This is a very wide and elongated sac, occupying 
the right hypochondriac, where it affects an oblique direction downwards 
and backwards... Copuuctnr dh, 

Dimensions—Capacity.—Its length is ordinarily a little over three feet, 
and it will contain, on an average, about 73 gallons of fluid. 

Form—External surface.—The elongated sac formed by the cacum is 
conical in shape, terminating in a point inferiorly, and bulging and curved 
like a crook superiorly. Externally, it exhibits a great number of circular 


furrows, interrupted by longitudinal muscular bands, four of which are ’ 


observed in the middle portion of the organ; they disappear towards its 
extremities. The bottom of these furrows necessarily corresponds to the 
internal ridges, and these can be made to disappear by destroying the 
longitudinal bands, which considerably lengthens the cecum; thus showin 
that these transverse puckerings are due to the presence of the riband-like 
cords, and have for their object the shortening of the intestine without 
diminishing the extent of its surface. aes 

Relations —To study its relations, the cecum is divided into three 
regions : 7 

1. The superior extremity, base, arch, or still better, the crook, presents 
in the concavity of its curvature, which is turned forwards, the insertion of 
the small intestine and origin of the colon. Placed in the sublumbar 
region, it responds, superiorly, to the right kidney and to the pancreas, 
throuch the medium of an abundant supply of connective tissue. Outwardly, 
it touches the parietes of the right flank, and is encircled by the duodenum. 
On the inner side, it adheres by cellular tissue to the termination of 
the large colon, and is in contact with the convolutions of the small 
nee. The middle portion (meso-ccecum) is in contact, inwardly, with the same 
convolutions and the large colon; outwardly, with the cartilages of the false 
ribs. whose curvature it follows. . 

3. The inferior extremity, or point, usually rests on the abdominal pro- 
longaticn of the sternum ; but as it is free and can move about in every 
direction, it often happens that it is displaced from this situation. ; 

Mode of attachment.—The cecum is fixed to the sublumbar region and 
the terminal extremity of the large colon by a wide adherent surface. 
All around this surface the peritoneum, which constitutes the serous 
covering of the cecum, is gathered into folds, and in passing from the 
cxcum to the origin of the colon, this tunic forms a particular short and 


narrow frenum designated the meso-cecum, 


408 THE DIGESTIVE APPARATUS IN MAMMALIA. 


Interior —Viewed internally, the cecum offers for study the valvule or 
transverse ridges corresponding to the external furrows. We have already 
seen that these are due to simple circular folds, comprising in their thick- 
ness the three tunics of the organ, and that they are susceptible of being 
effaced by distention, to re-appear afterwards in varying number and position ; 
differing widely, in this respect, from the valvule conniventes of the small 
intestine. f 

Two orifices, placed one above the other, open on the internal surface of 
the cecum, at the point corresvonding to the concavity of the crook. The 


Fig. 204 


GENERAL VIEW OF THE INTESTINES OF THE HORSE; SEEN FROM THE RIGHT SIDE, 
WITH THE PELVIC CURVATURE AND A PORTION OF THE SMALL INTESTINE 
CARRIED BEYOND THE ABDOMINAL CAVITY. 

a, Esophagus ; 8, Right sac of the stomach; c, Small intestine, showing its origin, 
or duodenal portion encircling the base of the cectim; d, Cecum ; ¢, Origin of 
the large colon; f, First portion of the large colon; g, Suprasternal flexure; h, 
Second portion of the large colon; 7, Pelvic flexure; j, Third portion of the large 
colon; 4, Diaphragmatic flexure ; J, Fourth portion of the large colon; m, Ter- 
mination of the free colon; n, Rectum; v, Mesentery proper; p, Colic mesentery 
(meso-colon); 7, Neck of the vaginal canal; s, Spermatic vessels; t, Deferent 
canal; w, Bladder; v, Vesicule seminales; «x, Pelvic enlargement of the deferen 
canal; y, Prostate; z, Suspensory ligament of the penis. 


most inferior represents the terminal opening of the small intestine at the 
centre of the ilio-eecal valve, whose presence in the domesticated animals 
has, in consequence of a wrong appreciation of analogies, been denied; it is 
nothing more than the projection described as being made by the end of the 
small intestine. The second opening, placed about 14 or 2 inches above 
the preceding, and puckered around its margin, establishes a communication 
between this viscus and the colon. If this opening be compared with the 
capacity of the canal which begins from it, it will be remarked that it could 
scarcely be narrower, 


THE INTESTINES 409 


NG 
A, The duodenum as it passes — 
behind the great mesen- 
tric artery ; B, Free por- 
tion of the small intes- 
tine; C, Ileocacal portion ; 
D, Cecum; E, F, G, Loop 
formed by the large colon ; 
G, Pelvic flexure; F, F, 
Point where the colic loop 
is doubled to constitute 
the suprasternal and dia- 
phragmatic flexures, 


GENERAL VIEW OF THE HORSE’S INTESTINES; THE ANIMAL IS PLACED ON ITS 
BACK, AND THE INTESTINAL MASS SPREAD OUT. 


410 THE DIGESTIVE APPARATUS IN MAMMALTA, 


SrructorE.—The serous tunic does not call for any notice beyond that 
already given when speaking of the attachments proper to the cecum. The 
muscular tunte is formed of circular fibres, crossed externally by longitudinal 
bands, which maintain the organ in transverse folds. The mucous membrane 
is thicker than that of the small intestine, and is also distinguished from it 
by the absence of the Brunnerian and aggregated glands. It has, however, 
the solitary follicles and crypts of Lieberkiihn, as well as some few 
intestinal villi. The blood-vessels are the cecal arteries and veins. The 
lymphatics pass to the sublumbar receptacle; and the nerves are derived 
from the great mesenteric plexus. 

Funcrions.—The cecum serves as a reservoir for the enormous quantities 
of fluid ingested by herbivorous animals. The greater part of this fluid, in 
its rapid passage through the stomach and small intestine, escapes the 
absorbent action of the villi and accumulates in the cecum, where it may be 
said to wash the alimentary mass with which it comes in contact; thus 
dissolving the soluble and assimilable matters this mass may yet contain, 
and favouring their entrance into the circulation through the immense 
absorbing surface formed by the mucous membrane of the large intestine. 

It does not appear that the aliment is submitted in the cecum to any 
transformation, all the molecular changes of the digestive process, properly 
speaking, having been accomplished when the mass reached the interior of 
this viscus. 

B. Colon. 
The colon is divided into two portions, which differ from each other in 


Fig 206. 


THE COLON OF THE HORSE. 


1, First portion ascending to form the suprasternal flexure; 2, Second portion 
descending to form the pelvic flexure, 7; 3, 6, Longitudinal muscular bands; 
4, Point of the cecum, 5; 8, Duodenum ; 9, Small intestine. 


volume, and in the disposition they affect in the abdominal cavity. The 
first is the large or double colon ; the second, the small or floating colon. 
Tut Larcz or Dovsie Coon (Figs. 204, 205, 206).—This intestine 


: THE INTESTINES. 411 


begins at the cecum, and terminates by suddenly contracting at the origin 
of the small colon. 


Length—Capacity—It is from about 10 to 13 fect in length, and has a 
medium capacity equal to 18 gallons. 

Form—General disposition Removed from the abdominal cavity, and 
extended on a table or on the ground, this portion of the intestine appears as 
a voluminous canal, offering a succession of dilatations and contractions ; 
its surface being traversed by longitudinal bands, and sacculated and 
furrowed transversely for a great part of its extent, exactly like the cecum. 
It is also doubled in such a manner as to form a loop, whose two branches 
are of equal length and are held together by the peritoneum, which is 
carried from one to the other; so that the terminal extremity of the large 
colon returns towards the point of its origin. 

But this colic flexure, owing to its length, could not be contained in the 
abdomen ; and it is therefore doubled in its turn from above to below and 
from right to left (at the points r, F, in Fig. 20 ) . 
and forms curvatures which will be noticed pre- Fig. 207, 
sently, From this circumstance, it happens that 
the large colon, studied in the abdominal cavity, 
is divided into four portions lying beside each 
other in pairs ; so that a transverse section of that 
cavity, made in front of the base of the cecum, 
would give for this intestine the results indicated 
in the annexed figure. 

Course and Relations.—In following the course 
of the large colon from its origin to its termina- 
tion, in order to study its four portions in their 
normal relations, the following is observed: 

Commencing from the arch of the cecum, the colon is directed forwards, 
above the middle portion of that reservoir, which it follows to its point. 
Arrived at the posterior face of the diaphragm at its most declivitous part, 
it bends downwards and to the left, forming its first or suprasternal Slexure, 
because it rests on the xiphoid cartilage of the sternum (Fig. 204, 7). Here 
begins the second portion of the viscus, which is in immediate contact 
with the inferior abdominal wall, and extends backwards into the pelvic 
cavity, where it is inflected to the left to constitute the pelvic flexure. This 
curvature, the centre of the colic loop, responds to the rectum and bladder, 
as well as to the deferent canals, or the uterus and ovaries, according to 
the sex. It is succeeded by the third portion of the colon, which is carried 
forward, above, and to the left of the preceding. Bound to the second 
division by peritoneum and connective tissue, this new section reaches the 
phrenie centre, and is then doubled upwards and to the right. The flexure 
arising from this third duplicature is called the diaphragmatic, because of its 
relations with the musculo-aponeurotic membrane which partitions the great 
cavity of the trunk, or the gastro-hepatic curvature, in consequence of its lying 
equally against the liver and stomach (it is also designated the sigmoid flecure) 
(Fig. 904, &). To this flexure succeeds the fourth and last portion of the 
large colon, bound to the first portion, as the second is to the third. This 
extends, posteriorly, to the base of the cecum, where it terminates in a 
sudden contraction, and is continued by the small colon; it occupies the 
sublumbar region, and through the medium of a cellular layer is applied 
against the inferior face of the pancreas and the inner side of the cecal arch. 

Mode of attachment.—The large colon can be easily displaced in the 


PLAN OF THE COLON. 


412 THE DIGESTIVE APPARATUS IN MAMMALIA. 


abdominal cavity. It is nevertheless fixed: 1, By its origin, to the ceecum 
aud to the serous frenum which attaches it to that receptacle; 2, By the 
adherence of its terminal portion to the pancreas and the cross of the cecum; 
3, By the mesocolon. The latter ligament forms, in the concavity of the 
pelvic flexure a kind of racket, the handle of which is prolonged to a short 
distance between the two branches of the colic flexure. Beyond this, these two 
branches are directly placed side by side. 

External surface.—We have seen that the large colon does not offer the 
sume diameter everywhere, and that it is bosselated, plicated, and traversed 
by longitudinal bands; it is, however, important to study in detail this dis- 
position of its external surface in each of the regions already named. 

At its origin, the large colon is extremely narrow, and scarcely equal to 
the small intestine. But it soon dilates and assumes a considerable volume, 
which it preserves beyond the pelvic flexure. It then becomes progressively 
constricted to the middle of its third portion, where the diameter, reduced to 
its minimum, is yet much greater than at the origin of the first portion. 
Near the diaphragmatic flexure, the large colon is again gradually dilated, 
and finishes by acquiring, near its termination, the greatest volume it has 
yet exhibited. The muscular bands which maintain its transverse folds 
throughout the whole extent of its first dilated portion, are four in number. 
Three disappear in arriving towards the pelvic curvature, and the only one 
remaining is that which is placed in the concavity of that curvature. At 

- the second dilatation there are three bands, two of which are prolonged to the 
floating colon. The transverse folds formed by these flat bands are but 
faintly marked towards the pelvic curvature, and are altogether absent in 
the narrow portion succeeding it; it is only in the whole extent of the first 
dilatation that they are deepest and most numerous. 

Internal surface. —This is exactly like that of the cecum. ; 

Structure.—The serous membrane envelops the whole organ, except in 
those places where it comes in contact with itself or with other viscera. So 
it happens that the peritoneum, in passing from the sublumbar region to 
the last portion of the colon, does not cover the surface which adheres by 
cellular tissue to the inferior aspect of the pancreas and cecum; neither, in 
being carried from one branch of the colic flexure to the other, does it envelop 
their opposed sides, except at the pelvic flexure, where it forms the meso- 
colon. ; 

The muscular tunic does not differ in its arrangement from that of the 
cecum; neither does the mucous membrane. The arteries emanate from the 
great mesenteric ; they are the two colic arteries. The two satellite veins 
soon forma single trunk, which enters the vena porte. The lymphatics empty 
themselves into Pecquet’s reservoir. The nerves emerge from the great 
mesenteric plexus. 

Tue SMa, or Froatine Conon (Fig. 204).—This isa bosselated tube, 
which succeeds the large colon, and is terminated in the pelvic cavity by the 
rectum. 

Length— Form— Course— Relations —This tube is about 10 feet in length, 
and offers a disposition analogous to that of the small intestine, except that 
it is double the size of that viscus, is regularly bosselated on its surface, and 
is provided with two wide and thick longitudinal bands, one on the side of 
its great, the other on its small, flexure. Arising from the terminal 
extremity of the large colon, to the left of the cecum, where it responds to 
the termination of the duodenum, and where it receives the insertion of the 
great omentum, this intestine is lodged in the left flank, forming folds which 


THE INTESTINES. 415 


are mixed with the convolutions of the small intestine. It afterwards 
passes into the pelvic cavity, to be directly continued by the rectum, 

Mode of attachment.—F loating like the small intestine, the small colon is 
suspended by a serous layer, exactly similar to the mesentery proper, though 
wider, and named the colic mesentery. This mesentery is detached from the 
sublumbar region, not from around a central point, but from a line extending 
from the great mesenteric artery to the bottom of the pelvic cavity. It is 
narrower at its extremities than in its central portion. 

Interior.—The internal surface of the floating colon shows valvular folds, 
analogous to those of the cecum and large colon. It is in the intervals 
between these that the fecal matters are moulded into balls. 

Structure—The serous membrane is without special interest, and the 
muscular tunic is similar to that of the large colon. The mucous membrane 
is also the same. These membranes receive their blood by the small, and 
a branch of the great, mesenteric artery. A venous trunk, passing between 
the layers of peritoneum composing the mesentery, carries back the blood 
to the vena porte. The lymphatics are nearly as fine and as numerous as 
those of the small intestine; they enter the same confluent, the reservoir of 
Pecquet. 

Functions or THE Concn.—In this intestine is accomplished the ab- 
sorption of fluids, and of soluble alible matters. When the alimentary mass 
arrives in the small colon, deprived of its assimilable principles and 
charged with excretory substances thrown out on the surface of the intes- 
tinal tube, it loses its name and receives that of excrement or feces. These 
excrements, compressed by the peristaltic contractions of the muscular tunic, 
are divided into little rounded or oval masses, which find their way to the 
rectum, where they accumulate, and whence, in due course, they are expelled. 


C. Rectum. (Fig. 204.) 


The rectum extends, in a straight line, from the entrance to the pelvic 
cavity to the posterior opening of the digestive canal, or anus. It is no- 
thing more, properly speaking, than the extremity of the small colon, the 
limit which separates them being somewhat arbitrary ; it differs from that 
viscus, however, in having no ridges, and in its walls being thicker and more 
dilatable, so that it can be distended into an elongated pouch, and form a 
reservoir or receptacle for the excrementitious matters until they are expelled. 

Relations.—|t responds, superiorly, to the roof formed by the os sacrum ; 
inferiorly, to the bladder, the deferent canals, vesicula seminales, prostate 
gland, Cowper’s glands, or to the vagina and uterus; laterally, to the sides 
a tO af aleaten—sTbate ought to be considered as such: 1, Tho 
posterior extremity of the colic mesentery, representing the mesorectum ; 
9. An orbicular fold, constituted by the peritoneum in its circular reflection 
around this viscera at the extremity of the pelvic cavity; 3, The suspensory 
ligaments of the penis, which, joining under the rectum, form a ring eu- 
circling the posterior extremity ot the intestine (see Fig. 204, and the 
description of the penis) ; 4, A thick, triangular fasciculus, comprising two 
lateral parts, and composed of white muscular fibres ; this fasciculus, which 
is really a prolongation of the muscular tunic of the viscera, 1s detached from 
the rectum above the anus, and is attached to the inferior aspect of the 
coceygeal bones, between the inferior sacro-coccy geal muscles, where its 
outline can be seen beneath the skin when the tail is elevated. 


414 THE DIGESTIVE APPARATUS IN MAMMALIA. 


Sravcturr.—The serous membrane does not envelop the whole of the 
organ; that portion which traverses the bottom of the pelvic cavity being 
left uncovered by it. The muscular layer is very thick, and composed 
of large, longitudinal, and slightly spiral fasciculi, beneath which are 
annular fibres. ‘The mucous membrane, loosely attached to the muscular 
tunic, shows longitudinal and transverse ruge. The small mesenteric and the 
internal pudic artery (artery of the bulb) supply these membranes with blood. 
The nerves are derived from the pelvic or hypogastric plexus. 

Anus.—The anus, or posterior opening of the digestive tube, is situated 
at the posterior extremity of the rectum, under the base of the tail, where, 
in Solipeds, it can be seen forming a rounded prominence which diminishes 
with age. It is the border or margin of this orifice, which is corrugated 
like the mouth of a draw-purse, where the intestinal mucous membrane 
meets with, and is continued by, the external skin. 

In proceeding from within outwards, there are found the following 
elements entering into the structure of the anus: 1, The mucous membrane 
of the rectum; 2, The prolongation of the circular and longitudinal fibres 
of the muscular layer, forming what is named the internal sphincter ; 
3, A sphincter muscle, composed of red fibres, which receives the insertion of 
a retractor ; 4, The fine, hairless, and closely-attached skin, which covers 
the sphincter ; though destitute of hair, it is rich in sebaceous follicles. We 
will only notice the muscles. 

The SPHINCTER OF THE ANUS, (sphincter ani) is formed of circular fibres, 
some of which are fixed above, under the base of the tail, and are confounded, 
below, with the muscles of the perineal region. Comprised between the 
skin and the prolongation of the muscular layer of the rectum, this muscle 
is (during life) in a state of almost permanent contraction to keep the anal 
aperture closed, it being only relaxed during the expulsion of fecal matters. 

The RETRACTOR OF THE ANUS, Or ISCHIO-ANAL muscle (retractor ani), is a 
wide band attached to the internal surface of the ischiatic ligament (sacro- 
ischiatic), and even to the supercotyloid crest, by aponeurotic fibres. The 
fasciculi composing this band are all parallel to each other, while their 
posterior extremities are insinuated beneath the sphincter, and are confounded 
with its fibres. This arrangement of the retractor ani clearly indicates that 
it pulls the anus forwards, re-establishing it in its normal position after 
expulsion of the feces : an act which always results in carrying the posterior 
extremity of the rectum backwards. 

These two muscles are of a red colour, and belong to those of animal 
life. Their vessels are derived from the same sources as those of the rectum. 
‘he hemorrhoidal nerve supplies them both with filament 


DIFFERENTIAL CHARACTERS OF THE INTESTINES IN OTHER THAN SOLIPED ANIMALS. 


In the domesticated animals, the intestines vary as much in their dimensions, length, 
and diameter, as in their general disposition. 


1, The Intestines of Ruminants. (Fig. 208.) 


The small intestine of the Ox floats at the extremity of a broad mesenteric lamina, 
which is narrower in front than behind, plane throughout, except at its intestinal border, 
which is of considerable length; and is folded into a multitude of festoons, Twice the 
length of the small intestine of the Horse—averaging about 49 yards—it is about 
one-half its diameter. The duodenum, at first sustained by the omentum, which 
attaches the small curvature of the fourth compartment of the stomach to the posterior 
fissure of the liver, forms a particular loop, which is in contact with the sublumbar 
region before it goes to be suspended by the large mesentery, and to be continued by the 
couvotutions of the floating portion. The ileum terminates as in the Horse. The 


‘THE INTESTINES. 415 


Peyerian glands are less numerous on the internal surface of the small intestine than 
in Solipeds, though they are larger in size. In the Sheep and Goat, they are olten 
more than eight inches in length, and extend to Bauhin’s (ileo- cxcal) valve. 

The cxcum is nearly cylindrical in form, without bulges or longitudinal bands. The 
extremity of the cul-de-sac, rounded and globular, floats freely in the abdominal cavity, 
and is directed backwards. At its opposite extremity, the cecum is continued directly 
Be i colon, without forming a crook, after having received the insertion of the small 
intestine. 

In the Ox, in the vicinity of this insertion, there are traces of one of Peyer’s patches. 
In the Sheep and Goat, these patches are very numerous. 

The colon, sustained between the layers of the great mesentery, on the margin of 
which is suspended the small intestine, is rolled upon itself in such a way as to form 
a certain number of elliptical convolutions, by at first making several concentric spiral 
turns, which leave a certain interval between them for the reception of the excentric convo- 
lutions. The last spiral turn isa little distant from the others; in the smaller Ruminants, 


Fig. 208, 


GENERAL VIEW OF THE INTESTINES OF THE OX; RIGHT FACE. 
igi 1; i ti intestine; c, Termina- 
A. Origin of the duodenum ; B, Floating portion of the small in Hyon 
poi of the small intestine 3 p, Cecum; E, Its point directed backwards ; F, 
Flexure of the large colon at its termination; «G, H, Terminal portion of the 
intestine.—1, Insertion of the ductus choledochus; 2, Insertion of the pancreatic 
duct. 


i i 1 i i ich it follows to 
oie the insertion of the mesentery in the small intestine, whic 
ae ee in describing regular festoons. be dn Ser tes Bel of ag es 
i this convolution passes to the right, and is directed backwards, 
Be age. foveal a flexure, and turns back in company with the duodenal 
flexure "The colon then continues in a direct line to the rectum, attached to a pee 
mesenteric layer, which, by its position, resembles the large suspensory band of the 
. we . d 4 : 
Te pen Thee iatadtios is at first equal to he of the Hai 3 buts na barnes 
i intai uniform diameter, which scarcely exceeds that 
inte iialie anaes The muscular layer has the same arrangement as in the latter, 
altho aa js not covered in all its points by the serous tunic, in consequence ot ~ 
a nee f the colon between the two layers of the mesentery. In emaciated anima! he 
hows ee ay be remarked that the serous covering furnished by these layers tot e 
aie os oF the colon is more extensive than at first we might be led to think; on 
the lef 7 ide : the prominences of the spiral convolutions are found to stand in relief on 
ine te aie mesentery, and it is therefore more completely enveloped in the 
ine peri layer. . : . i 
cone sere +t will be seen that in the large intestine of Ruminants the 
ee = Se eced at that the division of the colon into a large or double, 
Le abi eay ker portion can scarcely be made; unless we regard as the large or 
ie ae 1 - the spiral folds contained between the layers of mesentery, and see the dioal 
ice a the posleriot extremity of the tube lying at first against the sublumbar wal 
in \ 


416 THE DIGESTIVE APPARATUS IN MAMMALIA. 


of the abdomen, and afterwards susp 


ended by the short mesenteric frenum which 


resembles the great colic mesentery of Solipeds. It is worthy of remark that the great 


Fig, 209. 


INTESTINES OF THE DOG. 

a, Stomach ; b, Duodenum; ¢, Jejunum; d, Ileum; e, Cecum; 
f, Ascending colon; g, Transverse colon; /, Origin of des- 
cending colon; 7, Great omentum; 4, Spleen; /, Mesentery ; 

Great mesenteric artery; 3, 

Artery of the duodenum; 4, Artery of the large intestine, 


m, Pancreas.—1, Aorta; 2, 


5, Small mesenteric artery. 


mesenteric artery goes to the 
first, and the small mesen- 
teric to the second portion, 
as in the Horse. ; 

Measured throughout its 
whole extent, from the cecal 
cul-de-sac to the anus, the 
large intestine of the Ox is 
from 33 to 394 feet. It is, 
therefore, longer than that 
of the Horse; but its capa- 
city is much less, for it does 
not exceed from 6} to 74 
gallons. 


2. Lhe Intestines of the Pig. 


The average length of 
the Pig's intestines is about 
72 feet, of which 56 go to 
the small, and 16 to the 
large intestine. 

In their general dispo- 
sition they bear some resem- 
plance to those of the Ox; 
though only the last portion 
of the colon ig included be- 
tween the Jayers of the me- 
sentery, it being, for the 
remainder of its extent, out- 
side that membrane, where 
it forms a distinct mass. 

Among the peculiarities 
of the small intestine, may 
be cited the presence of an 
immeuse Peyeriun gland, 
which occupies the latter 
portion of the canal, where 
it figures as a band measgur- 
ing from 5 to 64 feet in 
length. 

The cxcum shows, on its 
internal surface, some Peye- 
rian patches, it is bosselated, 
as in the Horse, and is fur- 
nished with three longitu- 
dinal bands. The colon has 
two of these muscular bands 
in a portion of its track, and 
even three towards the cz- 
cum; as well as sume trans- 
verse folds. It is doubled 
exactly as in the Ox 


3. The Intestines in Car- 
nivora. (Fig. 209.) 
The intestines of the 
Carnivora are remarkable 
for their shortness and small 
volume. In a Dog of ordi- 


nary size, they scarcely measure more than 14 fect in length, of which only 24 to 28 


inclies are for the large intestine. 


In the Cut, the latter is about one-half ths length, 


and the entire exteut of the viscus is equal to about 6 or 7 fvet. With regard to 


THE INTESTINES. 417 


capacity, M. Colin gives the following averaces: for the Dog’ ‘ ‘ 
that af the Gat, 1 mone g averages: for the Dog's small intestine, 1 quart; 
a4 trifle ie en Cae a intestine in the Dog, nearly 1 quart, aud in the 

The small intestine, suspended at the extremity of a mesenter simila: 

Solipeds, rests on the inferior abdominal wall. It a distinaniiehed’ by the heen y 
its parietes, the length and number of its villosities, which cover its inner surface, and 
which are even found accumulated on Peyer’s patches. These latter number about 20 
in the Dog, and 5 or 6 in the Cat. The exewm forms only a small, spirally-twisted 
appendix, lined by a plicated and very follicular mucous membrane particularly in the 
ce eae shows at ee ee of the cul-de-sac a true Peyer’s eland. 
fhe colon is scarcely larger than the small intestine, and is neithe 

furnished with longitudinal bands. In its short course, it is ed pei the 
same intestine in Man; and,as in him, it may be divided into the ascending (Fig. 209, f), 
transverse (g), and descending colon (h), which is continued directly with the rectum. . : 

Near the anus, this latter viscus presents on its sides two narrow apertures leading 
to two glandular pouches, which are filled with a brownish matter, that has a strong and 
fetid odour, and which is secreted by the glands covering the internal wall of these 
diverticuli. 

(Measurements of the intes- 
tines, always a subject of interest 
to comparative anatomists, have 
been frequently made by different 
authorities. Leyh gives the length 
of the Horses intestines as from 
10 to 12 times that of its body ; 
those of the Ow as from 20 to 22 
times; the Sheep and Goat from 
26 to 28 times; the Pig from 15 
to 17 times; the Dog from 4% to 
54 times; and the Cat from 4 to 
5 times. 

According to Hering, the entire 
length of the intestines of the 
Horse averages 100 Wurtemburg 
feet, 70 of which are for the small 
intestine, and 30 for the large. In 
the Ox they are 150 feet, 120 being 
for the small intestine, and 30 
for the large; in the Sheep they 
average 90 feet, 65 to 70 being 
allowed for the small intestine; 
those of the Goat measure 95, 
the small intestine being 70; in 
the Pig they are 90 feet, 72 of 
which are for the small intestine, 
and 18 for the large; large-sized 
Dogs averaged from 23 to 27 feet, 
20 to 22 of which were for the 
small intestine; small dogs had 
only 6 feet in many_instances. 
The Cat has from 4 to 5 feet.) 


THE HUMAN INTESTINES AND SUPERIOR MESENTERIC 


COMPARISON OF THE INTESTINES OF ARTERY. 

MAN WITH THOSE OF ANIMALS. 1, Descending portion of the duodenum ; 2, Transverse 

Not unfrequently the small portion; 3, Pancreas; 4, Jejunum; 5, Teum; 6, 
intestine of Man is divided into Caecum and appendix vermiformis; 7, Ascending 
duodenum and small intestine colon 3 8, Transverse colon ; 9: Descending colon ; 
proper. The duodenum is from 10, Superior mesenteric artery; 11, Colica media ; 
9 to 11 inches; is dilated at its 12, The branch that inosculates with the colica 
origin, and firmly attached to the sinistra; 13, Pancreatico-duodenalis inferior; 14, 
posterior face of the liver by a Colica dextra; 15, Ileo-colica; 16, 16, Vasa intes- 


peritoneal fold, and to the right — tinis tenuis. 


of the sublumbar region by con- ; 
nective tissue. It desutibes the arc of acirele, in the concavity of which is Icdged t] e 


right extremity of the pancreas, and not the cecum as in Solipeds. 


418 THE DIGESTIVE APPARATUS IN MAMMALIA. 


intestine proper is suspended by a mesentery somewhat similar to that of 
iste Ge Hea rates much—from 13 to 26 feet. Its internal face has a large 
number of transverse ruge, the valoule connivertes. It also shows from 20 to 25 
Peyer's patches, particularly in the ileo-cxecal portion. Its structure is like that already 
described. : 

In the large intestine is recognised the excum, colon, and rectum. . : 

‘he excum is a small reservoir placed in the right iliac fossa, a little obliquely 
downwards and to the left. It commences at the ileo-cecal valve, has an average length 
of about 23 inches, and terminates by a rounded extremity with a small hollow prolong- 
ation, averaging 3 inches in length, the cecal or vermiform appendix. The mucous 
membrane is like that of animals, and the muscular tunic is the same. ; ' 

The human colon is regularly sacculated, like the small colon of the Horse; it begins 
in the right iliac fossa, above the valvula Bauhini; it ascends to the lower face of the 
liver, passes abruptly across from right to left, and, arriving at the spleen, again changes 
its direction downwards to the iliac fossa ; it then again describes the iliac 8, to reach 
the mesial line, where it is continued by the rectum. From this course, the colon has 
been divided into three portions: the ascending colon, transverse colon, and descending 
colon. In the ascending and transverse colon are observed three series of sacculi, 
separated by three muscular longitudinal bands; the descending colon has only two. 

There is scarcely anything special to note in the rectum and anus, except that they, 
and especially the latter, are very rich in arteries and. varicose veins, and that the anus 
is separated from the rectum by small cavities open in front, and which are found in 
the Dog; these are the sénuses of Morgagni. 


GENERAL AND COMPARATIVE SURVEY OF THE ABDOMINAL OR ESSENTIAL PORTION OF THE 
DIGESTIVE TUBE. 


We have terminated the description of the anatomical characters which distinguish 
the essential portion of the alimentary canal in all the domesticated animals, and what 
gradations has this study revealed! Let us recapitulate and compare them, before 
showing the admirable harmony which pervades these diverse arrangements, and 
adapts them to the variations in general organisation, habits, and instincts. 

In the Carnivora which subsist on flesh (Dog and Cat), we have seen a very ample 
stomach, secreting a gastric fluid throughout the whole extent of its mucous membrane, 
and intestines, (relatively) extremely short. 

In the Omnivora, or mammalia which live on a mixed diet (Pig!, we have found a 
small portion of the internal surface of the stomach occupied by a mucous membrane 
unfitted to secrete gastric juice, and the intestines relatively of much more considerable 
capacity than in Carnivora. 

With the Herbivora, which derive their nourishment exclusively from the vegetable 
kingdom { Ruminants and Solipeds), the surface destined for the production of the gastric 
juice also singularly diminishes in extent, although the stomach in some of these animals 
is remarkable for its extraordinary development. But to compensate for this, the 
capacity of the intestinal canal assumes considerable proportions, and in the various 
species is in directly inverse relation to the area of the gastric surface. This surface 
being relatively more extensive in Ruminants than in Solipeds, all these animals ought 
to be classed in an inverse order with regard to the development of the intestinal 
surface. 

Finally, in considering as the internal surface of the stomach (a point of view quite 
rational) only those portions of the mucous membrane organised for the secretion of the 
gastric juice, we are led to recognise that this surface is in inverse proportion to that of 
the intestine; that it reaches its highest degree of development in Carnivorous animals ; 
and that it is reduced to the smallest dimensions in Solipeds, animals which, on the 
contrary, present a very great development of the intestinal surface. 

The nature of the aliment readily accounts for these remarkable differences. The 
Carnivora, living on substantial food, tuke it in very large quantity, because they are 
exposed to frequent fastings; it is, therefore, necessary that they should have a 
stomach large enough to contain the ingested substances, and to secrete the amount of 
gustric juice needed to transform them into assimilable materials. If these animals have 
a short and narrow intestine, it is because a small surface only is required to absorb the 
products of digestion. these being mixed with but a minimum quantity of non-nutritive 
substances, and readily come in contact with the absorbing membrane. 

With regard to the Herbivora, their food contains a trifling proportion of nutritive 
elements inclosed in an extremely abundant matrix, and being compelled to ingest great 


ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL, 419 


quantities at short intervals, the stomach, pro 
receptacle for the aliment, which passes rapid] 


than in the Horse ; the mass, more finely broken up, retains less of the assimilable and 
reparative matters, and these are more easily seized by the absorbing surface; and, as a 


necessary consequence, the intestinal tube, although longer than in Solipeds, is far from 
offering the same capacity, 


Analogous considerations explain the reason for the intermediate conformation of the 
digestive canal in Omnivorous animals, 

There is, then, an admirable correlation between the conformation of the digestive 
tube and the nature of the substances which form the base of the alimentation of animals: 
and this harmony is equally apparent when the stomach and intestines are compared with 
the other apparatus of the economy, and with the natural habits and instincts of creatures, 
So it is that a creature furnished with an ample stomach and narrow intestine, will have 
sharp teeth and claws to tear its prey, strength and agility to capture it, and will ulso 
possess sanguinary instincts, while another, with its gastric surfuce greatly diminished, 
will have intestines as developed in their length asin their capacity, and be distinguished 
by its peaceful habits, the absence of aggressive claws, and the crushing and grinding furm 
of the principal pieces of its dental apparatus, ete. 


ORGANS ANNEXED TO THE ABDOMINAL PORTION OF THE DIGESTIVE 
CANAL. 


These organs are three in number: two glands—the liver and pancreas, 
which pour into the small intestine two particular fluids, the bile and pan~ 
creatic juice ; and a glandiform organ, the spleen, remarkable for its nume- 
rous vascular connections with different organs of the digestive apparatus, 
and which for this reason deserves to be studied with it, although it is 
doubtful, if not improbable, that it has anything to do with digestion. 


Preparation.—These three organs can readily be studied after removing the intestinal 
tmass, as indicated at page 385. In order to examine the details of their organisation 
with more facility, it would be well to detach them altogether with the diaphragm and 
kidneys, and to lay out the whole ona table. (To study the relations of these three 
organs with those of the abdominal cavity, it is advisable to place the subject on its 
sternum after removing the intestines, and to detach the posterior part of the body at the 


loins.) 


The Liver. (Figs. 182, 211, 216.) 


Situation— Direction —This organ is situated in the abdominal cavity, to 

the right of the diaphragmatic region, and in an oblique direction down- 
the left. ; ; ; 

ve Wapiti. The weight of the healthy liver, in a middle-sized Horse, is 
Pe re coud mlb Surface.—Released from all its connections with the 
neighbouring organs, and viewed externally, it is seen to be flattened before 
ahd banice irregularly elongated in an elliptical form, thick in its centre, 
and thin towards its borders, which are notched in such a manner as to 
divide the organ into three principal lobes. This configuration permits it 


died in two faces and a circumference. 
@ The aes yaks convex, perfectly smooth, and channeled by a wide 


420 THE DIGESTIVE APPARATUS IN MAMMALIA. 


and deep notch formed for the passage of the posterior vena cava. | This 
fissure extends directly from behind to before, and consequently slightly 
crosses the general direction of the liver; near the point where the 
vena cava leaves the gland to traverse the diaphragm are seen the 
openings of the principal suprahepatic veins. The posterior face is equally 
smooth and convex, and has also a fissure by which the vena ports and 
the hepatic artery and nerves enter, and by which the biliary ducts emerge 
from the liver. This groove is slightly concave towards the left, and follows 
the direction of the liver in proceeding obliquely downwards, backwards, 
and to the left. 

The circumference may be divided into a superior or left, and an inferior 
or right border, united at both extremities by the ellipsis formed by the 
liver. The superior border presents, in proceeding from right to left: 1, The 
insertion of the ligament of the right lobe; 2, The origin of the fissure for 
the vena cava; 3, A notch for the oesophagus; 4, The insertion of the left 
ligament. The inferior border is sharp, and offers two deep notches, which 
divide the liver into three lobes: a superior or right, an inferior or left, 
and an intermediate one. The right lobe is usually of medium volume, 
and has above, on its posterior face, an appendix in the shape of a small 
secondary lobule of a triangular form, whose base responds to the com- 
mencement of the portal fissures: this is the /obus Spigelit. The left 
lobe is nearly always the largest. The middle lobe, the smallest of the 
three, is itself divided by secondary notches into several digitations or 
lobules. 

Relations —Viewing the organ in position, in order to study its general 
relations, it is found that the anterior face is applied against the diaphragm— 
a disposition which augments its convexity in diminishing that of its pos- 
terior face; and that the latter is in contiguity with the stomach, the 
duodenum, and the diaphragmatic curvature of the colon. 

The connections proper to each lobe are observed to be as follows: 
1, The middle lobe responds to the centre of the aponeurotic portion of 
the diaphragm; 2, The left lobe touches the left and inferior part of this 
aponeurosis, and is prolonged to the corresponding point of the fleshy 
peripheral band of that muscle; 3, The right lobe is in contact with the 
right and superior part of the muscle; its upper border touches the right 
kidney ; the pancreas rests against its base, on the posterior face. 

Mode of attachment.—The liver is suspended to the sublumbar wall of 
the abdomen by the large blood-vessels which enter its fissures, and it is 
also fixed to the posterior face of the diaphragm by four particular bands. 
One of these is carried from the anterior face of the liver to the phrenic 
centre, and appears intended to oppose total displacement of the organ ; the 
other three belong to each particular lobe. 

A. The Ligament of the anterior face of the liver (or coronary ligament) 
comprises two series of very short aponcurotic fibres, which, arising from 
the two borders of the vena cava fissure, go to be fixed to the posterior face 
of the phrenic centre. The peritoneum is folded over it on each side in 
passing from the diaphragm to the liver. The adherence of these fibres to 
the walls of the vena cava is extremely close; and the vena cava itself, 
being thus in a manner united to the tissue of the liver, it happens that 
the union of the anterior face of the viscus with the phrenic centre could 
not be more solidly established. 

B. The ligament of the left lobe is a wide peritoneal fold, between the 
two layers of which are some fasciculi of white fibrous tissue. It is detached 


ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 421 


from the aponeurotic centre, to the left of the csophageal orifice, and is 
inserted into the left part of the superior border of the liver. 

C. The ligament of the right lobe is a fold analogous to the preceding, 
but much shorter, and whose origin, placed very high and near the sub- 
lumbar parietes, is partly covered by theright kidney. It is inserted into the 


ity, or ventriculus of stomach ; 


1 wall. 


Fig. 211. 


THE ABDOMINAL CAVITY, WITH THE LIVER AND OTHER ORGANS. 
4, Right extremity; Left abdomina 


1, Right lobe of the liver ; 2, Middle lobe; 3, Right extrem 


superior border of the viscus, and sends a small layer to the lobus Spigelii ; 
most frequently, however. this lobule is sustained by a special peritoneal 
frenum, given off from the anterior border of the kidney. 

D. The ligament of the middle lobe (the longitudinal, broad. faleiform, or 
suspensory ligament) is a falciform and vertical serous layer, whose adherent 


30 


422 THE DIGESTIVE APPARATUS IN MAMMALIA. 


border is attached, almost in the median plane, to the posterior face of the 
diaphragm, and even to the inferior abdominal parietes. At its free border 
is a fibrous cord (the rownd ligament), formed by the obliteration of the 
foetal umbilical vein. By its upper part, it penetrates a secondary notch 
in the middle lobe, and is prolonged on the anterior face of this to the point 
where the vena cava traverses the diaphragm. 

Srructure.—As elements in its structure, the liver offers for study: 
1, A serous membrane ; 2, A fibrous capsule ; 3, The proper and fundamental 
tissue of the organ. 

1. Serovs Memprane.—This membrane is only an expansion of the peri- 
toneal bands or ligaments already described, and of which the two, on 
arriving at the organ, separate to become developed on its surfaces, and to 
completely cover it, except in the anterior and posterior fissures. 

2. Frerovs, or Guisson’s CarsuLte.—This, the proper envelope of the 
liver, is formed by a very fine fibrous membrane, closely adherent to 
the preceding layer on the one side, and to the tissue of the liver on the 
other. It penetrates the substance of that tissue in passing around the 
vessels lodged in the posterior fissure, and from its inner face it sends a 
multitude of lamellar partitions, which separate the hepatic granulations, 
and form a veritable framework in the interior of the organ. The 
presence of this capsule has been denied, but its existence is not to be 
doubted in all the domesticated animals; it is particularly well developed 
in Ruminants. 

3. Proper Tissuz or THE Liver.—The proper substance of the liver is 
distinguished by its bluish-brown or violet hue, the shades of which vary 
much according to the subjects. It is heavy, compact, and so friable that it 
is crushed by the most moderate pressure. It is composed of polyhedric 
granulations from 1—-20th to 1-10th of an inch in diameter, which are 
readily enough distinguished from one another through the peritoneum on 
the surface of the organ, particularly when the septa thrown in between 
them from Glisson’s capsule are hypertrophied from some slight chronic 
irritation. 

Sometimes the hepatic lobule is uniform in colour throughout; often it 
shows a red central point, with a yellow circle around it, and an interrupted 
red ring circumscribing this again, and which communicates with a similar 
circle belonging to the adjoining lobules, so as to compose a network at the 
surface of the gland ; at other times the lobules are yellow at the centre and 
red at the circumference. All these appearances, the study of which at one 
time was considered of much importance, are uncertain, and may vary in a 
thousand ways, in combining with one another ; so that they really demand 
but little attention, due as they are to the greater or less degree of plenitude 
of the different vessels entering the lobule. 

As the liver is composed of lobules placed beside each other, we will 
describe one; as when its structure is well known, we will be familiar with 
the organisation of the entire organ. 

In a hepatic lobule we find: 1, Hepatic (or biliary) cells ; 2, Biliary canal- 
tculi (or ducts); 8, Afferent vessels; 4, An efferent vessel ; 5, Lymphatics ; 
6, Connective tissue. 

Hepatic cells—These are polygonal or round, and much resemble 
squamous epithelium; their diameter varies from 1-500th to 1-200th of an 
inch. They are composed of a thin enveloping membrane and yellow- 
coloured contents. The latter comprise one or two nuclei with nucleoli, 
coloured granules, biliary matter, a small mass of a substance which has been 


ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 423 


studied by Bernard and Schiff, and named “ animal amidon;” and, lastly, 
adipose granules, whose volume and quantity vary with the condition of the 
animals, or the period of digestion at which the liver has been removed. 
The hepatic cells are situated in the network formed by the vessels of the 
lobule, and constitute its principal portion. 

Hepatic Ducts.—Destined to carry away the bile secreted in the interior 
of the hepatic lobule, the bili- 
ary ducts form around it a kind A Fig, 212. B 
of girdle that accompanies the 
interlobular branches of the 
vena porte. Within and with- 
out, this girdle sends off small 
prolongments: the first bring 
it into communication with 
the ducts of the neighbouring 
lobules; the second enter the 
substance of the lobule and 
are soon lost. 

The wall of the biliary 
ducts is a thin amorphous 
membrane, lined by polygonal 
cells, smaller than the hepatic 
cells. . Red A. Portion of a hepatic column, showing its compo- 

The origin of the biliary or nent secreting cells; B, Secreting cells detache ; 
hepatic ducts in the interior 6f a, In their normal state; 6, A cell more highly 
the lobules is still a vexed magnified, showing the nucleus and distinct oil- 

: . catglooy: Lt -Was particles ; c, In various stages of fatty degenera- 
Pilieved aa pete ree aac 

e > 

still believe, that the ducts terminate in pouches, at a short distance from 
the periphery of the lobule. But it has been remarked that an injection 
introduced by the ductus choledochus does not remain near the periphery 
of the lobule, but, on the contrary, penetrates to 
its centre by passing between the hepatic cells; and 
from this it is admitted that the hepatic ducts fur- 
nish a very fine network around each of the cellular 
elements of the liver (Fig. 213). Nevertheless, there 
are histologists who do not share in this opinion, 
who assert that these terminal ducts have no 
proper walls, and that the supposed networks they 
form is only a simple system of intercellular spaces 
distended by the injection. 

Afferent vessels—These are the branches of the 
portal vein and hepatic artery. The portal vein, BILIARY CAPILLARIES OF 
after reaching the interior of the liver, divides into ae oT nee 
gradually decreasing vessels, until it terminates by eee eer. 
forming the interlobular or subhepatic veins. These  yexr op THE BILIARY 
vessels surround the lobule, communicate with the DUCTS IN RELATION TO 
neighbouring interlobular veins, and give off a large © THE HEPATIC CELIS. 
number of twigs to the interior of the lobule, where 4, Ee nee ie eee 
‘they-anastomose, and. constitute the hepatic capillary a B eo “ pore : pal ; 
plexus. The ney bast ; sesgeted ser) ses pillary blood-vessels. 

i ix wit. e ramifications 0 : : 
ee eal) plexus. The principal branches of the latter are all 


Fig. 213. 


424 THE DIGESTIVE APPARATUS IN MAMMALIA. 


directed from the periphery towards the centre of the lobule, where they 

unite to form the afferent vessel. It results from this arrangement that the 

hepatic cells which fill the spaces 
between the vessels are placed in 
radiating series. 

Efferent series.—Situated in the 
centre of the lobules, this vessel 
receives all the ramifications of 
the capillary plexus, and is named 
the intralobular or central supra- 
hepatic vein. It is voluminous, 
and communicates with the other 
intralobular veins. (These. intra- 
lobular veins terminate in the 
larger trunks that run along the 
bases of the lobules, and are named 
the sublobular veins.) 

Lymphatics—In a hepatie lo- 
bule are found very fine lymphatic 
vessels that surround the branches 
of the hepatic plexus, where they 
HORIZONTAL SECTION or THREE suPERrictaL form the lymphatic vaginew, or 

LOBULES, SHOWING THE Two pRiIncipaL canals which contain the blood- 
SYSTEMS OF BLOOD-VESSKLS. vessels. 

a, u, Intralobular veins, terminating in the Connective tissue.—The intra- 
hepatic veins; 6, 6, Interlobular plexus, 1obylar connective tissue is scanty. 
formed by branches of the portal vein. 7 eee! 

the lobule being almost entirely 
composed of cells or capillaries; so that only some trabecule exist around 
the lymphatic sheaths. There is, however, a larger quantity in the inter- 
lobular spaces; and in some 
animals—especially the Pig 

—Glisson’s capsule sends 

somewhat thick lamelle of 

connective tissue between 
these lobules. 

Excrrtory APPARATUS.— 
This is very simple in Soli- 
peds, and is composed of a 
vessel named the ductus chole- 
dochus, resulting from the 
union of several trunks lodged 
in the posterior fissure of the 
K ANY \ y liver, and which come from the 

NNN SN] three lobes. Traced in the 
AVN AGN. Ld substance of the hepatic tissue, 
these branches divide into 

SECTION OF A SMALL PORTION OF THE LIVER OF A more and more attenuated 
sie a are HEPATIC OR INTRALOBULAR ramuscules that arise from 

the periphery of the lobules, 
and are continuous with the biliary ducts that envelop and penetrate these. 

Course.—At its exit from the liver, the ductus choledochus is placed 
between the layers of the gastro-hepatic omentum, and ascends to the wall of 
the duodenum, which it passes through at about six inches from the pylorus, 


Fig. 214. 


ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 425 


along with the principal pancreatic duct. The orifices of these two canals 
are surrounded by a circular mucous fold (ampulla of Vater), which is 
usually very prominent, and acts as a valve in preventing the entrance of 
alimentary substances into the apertures it encircles; this office it fills so 


well, that it will not even allow the air with which the duodenum is inflated 
to pass into the ducts. 


Fig. 216. 


EXCRETORY APPARATUS OF THE HORSE’S LIVER. 

1, Left lobe of the liver; 2, Middle lobe; 3, Right lobe; 4, Lobule of Spigel; 6, 
Posterior vena cava at its entrance into the liver; 7, Vena porte; 8, Ductus 
choledochus ; 9, Pancreatic duct; 10, Common entrance of these two ducts into 
the small intestine. 


There enter into the structure of the ductus choledochus: 1, A fibrous 
membrane, which some anatomists believe contains unstriped muscular 
fibres; 2, Cylindrical epithelium ; 83, Numerous racemose glands, opening on its 
inner surface by very small orifices. 

Vessets anp Nerves or THE Liver.—The blood-vessels are the hepatic 
artery, portal vein, and suprahepatic veins. 

The hepatic artery is a branch of the cceliac, and enters the gland by the 
posterior fissure, in company with the portal vein and ductus choledochus. 
In the liver it divides into very fine ramifications which join the intra- 
lobular plexus, anastomose on the surface of the biliary ducts, or expand 
either on the serous membrane, or in the walls of the portal vein. 

The portal vein is the functional vessel of the liver. It reaches that 
organ by the posterior fissure, and Glisson’s capsule accompanies its rami- 
fications as far as the hepatic lobules, where they form the plexus of sub- 
hepatic veins. : 

The suprahepatic (or sublobular) veins are so named because they gain 
the antero-superior face of the viscus to open into the posterior vena cava. 
They carry away the blood that has been brought by the portal vein and 
hepatic artery. Their origin is due to the union of the intralobular veins, 
which make a passage through the hepatic tissue with which their walls are 
immediately in contact, gradually join each other, and enter the posterior 
vena cava on its way through the anterior fissure of the liver. The number 
of trunks (hepatic) entering this vessel is considerable, but the majority are 
very small; the principal confluent is placed at the anterior extremity of 


the fissure. ‘ me . 
The lymphatics form a fine superficial plexus, easy to inject; with deeper 


426 THE DIGESTIVE APPARATUS IN MAMMALIA. 


networks placed around the vessels that penetrate by the posterior fissure. 
In the lobules they are disposed as described above. Joined to the 
lymphatics of the stomach, they constitute a single trunk that goes to the 
sublumbar receptacle. 

The nerves are more particularly derived from the solar plexus, although 
the pneumogastric and diaphragmatic also supply filaments to the liver. 
They interlace around the hepatic artery and portal vein; their mode of 
termination is unknown. 

Foncrions.—The most important considerations are attached to the study 
of the functions of the liver; but we cannot enter into them in detail with- 
out going beyond our subject. Besides, there is yet much to be learned 
respecting them. 

The liver is a biliary and glycogenetic gland. It secretes the bile at the 
expense of the blood of the portal vein, which comes from the intestinal 
tunics charged with the assimilable substances absorbed by the veins from 
the villi. This fluid is submitted to modifications in the interior of the 
liver, by which it is relieved of certain matters, while at the same time it 
furnishes the biliary secretion. 

The bile is, therefore, in this respect an excrementitious secretion ; though 
all its elements are not thrown off, some of them acting on the alimentary 
substances, and-others being absorbed. From the most recent researches, 
it would appear that it has a share in the purification of the blood, in’ 
digestion, and in calorification; in the latter especially, as its absorbed 
elements are very rich in carbon and hydrogen, bodies eminently adapted 
for the production of animal heat. 

The liver is also a glycogenetic gland, this function having been demon- 
strated to pertain to it by Bernard. The sugar formed in the liver finds 
its way into the blood, and leaves the organ by the suprahepatic veins. It 
is elaborated in the hepatic cells by the transformation of the substance 
known as “animal amidon,” which is brought into contact with a kind of 
diastase that exists with it in their interior. 

Lastly, it is also believed that the liver is a heematogenetic organ, the red 
globules being formed in its mass at the expense of the fibrine of the blood 
that passes through it. 

It will thus be seen that the liver furnishes two very different products— 
bile and sugar. The knowledge of this fact, combined with the internal 
arrangement of the organ, has led some anatomists to consider the organ as 
two glands reciprocally contained within each other. But this hypothesis 
loses its value if it be admitted that the hepatic ducts pass between the cells 
to the centre of the lobule, and that in this portion they are destitute of 
epithelium. It is therefore probable that the sugar and bile are produced 
in the large hepatic cells, and that the first passes into the veins, while the 
second is poured into the biliary ducts. 

In Solipeds, the secretion of bile, though most active during the digestive 
period, yet goes on in a continuous manner. 

(Certain deductions of a pathological kind are based upon the foregoing 
anatomical facts, and have an important bearing with regard to comparative 
pathology. They have been pointed out by Wilson, and are as follows :— 
Hach lobule is a perfect gland; its structure and colour are uniform, and 
it has the same degree of vascularity throughout. It is the seat of a double 
venous circulation ; the vessels of the one (hepatic) being situated in the 
centre of the lobule, and those of the other (portal) in the circumference. 
Now the colour of the lobule, as of the entire liver, depends chiefly on the 


ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 427 


proportion of blood contained within these two sets of vessels; and so long 
as the circulation is natural, the colour will be uniform. But the instant 
that any cause is developed which shall interfere with the free circula- 
oe either, there will be an immediate diversity in the colour of the 
obule. 

Thus, if there be any impediment to the free circulation of the venous 
blood through the heart or lungs, the circulation in the hepatic veins will 
be retarded, and the sublobular (or supralobular) and intralobular veins 
will become congested, giving rise to a more or less extensive redness in the 
centre of each of the lobules; while the marginal or non-congested portion 
presents a distinct border of a yellowish white, yellow, or green colour, 
according to the quantity or quality of the bile it may contain. “This is 
‘ passive congestion’ of the liver, the usual and natural state of the organ 
after death ;” and, as it commences with the hepatic vein, it may be called 
the first stage of hepatic venous congestion. 

But if the causes which produced this state of congestion continue, or be 
from the beginning of a more active kind, the congestion will extend through 
the lobular venous plexuses “ into those branches of the portal vein situatud 
in the interlobular fissures, but not to those in the spaces, which being larger, 
and giving origin to those in the fissures, are the last to be congested.” In 
this second stage the liver has a mottled appearance, the nun-congested 
substance is arranged in isolated, circular, and ramose patches, in the 
centres of which the spaces and parts of the fissure are seen. This is an 
extended degree of hepatic venous congestion ; it is “active congestion” of the 
liver, and very commonly attends disease of the heart and lungs. 

These are instances of partial congestion ; but there is sometimes general 
congestion of the organ. “In general congestion the whole liver is of a red 
colour, but the central portions of the lobules are usually of a deeper hue 
than the marginal portions.”) 

DeveLtopment.—The liver of the foetus is remarkable for its enormous 
development. Its function commences early, for at birth the intestines are 
filled with meconium, a product of the biliary secretion. A more detailed 
description will be given when the general development of the foetus comes 
to be studied. 


2. The Pancreas. 


This organ has the greatest resemblance to the salivary glands in its 
structure and physical properties; and for this reason it has been named the 
abdominal salivary gland. 

Sétuation.—It is situated in the sublumbar region, across the aorta and 
posterior vena cava, in front of the kidneys, and behind the liver and 
stomach. Its weight is seventeen ounces. 

Form and Relations—The pancreas is rather irregular and variable in 
form, according to the kind of animal. Flattened from above to below, 
traversed obliquely from its inferior to its superior face by an opening for 
the passage of the portal vein, and which is named the pancreatic ring, this 
gland is sometimes triangular, sometimes oblong, and curved on itself; it is 
under the latter form that we will notice it. ; 

Its faces present the lobulated aspect of salivary glands. The superior 
adheres by cellular tissue to the aorta, posterior vena cava, cceliac trunk, 
solar plexus, splenic vessels, and the right kidney and. supra-renal capsule ; 
it is covered by the peritoneum for a certain portion of its extent. The 
inferior responds to the base of the caecum and the fourth portion of the 


428 THE DIGESTIVE APPARATUS IN MAMMALIA. 


colon, through the medium of # thick layer of cellular tissue. The anterior 
border, concave and undulating, is in contact with the duodenum and the left 
extremity of the stomach. The posterior is very convex, especially to the 
right, and near its middle presents a notch for the reception of the portal 
vein before its entrance into the ring. The right extremity (or head), the 
thinnest, adheres to the duodenum, and shows the excretory ducts of the 
gland. The left is carried towards the base of the spleen, in passing 
between the left extremity of the stomach and the kidney of the same 
side. 

Structure.—It resembles the salivary glands, except in its epithelium. 
This, instead of being simple polygonal cells lining the thin, structureless 
membrane of the ultimate follicles, is very granular, and fills these cavities. 
The gland receives its blood by the hepatic and great mesenteric arteries ; 
the nerves come from the solar plexus. 

Excretory apparatus —The pancreas has two excretory ducts : a principal, 
described by Wirsung, whose name it bears, and an accessory. The duct of 
Wirsung, lodged in the substance of the gland, but nearer the superior than 
the inferior face, at first comprises two or three thick branches, which soon 
unite to form a single trunk that emerges from the pancreas by the left 
extremity of the organ. Larger than the ductus choledochus, it opens, as 
already stated, at the same part of the duodenal surface. The accessory 
duct (ductus pancreaticus minor) is much smaller; it leaves the principal 
trunk, receives some branches in its passage, and opens alone into the small 
intestine, directly opposite the duct of Wirsung. 

The ductus choledochus and the duct of Wirsung do not pass directly 
through the wall of the intestine, but obliquely, like the entrance of the 
ureters into the bladder. They open in the middle of a circular valve—the 
ampulla of Vater. This ampulla is limited by a thick primary mucous 
fold, and within this is a second, thinner, beneath which the ductus chole- 
dochus opens; at the bottom of the space circumscribed by this second fold, 
beneath a free mucous lip, is seen the duct of Wirsung. 

Foncrions.—From the researches of Bernard, it appears established that 
the fluid secreted by the pancreas emulsities fatty matters and renders them 
absorbable. 


3. The Spleen. 


The spleen differs from glands not only in the absence of an excretory 
duct, but also in the other details of its organisation. It has been consi- 
dered as a vascular gland, whose uses are not yet determined in a precise 
manner, 

Situation.—It is situated in the diaphragmatic region, close to the left 
hypochondriac, and appears as if suspended in the sublumbar region, as well 
as at the great curvature of the stomach. 

Form —Direction— Relations—The spleen is falciform, and directed 
obliquely downwards and backwards. It has two faces, two borders, and a 
point. 

The external face is in relation with the muscular portion of the 
diaphragm, and is moulded to it. The internal, slightly concave, touches 
the large colon; it has sometimes a small lobule, or offers traces of lobula- 
tion. The posterior border is convex, thin and sharp. The anterior, thicker, 
concave, and bevelled at the expense of the internal face, is channeled by a 
slight longitudinal fissure which lodges the splenic vessels and nerves ; it 


ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 429 


receives the insertion of the great mesentery, by which it is held to the 
greater curvature of the stomach. The base, or superior extremity, is thick 
and wide, and responds to the left kidney and the corresponding extremity 
of the pancreas ; it shows the insertion of the suspensory ligament. The 
point, or inferior extremity, is smooth and thin. 

Weight—The average weight is 32 ounces; but it is sometimes of 
enormous dimensions—as much as three or four times its normal volume. 

Mode of attachment—The spleen is a floating organ, whose displacements 
are limited by a suspensory ligament, and the great (or gastro-splenic) 
omentum. The first is a peritoneal fold which proceeds from the anterior 
border of the left kidney and the sublumbar wall, and is strengthened by 
the elastic fibrous tissue comprised between its two layers. It is fixed to 
the base of the spleen, and is confounded, inwardly, with the great omentum. 
The latter is already known as proceeding to the colon, and in its passage 
becoming attached to the splenic fissure, whence it extends over the sur- 
face of the organ to form its serous covering. 

Srructurr.—The tissue of the spleen has a violet-blue colour, sometimes 
approaching to a red hue; it is elastic, tenacious, and soft, yields to the 
pressure of the finger, and retains the imprint. Enveloped externally by the 
peritoneum, its substance includes a fibrous framework, splenic pulp, Mal- 
pighian corpuscles, vessels, and nerves. 

Serous membrane. —This is developed over the whole surface of the organ, 
except in the fissure of the anterior border. Its internal face adheres most 
intimately to the proper tunic of the spleen. It is only an expansion of the 
serous bands which limit the movements of the viscus. 

Fibrous framework.— Under the peritoneal membrane is a thick, resisting, 
fibrous tunic, roughened and granular on its exterior, and sending from its 
deep face into the interior of the mass a multitude of prolongations called 
trabeculce, which cross in all directions, forming a cellular network whose 
numerous narrow meshes contain the other elements of the organ. In 
washing a morsel of spleen in a jet of water, the latter are removed, and the 
outlines of this fibrous structure are fully exposed. Ifa stream of water is 
passed through the splenic artery, the same result will be arrived at. 
Kélliker has found in the proper tunic of the spleen, and in its trabecule, 
a particular contractile tissue, the muscular cell-fibres, mixed with fasciculi 
of elastic or inelastic fibrous tissue. (The proper coat, the sheaths of the 
vessels, and the trabecule consist of a dense mesh of white and yellow 
elastic Abrous tissues, the latter considerably predominating. It is owing to 
the presence of this tissue that the spleen possesses a considerable amount of 
elasticity, admirably adapted for the very great variations in size that it 
presents under certain circumstances. In some of the mammalia, in 
addition to the usual constituents of this tunic, are found numerous pale, 
flattened, spindle-shaped nucleated fibres, like unstriped muscular fibre. 
It is probably owing to this structure, that the spleen possesses, when acted 
upon by the galvanic current, faint traces of contractility.) 

Splenic pulp.—This name 1s given to a reddish pultaceous material, 
which partly occupies the aveolar framework formed by the intersections 
of the trabecule. It is sustained by a very delicate reticulum of connective 
tissue, and is composed of numerous elements, such as pigment granules, 
free nuclei, large cells with several nuclei, lymphoid elements, and blood- 
globules in a state of decomposition or transformation. These globules 
are free or enveloped in an albuminoid membrane. (The proper substance 
of the spleen consists of coloured and colourless elements. The coloured 


430 THE DIGESTIVE APPARATUS IN MAMMALIA, 


are composed of red blood-globules and coloured corpuscles, either free or 
included in cells. Sometimes unchanged blood-dises are seen included in 
a cell; but more frequently the 
included blood-dises are altered 
ae both in form and colour. Besides 
/ le these, numerous deep-red, or red- 
( dish-yellow, or black corpuscles 
and crystals, either single or aggre- 
gated im masses, are seen diffused 
throughout the pulp substance ; 
these, in chemical composition, 
are closely allied to the hematine 
of the blood. The colourless ele- 
ments consist of granular matter; 
nuclei, about the size of the red 
blood-discs, homogeneous or gra- 
nular in structure; and nucleated 
vesicles in small numbers. These 
elements form a large proportion of 
OS the entire bulk of the spleen in well- 
\ nourished animals; whilst they 
hs diminish in number; and occasion- 
\ ally are not found at all, in starved 
animals. The application of chemi- 

BRANCH OF SPLENIC ARTERY WITH ITS RAMI- 


cal tests shows that they are essen- 

an STUDDED WITH MALPIGHIAN COR- tially a proteine compound. ) 

‘LES. oye 

Malpighian corpuscles.—These 
are contained, like the pulp, in the meshes of the fibrous framework, and are 
enveloped by this pulp. Scattered along the track of the small arteries, 
these corpuscles are visible to the naked eye, and appear as whitish closed. 
sacs, cells, and nuclei floating in a plasma. The 
Malpighian corpuscles are constituted by the adven- 
titious tunic of the arteries, in which lymphoid ele- 
ments are accumulated at certain points. They 
are therefore allied to the closed follicles of the 
intestines. (These splenic or Malpighian corpuscles, 
are round, whitish, semi-opaque bodies, glutinous 
in consistence, and disseminated throughout the sub- 
stance of the organ. They are more distinct in 
early than in adult life or old age, and vary con- 
A SINGLE spLentc corrus. Siderably in size and number, From the manner 
CLE, FROM THE spLuEN in which they are appended to the sheaths of the 
OF THE Ox. smaller arteries and their branches, they resemble 
1, External tunic, or mem- the buds of the moss-rose. Each consists of a mem- 
brana propria, 2, Gran- branous capsule, composed of fine pale fibres inter- 
ular contents; 3, Part lai * 1h Artest The blaod« ty manne 
of a small artery; 4, lacing in all directions. e blood-vessels ramify 
Its sheath, derived from ing on the surface of the corpuscles, are the larger 
the external tumc ofthe ramifications of the arteries to which the sacculus 
inde eeu the is connected, and also of a delicate capillary plexus, 
Be Ae “yen similar to that surrounding the vesicles of other 
glands. These vesicles have also a close relation 
with the veins, and the vessels begin on the surface of each vesicle through- 
out the whole of its circumference, forming a dense venous mesh in which 


Fig. 217. 


Fig, 218. 


ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE GANAL, 481 


each of these bodies is inclosed. It is probable that, from the blood con- 
tained in the capillary network, the material is separated which is occa- 
sionally stored up in their cavity; the veins being so placed as to carry 
off, under certain conditions, those contents that are again to be dis- 
charged into the circulation. Each capsule contains a soft, white, semi-fluid 
substance, consisting of granular matter, nuclei similar to those found in the 
pulp, and a few nucleated cells, the composition of which is apparently 
albuminous. These bodies are very large, after the early periods of diges- 
tion, in well-fed animals, and especially those fed upon albuminous diet. 
In starved animals, they disappear altogether.) 

Arteries.—These emanate from the splenic artery at different elevations, 
and plunge into the tissue of the spleen, preserving their reciprocal 
independence. Their terminal ramifications do not open, as has been 
said, into venous sinuses, but into minute tufts of capillaries, which traverse 
the splenic pulp, to be continued by the venous network. 

Veins.—All the venous branches of the spleen open into the splenic 
vein, and are lodged with the corresponding artery in the fissure of the 
organ. Traced from their commmencement, they are seen to gradually lose 
their constituent membranes, and to open into sinuses which are only lined 
by the epithelium of the vessels. It is in these sinuses that the network 
of venous capillaries which succeed the arterial capillaries, originates. 

Lymphatic vessels—These are found on the external surface of the 
organ, and along the track of the blood-vessels. (‘They invest these with 
a distinct sheath, between which and the parietes of the vessels numerous 
lymph corpuscles may be found.) 

Nerves.—They are derived from the solar plexus, and enveloping the 
splenic artery, with it enter the spleen. (They appear to be very large, 
but this appearance is due to the great proportion of ordinary fibrous tissue 
investing them. 

From what has been said above respecting the arrangement of the 
splenic arteries and veins, it will be perceived that the areole formed by 
the trabecule of the fibrous framework contain the pulp, and are not in 
direct communication with the arterial capillaries. Such an organisation 
belongs to erectile tissues. The arteries communicate with the veins proper 
by venous canals channeled in the splenic pulp, and are lined only by ellip- 
tical cells. These venous canals are extremely dilatable, especially in 
the Horse. When the splenic vein is inflated, their walls separate and 
press back the pulp, they become considerably enlarged, and distend 
the cells of the fibrous. structure, but the air does not reach the interior 
of these cells. 

Fonctions.—Nothing precise is known regarding the functions of the 
spleen ; though they must be of very secondary importance, because animals 
in which the organ has been extirpated, and which have recovered from the 
consequences of the operation, have continued to live in apparent good 
health. Numerous hypotheses have been formed on this subject; two of 
which, founded on the study of the anatomical peculiarities of the spleen 
tissue, and on exact physiological observations, are as follows: 1, The spleen 
is a diverticulum for the portal vein ; 2, The red globules are destroyed in the 
spleen. 
si With regard to the first hypothesis, it is evident that, owing to the 
presence of the venous sinuses already mentioned, and their great dilata- 
bility, as well as to the elasticity and contractility of the spleen tissue, the 
organ is favourably constructed to act asa blood reservoir. M. Goubaux, 


432 THE DIGESTIVE APPARATUS IN MAMMALIA. 


on the other hand, has demonstrated that there is always an augmentation 
in the spleen’s volume when an animal has ingested large quantities of 
water, the consecutive absorption of which determines a certain tension in 


the portal venous system. ; 
The second opinion, emitted by Kélliker, is founded on the existence 


in the splenic pulp of blood-globules in a state of decomposition, and 
in the analyses made by J. Beclard of the blood in the splenic vein, 
which have proved that there is a notable diminution in the proportion of 
globules. 

It is to be remarked that, in the researches undertaken to discover 
the functions of the spleen, account has not been taken of the connections 
existing between this organ and the great omentum in the majority of 
mammals, and which testify that the spleen is only, properly speaking, 
a vascular appendage placed on the track of this omentum. But the uses 
of this vast peritoneal fold are themselves little understood. Might they 
not be included with those which are presumed to belong to its appended 
organ ? 


DIFFERENTIAL CHARACTERS IN THE ANNEXED ORGANS IN THE ABDOMINAL PORTION OF 
THE DIGESTIVE CANAL IN OTHER THAN SOLIPED ANIMALS. 


The important differences these organs offer in the domesticated mammals belong 
more particularly to the liver. 

1. Liver.—In the domesticated mammals other than Solipeds, the liver exhibits vari- 
ations in form, volume, and position, which have no influence on its organisation: so that 
the study of these possesses but a mediocre attraction. This is not so, however, with re- 
gard to the excretory apparatus, the arrangement of which is complicated, and becomes 
very interesting. The biliary duct, in fact, on leaving the fissure of the portal vein, and 
before reaching the intestine, gives rise to a particular conduit which is detached at an 
acute angle, and which, after a course of variable length, according to the size of the 
animal, becomes dilated into a vast sac, the so-called gall-bladder. 

In all treatises on anatomy, the special conduit is designated the cystic duct, that 
portion which precedes its origin being named the hepatic duct ; while the appellation of 
ductus communis choledochus is reserved for the section which goes to the intestine. But 
these distinctions are vicious, and we limit ourselves to the recognition of: (a) A ductus 
choledochus exactly like that of Solipeds, and like it extending from the posterior 
fissure, where it originates by the union of several branches, to the duodenum; and (b) a 
cystic duct, which branches suddenly into the choledic duct, and terminates in the gall- 
bladder. 

a. The gall-bladder is a reservoir with membranous walls, in which the bile accumu- 
lates during the intervals of digestion. This sac, lodged wholly, or in part, in a fossa on 
the posterior face of the liver, is oval or pyriform, and presents a fundus and neck. Its 
parietes comprise three tunics: an external, of peritoneum: a middle, formed of dartoid 
tissue ; and an internal, or mucous, continuous with that of the various biliary ducts. 

b. The cystic duct extends in a straight line from the neck of the gall-bladder to the 
choledic duct. It adheres intimately to the tissue of the liver, and does not exhibit, in- 
ternally, the spiral valves which have been described in Man. In opening it longitudi- 
nally, there are discovered, at least in Ruminants and the Carnivora, very small orifices 
which pierce the wall adherent to the tissue of the liver: these are the openings of 
several minute but particular biliary canals, named the hepatico-cystic ducts. 

¢. The ductus communis choledochus comports itself exactly as in Solipeds. It is 
much wider than the cystic duct, and opens sometimes alone, sometimes with the pan- 
creatic canal, into the duodenum in a manner which, up to a certain point, reminds one 
of the mode of termination of the ureters. Instead of passing perpendicularly across the 
intestinal parictes, it first pierces the muscular layer, follows for a short distance between 
it and the mucous membrane, and then opens on the internal face of the latter by an 
orifice which is encircled by a valvular fold, as in the Horse. 

Such is the excretory apparatus belonging to the liver in animals provided with 
a gall-bladder. In these animals the biliary secretion is certainly continuous, as 
in the Horse; but in the intervals of digestion the bile, instead of flowing directly on 
to the intestinal surface, passes into the gall-bladder by the cystic duct, and there 


ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 433 


accumulates. When digestion commences again, this reserve of bile is thrown into the 
ductus choledochus by the contraction of the muscular fibres of the cyst, and by the 
pressure of the abdominal viscera; .it meets that which comes directly from the liver, 
and with it is carried to the duodenum. 

We will now glance at the particular arrangement of this viscus in each species. 

In the Oz, the liver is entirely confined to the right diaphragmatic region. It is 
thick, voluminous, and scarcely notched at its periphery ; so that it is difficult, if not 
impossible, to distinguish three lobes in it, the lobus Spigelii alone being detached from 
the mass of the organ. The gall-bladder, fixed towards the superior extremity, is nearly 
always floating; near its neck it receives the insertion of several large conduits, which 
come directly from the upper part of the liver. The ductus choleduchus opens alone at 


Fig, 219. 


SI 


LIVER OF THE DOG, WITH ITS EXCRETORY APPARATUS. 

p, Duodenum and the intestinal mass; P, Pancreas; r, Spleen; ¢, Stomach ; fh 
: Rectum; R, Right kidney; B, Gall-bladder ; ch, Cystic duct; FF, Liver; F’, Lobe 
of the liver, prepared to show the distribution of the vena porte and hepatic 
vein; vp, Vena porte; vi, Hepatic vein; d, Diaphragm; vc, Vena cava- 
c, Heart. 


i om the pylorus; M. Colin has found it to be 243 inches in one cow, 

Se cosh Ta the Sheep and Goat, the form and position of the liver 
differs but little from that of the Ox. The ductus choledochus, however, unites with 
that of the pancreas, and terminates at 12 to 16 inches from the pylorus. 

In the Pig, the liver has three well-marked lobes; the middle carries the gall- 
bladder. The ductus choledochus opens alone at 1 or 14 inches only from the pylorus. 

In the Dog and Cat, the liver is very voluminous, is deeply notched, and is divided 
into five principal lobes. The middle lobe has the gall-bladder attached to it, and gives 
it complete lodgment in a fossa. 


434 THE DIGESTIVE APPARATUS IN MAMMALIA. 


he ductus choledochus, joined to a small branch from the paucreatic duct, 
re io ie at a variable distance from the pylorus, depending upon the size of 
the animal, but usually between 13 and 43 inches. In the portion comprised between 
the intestine and the origin of the cystic duct, it receives several biliary canals ~ some- 
what considerable diameter. In the Cat, the ductus choledochus is most frequently 
inserted from about 1 to 13 ae from the a orifice ; it opens immediately along- 
i i ct when it does not join it. 

ae roe er Ox, the paneread is not placed across the sublumbar parietes, 
but is comprised between the layers of the mesentery, tothe right of the great mesenteric 
artery. The excretory duct is single, and opens into the small intestine at from 14 to 16 
inches beyond the ductus choledochus. 

In the Sheep and ee soe is the same general arrangement, but the excretory 

ith that of the liver. 

Satie Pe, this duct is inserted at from 4 to 6 inches behind the ductus choledochus, 

The pancreas of the Dog is extremely elongated, and included between the layers of 
the mesentery which sustain the duodenum. It is curved at its anterior extremity, 
behind the stomach, to one side of the median line. Its excretory duct, usually single, 
pierces the intestinal membranes 2 inches beyond the hepatic duct (Fig. 219, m). Except 
in the mode of insertion of the exeretory duct, which has been described in noticing the 
ductus choledoclius, the pancreas of the Cat comports itself exactly like that of the Dog. 

3. Spleen.—In Ruminants, the spleen is not supported by the great omentum, but 
adheres to the left side of the rumen and diaphragm. It is not falciform, and its breadth 
is the same throughout its extent. In the Carnivora, it is suspended to the great 
omentum at a certain distance from the left sac of the stomach. It is irregularly falci- 
form, its point is less acute than in Solipeds, and is directed upwards. 


COMPARISON BETWEEN THE ANNEXED ORGANS OF THE ABDOMINAL PORTION OF THE 
DIGESTIVE CANAL IN MAN AND THOSE OF ANIMALS. 


1. Liver.—Like that of Ruminants, the human liver is situated in the right excava- 
tion of the lower face of the diaphragm. Its direction is nearly horizontal; its shape is 
oval, and its average weight from forty-nine to fifty-three ounces. The posterior border 
is thick and round; the anterior border and extremities thin and sharp. The upper 
face, which in expiration ascends to the fourth rib, is divided into two portions or lobes— 
right and lett, by the falciform 
ligament; it is smooth and con- 
vex. The inferior face has three 
furrows, or fosse: two longitu- 
dinal, united by a transverse, re- 
sembling altogether the letter H. 
The transverse furrow represents 
that on the posterior aspect of 
the liver of animals, and its des- 
tination is the same. The right 
longitudinal furrow lodges the 
obliterated umbilical vein; the 
left, well marked before and be- 
hind, lodges the  gall-bladder 
in front, and the inferior vena 
cava behind. This face has four 
lobes, the right and left, and two 
middle lobes. In front of the 
transverse furrow is the lobus 
quadratus, and behind the same 
1, Right lobe; 2, Left lobe; 3, Lobus quadratus; 4, fissure is the lobus Spigelii. 

Lobus Spigelii: 5, Lobus caudatus; 6, Longitudinal On the lower face of the right 
fossa; 7, Pons hepatis; 8, Fossa of ductus venosus; lobe are three depressions: an 
9, Inferior vena cava; 10, Gall-bladder; 11, Trans- anterior or impressio colica; a 
verse fossa; 12, Vena cava; 13, Depression corres- deep middle one, impressio vesice ; 
ponding to the curve of the colon; 14, Double and a small posterior one, which 
depression produced by right kidney and supra-renal receives the supra-renal capsules, 
capsule. impressio renalis. 

2, Panereas.—This organ is 
very elongated transversely, like that of the Dog and Cat. It is closely applied against 
the lumbar vertebrae, as in the Horse, but its anterior face is much more enveloped by 
the peritoneum Its right extremity rests on tlie duodenum, while the left corresponds to 


UNDER SURFACE OF THE HUMAN LIVER. 


a 


a 


THE DIGESTIVE APPARATUS IN BIRDS. 435 


the spleen and left kidney. Its texture is consistent, and of a greyish-white colour. The 
duct of Wirsung terminates along with the ductus choledochus in the ampulla of Vater. 
3. Spleen.—This is not fulciform, but quadrangular; its inferior extremity is larger 
than the superior. It is attached to the stomach by the great omentum, and its inner 
fuce is divided into two portions by a salient ridge; a little in front of this is a fissure 
the hilum lients, by which vessels enter it. , 


CHAPTER ITI. 
THE DIGESTIVE APPARATUS OF BIRDS. 


ConsTrucTED on the same plan as that of Mammals, the digestive apparatus of Birds 
nevertheless offers in its arrangement several important peculiarities, which will be 
hurriedly noticed in reviewing, from the mouth to the anus, its different sections, 

Mouth.—The essentially distinctive character of the mouth of birds consists in the 
absence of lips and teeth, these organs being replaced by a horny production fixed 
to each jaw, and forming the salient part termed the beak. In the Gallinaex, the beak 
is short, pointed, thick, and strong, the upper mandible being curved over the lower. In 
Palmipeds, it is longer, weaker, flattened above and below, widened at its free extremity, 
and furnished within the mouth, on the borders of each mandible, with a series of thin 
and sharp transverse laminz to cut the herbage. 

The muscular appendage, or tongue, lodged in the buccal cavity, is suspended to a 
remarkably mobile hyoidean apparatus. Covered by a horny epithelium, and provided at 
its base with several papille directed backwards, this organ always affects the form of 
the lower jaw: in Poultry it is like the barbed head of an arrow, the point being directed 
forwards; in Pigeons this saggital form is still more marked; in Geese and Ducks, on 
the contrary, and in consequence of the wide shape of the beak, it has not this disposition, 
and is softer and more flexible than in the Gallinace. 

With regard to the salivary glands annexed to the mouth, they are imperfectly 
developed, the presence of the fluids they secrete being less necessary in birds than in 
Mammals, as the food is nearly always swallowed without undergoing mastication; 
consequently insalivation is all but useless. 

Gurlt! speaks of a parotid gland situated beneath the zygomatic arch, whose duct 
opens into the mouth behind the commissure of the jaws. Meckel names this organ the 
angular gland of the mouth, and says that it is ditficult to regard it as representing the 
parotids, any morethan the glands of the cheeks and lips. Duvernoy’ categorically 
assimilates it to the latter. ; 

The sublingual glands lie in the median line throughout nearly their whole extent, 
and form an apparently single and conical mass, whose apex occupies the re-entering 
angle formed by the union of the two branches of the lower maxilla, 

According to Duvernoy, the submaxillary glands are represented by two very small 
organs situated behind the preceding. Their existence, however, is far from being 
general; for among common poultry, the Turkey was tho only bird in which Duvernoy 
observed these submaxillary glands. : 

Puaryyx (Fig. 221, 2).—This cavity is not distinct from the mouth, the soft palate 
being entirely absent in birds. On its superior wall mav be remarked the guttural oritice 
of the nasal cavities: a longitudinal slit divided into two by the infcrior border of the 
yomer. Below is another less extensive slit, the entrance to the larynx, and which is 
remarkable for the complete absence of the epiglottidean operculum. : 

CsopHacus.—This canal is distinguished by its enormous calibre and great expanst- 
bility. Its walls are very thin, and contain in their substance lenticular glands, easily seen 
in an inflated cesophagus, in consequence of the tenuity and transparency of its textures. 

At its origin, the cesophageal canal is not separated from the pharynx by any 
constriction; in its course it lies alongside the long muscle of the neck, and the trachea ; 
its terminal extremity is inserted into the first compartment of the stomach, or succentric 
ventricle, after entering the thorax and passing above the origin of the bronchi, 

ir two branches. 
eta ae the cesophagus is dilated in its cervical portion in such a manner as 
to form, when its walls are distended, a long fusiform cavity. 


1 ‘Anatomie der Hausvogel.? Berlin, 1849. ; 
3 Gusien. ‘ Anatomie Comparée.’ Qnd Edition. Paris, 1836, 


436 THE DIGESTIVE APPARATUS IN BIRDS. 


The abdominal muscles 
have been removed, as 
well as the sternum, 
heart, trachea, the 
greater portion of the 
neck, and all the head 
except the lower jaw, 
which has been turned 
back to show the tongue, 
the pharynx, and the 
entrance to the larynx. 
The left lobe of the 
liver, succentric ven- 
tricle, gizzard, and in- 
testinal mass, have been 
pushed to the right to 
exhibit the diiferent 
portions of the alimen- 
tary canal, and to ex- 
pose the ovary and ovi- 
duct. 
Tongue; 2, Pharynx} 
3, First portion of the 
esophagus; 4, Crop; 
5, Second portion of the 
cesophagus ; 6, Succen- 
tric ventricle; 7, Giz- 
zard; 8, Origin of the 
duodenum; 9, First 
branch of the duodenal 
flexure; 10, Second 
branch of the same; 
11, Origin of the float- 
ing portion of the small 
intestine; 12, Small 
intestine; 12’, Terminal 
portion of this intestine, 
flanked on each side 
by the two ceca (re- 
garded as the analogue 
of the colon of mam- 
mals); 13, 13, Free 
extremities of the ca- 
cums; 14, Insertion of 
these two culs-de-sac 
into the intestinal 
tube; 15, Rectum ; 16, 
Cloaca; 17, Anus; 18, 
Mesentery; 19, Lett 
lobe of the livers 20, 
Right lobe; 21, Gall- 
bladder; 22, Insertion 
of the pancreatic and 
biliary ducts; the two 
pancreatic ducts are the 
anteriormost, the cho- 
ledic or hepatic is in the 
middle, and the cystic 
duct is posterior; 23, 
Pancreas; 24, Dia- 
phragmatic aspect of 
the lung; 25, Ovary 
; (in a state of atrophy, ; 
GENERAL VIEW OF THE DIGESTIVE APPARATUS OF A FOWL, 26, Oviduct. 


= 


THE DIGESTIVE APPARATUS IN BIRDS. 437 


In Gallinace (Fig. 221, 3. 4, 5), this dilatation does not exist; but the cesophagus 
presents in its course, and immediately before entering the chest, an ovoid membranous 
pouch named the crop (or ingluvies.) In the cesopbagus of these birds, then, we find 
two distinct sections, jomed end to end—one superior or cervical, the other inferior or 
thoracic. on the limit of which is the crop. The latter does not differ in its structure 
from the cesophagus, and is a temporary reservoir for the food swallowed by the animal 
during its meal, and where it is softened by being impregnated with a certain quantity 
of fluid; ufter which it is passed into the succentric ventricle by the contractions of the 
external membrane of the crop, aided by a wide subcutaneous cervical muscle which 
covers that reservoir. 

In Pigeons, the crop is also present ; but it is divided into two lateral pouches, and 
exhibits glandular eminences towards the common inferior opening of these sacs into the 
cesophagus. ‘Otherwise, singular changes are observed in the apparent structure of its 
walls in the male as well as in the female, during incubation, or during the first weeks 
after hatching.” (Hunter was the first to observe this :—‘ Observations on Certain Parts 
of the Animal Economy,’ London, 1792). “At this period, the membranes of the crop 
become thickened; the vessels, more numerous and more apparent, are redder, and the 
glands more developed. The internal surface is divided by folds or ridges, which cross 
each other, and form triangular meshes ; while an apparently milky fluid is poured: out 
from the secretory pores into the cavity of the crop. Pigeons exclusively nourish their 
young with this fluid during the first three days of their existence.” ! 

SromacH —The stomach presents numerous variations in birds. Its simplest form is 
seen in the heron, pelican, petrels, etc., where it is a single sac provided with a thick 
zone of glands around the entrance of the oesophagus, which secrete the gastric juice. 
But in the majority of tle other species, aud particularly in our domesticated birds, the 
disposition of the stomach is modified and complicated ; the glandular zone destined for 
the gastric secretion forms a special compartment—the succentric ventricle, and this is 
followed by a second reservoir—the gizzard, which is remarkable for the strong muscular 
constitution of its walls. The first is also named the glandular stomach, and tle second 
the muscular stomach. 

Glandular stomach, or succentric ventricle (proventriculus) (Fig. 221, 6)—This is an 
ovoid sac placed in the median plane of the body, between the two lobes of the liver, and 
beneath the aorta. Its anterior extremity receives the insertion of the cesoplagus; the 
posterior is continued by the gizzard. The volume of this stomach is inconsiderable, and 
its cavity is very narrow; the alimeut does not accumulate in it, but merely passes 
through, carrying with it the acid juice which afterwards dissolvesits protein elements. Its 
walls have three tunics: an external or peritoneal; a middle, formed of white muscular 
fibres, continuous with those of the cesophagus; and an internal, of a mucous nature, per- 
forated by orifices for the passage of the gastrie juice. These are small cylinders placed 
perpendicularly to the surface of the stomach, closely laid against one another, like the 
microscopic glands of Lieberkiihn, and contained irf the cellular layer uniting the inner 
to the middle tunic. The glandular structure of this receptacle sutfticiently demonstrates 
that it should be assimilated to the right sac of the stomach in Solipeds, and therefore 
must be regarded as the true stomach. 

Gizzard, or muscular stomach (ventriculus bulbosus) (Fig. 221, 7).—Much more volu- 
minous than the preceding, this stomach is oval in form, depressed on each side. and 
situated behind the liver, being partly covered by the lateral lobes of that gland. Above, 
and to the right, and ata short distance from each other, are seen the insertion of the 
succentric ventricle and the origin of the duodenum. The cavity of the gizzard always 
contains food mixed with a large quantity of silicious pebbles, whose use will be indicated 
hereafter. 

This viscera is composed of the three tunics which form the walls of all the 
abdominal reservoirs. The internal, or mucous, is distinguished by the thickness and 
extraordinary induration of its epidermic layer, which presents nearly all the characters 
of horny tissue, and is so easily detached from the mucous chorium that it is often 
regarded as a special membrane. On the adherent face of this corium are applied two 
powerful red muscles—a superior and inferior, occupying the borders of the organ, and 
whose fibres, disposed in flexures, pass from side to side, and are inserted into a strong, 
nacrous aponeurosis on the lateral surfaces of the organ. Outside this contractile 
apparatus is a thin peritoneal envelope. 

The gizzard is the triturating apparatus of birds. When the aliment reaches its cavity 
it has not yet submitted to any disaggregation, but here it meets with all the conditions 


1 Duvernoy. ‘Lecons d’Anatomie Comparée de G. Cuvier.’ 2nd Edition. 
31 


438 THE DIGESTIVE APPARATUS IN BIRDS. 


indispensable to the accomplishment of this act: two energetic compressor muscles, a 
corueous layer spread over the internal surface of the viscera, giving to it the rigidity 
necessary {o resist the enormous pressure exercised on its contents; and _ silicious 
pebbles—veritable artificial teeth—which an admirable instinct causes birds to swallow, 
and between which, by the efforts of the tiiturating muscles, the food is bruised. This 
triturating action of the gizzard is only effected in birds fed on hard coriaceous aliment, 
such as the various kind of grain, It would be useless in birds of prey, in which the 
two gizzard muscles are replaced by a thin fleshy membrane of uniform thickness ; 
showing that the presence of these muscles is subordinate to the kind of alimeutation. 

Inrestine.— The length of the intestine varies, as in Mammals, according to the 
nature of the food: very short in birds of prey, it is notably elongated in omnivorous 
and granivorous birds. Its diameter is nearly uniform throughout its whole extent, 
and it is difficult to establish in birds the various distinctions recognised in the intestine 
of Mammalia. It begins by a portion curved in a loop, which represents the duodenum, 
and whose two branches, lying side by side, are parallel to each other like the colic 
flexure of Solipeds. Fixed by a short mesenteric earth to the colon, this part of the 
intestine includes the pancreas between its two branches. Its curvature floats freely in 
the pelvic portion of the abdominal cavity (fig. 221, 8, 9, 10). 

To the duodenal loop suececd convolutions suspended to the sublumbar parietes by a 
long mesentery, and which are rolled up into a single mass, elongated from before to 
behind, occupying a middle position between the air sacs of the abdominal cavity. 
The analogy existing between this mass of convolutions, and the floating portion of the 
small intestine of Mammals, does not require demonstration (fig. 221, 11, 12). 

The terminal part of this floating iutestine lies beside the duodenal loop, and is 
flanked by the two appendages disposed like caca. ‘These, scarcely marked in the 
Pigeon by two smill tubercles placed on the track of the intestinal tube, do not measure 
Jess than from six to ten inches in the other domesticated birds; they are two narrow 
culs-de-sac, slightly club-shaped at their closed extremities, which are free and directed 
towards the origin of the intestine, while the other extremity opens into the intestinal 
canal near the anus. There are always alimentary matters in these sacs, these becoming 
introduce:l, in following w retrograde course, by the same almost unknown mechanisia 
which presides over the accumulation of spermatic fluid in tle vesicule seminales. Ac- 
cording to the majority of naturalists, these two appendages, although described as exea, do 
not represent the reservoir bearing that designation in Mammals. ‘This reservoir is 
nothing more than a small particular appendix placed on the track of the intestine, in front 
of the free extremity of the above-mentioned culs-de-sac, and which is only to be found 
in a small number of birds, and among these sometimes, as Guilt affirms, is the Goose. 
According to this view, which appears to be a very rational one, the portion of intestine 
comprised between the two blind tubes annexed to the viscera (fig 221, 12) corresponds 
to the colon, and these tubes themselves are only dependencies of this intestine. 

The rectum (fig. 221, 15) terminates the digestive canal; it is the brief portion of 
intestine which follows the opening of the cca. Placed in the sublumbar region 
this viscus is terminated hy a dilatation, the cloaca (fig. 221, 16), a vestibule coninii 
to the digestive and genito-urinary passages, which opeus oxternally at the anus, lodges 
the penis when it exists, and serves as a confluent for the ureters, oviduct, bursa of 
Fabricius, and the deferent canals. 2 

ABDOMINAL APPENDAGES OF THE DicrstivE CanaL.—Liver (Fig. 221, 19, 20).—This 
is a voluminous gland, divided into two principal lobes—a right and left, the former 
always larger than the latter; these incompletely include, on each side, the gizzard and 
succentric ventricle. In the Pigeon, this gland is provided with w gall-bladder 
(fig. 221, 21) attached to the internal face of the right lobe. But the arrangemé¢nt of 
the excretory apparatus is not altogether identical with that observed in Maufmals 
which possess this receptacle ; as two biliary ducts open separately into the int¥tine 
towards the extremity of the second branch of the duodenal loop. One prleeding 
directly from the two lobes of the liver, is the hepatic or choledic duct ; the other, the cystic 
duct, remains independent of the lutter,and opens behind it. It carries into the digestive 
eanal the bile accumulated in the gall-bladder, and which arrives there by a particular 
an aoe exclusively to the right lobe; the cystic canal is a brancli of this duct 

Pancreas (Fig. 221, 23).—In the Gallinace, this gland is very developed, lone 
narrow, and is comprised in the duodenal loop or ie at ie extremity nee 
gizzard it has two principal excretory ducts, which separately pierce the intestinal 
ar oll Re pe in front of the se canal. 

pleen.—This is a small, red-coloured, dise-shaped body, placed ic 
stomachs, on the limit of the gizzard and sefonire entice : seine sight af ah 


BOOK ITI. 


Respiratory APPARATUS. 


THE maintenance of life in animals not only requires the absorption of the 
organisable and nutritive matters conveyed to the internal surface of the 
digestive canal, but demands that another principle, the owygen of the atmo- 
sphere, should enter with these materials into the circulation. In animals 
with red blood, this element, in mixing with the nutritive fluid, commences 
by expelling an excrementitial gas, carbonic acid, and communicating a bright 
red colour to that fluid, with which it circulates ; it is brought into contact, 
in the general capillary system, with the minute structures of the various 
apparatus, exercising on the organic matter composing them a special 
excitory influence, without which the tissues could not manifest their 
properties, as well as inducing a combustible action which evolves the heat 
proper to the animal body. 

This new absorption constitutes the phenomenon of respiration. In the 
Mammalia, this is effected in the lungs : parenchymatous organs hollowed out 
into a multitude of vesicular spaces which receive the atmospheric air and 
expel it, after depriving it ofa certain quantity of oxygen, and giving, in return, 
a proportionate quantity of carbonic acid. These organs are lodged in the 
thoracic cavity, whose alternate movements of dilatation and contraction they 
follow. They communicate with the external air by two series of canals 
placed end to end: 1, A cartilaginous tube originating in the pharyngeal 
vestibule, and ramifying in the lungs; ; 2, The nasal cavities, two fosse 
opening into that vestibule, and commencing by two openings formed at the 
anterior extremity of the head. 


CHAPTER I. 


RESPIRATORY APPARATUS OF MAMMIFERS. 


In this apparatus we will first study the organs external to the thoracic 

ce ihe nana cavities, and larynw and trachea ; then the chest and the 
: it contains—the lungs. 

or oro ‘this study will be added that of the two glandiform organs whose 

uses are unknown, but which, by their anatomical connections, belong to the 

respiratory apparatus. ‘These are the thyroid bodies and the thymas gland. 


THE NASAL CAVITIES, 


These cavities are two in numberfi@gxight and left, and offer for study : 
their entrance, or nostrils—the fosge%e roperly called, which constitute 
these cavities; and the diverticuli named: sinuses. 

meee 


wea oe 


440 THE RESPIRATORY APPARATUS IN MAMMALIA. 


Preparation—Remove the lower jaw from three heads. On the first of these make 
two transverse sections, one passing between the second and third molar tooth, the other 
behind the dental ‘arcade. Saw through the second head longitudinally and vertically, a 
little to one side ofhe median line. On the third make a horizontal section in such a 
manner as to obtain ah inferior portion analogous to that shown in figure 23. 


1. The Nostrils. 


The nostrils are two oblong, lateral openings, situated at the extremity 
of the nose, circumscribed by lips or movable wings (ale) disposed in an 
oblique direction downwards and inwards, and slightly curved on them- 
selves, so as to present their concavity to the external side. 

The lips or ale of the nostril are enveloped, inwardly and outwardly, by a 
thin, delicate skin, covered by fine, short hairs. The external is concave on 
its free margin; the internal is convex. The commissure which unites these 
two wings superiorly, forms a slight cross curved inwards, When the finger 
is introduced into this commissure it does not enter the nasal cavity, but the 
false nostril: a conical pouch formed by the skin, extending to the angle 
comprised between the nasal spine and the elevated process of the pre- 
maxillary bone. 

In the Ass, according to Goubaux, the false nostril is areolated at the 
posterior extremity, which ascends beyond the summit of the re-entering 
angle formed by the nasal and premaxillary prolongation. 

The inferior commissure is round and wide, and, towards the bottom, 
presents an opening, sometimes double, which looks as if punched out; this 
is the inferior orifice of the lachrymal duct, which, in the Ass and Mule, is 
carried to the inner face of the external wing, near the superior commissure. 

Srructury.—The nostril is composed of a cartilaginous framework, 
muscles to move it, and integuments, vessels, and nerves. 

Cartilaginous framework (Fig. 222).—This framework is formed by a 

aes cartilage, bent like a comma, and which, in its middle 
mites! part, lies against that of the opposite side, the two 
ui making a kind of figure X. Fixed in a movable 
manner to the inferior extremity of the middle septum 
of the nose, by means of short interposed fibres, this 
cartilage offers: a wide upper part, situated in the 
substance of the inner wing of the nostril. and covered 
by the transverse muscle of the nose (Fig. 222, 1); 
and an inferior portion, which, after passing into the 
lower commissure, is prolonged, in a blunt point, to 
the external wing, where it receives the insertion of 
several fasciculi belonging to the orbicularis muscle 
of the lips, the pyramidal muscle of the nose, and 
the supernaso-labialis (Fig. 222, 2). Each wing, 
therefore, possesses a cartilaginous skeleton; but that 
Gacdie ee tauneee: of the external wing is very incomplete, in conse- 
1, 1, Wide portion, form. (ence of its being only formed by the inferior ex- 
ine the base of the inter- tremity of the common cartilage. 
nal wing of the nostril , This cartilage, it will be understood, sustains the 
2,2, Narrow extremity ale of the nose, prevents their falling inwards, and 
prolonged into the ex- always keeps open the external orifices of the re- 
ternal wing ; 3, Superior ¢ 
or anterior border of the SPiratory apparatus. 
septum. Muscles.—The motor muscles of the ale are all 
dilators in the domesticated animals. Theyare: the 
transversalis nasi (dilatator naris anterior—Percivall), or transversalis of the 


. THE NASAL CAVITIES. 441 


nose, @ single muscle placed on the widened portion of the cartilaginous 
pieces ; the supermawillo-nasalis magnus (dilatator naris lateralis —Percivall), 
or pyramidal muscle of the nose, whose insertion occupies the whole extent 
of the external wing; the swpermamillo-nasalis parvus (nasalis brevis labit 
superioris— Percivall), fixed, by its two portions, to the skin of the false 
nostril; the middle anterior (depressor alee nasi—Percivall) which is con- 
founded, superiorly, with the external fasciculus of the preceding muscle, 
it being attached to the inferior branch of the cartilaginous appendix of the 
maxillary turbinated bone; and, lastly, the supernaso-labialis (levator labii 
superioris aleque nasi—Percivall), whose anterior branch is inserted, in 
part, into the external wing. All these muscles having been described in 
the Myology (page 220), need not be further alluded to here. 

Integuments of the nose——The skin covering the alex of the nose, ex- 
ternally, is doubled over their free margin to line their internal face, being 
prolonged over the entire extent of the false nostril, and is continued, in 
the nasal fosse, properly called, by the pituitary membrane. This skin is 
fine, thin, charged with colouring pigment, often marked by leprous spots, 
and adheres closely to the muscles included between its duplicatures, through 
the medium of a very dense and resisting fibro-cellular tissue. 

Vessels and nerves —The nostrils are supplied with blood by the superior 

coronary, the external nasal, and the palato-labial arteries ; itis returned by the 
glosso-facial veins, and partly by the venous network of the nasal mucous 
“membrane. The lymphatics, large and abundant, receive those of the 
pituitary membrane, and join the submaxillary glands by passing over the 
cheeks. The nerves are very numerous, the sensory being derived from 
the maxillary branch of the fifth pair, and the motors from the facial 
nerve. 

Fuycrions.—The nostrils permit the entrance to the nasal cavities, 
of the air which is to pass to the lungs. Their dilatability allows the 
admission of a greater or less volume, according to the demands of 
respiration. It is to be remarked that, in Solipeds, the nostrils constitute 
the only channel by which the erial column can be introduced to the 
trachea, in consequence of the great development of the soft palate, which is 
opposed to the entrance of air by the mouth; these orifices are also, for the 
same reason, relatively larger than in the other domesticated animals, in 
which the passage of air, by the buccal cavity, is easily accomplished. 


2. The Nasal Fosse. (Figs. 223, 224.) 


Channeled in the substance of the head, above and in front of the palate, 
and separated from one another, in the median plane, by a cartilaginous 
septum which does not exist in the skeleton, the nasal fosse extend from the 
nostrils to the eribriform plate of the ethmoid bone, in a direction parallel 
to the larger axis of the head. Their length is, therefore, exactly measured 
by that of the face. See Fig. 223 for the whole of these cavities. 

The nasal fossee are formed by two lateral walls, a roof or arch, a floor, and 
two extremities. ’ 

Walls.—The two walls are very close to each other, and the more so as 
they are examined towards the ethmoid bone and the roof of the cavity. The 
space separating them varies, In proportion as it is measured at the level of 
the turbinated bones or at the meatuses. 

Inner wall.—This is formed by the nasal septum, and is perfectly 
smooth. 


442 THE RESPIRATORY APPARATUS IN MAMMALIA. 


Outer wall.—This is chiefly constituted by the supermaxillary bone, 
is very rugged, and is divided into three meatuses, or passages, by the 
turbinated bones—the irregular columns applied against the inner face of the 
before-mentioned bone. 

The turbinated bones have already been described, and we will only now 
refer to the principal features of their organisation. Each is formed of a 
bony plate rolled upon itself (Fig. 223, 2, 3), and is divided, internally, into 
tivo sections, the superior of which forms part of the sinus, and the in- 
ferior belongs to the nasal fosse ; they are continued, inferiorly, by a fibro- 
cartilaginous framework, which prolongs their nasal section to the external 
orifice of the nose. The flexible appendix of the ethmoidal turbinated bone 
is usually single, sometimes double, and disappears before reaching the ale 
of the nose. That of the maxillary turbinated. bone is always bifurcated, 


TRANSVERSE SECTION OF THE HEAD OF AN OLD HORSE, SHOWING THE ARRANGEMENT 
OF THE NASAL CAVITIES AND MOUTH. 


1, Nasal fossa; 2, Superior turbinated bone; 3, Inferior ditto; 4, Median septum of 
the nose; 5, Central part of the buccal cavity (drawn more spacious than it 
really is when the twe jaws are brought together); 6, 6, Lateral portions of the 
same; 7, Section of the tongue. 


and its antero-superior branch is directly continued by the superior extremity 
of the internal wing of the nostril. 

The meatuses are distinguished into superior, middle, and inferior, or into 
anterior, middle, and posterior, as the head is inspected in a vertical or hori- 
zontal position. The superior passes along the corresponding border of the 
ethmoidal turbinated bone, and is confounded with the roof: of the nasal 
cavity ; it is prolonged, behind, to near the cribriform plate of the ethmoid 


THE NASAL CAVITIES. 443 


bone: it is the narrowest. The middle, comprised between: the two tur- 
binated bones, presents, on arriving near the ethmoidal cells, the orifice 
which brings all the sinuses into communication with the nasai fossa. This 
orifice is ordinarily narrow and curved; but we have seen it sometimes 
converted into a foramen sufficiently wide to permit the introduction of a 
finger end. Itis also by this meatus that the inferior compartment of the 
turbinated bones opens into the nasal fossa, these two bones being each 
rolled in a contrary direction. The inferior meatus, situated under the 
maxillary turbinated bone, is not distinct from the floor of the nasal cavity. 
See figure 224 for the arrangement of the turbinated bones and the meatuses 
on the external wall of the nose. 

Roof or arch.—This is formed by the nasal bone, and is only a narrow 
channel, confounded, as has been said, with the superior meatus. 

Floor,—Wider, but not so long as the roof, which is opposite to it, but 
from which it is distant by the height of the cartilaginous septum, the floor 
is concave from side to side, and rests on the palatine arch, which separates 
the mouth from the nasal cavities. 

In front of this nasal region is remarked the canal or organ of Jacobson : 
a short duct terminating in a cul-de-sac in the middle of the cartilaginous 


LONGITUDINAL MEDIAN SECTION OF THE HEAD AND UPPER PART OF NECK. 


1, 1, Atlas; 2, 2, Dentata; 3, Trachea; 4, Right stylo-thyroideus ; 5, Guttural 
pouch; 6, Stylo-pharyngeus; 8, Palato-pharyngeus; 9, Sphenoidal sinus; 10, 
Cranial cavity; 11, Occiput; 12, Parietal protuberance ; 13, Frontal sinus ; 
14, Ethmoidal turbinated bone; 15, Maxillary turbinated bone; 16, Entrance to 
nostril, 18, Pharyngeal cavity; 19, Inferior maxilla; 20, Premaxilla; 21, 
Hard palate. 


substance which closes the incisive foramen. At the bottom of this cul-de- 
sac opens a second canal, longer, wider, and more remarkable, but which 
has not yet been described. (It has been described by Stenson, and is named 
“Stenson’s duct.”) It has sometimes the diameter of a writing quill, 
commences by a cul-de-sac on a level with the second molar tooth, accom- 
panies the inferior border of the vomer from behind to before, where it is 
enveloped in a kind of cartilaginous sheath—a dependency of the nasal 
septum; it terminates, as we have said, after a course of about 5 inches. 


444 THE RESPIRATORY APPARATUS IN MAMMALIA. 


The structure of this duct resembles that of the excretory ducts of glands; 
its walls are evidently composed of two tunics—an internal or mucous, 
very rich in follicles, and having longitudinal folds, and an external, of a 
fibrous nuture. These membranes receive numerous vessels, as well as 
nervous divisions emanating from a long filament of the spheno-palatine 
ganglion, and which may be traced from the external -side of the canal to 
near the incisive foramen, where it is lost. Such is the organ of Jacobson ; 
its uses are quite unknown. 

Extremities.—The anterior or inferior extremity of the nasal fossa is 
formed by the nostril already described. The posterior or superior extremity 
presents, above, a space occupied by the ethmoidal cells. Below and behind, 
this extremity communicates with the pharyngeal cavity by a wide oval 
opening, which is circumscribed by the vomer and palate bones: this is the 
guttural opening of the nasal fossa. 

Srructure.—The nasal fosse offer for study in their organisation: 
1, The bony framework by which these cavities are formed; 2, The 
cartilaginous septum separating them; 38, The pituitary membrane—the 
mucous layer covering their walls. 

1. Bony Framework or toe Nasat Fossa.-—This comprises: 1, The 
nasal, maxillary, frontal, and palate bones, which together form a vast irre- 
gular tube circumscribing the nasal fosse ; 2, The ethmoid bone, occupying 
the bottom of this tubular cavity and the turbinated bonea applied against 
the lateral walls; 8, The vomer, placed in the median plane, and serving as 
a support for the cartilaginous partition dividing this single cavity into two 
compartments. All these bones having been already studied in detail, we 
confine ourselves to their simple enumeration. 

2. Mippie Septum or Tre Nose (Fig. 223, 4).—Formed of cartilage 
susceptible of ossification, this partition is nothing more than the perpendi- 
cular lamina of the ethmoid bone prolonged to the extremity of the nose. 
Its elongated form permits us to recognise in it two faces, two borders, and 
two extremities. ‘The faces are channeled by a multitude of furrows, which 
lodge the anastomosing divisions of the magnificent venous plexus of the 
pituitary membrane. 

The superior border, united to the frontal bone and median suture of the 
nasal bones, expands to the right and left on the inner faces of these, in 
forming two lamine, thin at their free margin, the section of which is 
represented in Fig. 223, These lamine are wide enough in front to project 
beyond the nasal spine. The inferior border is received into the mortice of 
the vomer. 

The posterior extremity is continued without any precise limitation, by 
the perpendicular lamina of the ethmoid bone. 

The anterior extremity, a little wider, supports the cartilages of the 
nostrils. It is joined, below, to the premaxillary bones, and is spread out 
on the incisive openings in a thick layer which exactly closes them. 

This septum is covered by a thick perichondrium, which adheres 
intimately to the pituitary membrane. 

3. Prrorrary Memprans.—This membrane, also designated the olfactory 
mucous membrane, and Schneiderian membrane, is continuous with the cutaneous 
integument covering the inner face of the ale of the nose. Considered at 
first on the internal wall of the nasal fosse, the pituitary membrane is seen 
to cover the cartilaginous septum forming this wall, then to be spread over 
the floor as well as the roof of the cavity, reaching the outer wall, which 
it also covers in enveloping the external surface of the turbinated bones, 


THE NASAL CAVITIES. 445 


and is insinuated, by the middle meatus, into the cells of the inferior or 
anterior compartment of these osteo-cartilaginous columns. It also penetrates, 
by the semicircular opening of this meatus, into the sinus, to give it its 
mucous covering, and is likewise prolonged into the apparatus of Jacobson. 
Behind, it is confounded with the lining membrane of the pharyngeal cavity. 

Its deep face is separated by the periosteum or perichondrium, from the 
bony or cartilaginous walls on which it is spread; and it is united to the 
two precited layers, this union being closest where it is thinnest, although 
it can always be easily distinguished from these two fibrous layers through- 
out the whole extent of the nasal fossa. The free, or superficial face, presents 
numerous glandular orifices, and is constantly covered by an abundance of 
mucus, that prevents the desiccation to which this surface is exposed by 
the incessant movement of air over it. 

Srructure.—The organisation of the pituitary membrane resembles 
that of other mucous membranes, but it also presents some differences 
according as to whether it is examined near the nostrils or deeper in 
the cavities. It is also usual to divide it into two portions: the olfactory 
mucous membrane, which covers the upper part of the ethmoidal turbinated 
bone and cells; and the Schneiderian membrane covering the inferior two- 
thirds of the nasal cavities. 

The corium of the Schneiderian membrane is thick, soft, spongy, and 
rose-coloured, and contains a large number of vessels and glands. The 
latter are mucous or racemose glands, and are extremely abundant in the 
layer covering the septum of the nose, as well as at the inner face of the 
cartilaginous appendices of the turbinated bones; 
though they are rare or altogether absent on the Fig. 225, 
external face of the latter, The epithelium is ciliated 
and stratified, the deeper cells being round, those on 
the surface columnar. 

The olfactory mucous membrane differs from the 
preceding by its greater thinness, its delicateness, its 
slightly yellow tint, and the character of its epithe- 
lium. The coriwm contains straight or slightly-con- 
torted tubular glands—the glands of Bowman. The 
epithelium is columnar and_ stratified, and readily 
changes; in animals it is destitute of cilia. The 
deeper cells contain some yellowish pigment granules. 
Schultze describes as olfactory cells, certain fusiform 
elements which he considers as concerned in olfaction. 
These cells have two prolongations: a deep one, 
which is connected with the fibres of the olfactory 
nerve; and a superficial, that enters between the 
epithelial cells and tends to approach the free surface 
of the membrane. 

(The “olfactory cells” are thin, rod-like bodies 
(Fig. 225, b), presenting varicose enlargements which 
are connected with processes of deeper-seated nerve- Gaizs op tim OLFACTORY 
cells. The epithelial cylinders proper (4, €) are ~~ MUCOUS MEMBRANE. 
related at their bases with the septa of connective , 4 « After Schultze 
tissue belonging to the sub-epithelial glandular layer, "ad, e, f, After Lockhart 
and are probably in communication with the olfactory — Clarke. 
cell. Schultze describes another set of epithelial 
cells (a) as terminating externally by truncated flat surfaces, and to all 


446 THE RESPIRATORY APPARATUS IN MAMMALIA, 


appearance not covered by any membrane, apart from the contents of the cell, 
which area yellow, granular proto-plasma surrounding an oval nucleus lying 
in colourless proto-plasma. The extremity of these cells is thin, and they 
can be traced inwards until they expand into a flat portion that sends off pro- 
cesses which appear to be continuous with the fibres of the submucous 
connective tissue. Similar cells (c) are found towards the margin of the 
true olfactory region, but these have a band at their free extremity, which is 
also provided with a circle of cilia.) ; 

The pituitary membrane receives its blood by the ophthalmic and nasal 
arteries ; it is returned by the large anastomosing veins which form, in the 
deep layer, a long, close, and magnificent plexus that terminates in the 
satellite vein of the nasal artery. This plexuous arrangement is so marked at 
certain points—as at the appendices of the turbinated bones, taat it gives the 
mucous membrane somewhat the appearance of erectile tissue. It will be 
understood that in favouring the stagnation of the blood, this arrangement 
predisposes to hemorrhage. 

The lymphatics of the pituitary membrane could not be injected for a 
long time, neither in man nor animals; and this led several anatomists to 
deny their existence. Nevertheless, they do exist, and form a fine superficial 
network on the septum of the nose, the turbinated bones, and the meatuses. 
The trunks passing from it go to the submaxillary glands. 

The nerves of this membrane are numerous, and are derived from the 
first and fifth pairs, and from Meckel’s ganglion. The ramifications of the 
olfactory nerve, on emerging from the apertures of the cribriform plate of 
the ethmoid bone, pass to the inner and outer walls of the nasal cavities ; 
being destined for the olfactory mucous membrane, they do not descend 
below the upper third of these cavities. They form at first a close plexus, 
and afterwards terminate in a manner not quite understood. Schultze admits 
that they terminate on the olfactory cells mentioned above. 

The branches derived from Meckel’s ganglion and the fifth pair are 
specially destined for the Schneiderian membrane, and 
are named the ethmoidal branches of the palpebro-nasal 
and spheno-palatine nerves. They endow the nose with 
an acute degree of sensibility, and it is believed that 
they render olfaction more perfect. 

(It is to be remarked that the filaments composing 
the olfactory plexus differ from ordinary cephalic nerves 
in containing no white substance of Schwann, and are 
nucleated and finely granular in texture, resembling the 
gelatinous form of nerve-fibres. The surface to which 
they are limited is that covered with the yellowish- 
brown epithelium.) 


Fig. 226. 


3. Sinuses. 


The sinuses are very anfractuous cavities, excavated 
in the substance of the bones of the head, on the limits of 
FIBRES OF ULTIMATE the cranium and face, and around the ethmoidal masses, 

RAMIFICATIONS OF which they envelop. . 
— NERVE These cavities. diverticuli of the nasal fosse, are 
pairs, and are five on each side: the frontal, super- 
maxillary, sphenoidal, ethmoidal, and inferior maxillary sinuses. The first 
four communicate; the last is usually perfectly isolated. 
Frontat Sivus.—This cavity, situated at the inner side of the orbit, 


THE NASAL CAVITIES. 447 


presents very irregular walls, which are formed by the frontal, nasal, lachry- 
mal, and ethmoidal bones, and the superior portion of the ethmoidal 
turbinated bone. It communicates with the superior maxillary sinus by a 
vast opening made in a very thin bony partition. A thick vertical plate, 
often bent to the right or left, but always imperforate, separates this sinus 
from that of the opposite side. 

Superior Maxitpary Sinus.—Channeled beneath the orbit, between the 
maxillary, zygomatic, ethmoid, and lachrymal bones, this diverticulum is the 
largest of all, and is divided into two compartments by the maxillo-dental 
canal, which traverses it. The internal compartment constitutes a kind of 
shallow cavity, continuous with the sphenoidal sinus, and presents a narrow 
slit, which penetrates to the ethmoidal sinus. The external compartment 
is separated, in front, from the maxillary sinus by @ partition which M. 
Goubaux has, contrary to the generally-received opinion, demonstrated to be 
imperforate at all periods of life; though he has sometimes found it so thin 
as only to consist of two mucous layers laid against each other, This 
compartment is prolonged backwards into the maxillary protuberance, and 
the roots of the two last molars project into its anterior. 

SpHenomwaL Sinvus.—This is the smallest, after that of the great 
ethmoidal cell. Formed by the sphenoid and palate bones, this cavity is very 
irregular, and is subdivided by incomplete septa into several compartments, 
which may be always reduced to two: an anterior, comprised between the 
palatine lamine; the other posterior, hollowed in the body of the sphenoid 
bone. In contact, on the median line, with the sinus of the opposite side, 
it is separated from it by a twisted plate, which is constantly perforated, even 
in young animals. 

Erumorat Sinus.—By this name is designated the internal cavity of the 
large ethmoidal cell, which constitutes a real sinus, and which a narrow 
slit brings into communication with the superior maxillary sinus. 

Inrrriorn Maxitiary Sinus.—This last diverticulum is remarkable because 
of its not communicating with the others. Excavated in the supermaxillary 
bone, and separated from the superior sinus by the imperforate septum 
previously mentioned, it is divided, like the latter cavity, into twe compart- 
ments: an internal, prolonged into the superior cavity of the maxillary 
turbinated bones; and an external, the smallest, showing the roots of the 
fourth molar, rarely those of the third. It does not descend, as Rigot has 
asserted, above the three front molars; but supposing the head to be vertical, 
it does not extend, in the adult Horse, beyond the extremity of the maxillary 
ridge, in front of which it would be necessary to trepan, in order to arrive 
at its interior. 

Communicatine OrIFIcE or THE SrnusEs wits THE NasaL Fossa.—All 
the sinuses of one side communicate with the corresponding nasal fossa by 
the curved slit which has been observed at the bottom of the middle meatus, 
This slit penetrates the superior maxillary sinus, under the septum that 
separates it from the frontal sinus; it also enters the inferior maxillary 
sinus, which thus communicates solely with the nasal cavity, while the 
other diverticuli open in common into this cavity through the medium of 
the superior maxillary sinus. 

Mucous Mremsrane or tHE Sinvuses.—In entering the sinuses to cover 
their walls, the pituitary membrane becomes extremely thin, and loses its 
great vascularity ; it is applied immediately to the bones, and serves as a 
periosteum. . : 

' DEVELOPMENT oF THE SinusEs.—-These cavities begin to be developed in 


448 THE RESPIRATORY APPARATUS IN MAMMALIA. 


the foetus, and are gradually hollowed in the thickness of the bones which 
concur to form them. They increase during the animal’s lifetime, by the 
thinning of the bony plates inclosing or partitioning them, and particularly 
by the growth of the superior molar teeth, whose roots project into these 
cavities. The formation of the inferior maxillary sinus is more tardy than 
the others; though it is not so late as seven or eight years, as the majority of 
Veterinary Anatomists have asserted. M. Goubaux has proved that the sinus is 
already present at six months old ; and in a head which has been for several 
years in the museum of the Lyons School, and which belonged to a foal of 
very small stature, about a year old, this sinus is seen, in its external part, 
to be already 14 inches in depth, and 8-10ths of an inch in width. 

Functions or tHe Sinuses.— Have the sinuses or diverticuli of the nasal 
cavities the same uses as these cavities? It is probable, although not 
absolutely certain. There is nothing to prove that they have anything to do 
with respiration or olfaction ; and it would seem that their exclusive function 
is to give increased volume to the head without increasing its weight, and 
in this way to furnish wide surfaces of insertion for the muscles attached 
to this bony region—these cavities being all the more ample as the muscles 
are large and numerous. 


DIFFERGNTIAL CHARACTERS OF THE NASAL CAVITIES IN OTHER THAN SOLIPED ANIMALS. 


1. Nostrils —In the Oz, the nostrils, placed on each side of the muffle, are narrower 
and less movable than in the Horse. (The superior extremity of the ala is not horizontal ; 
the inferior is divided into two branches.) 

In the Pg, the end of the nose constitutes the snout (rostrum suis), whose anterior 
surface, planc and orbicular, shows the external orifices of the nostrils, This snout, a 
veritable tactile organ employed by the animal to dig up the ground, is covered by a 
dark-coloured skin, kept damp by a humid secretion, like the muffle of the Ox. It has 
for a base the scooping-bone, a particular piece situated at the extremity of the nasal 
septum, anil enveloped by a layer of cartilage which extends around the nostrils. It is 
easy to distinguish two symmetrical halves in this bone, which evidently represent the 
two cartilaginous pieces in the nose of Solipeds. 

In the Dog, the end of the nose forms a salient region, which is roughened, naked, 
usually dark-coloured, damp, and sometimes divided by a median groove ; in this region 
the nostrils ure pierced, their form resembling two commas opposed to each other by their 
convexities. The cartilaginous framework sustaining these orifices is not composed of 
separate pieces, but is only a dependance of the median septum and the appendages of 
the turbinated bones. 

The same considerations apply to the nostrils of the Cat with the exception of the 
colour of the integument, which 1s nearly always of a rosy hue, like the mucous surfaces. 

2. Nasal Cavities—The nasal fosse of the Ox, Sheep, and Goat are distinguished by 
the presence of a third turbinated bone—the olfactory antrum, and by the communication 
existing between them, posteriorly, above the inferior border of the vomer. We have 
already seen that in these animals, as in thuse yet to be mentioned, the canal of Jacobson 
completely traverses the palatine arch. 

In tlie Pig, the nasal fossee are long and narrow. They are, on the contrary, very 
short in the Dog and Cat, and the internal cells of the turbinated bones, remarkuble 
for their number and complexity, all communicate with the proper nasal fosse, without 
concurring in the formation of the sinuses. 

3. Sinuses—In the Uz, the frontal sinuses are prolonged into the bony cores which 
support the horns, and into the parietal and occipital bones; they therefore envelop, in 
a most complete manner, the anterior and superior part of the cranium, and form a 
double wali to this bony receptacle. They are extremely diverticulated, and do not 
communicate with those of the great maxillary bones. They usually open, on each side, 
into the nasal cavities by four apertures pierced at the base of the great ethmoidal cell. 
According to Girard, three of these orifices Jead to special compartments, isolated from 
one another, and grouped around the orbit ; in consequence of which these diverticuli of 
the frontal sinuses are designated the orbital sinuses. 

This author has denied the presence of sphenoidal sinuses; but they exist, although 
smal], and are in communication with the preceding. 


THE LARYNX. 449 


The sinus of the great ethmoidal cell comports itself as in the Horse. 

‘There is only one pair of maxéllary sinuses, which are very large, and partitioned into 
two compartments by a plate of bone, that bears at its superior border the supermaxillo- 
dental canal, like the superior maxillary sinus of Solipeds. The external or maxillary 
compartment is prolonged into the lachrymal protuberance; the internal occupies the 
thickness of the palatine arch. A wide orifice at the base of the maxillary turbinated 
pone affords a comniunication between this sinus and the nasal fossa. 

In the Sheep und Goat, there exists a similar arrangement of the sinuses of the 
head ; but these cavities are much less spacious than in the Ox; the frontal sinus, in 
particular, does not extend beyond the superior border of the fruntal bone. 

In the P2g, these latter sinuses are prolonged into the parietal bones; though they 
are far from offering the same exteut as in the smaller Ruminants. It is the same with 
the others; they present an arrangement analogous to those of the Sheep and Goat. 

In the Dog and Cat, there are only, on each side, a maxillary and a frontal sinus. 
The first scarcely merits notice; and the second, a little more developed, opens into the 
nasal cavity by means of a small aperture situated near the middle septum of the two 
frontal sinuses, 

(Leyh states that the Carnivora have no maxillary sinus ; consequently, the sphenoidal 
sinus communicates below with the nasal fosse.) 


COMPARISON OF THE NASAL CAVITIES IN MAN WITH THOSE OF ANIMALS, 


The external orifices of the nasal cavities of Man are called nostrils ; these are fla..ened 
transversely, and prolonged in front of the lobule of the nose; their external face or ala 
is concave and movable. They are lined internally by a membrane that holds a middle 
place between the skin and mucous membranes ; it has a number of little hairs, called 
vibrissx. 

The cavities or nasal fossx offer nothing particular ; as in animals, they show a superior, 
middle, and inferior meatus. On their floor, in front, is seen the superior orifice of the 
incisive foramen, which corresponds to the commencement of Jacobson’s canal. The 
pituitary membrane has a squamous epithelium in its olfactory, as on its Sclmeiderian 

ortion. At the bottom of the nasal cavities and the upper part of the pharynx, is a 
ind of diverticulum named the posterior nares; it has been already alluded to when 
speaking of the pharynx. 

The sinuses are: 1, The spheuoidal sinus and the posterior ethmoidal cells, that open 
beneath the roof of the nasal fossee; 2, The middle ethmoidal cells, opening into the 
superior meatus; 3, The unterior ethmoidal cells, and frontal and maxillary sinuses, 
communicating with the middle meatus, All these sinuses have a proper communicating 
orifice with the nasal cavities. 


THE AIR TUBE SUCCEEDING THE NASAL CAVITIES. 


This single tube comprises: the larynx, which commences the trachea ; 
the latter forms the body or middle portion, the bronchie terminating it. 


. Larynx. (Figs. 227, 228, 229.) 


Preparation.—1. Make a longitudinal section of the head, in order to study tho 
general disposition of the larynx (Fig. 224. 2. Isolate the cartilages, to examine 
their external conformation. 3. Remove the muscles from a third larynx, to show the 
mode of articulation of the various cartilages (Figs. 227, 228). 4. Prepare the muscles in 
conformity with the indications furnished by a glance at figure 229. 5. Remove a Jarynx 
as carefully as possible, ro as not to injure the walls of the pharynx, in order to study 
the interior of the organ, and especially its pharyngeal opening. 


Form—Situation.—The laryna forms a very short canal, which gives 
passage to the air during respiration, and is at the same time the organ 
of the voice. 

It isa cartilaginous box, depressed on each side, and open from one end to . 
the other : the anterior orifice being situated at the bottom of the pharyngeal 
cavity, and the posterior continuous with the trachea. 

This apparatus, situated in the intermaxillary space, is suspended 
between the two cornua of the os hyoides, and fixed to the extremities of 
these appendages by one of its constituent pieces. It serves to support the 


450 THE RESPIRATORY APPARATUS IN MAMMALIA. 


pharynx, and by means of the walls of the latter is attached to the cir- 
cumference of the posterior openings of the nasal cavities. : 

In order to facilitate description, this brief notice of its form, situation, 
general relations, and mode of attachment will be followed by a notice of 
its structure; afterwards, the study of its external and internal surfaces will 
receive attention. . 

Srructurs or THE Larynx.—It comprises in its structure: 1, A carti- 
laginous framework, composed of five pieces; 2, Muscles which move these 
pieces; 3, A mucous membrane spread over the inner surface of the organ ; 
4, Vessels and nerves. i 

1. Cartilayinous framework of the larynz.—In this we find: three single 
median cartilages, the cricoid, thyroid, and epiglottis; and two lateral 
cartilages, the arytenoid. All are movable one upon the other. 

Cricorp Cartitace.—This cartilage, as iis name indicates (xpikos, «tds, 
ke a ring), is exactly like a ring with a bezel looking upwards. Depressed 
on each side, but all the less as the animal has its respiratory apparatus 
well developed, this ring offers two faces, and two borders or circumferences, 
The internal face is smooth and covered by mucous membrane. The external 
face is provided, in the middle of the widened portion forming the bezel with 
a little eminence more or less prominent, elongated in the form of a crest, 
and separating the two posterior crico-arytenoid muscles, to which it gives 
attachment, from each other. On the sides of this bezel are two small, articular, 
concave facets, which correspond to the branches of the thyroid cartilage. 
Nothing remarkable is to be noted for the remainder of the extent of this face. 
The superior cireumference, comprised laterally between the two branches of 
the thyroid cartilage, is hollowed out in the narrow part opposite the bezel, 
where its shows two lateral convex articular facets for articulation with the 
arytenoid cartilages. The inferior circumference responds to the first ring 
of the trachea; it offers a small notch, often double, on the middle of the 
bezel. 

Tayror Carrinace (Oupeds, efSos, like a shield).—This is composed 
of two lateral plates, which have the form of an obliquangular parallelo- 
gram, and are united at their anterior extremity to form a thick constricted 
part which, in Veterinary Anatomy, is named the body of the thyroid. This 
body is smooth on its inferior face, where it is covered by the terminal 
extremity of the subscapulo-hyoideii muscles. On its superior face is 
an obtuse, rounded, and irregular protuberance, on which the epiglottis 
articulates. 

The plates, lateral branches, or ale of the thyroid present two faces, two 
borders, and two extremities. The eaternal face, slightly convex, is eavened 
by the hyo-thyroideus and thyro-pharyngeus muscles. The énternal face 
slightly concave, is covered, near the superior border, by the pharyngeal 
mucous membrane; for the remainder of its extent it responds to the thyro- 
arytenoid and lateral crico-arytenoid muscles. 

The superior border is divided by a small prolongation into two parts: 
an anterior, giving attachment to the thyro-hyoid membrane; the other 
posterior, into which is inserted the pharyngo-staphyleus (palato-pharyngens) 
muscle. This appendix, the great thyroid cornu of Man, forms one of the 
obtuse angles of the parallelogram represented by each lateral plate of the 
thyroid cartilage ; it is united to the extremity of the hyoid cornu - and at 
its base is an opening, or deep notch, through which passes the superior 
laryngeal nerve. The inferior border is also divided into two parts by the 
second obtuse angle of the cartilage: the anterior part forms, with that of 


THE LARYNX. 451 


the opposite plate, a receding angle occupied by the crico-thyroid membrane ; 
the posterior gives attachment to the crico-thyroid muscle. The extremities 
constitute the acute angles of the thyroid plate. The anterior is confounded 
with that of the opposite branch, to form the body of the cartilage. The 
posterior, slightly curved downwards, is terminated by a small, convex 
diarthrodial facet, which articulates with the concave facets of the external 
face of the cricoid cartilage. 

The thyroid cartilage is frequently partially, or even entirely, ossified. 

Ertetorris.—This piece forms a soft and flexible appendix, shaped like 
a sage-leaf; inferiorly, it circumscribes the entrance to the larynx, and 
is bent over it, so as to close it hermetically when the alimentary bolus ‘is 
traversing the pharyngeal vestibule. 
‘ This cartilage has two faces, two lateral borders, a base, and a summit. 
The anterior face is convex from side to side, concave from above to below, 
and covered by the mucous membrane of the pharynx; it gives attachment 
to the hyo-epiglottidean muscle. 

The posterior face shows an inverse configuration, and is covered by the 
lining membrane of the larynx, which is perforated by glandular orifices. 
The borders offer a free portion, which aids in circumscribing the entrance 
to the larynx; as well as an adherent part fixed to the arytenoid cartilage by 
means of a mucous fold, and made irregular by the little cartilaginous bodies 
which are superadded to it. (These are the cuneiform cartilages, or 
cartilages of Wrisberg, placed in the aryteno-epiglottidean fold of mucous 
membrane which extends from the apex of the arytenoid cartilage to the side of 
the epiglottis.) The base is thick, and articulated with the middle part of 
the thyroid ; it gives origin, posteriorly, to two lateral prolongations, which 
pass to the inferior border of the arytenoids, but usually without joining 
these. 

The summit unites the 1ree portion of both borders, and is thrown forwards 
on the upper face of the soft palate (Fig. 174, 9). 

ARYTENOID CaRTILAGES.—These two pieces have been so designated from 
their resemblance, when approximated, to the mouth of a pitcher ¢épvrawa, 
eidus, like a pitcher) They are situated in front of the cricoid, 
above the entrance to the larynx; each affects an irregular quadrilateral 
form, and presents for study two faces and four borders. The internal face 
is smooth, almost flat, and lined by the laryngeal mucous membrane. 
The eaternal face is divided by a ridge into two portions : a superior, covered 
by the arytenoid muscle; and an inferior, giving attachment to the thyro- 
arytenoid and lateral crico-arytenoid muscles. The superior border is concave, 
and joined to that of the opposite cartilage. The inferior border gives 
attachment, posteriorly, to the vocal cord. The anterior border, thick aud 
convex, and covered by the mucous membrane, circumscribes, superiorly 
and laterally, the entrance to the larynx; it is in joining above, with the 
homologous border of the other arytenoid cartilage, that the pitcher-beak 
already mentioned is formed. The posterior border projects into the larynx 
by its inferior portion ; superiorly, this border is very thick, and is hollowed 
by a small articular facet, which responds to the anterior facet of the bezel 
of the cricoid. Above, and to tle outside of this facet, is a very prominent 
tubercle which terminates behind the crest of the external face, and gives 
attachment to the posterior crico-arytenoid muscle. 

ARTICULATIONS OF THE Lanyneuat Cartitaces (Figs, 227, 228)—These 
articulations are of the simplest kind. They are as follows: 

A, The thyroid cartilage is joined to the os hyoides: 1, At the 


452 THE RESPIRATORY APPARATUS IN MAMMALIA. 


extremities of the cornua, by means of a short ligament interposed between 
that extremity and the appendix of the superior border of the thyroid ; 2, 
To the whole extent of the hyoid concavity, by an elastic membrane—the 
thyro-hyoid membrane, attached to the body of the thyroid cartilage and the 
superior border of the lateral plates of that cartilage (Fig. 228, 4). 


SUPERIOR FACE. INFERIOR FACE. 


CARTILAGINOUS PIECES OF THE LARYNX, MAINTAINED IN THEIR NATURAL POSITION 
BY THE ARTICULAR LIGAMENTS. 

u, Cricoid cartilage; 6,6, Arytenoid cartilages; c, Body of the thyroid; c’,c’, Lateral 
plates of the thyroid; d, Epiglottis; e, Body of the hyoid; jf, Trachea.—1, 
Crico-arytenoid articulation; 2, Capsule of the crico-thyroid articulation; 3, 
Crico-thyroid membrane; 4, 'Thyro-hyoid membrane ; 5, Crico-trachealis ligament. 


B. The thyroid cartilage articulates with the cricoid by two small 
arthrodiz, which unite the posterior extremities of the branches of the first 
cartilage with the facets on the external face of the second. A thin external 
capsule incloses this articulation (Fig. 227, 2). These two cartilages are 
also held together by means of a membranous elastic ligament—the erico- 
thyroid membrane, which passes from the angle comprised between the two 
branches of the thyroid to the anterior notch of the ericoid (Fig. 228, 3). 

C. The two arytenoid cartilages are united, at their superior border, by 
the arytenoid muscle and laryngeal mucous membrane. 

D. The latter cartilages are brought into contact with the anterior facets 
of the cricoid bezel, by means of the concave articular surface of their posterior 
border; the result is a small, but very movable, arthrodial joint, inclosed 
by a thin external capsule and by the surrounding muscles (Fig. 227, 1). 

E. These cartilages are also united to the thyroid through the medium of 
the vocal cords. These are two elastic bands which project within the 
larynx, and between them include the triangular space termed the glottis ; 
their internal face is covered by the mucous membrane of the larynx ; the 
thyro-hyoid muscles envelop their external face ; their inferior extremity ig 
fixed into the crico-thyroid membrane, and the angle of the thyroid cartilage ; 


THE LARYNX. 453 


the superior is attached to the inferior border of the arytenoid cartilage, 
towards the angle which separates this from the posterior border. The 
articulation of sounds is principally due to the vibration of these cords. 

F. The epiglottis is fixed by amphiarthrosis to the body of the thyroid 
cartilage, by means of elastic fasciculi mixed with fat, which pass from the 
base of the first to the upper face of the second. It is not rare to find among 
these fasciculi small synovial burse. 

G. The epiglottis is united, laterally, to the inferior border of the 
arytenoids, through the medium of the two mucous folds already noticed, in 
the substance of which are the cartilaginous prolongations annexed to the 
base of this fibro-cartilage. These prolongations circumscribe, anteriorly, 
the ventricles of the larynx, and are sometimes designated the superior vocal 
cords : a name we rarely give them, as they do not merit it. 

H. Finally, the first ring of the trachea is attached to the cricoid 
cartilage by a circular elastic membrane. : 

All of these articulations have neither the same importance nor mobility. 
The kind of movements they permit is easily understood, and they are suf-. 
ficiently indicated in the description of the muscles which execute them. 

It is sufficient here to state, that these movements may either produce 
the shortening or elongation of the larynx, its dilatation or contraction in a 
transverse direction, or the occlusion of its anterior opening. 

2. Muscles of the laryna.— The laryngeal apparatus is elevated or 
depressed with the hyoid bone, which it follows in all its movements. It 
is also moved by proper muscles, which either produceits total displacement, 
or cause the several pieces of its cartilaginous framework to play upon each 
other. Among these muscles there are three extrinsic: the sterno-thyroideus, 
hyo-thyroideus, and the hyo-epiglottideus, The others are intrinsic, or 
attached in their origin and termination to the different pieces of the larynx ; 
they are: the crico-thyroid, posterior crico-arytenoid, lateral crico-arytenoid, 
thyro-arytenoid, and the arytenoideus muscles. All are pairs, except the last 
and the hyo-epiglottideus. 

STERNO-THYROIDEUS.—(See page 198.) 

Hyo-tHyromevs.—This is a wide, triangular muscle formed entirely of 
muscular fasciculi, which originate from the whole extent of the hyoid 
cornu, and terminate on the external face of the thyroid ala; the most 
inferior are longest. This muscle covers the thyroid cartilage and the 
thyro-hyoid membrane. It is covered by the maxillary gland. 

In contracting, this muscle brings the thyroid cartilage within the branches 
of the hyoid bone, and in this way carries the larynx forward and upward. 

Hyo-zrictorripevs.—By this name is designated a small cylindrical 
fasciculus, whose fibres are buried in the middle of a mass of adipose tissue, 
and which extend from the superior face of the body of the hyoid bone to the 
antero-inferior face of the epiglottis. Partly covered by the mucous 
membrane of the pharynx, this muscle concurs in restoring the epiglottis 
to its normal position after the passage of the alimentary bolus. But it is 
also necessary to state that the epiglottis is carried forward more particularly 
by its own proper elasticity, as well as that of the ligamentous fasciculi 
which attach it to the thyroid cartilage. 

Crico-tuyrorEus (Fig. 229, 8).—This small muscle, applied to the 
external side of the cricoid cartilage, is elongated from above to below, 
and composed of strongly tendinous fibres which cross, more or less. the 
general direction of the muscle. They arise from the above-named cartilage, 
and pass to the posterior border of the thyroid plate. 


32 


454 THE RESPIRATORY APPARATUS IN MAMMALIA. 


The crico-thyroideus shortens the larynx, in bringing together the two 
cartilages into which it is inserted. ; 
: PosteR1on Crico-ARYTENOIDEUS (Fig. 
ahaa 229, 7) —This is the most powerful muscle 
‘ in this region. Its fibres are directed for- 
* wards and outwards, and originate from 
the bezel of the cricoid, which they cover, 
and from the median crest of that part. 
They all converge, in becoming more or less 
tendinous, towards the posterior tubercle of 
the arytenoid cartilage, on which they ter- 
minate. Covered by the cesophagus and 
the crico-pharyngeal muscular band, this 
muscle is separated from that of the oppo- 
site side by the median crest of the cricoid 
bezel. 

The posterior crico-arytenoid muscles 
dilate the entrance to the larynx, as well as 
the glottis, in causing the arytenoid car- 
tilages to rotate or swing on the cricoid 
cartilage. and in separating them from one 


POSTERO-LATERAL VIEW OF THE 


LARYNX another by their anterior and inferior bor- 
L, Epiglottis ; 2, Arytenoid cartilages; ders. They act as a lever of the first order. 
3, Thyroid cartilage; 4, Arytenoi- LATERAL ORICO-ARYTENOIDEUS (Fig. 229, 


deus muscle ; 5, Crico-arytenoideus 5), A triangular muscle, smaller than 
pars 6, Thyro-arytenoideus; the preceding, situated between the thyroid 

, Crico-arytenoideus posticus; 8, oe i 

Crico-thyroideus; 9, Ligament be- and arytenoid cartilages, and formed of 
tween the cricoid cartilage and fasciculi longer in front than behind; these 
first ring of trachea, 10; 11, In- oviginate on the side of the anterior border 
soual Ge pee extremities of crico- 6 the cricoid cartilage, and are directed 
yroid cartilages. : se . 
upwards to terminate outside the posterior 
crico-arytenoideus, on the tubercle of the arytenoid cartilage. 

It is a direct antagonist of the last muscle, and, consequently, a con- 
strictor of the larynx. 

THYRO ARYTENOIDEUS (Fig. 229, 6)—Lodged at the inner face of the 
thyroid ala, this muscle comprises two fasciculi, separated by the ventricle 
of the glottis. 

The anterior fasciculus is a long and pale band, originating on the 
internal surface of the ala of the thyroid cartilage, near its receding angle, 
and ascending to the arytenoid cartilage, bending round its external face to 
join, on the median line, the analogous fasciculus from the opposite side, 
mixing its fibres with those of the arytenoideus. By its inner face it covers 
the superior vocal cord and the laryngeal mucous membrane. 

The posterior fasciculus, wider than the anterior, comports itself in a 
somewhat similar manner. It commences from behind the same point, and 
terminates on the external crest of the arytenoid cartilage; but its most 
anterior fibres pass over this crest and join the arytenoid muscle. Its 
internal face corresponds to the vocal cord, and its posterior border is con- 
founded with the fibres of the lateral crico-arytenoideus. 

Sometimes it happens that these fasciculi are not distinct from each 
other, and exist only as a wide muscular band applied against the ventricle 
of the glottis. 

It is surmised that this muscle is a constrictor of the larynx. Its 


THE LARYNX. ‘ 455 


function is particularly marked in phonation, when it modifies the length, 
separation, and tension of the vocal cords. 

AnyTENoIDEUs.— Situated beneath the pharyngeal mucous membrane, 
above the arytenoid cartilages, this, the smallest of the laryngeal muscles, is 
composed of two lateral portions whose fibres arise from a median raphé 
and, diverging, pass to the superior part of the external face of the before- 
mentioned cartilages, where they terminate by becoming inserted into the 
crest dividing that face, and uniting with the thyro-arytenoid muscle. 

The French works on Veterinary Anatomy cite this muscle—we do not 
know why—as a dilator of the larynx. Its position in front of the crico- 
arytenoid cartilages sufficiently indicates that it cannot act otherwise than 
in bringing the two arytenoid cartilages together. And the continuity of 
a large number of its fibres with those of the thyro-arytenoideus, does not 
allow it to have any other action than that of this muscle. 

3. Mucous membrane of the laryna.—This membrane is only a con- 
tinuation of the pharyngeal mucous membrane, which, after covering the 
prominence formed by the opening of the larynx, is folded over the cir- 
cumference of that opening, to be spread on the posterior face of the epi- 
glottis and the internal face of the arytenoid cartilages, to dip into the 
ventricles, pass above the vocal cords, line the inner face of the cricoid 
cartilage, and, finally, to be prolonged into the tracheal tube. Its deep face 
adheres closely to the parts it covers, except in the lateral ventricles. The 
free face is perfectly tense, and is covered with stratified tesselated epi- 
thelium at the epiglottis and vocal cords, but only with ciliated epithelium 
‘elsewhere. 

The glandule of the larynx are racemose, and are numerous on the 
posterior face of the epiglottis, where they are lodged in the minute depres- 
sions of the cartilage; they are also found on the arytenoid cartilages and 
the aryteno-epiglottidean folds. The mucous membrane of the larynx 
possesses an exquisite sensibility, owing to which admission to the air- 
passage is denied to the solid or liquid alimentary particles, which, during 
deglutition, might deviate from their normal course and pass into this 
opening. The slightest touch brings into play this sensibility, and deter- 
mines an energetic reflex excitation of the constrictor muscles of the larynx 
and chest; from this results the almost complete occlusion of the laryngeal 
tube, and a violent cough which expels the substances whose contact has 
occasioned the irritation of the membrane. Everyone has experienced the 
effects of this reflex action, and knows by experience the great sensibility of 
the larynx. 

4, Teese and nerves.—Blood is carried to the larynx by the laryngeal 
arteries, which pass between the cricoid and the posterior border of the 
thyroid cartilages. Their branches spread over the ventrical of the glottis 
and the thyro-arytenoid muscle, to be expended in the substance of the 
muscles and mucous membrane. The terminal ramifications form red 
plexuses on certain parts of the larynx. The veins are satellites of the 
arteries. The lymphatics form a superficial and a submucous network, 

The pneumogastric furnishes the larynx with its principal nerves—the 
superior and inferior laryngeal. The first is distributed to the upper part 
of the organ and to the entrance to the glottis, endowing the mucous 
membrane with that high degree of sensibility that distinguishes it. The 
second is more especially a motor nerve, and supplies all the muscles, 
except the crico-thyroid muscle. A filament of the recurrent nerve is 
distributed in the mucous membrane of the subglottal portion, and to the 


456 THE RESPIRATORY APPARATUS IN MAMMALIA. 


inferior border and inner face of the vocal cords.. The presence of nervous 
filaments, analogous to those of the trachea, in the sub-glottal part of the 
larynx may explain the difference, well known to physiologists, that exists 
between the sensibility of the entrance to the glottis and that of the inferior 
border of the vocal cords. 

ExrernaL Surrace or THE Larynx.—It is divided into four planes: a 
superior, inferior, and two lateral. The superior plane, formed by the ary- 
tenoid and posterior crico-arytenoid muscles, is covered by the pharynx 
and esophagus ; in its anterior moiety, it is directly covered by the pharyn- 
geal mucous membrane. 

The inferior plane presents, from before to behtnd, the thyro-hyoid 
membrane, the body of the thyroid cartilage, the crico-thyroid membrane, the 
inferior part of the cricoidartilage, and the crico-trachealis ligament. There 
is remarked, laterally, the inferior border of the thyro-hyoid muscle. This 
plane corresponds to the scapulo-hyoideal muscles, which entirely cover it. 

The lateral planes exb’bit the external faces of the thyro-hyoid and 
crico-thyroid mascles, that of the cricoid vartilage, and the ale of the 
thyroid. They also show the opening through which passes the superior 
laryngeal nerve; they are related to the crico- and thyro-pharyngeal muscles, 
as well as the maxillary gland. 

InrernaL Surrace or THE Larynx.—This surface is divided into three 
perfectly distinct regions: a middle one, named the glottis ; a superior, called 
the supraglottic portion ; and an inferior, designated the subglottic portion. 

The glottis (rima glottidis) is a narrow space which affects the figure of a 
very elongated isoscelated triangle, its base being uppermost, This irregular 
fissure is comprised between the elastic structures known as the vocal cords, 
It is the narrowest part of the larynx. 

The supraglottic portion, wider than the glottis, but always greatly 
depressed on each side, particularly in the region comprised between the 
arytenoids, presents: 1, The two ventricles of the laryna, lateral excavations, 
dilated at the bottom, and which penetrate between the anterior border of 
the vocal cords and the prolongations of the base of the epiglottis, insinuat- 
ing themselves even between the fasciculi of the thyro-arytenoid muscle 
(in the Ass and Mule the ventricles are proportionately larger than in the 
Horse, and open close to the base of the epiglottis); 2, The subepiglottic 
sinus, a deep depression at the base of the epiglottis, which is provided, in 
the Ass and Mule, with a thin membrane, capable of vibrating; 3 The 
entrance of the larynx, or pharyngeal opening of the cavity, a vast gaping 
aperture of an oval form, circumscribed by the anterior border of the 
arytenoids and the lateral border of the epiglottis, and making a remark- 
able projection at the bottom of the pharyngeal space. 

The subglottic portion of the larynx is the widest of the three: it is 
directly continuous with the internal canal of the trachea. In front ig seen 
the prominence formed by the posterior border of the vocal cords: above 
a diffused and shallow excavation, placed at the point of junction of the 
arytenoid and cricoid cartilages, and which is named the subarytenoid sinus 

Funcrtons.—As a tube intended for the passage of a column of air 
during the act of respiration, the larynx does not give rise to any ver 
interesting physiological considerations. It is, nevertheless, worthy of nal 
that this organ, in imitation of the nostrils, dilates or contracts, accord} 
to the volume of the column of air introduced into, or expelled from 
lungs, and that its paralysis, during rapid movements, causes an se aN 
ent in the respiration which betrays itself in “roaring.” But a physio- 


THE TRACHEA, 457 


logical study of the larynx acquires a real interest when it is examined with 
regard to the articulation of sounds, or as an organ of phonation. This 
study, however, does not come within our province; though what has been 
said concerning the vocal cords will give a summary, but satisfactory, idea 
of the mechanism which presides over this function, and the part the larynx 
lays. 

. Tt may also be added, that nearly all the muscles of the larynx are con- 
cerned in phonation; by modifying the tension and the separation of the 
vocal cords they determine differences in the sounds. One only is concerned 
in respiration; this is the posterior crico-arytenoideus, which is a dilator of 
the glottis. 


2. The Trachea. (Figs. 230, 234.) 


Preparation.—Follow the same procedure as for the dissection of the cesophagus. 


The trachea is a flexible and elastic tube, formed of a series of incom- 
plete cartilaginous rings, which succeed the larynx, and terminate above the 
base of the heart by two divisions, which constitute the bronchi. 

Form.—This tube is cylindrical, and (slightly) flattened on both sides. 
Its inferior face and two borders are regularly rounded, and offer transverse 
grooves, which correspond to the intervals between the constituent pieces of 
the trachea. The superior face, nearly plane, shows the thin and widened 
extremities of these cartilaginous arcs. 

Course.—Leaving the posterior extremity of the larynx, the trachea 
descends backwards to the entrance of the chest, by following the inferior 
border of the neck below'the longus colli muscle. It afterwards becomes 
inflected, superiorly, to pass between the two first ribs, enters the chest in 
traversing the anterior mediastinum, proceeds directly backwards, and finally 
arrives above the left auricle of the heart, to the right of the posterior aorta, 
where the tube presents its terminal bifurcation. 

Relations.—In its cervical portion, the trachea, surrounded by a loose 
and abundant cellular tissue, lies in a kind of muscular envelope which the 
majority of the muscles of this region form around it, and which are: the 
sterno-hyoid and sterno-thyroid, placed in front; the sterno-maxillaries, 
situated at first in front, and afterwards on the sides towards their termina- 
tion; the subscapulo-hyoideii, above and in the middle of the lateral parts ; 
the scalenii, altogether below and at the sides; the longus colli, behind; 
and outside all these muscles, the superficial expansion of the subcutaneous 
muscle of the neck, This envelope is thinnest in front of the middle portion 
of the neck; and this is the place where the operation of tracheotomy 
should be performed. 

The trachea is also in relation, in its cervical portion: 1, With the 
cesophagus, which descends, as we know, at first in the middle of the 
posterior face, then to the left side of the air-tube; 2, With the carotid 
arteries, which pass along both sides of the tube, accompanied by their 
satellite nerves—the pneumogastric, great sympathetic, and recurrent 
nerves. 

After clearing the two first ribs, where it reaches is thoracic portion, 
the trachea responds, superiorly, to the longus colli and the cesophagus ; 
below to the brachial trunks, to the anterior aorta which furnishes them, to 
the anterior vena cava, the cardiac and recurrent nerves, and to the base 
of the heart; laterally, to the inferior cervical ganglia of the great sympa- 
thetic, the vertebral vessels—cervical and dorso-muscular—and to the two 
layers of the anterior mediastinum ; to the right, the vena azygos; to the 


458 THE RESPIRATORY APPARATUS IN MAMMALIA. 


left, the arch of the aorta and the thoracic duct. The latter is sometimes 
carried to the opposite side. ens 

Srructure.—The trachea comprises in its structure: the car eee 
rings which form its base ; the ligaments which unite these rings ; a 
mucous membrane spread over its inner face; a muscular layer, which only 
lines that membrane superiorly ; and vessels and nerves. 


Fig. 230, 


THE RESPIRATORY ORGANS; INFERIOR, OR FRONT VIEW. 

1, Trachea; 2, Jugular vein; 3, Great rectus anticus muscle; 4, Carotid artery; 
5,-Longus colli muscle; 6, Origin of the common carotids; 7, Vertebral artery ; 
8, Section of first rib; 9, Cephalic trunk of right axillary artery; 10, Anterior 
lobe of right lung; 11, Middle, or supplementary lobe of ditto; 12, Posterior 
portion or lobe of ditto; 13, Heart; 14, Cardiac artery ; 15, Ventricular branch 
of cardiac vein; 16, Esophagus. 


Cartilaginous rings of the trachea.—These are about fifty in number, 
and do not form perfect rings, being incomplete on the upper side of the 
trachea. Each is a kind of arc, composed of a cartilaginous plate flattened 
and curved on itself, whose extremities are turned towards each other, and 


THE TRACHEA, 459 


joined in the majority of the rings; they even overlap in some. These 
extremities are thin and wide, and sometimes bifurcate and unite with the 
adjoining rings. 

In the middle part of the trachea, these rings are generally larger than 
at the origin or termination of the tube. The last ring, in serving as a 
transition between the trachea and bronchi, presents a more complicated 
arrangement ; being frequently completed by isolated cartilaginous plates, 
and is always divided by a median spur or bifurcation—directed towards the 
interior of the trachea, into two lateral segments, each of which corresponds 
to a bronchus. 7 

Ligaments.—The rings of the trachea are united at their borders by 
intermediate ligaments, which are composed of elastic tissue, and permit the 
lengthening or shortening of the tube they concur to form. 

Towards the extremities of the arcs, they are confounded with a thin 
cellular layer that unites these extremities. The first cartilage is received by 
its anterior border into the cricoid ring, and joined to it by the wide annular 
ligament mentioned at page 452. Owing to the elasticity of this ligament, 
the two cartilages it binds together can move one within the other, 
like two segments of a telescope, and in this way vary the length of the 
tube. 

Muscular layer—This layer only covers the superior face of the 
trachea; it is formed of pale, rose-coloured, transverse fasciculi, attached 
by their extremities to the internal face of the cartilages. Its action 
undoubtedly diminishes the diameter of the trachea, by contracting the arcs 
composing this cartilaginous tube. (Kélliker has found some longitudinal 
fibres passing across the transverse ones at the posterior part of the trachea. 
Leyh describes longitudinal fibres in the anterior wall of the trachea, 
between the mucous membrane and the cartilaginous rings, and which, ho 
states, diminish the length of the tube.) 

Mucous membrane.—Continuous with that of the larynx, this membrane 
is prolonged, through the medium of the bronchi, and in becoming modified 
in character, into the air-cells. Its free or superficial 
surface is perforated by glandular orifices, and ex- 
hibits longitudinal ridges which are ineffacable by 
distension ; it is lined with ciliated epithelium. Its 
deep face is covered with yellow elastic tissue dis- 
posed in longitudinal fasciculi, and adheres inti- 
mately either to the face of the cartilages and their 
intermediate ligaments, or to the posterior muscular 
layer. 

oat essential characteristic which distinguishes 
this membrane from that lining the larynx, is its CILIATED EPITHELIUM 
slight sensibility. FROM THE TRACHEA, ; 

(The tracheal glands, whose orifices are so nume- 1, oa par as 
rous in the mucous membrane, abound towards the 9 Homogeneous surface 
posterior part of the tube; they are small, ovoid Jayer of the mucous 
bodies, lying between the muscular and fibrous coats. membrane; 3, Round 
Other glands, less in size, are placed between the en, a ra ae ae 
layers of fibrous tissue uniting the cartilages at the aie See a Sa Ane 
sides of the trachea. Their secretion is poured out 
upon the free surface of the mucous membrane, to lubricate and protect it.) 

Vessels and nerves.—The small arteries emanating from the vessels 
in the vicinity of the trachea—as the carotid and the collateral branches 


460 THE RESPIRATORY APPARATUS IN MAMMALIA. 


of the brachial arteries—supply it with blood. Its nerves come from the 


recurrent ; they show small ganglia on their track. 
Funetions.—Except as a tube for the passage of the inspired and expired 


air, the trachea performs no other function. 


3. The Bronchi. (Fig. 232.) 

Preparation.—After removing the lung from the thoracic cavity, it is filled with water 
by fixing the trachea to a water-tap. The bronchi may then be dissected by tearing 
and triturating the pulmonary tissue. 

Each of the two bronchi—the terminal branches of the trachea—resembles 
a tree imbedded in the substance of the lung, and sending out a multitude 
of branches. 


Fig, 232, 


gt, 
inti 


BRONCHIAL TUBE, with its Bronchules and Ultimate Ramifications (natural size). 


Disposition. —At a short distance from their origin i 

the lobes of the lung, and pass backwards and eee a teases Raa 
superior part of the base of the organ, giving off in their course lar e 
collateral branches until they themselves are expended. These ruc 
originate alternately above, within, below, and outwards: and thus extend 
in every direction. The first forms an obtuse angle with the principal 
trunk, and is directed forwards, to ramify in the anterior iobule of th 
lung ; the others are detached at an angle more or less acutc. All _ 
i ee gradually-decreasing branches, which soon become a 
capillary diameter, and finally open int i 

‘ae y Se ae y op 0 the pulmonary air-cells. (See 


THE TRACHEA. 461 


Form.—The bronchial tubes are not flattened like the trachea; a 
transverse section shows them to be regularly cylindrical. 

Volume.—The left bronchus is always smaller than the right, and both 
are much inferior in volume to the aggregate of their respective branches. 

Relations.—Each bronchus enters the pulmonary lobe along with the 
blood-vessels, which with it forms what is called the root of the lung. The 
divisions of this arborescent trunk are accompanied by the bronchial artery, 
vein, and nerves, which ramify in the same manner. 

Near their origin, the bronchi are related to the bronchial glands, above 
which, and to the left side, passes the cesophagus. 

Srructure.—The structure of the bronchial tubes resembles that of the 
trachea ; their walls being formed by a cartilaginous framework, a muscular 
layer, mucous membrane, and vessels and nerves. 

Cartilages of the bronchi.—These only exist in tubes of a certain calibre, 
the minute passages being deprived of them, and having only membranous 
walls. As in the trachea, this framework includes, for each tube, a series 
of transverse rings joined border to border; though these are no longer 
formed of a single arciform piece, but each results from the union of several 
lozenge-shaped pieces whose extremities overlap, and which are united to 
each other, like the cartilaginous segments of the neighbouring rings, by 
means of cellular layers, and also by the membranes spread over their 
internal surface. 

Muscular layer —¥xtended in a very thin continuous layer over the 
entire inner ‘surface of the cartilaginous rings, this layer disappears in the 
smallest bronchial tubes. 

Mucous membrane.—This membrane is dis- 
tinguished from that of the trachea by its great 
sensibility; it alone constitutes the walls of 
the terminal bronchial divisions. (When the 
cartilages terminate, the tubes are wholly mem- 
branous, and the fibrous coat and longitudinal 
elastic fibres are continued into the ultimate 
ramifications of the bronchie.- The muscular 
coat is disposed in the form of a continuous 
layer of annular fibres, and may be traced upon 
the smallest tubes ; it is composed of the un- 
striped variety of muscular fibre.) 

Vessels and nerves.—The vascular and ner- 
vous branches distributed in the tissue of the Poa 6 ee peas 
bronchial tubes come from the satellite vessels  tantes mnJECTED. 
and nerves of these tubes—the hronchial arteries, 
veins, and nerves. ‘lhe lymphatics pass to the bronchial glands. 


DIFFERENTIAL CHARACTERS IN THE AIR-TUBE SUCCEEDING THE NASAL CAVITIES IN OTHER 
THAN SOLIPED ANIMALS, 


Rouminants.—In the Ox, Sheep, and Gort, the interior of the larynx is simpler than in 
the Horse, and the lateral ventricles and vocal cords are almost effaced. The most 
important differences in its various pieces are as follows: 1, The thyroid cartilage has 
no anterior appendices, but is provided, posteriorly, with two considerable prolongations 
that articulate with the cricoid cartilage (it has no excavation between the two wings, 
and is formed by a single piece; its inner face, in the middle, near the lower border, has a 
small fossette to which a round and very salient tuberosity on the external face corres- 
ponds); 2, The upper border of the cricoid is not notched in front (neither is the bezel on 
its lower border) ; 3, The epiglottis is wider, but less acute, than in Sulipeds (Leyh says it 


462 THE RESPIRATORY APPARATUS IN MAMMALIA. 


is less extensive, but thicker); 4, A hyo-epiglottidean muscle bifid at its origin. (There 
is no aryteno-epiglottidean ligament.) vee: 

The trachels of these animals does not offer any important differences. The last ring is 
not so developed as in the Horse, and the tube detaches a supplementary bronchus to a 
lobe of the lung which does not exist in Solipeds. (The rings of the middle portion are 
proportionally nariow, and their extremities meet behind and form a salient ridge.) _ 

Pic.—The larynz of the Pig is remarkable for its great mobility, suspended as it is to 
the hyoid cornua by the base of a very developed epiglottis, rather than by the wings of 
the thyroid cartilage. “There are wide, shallow, lateral ventricles, which have a small 
oblong sinus that ascends between the thyroid cartilage and the mucous membrane. 
These ventricles are not surrounded by the thyro-arytenoideus muscle, which is small 
and undivided; above and outwardly, they are margined by a thick cord—a kind of 
superior vocal cord, considered by Duges as acting with the ventricles to modify the 
deep grunting sounds.”! (Instead of a tuberosity on the external face of the thyroid 
cartilage, there is a median crest, and its inferior border has a small point. The cricoid 
appears to be drawn downwards and backwards, and its lower border is very prominent in 
the middle, and articulates with one or two small cartilaginous plates which have been 
sometimes wrongly described as befonging to the proper cartilages of the larynx. The 
antero-superior angles of the arytenoid cartilages are united to a small cartilaginous 
piece which prolongs them; their external face has a spine, and the internal angles are 
separated: by a small pisiform body called the “ interarticular cartilage.” ; . 

The trachea of this animal resembles that of Ruminants. (It has about thirty rings, 
and has three bronchi.) ; 

Caryivora.—The larynx of the Dog and Cat is very like that of the Horse. In 
proportion, the epiglottis is shorter, wider at the base, and more triangular than in the 
other species; the lateral ventricles are shallow. (There is an interarticular cartilage as 
in the Pig; there is no sub-epiglottidean ventricle, and the vocal cords appear to be 
nearer each other. The trachea has about forty-two rings, whose extremities do not meet ; 


the space between them is less in the Cat than the Dog.) ; 
The larynx and trachea of Man will be compared with that of animals when we come 


to describe the lungs. 


THE THORAX. (Figs, 230, 234.) 


The thorax, also called the thoracic or pectoral cavity, lodges not only 
the lungs, but also the heart and the large vevsels that spring from or 
pass to that organ, with a portion of the cesophagus and trachea, as well 
as nerves, which are as remarkable for their number as their physiological 
importance. 

Situation.—We have seen that the thorax has for its base the bony cage 
formed by the ribs, sternum, and bodies of the dorsal vertebra. Suspended 
beneath the middle portion of the spine, this cage is transformed into a 
closed cavity by the intercostal muscles, which fill the spaces between the 
ribs ; and by the diaphragm, that vast oblique partition which separates the 
thorax from the abdomen. 

Internal conformation.—Considered as a whole, the thoracic cavity 
represents a hollow cone placed horizontally, depressed on each side, and 
particularly in front towards the summit; with its base, formed by the 
diaphragm, cut very obliquely, in consequence of the direction taken by that 
muscle. This obliquity of the diaphragm renders the antero-posterior 
diameter of the cavity much greater above than below; the difference is 
more than double. 

‘The internal surface of this conical cavity may be divided into six 
regions : a superior, inferior, and two lateral planes, a base, a posterior plane, 
and a summit. 

The superior plane presents, on the middle line, a large projection 
resulting from the union of the vertebral bodies ; and, laterally, two deep 
channels—furrows—the vertebro-costal channels. These latter, wider behind 
than before, are formed by the superior extremities of the costal arches ; 


1 Lavocat, ‘ Anatomie des Animaux Domestiques.’ 


THE THORAX. 463 


they lodge the superior border of the pulmonary lobes. The middle 
projection, or ridge, is comprised between these two lobes. Covered in front 
by the posterior extremity of the longus colli, this ridge responds, for the 
remainder of its extent, to the posterior aorta, the thoracic canal, and the 
vena azygos; on its sides are seen the subdorsal branches of the great 
sympathetic nerve. 

The tnferior plane, much shorter than the preceding, is, like it, narrower 
in front than behind ; it has for a base the superior face of the sternum, 
the sternal cartilages, and the triangularis sterni muscle. Posteriorly, 
it gives attachment to the fibrous sac containing the heart. 


Fig, 234, 


THE PECTORAL CAVITY AND MEDIASTINUM, WITH THE COURSE OF THE TRACHEA 
AND CGSOPHAGUS. 


A, Anterior mediastinum; B, Posterior mediastinum; ©, The heart and pericar- 
dium in the middle part of the mediastinum; D, Diaphragm; §, Trachea; F, 
Csophagus, 


The lateral planes, more extensive than the other two, are concave in 
both their diameters. Formed by the internal face of the ribs and the 
deep intercostal muscles, they are in contact with the external face of the 
lung. 

The base, or posterior plane, formed by the convex face of the diaphragm, 
is circumscribed on its exterior contour by the circle of asternal cartilages, 
and by the last rib. In it we see the three openings which traverse the 
diaphragmatic septum. ; 

The summit, or entrance of the thorax, is an_ oval opening, elongated 
vertically, comprised between the two first ribs and the longus colli muscle, 
and which is partly obstructed by an enormous collection of lymphatic 
glands; through this opening passes the trachea, cesophagus, the axillary 
and carotid arteries, the anterior vena cava, and the pneumogastric, great 
sympathetic, inferior laryngeal, and diaphragmatic nerves. 


464 THE RESPIRATORY APPARATUS IN MAMMALIA, 


Such is the thoracic cavity. Like the abdomen, it is provided with a 
serous lining, which remains to be examined. ’ Bae 

Tan Pieurm.—The serous lining of the thorax comprises two distinct 
membranes, designated as the pleuree, constituting two sacs placed one 
against the other in the median plane, and forming a septum named the 
mediastinum, which divides the thoracic cavity into two lateral compart- 
ments. Each pleura, therefore, covers one of the external or costal walls 
of the thorax, and the corresponding moiety of the diaphragm; it is 
afterwards reflected in the vertical and antero-posterior plane of the cavity, 
to concur in the formation of the mediastinum, whence it is carried 
over the lung. This arrangement exhibits the pleura in four portions: 
a costal, diaphragmatic, mediastinal, together representing the parietal layer 
of the membrane, and a pulmonary or visceral portion. 

The costal pleura is applied to the inner face of the ribs and the internal 
intercostal muscles. Strengthened on its adherent face, at each intercostal 
space, by a lamina of yellow elastic tissue, this membrane responds, by 
its free face, to the external plane of the lung, with which it does not, in 
a normal condition, contract any adhesions. It is continued, posteriorly, 
with the diaphragmatic layer; in front, above, and below, with the medias- 
tinal pleura. 

The diuphragmatic pleura adheres somewhat loosely to the fleshy portion 
of the muscle, but the union is more intimate on the aponeurotic portion. 
This layer is contiguous, by its free face, with the base of the lung; it is 
confounded with the mediastinum by the internal part of its periphery. ~. 

The mediastinal pleura is placed, by its adherent face, against that of the 
opposite side, and in this way produces the middle septum which divides 
the thoracic cavity into two portions. Several organs are comprised between 
the two layers of this partition, but most important of all is the heart. In 
Veterinary Anatomy, that part of the septum in front of this organ is named 
the anterior mediastinum ; the appellation of posterior mediastinum being 
reserved for the portion situated behind it. These terms have not the same 
signification as in human anatomy, though they are retained here to prevent 
misunderstanding. 

The anterior mediastinum, thicker than the posterior, but much less 
extensive, contains, superiorly, the trachea, esophagus, the anterior aorta and 
its divisions, the anterior vena cava, thoracic duct, the cardiac, pneumo- 
gastric, recurrent, and diaphragmatic nerves; it also includes the thymus 
gland in the fcetus and young animal. The posterior mediastinum is 
incomparably narrower below than above, in consequence of the oblique 
position of the diaphragm. Its inferior part, always deviated to the left, is 
extremely thin, and perforated by small openings, which give it the 
appearance of fine lace-work. Traversed altogether superiorly by the pos- 
terior aorta, the vena azygos, and the thoracic duct, this mediastinum gives 
passage, a little lower between its layers, to the esophagus, the cesophageal 
branches of the pneumogastric nerves, and to the left diaphragmatic nerve. 
It is these layers of this mediastinum which pass to the lung to constitute 
the pulmonary pleura, in becoming reflected above and below, in a hori- 
zontal line extending from the root of the pulmonary lobe to the anterior 
face of the diaphragm. 

The pulmonary or visceral pleura, a continuation, as has been said, of the 
mediastinal pleura, is in contact, by its free face, with the parietal layer of 
the membrane. Its deep face adheres intimately, in Solipeds, to the proper 
tissue of the lungs. 


THE THORAX. 465 


Independently of these four serous layers, the right pleura furnishes a 
special membranous fold, which arises from the inferior wall of the thoracic 
cavity, and ascends to envelop the posterior vena cava. This fold also 
sustains the right diaphragmatic nerve. 

In order to study the various portions of the pleure collectively, with 
their reciprocal relations, and their connections with the organs contained 
in the thoracic cavity, we will suppose three transverse sections of this 
cavity : one passing behind the heart; the other at the roots of the lungs, 
and dividing the left ventricle of the heart, the third traversing the anterior 
mediastinum, a little in front of the right ventricle. 

If, in the first section (Fig. 235), we take the costal pleura at the point 
a, and follow it up to b, we will see it folded downwards to form the 


Fig. 235. Fig. 236. Fig. 237 


THEORETICAL SECTIONS OF THE THORACIC CAVITY; INTENDED TO SHOW THE 
DISPOSITION OF THE PLEURA. 


mediastinal layer, to be applied to the aorta, c, and the esophagus, d; then 
reflected at ¢ on the lung, f, enveloping every part of the organ ; returning to 
the point e, it leaves the lung, is again reflected to achieve the formation 
of the mediastinal septum, b g, and finally regains the point it started from. 
On the right side, with only a slight variation, it has the same arrangement. 
After being carried from the point a’ to 6’, then to e’, and after enveloping 
the lung, returning to e’, and being reflected in the median plane to the 
point g’, the right pleura leaves the inferior thoracic wall to pass around 
the posterior vena cava, and come back to a’, its point of departure. 

The second section, (represented by Fig. 236) shows the pleura arrived 
at the point b, descending on the root of the lung, ¢, covering that organ 
and returning to c, and reflected on the pericardium, d, to gain the point a. 

In the third section (Fig. 237), we see the parietal pleura, a b, without 
any points of continuity with the visceral pleura, c. It is at the level of 
this section that the lung forms two perfectly free lobes, which are not 
attached to the anterior mediastinum. 

SrructurE.—Like all the serous membranes, the pleure have a free face 
covered by a simple tesselated epithelium ; it is perfectly smooth, always in 
contact with itself, and constantly lubricated by a serous fluid which 
facilitates the gliding of the lung on the parietes of the thoracic cavity. 


, 


466 THE RESPIRATORY APPARATUS IN MAMMALIA. 


The deep face is united to the subjacent parts by connective tissue 
destitute of fat; the adherence of the visceral pleure is most intimate. 

The pleura has plexuses of vessels : one, the subserous, has large meshes ; 
but a second, the subepithelial, has a closer network. f 

The nerves are from the sympathetic and pneumogastric for the pul- 
monary pleura: from the diaphragmatic and intercostal nerves for the 
parietal pleura. 

Foncrions.—The thorax is not a mere receptacle, but, on the contrary, 
performs a very important part in the act of respiration. We know, in fact, 
that it is dilated and contracted by the movements of the diaphragm and the 
ribs (see pp. 142, 248). The lung being applied immediately against the 
thoracic walls, and never at any time separate from them, follows this cavity 
in its movements, dilating in inspiration and contracting in expiration, after 
a certain quantity of the oxygen of the inspired air has been removed and 
replaced by an equivalent amount of carbonic acid. aaa 

The movements of the thorax are, therefore, of capital importance, con- 
stituting, as they do, the initial phenomenon of respiration, and having 
dependent on them all the other acts of this function. 


DIFFERENTIAL CHARACTERS IN THE THORAX OF OTHER THAN SOLIPED ANIMALS, 
In the Ox, the thorax is not so long, particularly in its superior part, as in Solipeds, 
by reason of the slight obliquity of the diaphragm, and of its mode of attachment to the 


ribs. 

The total capacity of this cavity is also certainly inferior to that of the Horse’s chest. 
Tt is the same, though relatively more extensive, in the Sheep, Goat, and Pig; while 
the Dog possesses in this respect an incontestable superiority over Solipeds. It is to be 
noted that all these animuls, without exception, are distinguished from the Horse, Ass, 
and Mule by the conformation of the posterior mediastinum. In them it is not open in 
its lower part, but as solid, thick, and complete there as elsewhere. Therefore it is that 
the consecutive effusion of pleuritis is readily localised in one of the pleural sacs in the 
first-named animals, while this localisation is impossible in the second. (This is an 
important observation, in a patholugical point of view.) 


THE LUNG (oR LUNGs). (Figs. 230, 234.) 


Preparation.—The disposition of the lung in the thoracic cavity is best studied by 
placing the subject in the second position, opening the chest by excision of the ribs, as 
in Fig. 234, and inflating the organ by the trachea. To study its external conformation, 
it should be removed from the cavity, with the heart and large vessels, and inflated as 
before. 


Situation —General disposition.—This essential organ of respiration is a 
spongy viscus, lodged in the thoracic cavity, and divided into two lateral, 
but independent, moieties, each of which occupies one of the two serous sacs 
formed by the plure. It is also described as two pulmonary lobes, or two 
dungs—a right and left, the latter a little less voluminous than the former. 

Form and Relations.—Together, the lungs affect the outline of the 
thoracic cavity; each represents the moicty of a cone, and offers for study: 
an external and internal face, a base and summit, and a superior, inferior, and 
posterior border, 

The external or costal face is convex (and smooth), and moulded to the 
external wall of the thorax. 

The internal, or mediastinal face. forms a vertical plane, separated from 
the opposite lung by the mediastinum. It shows: 1, An inextensive anterior 
part, in contact with the anterior mediastinum; 2, At the level of the heart, 
an excavation in which that organ is lodged; 8, Immediately behind this 
excavation, and a little above it, the root of the lung (hilum-pulmonis), a fasci- 


THE LUNGS. 467 


culus formed by the air-tubes and pulmnary vesse.s in entering the viscus ; 
4, A posterior portion, more extensive than the other two put together, 
corresponding to the posterior mediastinum, and attached to that septum by 
means of a fold developed around the organ, to form the pulmonary pleura ; 
this fold constitutes, posteriorly, a small serous ligament (ligamentum latum 
pulmonis), attached at once to the mediastinum and the posterior face of the 
diaphragm. On this portion of the lung are remarked two antero-posterior 
fissures: one, hollowed near the upper border of the organ, to receive the 
thoracic aorta; the other situated lower, but not so deep, more marked in 
the left than the right, and lodging the esophagus. In the right lung this 
mediastinal face offers a small particular lobule, which is absent in the left. 

The base, or diaphragmatic face of the lung, cut obliquely from above to 
below, and before to behind, is concave, and moulded to the anterior face of 
the diaphragm. On the right lung ig seen the posterior face of the small 
lobule noticed on the inner side, and a deep fissure excavated between it and 
the principal lobe, for the passage of the posterior vena cava. 

The summit of the viscus, situated behind the first rib, presents a kind of 
detached appendix, designated the anterior lobule of the lung. 

The superior border, thick, convex, and rounded, is lodged in the vertebro- 
costal channel or concavity. The inferior, much shorter and thinner, is 
deeply notched at the level of the heart, and more so at the left than the 
right side. The posterior is elliptical, and everywhere circumscribed by the 
face of the diaphragm, which it separates from the costal and mediastinal 
faces. 

Srrucrure.—An external serous envelope, proper fundamental tissue, 
functional and nutrient vessels, lymphatics, and nerves: such are the elements 
which enter into the organisation of the lung. : 

Szrous Envetore.—This is the pleura pulmonalis already described. 
(There has also been described a subserous connective tissue, containing a 
large proportion of elastic fibres; it invests the entire surface of the lung, 
and extends between the lobules.) ; : 

Fonpamentat Tissuz.—Physical characters.—The pulmonary tissue in 
the adult is of a bright rose-colour ; it bas a deeper hue in the foetus which 
has not respired. Although soft, it is yet very strong and resisting, and 
can with difficulty be torn. Its elasticity is remarkable; it concurs in the 
collapse the lng experiences when air is admitted to the pleural sacs. It is 
very light: plunged in water, if healthy, it floats: this specific lightness 
ought to be attributed to the air imprisoned in the pulmonary vesicles. 
This may be proved by what takes place when the lung of a foetus is 
inflated: heavier than water before that operation, it then becomes lighter, 
because, notwithstanding all the manipulation that may be employed to expel 
the air introduced into the pulmonary vesicles, a certain quantity always re- 
mains. On the other hand, the absolute weight of the lung is relatively more 
considerable in the adult than in the foetus, the first representing 1—-30th of 
the total mass of the body, while it is only 1-60th in the second. ; 

A knowledge of these facts may be utilised in determining whether a given 
lung has belonged to an animal which has respired or bas died before birth. 
If the tissue is plunged in water, this test is called hydrostatic pulmonary 
docimacy ; if its relative oe is to be ascertained, it is designated 

imacy by weight. 
coe ‘the Piet eee of the fundamental tissue of the lung; 
i y its anatomical characters. 
~ ee he pulmonary tissue is partitioned into a great 


468 THE RESPIRATORY APPARATUS IN MAMMALIA. 


1 lobules by septa of connective tissue, which 
ee eee Hie rs of ie external serous membrane, 
This segmentation into lobules is a common feature in the organisation of 
the lungs in the mammalia, but it is more readily demonstrated in some than 
others: not very evident in pense and less so in the Carnivora, it is well 

in Ruminants and Pachyderms. i 
wa yee ea of these Icbules resembles, in a striking manner, that 
of the salivary lobules. Hach receives a small bronchial tube (lobular 
bronchial tube), which is prolonged into the lobule by several short terminal 
branches, in which open a certain number of elementary vesicles. In 
comparing, for the moment, the lung to a gland, it will be seen that this 
organ should be ranged in the category of racemose glands. ; 

To demonstrate the vesicular structure of the lung, it may be inflated 
and dried, and sections afterwards made to show the pulmonary vesicles. 
But this procedure has the inconvenience of unduly extending the vesicles, 
and thinning, and even destroying, their walls. A better method is the 
following: leave the lung in the intact thoracic cavity ; by the jugular vein, 
pour into”the right side of the heart an injection of very hot tallow, 
employing a certain amount of force to propel it from the pulmonary artery 
into the veins; when this injection has cooled, open the thoracic cavity, and 
take out the lungs. These, being impregnated with solidified fat, do not 
collapse on contact with the air, and sections made in different directions 
then exhibit innumerable perfectly-circular porosities, which are the open 
pulmonary vesicles. ; 

In this way it is easy to demonstrate the presence of the air-cells ; but, 
in order to conveniently study their arrangement, it is necessary to take a 
cast of them by means of a solidifiable material introduced by the bronchii, 
and afterwards destroyed by the maceration of the pulmonary tissue. The 
Darcet alloy, employed in this manner, often gives very good results. It is 
then found that the pulmonary vesicles form, in each lobule, saccular 
dilatations or culs-de-sac, from 1-70th to 1-200th of an inch in diameter, 

grouped around the infundibuli, of which they are only 
diverticuli; these infundibuli communicate with the 
terminal bronchule of the lobule through the medium of 
a narrow central cavity, into which they all open. Such 
are the principal histologic details relative to this im- 
portant point in the history of the lungs; and: it must 
necessarily be followed by a notice of the structure of 
the pulmonary vesicles (or air-cells), 

The pulmonary vesicles comprise, in the organisation 
of their walls: a proper membrane; epithelium ; and 
capillary vessels. 

‘PLAN OF A PUL- 1. The proper membrane is thin and homogeneous: it 
MONARY LoBULE. contains the nuclei of connective tissue and elastic fibres, 
a, Bronchule termi- and its external face is applied to that of the neighbour- 


nating in a slight ing vesicles; its internal face is lined by e ithelium. 
dilatation, b; c, Air- sd 2 y ep 


ats, or infandibuli: 2. The epithelium is simply tesselated, and is com- 
d, Air or pulmonary Posed of extremely thin cells. It is continuous through- 
vesicles. out the vesicles, and with that of the terminal bronchule. 


In a properly-prepared section, the polyhedral cells 
lining the latter can be seen changing gradually and rapidly into 
Squamous epithelium in the cavity of the lobule, at the entrance to the 
infundibult. 


THE LUNGS 469 


(The Praeger con Fa the air or pulmonary vesicles 
measure from 1— o 1- th of inch in di : ; 
00h ie Leads ce of an inch in diameter, and from 


inch in thickness. Between the 
vesicles is a trabecular tissue, 
mainly composed of yellow elas- 
tic with a few muscular fibres, 
some of which are united with 
the lining membrane to strength- 
en it, especially around the 
apertures of communication be- 
tween the adjoining air-cells.) 

3. Capillary vessels ramify 
in the walls of the vesicles, and 
even project on their inner 
face. 

(The capillary plexuses are 
so arranged between the two 
layers forming the walls of two 
adjacent cells, as to expose one 
of their surfaces to each, in order 
to secure the influence of the 
air upon them. These networks 
are so close, that the diameter 
of the meshes is scarcely so 
great as that of the capillaries N\ 


which inclose them.) AIR-CELLS OF LUNG, WITH INTERVENING TISSUES. 


VesseLs—The lung is a a, Epithelium ; 6, Elastic trabecule ; c, Membranous 
very vascular organ. The nu- wall, with fine elastic fibres. 


merous ramilications it receives 
divide into two orders—the functional and the nutritive vessels. 

Functional vessels of the lung. We know that the blood rvturns from all 
parts of the body by the veins, after 
losing, along with its bright red 
colour, the properties which render 
it fit to maintain the vitality of the 
tissues. It thus arrives at the right 
side of the heart, whence it is pro- 
pelled into the lung, there to be 
regenerated by mediate contact with 
the air. It is the pulmonary artery 
which conveys this fluid into the 
parenchyma of the organ. and by 
the pulmonary veins it is carried 
back to the heart. The artery is 
at first divided into two branches, 
which ramify and finally terminate 
in dense capillary plexuses upon the |. .xocmmnr OF THE CAPILLARIES AROUND 
walls of the air-cells. The veins, THE. ATHAGEETS: 
innumerable and attenuated at their 
origin, like the arterial capillaries, terminate in from four to eight principal 
trunks, which open into the left auricle of the heart. 

These two orders of vessels, which necessarily participate in the physiolo: 

33 


\ 


470 THE RESPIRATORY APPARATUS IN MAMMALIA. 


gical functions of the lung, like the vena porte with the liver, are very 
properly distinguished from the other arteries or veins of the organ by the 
designation of functional vessels. But though they are S0 named, it must 
not be inferred that they are excluded from all participation in the acts of 
nutrition, It is now admitted by competent authorities that the blood 
of these vessels concurs to sustain vitality in the tissue of the lung, in 
common with the nutritive fluid carried by the arteries and veins now to be 
described. Pane 

Nutrient vessels—By this name is designated the divisions of the 
bronchial arteries and veins, whose terminal ramifications anastomose with 
the capillaries of the pulmonary vessels at the ultimate bronchules. 

Lymphatics—These vessels are divided into superficial and deep. The 
first form a network beneath the pleura, the second exist in large numbers 
around the lobules. They mix together, and terminate in the bronchial 
glands. (Lymphatics of very small size have been described as commencing 
in the alveolar spaces, on leaving which they gain a proper coat or internal 
tunic, and are subsequently supplied with valves.) 

Nerves.—The nervous branches supplied to the tissue of the lung come 
from the same source as those of the bronchial tubes—the pneumogastric and 
great sympathetic nerves. Their ramifications accompany the pulmonary 
vessels and bronchie, and they show small ganglia on their course. 

Functions.—To know that the lung is the seat of the absorption of 
oxygen and the expulsion of carbonic acid from the nutritive fluid— 
phenomena accompanied by the transformation of the dark into red-coloured 
blood, and probably of several other metamorphoses yet doubtful or un- 
known —is the only authentic fact necessary to remember with regard to the 
functions of this organ. It must be added that the subtle molecular opera- 
tions from which all these phenomena result, take place in the lung by the 
mediate contact of the atmosphere introduced into the air-cells during 
inspiration, with the blood traversing the walls of these cells, With the 
intimate mechanism of these molecular actions we have nothing to do here, 
however 

Devetorment.—Although the lung is in a state of inactivity in the 
foetus, yet it is one of the organs éarly developed. During the whole period 
of foetal existence, its lobular texture is much better defined than in the 
adult, and it then appears to be formed exactly like a racemose gland. 
Sections of it prepared for microscopical examination distinctly show the 
vesicles and their arrangement. We have already made known the differ- 
ences in colour and density which distinguish the pulmonary tissue of the 
foetus and that of the adult. It only remains to repeat what has been said 
as tc the slight vascularity of the first, and to note that the blood of the 
pulmonary artery passes almost entirely into the posterior aorta by the 
arterial canal (or ductus arteriosus), 


DIFFERENTIAL CHARACTERS IN THE LUNGS OF OTHER THAN SOLIPED ANIMALS. 


The lungs of the Ox, Sheep, and Goat are remarkable for the distinctness with which 
the lobules are defined. They are, in fact, separated by thick layers of cellular tissue 
continuous with the internal face of the viscerai pleura. - These thick septa are rather 
the interlobular ramifications sent off from the subserous envelope.) Dietrichs, who was 
the first to draw attention to this peculiarity in the larger Ruminants, has justly remarked 
that it perfectly explains the altogether special characters of the lesions of pueumonia in 
these animals. 4 

The general figure of the lungs of Ruminants does not differ from that obser i 
the Horse ; the left lung, however, is divided into two lobes, and the right eas 


— 


THE LUNGS. 471 


a ie an anterior, is curved in front of the heart. The annexed figure shows 
In the Pig, the lungs comport themselves li i 
In the By aa Cat, re ae sa like those of Ruminants. 
marked fissure in either lung toward: i 
heart, which causes that Sipe to be oe ee 
completely enveloped by pulmonary tissue. 
The left lung has three lobes, and the right 
four, separated from one another by deep 
furrows, which are generally prolonged to 
the root. ‘The lobules are small, very close, 
and the pulmonary tissue is exceedingly 
compact, (The pulmonary vesicles are pro- 
portionately larger than in Ruminants.) 


COMPARISON OF THE LARYNX, TRACHEA, AND 
LUNGS OF MAN WITH THOSE OF ANIMALS, 


1. Larynz.—The human larynx is pro- 
portionally shorter and wider than that of 
animals, The principal cartilages are those 
which have been already studied; but there 
are, besides, small cartilaginous bodies, to 
which special names have been given: these 
are the cartilages of Santorini and of Wris- 
berg. The facets on the cricoid for articu- 
lation with the thyroid are placed on the 
small cornua detached from the external face 
of the cartilage. ‘The thyroid is wide, and 
protects the anterior face of the larynx; the 
angle formed by the ale, which is more 
marked in the male than the female, is very 
prominent, and is named the pomum Adami. 
The epiglottis is short, broad in its middle, 
and rounded at its summit, something like 
that of the Carnivora. The muscles are the LUNG OF THE SHEEP; INFERIOR VIEW. 
same in number and disposition as in these 1, Right lung; 2, Left lung; 3, Trachea; 
animals: but there is distinguished an 4, Heart; 5, Carotid arteries; 6, Posterior 
oblique arytenoideus—a fasciculus of the vena cava. 
arytenoid, which crosses its fellow to form 
an X in passing from the upper Fi 
border of one arytenoid cartilage ig. 242. 
to the lower border of the other. 


1, Right ventricle; 2, Left ventricle; 
3, Right auricle; 4, Left auricle ; 
5, Pulmonary artery; 6, Right 
pulmonary artery; 7, Left pul- 
monary artery; 8, Ligament of 
ductus arteriosus; 9, Arch of 
aorta; 10, Superior vena cava; 
11, Arteria innominata ; 12, Right 
subclavian vein, with the artery 
behind it; 13, Right common 
carotid artery and vein; 14, Left 
vena innominata; 15, Left caro- 
tid artery and vein; 16, Left 
subclavian vein and artery; 17, 
Trachea; 18, Right bronchus; 
19, Left bronchus; 20, 20, Pul- 
monary veins; 21, Superior lobe 
of right lung; 22, Middle lobe; 
23, Inferior lobe; 24, Superior 
lobe of left lung; 25, Inferior 
lobe. HUMAN LUNGS AND HEART; FRONT VIEW. 


472 THE RESPIRATORY APPARATUS IN MAMMALIA. 


i i id si i hat of 
h larynx has no subepiglottic or subarytenoid sinus like j 
Brreaete ane itt ited intern, or Morgagni’s, ventricles that uscend a little to the outside 


i 1 cords. : 
ig ve Geis. Bronee sthete is little difference to be remarked in these. The 


i our inches long and about one inch wide, and is composed of about 
hee Gutaea Sal which are closely united, as in animals. It is situated in the 
median plane, in the upper part of the neck, where it is embraced by the lobes of the 
thyroid gland; at its entrance into the chest it deviates slightly to the right. T he two 
short canals between its lower extremity and the lungs are the bronchi ; the right 
bronchus is the shortest and widest, and Las an almost horizontal direction, entering 
the right lung at the fourth dorsal vertebra; the left is longer and less voluminous, and 
reaches the corresponding lung at the fifth vertebra. ‘ ; ; ; 

4. Iungs.—The lungs weigh about forty ounces. As in all animals, the right is 
more voluminous than the left, and is divided into three lobes; the latter has only two. 
The inferior vena cava is not surrounded by pulmonary tissue; the principal lobes are 
partitioned into lobules, which are visible on the surface, and on the limits of which 
are deposited, only in the adult, a notable quantity of pigmentary matter, that gives the 
lungs the appearance of a chess-board. ‘There is nothing to be said respecting their 
internal conformation and structure. 


THE GLANDIFORM BODIES CONNECTED WITH THR RESPIRATORY APPARATUS. 
1. Thyroid Body (or Gland). 


The thyroid gland, or body, is composed of two oval lobes of a reddish- 
brown colour, and'is situated close to, and behind, the larynx, beside the two 
first rings of the trachea. : 

These two lobes, distinguished as right and left, appear at first sight to 
be perfectly independent ; but a less superficial examination shows them to 
be united by an intermediate portion (the isthmus), which passes across the 
anterior face of the trachea. 

Each lobe of the thyroid body corresponds, inwardly, to that tube; 
outwardly, it is covered by the subscapulo-hyoid muscle. 

Srructure.—The thyroid body 
is composed of a fibrous envelope, 
and a proper tissue or parenchyma, 

The fibrous envelope is composed 
of slender, but strong connective 
tissue; it sends from its inner 
face a large number of thin nu- 
cleated lamine that intersect each 
other, forming spaces in which the 
proper tissue is contained. 

The parenchyma is divided into 
lobules, whose presence is mani- 
fested on the surface of the organ. 
They are composed of vesicles, the 
shape and contents of which vary 
considerably with age and situa- 
tion. In the foetus, or very young 
animal, they are round or ellip- 
tical, and constituted by a thin 


GROUP OF GLAND VESICLES FROM THE THYROID 


BODY OF A YOUNG SUBJECT. amorphous membrane, lined by 
a, Connective tissue; , Basement membrane of Polygonal cells with a large nu- 
tle vesicles; c, Epithelial cells, cleus, and containing a granular 


: . fluid. In the adult, these vesicles 
are deformed, and, after being distended, several are confounded together ; 


THE THYROID AND THYMUS GLANDS. 473 


the epithelium is less evident and uniform, the contents have become brown 
and hold granules and nuclei in suspension, and, finally, often assume the 
character of colloid matter in becoming viscous and of a yellow tint. 

Vessels and nerves.—The thyroid body is remarkable for the relatively 
enormous volume of its blood-vessels; the arteries chiefly come from the 
thyro-laryngeal branch—a collateral of the primitive (or common) carotid 
(they form plexuses on the vesicle walls); the veins pass to the jugular. 
Its nervous filaments are from the first and second cervical pairs, with twigs 
from the sympathetic, It has an abundance of lymphatics. 

Fonctions.—The thyroid is one of the organs classed, in a somewhat 
arbitrary manner, in tke ill-defined category of ductless or blood-vascular 
glands. Our knowledge of its use is as uncertain at present as in the 
infancy of anatomical science. So that we can say nothing more on this 
subject, except that the successive or simultaneous excision of the two 
lobes in the Horse do not appear to cause any derangement in the animal’s 
health. 

Neither does the study of its development throw any light on its func- 
tions. It is certainly relatively larger in the foetus and young animals than 
in adults; but the difference is not sufficiently marked to authorize us in 
drawing any physiological inductions therefrom, 


2. Thymus Gland. 


The thymus gland is a transitory organ, only present in the fostus and 
very young animals, and in its nature closely resembling the thyroid gland. 
Like it, it is divided into two lateral lobes placed close together in the 
middle line, under the lower face of the trachea, partly without and partly 
within the chest, between the two layers of the anterior mediastinum. It is 
elongated from before to behind, of a whitish colour, and uneven or 
lobulated on its surface like a salivary gland. 

Strructure.—It owes its uneven aspect to its lobular structure, for it is 
effectively reduced by dissection into a multitude of granular lobules, in the 
centre of which are found vesicular cavities containing a lactescent fluid. 
.The vesicles are larger than those of the thyroid gland, and have for their 
walls a very thin layer of delicate connective tissue; they are filled by a 
mass of nuclei. A wide, irregular cavity has been described as existing in the 
middle of each lobe (reservoir of the thymus), and evidently communicating 
with the vesicles of the lobules, as it contains a notable quantity of the same 
milky fluid. This cavity is certainly not present at all periods ; for I have 
not met with it in two young foetuses now lying before me as I write. But 
without dwelling on this particular point, we may notice enormous bleod- 
vessels, lymphatics, and nerves, as complementary elements in the organisa- 
tion of the gland, whose structure is very similar to that of the proper 
glands, though differing from them in an important feature—the absence of 
-an excretory duct. 

Nothing positive is known as to the functions of the thymus gland; 
it is only certain that they are exclusively related to the development of the 
young animal, as it generally disappears some months after birth, though it 
is sometimes found in adult, and even in very aged animals. 

(Its functions are supposed to be the same as, or analogous to, those of the 
thyroid. Structurally, the organ may be said to consist of an assemblage of 
hollow glandular lobules joined together by connective tissue, each having 
a cavity which opens into a central canal that has no duct, and being lined 


474 THE RESPIRATORY APPARATUS. 


externally by an almost amorphous membrane which divides it into “ acini,” 
or gland-granules. Separate acini are often observed on the main canal. 
Each lobule is made up of its greyish-white, soft parenchyma composed of 
free nuclei and small cells, and has a minutely-distributed capillary plexus: 


Fig. 245. 


PORTION OF THYMUS COURSE AND TERMINATION OF THE ABSORBENT 


GLAND OF CALF, DUCTS OF THE THYMUS GLAND OF A CALF. 
UNFOLDED. 1, Internal jugular veins; 2, Superior vena cava; 
a, Main canal; 6, 3, Thoracic duct, dividing into two branches, 
Glandular lobules; that again unite before terminating in the root 
c, Isolated gland of the left jugular vein; 4, The two thymic 
granules seated on ducts: that on the left side opening into the 
the main canal. thoracic duct, and the right into the root of 


the corresponding jugular vein. 


The lymphatics terminate in two large ducts that commence at the upper 
extremities of the lobes of the gland, the thymic ducts, and pass down- 


ward to terminate at the junction of the jugular and axillary veins at each 
side.) 


DIFFERENTIAL CHARACTERS IN THE GLANDIFORM BODIES ANNEXED TO THE RESPIRATORY 
APPARATUS IN OTHER THAN SOLIPED ANIMALS. 


The thyroid body, peculiar to Mammals, is more developed in Ruminants, Pachy- 
derms, and the Carnivora, than in Solipeds. The two lobes are closer together, and 
often joined by the thyroid isthmus. In the Pig this is very marked, and the gland 
well merits its name, as it forms a veritable shield in front of the trachea, towards the 
lower part of the neck. : 


THE RESPIRATORY APPARATUS IN BIRDS. 475 


The thymus gland in young Ruminants is more voluminous than i i 
' h a u 1 an in the Foal, and is 
i higher up in the cervical region. (1n the Carnivora, it is divided into two branches : 

ut it is small, and completely lodged between the layers of the anterior mediastinum. 
It persists for some time after birtu, and seldom disappears in less than a year.) 


r 
.COMPARISON OF THE GLANDIFORM BODIES ANNEXED TO THE RESPIRATORY APPARATUS IN 
MAN WITH THOSE OF ANIMALS. 


In Man the two lobes of the thyroid body are connected by an isthmus, and the upper 
extremity of the lobe is carried up to the side of the thyroid cartilage. The isthmus 
often gives origin to a process of variable length and size, called the pyraméd or third 
lobe, which is generally situated to the left A muscle is sometimes found connected 
with the isthmus or pyramid, and is attached above to the body of the os hyoides or to 
the thyroid cartilage; it has been named the levator glandula thyroide. 

The thymus gland is composed of two lobes, a right and left, only joined by 
connective tissue, and having no structural communication. There is a cervical and a 
thoracic portion, the whole extending from the fourth rib as high as the thyroid gland. 
After birth it continues to enlarge wntil the end of the second year, and begins to 
diminish between the eighth and twelfth years.) : : 


CHAPTER II. 


THE RESPIRATORY APPARATUS IN BIRDS. 


THE organs composing the respiratory apparatus of birds, offer conditions altogether 
special, and which have a remarkable influence on the mechanism of respiration. The 
modifications imposed upon the performance of this function will be indicated after an 
examination of the tubular apparatus, which carries the air into the /ung, and the 
characters of that organ, as well as the air reservoirs (or sacs; annexed to it. 

Tue 'TuBULAR APPARATUS.— When this apparatus is compared with that of Mammals, 
no very sensible differences are observed—at least in domesticated birds. 

The nostrils, pierced through the upper mandible of the beak, have no membranous 
and movable wings, and the nasal foss open into the pharynx by a long, narrow sl.t 
behind the bony palate. A transverse row of small, lorny papille, placed at the 
anterior extremity of this aperture, represents the soft palate. 

The larynx has no epiglottis: a defect which does not prevent the complete occlusion 
of the glottis during the passage of food, as the laryngeal orifice is circumscribed by two 
lateral lips which then meet in the most exact manner. 

The trachea is composed of complete cartilaginous rings, and not simple ares. In 
song-birds, the last ring is a second larynx, tl.e real organ which produces the modulated 
voice of these creatures; it only exists in a rudimentary condition in poultry, however, 
the last tracheal piece in them being slightly dilated, and showing at the origin of the 
bronchi a membranous layer, from whose vibration results cries or crowing. Other 
singular peculiarities belonging to the trachea deserve to be described here, if they 
were not the exclusive appanage of some wild fowl. We are content to mention the 
presence of the bony drum found at the terminal extremity of the trachea in the 
whistling duck, and the remarkable convolutions that tube forms in the breast-bone of 
Cranes and male Swans. 

The bronchi only show incomplete rings in their structure. They pass into the lung 
by its inferior face, towards the union of its anterior «nd two posterior thirds. When 
describing this organ, their mode of ramification, and the nature of the relations they 
bear to its proper tissue will be considered. : ; : 

Tue Lunes.—M. Sappey, in the remarkable memoir published by him in 1847, has 
described them as follows: ‘The lungs of birds are situated on the lateral parts of the 
vertebre of the back—which separate them, and lying against the arch of the thoracic 
cavity, to which they adhere. Their rosy colour resembles that presented by these 
organs in Man and the Mammalia during uterine life, and for some time after birth; 
they are especially remarkable for their restricted volume, which scarcely represents an 
eighth part of the thoracic capacity. Their configuration 1s far removed irom the 
conical form of the lungs in M ammals, and the oval form of the same organs in reptiles ; 
they are semi-elliptical, and if the two lungs of a Mammal were opposed base to base, 


\ 


476 THE RESPIRATORY APPARATUS, 


their likeness would be produced; to obtain the same results with the lungs of a reptile, it 
is necessary to divide them in the direction of their great axis. 

“This shape enables us to distinguish in the lungs ofa bird, two faces—-n convex 
and concave; two borders—an external and internal; and iwo extremities—an anterior 
and posterior. 

“The convex face, also named the dorsal, costul, or superior face, corresponds inwardly 
to the dorsal vertebra, and outwardly to the ribs and the intercostal muscles; it is 
exactly moulded on the walls of the thorax, and as the ribs protrude on the internal face 
uf these walls, it results that this surface of the lungs is marked by transverse furrows 
which give it a lobulated aspect ; but these lobes or lobules show nothing common with 
those composing the same organ in Mammalia. In that class, the existence of lobes and 
lobules ig an established tact, and is caused by the dichotomous division of the bronchi ; 
in birds, it is only apparent, and depends on the dimiuished thickness of the lung at 
each rib, This face, quite imperforate, is covered bya thin layer of cellular tissue, which 
unites it to the sides of the thorax. 

“The plane or concave face looks downwards; it is in relation with the diaphragm, 
which separates it from the viscera of the thorax, and from the abdomen ; from this arises 
its other names of inferior, diaphragmatic, or visceral face. Like the preceding, it is 
covered by avery fine layer of cellular tissue, which forms adhesions with the diaphragm ; 
but it differs from it by the orifices it presents, which are five in number, and constitute 
veritable canals, through which tho air passes and repasses incessantly to and from the 
sacs, and from them to the lungs. 

“The borders are parallel to the axis of the body; the internal is rectilinear, thick 
and rounded; the external, convex, thin, and sharp. : 

“Of the two extremities, the anterior, which is very acute, occupies the receding 
angle formed by the spine within and the first rib without; the posterior, more consider- 
able, has a rounded furm.” 

In regard to structure, that which distinguishes the lung of birds from that of 
Mammals is the mode of distribution and termination of the air-passages. In Mammals, 
the large bronchial tubes, placed in the centre of the lung, send their divisions towards 
the surface of the organ, or in a centrifugal manner; in birds they are disposed at the 
periphery of the lung, and direct their diff rent ramifications towards the centre, or in a 
centripetal fashion. On the other hand, the arboreal division of the bronchi in Mammals 
is replaced in birds by penniform ramificution. Lastly. the terminal bronchial tubes 
instead of opening into a series of closed vesicles, as in Mammals, anastomose with one 
pee in Pe a as fi form an inextricable xrial network. 

P . Sappey hus further developed the knowledge acquired on this i ing j 

in the following terms: “ Arrived in the Danny tissue, it Gils INonDbial pean 
pe as ate, gralually capa toy following its primary direction, and in this way 
gains the posterior extremity o e orgau, where i yma ing i 

sna ee y gau, where it terminates by opening into the 

“This erifying trunk, therefore presents two very distinct i 
pulmonary, the other ictia- pulmonary: The first "Aeate the aes : ae igi 
bronchi of Mammalia; it is membranous internally, elastic and fibrous eiuee Were 
iene eens with cartilaginous rings, which embrace three-fourths of its cireum- 
ed ae by mucous membrane characterised by its pale rose-colour, and its 

“The second differs from the preceding in its dimensi 
Owing to its dilatation at its antiamige to the eng, its dagen ee Mie cane 
and may be stated as three to two of the extra-pulmonary portion. Beyond this nia “ 
meut, it diminishes in capacity by the emission of branches, losin its eyli ari al ‘pn 
i se that ofa cone with a truncated summit. Its walls are almost eu fitele destitute 
: eo slo rings, so that the origin of the principal conduits is constantly 

“ The air-passages arising from this common trunk to i 
the lung, are remarkable for their uniformity in numbir Le ne 
offer in all classes of birds. They are generally twelve, and their ori in i "th aa Hd 
buted : four arise from the internal wall of the trunk by a series of ae ve apes 
after the other ; seven are detached from its external wall by a second settee y r a ries 
also disposed in rows; the twelfth springs from its inferior wall, and inomnedlia 1 a3 nda 
downwards and outwards to open into the posterior diaphragmatic reservoir, hich coe 
be oes as a terminal branch of the principal trunk. Junge 
ae e canals which have their origin from these linear seri i 
internal and external walls of the aici g trunk, show this pened a upeeinon hae 
from their commencement they pass towards the periphery of the lung, that they divide 


THE RESPIRATORY APPARATUS IN BIRDS. 477 


and subdivide at this periphery, that they cover it with their ramifications, and do not 
rae is i to enter the pulmonary parenchyma until their volume has been considerably 
reduced. 

“The conduits leaving the orifices situated on the inner wall of the exrial trunk 
ramify on the inferior face of the lung; those proceeding from the echeloned orifices on 
the outer wall are distributed on the opposite face. The first constitute the diaphrag- 
matic, and the second the costal bronchial tubes. 

“The diaphragmatic bronchial tubes, four in number, like the orifices from which 
they originate, may be distinguished by the numerical names of first, second, third, and 
fourth, in proceeding from before to behind; the first bronchus is carried forward 
horizontally, the second transversely inwards, the third obliquely inwards and back- 
wards, and the fourth directly backwards. In view of their divergent direction, which 
resembles a fan, they might be designated as the anterior, internal, and posterior 
diaphragmatic bronchial tubes ; and to distinguish the last two, the more voluminous 
one, which is directed backwards and inwards, might be named the great posterior 
diaphragmatic bronchus, and the one passing directly backwards the small posterior 
diaphragmatic bronchus. = 

“The costal bronchial tubes, seven in number, may be also designated as first, second, 
third, etc., in proceeding from before to behind; parallel at their origin, and in juxta- 
position, like the pipes of an organ, they separate after following a certain course, and 
affect, by their divergence, the fan-shape already observed in the disposition of the 
diaphragmatic bronchi. Like the latter, they become peripheral from their origin, and 
spread out from centre to circumference. The first is carried very obliquely upwards 
and inwards, to attain the anterior extremity of the lung; all the branches it furnishes 
arise from its anterior wall, and those which are nearest its origin are inflected to gain 
the external border of the organ; the succeeding tubes are directed forwards, the others 
forwards and inwards; while all proceed to meet those coming from the anterior 
diaphragmatic bronchus, though they do not anastomose with them. Coming in contact, 
they plunge into the pulmonary tissue in such a way, that, when a lung is inflated, we 
observe between these two orders of ramifications a very manifest groove, which is 
perfectly distinct from those due to the protrusion of the ribs; this groove evidently 
represents, though in a rudimentary state, the interlobular fissures in the lungs of 
quadrupeds. 

“The second, third, and fourth costal bronchie follow a transverse course, and 
ramify on the inner border of the lung; the fifth and sixth incline towards the 
posterior extremity of the organ; the seventh, very small, reaches this extremity and 
disappears. 

“The first costal bronchus is the most voluminous: those succeeding it gradually 
diminish in calibre. At their point of emergence they adhere closely to the ribs; all are 
imperforate, and this feature essentially distinguishes them from those occupying the 
opposite face. 

“ The canaliculi furnished by these principal tubes do not sensibly differ in calibre 
in the various bronchi: all offer an equal diameter, and their dimensions are only in 
relation to the total volume of the lung. All are detached at a right angle from the 
pulmonary wall of each bronchus, and descend perpendicularly into the lung; and all, 
from their origin to their termination, preserve the same diameter, and consequently the 
same cylindrical form. If this mode of ramification be compared with that observed 
in Mammals, it will be seen to differ considerably. In the latter class, the air-passages 
affect the dichotomous division proper to the arteries and veins, the result of which is a 
series of arboreal canals decreasing in capacity. In birds only two kinds of conduits are 
observed, the primitive and peripheral, disposed around a generating axis like the barbs 
of a feather on their stalk; and the secondary and parenchymatous, implanted on the 
pulmonary walls of the first, like the hairs of a brush on their common base. These 
two arrangements are evidently similar, except that the peripheral canals, which are few, 
only form a single row on each side ; while the canaliculi, very numerous, form several, 
Consequently, it may be said that the mode of ramification proper to Mammalia is essen- 
tially dichotomous, and that observed in birds essentially penniform. : 

“Independently of the canaliculi arising from the pulmonary walls of the diaphragm- 
atic and costal bronchie, there are others which spring directly from the generative 
trunk: but in their dimensions, direction, form, and general disposition, they do not 
differ from the preceding. , ‘ : 

“ How do these canals terminate? Notwithstanding the importance of this question, 
it has been generally neglected ; though its solution alone may furnish the analogies and 
differences necessary for the parallel which has always been attempted to be established 
between the lungs of birds and those of other vertebrates. Our special researches on this 


478 THE RESPIRATORY APPARATUS. 


point nave led us to the conclusion that all the canaliculi open into one another, and 
by this anastomosis constitute an extricable plexus whose various parts communicate 
with each other.” AA ; 

Finally, it may be mentioned that “ the walls of the pulmonary canaliculi, examined 
microscopically, appear to be covered internally with irregular septa which circumscribe 
the areol, and give them a cellular aspect.’ F . 

Tue Arr-sacs.!'—* In birds, the pulmonary mucous membrane is continued, at the 
level of the orifices in the lung, into the utriculiform cavities which are developed 
between the walls of the thorax and the abdomen on the one side, and the thoracic and 
abdominal viscera on the other. These air-reservoirs exist in all the vertebrata of the 
second class. In all, they are situated ut the periphery of the viscera in the trunk, in 
such a manner that Carus has justly observed that the lungs of birds inclose all the 
other viscera: so that when they are distended by the entrance of air, they generally 
depress these viscera by pushing them towards the median plane. In all, they are 
independent of each other, and freely communicate either with the lung by a single 
aperture, or with the bones by oue or more openings. Lastly, in all they are nine in 
number. 

“These reservoirs are’ the thoracic sac, situated at the anterior part of the thorax - 
two cervical reservoirs, situated at the base of the neck; two anterior diaphragmatic 
reservoirs, placed between the two diaphragms; two posterior diaphragmatic reservoirs, 
also between these two diaphragms, but behind the preceding and, lastly, two 
abdominal reservoirs, placed against the superior wall of the abdomen. Of these nine 
reservoirs, the first only is single and symmetrical; the others are pairs, and similarly 
arranged on each side of the median plane. 

“The thoracic and cervical reservuirs are situated beneath, and in front of, the lungs; 
the abdominal reservoirs lie behind these organs, and the four diaphragmatic sacs at 
their inferior part and between the preceding; henre the denomination of middle 
reservoirs sometimes applied to the latter, in opposition to the first, which are named the 
anterior reservoirs, ancl to the second, called the posterior reservoirs.” 

ExtTERNAL CONFORMATION OF THE ResErvorrs.—l. Thoracic reservoir (Fig. 246, 2).— 
“Tt is situated above the clavicles and the inter-clavicular space, in the cavity of the 
thorax, which it extends beyond on each side to the roots of the wings, around the 
articulation of the shoulder. It is related with : above, the trachea and cesophagus on 
the riddle plane, the lungs and the origin of the cervical reservoirs on the lateral parts ; 
below, with the sternum, the clavicles, and the interclavicular aponeurosis; behind, 
with the heart and anterior diaphragiratic reservoirs, beneath which it is prolonged by 
forming on each a long point ; in front, with the integuments of the neck, which it raises 
into a hemisphere in Palmipeds, but which is angularly depressed in other classes; on 
the sides, with the sternal ribs, the two clavicles, and the membrane uniting them. 

“The prolongations which arise from the lateral parts of these reservoirs, and cross 
the walls of the thorax to pass around the articulation of the shoulder, are three in 
number, and may be distinguished into inferior or subpectoral, superior or subscapular, 
and middle or humeral. 

“The subpectoral prolongation (Fig. 246, d) issues from the thoracic reservoir by an 
orifice situated behind the posterior clavicle, and passes beneath the tendon of the great 
pectoral muscle, where it spreads out as a lenticular cavity. The relations it contracts 
with that muscle are remarkable: in birds, still more than in Man and a great number 
of quadrupeds, the tendon of the great pectoral is furmed of two parts. one direct, the 
other reflected ; it is between thes two portions that this small air-sac is insinuated, and 
where it forms a very firm connection with them; the effect of which is, that at the 
moment the great pectoral muscle contracts, it dilates the subjacent cell and draws into 
it a greater quantity of air. 

“The subscapular and humeral prolongation communicate with the principal reservoir 
by a common opening placed behind the small adductor muscle of the humerus. After 
leaving this orifice, the subscapular sac spreads under the scapular and subscapular 
muscle, which it separates from the ribs and corresponding intercostal muscles ; it is 
developed more particularly in a longitudinal direction. i 

* The humeral prolongation occupies the axilla ; it is smaller than the preceding, of a 
pyramidal form, and opens by its summit into an infundibular fossa, which leads to the 
canal of the humerus. 

“The thoracic reservoir differs from all the others by the extremely numerous 


1 What is said relating to these air-sacs is taken from the Memoir of M — 
‘Recherches Sur l’Appareil Respiratoire des Oiseaux,’ Paris, 1847. eres 


THE RESPIRATORY APPARATUS IN BIRDS. 479 


membranous folds which partition .ts cavity. The membrane forming it bei i 

on itself, every organ traversing the phorae becomes the cause of is aa 
imprisoned ; and as the thoracic cavity is traversed by the trachea and the cesophagus, the 
muscles which move the inferior larynx, and the arteries and veins, it will be understood 
how this reservoir should become irregular in consequence of these various partitions 
and also why the other erial sacs situated between the viscera and the walls of the 
eh or the simple contiguous surfaces, should preserve their regular and proper 

“The thoracic reservoir communicates with the lungs i i i 
Sa on the external side of the embouchure of each cee eels ged i a 
hina erent inspiration, by the contraction of the two first fusciculi of the pulmonary 

2. Cervical reservoirs (Fig. 246, 1,1).—“ They are situated i 
and the inferior part of the neck and anterior earh of the lung; ie ak 
from the neighbouring parts, they resemble two cones, whose rounded base looks 
fore ao ie pediculated summit is directed backwards. 

uperiorly, these reservoirs lie against the cervical muscles; inferi o 
pond to the air-sac of the thorax, from which they are ancient aes 
esophagus, the pneumogastric nerves, and the jugular veins. Inwardly, they are in 
juxtaposition, and consequently form a median septum which includes in its substance 
the two common carotid arteries. Outwardly, they are related to the origin of the 
cervical nerves, to each of which they furnish a small sheath, and with the vertebral 
artery which they surround, but do not contain in their cavity, as well as with a 
subcutaneous muscle and the skin. By their summits, they communicate with the 
anterior diaphragmatic bronchus; and by their base they send out a prolongation which 
conducts the air into all the vertebrae of the neck and back, into all the vertebral ribs 
and, finally, into the spinal canal. : 

“Tn their cervical portion, these prolongations present themselves in the form of two 
canals extending from the base of the cervical reservoirs to the base of the cranium 
where they terminate; parallel and contiguous to the vertebral arteries, like them 
they are lodged in the canals excavated in the substance of the transverse processes. 

“From their external part arises, at the six last cervical vertebre, as many diverticuli 
which, lying against each other, pass from each side in the muscles of the neck. sur- 
rounded by a common fibrous envelope, and apparently form a kind of canal at the 
inferior part of this region; when, however, this fibrous membrane is removed, it 
becomes easy to isolate them. and it is then seen that they are completely independent 
and resemble small cornua. Highly developed in Palmipeds, they are only present in a 
rudimentary state in the other classes. 

“On the internal side of these conduits, we see, at the level of each vertebra, one or 

more orifices by which the air enters their interior; and at the intervertebral foramina 
another orifice, which allows it to pass into the spinal canal, From the communication 
established by these orifices between the respiratory apparatus and the spinal canal, it 
follows that in birds the cervical region is traversed by three atmospherical currents— 
two lateral or intertransverse, parallel to the vertebral arteries; the third median or 
interspinal, parallel to the spinal cord. 
_ “Just as the medullary tissue is replaced by air in the bones of birds, so might it be 
imagined that the sub-arachnoidean fluid was also replaced by air around their spinal 
cord ; and observation justifies the correctness of this prevision. The dura mater, whose 
capacity is so superior to the volume of the marrow in Mammals, exactly measures the 
volume of that organ in birds; so that there does not exist between the fibrous and 
nervous surfaces any space for an accumulation of liquid ; this anatomical fact is 
sufficient to demonstrate the absence of sub-arachnoidean fluid in birds. In denying the 
existence of this fluid, it ought to be added that in this class of vertebrata, as in the 
preceding, the spinal prolongation is covered by a triple envelope ; that in each, between 
the pia mater and dura mater, is found a thin transparent membrane, which is lubri- 
cated by a serous fiuid; but here this fluid does not collect, it only moistens the 
arachnoid membrane. 

“ Considered in their dorsal portion, the prolongations springing from the cervical 
reservoirs offer an entirely different arrangement to that already noticed. The inter- 
spinal current, having entered the thorax, terminates by passing into the first dorsal 
vertebra; after coursing through every part of this vertebra, it escapes by a lateral 
orifive into a small sac situated between the two first ribs, at the origin of the first dorsal 
nerve; from this sac, it passes into the second vertebra by an opening placed on its 
antero-lateral part, then it flows back from this into a new air-sac developed between 
the second and third ribs; and passing in the same manner into the third vertebra to 


480 


THE RESPIRATORY APPARATUS. 


sweep through a third intercostal sac, it arrives nearer and nearer the last dorsal 


vertebra. In their dorsal portion, 


GENERAL VIEW OF THE AIR RESERVOIRS OF THE 
DUCK, OPENED INFERIORLY; ALSO THEIR RELA- 
TIONS WITH THE PRINCIPAL VISCERA OF THE 
TRUNK, 


1, 1, Anterior extremity of the cervical reservoirs ; 
2, Thoracic reservoir; 3, Anterior diaphragmatic 
reservoir; 4, Posterior ditto; 5, Abdominal reser- 
voir.—a, Membrane forming the anterior dia- 
phragmatic reservoir; b, Membrane forming the 
posterior ditto.—6, Section of the thoraco-abdomi- 
nal diaphragm.—d, Subpectoral prolongation of 
the thoracic reservoir; e, Pericardium; f, f, 
Liver; g, Gizzard; A, Intestines; m, Heart; 
n, n, Section of the great pectoral muscle above 
its insertion into the humerus; o, Anterior 
clavicle; p, Posterior clavicle of the right side 
cut and turned outwards——From MM, Sappey’s 
work, 


the prolongations emanating from the cervical 


reservoirs thus form two currents, 
though these are constituted alter- 
nately by the vertebre and the small 
air-sacs placed on their lateral aspect. 
At the same time that these sacs 
receive the air from the vertebre pre- 
ceding them, and transmit it to those 
which follow, they communicate it to 
all the vertebral ribs. 

“Tn no order of birds do the erial 
currents leaving the cervical reser- 
voirs communicate with those which 
circulate in the cranium. Liquids 
injected either by the erial portion 
of the vertebral canal or the lateral 
prolongations of the neck, never enter 
the bones of that cavity. Thinking 
that the injection might perhaps 
penetrate if passed in the opposite 
direction, we have perforated the 
bones of the cranium, and to the 
aperture have adapted the extremity 
ofa steel syringe filled with mercury ; 
but the metal did not reach the erial 
prolongations of the neck. From this 
double experiment, we concluded 
that the cranial bones have no com- 
munication with the respiratory appa- 
ratus.” 

3. Anterior diaphragmatic reser- 
voirs (Fig. 246, 3).—‘‘ Placed be- 
tween the two diaphragms, they cor- 
respond : in front, to the thoracic 
reservoirs, against which they stand; 
behind, to the posterior diaphragm- 
atic reservoirs; outwardly, to the 
ribs and intercostal muscles; in- 
wardly, to the thoraco-abdominal 
diaphragm and cesophagus; below, 
to the most distant part of the tho- 
racic reservoir; above, to the pul- 
monary diaphragm, which separates 
them from the corresponding lung. 
These air-sacs communicate with the 
lungs by a circular opening, which 
originates from the great posterior 
diaphragmatic bronchus; there is: 
often a second opening of communi- 
cation beyond the embouchure of the 
trunk ; this reservoir is the only one 
which receives air from the lung by 
a double orifice.” " 

4. Posterior diaphragmatic reser- 
voirs (Fig. 246, 4).—“ Oval-shaped 
like the preceding, and situated like 
them in the interval which separates 
the two diaphragms, these air-sacs 
are in contact, by their anterior part, 
with the anterior diaphragmatic re- 
servoirs, with which they form a ver- 
tical and transverse septum. Some- 
times this septum is carried a little 


more forward, and then the anterior reservoir is smaller; this is most frequent in 


THE RESPIRATORY APPARATUS IN BIRDS. 481 


Palmipeds. At other times it inclines backwards, and the anterior reservoir 1s larger ; 
this arrangement is peculiar to the Gallinacw. And, lastly, this partition divides the 
intercepted space between the diaphragms into two equal cavities; rapacious birds offer 
numerous examples of this. , 

“Behind, these reservoirs stand against the abJomin i r 

separated by the thoraco-abdominal diaphragm ‘ ieee Lae Hpac | vba 
d the lateral parts of the st > ab h : ave ai i 

an parts e sternum; above, to the pulmonary diaphragm; inwards, 

eo eer diaphragm ; outwards, to the vertebral ribs and intercostal 

“A parabolic opening, situated in the middle part of the external border of the lung, 
or a little more behind, establishes their communication with that organ This orifice, 
which is remarkable for its great dimensions, occupies the extremity of a voluminous 
bronchial tube which follows the direction of the generating trunk, and in such a manner 
rt ee soe ate! to pass directly tuwards the posterior diapliragmatic reservoir, 

canal. 

5. Abdominal reservoirs (Fig. 246, 5).—* The two air-sacs situated in the abdumen 
present themselves, when inflated, as two enormous bladders, the capacity of each 
differing but little from the volume of the trunk. Situated between the superior 
and lateral parietes of the abdomen on one side, and the abdominil viscera on tue 
ae cannot be dilated without driving the intestinal mass downwards and 
inwards. 

“Their anterior extremity, continuous with the lung, is somewhat inflected to pass 
under the fibrous arch extending from the spine to the pelvis. 

“ Their posterior extremity, dilated and voluminous. responds to the cloaca. Out- 
wardly, they adhere by cellular tissue to the thoraco-abdominal diaphragm, the parietes 
of the abdomen, and those of the pelvis. Inwardly, they are in contact with tle intes- 
tinal mass and the testicles or ovaries. Below and in front, they rest on a fibrous 
septum, which in all birds divides the abdomin ‘l cavity into two smaller cavities: one 
anterior, which represents the abdomen and lodges the liver, the other posterior, which 
represents the pelvis and contains the stomach and intestines. ‘Chis fibrous septun: is ex-, 
tremely remarkable in large birds, particularly the Ostrich, in which it has been described. 
by Perrault as a transverse diaphragm ; it is insertea into the entire cireumference of the 
pelvic bones, and sustains the stomach as well as the intestinal tube. Below and 
behind, the abdominal reservoirs lie on the intestines. Above, these sacs cover the 
inferior face of the kidneys, and there furnish three prolongations: 1, A suprarenal 
prolongation ; 2, ‘I'wo femoral prolongations. 

“The suprarenal prolongation leaves the principal reservoir at the postero-external 
part of the kidneys; from thence it passes obliquely upwards and forwards, to spread 
over the superior surface of the kidney, which it depresses when the abdominal sac is 
inflated. Arrived at the internal border of the kidneys, these prolongations are intro- 
duced between the transverse processes of the sacral vertebre, and ascend from behind 
forwards to the height of the two first dorsal vertebre, forming two triangular canals 
situated above the sacrum, in the sacral channels, and separated from one another by a 
series of corresponding spinous processes. The suprarenal prolongations are not 
present in all birds; they are particularly observed in the Gallinace and diurnal 
rapacious birds. In some Palmipeds, the Swan for example, they are equally developed ; 
in the Ostrich, they are replaced by the supraspinal canals. ; 

“The femoral prolongations are two in number—an anterior small and a posterior 
farge; they arise from the abdominal reservoir at the cotyloid cavities, and leave the 
pelvis in traversing the bony opening through which the crural vessels pass ; after clear- 
ing the limits of these cavities, they spread around the coxo-femoral articulation, and 
terminate in a cecum in the majority of birds. In diurnal birds of prey, they commu- 
nicate with the femoral canal by an orifice situated at the anterior part of the great 
trochanter. These prolongations, very developed in the Ostrich, also open in 1b into the 
femoral cavity ; it is not without surprise that we see this arrangement, which is peculiar 
to birds remarkable for their rapidity and power of flight, also present in those to which 
mrial locomotion has been entirely denied. The abdominal reservoirs communicate with 

. the lung by an orifice situated beneath the fibrous arch of the diaphragm, and disposed 
like the rose of a watering-can.” an 

COMMUNICATION OF THE RESERVOIRS WITH THE Bonrs.—‘ The communications of the 
respiratory apparatus with the skeleton in birds are extremely numerous, Wo will 
successively examine those belonging to each reservoir. ; ae 

“The bones which receive air from the thoracic reservoir are: 1, The anterior clavicle, 
which is perforated at its two extremities; 2, The posterior clavicles, which are also 
perforated a little below their scapular extremity 3, The sternum which presents two 


482 THE RESPIRATORY APPARATUS. 


series of openings—the middle ones that conduct the air into the sternal ridge, and the 
lateral ones, very small, six to eight in number, corresponding to the intercostal spaces; 
4, The scapule, which offer one or more apertures at their anterior extremity, and recelve 
the air for the subscapular prolongation; 5, The humerus, which obtains the air for 
the humeral prolongation by a fossa situated at the inferior and internal part of its 
articular head ; 6, The sternal ribs, which allow the atmosphere to penetrate by small 
openings at their inferior extremities. To sum up, eight bones, without reckoning the 
sternal ribs, whose number varies, receive the air which fills them from the thoracic 
reservoir. 

“The cervical reservoirs conduct the air: 1, To all the cervical vertebre ; 2, To all the 
dorsal vertebre ; 3, To all the vertebral ribs. The vertebre of the neck are erated in 
their anterior part by the currents which accompany the vertebral artery, and in their 
posterior part by the interspinal current. The tirst obtain entrance to the anterior 
segment by one or more orifices made in the inner wall of the intertransverse canals; 
the median current penetrates the posterior segment by two orifices, a right and left, 
situated on the inner and medullary wall of that segment. The first vertebra of the 
back is provided with air in the same manner, by the middle and lateral currents of the 
neck. This air, after passing through the first vertebra, leaves by its lateral parts, to 
enter a small sac; from this it goes into the superior part of the second vertebra, escapes 
from this by its lower portion, to be received into a lateral sac, and so on to the last dorsal 
vertebra. These sacsalso supply the vertebral ribs with air, which enters them by very 
small apertures situated at their spinal extremity. 

“The diaphragmatic reservoirs have no bony communications. The abdominal 
reservoirs supply: 1, The sacrum; 2, The coccygeal vertebre ; 3, The iliac bones; 4, The 
femurs. The air traversing the sacrum, coccyx, and ileum, comes directly from the supra- 
renal prolongations, and that filling the femoral cavity from the femoral prolongations, 
In this enumeration of the communications between the skeleton and the respiratory 
apparatus, we have taken as a type the most erated skeleton: that of diurnal birds of 
prey, like the eagle, kite, hawk, etc.; the bones which communicaty with the air-sacg 
are not so numerous in the other classes. In this respect, they may be ranged in three 
categories: 1, Those which are eriferous in all classes; 2, Those in certain classes only; 
3, And those which are not so in any class. The bones always erated are the cervical 
and dorsal vertebra, the sternum, and we may add the humerus, though it is not so in 
the Ostrich. Those erated in some classes only are: the furculum, clavicles, scapule. 
vertebral and sternal ribs, the sacrum, coccyx, and femurs. And the bones which are 
never wrated are those of the fore-arm and hand, the leg and foot.” 

; STRUCTURE OF THE RESERVOIRS.—The walls of these cavities are essentially formed by a 
thin cellulo-serous membrane, strengthened in some places by an external envelope of 
elastic fibrous tissue. Long, thin blood-vessels are distributed to the substance of these 
walls; they do not belong to the pulmonary, but to the general circulation, the arteries 
being derived from the aorta, and the veins opening directly or indirectly into the vene 
cava. No lymphatics have been found in the air-saca. 

Mecuanism or ResprraTion 1n Brirps.—The anatomical arrangement descriled 
above differs in so many respects from that existing in Mammals, that it ought to brin 
about important modifications in the mechanism of respiration. It does not pr bs 
within our scope to write the history of these modifications; but we cannot disperse 
with indicating, in a summary way, their principal characters, in order to make knowm 
ae See manner the signification of the special organisation this apparatus offers in . 

We remark, in the first place, that the slizht mobility of rtebral ri 
adhesion of the lung to their inner face, only allows fe As oeh Gece Nae 
viscus during inspiration. And the entrance of air into the pulmonary tissue is not 
due to this dilatation; it is due to the dilatation of the diaphragmatic reservoirs: the 
position of these effectively admits of their expansion, by the play of the inferior otk the 
superior ribs. The air is then drawn into their cavity after traversing the larger 
bronchial tubes which open into them, and also after passing across a certain re fon of 
the capillary network formed by the canaliculi, where it comes into mediate Ene t 
with the blood, and is submitted to the necessary transformations. The at; } oe 
therefore, arrives in the diaphragmatic sacs partly pure d par : ee 

M 2 sean sacs partly pure and partly altered by its contact 
with the blood. During expiration, it again resumes the course it followed it 
introduction, traverses a second time the lung, and is thus respired once m : et re 
ie is ae the body. It is, therefore, obvious that the hematosic fousibest 
and eepianek, ed in the lung take place during the two acts of respiration—inspiration 


In studying the part that the other reservoirs play in this function, M. Sappey has 


THE RESPIRATORY APPARATUS IN BIRDS. 483 


been able to prove that they act as antagonists to the first, by contracting during inspira- 
tion and expanding in expiration. No doubt, at the time of the contraction of the middle 
reservoirs, a small quantity of the air they contain is driven back into the anterior and 
posterior sacs in passing across the lung; and without doubt, also, these latter give a part 
of their contents to the diaphragmatic sacs at the moment of the expansion which draws 
the air into these reservoirs. M. Sappey has also noted that these contents are always 
formed of entirely vitiated air, while the air of the middle reservoirs has only been 
partially respired. 

It is necessary to add that the functions of the air-sacs do not cease here ; for it has 
been demonstrated that they exercise a very marked influence: 1, On locomotion, by 
diminishing the weight of the body, and, by their position, rendering equilibrium more 
stable ; 2, On the voice, the extent and power of which they augment. 


BOOK IV. 


Uninary APPARATUS. 


Tus apparatus, though simple, yet plays a very important part in the 
animal economy, as it is charged with the duty of eliminating from the blood, 
along with the superfluous water and other accessory substances, the excre- 
mentitial azotised products resulting from the exercise of the vital functions. 
These products we find in the urine—the liquid secreted by the kidneys, and 
which is carried by the ureters into a special reservoir, the bladder, where it 
accumulates, and whence it is expelled from the body by the urethral canal, at 
periods more or less distant, according to the requirements of the animal. 

The kidneys, the essential organs of urinary depuration, will be first 
studied; then the excretory apparatus; and, finally, a brief notice will be 
given of the suprarenal capsules—small appendicular bodies annexed to the 
kidneys, and whose function is not yet determined. 

Preparation.—Place the animal in the first position, and remove one of the posterior 
limbs. Take out the intestines, adopting the precautions indicated at page 385. Saw 
through the pelvic symphysis, as weli as the neck of the ilium on the side opposite the 
remaining abdominal member, removing the coxal portion between these sections. The 
pelvic cavity being now opened, the urinary apparatus is exposed, and to complete the pre- 
paration it is necessary to: 1, Remove the peritoneum, to show that the urinary appara- 
tus is situated external to that membrane; 2, Free the ureters anl kidneys from the 
cellulo-adipose tissue surrounding them, but retaining the vessels of the latter. and 
leaving undisturbed their relations with the pancreas and suprarenal capsules; 3, Inflate 
the bladder, and dissect its neck, taking care to preserve the orbicular peritoneal fold. 
which envelops its anterior cul-de-sac. 

In the male, the inflation of the bladder is very simple, and requires no directions. 
In the female, however, it is requisite first to close the mcatuy urinarius, which is ac- 
complished by drawing its two lips towards the entrance to the vulva, by means of two 
chain-hooks, passing two pins through their mucous membrane, and tying a lizatme 
behind th: se; the bladder is then inflate.l by the ureter. 

Independently of this dissection in situ, it is advisable to examine the urinary 
apparatus when isolated, and laid arranged upon a table, as in Fig. 247. We can tihen 
study : 1, By dissection, the structure of the kidneys and arrangement of the pelvis 
renalis; 2, The mode of termination of the ureters; 3, The interior of the bladder. 

\ 
1. The Kidneys. (Figs. 182, 247.) 


Stiuation—These are two glandular organs situated in the abdominal 
cavity, to the right and left of the sublumbar region, lying against the 
great psoas muscles, and maintained in that position: 1, By an envelope 
of cellulo-adipose tissue; 2, By the peritoneum, which passes beneath them : 
3, By the pressure of the digestive organs contained in the abdominal cavity. 

Their situation is not absolutely alike, for the right comes forward to 
beneath the two last ribs, while the left scarcely reaches beyond the eighteenth 
rib. The latter is therefore more posterior than the former. 

External conformation—Studied externally, the kidneys present a special 
form, which often serves asa term of comparison, and resembles more or less 
that of a haricot bean, or the heart on a playing card. The latter con- 
figuration is most frequently noticed in the right kidney, the left being 
generally like the first. 


THE KIDNEYS. 485 


Flattened on both sides, the kidneys show two perfectly smooth faces, 
the inferior of which always exhibits a variable number of furrows which 


Fig. 247. 


A, Left kidney; B, Right kid- 
ney; a, b, Ureters; ©, ©, 
Supra-renal capsules; D, 
Bladder; &£, E, Testicles,; 
e, Head of the epididymus ; 
e', Tail of the epididymus , 
F, Deferent canal; G, Pel- 
vic dilatation of the defe- 
rent canal; H, Left vesicula 
seminales; the right has 
been removed, along with 
the deferent canal of the 
same side, to show the in- 
sertion of tbe ureters into 
the bladder; 1, Prostate; 
5, Cowper’s glands; «, 
Membranous, or intra-pel- 
vic portion of the urethral 
canal; L, Its bulbous por- 
tion; M, Cavernous body ot 
the penis; m, m, Its roots ; 
N, Head of the penis.—1, 

SUPERIOR AND GENERAL VIEW OF THE GENITO- Abdominal aorta; 2, 2, Ar- 
URINARY APPARATUS IN THE MALE, WITH Tue teries (renal) giving off the 
ARTES: principal capsular artery, 

3, Spermatic artery, 4, 

Common origin of the umbilical and arteries of the bulb; 5, Umbilical artery 6, 

Its vesical branch; 7, Internal artery of the bulb; 8, Its vesico-prostatic branch, 


34 


486 THE URINARY APPARATUS. 


lodge the arteries; the right kidney has always a special furrow for the 
ureter. Each kidney has a circumference divisible into three borders, only 
the internal of which offers a certain interest. This is deeply notched, to 
form the fissure or hilus of the kidney, which lodges the vessels and nerves 
of the organ, as well as the origin of its excretory canal, : : 

Weight.—The kidneys vary much in weight in individuals. The right 
is always more voluminous and heavy than the left, its average weight 
being 27 ounces, while that of the last is 25 ounces. 

Relations.—The relations of these two glands with the neighbouring 
parts ought to be particularly examined. The right kidney corresponds, by 
its upper face, to the great psoas muscle, the muscular portion of the 
diaphragm, and to the last, or even the second-last rib. Its inferior face, 
incompletely covered by peritoneum, adheres, for the greater part of its 
extent, either to the pancreas and supra-renal capsule, or to the base of the 
cecum, by means of a loose and abundant cellular tissue. The internal 
border is in contact with the posterior vena cava and the small psoas 
muscle; the anterior, with the base of the right lobe of the liver and the 
lobule of Spigel (Jobus Spigeléi), through the medium of the peritoneum ; 
the posterior border is enveloped in peritoneum. The left kidney affects, by 
its superior face, the same connections as the right, except in its relation 
with the second last rib. Its inferior face is almost entirely covered by 
peritoneum, and responds, in front and inwardly, to the supra-renal capsule. 
The internal border is margined by the aorta; the anterior touches the base 
of the spleen and the left extremity of the pancreas; the posterior is, like 
the inferior face, in contact with the serous membrane of the abdominal 
cavity. 

Internal conformation.—If a horizontal section is made of the kidney, it 
will be found to possess a cavity called the renal pelvis, into which the urine 
secreted by the gland flows, and at which the ureter commences. Placed in 
the middle of the kidney, near the hilus, the pelvis is elongated from before 
to behind, and depressed from above to below. Within it is remarked a 
wide infundibulum, the origin of the ureter (the sinus-renalis). Opposite to 
this funnel-shaped space is a very prominent crest that runs along the whole 
length of the external side of the pelvis, and on which are noticed the 
orifices of the uriniferous tubes ; these, by pressing the tissue of the kidney 
with the fingers, can be made to pour out the urine accumulated in them. 
The renal cavity forms some very small diverticuli opposite the infundibulum, 
the largest of which, situated before and behind the latter, are named the 
arms of the pelvis. 

This cavity is lined by a transversely plicated mucous membrane, 
continuous with that of the ureter, and is covered with the epithelium of the 
uriniferous tubes which open on the border of the crest. 

Srructure.—The kidneys present for study in their structure: 1, An 
enveloping tunic ; 2, Their proper tissue ; 38, A cavity named the renal pelvis, 
into which the urine secreted in the glandular tissue flows, and which serves 
as the origin of the ureter. 

1. Envetopine Tunto.—This is a fibrous membrane, intimately united 
to the proper substance of the kidney, into which it sends a multitude of 
prolongations, and is folded around the blood-vessels in such a manner as to 
form sheaths, which enter with them into the organ. (Some authors— 
among them Leyh—describe, in addition to this capsula propria, a thin layer 


formed by the condensed areolar matrix of the kidney, from which it can be 
easily torn.) 


THE KIDNEYS. 487 


Prorrr Tissvz.—The glandular tissue of the kidneys (areola parench 
or matrix) has, externally, a reddish-brown colour, mee or ie pith le 
different individuals. It is dense and friable, and easily torn when deprived 
of its fibrous capsule. Its substance is not everywhere homogeneous: very 
dark-coloured externally, where it forms the cortical layer, it becomes 
whiter around the pelvis, where it consitutes the medullary layer ; where the 
latter comes in contact with the former, and sometimes even near the pelvis 
it assumes a tint like that of wine. 

‘These two portions are not well defined, but penetrate each other 
reciprocally, so as to compose, at their point of junction, irregular festoons, 
very readily perceived in a horizontal section of the kidney (Fig. 248), 

The cortical is also distinguished from the medullary substance by its 
granular aspect, and the presence of minute, reddish spheres, readily visible 
to the naked eye, and named Malpighian corpuscles ; while the medullary 
substance appears composed of radiating fibres. 


Fig. 248. 


HORIZONTAL LONGITUDINAL SECTION OF THE HORSE’S KIDNEY. 
a, Cortical (or vascular) portion; 6, Medullary (or tubular) portion; c, Peripheral 
portion of the latter; d, Interior of the pelvis; d’, d’, Arms of the pelvis; ¢ 
Border of the crest; f, Infundibulum; g, Ureter. 


In the Horse, the tissue of the kidney cannot be divided into lobules or 
pyramids ; to the naked eye it appears to be composed of fibres that start 
from every part of its exterior, and converge towards the crest of the pelvis. 
A microscopical examination demonstrates these fibres to be canals or tubes ; 
hence they are designated tubuli uriniferi or Bellini’s tubes. <A delicate 
connective tissue, a kind of stroma, which is very rare in the cortical, but 
more abundant in the medullary substance, especially in the vicinity of the 
pelvis, sustains the vessels and nerves, and unites the tubuli uriniferi to each 
other. 

The tubuli uriniferi are constituted by a proper amorphous membrane, 
very thin and elastic, whose internal face is lmed by simple epithelium that 
readily alters ; the cells are polygonal in certain points, polyhedral in others, 
and transparent or granular 


488 THE URINARY APPARATUS. 


The uriniferous tube has not everywhere the same direction or diameter 
Taking it at its termination on the crest of the pelvis, and following it to its 


Fig. 249. 


SECTION OF THE CORTICAL SUBSTANCE OF THE KIDNEY 


A, A, Tubuli uriniferi divided transversely, showing the spheroidal epithelium in - 
their interior; B, Malpighian capsule; a, Its afferent branch of the renal artery ; 
b, Its glomerulus of capillaries; ¢, c, Secreting plexus formed by its efferent 


vessels; d, d, Fibrous stroma. 


Fig. 250. 


DIAGRAM OF THE COURSE OF THE URINIFEROUS 
TUBULE, 

a, Orifice of tubule at pelvic crest’; b, Recurrent 
branches which form loops, ¢, in the medullary 
portion of the kidney, and terminate in the 
Malpighian capsules in the cortical portion. 


origin in the Malpighian body, it 
is found that the tubule is at first 
single, straight, and voluminous, 
but that during its course across 
the medullary substance it divides 
into three or four tubes, which, in 
their turn, subdivide in a dicho- 
tomous manner. These divisions 
are less voluminous and straight, 
and their diameter is uniform until 
they reach the cortical substance ; 
here they bifurcate, each branch 
becomes flexuous, and is designated 
the uniting tube, and is continued 
in a kind of elongated U shape, the 
ansiform tube of Henle, which des- 
cends towards the centre of the 
kidney. The ascending branch of 
this ansiform tube, whose diameter 
is very small, suddenly dilates on 
entering the cortical substance, 
describes several bends, contracts 
into a narrow neck, and then opens 
into a Malpighian body, after having 
taken the name of convoluted tube. 
The corpora Malpighiana (or 
capsules) are minute vesicles, whose 
walls possess the same structure as 
the uriniferous tubes; each lodges 
a cluster of arterial capillaries or 
renal glomerulus, and has two oppo- 
site openings: one communicating 


THE KIDNEYS. 


489 


between the corpora and convoluted tubes, the other affording a passage 


to the afferent and efferent vessels of the glomerule, 

3. Vessets anp Nerves.—a. The kidney pos- 
sesses a special artery and vein, remarkable for 
their enormous volume. 

The artery forms several branches which reach 
the kidney by its inner border and inferior face, 
and divide into a certain number of principal 
vessels, which are disposed in a wavy manner on the 
limits of the cortical and medullary substances. 
‘From them are given off branches to each of 
these substances, and among those distributed to 
the cortical are some regularly disposed, which 
furnish, on each side, the glomerule ramifications ; 
these are the afferent vessels or Malpighian glome- 
rules (or tufts); the others form a polyhedral 
plexus around the convoluted tubes and corpora 
Malpighiana. The afferent vessels of the renal 
glomerules enter this plexus. 

The arterial branches of the medullary sub- 
stance descend parallel to the straight tubes, and 
anastomose by transverse branches, so as to form 
a network with elongated meshes. 

The vein issues from the kidney by the hilus, 
and succeeds the arterial capillaries. In the me- 
dullary substance, there are straight veins as there 
are straight arteries. On the surface of the organ, 
beneath the fibrous envelope, are the stars of 


Fig. 251. 


DISTRIBUTION OF THE RENAL 
VESSELS IN THE HORSE’S 
KIDNEY. 

a, Branch of renal artery ; a7, 
Afferent vessel; m, m, Mal- 
pighian tufts; ef, ef, Ef 
ferent vessels; p, Vascular 
plexus surrounding the 
tubes; st, Straight tube ; 
ct, Convoluted tube. 


Verheyen: the junction of five or six venules which converge towards a 


central vein. The veinlets of the 
two substances collect into more 
voluminous vessels, which form 
complete arches at their limits ; 
it is to the presence of these 
vascular canals, that the dark 
colour observed at this point of 
the renal tissue must be attri- 
buted. 

b. The lymphatics are abund- 
ant at the superficies and in the 
mass of the organ, forming plex- 
uses, whose ultimate branches 
pass to the sublumbar glands. 

c. The nerves emanate from 
the solar plexus, and compose a 2 
particular network around the 
arteries, exhibiting, on their 
course, some microscopic gan- 


Fig. 252. 


TRANSVERSE SECTION OF THE KIDNEY. 


1, Inferior border; 2, Cortical tissue ; 3, Section of 
blood-vessels; 4, Pelvis; 5, Ureter; 6, Superior 


glia. Itis not known how they border; 7, Renal artery; 8, Proper capsule. 


terminate. 


Devetorment.—The kidneys appear very early in the foetus, above and a 
little behind the Wolffian bodies. They are then very distinctly lobulated, but 
the lobes gradually become fused, and have entirely disappeared at birth ; the 


490 THE URINARY APPARATUS. 


small irregularities on the surface being the only indications of their having 
existed in Solipeds. ; 

Funcrions.—The kidneys are the organs which secrete the urine ; but 
this secretion docs not take place to the same extent in all parts of their 
tissue. The abundance of vessels in the cortical substance, the presence of 
the Malpighian corpuscles, and the flexuosities described by the uriniferous 
tubes, sufficiently indicate that this substance should be the principal, if not 
the exclusive, seat of the secretory function. But in what manner does this 
secretion take place? At present it is generally agreed that the urinary 
secretion is simply an infiltration of the elements of the urine contained in 
the blood, through the walls of the vessels and the uriniferous tubes. A 
knowledge of the phenomenon of dialysis, discovered by Graham ; and the 
difference existing between the diameter of the afferent and efferent vessels of 
the Malpighian glomerules—a fact whose importance was pointed out by 
Ludwig—sufficiently explains this filtration of the urine through the tissue 
of the kidneys. 


2. The Ureters. (Fig. 247.) 


Form.—The ureter is a membranous canal, having the diameter of a thick 
goose quill, which conveys the urine from the pelvis of the kidney into the 
bladder. Its origin, course, termination, and structure, will be successively 
considered. i 

Origin.—It has been already shown that the origin of the ureter is at the 
infundibulum of the pelvis; it leaves the kidney by the internal fissure or 
hilus, curves outwards, passes along its lower face, and is inflected backwards 
in quitting the organ. 

Direction—The course it afterwards follows is almost in a straight line 
towards the pelvic cavity, along with the aorta or posterior vena cava, 
according to the side to which it belongs; it is in contact with the small 
psoas muscles, and proceeds above the peritoneum. After passing beyond 
the terminal branches of the aorta, which it crosses very obliquely, it 
becomes enveloped in a short peritoneal fold that maintains it against the 
lateral wall of the pelvis; it afterwards emerges from this fold, and reaches 
wie posterior and superior part of the bladder. 

Termination. Having reached that viscus, its termination takes place as 
follows : instead of opening directly into the bladder by traversing at once, 
and perpendicularly, the two membranes composing the organ, the ureter at 
first pierces the muscular coat, between which and the mucous membrane 
it passes for about an inch, and then opens on the surface of the latter. 
This arrangement prevents the flowing back of the urine into the ureter 
during its expulsion, the intermembranous portion of that canal being 
strongly compressed by the external pressure then exerted by the muscular 
coat, and by the internal resistance which the accumulation of urine in the 
bladder opposes to this pressure. So well are Nature’s intentions fulfilled 
in this respect, that we may inflate the bladder by the ureter, after tying the 
canal of the urethra, and press vigorously on the distended organ, without 
oh able to make a single bubble of air pass through the perfectly pervious 
canal. 

Srrucrurs.—The excretory canal of the kidney is composed of three tunics: 

1. An internal mucous tunic, continuous, in front, with that lining the 
pelvis of the kidney, and behind, with that of the bladder. It is very thin, 
pale, ridged longitudinally, and has a stratified tesselated epithelium. (It 
has some mucous follicles, but no villi.) 


THE BLADDER. 491 


2. A middle muscular layer arranged in two orders: a superficial, whose 
fibres are circular, and a deep, passing in a longitudinal direction. (Leyh 
and other authorities describe the arrangement of the muscular planes, 
which are composed of smooth fibres, to be the reverse of this, the longi- 
tudinal being superficial, and the deep circular.) 

3. An external tunic, composed of connective tissue and elastic fibres. 

The muscular tissue of the ureter, by contracting, accelerates the flow 
of the urine. 


3. The Bladder. (Fig. 247.) 


Position.—This is a membranous reservoir, lodged in the pelvic cavity, 
where it occupies more or less space, according to the quantity of urine it 
contains ; it may extend beyond the pubis, into the abdominal cavity. 

Form.— Considered in a moderate state of plenitude, the bladder is ovoid 
in figure ; its large extremity being turned forward, forms a rounded cul-de- 
sac (fundus), at the bottom of which is remarked a kind of cicatrice, caused 
by the obliteration of the urachus. The other extremity terminates, 
posteriorly, by a well-marked constriction, the neck of the bladder, which 
gives rise to the urethral canal. 

Weight.—The average weight of the empty bladder is about sixteen 
ounces. 

Relations and mode of attachment.—The bladder responds: above, to 
the vesicule seminales, to the pelvic dilatations of the deferent ducts, as 
well as to the rectum; below, to the inferior wall of the pelvis, on which it 
rests (by its dase); on the sides, to the lateral walls of that cavity. In the 
female, the superior face of the bladder is in relation with the uterus and 
vagina, which entirely separate it from the rectum. The posterior extremity 
or neck (cervix), flanked on each side by the lobes of the prostate, is fixed 
below to the ischio-pubic symphysis, by means of a particular ligament or 
fasciculus of elastic and contractile fibres, which are detached from the 
muscular layer, and expanded over the lower face of Wilson’s muscle, to 
be carried backwards and downwards, and terminate on the surface of 
the internal obturator muscle. The anterior extremity, or fundus, usually 
responds to the pelvic curvature of the large colon. 

It is remarked that this extremity is covered by a serous cap, which is 
prolonged backwards on its body, but further above than below. This 
covering is continuous with the parietal layer of peritoneum, and adheres 
closely to the muscular tunic of the bladder, so that it constitutes its chief 
attachment ; its disposition is precisely similar, in principle, to that of the 
other serous visceral membranes. 

Thus the peritoneum, after covering the walls of the pelvis, is reflected 
on the organs contained in that cavity, and in particular on the bladder, 
around which it forms an orbicular fold. This again gives rise to three 
secondary folds, a kind of serous layers, which are usually termed the 
ligaments of the bladder. One of these layers is single and vertical, and is 
fixed to the inferior part of the fundus; it is not rare to see it prolonged 
forward on the lower wall of the abdomen, as far as the umbilicus ; on its 
free border it is said to have a thin hem or cord, the last vestige of the 
urachus. If this cord exists, which appears doubtful to us, it cannot possess 
the signification given to it; for the urachus has not, like the umbilical 
’ arteries, an abdominal portion; it only commences at the umbilicus to be 
prolonged in the cord to the allantois. The other two serous layers 
(umbilical ligaments), pairs and horizontal, are attached to the sides of the 


492 THE URINARY APPARATUS. 


fundus, and present, on their free border, a thick cord, the obliterated 
bilical artery. Sa dines : 
ee Owing to thie disposition of the peritoneum, the bladder is divided mio 
two perfectly distinct regions: an anterior, enveloped by ® serous layer ; 
the other, posterior, is brought in contact with the surrounding organs 
through the medium of the loose and abundant cellular tissue of the pelvic 


THE KIDNEYS AND BLADDER IN THE FETUS OF SOLIPEDS. 
A, Supra-renal capsules; 3, Kidney; 6, Ureter; o, Bladder; p, Urachus.—1, 
Abdominal aorta; 2, External iliac artery ; 3, Umbilical artery; 4, Umbilical 
vein. 


region. This tissue, constantly mixed with adipose masses around the neck 
of the bladder, submits, with the serous membrane of the anterior region, to 
the changes in form and continual displacements of the urinary sac. 


THE URETHRA. 498 


Interior —This pouch, studied internally, exhibits folds and ridges moro 
or less marked, according to its state of plenitude. It also shows, pos- 
teriorly, the opening of the neck, which communicates with the urethral 
canal, and a little higher, the orifices of the ureters. These three apertures 
circumscribe a triangular space, the trigonum vesice. 

Srrvcture.—The structure of the bladder is very simple. Two mem- 
branes compose its walls, the internal of which is mucous, and the external 
muscular. Anteriorly, the latter is covered by the serous investment 
described above. 

The mucous membrane is pale and thin, and is continuous with that lining 
the ureters and the urethra. It thows some papille and some simple 
tubular glands towards the neck. Its epithelium is stratified and tesselated, 
the superficial cells being very irregular. 

The muscular layer is composed of white fibres, the arrangement of which 
is very complicated. Certain authorities describe three superposed planes, 
whose fibres pass in different directions. In the Horse, the walls of whose 
bladder are very thin, these planes are difficult to demonstrate. The fibres are 
longitudinal, circular, oblique, spiral, and even twisted towards the fundus 
of the bladder ; the deep fibres are reticulated. In the posterior region they 
do not form a sphincter around the neck of the organ, as is generally 
believed; the real sphincter is Wilson’s muscle, which encircles the 
membranous portion of the urethral canal. 

Vessels and nerves.—The parietes of the bladder receive their blood 
from several sources. The principal arteries come from the vesico-prostatic 
branch of the internal pudic ; the umbilical artery also furnishes ramifications 
that reach the fundus of the organ. The lymphatics pass to the sublumbar 
glands. The nerves are furnished by the pelvic or hypogastric plexus, and 
the inferior branches of the two last sacral pairs; their twigs are spread 
more especially between the muscular and mucous layers. 

Dervetorment.—The study of the development of the urinary reservoir 
is very interesting. It is narrower and more elongated in the foetus than 
the adult, and is relatively more capacious during the whole period of intra- 
uterine life. It then occupies the abdominal cavity as far as the umbilical 
opening, and is flanked by the two umbilical arteries. Its posterior 
extremity alone enters the pelvis; the anterior extremity, forming a veritable 
neck, is continuous with the urachus, just as the neck, properly so called, is 
continuous with the urethral canal (Fig. 253). At birth, this anterior neck 
separates from the urachus, and is transformed into a free cul-de-sac; while 
the bladder is gradually withdrawn into the pelvic cavity, carrying with it 
the umbilical arteries, and finishes by acquiring the position it definitively 
preserves in the adult. 

Founctions.—The part played by the bladder is one of incontestible 
utility. In permitting the accumulation of the urine and the intermittent 
expulsion of that excrementitial fluid, it spares animals the disagreeable 
condition in which they would be placed if the liquid secreted by the 
kidneys was continually being discharged as it was produced. 


4. Urethra. 


The description of this organ will be given with that of the genital 
organs ; asin the male it is common to the urinary and generative apparatus ; 
even in the female it is intimately connected with the latter 


494 THE URINARY APPARATUS. 


5. The Supra-renal Capsules. (Fig. 247.) 


tuation—Form.—'The supra-renal capsules (or adrenals) are two small 
Pr Ree to the ela thee of the kidneys, in front of the hilus, aud 

to their inner border. : 
ieee are clongated from before to behind, flattened on both sides, and 
irregularly lobulated on their surface. Their length is from 2 to 24 inches, 
and width from 14 to 1} inches. They have not the same volume, the 
right being larger than the left. ; . 

Relations—A large amount of connective tissue, vessels, and nervous 
filaments attach these bodies to the neighbouring organs. The right is 
related, in front, to the liver; above, to the right kidney; and inwardly, to 
the posterior vena cava and the ramifications of the solar plexus. The left 
does not touch the liver or spleen, but, by its inner border, is applied against 
the posterior aorta and great mesenteric artery. 

Srrucrurs.—At present, anatomists are not agreed as to the structure of 
the supra-renal capsules. ‘I'he following is what is probably most reliable 
in this difficult point in normal histology. 

These organs offer an enveloping membrane and parenchyma. — 

The enveloping membrane is fibrous, and sends off, from its inner face, 
prolongations which pass into the parenchyma and form cylindrical spaces, 
subdivided by transverse lamella. These spaces are named glandular 
cavities ; but the septa soon become thin, and disappear almost completely, 
leaving nothing but some very few trabecule of connective tissue. 

The parenchyma is divisible into two layers: the cortical and medullary 
substance. The first is of a dark-brown colour; the second is yellow and 
soft, and does not show any cavity in its centre; that which has been 
described is the result of the destruction of its proper elements, which soon 
change after death. 

The glandular cavities of the cortical substance are filled with nucleated, 
granular, and often fat cells in the adult animal; near the central substance 
these cavities only contain a single cell. 

The medullary substance has, for its basis, a very delicate reticulum, 
supporting cells analogous to those of the cortical substance, and stellate 
elements which Luschka considered were nerve cells. 

Vessels and nerves.—Like the kidneys, which are contiguous to them, the 
supra-renal capsules receive a large quantity of blood, compared with their 
small volume. The arteries are branches of the neighbouring vessels: the 
mesenteric and renal. They form avery delicate plexus in the parenchyma. 
(They keep to the stroma of the trabecule; consequently, their finest 
ramifications are found in the secondary septa of the cortical substance, 
where they form elongated plexuses, which are rounder in the medullary 
portion. In the middle of the latter, the venous ramuscules unite, and give 
rise to a considerable trunk, the vena supra-renalis, on which the organ is 
oo on a pedicle. It is this vein which constitutes the debated 
cavity. 

__, The veins are satellites of the arteries in the tissue of the organ, and pass 
into the renal vein or posterior vena cava. The lymphatics are scarce. 

The supra-renal bodies receive many ganglionic nerves derived from the 
solar plexus, and whose mode of termination is unknown. (As mentioned 
by Chauveau, the nerves of these organs are extremely numerous, they being 
more abundantly supplied than any other structure of the kind in the body ; 
a large number of small branches enter the cortical portion, to become 


THE URINARY APPARATUS. 495 


developed in the medullary tissue. As these nerves do not leave the medullary 
substance, and as, besides, its cellular elements appear to be of the same 
nature as the multipolar ganglionic cells, it is presumed that the nervous 
fibres emerge from these globules, and that the medulla acts as a ganglionic 
nervous centre. Though Leydig fully believed the internal portion to be 
of a nervous character, he thought another function might be attributed to 
the cortical, in consequence of its being most frequently of a fatty nature. 
Bergmann was the first, in 1839, to class these organs with the nervous 
system, and Remak, in 1847, by his researches in embryology, was led to 
group them with the sympathetic ganglia, and named them nervous glands. 
Injury to the dorsal portion of the spinal cord causes congestion and 
hypertrophy of the supra-renal capsules. In a watery solution of the 
cortical portion, a rose-tinted substance has been discovered, which changes 
to green with persalts of iron.) 


Development.—These bodies are relatively larger in the foetus than the 
adult, though this difference does not influence their structure. : 

Functions.—Their uses are still unknown; they are ranked in the 
category of blood-vascular glands, along with the spleen and thyroid body, 
whose functions are also not yet ascertained. (Leydig is of opinion that 
these bodies should be regarded as belonging to the nervous system.) 


DIFFERENTIAL CHARACTERS IN THE URINARY APPARATUS OF OTHER THAN SOLIPED 
ANIMALS 


1. Kidneys.—In other than Soliped animals, the renal glands are simple or multiple, 
or in other words, simple or lobulated. In the Ow, the kidneys have an elongated shape 
from before to behind, which is altogether characteristic; and, in addition, they 
preserve during life the lobulated form only seen in the other animals during intru- 
uterine existence. Each agglomeration is composed of from fifteen to twenty secondary 
kidneys; but the pelvis is not formed in the centre of this agglomeration, being carried 
altogether outwards, and occupying an excavation in the inferior {ace of the organ, which 
represents the hilus. This cavity is divided into as many short, wide prolongations—the 
calices, as there are principal lobules; the uriniferous tubes from each lobule open 
on a small papilla, which projects into the bottom of the calyx. This papilla is, therefore, 
nothing more than the crest of the simple pelvis in the kidney of Solipeds (Fig. 256). 

In the Sheep, the kidneys are not lobulated, and the pelvis is carried to the inner 
border, as in the Horse. 

The kidneys of the Pég are simple and voluminous, and their pelvis is disposed as in 
the Horse. (There are 10 or 12 papille, and as many calices.) 

In the Dog and Cat, there are no calices absolutely comparable with those of 
Ruminants. The pelvis is simple, and presents at the bottom a single, large, elongated 
tubercle, that has at its base some very short projections or pillars. 

2. Bladder—The most important difference in the bladder of the domesticated 
animals consists in the extent of the development of its perituneal envelope. In non- 
soliped animals this covers all the organ to the neck; the ligaments are also very short, 
and the viscus may be easily projected into the abdominal cavity. The bladder is thin, 
and of a considerable capacity in Ruminants and the Pig; in the Dog, on the coutrary, 
it has a very thick muscular layer, its fibres forming distinct fasciculi, especially when 
in a state of retraction. (In Ruminants, the orifices of the ureters are near each other ; 
at the fundus the mucous membrane shows a small fossa which is continued by a narrow 
canal that terminates in a cul-de-sac, and constitutes a free appendix about half an inch 
long, and of the thickness of a goose-quill.) 

3. Supra-renal capsules—These small organs are discoid in the Sheep and Pig, 
reniform in the Dog. In the Oz, they are situated at a certain distance in front of the 
kidneys, and their shape is like that of these bodies in the Horse; though they are a little 
constricted in the middle, and slightly curved. 

In Birds, the kidneys “are lodged at the same height, behind the peritoneum, 
immeiliately posterior to the lungs, and in the lumbar and pelvic regions, where they 
occupy several fossze excavated in the upper face of the pelvis. Their form is irregular 
and more or less elongated, depending upon the bones and other parts to which they are 


496 THE URINARY APPARATUS. 


i ¢ ‘tions 
i nd on which they are moulded. In many birds, nevertheless, three por A 
anes io separated by thane may be recognised. The ileo-lumbar ec SA ae 
becatise of its constant position in this region) is the most advanced “ is 0 aoe 
largest. The middle is the narrowest; it is turned towards thé ileo-sacra. pee Haas 
the pelvis. The posterior is contained in that cavity, and is again lene Mapas 
latter portions are designated as the anterior or superior pelvic, and the inferior head 
pelvic portions. Their internal and superior border is often notched by a series ©: s- 


Fig. 254, Fig. 255. Fig. 256. 


KIDNEYS OF THE OX. 


Fig. 254.—Right kidney, viewed on its upper and external face. Fig. 255.—Left 
kidney, from its internal and inferior face; a, Pelvis; 6, b, 6, Branches of the 
pelvis terminating in calices; c, Ureter; d, Renal artery. Fig. 256.—The calices 
in the left kidney. The contents of the hilus, including the branches of the 
pelvis, have been removed to show the tubercles at the bottom of these calices. 
Only seven are visible, the others being beneath the borders of the renal fissure. 


verse fissures produced by the protrusion of the transverse processes of the sacral verte- 
bre, as the lungs are furrowed by the projection of the ribs.”? 

The excretory apparatus is incomplete, and is only formed by the ureters, which open 
into the cloaca, where tle urine is mixed with the faces. Only one bird, the Ostrich, 
possesses a bladder, which is disposed in a particular manner. 


COMPARISON OF THE URINARY APPARATUS OF MAN WITH THAT OF ANIMALS, 


1. Kidneys.—The two kidneys of Man have, like those of the smaller domesticated 
animals, the same shape—that of a haricot bean. The average weight is about from three 
to five ounces. Contrary to what is observed in the Horse, the left kidney is more 
voluminous than the right, and is higher. 

The kidneys are simple externally, though their tissue is disposed in distinct lobes, 
which number from eight to fifteen, and are composed of a Malpighian pyramid and a 


? Cuvier, ‘Anatomie Comparee, 2nd edition. Paris, 1836-46, 


THE URINARY APPARATUS. 497 


superposed pyramid of Ferrein; they terminate, towards the hilus, by acone or renal 
papilla, each surrounded by a calyx, and are separated by small prolongations of the 
cortical substance—the columne Bertini. 

2. Ureters—The canals are disposed at their origin as in the Ox; they terminate as 
in the other animals. In the hilus of the kidney are from eight to fifteen prolongations or 
calices, which unite into a larger cavity or great calyx, that finally opens into the renal 
pelvis; this is immediately followed by the ureter. 

8. Bladder—The large extremity of this organ is directed downwards in the bottom of 
the pelvis, where it is continuous with the urethral canal; its summit is directed upwards, 
and is frequently pointed. Its mode of attachment and internal conformation are the 
same as in animals; and, as in the Horse, the peritoneum envelops it very incompletely. 
The muscular fibres are arranged into three planes: a superficial, which forms a band 
that is carried from the anterior to the posterior face in passing over the summit; a 
middle plane whose fibres are circular; and a deep plane with reticulated fibres. 

Supra-renal capsules.—This name is quite appropriate to these bodies, as in Man, or 
at least in the foetus, they form a kind of helmet that covers the upper part of the 
kidney. 

There is nothing to add respecting their structure, 


BOOK V. 
CIRCULATORY APPARATUS. 


Tse animal economy is incessantly traversed by two fluids—blood and 
lymph. 

‘The blood is a liquid, coloured bright-red or brown by particular globules, 
from which the tissues derive not only the materials for nutrition and 
secretion, but also the exciting principle which vivifies the organic 
matter. It is named red or dark-coloured blood, according to its 
tint. 

The lymph or white blood is a transparent, citrine-coloured fluid, which 
can be obtained from the majority of the organs. That which comes from 
the abdominal portion of the alimentary canal is charged, during digestion, 
with a portion of the reparative materials elaborated in that apparatus, and 
is distinguished by its lactescent aspect ; it is designated the chyle. 


Fig, 257. 


THEORETICAL PLAN OF THE CIRCULATORY SYSTEM. 

CH, D, C, E, The canal for red blood; §, B, A, G, Canal for black blood. The arrows 
indicate the course of the blood. The two canals are represented in their middle 
portion, AB, CD, as isolated; but in nature they are enveloped at this point ina 
common sac that concurs to form the heart.) 


These fluids are carried by vessels—tubes which are continuous with one 
another. When joined together, end to end, these tubes give rise to three 
principal canals : 


“One of these canals extends from the lungs to all parts of th 
and is traversed by red blood. cas parts of the body, 


THE HEART, 499 


‘The second extends from all parts of the body to the lungs, and carries 
dark blood. 

“ The third passes from the majority of the organs towards the canal 
ae dark blood, in which it terminates; it conveys the white blood or 
ymph. 

“The red-blood and dark-blood canals bear the greatest analogy to each 
other. Both are simple in their middle portion, which alternately dilates 
and contracts to impress upon the blood the movement necessary to life. 
Both present at their extremities innumerable ramifications, which ultimately 
join each other; so that the fluid they carry passes from one to the other 
in a constant and circular direction. Both are composed, at their origin, 
of vessels in which the blood moves in confluent columns: these are the 
veins ; and in their terminal part, of vessels in which the same liquid is 
spread in divergent columns: these are the arteries. 

“The canal for white blood is composed of a single order of vessels, the 
lymphatics : converging tubes, whose common trunk opens into the circulatory 
canal that results from the abouchement of the red and dark blood canals ; 
the relation it affects with these latter is that of a tangent with its cir- 
cumference.”—Sappey. 

These three canals constitute the circulatory apparatus. 

This apparatus therefore comprises: 1, The heart, a central organ, 
charged to propel the blood; 2, A system of centrifugal vessels, the arteries, 
which carry the blood from the heart into the different organs; 3, A 
system of centripetal vessels, the veins, which bring the nutritive fluid to 
the heart; 4. The lymphatics, an accessory centripetal system, destined to 
convey the lymph into the blood-vascular circle. 

In many anatomical works, the study of this apparatus—the heart, 
arteries, veins, and lymphatics, is designated “ angiology.” 


FIRST SECTION. 


THE Heart. 


Tue history of the heart comprises: 1, A general view of the organ; 
2, The study of its external conformation ; 3, Its interior; 4, Its structure ; 
5. A description of the pericardium, the serous cavity containing it; 6, A 
glance at its physiology. 


1. The Heart as a Whole. (Figs. 230, 234, 258, 259.) 


General sketch—The heart, the central portion of the circulatory 
apparatus, is a hollow muscle, whose cavity is divided by a thick vertical 
septum into two perfectly independent pouches. Of these two contractile 
pouches, one placed on the track of the dark blood, propels it into the lungs ; 
the other, situated on the course of the red blood, distributes it to all parts 

f the body. 
: Hach af these is subdivided into two superposed compartments by a 
circular constriction, at which is a membranous valve that at certain fixed 
periods is elevated, and then forms 2 complete horizontal partition extended 
the two compartments. f ; 
me superior compartment receives the convergent or centripetal portion 


500 THE CIRCULATORY APPARATUS. 


of the blood canal—that is the veins: it is named the auricle. The inferior 
gives origin to the divergent or centrifugal part of the same canal, and is 
designated the ventricle. he bet ' : : 

The cavities of the heart are distinguished into right or anterior, and 
left or posterior, because of their relative positions. There are, then: a 
right auricle and ventricle, the two dark-blood pouches; and a left auricle 
and ventricle, situated on the track of the red-blood canal. 

Situation.—The heart, enclosed as it is in a fibro-serous sac, named the 
pericardium, is placed in the chest between the two layers of the mediastinum, 
opposite the third, fourth, fifth, and sixth ribs; in front of the diaphragm, 
which separates it from the abdominal viscera; above the sternum, which 
appears to support it; and beneath the vertebral column, to which it is 
suspended by means of the large vessels. (Between the middle of the 
anterior border of the heart, in front, and the entrance to the chest, is an 
interval of about four inches; and behind, at the same level, this organ is 
at a similar distance from the diaphragm. It is distant from the fifth and 
sixth dorsal vertebra, from which it is suspended, about 44 to 5 inches 
in an average-sized Horse.) 

Form and direction.—The heart presents the form of an inverted cone, 
slightly depressed on each side, and whose axis, directed obliquely 
downwards and backwards, deviates a little to the right at its superior 
extremity. 

Volume.—In a middle-sized Horse, the greater axis of the heart is about 
10} inches in length; its antero-posterior diameter, measured near the base, 
is equivalent to about 74 inches. Its lateral diameter does not excéed 
from 5 to 53 inches. 

Capacity—It is very difficult, if not impossible, to obtain the exact 
capacity of the heart’s cavities. From reasoning, one is led to think that 
the two hearts have exactly the same capacity, and that this capacity is 
equivalent to an average of 1 to 1} pints. The amount obtained by 
measurement is much more considerable; but then the heart is distended 
to a greater degree than in its physiological state. 

Weight.—The weight of the heart varies with the size of animals, and 
that to a considerable degree. Its average is about 6? pounds. (The volume 
and weight of the heart are very much greater in well-bred than in under- 
bred Horses. Its dimensions and capacity are greater in the living than 
the dead animal; as, after death, its cavities contract, particularly the aortic 
ventricle, whose walls are the thickest. This ventricle will then scarcely 
contain more than 3-4ths to 1ith gills; the pulmonary ventricle, which 
is not so thick, and consequently less contracted, may usually receive double 
that quantity; while in animals experimented on when expiring, it was 
observed that these two ventricles were much more capacious, and that each 
contained at least from 1} to 14 pints.) 


External Conformation of the Heart. (Figs, 258, 259.) 


The cone represented by the heart is divided by a horizontal groove into 
two unequal portions: the one superior, comprising the auricles or auricular 
mass ; the other inferior or principal, formed by the ventricles or ventricular 
mass. 

A. Ventricounar Mass.—It is this which determines the conical shape 
of the heart, and constitues its largest portion. Owing to the slight flatten- 
ing which depresses the organ in a lateral sense, it may be considered as 


THE HEART. 501 


pone a right and left face, an anterior and posterior border, an apex, and a 
ase. 

The right face, smooth and rounded, is traversed by a vascular furrow 
parallel to the axis of the heart, and which divides this face into two 
sections: an anterior, belonging to the right ventricle; and a posterior, less 
extensive, forming part of the left ventricle (Fig. 259). 

The left face, disposed in the same manner, also shows a groove on the 
limit of the two ventricles. whose direction slightly crosses the great 


Fig. 258, 


THE HEART AND PRINCIPAL VESSELS; LEFT FACE. 

a, Right ventricle; 5, Left ventricle; c, Right auricle; d, Left auricle; e, Pul- 
monary artery; e’, Obliterated arterial canal; 7, Pulmonary veins; g, Anterior 
aorta; A, Lett axillary artery; ¢, Right axillary artery, or brachio-cephalic 
trunk; j, Origin of the dorsal artery; 4, Origin of the superior cervical artery ; 
Z, Origin of the vertebral artery ; m, Origin of the inferior cervical artery; x, 
Origin of the internal thoracic artery ; 0, Origin of the external ditto; p, Carotid 

_. arteries; g, Posterior aorta; r, Anterior vena cava; s, Trunk of the axillary 

* vein; ¢, Trunk of the internal thoracic vein; uv, Trunk of the dorso-cervical 
vein; v, Posterior vena cava; v', Embouchure of the hepatic and diaphragmatic 
veins; x, Vena azygos; y, Thoracic duct; <, Embouchure of that vessel, placed 
near the origin of the anterior vena cava—l, Right cardiac artery; 2, Left 
cardiac artery; 3, Auriculo-ventricular branch of the latter; 4, Its ventricular 
branch ; 5, Cardiac vein. 


diameter of the heart from behind to before, and above to below, and which 
is much nearer the anterior than the posterior border (Fig. 258), 


35 


502 THE CIRCJLATORY APPARATUS. 


These two faces respond, through the medium of the pericardium, to the 
plure and the pulmonary lobes ; the latter separate them from the thorax, - 
cept towards the middle and apex of the organ, where these faces come directly 
in contact with the thoracic parietes through the notch at the inferior border 
of the lung, and which we know is more marked in the left than the right. 

The borders are thick, smooth, and rounded. The anterior, formed by 

the right ventricle, is very 

Fig. 259. oblique from above to below, 

and before to behind; it then 

inclines on the sternum more 

or less, according to the sub- 
jects. 

The posterior border, much 
shorter than the anterior, is 
~ nearly vertical. Superiorly, 
it is separated from the dia~ 
phragm by the lung; but, 
below, it is quite close to 
that muscular septum. 

The apex, or point of the 
ventricular cone, is blunt, 
slightly rounded, turned to 
the left, and formed entirely 
by the left ventricle. 

The base responds on the 
right, in front, and behind, 
to the auricular mass ; it gives 
exit on the left, and a little 
in front, to the two arterial 
aortic and pulmonary trunks. 

B. Avricunar Mass.— 
Elongated from before to be- 
hind, disposed like a crescent 
above the right side of the 
base of the ventricles, con- 
stricted in its middle part, 
on the limit of the two auri- 

THE HEART AND PRINCIPAL VESSELS; RIGHT Face. les, the auricular mass pre- 
a, Right ventricle; b, Left ventricle; c, Right auricle; sents for study three Faces, 
4, Anterior vena cava; ¢, Vena azygos; f, P osterior two extremities, and a base. 

vena cava; 9, 9, Pulmonary veins; h, A, Divisions T, fe dic 
of the pulmonary artery ; 2, Posterior aorta; 7, An- , & super Lor face is - 
terior aorta; 4, Thoracic duct; /, Right cardiac vided by a middle constric- 
artery; im, Its vertical or ventricular branch; n, Its tion into two convex sections, 


horizontal or auriculo-ventricular branch; 0, Ven- each of which corresponds to 
tricular branch of the cardiac vein; p, Auriculo- ¥ . 
ventricular branch of the same. enaunicle, The BnbenOY, OF 


right section, shows the in- 
sertion of the anterior vena cava and vena azygos ; the posterior, or left, 
that of the pulmonary veins. The trachea, bronchi, and pulmonary artery 
pass above this face (Figs. 258, 259). 

The right face, the most extensive in the antero-posterior direction, is 
divided like the preceding, and disposed in a similar manner. The right, or 
anterior part, receives, behind and below, the insertion of the posterior vena 
cava, and the coronary and bronchial veins (Fig. 259). 


THE HEART. 503 


The left face, concave from before to behind, includes the arterial trunks 
which leave the base of the heart. 

Each of the extremitis, anterior and posterior, constitutes a detached 
portion, named the appendix auricularis; these appendages are curved 
towards each other in being flattened from above to below. Their convex 
border is more or less crenelated, like the margin of a cock’s comb, and their 
culminating portion advances nearly to the pulmonary artery, above the 
trunk of the cardiac vessels (Fig. 258). 

: The base of the auricular mass, opposed to the base of the ventricles, 
is separated from it at its periphery by the horizontal groove of the heart. 


3. Internal Conformation of the Heart. 


Preparation.—It suffices to make a longitudinal incision before and behind the organ, 
in order to expose its cavities. (I have followed Wilson's directions for many years when 
examining the interior of the heart, and as a careful inspection of it is often necessary in 
the course of an autopsy, I think the student should practise the best method of laying 
open these cavities. The right auricle is prepared by making a transverse incision along 
its ventricular margin, from the appendix to its right border, and crossed by a perpendi- 
cular incision, carried from the side of the anterior to the posteiior cava. ‘lhe right 
ventricle is laid open by making an incision parallel with, and a little to the right of, the 
middle line, from the pulmonary artery in frout, to the apex of the heart, and thence by 
the side of the middle line behind to the auriculo-ventricular opening. The interior of 
the left auricle is exposed by a J-shaped incision, the horizontal section being made 
along the border which is attached to the base of the ventricle. The latter is opened by 
making an incision a little to the left of the septum ventriculorum, and continuing it 
around the apex of the heart to the auriculo-ventricular opening behind.) 


If the heart, when viewed externally, appears to be a single organ, it is 
not so when examined internally. The vertical septum which divides it 
into two bilocular pouches, in reality makes two hearts of it—one for the ‘ 
dark, the other for the red blood. We will successively study these two 
cavites by commencing with the partition that separates them. 

A. Carpiac Seprum.—tThe superior part of this septum, placed between 
the two auricles, is named the interauricular partition (septum auricularum). 
The inferior portion constitutes the interventricular partition (septum ven- 
triculorum). The first, thin and not extensive, is perforated in the foetus by 
the foramen of Botal (foramen ovale). The second, thick in its centre, thins 
a little towards its borders. 

B. Darg-Bioop (or Putmonary) Hzart.—The two superposed cavities 
forming this pouch are situated in front and to the right. They are indif- 
ferently named the anterior or right cavities of the heart: the latter term 
being in most general use, though the first is much more convenient in 
Veterinary Anatomy. 

Rieut Venrricte.—The right ventricle represents a hollow cone, the 
horizontal section of which resembles a crescent, its posterior plane being 
pushed into the cavity by the left ventricle. 

It offers two walls, an apex, and a base. 

Walls.—The anterior wall is concave ; its thickness is more considerable 
above than below, and averages 6-10ths of an inch. The posterior wall is 
convex, and formed by the septum ventriculorum. 

Both walls are uneven, from the presence of fleshy columns (columne 
carnese), which we will commence examining in a general manner, as they are 
found in the four compartments of the heart. They are of three kinds: 
one kind, named the pillars of the heart (columns or musculi papillares), thick 
and short, and fixed by their base to the walls uf the ventricles, have a free 


504 


THE CIRCULATORY APPARATUS. 


summit, into which are implanted the tendinous cords (chorde tending) 
proceeding from the auriculo-ventricular valve ;_ those of the second order 
are free in their middle part, and attached by thar extremities to the walls 
of the heart; while the third description adhere throughout their length to 
the cardiac tissue, on which they stand as if sculptured in relief. 

In the right ventricle, two columns of the first order, rarely three, are 


RIGHT SIDE OF THE HEART LAID OPEN. 


1, Cavity of right auricle; 2, Appendix auri- 
cule, with musculi pectinati; 3, Anterior 
vena cava opening into the upper part of 
the right auricle; 4, Posterior vena cava; 
5, Fossa ovalis, surrounded by the annulus 
ovalis ; 6, Eustachian valve; 7, Opening 
of the coronary sinus; 8, Coronary valve; 
9, Entrance of auricular-ventricular open- 
ing.—a, Right ventricle ; b, Its cavity; c¢, 
Conus arteriosus, or infundibulum ; d, Pul- 
monary artery; ¢, f, Tricuspid valve; g, 
One of the musculi papillares to which 
the curtains of the tricuspid valve are 
attached by chorda tendine ; A, Columne 
carnee ; 7, Two musculi papillares of val- 
vular curtain; /, 7, Chorde tendinex ; m, 
Semilunar valves of pulmonary artery ; 
n, Apex of left appendix auricule ; v, Left 
ventricle. 


met with: one on the anterior wall, 
the other on the posterior. The 
columns of the second order num- 
ber two or three principal ones, ex- 
tending from one wall to the other, 
or attached to two different points 
of the same wall. There also ex- 
ist a considerable number of small 
ones intermixed with those of the 
third order. The latter are par- 
ticularly abundant in the angles 
formed by the union of the two 
faces, where they interlace and give 
rise to more or less complicated 
areole. 

Apex.—The apex of the right 
ventricle does not descend to the 
point of the heart, being distant 
from it about 14 inches. 

Base.—This is pierced by two 
large orifices—the auriculo-ven- 
tricular opening and the pulmonary 
opening. 

Auriculo-ventricular opening.— 
Placed on a level with the con- 
striction which divides the right 
heart into two superposed compart- 
ments, this orifice, widely open and 
almost a regular circle, forms the 
communication between the auricle 
and ventricle. It is provided with 
a valvular fold that exactly closes 
the orifice when the ventricle con- 
tracts to propel the blood into the 
lungs, and which is termed the 
tricuspid (having three points) valve, 


in consequence of its form. This valve offers: 1, A superior border, attached 
to the entire margin of the auriculo-ventricular opening ; 2, An inferior 
opening, free, cut into three festoons by three deep notches, and fixed to 
the ventricular walls, principally on the summits of the fleshy columns, by 
means of tendinous cords which ramify on reaching the valve. One of these 
festoons, more developed than the others, is placed on the limit of the 
auriculo-ventricular and pulmonary openings; thereby constituting a kind of 
vertical partition which divides the ventricular cavity at its base into two 
compartments: a right cr auricular, and a left or arterial. The other 
festoons are applied to the anterior and posterior walls of the ventricle; 
3, An external face, which receives the insertion of a great number of 


THE HEART. 505 


tendinous cords; 4, An internal face, which becomes superior when the 
valve is raised to close the opening, at which period it constitutes the floor 
of the auricular cavity. 

Pulmonary opening.—This orifice represents the embouchure of the 
pulmonary artery. Situated in front and to the left of the preceding, and 
a little higher, it occupies the summit of a kind of infundibulum formed by 
the left compartment of the ventricle being prolonged upwards. It is 
perfectly circular, smaller than the artery to which it gives origin, as well 
as the auriculo-ventricular opening, from which it is separated by a species 
of muscular spur, to which is 
attached the principal festoon 
of the tricuspid valve. 

The pulmonary opening is 
furnished with three valves: the 
sigmoid (or semicircular), sus- 
pended over the entrance to the 
pulmonary artery, and, as has 
been ingeniously remarked (by 
Winslow), like three pigeon’s 
nests joined in a triangle. 
These valves are remarkable for 
their thinness; a circumstance 
which does not interfere with 
their solidity. They present: 
an external, convex border, at- 
tached to the margin of the 
orifice and to the walls of the 
pulmonary artery; a free bor- 
der, straight when pulled tense, 
coucave when left to itself, and 
sometimes provided in its middle 
with a small, though very hard, Pee eee <a aa : 
tubercle, the nodule of Arantius By ESuOnaRy aT ait aes Tes 
(noduli Arantit); a superior, 
concave face; and an inferior, convex one. The sigmoid valves are raised 
and applied to the walls of the vessel whose entrance they garnish, when 
the ventricle contracts and sends the venous blood into the lung. When 
this contraction ceases, they fall back one against the other by that part 
of their inferior face next to their free border, so as to oppose the reflux of 
the blood into the ventricular cavity.’ 

Ricut Avricir.—The cavity of the right auricle represents a very 
concave lid or cover surmounting the auriculo-ventricular opening, and 
is prolonged, anteriorly, by a curved cul-de-sac. It offers for study this 
anterior cul-de-sac, a posterior, external, and internal wall, as well as a superior 


SECTION OF THE HEART AT THE LEVEL OF THE 
VALVES. 


1 It has been repeated. ad nauseam, that the occlusion of the arterial openings results 
from the juxtaposition of the free border of the sigmoid valves; even the small tubercle 
in the middle of this border has been considered to play its part in closing the triangular 
central space Jeft when these valves meet. In passing the finger into the pulmonary 
artery of a living animal, to explore the function of these membranous folds, it is readily 
perceived that they come in contact by a large portion of their convex face, and not alone 
by their free border. This arrangement is such, that we have with much difficulty tried 
to produce an insufficiency of contact by keeping one of the valves up against the 
walls of the vessel with tho finger; but the others came down against the finger and 
applied themselves around it so as to exactly close the orifice. 


506 THE CIRCULATORY APPARATUS. 


wall or roof, and the auriculo-ventricular opening, which occupies the whole 
floor of the cavity. This orifice has been already described. 

The anterior cul-de-sac is in the appendix auricule; it 1s divided by a 
great number of muscular columns of the second and third orders (musculi 
pectinati), into deep and complex areole. 7) 

The posterior wall responds to the interauricular septum ; it 18 smooth, 
and usually marked by an oblique and more or less deep cul-de-sac (or de- 
pression), the remains of Botal’s foramen. This depression 18 surrounded 
by the ring of Vieussens (annulus ovalis) and is named the fossa ovalis ; it is 
only separated from the left auricular cavity by a thin membrane, a vestige 
of the valve circumscribing the interauricular opening in the foetus. 

The external wall is areolated, and perforated behind and below by two 
orifices, the largest of which is the embouchure of the posterior vena 
cava, the other the opening of the large coronary vein. Both are destitute 
of valves, though these are found at a short distance in the coronary vein. 
The bronchial vein sometimes opens separately beside the latter. 

The internal wall is smooth. 

The superior wall, or roof of the auricle, shows the openings of the 
anterior vena cava and vena azygos ; the latter only is provided with valves, 
which are, however, not always present. On this wall are also remarked, in 
front, areola separated by muscular columns. 

The thickness of the right auricular walls is very irregular, in conse- 
quence of the reliefs sculptured on the inner face of that cavity. In some 
points it is about the third of an inch, and in others, particularly in the 
small culs-de-sac formed by the reticulations, it is sometimes so thin as 
to appear exclusively formed by the union of the external and internal 
serous membrane. 

(When the vena azygos opens behind, there is between it and the orifice 
of the anterior vena cava, a muscular lamella with a free concave border, 
which forms a kind of valve whose extent is very variable. Behind this vena 
cava is a thick eminence, the twberculum Loweri; this has the form of a 
crescent, open in front, and elongated from right to left at the superior 
border of the septum. The anterior, or left border of the fossa ovalis, is 
thin and prominent, and constitutes the Eustachian valve: a muscular 
membranous fold of a semilunar shape, with a concave free border directed 
to the right and behind. It is of little use in animals, because of their 
horizontal position. Immediately beneath the posterior vena cava, and 
between it and the coronary vein, is a small membranous crescent—the valve 
of Thebesius.) 

C. Rep-zLoop (or Aortic) Hzarr.—This is also called the posterior 
heart, and more frequently the left heart, because it is situated behind and 
to the left of the dark-blood heart. Its general disposition otherwise exactly 
resembles that of the latter receptacle. 

Lert Ventricre.—This is a cylindro-conical cavity, whose transverse 
section gives an irregularly circular figure. Its walls attain a thickness of 
from 1} to 13 inches, except towards the apex of the heart, where they are 
extremely thin, They are less reticulated than those of the right ventricle, 
and exhibit several columns of the second order, as well as two enormous 
muscular pillars—an external and internal, for the attachment of the tendons 
of the auriculo-ventricular valve. The apex of the cavity forms a re- 
ticulated cul-de sac, which occupies the point of the heart. The base is 
perforated by the auriculo-ventricular and the aortic openings. The awriculo- 
ventricular opening, precisely similar to that of the right ventricle, is 


THE HEART, 507 


provided with a circular membrane, the mitral (or bicuspid) valve, because it is 
cut into several festoons, of which two are the principal: the one anterior, 
the other posterior, simulating in their outline the two faces of a bishop’s 
mitre. The anterior festoon is the largest, and is attached to the limit of 
the two orifices, isolating from 
the ventricular cavity a diver- 
ticulum which corresponds, in 
every respect, to the pulmonary 
infundibulum. The posterior 
festoon is applied to the walls 
of the ventricle. Between these 
two there are usually two second- 
ary festoons, making up the 
total number to four; fre- 
quently there is an accessory 
fold, situated on the right side, 
and fairly developed; the valve 
is then tricuspid, like that of 
the right ventricle. Sometimes 
two of these rudimentary folds 
are found on the left side : 
—making five festoons in all. ~ LEFT CAVITIES OF HEART LAID OPEN, 

The aortic opening, so named 1, Cavity of left auricle; 2, Cavity of appendix 
Decanso it constitutes the ovigin “srteule: 9, Oneang afte oekt yelmonry 
of the aorta, 1s placed in front open i 5, Left pulmonary ‘veins ; b, peers Rend 
and to the left of the auriculo- tricular opening; 7, Coronary vein lying in 
ventricular opening, from which auriculo-ventricular groove; 8, Left ventricle; 
it is only separated by a thin 9,9, Cavity of left ventricle.—u, Mitral valve, 


: : . its curtains connected by chord tendine to }, 6, 
muscular spur, to which is at- Columne carnee; cv, vc, Fixed columne carne 
tached the adherent border of on inner surface of ventricle; ¢, Point of appendix 


the great festoon or curtain of of right auricle. 

the mitral valve. It does not 

differ in anything from the pulmonary opening, and like it, is provided with 
three sigmoid valves. 

Lrrr Avuricte.—As in the right auricle, this forms a kind of cover 
above the auriculo-ventricular opening. Smooth behind, in front, inwards 
and outwards, its cavity presents a reticulated cul-de-sac, which occupies the 
appendix auricule ; and a superior wall, also reticular, having from four to 
eight orifices, the openings of the pulmonary veins. These orifices have no 
valves, (Carnez columne of the third kind are also present, but chiefly. 
between the two posterior pillars; small ones are very numerous on the 
borders and summit cf the ventricle. The columns of the second order are 
simple or ramous, and pass from the angles of union of the walls and the 
point of the cavity ; others on the posterior wall go to the borders and the 
interval between the two pillars. The most remarkable are bands extending 
from one wall to the other, the two principal of which are long, strong, and 
ramous; they are fixed, on the one side, to the centre of the great posterior 
reliefs, and ascend to be implanted, on the other side, into the middle of 
the anterior wall.) 


4, Structure of the Heart. 


. Preparation.—Before proceeding to dissect the muscular fibres of the heart, it is 
indispensable to keep that viscus in boiling water for haif or three-quarters of an hour. 
It should then be immediately immersed in cold water, to prevent the desiccation of the 


508 THE CIRCULATORY APPARATUS. 


ing it, and which must be at once removed. The furrows should 
they be pu “of thete “vessels and fat; this renders the superficial muscular fibres 
very apparent. The same result may be attained by immersing the heart in vinegar or 
dilute hydrochloric acid. To isolate the ventricles and unitive fibres from each other, 
the following procedure may be adopted: After removing the auricular mass | and 
dissecting the fibrous rings, the unitive fibres around these are divided with the point of 
the sealpel, care being taken not to injure the proper fibres. Then, with the aid of the 
finger-nail or handle of the scalpel, follow the more or less artificial limit of these two 
series of muscular planes in w spiral manner ; the vessels passiug through the walls of 
the heart must be cut through. The same course is followed in the substance of the 
interventricular septum, in order to separate the two sacs formed by the proper fibres, 
(It will be found that the simplest and best way to prepare the heart for an examina- 
tion of its fibres, is to steep it in a very weak dilution of hydrochloric acid. Remove the 
serous membrane, avd the fibres can then be traced, layer by layer, from their origin to 


their termination.) 


‘The muscular tissue composing the heart rests on a fibrous framework, 
disposed in rings around the auriculo-ventricular and arterial openings; it 
receives vessels and nerves, and while covered in the internal cavities by two 
independent serous membranes, it is enveloped, externally, by another 
membrane of the same kind. An annular framework, muscular tissue proper, 
vessels and nerves, and serous tunics—such are the elements entering into 
the organisation of the heart. 

A. Fisrous Rines.—These are also named the fibrous zones of the heart, 
and are four in number: one for each of the openings at the base of the 
ventricles. 

The two arterial zones (the pulmonary and aortic) constitute two complete 
rings, which are not disposed in a circular manner around the pulmonary 
aortic openings, but are divided into three regular festoons with their con- 
cavities superior and internal, and which correspond to the insertions of 
the three sigmoid valves. These zones are continuous, by their superior and 
external contour, with the walls of the arteries, from which they are only dis- 
tinguished by their whitish-grey colour and slight elasticity, the arterial 
tissue being yellow and very elastic. Their internal and inferior outline 
sends three thin prolongations into the serous duplicatures of the sigmoid 
valves. 

The auriculo-ventricular zones do not completely surround the openings 
they cireumscribe. They are flattened, brilliant-white tendons, laid one 
against the other at the level of the ventricular septum, and against 
the aortic ring; they turn to the right and left around the auriculo- 
ventricular openings, but without joining at their extremities, which are 
dispersed as fibrille in the muscular tissue of the ventricles. Above, these 
zones give attachment to the muscular fibres of the auricles; below, to the 
ventricular fasciculi. Their internal and inferior border is prolonged into 
the mitral and tricuspid valves, and is continuous, through these valves, 
with the tendinous cords fixed to the walls of the ventricles. Some of these 
cords, generally the strongest, are even directly inserted into the auriculo- 
ventricular zones. 

It must be noted that, in Solipeds, there is constantly found, at the 
point where the aortic and auriculo-ventricular zones lie against each other, 
a more or less developed cartilaginous body, which, in the larger Ruminants, 
is transformed into true bone. (Lavocat speaks of two cartilaginous points, 
one to the right, at the junction of the aortic with the left auriculo- 
ventricular ring and the cardiac septum; the other, less developed, on the 
left, at the origin of the left ventricular groove.) 

B, Muscutar Tissvz.—The muscular tissue composing the mass of the 


THE HEART, 509 


heart belongs to the system of organic life, as it contracts without the 
participation of the will. Nevertheless, it is formed of red striated fibres 
which only differ from the muscular fibres of animal life in being less in 
diameter. As in the tongue, these fibres also possess ramifications that unite 
them to each other; they are likewise very granular. (They are more 
friable than those of the muscular system generally; the sarcolemma is 
more delicate, and the longitudinal markings and nuclei are more apparent, 
the latter being placed in the axis of the fibre along with rows of minute 
fatty granules, which are extremely numerous in fatty degeneration of the 
heart. The connective tissue is scanty ; so that the fibres lie closer together 
while forming innumerable anastomosing networks and interlacings—a 
character peculiar to the muscular organisation of the heart. It has been 
asserted that there is no sarcolemma.) 

The striation of the muscular fibres of the heart, 
which constitutes an exception in the laws of organisa- 
tion, may be explained to a certain point by the nature 
of the functions imposed on the muscular tissue of the 
organ. Charged to propel the blood into the arterial 
ramifications by successive, instantaneous, and vigorous 
contractions, the heart, probably, would not have been 
capable of executing such movements if it had been com- 
posed of organic fibres, as these come into action in a 
steady, slow, and prolonged manner. The ramifications 
that unite the fibres, and establish a kind of solidarity 
between them, afford a clue to the simultaneousness in 
the movements of the auricles and ventricles. 

It is also worthy of remark, that between these 
fibres there is so little connective tissue that the majority ANASTOMOSING — MuUS- 
of anatomists absolutely deny its existence. ee asc te 

The arrangement of the muscular fasciculi of the 
heart has been the object of numerous recent investigations, which have 
only complicated what was already known on the subject. We will endea- 
vour to sum up, as simply as possible, this arrangement, in examining it in 
the different compartments of the organ. The following is the disposition 
of the fasciculi, considered successively in the ventricles and auricles : 

1. Fisrzs or tHe Ventrictes.—According to the remark of Winslow, 
we may compare the ventricles, in regard to the arrangement of the fibres 
essentially composing them, to “two muscular sacs included in a third :” 
that is to say, each ventricle is formed of proper muscular fibres, covered 
externally by a layer of unitive fibres, which envelop the two ventricles in 
common. 

a. Proper fibres of the ventricles.—Taken altogether, these fibres repre- 
sent, for each cavity, a hollow cone, open at both its extremities: at the 
superior extremity. by the auriculo-ventricular and arterial orifices; and at the 
inferior extremity, by an aperture which admits the reflected fibres of the 
common layer. All form loops attached, by their extremities, to the out- 
line of the superior orifices, on the fibrous zones. and are rolled, more or 
less obliquely, around the axis of the ventricles. It is from the apposition 
of the right and left systems that the ventricular septum is formed. 

b. Unitive fibres of the ventricles—These are disposed as an external 
shell enveloping the proper fibres. They leave the fibrous zones at the base 
of the heart, and descend towards its apex : those of the right side, by inclining 
forward ; the anterior, in following the direction of the great axis of the 


Fig. 263. 


510 THE CIRCULATORY APPARATUS, 


ventricles ; those of the left face, by directing their course from above to 
below, and before to behind; and the posterior, in rolling themselves from 
left to right around the left ventricle. On arriving near the point of the 
heart, they turn from left to right, and before to behind, in-forming a twisted 
spire; then they are reflected from below upwards, to enter the inferior 
extremity of the ventricles, on the internal face of whose proper fibres they 
spread and ascend to the fibrous zones at the base of the heart, where they 
terminate. Some of these reflected fibres are disposed in relief to constitute 
the columne carne, and reach the auriculo-ventricular zones through the 
medium of the tendinous cords which directly connect these fibrous rings 
with the summits. of the muscular pillars. ; 

Such is the general disposition of the unitive fibres of the ventricles ; 
and it will be seen that they form a superficial and a deep or reflected plane, 
between which are comprised the fasciculi proper to each ventricular pouch. 

The unitive fibres of the ventricles, therefore, form collectively a kind 
of figure 8, the smallest loop of which is at the point of the heart; there 
the fibres are heaped together, leaving in the centre of the loop a very small 
space, through which it is possible to pass a probe into the ventricle, without 
piercing anything but the external and internal serous membranes of the 
organ. 

a Freres or tae Avrictes.—The fibres of the auricles are either 
common to the two cavities, or proper to each. The wnitive fibres con- 
stitute two thin bands—a right and left, carried from one auricle to the 
other. 

The proper fibres are divided into several fasciculi, some of which are 
arranged in rings around the auriculo-ventricular opening; others in inter- 
woven loops, and others, again, in sphincters, which surround the embouchures 
ofthe veins. These fibres are arranged in such a manner that, in contracting, 
they diminish the auricles by their superior and lateral planes and ex- 
tremities, and propel the blood towards the auriculo-ventricular openings. 

(The arrangement of the muscular fibres constitutes the most remarkable 
feature in the anatomy of the heart. We have seen that the auricles, as well 
as the ventricles, possess not only fibres proper to each compartment, but 
also unitive or common fibres which assure the simultaneousness in action 
of the similar or homologous cavities. Besides, the fibres of the auricles 
and those of the ventricles are distinct. and not continuous; so that, from 
their independence of each other, it results that these two sections of the heart 
may act separately, and contract, not simultaneously, but alternately, a con- 
dition indispensable to the free course of the blood. The extremcly fine 
and close connective tissue uniting the muscular fibres, is another peculiarity 
of structure that must be favourable to the solidarity of their action, 
which ought to be simultaneous. Adipose tissue is only found in the 
grooves on the surface of the organ, around the vessels lodged in them, and 
particularly at its base, between the large arterial trunks.) 

__C. Vesseis anp Nerves or tur Huart.—Blood is carried to the muscular 
tissue of the heart by two large vessels, the coronary arteries. They emanate 
from the trunk of the aorta, at the sigmoid valves, and each divides into 
two principal branches : one passing along the horizontal, the other in the 
vertical furrow of the heart, Collectively, these arteries form two circles, 
which surronnd the heart in intersecting it at a right angle in the auriculo- 
ventricular groove. 

The blood is carried from the walls of the heart by a single but impor- 
tant vein, which empties itself into the right auricle. 


THE HEART. 511 


The lymphatics follow the arteries, passing along the visceral layer of 
the pericardium, and ontering the cluster of glands situated near the base of 
the heart. (The endocardium, especially in the ventricles, has a network 
of fine lymphatics, the walls of which consist of only a single layer of 
intimately-adhering cells. None have been traced upon the chorde tendines, 
and very few upon the auriculo-ventricular and semilunar valves.) 

The nerves of the heart, furnished by the cardiac plexus, come from the 
pneumogastric and sympathetic. ‘The tubes are small, and show some cells 
in their course. In addition to these, the heart is provided with a particular 
ganglionic system, to which Remak has called attention. It is believed that 
there exist three ganglia in different points of the cardiac parietes, and that 
on these depend the movements of the organ. (According to Carpenter, the 
nerves of the heart are: 1, Minute ganglia and fibres of the sympathetic, 
situated in the walls of the cavities, and especially in the auriculo- 
ventricular furrow; 2, Fibres derived from the cervical portion of the 
sympathetic, and passing to the cardiac plexus, between the aorta and 
pulmonary artery ; 3, Cerebro-spinal fibres entering the inferior cervical or 
stellate ganglion, and proceeding to the same plexus, and probably derived 
from a centre situated in the brain and spinal cord; and, 4, Fibres coursing 
in the vagus, and originating in a centre situated in the medulla oblongata. 
The first three of these ganglia and fibres probably collectively con- 
stitute the excito-motor system of the heart, the fourth is an inhibitory, 
restraining, or regulo-motor centre.) ; 

D. Serous Membranes or tHE Heart.—These are three in number: 
two internal, or endocardial, one of which occupies the right, the other the 
left cavity; and an external, a dependency of the fibro-serous sac which 
contains the heart. 

1. Internal serous membranes, or endocardia.—These two membranes, 
independent, like the cavities they line, are spread over the auricular and 
ventricular walls, covering the tendinous or muscular columns attached to 
these walls, and are prolonged into the veins and arte- 
ries, to form the internal tunic of these vessels. At 
the auriculo-ventricular and arterial openings, they con- 
stitute a duplicature for the valves situated there. 
These valves are, therefore, due to the projection of a 
circular fold of the endocardia, between the two layers 
of which a thin prolongation of the fibrous zones from 
the base of the heart is insinuated. In the auriculo- 
ventricular valves there is also found, beneath the 
internal or superior layer, muscular fibres furnished by 
the auricles. 

The endocardium of the right heart has a red tint, 
which is deepest in the ventricle. In the left heart, 
this tint is slightly yellow, especially in the walls of 
the auricular appendix, which may be attributed to the 
presence of a thin layer of yellow elastic tissue that 
covers the adherent face of the membrane. EPITHELIUM OF THE 

The endocardium consists of three layers: 1, A ENDOCARDIUM. 
thin bed of white fibrous tissue, connecting it to the 1, Nucleated cells as- 
: suming the fusiform 
muscular structure; 2, A middlo layer, composed of figure; 2, Polygonal 
elastic tissue which is very abundant in the auricles; — pucleated cells. 
and 8, An epithelium, consisting of a single or double 
layer of somewhat elongated, polygonal, pavement nucleated cells.) 


512 THE CIRCULATORY APPARATUS. 


9. External serous membrane.—This is the visceral lining membrane of 
the pericardium, the description of which follows. 


5. The Pericardium. (Fig. 234, c.) 


Preparation.—Place the animal in the second position, and remove the sternal ribs by 
separating the cartilages and luxating their costo-vertebral articulations. This pro- 
cedure permits the study of the situation and general dispozition of the heart and 
pericardium, But in order more easily to examine the reciprocal arrangement of these 
two parts, it is necessary to extract tuem from the thoracic cavity by tearing through the 
sternal insertion of the pericardium. 


The pericardium, or proper serous membrane of the heart, is a membranous 
sac inclosing that organ, fixing it in the thoracic cavity, and favouring its 
movements by its polished surface. 

This sac is formed by a fibrous layer, within which is spread a serous 
membrane, divided into two parts—one parietal, the other visceral. 

The fibrous layer of the pericardium presents somewhat the general form 
of the heart Its internal surface is covered by the parietal portion of the 
serous membrane. The external surface corresponds to the two lamine of 
the mediastinum. Its summit (or apea), depressed on each side, and elon- 
gated from before to behind, is firmly attached to the superior face of the 
sternum, from the fourth rib to the origin of the xiphoid cartilage. By 
its base, it is fixed to the large vessels going to and leaving the heart, where 
it is continuous with their cellular sheath, and where it sends some fibres to 
the longus colli. ; 

The serous membrane of the pericardium has been well compared by 
Bichat to a cotton night-cap, the external part of which would represent the 
parietal layer, and the inverted part the visceral division of that membrane. 
The parietal layer adheres in the most intimate manner to the internal face 
of the fibrous tunic, and is seen to be reflected, to form the visceral portion, 
around the pulmonary arteries and the aorta to a ccrtain distance from 
their origin, and on the pulmonary veins. The visceral layer envelops 
in common the two arterial trunks, covers a small part of the vene cave, 
particularly the anterior, spreads over the insertion of the pulmonary veins, 
and then descends on the auricles and ventricles. The free face of this 
layer is in contact with that of the parietal layer; the adherent face is 
applied to the tissue of the heart or that of the large vascular trunks, except 
at the horizontal and vertical grooves, where it rests on the coronary vessels, 
and on the mass of adipose tissue constantly accumulated on their track. 

In the living animal, the cavity of the pericardium is never entirely 
filled by the heart, whose movements are, therefore, allowed much more 
liberty. Otherwise, as it does not contain any gas, nor a sensible proportion 
of fluid," its walls are immediately applied to the surface of the heart. 

Blood reaches the pericardium by the mediastinal arteries. Its walls 
receive some sympathetic nerve-fibres. 

(The pericardium is composed of a fine network of elastic fibres adhering 
to the muscular structure of the heart by one surface, and covered by a 
single or double layer of tesselated epithelium on the other. Gurlt, in 1867, 


> With horses in health, the fluid exhaled into the pericardium is barely sufficient to 
moisten and lubrify the free surface of its serous membrane. But in those worn-out and 
enfeebled by age. privations, or disease, it is not rare to see it accumulated in greater or 
less quantity. To verify this, however, an examination ought to take place immediately 


after death, as the accumulation of fluid in the serous cavities by cadaveric exhalation is 
common in all animals, : 


THE HEART. 513 


described a thin muscle, nine inches long, situated between the pericardium 
and the diaphragm of the Harse.) 


6. Action of the Heart. 


The function of the heart is to maintain the circulation of the blood, by 
the rhythmical contractions of its two pouches. The right pouch sends 
that fluid to the lungs, whence it returns to the left pouch, and from 
this it is thrown into all parts of the body, and is brought back again to the 
right heart. These contractions take place simultaneously in the two cardiac 
compartments. 

In taking the heart at the moment when it is in a state of-repose: that 
is,in the intervals between the two contractions, we find that its two 
pouches are being rapidly filled with the blood brought to it by the venous 
openings. When sufficiently replete, the auricles slightly contract and 
push a portion of the fluid they contain into the ventricles: these contracting 
immediately after, to propel the blood into the arterial ramifications. This 
passage of the blood into the arteries is a necessary consequence of the 
contraction of the ventricles, as at the moment of this contraction the 
auriculo-ventricular valves are raised, and so prevent the reflux of the 
blood into the auricles. This fluid is then forced to enter the arterial 
orifices, whose valves are separated under the impulsive effort communicated 
to the column of blood. When the heart returns to a state of repose, these 
valves fall down, preventing the return of the blood into the ventricular 
cavities; while the mitral and tricuspid valves subside against the walls of 
these cavities, and thus again allow the passage of blood through the 
auriculo-ventricular openings. 

By the term systole is designated the contraction of the heart’s cavities, 
and by diastole, the repose or relaxation of its tissue. For each revolution 
of the heart there is, therefore: 1, The general diastole of the organ, during 
which the two cardiac cavities are filled by the afilux of venous blood; 
2, The systole of the auricles, the effect of which is the repletion of the 
ventricles ; 3, The systole of the ventricles, propelling the blood into the 
arterial systems ; after which comes another period of general diastole. 


DIFFERENTIAL CHARACTERS IN THE HEART OF OTHER THAN SOLIPED ANIMALS. 


In the Ox, Sheep, and Goat, the ventricular mass of the heart is more regularly 
conical than in Solipeds; it has three longitudinal furrows, one of which is accessory 
and passes behind the (left) ventricle. : 

In the Ox two small bones, named bones of the heart, are found in the substance of 
the aortic zone. The largest is in the right side, at the point where the arterial ring is 
approximated to the auriculo-ventricular zones: the other, situated in the left, is perhaps 
not constantly present. The first is triangular in shape, curved to the right and its 
base directed upwards. ‘The right face lies against the auriculo-ventricular opening ; 
the left is covered by the walls of the aorta at its commencement. It is about an inch in 
length. (The Ox’s heart averages from about 33 to 42 lbs., that of the Sheep from 53 to 
voz. It is more elongated and pointed in Ruminants than in the Horse or Pig. The 
large bone in the Ox’s heart is elongated from before to behind, flattened laterally and 
curved to the left; its surtace is roughened, and its length is sometimes about 2 inches, 
The left, or small bone, is usually flattened on each side and triangular, one of its points 
is directed forwards, another backward, and a third inferiorly ; its length is about three- 
quarters of an inch when fully developed. Besides the Ox, a small cross-shaped bone is 
found in the heart of the Sheep, Pig, Camel, Deer, Giraffe, and sometimes in the Horse. 
Remak found in the pericardium of the Ox, at the border of the left auricle, a row of 
villi similar to those discovered in the border of the chtcken’s heart.) : 

The heart of the Pég resembles that of the Horse ; its direction is a little more oblique, 


514 THE CIRCULATORY APPARATUS. 

and the pericardium is fixed to the sternum from the third rib to the xiphoid appendix, 

as well as to the diaphragm. (The cartilage is not ossified until a late period.) : 
In the Dog and Cut, the heart is oval or nearly globular. It is almost entirely resting 

on the upper face of the sternum; its anterior face has become the inferior, and its 

point, directed backwards, touches the anterior surface of the diaphragm, The pericardium 

is attached to the aponeurotic centre of the diaphragm. 


COMPARISON OF THE HEART OF MAN WITH THAT OF ANIMALS, 


The human heart is ovoid, and similar to that of the Carnivora; the ventricular mass ig 


HUMAN LUNGS AND HEART; FRONT VIEW. 


1, Right ventricle 2, Left ventricle; 3, Right auricle; 
4, Left auricle; 5, Pulmonary artery; 6, Right 
pulmonary artery; 7, Left pulmonary artery; 8, 
Ligament of ductus arteriosus; 9, Arch of aorta; 
10, Superior vena cava; 11, Arteria imnominata; . 
Right subclavian vein, with the artery behind it; 
18, Right common carotid artery and vein, 14, Left 
vena innominata, 15, Left carotid artery and vein; 
16, Left subclavian vein and artery; 17, Trachea ; 
18, Right bronchus; 19, Left bronchus; 20, 20, 
Pulmonary veins; 21, Superior lobe of right lung; 
22, Middle lobe ; 23, Inferior lobe ; 24, Superior iobe 
of left lung; 25, Inferior lobe. 


the aponeurotic centre of the diaphragm: 
and it adheres to the posterior face of the sternum. 


not scute at its apex, as in 
Solipeds and Ruminants. Its 
direction is modified in conse- 
quence of the antero-posterior 
flattening of the chest. It is 
situated across the median plane 
of the thorax, its right face in 
animals has become the anterior 
face in Man, and is applied to the 
sternum; the anterior border is 
in him the right border, and the 
posterior the left border. 

The organ is suspended ob- 
liquely downwards, forwards, and 
tv the left; consequently, the right 
auricle is to the right of the 
sternum, between the third and 
fourth ribs, and the point on a 
level with the sixth left inter- 
costal space. The auricular ap- 
pendages, paiticularly the right, 
are more rounded and bulging 
than inanimals. The pulmonary 
veins, four in number, open on 
the npper face of the left auricle. 

There are no essential differ- 
ences to be noted in its internal 
conformation, We may indicate 
the presence of a fold that passes 
from, the ring of Vieussens to the 
op ning of the inferior vena cava: 
this is the Zustachiun valve. We 
may ulso mention the ‘hebesian 
valve at the entrance of the coro- 
mary vein. 

The fibrous rings and muscular 
fasciculi are disposed as in the 
Horse. 

The pericardium is a conical 
sac; but instead of its base being 
presented upwards, it rests against 


its summit is lost among the large vesrels, 


SECOND SECTION. 


THE ARTERIES, 


CHAPTER I. 


GENERAL CONSIDERATIONS. 


Tue name of arteries is given to the centrifugal vessels, which carry 
the blood from the heart to the various organs. These vessels proceed from 
the heart by two trunks, which are perfectly independent in the adult 
animal; they originate, one in the right ventricle, the other in the left. 

The first of these trunks, destined to carry the dark blood, is the pul- 
monary artery. The second conveys the red blood, and is named the aorta. 
There exist, therefore, two groups of arteries; the pulmonary system, and 
the aortic system. 

GrnerRaL Form.—Single at their origin, the two arterial systems soon 
divide into less voluminous trunks, which again subdivide into successively 
decreasing canals, until at last their diameter becomes reduced to an extreme 
degree of tenuity. In a word, the arterial trunks present the ramous dis- 
position of dicotyledonous plants. The total volume of the secondary trunks 
exceeds that of the primary trunk, and the same relation exists between the 
respective dimensions of the branches and their ramifications, to the ultimate 
divisions of the artery. In tracing all the ramifications of one of these systems 
to a single canal, it will then be found that this canal is incessantly increas- 
ing from its origin to its termination, and that it represents a hollow cone 
whose apex corresponds to the heart. 

Form or tHe Arrertes.—Each arterial tube affects a regularly cylin- 
drical form, whatever its volume may be. When the diameter of these 
vessels is measnred at their origin and their termination, between two 
collateral branches, no sensible difference is perceived. 

Mone or Oricin.—The arterial ramifications are detached in an angular 
manner from the parent branches which give them crigin. Sometimes the 
angle of separation is more or less acute—this is most frequently the case ; 
sometimes it is at a right angle, and at other times it is obtuse. It will be 
readily understood that the opening of this angle exercises a somewhat 
marked influence on the course of the blood ; for example, the blood from 
a principal vessel, in passing into the canal of a secondary one which springs 
from it at an obtuse angle. must experience a notable check in its impetus, 
because of the change in direction it has to encounter, on the contrary, the 
rapidity of the current is not modified to any appreciable degree in those 
vessels which separate from their trunk of origin at a very acute angle. 
Towards the point of separation, there is always remarked, in the interior of the 
vessel, a kind of spur whose sharp border is towards the heart, thus dividing 
the current of blood and diminishing the resistance. This spur resembles 
in its disposition the pier of a bridge, against which the waters are divided 
to pass on each side. (When a short trunk divides abruptly into several 
branches, proceeding in different directions, it is termed an amis. A very 


peculiar feature in the division of arteries, however, and one which will be 


516 THE ARTERIES. 


made amply conspicuous in the following description, is their bifurcation or 
dichotomous arrangement, which prevails so largely.) : 

Courss.—In the course pursued by an artery, it is necessary to consider 
the situation occupied by the vessel, its direction, relations, and the anastomoses 
which establish communication between it and the neighbouring vessels. ; 

Situation.—The arteries tend constantly to recede from the superficial 
parts: to become lodged in the deep-seated regions, and in this way to be 
removed from the hurtful action of external causes, a tendency all the more 
marked as the arteries are more considerable in volume, and which ceases to 
be manifested in the less important ramuscules. These vessels, therefore, 
occupy either the great cavities of the trunk, or the deep interstices on the 
internal face of the members; when they pass over an articulation, it is 
always on the side at which flexion occurs. But in the limbs, for instance, 
the joints are flexed alternately in opposite directions, and it then happens 
that the arteries in these regions have a slightly helicoid (or spiral) disposi- 
tion. This is evident in the case of the femoral artery, which passes round 
the inner face of the femur to become the popliteal artery ; and also in the 
humeral artery, which is at first situated to the inner side of the scapulo- 
humeral articulation, then turns around the humerus to be placed in front of 
the elbow joint. ; 

Direction—The arteries are sometimes rectilinear, and at other times 
more or less flexous. The latter disposition is evidently intended to prevent 
the dilaceration of the vessels in organs susceptible of elongation and con- 
traction, as may be remarked in the tongue’ or to moderate the impetus of 
the blood, as in the internal carotid arteries. 

Relations—In their course, the arteries may be in contact with the 
viscera, nerves, muscles, bones, skin, and connective tissue. 

a. In nearly every part of the body, the arteries maintain the most 
intimate relations with the veins: sometimes with two of these vessels, when 
the artery is placed between them ; sometimes with only one, which is always 
more superficial. 

b. The arteries are usually accompanied by nerves belonging to the 
cerebro-spinal or ganglionic systems. Those of the latter category are 
distinguished by the reticular interlacing they form around the visceral 
arteries; their structure will be alluded to presently. 

c. Lodged for the most part in the interstices of the muscles, the arteries 
contract relations with these organs which it is very important to know in a 
surgical point of view. Some of these muscles lie parallel with important 
arteries, and for this reason have been designated satellite muscles ; they 
serve to guide the surgeon in searching for the arteries, by the more or less 
salicnt relief their presence affords beneath the skin. 

It is worthy of remark that the arteries are not included in the fibrous 
sheaths enveloping the muscles; these vessels nearly always occupy, with 
the nerves which accompany them, special lod gments resulting from the 
approximation of several aponeurotic sheaths. When they pass through 
the substance of a muscle, which sometimes happens, they are covered 
by an arch or fibrous ring, which protects them from compression during 
muscular contraction: the arch or ring receiving on its convexity the 
insertion of fibres from the muscle. 

d. Nothing is more common than to see the arteries in direct contact 
with the bones: as, for instance, the aorta, intercostals, &c. Neither is it 
very rare to find a more or less thick muscular layer between the arteries 
and portions of the skeleton. In every case, a Inowledge of the connections 


GENERAL CONSIDERATIONS. 517 


of the arteries with the bones is important to the surgeon; as it enables him, 
temporarily, to interrupt the circulation in these vessels by exercising external 
pressure on the points of their course which correspond to the several bones, 
and thus diminish their calibre by flattening them. 

e. By virtue of their deep situation, the arteries are, in general, distant 
from the skin ; there are, nevertheless, some which course immediately beneath 
the inner face of that membrane; these are only found about the head and 
in the extremities. 

J. Lastly, all the arteries are enveloped by a layer of connective tissue, 
which forms around them a kind of sheath, generally difficult to tear with 
the fingers alone, and which isolates from the neighbouring parts, but chiefly 
the veins. This connective tissue, more or less abundant according to the 
regions, is always loose enough to allow the arteries to roll and be displaced 
with the greatest facility, and thus to glide away from incisive bodies 
accidentally introduced into the tissues. 

Anastomoses.— Very often the arterial branches are united to each other by 
communications, which have received the name of anastomoses, and which 
assure the distribution of the blood in regulating its flow. There are 
distinguished : 

1. Anastomoses by convergence : formed by two vessels joining at their 
terminal extremity in an angular manner, to form a third and more 
voluminous trunk. 

2. Anastomoses by arches or by inosculation: due to the junction of two 
principal branches, which are inflected towards cach other, meet, and unite to 
form a single and curvilinear canal. 

3. Anastomoses by transverse communication : represented by ramifications 
thrown transversely between two parallel arteries. 

4. Mixed or composite anastomoses: in which are found a combination of 
the different types enumerated above. 

A knowledge of the anastomoses of vessels is of the highest practical 
interest; as these communications permit the surgeon, in cxtreme cases, to 
tie the principal artery of a region without the latter experiencing any 
considerable nutritive disturbance; the blood continuing to arrive by the 
collateral vessels which, at first very small, gradually dilate from the 
excentric pressure to which their walls are submitted. But these anasto- 
moses, if they offer this immense advantage, have also their inconveniences : 
we allude to the difficulties experienced in arresting hemorrhage in wounds 
of certain organs, owing to the relations of the principal vessel with its 
communicating collaterals. 

Move or Distrisurion.—The branches an artery distributes in the 
neighbouring organs are distinguished as terminal and collateral. The 
arterial trunks, after finishing a certain course, divide into several branches— 
nearly always two, which, as new arteries, continue the primary vessel and 
take the name of terminal branches, because they really begin at the terminal 
extremity of that vessel. ; 

The collateral vessels originate at various distances along the course of 
the arteries, and proceed in a lateral direction: these collateral branches 
increase in number as the arteries become more superficial, the ramifications 
being particularly abundant around the articulations, and in the organs which 
are prominent on the surface of the body. This abundance of vessels is 
intended to maintain a moderate temperature in those parts which, by their 
structure or situation, are exposed to sudden chills. 

The distinction between the terminal and collateral branches of arteries 

36 


518 THE ARTERIES. 


is not always easy to establish, and is far from having an absolute value ; it 
possesses, nevertheless, some importance, as it greatly facilitates description. 

Trermination.—The arteries terminate in the substance of the tissues 
by extremely fine and numerous ramuscules, which so frequently anastomose 
with each other as to form a plexus or microscopical nctwork, whose meshes 


Le a 
ne As 


WEB OF FROG’S FOOT STRETCHING BETWEEN TWO TOES, SHOWING THE BLOOD- 
VESSELS AND THEIR ANASTOMOSES, 


a, a, Veins; b, 6, b, Arteries, the capillaries being between. 


are very close. These ramuscules constitute the capillary system, which 
again gives rise to ramifications of gradually increasing size, the veins. 
The capillary system is, therefore, nothing more than 
a network of microscopical canals intermediate to the 
arteries and veins. 

In the erectile tissues, the mode of termination is 
different: the small arteries sometimes opening directly 
into the cells placed at the origin of the veins, without 
passing through a capillary plexus. In describing the 
genital organs we shall notice, in detail, the termination 
of the arteries in the cavernous tissues. 

Srructure.—The walls of arteries offer a certain 
rigidity, which permits these vessels to remain open 
when they are emptied of blood. The ancients believed 

this was their normal condition, and that they were 
mipen-VESSES: filled with air during life. This was a grave error, as 
"4 Lect pee “ a perfect vacuum exists throughout the entire circulatory 
Magnified 350 Gee system. The gaping of the arteries must be attributed 
meters, solely to the physical properties of their walls. 
‘ These wails comprise three superposed tunics: an 
internal, middle, and external. 
The internal tunic is continuous with the endocardium of the left heart 


Fig. 267. 


EPITHELIAL CELLS OF 


GENERAL CONSIDERATIONS. 


519 


on the one part, and on the other with the capillaries and veins. For a 
long time it has been assimilated to a serous membrane, but it has not 
absolutely the same texture. It is composed of a simple epithelial layer 
which is in contact with the blood, and is formed by fusiform cells that 


Fig. 268, 


FENESTRATED MEMBRANE 
FROM THE CAROTID 
ARTERY OF THE HORSE. 
Magnified 350 diame- 
ters, 


slightly bulge in the situation of their nucleus. 
ahese cells sometimes become detached, and are 
carried about in the nutritive fluid, in which, after a 


certain period, they resemble 
more or less mis-shapen blood- 
globules. The epithelium lies 
upon a layer of amorphous 
elastic tissue, perforated by 
openings, and named the fene- 
strated membrane ; on its cx- 
ternal face are proper elastic 
fibres passing in a longitudinal 
direction. 

The middle tunic is remark- 
able for its thickness, its elas- 
ticity, and the yellow colour it 
offers in the principal vessels. 


Itis composed of a mixture of elastic fibres, as well as 
smooth muscular fibres, the first constituting a kind of 
network, in the meshes of which the contractile fibres 
are disposed in a circular manner around the vessels. 


NETWORK COARSE 


OF 
ELASTIC TISSUE FROM 
MIDDLE COAT OF PUL- 
MONARY ARTERY OF 
THE HORSE, THE FIBRES 
BEING PIERCED WITH 


CIRCULAR OPENINGS. 
Magnified 350 diame- 
ters. 


as that just described, b 
the smallest capillaries, 
ong 


brane, in which (obl 


The proportion of these two 
elements varies with the size 
and situation of the artery. 
In the large trunks, such as 
the aorta, the elastic is more 
abundant than the contractile ; 
in the middle-sized vessels 
they are about equal; but in 
the small arteries, in which 
the contractile force of the 
heart is lost because of their 
distance from it, the muscular 
fibres almost exclusively com- 
pose the middle tunic. 

The external tunic is only 
a layer of connective tissue, 
with some longitudinal reticu- 
lated elastic fibres in its deeper 
part. Though this tunic is 
very thin, yet it is strong; as 


Fig. 270, 


TRANSITION OF A MINUTE 
ARTERY OF THE BRAIN 
INTO CAPILLARY VES- 
SELS. 

1, Minute artery; 2, Tran- 
sitional capillary; 3, 
Coarse capillary with 
thick coat, represented 
by a double contour 
line; 4, Fine capillary, 
with single contour. 
The nuclei are seen 
widely scattered in 4 
and 3; more closely con- 
gregated in 2; and still 
more so in 1, where they 
form an epithelium.—a, 
Transverse elongated 
nuclei of muscular cells, 
the incipient muscular 
coat of the artery. 


a ligature tied tightly around en artery will rupture 


the other tunics, but not this. 


The structure of the capillaries is not the same 


ut is modified in proportion as they are fine. 
the walls are formed by a thin amorphous mem- 
) nuclei are somewhat regularly disseminated; in 


In 


medium-sized vessels, another layer containing transverse nuclei is observed ; 
and in the largest capillaries—those immediately succeeding the small 


a 


520 THE ARTERIES. 


arteries, these two nucleated layers are enveloped by a thin tunic of con- 
nective tissue. : See, 

(Some authorities state that the walls of the very finest capillaries are 
merely composed of closely-adhering cells, without any basement membrane, 
which only becomes apparent in tubes of a large diameter. ) 

Vessels and nerves—The arteries are provided with vessels termed vasa, 
rasorum, which are furnished either by the arteries themselves, or by neigh- 
bouring vessels. These vasa vasorum form a superficial network with quad. 
rilateral meshes, and a deep plexus whose principal branches are helicoidal. 
The majority of anatomists believe that this plexus dues not extend beyond 
the external tunic. : . . ; 

The lymphatic vessels maintain intimate relations, in certain regions, 
with the capillaries. In the brain and spleen there has been discovered, 
around the arterial capillaries, a vessel that completely envelops them, 
and which has been named the lymphatic sheath. 

The nerves, designated vasa motors, accompany the vessels and penetrate 
the muscular tunic, for which they are naturally destined. These vaso- 
motor filaments join the branches of the capillary plexuses, and form, at the 
points where they meet each other, ganglionic enlargements, from which arise 
the fibres of Remak, the termination of which is unknown. 

ANoMALIES IN THE ARTERIES.—In their arrangement, the arteries very 
often present anomalies which the surgeon should be guarded against. 
These usually belong to their number, their point of origin, and their 
volume. In apurely anatomical and physiological point of view, however, 
these anomalies are of no moment; as it matters little whether the blood 
comes from one source rather than another, or that a collateral vessel be- 
comes the principal at the expense of the parent trunk, provided its rela- 
tions are not altered, and the principle of immutability of connections is 
maintained. 


PREPARATION OF THE ARTERIES.—This requires two successive operations: 1, In- 
jection: 2, Dissection. 

Injection of the artertes.—The object to be attained in injecting these vessels, is to 
introduce into their interior a solidifiable substance which will cause them to assume the 
volume and conformation they presented during life, when they are filled with blood. 

Tallow, coloured by lamp-black, is the most convenient and generai injecting mate- 
tial. Sometimes a solution of gelatine, with the addition of a certain quantity of plaster 
of Paris, is used; but this is seldom employed in the French schools. A copper or 
brass syringe, and a canula with a stop-cock to fit on its extremity, are the only instru- 
ments necessary to propel these matters into the arteries. 

The following are the details of the operation, when it is desired to make a general 
injection :—The animal being placed on a table, the carotid artery is exposed by an 
incision in the jugular channel, and opened longitudinally.* A ligature is applied above 
the opening, and the tube, with the stop-cock, is firmly fixed in the cavity of the 
artery towards the heart by a second ligature. The injection, previously prepared, is 
taken up by the syringe, which is fitted into the tube, and the piston pushed, in order 
to drive the contents of the instrument into the arterial canals. 

To perform the operation successfully, the following precautions are to be attended 
to: 1. Inject the vessels of an animal killed by effusion of blood, and yet warm, 2. If 
suet is employed, and which is always to be recommended, make it so hot that the finger 
can scarcely endure it. When it is colder than this it solidifies too quickly, and when 
hotter it shrivels up the sigmoid valves, passes into the left ventricle, and trom thence 
into the auricle and pulmonary veins; an accident generally attributed to the too power- 
ful force applied to the piston of the syringe. 3. Do not make any undue pressure on 
the piston, though this does not strain the sigmoid valves so frequently as is believed. 
4. Cease injecting when the arteries react, by their elasticity, on the piston, so as to 
drive it back in the syringe. 

In order “to insure the retention of the injected matter in the arteries, and prevent 
the sigmoid valves being forced a cork may be intioduced into the aorta througn the 


PULMONARY ARTERY. 521 


left ventricle, and firmly tied there by a strong ligature; the cork should have a trauas- 
verse notch for the reception of the ligature. 

Instead of injecting by the carotid, a long curved canula may be fixed to the aorta 
itself, after making an opening in the left side of the chest, on a level with the heart, 
by the ablation of two segmeuts of the ribs, and incising the pericardium and left 
auricle to introduce it. This mode allows the tallow to be injected at a very high 
temperature, and gives the best results, for it can then penetrate to the capillaries, if we 
ouly know how to manage it; in certain organs the injected matter may even be made 
to return by the veins. 

But no matter what procedure may be adopted, there are several parts into which 
the tallow can never be made to enter by a general injection : these are the four extre- 
mities. So that a special operation must be resorted to, in order to fill their vessels. 
After separating them from the trunk, by sawing them through above the knees and 
hocks, they should be allowed tv steep for two houis in water, constantly kept up to a 
temperature of 140° to 160° Fahr. ut most ; it is then easy to inject them, either by the 
posterior radial artery, or the: anterior tibia!, alter tying those branches which may be 
open at the cut extremity of the limbs. 

If it is desired to make partial injections in other parts of the body, it will be better 
not to separate them from the trunk; but only to tie those vessels which anastomose 
between the arteries to be filled and those which are not. For example, to inject the 
arteries of the head, it suffices to push the mixture into one of the common carotids, 
after ligaturing the other in the middle of the neck, and both vertebrals in the space 
between the two portions of the scalenus muscle. 

We may give the tallow more fluidity, and a higher degree of penetration, by mixing 
with it a little spirits of turpentine ; or mvre consistence, in adding to it a small proportion 
of beeswax, 


The two following mixtures are borrowed from Cruveilhier’s Anatomy :— 
Tallow Be ae Ro Sah, ah ties, 8 es ee a ye “Oepaitits 
Turpentine; 2 4 68 8 @ a « wm we & 2 
Ivory Black, mixed with spirits of turpentine . 2 

For preservative injections :— 

Beeswax . « © «© © © # & % 
BOW: So a eg ee Se Bae ok SB es 
Vermilion, indigo, or Prussian blue, previously 
mixed in spirits of turpentine. . . . . Asufficient quantity. 

Of course it is well understood that these instructions are only intended for the 
dissecting-room injections necessary for the study of descriptive anatomy. To inject the 
capillaries, it is requisite to have recourse to other substances and other procedures. 
Suffice it to say that these injections are made with eold fluids, such as varnish, alcohol, 
or spirits of turpentine, holding in suspension extremely fine colouring matter, gum arabic 
dissolved and coloured by a substance also in solution, ete., or, better still, colours 
rubbed up in oil, and mixed with spirits of turpentine. f ; 

Dissection of the arteries—There are no general rules to be given for the dissection 
of arteriez. 


” 
” 


- . I part 
3 


” 


CHAPTER IL. 
PULMONARY ARTERY (Fig. 258, e). 


Preparation.—The pulmonary artery is not filled by the general injection mentioned 
above, It is directly injected by propelling the tallow into the right heart by the 
anterior vena cava, after tying the posterior vena cava. 

The pulmonary artery springs from the infundibulum of the right 
ventricle, is directed upwards and then backwards, describing a curve whose 
concavity is infero-posterior, and arrives above the left auricle, where it 
divides into two secondary arteries, one for each lung. These arteries 
enter the pulmonary tissue with the bronchi, and exclusively ramify in it. 

The pulmonary artery accompanies the trunk of the aorta on the right 
side, and is enveloped with it in a serous sheath, a dependency of the visceral 
layer of the pericardium. At its origin, it is flanked before and behind by 


522 THE ARTERIES. 


the appendages of the auricles and the cardiac vessels. About the middle 
of its course, it is united to the posterior aorta by means of a yellow elastic 
fibrous cord (the ligamentum arteriosum), the remains of the ductus arteriosus 
which, in the foetus, establishes a large communication between these two 
ig. 258, e). 

enn of Ne pulmonary artery are much thinner than those of the 
aorta, and are yellow and elastic, as in the other canals of the same order. 
We remember, however, having seen them in an Ass, formed almost entirely 
of red muscular fibres, analogous to the fasciculi of the heart. ; 

It may be repeated that the pulmonary artery conveys into the lungs 
the dark blood carried to the right heart by the veins of the general 
circulation. 


CHAPTER III. 
THE AORTA, 


Ir we take a general survey of the aortic trunk, we will find that it arises 
from the base of the left ventricle, ascends to beneath the dorso-lumbar 
column, curving backwards and downwards, and reaches the entrance to the 
pelvis, where it terminates by four branches. It furnishes, besides, about 
2 to 24 inches from its origin, a secondary trunk, which soon divides into 
two new arteries, the right and largest of which gives off a particular 
trunk, the common origin of the two long vessels destined for the head. 

This disposition permits us to recognise in the aorta seven principal 
sections : 

1. The aortic trunk or common aorta: the source of all the arteries 
belonging to the red-blood system, aud giving rise to the anterior and 
posterior aorta. It only furnishes blood directly to the heart itself. 

2. The posterior aorta: the veritable continuation of the common aorta, 
is distributed to the posterior moicty of the trunk and to the abdominal 
limbs; it terminates by a double bifurcation. 

3. The internal and, 4, external iliac arteries: branches of this bifurcation 
which are almost entirely expended in the posterior limbs. 

5. The anterior aorta: the smallest of the two trunks furnished by the 
common aorta, is chiefly destined to the anterior moiety of the trunk and 
the thoracic limbs. 

6. The axillary arteries, or brachial trunks: these come from the bifurca- 
tion of the preceding artery, and are continued by their terminal extremity 
into the fore-limbs. 

7. The carotid arteries, or arteries of the head: these emanate by a 
common trunk from the right brachial bifurcation. 


Articte I.—Aortic Truxk or Common Aorta. 


The point of departure for all the arteries carrying red blood, the aortic 
trunk proceeds from the left ventricle by becoming continuous with the 
festooned fibrous zone which circumscribes the arterial orifice of that 
cavity. It passes upwards and a little forwards, bifurcating, after a 
course of 2 or 24 inches, into the anterior and posterior aorte. 

Its volume, inferior to that of its two terminal branches, is not uniform ; 
as at its origin, and opposite the sigmoid valves, it presents (an enlargement 


—the bulbus aortee—caused by) three dilatations described as the sinus of 
the aorta (sinus aortici, sinus Valsalve), 


THE POSTERIOR AORTA. 523 


Included, on the right side, in the crescent formed by the auricular 
mass; in relation, on the left side, with the pulmonary artery, which 
is joined to it by means of cellulo-adipose tissue traversed by the 
cardiac nerves, the common aorta forms, with the latter artery, a 
fasciculus enveloped by the visceral layer of the pericardium, which is 
reflected as a sheath around these two vessels. 


Two collateral arteries are given off directly from the aortic trunk: these 
are the cardiac or coronary arteries, 


Cardiac or Coronary Arteries. (Figs. 258, 259.) 


There are two cardiac arteries, a right and left, exclusively destined for 
the tissue of the heart. 

Ricut Carpiac Artery (Figs. 258, 259, 1).—This originates from 
the front and to the right of the aorta, at the free margin of the sigmoid 
valves, and proceeds perpendicularly, or at a right angle, from the trunk, 
passing forwards to the right of the pulmonary artery, beneath the anterior 
auricle ; then to the right and backwards, to reach the auriculo-ventricular 
groove, which it follows till near the origin of the right ventricular furrow. 
Here it divides into two branches: one vertical, descending in this furrow 
to the apex of the heart, which it bends round to the front, and anastomoses 
with an analogous branch of the left coronary artery ; the other is horizontal, 
is smaller than the first, and follows the primitive course of the artery 
in the auriculo-ventricular groove, also inosculating with the artery of the 
left side. 

Lert Carprao Artery (Fig. 258, 2).—This arises opposite the pro- 
ceding, at the same angle of incidence, passes behind the pulmonary artery, 
and divides, under tho left or posterior auricle, into two branches similar 
in every respect to those of the right artery. The vertical branch descends 
in the left perpendicular furrow; the horizontal is lodged in the coronary 
groove ; and both anastomose with the analogous branches of the opposite 
vessel. 

From this arrangement, it results that the heart is surrounded by two 
arterial circles: a vertical, or ventricular, which has been compared to a 
meridian; and a horizontal, or auriculo-ventricular, analogous to an 
equatorial circle, 

In their course, which is more or less tortuous, the coronary artories 
throw out a considerable number of ramuscules, which enter the muscular 
tissue of the heart. The vertical circle gives off branches which are 
entirely ventricular ; while from the horizontal circle come the superior or 
auricular, and inferior or ventricuJar branches. Among the latter there is 
one which, rising from the right artery where it bends at an angle beneath 
the auricle, enters the substance of the right ventricle by passing round 
the pulmonary infundibulum ; its ramifications anastomose with those of a 
similar branch from the left artery, and in this way establish another com- 
munication between the two vessels. 


Arc Le II.—Posrrrion Aorta. 


Course.—This artery is a continuation of the aortic trunk, which it 
nearly equals in volume, and from which it passes upwards and backwards, 
describing a curve whose convexity is antero-superior, and which is known 
as the arch of the aorta. It thus reaches the left side of the inferior face of 
the spine, about the seventh dorsal vertebra, behind the posterior extremity 
of the longus colli muscle, and is then carried directly backwards, following 


524 THE ARTERIES. 


the vertebral bodies, though a little to the left at first ; it gradually inclines 
to the right, however, and reaches the median plane at the pillars of the 
diaphragm. Here it passes through the opening circumscribed by these 
two pillars, enters the abdominal cavity, and extends to the entrance of the 
pelvis, under the spine, still preserving its median position. On reaching 
the last intervertebral articulation, the posterior aorta terminates by a 
double bifurcation, from which arises the external and internal iliac arteries, 

Relations.—To facilitate the study ot its connections, the posterior aorta 
may be divided into two sections : one thoracic, the other abdominal. 

a. At its origin or arch, the thoracic aorta is crossed to the right by the 
trachea and cesophagus ; on the opposite side, it responds to the pulmonary 
artery and the left lung. For the remainder of its extent, it is comprised 
between the two layers of the posterior mediastinum, and through these 
is in relation with the pulmonary lobes, which are fissured for its reception ; 
this fissure is much deeper in the left than the right lung. Above, it is 
in contact with the bodies of the last twelve dorsal vertebra, and is 
accompanied on the right by the large vena azygos and the thoracic duct; 
the latter is often carried to the left for the whole or a portion of its extent. 

(Remak observed muscular fibres on the external face of the aortic 
arch and thoracic aorta in the Horse, Sheep, and Pig ; the fasciculi they form 
are so large as to be visible to the naked eye.) 

b. The abdominal aorta, enlaced by the abdominal nerves of the great 
sympathetic, corresponds, above, with the bodies of the lumbar vertebree, 
the originating tendon of the diaphragmatic pillars, Pecquet’s reservoir, and 
the common inferior vertebral ligament ; it passes above the pancreas and 
the peritoneum, the latter by its sublumbar layer covering the posterior 
two-thirds of the vessel. On the right, it is accompanied by the posterior 
vena cava, which perhaps it slightly pushes to the left of the median plane. 

Collateral branches.—The arteries emanating from the posterior aorta 
during its long course, very naturally form two classes; some are desig- 
nated parietal, because they are distributed to the parictes of the great 
splanchnic cavities; the others are the visceral branches, destined for the 
organs lodged in these cavities. 

Among the parietal branches, may be noticed : 

1. The intercostal arteries, furnished by the thoracic aorta. 

2. The diaghragmatic arteries, whose origin is placed on the limits of the 
two portions of the vessel. 

3. The lumbar arteries, and the middle sacral artery, springing from the 
abdominal aorta. 

The visceral branches are : 

1. The broncho-cesophageal trunk, emitted by the thoracic portion of the 
aorta. : 

2. The celiac trunk, great mesenteric artery, small mesenteric artery, renal 
arteries, spermatic arteries, and small testicular or uterine arteries, which 
emerge from the abdominal portion. 


Preparation of the posterior aorta and its collateral branches.—Immediately after 
injecting according to one of the modes recommended at p. 519, place the subject in 
the first position, the two posterior members being well extended backwards. Open the 
abdominal cavity, and remove from it the intestines in the manner already indicated. 
The tallow having become perfectly solidified during these necessary manipulations, 
dissection may be proceeded with at once. It is requisite, however, to remove the ight 
and left walls of the thoracic cavity beforehand, by sawing through the last fourteen or 
fifteen ribs at six or seven inches from their superior extremity, and afterwards sepa~ 
rating them from the sternum by the saw, taking the precaution of detaching the peri- 


THE POSTERIOR AORTA. 525 


pheral insertion of the diaphragm. It is recommended to prepare, from before to behind, 
the various visceral branches of the vessel; first, the broncho-cesophageal trunk, then 
the coeliac trunk, next, the great mesenteric artery and the renal arteries, after spreading 
out the intestinal Inass as in figure 271; and, lastly, the small mesenteric and testicular 
arteries, alter arranging the intestines as in figure 272, 


PARIETAL BRANCHES OF THE POSTERIOR AORTA, 
1. Intercostal Arteries. (Fig. 237.) 


The intercostal urteries, placed, as their name indicates, in the intervals 
of the ribs, number seventeen pairs. 

Origin, Course, and Distribution—The last thirteen emanate from the 
thoracic aorta only; the first comes from the cervical artery; and the next 
three are furnished by a special branch of the dorsal artery. 

The aortic intercostals escape at a right angle from the superior plane 
of the trunk, on a level with the bodies cf the dorsal vertebree, and at 
regular intervals. Their origin is nearer that of the arteries on the 
opposite side as they are more anterior, the first two or three arising in pairs 
from a common trunk. 

These aortic intercostals ascend to the vertebral bodies, beneath the 
pleura, in crossing the direction of the sympathetic nervous chain and (the 
arteries of the right side only), in addition, that of the vena azygos and 
the thoracic duct, to the superior extremity of the intercostal spaces, where 
those of both sides divide into two branches: the one inferior, or proper 
intercostal; the other superior, or dorso-spinal. 

The inferior and superior branches of the first four intercostal arteries 
emanate solely from the trunk which furnishes them, and which is the 
superior cervical artery for the first intercostal, and the subcostal branch 
of the dorsal artery for the succeeding three. 

Inferior or intercostal branch—This branch, the most considerable of 
the two, placed at first beneath the pleura, then between the two intercostal 
muscles, is lodged, along with a satellite vein and nerve, in the furrow on 
the posterior face of the rib, and descends to the inferior extremity of the 
intercostal space, where it terminates in the following manner: the first 
twelve or thirteen branches anastomose with the intercostal ramifications 
of the internal thoracic artery and its asternal branch; the others are 
prolonged into the abdominal muscles, where their divisions communicate 
with those of the anterior and posterior abdominal arteries, as well as with 
the circumflex iliac. 

In their course, these intercostal branches give arterioles to the pleure, 
the ribs, and the thoracic muscles, with the perforating ramuscules which 
cross these muscles to ramify in the skin and the panniculus carnosus, but 
which, of course, are absent where the pectoral wall is covered by the thoracic 
limb. 

Supertor or dorso-spinal branch.—This passes directly upwards to be 
distributed to the spinal muscles of the dorsal region and the integument 
covering them, after giving off, when passing the intervertebral foramen, a 
branch which enters the spinal canal by that opening, and is destined for the 
spinal cord and its envelopes. An auxiliary of the middle spinal artery, 
this branch will be studied at greater length when the cerebro-spinal artery 
comes to be described. 

Variations in origin—Not unfrequently the first two pairs of aortic 
intercostal arteries proceed from a single trunk, which thus gives rise. to 
four branches; and this trunk is also often the common source of these four 


526 THE ARTERIES. 


intercostals and the bronchial and cesophageal arteries, when its volume is 
very considerable. It is much smaller when it only gives off the second 
pair of intercostals, which is sometimes the case. 


2. Lumbar Arteries. 


These are five or six in number, and do not differ in their general 
arrangement from the intercostal arteries; they having the same mode of 
origin, the same division into two branches, and the same distribution. The 
superior, or lumbo-spinal branch, is much larger than the inferior, and goes to 
the muscles and integuments of the lumbar region; it also furnishes a 
branch to the spinal cord. The znfercor branch passes above the large and 
small psoas muscles, giving them numerous twigs, and extending to the 
muscular portions of the transverse and small oblique abdominal muscles, 
where their ramifications anastomose with those of the circumflex iliac 
artery. 

The last, and sometimes also the second-last lumbar artery, arises from 
the internal iliac trunk; the others emerge directly from the abdominal 
aorta, 

3. Diaphragmatic (or Phrenic) Arteries. 

These are two or three small vessels which spring from the aorta as it 
passes between the two pillars of the diaphragm, and are destined for that 
muscle. The left pillar receives a very insignificant branch ; but the right 
has two, the most considerable of which is alone constant ; it sometimes sends 
subpleural ramuscules to the right lung. 


4. Middle Sacral (Sacra Media) Artery. 


This vessel is often absent, and when it exists is very variable in size, 
though always extremely slender. It arises from the terminal extremity of 
the aorta, in the re-entering angle comprised between the two internal iliac 
arteries, and is carried to the inferior face of the sacrum, where it is 
expended in lateral ramifications which go to the periosteum. It has been 
thought necessary to notice this artery, as it attains a considerable volume 
in Man and some animals, and continues the aortic tree beneath the sacral 
portion of the vertebral column. 


VISCERAL BRANCHES OF THE POSTERIOR AORTA, 
1. Broncho-cesophageal Trunk. 


Destined for the lung, the visceral pleura, the mediastinum, and the 
cesophagus, this artery arises, not, as is generally said, in the concavity of 
the arch of the aorta, but opposite to it, and very near, but to the right 
of, the first pair of intercostals; often even in common with these arteries 
and with the second pair.’ After leaving the aorta, it insinuates itself 
between that trunk and the csophagus, and above the bifurcation of the 
trachea divides into branches, the bronchial arteries. In its short course, it 
gives off the two esophageal arteries and a certain number of innominate 
ramuscules, 

Broncniat ArrerrEes.—The disposition of these two vessels is extremely 
simple; they enter the lung with the bronchi, one to the right, the other to 
the left, and there break up into arborescent ramifications which follow the 
air-tubes to the pulmonary lobules. 

CisopnaceaL ArrEnixs.—These two arteries are placed in the posterior 

1 See Intercostals, 


THE POSTERIOR AORTA. 527 


mediastinum, one above, the other below the esophagus, which they accompany 
for a short distance, from before to behind, to the extremity of that canal. 
The superior esophageal artery, much more voluminous than the inferior, 
inosculates with a branch of the gastric artery. In its course it gives descend- 
ing branches to the cesophagus, and ascending ones to the mediastinum. 
The inferior cesophageal artery also anastomoses with a branch of the 
gastric; most frequently with that noticed above. It likewise furnishes 
ascending and descending divisions; the latter, however, going to the 
mediastinum, and the former to the cesophagus. 
~ Inyominate RamuscuLes.—The innominate ramuscules of the broncho- 
cesophageal trunk do not all come directly from it; there being always 
a certain number which emerge from the bronchial or cesophageal arteries. 
They are more particularly distributed to the trachea, to that portion 
of the cesophagus which is in contact with the posterior extremity of this 
cartilaginous tube, to the bronchial glands, the mediastinum, and the 
pulmonary pleura. Those destined for the latter form on the surface of 
the lung, along with the divisions of the pleural branch furnished by the 
gastric artery, a beautiful plexus. 


2. Celiac Artery or Trunk (or Axis). 


This artery arises at a right angle from the inferior face of the aorta, 
immediately on the entrance of that vessel into the abdominal cavity. 
After a course of from half to three-fourths of an inch at most, in the 
middle of the solar plexus, and beneath the superior face of the pancreas, this 
trunk separates into three branches: a middle, the gastric artery; a right, 
the hepatic artery ; and a left, the splenic artery. 

1. Gasrrio Arrury (the coronaria ventriculi of Man.)—This artery 
descends on the large tuberosity of the stomach, extends to near the 
insertion of the cesophagus, and then divides into two branches: the anterior 
and posterior gastric. The first passes behind and to the right of the 
cesophagus, and crossing the small curvature of the stomach, gains the 
anterior face of that viscus, where it separates into flexuous and divergent 
branches which run beneath the serous membrane, and are carried more 
particularly towards the left cul-de-sac and around the cardia. The second 
vessel is distributed in the same manner to the posterior wall of the organ, 
but chiefly to the right sac. 

Independently of these two arteries, the gastric trunk gives off a third 
and constant branch, which often comes from one of the two branches 
of this trunk, and sometimes also from the coeliac artery itself, or from the 
splenic. This branch accompanies the wsophagus, along with the right 
pneumogastric, crosses the opening of the right pillar of the diaphragm to 
enter the pectoral cavity, and then divides into two branches, each of which 
anastomoses with one of the cesophagea! arteries, and is then thrown over 
the posterior extremity of pulmonary lobe, which it covers with a magnifi- 
cent subpleural reticular arborisation. This gastro-pulmonary artery often 
anastomoses with the superior cesophageal branch only, and goes exclusively 
to the right lung; for the left lung and the inferior cesophageal artery, 
in this case there is a special branch which emanates from the anterior 
gastric. It is not rare to meet with varicties of another kind, but of which 
it is not necessary to speak ; inasmuch as in these pleural ramifications we 
find a disposition common to the whole arterial system: distribution almost 
invariable, origin very inconstant. 

2. Spuento Arrury.—The largest of the three branches of the cceliac 


528 THE ARTERIES. 


axis, this artery is directed downwards and to the left, lying beside its 
satellite vein and the superior face of the left extremity of the pancreas. 
Tt reaches the anterior fissure of the spleen in turning round the large tube- 
rosity of the stomach, passes along the entire length of that fissure, and leaving 
it only near the point of the organ to throw itself into the great omentum, 
where it is named the left gastro-omental artery (or gastro-epiploica sinistra). 
The splenic artery gives off, during its course, very numerous collateral 
hes. These are: 
a External or splenic ramifications, which immediately enter th 
substance of the spleen. . ? 

2. Internal or gastric ramifications, also called the short vessels (vasa 
brevia) in Man, which are comprised between the two layers of the gastro- 
splenic omentum, and go to the great curvature of the stomach, where they 
nearly always divide into two branches: one which ramifies on the anterior 
wall of the viscus, the other on its posterior wall. These vessels inosculate 
with those sent to the membranes of the stomach by the proper gastric artery. 

3. Posterior or omental twigs of little importance, destined for the great 
omentum. 

Left gastro-omental artery.—This artery follows the great curvature 
of the stomach to a distance varying with the state of repletion of that 
viscus, passing between the two layers of the omentum, and inosculating 
with the right gastro-omental artery. The branches it sends off on its 
track are descending or omental, and ascending or gastric ; the latter being 
disposed exactly like the analogous branches emanating directly from the 
splenic artery. 

3. Hepatic Antery.—Applied to the superior face of the pancreas, and 
incrusted, as it were, in the tissue of that gland, whose anterior border it 
follows, the hepatic artery is directed from left to right, passes under the 
posterior vena cava, which it crosses obliquely, reaches the posterior fissure 
of the liver, and enters it with the vena porte to become broken up into 
several branches, whose ultimate divisions carry nutritive blood to the lobules 
of the liver. 

Before reaching that organ, however, the hepatic artery furnishes the 
pancreatic branches, the pyloric artery, and the right gastro-omental artery. 

Pancreatic arteries.—Irregular and very numerous, these branches are 
detached from the hepatic artery on its passage over the superior face 
of the pancreas, and plunge into the tissue of that gland, whose arterial 
blood is chiefly derived from this source. 

Pylorie artery—This vessel arises at the dilatation towards the origin 
of the duodenum, before the hepatic artery enters the posterior fissure 
of the liver, and most frequently by a trunk common to it and the right 
gastro-omental artery. It passes towards the small curvature of the 
stomach, and sends off branches around the pylorus, which anastomose 
with the posterior gastric arteries and the right gastro-omental artery. 

Right gastro-omental artery (gastro-epiploica dextra).—This artery crosses 
the duodenal dilatation inferiorly and posteriorly, to place itself in the 
substance of the great omentum; in doing which it passes along the great 
curvature of the stomach, and anastomoses by inosculation with the left 
gastro-omental artery. In its course, it throws off omental and gastric 
branches, which are analogous to those emanating from the latter vessel. 
Before crossing the duodenum, it also emits a particular branch, designated 
in treatises on Veterinary Anatomy the duodenal artery; this is a somewhat 
considerable division, which follows the small curvature of the duodenum in 


THE POSTERIOR AORTA. 529 


the substance of the mesentery, and joins the first artery belong'ng to the left 
fasciculus of the great mesenteric, after furnishing sume twigs to the 
pancreas, and numerous branches to the duodenum. 

In terminating the description of the right gastro-omental artery, it may 
be remarked that the stomach, owing to the anastomoses uniting that vessel 
with the artery of the left side, is suspended, as it were, in a vertical arterial 
circle, formed by the splenic and left gastro-omental arteries on the one 
part, and the hepatic and right gastro-omental arteries on the other—a circle 
whose concavity sends out on the stomach a great number of divisions, 
which communicate with the arterial ramuscules proper to that viscus. 


8. Great Mesenteric Artery. (Fig. 271.) 


The great mesenteric artery, which almost entirely supplies the intestinal 
mass with blood, is as remarkable for its volume as for its complicated 
distribution. This complexity, together with that of the intestine itself, 
gives rise to some difficulty in the study of this vessel; but this may be 
averted by adopting the mode of description, as simple as it is methodical, 
resorted to in his lectures by M. Lecoq. 

The great mesenteric arises at a right angle from the abdominal aorta, 
at the renal arteries, and at 2 or 24 inches behind the cceliac trunk, from 
which itis separated by the pancreas ; it is directed immediately downwards, 
enlaced by the anastomosing nervous branches of the solar plexus, and divides, 
after a course of from 1 to 131 inches, into three fasciculi of branches, which 
are distinguished as left, right, and anterior. The left fasciculus goes to the 
small intestine ; the right is distributed to the terminal portion of that intes- 
tine, to the cecum, and to the first portion of the loop or flexure formed by 
the large colon; the anterior is carried to the second portion of that flexure, 
and to the origin of the small colon. The order in which these three fasci- 
culi have been indicated will also be that followed in their description ; it 
has, as will be observed, the advantage of recalling to the memory the 
regular succession of the various parts of the intest:ne, and consequently 
the passage of the food in this important portion of the digestive canal. 

A. Arteries oF THE Lert Fascicuius (Fig. 271, 2)— These arteries 
number from fifteen to twenty, and are named the ARTERIES OF THE SMALL 
INTESTINE (vasa intestini tenuis), because of their destination. All spring at 
once trom the great mesenteric artery, either separately, or several in 
common, and pass between the two layers of the mesentery to gain the 
intestine. Before reaching the small curvature of that viseus, each divides 
into two branches, which go to meet corresponding branches from the 
neighbouring arteries, and to anastomose with them by inosculation ; from 
this arrangement results a series of uninterrupted arterial arches, whose 
convexity is downwards, and which exist for the whole length of the intestine 
opposite, and in proximity to, its concavity. From the convexity of these 
arches emanate a multitude of branches that arrive at the inner curvature 
of the intestine, and whose divisions pass to each of the faces of that viscus to 
rejoin and anastomose on its great curvature. These divisions are situated be- 
neath the peritoneum or in the muscular layer, and send the majority of their 
ramuscules to the mucous tunic, which is therefore distinguished by its great 
vascularity : a feature common to all the hollow organs in the abdominal cavity. 

1 This trunk of the great mesenteric is usually, in the old horses killed for dissec- 
tion, the seat of a more or less voluminous aneurism, which sometimes extends to the 


arterial tube placed at the origin of the branches of the right fasciculus, and it is not 
unfrequently met with in one or the other section of the great mesenteric artery. 


530 THE ARTERIES, 


Abdominal aorta; 2, 2, 
2, Arteries of the left fas- 
ciculus, destined for the 
small intestine; 3, Ileo- 
cacal artery ; 4, Superior 
cecal artery; 5, Inferior 
cecal artery; 6, Artery 
of the arch of the cecum ; 
7, Right colic artery; 8, 
Left colic artery ; 9, First 
artery of the small colon, 


DISTRIBUTION OF THE GREAT MESENTERIC ARTERY. 


THE POSTERIOR AORTA. 531 


Such is the general arrangement of the arteries of the small intestine; 
and it remains to indicate some of their special characters, which are as 
follows : 1, The longest arteries of the small intestine are the most posterior, 
as they follow the development of the mesentery, by which they are sus- 
tained; 2, The anterior arteries generally form two series of superposed 
arches, before sending their divisions to the intestine; 3, The first reaches 
the duodenum and anastomoses with the duodenal artery—a branch given off 
by the coeliac axis; 4, The last communicates with the ileo-cwcal artery—one 
of the branches of the right fasciculus. 

B, Arrertes or THE Ricur Fascicutus.—The right fasciculus of the 
great mesenteric artery constitutes, at first, a single trunk some inches in 
length, which soon divides into four branches; these are as follows: the 
ileo-ceecal artery, the two cecal arteries, and the right or direct colic artery. 

Itz0-Cawcat Artery (Fig. 271, 3)—This vessel often has its origin 
from the internal cecal artery. It is placed between the two layers of the 
mesentery, follows for a short distance, and in a retrogade manner, the ileo- 
cecal portion of the small intestine, and wholly anastomoses with the last 
artery of the left fasciculus, after emitting a series of branches, which are 
distributed to the intestinal membranes. 

Cacat Arteries.—Distinguished into internal or superior, and external 
or inferior, these two arteries pass downward and a little to the right, 
towards the concavity of the cecal flexure, embracing between them the 
terminal extremity of the small intestine, and lying at the middle part 
of the cecal sac, whose direction they follow. 

The superior, or internal cecal artery, is lodged in the most anterior 
of the fissures formed by the longitudinal bands of the cecum, and extends 
beneath the serous tunic to nearly the point of the viscus, where it terminates 
by anastomosing with the external cecal artery. The branches furnished 
by this artery during its course escape in a perpendicular direction, and 
distribute their ramifications on the walls of the cecum (Fig. 271, 4). 

The external, or inferior cecal artery, passes between the cecum and the 
origin of the colon, to descend along the first-named receptable by placing 
itself in one of the external fissures, which is situated outwardly and 
posteriorly. Arriving at the point of the organ, this artery bends over it to 
anastomose with the vessel just described (Fig. 271,7). It gives off on its 
track a series of transverse ramifications, similar to those of the latter artery ; 
and besides these, a remarkable branch which may be named the artery of 
the cecal arch. This branch is detached from the principal vessel near the 
origin of the colon, and ascends to the cecal arch, whose concavity it follows 
outwardly to pass forwards and downwards to the initial portion of the large 
colon, where it disappears after following a certain course. The numerous 
collateral branches detached by this artery are sent to the walls of the latter 
portion of intestine, and the arch of the cecum (Fig. 271, 6). 

Ricut on Direct Corio Artery (Fig. 271, 7).—This is the largest of 
the branches composing the right fasciculus of the great mesenteric artery. 
Destined for the right portion of the flexure formed by the large colon, it 
lies immediately beside that viscus, beneath the peritoneal. membrane, 
following it from its origin to its pelvic curvature, where. the artery 
anastomoses by inosculation with the left colic or retrograde artery. 

C. Arreries oF THE ANTERIOR Fascicutus.—These are only two in 
number: the left colic or retrograde, and the first artery of the small colon, 
joined at their origin to an extremely short trunk. 

Lerr Couric on Rerrogrape Artery (Fig. 271, 8).—This is carried 


532 THE ARTERIES. 


to the left portion of the colic ficxure, which it passes over, beneath the 
peritoneum, from the terminal extremity of the viscus to the pelvic curvature, 
where it meets the right artery; im this manner it. follows a course the 
inverse of that pursued by the aliment, and whence its name of retrograde 
colic artery. : . 

Considered collectively, the two colic arteries represent a loop or flexure 
exactly like that formed by the large colon itself. They proceed parallel to 
each other, and finish, after being slightly separated, by uniting to form a 
parabolic curve. This arterial loop occupies a deep position on the 
intestinal loop, being found on the inferior face of the first and fourth 
sections of the large colon, in the concavity of the flexure which gives 
rise to the suprasternal and diaphragmatic curvatures, and on the superior 
plane of the second and third portions of the viscus. 

A considerable number of collateral branches escape perpendicularly 
from this arterial loop, and pass into the membranes of the intestine ; 
some of them establish a transverse communication between the two vessels. 

First Arrery or tHe Smatt Coxon (Figs. 271, 9; 272, 4)—This 
branch, whose calibre is often considerable, is inflected to the left, 
downwards and backwards, to be placed in the substance of the colic 
mesentery, very near the lesser curvature of the floating or small colon. It 
soon meets a branch of the small mesenteric artery, with which it anasto- 
moses by inosculation. 

D. Innominate Brancues of THE Great Musentery.—These are the 
twigs sent to the lymphatic glands, supra-renal capsules, mesentery, and 
pancreas, and whose existence it is sufficient merely to mention. Among 
those supplied to the pancreas, there is one of somewhat considerable volume. 

EK. Tue Anastomosss or THE Great Mesenteric Artery.—The 
multiplicity and calibre of these anastomoses assure, in the most favourable 
manner, the circulation of the blood in the intestinal mass, which, by reason 
of its great mobility, is exposed to displacements capable of inducing more or 
less extensive compression. Not only do these anastomoses unite the 
different branches destined to the same portion of the viscera, be it the small 
intestine, the caecum, or the large colon; but they also establish communica- 
tions between the great mesenteric artery and the neighbouring trunks, 
which in case of need can maintain the circulation: as, for example, when the 
two intestinal arteries are completely obstructed. The blood from the 
celiac trunk can really pass from the duodenal artery into the branches 
of the left fasciculus of the great mesenteric artery: then by the ileo-cecal 
artery into the branches of the right fasciculus, and thence into the left 
colic artery, which, finally, transmits it to the first artery of the small colon, 
as well as to the arches of the small mesenteric artery. The communica- 
tion existing between the broncho-cesophageal and the cceliac trunks, through 
the medium of the cesophageal and gastric arteries, even allows a collateral 
circulation to be formed, and which would be capable of supplementing the 
posterior aorta, supposing that vessel tied behind the trunk that distributes 
blood to the bronchi and cesophagus. 


4. Small Mesenteric Artery. (Fig. 272.) 


This artery carries blood to the small colon and rectum, and arises at 2 
right angle from the inferior face of the abdominal artery, from 44 to 
6 inches behind the great mesenteric. It descends between the two layers 
of the colic mesentery, and is soon inflected back in describing a curve 


THE POSTERIOR AORTA, 533 


upwards, to pass above the rectum; when near th i i 
sa enter the walls of that intestine. eer ee 
n its course this artery gives off, at prett lar i i 
; y regular intervals, thirt 
fourteen branches, the foremost of which are fe eek and loageat : Tie 
originate from the convexity of the artery—that is from below, and “either 


Fig. 272. 


. DISTRIBUTION OF THE SMALL MESENTERIC ARTERY; THE SMALL COLON WITH ITS 
MESENTERY IS SPREAD OUT, AND THE SMALL INTESTINE THROWN BACK TO THE 
RIGHT UNDER THE LARGE COLON. 


- 1, Trunk of the small mesenteric artery; 2, Great mesenteric artery; 3, Its 

é anterior fasciculus; 4, First artery of the small colon, forming part of that 
fasciculus ; 5, Retrograde colic artery; 6, Right fasciculus of the great mesen- 
teric; 7, Branches of the left fasciculus; 8, Renal artery ; 9, Terminal extremity 
of the aorta; 10, External iliac artery ; 11, Circumflex iliac artery; 12, Internal 
iliac artery. 


singly or in clusters ; the latter disposition is the most common for the first 
four or five. They descend into the mesentery and arrive near the superior 
curvature of the intestine, where they are disposed in the following manner :. 
he first seven or eight bifurcate, and form arches like those of the arteries 
supplying the small intestine, differing from them only in being nearer the. 


37 


534 THE ARTERIES. 


small curvature of the colon; the other branches, which are destined for 
the terminal part of that viscus and the rectum, ramify in the intestinal 
membranes without having previously formed any arches. : 

The anterior ramuscule of the first branch anastomoses directly with the 
artery sent to the small colon by the great mesenteric, and from this 
anastomosis results the first colic arterial arch. 


5. Renal or Emulgent Arteries. (Fig. 275, 2.) 


These are two arteries, one for each kidney, detached laterally, and at a 
right angle, from the abdominal aorta, near the great mesenteric artery ; 
passing outwards to the internal border of these organs, each divides 
into several branches, which enter the gland either by its notch or by its 
inferior face. Reaching the interior of the kidney, these branches subdivide, 
and form a network of large vessels placed on the limit between the cortical 
and medullary substances, from which a multitude of ramuscules are given 
off, and pass almost exclusively into the tissue of the cortical portion. (See 
the description of the kidneys.) 

The right renal artery, longer than the left, passes between the small 
_psoas muscle and the posterior vena cava, to reach the right kidney. Both 
arteries are in relation with the posterior extremity of the supra-renal 
capsules. 

Remarkable for their relatively enormous volume, when compared with 
that of the glands receiving them, these arteries do not, before penetrating 
the proper tissue of the kidneys, give off any but a few unimportant 
ramuscules, the principal of which proceed to the supra-renal capsules 
(Fig. 275). Other twigs from the great mesenteric artery, or even from the 
aorta itself, also supply these small bodies. It is not unusual to find 
the kidneys receiving vessels from the arteries in their vicinity. Thus, we 
have seen an artery from the external iliac pass into a kidney by its lower 
face; and we have also observed an artery, detached from the aorta along 
with the great mesenteric, enter the kidney by its anterior border. 


6. Spermatic Arteries. 


‘hese arteries differ in the male and female; in the male they are 
-also named the great testicular arteries ; in the female they are exclusively 
designated as the utero-ovarian arteries. 

Great Testicutak Artery (Fig. 275, 38).—This arises close to 
the small mesenteric artery, either before, behind, or to one side of it, but 
rarely on the same level as the artery of the opposite side; it is then 
directed backwards and downwards, sustained, with its satellite vein, in a 
particular fold of peritoneum, and reaches the entrance to the vaginal sheath 
(internal abdominal ring), into which it is seen to pass with the other 
constituent portions of the spermatic cord, and to descend on the testicle 
by forming remarkable flexuosities united in an elongated mass. Arrived 
within the head of the epididymis, this artery insinuates itself under the 
tunica albuginea, becomes incrusted, as it were, in its substance, and 
successively passes round the superior border, posterior extremity, and the 
inferior border and anterior extremity of the testicle. In this course it is 
very sinuous, and detaches at a right angle a large number of equally 
flexuous branches, which creep over the faces of the organ while sending 
numerous ramuscules into its structure. The epididymis also receives its 
blood by this artery. 


THE POSTERIOR AORTA. 535 


Urero-ovartan Artery.—The origin of this vessel is conformable with 
that of the preceding artery. It is placed between the two lamin of the 
broad ligament, and soon bifurcates into the ovarian and uterine arteries. The 
ovarian branch describes numerous flexuosities, like the corresponding artery 
in the male, and comports itself on the ovary in the same manner as the 
latter vessel does on the testicule. The uterine branch passes to the cornu 
of the uterus, where its divisions anastomose with the proper uterine artery. 


7. Small Testicular Arteries: Male. Uterine Arteries: Female. 


Smatt Testicutar Artery (Cremasrerio Arrery, ARTERY OF THE 
Corp).—A pair, like the great testicular artery, this vessel is very slender. 
and originates either from the aorta between the internal and external iliaes, 
or from the latter, near its commencement. The last being the most 
common, it is usual to describe it asa collateral branch of the crural (external 
iliac) trunk. We have regarded it as an artery emanating directly from 
the posterior aorta, in order to include its description with that of the great 
testicular and the utero-ovarian arteries. 

Whatever may be its mode of origin, it gains the entrance to the vaginal 
sheath, and enters it with the spermatic vessels, to be distributed to the 
various parts constituting the cord. Before penetrating the substance of this 


cord, it gives off several ramuscules destined for the peritoneum, iliac glands, 
ureter,.and deferent canal. 

Uterine Artery.—This has the same point of origin as the preceding, 
its analogue, but differs from it in its larger volume. It is placed between 
the two layers of the lumbar ligament, and is divided into two branches on 
arriving at the small curvature of the uterine cornu: the anterior branch 
anastomoses by its divisions with the utero-ovarian artery; the posterior 
passes to the body of the matrix, where it communicates with the vaginal 
artery. 


DIFFERENTIAL CHARACTERS OF THE POSTERIOR AORTA AND ITS COLLATERAL BRANCHES IN 
OTHER THAN SOLIPED ANIMALS. 


1. Posterior Aorta in Ruminants. 


The artery pursues the same course as in Solipeds, and also terminates by four 
branches, towards the entrance to the pelvic cavity. 

ParretaL Brancaes.—The intercostal arteries only differ from those of the Horse in 
their number; as but twelve are met with, of which eight or nine alone are furnished by 
the posterior aorta. : ee a entee 

Phe lumbar and déaphragmatie branches are absolutely identical, in their disposition, 
with the analogous arteries of Solipeds. ; 

The middle sacral artery is more considerable in volume, particularly in the Sheep 
and Goat. This will be referred to hereafter (see internal iliac artery of Ruminants). 

VisckRAL Brancues.—Broncho-esophageal trunk.—This offers nothing particular. 

Celiac trunk (Fig. 273, 1).—This artery descends on the rumen, a little behind the 
insertion of the cesophagus, is directed to the right, and divides near the omasum into 
two terminal branches—the superior and inferior arteries of the omasum and abomasum. 

The collateral branches escaping from this trunk are: 

1. Several diaphragmatic arteries. _ : ; 

2. The splenic artery, almost exclusively destined for the spleen (Fig. 278, 8). 

3. The superior artery of the rumen, always arising from a very short trunk common 
to it and the preceding vessel, is carried backward to the superior face of the rumen, and 
from this descends between the two conical vesice to anastomose with the artery of the 
inferior face of the viscus (Fig. 273, 2). er hre: 

4. The inferior artery of the rumen, which is insinualed between the two anterior 
culs-de-sac, and afterwards runs along the inferior face of the organ, passing towards 
the notch separating the two conical vesica, to meet the superior vessel (Fig. 273, 3). 


536 THE ARTERIES. 


e reticulum, having usually a common origin with the inferior 
mone ce ie passing forward ‘on the left of the msophagus, to be divided, 
near the insertion of that conduit, into two branches: one, the superior, inclines to the 
right to the small curvature of the viscus (Fig. 273, 5); the other, the inferior, occupying 
the fissure separating the great curvature of the reticulum from the right sac of the 
paunch, and giving to the latter organ a great number of branches (Fig. 273, 4). _ 

6. The hepatic artery, which is not only distributed to the liver, but also furnishes a 
branch for the gall-bladder, and a duodenal artery breaking up into two branches: the 
posterior branch forming with the first artery of the small intestine an arching anasto- 
mosis ; the anterior communicating with the superior artery of the omasum and abomasum, 
This hepatic artery always originates between the trunk common to the splenic artery 
and the superior branch of the rumen, and that which gives rise to the superior branch 
of the same viscus and the artery of the reticulum. 

The terminal branches of the ceeliac artery comport themselves as follows : 

1. The superior artery of the omasum and abomasum passes successively to the great 
curvature of the first of these reservoirs, and to the concave curvature of the second ; then 
it goes beyond the pylorus to unite with the duodenal branch of the hepatic artery by 
inosculation (Fig. 273, 6). 


Fig. 273. 


ARTERIES OF THE STOMACH IN RUMINANTS. 

1, Celiac trunk; 2, Superior artery of the rumen; 3, Inferior artery of the 
rumen; 4, Inferior. artery of the reticulum; 5, Superior artery of the reticulum; 
6, Superior artery of the omasum and abomasum; 7, Inferior artery of ditto; 
8, Splenic artery; a, Esophagus; B, Left sac of the rumen; B’, Left conical 
vesica ; C, Right sac of the rumen; c’, Right conical vesica; D, Reticulum; 5, 
Omasum; F, Abomasum ; G, Duodenum; R, Spleen 


2. The infertor artery of the omasum and abomasum, on the contrary, passes at first 
over the smali curvature of the omasum, afterwards the great curvature of the abomasum, 
and disappears in the omentum, to which on its course it furnishes a great number of 
branches (Fig. 273, 7). 

In small Ruminants, the distribution of the arteries of the coeliac trunk presents 
some modifications. We will cite the principal, which belong to the mode of origin of 
the two branches destined for the reticulum: these branches form two particular 
vessels which arise singly from the coeliac trunk; the inferior artery at the same point as 
the superior artery of the rumen, the superior towards the terminal bifurcation of the 
trunk. : 

Great mesenteric artery.—Its origin approaches very closely that of the cceliac trunk. 
After a course of from 6 to 8 inches, it divides into two branches—an anteriur and a 


THE POSTERIOR AORTA. 587 


post rior. The first, destined for the. small intestine, creeps above it, between the two 
layers of the mesentery, and passes backward by describing a curve which gives off from 
its convexity—that is, below, a great number of branches, analogous in their mode of 
termination to the arteries of the small intestine in the Horse. The posterior branch goes 
to the large intestine, where it separutes into two principal branches: one which passes 
to the colon, and whose divisions cross to the right, from before to behind and from above 
to below, the convolutions described by that viscus; another which reaches the concave 
curvature of the caecum, and anastomoses by an arch with the terminal extremity of the 
parent-branch of the arteries supplying the small intestine. 

Small mesenteric artery.— Very short and narrow. 

Renal, spermatic, and small testicular arteries—These do not differ in their essential 
disposition trom the analogous vessels in Solipeds. 


2. Posterior Aorta in the Pig. 


With the exception of the mesenteric vessels, whose distribution resembles that 
already indicated for Ruminants, and with the exception, also, of the middle sacral artery. 
which will be alluded to when describing the internal iliac arteries, all the branches 
given off by the posterior aorta comport themselves almost as in the Horse, 


3. Posterior Aorta in Carnivora. 


In these animals, as well as in the Pig, the denomination of posterior aorta is not 
justifiable, because the arteries of the head and thoracic limbs spring directly from the 
aortic arch. 

The branches of the aorta are distinguished as parietal and visceral. 

A. ParietaL Brancues.—Beyond the fourth space, the intercostal arteries are fur- 
nished by the aorta: the first is voluminous, and throws off some considerable filaments 
to the muscles of the withers. The first two lumbar arteries arise from the thoracic 
portion of the aorta, because of the very backward insertion of the diaphragm; the third 
is detached between the two pillars of that partition. In the abdominal cavity, close to 
the great mesenteric, the aorta gives off a branch that soon divides into two: one is 
diaphragmatic, and descends on the posterior face of that muscle ; the other reaches the 
sublumbar region, passes over the psoas muscle, and traverses the abdominal wall in the 
vicinity of the transverse processes of the lumbar vertebra. We will speak presently of 
the middle sacral. 

B. Viscerat Brancues.—I have not found in the Dog any special bronchial arteries ; 
but there are four or five wsophageal arteries that arise from different points of the 
thoracie aorta; they descend into the mediastinum, to the right and left of the 
cesophagus, to which they are distributed. They furnish branches that accompany the 
bronchi and enter the lungs. ; 

The celiac trunk is again divided into three branches, whose disposition is as follows: 
The gastric, or stomachic coronary artery, does not divide into two branches (anterior and 
posterior gastric) as in Solipeds. Near its origin it furnishes a pancreatic branch ; then 
it expends itself in a great number of filaments that are spread over the posterior face 
and great tuberosity of the stomach, or over its anterior face after crossing the small 
curvature. 

The splenic artery reaches the spleen at the middle of its upper border. It gives on 
its course: 1, A splenic branch that enters the upper extremity of that organ; 2, The 
left gastro-omental. The hepatic artery provides the principal hepatic vessel at the 
posterior fissure of the liver; it is then continued by the right gastro-omental artery. 
On the duodenum, the latter gives origin to the pyloric and the pancreatico-duodenal 
branches; the latter is voluminous, is lodged in the substance of the pancreas, and 
‘anastomoses by its last filaments with the great mesenteric. 

The great mesenteric artery arises in the vicinity of the cceliac artery ; it forms a curve 
whose convexity is backward, and anastomoses by its extremity with the pancreatico- 
duodenal branch of the hepatic. From its convexity are detached several filaments 
(filaments to the small intestine), that form arches towards the sn.aller curvature of that 
viseus. Behind, and at a short distance from its origin, it gives a branch to the cecum 
and branches to the colon; the latter are sometimes large. 

The small mesenteric commences near the termination of the aorta, and divides into 
two branches. one passing forward, and the other backward; they form the hemorrhoidal 
vessels (see Fig. 209). 

There is nothing special to note with regard to the renal and spermatic arteries, 


538 THE ARTERIES. 


COMPARISON OF THE AORTA OF MAN WITH THAT OF ANIMALS. 
The aorta in Man offers the same general disposition as in the Carnivora, the trunk 
being inflected across, to be placed along the body of the dorsal and first lumbar vertebrae, 


where it terminates in the iliac vessels. . ; 
It furnishes the coronary arteries, the arteries of the head and thoracic members— 


which will be noticed hereafter ; and the parietal and visceral branches to the chest and 
abdomen. At first these are the intercostals, beyond the third space; the diaphragmatic 
arteries, superior and inferior according as they occupy one or other face of the diaphragm ; 


and, lastly, the Zumbar arteries. : : : 
Se the visceral branches are distinguished: 1, The bronchial arteries, two in 


number; the left arises from the concavity of the aortic arch, and enters the lungs with 
the left bronchus; the right originates alone or in common with the preceding, and enters 
on the right bronchus; 2, The esophageal arteries disposed somewhat as in the Dog; 
3, The celiac trunk, whose distribution is nearly identical with that of the Carnivora ; 
4, The superior or great mesenterig, disposed in arches as in the Dog (see Fig. 276, 9). Its 
last branches pass to the cecum, and the ascending and origin of the transverse portion of 
the colon; 5, The inferior or small mesenteric, which arises 1} to 2 inches from the bifur- 
cation of the aorta; this artery descends into the meso-colon, and terminates on the sides 
of the rectum by the hemorrhoidal vessels; to the left, they emit branches to the large 
intestine; the first ascend along the descending colon, and anastomose on the transverse 
colon with the right colic branch of the superior mesentexic; 6, The renal and capsular 
arteries, which do not offer important differences ; 7, Lastly, the spermatic arteries, which 
are remarkable for the length of their course, commencing, as they do, at the aorta, a 
short distance below the renal vessels 


ArricLe TIJ.—Inrernat Intac Antrrres on Petvio Trunss. (Fig. 277, 2.) 


The two internal iliac arteries represent the middle or internal branches 
of the quadrifurcation formed by the posterior aorta at its terminal extremity. 

Extending from the body of the last lumbar vertebre, to near the 
terminal insertion of the small psoas muscle, in an oblique direction 
downwards, outwards, and backwards, these arteries correspond: in front, 
with the trunks of the common iliac veins, which separate them from the 
external iliacs; inwards, to the peritoneum; above and outwards, to the 
sacro-iliac articulation and to the ilium. 

In its course, the internal iliac artery emits the following branches : the 
umbilical artery, artery of the bulb, ileo-lumbar, gluteal, and subsacral arteries. 
At its terminal extremity, it is divided into two branches which ride on the 
superior border of the tendon belonging to the small psoas muscle: the one 
within, the other without that tendon. The first is the obturator artery, the 
second the ileo-femoral artery. All these branches will be studied in the 
order of their enumeration. 


Preparation of the internal iliac artery—Place the subject in the first position; 
remove one of the posterior limbs, leaving the rectum and bladder in the pelvis, and 
slightly inflating the latter organ. Dissect, on the side from which the limb has been 
removed, the origin and visceral ramifications of the branches furnished by the trunk of 
the artery. Follow, on the opposite side, the ramifications given off by these branches to 
the muscles, To conveniently prepare the coccygeal arteries, it is necessary, after 
removing the great sciatic ligament and dissecting the internal artery of the bulb along 
with the subsacral trunk, to raise up the rectum and bladder by means of the chain-hooks, 


- Umbilical Artery. (Bigs. 274, 5; 277, 3.) 


This artery forms a considerable vessel during f; i i 
g foetal life, and carries the 
blood of the foetus to the placenta; it will be described in detail in the 
anatomy of the foetus. 
In the adult it is almost entirely obliterated, appearin only as a fibrous 
cord extending from the internal iliac artery to ‘Ge ee of Nhe bladder, 
and placed at the free margin of the lateral serous fold detached from the 


THE INTERNAL ILIAC ARTERIES. 539 


cul-de-sac of that organ. This cord throws off on its track, one or more 
vesical branches, beyond which its canal altogether disappears. These 


Fig. 274, 


A, Left kidney; B, Right kid- 
ney; u, 6, Ureters; C, ©, 
Supra-renal capsules; D, 
Bladder; 5, 5, Testicles; 
v, Head of the epididymis ; 
e', Tail of the epididymis ; 
¥, Deferent canal; G, Pel- 
vic dilatation of the defe- 
rent canal; H, Left vesicula 
seminales; the right, with 
the deferent canal of the 
same side, has been removed, 
to show the insertion of 
the ureter into the bladder ; 
q, Prostate; J, Cowper’s 
glands; Kk, Membranous 
portion of the urethral 
canal; x, Bulbous portion 
of the same; M, Cavernous 
body of the penis; m, m, 

A Its roots; N, Head of the 

rem” penis.—1, Abdominal aorta; 


UPPER AND GENERAL VIEW OF THE GENITO-URINARY 2, 2, Renal arteries giving 


APPARATUS AND ARTERIES IN THE MALE. off the principal capsular 
artery; 3, Spermatic, or 


great testicular artery ; 4, Common origin of the internal pudic and umbilical arteries; 
5, Umbilical artery ; 6, Its vesical branch; 7, Internal pudic artery; 8, Its vesico- 
prostatic branch. 


540 THE ARTERIES. 


vesical branches also, though very rarely, come from the internal artery of 
the bulb; in which case the obliteration of the umbilical artery is complete. 


2. Internal Pudie Artery, or Artery of the Bulb. 
(Figs. 274, 7; 275, 16; 277, 4.) 

This vessel differs in its distribution in the male and female. 

InrernaL Pupic ARTERY IN THE Maux.— It proceeds from the internal 
iliac, near the origin of that vessel, by a trunk common to it and the 
umbilical artery ; it is then directed backwards, following the superior border 
of the internal obturator (pyriformis) muscle, and placed either without or 
within the texture of the great ischiatic ligament. Arrived at the neck of the 
bladder, it enters the pelvic cavity, lying beside the prostate and Cowper's 
glands, and is finally inflected downwards, passing round the ischial arch to 
reach the bulb of the urethra. 

In its progress it furnishes : 

1. Insignificant ramuscules to the muscle adjoining the sacro-ischiatic 
ligament. 

2. The vesico-prostatic artery (Figs. 274, 8; 275, 17). This is a 
branch constant in its distribution, but variable in its origin. Destined to 
supply the prostate gland, vesicule seminales, the pelvic dilatation of the 
deferent canal and the canal itself, as well as the bladder, it usually 
commences near the prostate gland, and passes from behind to before, in a 
flexuous manner, on the vesicule seminales and the deferent canal. 

3. Slender ramifications for the pelvic portion of the urethral canal, 
Cowper's glands, the anus, and the ischio-cavernous muscle (erector penis). 

The terminal extremity of the vessel is insinuated beneath the accel- 
erator muscle, and immediately divides into a multitude of ramuscules 
which enter the erectile tissue of the urethral bulb, where they comport 
themselves ag in all tissues of this kind. 

Varieties.—It is not rare to see the artery of the bulb detach, before 
attaining Cowper's gland, the cavernous artery, which then passes round the 
ischial arch along with the nerve of the penis. Sometimes it only gives off 
the posterior dorsal artery of the penis, a branch of the cavernous. 

Distripvtion or tHe Internat Pupio Arrery in THE Feats. (Fig. 
277, 4.)—This artery terminates, towards the vagina, by rectal, vulvular, 
vaginal, and bulbous branches ; the latter are for the bulb of the vagina. 
As in the male, it does not give off more than one important branch on its 
course ; this, the vaginal artery (Fig. 277, 5) is analogous in every respect to 
the vesico-prostatic artery; its terminal divisions go, not only to the middle 
portion of the vagina, but also to the body of the uterus, where they 
anastomose largely with the branches of the uterine artery, and even pass 
to the bladder and rectum. 

Tho internal pudic artery of the female, as in the male, is liable to nu- 
merous variations. It may furnish the cavernous artery, or only the dorsal 
eee . the clitoris. We have scen the vaginal artery come from the 


3. Subsacral or Lateral Sacral Artery. (Figs. 275, 2; 277, 6.) 


Rising within the internal iliac artery, at, or a little behind the lumbo- 
sacral articulation, lying above the peritoneum, and beneath the sacral 
foramina and the large nerves passing through them, this vessel is directed 
backwards and arrives near the posterior extremity of the sacrum, whero 


THE INTERNAL ILIAC ARTERIES. 541 


it ends in two branches: the ischiatic and lateral coccygeal arteries, to which 
must be added the middle coccygeal artery, usually emitted by the subsacral 
vessel of the right side. 

CotnaTEeraL Brancues.—The lateral sacral artery distributes on its 
course several insignificant ramuscules destined for the neighbouring parts, 
and four spinal branches which enter the vertebral canal by the inferior 
sacral foramina, and leave it again by the superior, after throwing off some 
divisions to the posterior extremity of the spinal cord and the nerves of ’ 
the tail; these branches ramify in the muscles lying on the sacral spine. 

Terminal Brancues.—1. Iscuratic Antery.—lt crosses the ligament of 
the same name to place itself under the superior extremity of the anterior 
portion of the long vastus, passes backwards and downwards, and divides 
into several branches which descend into the spbstance of the ischio-tibial 
muscles (semimembranosis and semitendinosis), to beneath the ischial 
tuberosity. These branches anastomose, by their extremities, with the 
ascending branches from the the femoro-poplitea] as well as with the 
divisions of the obturator and deep femoral arteries. 

2. Laverna CoccyeeaL Artery.—This vessel represents the continua- 
tion of the lateral sacral artery, though not by its volume, which is much 
less than the ischiatic artery, but in its direction. It proceeds from before 
to behind, for the whole length of the coccyx, between the rudimentary 
vertebree of that region and the depressor muscles of the tail, gradually 
diminishing in volume, and detaching on its course a series of collateral 
ramuscules which are expended in the muscles and integuments of the tail. 

There has been described a superior lateral artery, a branch of the pre- 
ceding, and which passes between the elevator muscle of the tail and the 
superior face of the coccygeal vertebre ; but this artery never exists: the 
superior coccygeal muscle receives its blood by branches analogous to the 
spinal branches of the intercostal, lumbar, and sacral arteries, and which 
emanate from the lateral coccygeal artery at each of the vertebral bodies. 

3. Mippitz Coccyezat Artery.—The origin of this vessel is liable to 
numerous variations. Ordinarily, it is detached from the right subsacral 
artery, in common with the lateral coccygeal of the same side. At other 
times, it escapes from the lateral at 5 or 6 inches from its origin. In a 
specimen now before us, it arises nearly from the middle of the subsacral 
artery. And it may also proceed from either the left sacral or the corres- 
ponding lateral coccygeal artery. 

Whatever may be its point of emergence, this vessel is placed beneath the in- 
ferior face of the caudal vertebre, between the two depressor muscles of the tail, 
crosses te suspensory ligament of the rectum, and extends to the extremity 
of the cuccyx, distributing ramuscules to right and left, and even below. 


4, Ilio-muscular or Ilio-lumbar Artery. (Figs. 275, 14; 277, 8.) 


Immediately after clearing the inferior face of the lateral angle of the 
sacrum, and even often before, the pelvic trunk gives off from its external 
side, and at a right angle, the ilio-lumbar artery, which passes directly 
outwards, behind the sacro-iliac articulation, between the iliacus muscle and 
the bony surface covered by it, and emits divisions that proceed to the 
above-named articulation, as well as to the muscles of the sublumbar 
region. Near the angle of the haunch, it terminates in several branches, 
which bend upwards on the external border of the ilium, to penetrate the 
principal gluteal muscle, or the muscle of the fascia lata (tensor vagine 
femoris. ) 


542 THE ARTERIES. 


5. Gluteal Artery. (Figs. 275, 18; 277, 7.) 


i i i the pelvic 
his, the most voluminous of the branches emanating from | 
Fea oe opposite the preceding, and from 8-10ths of an inch to 14 
inches behind the subsacral. It is immediately reflected on the internal 


Fig. 275. 


LATERAL VIEW OF THE GENITO-URINARY ORGANS IN THE MALE, 

1, Abdominal aorta; 2, External iliac artery; 3, Common origin of the prepubic 
and deep femoral arteries ; 4, Prepubic artery; 5, Posterior abdominal artery; 6, 
External pudic artery; 7, Subcutaneous abdominal artery; 8, Anterior dorsal 
artery of the penis; 9, 9, Anterior and posterior branches of that artery ; 10, 
Internal iliac artery; 11, Last lumbar artery ; 12, Subsacral artery; 13, Gluteal 
artery; 14, Iliaco-muscular artery; 15, Umbilical artery; 16, Internal pudic 
artery $ 17, Its vesico-prostatic branch; 18, Iiaco-femoral artery ; 19, Obturator 
artery ; 20, Artery of the corpus cavernosum ; 21, Posterior dorsal artery of the 
penis—a branch of the preceding ; 22, Spermatic artery ; 23, Posterior mesen- 
teric artery; Cc, Termination of the small colon; R, Rectum; s, Sphincter of the 
anus ; /, Suspensory ligament of the penis; /’, Suspensory ligament of the rectum ; 
v, Bladder; u, Ureter; T, Testicle; £, Epididymis; Dp, Deferent canal; v, Vesi- 
cule seminales; P, Prostate; p, Cowper’s gland; r, Crus penis; s, Ligament of 
the corpus cavernosum. 


border of the ilium, and emerges from the pelvis by the great sciatic notch, 
along with the anterior gluteal nerves, dividing into several branches which 
ramify in the texture of the great and small gluteal muscles. 


6. Obturator Artery. (Figs. 275, 19 ; 232, 10.) 
This vessel, the origin of which has been already indicated, directs its 


THE INTERNAL ILIAC ARTERIES. 543 


course backward and downward, accompanied by a satellite vein and nerve, 
passes beween the peritoneum and ilium in following the inferior border 
of the internal obturator muscle, and finally insinuates itself beneath ‘thas 
muscle to make its exit from the pelvis by creeping through the oval (obtu- 
rator) foramen, after furnishing a constant vesical twig. Placed between the 
external obturator muscle and the inferior face of the ischium, it separates 
into several branches, the majority of which descend inte the internal 
crural and ischio-tibial muscles (long or external vastus, and the semi- 
membranosis and semitendinosis), anastomosing with the ultimate divisions 
of the ischiatic and deep femoral arteries. Among these branches there 
are two or three which go to the roots of the penis, and enter the erectile 
tissue of the cavernous body ; one of them, more important than the others by 
its volume, is designated the artery of the corpus cavernosum. 

ARTERY OF THE Corpus Cavernosum (Fig. 275, 20).—This vessel 
creeps on the inferior face of the ischium, backwards and inwards, reaches 
the crus penis, and pierces it by several branches, after supplying some 
muscular divisions and the posterior dorsal artery of the penis. 

The latter is situated on the dorsal margin of the penis, passes forward 
between the two ligaments attaching that organ to the symphysis pubis, 
and proceeds to anastomose with the posterior branch of the anterior dorsal 
artery (Fig. 275, 21.) 


7. Tliaco-femoral Artery (Figs. 275, 18 ; 277, 9.) 


Necticed as one of the terminal branches of the pelvic trunk, the iliaco- 
femoral artery only exists as a vessel of a certain volume in Solipeds. In 
other animals, as in Man, it is merely an insignificant and innominate branch 
of the obturator artery. It proceeds outside the tendon of the small psoas 
muscle, between the iliacus and the neck of the ilium, which it passes round 
obliquely, above the origin of the anterior rectus muscle, to descend on the 
external side of the latter, and plunge into the mass of the patellar muscles, 
entering them between the anterior rectus and vastus externus, after sending 
out some branches to the psoas, gluteal, and muscles of the fascia lata. 


DIFFERENTIAL CHARACTERS OF THE INTERNAL ILIAC ARTERIES IN OTHER THAN SOLIPED 
ANIMALS, 


1, Internal Iliac Arteries of Ruminants. 


The terminal extremity of the aorta, after giving off the external iliac arteries, 
bifurcates to constitute the pelvic trunks, and in the angle of bifurcation throws out a 
very large branch—the suera media—from which emanate the arteries of the tail. 
This, however, is not the only important peculiarity to be noted in the disposition of the 
pelvic arteries. The internal iliac artery emits at its origm a very short, but very large 
branch, which divides to form the umbilical artery, and an enormous uterine artery, that 
supplants, to a great extent, the utero-ovarian artery; it is then directed backwards, on 
the internal face of the great ischiatic ligament, crossing the direction of the lumbo-sacral 
plexus. In its course it furnishes branches resembling the iliaco-muscular, the gluteal, 
and the ischéatic, and is continued about the middle of the pelvis by the internal pudic 
artery, which terminates by forming the dorsal artery of the clitoris, after distributing 
branches to the rectum and the genito-urinary organs lodged in the pelvic cavity. ; 

Tt will be seen from this description—which refers only to female animals, but is 
easily applicable to males—that no mention is made of an iliaco-femoral or obturator 
artery. This is because these two vessels are entirely absent in the Sheep, and the last, 
though present in the Jarger Ruminants, is yet in a very rudimentary state, both being 
supplemented by the deep femoral, whose dimensions are considerable. Neither is 
the lateral sacral or subsacral artery described, as it is also wanting, its ischiatic branch 
coming directly from the pelvic trunk, and its coccygeal divisions being supplied by the 
middle sacral artery. 


544 


Jateral branches, 


THE ARTERIES. 


% 


2. Internal Iliac Arteries of the Pig. 


Two singe branches, 
the aorta, between 


tives of the éliaco 


Fig. 276. 


ABDOMINAL AORTA, WITH ITS BRANCHES, IN 

; MAN. 

1, Phrenic arteries; 2, Ceeliac axis; 3, Gastric 
artery ; 4, Hepatic artery, dividing into right 
and left hepatic branches; 5, Splenic artery, 
passing outwards to the spleen; 6, Supra- 
renal artery of right side; 7, Right renal 
artery longer than the left, passing outward 
to right kidney; 8, Lumbar arteries; 9, Su- 
perior mesenteric artery; 10, The two sper- 
matic arteries ; 11, Inferior mesenteric artery ; 
12, Sacra media; 13, Common iliaes; 14, Right 
internal iliac; 15, External iliac; 16, Epigas- 
tric artery ; 17, Circumflexa ilii; 18, Common 
femoral artery, dividing into superficial and 
deep femoral. 


originating one above the other, arise from the extremity of 
tle two internal iliac arteries; one divides almost at once into two 
which go to right and left bene ath the iliacus, and are the representa- 
-muscular arteries of the Horse; the other, or sucra media, placed in the 


middle line, proceeds backwards on the 
jnferior face of the os sacrum, and con- 
stitutes the coccygeal arteries, after giving 
off, at about 14 inches frum its origin, two’ 
lateral branches, traces of the lateral 
sacral arteries, which furnish the spinal 
ramuscules of the sacral region. 

The iliae trunk near its origin sends 
off the umbilicul artery, is directed back 
towards the great sciatic notch, there 
detaches gluteal branches, and is pro- 
longed beyond the notch to the external. 
surface of the great ischiatic ligament in 
forming the internal pudic artery. 

The latter emits, before leaving the 
pelvic cavity, a lung hemorrhoidal artery, 
that creeps back by the side of the rectum, 
to be distributed to the posterior extre- 
mity of that intestine and the adjoining 
genito-urinary organs. Without the pel-' 
vis, it abandons some gluteal branches, 
the most considerable and posterior of 
which represent the ischiatice artery of 
Solipeds. It then re-enters the cavity 
of the pelvis, and terminates at the base 
of the penis by forming the cavernous 
and dorsal arteries of that organ. 


3. Internal Iliae Arteries of Carnivora. 


The internal iliac arteries in the Car- 
nivora result from the bifurcation of an 
arterial trunk, that prolongs the aorta 
beyond the origin of the external iliacs, 
as far as the first intersacral articula- 
tion. 

The pelvic trunk of the Dog at first 
transmits the umbilical artery, which is 
remarkable for its small calibre, and the 
flexuosities it describes before reaching 
the bladder. 

Then the internal iliac courses for 1 or 
1} inches behind, and to the inside of, the 
pelvi-crural venous trunk, dividing into 
two branches at the entrance to the pelvis. 

One of these branches goes towards 
the viscera contained in the pelvic 
cavity ; this is the internal pudic artery. 
It passes backwards, turns the ischial 
arch, and terminates in the cavernous 
and dorsal arteries of the penis, after 
furnishing vesical, hemorrhoidal, and 
urethral branches, as well as the uterine 
artery of the female. The latter is very 
voluminous, and is placed in the sub- 
stance of the broad ligament, above the 


small curvature of the uterine cornu, whence it is directed forward to the ovary, 
where it meets the utero-ovarian artery, after emitting numerous collateral branches, 
remarkable for the richness of the vascular network they form in the walls of the uterus, 

The second branch of the internal iliac artery resembles the subsacral artery and its 


UVHE EXTERNAL ILIAC ARTERIES. 545 


ischiatte branch in Solipeds; it escapes from the pelvic cavity with the great sciatic 
nerve, which it accompanies to beliind the thigh, where it is expended, after giving off 
on its course spinal and gluteal twigs. It is not this branch which supplies the cocey- 
geal arteries ; these come, as in the Pig and Ruminants, from the middle sacral artery. 


COMPARISON OF THE INTERNAL ILIAC ARTERIES IN MAN WITH THOSE OF ANIMALS. 


The aorta in Man bifurcates at the fourth lumbar vertebra to form the primitive (or 
common) iliac arteries, which descend to each side of the margin of the pelvis, where 
they divide into two branches, the internal and eaternal iliacs. 

The internal iliac, or hypogastric artery, passes beneath the sacro-iliac articulation, 
and breaks up into nine or eleven branches that go to the walls of the pelvic cavity, or 
to the organs contained in it. Their disposition somewhat resembles that of Car- 
nivora; in their distribution they represent the various branches of the internal iliac of 
Solipeds. ‘hus we find: 1, An umbilical artery; 2, The vesico-prostatie artery, re- 
sembling the branch of the same name given off in the Horse by the internal pudic ; 
38, The middle hemorrhoidal artery, that passes to the rectum like the branch of the 
internal pudic; 4, Tbe dleo-lumbar artery, the iliaco-muscular of Solipeds; 5, The lateral 
sacral artery. which, behind, joins the middle sacral instead of dividing, as in the Horse, 
into ischiatic and lateral coccygeal; 6, The obturator artery; 7, Gluteal artery; 8, Is- 
chiatic; 9, Internal pudic, that terminates, as in animals, by the cavernous, dorsalis 
penis, and the transversa perinei arteries. The arterial branches of the rectum, or 
inferior hemorrhoidal, are furnished by the interual pudic artery. 


ArtioLe [V.—Exrernat Intac Arrertes orn Crurau Tronas. (Fig. 277, 11.) 


The external branches of the terminal quadrifurcations of the posterior 
aorta, the crural trunks descend on the sides of the entrance to the pelvic 
cavity, in describing a curve downwards and forwards, and a direction 
oblique from above to below, before to behind, and within outwards. 
Maintained within the small psoas and iliacus muscles by the peritoneum 
covering them, they are bordered posteriorly, ard to the inner side, by 
the iliac vein, which isolates them from the pelvic trunk. When they 
arrive at the anterior border of the pubis, in the interstice which separates 
the pectineus from the long adductor of the leg, each is prolonged to 
the thigh, and takes the name of femoral artery ; and thence into the angle 
of the femoro-tibial articulation, where it receives the denomination of 
popliteal artery. , ; 

Before passing to the description of these two vessels—continuations 
of the external iliac artery, we will indicate the collateral branches which 
emanate from this trunk itself, These are two principal: the small 
testicular or uterine (cremasteric), and the circwmflexa ilii. The first having 
been already described (p. 534), we have only to notice the second. 

Crrcumriex Iniac Arrery (Fig. 272, 11).—This artery commences at 
an acute angle near the origin, and in front of, the external iliac ; it 
sometimes emerges directly from the abdominal aorta. It is directed 
outwards, passes between the peritoneum and the lumbo-iliac aponcurosis, 
and arriving at the external border of the great psoas muscle, or even 
beyond that, it bifurcates. The anterior branch sends its ramifications into 
the transverse and small oblique muscles of the abdomen, where they 
anastomose with the abdominal ramuscules of the lumbar and intercostal 
branches; the posterior bifurcation, after giving some vessels to the same 
muscles, traverses the abdominal wall a little below the external angle of the 
ilium, in passing between the small oblique and iliacus muscles, to descend 
within the anterior border of the ilio-aponeuroticus (tensor vagine) muscle, 
and expend itself in front of the thigh by subcutaneous divisions, 


546 


THE ARTERIES. 
Fig. 277. 


DISTRIBUTION OF THE EXTERNAL AND 
INTERNAL ILIAC ARTERIES IN THE MARE. 


1, Abdominal aorta; 2, Internal iliac artery ; 
3, Common origin of the internal pudic and 
the umbilical arteries—the latter is cut; 4, 
Internal pudic artery; 5, Vaginal artery; 
6, Lateral sacral artery; 7, Origin of the 
gluteal artery, which springs in this instance 
from the lateral sacral, a circumstance most 
frequently observed in the Ass; 8, Origin 

of the ilio-muscular artery; 9, Origin of 

the iliaco-femoral artery; 10, Obturator artery; 11, External iliac artery; 12, Cir- 
cumflex iliac artery, cut; 13, Femoral artery; 14, Common origin of the deep 

femoral and prepubic arteries; 15, Origin of the anterior great muscular artery; 16, 

Origin of the saphena artery, cut; 17, Innominate branch; 18, Popliteal artery; 

19, Femoro-popliteal ; 20, Satellite artery of the great femoro-popliteal nerve; 21, 

Posterior tibial artery; 22, Its communicating branch with the saphena; 23, Exe’ 


ternal plantar artery; 24, Satellite artery of the internal plantar nerve; 25, Digital 
artery. 


THE EXTERNAL ILIAC ARTERIES, 547 


, FEMORAL ARTERY. (Fig. 277, 13), 


_ The femoral artery, a prolongation of the external iliac, which changes 
its name on leaving the anterior border of the pubis, at first lies beneath the 
‘erural arch, beside a. cluster of lymphatic glands, in the space comprised 
between the pectineal muscles, the long adductor of the leg, and the iliacus. 
From this interstice it descends, accompanied by its satellite vein, which lies 
behind it, and the internal saphena nerve, along the pectineus and vastus 
internus, at the posterior border of the long adductor of the leg. It soon 
leaves that muscle, however, to traverse the ring formed by the two branches 
of the great adductor of the thigh and the oblique concavity on the posterior 
face of the femur, and reaches the superior extremity of the gastrocnemii, 
between which it is continued, and assumes the name of popliteal artery. 
On its course the femoral artery distributes a certain number of collateral 
branches to the adjacent parts. These are: the prepubic, deep muscular, 
superficial muscular, the small muscular, and saphena arteries. 


Preparation.—The animal being placed in the first position, and the limb raised, the 
skin is carefully removed from the inner aspect of the thigh, the external generative 
organs in the inguinal region, and the inferior abdominal wall. ‘The saphena vein is 
first to be exposed, and the branches of the artery of that name dissected ; next, the 
prepubic artery, which is to be sought for in the inguinal canal, and its branches 
prepared by dissecting from their origin to their termination. The excision of a portion 
of the adductors of the leg, and the great adductor of the thigh will sufficiently expose 
the femoral artery and its other collateral branches, 


1. Prepubic Artery. (Fig. 275, 4.) 


This artery originates at the artificial line of demarcation which separates 
the external iliac from the femoral artery, at the superior extremity of the 
latter. It therefore emerges from that vessel at the anterior border of 
the pubis, and never alone, but always with the deep muscular branch, 
by means of a common and generally very short trunk, which springs at 
an acute angle from the inner side of the femoral artery. 

The prepubic artery traverses the crural ring, opposite which it arises; 
it lies on the anterior face of Poupart’s ligament, behind the neck of the 
vaginal sheath, and after a very short course separates into two branches— 
the posterior abdominal and external pudic arteries. 

Posterior Aspominau Artery (Epigasiric of Man)—(Fig. 275, 5).— 
This leaves the external pudic artery at an acute angle, enters the femoral 
ring by crossing the direction of the spermatic cord, places itself between the 
small oblique and transverse muscles of the abdomen, passes forward 
along the external border of the great rectus muscle, and finally enters the 
substance of that muscle, where its terminal divisions anastomose with those 
of the anterior abdominal artery. The numerous collateral branches this 
artery throws off on its track principally go to the rectus muscle, or the 
other parts composing the inferior abdominal wall, the skin included; the 
superior branches communicate with the circumflexa ilii. 

The position this artery occupies at its origin, and with reference to the 
abdominal ring, is worthy of, remark; indicating, as it does, that in 
strangulated inguinal hernia division of the ring should be made outwards, 
to avoid wounding the vessel. 

ExternaL Pupio Artery (Fig. 275, 6).—This artery descends at first 
on the posterior wall of the inguinal canal, behind, and a little to the inside 
of, the spermatic cord ; then, having passed the inferior ring of the canal, it 


548 THE ARTERIES. 


bifurcates into the subcutaneous abdominal artery, and the anterior dorsal 

tery of the penis. : 
i the es abdominal artery is directed forward on’ the superficial 
face of the abdominal tunic, bordering in its course the insertion of the 
suspensory ligament of the sheath. Arriving at the anterior extremity. 
of that ligament, it terminates in: several subcutaneous divisions, one of 
which is inflected beyond the umbilicus to anastomose en arcade with 
a similar branch from the opposite artery. It gives off twigs to the scrotum, 
sheath, superficial inguinal glands, skin, &e. (Fig. 275, 7). : 

The anterior dorsal artery of the penis gains the superior border of 
that organ, after supplying one or two scrotal branches, and separates into 
two portions ; one, posterior, meets the dorsal cavernous artery of the penis 
and anastomoses with it; the other, anterior, longer, more voluminous, and 
very flexuous during retraction of the penis, follows the dorsal border of the 
organ to its anterior extremity, where it enters the erectile tissue that forms 
this part. From the two branches of this anterior dorsal artery, there are 
given off, as in the posterior one, ramuscules which penetrate the corpus 
cavernosum, and the walls of the urethra; they give, besides, some preputial 
twigs (Fig. 275, 8). 

In the remauu, the external pudic artery offers a disposition which, if not 
similar, is yet analogous to that just indicated. As in the male, this vessel . 
traverses the inguinal canal, and after leaving it divides into two branches: 
one, the anterior, or stibcutaneous abdominal artery, the other the posterior, or 
mammary artery. The last, the most voluminous. represents the dorsal 
artery of the penis. It distributes several branches to the mammary tissue, 
and is prolonged between the thighs by a perineal branch, which terminates 
in the inferior commissure of the vulva, after giving off glandular and 
cutaneous branches. 


2. Profunda Femoris, Great Posterior Muscular Artery of the Thigh, or Deep 
Muscular Artery. (Fig. 277, 14). 


Arising in common with the prepubic artery, the profunda femoris passes 
backward, penetrates between the iliacus and the pectineus muscles, afterwards 
between the latter and the external obturator muscle. In this way it arrives 
béneath the deep face of the adductors of the thigh, when it becomes inflected 
behind the femur, and: disappears in the substance of the internal and 
posterior crural muscles by ascending branches, which anastomose with the 
ischiatic artery, and descending and internal branches, whose terminal 
ramifications open into those of the obturator artery. 

es principal twigs of the coxo-femoral articulation are derived from this 
vessel, 


83. Superficial Muscular, or Great Anterior Muscular Artery. (Fig. 277, 15.) 


Smaller than the preceding, and commencing opposite to it, but a little 
lower, this artery passes downwards, outwards, and forwards, runs between 


the long adductor of the leg and the musculo-tendinous cone which terminates | 


in common the psoas magnus and iliacus, furnishes some ramuscules to these 
muscles, dips into the interstice separating the vastus internus from the 
anterior rectus of the thigh, and is lost in the mass of the triceps cruris. 

This vessel, therefore, resembles the iliaco-femoral artery, which we 


observed to enter this triceps by penetrating between the anterior rectus and 
the vastus externus. ‘ 


; ened mith 2 z 


$ 


THE EXTERNAL ILIAC ARTERIES. 549 


4. Innominate or Small Muscular Arteries. 


The femoral artery gives off on its course numerous small branches 
destined for the neighbouring muscles, though too diminutive to merit parti- 
cular description. One of these furnishes the nutritive artery of the femur, 
the largest, perhaps, of all the arteries supplying bones. Another (Fig. 277, 
17) sends to the stifle a long articular branch, analogous to the great 
anastomoticus of Man, which descends along the vastus internus, beneath the 
adductors of the leg, at the interstice which separates these two muscles. 


5. Saphena Artery. (Fig. 277, 16.) 


This artery, remarkable for its small volume, the length of its course, and 
its connections with the vein whose name it bears, is destined for the skin on 
the inner side of the thigh and leg. 

It takes its origin at an acute angle, from nearly the middle of the femoral 
artery, either alone or in common with one of the principal innominate 
muscular branches, and becomes superficial in passing into the interstice of 
the two adductors of the leg, or in traversing one of these, usually the short 
one or gracilis. It lies on the surface of this muscle, beside the saphena 
vein, and bifurcates at the angle of union of the two roots which constitute 
that vessel. One of the branches accompanies the anterior vein to nearly 
the lower third of the leg ; the other follows the posterior vein, and usually 
anastomoses in the hollow of the hock, above the calcaneus, with a branch 
from the posterior tibial artery, and which also communicates with one of the 
branches of the femoro-popliteal artery. 


Popliteal Artery. (Fig. 277, 18.) 


Preparation.— The preparation which has served for the study of the femoral artery 
being nearly arranged as in figure 277, remove from it the internal gastrocnemius and 
popliteus muscles. 


The above name is given to the continuation of the femoral artery. 
This vessel follows a descending direction behind the femoro-tibial articula- 
tion, between the two gastrocnemii muscles, insinuates itself beneath the 
popliteus, and bifureates at the peroneal arch after a course of from 6 to 
8 inches, to form the posterior and anterior tibial arteries. 

The popliteal artery emits on its track: 1, The femoro-popliteal artery ; 
2, Articular branches; 8, Muscular branches chiefly destined to the 
gastrocnemii muscles, of which it is necessary to particularise one long 
division that descends within the perforatus, in company with the great 
femoro-popliteal nerve, to terminate superficially near’ the tendo-Achillis, 
where it anastomoses with a recurrent branch of the posterior tibial 
artery (Fig. 277, 20). 

The femoro-popliteal artery is the . nly one of these collateral branches 
deserving particular mention. Its origin indicates the limit of the femoral 
and popliteal arteries, as it is detached at a right angle below the ring of 
the great abductor of the thigh, at the intermediate point of these two 
vessels. Placed between the semimembranosis and semitendinosis 
muscles on the one part, and the long vastus on the other, this vessel is 
directed from before to behind, and arrives at nearly the posterior border of 
the buttock, where it terminates in subcutaneous branches, after emitting 
descending and ascending branches. Among the first of these, which are 
principally destined to the gastrocnemii muscles, sometimes exists the 


38 


550 THE ARTERIES. 


satellite branch of the sciatic nerve, and a thin twig which descends with 
the external saphena nerve into the hollow of the hock, where it meets, like 
the preceding, a branch of the posterior tibial artery. Several of the 
ascending branches pass along the great femoro-popliteal nerve, and all 
anastomose either with the deep femoral, or with the ischiatic arteries in the 
substance or interstices of the ischio-tibial muscles (Fig. 277, 19). 


TERMINAL BRANCHES OF THE POPLITEAL ARTERY. 


1. Posterior Tibial Artery. (Fig. 277, 21.) 
Preparation —Follow the indications furnished by figure 277. 


At first situated deeply behind the tibia, beneath the popliteal muscles 
and the oblique and deep flexors of the phalanges, this artery descends 
towards the hollow of the hock, becoming gradually more and more super- 
ficial, and lying below the tibial fascia, behind the tendon of the oblique 
flexor muscle, along with its satellite vein. Arriving at the apex of the 
os calcis, it crosses the precited fascia, describes an § curve, and, along 
with the sciatic nerve, passes beneath the tarsal arch; at the astragalus it 
separates into two terminal branches—the plantar arteries. 

Collateral branches—We cite: 1, Numerous branches destined to the 
posterior deep tibial muscles; 2, The medullary artery of the tibia; 3, The 
tarsal articular arteries, a principal of which, with a large venous arch, 
passes under the perforans, near the inferior extremity of the tibia, to be 
distributed outside the tarsus by descending ramuscules and ascending twigs, 
which extend as far as the gastrocnemii tendons; 4, A superficial ascending 
branch, arising ordinarily from the second inflexion of the § curvature 
formed by the artery at its lower extremity, situated in the hollow of the 
hock, anastomosing with the saphena artery, as well as with the satellite 
popliteal branch of the sciatic nerve, and whose ramifications, nearly all 
subcutaneous, are scattered, within and without, on the sides of the hock 
and the inferior extremity of the thigh. 

Terminal branches.—The two terminal branches of the posterior tibial 
artery are slender vessels, vestiges of the plantar arteries in Man. Lying on 
the outer side of the synovial tendinous sheath lining the tarsal groove, they 
are placed, one within, the other without, the perforans tendon, and descend 
along with the plantar nerves to the upper extremity of the metatarsus, 
where they leave the nerves, each to anastomose with the perforating pedal 
artery, and form a kind of deep arcade across the upper extremity of the 
suspensory ligament of the fetlock: that is, from the post-metatarsal fibrous 
band which represents the interosseous plantar muscles of tetradactylous or 
pentadactylous animals. 

In their course, these plantar arteries only distribute some insignificant 
ramuscules to the tarsal articulations. 

From the convexity of the arch they form in uniting with the perforating 
pedal artery, arise four long descending branches: 1, Two superficial, 
innominate and very fine twigs accompanying the plantar nerves, and 
creeping by the side of the flexor tendons to the sesamoid groove, where 
they inosculate with the collaterals of the digit (Figs. 277, 24; 278, 8); 
2. Two deep branches constituting the plantar interosseous arteries, dis- 
tinguished into external and internal. The first is only an extremely fine 
vascular thread, very uncertain in its disposition, and possesses no other 
importance in Solipeds than representing, in a rudimentary state, an 


THE EXTERNAL ILIAC ARTERIES. 551 


artery which is of considerable size in other animals. Placed within the 
external metatarsal bone, it anastomoses, by its inferior extremity, with a 
branch of the metatarsal pedal artery. The internal interosseous plantar artery 
may be considered, if we would neglect the study of analogies, as the continua- 
tion of the perforating pedal artery, which it rivals in volume. It descends 
to the external side of the internal metatarsal bone, beneath the margin of the 
suspensory ligament of the fetlock, and terminates a little above the tubercle 
of the external metatarsal bone, in uniting ata very acute angle with the 
metatarso-pedal artery. It gives off on its tract: the medullary branch of 
the principal metatarsal bone; a small branch to the external interosseous 
artery ; several ramuscules which transversely cross the posterior border 
of the internal metatarsal bone to supply the cellular tissue, the skin, and 
the tendons applied to the median metatarsal bone. 


2. Anterior Tibial Artery. (Fig. 278, 1.) 
Preparation,— Expose the artery by removing the anterior muscles of the leg. 


The anterior tibial artery is the largest of the two branches terminating 
the popliteal trunk. It traverses the tibia! or tibio-peroneal arch, and, with 
its satellite veins, places itself on the anterior aspect of the tibia, down 
which it passes by following the deep face of the flexor muscle of the 
metatarsus. On reaching the front of the tibio-tarsal articulation, it loses 
its name and takes that of the pedal artery. 

The anterior tibial artery gives off a great number of collateral branches, 
which are principally distributed among the tibial muscles. One of them, 
descending along the fibula, beneath the lateral extensor muscle of the 
phalanges, clearly represents a trace of the peroneal artery of Man. 


8. Pedal Artery. (Fig. 278, 1’.) 


A continuation of the anterior tibial artery, whose name changes on its 
arrival in the region of the foot, the pedal artery courses downward over the 
anterior face of the tibio-tarsal articulation, by bending slightly outwards, 
and passing beneath the cuboid branch of the flexor muscle of the metatarsus. 
At the second row of tarsal bones it divides into two branches, which we 
will designate the perforating pedal, and the metatarso-pedal arteries,’ the 
latter continued inferiorly by the digital arteries, or collaterals of the digit. 

The collateral branches emanating from this vessel are all articular 
cutaneous, and of no importance.” 

Prrroratinc Prepau Artery.—It crosses the tarsus from before to 
behind, by passing, with a venous branch, into the canal between the 
cuboid, scaphoid, and great cuneiform bones; it then joins the arch formed 
by the anastomoses of the two plantar arteries—terminal divisions of the 
posterior tibial (Fig. 278, 2). 

METATARSO-PEDAL OR ConLATERAL ARTERY oF THE Cannon.2—Much 


1 The vessel we have here named the perforating pedal artery is only the like 
termination of the same artery in Man. The metatarso-pedal artery ought to be regarded 
as the representative of one of the dorsal interossei arteries, because of its position in the 
interstice of the middle and external lateral metatarsal bones. The dorsal interstice of 
the inner side also lodges an interosseous branch, usually supplied by the external 
plantar artery ; but its diameter is so diminished that, in order to avoid complexity by 
introducing an almost useless element into the didactic description of the posterior 
tibial artery, we have thought it our duty to neglect its indication. : 

2 One of these may be regarded as the analogue of the dorsalis pedis of Man. 

” Rigot has designated this artery—we do not know why—the superficial plantar artery. 


552 THE ARTERIES. 

larger than the preceding, this vessel (Fig. 278, 3) may be considered as a 
continuation of the primitive pedal artery. It is lodged at first in the 
fissure situated outside the middle metatarsal bone, in front of the external 
metatarsal bone, and afterwards passes between these two bones, above the 
tubercle terminating the latter, reaching the posterior face of the first, 


PRINCIPAL ARTERIES 


AND VEINS OF THE 
POSTERIOR FOOT. 

1, Anterior tibial ar- 
tery; 1’, Pedal ar- 
tery; 2, Perfora- 
ting pedal artery ; 
38, Metatarso-pedal, 
or collateral artery 
of the cannon; 4, 
Digital artery ; 5, 
Anterior tibial ar- 
tery; 6, Posterior 
root of the internal 
saphena vein; 7, 
Origin of the ex- 
ternal saphena vein; 
8,9, 10, Metatarsal 
veins; 11, Digital 
veia; 12, Venous 
Plexus of the foot. 


between the two inferior branches of the suspensory 
ligament, above the sesamoid groove, where the vessel 
bifureates to form the collateral arteries of the digit. 

The collateral artery of the cannon receives, a short 
distance above this terminal bifurcation, the internal 
plantar interosseous artery. 

On its course it gives off: 1, Numerous anterior 
ramuscules for the cellular tissue, tendons, ligaments, 
and the skin on the anterior face of the metatarsus and 
fetlock; 2, Some thin posterior divisions, one of which 
ascends within the external metatarsal bone to anastomose 
with the external plantar interosseous artery, after fur- 
nishing several ligamentous, tendinous, and cutaneous 
ramuscules in the posterior metatarsal region. 

Dierra, ARTERIES, OR COLLATERAL ARTERIES OF THE 

Dierr (Figs. 277, 25; 278, 4; 283, 11).—Remarkable 
for their volume, these arteries carry blood to the 
keratogenous apparatus enveloping the ungual phalanx, 
and from this destination derive such importance that 
they deserve a detailed study. 
‘Origin —The digital arteries succeed the terminal 
extremity of the collateral of the cannon, and separate 
from one another in forming an acute angle below the 
sesamoid venous arch, above the fetlock joint, between 
the two branches of the suspensory ligament, behind the 
inferior extremity of the principal metatarsal bone, and 
in front of the flexor tendons of the phalanges. 

Course and Relations. —These vessels descend, one to 
the right, the other to the left, from the lateral parts of 
the metacarpo-phalangeal (and  metatarso-phalangeal) 
articulation to the internal face of the basilar process, 
where they bifurcate to form the plantar and preplantar 
ungueal arteries. 

“In the whole of this course, it (the digital artery) 
follows the track of the flexor tendons, on whose margin 
it rests, and where it is maintained by loose connective 
tissue. Behind, it is flanked by the plantar nerve, which 


It would have been better to have allowed it to retain the name 
given to it by Girard—the lateral artery of the cannon. This is 
not the only instance in which the attempts of Rigot to conform the 
nomenclature of the arteries to that of anthropotomists has proved 
unfortunate, as he has not always succeeded in finding in the 
Horse the real representatives of arteries in Man. The aim of 
this work does not allow us to discuss the vicious determinations 
and denominations of Rigot every time we mect them. We 
are content to change them, purely and simply, leaving to the 
judgment of the reader, should this matter iuterest him, the task 
of deciding if we are right. 


THE EXTERNAL ILIAC ARTERIES. 553 


covers a portion of its surface, enlaces it with numerous filaments, and is so 
ela associated with it in all its flexuosities as to form but a single cord 
with it. 

“In front, it is margined, though for a short distance, by its satellite 
vein, which for the whole of its track rests on the lateral faces of the two 
first phalanges. 

‘“‘ At its upper part, near its origin, and on the lateral portions of the 
metacarpo-phalangeal articulation. the digital artery is crossed from behind 
to before by the anterior branch of the plantar nerve, and it is covered for 
the whole of its extent by the fascia which continues the proper tunic of the 
plantar cushion, whose lateral ligamentous band cuts its direction obliquely 
aie above to below and behind to before, at the middle portion of the first 

alanx,’” 

Collateral divisions.—These are: 1. At the fetlock, numerous fine 
branches distributed to the metacarpo-phalangeal articulation, but par- 
ticularly to the sesamoid sheath, and the tendons lodged in it. 

2. To the environs of the upper extremity of the first phalanx, a slightly 
ascending and sometimes voluminous twig, for the tissue of the ergot (the 
horny tubercle behind the fetlock). 

3. Towards the middle of the same bone, the vessel named by Percivall 
the perpendicular artery, and correctly so, for it arises at a right angle from 
the digital artery to divide almost immediately afterwards into two series of 
ramifications—anterior and posterior. The anterior branches are in nearly 
every instance two principal: one ascending, passing beneath the check 
band of the extensor tendon, and climbing to the capsular ligament of the 
fetlock joint to meet the arterial divisions furnished directly to that ligament 
by the collateral artery of the cannon; the other descending, which reaches 
the side of the second phalanx, where its ramuscules anastomose with the 
coronary circle and the circumflex artery of the coronary substance (cushion). 
The posterior ramifications consist most frequently of two principal branches, 
—one ascending, the other descending ; these insinuate themselves between 
the flexor tendons and the sesamoid ligaments, to be distributed to these 
organs, but especially to the synovial membrane lining the large sesamoidean 
sheath. Sometimes it is seen to arise alone from the digital artery. It must 
here be noted, that the divisions furnished by the anterior branches of this 
perpendicular artery communicate with those of the opposite side in front 
of the first phalanx, either above or below the principal extensor of the 
digit; and that the posterior branches exhibit a series of analogous anasto- 
moses. The body of the first phalanx is therefore enveloped on every side 
by an arterial plexus. 

4, At different elevations on the first and second phalanges, several 
tendinous and cutaneous twigs, which are of no importance. 

5. The artery of the plantar cushion, which arises at the superior border 
of the lateral cartilage, is directed obliquely backward and downward, and 
placed within the posterior border of that cartilage, to be distributed to 
the middle portion of the complementary apparatus of the third phalanx, as 
well as to the villous tissue and the coronet. The branch expended in the 
latter sometimes proceeds. directly from the digital artery; it is a very 
remarkable vesssel, is inflected from before to behind, crossing the posterior 
border of the pedal cartilage, creeping on the internal face or in the texture 
of the skin, a little above the coronet, parallel with that portion of the 


1 FH, Bouley.—‘ Traité de Organisation du Pied du Cheval.’ Paris, 1851. 


554 THE ARTERIES. 


keratogenous apparatus, and terminates by anastomosing with a branch of 
the artery now to be noticed. ; 

6. The coronary circle, formed by two transverse branches—one anterior, 
the other posterior, springing at a right angle from the digital artery, under 
the cartilaginous plate of the os pedis—passes around the coronary bone to 
meet the analogous branches of the opposite artery, to anastomose with them 
directly and by inosculation. The coronary circle therefore presents two 
distinct portions: one posterior, placed above the superior border of the small 
sesamoid, beneath the perforans tendon ; the other anterior, more extensive 
and voluminous, covered on the sides by the lateral cartilages of the foot, 
and in its front or middle part by the expansion of the anterior extensor 
tendon of the phalanges. 

The collateral ramuscules furnished by the posterior part of the circle 
are small, few, and of no interest. 

Among the branches arising from the anterior portion, there is only a 
single pair of arteries to be noted, which are remarkable for their mode 
of distribution and their volume. They originate near the border of 
the extensor tendon, and immediately divide into two divergent branches: 
one the internal, which passes across that tendon to anastomose with the 
homologous branch of the opposite side; the other, external, passes backward 
to meet the cutigeral branch furnished by the artery of the plantar 
cushion, and joins that vessel. From this disposition results a very fine 
superficial vascular arch around the coronet, which is well named the 
circumflex artery of the coronary cushion ; it is situated a little above the 
cutidural artery, beneath the skin of the coronet, and looks as if incrusted 
in that membrane; by its two extremities it rests on the arteries of the 
plantar cushion, and is fed by the two principal vessels of the coronary 
circle; while it furnishes ascending anastomosing ramuscules to the inferior 
divisions of the perpendicular artery, as well as numerous descending 
branches passing into the coronary cushion and the laminal tissue of the 
foot. 

Such is the ordinary disposition of the coronary circle and its super- 
ficial arch—the circumflex artery of the coronary substance ; though it varies 
much in different animals, and even in the feet of the same animal. To attempt 
to describe here the variations we have seen would be supererogatory, and we 
may limit ourselves to saying that these varieties were almost exclusively 
confined to the origin of the branches composing these two circular vessels 
and their manner of arrangement, without modifying in any way the general 
disposition of the circles.? 

Terminal divisions.—These are, as has been already mentioned, the plantar 
and preplantar ungual arteries.* 

a. The preplantar ungual artery is the smallest of these two terminal 
branches. Situated at first inside the basilar process of the third phalanx, 
it turns round this to traverse the notch which separates this process from 
the retrossal eminence, is lodged with a satellite nerve in the preplantar 


1 So named because it neircles the coronet. 

* We may notice here one of these variations, which is somewhat frequently met 
with in the anterior limb. This consists in the anterior descending branch of the 
perpendicular artery uniting at its terminal extremity with the circumflex artery of the 
coronary substance, which it concurs to form. 

% In all treatises on anatomy these vessels are simply designated the plantar and 
preplantar arteries. We have added the epithet ungueal to distinguish these arteries 


from the properly so-caile plantar branches—the terminal divisions of the posterior 
tibial artery. 


THE EXTERNAL ILIAC ARTERIES, 555 


fissure, which it crosses from before to behind, and terminates near its 
auterior extremity by several divisions that bury themselves in the os 
pedis. In its course, it distributes: 1, Before passing into the sub-basilar 
notch, a deep retrograde branch destined to the bulb of the heel and the 
villous tissue; 2, Immediately after leaving that notch, a second retrograde 
branch, whose divisions pass backward, behind the great circumflex artery of 
the pedal bone; 3, During its passage in the preplantar fissure, several ascend- 
ing and descending branches which ramify in the laminal tissue; the first 
anastomose with the descending divisions of the coronary circle and the 
circumflex artery of the coronary cushion. 

b. The plantar ungual artery ought to be regarded as a continuation of 
the digital artery, because of its volume and direction. Lodged at first, 
with a fine nervous branch, in the plantar fissure, it afterwards enters the 
canal of the same name, and thus penetrates into the semilunar sinus of the 
os pedis, where it anastomoses by inosculation with the opposite artery, 
forming a deep vascular arcade which we designate the plantar arcade or 
circle, or, after M. H. Bouley, the semilunar anastomosis (Fig. 283, 12). 

Two orders of branches emanate from the convexity formed by this 
anastomotic loop. The ascending order “ irradiate in the spongy framework 
of the third phalanx, and like so many hair-roots, escape by numerous open- 
ings from its anterior face, where they form a very intricate plexus by anasto- 
mosing, in the texture of the laminal tissue, with the extreme divisions of the 
anterior branch of the digital artery and those of the coronary circle... . . 
It is to these divisions that Spooner has given the name of anterior laminal 
arteries.’ —H. Bouley. 

The descending order, much more considerable, named by Spooner (W. C., 
of Southampton) the inferior communicating arteries, arise at a right angle from | 
the anterior circumference of the semilunar anastomosis, traverse in a diver- 
gent manner the tissue of the phalanx, and make their exit by the large fora- 
mina situated a little above the inferior border of the bone, where they furnish 
a multitude of ascending ramuscules which concur to form the arterial net- 
work of the laminal tissue. ‘Then they anastomose transversely by a 
succession of little arcades which are thrown from one to the other, and in 
this way give rise to a great circumflex canal which follows the contour of the 
parabolic curve exhibited by the thin border of the os pedis, on its inferior 
face.”—H. Bouley. This vascular arcade, which we purpose naming the in- 
ferior circumflex artery of the foot, to distinguish it from the circumflex of the 
coronary cushion, is joined by its extremities to the preplantar artery, in the 
same manner that the latter circumflex is united to the artery of the plantar 
cushion. From its concavity it throws off some fourteen or fifteen con- 
vergent branches, which are destined to the villous tissue of the sole. 


DIFFERENTIAL CHARACTERS OF THE EXTERNAL ILIACS IN OTHER THAN SOLIPED ANIMALS, 
1. External Iliac Arteries of Ruminants. 


In the Oz, apart from the considerable volume of the great muscular arteries of the 
thigh, the crural trunk, as well as the femoral and popliteal arteries continuing it, 
comport themselves almost the same as in the Horse. It is only when we reach the 
posterior and anterior tibial arteries that we find some peculiarities worthy of notice. 

Posterior tibial artery.—Much more voluminous than that of Sulipeds, this artery follows 
the same track, and terminates in an analogous manner : forming at its lower extremity 
two plantar branches, which anastomose with the perforating pedal artery behind the 
superior extremity of the principal metatarsal bone, and beneath the suspensory ligament. 
But these two branches are far from possessing the same volume; the internal is in- 
comparably the largest, and appears to be the direct continuation of the posterior tibial 
artery. 


556 THE ARTERIES. 


From this anastomosis results, as in the Horse, two series of metutarsal branches—a 
x y cial. i 
i ie as two or three in number, form on the posterior face of the 
metatarsal bone, below the suspensory ligament, the posterior interossex, mixed with 
two or three reticulated venous branches, and anastomose by their inferior extremity 
with a perforating branch of the collateral of the cannon, ; 

The superficial branches, similar to those which accompany the plantar nerves in the 
Horse, are of very unequal calibre: the external is so rudimentary that it often escapes 
dissection; the internal in reality continues the plautar artery of the same side. Both are 
uuited tu the perforating branch already noticed. fi 

Anterior tibial artery.—After passing down along the leg on its antero-external face, 
as in Solipeds, this vessel arrives on the hock, where it takes the name of pedal 
artery, and furnishes the perforating-pedal artery ; it is continued by the metatarso-pedal 
or collateral artery of the cannon. 

a. The eer pedal artery does not differ from that of the Horse. ; 

b. The metatarso-pedal, or collateral of the cannon, descends, flanked by two satellite 
veins, in the channel on the anterior face of the metatarsal bone, giving off towards the 
inferior extremity of that channel the perforating branch already spoken of, and is 
continued into the digital region as the common digital artery. _ ' 

The perforating branch of the collateral of the cannon passes into the foramen pierced 
from before to behind, across the inferior extremity of the metatarsal bone, arriving 
beneath the suspensory lig«ment, and then divides into several ascending and descending 
branches. The first join the deep and superficial poste1ior metatarsal arteries furnished 
by the plantar and pedal perforating arteries. Among the second, we notice three digital 
arteries, fac-similes in miniature of those which will be described in the anterior 
limb: two lateral, descending on the excentric side of the phalanges; a median, 
turning within the flexor tendons to place itself behind them on the middle line of the 
digital region, and prolonged into the interdigital space, where it anastomoses with a 
brauch of the principal artery of the digits. 

The latter artery, the common digital, descends into the space between the digits, 
after passing beneath the capsular ligament of the metatarso-phalangeal articulations, in 
tue notch comprised between the two articular surfaces of the metatarsal bone, and 
terminates above the inferior extremity of the first phalanx by two ungueal arteries, 

‘ whose description will be reserved until describing the arteries of the anterior limb, 
In the number of collateral branches emanating from this vessel, there my be particularly 
remarked a large off-shoot which arises a little before the separation of the two ungueal 
arteries, and is directed from before to behind, dividing at the posterior part of the 
interdigital space into several divisions, the principal of which are: 1, Two transverse 
branches passing between the flexor tendous and the phalanges, to be joined to the 
lateral digital arteries; 2, A single ascending branch, joining with the posterior median 
digital artery; 3, A descending branch, also single, dividing into two portions which 
reach the heels, to be distributed to the plantar cushion and the villous tissue. These 
branches represent the arteries of the plantar cushion in the Horse, and will be noticed 
more in detail in the description of the arteries of the anterior limb, where in 
priuciple they are found to be exactly like these. : 


2, External Iliae Arteries of the Pig. 


The distribution of these vessels in the Pig is remarkably like that we have described 
as existing in Ruminants, even in the terminal portions of the limbs, notwithstanding 
the complete development of the two lateral digits. It may be noted, however, that the 
posterior tibial artery is somewhat slender, and that it is singularly reinforced by its 
anastomosis with the saphena artery, whose dimensions are relatively considerable! 


3. External Iliae Arteries of Carnivora. 


The crural trunk is divided in the Carnivora, as in the other animals, into three 
sections: the proper iliac artery, the femoral artery, and the popliteal artery, terminated 
by the tibial branches. 

Proper iliac artery.—This vessel does not give rise to any branch, as the cir- 
cumflexa ilit comes directly from the abdominal aorta, 


‘In small Ruminants, the posterior tibial artery, properly speaking, is equally 
rudimentary; the saphena artery constitutes the principal vessel. From a note which 
we made a long time ago, it appears the first vessel is altogether absent sometimes, and 
that the plantar divisions come exclusively from the saphena, as in the Carnivora, 


THE EXTERNAL ILIAC ARTERIES. 557 


Femoral artery—As in the Horse, this gives off: 1, Several muscular innominate 
branches ; 2, Two great muscular arteries, the posterior of which furnishes the prepubic 
artery ; 3, A saphenal branch. 

In the Bitch, the external pudic artery, emanating from the prepubic division, presents 
some peculiarities in its distribution: it gives off a long branch which is placed in the 
texture of the mamme, and passes forward to meet and unite with the mammary branch 
furnished by the internal thoracic artery; it then runs between the two thighs in a 
tlexuous manner, and reaches the lips of the vulva, where it ends in numerous ramuscules 
that anastomose with the vulvular divisions of the internal pudic artery. 

The saphena artery is as remarkable for its large volume as for its destination. It 
descends on the internal face of the leg, furnishing numerous subcutaneous divisions, 
and terminates at the hock by several slender plantar twigs, which accompany the flexor 
tendons. Among the branches given off by tuis vessel in its course, it is necessary to 
distinguish two: one which follows the anterior branch of the saphena vein to the 
hock, where it communicates by its terminal divisions with the tarsal artery; the other 
arises a little lower, passes beneath the phalangeal flexor muscles, and is expended on the 
hock in articular and malleolar branches. In the latter branch we see a trace of the 
peroneal artery of Man. The saphena itself, considered as a whole, and particularly 
towards its inferior moiety, supplements the posterior tibial artery. 

Popliteal artery—This artery gives an important femoro-popliteal branch, and enters 
the tibio-peroneal arcade to constitute the anterior tibial artery, after distributing on 
its course muscular ramuscules—rudiments of the posterior tibial artery of other animals. 

The anterior tibial artery, arriving in front of the huck, detaches the tarsal artery: 
a voluminous branch divided near its origin into several superficial superior and inferior 
branches. It continues to descend, traverses from before to behind the superior part of 
the third intermetatarsal space, and terminates by an arterial arcade situated bencath 
the flexor tendons; from this arcade emanate ascending divisions, which wnastomose 
with the plantar arteries, and three large descending or digitai branches, which affect the 
same disposition as three analogous principal arteries emanating from the superficial 
palmar arcade of the anterior limb. 


COMPARISON OF THE EXTERNAL ILIAC3 OF MAN WITH THOSE OF ANIMALS. 


In Man, the external iliac forms the external branch of the bifureation of the 
common iliac; it extends to the crural arch, where it takes the name of femoral artery. 
It furnishes the cireumflexa ilit and epigastric: the latter resembling, in its distribution, 
the posterior abdominal branch given off by the prepubic artery in the Horse. 

The femoral artery has the same general disposition as in. animals, and almost the 
same collateral branches. There is no prepubic artery; the divisions furnished by this 
trunk in Solipeds originate separately from the femoral artery ; these are: the abdominal 
tegumental artery (superficial epigastric), and the external pudic arteries—ihe one re-~ 
sembling the subcutaneous abdominal artery, and the others the bianches of the external 
pudic artery of animals. . 3 

The popliteal artery is a superficial vessel situated at the posterior face of the knee- 
joint, in a lozenge-shaped space limited by the muscles of the region. and named the 
‘popliteal space. At the tibio-peroneal arch it bifureates, and constitutes the anterior 
tibial and the tibio-peroneal trunks. : ; 

The tébio-peroneal trunk does not exist in animals in which the peroneal artery 
is in a rudimentary state, in consequence of the feeble development of the peroneus. 
This trunk is short, and furnishes the nutrient artery of the tibia, then divides into the 
peroneal and posterior tibial arteries. The first descends to the external malleolus, 
along the inner face of the tibia, and terminates in two branches, one of which, the 
anterior peroneal, communicates with the dorsal artery of the tarsus—a branch of the 
pedal. The posterior tibial, on reaching the concavity of the calcis, constitutes the 
internal and external plantar arteries. The internal plantar is directed forwards, beneath 
the sole of the foot, and is lost in the muscles of the great toe, or forms the collateral of 
the latter vessel. Beneath the tarsal articulations, the external plantar describes a curve, 
having its con-avity backwards, and anastomoses, at the fourth intermetatarsal space, 
with the termination of the dorsalis pedis; from this results a plantar arch, which gives 
off, from without to withiu: 1, The external collateral of the little toe; 2, 3, 4, 5, the 
interosseous plantar (or digital) arteries of the first, second, third and fourth inter- 
metatarsal spaces; these arteries, at the root of the toes, bifurcate to furnish collaterals 
fi ‘te Ae re tibial artery, situated on the anterior face of the interosseous ligament 
that unites the tibia to the peroneus, extends to the annular ligament of the tarsus, 


558 THE ARTERIES. 


where it is continued by the dorsalis pedis, which descends along the dorsum of the foot 


i it of the fourth interosseous space. Ne : ; 
- “The Seer of the metatarsus (metatarsea) is almost nl in Solipeds. In Man it 


\ 


ANTERIOR ASPECT OF HUMAN LEG AND FOOT. 


1, Tendon of insertion of the quadriceps ex- 
tensor muscle; 2, Insertion of the ligamen- 
tum patelle; 3, Tibia; 4, Extensor longus 
digitorum; 6, Peronei; 7, Inner belly of 
gastrocnemius and soleus; 8, Annular 
ligament ; 9, Anterior tibial artery; 10, 
Its recurrent branch inosculating with (2) 
inferior articular and (1) superior articular 
arteries, branches of the popliteal; 11, 
Internal malleolar artery; 17, External 
ditto, inosculating with anterior peroneal 
artery, 12; 13, Dorsalis pedis artery; 14, 
Tarsea and metatarsea; 15, Dorsalis hal- 
lucis artery; 16, Continuation of dorsalis 
pedis into sole of foot. 


POSTERIOR ASPECT OF HUMAN LEG. 


1, Tendons of inner ham-string ; 2, Ditto ot 


biceps; 3, Popliteus muscle; 4, Flexor 
longus digitorum; 5, Tibialis posticus ; 
6, Fibula; 7, Peronei muscles; 8, Lower 
portion of flexor longus pollicis, with its 
tendon; 9, Popliteal artery, giving off 
articular and muscular branches; 10, An- 
terior tibial artery; 11, Posterior tibial 
artery; 12, Relative position of tendons 
and artery ; 13, Peroneal artery; 14, Pos- 
terior peroneal, 


is directed transversely to the tarsus, from within to without; its terminal branches 
unite on the dorsum of the tarsus, and the arch it forms gives off the dorsal interosseous 
arteries of the three first spaces. These communicate above and below in the inter- 


THE BRACHIAL OR AXILLARY ARTERIES. 559 


metatarsal spaces, with the plantar interosscous arteries by the anterior and posterior 


perforating arteries ; finally, at the base of the toes they bifurcate to form the collateral 
arteries of the toes. 


The dorsal collateral artery of the fourth space represents 
the vessel described in the Horse by the name of metatarso- 
pedal artery, or collateral of the cannon; it forms the in- 
ternal collateral dorsal of the fourth toe, and external collateral 
of the great toe. 

The dorsalis pedis, after giving off the last-named vessel, 
dips into the fourth space and reaches the lower surface of 
the foot, where it anastomoses with the internal plantar artery. 
In this last portion of its course it resembles the vessel we 
have named the perforating pedal in Solipeds. 


Articie V.—Anterion Aorta. (Fig. 282, 1.) 


This vessel, the smallest of the two trunks suc- 
ceeding the common aorta, is no more than 2 or 24 
inches in length at the most. It leaves the pericar- 
dium to pass between the two layers of the medias- 
tinum in an oblique direction from below upwards 
and behind forwards, above the right auricle, below 
the trachea, and to the left of the anterior vena cava. 
After furnishing some insignificant twigs to the 
pericardium and mediastinum, it divides into two 
branches which constitute the brachial trunks or 
axillary arteries. 

In the Pachyderms and Carnivora, the anterior 
aorta does not exist, and the axillary arteries arise 
directly from the aortic trunk, towards the point 
from which the anterior aorta springs in other 
animals. 


ARTERIES OF SOLE OF 
HUMAN FOOT. 


1, Under surface of os cal- 
cis; 2, Musculus acces- 
sorius; 3, Long flexor 
tendons; 4, Tendon of 
peroneus longus; 5, Ter- 


ArticLe VI.—Bracutat Trunks or AXILLARY 
Arreries. (Fig. 282, 2, 3.) 


The brachial trunks, terminal branches of the 
anterior aorta, are distinguished into left and right. 
The latter is much larger than the former, because 
it furnishes the arteries of the head. It is also 
named the brachio-cephalic trunk (or arteria innomi- 
nata). 

Origin.—They separate from one another at an 


mination of posterior 
tibial artery; 6, Internal 
plantar; 7, External 
plantar ; 8, Plantar arch 
giving off four digital 
branches, three of which 
are seen dividing into 
collaterals for adjoining 
toes. 


acute angle, the left being a little more elevated 
than the right. 

Course and direction.—Both branches are directed forwards, between the 
lamine of the anterior mediastinum and beneath the trachea; gaining the 
entrance to the chest, and leaving it by turning round the anterior border 
of the first rib, under the insertion of the scalenus, they become inflected 
backwards and downwards, to be placed, one to the right, the other to the 
left, at the internal face of the anterior limb, in the middle of the nervous 
branches of the brachial plexus, and continue within the arm, assuming the 
name of humeral artery on leaving the interstice which separates the sub- 
scapularis muscle from the adductor of the arm. 

In its thoracie course, the left trunk describes a curve whose convexity 
is upwards, the right taking a rectilinear direction. 

Relations.—In studying the relations of the brachial trunks, we recognise 
two principal portions: one thoracic, placed in the chest; the other axillary, 


560 THE ARTERIES. 


situated beneath the limb. In their thoracic portion, the orachial trunks, 
at first lying beside each other, separate slightly in front to reach the interna] 
face of each of the two first ribs. They are accompanied by the cardiac, 
pneumogastric, inferior laryngeal, and diaphragmatic nerves, and are in- 
cluded, as already noticed, between the two layers of the anterior medias- 
tinum. ‘I'he right occupies nearly the median line beneath the inferior face 
of the trachea, to the left and above the anterior vena cava. The left 
slightly rises on the side of the trachea, and generally corresponds inwardly 
to the thoracic duct. : 

In their axillary portion, these vessels accompany the corresponding 
venous trunks, cross the terminal tendon of the subscapularis muscle in 
passing below the humeral insertion of the pectoralis magnus, and among 
the branches of the brachial plexus, but embraced more particularly by 
the median, anterior humeral, and ulnar nerves. 

Distribution.—The axillary arteries give off, on their course, eight col- 
lateral branches. Four arise from the thoracic portion: three upper, the 
dorsal, superior cervical, and vertebral arteries ; and an inferior, the internal 
thoracic. Two are detached at the first rib: one downwards, the other 
‘forwards; these are the external thoracic and superior cervical arteries. ‘Two 
originate from the axillary portion of the trunk and pass upwards: they are 
the super- and subscapular arteries. After furnishing the latter vessel, the 
brachial trunk is continued by the humeral artery. 

Independently of all these branches, the right axillary artery gives off, 
near its origin, the common trunk of the two carotid arteries, which will be 
studied in a separate article. 


Preparation.— The subject being placed on the right side, remove the skin and the left 
anterior limb, in order to make the dissection at two periods. 

First pertod.—Dissect all the intra-thoracie portion of the left axillary artery and its 
collateral branches, as in figure 282, taking care to leave the inferior cervical artery (which 
has been cut in the figure to render the drawing more distinct) attached by its superior 
extremity to the middle portion of the mastoido-humeralis, which has not been disturbed. 

Second period.—Prepare, on the separated limb, the extra-thoracie portion of the 
vessel and all the arteries it furnishes, in taking us guides figures 283, 290, and 291. 


COLLATERAL BRANCHES OF THE AXILLARY ARTERIES. 
1. Dorsal, Dorso-muscular or Transverse Cervical Artery. (Fig. 282, 4.) 


Chiefly destined to the muscles of the withers, this artery, the first given 
off by the brachial trunk, crosses outwardly the trachea, thoracic duct, 
cesophagus, great sympathetic nerve, and the long muscle of the neck, in 
proceeding beneath the mediastinal layer; it reaches and passes over the 
second intercostal space, bends slightly backwards, and places itself in the 
interstice which separates the angular muscle of the scapula and great 
serratus muscle from the inferior branch of the ilio-spinal muscle (longis- 
simus dorsi), where it separates into several divergent branches. The majority 
of these ascend towards the superior border of the withers, neck, and 
shoulders, by gliding between the latter muscles, the splenius, and the 
small anterior serratus on the one part, and the great serratus, rhomboideus, 
and proper elevator of the shoulder on the other, to be distributed to those 
muscles and the integuments covering them. The most anterior of these 
branches passes between the splenius and the great complexus muscles, 
parallel with the superior cervical artery, which is in front of it, and com- 
municates by its ramuscules with the latter vessel, as well as with the 
verteb:al and occipito-muscular arteries, The last-named branch is some- 


THE BRACHIAL OR AXILLARY ARTERIES. 561 


times long and voluminous, and partly supplements the superior cervical, 
as is exemplified in the specimen which served for Fig. 282. 

Before leaving the thorax, the dorsal artery gives off some unimportant 
ramuscules and the subcostal artery (superior intercostal of Man). This 
branch (Fig. 282, 5) curves backwards and, with the sympathetic chain, places 
itself beneath the costo-vertebral articulations, against the long muscle of 
the neck, furnishing the second, third and fourth intercostal arteries and 
the corresponding spinal branches, and terminating at the fifth intercostal 
space by either forming the artery which descends into that space, in 
anastomosing by inosculation with a branch emanating from the first 
posterior intercostal artery, or by expending itself in the spinal muscles, 
Frequently the second intercostal and its spinal branch come directly from 
the dorsal artery ; the fifth also often arises from the posterior aorta. 

On the right side, the dorsal artery always proceeds from a trunk common 
to it and the superior cervical artery: a circumstance sometimes observed in 
the left. This trunk has no relation with the esophagus. 


2. Superior Cervical, Cervico-muscular, or Deep Cervical Artery. 


(Fig. 282, 6.) 


This vessel arises in front of the preceding artery, affects the same 
relations in the thoracic cavity, which it leaves by passing between 
the two first ribs, behind the last costo-transverse articulation ;? it is 
then directed upwards and forwards, passing beneath the inferior branch of 
the ilio-spinal and great complexus muscles, courses in a flexuous manner 
through the space comprised between the latter muscle on one side, and 
the superior branch of the ilio-spinalis and cervical ligament on the 
other, and arrives at the second vertebra of the neck, where its terminal 
divisions anastomose with the branches of the occipito-muscular, vertebral, 
and even the dorsal, arteries. 

The superior cervical artery distributes in its course: 1, The first inter- 
costal artery and the first spinal branch ; 2, Very numerous branches which 
are expended in the muscles and integuments of the cervical region, as well 
as in the large ligament occupying the middle plane of that region ; among 
these branches, one longer than the others traverses the great complexus 
muscle to place itself between it and the splenius, and which is sometimes 
supplemented in great part by the dorsal artery. 


3. Vertebral Artery. (Fig. 282, 7.) 


Arising at an acute angle from the axillary artery at the first intercostal 
space, and covered at its origin by the mediastinal layer, the vertebral 
artery prockeds forward and upward, within the first rib, outside the 
cesophagus,? the trachea, and the inferior cervical ganglion, and is situated 
at the bottom of the interstice separating the two portions of the scalenus, 
with the fasciculus of branches originating from the brachial plexus, which 
is a little above the vessel. It then passes beneath the transverse process 
of the seventh cervical vertebra, and traverses the series of cervical 
foramina, hidden beneath the intertransverse muscles, to anastomose in 


1 For the description of these arteries, see page 524. 
2 We have seen it escape, along with the dorsal artery, by the second intercostal 


spac 


e. 
2 On the right, these relations with the cesophagus are not present. 


562 THE ARTERIES, 


Fig. 282. 


DISTRIBUTION OF THE ANTERIOR AORTA. 

1, Anterior aorta; 2, Left axillary artery; 3, Right axillary artery; 4, Dorsal 
artery; 5, Subcostal artery; 6, Superior cervical artery; 7, Vertebral artery; 
8, 8’, Inferior cervical artery; 9, Origin of the internal thoracic artery; 10, 
Origin of one of the external or intercostal branches of this artery; 11, One of 
its inferior ramuscules; 12, External thoracic artery ; 13, Origin of the super- 
scapular artery; 14, Primitive, or common carotid artery ; 14’, Accessory thyroid 
artery; 14” Thyro-laryngeal artery ; 15, Atloido-muscular artery; 16, Occipito- 
muscular artery ; 17, Posterior aorta.—a, Pulmonary aorta; B, Trachea; c, Gso- 
phagus; D, Cervical ligament; E, Superior branch of the ilio-spinal muscle; F, 
Inferior branch of the same; G, Great complexus muscle; H, Splenius muscle ; 
I, I, Originating aponeurosis of the splenius and the small anterior serratus 
muscles ; K, Section of the great oblique muscle of the head ; L, Great posterior 
rectus muscle of the head; mM, Great anterior ditto; N, Sterno-maxillaris muscle 5 
©, P, Great pectoral and sterno-prescapularis muscles turned downwards, 


THE BRACHIAL OR AXILLARY ARTERIES. 563 


full canal with the retrograde branch of the occipital artery, at the atlo-axoid 
articulation, underneath the great oblique muscle of the head. 

In its track, it detaches at each intervertebral space numerous branches 
which may be divided into inferior, superior, external, and internal. The 
first chiefly pass to the scalenus, longus colli, and the great anterior rectus 
muscle of the head. The second, which are incomparably larger and more 
numerous than all the others, are destined to the two complex muscles, the 
transverse-spinous (semispinalis) muscles of the neck, and to the ilio-spinal 
muscle; they anastomose with the divisions of the superior cervical and 
occipito-muscular arteries. The external branches, are very small, and 
pass to the intertransverse muscles. The internal branches enter the inter- 
vertebral foramina to join the middle spinal artery. 


4. Internal Thoracic, or Internal Mammary Artery. (Fig. 282, 9.) 


The internal thoracic artery emerges from the brachial trunk at the 
first rib, and immediately descends along the inner face of that bone to the 
sternum, remaining covered by the pleura. It then bends backwards, passes 
under the triangular muscle and above the sternal cartilages, which it 
crosses near the chondro-sternal articulation, and reaches the base of the 
xiphoid appendix, where it ends in two branches: one abdominal, the other 
thoracic, and which have been named the anterior abdominal and asternal 
arteries. 

In its course, the internal thoracic artery sends off collateral branches 
which may be distinguished into superior, inferior, and external, The 
superior are always very slender. and proceed to the pericardium and 
mediastinum. The inferior (Fig. 282, 11) are very large, and traverse the 
intercostal spaces to enter the pectoral muscles, where they meet the ramifi- 
cations of the external thoracic artery. The eaternal branches (Fig. 282, 10) 
follow the intercostal spaces; each generally divides into two branches, 
which finally anastomose by inosculation with the terminal divisions of the 
first seven intercostal arteries. 

Terminal branches of the internal thoracie artery—I1. Anterior ab- 
dominal artery.—This vessel separates from the asternal artery at an acute 
angle, and passes directly backward to escape from the chest by coursing 
beneath the xiphoid appendix; it then places itself on the superior face of 
the rectus muscle of the abdomen, which it enters, after detaching lateral 
branches to the abdominal walls, and anastomoses by its terminal ramifica- 
tions with the posterior abdominal artery. aes ; 

2. Asternal artery—This vessel glides within the cartilaginous circle 
formed by the false ribs, in crossing the digitations of the transverse muscle 
of the abdomen, and terminates at the thirteenth intercostal space, in which 
it ascends to anastomose with the corresponding intercostal artery. It 
supplies in its track: intercostal branches, which comport themselves like 
the analogous branches of the internal thoracic artery ; fine diaphragmatic 
twigs; and abdominal divisions, which particularly ramify in the tranverse 
muscle. 


5. External or Inferior Thoracic, or External Mammary Artcry. 
(Fig. 282, 12.) 

Principally destined to the deep pectoral muscles, this artery commences 
at an acute angle in front of, but close to, the preceding, turns the anterior 
border of the first rib, and then passes back against the internal face of the 
great pectoral and sterno-prescapular muscles, in which are expended its 


564 THE ARTERIES, 


collateral and terminal divisions. It gives off a fine branch which accom- 
panies the spur vein, and ramifies in the panniculus carnosus. — 

This artery sometimes rises from the suprasternal vessel; its’ volume 
is subject to great variations, and we have seen it entirely absent, 


6. Inferior Cervical, or Trachelo-muscular Artery. (Fig. 282, 8, 8'.) 


Originating opposite the two preceding vessels, sometimes near the 
external, and at other times near the internal mammary arteries, this vessel 
is at first situated in the gulf between the jugulars, within the sterno-pre- 
scapular muscle, and above the glands at the entrance to the chest ; it divides 
after a short course into two branches, which separate at a very acute angle. 
One of these, the superior (ascending cervical of Man), rises | between the 
mastoido-humeralis and subscapulo-hyoideus muscles, to which it is dis- 
tributed, as well as to the glands at the point of the shoulder, and the sterno- 
prescapularis and triangularis scapule muscles. ; ; 

The inferior branch (thoracica acromialis of Man) descends in the in- 
terstice comprised between the mastoido-humeralis and the sterno-humeralis 
(pectoralis parvus) muscles, accompanying the cephalic vein; it is distri- 
buted to these two muscles, the sterno-aponeuroticus (pectoralis transversus), 
and the sterno-prescapularis. 


7. Superscapular, or Superior Scapular Artery. (Fig. 282,13.) 


A small and slightly tortuous vessel, which arises from the axillary 
artery, little before it reaches the tendon of the subscapularis muscle. 
It is directed upwards, and enters the space included between that muscle 
and the super- (antea-) spinatus, after sending off some divisions to the sterno- 
prescapularis muscle. Its terminal branches are expanded in the inferior 
extremity of the super- and subspinati muscles, the tendon of the coraco- 
radialis, and in the articulation of the shoulder. 


8. Inferior, or Subscapular Artery. (Fig. 847.) 


This artery is remarkable for its considerable volume; it arises at a 
right angle from the axillary artery, at the space separating the subscapularis 
from the adductor of the arm. Its origin indicates the limit artificially 
fixed between the brachial trunk and the humeral artery. It is seen to 
proceed upwards and backwards in this interstice, within the large extensor 
of the fore-arm, until near the dorsal angle of the scapula, where it 
terminates, 

It gives off on its track : 

1. An artery which, following the inferior border of the great dorsal 
muscle, ascends to its inner face, throwing off twigs into the substance of 
the muscle as well as into the panniculus carnosus. 

2. The seapulo-humeral, or posterior circumflex artery of the shoulder, which 
passes from within that articulation, beneath the great extensor muscle of 
the shoulder, to reach its external face; after giving off some collateral 
branches, it arrives, with the circumflex nerves, underneath the abductors of 
the arm, where it breaks up, like its satellite nerve, into several divergent 
branches destined to the three muscles above named, the oblique flexor and 


short extensor of the fore-arm, and to the mastoido-humeralis and panniculus 
carnosus. 


THE BRACHIAL OR AXILLARY ARTERIES. 565 


3. Muscular branches, which escape at intervals during the course of the 
vessel, and are sent forwards and backwards. The anterior pass either to the 
internal or external side of the scapula, or to both sides of that bone, whose 
posterior border they embrace in their bifurcation. The internal divisions 
creep in the fissures on the deep face of the bone, throwing their ramuscules 
into the subscapularis muscle, and even reaching the supér- (antea-) spinatus 
as well as the insertion of the angularis and great serratus muscles. The 
external divisions traverse the large extensor of the fore-arm, to be dis- 
tributed to the super- and subspinati and the abductor muscles of the arm, 
one furnishing the nutrient artery of the scapula. The postericr branches 
supply the abductor of the arm, and the large extensor of the fore-arm. 


HUMERAL ARTERY, OR TERMINAL ARTERY OF THE BRACHIAL TRUNK. 
(Fig. 347, a.) 


Course.—This, a continuation of the axillary artery, which changes its 
name after giving off the subscapular branch, at first describes a slight 
curve forwards to descend almost vertically within the thoracic limb by 
crossing obliquely the direction of the humerus, and terminates above the 
inferior extremity of that bone by two branches which constitute the anterior 
and posterior radial arteries. 

Relations.—In its course, the humeral artery corresponds: in front, to 
the median or ulno-plantar nerve, and to the posterior border of the coraco- 
humeralis muscle, which it closely follows; behind, to the vein of the arm, 
and through it to the ulnar nerve ; outwardly, to the common tendon of the 
great dorsal muscle and the adductor muscle of the arm, to the middle 
extensor of the fore-arm, and to the humerus; inwardly, to the sheath of the 
coraco-radialis muscle, which separates the pectoralis magnus from the 
artery of the arm, and in which this vessel is inclosed, in common with its 
satellite vein, the lymphatic glands and vessels of the arm, as well as with 
the nerves of the fore-limb. 

Collateral branches—Among these may be distinguished four, which 
merit particular mention. They are the prehumeral, external and internal 
collateral arteries of the elbow, and the principal artery of the coraco-radialis 
muscle. We need only indicate, besides these, several irregular ramuscules 
which go to the latter muscle, to the coraco-humeralis, and to the middle 
extensor of the fore-arm. 

1. Prehumeral, or anterior circumflea artery of the shoulder —This 
arises at a right angle, is directed forward, passes between the two branches 
of the coraco-humeralis, turns round the anterior face of the humerus, 
beneath the bicipital groove, and terminates in the mastoido-humeralis 
muscle. During its progess it gives off branches to the scapulo-brachial 
and biceps muscles, as well as to the articulation of the shoulder. Among 
the articular ramifications, there is one which ascends outwardly on the 
tendon of the subspinatus, and whose ultimate divisions anastomose with the 
ramuscules of the posterior circumflex artery. 

2. Deep humeral, or external collateral artery of the elbow.—A very large 
branch which emerges from the humeral trunk, by forming with that artery 
an almost right angle at the common terminal tendon of the great dorsal 
muscle and the adductor of the arm. After a very short course, it divides 
into two principal branches; one of these sends its ramuscules into the 
body of the large extensor muscle; the other passes under that muscle in 


389 


566 THE ARTERIES. 


turning round the oblique flexor of the fore-arm, along with the radial 
nerve, and reaching beneath the short extensor, to descend, still with its 
satellite nerve, in front of the articulation of the elbow, where this branch 
anastomoses with the anterior radial artery; it supplics-all the olecranian 
muscles, except the long extensor, as well as the oblique flexor of the fore- 
arm and the anterior extensor of the metacarpus. 

3. Epicondyloid, internal collateral of the elbow, or ulnar artery.— 
Smaller than the external collateral, this artery arises at the nutrient 
foramen of the humerus, and proceeds backwards on the internal face of 
that bone, to pass beneath the long extensor of the fore-arm, by following in 
a more or less flexous manner the inferior border of the middle extensor; 
jt then descends, at first behind the epicondyle, then on the fore-arm, which 
it passes along for its whole length, underneath the aponeurotic sheath of 
this region, between the oblique and the external flexor of the metacarpus, 
accompanied by the ulnar vein and nerve of the same name, and the tendon 
of the ulnar portion of the perforans muscle. Arriving near the carpus, 
this long branch anastomoses by inosculation with a branch from the 
posterior radial artery. 

In its antibrachial course, this artery only gives off very attenuated 
branches, whose study is of little importance. But before attaining the 
fore-arm, it furnishes: 1, The nutrient artery of the humerus; 2, Articular 
ramuscules; 3, More or less voluminous muscular branches, particularly 
for the long extensor of the fore-arm, the middle extensor, and the sterno- 
aponeuroticus: those which arrive in the latter muscle traverse it only to 
become subcutaneous alternately ; one of them accompanies the principal 
superficial vein of the fore-arm, and sends ramuscules into the bend of the 
elbow. Regular in their distribution, these different arteries present 
numerous varieties of origin, among which it is difficult to distinguish the 
most constant disposition. The last-mentioned vessel and the nutrient 
artery of the humerus, often emanate directly from the humeral trunk. 

4. Principal artery of the biceps, or coraco-radialis artery. —This 
originates a little below or above the preceding; opposite to, or in front of 
it, it usually divides into two branches: one ascending, the other descending, 
which enter the substance of the muscle. 


1. Anterior Radial Artery. (Fig. 348, a.) 


The anterior radial artery,! the smallest of the two terminal branches of 
the humeral, separates itself at an acute angle from the posterior artery, 
above the articular condyle of the humerus. It descends on the anterior - 
face of the ulnar articulation, passing beneath the inferior extremity of the 
flexor muscles of the fore-arm and the superior extremity of the principal 
extensor of the metacarpus, where it meets the radial nerve; in company 
with this nerve it extends on the anterior face of the radius, below the 
anterior extensor muscle of the phalanges, to the knee, where it becomes 
very thin and breaks up into several ramuscules, which are continued on 
the capsular ligament of the carpal articulations, after anastomosing on 
the inner side with the divisions of a branch furnished by the posterior 


radial artery, and on the outside with the ramifications from the interosseous 
artery of the fore-arm. 


‘In Man this artery is absent, or rather it is represented by an insignificant 
muscular twig. 


THE BRACHIAL OR AXILLARY ARTERIES. 567 


These terminal ramuscules of the anterior radial artery are distributed 
to the carpal articulation, or the sheaths of the extensor tendons, and com- 
municate with the dorsal interosseous metacarpal arteries. 

The collateral branches given off by this artery are very numerous, the 
majority of them being detached from the superior portion of the vessel 
near the elbow; they are intended to supply that articulation, but more 
especially the muscular masses lying in its neighbourhood, or covering it. 

Such is the usual disposition of the anterior radial artery ; though it is 
liable to numerous variations: principally in the manner in which it comports 
itself with the interosseous artery of the fore-arm, which may even supple- 
ment it for the whole of the middle and lower part of its course. This will 
be noted in describing the next artery. 


2. Posterior Radial Artery. (Figs. 283, 1; 347, 3.) 


This vessel, in its volume and direction, represents the continuation of 
the humeral artery. It descends, along with the ulno-plantar nerve, on the 
internal ligament of the humero-radial articulation, behind the terminal 
extremity of the coraco-radialis; then under the internal flexor of the meta- 
carpus, its satellite muscle. Arriving at the inferior extremity of the radius, 
it divides into two terminal branches; which are, the common trunk of the 
interosseous metacarpal arteries and the collateral artery of the cannon. 

The following are the principal collateral branches furnished by the 
posterior radial artery : 

1. At the superior extremity of the radius, articular ramuscules which 
anastomose with analogous branches from the epicondyloid artery. 

2. A little lower, large divisions destined for the muscles of the posterior 
antibrachial region, some of them arising from the next artery. 

8. The interosseous artery of the fore-arm, a considerable vessel which 
originates at the same point as the preceding—the radio-ulnar arch, and 
which crosses this from within to without, after traversing the posterior face 
of the radius, beneath the perforans muscle, to descend along the lateral 
extensor muscle of the phalanges, in the channel formed outwardly by the 
union of the two bones of the fore-arm. This interosseous artery furnishes, 
immediately after its exit from the radio-ulnar arch, several branches to the 
articulation of the elbow and the antibrachial muscles. At its terminal 
extremity it usually-divides into a number of branches, the majority of 
which join the branches sent to the carpus by the anterior radial artery. It 
is rare that it does show some fine anastomoses with one of the divisions of 
the latter artery in front of, or outside the articulation of the elbow ; some- 
times it directly joins that vessel; and I have seen it, on the contrary, receive 
the anterior radial artery, which it in part supplanted. ; 

4. Several muscular and musculo-cutaneous ramuscules without any fixed 
arrangement, arising from different points of the course of the parent artery, 
below the preceding divisions. ~ ae 

5. A deep branch, also liable to very numerous variations, having its 
origin at the radial insertion of the perforatus muscle, descending on the 
posterior face of the radius, chiefly destined to the carpus, and remarkable 
for the anastomoses that its internal divisions contract with the anterior 
radial artery, and for those which occasionally unite its external ramifications 
to the ultimate branches of the interosseous artery of the fore-arm or the 


epicondyloid artery (Fig. 288, 2). 


568 


ARTERIES OF THE 
FORE-FOOT, SEEN 
FROM BEHIND, 


THE ARTERIES. 


1. First Terminal Branch of the Posterior Radial Artery, 
or Common Trunk of the Interosseous Metacarpal 
Arteries (Fig. 283, 5.) 


This arterial branch separates at a very acute angle 
from the collateral artery of the cannon. It descends 
inside and behind the carpus, accompanied by the prin- 
cipal subcutaneous vein of the limb, and with it is 
included underneath a superficial fascia, which maintains 
them in a channel hollowed on the external face of the 
carpal fibrous sheath. It thus arrives within the head of 
the inner metacarpal bone, where it is inflected to the 
outer side by crossing the superior extremity of the sus- 
pensory ligament, and between it and the metacarpal liga- 
ment the latter furnishes to the perforans tendon ; it anas- 
tomoses by inosculation with a descending branch which 
emanates from the superficial arch that, above the carpus, 
unites the epicondyloid or ulnar artery to the origin 
of the collateral artery of the cannon (Fig. 283, 6). The 
loop-like anastomosis thus formed by the radio-palmar 
artery, exactly corresponds to the deep palmar arch of 
pentadactylous animals, particularly to that of Man. We 
propose to name it also the subcarpal arch, by reason of 
the position it occupies in regard to the carpus, reser- 
ving the appellation of supracarpal arch for the super- 

cial palmar arch, which is represented by the anastomosis 
established between the collateral artery of the cannon 
and the epicondyloid artery. 

Four principal branches emanate from this subcarpal 
arch: these are the metacarpal interosseous arteries, dis- 
tinguished into posterior or palmar, and anterior or dorsal. 

a. The posterior interosseous arise, one on the right, 
the other on the left, at the head of the lateral meta- 
carpal bones, each descending on its own side, and in a 
flexuous manner, along these rudimentary bones, in the 
angular groove formed by their inner face and the pos- 
terior face of the principal metacarpal bone, terminating 


The muscles and tendons have been removed, only a small portion of 
the perforans tendon being left; the os pedis has been chiselled 
away on its plantar face to expose the semilunar anastomosis. 

1, Posterior radial artery; 2, Innominate carpal branch; 3, Supra- 
carpal arch; 4, Epicondyloid (ulnar) artery; 5, Radio-palmar 
artery, or common trunk of the interosseous metacarpal arteries ; 
6, Subcarpal arch; 7, 7, Posterior interosseous metacarpal arteries 
7’, 7', Anterior interosseous metacarpal arteries; 8, 8, Their origin; 
9, Collateral artery of the cannon; 10, Its communicating branch 
with the interosseous arteries; 11, 11, Digital arteries, 12, Semi- 
lunar anastomosis in the os pedis; 13, Emergent branches of this 
anastomosis; 14, Plantar ungueal artery, forming this anastomotic 


arch; 15, Origin of the preplantar ungueal artery; 16, Origin of the plantar-cushion 
artery; .17, Origin of the anterior branch of the coronary circle; 18, Posterior branch of 


the same. 


1 This vessel corresponds to the radio-palmar artery of Man, by which name it is 
sometimes designated. Rigot has improperly named it the deep plantar artery. 


THE BRACHIAL OR AXILLARY ARTERIES. 569 


at the inferior extremity of the lateral bones by anastomosing in full 
canal with a branch of the collateral of the cannon. They furnish some 
ramifications to the suspensory ligament which covers them, and several 
tendinous and cellulo-cutaneous twigs ; one supplies the medullary artery 
of the principal cannon bone (Fig. 283, 7). 

b. The anterior interosseous arteries arise from nearly the same point as 
the preceding, one outwards, the other inwards, turning back round the head 
of the lateral metacarpals to place themselves in the groove which separates 
these from the principal metacarpal bone, on their external or dorsal face, 
after having thrown off several anastomosing ramuscules which communicate 
between the two arteries in front of the upper extremity of the median meta- 
carpal bone, or with the terminal branches of the anterior radial and the 
interosseous arteries of the fore-arm. By their terminal extremity, these two 
arteries anastomose with a branch of the collateral of the cannon—that 
which receives the posterior interosseous arteries (Fig. 282, 7’, 8). 

The dorsal interosseous arteries, although much finer than the palmar (in 
Solipeds these arteries are quite rudimentary), nevertheless furnish collateral 
divisions destined for the anterior tendons of the metacarpus, the periosteum, 
the connective tissue, and the skin. They often communicate with the 
posterior arteries by deep branches, which cross the intermetacarpal 
ligaments. 

Variations.—The existence of the interosseous metacarpal arteries, their 
position, and their anastomoses with the inferior extremity of the collateral 
of the cannon, are constant; though this is not the case with regard to their 
origin, or the source from which they arise. In the typical description we 
have given, we have considered them all as being furnished by the radio- 
palmar artery; but it is necessary to add that one of the four, the external 
dorsal, often comes directly from the arterial branch that, from the supra- 
carpal arch, descends along the carpus to concur in forming the subcarpal 
arch, by anastomosing with the radio-palmar, or rather with a branch of the 
interosseous of the fore-arm, It is also necessary to add that these meta- 
carpal arteries sometimes arise together from one large branch furnished by 
the collateral of the cannon, at the superior extremity of the metacarpus, 
and which receives the now rudimentary radio-palmar artery, as well as that 
given off by the supracarpal arch; so that we may have two superposed 
supracarpal arches. We have met other anomalies which need not be noticed 
here, as they are without interest. 


2. Second Terminal Branch of the Posterior Radial, or Collateral Artery of the 
Cannon) (Fig. 283, 9.) 


The collateral artery of the cannon continues, in its volume and direction, 
the posterior radial artery. It passes, with the flexor tendons, under the 
carpal arch, and descends on the inner side of these tendons, accompanied 
by the internal plantar nerve, to above the fetlock and near the great 
sesamoid bones, where it bifurcates into the digital arteries. 

Collateral branches.— We observe : 

1. Near the origin of the artery, and very often from the posterior radial 
artery itself, a branch which anastomoses above the pisiform bone with the 
epicondyloid artery, forming an arch whose convexity is inferior (Fig. 283, 3), 
and which has been already noticed as the supracarpal or superficial palmar 

1 This artery, the superficial plantar of Rigot, represents one of the metacarpal 
palmar branches furnished by the superficial palmar arch in Man and other pentadactylous 
animals. 


570 THE ARTERIES. 


arch, in contradistinction to the subcarpal or deep palmar arch, the source 
of the interosseous arteries of the metacarpus. This ramification furnishes 
one or more muscular twigs that usually anastomose with the other branches 
of the posterior radial artery ; and an inferior division,’ which descends in 
the carpal arch, within the pisiform bone, to the superior extremity of the 
metacarpus, where it inosculates with the radio-palmar artery, after detach- 
ing several carpal ramuscules, the principal of which turns round the inferior 
border of the pisiform bone. 

9. On its course, numerous and fine synovial tendinous and cutaneous 
divisions. : ; 

3. A trunk springing from the terminal extremity of the vessel, between 
the two digital arteries, sometimes even from one of these, which is placed 
at the posterior face of the principal metacarpal bone, within the two 
branches of the suspensory ligament, and, passing upwards, soon divides into 
two branches; these anastomose by inosculation with the posterior inter- 
osseous arteries of the metacarpus, after giving off on each side two other 
ramuscules which wind round the borders of the middle metacarpal bone, 
receiving the dorsal interosseous arteries, and ramify in front of the fetlock, 
on the anterior face of the cannon bone, and in the texture of the capsular 
ligament of the metacarpo-phalangeal articulation (Fig. 283, 10). 

Terminal branches.—These are, as we said, the digital arteries, whose dis- 
position almost éxactly repeats that of these vessels in the posterior limb, 
and which have been described at page 551. . 


DIFFERENTIAL CHARACTERS IN THE AXILLARY ARTERIES OF OTHER THAN SOLIPED ANIMALS, 


1. Axillary Arteries of Ruminants. 


These vessels comport themselves in their origin, course, and relations, as in Solipeds. 

The special characters they present in their distribution are as follows: 

1. Dorsal artery.—This arises from a trunk common to it and the vertebral artery, 
and usually leaves the thorax by passing above the first costo-vertebral articulation. Its 
subcostal branch proceeds directly from the above-named trunk. 

2. Superior cervical artery—This is absent, and is replaced by a branch of the dorsal 
artery, but particularly by the superior muscular divisions of the vertebral artery. 

3. Vertebral artery.—Extremely voluminous, and terminates in the muscles of the 
neck, after passing through the foramen of the axis; it is remarkable for the considerable 
size of its spinal branches. 

4. Inferior cervical, internal and external thoracic arteries—These do. not present 
anything worthy of special consideration, except that the last is very voluminous in the 
Ox and very slender in the Sheep, and supplies the satellite arterial branch of the 
cephalic vein, which, in Solipeds, arises from the inferior cervical artery. 

5. Superscapular artery—This vessel appears to us to be absent in the Sheep, and 
its place supplied by the divisions of the inferior cervical artery. 

6. Subscapular artery.—The scapulo-humeral branch gives oft the majority of the 
branches destined to the posterior brachial muscles. 

7. Humeral artery—The muscular arteries are of small size, particularly the deep 
humeral, which is largely replaced by the scapulo-humeral branch. 

8. Anterior radial artery—This comports itself similarly to that of the Horse, and 
is liable to as frequent anomalies. 

9. Posterior radial artery—This artery follows the same course as in Solipeds ; only 
instead of furnishing the radio-palmar artery near the carpus, at the point where it 
becomes the collateral artery of the cannon, it gives off that vessel much higher, and near 
the upper third or middle of the fore-arm. Its interosseous branch, lodged in the deep 
channel on the outside of the bones of this region, where the radius and ulna join. is 
separated into two branches near the inferior extremity of that groove. The anterior of 
these ramifies on the dorsal face of the carpus, and anastomoses with the divisions of the 


? Analogous to the radio-ulnar artery of Man, 


THE BRACHIAL OR AXILLARY ARTERIES, 571 


anterior radial artery; the posterior traverses the inferior radio-ulnar arch, to distribute 
the majority of its branches behind the carpal articulations, 

10. Radio-palmar artery —Arising, as we have already seen, from the posterior 
radial artery, towards the upper third of the fore-arm, this branch descends tc the 
superior extremity of the metucarpus in following, as in the Horse, a superficial course 
and ends in four metacarpal interosseous arteries’ three posterior or palmar, and ore 
anterior or dorsal, ‘Yhe posterior interosseous arteries are very irregular and inconstant 
in their disposition; they communicate with eich other by severat branches, and 
anastomose, inferiorly, either with the iateral digital arteries, the collateral of the cannon 
or, as is most commonly the case, with a branch of the latter vessel. ‘hese interosscous 
arteries are distinguished inte external, middle, and internal; the first two are comprised 
between the posterior face of the metacarpus and the suspensory ligament; the third 
placed at the inner border of that ligament, is more considerable than the others, and by 
its volume and direction represents the continuation of the radio-palmar artery. The 
anterior interosseous artery passes through the foramen at the superior extremity of the 
metacarpus, and arriviug «t the dorsal face of the bone, it bifurcutes, its ascending 
branch reaching the capsular ligament of the carpal articulations, where it anastomoses 
with the divisions of the anterior radial and interosseous arteries of the fore-arm; the 
descending is lodged in the anterior groove of the metacarpal bone, and joins a perforating 
branch of the collateral artery of the cannon—a branch which crosses the foramen 
pierced towards the inferior extremity of the bony diaphysis. If it is desired to ascertain 
the signification uf these interosseous arteries in their relation to the elements composing 
the foot of Rumiuunts, we readily recognise: in the posterior median artery, the 
interosseous palmar of the two great digits; in the posterior lateral arteries, the 
interossevus palmar, intermediates to these middle digits, and the rudimentary lateral 
digits represented by the ergots or dew claws; and in the single anterior artery, the dorsal 
interosseous of the two great digits. Wemay even prove, by a more minute examination, 
the existence of dorsal interosseous arteries corresponding to the lateial palmar inter- 
osseous vessels. 

11. Collateral artery of the cannon.—This artery follows the same track as in the 
Horse, as far as the lower third or fourth of the metacarpus. Arrived at this point, it 
abandons, as in the Horse, a branch whose divisions communicate with the interosseous 
arteries, and are continued by the digital arteries, three in number: a middle and tuo 
lateral (Fig. 349). 

a. The communicating branch with the metacarpal interosseous arteries very often 
arises from the internal digital artery. : 

It is insinuated between tle divisions of the suspensory ligament, and ascends on the 
posterior face of the metacarpus, breaking up into a number of branches which neuriy 
all join the precited arteries, or even the lateral digital, in affecting a variable and 
complicated disposition which it is needless to notice here. One of these branches—a 
true perforating artery, traverses the inferior extremity of the cannon bone, and ascends 
in its anterior groove to join the anterior interosseous artery, after detaching ramuscules 
to the metacarpo-phalangeal articulation. 

b. The middle digital artery represents, by its dimensions, the continuation of the 
collateral artery of the cannon, and is a very voluminous vessel, It is at first inflected 
backwards and outwards to be placed on the posterior face of the perforatus tendon; then 
it descends into the interdigital space by passing behind the great seramoid sheath, 
beneath the ligament uniting the two claws. Reaching the inferior extremity of the 
first phalanx, it divides into two ungueal arteries, one for euch digit, which are inflected 
forwards, pass beneath the internal ligament common to the two interphalangeal articu- 
lations, and enter by the foramen pierced at the inner side of tle pyramidal eminence 
into the internal sinus of the third phalanx, where cach ramifies in the same mauner 
as the plantar ungueal arteries of the Horse. 

Several collateral branches, remarkable for the richness of their arborisations. escape 
from this median artery of the digits and its terminal divisions. The most important of 
these are: 1, At the middle of the first phalanx. two short transverse branches—a riglit 
and left, passing beneath the flexor tendons and going from the median digital artery 
to the lateral arteries of the digits; 2, Nearly at the same point, a single artery which 
traverses the interdigital space from behind to before. to pass between the two tendons 
of the common extensor of the phalanges, whence it ramifies on the anterior fare of 
the digits by ascending along the anterior median vein, and anastomosing with a 
descending branch of the perforating artery which crosses the inferior extremity of the 
metacarpus; 3, A double branch analogous to the artery of the plantar cushion of the 
Horse. having its origin at the terminal extremity of the digital artery, often arising from 
the ungueal artery, either on one side or both, and communicating, by a transverse branch, 


572 THE ARTERIES. 


with its homologue; it is directed backward and downward on the bulb of the heel, 
where it forms an anastomotic arch with the lateral digital artery ; from the convexity 
of this arch, which is turned downwards, there escape a large number of reticulating 
ramuscules, destined for the keratogenous membrane and the plantar cushion. 

e. The lateral digital arteries are distinguished into internal and external. The first 
has its origin at the bend formed by the collateral of the cannon, when that vessel is 
inflected on the posterior face of the perfuratus tendon to become the median digital 
artery, most frequently in common with the branch whose divisions join the metacarpal 
interosseous arteries. The second commences a little further off, after having received a 
branch from either this communicating artery, or from the external interosseous palmar ; 
it is not rare to see it entirely formed by one of these bianches, or by the two together, 
Whatever may be their point of origin, the lateral digital arteries descend on the ex- 
centric side of the digits, without the flexor tendons, and terminate in anastomosing 
by inosculation with the artery of the plantar cushion, Among the collateral branches 
emanating from these arteries, there ought to be distinguished that which goes to the 
ergot, and the transverse branch thrown across between each, as well as tue mediau 
digital artery.’ 

2. Axillary Arteries of the Pig. 


Both spring separately from the arch of the aorta; consequently, there is no anterior 
aorta, The right artery, or brachio-cephalic trunk, first arises; the left comes immediately 
after. 

a. The brachto-cephalic trunk is directed forwards, under the inferior face of the trachea, 
and leaves the thorax to reach the inner face of the anterior limb, as in other animals, 

It furnishes successively :-— 

1. At the first rib, and below, the two carotid arteries, rising singly from nearly the 
same point. 

2. Directly opposite to these vessels, a trunk remarkable for the complication 
attending its mode of distribution; it is directed upwards and backwards, on the side 
of the trachea and longus colli, crosses the interval between the second and third ribs, 
and elevates itself into the deep cervical muscles, to terminate in the vicinity of the nape 
of the neck. It evidently represents the deep or superior cervical artery. Near its origin 
it gives off the vertebral artery, whose mode of termination is exactly the same as in the 
Horse. Beyond this, it detaches the dorsal artery, which ascends into the muscles of 
the withers, after passing into the first intercostal space. Lastly, it supplies, before 
leaving the thorax, the subcostal or superior intercostal artery, placed across the superior 
extremities of the third, fourth, agd fifth ribs. 

3. Always within, but a little more forward than the first rib, a voluminous inferior 
cervical artery, divided into several ascending bianches; and the two thoracic arteries, 
which offer nothing particular for description. 

4, Without the thorax, on the internal face of the scapulo-humeral articulation, the 
humeral or subscapular arteries ; the first, less voluminous than the other, presents, from 
its origin to the distribution of its branches in the fovt, a disposition essentially 
resembling that observed in this vessel in Ruminants; the second courses upwards in 
the space between the subscapular muscle and the teres major, and soon divides into 
two terminal branches, one of which continues the primitive track of the vessel, while 
the other passes beneath the subscapular muscle to carry its ramifications into the 
antero-external muscles of the shoulder, furnishing in its course: 1, The great dorsal 
artery, throwing a part of its ramifications into the olecranian muscles: 2, A volu- 
minous branch which provides the greater number of the divisions given off, in the 
Horse, by the deep humeral and prehumeral arteries; 3, Two articular branches, one 
of which closely represents the superscapular artery. 

b. The left brachial trunk only differs from the right in the disposition of the 
superior cervical, dorsal, and vertebral arteries, which have distinct origins; the two 
last are very close to each other, and the first furnishes the subcostul branch. 


3. Axillary Arteries of Carnivora, 


These arise separately from the convexity of the arch of the aorta, as in the Pig, and 
ie oe successively, apart from the carotids, special branches of the brachio-cephalic 
runk :— 


1, A voluminous trunk, the common origin of the dorsal, superior cervical, and sub- 


* In several instances, we have seen the lateral digital arteries stop at this transverse 
anastomosis, which then received them entirely. 


THE BRACHIAL OR AXILLARY ARTERIES. 573 


costal or superior intercostal arteries the first passes between the two anterior ribs ; tho 

second in front of the first; the third across the internal face of the first, second, and 

are ‘i near their cartilages, where it emits ascending and descending intercostal 
ranches. 

2. The vertebral artery, anastomosing, as in Solipeds, with a retrograde branch from 
the occipital artery; it supplements, in very great part, the superior cervical, whose 
volume is diminutive, and which is only distributed to the posterior part of the neck, 

3. The inferior cervical artery, giving off the pectoral branches. 

4. The internal thoracic artery, remarkable for its large volume, and for a superficial 
division chiefly destined to the mamme, which joins an anulogous branch from the 
external pudic artery. 

5. An external thoracic branch, whose origin more resembles that of the super- 
scapular artery, which appears to be absent. 

6. The subscapular artery. After furnishing this vessel, the brachial trunk is pro- 
longed by the humeral artery, which we will now examine in detail. 

Homerat Arrery.—Placed at first immediately beltind the coraco-radial or biceps 
muscle, this vessel descends beneath the round pronator, and divides at the superior 
extremity of the radius into two terminal branches; these are the ulnar and radial 
arteries. 

It detaches on its course collateral branches, analogous to those which have been 
described for Solipeds, and among which is a thin vessel, a vestige of the anterior radial 
artery, that passes beneath the terminal extremity of the biceps to supply the muscles 
covering, anteriorly, the articulation of the elbow. 

Ulnar artery—Much smaller than the radial, this vessel transmits, near its origin, 
the interosseous artery, which sometimes proceeds directly from the humeral artery, and 
whose calibre always exceeds, in animals, that of the ulnar artery. The latter is directed 
obliquely outwards and downwards, passing under the perforans, and gains the internal 
face of the anterior ulnar or oblique flexor of the metacarpus, where it lies beside the 
ulnar nerve, to descend with it inside the unciform bone, and join the posterior interosseous 
artery, or one of its terminal branches. On its track it gives off a number of muscular 
or cutaneous branches, several of which anastomose with the internal collateral artery 
of the elbow, as well as with divisions of the radial artery. 

Interosseous artery.—This artery is placed between the cubitus and radius, under- 
neath the square pronator, and is prolonged to the lower third of the fore-arm, where it 
separates into two branches—the anterior and posterior interosseous arteries, after 
abandoning on its way several branches, mostly anterior, which enter the antibrachial 
muscles by traversing the space comprised between the two bones of the fore-arm, the 
principal escaping by the radio-ulnar arch. j 

The anterior interosseous artery, after passing between the radius and ulna, descends 
on the anterior face of the carpus, where its divisions meet, inwardly, the collateral 
ramuscules of the radio-palmar artery, and outwardly, the arborisations of a branch from 
the posterior interosseous artery, forming with these vessels a wide-meshed plexus, 
from which definitively proceed several filaments that join the dorsal iuterosseous 
metacarpal arteries. : sere 

The posterior interosseous artery may be regarded, by its volume and direction, as the 
continuation of the interosseous trunk. After emerging from beneath the square pronator, 
it detaches an internal flexuous branch anastomosing with the radio-palmar artery, then 
several external musculo-cutaneous branches; after which. it is placed within the 
pisiform bone, where it divides into two branches, after receiving the ulnar artery. The 
smallest of these branches anastomoses by inosculation with the superficial palmar arch; 
the other, larger and deeper-seated, is carried in front of the flexor tendons, beneath the 
aponeurosis covering the interosseous muscles, across the superior extremity of these, and 
so forming the deep palmar arch, which unites with a thin filament from the radio-palmar 
artery. This arch supplies, with some ramuscules destined to the muscles of the hand 
(or paw), eight interosseous metacarpal arteries: four posterior or palmar, which are united 
by their inferior extremity with the collaterals of the digits, after giving several divisions 
to the muscles of the hand; and four anterior or dorsal, traversing the superior extremity 
of the intermetacarpal spaces, like the perforating arteries in Man, joining the anterior 
interosseous branches of the fore-arm, and descending afterwards into the intermetacarpal 
spaces, to unite with the collateral arteries of the digits at the metacarpo-phalangeal 

iculations. : Z 
ao artery: the posterfor radial of the other animals. Lying alongside the 
long flexor of the thumb and the perforans muscle, this artery follows the inner face of 
the perforatus muscle, and curving outwards to be united to a branch from the posterior 
antibrachial interosseous artery, forms the superficial palmar arcade, from which escape 


ARTERIES OF THE HUMAN 


FORE-ARM. 

1, Lower part of biceps; 2, 
Inner condyle of humerus ; 
3, Deep portion of pronator 
radii teres; 4, Supinator 
longus; 5, Flexor longus 
pollicis; 6, Pronator quad- 
ratus; 7, Flexor profundus 
digitormn; 8, Flexor carpi 
ulnaris; 9, Annular liga- 
ment; 10, Brachial artery ; 
11, Anastomotica longus 
magna, inosculating above 
with the inferior profunda, 
and below with the anterior 
ulnar recurrent ; 12, Radial 
artery ; 15, Radial recurrent 
inosculating with the supe- 
rior profunda; 14, Super- 
ficialis vole; 15, Ulnar ar- 
tery ; 16, Superficial palmar 
arch, giving off digital 
branches to three fingers 
and a half; 17, Magna 


THE ARTERIES, 


four branches—the palmar or collateral of the digits. 
These are at first situated between the perforatus and 
perforans tendons, and reach the superior extremity of 
the interdigital spaces, where they receive the metacarpal 
interosseous arteries, and comport themselves in the fol- 
lowing manner: the internal goes to the thumb; the 
second—counting from within outwards—gains the con- 
centric side of the index; the third, the largest, divides 
into two branches which lie alongside the great digits; 
the last goes to the external digit. 


COMPARISON OF THE AXILLARY ARTERIES IN MAN WITH 
THOSE OF ANIMALS. 


The arteries of the thoracic limbs and head arise sepa- 
rately from the arch of the aorta; consequently, in Man 
there is no anterior aorta. 

The vessel of the limb that represents the axillary of 
animals is here resolved into two portions: the subclavian 
artery and axillary artery. 

The sUBCLAVIAN ARTERY has not the same origin on 
both sides; on the right it arises from the aorta by a trunk 
common to it and the carotid of that side—the brachio- 
cephalic trunk (arteria innominata); while the left is 
detached separately from the most distant part of the 
aortic arch. The subclavian vessels extend to the in- 
ferior border of the clavicles, and furnish seven important 
collateral branches, which are present in the domesticated 
animals. They are :— 

1. The vertebral artery, situated in the vertebral fora- 
mina of the cervical vertebre, as far as the axis; there it 
anastomoses, as in Solipeds, with a branch of the carotid, 
enters the spinal canal by the foramen magnum, and 
unites with its fellow at the lower border of the pons 
Varolii to form the basilar artery which, in the Horse, 
comes from the cerebro-spinal artery of the occipital. 

2. The infer‘or thyroid, whose origin and some branches 
we find in the ascending branch (ascending cervical) of 
the inferior cervical artery in the Horse. 

3. The internal mammary artery divides into two 
branches at the xiphoid appendix of the sternum. 

4. The superior intercostal artery, whose analogue we 
see in Solipeds, in the subcostal branch of the dorsal. 

5. The superscapular artery, present in all animals 
and disposed in tiie same manner. 

6. The transverse cervical (transverea collz), represented 
by the extra-thoracic branches of the dorsal artery. 

7. The deep cervical (cervicalis profunda) corresponds 
to the superior cervical in the Horse. 

The AXILLARY ARTERY, or extra-thoracic portion of the 
subclavian trunk, extends to the external border of the 
pectoral muscle, where it is continued by the humeral 
artery. The axillary gives off: the thoracica acromialis, 
resembling the descending branch of the inferior cervical 
artery of large quadrupeds; the external mammary , sub- 
scapular ; and posterior and anterior circumflex, branches 
of the preceding in Solipeds. ij 

Homerat (Bracuat) Arrery.—This artery extends’ 
from the external border of the pectoral muscle to the 
bend of the elbow: here it divides into two terminal 
branches—the ulnar and radial, 

In its course it gives off several muscular branches, 


pollicis and radialis indicis ; 18, Posterior ulnar recurrent; 19, Anterior interosseous; 


20, Posterior interosseous. 


a a 


THE BRACHIAL OR AXILLARY ARTERLES, 575 


and an external and internal collateral of the elbow (collateralis ulnaris superior and 
inferior). In the lower third of the arm, the brachial artery is comprised between 
tue brachialis anticus and inner border of the biceps; so that, during flexion, and 
especially active and forced flexion, of the fore-arm on the arm, in vigorous subjects, the 
circulation is arrested in the vessels of the hand. 

The radial artery of Man is represented in the Horse by the posterior radial artery. 
It is directed downward and a little inward, supposing the hand to be in a state of 
pronation ; it crosses the carpus in front of the trapezium and scaphoides, at the bottom 
of the anatomical snutfbox, and beneath the flexor tendons of the phalanges forms the 
deep palmar arch, finally anastomosing with a branch of the ulnar at the hypothenar 
eminence. Along its course it furnishes muscular branches: the carpea anterior; radio- 
palmar, which passes outwards, and unites with a branch of the ulnar artery to form the 
superficial palmur artery ; the dorsalis pollicis; the carpea posterior, which concurs in 
the so ra of the dorsal arch of the carpus that gives origin to the dorsal interosseous 
branches, 

The ulnar artery, formed, in Solipeds, by the anterior radial, passes downward and 
outward; itis at first covered by the great pronator muscles, great and small palmar, 
and superficial flexor; lower, it is only protected by the antibrachial aponeurosis and 
the skin. On the anterior face of the carpus, it passes within the pisiform bone, and 
anastomoses with the radio-palmar artery, whence results the superficial palmar arch. 
It gives rise to two recurrent arteries that ascend to receive the collateral vessels of the 
elbow, then to a trunk seen in animals, and which divides into the anterior and posterior 
interossex. 

The three arches that exist in the vicinity of the carpus, the constitution of which 
has been already given, are distributed in the following manner 

The superficial palmar arch is situated at the surface of the flexor tendons; from its 
convexity it emits four or five metacarpal branches: the first reaches the external 
border of the little finger as the eaternal collateral of that organ the other four 
are lodged in the interosseous spaces, and when they reach the roots of the fingers 
they bifurcate and constitute the external or internal collateral arteries of the five fingers. 
The deep palmar arch furnishes: articular branches to the wrist, the perforating branches 
which cross the interosseous spaces to unite with the dorsal interossee; the palmar 
interossex, which join the superficial interosses before their division into collateral 
branches. Lastly, the carpal dorsal arch gives off tle dorsal interossex, which receive 
perforating filaments above and below the metacarpus, and are expended in the 
articulations and skin of the fingers. 


Arricne VII.—Prmirtve (or Common) Carotrp ARTERIES. 
(Figs. 282, 14; 286, 1.) 


Origin.— These two vessels (named from «dpa, the head) arise from the 
right axillary artery, at a short distance from its origin, by a common 
trunk, the cephalic, which is detached at a very acute angle, and is directed 
forward beneath the inferior face of the trachea, and above the anterior vena 
cava, to terminate near the entrance to the chest by a bifurcation that 
commences the two common carotids. 

Course-—Each of these arteries afterwards ascends in the midst of an 
abundant, though dense, connective tissue, along the trachea, at first beneath 
that tube, then at its side, and finally a little behind its lateral plane. 
Each carotid arrives in this way at the larynx and guttural pouch, where it 
divides into three branches. : 

Relations.—In its course, this vessel, independently of the connection 
between it and the trachea, affects the following relations :— 

Throughout its entire length, it is accompanied by the cord that results 
from the union of the pneumogastric nerve with the cervical portion of the 
sympathetic, and by the recurrent nerve ; the latter is placed below or in 
front of the vessel, from which it is somewhat distant in the lower part of 
the neck; the first is situated above or behind the artery, and lies close to 
it. 

It also corresponds: behind, in its upper two thirds, to the longus colli 


576 THE ARTERIES. 


and the rectus anticus major; outwardly, to the scalenus, towards the 
inferior extremity of the neck, and to the subscapulo-hyoideus, which 
separates the artery and jugular vein in the middle and superior part. But 
near the entrance to the chest, these two vessels are in direct relationship, 
the vein below and the artery above. 

It is also to be noted, that the glands at the entrance of the chest are in 
contact with the carotids, and that the left artery corresponds, besides, to 
the cesophagus. 

CoLLaTERAL BrancHEs.—The branches furnished by the common carotid 
on its course are somewhat numerous, but they are of such inconsiderable 
diameter that their successive emission does not sensibly vary the calibre 
of the vessel from which they emanate; so that the carotids represent, from 
their origin to their termination, two somewhat regular cylindrical tubes. 
These collateral branches are destined either to the muscles of the cervical 
region, or to the cesophagus and trachea. Two of them, the ¢hyro-laryngeal 
and accessory thyroid arteries, will occupy us in a special manner, 

Tuyro-LarynenaL Artery (Fig, 282, 14").—This vessel, which corre- 
sponds exactly to the superior thyroid artery of Man,’ arises from the 
common carotid at a short distance from its termination, a little behind the 
larynx or above the thyroid body; it passes on that organ, into which it 
enters by two principal branches that turn round its superior extremity and 
anterior border, after sending two branches to the larynx—a superior, des- 
tined also to the pharyngeal walls; and an inferior, much more considerable, 
which is exclusively distributed to the laryngeal apparatus. 

It sometimes happens that the thyro-laryngeal artery is found divided 
from its origin into two quite distinct branches, each furnishing a laryngeal 
and a thyroid division, as in figure 286, 3.” 

We have already remarked the disproportion that exists between the 
considerable calibre of the branches sent by this artery to the thyroid body, 
and the slender volume of that organ; so that it will at present suffice to 
remind the student of this peculiarity. 

Accessory Turroip Artery (Figs. 282 14’; 286, 2)—The origin of 
this vessel precedes that of the first; it is much smaller, and enters the 
thyroid body by the posterior or inferior extremity of this glandiform 
lobe. 

This artery often sends only some excessively fine ramuscules to the 
thyroid gland, and expends itself almost entirely in the cervical 
muscles.? ‘ 

Terminal Branones.—The three branches which terminate the common 
carotid are the occipital, and internal and external carotid arteries; the latter 
is incomparably larger than the other two, which only appear to be collateral 
twigs from the principal vessel. It is these branches which distribute the 
blood to the various parts of the head. We will devote three special 
paragraphs to their study; but their preparation will previously demand 
some notice. 


' We would have given it the same name if we could have found the true repre- 
sentative of the inferior thyroid artery. 

* It was doubtless a case of this kind that Rigot had before him when he described 
the above vessel, and made two arteries of it—the thyroid and laryngeal. But, we 
repeat, this example is only exceptionally met with, and does not authorize its being 
supposed to be the rule, and cause the creation of a distinct thyroid and laryngeal artery; 
since pe branch of the vessel is distributed to the larynx and thyroid body at the 
same time. 


* We regard it as the analogue of the middle thyroid of Man, 


THE COMMON CAROTID ARTERIES. 577 


Preparation of the arteries of the head.—After carefully removing the skin, dissect the 
superficial arteries of one side—that is, the external maxillary, maxillo-muscular, the 
temporal trunk, and the posterior auricular arteries, excising the parotid to expose the 
origin of the three last-named vessels. On the opposite side, the deep arteries are 
prepared, after disposing of the branch of the maxilla, as in the preparation of the 
muscles of the tongue; the orbital and zygomatic processes being removed in three 
sections with the saw, as in figure 286, which will serve as a guide in the dissection of 
all these arteries. 


OocIPITAL ARTERY. (Fig. 286, 6.) 


The occipital artery is a slightly flexuous vessel, lying beside the upper 
third of the internal carotid. It ascends beneath the transverse process 
of the atlas in passing behind the guttural pouch, between the maxillary 
gland and the straight anterior muscles of the head. It then insinuates 
itself between the small lateral straight muscle and the inferior arch of the 
above vertebra, to pass through its anterior foramen, and terminate by two 
branches, after coursing along the short fissure which unites this foramen 
with the superior. In its track, this artery is crossed, outwardly, by the 
pneumogastric and spinal nerves, and the occipital nerve of the great sym- 
pathetic, and is accompanied by the divisions of the inferior branch of the 
first pair of cervical nerves. 

The two terminal branches of the vessel are the occipito-muscular and 
cerebro-spinal arteries. 

The collateral branches are three in number, and in the order of their 
emission are named: 1, The prevertebral artery; 2, The mastoid artery; 3, 
The atloido-muscular artery. 

CottateraL BrancuEs—l, PrevertesraL Artery (Fig. 286, 9)—The 
smallest of all the branches emanating from the occipital, this artery is 
detached at a very acute angle, and immediately divides into several 
filaments, some muscular, the others meningeal. The majority of the first 
pass between the occipito-atloid articulation and the small anterior rectus 
muscle of the head, and expend themselves either in that muscle, or the 
great rectus; the second, generally two in number, are always very slender, 
and reach the dura mater by entering, one through the posterior foramen 
lacerum, the other by the condyloid foramen. 

2. Masrom Arrury (Fig. 286, 8).— This vessel arises at an acute 
angle above the preceding, and goes towards the mastoid foramen by 
creeping on the external surface of the styloid process of the occipital bone, 
beneath the small oblique muscle of the head. It enters the parieto- 
temporal canal by this foramen, to anastomose by inosculation with the 
spheno-spinous artery. 

In its course it describes a curve downwards, and throws off a large 
number of collateral branches. Among these are some which originate 
before the artery enters its bony canal, and which are destined for the 
muscles of the nape of the neck. Others arise in the interior of this canal, 
and escape from it by the orifices that cribble the temporal fossa, to expend 
themselves in the temporal muscle. Some ramuscules reach the dura mater. 

We have scen the mastoid artery arise directly from the common 
carotid, and furnish a parotideal branch. 

3. ATLOIDO-MUSCULAR oR Retrograde Artery (Fig. 286, 7).—This 
branch is not constant, and when it does exist it presents a variable volume. It 
is detached from the occipital, underneath the transverse process of the atlas, 
by forming with the parent branch a right, or even an obtuse angle ; it is 
directed backwards, traverses the inferior foramen of the process of the 


578 THE ARTERIES. 


a” 
atlas, places itself beneath the atlo-axoid muscle, and in a flexuous manner 
advances to meet the vertebral artery, which it directly joins, after giving 
off some branches to the great oblique and neighbouring muscles. This 
anastomosis is the means of establishing a collateral communication between 
the vertebral artery, and the divisions furnished by the common carotid ; so 
that these two arteries can mutually assist or supplant each other. 

TurminaL Branones.—1l. Occiprro-muscunar ARTERY (Fig. 286, 10).— 
Covered at its origin by the great oblique muscle, the occipito-mu uur 
artery is directed transversely inwards to the surface of the posterior 
straight (recti) muscles, and soon separates into several branches—ascending 
and descending—mixed with the nervous divisions of the first superior 
cervical branch, all of which are destined to the muscles and integuments of 
the occipital region. The descending branches anastomose with the ter- 
minal divisions of the superior cervical artery. 

2. CeREBRO-sPINAL ArTERY.—This vessel enters the spinal canal by the 
anterior foramen of the atlas, traverses the dura mater, and divides into two 
branches on the inferior face of the spinal cord. Of these two branches, the 
anterior is united, by convergence, with the analogous branch of tl 
opposite artery on its arrival at the middle of the length of the bulb (medulla 
oblongata), and so forms the basilar trunk ; the other passes backwards, and 
constitutes the origin of the median spinal artery, by anastomosing, after a 
short course, with the corresponding branch of the other cerebro-spinal 
artery. There results from this distribution a kind of vascular lozenge, 
situated at the lower face of the medulla oblongata, which receives in its 
middle the two cerebro-spinal arteries. This regular arrangement is not, 
however, always observed ; these arteries may unite at the posterior extremity 
of this lozenge, as is shown in figure 285. 

Basilar trunk.—This is a single vessel which creeps in a somewhat 
flexuous manner on the inferior face of the medulla oblongata, beneath the 
visceral arachnoid membrane, and passing over the annular protuberance 
(pons Varolii), terminates at the anterior border of this portion of the 
encephalic isthmus, by anastomosing with the two posterior cerebral arteries 
(Fig. 285, 11, 11). 

On its course it gives off: 

1. A multitude of plexuous ramuscules, which enter the substance of the 
medulla oblongata and the pons Varolii, or are distributed to the roots of the 
nerves emanating from the medulla oblongata. 

2. The posterior cerebellar arteries, vessels liable to numerous anomalies 
in their origin; they usually arise from the basilar trunk ata right angle, 
behind the posterior border of the pons Varolii, and bend outwards, one to 
the right, the other to the left, by gliding along the surface of the bulb 
(medulla oblongata), whose external border it thus reaches, and is then 
inflected backwards beneath the cerebellar plexus choroides, whence they 
sa their ramifications on the lateral and posterior parts of the cere- 

ellum. 

3. The anterior cerebellar arteries, two or three on each side, only one of 
which is constant. _These vessels are very variable in their disposition, and 
arise from the terminal extremity of the basilar trunk, in front of the pons 
Varolii, and sometimes even from the posterior cerebral arteries. Usually 
united in fasciculi, they are directed outwards and a little backwards in 
turning round the cerebral pedunculi, and plunge into the anterior part of 
the cerebellum. 


4. Two branches anastomosing with the internal carotid artery; these 


THE COMMON CAROTID ARTERIES. 579 


~ 
branches are not constant, and are most frequently met with in the Ass. 
They begin at the basilar trunk, in front of the posterior border of 
the annular protuberance, traverse the dura mater to enter the cavernous 
sinus, anid join the carotid arteries at their second curvature. 

Posterior Cureprat Arrertes.—These terminate the basilar trunk, and 
separate into right and left of it, behind the pisiform tubercle (Fig. 285, 11). 
They first proceed forward, receiving posterior communications, then pass 
6u...ard and upward, to turn round the cerebral peduncles and reach Bichat’s 
fissure. On their course, they furnish a multitude of hair-like twigs that enter 
the substance of the peduncles; but the principal branches they give off are 
flexuous, and directed either towards the great cerebral fissure, where they 
terminate, to the posterior extremity of the hemisphere of the cerebrum, or its 
interior, to the plexus chorides more particularly, or even to the cerebellum. 
The disposition and number of these branches are very variable. 

Mepian Sprinan Anrery.—A very long vessel, lodged in the inferior 
~issure of the spinal cord, and measuring the whole extent of that organ, 
which it follows from before to behind. It is from this artery that are 

given off the branches which cover with their arborisations the medullary 
otissue, or penetrate its substance. This emission, which ought soon to 
exhaust the artery, does not sensibly diminish its diameter, as it receives on 
both sides, during its course, numerous additional filaments. Two series of 
ramuscules, in fact, emanate either from the vertebral, intercostal, lumbar, 
or sacral arteries, and enter the spinal canal by the intervertebral foramina, 
and go to join this artery. Generally, however, they do not pass to the 
spinal cord until they have anastomosed with each other outside the dura 
mater, so as to form on the floor of the vertebral canal two lateral conduits 
placed beside the venous sinus, and united by transverse anastomoses ; this 
disposition is most evident in the cervical region of the Ox (Fig. 288). 


INTERNAL OAROTID ARTERY. (Figs. 285, 8; 286, 5.) 


One of the terminal branches of the common carotid, the internal carotid 
ascends at first to beneath the base of the cranium, outside the anterior 
rectus muscles of the head, and bends forward to reach the lacerated 
foramen. In this primary portion of its course, it is suspended in a par- 
ticular fold of the guttural pouch, margined by the superior cervical 
ganglion, accompanied by the cavernous branch of the sympathetic nerve, 
and crossed in various directions by the nerves which form the guttural 
plexus. On arriving at the middle of the occipito-spheno-temporal hiatus, 
it enters the cavernous sinus, and in the interior of that cavity, where it is 
bathed in venous blood, describes two successive and opposite curvatures ; 
the first looking forwards, occupies the carotid fossa of the sphenoid bone : 
the second, with its convexity posterior, at which the internal carotid 
receives an anastomosing branch from the basilar trunk : which branch is 
voluminous and nearly constant in the Ass; but is rare and, when present, 
very slender in the Horse. After the last inflexion, the two internal carotids 
communicate by a very large transverse branch, which is always flexuous, 
often reticulated, and leave the cavernous sinus In crossing the dura mater, 

in the cranial cavity. = 
‘i erhese arteries are on placed at the sides of the pituitary gland, within 
the superior maxillary nerve, proceed from behind forward, and terminate 
in two branches before reaching the optic nerve. One of these branches 


ge 


580 THE ARTERIES. 


constitutes the posterior communicating artery ; the other soon bifurcates to 
form the middle and anterior cerebral arteries. 


Fig. 285. 


) 
y 


= 


; 
We 


\ 


\\\ \ \ 
\ N\ \ 


ARTERIES OF THE BRAIN. 


B, Medulla oblongata; P, Pons Varolii; L, Mastoid lobule; 0, Olfactory lobule; 
c, Chiasma of the optic nerves ; M, Mamillary, or pisiform tubercle; H, Pituitary 
gland ; three-fourths have been excised,—1, 1, Cerebro-spinal arteries; 2, Median 
spinal artery; 3, Lozenge-shaped anastomosis of the two cerebro-spinal arteries, 
from which result, in front:—4, The basilar trunk (usually the cerebro-spinal 
arteries arrive in the middle of the lozenge); 5, 5, Posterior cerebellar arteries ; 
6, Anterior ditto; 7, Internal carotid artery, with the two curves it makes in 
the cavernous sinus ; 8, Internal carotid on the sides of the pituitary gland; 9, 
Transverse reticulated anastomosis thrown between the two internal carotids 
behind the pituitary gland; 10, Bifurcation of the internal carotid; 11, 11, 
Posterior cerebral arteries anastomosing behind the pisiform tubercle, receiving 
in the middle of this anastomosis the two terminal branches of the basilar trunk ; 


12, Middle cerebral artery; 13, Anterior cerebral artery; 14, Posterior com- 
municating artery. 


THE COMMON CAROTID ARTERIES. 581 


Posterior Communicatina Arrery.—This vessel is inflected backward on 
the side of the pituitary gland, and anastomoses behind it with the 
posterior cerebral artery. 

Mivpie Cxresran Arrery.—This vessel separates itself from the an- 
terior cerebral artery, external to the chiasma of the optic nerves, is lodged 
in the fissure of Sylvius, passing through it in a flexuous manner, and at its 
extremity separates into several branches which ramify on the lateral and 
superior faces of the brain, and anastomose by their terminal divisions with 
the posterior and anterior cerebral arteries. 

Anterior CeresraL Artery.—This enters immediately above the cum- 
missure of the optic nerves, and proceeds inwards to unite, in the middle 
line, with the opposite artery, forming with it a single vessel. This median 
artery (or arteria corporis callosi) enters the longitudinal fissure of the brain 
by bending round the anterior extremity of the corpus callosum, and, after 
a short course, divides into two branches which pass from before to behind, 
one to the right, the other to the left, on the internal face of the. hemispheres, 
a short distance from the corpus callosum, and near the posterior extremity 
of that great commissure. The branches emitted by these arteries, either in 
their track or at their termination, anastomose with those of the posterior and 
middle cerebral arteries, as well as with the lobular branch of the ophthalmic. 

Before uniting ina common trunk, the two anterior cerebral arteries 
receive the meningeal branch of the ophthalmic, the calibre of which often 
even surpasses that of these vessels. 


EXTERNAL CAROTID ARTERY. (Fig. 286, 12.) 


This artery ought to be considered, because of its volume and direction, 
as the continuation of the common carotid. It is directed forward, arrives 
at the posterior border of the great branch of the os hyoides, passes between 
it and the great hyoid muscle, and is inflected so as to form an elbow which 
is turned forward, and afterwards ascends vertically to near the neck of the 
condyle of the inferior maxilla, at the posterior angle of the hyoid branch. 
There it bifurcates to give rise to the superficial temporal and internal 
maxillary arteries. 

In the first part of its course—that is, from its origin to the hyoid 
bone, the external carotid artery responds: inwardly, to the guttural pouch 
and the glosso-pharyngeal and superior laryngeal nerves ; outwardly, to the 
outer belly of the digastric muscle, and the hypoglossal nerve. ; 

In its second portion, it is comprised between the guttural pouch, the 
parotid gland, the great branch of the os hyoides,and the inner side of 
the posterior border of the inferior maxilla. 

The collateral branches this artery furnishes are three principal: the 
glosso-facial, macillo-muscular, and posterior auricular. But it also gives off 
others of less importance, which are distributed to the guttural pouch, the 
guttural glands, and the parotid gland. 


1. External Mazillary, Facial, or Glosso-facial Artery. (Fig. 286, 18.) 


It originates from the external carotid, at the point where that vessel 
passes beneath the great hyoid muscle, and is immediately inflected downwards 
on the side of the pharynx, between the posterior border of the large branch 
of the hyoid bone and the above muscle. It passes in proximity to tho 
anterior extremity of the maxillary gland, crossing Wharton’s duct outwardly, 


40 


582 THE ARTERIES. 


and leaves the deep situation it at first occupied, to become more superficial 
in the submaxillary space, where it rises on the surface of the internal 
pterygoid muscle, and is directed forwards to the maxillary fissure. Turning 
round this fissure, it climbs on the face, in front of the masseter muscle, to 
above the maxillary spine, where it terminates in two small branches. : 

In its long and complicated course, the glosso-facial artery describes 
a semicircle upwards, and is very naturally divided, for the study of 
its relations, into three portions: a deep, an intermaxillary, and a facial. 
The first, or deep portion, accompanied in its superior moiety by the glosso- 
pharyngeal nerve, responds, outwardly, to the internal masseter (internal 
pterygoid) muscle; inwardly, to the guttural pouch, the hyo-pharyngeal 
muscle, hypoglossal nerve, middle tendon of the digastricus, the basio- 
glossus, canal of Wharton, and the subscapulo-hyoideus. The inter- 
maxillary, or middle portion, is bordered by the glosso-facial vein, lies 
against the pterygoideus internus, and is in contact with the submaxillary 
glands. The facial, or terminal part, is lodged, at its commencement, in the 
maxillary fissure, in front of the glosso-facial vein and the parotid duct; it 
ascends with these two vessels along the anterior border of the masseter. 
on the maxillo-labial and buccinator muscles, beneath the subcutaneous and 
zygomatico-labial muscles and the ramifications of the facial nerve, which 
perpendicularly crosses the direction of the artery. 

TerminaL Brancues.—The external maxillary artery terminates in two 
small branches which separate from each other at an obtuse angle, one being 
directed upwards, the other downwards. The ascending branch passes 
to the surface of the elevator muscle of the upper lip, below the lachrymal 
muscle. and anastomoses with the divisions of a palpebral branch emanating 
from the supermaxillo-dental artery (Fig. 286, 19). The descending 
branch goes to the false nostril and the entrance to the nasal cavities, 
by creeping beneath the supernasalis-labialis muscle (Fig. 286, 20). 

CottaTeraL Brancues.—These are five principal branches: 1, ‘The 
pharyngeal ; 2, lingual; 8, sublingual; all of which arise from the first 
portion of the glosso-facial artery; 4, The inferior and superior coronary 
arteries, emanating from the facial portion. Besides these, there are a great 
number of innominate branches of secondary importance, which proceed 
to the neighbouring parts, and principally to the maxillary gland, sub- 
maxillary glands, the masseter muscle, and the muscles and integuments of 
the face. We will content ourselves with merely noting the existence 
of these latter branches. 

1, Paarynenan Artery (Fig. 286, 14).—This arises from the glosso- 
facial, at a variable distance from its origin, and sometimes even in the 
angle formed by that vessel and the external carotid artery. Whatever may 
be its commencement, it is always directed forwards, passes between the hyo- 
pharyngeus muscle and the great branch of the hyoid bone, and describing 
some flexuosities, goes towards the pterygoid process, beneath the elastic 
layer which covers the pterygd-pharyngeus muscle (anterior constrictor 
of the pharynx). It terminates in the soft palate, after giving off on 
its course ascending and descending branches, which expend themselves in the 
walls of the pharynx. 

2. Livevan Arrery (Fig. 286, 15).--As considerable in volume as the 
parent branch, this artery is detached at an acute angle from it, at 
the extremity of the hyoid cornu. With the glosso-pharyngeal nerve, it 
passes beneath the basio-glossal muscle, crossing the small branch of the os 
hyoides, and extends to the extremity of the tongue by gliding in the 


THE COMMUN CAROTID ARTERIES. 583 


Fig, 286, 


ARTERIES OF THE HEAD. 


1, Common carotid artery; 2, Accessory thyroid artery, 3, 4, Thyro-laryngeal 
artery, divided into two branches; 5, Internal carotid artery; 6, Occipital 
artery ; 7, Atloido-muscular artery at its exit from the inferior foramen of the 
atlas; 8, Mastoid artery; 9, Prevertebral artery ; 10, Occipito-muscular artery ; 


584 THE ARTERIES. 


interstice between the genio-glossus and basio-glossus muscles, where 
it meets the branches of the lingual and hypoglossal nerves. 

Flexuous in its course, in order to adapt itself to the elongation of the 
tongue, the lingual artery emits a very great number of collateral branches, 
which escape perpendicularly from the entire periphery of the vessel; 
but chiefly above, below, and on the inner side, to ramify in the muscles 
and integuments of the tongue. 

Running parallel to each other, the two lingual communicate by 
five transverse ramuscules, and join at their terminal extremity, which 
becomes very slender. 

3. SupiineuaL Artery (Fig. 286, 16).—This artery has its origin 
at the anterior extremity of the maxillary gland, and runs forward along the 
external surface of the mylo-hyoideus muscle, which it afterwards crosses 
towards the posterior extremity of the sublingual gland. It then follows 
the inferior border of this gland, sending into it numerous branches, 
and after giving some filaments to the genio-glossus and genio-hyoideus 
muscles, is prolonged on the sides of the frenum lingue, where it ends by 
fine ramuscules in the buccal mucous membrane. 

Among the branches this artery detaches before attaining the sublingual 
gland, it is necessary to distinguish those which are destined to the mylo- 
hyoideus muscle, some of which, the descending, are thin and irregular ; 
and others, ascending, being long, thick, and parallel to each other. 

Sometimes this artery does not reach the sublingual gland; it then 
remains, for the whole of its extent, external to the mylo-hyoideus muscle, 
and sends its terminal divisions to the vicinity of the symphysis of tle 
chin. In this case, the gland receives a special branch trom the lingual 
artery, a circumstance which is usual in Man, in whom this artery is named 
the submental. 

4, Coronary or Inreriorn Laziat (Fig. 286, 17).—Springing from the 
glosso-facial artery at an acute angle, shortly before that vessel arrives 
at the maxillo-labial muscle, the inferior corenary artery passes under that 
muscle, and following its direction, descends into the texture of the lower 
lip, where it is mixed up with the ramifications of the mental nerve, 
and where it terminates by forming a very fine anastomotic arch with 
the vessel of the opposite side. 

In its track, it gives branches to the buccinator and maxillo-labial 
muscles, and to the tissues of the lower lip, to which it is chiefly destined. 
In its passage near the mental foramen, it receives the inferior dental artery 
as it leaves that opening. 

5. Coronary on Supgrion Lazran Artery (Fig. 286, 18)—Smaller 
than the preceding vessel, and often altogether rudimentary, this artery 
is detached from the principal trunk at nearly a right angle, above the 


11, Terminal extremity of the vertebral artery joining the atloido-muscular 
branch; 12, External carotid artery; 13, External maxillary artery ; 14, Pha- 
ryngeal artery; 15, Lingual artery; 16, Sublingual artery ; 17, Coronary, or 
inferior labial artery; 18, Coronary, or superior labial artery; 19, Superior 
terminal branch of the external maxillary artery ; 20, Inferior terminal branch 
of ditto ; 21, Maxillo-muscular artery ; 22, 23, Posterior auricular artery ; 24, 
Superficial temporal trunk; 25, Subzygomatic artery; 26, Inferior auricular 
artery; 27, Internal maxillary artery; 28, Inferior dental artery ; 29, Fasciculi 
of pterygoid arteries; 30, Tympanic artery; 31, Spheno-spinous artery , 32, Deep 
posterior temporal artery; 33, Deep anterior temporal artery ; 34, Ophthalmic 
artery ; 35, Supra-orbital artery ; 36, Lachrymal artery; 37, Buccal-artery ; 38. 
Palatine artery ; 39, Superior dental artery ; 40, Orbital branch of that vessel. : 


THE COMMON CAROTID ARTERIES 585 


origin of the pyramidal muscle of the nose, (supermaxillo-nasalis magnus), 
and sometimes below that muscle. It subsequently gains the upper lip, 
along with the infra-orbital branches of the superior maxillary nerve, 
by passing between the supernasalis-labialis and the pyramidal muscle of 
the nose; it then terminates in forming an arch by inosculation with the 
palato-labialis artery. 

The branches it gives off pass to the external ala of the nose and the 


textures of the upper lip. Some are expended in the muscles just named, 
and in the alveolo-labialis. ; 


2, Mawillo-muscular Artery. (Fig. 286, 21.) 


The maxillo-muscular artery is a vessel that does not appear to have its 
representative in Man. It emerges from the external carotid, above the 
point where it is included between the large branch of the os hyoides and 
the stylo-hyoid muscle. LKemarkable for the very obtuse angle it forms at 
its origin with the principal vessel, it descends behind the posterior border 
of the inferior maxilla, covered by the parotid gland. It then divides 
into two branches: a deep one, which goes to the internal pterygoid muscle, 
after furnishing some ramuscules to the neighbouring organs; and a 
superficial one, which turns round the posterior border of the maxilla, 
and emerging from beneath the parotid gland, above the insertion of 
the sterno-maxillaris muscle, plunges into the masseter, and expends itself 
in the body of that muscle by several branches which anastomose with the 
divisions of the subzygomatic artery. 


3. Posterior Auricular Artery. (Fig. 286, 22.) 


Third collateral branch of the external carotid, the posterior auricular 
artery arises at a very acute angle above, and a little behind, the preceding 
vessel. It ascends beneath the parotid gland, behind the base of the concha 
of the ear, crosses the cervico-auricular muscles, and reaches the extremity 
of the cartilage by passing underneath the skin which covers its posterior 

lane. 

E In its course, it emits several ascending auricular branches, which arise 
at different elevations and cover the concha with their divisions. Among 
these we ought to distinguish the first (Fig. 286, 23); this has its origin at 
the temporal trunk, and soon divides into two branches: one, profound, 
after sending a very thin filameut into the middle ear by the stylo-mastoid 
foramen, passes between the external auditory canal and the mastoid 
process to enter the subconchal adipose tissue and the internal scuto- 
auricular muscle; the other, superficial, imbedded in the parotid tissue, 
proceeds to the external side of the concha, and buries itself in the interior 
of that cartilage, along with the middle auricular nerve, after abandoning 
some external ramuscules. 

‘From these auricular branches there also escape a multitude of 
parotideal twigs. 


4, Superficial Temporal Artery or Temporal Trunk. (Fig. 286, 25.) 
This is the smallest of the two terminal branches of the external carotid. 
After a short ascending course between the parotid gland, the guttural pouch, 
and the neck of the maxillary condyle, behind which it is situated, 
this artery is divided into two branches: the anterior auricular and the 
subaygomatic. 


586 THE ARTERIES. 


Ayrurion Aurtcubar Artery (Fig. 286, 26).—This vessel appears to 
be, nut only by its volume, but also by its direction, the continuation of the 
temporal trunk. Embraced, near its origin, by the facial nerve and sub- 
zygomatic branch of the inferior maxillary nerve, it rises behind the 
temporo-maxillary articulation and supercondyloid process, beneath the 
parotid gland, to the temporal muscle, into which it passes after emitting 
parotideal twigs and auricular branches, one of which penetrates to the 
interior of the concha, while the others are expended in the anterior 
muscles of the ear and the integuments covering these muscles. 

Supzycomatio Artery (Fig. 286, 25.)—More considerable than the 
anterior auricular, this artery disengages itself from beneath the parotid 
gland by turning round the posterior border of the maxilla, along with the 
nervous anastomosis which gives rise to the subzygomatic plexus, and is placed 
above that anastomosis, beneath, and to the outside of, the afore-mentioned 
condyle. There it ends in two branches of equal volume : a superior or 
superficial, and an inferior or deep, both of which ramify in the substance 
of the masseter muscle, and anastomose with the divisions of the maxillo- 
muscular, or with the masseter branches of the external maxillary arteries. 

The superior branch, or transverse artery of the face, goes towards the 
anterior border of the masseter muscle in a flexuous manner, close to 
the zygomatic ridge. At first lying on the superficies of the masseter, 
it afterwards buries itself in that muscle. 

The inferior branch, or masseteric artery, dips in among the deep 
fasciculi of the masseter muscle, to which it is distributed, along with 
the masseteric nerve. Near its origin, it communicates with the deep 
posterior temporal artery by a fine ramuscule, which passes into the sigmoid 
notch. In Man and sore animals, this artery comes from the internal 
maxillary. : 


5. Internal maxillary or Gutturo-maaillary Artery. (Fig. 286, 27.) 


Situated at first immediately within the maxillary condyle, below the 
articulation of the jaw, this artery passes to the inner side, towards the 
entrance of the subsphenoidal (or pterygo-palatine) canal, by describing 
two successive curvatures: the first backwards, the other forwards. After 
being thus shaped like an 8, it travels forward along the subsphenoidal 
canal to the orbital hiatus, and then reaches the maxillary hiatus to enter 
the palatine canal, where it is designated the palato-labial artery. 

In order to study its relations, the course of this artery may be divided 
into three portions: a posterior or guttural, a middle or sphenoidal, and an 
anterior or infra-orbital. The posterior portion lies on the internal face of 
the external pterygoid muscle, covered inwardly by the guttural pouch, and 
crossed outwardly by the inferior maxillary nerve and some of its branches. 
The middle division is enveloped by the bony walls of the subsphenoidal 
canal. The anterior portion, alone with the superior maxillary nerve, 
passes across the space separating the orbital from the maxillary hiatus, by 
creeping along the palate bone, beneatk a considerable mass of fat. 

CoLLATERAL Brancuzs.—The arteries given off by the internal maxillary 
on its course are eleven principal. Five arise from the first portion of the 
vessel: two below, the inferior dental and the group of pterygoid arteries; 
three above, the tympanic, spheno-spinous, and deep posterior temporal. 

_ ‘Two escape from the superior portion of the interosseous or sphenoidal 
division. These are the deep anterior temporal and ophthalmic arteries. Four 


THE COMMON CAROTID ARTERIES. 587 


commence from the third section of the artery: two inferior, the buccal and 
palatine ; and two upper, the superior dental and the nasal. 

1. Inventor Dentat Anrsry (Fig. 286, 28).—This vessel, also named 
the mawillo-dental artery, is detached at a right angle from about the middle 
of the first curvature described by the internal maxillary. It travels 
forward and downward between the two pterygoid muscles, afterwards 
between the internal one and the maxillary bone, entering with the inferior 
maxillary nerve into the dental canal, through the whole extent of which it 
passes. Arrived at the mental foramen, it separates into two branches: a 
deep one, which continues the interosseous course of the vessel, to be 
distributed to the roots of the tusk or tush, and the three adjoining incisor 
teeth; the other superficial, generally very slender and even capillary, 
issuing by the mental foramen with the terminal branches of the maxillary 
nerve, and anastomosing with the inferior coronary artery. 

Before penetrating the maxilla, this artery furnishes divisions to the 
internal pterygoid and mylo-hyoid muscles. 

In the interior of the maxillo-dental canal, it gives off diploic branches 
as well as twigs, destined to the roots of the molar teeth and the alveolar 
membrane. 

2. Prerycor Arterms (Fig. 286, 29)—It may be said, in a 
general manner, that the two pterygoid muscles borrow their arteries from 
all the vessels passing near them, though there are two, and sometimes three, 
-pranches more especially intended for them. These branches, or, properly 
speaking, pterygoid arteries, arise from the middle of the second curvature of 
the internal maxillary, either at an acute or right angle, and enter the 
pterygoid muscles, after a short course forward and downward on the 
external tensor palati muscle; this and its fellow, the internal muscle, also 
receiving some branches. 

3. Tympanto Artery (Fig. 286, 30).—A very thin and small, but constant 
artery, gliding along the surface of the guttural pouch, accompanying 
the tympano-lingual nerve, and penetrating the tympanic cavity by a foramen 
situated at the base of the styloid process of the temporal bone (the fissura 
Glaseri). It throws off ramuscules to the wall of the guttural pouch 
and the trigeminal nerve ; these often arise directly from the trunk of the 
internal maxillary artery, besides the tympanic branch. 

4, SpHuNno-spinous on Great Meyineran Artery (Fig. 286, 81).— 
Commencing at an obtuse angle, opposite the pterygoideal vessels, this 
artery lies against the sphenoid bone, near the temporal insertion of 
the tensor palati muscles, is directed backwards and upwards, enters the 
cranium by the anterior lacerated foramen, outside the inferior maxillary 
nerve, passes beneath the dura mater, and soon after engages itself in 
a particular foramen in the parieto-temporal canal, where it anastomoses by 
inosculation with the mastoid artery. 

Before penetrating this canal, the spheno-spinous artery gives off 
a, meningeal branch, whose ramifications, destined to the dura mater, stand 
in relief on that membrane, and creep along in the small grooves channeled 
on the inner surface of the cranium. 

The volume of this vessel is subject to the greatest variations, and 
is always in an inverse proportion to that of the mastoid artery. 

5. Deep Posterior Temrorat Artery (Fig. 286, 32).—This arises at 
a right angle, immediately before the entrance of the internal maxillary 
artery into the subsphenoidal canal. Then it ascends on the temporal bone, 
in the temporal muscle, passing in front of the temporo maxillary articula- 


588 THE ARTERIES. 


tion, which it turns round to be inflected backwards. This vessel com- 
municates with the masseteric artery by a fine division, which traverses the 
sigmoid notch of the maxillary bone. : 

a Deep ANTERIOR Tea Artery (Fig. 286, 33).—Springing at a 
right angle, like the preceding, in the interior of the subsphenoidal canal, 
this artery escapes by the superior branch of that conduit, ascends against 
the bony wall of the temporal fossa, along the anterior border of the temporal 
muscle, in which it is almost entirely expended. It gives some ramuscules 
to the adipose tissue of the temporal fossa. Its terminal extremity arrives 
beneath the internal parieto-auricular muscle, ramifies in it, and in the skin 
of the forehead. 

7. Opataatmic Artery (Fig. 286, 34).—This vessel has a somewhat 
singular arrangement. After being detached from the internal maxillary in 
the subsphenoidal canal, in front of the deep anterior temporal artery, with 
which it is sometimes united, it penetrates by the orbital hiatus to 
the bottom of the ocular sheath; it then enters the cranium by the orbital 
foramen, after describing a loop opening backwards and downwards, which 
passes between the muscles of the eye, beneath the superior rectus, and 
above the optic nerve and the sheath formed round it by the posterior rectus 
(or retractor). 

Entering the cranium, the ophthalmic artery passes inwards along a 
groove in the ethmoidal fossa, and terminates by two branches: a meningeal 
and nasal. 

Collateral branches.-—In its orbital track, the ophthalmic artery 
emits numerous collateral branches, which arise from the convex side of the 
loop described by this vessel. These are: the muscular arteries of the 
eye, the ciliary, central artery of the retina, supra-orbital, and lachrymal 
arteries. 

In its cranial portion, it furnishes the cerebral branches. 

The muscular arteries of the eye have a destination sufficiently indicated 
by their name. Their number and mode of origin vary. They are 
usually two principal, which arise directly from the ophthalmic artery, and 
others of a smaller size furnished by the lachrymal and supra-orbital 
branches. 

The ciliary arteries, destined to the constituent parts of the globe of the 
eye, but chiefly to the choroid coat, the ciliary processes, and the iris, 
are long thin branches, emanating, for the most part, from the muscular 
arteries. 

We only mention the centralis retinee artery here; as it and the ciliary 
arteries will be described when we come to study the visual apparatus. 

The supra-orbital artery ascends, with the nerve of the same name, against 
the inner wall of the ocular sheath, to gain the supra-orbital foramen ; 
passing through that orifice, it is distributed to the frontal and supra-orbital 
muscles, the orbicularis of the eyelids, external temporo-auricularis muscle, 
as well as to the integument of the frontal region (Fig. 286, 35). 

The lachrymal artery creeps upwards and forwards. between the muscles 
of the globe of the eye and the superior wall of the ocular sheath, to terminate 
in the lachrymal gland and the upper eyelid (Fig. 286, 36.) 

The cerebral branches of the ophthalmic artery vary in number, and 
frequently there is only one, of somewhat considerable volume. They pass 
to the anterior extremity of the cerebral lobe, and anastomose with the 

divisions of the anterior cerebral artery. 


Terminal branches.—The meningeal branch, after detaching ramuscules 


THE COMMON CAROTID ARTERIES. 589 


to'the dura mater, and particularly to the falx cerebri, anastomoses on the 
median line, below the process of the crista galli, with that of the 
opposite side, and afterwards joins the anterior cerebral artery. 

The nasal branch traverses the cribriform plate of the ethmoid bone, and 
divides into a number of ramuscules, which descend either on the ethmoidal 
cells, or on the middle septum of the nose, where their ramifications form 
arterial tufts of a pleasing aspect. 

8. Bucoan Antury (Fig. 286, 87).—The buccal artery emerges at an acute 
angle from the internal maxillary, a short distance in front of the orbital 
hiatus, and descends obliquely between the maxillary bone and the superior 
insertion of the internal pterygoid muscle, terminating in the posterior 
part of the molar glands, and in the alveo-labial and maxillo-labial muscles. 

In its course it gives some insignificant ramuscules to the pterygoid 
muscles, as well as the masseter, and a long adipose branch to the cushion 
in the temporal fossa. The latter sometimes comes directly from the 
internal maxillary artery. 

9. StapHytin Artery (Fig. 286, 38)—A very thin filament, which 
accompanies the posterior palatine nerve in the groove of the same name, 
and is distributed to the soft palate. 

10. Supzrion Denran Artery (Fig. 286, 39).—This vessel, which is 
also named the supermawillo-dental artery, enters the superior dental canal, 
arrives near its inferior or infra-orbital opening, and then divides into two 
thin branches. One of these continues in the same course in the super- 
maxillary bone, to supply arterial blood to the alveoli of the foremost 
molars, the tusk, and the incisor teeth; the other passes out of the canal 
with the terminal divisions of the superior maxillary nerve, and com- 
municates on the forehead with a ramuscule from the external maxillary 
artery. 

On its way, the superior dental artery emits several collateral branches, 
the majority of which commence in the interior of the dental canal, and 
pass either to the alveoli of the posterior molars, the tissue of the bone, or 
the membrane lining the sinuses. One of these branches—the orbital, and 
the largest—escapes from the principal artery before its entrance into the 
supermaxillary canal, creeps along the floor of the orbit towards the nasal 
angle of the eye, whence it descends on the forehead, after giving off 
some divisions to the caruncle of the eye, the lachrymal sac, and the lower 
eyelid. 

a 11. Nasat on SpHeno-patatine Anrtery.——Situated, at first, at the 
bottom of the maxillary hiatus, this artery, springing at a right angle from the 
parent trunk, traverses the nasal foramen, and separates into two terminal 
branches—an external and an internal—in ramifying on the walls of the 
nasal cavity. 

TerminaL Branod oF THE Internat Maxinuary Artery. Panato- 
Lasrat on Pauatine Artery. (Fig. 148, 3.)—A continuation of the 
internal maxillary, this vessel at first traverses the palatine canal, follows 
the palatine groove to near the superior incisors, is then inflected inwards 
above a small cartilaginous process (Fig. 148, 4), and unites on the median 
line with the artery of the opposite side, forming an arch whose convexity 
is forwards, and from which proceeds a single trunk that passes into the 
incisive foramen. 

The palatine arteries, in their advance, furnish a series of branches 
destined to the anterior part of the soft palate, the membranes on the roof of 
the mouth, and the gums and upper teeth. ; 


590) THE ARTERIES. 


The single trunk which results from their anastomoses is placed, im- 
mediately after its exit from the incisive foramen, directly beneath the 
buccal mucous membrane, and at once divides into two principal branches 
—a right and left; these are lodged in the tissue of the upper lip, and pass 
back to meet the coronary arteries, with which they anastomose by Inoscula- 
tion, after throwing off on their track a great number of branches destined 
to the muscles and integuments of the lip and nostrils. 


DIFFERENTIAL CHARACTERS IN THE CAROTID ARTERIES OF OTHER THAN SOLIPED ANIMALS. 


1. The Carotid Arteries in Carnivora, 


In the Dog, the carotids arise singly from the brachio-cephalic trunk, and ascend 
beneath the transverse process of the atlas, along the trachea, following a course 
exactly like that pursued by these vessels in the Horse. eee 

Among the collateral branches furnished by them, may be distinguished the thyro- 
laryngeal artery, remarkable for its enormous calibre, its descending in front of the 
lateral lobe of the thyroid gland, and its termination in the median isthmus of that 

nd. 
ee terminal branches of the carotid are, as in Solipeds: 1, The oceépital ; 2, The 
internal carotid ; 3, The external carotid, the continuation of the primitive vessel. 

OcctrrraL Arrery.—Inconsiderable in volume, this vessel arises in front of the 
anterior border of the transverse process of the atlas, passes into the notch on its 
border, and divides into two branches—the oce/pito-muscular and the cerebro-spinal 

teries. 
~ In its course, it gives off branches analogous to those which emanate from the pre- 
vertebral artery of the Horse. It also gives a mastutd artery, which only sends one very 
small branch into the parieto-temporal canal, and is destined almost exclusively to the 
deep muscles of the neck. In addition, the occipital throws offa retrograde artery, which 
directly joins the vertebral. : ; : : ; 

The arrangement of the occipital artery in Carnivora is, therefore, almost identical 
with what has been described in Solipeds. 

IyternaL Carotip Arrery.—This vessel reaches the posterior opening of the carotid 
canal, along which it passes forward, then describes a very curious flexure which leaves 
the cranium by the carotid foramen (see page 62), then re-enters that cavity after 
receiving a particular branch from the external carotid. It afterwards anastomoses on 
the side of the pituit wy fossa, with the divisions of the spheno-spinous artery and the 
returning branches of the ophthalmic artery, forming a kind of plexus, which appears to 
be a trace of the réseau admirable of Ruminants and Pachyderms, and from which 
proceed the cerebral arteries. 

Exrervat Carorm Arrery.—This arterial branch terminates, as in Solipeds, by 
the superficial temporal and the internal maxillary arteries, 

It gives off on its course: 1. An artery representing the meningeal branch of the 
prevertebral of the Horse, and which ascends in a flexuous manner on the side of the 
pharynx to join the carotid flexure. 

2. A laryngeal artery, entering the larynx with the superior nerve of that organ, 
after giving ramuscules to the maxillary gland. 

3. The lingual artery, a very large tortuous branch, whose course resembles that of the 
same vessel in the Horse. 

4. A facial or external maxillary artery, divided into two branches above the inferior 
insertion of the digastricus. One of these branches, analogous perhaps to the submental 
of Man, passes within this insertion, and is prolonged to the chin, after furnishing 
ramuscules to the parts lodged in the intermaxillary space. The other branch winds 
round the inferior border of the maxilla, in front of the masseter muscle, and is expended 
on the face by ascending and descending branches, among which we can readily perceive 
the two coronary arteries, and the two twigs which we have noticed in Solipeds as 
termiial branches of the vessel. 

5. The posterior auricular artery, after detaching parotideal and musculo-cutaneous 
vessels, is situated on the middle of the external face of the concha, and is directed 
towards the terminal extremity of the cartilage, where it separates into two branches, 
which are inflected en arcade, and return, in following the borders of the concha, towards 
the base of the latter, where they anastomose with other branches, either from the pos- 
terior or ant:rior auricular, and which come to meet them. 


THE COMMON CAROTID ARTERIES, 591 


_ Superficial temporal artery.— After a brief course behind the temporo-maxillary articula- 
tion, this vessel bifurcates: its posterior or auricular branch, anastomosing with a division 
of the posterior auricular, but not before it has sent ramuscules to the interior of the 
eoncha, and furnished some musculo-cutaneous twigs. The other, the anterior or temporal 
branch, glides beneath the aponeurosis of the temporal muscle, above the upper margin 
of the zygomatic arch, and winds upwards and inwards around the outline of the orbit, 
to terminate on the face by anastomosing ramuscules, either with the infra-orbital branch 
of the superior dental artery, or with the facial. In its subaponeurotic course, it gives 
divisions to the temporal muscle. Above the orbital arch, it emits several superficial 
ascending and internal twigs, one of the principal of which communicates by ramuscules 
with the posterior auricular artery, the auricular branch of the superficial temporal, and 
with the homologous ramuscules from the opposite side. 

Internal maxillary artery—The course pursued by this vessel is similar to that it 
follows in the Horse. After describing an S curvature between the condyle of the 
maxillary bone and external pterygoid muscle, it traverses the subsphenoidal canal, 
and passes outside the internal pterygoid towards the maxillary hiatus, where it is con- 
tinued by the superior dental artery. 

a. The followivg are the principal collateral branches emitted by this vessel : 

1, The inferior dental artery. 

2. The deep posterior temporal artery, which furnishes a masseteric branch that 
traverses the sigmoid notch of the maxillary bone to enter the masseter muscle. 

3. A fine tympanic twig. + 

4. The spheno-spinous artery, almost entirely destined to the formation of the plexus 
of the cerebral arteries. 

5. Several pteryyoid arteries. 

6. The ophthalmic artery, which, before entering the ethmoidal fossa by the orbital 
foramen, gives, independently of the branches noted in Solipeds—except the supra-orbital, 
which is absent—a fasciculus of particular branches. These penetrate the cranium by the 
great sphenoidal fissure, accompanying the motor and sensory nerves of the eye, to join 
the internal carotid and spheno-spinous arteries. 

7. The deep anterior temporal artery. P 

8. A staphylin artery, more voluminous than that in the Horse. 

9. The palatine artery. 

10. A buccal and an alveolar artery, whose principal divisions enter Duvernoy’s gland. 

b. The superior dental artery, which terminates the internal maxillary, and furnishes 
an orbital and an infra-orbital branch, as in Solipeds. The latter, remarkable for its 
volume, emerges from the supermaxillary canal with the infra-orbital nerves, to join the 
divisions of the external maxillary artery on the face, and in the tissue of the upper lip. 


2. Carotid Arteries in the Pig. 


There is nothing particular to notice regarding the course of these vessels, which we 
know arise separately from the brachio-cephalic trunk. ; 

Occipital artery —In its distribution, it greatly resembles the same vessel in the Horse 
and Dog. Its most important branches are the following: 1, A very small retrograde artery, 
anastomosing with the vertebral; 2, A branch which mounts into the muscles of the 
neck, representing the mastoid artery; 3, Several occipital twigs, which pass, with the 
principal artery, by the anterior foramen of the atlas. This artery is expended in a 
complete manner in the muscles of the neck, and without sending a cerebro-spinal branch 
to the interior of the spinal canal. ' 

Internal carotid artery—After furnishing a large meningeal artery, this vessel enters 
the cranium by the posterior lacerated foramen, and there divides to form a réseau 
admirable, analogous to that of Ruminants, and of which a description will be given 
hereafter. The cerebral arteries arising from this réseau differ but little from those of 
Solipeds; these are the posterivr cerebral arteries, which give rise to the basilar trunk, 
and originate the median spinal artery. . 

External carotid artery.—This artery is seen to pass between the pterygoid muscles 
and the branch of the maxillary, in describing several inflexions, and arrives in the 
maxillary hiatus, without exhibiting in its course any sensible distinction between the 
external carotid, properly called, and its continuation, the internal maxillary artery. 

Among the branches it supplies, we notice : ; : 

1. The lingual artery, more voluminous, perhaps, than in the other animals, 

2. A branch analogous, in its origin at least, to the glosso-facial artery of the Horse, 
and which distributes its ramuscules in the intermaxillary space, and particularly to the 
salivary and lymphatic gland 


592 THE ARTERIES. 


8, The posteriur auricular artery, noticeable for its great length and considerable 


vo the transverse artery of the face and the anterior auricular artery, arising separately 


beside eavh other, and extremely slender. | jl 
e, Sey eral deep temporal and masseterte arteries. 
6. Pterygoid eat ciee seineh 
. An enormous buccal branch. ; 
i The ophthadate artery, concurring to form the réseau admirable. 


9. A small orbital branch, coming from the superior dental artery in Solipeds and 


Carnivora, : ; 
10. The nasal, palatine, and superior dental arteries. 


3. Carotid Arteries of Ruminants. 


A. In the Sheep, which will serve as a type for this description, the carotid arteries 
arise by a common trunk from the right axillary artery, as in Solipeds. Arriving in the 
cephalic region, towards the upper part of the neck, they furnish a thyroid and a 
laryngeal branch, then give off a very slender occipital artery, and are continued from this 
point by the eaternal carotid. . : : : a 

The internal carotid, properly called, is absent, and we will see immediately how it is 

ensated for. 

see Decipital artery Having given some ramuscules to the anterior recti muscles of the 
head, and a small meningeal branch which enters the cranium by the posterior lacerated 
foramen, this vessel passes into the condyloid foramen, which also affords a passage to 
the hypoglossal nerve, places itself beneath the dura mater, and is inflected backward to 
open into the anterior extremity of the collateral artery of the spine, at the superior 
foramen of the atlas. The branch resulting from this junction emerges by that foramen, 
to be distributed in the muscles of the neck, where its divisions resemble those of the 
occipito-muscular and atloido-muscular branches in the Horse. ; ; 

In traversing the condyloid foramen, the occipital artery sends into the parieto- 
temporal canal, by a peculiar bony conduit (see page 56), a very small filament which 
is distributed to the dura mater, in anastomosing with a branch of the posterior auricular. 

It communicates, after its entrance into the cranial cavity, with the réseau admirable. 

External carotid artery—Terminated, as in the Horse, by the superficial temporal and 
internal maxillary arteries, this vessel sends off on its course : : . 

1. A pharyngeal artery, whose origin is nearly confounded with that of the occipital 
artery. 

oe The Ungual artery, furnishing a collateral branch which exactly represents the 
submental of Man, and is divided into two branches, which resemble the sublingual and 
ranine arteries. 

3. A large division for the maxillary gland. 

4. The posterior auricular artery, from which proceeds: 1, The stylo-nastoid twig, 
which penetrates the aqueduct of Fallopius; 2, Concho-muscular branches; 3, A large 
branch, resembling the mastoid artery of the Horse. This enters the temporo-parietal 
canal by a small foramen between the occipital and petrous portion of the temporal 
bone, and forms two branches: an external, emerging from this canal by the wide 
orifice in the temporal fossa, and expending itself in the temporal muscle, after anas- 
tomosing with the two deep temporal arteries; and an internal, a considerable 
meningeal artery, destined principally to the falx cerebri and the tentorium cerebelli. 

5. A small mazillo-muscular artery, ramifying entirely in the internal pterygoid and 
the subcutaneous muscles. 

Superficial temporal artery—This vessel divides, almost at its origin, into three 
branches : 

1. A posterior, supplying the anterior arteries of the ear, 

2. An anterior, forming the transversal faciei, and terminating by the coronary or 
ee cae after giving some ramuscules to the masseter and the muscles of the 

orehead, 

3. A median artery, representing the middle temporal of Man. This vessel detaches 
some divisions to the temporal muscle, gives off the lachrymal artery, as well as a 
palpebral branch rising from the same point, and terminates near the base of the cranium 
by two particular arteries which are developed around the base of the horn, and form a 
real arterial circle from which inferior and superior divisions axe given off. The latter 
are the most considerable, and glide on the bony core of the frontal appendage, where 
they are distributed almost exclusively to the generating membrane of the horny tissue, 
only throwing some filaments into the sinuses, 


THE COMMON CAROTID ARTERIES 593 


Internal maxillary artery.—It does not traverse the subsphenoidal canal, as that 
bony passage does not exist. 


The following are its principal branches: 

1. The inferior dental artery, which emits some pterygoid ramuscules. 

2. The spheno-spinous artery, arising from the same point as the preceding, often in 
common with it, giving also some pterygoid branches, and entering the cranium by the 
oval foramen to aid in the formation of ‘the reseau admirable, in a way to be indicated 
hereafter. 

3. The deep posterior temporal artery, which detaches a masseleric artery. 

4. The deep anterior temporal artery. 

5. The buceal, principally destined to the masseter muscle. 

6. The ophthalmic artery, longer than in the other animals, forming a loop before 
traversing the orbital foramen, and giving a supra-orbital branch and a fasciculus of 
muscular and ciliary arteries. Near the point where the originating trunk of this 


Fig. 287, 


THE RESEAU ADMIRABLE OF THE SHEEP, SEEN IN PROFILE. 

1, Carotid artery; 2, Occipital artery; 3, Lingual artery; 4, Maxillo-muscular 
artery ; 5, Posterior auricular artery ; 6, Superficial temporal artery ; 7, Anterior 
auricular artery; 8, Middle temporal artery; 9, Transverse artery of the face; 
10, Internal maxillary artery; 11, Inferior dental artery; 12, Spheno-spinous 
artery; 13, Deep posterior temporal artery; 14, Deep anterior temporal artery ; 
15, Commencement of the originating arteries of the réseau admirable; 16, Ence- 
phalic réseau admirable; 17, Trunk of the encephalic arteries arising from the 
réseau admirable ; 18, Ophthalmic artery; 19, Ophthalmic réseau admirable ; 20, 
Common origin of the arteries of the eye; 21, Supra-orbital artery; 22, Buccal 
artery; 23, Superior dental artery; 24, Orbital branch of the latter; 25, 
Palatine artery; 26, Nasal artery 


fasciculus is detached, the ophthalmic artery shows on its course a very curious arrange- 
ment which has not yet been noticed, we believe: this is a veritable arterial plexus in a 
ganglionic form, in principle exactly disposed as that about to be described (Fig. 287, 19). 

7. The originating arteries of the réseau admirable, usually consisting of two principal 
vessels, arising with the ophthalmic. passing backward through the suprasphenoidal 
canal, and ramifying in a special manner to form a mass of reticular twigs, designated 
the réseau admirable (Fig. 287, 16). 

This network is a small ovoid mass, elongated from before to behind, placed beneath 
the dura mater, on the side of the sella turcica, within the superior maxillary nerve, and 
composed of a multitude of fine arterial divisions which anastomose with each other 


594 THE ARTERIES. 


i licated manner. Its inferior extremity, passing into the supra- 
een reed ree the generating arteries. The posterior extremity, covered by the 
clinoid process, is in communication with the spheno-spinous artery, which there expends 
itself. Towards its middle part, and above, the twigs forming it reconstitute them- 
selves into a single trunk analogous to the intercranial portion of the ¢nternal carotid of 
Solipeds (Fig. 287, 17), and which traverses the dura mater, dividing into three branches, 
These are the anterior, middle, and posterior cerebral arteries ; the latter anastomoses, by 
convergence, with the homologous artery of the opposite side, behind the pituitary 
gland, to form the basilar trunk aud the median spinal artery, which continues it. 

This singular disposition of the arteries of _the encephalon well deserves the name of 
réseau admirable (admirable network), by which it is known. If we were desirous of 
giving a summary idea of this network, we might compare it to a lymphatic gland, whose 
efferent vessels would be represented by the originating arteries with the spheno-spinous, 
and the etterents by the originating trunk of the encephalic arteries. : 

8. Next comes the superior dental, whose orbital branch presents a considerable 
volume, and terminates on the anterior surface of the head by long superficial di visions. 
Some of these, the ascending, anastomose with the inferior branches of the arterial 
circle situated around the base of the horn; while others, the descending, communicate 
with the injra-orbital branch of the same vessel, and with the superior coronary 

ry. 

a The last to be given off are the nasal and palatine arteries, which terminate the 
internal maxillary : the nasal artery is disposed 
Fig. 288, asin the Horse; the palatine goes entirely to the 
alate. 
B. In the Ox, we find all the peculiarities 
just enumerated, save with the following differ- 
ences : 

1. A little above the origin of the lingual 
artery, the external carotid gives rise to an 
external maxillury artery, which turns round 
the inferior border of the maxillary bone, in 
company with its satellite vein, and terminates 
on the forehead, as in the Horse, after supply- 
ing the coronary arteries, 

2. The maxillo-muscular artery is distributed 
to the two masseters—to the external as well as 
the internal. 

3. The transverse artery of the face does not 
form the coronary arteries, as these come from 
the external maxillury; it is altogether ex- 
pended in the masseter muscle. 

4. The anterior auricular artery sends an 
enormous branch into the temporo-parietal canal, 
by the orifice situated behind the supercondyloid 
process. 

5. The ophthalmic artery and the generating 
arteries of the réseau admirable proceed from a, 
common trunk. 

6. The réseau itself shows some differences. 
We do not find, as in the Sheep, two lateral 
. elongated lobes, almost independent of each 
THE RESEAU ADMIRABLE OF THE OX}; other, but a circular mass surrounding the sella 

POSTERIOR FACE. turcica. Besides, the occipital arteries concur 
1, Réseau admirable; 2, Trunk of the in its formation, and pass into its posterior part 
originating arteries of the réseau ad- (Fig. 288). 
mirable ; 3, Spheno-spinous artery; 4, (This réseau admirable is the “ rete mira- 
Trunk of the encephalic, or internal bile” of Galen, and would appear to be formed 
carotid arteries; 5, Branches of the on the carotid and vertebral arteries of animals, 
occipital passing to the réseau admir- which, in a state of nature, feed from the 
able; 6, Interspinal arterial canal, ground; the object being to furnish an equable 
formed by the intervertebral spinal and prolonged supply of blood without the risk 
branches, of check or hindrance, and thus to obviate the 
tendency to congestion of the brain during the 
dependent position of the head. This minute subdivision and subsequent reconstitution 
of an artery, with a like intention, is also observed in other creatures besides grazing 


THE COMMON CAROTID ARTERIES, 595 
animals. The vessels in the arm of the sloth are so disposed that the animal can remain 
suspended by it for long periods, and a similar arrangement is noted in the legs of birds, 
such as the swan, goose, &c., which stand for a long time. Around the Horse's foot the 
arteries break up into numerous divisions, and we know that this animal can remain 
in a standing attitude for months, and even years. ‘Ihe rete ophthalmicum of birds is 
arranged like the rete mirabile. The same object is sometimes attained by great tor- 
tuosity, as we have already seen in the description of several of the arteries. Perhaps 
the most marked example, Liowever, is to be found in the carotid artery of the Seal, 
which is nearly forty times longer than the space it has to traverse.) 


COMPARISON OF THE CAROTID ARTERIES OF MAN WITH THOSE OF ANIMALS, 


The common carotids of Man have a separate origin, the right arising from the 
arteria innominata, the left from the arch of the aorta. At the inferior border of the 
thyroid cartilage, they terminate by only two branches: the external and internal 
carotids; the occipital artery is but a division of the former. 


Fig. 289. 


ARTERIES OF THE FACE AND HEAD OF MAN. P , 
i " rotid; 3 rnal carotid; 4, 4, Occipita 
otid; 2, Internal carotid; 3, Externa : ; 4, 4, 

% ee ‘Superiey thyroid artery; 6, Trapezius; 7, Lingual artery ; 8, Sterno- | 
= aie "9, Facial artery; 10, Temporal artery, dividing into anterior and 
sreterion branches ; 11, Submental branch; 12, Transverse facial artery; 13, 
Taferior labial branch ; 15, Inferior coronary, and, 17, Superior coronary branch ; 
19, Lateral nasal branch; 21, Angular branch. 


rerY.—Contrary to what is observed in animals, the internal 
an is Ale seen fal the external, a difference which is explained in Man by 


596 THE VEINS. 


the predominance of the cranium over the face. This vessel describes a flexuous course 
until it reaches the carotid foramen in the petrous bone; it forms two curves in the 
cavernous sinus, penetrates the dura mater, and divides at the fissure of Sylvius into 
four branches, which are, as in Solipeds: the posterior communicating, anterior cerebral, 
middle cerebral, and artery of the choroid plexus, The internal carotid has an 
important collateral branch, the ophthalmic artery, that arises from the convexity of 
the curve the carotid makes inside the anterior clinoid process, at the bottom of the 
orbit. If it differs at its origin, yet this vessel has a distribution analogous to that 
1 described. 

Oa CaroTip ArTery.—In its origin, course, and termination, the extemal 
comports itself as in animals. It gives rise to six branches : 

4. The superior thyroid, resembling in its distribution the thyro-laryngeal of 
Solipeds. 

2 The Lingual artery, which furnishes a sublingual, and takes the name of ranine 
at its termination. 

3. The facial artery, which gives off the palatina ascendens analogous to our 
pharyngeal, and the submental. 

4. The posterior auricular artery. 

5. The tnferior pharyngeal artery. . 

6. The occipital. —'This vessel represents the occipital of the Horse minus its cerebro- 
spinal branch. It gives off a mastoid artery, and terminates in the muscles of the neck 
and on the posterior aspect of the cranium. The cerebro-spinal branch is replaced by 
the termination of the vertebral artery, which forms on the inferior face of the medulla 
oblongata the basilar trunk, whose disposition is identical with that already described. 

The superficial temporal artery, and the internal maxillary artery, constitute the 
termination of the external carotid. 

The ‘internal mavrillury is directed towards the spheno-palatine or nasal foramen, 
into which it passes and terminates as the spheno-spinous artery. It does not give off 
the ophthalmic artery, that vessel coming from the internal carvtid; but it furnishes 
all the other branches we have studied in animals. There are. therefore: a tympanic 
artery ; a meningeal, middle, or spheno-spinous ; an anterior and posterior deep temporal ; 
an tuferior dental; a buccal; a masseteric; pterygoideans; and a descending palatine 
or palato-labial artery. 


THIRD SECTION. 
THE VEINS. 


CHAPTER I. 
GENERAL CONSIDERATIONS, 


Derriition.—The veins are the centripetal vessels of the circulatory 
system. They bring back to the heart the blood which had been carried 
from that viscus to the organs. Some proceed from the lungs, carrying 
ted blood, and converge towards the left auricle of the heart: these are 
the pulmonary veins, or veins of the lesser circulation. Others emerge from 
the mass of all the organs, transport the dark blood, and open into the right 
auricle: these are the veins of the general circulation. 

There are, therefore, two venous systems commencing by a capillary 
network, opposite an arterial network. Sometimes a third system of veins 
has been described for the intestines; indeed, the vena porte: offers a certain 
independence in the midst of the veins of the general circulation, as it 
terminates in a capillary plexus in the interior of the liver, and by this 
plexus it communicates with the posterior vena cava, 

Exrerwan Coxrormation.—The veins, after succeeding the capillary net- 
work which terminatcs the arteries, or the cells of the erectile tissues, 


« 


GENERAL CONSIDERaTIONS. 597 


form a series of convervent ramifications which repeat, in a general manner, 
but in an inverse sense, the arterial ramifications whose course they for 
the most part follow. A certain number, nevertheless, are placed at some 
distance from the arterial trunks, beneath the external tegumentary 
membrane, where they are disposed in a vast network which constitutes 
the superficial veins of the body. Apart from this peculiarity, we have 
nothing more to say with regard to the situation, direction, relations, and 
anastomoses of the veins: than has been already made known in studying 
the arteries. It is only to be remarked, that the anastomoses of the venous 
system are more numerous, larger, and more complicated, than those 
of the arterial system ; that they also communicate with more voluminous 
trunks; and that they very often join the deep to the superficial veins. 
At certain points (external genital organs, bladder, rectum), the anastomoses 
are so numerous as to constitute veritable venous plexuses. These are more 
especially met with in regions where the circulation is exposed to be more 
or less hindered, either from the displacement of organs or variations in 
their volume. 

With regard to form, we also find a close analogy between the veins 
and arteries. The majority of the first, at least, represent—as do the second 
—cylindrical tubes, slightly knotted, it is true, on those parts of their track 
which correspond to their valves; the only exceptions are found in the 
venous dilatations of the dura mater—polyhedral spaces which are designated 
sinuses. On the other hand, veins offer the same collective form as the 
arteries; the general volume of the venous ramifications being as much more 
developed as they are distant from the heart, all the branches collected at 
last into an imaginary single canal would forin a hollow cone whose apex 
would correspond to the auricles. : 

It is only in comparing the two orders of vessels with reference to their 
number and capacity, that we can discover any sensible difference. The 
veins are more numerous than the arteries, as a great number of the latter 
are accompanied by two of the former, and the subcutaneous veins have no 
representatives in the arterial system. All the veins being, besides, much 
more voluminous than the corresponding arteries, it follows that the total 
capacity of the venous system much surpasses that of the arterial tree, and 
that we may boldly consider the relation of two to one as being the approxi- 
mative expression of this difference. 

When the veins are compared with the arteries, it is remarked that the 
relations between the length of the trunks and branches are reversed. In 
the arteries, the trunks are large and the branches short; in the veins, on 
the contrary, the branches are relatively much longer than the trunks. 
This disposition favours the flow of the blood in the veins, at whose 
commencement we do not find, as in the arteries, a propelling organ. 

Another arrangement to answer the same end, in opposing the influence 
that atmospheric pressure might have on the veins, is the attachment of 
these vessels to the walls of the cavities they pass through ; this is observed, 
for instance, at the entrance to the thorax. 

This disposition, so favourable to the circulation of the blood, becomes 
a constant source of danger to the surgeon, by its permitting the intro- 
duction of air into the circulatory system when a vein is opened. 

Internat Conrormation.—The interior of the veins is remarkable for 
the presence of valvular folds, whose disposition resembles, in principle, that 
of the sigmoid valves of the heart. These veins offer: an adherent border 
attached to the walls of the vessel; a free, semilunar border; a concave 

41 


598 THE VEINS. 


face turned towards the heart when the valves are tense; and a convex face 
which, on the contrary, looks towards the roots of the veins. 

These valves are often isolated, and sometimes joined in twos or threes ; 
according to some authorities, they are even found four or five together, 
arranged in a circular manner. All the veins are not provided with them, 
however, and where they exist they may be more or less numerous. They 
are absent in the pulmonary system, and in the trunk of the vena cava; 
absent or quite rudimentary throughout the extent of the vena porte; rare 
and slightly developed in the vena azygos, the veins of the testicle, uterus, 
and ovary; and very numerous, very large, and very complete in the veins 
of the limbs. 

The function of these valves is to favour the course of the blood, and 
to oppose its reflux from the heart towards the organs. Applied, as they 
are, tv the walls of the veins by their concave face during the regular and 
normal circulation, they are disposed as a transverse valve to sustain the 
column of blood when any strain or pressure gives that column a retrograde 
movement. 

Srructure—The walls of the veins are thin, semi-transparent, and 
elastic, and collapse when the vessels are empty. Like the arteries, they 
have three tunics. 

The internal tunic is composed of an epithelial layer of elongated cells, 
lying on an elastic membrane made up of longitudinal fibres. In the small 
veins, besides the epithelium and elastic fibres, are striped layers with 
elongated nuclei. This tunic is the most important; it is persistent, while 
the other two may be absent in certain veins. 

The middle tunic is much thinner than that of arteries, and has fewer 
muscular and elastic fibres, while its tint is rather red than yellow. 
The proportion of smocth fibres, disposed in a circular manner in the 
midst of the connective tissue, varies with the volume and situation of 
the veins; being more considerable in the small than the large vessels, 
and also in those through which the blood circulates with difficulty. 

The external, or adventitious tunic, is formed by connective tissue and 
some longitudinal fasciculi of elastic and muscular fibres. 

In the veins of the bones, and in the sinuses of the dura mater, the two 
latter tunics may be absent, and the walls of the vessels only consist of 
epithelium. 

The veins have very numerous vasa vasorum, which form a complete 
network around them. The vena porte alone is accompanied by nervous 
filaments of the great sympathetic. 

(As remarked, the superficial veins are generally unaccompanied by 
arteries; they usually pass between layers of superficial fascia, and at the 
most convenient situations—generally those best protected—pass through 
the underlying fascia to terminate in the deep veins. These are most 
frequently accompanied by arteries, being often inclosed in the same sheath 
with them, particularly in the extremities. With a large number of arteries 
there are two veins, one on each side, the venee comites, though the largest 
arteries have only one venous trunk. The large and frequently repeated 
communications are undoubtedly intended to compensate for the thinness of 
their parietes, which exposes to obstruction and dilatation; this they cannot 
overcome. because of the slowness with which the blood passes through 
them. The valves are accessory to these inosculations ; upon the cardiac 
face of each valve the vein is expanded into two sinuses, which correspond 
with the extent of the valve; these pouches give the distended vessel its 


THE CARDIAC OR CORONARY VEINS. 599 


nodulated appearance. Remak found longitudinal muscular fibres in 
the adventitia of the large veins of the Ox and Sheep, but chiefly in the 
hepatic portion of the posterior vena cava and the veius of the liver.) 


INJECTION OF THE VEINS.—To render the dissection and study of the veins more eas 
tley ought to be filled with tallow or any other solidifiable srintlon, like the arteries. But 
to attain this result the same mode of proccdure cannot be employed as for them, 
Instead of causing the injecting material to flow from the trunk into the branches, it is 
necessary to propel it from the branches towards the trunk, because of the presence of 
the valves; this is to be done by successively fixing the canula into several venous 
branches. 

Four injections generally suffice to fill the whole venous system in a satisfactory 
manner. ‘The first is made from the alveolar vein, beneath the masseter muscle; the 
second from a digital vein of one or both anterior limbs, or from the side of the foot, 
after having destroyed bya stylet the few valves which are sometimes found towards the 
point of union in this vein; or from the side of the heart. The third, from the posterior 
digital veins, in the same way; the fourth, by an intestinal vein. If any important veins 
are oe after these four injections, a case of frequent occurence, they can be directly 
injected. 


CHAPTER II. 
VEINS OF THE LESSER CIRCULATION, OR PULMONARY VEINS. 


Tue pulmonary veins comport themselves in the same manner as the 
corresponding arteries. They are lodged in the substance of the lung (com- 
mencing in the capillaries, upon the walls of the intercellular spaces and air- 
cells, joining to form a single trunk for each lobe), and collect in from four 
to eight trunks, which open into the roof of the left auricle, after emerging 
from the pulmonary organ immediately above the origin of the bronchi. 
As they are destitute of valves, they readily allow the blood to flow towards 
their roots. It is they which carry to the left heart the fluid thrown into 
the lung by the right ventricle, to be submitted to the revivifying influence 
of the atmosphere. 


CHAPTER III. 
VEINS OF THE GENERAL OR SYSTEMIC CIRCULATION. 


TuxsE vessels bring to the right auricle the blood which has been dispersed 
in the texture of organs, by the ramifications of the great arterial tree. 

They open into the auricle by forming three groups: the group of 
coronary or cardiac veins ; the anterior vena cava, and the posterior vena cava, 


Arrrone I.—Carprac on Coronary VEINS. 


There are several small, and one large or great coronary vein, 

Suatt Carprac Verns.—These are the almost insignificant vessels, un- 
determined in number, which come from the walls of the right ventricle and 
open directly into the corresponding auricle at the coronary groove. 
(Among these may be included the debatable venze Thebesit, a, multitude of 
minute venules said to arise in the structure of the heart and open directly 
i i vities. 
ae as Vu (Figs. 258, 5; 259, 0, p).—This vein is formed 
by two roots: one is lodged in the right ventricular groove, and accompanies 


600 THE VEINS. 


the cardiac artery of the same side; the other follows at first the left 
ventricular groove, ascends nearly to the pulmonary artery, and is then 
inflected backwards by placing itself in the coronary groove, along with the 
horizontal branch of the left cardiac artery. Turning round the base of the 
posterior ventricle, it joins the right root, near the upper extremity of its 
groove. The common trunk resuliing from this junction. after a short course, 
opens into the right auricle, below and within the embouchure of the posterior 
vena cava. 

In their track, the two branches of the coronary vein receive branches 
which escape from the auricular and ventricular walls. ; 

The bronchial veins, ramifying on the bronchi like the arteries, whose 
satellites they are, also open into the great coronary vein, very near its 
embouchure, after becoming a single vessel, which is sometimes thrown 
directly into the auricular cavity. 


Anticir IJ.—Anrerton Vena Cava. (Figs. 258, r; 259, d; 293.) 


This is a voluminous trunk, which ought to be considered as the corres- 
ponding vein of the anterior aorta. It extends from the entrance of the 
chest to the right auricle, into the roof of whichit is inserted. It is com- 
prised between the two layers of the anterior mediastinum, and lies 
below the trachea, to the right of the anterior aorta. 

Four large vessels—the two jugular and two aaillary vens—opening in 
common in the space comprised between the two first ribs, constitute the 
roots of this vessel. 

CottareraL AFFLUENTS.—The affluent vessels which the anterior vena 
cava receives in its course are: the internal thoracic, vertebral, superior 
cervical, and dorsal veins, and the great vena azygos. 

Internat THoracio (on InrerNAL Mammary) Veins—A satellite of the 
artery of the same name, this vein opens into the anterior vena cava, at its 
origin (Fig. 293). 

VERTEBRAL VuIN.—It accompanies the corresponding artery in the canal 
formed by the foramina in the transverse processes of the cervical vertebra, 
and joins the vena cava at the origin of that artery (Fig. 293). 

Surerion CrrvicAL VrEIn.—Exactly resembles the artery whose name 
it bears. 

Dorsat Vein.—This vessel follows the dorso-muscular artery, and, like 
it, presents a subcostal branch. On the left side, this branch is designated 
the small vena azygos, and is often prolonged to the eleventh or twelfth rib; 
it receives the intercostal veins of the spaces it crosses. 

It may be remarked that the vertebral, superior cervical, and dorsal 
veins of the right side, are nearly always thrown separately into the vena 
cava, while on the left side they constantly unite to form a single trunk 
(Figs. 258, wu; 293). 

Grear Vena Azycos (Figs. 258, «; 259, e; 293).—This is a long 
single vein, which commences at the first lumbar vertebra, and extends 
forward on the right of the thoracic aorta, beneath the bodies of the dorsal 
vertebre to about the sixth, when it is inflected downward to terminate in 
the anterior vena cava, near the embouchure of that vessel, or even directly 
into the right auricle. ° 

In its course, the great vena azygos is maintained against the bodies 
of the dorsal vertebree by means of the parietal pleura; it runs along- 
side the outer border of the thoracic duct, which senarates it from the 


THE ANTERIOR VENA CAVA, 601 


aorta! The terminal extremity of its inflection crosses the esophagus and 
trachea to the right, and is included between these two tubes on the one 
side, and the right layer of the mediastinum on the other. 

Its roots are some branches emerging from the spinal and psoas muscles, 
and which are not usually in direct communication with the posterior vena 
cava, as in Man and the other animals. , 

During its progress, it receives the first lumbar and the satellite veins 
of all the aortic intercostal arteries, right and left. But when the small 
vena azygos is prolonged backwards beyond the posterior extremity of the 
subcostal artery, that vessel, as we have already seen, forms the confluent of 
a certain number of left posterior intercostals 


JUGULAR VEINS, 


The jugular is a satellite vein of the carotid artery. 

Origin.—It commences behind the inferior maxilla, below the articula- 
tion of the jaw, by two large roots: the superficial temporal trunk and the 
internal maxillary vein, which correspond to the two terminal branches of 
the external carotid artery (Fig. 290). 

Situation—Direction.—This vessel passes downward and backward, 
lodged at first in the substance of the parotid gland, afterwards in the 
muscular interstice designated the jugular channel, and which is comprised 
between the adjacent borders of the levator humeri (mastoido-humeralis) and 
sterno-maxillaris: muscles. Reaching the inferior extremity of the neck, it 
terminates in the following manner (Fig. 290): 

Termination.—On arriving near the entrance to the chest, the two 
jugulars unite in forming a vessel named the confluent of the jugulars. This 
confluent, into the sides of which open the two axillary veins, is comprised 
between the two first ribs, and situated below the trachea, in the middle of the 
lymphatic glands at the opening of the chest. Fixed by fibrous bands to the 
neighbouring parts, and particularly to the two first ribs, the walls of the 
jugular confluent do not collapse when the venous system is in a state of 
vacuity : an anatomical peculiarity which it is necessary to understand, in 
order to explain the manner in which air obtains an entrance into the circu- 
latory system when the jugular or axillary veins are opened, as well as 
affording an indication how to prevent this serious accident. 

Relations. At its upper extremity, the jugular vein is surrounded by the 
parotideal tissue. For the remainder of its extent, it is covered externally 
by the subcutaneous muscle of the neck, and by the branches of the cervical 
plexus which creep on the external surface of that muscle. Inwardly, 
its relations vary as we consider its situation, above or below: above, it 
responds to the subscapulo-hyoideus muscle, which separates it from the 
common carotid, and its satellite nerves; in its inferior moiety, it is in 
direct relation with that vessel, which is above it,as well as with the trachea, 
and even, though only on the left side, with the esophagus. 

ContareraL AFFLUENT VesseLs.—The collateral veins which go to the 
jugular from its origin to its termination, are: 1, Mazillo-muscular veins 
2, Posterior auricular vein ; 8, Occipital vein ; 4, External maxillary, or glosso- 
facial vein; 5, Thyroid vein; 6, Cephalic vein; 7, Parotideal and innominate 
muscular branches. 

A. Maxito-muscunar Veins.—Two in number, corresponding to the 


1 Sometimes the azygos is situated between the aorta and the thoracic duct. When 
the latter lies to the left side, it is in direct contact with the posterior actita. 


602 THE VEINS. 


branches of the artery of the same name, and entering the jugular close to 
its origin, either separately, or after forming a common trunk (Fig. 290). 

B. Posrerror Auricutar Vetn.—A voluminous vessel which commences 
on the concha, and descends on the external face of the parotid gland, near 
its posterior border, where it is joined by numerous divisions from the 
parotid lobules. It opens into the jugular vein, generally a little below, and 
opposite to, the maxillo-muscular vessels, though it is sometimes lower, and 
even beyond the occipital vein (Fig. 290). 

C. Occrrirat Vern.—The occipital vein corresponds, in every respect, to 
its fellow artery. It offers two roots: an anterior, which originates at the 
posterior extremity of the subsphenoidal confluent ; and a posterior, com- 
mencing beneath the transverse process. of the atlas, and formed by three 
principal branches. 

Among the branches of the latter root, one passes with the retrograde 
artery through the posterior foramen of the atlas, and constitutes, as 
it were, the origin of the vertebral vein ; the second communicates with the 
occipito-atloid sinuses, by traversing the atlas near its middle; the third, 
satellite of the cerebro-spinal artery, comes also from these sinuses, and 
receives the venules which accompany the ramifications of the occipito- 
muscular artery. 

D. Extrernat Maxituary or Guosso-racraL Vetn.—aA satellite of the 
artery of the same name, this vessel begins on the forehead by two roots: a 
superior and inferior, analogous in every point to the terminal branches of 
the artery. It descends along the anterior border of the masseter muscle, 
gains the maxillary fissure, into which it is inflected, placing itself between 
the artery and Stenon’s duct; then proceeds backwards and downwards 
on the internal pterygoid muscle, always accompanied by the glosso-facial 
artery until near the anterior extremity of the maxillary gland, when 
it leaves it to follow the inferior border of that gland, and enters the jugular, 
after crossing the sterno-maxillaris muscle outwardiy, and forming with the 


latter vein an angle which is occupied by the inferior extremity of the parotid ---- 


gland (Fig. 290). 

Branches of origin,—Of the two branches which, by their union, constitute 
the origin of the external maxillary vein, the inferior, a satellite of 
the nasal branch of the corresponding artery, possesses no interest. The 
superior, or angular vein of the eye, merits particular notice, as venesection is 
sometimes practised on it. It arises near the nasal angle of the eye, 
and creeps to the external face of the elevator muscle of the upper lip, below 
the lachrymal muscle. 

Collateral branches.—In its progress, the external maxillary vein 
receives a great number of affluents, the principal of which are the alveolar 
vein, the labial or coronary veins, the buccal vein, and the sublingual vein. 

a, Alveolar vein--‘This is a considerable vessel lodged beneath the 
masseter, and lying against the great supermaxillary bone, between the zygo- 
matic crest and the line of the molar teeth (Fig. 291), 

The disposition of this vessel is most singular; its anterior cxtremity 
opens into the external maxillary vein, and its posterior extremity traverses 
the ocular sheath, receives the ophthalmic veins, and passes, with the 
ophthalmic nerve of the fifth pair, into one of the supra-sphenoidal canals, to 
open into the cavernous sinus in the interior of the cranium.} 


} We have also seen it send into the subsphenoidal canal, to the the inner side of 
the internal maxillary artery, a lender branch that joined the anterior extremity of 
the subsphenoidal confluent. But we cannot say that this disposition is constant. 


THE ANTERIOR VENA CAVA. 603. 


_ Before traversing the ocular sh-ath, and towards the maxillary hiatus, 
this vein receives the superior dental and the confluent of the nasal veins : 
vessels which emerge from the bony orifices traversed by the arteries of the 
same name—that is, the maxilloental canal and the nasal foramen. It also 
receives the confluent of the palatine veins, which pass by the palatine groove, 
instead of coursing along the palatine canal with the corresponding artery. 
In general, these three branches do not join the alveolar separately, but 
rather by a common trunk. | 

The alveolar vein does not present a uniform volume. It increases from 
before to behind to the maxillary protuberance, where it forms a kind 
of large reservoir; but in traversing the ocular sheath it suddenly becomes 
constricted, and maintains a small diameter until its entrance into the 
cavernous sinus. 

This vein may be considered as an affluent of the sinuses of the dura 
mater, as well as of the external maxillary vein. 

b. Labial or coronary veins.—Satellites of the labial arteries. The 
superior is often rudimentary. The inferior, always voluminous, is 
constituted by the union of several anastomotic branches lying against the 
external face of the mucous membrane of the cheek. 

ce. Buccal vein.—Among the affluents of the external maxillary vein, 
we cite this, because it opens into the latter by its anterior extremity, 
opposite the inferior coronary vein, with which it sometimes communicates 
by a particular branch. But the buccal vein, properly speaking, con- 
stitutes the root of the internal maxillary, and we will describe it as such. 

d. Sublingual vetn.—A large vessel, formed of two branches, which arise 
in the substance of the tongue, and are sometimes thrown separately into the 
internal maxillary vein. This sublingual vein passes through the mylo- 
hyoideus muscle, from within to without, and joins the principal vessel at 
the lymphatic glands lodged in the intermaxillary space. 

E. Tayrow Vxrn.—This is a voluminous trunk, resulting from the 
union of the venous divisions which accompany the laryngeal aud thyroid 
branches of the thyroid or thyro-largyngeal artery. It joins the jugular 
beside the external maxillary vein, and must frequently above it. 

F. Cepruanic on Prat Vern.—A superficial vessel, which represents 
one of the terminal branches of the principal -subcutaneous vein of 
the fore-arm. It is lodged in the interstice of the levator humeri and 
small pectoral muscles, and enters the inferior extremity of the jugular 
vein (Fig. 293). 

G. Inyominats Vetns.—A certain number come from the parotid 
gland, but the principal arise in the muscles of the neck and withers. One 
of the latter accompanies the superior branch of the cervico-muscular 
artery. 


ROOTS OF THE JUGULAR VEIN. 


These are constituted by the superficial temporal and internal maxillary 
veins, which are chiefly fed by the sinuses of the encephalic dura mater. 


1. Superficial Temporal Vein. 


Corresponding in the most exact manner to the temporal trunk, this 
vessel is lodged behind the posterior border of the maxilla, near the articula- 
tion of the jaw, beneath the parotid gland, and is, as 14 were, incrusted in 
its tissue. 


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THE ANTERIOR VENA CAV4, 605 


internal maxillary artery. This vein issues from the parieto-temporal 
conduit, behind the supercondyloid eminence; it receives one or two 
branches which escape from this conduit by the foramina in the temporal 
fossa, crosses the temporal muscle, and is charged with venules which arise 
in the interior of that muscle, as well as in the textures of the external ear. 

2. The subzygomatic vein, a satellite of the homonymous artery, and 
like it, divided into two branches: one accompanying the transverse artery 
of the face, the other the masseteric artery. The latter branch com- 
municates by its inferior extremity with the external maxillo-muscular vein; 
it joins, by its other extremity, an enormous branch which comes from the 
temporal muscle, and which passes into the corono-condyloid notch, after being 
largely anastomosed with the deep temporal branches of the internal 
maxillary vein. 


2. Internal Macxillary Vein. 


Remarkable for its enormous volume, this vein creeps between the internal 
masseter muscle and the maxilla, in an oblique direction upwards and 
backwerds. Arriving within the articulation of the jaw, a little below the 
maxillary condyle and the external pterygoid muscle, it joins the temporal 
trunk after being slightly inflected downwards. It, therefore, runs its course 
at a certain distance from the corresponding artery (Fig. 290). 

The internal maxillary has for its root the buccal vein, which it succeeds 
near the superior extremity of the alveolo-labialis muscle. 

Satellite of the artery and nerve of the same name, this buccal vein, re- 
markable for its volume, is situated beneath the masseter muscle, near the 
inferior border of the alveo-labialis muscle; by its anterior extremity it 
communicates directly with the internal maxillary vein, nearly opposite to 
the embouchure of the inferior coronary vein; its posterior extremity is 
continued directly with the internal maxillary. The collateral branches 
it receives in its course come from the masseter muscle and the parietes of 
the cheek. 

On its way it receives a great number of affluents.; these are: 

1. A large lingual vein, accompanying the small hypoglossal nerve. 

2. The inferior dental vein. 

8. The trunk of the deep temporal veins, a large vessel situated in front 
and to the inside of the temporo-maxillary articulation, where it com- 
municates with the masseteric. This vessel arises in the texture of the 
temporal muscle, but particularly in the parieto-temporal confluent, with 
which it joins by the foramina in the temporal fossa. 

4, The pterygoid veins (Fig. 291), numerous branches, only a portion of 
which come from the pterygoid muscles. The others, springing from the 
subsphenoidal confluent of the sinuses of the dura mater, form, on the 
superficial face of the external pterygoid muscle, a wide-meshed network 
which communicates posteriorly with the temporal trunk, and anteriorly 
with the confluent of the deep temporal veins. But as these two vessels are 
bound together, outside the temporo-maxillary articulation, by means of the 
masseteric artery, it results that this articulation is enlaced on every side 
by one of the richest venous plexuses in the whole economy. 


3. Sinuses of the Dura Mater. 


We will here describe not only the sinuses of the encephalic dura mater 
which supply the roots of the jugular vein, but also those of the spinal dura 


606 THE VEINS. 


mater, although these empty themselves into other veins; in order that we 
may be able to consider, in their entirety, all the vessels of the nervous 
centres which carry dark blood. 

Tar Sinuses oF THE Dura Mater in Generat.—These are vascular 
spaces comprised in the texture of the external meninge, or situated between 
that membrane and the bones which form the walls of the cerebro-spinal 
sheath, or even excavated on the inner surface of these bones. ‘lhese spaces 
differ more particularly from the veins, by their being generally of a prismatic 
form, by being continually open, by the absence of valves in their interior, 
and the presence, in some of them, of lamelle (trabecule), or intersecting 
filaments (chorde Willisii) which stud their inner surface, and make them 
look reticulated. 

Their walls are reduced to an epithelial layer that lies either on the dura 
mater, or on the osseous tissue. 

It is into these sinuses that the veins of the encephalon and the spinal 
cord disgorge themselves. 

Tue Sinuses or tae Crantan Dura Mater in Particutar.—Four 
principal will be described: the sinus of ihe fala cerebri or median sinus, 
the two cavernous or sphenotdal sinuses, and the group of occipito-atloid 
sinuses. 

1. Srnus or THe Faux Crresrr, on Mepian Sinvs.—Channeled in the 
substance of the falx cerebri, and becoming wider as it extends backwards, 
this sinus commences near the crista galli, and terminates on the internal 
pirietal protuberance by bifurca ting. The two branches resulting from this 
division form the origin of the parieto-temporal confluent, or winepress of 
Heérophilus (torcular Herophilt). 

2. CAVERNOUS OR SUPRA-SPHEN OIDAL SinusEs.—These are two in number— 
aright anda left. ‘They occupy, on the internal face of the sphenoid bone, 
at each side of the sella turcica, the so-called cavernous fissures. Bordered 
outwardly by the superior maxillary nerve, they receive at their anterior ex- 
tremity the insertion of the alveolar vein. Posteriorly, they join each other, 
and in doing so form a kind of arch, open in front, around the pituitary 
gland. Hach opens widely at the lacerated foramen, into the subsphenoidal 
confluent. 

3. Occrprto-attom Sinuses.—By this name is designated a network of 
large irregular veins, situated beneath the external face of the dura mater, 
on the sides of the occipital foramen, and on the entire internal surface 
of the atloidean ring. Anteriorly, these venous reservoirs communicate, 
through the condyloid foramen, with the posterior extremity of the sub- 
sphenoidal confluent. Posteriorly they are continuous with the spinal 
sinuses, of which we may consider them to be the origin. 

4. Ruptmeytary Sinuses or tHE Crantan Dura Marsr.—Independently 
of the above-described reservoirs, there exist, on the inner wall of the 
cranium, some rudimentary venous sinuses which should be indicated ; these 
are: 1, One or two veins lodged in the structure of the tentorium, designated 
the petrosal or transverse sinuses, communicating, below, with the cavernous 
sinuses, and entering, above, into the parieto-temporal confluent ; ! 2, Some 
small, irregular, and reticulated cavities, very variable in their disposition. 
situated beneath the dura mater, on the sides of the cerebellar cavity, and 
which generally empty themselves into the subsphenoidal confluent, by 


‘ More frequently, perhaps, these veins arise directly from the substance of th i 
and do not communicate, below, with the cavernous sinuses sa 


. 


607 


In some instances, an inferior 


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these cavit 


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THE ANTERIOR VENA CAVA. 
traversing the posterior part of the lacerated foramen, and also opening some- 


times into the petrosal sinus 
tatives of the lateral sinuses in Man 


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163 ‘S14 


608 THE VEINS. 


median sinus, channeled near the free border of the face of the brain, passes 
behind into the torcular Herophili. : : 

Tae Srrvat Sinvusus iv Particunar.—We thus designate in Veterinary 
Anatomy, and with good reason, two series of venous reservoirs which are 
found throughout the whole extent of the vertebral column, on the sides of 
the roof of the spinal canal. Lodged in the lateral depressions of the 
superior face of the vertebral bodies, at the side of the common superior 
vertebral ligament, and covered by the dura mater, these reservoirs, 
continued from one vertebra to the other, are like two large, irregular, 
parallel veins, which commence at the atlo-axoid articulation, terminate 
on the first coccygeal vertebre, where their presence is yet well defined, 
and communicate with one another during their course by transversal 
anastomoses. 

A¥FLuENT VEINS THAT OPEN INTO THE SINUSES oF THE Dura Marer.— 
These are the vessels which carry blood either from the dura mater itself, 
or from the substance of the nervous centres: those of the first category are 
rare, but the second are numerous. Although we are unwilling to make a 
detailed study of the latter, we must nevertheless notice what is most 
remarkable in their disposition. 

a. On the encephalon, the veins form a much richer and closer network 
than that of the arterial ramifications; from this network proceed a 
certain number of principal branches, which throw themselves into the 
sinuses of the cranial dura mater. The veins of the cerebrum, for the most 
part, gain the median and transverse sinuses; a few only pass into the 
cavernous sinuses. Those of the isthmus and cerebellum go to the petrosal 
and occipito-atloid sinuses. 

With regard to the internal veins of the brain—those which, by their 
interlacing, constitute the choroid plexus—we sec them unite into a large 
trunk—the great vein of the brain, or vena Galeni, which bends round the 
superior extremity of the corpus callosum, reaches the interlobular fissure, 
and throws itself into the falciform or middle sinus, near its posterior 
extremity, after receiving the superficial veins from the inner face of the 
hemispheres. 

b. The venules arising from the spinal cord are also very remarkable for 
the fine network they form on the surface of the organ. They collect into a 
common trunk—the median spinal vein, which runs from before to behind, 
throughout the whole extent of the superior groove in the spinal cord; thus 
oceupying an analogous, though opposite, position to that of the artery of 
thesame name. From this vein escape, at intervals, emergent branches which 
open into the spinal reservoirs. 

Erriugent Canats or tae Dura Maver Stnvuses.—We have to notice, 
under this designation, the veins which transport the blood from the sinuses, 
and we will consider in succession those which commence at the encephalic 
reservoirs, as well as those that emerge from the interspinal canals. 

_ 4 To be carried from the encephalic sinuses, the blood flows into two 
kinds of double gulfs, known as the parieto-temporal and subsphenoidal 
confluents. 

The parieto-temporal confluents are lodged in the canals of the same name, 
along with the mastoid artery. Each commences at the base of the internal 
parietal protuberance, and terminates behind the supercondyloid eminence. 
The median and transverse sinuses are confounded with the superior 
extremity of these reservoirs, and empty into them the blood coming from 
the encephalic mass. This fluid is subsequently taken away by the super- 


THE ANTERIOR VENA CAVA. 609 


ficial and deep temporal veins, which have their principal roots in these 
confluents. 

The subsphencidal confluénts extend on the sides of the body of the 
sphenoid bone and the basilar process, from the base of the subsphenoidal 
process to the condyloid fossa, by concurring in the obturation or closing 
of the occipito-spheno-temporal hiatus. They open at their middle portion 
into the corresponding cavernous sinus, by an oval aperture which the in- 
ternal carotid artery traverses in penetrating into the cranium. The anterior 
extremity terminates in a cul-de-sac. Posteriorly, they communicate through 
the condyloid foramina with the occipito-atloid sinuses. The vessels which 
carry off the blood from these confluents are the pterygoid veins, and the 
anterior root of the occipital vein. We already know that the posterior 
branch of the latter vessel removes the blood directly into the occipito-atloid 
sinuses. 

b. The emergent veins of the spinal sinuses present a more simple dis- 
position. At each intervertebral space arise several branches, which more 
particularly make their exit by the intervertebral foramina to join the 
neighbouring veins; in the cervical region, the vertebral veins serve as a 
receptacle in this way for the venous branches emanating from the spinal 
sinuses ; in the dormak region, it is the spinal branches of the intercostals ; 
in the loins, the ‘analogous branches of the lumbar veins; and in the sacral 
region, the lateral sacral vein. 


AXILLARY VEINS, 


A general confluent of all the veins of the thoracic limb, and of some 
from the trunk, the axillary vein commences beneath the scapulo-humeral 
articulation, towards the terminal extremity of the corresponding arterial 
trunk, accompanying the latter to the entrance of the chest, and joining the 
confluent of the jugulars to constitute, with these two vessels, the inferior 
vena cava (293, 18). 

In studying, from their origin to their termination, the numerous 
branches which concur in the formation of this venous trunk, we re- 
cognise : 

1. That they form in the foot a very rich network, from which proceed 
the digital veins, satellite vessels of the homonymous arteries. 

2. That to these digital veins, which are united in an arch above the 
large sesamoids, succeed three metacarpal branches or collaterals of the 
cannon: two superficials, placed on each side of the flexor tendons, and a 
profound (or deep) vein, situated underneath the suspensory ligament, along 
with the interosseous arteries. ; ; 

3. That the metacarpal veins also open into each other, in the superior 
and posterior region of the carpus, to form, on again separating, two groups 
of antibrachial veins : one group comprising the ulnar and the posterior or 
internal radials, which accompany the arteries of the same name ; the other, 
constituted-by a single subcutaneous branch, the median vein, which receives 
at its superior extremity the anterior superficial radial vein. : ; 

4. That at the ulnar articulation, these two groups of antibrachial veins 
join the satellite vessel of the anterior radial artery, and communicate by a 
very complicated system of anastomoses, from which results a principal 
trunk, the humeral vein. . 

5. That the humeral vein, after receiving on its course several muscular 


610 THE VEINS. 


branches .and the subcutaneous thoracic vein, unites near the shoulder-joint 
with the subscapular trunk, to form the axillary vein, ; 
We will study all these branches in’ the inverse order of their 


enumeration, 
1. Subscapular Vein. 


A very considerable vessel, whose disposition resembles that of the 
subscapular artery, though presenting some special peculiarities whose 
study does not deserve a moment’s delay; for example, it most frequently 
receives the satellite vein of the prehumeral artery. 


2. Humeral Vein. 


Placed behind and within the humeral artery, this vessel commences 
above the articulation of the elbow, being formed at this point by the anasto- 
mosing system of veins from the fore-arm, and terminates below the shoulder- 
joint in opening into the subscapular vein. 

Independently of the subcutaneous thoracic vein, which will be studied 
in a special manner, the humeral vein receives on its way several collateral 
satellites of the branches emanating from the humeral artery. One of these, 
the epicondyloid, is only a continuation of the ulnar vein. 

Very often we find a second humeral vein in the deep region of the arm; 
this is an accessory vessel, parallel to the preceding, and situated opposite 
it in front of the artery. 


8. Subcutaneous Thoracic or Spur Vein. 


This vein, which is important to know, as bleeding is sometimes 
practised from it, commences on the flank and belly by numerous super- 
ficial divisions, which unite in two principal roots, and afterwards become a 
single trunk, placed in the substance, or on the external surface of the 
panniculus carnosus, where it is directed forwards in following the superior 
border of the large pectoral muscle, accompanied by an arterial ramuscule 
and a thick nerve. It insinnates itself beneath the olecranian muscles, 
and finally terminates in the humeral vein by opening into the branch that 
follows the deep muscular artery. 


4, Deep Veins of the Fore-arm. 


A, ANTERIOR Rapiat Vern.—This follows the same track, and affects 
the same variations, as the corresponding artery. 

B. Posrerion Raptat Verns—The posterior radial artery is always 
accompanied, and, as it were, enveloped, by a fasciculus of three or four 
venous branches, which frequently anastomose with each other, and are 
reinforced by collateral branches, among which the interosseous vein must 
be noted. 

These radial branches commence above the carpus, by continuing the 
metacarpal veins. They concur to form the humeral vein, in joining the 
otber antibrachial veins at the inferior extremity of the arm. 

C. Unyar Very.—This vessel is lodged, with the nerve and small artery 
of the same name, in the interstice of the oblique and internal flexors of the 


THE ANTERIOR VENA CAVA, é6ll 


metacarpus. 
vein, 


It has the same origin as the posterior radial veins. Its superior or 
terminal extremity bends forward, close to the trunk of the epicondyloid 
artery, and goes to the inferior extremity of the humeral vein. Frequently 
the ulnar vein is double in the latter portion of its track, and between the 
two branches lies the artery. It always communicates at this point, by 
one or more branches, with the deep muscular vein. , 


A number of muscular and subeutancous branches enter this 


5. Superficial Veins of the Fore-arm. 


Placed outside the fibrous sheath formed by the antibrachial aponeurosis, 
these veins, which are principally two in number, are maintained against 
the external face of that membrane by a thin fascia which separates them 
from the skin. 

A. Mepran, or Internat Suscuranzous Varn (Fig. 293, 31).—This is 
also one of the vessels selected for the operation of phlebotomy. It is the 
continuation of the internal metacarpal vein, ascends from the inner face 
of the carpus to the superior extremity of the fore-arm, by crossing the 
radius in a very oblique manner, and terminates in two very large 
branches, the posterior of which is the basilic vein, and the anterior the 
cephalic vein. 

The basilie vein traverses the sterno-aponeurotic (transverse pectoral) 
muscle, to aid in forming the humeral trunk (Fig. 293, 34). 

The cephalic, or plat vein, crosses the superficial band of the biceps or 
coraco-radial muscle, is lodged in the space comprised between the levator- 
humeri and small pectoral muscles, and afterwards opens into the jugular 
vein (Fig. 293, 35). 

B. Suscuranzous, on ANTERIOR Rapist Vein (Fig. 293, 32).—Less 
considerable than the preceding, this vein arises at the carpal region, in its 
course occupies the anterior face of the fore-arm, and terminates in uniting 
its superior extremity either to the subcutaneous median or the cephalic 
vein; the last is most frequently the case. 


6. Metacarpal Veins. 


Three in number, as we know, these veins are distinguished into in- 
ternal and external collateral of the cannon, and deep or interosseous collateral. 

A. InrernaL CoLLATERAL OF THE Cannon.—More voluminous than tke 
others, this vein passes from the vicinity of the fetlock along the flexor 
tendons, accompanied by the principal artery of the cannon and the 
external plantar nerve, places itself in the special sheath which envelops 
the common trunk of the interosseous artcries to the inside of, and behind 
the carpus, to be continued in the antibrachial region by the median 
subcutaneous vein, after communicating with the other metarcarpal veins 
(Fig. 293, 30). ; ; 

B. ExrernaL CoLnaTeraL or THE Cannon.—Situated opposite the 
preceding—to the external side of the flexor tendons, in company with the 
corresponding plantar nerve—the external collateral of the cannon follows 
that nerve to near the trapezium, and then separates into several reticulated 
branches which anastomose with the internal collateral, from which proceed 
the ulnar and internal or posterior radial veins. 


612 THE VEINS. 


C. Inrerossrous Vern.—A tortuous, irregular, and sometimes multiple 
vessel, lodged with the plantar interosseous arteries between the suspensory 
ligament and the posterior face of the principal metacarpal bone. Reaching 
the superior extremity of that bone, it unites largely to the right and lett 
with the external and internal collaterals, sending upwards one or two small 
branches which traverse the carpal sheath along with the collateral artery 
of the cannon, and open into the posterior radial branches above the knee. 


7. Digital Veins. 


These veins occupy, on the sides of the digital region, the same position 
as the homonymous arteries in front of which they are placed. They arise 
from the network formed on the lateral cartilages by the veins of the foot, 
and terminate in uniting above the fetlock, between the flexor tendons of the 
phalanges and the superior sesamoid ligament, so as to form an arch from 
which proceed the three metacarpal veins (Fig. 298, 37). 


8. Veins of the Foot or Ungual Region. 


The importance of the region to which these vessels belong, requires that 
they should be described more fully than the other veins, and as has been 
already done with the arteries of this part of the body. We will, therefore, 
borrow the exact and minute description given by M. H. Bouley.t 

This venous apparatus may be divided into external and internal or 
intra-osseous. 


a. External Venous, Apparatus. 


“The external venous apparatus of the digital region is very remarkable 
for the number, development, superficial distribution, and reticulated 
disposition of the canals composing it. To give an idea of this, we cannot 
do better than compare its general form to a net whose irregular meshes 
are extended over, and moulded on, the two last phalanges which are contained 
in it. 

“This intricate reticulation of the venous apparatus of the foot is 
marvellously displayed in specimens injected after maceration, and then 
dried. 

“To facilitate its description, we recognise in it three parts distinct by 
their situation, though they only form a continuous one. They are: 

“1. The solar plexus. 

“2, The podophyllous plexus. 

“3, The coronary plexus. 

“A. Soran Purxus.—The veins of the solar plexus are remarkable for 
the equality of their calibre throughout the whole extent of the plantar 
surface, and by the almost absolute absence of anastomotic communications 
with the deep parts. 

“Sustained in a special fibrous web (plantar reticulum), which replaces 
the periosteum at the lower surface of the phalanx, and is a continuation of 
the corium of the villous tissue, these veins appear indeed to have so little 
communication, except with each other, that it is possible to detach the 


plantar reticulum trom the superior face of the third phalanx without 
disturbing them. 


‘*Traité de Organisation du Pied du Cheval,’ p. 65. 


THE ANTERIOR VENA CAVA. 613 


“The general disposition of the venous canals in the texture of the 
reticulum supporting them, closely resembles that of the secondary ribs of 
the limb (or laminar merithal) of certain asymmetrical leaves. In their 
course they follow an irregularly-broken line, intercepting each other by 
joining at short intervals, so as to form unequal-sized, unsymmetric, 
polygonal spaces. 

“ These venous conduits have a double canal for discharging themselves: 
a central, the least considerable and least constant; the other peripheral 
or circumflex, corresponding to the artery of the same name, and whose 
satellite vein it is. 

“Central canal_—The central canal is formed by the simultaneous 
anastomoses of a crowd of venous ramifications converging towards the 
centre of the digit. It is of a parabolic shape, and embraces in the concavity 
of its curvature the point of the pyramidal body, whence it throws its two 
branches in a parallel manner on the sides of that body, into the bottom of 
the lateral lacune as far as the cartilaginous bulbs, where it proceeds 
to the external coronary plexus. This disposition is not constant, however, 
as specimens are frequently met with in which this central canal is replaced 
by multiple veins, which are more considerable than those forming the 
whole of the plexus, and which serve them as overfalls towards the super- 
ficial coronary plexus. 

Circumflex vein, or peripheral venous canal— ‘This vein is of large 
calibre, and formed by divergent ramifications from the solar plexus, as well 
as the descending veins of the podophyllous plexus; it margins the external 
limb of the villous tissue in following a slightly undulous line within the 
circumflex artery, whose satellite it is. It is sometimes broken up, at 
certain points of its course, into several smaller canals which are continuous 
with its trunks. 

“In its circular route, all the divergent solar and descending podo- 
phyllous veins are discharged into it, and it terminates, at the extremities of 
the crescent formed by the third phalanx, in several large branches which 
pass beneath the podophyllous tissue to the lateral cartilage, where they 
concur to form the superficial coronary plexus. 

“B. Popopxyitiovs Venous Prexus or Nerworx.—The veins of the 
podophyllous plexus exhibit a disposition analogous to those of the solar 
plexus; like them, they are sustained in the meshes of a fibrous texture (the 
reticulum processigerum of Bracy Clark, the subpodophyllous reticulum ot 
French Veterinarians) spread on the anterior surface of the bone, in the 
same way as the periosteum is on other bones, and continuous with the 
corium of the laminal tissue. Communicating largely between each other 
by multiple anastomoses, like the solar plexus, they appear to be completely 
isolated from the deeper parts, from which it is commonly believed they 
emanate. 

“Tortuous and split up into branches in their course, the podophyllous 
veins wind ina serpentine manner along the length of the lamin they cover, 
very close to each other, and forming narrow elongated meshes. Their 
confluence is such, that at certain points they appear bound together by their 
external walls. 

“The calibre of these vessels is tolerably uniform throughout the extent 
of the podophyllous plexus, except towards the posterior parts, where their 
principal canals empty themselves into the coronary plexus. 

“The podophyllous veins are in anastomotic communication, below, with 

1 The inferior circumflex artery of the foot. 


42 


614 THE VEINS. 


the circumflex vein of the solar plexus, which they concur to form, and above, 
with the coronary plexus, which is only a continuation of them. 

«“C. Coronary Venous Prexus.—The coronary venous plexus (Fig 
292, 2, 4) is arranged like a 
ramose garland around the second 
phalanx to the origin of the 
third, and on the surface of the 
cartilaginous apparatus which 
completes the latter. 

“It is supported, like the 
other venous networks of the 
digit, by a fibrous texture imme- 
diately subjacent to, and con- 
tinuous with, the corium of the 
coronary substance, and is juxta- 
posed, as well as adherent, to 
the expansion of the extensor 
tendon, the lateral cartilages, 
and to the bulbous enlargements 
of the plantar cushion. 

“This plexus proceeds from 
the intra-osseous, podophyllous, 
and solar networks. To facili- 
tate its description, we recognise 
in it three parts: one central 
and anterior, situated between 
the two cartilaginous plates, and 
two lateral, corresponding to 
these cartilages. 

THE VEINS OF THE FOOT. “CENTRAL Part OF THE 

Coronary PLexus.—The central 

part of the coronary plexus (Fig. 292, 2), immediately subjacent to the 

substance or cushion of that name, constitutes a very close network formed 

by innumerable venous radicles, which rise in a tortuous manner from, 

and are continuations of, the podophyllous plexus, until they reach a 

large anastomotic vein thrown across from one cartilaginous plexus to 

the other, and iuto which they open by ten to twelve principal mouths 
(Fig. 292, 8’). 

“These veins of the central part of the coronary plexus gradually 
increase in calibre, and diminish in number, from the podophyllus plexus, 
where they take their origin, to their superior and terminating canal, which 
itself only appears to be the result of their successive anastomoses. 

“ CaRTILAGINOUS PLExus, on LATERAL Parts of THE CORONARY PLEXUS.— 
The cartilaginous plates serve to support, by their two faces and the 
canaliculi by which they are traversed, a mass of very close, anastomosing, 
and converging veins, which, from its situation, may be designated the 
cartilaginous plexus, 

“This cartilaginous plexus is formed by two layers of vessels—a 
superficial and deep. 

“Superficial cartilaginous layer or plexus—The superficial layer (Fig. 
292, 3, 4), extended over the external surface of the cartilaginous plates and 
bulbs, has its origin by innumerable roots from the veins of that part of the 
podophyllous plexus corresponding to the superficies it occupies. These 


Fig. 292. 


THE ANTERIOR VENA CAVA, 615 


roots, massed in a very dense network, converge towards the supcrior 
portions by diminishing in number and augmenting in volume, and terminate 
in forming themselves, by the aid of successive anastomoses, into ten 
or twelve principal branches which again unite into two considerable 
vessels (Fig. 292, 6), situated at the superior limit of the plexus. Theso 
vessels, finally, by their last fusion at the inferior extremity of the first 
phalanx, constitute the digital vein, the satellite of the artery of the same 
name (Fig. 292, 5). 

_ _ “Considered from below upwards, in a foot previously prepared by 
injection, the digital vein, divided into two branches, subdivides itself 
into secondary branches and ramuscules which diverge and spread over. the 
convex surface of the cartilage and coronary cushion, resembling somewhat 
the disposition of trees trained on espaliers, whose spreading branches are 
fixed to the walls on which they ramity. 

“The two peripheral branches of the superficial cartilaginous plexus 
establish communications with the opposite cartilaginous plexus, in con- 
tracting direct anastomoses with the branches of the plexus which are 
symmetrical to them. 

“The anterior anastomosing canals are double and superposed. 

“The most inferior and superficial is constituted by the large vein (Fig. 
292, 3’) thrown slantingly across from one plexus to the other in the median 
plane, and on the external surface of the extensor tendon; this receives a 
considerable multitude of venous ramuscles, which emerge from the anterior 
part of the podophyllous plexus. 

“This first communicating vein joins the anterior branches of the carti- 
laginous plexus. 

“The second communicating vein, situated three-quarters of an inch above 
the first, and beneath the tendon, is thrown transversely from one anterior 
branch of the plexus to the other. They open into each other on each sido, 
at the same point where the first communicating vein enters. 

“Sinuous in the whole of its track, sometimes double, and sometimes 
formed of several confluent veins, as in Fig. 292, this anastomosing canal 
serves as an outlet for several deep veins. 

“The anastomosis between the posterior peripheral branches of the 
cartilaginous plexus is formed by an irregularly curved and long vein of 
large calibre, sinuous or broken in its course, but always considerably 
longer than the distance from the two cartilaginous plates between which it 
is extended. 

“This posterior communicating vein acts as a confluent to the canals 
emerging from the cartilaginous bulbs, and to the posterior part of the solar 
plexus, which throws into it five or six well-developed afferent veins. ‘ 

“ Deep cartilaginous layer or plexus. —The deep layer of the carti- 
laginous plexus is formed : ; 

“1, By somewhat large ascending branches from the posterior part of the 
podophyllous and solar plexuses. ; 

“9, By the deep internal venous apparatus of the third phalanx. 

“3, By the deep veins arising from the coronary bone and the liga- 
ments and tendons surrounding it. . ; 

“ The ascending branches of the podophyllous tissue are introduced by 
the numerous foramina which traverse the base of the cartilaginous plate 
and the inferior fibrous covering of the plantar cushion; they follow the canals 
which continue those foramina in the substance of the cartilage, and reach 
its internal face, along with the branches proceeding from the intra-osseous 


616 THE VEINS. 


venous system and those coming from the tendons aud ligaments, forming a 
fasciculus of five or six thick converging veins which unite in two large 
ascending branches. These anastomose with each other before their de- 
finitive junction with the two peripheral branches resulting from the super- 
ficial cartilaginous plexus, with which they concur in constituting the 


digital vein.” 


b. Internal, or Intra-osseous Venous Apparatus. 


“Girard, the younger, and Rigot have denied that the plantar artery had, 
in the interior of the phalanx, a satellite venous system. These two able 
anatomists committed an error. ; 

“The disposition of the venous apparatus in the interior of the phalanx 
is absolutely identical with that of the arterial. 

“The satellite radicular venules of the terminal arteries converge, by 
forming successive anastomoses, towards the semilunar sinus, into which 
they enter by the anterior interosseous canals, ascending and descending, and 
by which the emergent arteries from the semilunar anastomosis pass out- 
wards. There they join into a semicircular canal, the satellite of that 
anastomosis, which is continued backwards by two efferent veins that follow 
the posterior canals of the semilunar sinus, emerge by the plantar foramina, 
pass into the fissure of the same name, ascend within the basilar process, 
lie at the internal face of the cartilaginous plate, in one of the infractuosities 
with which it is sculptured, and concur in the formation of the deep layer 
of the cartilaginous plexus. 

“ Beside these veins converging towards the cartilaginous plexus, there is 
a small number of divergent ones which follow the track of the arteries, and 
pass into tho podophylous plexus through the anterior porosities of the 
phalanx. 

“ The dissection of specimens injected by the veins puts this arrangement 
of the venous apparatus in the interior of the os pedis beyond a doubt. 

“ But is this internal venous system limited to the group of vessels which 
are satellites of the arteries, or is it not rather extended over a vaster 
surface, and may not all the areole of the spongy tissue of the bone be 
considered as a dependency of it? 

“This way of viewing it would seem to be supported by the result of 
certain injections, in which the material introduced by the neighbouring 
veins has filled all the internal spongiole of the bony tissue; though this 
was probably due to an accident in the operation, and it is presumable that 
the direct passage of the venous injection into the areole of the spongy 
tissue arose from a rupture in the vascular walls. If the tissue of the 
phalanx formed a kind of diverticulum for the venous system, as the opinion 
just given would admit, operations performed on this part during life, when 
the texture of the bone is deeply involved, ought to be followed by he- 
morrhage from the open orifices of these aerole—a circumstance which 
does not take place. 

‘It does not appear, therefore, that there is in the structure of the third 
phalanx any departure from the general plan on which bones are constructed, 
and we think that its internal veinous system is limited to the vessels, very 
numerous as they are, which accompany the arterial divisions.” 


THE POSTERIOR VENA CAVA. 617 


Anrtiote ITI.—Posrerion Vena Cava. (Figs. 258, 0; 259, f; 293.) 


This vein, whose volume is not equalled by that of any other vessel in 
the body, commences at the entrance to the pelvis by two large roots, the 
pelvi-crural trunks. 

From this point it is directed forward, beneath the bodies of the lumbar 
vertebra, soon reaches the superior border of the liver, where it leaves the 
lumbar region to lodge itself in the fissure excavated on the anterior face 
of that gland; passing through this, it traverses the aponeurotic centre of 
the diaphragm, and opens into the postero-external part of the right auricle 
of the heart. 

In this course, the posterior vena cava is naturally divided into three 
portions—a sublumbar, hepatic, and thoracic. 

The sublumbar portion, placed to the right of the abdominal aorta and to 
the left of the right kidney and suprarenal capsule, is maintained against 
the common inferior vertebral ligament and the left small psoas muscle by 
the peritoneum and the pancreas. It responds, besides, to the right renal 
artery, which crosses its face perpendicularly, as well as the corresponding 
great splanchnic nerve and the nervous divisions of the right renal and 
lumbo-aortic plexuses. 

In its hepatic portion, the posterior vena cava is only related to the liver 
and diaphragm, which form a complete canal around it. 

The thoracic portion is lodged between the right lung and its internal 
accessory lobule, and enveloped by a particular serous fold—a dependency 
from the right pleura, and which has been already described (page 465). 

Collateral afferents ——Those vessels which, as considerable as they are 
numerous, open into the posterior vena cava, are, enumerating them from 
before to behind : 

1. The diaphragmatic veins. 

2. The vena porte, a trunk into which are collected the majority of the 
visceral abdominal veins, and which, instead of opening directly into the 
vena cava, is divided in the liver like an artery, reconstituting itself 
into a certain number of thick branches—the suprahepatic vessels, which 
enter the vena cava on its way through the anterior fissure of the liver. 

3. Renal veins. 

4. Spermatic veins. 

5. Lumbar veins. « 

All these vessels will be studied, in the order above indicated, before the 
roots or pelvi-crural trunks of the vena cava. 


DIAPHRAGMATIO VEINS. 


These are two, sometimes three, enormous vessels lodged in the texture of 
the aponeurotic centre, commencing by several branches in the fleshy portion 
of the muscle, and entering the vena cava at the moment when it traverses 
the diaphragm. 


VENA PoRTa. (Figs. 293; 294.) 


The manner in which this vessel comports itself gives it an altogether 
peculiar physiognomy, and has caused it to be considered as a separate 
vascular system. After what has been already said concerning the structure 
of the liver, it cannot be ignored that the vena porte is distributed in 
that gland exactly like an artery. 


618 THE VEINS. 
Fig. 293, 


By 


GENERAL VIEW OF THE VEINS IN THE HORSE. 


THE POSTERIOR VENA CAVA, 619 


_It begins in the sublumbar region, at the great mesenteric artery, by the 
union of three large roots; it is then directed forwards and a little to the 
right, traversing the pancreatic ring, below the vena cava, and is afterwards 
lodged in the great posterior fissure of the liver, where it ramifies by forming 
the subhepatic veins, whose capillary divisions themselves give rise to the 
suprahepatic vessels, 

Suprahepatic and subhepatic veins (Fig. 219, VP, Vh).—These vessels 
having been already studied in the description of the liver, we need not 
again occupy ourselves with them, but refer only toa peculiarity incompletely 
noticed in that description, with reference to the suprahepatic veins. 

We know that these vessels are divided into two categories, according to 
the arrangement of their,openings. The majority enter the vena cava in 
forming a single confluent placed at the anterior extremity of the fissure in 
the liver, at the diaphragmatic veins ; the others open separately over the 
whole extent of the hepatic portion of the venous trunk. In carefully 
examining the confluent towards which all the veins of the first group 
converge, we recognise the embouchures of three principal veins, one coming 
from each of the hepatic lobes, and furnished with three very thick, incom- 
plete valves. With regard to the vessels of the second group, M. Claude 
Bernard? considers them to come, for the most part, directly from the sub- 
hepatic veins, and not from the capillary network formed by the arborisation 
of these veins in the lobules of the liver. It is true that injections readily 
penetrate from the vena ports into the vena cava, but they do this quite as 
much by passing along the large suprahepatic vessels as the canals of which 
we now speak; and, besides, if the material forced into the vena porte is 
mixed with some imperfectly-powdered colouring matter, the injection will 
arrive colourless, or but slightly tinged, in the suprahepatic vessels and the 
vena cava. These facts, we see, do not militate in favour of M. Bernard’s 


* Lecons de Phystoloyie Experimentale.’ Paris, 1856, 


Anterior vena cava; 2, 2, Posterior vena cava; 3, Right pelvi-crural trunk, 
divided at the ilio-sacra] articulation; 4, Left pelvi-crural trunk ; 5, Femoral 
vein; 6, Obturator vein; 7, Subsacral vein; 8, Left testicular vein; 9, Puste- 
rior abdominal vein; 10, Renal vein; 11, 11, Ascending branches of the asternal 
vein; 12, Vena azygos, with its intercostal branches, and in front the subdorsal 
venous branch, 13; 14, Csophageal vein; 15, Dorsal, or dorso-muscular vein ; 
16, Cervical, or cervico-muscular vein; 17, Vertebral vein; 18, Right axillary 
vein, cut at the anterior border of the first rib; 19, Substernal, or internal 
mammary vein; 20, Left axillary artery ; 21, Termination of the left cephalic 
vein; 22, Left jugular; 23, Right jugular; 24, External maxillary, or glosso- 
facial vein; 25, Coronary vein; 26, Angular vein of the eye; 27, Subzygomatic 
vein; 28, Posterior auricular vein; 29, Maxillo-muscular vein; 30, Internal 
metacarpal vein; 31, Median subcutaneous vein; 32, Radial subcutaneous vein ; 
33, Posterior radial vein; 34, Basilic vein; 35, Plat, or cephalic vein; 36, 
Coronary venous plexus, 37, Digital vein; 38, Internal metatarsal vein; 39, 
Anterior root of the internal saphena vein; 40, Posterior root of ditto; 41, 
Internal saphena; 42, Great coronary vein; 43, Small mesaraic vein; 44, Dif- 
ferent branches of the great mesaraic vein; 45, Trunk of the vena porte in its 
sublumbar portion, lodged in the pancreas; 46, The same in the posterior fissure 
of the liver; below it is seen entering the substance of the gland.—m, Sub- 
scapular hyoideus muscle cut obliquely in the direction of the trachea; P, Cervical 
panniculus turned down to expose the jugular channel; 0, Right auricle of the 
heart; A, Posterior aorta; G, Section of the right lung; F, Lett lobe of the liver 
behind the section of the diaphragm; R, Right kidney carried up and forward; 
L, Esophagus; v, Bladder; s, Rectum; 1, Thoracic duct; 1’, Termination of 
that duct in the confluent of the jugulars. 


620 


THE VEINS. 


opinion ; and there is every reason to believe that the system of the vena porte 


and that of the vena cava do not communicate, 


THE VENA PORT AND ITS ROOTS; PARTLY 
THEORETICAL, 


1, Trunk of the vena porte; 2, Its origin; 
3, Veins of the small intestine; 4, Ilio- 
cecal vein; 5, External cecal vein; 6, In- 
ternal cecal vein; 7, Great mesaraic vein ; 
8, 9, Colic veins forming the roots of that 
vessel; 10, Collateral vein sometimes con- 
tinuing the left colic, and joining the great 
mesaraic vein near its origin; 11, Com- 
mon confluent of the small mesaraic and 
splenic veins; 12, Small mesaraic vein and 
its collateral branches; 13, Splenic vein ; 
14, Left gastro-epiploic vein; 15, Right 
ditto; 16, Posterior gastric vein.—a, 
Stomach; 6, Duodenum; ec, Small intes- 
tine; d, Caecum; ¢, Large colon; f, Float- 
ing colon; g, Rectum; h, Portion of the 
great omentum; ¢, Spleen; j, Mesentery ; 
hk, Colic mesentery. 


in the adult, otherwise than 
by the capillary network which is 
intermediate to the subhepatic and 
suprahepatic vessels. If any other 
means of communication exist, they 
must be extremely small. 

Constituent vessels of the vena porte. 
—The three roots of this vein are the 
great and small mesenterics and the 
splenic vein. 

The collateral affluents it re- 
ceives on its course are principally 
two: the right gastro-epiploic veins and 
anterior gastric. 

We will make a rapid survey of 
all these vessels. 


1. Roots of the Vena Porte. 


A. Great MxrsenTERIC on AN- 
TeRIoR Mesaraic VEIN (Fig. 293, 
44; 294, 2, 7).—This is an enormous 
venous canal into which flows the 
blood that has passed through the 
walls of the small intestine, ceecum, 
large colon, and the origin of the small 
colon, and whose divisions correspond 
exactly to the different branches fur- 
nished by the great mesenteric 
artery. 

When traced from its opening to 
its origin, in an inverse direction to 
the course of the blood, it is observed 
to lie between the two colic arteries, 
and proceed beyond the fold formed 
by the suprasternal and diaphragmatic 
curvatures, beyond which it divides 
into two satellite branches for the 
colic arteries, which anastomose in 
arcade towards the pelvic curvature, 
like the arteries they accompany. 

It is therefore by the union of two 
colic veins (Fig. 294, 8, 9) that the 
great mesaraic vein is constituted, and 
in whose formation numerous collateral 
affluents concur; among these may be 
noticed the two cecal veins (Fig. 294, 
5, 6), the ilio-ccecal vein (Fig. 294, 4) 
coming from the origin of the floating 
colon, and the veins of the small intes- 
tine: vessels arranged so exactly like 
the corresponding arteries that we may 


dispense with any further description of them. 


THE POSTERIOR VENA CAVA. 621 


B. Suatt Mezsznteric or Posterior Mesaraio VEIn (Figs. 293, 43. 
294, 12).—This vessel commences above the rectum, near the ainiata by 
large hemorrhoidal branches which communicate with the Hemoupatat: 
ramuscles of the internal pudic. It is directed forwards,.between the two 
layers of the second mesentery, along the small mesenteric artery, which it 
passes, and extends to the great mesenteric artery, on the left side of which 
it unites with the splenic vein, before opening into the anterior mesaraic to 
form the vena porte. In its course it receives all the satellite venous 
branches of the divisions of the artery of the same name, and whose 
arrangement is similar to that of the arterial ramifications, ; 

C. Serenic Vein (Fig. 294, 13).—This is an enormous canal which 
follows the splenic artery, and comports itself exactly like it. Itbegins by 
the left gastro-epiploic vein (Fig. 294, 14) anastomosing in arcade with the 
right gastro-epiploic, receiving on its track gastric, splenic, and epiploic 
branches, and joining the small mesaraic after passing above the left ex- 
tremity of the pancreas, and obtaining the posterior gastric vein (Fig. 294, 16). 


2. Collateral Affluents of the Vena Porte. 


A. Ricut Gasrro-epiptoro Vern (Fig. 294, 15).—We already know that 
the hepatic artery, before entering the liver, gives off pancreatic branches, a 
pyloric branch, and a gastro-epiploic division, which in turn detaches a small 
duodenal artery; the vessel described as the right gastro-epiploic vein cor- 
responds, in every respect, to all these collateral ramifications of the hepatic 
artery. 

This vein, then, has its origin from around the great curvature of the 
stomach, but at an undetermined point, as it forms an anastomotic arch with 
the left gastro-epiploic vein. Posteriorly, it crosses the dilatation at the 
origin of the duodenum, receives the pyloric, duodenal, and pancreatic veins, 
and opens into the vena porte after traversing the pancreas. 

B. Ayterior Gastric Vzrn.— Satellite of the homonymous artery, 
this vein joins the vena porte separately, after the entrance of that vessel 
into the great posterior fissure of the liver, and when very near the terminal 
extremity of that fissure. 


RENAL VEINS. 


Two in number, like the arteries they accompany, these veins are dis- 
tinguished by their enormous volume and the tenuity of their walls. The 
left, having to cross the abdominal aorta before entering the vena cava, is 
longer than the right. They receive the majority of the veins from the 
suprarenal capsules (293, 10). 


SPERMATIC VEINS. 


These vessels correspond to the great spermatic arteries of the male, and 
the utero-ovarian arteries of the female. 

Testicular vein.—The radicles which constitute this vein present, at their 
emergence from the superior border of the testicle, a flexiform and very 
complicated arrangement, enlacing, turning, and inflecting themselves in a 
thousand ways around the convolutions of the great spermatic artery, and 
ascending in this manner towards the neck of the vaginal sheath (abdominal 
ring), which they pass through usually after joining to form two trunks. 
These rise towards the sublumbar region, beneath the peritoneum, in a fold 
of which they are at first included; they communicate with one another in 


622 THE VEINS. 


their course by anastomosing branches, and are generally confounded into 4 
single spermatic vein, which opens into the vena cava near the renal vein 
annem vein.—This vein, which is very voluminous, enters the 
vena cava at the same point as the corresponding vessel in the male, and 
proceeds, as its name indicates, from the ovaries and uterus by flexuous and 
reticular branches, whose fusion into a single trunk only takes place near 


the vena cava. 
LUMBAR VEINS. 


Satellites of the arteries of the same name, these vessels enter the vena 
cava separately. The most anterior often open into the vena azygos. 


PELVI-CRURAL TRUNKS OR COMMON ILIAC VEINS. 


These appellations are given to two enormous vessels, into which are col- 
lected all the veins of the abdominal limb and the posterior part of the 
trunk—very short vessels, which, by their junction, form the posterior vena 
cava (Fig. 293, 3, 4). 

The common iliac vein is lodged in the angle of separation comprised 
between the external and internal iliac arteries, and is a continuation of 
the two satellite veins of these arterial canals. The right, shorter than the 
other, passes above the external iliac artery to join the vena cava at its 
origin. ‘Lhe left, longer, insinuates itself between the body of the second 
last lumbar vertebra and the terminal extremity of the posterior aorta, to 
open into the other. 

If we trace, as was done with the veins of the anterior extremity, from 
the ungueal region to the pelvis, all the branches which concur in the 
formation of these two trunks, we will find, as the common point of de- 
parture for each, a rich subungueal plexus, from which spring two digital 
veins. 'To these succeed three metatarsal veins, the common origin of all the 
vessels of the leg. These latter are distinguished as superficial and deep, 
and are four in number—two saphena veins in the first group, and two tibial 
vems in the second—continued by the popliteal vein. This vessel is itself 
continued by the femoral and external iliac veins, which finally form the 
pelvi-crural trunk by opening into the internal iliuc vein. 

All these vessels will be studied in an inverse order to that in which they 
have been enumerated, and as follows: 


. Internal iliac vein. 
External iliac vein. 
Femoral vein. 

Popliteal vein. 

Deep veins of the leg. 

. Superficial veins of the leg. 
. Metatarsal veins. 

. Veins of the digital region. 


COIR OR co RO 


1. Internal Iliac Vein. 


This vessel is formed by the satellite veins of the branches furnished 
by the homonymous artery: these are the <liaco-femoral, obturator, iliaco- 
muscular, gluteal, lateral sacral, and internal pudic, whose distribution does 
not differ from that of the corresponding arterial divisions. 


THE POSTERIOR VENA CAVA. 623 


The trunk resulting from the union of these different branches is usually 
very short; it may even be altogether absent, and we then see its con- 
stituent veins open into the common iliac vein by forming two or three 
separate groups situated very close to each other. 


2. External Iliac Vein. 


This vein constitutes the principal root of the pelvi-crural trunk, which 
is but a continuation of it, the internal iliac being only, properly speaking, 
a collateral affluent of the single canal represented by the external and 
common iliac veins. 

Situated behind the crural arterial trunk, this external iliac vein com- 
mences at the anterior border of the pubis, where it is directly continued, 
without any line of demarcation, by the femoral vein. 

The only important vessel it receives on its course is the iliac circumflea 


vein, which, however, opens more frequently into the common than the 
external iliac. 


3. Femoral Vein. 


Continuous by its superior extremity with the external iliac vein, and 
inferiorly with the popliteal, this femoral vein is remarkable for its large 
volume, and closely follows the artery of the same name throughout its 
extent (Fig. 293, 5). 

The collateral affluents it receives in its course are distinguished by 
their number and considerable volume. They are :— ‘ 

1. The satellite veins of the muscular arteries. 

2. The internal saphena vein, which will be again referred to in describing 
the superficial veins of the leg. 

3. The prepubic vein, formed by the posterior abdominal and the branches 
of the internal pudic. The latter are very numerous and large, and anas- 
tomose with each other, forming between the thighs, in the texture of the 
scrotum and sheath, and above the penis, a very rich network which com- 
municates behind with the cavernous veins. This network only sends a 
small trunk into the inguinal ring, along the external pudic artery; in its 
middle part it opens into an enormous branch which traverses the ring in 
the sartorius muscle, and is lodged in the inferior groove of the pubis to 
join the femoral vein. 

One of these external pudic veins represents the subcutaneous abdominal 
vein, and communicates with the subcutaneous thoracic vessel. 

All these branches in the female show an analogous disposition, 


4. Popliteal Vein. 


Satellite of the popliteal artery, this vein is formed by the union of the 
anterior and posterior tibial veins. ; : 

Among the branches it receives on its course, the femoro-popliteal vein 
may be particularly noted; this accompanies the artery of the same name, 
and joins the external saphena before opening into the popliteal vein. 


5. Deep Veins of the Leg. 


These are two in number: the anterior and posterior tibial. 
A. Anterior Trea, Ven (Fig. 278, 5).—Placed beside the homo- 
nymous artery, often double, always very ample, this vein originates on the 


624 THE VEINS. 


anterior face of the tarsal articulations by means of several anastomosing 
roots, the principal of which is formed by the deep metatarsal vein, that 
passes through the cuboido-cuneo-scaphoid canal from behind to before. 
‘After crossing the fibular arch with the artery, it joms the posterior tibial 
to constitute the popliteal vein. 

B. Posrerior Tusran Ver.—This commences near the hollow of the 
hock, within the calcis, by radicular branches which principally come from 
the two saphena veins. It then ascends along its satellite artery, to open 
into the anterior vein beneath the popliteal muscle. 


6. Superficial Veins of the Leg. 


These are the internal and external saphena. 

A. Invernan Sapuena Vern.—This vessel shows two roots—an anterior 
and posterior (Fig. 293, 39, 40). : 

The first proceeds from the internal metatarsal vein, the second from the 
external. Both ascend, in converging towards each other, on the internal 
face of the tibia, uniting into a single branch before reaching the thigh. 

This single branch, always very volumingus, glides upwards on the 
sartorius muscle, and terminates in a variable manner on reaching the groin: 
sometimes it is insinuated into the interstice of the two adductors of the 
leg, to join the femoral vein, and at other times it ascends to the ring of the 
short adductor, and opens into the external pudic veins. 

B. Exrernay Saraena VEIn.—It rises, by a short branch, outside the 
os calcis, communicates, even at its origin, with the posterior root of the 
internal saphena by means of a large reticular anastomosis thrown trans- 
versely in front of the apex of the calcis ; and with the posterior tibial, by a 
large branch which passes between the tibia and the perforans muscle. It 
follows the external saphena nerve outside the gastrocnemii tendons, behind 
the external gastrocnemius muscle, and enters the popliteal vein, after 
joining the femoro-popliteal vessel. 


7. Metatarsal Veins. 


These veins arc three in number, and are distinguished as internal, 
external, and deep ; they proceed from the sesamoid arch, which is formed 
by the anastomosis of the two digital veins. 

A. InrernaL MurararsaL Vern (Fig. 278, 9).—This vessel, the most 
considerable of the three, appears more particularly to continue the digital 
vein of the same side. For the greater part of its extent it is placed with 
the internal plantar nerve, along, and a little in advance of, the flexor 
tendons. Arriving near the tarsus, it deviates slightly to reach the anterior 
face of the tarsal articulations, and there communicates, by a very large 
transverse branch, with the origin of the anterior tibial vein; afterwards it 
rises on the internal face of the leg, where it constitutes the anterior root of 
the internal saphena vein. 

B. Exrernan Merararsan Vern (Fig. 278, 8).—It occupies, outside 
the flexor tendons, a position analogous to the preceding. Towards the 
superior extremity of the metatarsus, it communicates, by a short thick 
branch, with the deep vein. It then continues its ascending course by 
entering the tarsal sheath along with the plantar arteries, and is prolonged 
in the hollow of the hock, along the great femoro-popliteal nerve, in con- 
stituting the posterior root of the internal saphena, 

C. Derr Meratarsan Vern (Fig. 278, 10).—This is placed beneath 


THE POSTERIOR VENA CAVA. 625 


the suspensory ligament, at the inner side of the principal interosseous 
plantar artery. Near the tarsus, it receives a very large branch from the 
external vein, and then traverses the cuboido-cunco-scaphoid canal, to form 
the largest root of the anterior tibial vein. 


8. Veins of the Digital Region. 


As these resemble, in every respect, those belonging to the anterior 
limb, the same description will suffice for both (see page 613). 


DIFFERENTIAL CHARACTERS IN THE VEINS OF OTHER THAN SOLIPED ANIMALS. 


It does not come within our plan to give a complete history of the venous system of 
these animals, because of the small utility of such a study. To remain faithful to the 
object in view, we confine ourselves to the indication of the special characters of the 
veins on which bleeding is usually practised, and those which may be interesting in a 
surgical point of view, as the digital veins of Ruminants. 

A. ANGULAR VEIN oF THE Kye.—This vessel is remarkable for its large volume in 
the Sheep; and as it is well defined beneath the skin, in consequence of the fineness of 
that membrane, it is more frequently selected for phlebotomy than in other animals, 

B. Jugutar Vein.—Very large m all animals, and particularly in the Oz, this vein 
deserves the preference given to it when it is proposed to abstract a certain quantity of 
blood from the system. 

In all non-soliped animals there is found an accessory jugular, which sometimes exists 
in the Horse, but is much less in size, alongside the common carotid artery. It arises 
from the occipital vein, and, therefore, measures the whole length of the neck. Sometimes 
its diameter is small; but it is often so large as to receive a very notable quantity of 
blood from the principal jugular, when compression is applied to the latter to favour the 
flow of blood after opening it: a circumstance which explains the difficulty sometimes 
experienced in obtaining a voluminous jet of blood. 

©. ABpomINAL SuBouraNneots Vein.—In the Bovine species, this vessel has an 
enormous volume, especially in the milch-cow, in contradistinction to the subcutaneous 
thoracic vein, which is always very narrow. 

This vein is prolonged forward on the wall of the abdomen, to nearly the xiphoid 
cartilage, where it passes through to join the internal thoracic vein.’ Behind, it is 
formed by multiple branches, which anastomose with each other, or with thoze of the 
opposite vein, and are in communication with the proper external pudic veins. 

D. InrernaL SapHeNA VEIN.—This is alway smaller than in Solipeds, and is rarely 
selected to bleed from. 

E. Exvernau SapHena VeIn.—This vessel is, on the contrary, more voluminous than 
in the Horse, and at the same time more superficial ; consequently, it is more favourably 
situated for phlebotomy, as well in Pigs and the Carnivora, as in Ruminants. It arises 
from the union, in the hollow of the hock, of the two principal roots furnished by the 
metatarsal veins. 

F. Vers or THE Posterior Foor iv tue Ox.—As in the Horse, they commence in 
the subungueal network of the digital region, which is double, like the region itself. 

a. Three digital veins leave this reticulum: 1, A median or anterior one, arising by 
two roots from the anterior part of each network, passing between the two digit, and 
joining the anterior superficial metatarsal vein above the fetlock ; 2, Two laterals, com- 
municating with one another, behind, by a transverse anastomosis which receives several 
venules from the ungueal plexus, and with the anterior vein by an interdigital branch, 
united by an arch in front of the flexor tendons, above the sesamoid groove. 

b. These digital veins are continued by five metatarsal veins: two deep and one 
superficial anterior, and two posterior. . 

The two deep anterior veins are small vessels which accompany the collateral artery 
of the cannon, which is placed between them. They arise in the interdigital space from 
the anterior digital vein, communicating, by the inferior metatarsal foramen, with the 
sesamoid arch, sending off on their way transverse anastomoses, and being continued 
above the tarsus by the two anterior tibial veins, whose roots they constitute. 

The anterior superficial vein is very voluminous. It proceeds from the sesamoid arch, 


1 The openings through which these vessels pass in the abdominal parietes, are 
commonly named the milk fountains or doors. 


626 THE VEINS. 


receives near its origin the median digital vein, rises in front of, and a little to the 
outside of, the tarsus, communicating at this point with the anterior tibial veins; it 
divides above the tibio-tarsal articulation into two branches: a posterior, forming the 
anterior root of the external saphena; the other anterior, joining the anterior tibial vein 
sternal side. ; 
se pews posterior veins spriug from the sesamoid arch, Situated at first between the 
suspensory ligament of the fetlock and the posterior face of the metatarsus, and com- 
municating there by several anastomoses, these two veins are continued along the tarsus, 
the one within, the other without, The internal follows the corresponding plantar artery, 
and is prolonged in the tibial region by the posterior tibial and internal saphena veing, 
The external ascends within the calcis, and is united to a branch of the anterior super- 
ficial metatarsal, to form the external saphena vein. Before leaving the deep situation 
it occupies below the suspensory lixament of the fetlock, these two vessels concur, but 
especially the internal, to form a perforating brauch which traverses the cuboido-scaphoid 
canal to join the anterior tibial veins. 

G. Veins or THE ANTERIOR Foor in THE Ox.—Four digital veins escape from the 
two subungueal plexuses: an anterior, posterior, and two lateral. 

a. The anterior digital vein, which is very slender, is lodged superficially between the 
two digits, and comports itself at its origin like the analogous vein of the posterior 
limb, in rising by two roots. In being prolonged above the fetlock, it constitutes a 
subcutaneous metacarpal branch, which occupies the anterior and internal plane of the 
cannon, and is united above the knee to the principal cutaveous vein of the fore-arm. 

b. The posterior digital vein, often doubled by a small accessory branch, accompanies 
the common digital artery, and extends aloag the collateral artery of the cannon, to 
constitute one of the posterior radial veins. 

e. The internal digital vein, after passing the digital region, is lodged between the 
cannon bone and the internal border of the suspensory ligament, proceeds outside the 
carpal sheath with the radio-palmar artery, and divides above the knee into two 
branches: au anterior, the origin of the iuternal subcutaneous vein of the fore-arm; the 
other posterior, forming one of the posterior radial veins. : 

d. The external digital vein occupies, cn the outer side of the external digit and the 
cannon bone, a position analogous to the internal vein. It gives rise to several deep 
metacarpal veins which anastomose, and are mixed with the interosseous palmar 
arteries ; the principal vein and its accessory branches are joined, below the carpus, to 
the internal vein. 

It is to be remarked that these four digital veins communicate, in’the interdigital 
space, by anastomoses resembling those of the posterior limb; and that the last three, 
or principal veins, anastomose above the fetlock in forming a complicated and variably- 
arranged sesamoid arch, on Ieaviug which these digital veins become metacarpal vessels, 


COMPARISON OF THE VEINS IN MAN WITH THOSE OF ANIMALS. 


In Man, as in animals, the veins are grouped into those of the lesser circulation, or 
pulmonary veins, and those of the greater circulation. ‘The latter open into the heart by 
three trunks: the cardiac veins, and superior and inferior vena cara, 

The superior vena cava represents the anterior vena cava of animals, and receives the 
blood from the veins of the head, thoracic limbs, and a portion of the chest. It extends 
from the first costal cartilage to the heart, and commences after the junction of the two 
brachio-cephalic trunks (innominate veins). 

The superficial veins of the thoracic limb at first form, on the back of the hand, a 
plexus of elongated meshes from which the median, radial, and ulnar veins spring. Near 
the bend of the elbow, the median bifurcates and gives rise to the median cephalic and 
median basilic. Blood is abstracted from one or other of these branches, At the arm, 
all the superficial veins constitute but two trunks: the cephalic and basilic veins. Tho 
deep vessels join these to form the axillary vein, which becomes the subclavian below the 
oe then the brachiv-cephalic trunk (vena tunominata) when it receives the internal 
jugular 

The venous sinuses of the cranial dura mater are proportionately more developed 
than in Solipeds, though they have the same disposition. ‘There is constantly present a 
median or inferior longitudinal sinus. 

_ The jugulars which carry the blood from the cranium and face to the heart, are four 
innumber. The anterior jugular, the smallest, descends beneath the superficial cervical 
aponeurosis, in front of the sterno-mastoideus muscle, and enters the subclavian vein. 
The external jugular commences by the union of the facial and temporal vein; in its 
disposition it resembles the jugular or the Horse, and would be a complete representative 


GENERAL CONSIDERATIONS. 627 


if deprived of the branches from the cranial si 7 j i 
r anial sinuses. The internal jugular ariscs at the 
Spaced foramen lacerum, at a dilatation of the lateral sinus i the bulbus venz 
Jugu: a ee ale: to the subclavian vein. Lastly, the posterior jugular (or vertebral 
iat ae ve mate Wen ha complexus, and in relation with the cervical vertebra, 
bl e spinal sinuses in thi i ich, i ipeds, i i 
by the cecil ance in this region, and which, in Solipeds, is received 
© inferior vena cava corresponds to the posterior vena cava of animals, and receives 
the blood from all the subdiaphragmatic veins. It originates from the union of the 
two ga iliac veins, at the third lumbar articulation, and terminates in the right 
auricle. In its course it receives the median sacral, lumbar, renal, suprurenal, inferior 
Shins a ib cal 4 ae ie latter forms on the surface of the testicle, and at 
gin of the cord, a rich network—the spermatic pl : i ti 
the ae it constitutes the pampiniform sia eit elie aka 
e vena cava also receives the vena porte, which has the same disposition as in 
animals. It begins by three branches : the great and small mesaraic sel aplonts veins. 
For affluents, it has the pancreatic and duodenal venules, and the right gastro-omental 
vein. It passes behind the pancreas, and not through that gland, as in the Horse. 

The veins of the abdominal limb are divided into deep and superficial. The first 
terminate by forming the femoral vein, which, in joining the vessels of the pelvis, 
constitutes the common iliac vein. The superficial veins commence by a network on 
the dorsum of the foot, which gives origin to the two saphenas: external and internal. 


FOURTH SECTION. 
Tur LyMpuarics. 


CHAPTER I. 


GENERAL CONSIDERATIONS. 


CuarcED with the absorption and transport of the chyle and lymph, the 
lymphatic or absorbent vessels are convergent canals with thin and transparent 
walls, which originate in the texture of organs by fine reticulated radicule ; 
and which, after traversing one or more ganglia (or glands)—glandiform 
bodies placed on their course—enter the venous system by two trunks: the 
thoracic duct and the great lymphatic vein. 


LYMPHATIC VESSELS. 


These canals resemble veins in so many points, as to merit the name of 
white-blood veins. Like these vessels, the lymphatics are directed from the 
periphery to the centre of the circulatory apparatus; like them, they are 
nodulated cylindrical tubes; internally, and at those points where they 
outwardly appear to be constricted, they show numerous valves which louk 
towards the heart; like the veins, again, they separate into two orders of 
canals: the ones deep-seated, lodged in the vasculo-nervous intermuscular 
sheaths; the others superficial, situated on the surface of containing apon- 
euroses; like the veins, also, the lymphatics terminate in two principal trunks 
resembling the vene cave; and, finally, as the veins have three tunics, 0) 
have the lymphatics, these not differing in any respect, except in being very 
much thinner. ; : 

In carrying this parallel still farther, we will find other analogies whose 
existence was but little suspected until recently: the glands—those organs 
which are apparently glandular, and seem to be proper to the lymphatic 
system—are they not represented in the venous system by the lver— 


628 THE LYMPHATICS. 


that enormous gland placed on the track of the abdominal veins—as the 
glands are on parts of the lymphatics ? : ; 7 

It may be added that, if we pass into the domain of physiology, it is also 
easy to observe characters which are common to the two anatomical systems 
under comparison. They, in fact, almost equally divide the absorbent 
function between them: a function which is accomplished in the radicular 
network of each; and the dynamical process which gives impulsion to the 
fluids they carry, if it is not quite identical in both, is at any rate very similar 
in many points. ; 

We may, nevertheless, observe numerous differences between the veins and 
the lymphatics, and chiefly in their form, number, capacity, and structure. 

The form of the lymphatic canals is, as we have said, nodulated and 
cylindrical ; but their external nodosities are much less marked, and are closer 
together than in the veins, owing to the larger number and greater develop- 
ment of the valves. Besides, as these canals travel for considerable distances, 
and preserve their regularly-cylindrical form with undiminished capacity, 
if we mentally bring all the divisions of the lymphatic system to a single 
canal, we no longer obtain a hollow cone whose apex corresponds with the 
heart, although the capacity of the lymphatic vessels augments from the 
trunk towards the branches; this conduit only represents a series of 
cylinders joined end to end, and successively decreasing from its origin to its 
termination. 

The number of lymphatic vessels in a certain region is always much 
greater than that of the veins. But as the lymphatics are much smaller 
than the veins, there is not,as might at first be supposed, a proportional 
increase in their total capacity. Observation, indeed, demonstrates that the 
relation between the capacity of the lymphatics, and the corresponding veins 
of a region does not exceed one to two. 

The structure of the lymphatics differs from that of veins in that there 
exists, in those of average dimensions, smooth muscular fibres in the adven- 
titious tunic. The presence of muscular fibres in the external tunic of 
these vessels is rendered necessary by the absence of an impelling organ at 
the origin of the lymphatic system : this organ being, in reality, disseminated 
throughout the extent of the canals, and aids the vis a tergo that causes the 
lymph to circulate in their interior. 

We terminate this short parallel, to dwell in detail on several points 
connected with the general history of the lymphatics, and which merit 
particular attention; we allude to the origin, course, and termination of 
these vessels, 

Ortary.—For a long period after the discovery of the lymphatic vessels, a 
state of profound ignorance existed as to their origin. Nevertheless, the 
importance of the solution of the problem was well appreciated, as it was 
really the key to the theory of absorption; numerous hypotheses, therefore, 
sprang into existence. The anatomists who occupied themselves with the 
question were hindered in their investigation by the imperfect means of 
research at their disposal. Beyond the larger branches, the lymphatics 
escaped attention, owing to their transparency and tenuity. Thanks, how- 
ever, to the patient and minute researches of Hunter, Cruikshank, Mascagni, 
Fohmann, Panizza, Cruveilhier, and Sappey, the lymphatics were injected by 
colouring matters or by mercury, and thus rendered visible to their finest 
ramifications. 

It is now known that the lymphatics arise from capillaries, which form 
networks or terminal culs-de-sac, 


GENERAL CONSIDERATIONS. 629 


These terminal culs-de-sac exist in the intestinal villi; and itis no longer 
maintained that the ends of these small appendices have an opening by 
which the lymphatic receives the chyle that bathes the mucous membrane of 
the intestine. 

The plexuses are composed of more or less irregular meshes, and their 
form and volume often vary with the disposition of the tissues or organs in 
which they are studied. They may be superficial or deep, and exist together 
or separately. In many membranes the two networks are found, but then 
the superficial is thinner than the deep. They are mixed with, or placed 
above, the blood-vessel plexuses, but never communicate with them. 

Do these lymphatic plexuses ewist in all the tissues, properly speaking ? Here 
is another question of incontestible importance, and whose solution is even 
now occupying the attention of anatomists. Judging by analogies, one is 
tempted to reply in the affirmative: why, in fact, should the lymphatics not 
be spread everywhere throughout the organism, when the sanguine capil- 
laries are constituent parts in the framework of each tissue? It is true we 
may ask if lymphatic absorption is a necessary act in the vital movement ; and 
although science is far from being satisfied on this point, we know some 
facts which at least authorize the doubt. On the other hand, direct ob- 
servation has not revealed lymphatic plexuses in all organs; there are even 
tissues in which their existence has been denied: though prematurely, it is 
well to say, because we may always attribute the non-success of a lymphatic 
injection either to the imperfection of the instruments employed, the 
insufficiency of the measures adopted, or certain peculiar conditions as yet 
unknown attaching to the species of animals selected for the demonstration 
of the lymphatic networks in a certain region. As bearing out this last 
assertion, we may observe that M. Sappey has not yet. been able to inject 
the pituitary plexuses in Man or the Calf, and that he looks upon their 
existence as being at least doubtful; while in the Horse, this lymphatic 
apparatus is as remarkable for its richness, as for the facility with which 
it may be filled with mercury. 

The following are the most trustworthy notions available on this subject. 

The lymphatic vessels of the skin are very numerous, and form two net- 
works: one, with extremely fine meshes, occupies the most superficial 
layer of the dermis; the other, placed beneath the deep face of the integu- 
ment, includes vessels more voluminous than the first, and communicates 
with it by multiplied ramuscules. These lymphatic plexuses are far from 
being equally developed in every region: though it is unanimously agreed 
that no part is entirely destitute of them. an 

In the internal tegument, or mucous membranes, an analogous disposition 
of these vessels is met with. It is more than probable that they exist 
throughout the whole extent of these membranes, though their positive 
demonstration has yet to be made in some regions. In other regions, the 
injection of these networks is, on the contrary, very easy, and gives the most 
magnificent results; we particularly mention the lingual, intestinal, and 
pituitary mucous membranes. The lymphatics belonging to the latter 
membrane assume so beautiful an aspect in the Horse, that we would advise 
anatomists who desire to inject lymphatics always to choose that animal. 
The operation is simple and constantly performed, and we are astonished 
that in the hands of some individuals it should fail. Not only can the two 
networks of the membrane be filled, but also the trunks arising from them, 
and which are directed towards the entrance of the nasal cavities, collect in 
several thick branches around the nostril, and bend up towards the fece 

43 


630 THE LYMPHATICS. 


to reach the submaxillary cavity, where they enter the ganglia situated to 
the right and left of that space. : ' : 

The majority of anatomists admit the presence of lymphatic plexuses in 
the splanchnic or synovial serous membranes. M. Sappey, however, denies 
this; he considers the vessels that can be so easily injected by pricking the 
external surface of a viscus, as belonging to its proper tissue, and not to the 
serous membrane covering it. Those on the inner face of the walls of the 
splanchine or synovial cavities, and which are sometimes filled with mercury, 
do not, according to him, come from the serous tunic, but from the sub- 
jacent tissues. ; 

The lymphatics do not exist in vessels, although some modern anatomists 
have admitted them to be present in the inner layer of the circulatory 
apparatus. The lymphatic sheaths discovered by His, Robin, and Tomaso, 
around the blood-capillaries of the frog, and those of the brain and spleen 
of Man, ought not to be considered as the lymphatics of vessels, as they 
merely surround the ultimate vascular ramifications, and do not arise in the 
substance of their walls. 

In the nervous tissue lymphatics have not been discovered, though they 
are present in the meninges. 

Their existence is doubtful in bone tissue and in the muscles ; but they are 
abundant in the glands and glandiform organs of the animal economy, 
forming the finest, richest, and most easily demonstrated plexuses. 

It has been stated above that the lymphatics commence by capillaries 
arranged in networks. Are these networks the real, or only the apparent, origin 
of the lymphatics? This isa question that has been, and is still, warmly 
discussed. It is, however, believed that the plexuses are fed by very minute 
radicles lodged in the substance of the tissues. 

But how do these radicles originate? In the epithelium, says Kiiss; in 
the plasmatic cells of the connective tissue, asserts Virchow ; in the serous 
membranes, states Recklinghausen, since he observed fatty matters pene- 
trate the lymphatics by the abdominal face of the diaphragm. The opinion 
of Virchow is overthrown at present by the researches of Ranvier, which 
have modified the descriptions given of the connective tissue. According to 
this authority, plasmatic cells do not exist in that tissue; what have been 
described as such by Virchow have been only radiating spaces limited by the 
fasciculi of connective fibres, in which elements analogous to lymph globules 
circulate. It may be added that these fasciculi are covered by large flat 
cells, which give these spaces the appearance of a serous cavity with septa at 
close intervals. These conclusions of Ranvier, then, should affirm the 
hypothesis of the Wiirzbourg professor, and tend to prove that in the connec- 
tive tissue of the economy there is an infinite number of minute serous cavities 
into which the lymphatic vessels open, in which the lymph circulates, and 
which are in communication, on the other hand, with the great splanchnic 
cavities. It must be mentioned, however, that these deductions are only 
hypothetical, particularly at the period of scientific evolution through 
which we are now passing. 

Course or THE Lympaatic Vessets.—The lymphatics follow the track 
of the veins, and are divided, exactly like them, into superficial and deep 
vessels. The latter, running parallel to each other, are grouped immediately 
around the corresponding veins, on which they are generally superposed. 
The first, although situated in proximity to the superficial veins, are widely 
spread on each side and on the surface of the superficial aponeuroses, by 
forming parallel fasciculi, like the deep lymphatics. 


GENERAL CONSIDERATIONS. 631 


The direction followed by the lymphatics in their course is nearly 
always somewhat rectilinear; they never show the flexuosities which are so 
developed on the track of certain arteries, and even some veins. Neither do 
they communicate with one another by transverse or arching anastomoses. 
like those so commonly met with in the other two orders of canals belonging 
to the circulatory apparatus. They frequently, however, in their parallel 
course, bifurcate and join the neighbouring vessels. (At certain situations, as 
at some of the articulations, and in other parts, the larger stems suddenly 
break-up into a close interlacing plexus of small vessels or capillaries 
(Fig. 295), which in their disposition, greatly resemble the rete mirabile of 
the blood-vessels. This plexus is surrounded by condensed connective 
tissue, and is penetrated by blood-vessels, though no communication takes 
place between them and these, the only points at which communication occurs 
being where the great lymphatic trunks empty themselves into the vena cava. 


This rete would appear to be the first step towards the formation of a lymphatic 
gland.) 


A SECTION OF A SIMPLE RETE MIRABILE, VIEWED FROM THE SURFACE, 


a, a, Afferent vessels; 6, 6, -Efferent vessels only partially visible; from the 
popliteal space. 


But of all the considerations relative to “the course cf these canals, the 
most interesting are those which belong to the glandiform bodies placed 
along their track, and whose abridged history we shall give immediately. 

TerminaTIon.—We have already mentioned the thoracic duct and the right 
great lymphatic vein as being the receptacles of all the absorbent vessels of 
the body, and we have also stated that these two trunks enter the general 
venous system ; this union of the sanguine with the lymphatic system takes 
place at the origin of the anterior vena cava, and this vessel may be con- 
sidered as the general confluent for all the absorbents. The researches of 
Haller, Cruikshank, and Mascagni first threw light on this important fact ; 
and it is to those of Fohmann, Panizza, Rossi, é&c., that we owe the dedi- 
cation of this discovery. 


632 THE LYMPHATICS. 


LYMPHATIO GLANDS, 


The lymphatic glands are ovoid, spherical, or discoid bodies of medium 
consistency, grey, rosy, or red-coloured, and sometimes quite black, and 
which at several points intercept the course of the lymphatic vessels. 

Their number is considerable, and they are rarely isolated; most 
frequently they are collected in groups along the blood-vessels. They are 
always larger in youth than in old age. 

All the canals of the lymphatic system are provided with at least one 
gland on their course, and some even traverse two or three before opening into 
the thoracic duct or great lymphatic vein. On reaching these glands, they 
plunge into their structure in ramifications, appearing on the opposite point 
after being reconstituted into several principal canals, which are generally 
larger and less numerous than the primitive vessels. The latter take the 
name of afferents (vasa inferentia or afferentia); the others are named 
efferents (vasa efferentia), because they leave the gland to reach the central 
canal. 

Sravcture.—The structure of the glands is extremely complicated, and 
difficult to make out, in consequence of the delicateness of their tissue. The 
following is what is positively known in reference to this subject. 

The glands have an envelope of connective tissue (continuous with the 
tunics of the afferent and efferent vessels), which surrounds a substance that is 
readily perceived to be composed of two layers of a different aspect: one 
cortical, the other medullary. 

The first appears to be granular, the second somewhat fibrous. This 
proper tissue is sustained by connective lamine (or septa—continuations of 
the capsule) which contain smooth muscular fibres. The lamine form alveoli 
in the cortical layer, and a sort of minute tubes in the central layer. These 
alveoli are in their turn divided by reticular tissue into secondary spaces, 
which become smaller as they lie near the centre; at the periphery, where 


Fig, 296, 


SIMPLE LYMPHATIC GLAND. 
a, The capsule with sections of lym- 
phatics, d, d, passing through it; 
6, Lacunar and intercommunicating 


SECTION OF A LYMPHATIC GLAND, 


a, a, The fibrous tissue that forms its exterior: 0. b passa, 9 
I s q ges, permeated by the lymph 
Superficial vasa inferentia; 0, c, Larger alveoli, and forming the saneridal Tyme 
near the surface ; d, d, Smaller alveoli of the path of Frey; c, Nucleus, or me- 
interior ; ¢, ¢, Fibrous walls of the alveoli. dullary portion, with section of 


blood-vessel in the centre. 


they are most voluminous, they are named ic si 
s, ymphatic sinuses. Everywhere 
these sinuses are filled with lymph globules. The arrangement is identical 


GENERAL CONSIDERATIONS. 633 


in the medullary substance ; in the interior are seen o great number of 
arterial capillaries. The nerves are derived from the sympathetic system. 


The atterent lymphatics, where they enter the gland, communicate with 
the alveoli which correspond to 


the cortical substance ; these al- 
veoli are connected by the cords 
of the central layer, and the latter 
are united, in their turn, to the 
alveoli of the opposite side of the 
cortical substance, from which the 
efferent ramuscules spring. The 
lymph, therefore, traverses every 
part of the gland, and during this 
very tortuous course becomes 
charged with solid particles. 
Certain glands have a much 
more simple structure, being en- 
tirely composed of lymphatic capil- 
laries rolled up on themselves in 
clusters, and anastomosing in net- 
works. These capillaries arise 
from the divergent arborisation of 
the afferent vessels, and are contin- 
uous with the convergent branches 
which, by their union, form the 
efferent lymphatics. The organs 
have received the name of false 
glands, though they are really 
lymphatic glands. In support of 
this assertion, it may be said that 
“in descending the animal series, 
we see the glands becoming more 
and more simplified, and trans- 


Fig. 298. 


PORTION OF THE MEDULLARY SUBSTANCE OF THE 
MESENTERIC GLAND OF AN OX, THE ARTERY 
OF WHICH IS INJECTED WITH CHROMATE OF 
LEAD; MAGNIFIED 300 DIAMETERS. 

a, Medullary substance with capillary network, 
fine reticulum of connective tissue, and a few 
lymph corpuscles; 6, 6, Superficial lymph- 


formed at a great number of points 
into an interlacing of vessels. In 
birds, they only occupy the base 
of the neck and the entrance to the 
chest, forming in all the other 
regions simple plexuses; in rep- 


path, traversed by 4 reticulum of nucleated 
cells (cc), with numerous anastomosing pro- 
longations. The lymph corpuscles have for 
the most part been removed; d, d, Trabecule 
composed almost exclusively of unstriped mus- 
cular tissue; g, A small medullary cord, or 
bridge, containing a blood-vessel and numerous 
lymph corpuscles. \ 


tiles and fishes, the lymphatic glands 
disappear altogether, and the plexuses that replace them are themselves not 
at all complicated.”— Sappey. 


PREPARATION o¥ THE LympPHaTIC VeESseLs.—The lymphatic networks can only be 
studied after having been filled with mercury by means of injection; but as this opera- 
tion is not usually practised by the pupils for whom this book is written, the mode of 
performing it will only be traced in a few words. ; : : 

The apparatus in use consists of a glass tube continued by a flexible one, which 
carries at its inferior extremity an iron tap and a fine canula, also of iron, or (better) glass. 
To apply this apparatus, the tube ought to be suspended and then filled with mercury ; 
the canula is then seized by the right hand, keeping it parallel to the membrane we 
wish to inject, and burying it in the most superficial layer of that membrane. The 
extremity of the canula is thus introduced into the midst of the meshes of the lymphat‘e 
network, and necessarily wounds some of the capillaries which compose it. In opening 
the tap, the mercury is allowed to flow into the capillaries by the solutions of continuity 
they present, and fills them in the most perfect manner. The lymphatic plexuses being 


634 THE LYMPHATICS. 


illary blood-vessels, one is always certain of injecting them 
pein ike omer to penetrate the membrane as superficially as possible. If 
the point of the canula enters too deeply, the mercury will pass into the veins, and the 
operation will be unsuccessful, and must be commenced again. : ‘ ; 

To study the branches and lymphatic trunks, it will suffice to inflate them from 
their origin towards their termination. This procedure, properly conducted—and it was 
almost exclusively the only one adopted by the older anatomists—gives the most satis- 
factory results, and is even sufficient to demonstrate the texture of the glands. 

The latter do not require any particular precautions in their preparation. 


CHAPTER IT. 


THE LYMPHATICS IN PARTICULAR. 


We will commence with the examination of the thoracic duct and all 
its effluents, and terminate by studying the great lymphatic vein. ; 

In this description the glands and principal lymphatic vessels will be 
only referred to, the disposition of the networks being already noticed 
in speaking of the different organs, and they will be further mentioned 
when speaking of the nervous system, the organs of sense, and those of 
generation 


ArticLe I.—Tue Tuoracto Duct. (Fig. 293, r 1.) 


Preparation.—Tie the jugulars and axillary veins near their termination, as well as 
the anterior vena cava about the middle of its length; expose the thoracic duct by 
removing the ribs on the right side; open that canal near the pillars of the diaphragm, 
and throw into its interior two injections of tallow, one forward, the other backward 
from the incision. The first injection will fill the canal and the venous reservoir which 
is intersected between the ligatures applied to the above-named vessels; the second, 
although directed in opposition to the valves, overcomes the resistance offered by them, 
and passes into Pecquet’s cistern and the principal branches which open into that 
confluent. Or we may select one of these branches in the abdominal cavity—for example, 
one of those which lie beside the colic arteries near their origin—and inject the entire 
thoracic duct from its origin to its termination. 

But this proceeding requires more practical ability than the first, in order to find 
the ca which is te receive the canula; and if the animal ig very fat, it is im- 
possible. 


The thoracic duct is the general confluent for all the lymphatics of the 
body, with the exception of those which come from the right anterior limb 
and the right moiety of the head, neck, and thorax. 

Extent.—It extends beneath the vertebral column, from the first lumbar 
vertebra to beyond the entrance to the thorax. 

Origin.—Its origin is marked by a very irregular dilatation described as 
the sublumbar reservoir, or cistern of Pecquet (receptaculum or cyster nachyli), 
into which open the principal affluents of the canal. 

This reservoir is divided, internally, by lamell into several incomplete 
compartments, and may be more or less voluminous and circumscribed, and 
present very variable forms. 

It is placed above the abdominal aorta and the posterior vena cava, at 
the great mesenteric artery, or more frequently a little behind it. In the 
Dog it is of an enormous size, oval in shape, and prolonged between the 
pillars of the diaphragm into the thoracic cavity. 

Course.—To this reservoir succeeds a tube whose calibre is very irregular, 
and appears singularly slender when compared with the diameter of the 


THE THORACIC DUCT. 635 


initial dilatation, or that of the affluent vessels composing it. This is the 
thoracic duct. We see it enter between the two pillars of the diaphragm 

along with the aorta, deviating more or less to the right side of that vessel, 
and follow it thus to about the sixth dorsal vertebra, in passing to the outside 
of the right intercostal arteries, which it crosses, and beneath the great vena 
azygos, beside which it lies. Sometimes, however, we find it carried in this 
first part of its course directly above the thoracic aorta, between the double 
series of intercostal arteries, and to the left of the vena azygos, which is 
then found immediately in contact with the right side of the aorta; or it 
may even creep to the right of that vein, concealing the greater part of it 
from sight. Leaving the above-mentioned dorsal vertebra, the thoracic 
duct abandons the aorta and crosses the flexure of the vena azygos to the 
left, to extend itself forward on the left side of the trachea, but often also 
on the right side. It afterwards places itself between the two axillary 
arteries, crosses the interval comprised between the prepectoral glands, 
emerges from the chest, and terminates in a manner to be indicated 
hereafter. 

Termination.—The terminal extremity of the thoracic duct is always 
provided with a dilatation analogous to that which exists at its origin, though 
much smaller, better circumscribed, and less irregular—a dilatation which 
opens into the anterior vena cava sometimes by a single orifice furnished 
with valves, at other times by two very short branches, whose length we 
cannot estimate at more than the fifth part of an inch, and which are also 
valvular at their entrance. The point where this entrance takes place is 
nearly always at the summit of the vena cava, and precisely at the point of junc- 
tion of the two jugulars. ‘The thoracic duct rarely opens elsewhere ; though 
the fact that it does so at times is exemplified in a specimen in the museum 
of the Lyons School, in which the embouchure of the duct is placed 
between the termination of the left jugular and that of the corresponding 
axillary vein. 

Varieties in Solipeds——* The thoracic duct is far from always showing 
itself in Solipeds as I have described it, but in its course and insertion 
presents a great number of variations which we will now pass in review. 

“The single canal is separated sometimes, at a part of its length, into two 
branches, which, after proceeding parallel to each other, soon unite to form 
a single vessel. This division usually takes place at the base of the heart, 
at the place where the lymphatics of the bronchial and cesophageal glands 
enter ; it forms a ring whose diameter is often not more than four-tenths of 
an inch, or an ellipse whose larger axis is from four to eight-tenths of an inch. 
We see this produced once, twice, and even thrice on the anterior half of 
the canal, which becomes simple at its termination as it was at its origin. 
The spaces circumscribed by the bifurcations constitute what have been 
termed the insule. 

“The canal, instead of remaining single, very often becomes double from 
its commencement (Fig. 300). Then the two canals are sensibly equal, 
or one is larger than the other. If they are unequal, it is usually the right 
which has the advantage, though the contrary sometimes occurs. In any 
case, the two canals are isolated, one being to the right, the other to the left 
of the aorta. In advancing towards the entrance to the thorax, they remain 
completely.separated, or communicate with each other by one or two, more 
or less voluminous, transverse anastomosing branches. Reaching to ten, 
eight, and sometimes even to two inches from their opening into the jugular, 
gulf, the two canals approach each other, and become confounded into a single 


THE LYMPHATICS. 


Fig. 299. 


DIFFERENT VARIETIES OF THE THORACIC DUCT IN THE HORSE. 


A, Receptaculum chyli; B, Sublumbar branches; ¢, Anterior mesenteric branch ; D, Posterior 
mesenteric branch, In figure 299 the duct is single, the usual condition, and enters the 


AFFLUENTS OF THE THORACIC DUCT. 637 


vessel. Their fusion generally takes place at the base of the heart, and 
I have never seen them remain distinct throughout their whole extent, to 
enter the vena cava separately. 

“Sometimes (Fig. 301) there emanates from the gland, at the entrance 
to the thorax, a long canal which proceeds parallel to the first, and joins 
it, after a retrograde course, near the pillars of the diaphragm. 

“The thoracic duct, double for the greater part of its extent, from the 
time it leaves the sublumbar reservoir, occasionally ends by becoming 
triple. In this case, the largest of the two canals is divided into two 
branches; then the three canals, after pursuing a certain course, all join at 
the same point, or two are first united into a single conduit, into which the 
third opens at a variable distance from the confluent of the first.” 

The affluents of the thoracic duct.—The lymphatic branches which 
enter the thoracic duct are as remarkable for their number as their volume. 
Some empty themselves into the sublumbar reservoir; a few vessels open 
into the great lymphatic vein of the thorax, and the others terminate in that 
conduit, near its insertion into the venous system. 

The first, variable in their number, particularly the largest, are more 
especially regarded as the roots of the thoracic duct. 

Ordinarily three are found, with a certain number of small accessory 
trunks. One of the largest branches enters the posterior part of the cistern ; 
very often double, and even multiple, it arises from an enormous group of 
ganglia placed in the sublumbar region, around the posterior extremity of 
the abdominal aorta and vena cava, and into which are collected all the 
yessels of the posterior limbs, the pelvis, abdominal walls, and the pelvi- 
inguinal viscera. The other two trunks reach the left side of the cistern, 
and result from the union of the lymphatics which have their source in the 
abdominal digestive organs; among these lymphatics, however, there are 
some belonging to the parictes of the stomach and the parenchyma of the 
liver and spleen, and which approach the right side of the sublumbar recep- 
tacle, to open singly into that cavity. 

The affluents the thoracic duct receives on its course, proceed from 
the viscera contained in the thoracic cavity, and from the walls of that cavity. 

Those which terminate at the anterior extremity of the duct are formed 
by the lymphatics of the left anterior limb, and the left half of the 
thorax, diaphragm, neck, and head. 

We will now examine rapidly all the radicular branches of these 
affluents. 


Articte IL.—Tae Lympuatics WHICH FORM THE AFFLUENTS OF THE 
Troracic Duct. 


These lymphatic vessels are divided into five groups. 1, Those of the 
abdominal limb, the pelvis, abdominal parietes, and the pelvi-inguinal 
organs; 2, Those of the abdominal digestive viscera; 8, T'hose of the 
organs contained in the chest; 4, Those of the thorax; 5, Those of the 
head, neck, and anterior limb. 


1 @ Colin. ‘Traite de Physiologie Comparée des Animaux Domestiques,’ vol. ii. 


summit of the anterior vena cava by two short branches. It is double in Figure 300; 
and in Figure 301 it has a long branch that arises at the entrance to the thorax and 
joins the duct, by a retrograde course, near the pillars of the diaphragm. 


638 THE LYMPHATICS. 


LYMPHATICS OF THE ABDOMINAL LIMB, PELVIS, ABDOMINAL PARIETES, AND 
THE PELVI-INGUINAL ORGANS, 


All these vessels converge towards an immense group of ganglia, named 
the sublumbar glands. Besides these, there are other groups on different 
parts of their track, constituting the deep inguinal, superficial inguinal, 
popliteal, iliac, and precrural glands. The successive description of these 
ganglia, and their afferent and efferent vessels, will conveniently make 
known the lymphatic apparatus, whose study we have in view in this 
paragraph. 

1. Sublumbar Glands. 


This group, which occupies, as its name indicates, the sublumbar region, 
comprises: 1, A small single mass situated in the sinus of the angle formed 
between the two internal iliac arteries, and is often formed by a single large 
ganelion; 2, Another mass lodged between the two iliac arteries, and a 
third placed without, and to the front of, the crural trunk: these two are 
double; 3, A single agglomeration of glandular lobules dispersed around 
the origin of the small mesenteric and spermatic arteries: these are isolated 
from one another. 

These different masses receive the lymphatics of the pelvis, the emergent 
branches of the deep inguinal ganglia, those which come from the iliac 
ganglia, some ramuscules from the rectum and large colon, and those from 
the spermatic cord. 

They are bound to each other by communicating branches, and give rise 
to several series of emergent branches, which soon collect into one or more 
trunks that enter Pecquet’s reservoir. 


2. Deep Inguinal Glands. 


This is a considerable mass of glandular lobules lodged beneath the 
aponeurosis and the crural arches, in the interstice of the adductor muscles 
of the leg, along with the crural vessels, within which they are placed. 

The form of this group is elongated, and its length may be six to eight 
inches, or even more; its superior extremity extends as high as the 
anterior border of the pubis. It is composed of from fifteen to twenty 
lobules, which rarely have an uniform colour, some being grey and others 
brown, or nearly black, 

The afferents are formed by the superficial lymphatics which accompany 
the internal saphena vein, whose roots may be traced beyond the fetlock, 
and by the deep satellite vessels of the crural artery and vein. The efferents 
proceed to the sublumbar glands, by ascending in the abdomen along the 
external iliac artery and vein. 


3. Superficial Inguinal Glands. 


These are placed in front of the inguinal ring, at the side of the sheath 
on the track of the subcutaneous abdominal artery, where they form a small 
elongated mass from two and a-half to three inches in length, and are 
composed of a dozen principal lobules. . 

Their afferents, which are very numerous, come from the in 
the thighs, the sheath, scrotum, and the inferior eas ae 
efferent vessels, much larger, but less numerous—there are only five or six— 
ascend in the inguinal canal, accompanying the external pudic artery and 


AFFLUENTS OF THE THORACIC DUCT. 639 


THE LYMPHATIC SYSTEM OF THE HORSE, 


(For Description, see p. 640. 


640 THE LYMPHATICS. 


the inguinal nervous branches. They enter the deep inguinal glands, after 
traversing the crural ring, in company with the prepubic artery. 


4, Popliteal Glands. 


These glands represent a very small mass composed of from three to 
five independent lobules, situated behind the great sciatic nerve and gas- 
trocnemii muscles, between the long vastus and semitendinous muscles, and 
near the femoro-popliteal artery. ; ; 

They receive some of the lymphatics which arise from the environs of 
the hock, and those coming from the posterior and inferior part of the 
gluteal region. Their efferents join the deep inguinal glands, by following 
the muscular interstices of the thigh. 


5. Ihae Glands. 


Slightly yellow in colour, and of a soft consistence, these glands are 
five or six in number, and form a group which is situated in the triangular 
interval comprised between the two branches of the circumflex iliac artery, 
They receive the emergent branches of the anterior crural glands, and a 
great number of deep lymphatics from the abdominal wall. Their efferent 
branches, four or five in number, follow the circumflex iliac artery to pass 
to the sublumbar glands. 


6. Precrural Glands. 


Placed within the anterior border of the fascia lata, on the track of the 
circumflex iliac artery, these glands form a small elongated mass, composed 
of a dozen lobules lying close to each other. To this group come afferent 
vessels from the anterior and internal part of the thigh. It gives rise to 
three or four large efferent vessels, which ascend the internal face of the 
muscle of the fascia lata, accompanying the circumflex iliac artery, and 
entering the abdominal cavity near the angle of the haunch, to join the iliac 
glands. 


LYMPHATICS OF THE ABDOMINAL VISCERA. 


1. Glands and Lymphatic Vessels of the Rectum and Small Colon. 


The glands in this portion of the intestinal tube are: at first, two or 
three lobules placed at the base of the tail and on each side of the sphincter 
ani; in the second place, a very numerous series of small glandular bodies 
situated along the small curvature of the viscus; thirdly, some rounded 


A, Facial and nasal plexus whose branches pass to the subglossal glands; B, ¢, Parotid 
lymphatic gland, sending vessels to the pharyngeal gland; p, x, Large trunks passing 
towards the thorax; F, G, H, Glands receiving the superficial lymphatics of the neck, 
a portion of those of the limbs, and those of the pectoral parietes; 1, Junction of the 
jugulars; J, Axillary veins; K, Summit of anterior vena cava; L, Thoracic duct; 
u, Lymphatics of spleen—n, of stomach—o, of large colon—s, of small colon; R, Lac- 
teals of small intestine—all joining to form the two trunks, P, Q, which open directly 
into the receptaculum chyli; T, Trunk whieh receives the branches of the sublumbar 
glands, u, to which the vessels of the internal iliac glands, v, the receptacles of the 
lymphatics of the abdominal parietes, pass ; w, Precrural glands receiving the lymph- 
atics of the posterior limb, and which arrive independently in the abdomen; x, Super- 
ficial inguinal glands into which the lymphatics of the mamme, external generative 
organs, some superficial trunks of the posterior limb, ete., pass; Z, Deep inguinal 
glands receiving the superficial lymphatics, z, of the posterior limbs. 


AFFLUENTS OF THE THORACIC DUCT. 641 


lobules comprised within the two layers of the mesentery, and placed on the 
track of the arterial and venous divisions. 

Originating in the texture of the mucous and muscular tunics, the lymphatic 
radicles gain the glands of the small curvature of the colon, and escape from 
them as efferent branches, which pass in great numbers into the mesentery. 
These efferents, or at least some of them, traverse the lymphatic glands 
placed on the course of the blood-vessels, and collect, near the origin of the 
posterior mesenteric artery, into several somewhat voluminous branckes, 
which join the divisions of the sublumbar glands, or those of the large colon. 


2. Glands and Lymphatic Vessels of the Large Colon. 


There'is seen on this enormous viscus a double chain of glands, lying 
beside the colic arteries, and numerous small lobules disseminated at a short 
distance from the principal glands, and on the track of the collateral 
branches furnished by these two vessels. 

Received at first, for the most part, by these lobular bodies, the lym- 
phatics which have emanated from the tunics of the viscus afterwards join 
the principal glands, from which they emerge in forming several large 
satellite branches for the colic vessels. Only two or three in number at the 
pelvic curvature, these branches are increased to ten or twelve on arriving 
near the origin of the colic arteries. It is from the union of these vessels 
with those of the small intestine, that the two large mesenteric trunks 
(Fig. 299, a, 0) arise, which, with the branches emanating from the sub- 
lumbar glands (Fig. 299, 8), form Pecquet’s reservoir. 


8. Glands and Lymphatic Vessels of the Caecum. 


There exists, on the track of each cecal artery, a moniliform series of 
glands, farther apart from one another than those of the double colic chain, 
to which the vessels coming from the cacal membranes are directed, and 
from which several long satellite branches of the blood-vessels, that 
proceed to the same trunk as those of the small intestine, depart. 


4. Glands and Lymphatic Vessels of the Small Intestine. 


The glands which receive the lymphatic vessels from the small intestine 
are very large and abundant. About thirty in number, of a grey colour, 
very compact, fusiform, often bifurcated at their superior extremity, these 
glands are placed in the texture of the mesentery, near the origin of the 
great mesenteric artery, from which those belonging to the portion of 
intestine nearest the end of the viscus are most distant. The latter also 
possess, in addition, fifteen special small glandular lobules, dispersed on the 
track of the ileo-caecal artery. 

We have already noted the richness of the vascular apparatus which 
rises from the wall of the small intestine, towards the mesenteric glands 
Tt must be added that these glands give rise, at their superior extremity, to 
large emergent branches, two or three for each, which soon coalesce to make 
more voluminous branches that concur in the formation of the two intestinal 


roots of Pecquet’s reservoir. 


5. Glands and Lymphatic Vessels of the Stomach. 


There are two classes of lymphatic glands for the stomach 1, Several 
large glands situated on the small curvature of the organ; 2, A series of 


642 THE LYMPHATICs. 


small lobules disseminated along the great curvature to the attachment of the 
great omentum. : 
The vessels which emerge from them “ gather on the track of the gastric 
arteries and veins, and ascend to the great tuberosity, near the trunk of the 
ceeliac artery ; there they anastomose with the lymphatics derived from the 
spleen and liver, and unite into several flexuous branches, some of which 
open directly into the thoracic duct, to which the others pass, after being 
confounded with the anterior trunk of the intestinal lymphatics.’—-Colin. 


6. Glands and Lymphatie Vessels of the Spleen and Liver. 


“The lymphatic vessels of the spleen, rising some from the interior of 
the viscus, others from its surface, pass towards the splenic artery and vein ; 
they traverse several groups of glands disposed on the track of these vessels, 
commencing from the middle of the length of the fissure, ascend, five or six 
in number, towards the origin of the artery in forming a sinuous mass whose 
divisions, anastomosing with those of the stomach and liver, open, on the 
one hand, with the latter in the anterior trunk of the intestinal lymphatics, 
and, on the other, into a magnificent plexus communicating directly with 
the thoracic duct. 

* Finally, the lymphatics of the liver form a very close network on the 
surface, and another in the interior of the parenchyma. They collect towards 
the posterior fissure, and first dip into a primary and very small glandular 
group, then into a second group of voluminous round glands, which are 
concealed between the trunk of the vena porte and the pancreas. They 
open in common with tho vessels of the stomach and spleen.”—Colin. 


GLANDS AND LYMPHATIC VESSELS OF THE ORGANS CONTAINED IN THE 
THORACIC CAVITY. 


We find annexed to these organs three groups of lymphatic glands: 
1, A series of small granulations placed in the posterior mediastinum, on 
the course of the esophagus; 2, The bronchial glands, situated in the angle 
of bifurcation of the trachea, around the origin of the bronchi, which they 
follow for a short distance into the pulmonary parenchyma; 3, Two long 
strings of lobules extended on the sides of the inferior face of the trachea, 
trom the base of the heart to near the first rib. 

The first group receives the posterior lymphatics of the oesophagus, the 
second those of the lung, and the third those of the pericardium, heart, 
and a portion of the trachea and esophagus. Their efferents, uniting into 
some large trunks, enter the thoracic duct at different distances. 


GLANDS AND LYMPHATIO VESSELS OF THE THORACIO WALLS. 


These glands form three series: 1, A double chain of rounded grains, 
situated on each side of the dorsal column, above the intercostal spaces, and 
beneath the costal pleura; 2, A frequently voluminous mass, lodged at the 
base of the xiphoid appendix, behind the heart, and in front of the inferior 
part of the diaphragm; 3, Some rudimentary granulations lying beside the 
internal thoracic vessels. 

The lymphatics of the diaphragm, after receiving those from the convex 
face of the liver, pass to the glands placed at the base of the muscle. frow 
which they escape in the form of several canals that accompany the 
internal thoracic vessels, and open into the anterior extremity of the thoracic 


AFFLUENTS OF THE THORACIC DUCT. 648 


duct or the great lymphatic vein, the majority of them through the medium 


ad Prepectoral glands. These vessels receive, on their course, those 
which are brought from the inferior part of the intercostal spaces into the 
suprasternal eranulations, 


oe other lymphatic vessels of the costal wall ascend between the two 
muscles which close these spaces, and go to the subdorsal glands, which 


afterwards eject them, near the origin of the thoracic duct, in the form of 
one or two long vessels proceeding in a retrograde manner on each side of 
the dorsal column, 


* 


LYMPHATIC VESSELS OF THE HEAD, NECK, AND ANTERIOR LIMB. 


These vessels are all directed towards the entrance to the chest, and are 
gathered into a group of glands, called the prepectoral, which, with regard 
to the lymphatics of the anterior part of the body, play the same part as 
the sublumbar glands do to the vessels of the posterior region. 

Before arriving at this common point of convergence, they are inter- 
cepted on their course by other glands, which form four principal groups: 
1, The guttural or pharyngeal glands; 2, The submaxillary glands; 8, ‘The 
prescapular glands ; 4, The brachial glands. 

In studying these different glandular groups in succession, with their 
afferent and efferent vessels, we will give a sufficient idea of the entire 
lymphatic apparatus in the region which remains for us to examine. 


1. Prepectoral Glands. 


They form, on each side of the terminal extremity of the jugular, within 
the inferior border of the scalenus muscle, a very large mass which extends 
into the chest by passing beneath the axillary vessels, and ascends to the 
inner face of the first rib. 

Into these glands pass the lymphatic vessels emerging from the pre- 
scapular and axillary glands, those which descend along the trachea with 
the common carotid, and which come from the pharyngeal glands, as well 
as the majority of those which follow the internal thoracic vessels. 

They give rise to several short and voluminous branches: those from 
the glands of the right side form, by their junction, the great lymphatic 
vein; and those from the left side join the thoracic duct, or are inserted 
separately beside the latter, at the summit of the anterior vena cava. 


2. Pharyngeal Glands. 


Very numerous, soft, and loosely united to one another, these glands are 
disposed in an elongated mass that occupies the lateral plane of the pharynx, 
below the guttural pouch, and which is prolonged backwards even beyond 
the thyroid body. ; 

They receive all the lymphatics from the head: some come directly 
from the base of the tongue, the soft palate, the pharyngeal walls, and the 
larynx ; the others are derived from the submaxillary glands, and from a 
lobule lodged in the substance of the parotid gland. 

The efferent branches which leave it are four or five in number. 
Always voluminous, they descend along the trachea, some separately, but 
the majority are united in a fasciculus which follows the carotid artery; 


1 These are glands, we believe, which ought to be regarded as the representatives of 
the axillary glands of Man. 


644 THE LYMPHATICS. 


they are provided on their course with several elongated glands, to which 
the lymphatic radicles that arise from the cervical portion of the trachea 
and cesophagus pass. On arriving near the entrance to the chest, they are 
lost in the prepectoral glands. Some of them, however, traverse these 
without dividing, and directly enter, on the left, the thoracic duct, and on 
the right, the great lymphatic vein. It has been even possible for us to 
inject the latter vessel by one of these canals exposed on the right side. 


3. Submaaillary or Subglossal Glands. 


They represent a fusiform mass situated at the bottom of the inter- 
maxillary space, in the receding angle comprised between the digastricus 
on the one side, and the mylo-hyoideus and subscapulo-hyoideus muscles on 
the other. above and near to the external maxillary artery. The lymphaiics 
of the tongue, cheeks, lips, nostrils, and nasal cavities join these glands, 
Their efferents reach the pharyngeal or guttural glauds. 


4, Prescapular Glands. 


By their union they form a species of chain, at least twelve inches in 
length, placed on the course of the ascending branch of the inferior cervical 
artery, beneath the internal face of the levator humeri muscle, and descend- 
ing close by the fixed insertion of the sterno-maxillaris muscle. 

The majority of the lymphatics of the neck, and those of the breast and 
shoulder, open into these glands. Their efferents, short and voluminous, 
enter the prepectoral glands. 


5. Brachial Glands, 


Situated beneath the anterior limb, within the arm, these vessels are 
divided into two groups: one placed near the ulnar articulation, within the 
inferior extremity of the humerus; the other disposed in a discoid mass 
behind the brachial vessels, near the common insertion of the adductor 
muscle of the arm and the great dorsal muscle. 

The first group receives the vessels from the foot and the fore-arm, 
which accompany the superficial veins, or pass with the deep arteries and 
veins into the muscular interstices. It sends nine or ten flexuous branches 
to the second group, into which open directly the lymphatics of the arm 
and shoulder, and from which emerge a certain number of efferents that 
pass, in company with the axillary vessels, to the prepectorat glands. 


ArtioLe JII.—Great Lympuatric Vet. 


The second large receptive trunk of the lymphatic vessels, this great 
vein (the ductus lymphaticus deater) leaves the prepectoral glands of the right 
side, and therefore becomes the general confluent of the lymphatics from 
the right anterior limb, the right axillary and superficial costal regions, 
as well as the right half of the head, neck, and diaphragm. 

This trunk is only from three-fourths of an inch to two inches in length. 
“Tt usually opens at the junction of the jugulars, at the side of the canal, 
by an orifice furnished with a double semilunar valve. Sometimes one or 
two of the branches which concur to form it describe cireumvolutions around 
the corresponding brachial trunks or some of its divisions, before joining 
the others, Lastly, it is not rare to see this lymphatic trunk anastomose 


GREAT LYMPHATIC VEIN. 645 


with the thoracic duct by voluminous collateral branches, then unite with 


it in such a way as to be inserted t i i 
a ihe lagules are rted together by a single orifice above the gulf 


Fig. 303. Fig. 304 


THE GREAT LYMPHATIC VEIN AND ENTRANCE OF THE THORACIC DUCT. 


A, Thoracic duct; B, Great lymphatic vein, or right lymphatic trunk ; c, p, Anasto- 
moses established between them near their insertion. ; 


DIFFERENTIAL CHARACTERS IN THE LYMPHATIC SYSTEM OF OTHER THAN SOLIPED ANIMALS. 


The lymphatic system, glands and vessels, is mo: i i 
Pig than fie ek aaa re developed in Ruminants and the 

In this respect the domesticated animals may be classified i i rder : 
Gis, Sheep, Horan, Pig; Dog, Cat, y ssified in the following order: 

Ruminants.—“ The thoracic duct of large Ruminants, when it has entered the thorax 
by a special opening in the diaphragm, almost distinet from that of the aortic arch, is 
placed above and to the right of the aorta, between it and the spine. There. although 
outside the corresponding intercostal arteries, it is completely concealed by a thick layer 
of adipose tissue, in which are numerous subdorsal glands. Towards the fifth dorsal 
vertebra, it receives a large lymphatic vessel coming from the enormous gland that exists 
on the track of the cesophagus in the posterior mediastinum; it then crosses the direc- 
tion of the aorta and the cesophagus, passes to the left, gains the entrance to the thorax, 
and opens in front cf the first rib, above the junction of the left jugular with the anterior 
vena cava.! 

“ The varieties it presents in the Ox are numerous and very common. The xarest 
disposition is that of a canal, single through- 
out its entire length, such as it has been Fig 305. 
described, and such as it is usually found 
to be in small ruminants (Fig. 309). This 
canal (Fig. 306), single at its origin and 
for the greater partof its extent, often bifur- 
cates towards the base of the heart, or ata 
short distance from its insertion. Of these 
two branches, one passes to the right of the 
cesophagus and trachea, the other to the left 
of these, in following the ordinary direction ; 
and, at the entrance to the thorax, they either 
terminate separately, each in the angle of 
union of the jugular and corresponding axil- ENTRANCE OF THE THORACIC DUCT IN 
lary vein, or together at the same point—the THE OX. 


gulf of the two jugular veins. 
“Tt happens that one of the branches of the bifurcated canal is in its turn subdivided 


into two smaller branches, and that the other experiences at the same time a similar 


(1 Zundel has pointed out the curious fact, that in Ruminants, the long, special, 
lymphatic gland situated between the layers of the mediastinum and above the cesopha- 
gus, sometimes becomes so voluminous that its weight impedes rumination, especially 
when the animal is lying. The bolus of food is prevented from ascending into the 
cesophagus, and this may become a frequent and periodic cause of indigestion.) 

44 


THE LYMPHATICS. 


646 
ivision : i h a way that the trunk of the canal, at first single, becomes double, 
Ph eran a ereenwantly opens into the venous. system by four distinct orifices. 


Fig. 306 


VARIETIES OF THE THORACIC DUCT IN THE OX. 


If the branches of the canal, instead of remaining isolated. send off transverse anastomoses, 
there results a complication of which Solipeds do not offer an example (Fig. 305), 
* The thoracic duct is often double throughout its extent. The two canals are then 


THE CIRCULATORY APPARATUS OF BIRDS. 647 


ae ed separately from the cistern, one follows the right side, the other the left side of 
the aorta, describing an arch whose concavity is downward at the base of the heart, on 
the lateral parts of the trachea, terminating either very near one another, and on the same 
transversal line, at the Junction of the two jugulars, or one to the right, the other to the left, 
in each of these two veins, and not far from their junction with the axillaries (Fig. 307.) 
When the two canals arise from the sublumbar reservoir, they sometimes repeatedly 
anastomose with each other by sinuous and curved branches, as shown in figure 308. 


Fig. 309 


THORACIC DUCT OF SMALL RUMINANTS. 


“Then all the branches collect in the anterior mediastinum, and constitute a single 
canal which, near its termination, again subdivides into four vessels that open sepurately, 
two to the right and two to the left, in the usual place. 

“This variety is the most remarkable and complicated of all those observed in the 
domesticated animals. 

Pic.— The thoracic duct of the Pig, usually single throughout its whole extent, 
is sometimes divided, at one to one and a-half inches from its insertion, into two branches 
which soon reunite in an oval dilatation ; this, after receiving the vessels from the head, 
neck, and limbs, opens towards the extremity of the left jugular. 

Carnivora.‘ In the Dog, Pecquet’s reservoir is enormous; in shape it is ovoid, 
and is prolonged between the pillars of the diaphragm into the thoracic cavity. The 
thoracic duct of this animal generally resembles that of the Pig. Yet it sometimes 
offers in its course and termination very numerous variations: Rudbecky has noticed a 
bifurcation above the heart, and another bifurcation whose branches anastomose with 
each other several times. Swammerdam and Stenon have figured numerous irregular 
anastomotic divisions towards the middle of a single canal, to its point of departure. These 
old authors have indicated and represented double and triple insertions of different 
forms. Lastly, Bilsius has shown an arch, or rather a very remarkable ring, at the 
entrance of the conduit, and at its junction with the lymphatic vessels of the neck and 
anterior limbs, and which is more or less analogous to that which I have observed on 
several occasions in the Horse, Pig, and Cat.”? 


CHAPTER III. 
THE CIRCULATORY APPARATUS OF BIRDS. 


We will briefly examine the characteristics of the different portions of the circulatory 
apparatus—the heart, blood-vessels, and lymphatic vessels—of birds. 


ArTIcLe I—THE Heart. 


The heart, in birds, is situated quite at the entrance to the chest, in the median line, 
and is contained in a pericardium that adheres to the posterior diaphragmatic septum 


1 G. Colin, op. cit. 


648 THE CIRCULATORY APPARATUS OF BIRDS. 


and the cervical reservoir. In the domesticated species, it has the form of an acute cone, 
whose base is surmounted by a less distinct auricular mass than in the Mammalia. __ 

Internally it has four cavities. The right ventricle is more crescent-shaped than in 
Solipeds, and in a manner envelops the lett ventricle in front and to the right; it does 
not reach the point of the heart. The auricular valve is not tricuspid, and offers a very 
remarkable arrangement. “This valve, in fact, instead of being formed as usual by 
membranous curtains Whose margin is retamed by cords fixed to the walls of the 
ventricles, is composed of a wide muscular leaf which appears to be a portion of the 
inner wall of the ventricle detached from the interventricular septum, ‘his septum is 
convex, and the auriculo-ventricular orifice is situated in the space comprised between it 
and the muscular valve in question; so ee when the latter contracts at the systole, it is 

lied against this septum and closes the passage. 
wee There is nothing Paetianine to note with regard to the left ventricle, whose walls 
are likewise thicker than those of the right. : : : : 

The auricles have a kind of diverticulum or sinus, in which the veins that open into 
each of these cavities unite. 


ARTICLE IJ.—TuE ARTERIES. 


The aorta of Gallinaceous birds ascends beneath the lower face of the right lung, then 
turns abruptly backwards and a little to the left. It attains the median line towards 
the anterior extremity of the kidneys, and in this situation it reaches the sacral vertebra, 
where it divides into three branches—the arteries of the pelvic limbs, and the middle 
sacral artery. 

Close to its origin, the aorta gives off the brachio-cephalic (or innominate) trunks. 
With the Fowl this name is perfectly correct, as they both furnish vessels to the wings 
and head. The right passes upwards and forwards, is inflected backwards at the first 
rib, and continued on the lower face of the wing by the humeral artery. It throws off a 
thoracic artery, whose volume is in relation with that of the pectoral muscles; this artery 
emits superficial branches that form in the skin of the abdomen, with other vessels, a 
very rich plexus named by Barkow the rete mirabile of incubation. It afterwards gives off 
a cephalic trunk, from which arise the ascending cervical, vertebral, and right carotid 
artery. The left brachio-cephalic trunk has the same distribution as the right, a slight 
difference only being observed in its direction ; on leaving the thoracic cavity it describes 
a small § curvature. . 

The carotid arteries exhibit a somewhat curious arrangement. Each springs from 
a corresponding brachial trunk; and placed at first on the sides of the neck they make 
a curve, whose convexity is anterior, and gain the median line by passing, the right 
above the oesophagus, the left above the trachea. They remain beside each other, 
beneath the longus colli, from the second last to the second cervical vertebre, where 
they separate at anacute angleand reach the border of the jaw, terminating there in 
two branches—the internal and external carotid arteries. 

The other collateral branches furnished by it, are: 1, The intercostal arteries, These 
may arise from the subcostal branches which are parallel to the aorta; thus. in the Fowl, 
there is a common descending intercostal which proceeds from the vertebral, and a common 
ascending intercostal that leaves the aorta as it passes into the abdomen; 2, The 
celiac trunk, which commences at the middle of the lower face of the lung, and descend- 
ing obliquely backward, reaches the posterior aspect of the liver. It divides into several ; 
ramuscules, of which there are three principal vessels: a very fine one goes to the 
spleen; a left or middle one passes to the gizzard along the proventriculus; the third, 
more voluminous, is directed to the right side, gives a twig to the liver, and is continued 
by a long pancreatico-duodenal branch that joins the extremity of the loop which the 
intestine forms at its origin; 3, The anterior or superior mesenteric, which arises at a short 
distance behind the coeliac trunk, enters the mesentery, and is directed backwards, 
describing a curve whose convexity is antero-inferior, and which emits twigs to the 
intestine; 4, The spermatic or ovarian arteries. The inferior or posterior mesenteric 
leaves the subsacral artery, and, by some ramuscules, reaches the rectum and cloaca. 

Shortly before its termination in three branches, the aorta gives off an artery that 
crosses the middle portion of the kidneys, leaves the abdominal cavity, and becomes dis- 
tributed to the anterior muscles of the thigh, after detaching the epigastric artery. The 
latter proceeds forward, beneath the skin of the abdomen, and anastomoses with the 
ramificutions of the thoracic artery. 


1 Milne Edwards— Legons sur la Physiologie et Anatomie Comparée de YHomme 
et des Aniinaux.’ Vol. iii. 


THE CIRCULATORY APPARATUS OF BIRDS. 649 


The arteries of the pelvic limbs—the femoral or crural, in passing above the kidneys 
furnish the renal arteries ; they then leave the pelvis by the great ischiatic notch, im. 
mediately behind the coxo-femoral articulation. Placed beneath the muscles on the 
posterior face of the thigh, in following the branches of the lumbo-aacral plexus as far 
as the femoro-tibial articulation, they are then continued by the popliteal vessels. These 
arteries throw off articular ramuscules, the medullary artery of the tibia, and a long 
branch to the muscles on the posterior aspect of the leg ; they are placed in the groove 
resulting from the junction of the tibia and tibula, and pass through the osseous inter- 
space to form the anterior tibial arteries, 

‘The middle sacral continues the aorta to the bottom of the pelvis; when it arrives 
below the last coceygeal vertebra, it forms a kind of arch whose ramifications are dis- 
tributed among the muscles and quills of the tail. 


Antics Ill.—Tur Vets, 


As in Mammals, the veins are distinguished as belonging to the great and lesser 
circulation. 

The veins of the great circulation are collected into three trunks that open into the 
right auricle of the heart; there are two anterior vene cave and one posterior vena cava. 
They enter a particular compartment, a kind of sinus, in the auricle. 

‘The anterior vene cave collect the blood from the subclavian arteries and those of 
the head. The jugular veins, which are their principal branches, are not the satellites 
of the carotid arteries, as in the larger domesticated animals; they are superficial and 
placed on the sides of the trachea; while the carotids are placed in the median line, 
beneath the long flexor muscle of the neck. They are not of the same calibre in all 
species, the right jugular being more voluminous than the left ; there is always, however, 
a transverse anastomosis between the two jugulars, below the base of the cranium. 

The posterior or inferior vena cava commences at the anterior extremity of the 
kidneys, and passes forwards, traversing the right portion of the liver, receiving the 
hepatic veins, and enters the right auricle. 

Among the branches forming it, there may be cited the femoral or crural veins. 
These vessels do not accompany the corresponding arteries; not entering the pelvic 
cavity by the great ischiatic notch, they pursue a course analogous to that described for 
tiese vessels in Solipeds, in passing beneath the crural arch. 

In birds furnished with a crest and mandibles, the skin of the head is provided with 
an excessively rich vascular plexus. 


ArricLE [V.—Tue Lympwarics, 


Birds possess lymphatic vessels and glands. The latter are few, and are scarcely met 
with elsewhere than in the cervical region ; the former are abundant in the viscera, and 
unite in such a manner as to form two thoracic ducts. These ducts commence at the 
cceliac trunk, and pass along the lower face of the lung, receiving the lymphatics of that 
organ and those of the wings, and finally open into the jugular veins, a little in front of 
their unicn with the axillary veins. A transverse branch forms a communication 
between the two thoracic ducts, towards their termination. 


BOOK VI. 
APPARATUS OF INNERVATION. 


FIRST SECTION. 


THE NERVOUS SYSTEM IN GENERAL. 


Tur functions whose instruments we have just described, suffice in them- 
selves to maintain nutrition—that mysterious molecular movement which is the 
ultimate object of the activity of organs, and the essence even of life: loco- 
motory acts which permit the animal to seek its food and to introduce it into 
its organism, lead to the elaboration and absorption of the assimilable 
materials of the alimentary mass in the interior of the digestive cavity, the 
circulation of the reparative fluids in the economy, and the depuration and 
revivification of these fluids by the action of the lungs and the kidneys: in 
brief, could anything more be required to constitute the conditions necessary 
for the manifestation of the nutritive phenomena ? 

And yet, while the anatomist conceives in his mind a vertebrate animal 
exclusively endowed with the apparatus destined to execute these functions ; 
while he supposes the breath of life and the dependent properties of that 
animating principle to be due to these apparatus, he could not succeed in 
creating an imaginary being capable of moving, digesting, keeping in circula- 
tion the nutritive fluids, reviving these fluids by respiration and urinary depu- 
ration—in a word, of executing all those acts whose concurrence is indispens- 
able to the maintenance of nutrition, the supreme vital act. It is because the 
tissues of that animal, though possessing the organic properties inherent in 
their structure, require an excitant capable of bringing these properties into 
play. Their inertia is due to the absence of this excitant; for all motion, 
no matter what kind it may be, demands for its realisation, not only the 
motor faculty in the organ which executes it, but also an excitatory cause. 

But give to this mutilated organism, this creation of our fancy, white 
cords, ramifying by extremely slender divisions in the depth of these 
instruments of life, and commencing from a central axis lodged in the 
cranium and spinal canal; or, in other words, add to our incomplete 
animal an apparatus of innervation, and, as-if by enchantment, there will 
appear the first signs of life. Owing to the peculiar properties which dis- 
tinguish the tissues of this apparatus, and concerning which we will have 
more to say hereafter, it plays the part of an excitor and regulator with regard 
to the properties of the other tissues. Stimulated by the nervous system, these 
properties no longer remain in a latent state, but manifest themselves by 
their usual results—such as contraction in the muscles, and exhalation 
and secretion in the membranes and glands; then the imperfect being at 


once begins to digest, respire, ete.—in a word, to live, and is worthy of 
taking rank in the animated world. 


THE NERVOUS SYSTEM IN GENERAL. 651 


But the effects of this radical transformation do not cease here. Tho 
animal thus rendered apt to the nutritive movement acquires, beyond thig 
vegetative life, the common appanage of all organised beings, all the attributes 
of what it has become habitual, after Bichat, to term animal life,—that is, 
sensibility, volition, instinct, and intelligence. 

The perceptive centre which receives the excitations developed at the 
periphery of organs, or in their structure; the excitatory centre which 
induces motion in all the other tissues; the seat of the instinctive and 
intellectual faculties ; in short, does not the apparatus of innervation, thus 
charged with the grandest physiological finality, present itself as a most 
attractive study ? We will commence by giving a general and succinct idea 
of its conformation, structure, properties, and functions, before undertaking 
the special description of the different parts composing it. 


GENERAL CONFORMATION OF THE NERVOUS SYSTEM. 


The apparatus of innervation comprises a central and a peripheral 
portion. 

The first represents a very elongated stalk lodged in the spinal canal, 
and bulging at its anterior extremity, which occupies the cranial cavity. 
This is named the cerebro-spinal axis or centre. 

The second consists of a double series of ramescent branches, which are 
given off laterally from the central stalk, to be distributed to all parts of 
the body ; these branches are the nerves. 

Tue Crrepro-spinaL Axis.—The stalk, or aais properly so called, 
lodged in the spinal canal, forms the spinal marrow (or cord). It is a large 
white cord, terminating in a point at its posterior extremity, and giving rise, 
at each intervertebral foramen, to one of those nervous branches which, collec- 
tively, represent the peripheral portion of the apparatus of innervation. 

The bulging extremity inclosed in the cranium, is named the encephalon 
(or brain). More complicated in its conformation than the spinal cord, this 
portion is divided, as we will see, into four parts: 1, A white peduncle, the 
continuation of the spinal cord; 2, Three grey-coloured ovoid masses, one 
of which is posterior, the other two being anterior, and placed symmetrically 
side by side. This medullary prolongation emits, right and left, like the 
cord itself, nervous branches destined almost exclusively for the head. 

Tre Nerves.—The nerves are in the form of fasciculated cords, and 
make their exit from the orifices at the base of the cranium, or through the 
intervertebral foramina, passing into all the organs by ramifying like 
arteries, which they generally accompany. . ; 

All the nerves have their origin from the medullary axis, or from its 
encephalic prolongation, by radicles more or less apparent. They are 
divided, according to the relative position of their point of emergence, into 
two great categories ; the superior, arising from the corresponding face of 
the spinal axis ; the others, énferior, escaping from the lower face: a distinc- 
tion which is perfectly appreciable with regard to the cord itself, but which 
is more difficult to establish in the encephalic peduncle, as it is less 
distinct. Be. 

At their emergence from the bony canals which give them passage, 
the radicles of each nerve always unite into a thick common trunk. 

In the majority of cases, there enters into the composition of this trunk 
the nerves or fibres of the two orders; only a few nerves are composed of 
fibres of the one kind, and these all belong to the brain. 


652 THE NERVOUS SYSTEM IN GENERAL. 


At the origin of the trunk into which the nerve roots are collected, 
there is a greyish enlargement termed a ganglion; but this peculiarity 
belongs exclusively to the superior fibres. aa 

After a variable course, which is generally short, this trunk divides into 
branches, the point of departure for all the nerves of the body. Among 
these branches, those which are expended in the apparatus of animal life are 
pairs, and perfectly alike on both sides of the body. Those of the organs 
of nutrition are composed at first of an almost symmetrical double chain, 
placed beneath the spinal column, and whose elements are borrowed from 
nearly all the nervous trunks emanating from the cerebro-spinal axis; in 
proceeding to their destination, their distribution is most irregularly com- 
plicated. As they offer on their course a great number of ganglia similar to 
those we have already mentioned, they are called ganglionic nerves ; they are 
also designated the nerves of organic or vegetative life, while the others are 
named the nerves of animal life or of relation. 


STRUCTURE OF THE NERVOUS SYSTEM. 


Two particular substances, one grey, the other white, enter into the 
organisation of the nervous apparatus. These two substances are formed, 
the first by nerve-tubes and united nerve-cells; the second by tubes alone. 

The nerve-tubes are microscopic elements, composed of a proper wall and 
contents. The wall, named the nervous sheath (sheath of Schwann), is a thin, 
homogeneous, elastic membrane that contains in its substance or its inner face 
some nuclei of cells. It is not visible in quite fresh tubes. The contents 
comprise, in the centre, a solid core, the aais-cylinder 
(or primitive band of Remak), which becomes very appa- 
rent after the addition of certain reagents; between the 
axis-cylinder and the wall is found a viscid substance, the 
nervous medulla or white substance of Schwann, which 
coagulates very quickly under the influence of cold. 

When the medulla is solidified, it is seen to be 
bordered by two dark lines, parallel to the walls of the 
nerve-tubes; this aspect has caused the latter to be 

named “ double-contoured tubes (or nerve-fibres).” 

DIAGRAM 7 OF SSTRUC: All the nerve-tubes do not possess, at the same time, 
TURE OF NERVE 

PinRR: these three parts, for the medulla may be absent; so that 

1, Sheath; 2, Medul- there are distinguished medullated and non-medullated 

lary substance of nerve-fibres. The first, more or less thick, are met with 

Schwann; 3, Axis- in the nervous centres, and at the origin, and in the 

ic nel or primi- middle portion of the nerves 3 the second are found at 

. the termination of nerves, and in the great sympathetic. 

There are also observed in the nerves of organic life, elongated elements, 
designated fibres of Remak, grey fibres, and nucleated nervous fibres. These 
are pale, flattened fibres, with parallel borders, and furnished with elliptical 
nuclei. Some authorities consider these to be bands of connective tissue, and 
not nerve elements. 

The nerve-cells, or corpuscles, are voluminous, and are formed by a mass 
of granular protoplasm without any enveloping membrane. In the ganglia 
they are covered by a layer of fibrous connective tissue, provided with nuclei, 
which appear to furnish them with a very thick enveloping membrane. The 
nucleus, with one or two nucleoli, is often surrounded by granulations, 
whose dark colour gives rise to the supposition that they are pigment cells. 


Fig. 310. 


THE NERVOUS SYSTEM IN GENERAL. 653 


The nerve-cells have prolongations or poles, whose number varies from one 
to five. Cells with only one prolongation are named unipolar; those which 
have two are bipolar; and those which have a greater number are designa- 


ted multipolar. These poles establish relations with the nerve-tubes and 
constitute the origin of the nerves. ; 


Fig. 311. 


MULTIPOLAR OR STELLATE GANGLIONIC NERVE-CELL, WITH ONE OF ITS 
PROLONGATIONS— 


a, Becoming continuous with the axis-cylinder of a double-contoured nerve-fibre, 5. 


Such are the anatomical elements that enter into the structure of the 
nervous system. 

In the white substance of the cerebro-spinal axis, only medullated nerve- 
tubes of every size are found ; in the grey substance are tubes, and a more 
or less considerable number of nerve-cells are situated along their course. 

To these two elements is added a large quantity of blood-vessels, which 
are incomparably more abundant in the grey than in the white substance. 

In the nervous cords, the elementary tubes are alone met with; they are 
disposed in long bundles, which are collected into successively increasing 
fasciculi. A cellulo-vascular envelope, the neurilemma (or perineurium}, 
binds all these fasciculi into a single cord, and forms a special sheath 
around each of them. The details of their organisation will be referred to 
hereafter. 

It is admitted that the ganglionic, or nerves of organic life, possess a 
greater quantity of slender tubes than the others. These tubes are com- 
monly designated as the organic nerve fibres. They also contain fibres of 
Remak. 

In the ganglia, the cells are joined to the nerve-tubes. It has been shown, 
by dissection and microscopical observation, that the corpuscles composing 
the ganglia at the origin of the trunks are all attached to the superior 
fibres, ‘The other tubes have none. 

In the cerebro-spinal axis, the two substances are equally associated with 
each other, but in a variable manner, according to the region. In the cord 


654 THE NERVOUS SYSTEM IN GENERAL. 


and its prolongation into the encephalon, the grey substance occupies the 
interior, while it is spread over the exterior of the encephalic lobes and 
envelops the white substance. 


Fig. 313, 


MICROSCOPIC GANGLION FROM HEART BIPOLAR GANGLIONIC CELLS AND NERVE- 
OF FROG. FIBRES, FROM GANGLION OF FIFTH PAIR 
IN LAMPREY. 


(In some instances, as in the cells of various parts of the spinal cord, 
the prolongations subdivide and ramify in a curious manner, and form a close 
network that penetrates the surrounding nervous tissue. In addition to 
these. there are other very complex nerve-cells whose structure has only 


Fig. 815. 
Fig. 814. 


8TELLATE NERVE-CELL, FROM THE 
NUCLEUS CERVICIS CORNU (Pos- 


TERIOR VESICULAR COLUMN) OF STRUCTURE OF GANGLIONIC NERVE-CELL, 

A FETUS OF SIX MONTHS, A, According to Beale; B, According to 

MAGNIFIED 420 DIAMETERS. Arnold.—a, Straight fibre; 6, Double 
spiral fibre; c, Capsule of connective 
tissue. 


recently been clearly established. These have been found in the sympathetic 
ganglia, and each is invested in a capsule of connective tissue. In shape, 
the cell is pyriform, and it contains a nucleus; from the narrow end spring 
two fibres, that pass in opposite directions when they reach the nervous 


THE NERVOUS SYSTEM IN GENERAL. 655 


bundle to which they are distributed. This disposition has given rise to the 
opinion that every nerve-fibre, no matter how long its course may be, is a 
loop that originates in, and returns to, the same cell. One of the fibres that 
enters the cell, and looks like a stalk to it, is usually straight; the other 
seems to arise from the outside of the cell, is sometimes double, and circles 
round the other in a spiral manner two or three times. Both fibres at first 
resemble the cylinder-axis of ordinary nerve-fibres, and may subsequently be- 
come dark-bordered, or remain pale fibres. The spiral fibres bear large oblong 
nuclei in their course. Some observers state that they have traced the 
straight fibre into the nucleus, and the spiral fibre into a plexus on the 
exterior of the cell, but which may be ultimately traced into the nucleolus ; 
so that the two fibres are continuous through the nucleus and nucleolus). 


PROPERTIES AND FUNCTIONS OF THE NERVOUS SYSTEM. 


It would require a long chapter to do justice to this subject, and we 
could not venture on it here without going beyond our domain. We will, 
however, offer some remarks on those notions connected with the properties 
and functions of the nervous system which are strictly necessary for the 
comprehension of the anatomical facts to be hereafter dealt with. 

And first as to the properties of the nerves. 

We will suppose the spinal canal to be opened in the lumbar region, and 
the cord laid bare in a living animal. If we cut across the inferior roots of 
one of the spinal nerves, and if we compress with a pair of forceps one or more 
of these roots, by the end remaining attached to the cord, nothing results 
to denote that this irritation has had any influence on the organism. But 
if, instead of operating on the central or attached end of these divided roots, 
we excite the peripheral end which is continued by the trunk of the nerve, 
contraction of the muscles of the limb which receives the fibres coming 
from the irritated roots is produced, 

The muscular tissue comports itself as if the irritation were directly 
applied to it; so that the nerve has served as the medium of communication. 
It has received the excitation, it has been tmpressioned by it, and it has 
conducted this to the muscles to which the nerve is distributed. This 
double reaction produced by the nervous tubes is their special attribute, 
their essential property. With M. Vulpian we might designate it as a whole 
by the name of neurility ; but it is necessary to distinguish the two modes it 
affects by naming the property of being impressed by excitations as the 
excitability of the nerve, and nervous conductibility its aptitude to convey the 
excitations which have impressed it. 

The same experiment may be repeated on the upper roots. It is then 
perceived that the pinching, which produces no effect at the peripheral 
extremity, causes pain when applied to the central end. The animal 
testifies immediately, by cries and movements, that it feels the touch of the 
forceps. But, as will be mentioned in a moment, the impression resulting 
from this touch has only been perceived by the brain ; it has therefore been 
conducted to the spinal cord by the excited nervous fibres, and then to the 
brain by the fibres of this medullary axis. 

In putting to one side, for the moment, the part played by the latter in 
the phenomenon now analysed, it will be seen that the superior fibres of the 
spinal nerves enjoy the same attributes as the inferior ; neurilily is their 
appanage, and this property is apparent in its two qualities—excitability and 
conductibility, Only here the latter property is exercised in a centripetal 


656 THE NERVOUS SYSTEM IN GENERAL. 


sense; while in the first instance it acted in a centrifugal sense. But it must 
not be assumed that these two conductibilities are essentially distinct. The 
physiological differences by which they appear to be distinguished seem to 
belong to the difference in the relations of the nerve-fibres with the organs 
to which they are distributed. In one case, that of the centrifugal nerves, the 
organs of reaction—the muscles—are placed at the peripheral extremity of 
the nerves; in the case of the centripetal nerves, the organs of reaction— 
the brain and spinal cord—are found at the central extremity of the nervous 
fibres. This theory of the unity of nervous conductibility has, moreover, 
been proved to be correct by the researches of Philipeaux and Vulpian, who 
have utilised the experiment of Gluge and Thiernesse on the union of the 
central end of the lingual (centripetal) with the peripheral end of the 
hypoglossal nerve (centrifugal), to demonstrate that the fibres of the former 
then acquire centrifugal conductibility. 

It is easy to demonstrate that this double property of conduction belongs 
to all the nerve-fibres springing from the cerebro-spinal axis, centripetal 
conductibility being peculiar to the superior fibres, and centrifugal conducti- 
bility to the inferior ones. It is also demonstrated that this conduction acts 
in either one sense or the other, whatever may be the point on the course of 
the nerves so stimulated ; as the nerve-tubes possess, throughout their whole 
length, the property of excitability and conductibility. 

The fibres with centrifugal conductibility constitute the motor nerves ; 
those whose conductibility is centripetal are the sensitive nerves. But sensi- 
bility does not exist only in the filaments of the superior roots; it has also 
been remarked in the lower roots, and they owe it to the filaments which 
are given off from the roots whose conductibility is centripetal, and which 
return to the nervous centres by the motor roots. The sensitiveness evinced 
by these motor roots is named recurrent sensibility. 

The anatomical and physiological characters of the nerves persist as 
long as they communicate with the centres. If they are divided at any part 
of their course, the portion attached to the spinal axis still preserves its 
properties; but that situated beyond the section—the peripheral end, as it 
is named—degenerates, and becomes incapable of conducting the sensitive 
impressions, or of transmitting the voluntary motor excitations. 

Now as to the spinal cord. 

Does the medullary axis, which has apparently, in great part, the 
structure of a nerve, possess, like the latter, eacitability and conductibility, 
those two essential properties of the peripheral nervous system ? 

Excitability is entirely absent in the grey substance. On the surface of 
a section of the cord, the slightest, or even the most intense irritation of this 
portion produces no reaction. In the white substance, this excitability can 
only be easily rendered evident on the surface of the upper bundles or 
fasciculi, where it is exquisite. With regard to the always limited reactions 
observed when the excitations are made on the deep part of the fasciculi, it 
is difficult to say if they result from the excitability of the spinal cord, or 
that of the nerve roots that traverse the white substance. 

Nervous conductibility is certainly one of the attributes of the spinal 
cord; the transmission of excitations of the sensitive nerves to the brain, 
and the voluntary movements that result from stimulation of the motor 
nerves, demonstrate that the necessary medium between the nerves and 
brain—the spinal cord—possesses conductibility. But does this portion of 
the nervous system possess no other property? Yes; it may act as a 
nervous centre, and the following experiment irrefutably demonstrates it: 


THE NERVOUS SYSTEM IN GENERAL. 657 


I will suppose that an animal has had its spinal cord cut across in the 
lumbar region, and I excite, by pinching, one of the superior roots re- 
maining intact on the caudal portion. The stimulus cannot be conducted 
to the brain, as this part is isolated from it; and yet movements take place 
in the muscles of the posterior members. Does it happen that, after section 
of the medulla, the conductive property of the nervous fibres which originate 
superiorly is interverted and changed into centrifugal conductibility? No; 
for after the transverse section of these roots, the irritation of their central 
end produces exactly the same effects. It must be, therefore, that the 
excitation had first reached the medulla, and was then transmitted by it to 
the muscles by means of the centrifugal current fibres. And this is really 
what occurred ; the section of the whole of these fibres on the trunk of the 
cord hindered the manifestation of all movement in the muscles when the 
superior roots were touched. There is, as has been said, reflexion in the 
substance of the cord, on to the inferior roots, from the irritation due to this 
pinching, and the property which permits the medullary axis to act in this 
manner is named the reflex power. It may be remarked that, if we suppose 
for a moment the superior and inferior nervous Yoots to be united in an 
arch in the substance of the spinal cord, this reflex property would be 
nothing more than the nervous conductibility itself operating precisely in the 
direction special to each kind of nerves. 

This union really takes place; only the nerve-roots are not in communi- 
cation, except through the medium of the cells in the grey substance, in 
which the sensitive is changed into motor excitation. * 

The reflex power is extinct immediately after death occurs in Mammals, 
but it may last for several hours, or even for a day, in a decapitated animal 
in which asphyxia has been averted by pulmonary insufflation. The extent 
of the movements it determines is in relation to the intensity of the stimulus 
which is the primary cause of it; merely localised when they result from 
a slight irritation, these movements may take place in all the muscles of the 
body after an energetic stimulation. 

Let us now inquire into the attributes of the encephalon. 

Excitability is not remarked in all parts of the brain; it exists in 
several points of the medulla oblongata, and in the deep substance of the 
cerebellum; but it cannot be rendered evident on the surface of the latter, 
nor yet in the cerebral hemispheres. The brain possesses conductibility, 
because the grey substance composing it is the receiver of, and the point of 
departure for, all the excitations. In fine, the encephalic mass should 
possess neurility like the nerves, but this general property is more or less 
modified. What more particularly distinguishes the encephalon is its action 
as a sensitivo-motor centre; in it arrive the excitations from the sensitive 
nerves, and there they are felt and judged. In the brain arise the motor 
excitations which result in spontaneous voluntary movements. 

In an animal paralysed by division of the cord at the occipito-atloid 
articulation, and in which death has been prevented by artificial respiration, 
observation demonstrates that sensibility and spontaneous motricity are 
preserved in the head, whose nerves are in direct communication with the 
encephalon. Pinch the upper lip, and the patient testifies by the movements 
of this organ that it feels pain. Pass the finger towards the eye, and thg 
eyelids are twinkled and closed: a proof that the animal sees objects, 
appreciates the distance which separates it from. them, and tries to remove 
the eye from their contact. More striking still, the animal feels hungry, 
and endeavours to satisfy this craving by seizing the food within its reach, and 


658 THE NERVOUS SYSTEM IN GENERAL. 


masticating and swallowing it. After this demonstration, it is no longer 
possible to doubt that, if an animal feels, it is by the brain, and if it wills, it is 
also by the brain. : : 

But sensibility and volition do not constitute the only attributes of the 
brain tissue; for it is the seat of other manifestations not less interesting— 
those of the znstincts and intelligence. 

If the encephalon is to be considered as the immediate instrument of all 
these phenomena, it would be impossible—it is impossible—to attribute the 
cause, properly speaking, to the activity of its physical matter ; above this 
hovers a mysterious power that can only be demonstrated by a methodical 
analysis of the manifestations produced by that activity. But we dare not 
venture to touch upon the nature of this power; the first word would be 
useless without the last, and this would carry us too far. 

To sum up, the nerves possess a single vital property—neurility, which 
is manifested by excitability and by centripetal conductibility in the nerves 
whose roots are uppermost, centrifugal conductibility in the nerves whose 
roots are inferior. 

The spinal cord is ‘excitable in its grey substance, but is excitable on 
the surface of its superior fasciculi, though scarcely so in the remainder of its 
white substance. It serves as the organ of transmission between the brain 
and the nerve-roots; and is, in addition, endowed with the reflex property or 

ower. 
4 The brain has for its appanage a special activity, to which is due sensi- 
bility, volition, and the manifestations of instinct and intelligence. 

It remains to make known the nature of the influence the nervous system 
exercises on the other apparatus through the properties we know it to 
possess. But here again we must limit ourselves to principles. 

Since Bichat’s time, it has been agreed to divide into two great classes 
those functions whose operation maintains the life proper of the individual : 
those of animal life or relation, and those of organic or vegetative life. 

The first, which are exercised with consciousness, comprise the sensorial 
functions and voluntary movements ; the latter are provoked by the spon- 
taneous excitation originating in the brain, and transmitted to the muscles 
by the nerve-fibres whose conductibility is centrifugal; the former have 
for their object the appreciation, by the brain, of tactile sensations—of heat, 
light, taste, and smell, by means, or through the instrumentality, of the 
nerve-fibres possessed of centripetal conductibility, which transmits to the 
encephalic mass the stimulus developed at their terminal extremity by these 
diverse physical agents. 

The functions of vegetative life—those which are executed unconsciously, 
we may say, in animals, and which are not the result of physico-chemical 
forces—are placed under the influence of the reflex power of the spinal cord. 
For example, the stomach is empty and its mucous and muscular membrancs 
remain altogether passive; there being no contractions in the first, nor 
secretion of gastric fluid in the second. Food arrives in its interior, and 
immediately its activity is developed; the muscular tunic executes move- 
ments which cause the mixture of the food, and propel it towards the pyloric 
orifice; while the free surface of the internal membrane pours out an 
abundant solvent secretion. This change is due to the stimulus exercised 
by the presence of the alimentary particles on the extremity of the centri- 
petal nerve-fibres, and which has been transmitted by them to the medul- 
lary axis, there reflected on the centrifugal fibres, and carried by these to the 
tunics of the stomach, whose special functions are thus brought into play. 


. 


THE CEREBRO-SPINAL AXIS. 659 


It is worthy of remark that the properties of the nervous system, which 
act in So important @ manner on the organs of vegetative life, have no 
direct influence on nutrition itself. Destruction of the nerves in a certain 
region will certainly derange the nutrition of its tissues, in consequence of 
the paralysis of the vessels, but it is not destroyed. There is an immense 
category of organised beings—vegetables, for instance—in which nutrition 
is very active, and in which there is no nervous system. So that the 
property which determines the essential phenomena of nutrition is indepen- 
dent of nervous action: it is an attribute of living matter. 


SECOND SECTION. 


THe CENTRAL AXIS OF THE NERVOUS SysTEM. 


Tue cerebro-spinal axis is resolved, as we have said, into two principal 
sections—the spinal cord and the encephalon. We will study these two 
portions in succession, the spinal cord first, in order to facilitate our de- 
scription, although that organ only holds the second place in a physiological 
point of view. The protective parts of these two apparatus will, however, be 
examined before we proceed further. 


CHAPTER I. 


_THE ENVELOPING AND PROTECTING PARTS OF THE CEREBRO-SPINAL 
AXIS. 


Tue cerebro-spinal apparatus is lodged, as we already know, in a bony case 
—the spinal canal—which is prolonged anteriorly by the cranial cavity ; but 
it is protected more immediately by three envelopes, which have received the 
names of dura mater, arachnoid, and pia mater. 


THE BONY CASE THAT CONTAINS THE CEREBRO-SPINAL AXIS. 


A knowledge of the bones which enter into the composition of this pro- 
tective case, cannot be acquired without also knowing the case itself; so 
that we dispense with its special study here. We will allude, however, to 
the succinct terms already employed in describing the spinal canal, and in 
the same spirit of concision will also describe what has hitherto been 
deferred —the cranial cavity. 


1. The Spinal Canal. 


This canal communicates, anteriorly, with the cavity of the cranium. 
Very wide at the atlas to receive the odontoid process, and allow those 
rotatory movements of the head which prevent the medulla being injured, 
the spinal canal suddenly contracts at the axis; it expands again at the end 
of the cervical, and the commencement of the dorsal region, where the 
medulla presents a greater volume, and the movements of the spine are very 
extensive. Towards the middle of the back, the spinal canal offers its 


smallest diameter, but on leaving this portion, and as far as the lumbo-sacral 


660 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


articulation, it widens again; after which it rapidly lessens, and altogether 
disappears towards the fourth or fifth coceygeal vertebra. The lumbv-: 
sacral dilatation coincides with the expansion the cord shows at this point, 
and with the enormous volume of the nerves lying beside it. 


2. The Cranial Cavity. (Figs. 22, 23, 175.) 


This is a very irregular oval box, whose walls are formed by the frontal, 
parietal, occipital, ethmoidal, and temporal bones. 

It presents for consideration four planes and two extremities. 

The superior plane offers on the middle line, and towards its superior 
third, the parietal protuberance, the two lateral crests of which concur 
with that eminence in dividing the cranial cavity into two compartments: 
one posterior, destined to contain the cerebellum; the other anterior, 
incomparably larger, lodging the cerebral hemispheres, and divided by the 
single rudimentary crest which begins at the falciform eminence, and joins 
the crista galli, into two lateral sections—one for each hemisphere. Here- 
after we will see that the folds of the dura mater are attached to this 
parietal protuberance, and to the ridges detached from it, thus rendering 
much more perfect the partitioning of the cranial cavity. 

On the lateral planes there is also noticed the division into a cerebellar 
and cerebral compartment, due to the lateral crests of the falciform process, 
which are prolonged obliquely to near the sphenoid bone: the first section 
is formed by the occipital and the inner face of the petrous bone; the 
second by the squamous portion of the temporal, the frontal, and the great 
ala of the sphenoid bouc. Both are concave, and marked by digital 
impressions, as they also are on the superior plane. 

The inferior plane, very irregular, offers from behind forward: 1, On 
the median line, the basilar channel, into which the greater portion of the 
encephalic isthmus is received; the pituitary fossa, made deeper by a 
circular fold of the dura mater, and lodging the gland of that name; the 
optic fossa, where the chiasma of the optic nerves is situated; 2, On the 
sides, the foramen lacerum, partly closed by cartilaginous substance, and by 
the dura mater; the cavernous sinuses and maxillary fissures, outside which 
is remarked a deep and wide digital impression for the reception of the 
mastoid lobule, or inferior lobe of the brain. 

The posterior extremity of the cranial cavity presents the occipital 
foramen, by means of which this cavity communicates with the spinal canal. 

The anterior extremity offers, in the median plane, the crista galli 
process, or superior border of the perpendicular plate of the ethmoid 
bone; on the sides, the two ethmoidal fossee—deep depressions containing 
the olfactory lobes, and at the bottom of which is observed the cribriform 
aspect of the transverse plate of that bone. 


THE ENVELOPES OF THE CEREBRO-SPINAL AXIS. 


The three membranes which cover the cerebro-spinal axis, and separate 
it from the walls of the bony cavity inclosing it, are thus designated. 
Generally termed meninges, and distinguished as external, middle, and 
internal meninge, these membranes are better known as the dura mater, 
arachnoid, and pia mater—names which will be employed in our description. 

The dura mater, or external meninge, is a strong fibrous membrane in 
contact with the walls of the cranium and the spinal canal. 

The arachnoid, or middle meninge, isa tunic of a serous nature, which 


THE CEREBRO-SPINAL AXIS. G61 


resolves itself into two layers: an external, applied to the inner face of the 
dura mater; and an internal, spread, through the medium of the pia mater, 
over the cerebro-spinal axis, from which it is again separated in a great 
number of points by a particular fluid, the subarachnoid. 

The pia mater, or internal meninge, is the proper envelope of the central 
nervous stalk ; it is cellulo-vascular, closely adherent to the external surface 
of the cord, united to the visceral layer of the arachnoid by more or less 
dense connective tissue, between the meshes of which is deposited the 
subarachnoid fluid. 

; This arrangement of the cerebro-spinal envelopes permits the cerebro- 
spinal axis to be assimilated, to a certain extent, to a viscus, and the bony 
sheath containing them to a splanchnic cavity, whose serous membrane, the 
arachnoid, is covered outside its parietal layer by a fibrous expansion, the 
dura mater, and within its visceral layer by a cellulo-vascular tunic, the 
pia mater, or internal meninge. 

This collective view of the envelopes belonging to the nervous centres 
will now be followed by a special description of each, in which their spinal 
and cranial portions will be successively considered, after glancing at them 
in a general manner. 


1. The Dura Mater. 


This membrane is the most external and the strongest of the cerebro- 
spinal envelopes, and covers the walls of the cerebro-spinal cavity, whose 
form it exactly repeats. It is, therefore, a second protective sheath, which 
is dilated at its anterior extremity into an ovoid cavity that lodges the 
encephalon, and terminates in a prolonged point in the coecygeal vertebrae. 

Tt offers two faces: an external, in contact with the walls of the bony 
case; and an internal, adhering in the most intimate manner to the external 
layer of the arachnoid. 

In several points of its extent it is traversed by the nerves which escape 
from the cerebro-spinal axis, and by the vessels destined to this portion of 
the nervous system. 

SrructurE.—The dura mater possesses the texture of all white fibrous 
membranes. It is composed of parallel longitudinal fasciculi of connective 
tissue, mixed with some fine elastic fibres. Bourgelat thought they formed 
two distinct layers—an external and internal; but nowhere is it possible to 
demonstrate this. It receives blood-vessels ; the arteries are derived, for the 
spinal portion, from the vertebral, the intercostals, lumbar, and lateral 
sacrals; for the cranial portion, meningeal ramuscules. such as the ethmoidal 
branch of the nasal, the spheno-spinous, and tympanic, mastoideal, and 
cerebro-spinal arteries. Nerves have been seen passing to its cranial portion ; 
these have been divided into anterior, middle, and posterior. The first 
are furnished by the ethmoidal filament of the nasal nerve; the second from 
the Gasserian ganglion; and the third, by the ophthalmic branch of Willis. 
The existence of lymphatic vessels has not yet been demonstrated. 

SrivaL Dura Marur (Tasca VeERTEBRALIS).—This is a very elongated 
sheath, continuous at the occipital foramen with the encephalic dura mater, and 
terminated behind by an attenuated point lodged in the narrow channel which, 
in the middle coccygeal vertebre, represents a trace of the spinal canal. 
As it is in shape exactly like the latter, its largest diameter is at the atlas, 
and at the brachial and lumbo-sacral enlargements of the spinal cord. Its 
capacity depends greatly on the volume of the latter, and in some of its 
parts it can allow the accumulation of the cerebro-spinal fluid; this 


45 


662 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


accumulation is impossible for nearly the whole extent of the cranial 
region. : ; . 

The external face of the dura mater is very slightly adherent, especially 
above, to the walls of the spinal canal; and it is even separated from them, 
at the intervertebral spaces, by a certain quantity of adipose tissue which is 
never absent, though the animals be ever so emaciated, This face covers, 
inferiorly, the common superior ligament, and the veins we have described 
as spinal sinuses. ; 

The internal face gives attachment, between each pair of nerves, to the 
festoons of the dentated membrane, a dependency of the pia mater. It is 
rendered smooth and polished by the external layer of the arachnoid, to 
which it is so firmly united, that it is needless to attempt their separation, 
Here the external layer of the arachnoid is reduced to a simple layer formed 
by a row of cells with flattened nuclei. 

On each side, the substance of this meninge is completely traversed by a 
double series of orifices for the passage of the spinal nerves, around which 
it sends small special sheaths as far as the intervertebral foramina. 

CrantaL on EncerHatic Dura Mater.—This membrane forms a sac 
which is exactly moulded by its external face to the cranial parietes, and by 
its internal face to the superficial surface of the encephalon. The latter, 
therefore, completely fills the cavity of the cranium, a circumstance that 
explains why an accumulation of fluid is impossible in this region. 

External surface.—It adheres strongly, by cellulo-vascular bands, to the 
cranial walls, whose undulations it follows; this adhesion is not, however, 
equally marked everywhere, for on the sides of the roof of the cerebral 
compartment it is least intimate, and it is closest on the middle plane of 
this roof, on the crista galli, around the parietal protuberance, on its crests, 
and towards the lateral faces of the cerebellar compartment at the petrous 
bones, where the membrane is very thin. 

This face gives rise to a number of prolonged sheaths, corresponding to 
the nerves leaving the base of the cranium. The principal are found around 
the ethmoidal filaments, the optic nerves, and the two thick branches 
furnished by the Gasserian ganglion. 

Internal surface—The internal surface of the cranial dura mater is 

covered by the parietal layer of the arachnoid, which is firmly attached to 
it only in the spinal region. It sends into the cranial cavity three pro- 
longations, which are distinguished as the falx cerebri (fala, a sickle), 
-tentorium cerebelli (tentorium, a tent), and the pituitary fold. These processes 
complete the partitioning of the cranial cavity, isolate the various external 
‘bulgings of the encephalic mass, and protect them from the compression 
‘they might exercise on each other. 

a. The falx cerebri is a vertical lamina comprised between the two 

cerebral hemispheres, and owes its name to its sickle-like form. 

Its antero-superior border is adherent and very convex, and corresponds 
to the crista galli process, as well as to the median ridge on the inner 
face of the frontal and parietal bones. This border is very thick, and 
hollowed internally by a prismatic and triangular venous canal, which con- 
stitutes the median sinus. 

Towards its inferior border, which is free and concave, and corresponds 
to the eorpus callosum, the falciform process is extremely thin, and cribbled 
like lace-work. 

The posterior extremity, or base of the falx, rests on the parietal 
protuberance, 


THE CEREBRO-SPINAL AXIS. 663 


The anterior extremity advances in a curve to near the optic fossa. 

In aged animals, there are sometimes found on the faces of the falx 
cerebri, especially towards its posterior extremity, small yellow granules, 
known as the Pacchionian glands, They are little nuclei of connective 
tissue that arise from the subarachnoideal tissue; meningeal granulations 
would be a better designation for them than that of glands. 

b. The tentorium cerebelli is composed of two lateral lamine, which form 
a transverse partition between the cerebellum and the posterior extremities 
of the cerebral lobes. 

Each lamina, coursed internally by one of the transverse sinuses, offers : 
an adherent convex border, attached to the parieto-temporal crest; a free 
concave border, turned inwards and a little forwards, remarkable for its 
thickness and solidity, and, with the second lamina, circumscribing an oval 
opening through which the encephalic isthmus passes; a superior extremity, 
attached to the parietal protuberance; an inferior extremity, which 
disappears above the Gasserian ganglion, near the fold that surrounds the 
pituitary gland. d 

Of the two faces of these lamine, the anterior corresponds to the cerebral 
lobes, the posterior to the cerebellum. 

c. The suprasphenoidal, or pituitary fold, is a thick, slightly salient, and 
almost circular pad, channeled internally by the cavernous sinus, and 
circumscribing the sella turcica by enveloping the pituitary gland laterally 
and posteriorly. 


2. The Arachnoid Membrane. 


The arachnoid presents the same disposition as all the splanchnic serous 
membranes, in being resolved into two layers—a parietal and a visceral, 
both constituting a perfectly closed sac, outside which the cerebro-spinal 
axis is contained. The cavity of this sac is traversed by the roots of nerves, 
the vessels of the brain and cord, and filaments and cellular lamelle which 
pass from the pia mater to the dura mater ; around all these its layers form 
sheaths by becoming continuous with one another. 

Each of these layers exhibits an adherent and a free face. The adherent 
face of the parietal layer is united, as we have already seen, to the dura 
mater. That of the visceral layer covers the nervous axis in spreading 
itself over the pia mater, but without accompanying it into the anfractuosi- 
ties of the central mass; it is beneath this face of the visceral layer that the 
cerebro-spinal (or subarachnoid) fluid is confined in spaces which will be 
studied hereafter. By their free face, which is smooth and moist, like that 
of all serous membranes, the arachnoid layers are in contact with each 
other. 

SravcturE.—The structure of this membrane resembles that of all others 
of the same nature. ‘The meshes of elastic fibres are most abundant in the 
cranial portion. Everywhere the parietal layer is only composed of a 
simple layer of epithelium. The arachnoid has no proper vessels or 
nerves; those which pass through it only accompany each other. ; 

Sprvat AracanormD Memprane.—The parietal layer presents nothing of 
interest. The visceral layer is separated from the spinal cord, throughout 
its extent, by a somewhat considerable space (the subarachnoid), in which 
the subarachnoid fluid is collected; this space is greatest posteriorly, 
around the terminal extremity of the cord and the nerves of the cauda 
equina. ; : 

The adherent face of this membrane is only connected with the external 


664 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


surface of the spinal cord by thin cellular filaments detached from the pia 


mater. ; . 
CranraL or Encepuatic ARracnnorp.—There is nothing special to 


note in the parietal layer. ua 7 

If the visceral layer be traced from the occipital foramen, where it is 
continuous with the spinal arachnoid, to the anterior extremity of the 
cerebral lobes, it is seen to be prolonged inferiorly on the lower face of the 
isthmus, as far as the pituitary stalk, to which it furnishes a sheath: the 
pituitary gland itself is not covered by the arachnoid, except on a portion of 
the superior or deep face ; from the isthmus it is carried forward, and extends 
on each side of the cerebellum and cerebral lobes. Superiorly, this internal 
layer spreads over the surface of the cerebellum, and is reflected at the 
bottom of the fissure between that organ and the cerebral hemispheres, 
over the posterior extremity of the latter, enveloping them separately by 
descending into the interlobular fissure as far as the corpus callosum. 
Reaclfhg the anterior extremity of the cerebrum, it gains the olfactory 
lobes, is principally prolonged on their supero-posterior face, and doubles 
around the ganglion of grey substance on their inferior face, to be con- 
tinued with the parietal layer. 

In covering the external surface of the encephalon, the cranial arachnoid 
does not adhere everywhere to the nervous substance, but is only slightly 
connected with it, through the medium of the pia mater, at such salient 
portions as the summits of the cerebral convolutions. Neither does it dip 
down to enter the sulci existing between these parts, but passes over them, 
and in this way forms a large number of subarachnoid spaces analogous to 
that developed over the whole extent of the spinal cord. 

These spaces, which are filled by the subarachnoid fluid, differ widely in 
form and dimensions. In Man, three principal have been described, and 
these are also found in animals; Magendie has named them the confluents of 
the subarachnoid fluid. Of these three confluents, the anterior is situated in 
advance of the chiasma of the optic nerves, between the two cerebral lobes; 
the inferior, the largest, is comprised between the pituitary stalk and the 
annular protuberance to the surface of the pedunculi of the cerebrum ; while 
the third, or posterior confluent, lies behind the cerebellum, at the calamus 
scriptorius. 

None of these spaces communicate with the internal cavities of the en- 
cephalon, and, consequently, the subarachnoid fluid cannot enter them. 
Magendie has nevertheless described a communication between the pos- 
terior confluent and the ventricle of the cerebellum ; though the opening he 
described towards the calamus scriptorius has not been found in the Horse 
by M. Renault, and we believe we may affirm, with M. Lavocat, that it does 
not exist in the other animals. 

THe Suparacunoiw Fium.—tThe fluid contained in the subarachnoid 
spaces is slightly yellow or colourless, and perfectly limpid and transparent. 
Some authorities admit that it is secreted by the visceral layer of the 
arachnoid, and others by the pia mater. According to the remark made by 
Cruveilhier, the nervous centres are immersed in it, like a foetus in the 
liquor amnii; and this remark, which is particularly applicable to the 
spinal cord, gives the key to the use of this fluid, which keeps the organ 
away from the walls of the spinal canal, deprives it of the greater part of 
its weight (Foltz), and thus diminishes every kind of concussion to which 
it might be exposed. 

(This fluid, so necessary for the support and protection of the cord and 


THE CEREBRO-SPINAL AXIS. 665 


brain, is alkaline, and contains but a small quantity of albumen ; it varies 
in quantity according to the relative size of the cerebro-spinal axis and its 
containing cavity, or with the amount of blood sent to this region. By 
affording, under all circumstances, an equable pressure on the brain and 
spinal cord, and the nerves emanating from these, its importance as a hydro- 
static agent is greatly enhanced.) 


3. The Pia Mater, 


The pia mater, the proper envelope of the cerebro-spinal axis, is a thin 
membrane whose framework, essentially connective, sustains on its external 
face a very abundant network of blood-vessels and nerves. 

Applied immediately to the surface of the encephalon and spinal cord, it 
adheres firmly to that surface and follows all its inequalities, penetrating 
between the cerebral or cerebellar convolutions, and forming in each inter- 
mediate sulcus two layers that lie against each other. 

The external face of the pia mater, bathed in part of its extent,by the 
subarachnoid fluid, adheres to the visceral layer of the arachnoid by means 
of a more or less dense and close filamentous connective tissue. From it 
arise the cellular coverings that constitute the neurilemma ‘of the nerves. 
Ii detaches a multitude of filamentous or lamellar prolongations to the 
internal face of the dura mater, which traverse the arachnoid cavity in the 
same manner as the nerves and vessels, by being enveloped, like these, in a 
sheath furnished by the arachnoid membrane. Always very short, these 
prolongations simulate the adhesions established between the two layers of 
that membrane. 

The internal face is united to the nervous substance by multitudes of 
arterial and venous radicles or connective filaments, which leave the pia 
mater to plunge into this substance. 

The vessels of the pia mater forma very close network, from which are 
detached branches that reach the medulla and encephalon. They are ac- 
companied by nervous filaments, and surrounded by perivascular canals, which 
are now believed to be lymphatics. Certainly, in their interior a colour- 
less fluid circulates, and which contains globules very like those of lymph. 

Spivau Pra Marer.—Less vascular than the cranial pia mater, with 
which it is continuous towards the medulla oblongata, this membrane is 
remarkable for the arrangement of the prolongations that arise from its 
two faces. 

The internal prolongations form longitudinal lamine at the fissures of the 
cord, and enter these fissures. . 

The external prolongations attach, as we have said, the pia mater to the 
external meninge. A very large number are filamentous in form, and are 
dispersed over the superior and inferior surfaces of the cord. Others consti- 
tute, on each side of the organ, a festooned band named the dentated ligament 
(ligamentum dentata, or denticulatum). These ligaments exist throughout the 
entire length of the medullary axis, between the superior and inferior nerve- 
roots: their inner border is confounded for its whole length with the pia 
mater; and their outer margin, cut into festoons, attaches itself to the dura 
mater by the summit of the angles separating these festoons. ; 

To complete this description of the spinal pia mater, there may be noticed 
a posterior or coccygeal prolongation (filum terminale) : @ very narrow process 
formed by this membrane at the posterior extremity of the cord, situated in 
the midst of the cauda equina nerves, and attached to the bottom of the 
conical cul-de-sac at the termination of the dura mater. 


666 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


(This ligament, or membrana dentata, serves to maintain the position of 
the spinal cord in its hydrostatic bed, and to prevent the nerves proceeding 
from it being dragged during flexion of the spine.) 

CrantaL, oR EncepHatic Pra Marer.—The vascular element pre- 
dominates in this portion of the internal meninge. 

This membrane sends scarcely any prolongations to the dura mater, 
except at the medulla oblongata, though it projects remarkably large ones 
into the cerebral mass and the sides of the cerebellum. The description of 
the velum interpositum, and the cerebral and cerebellar plexus choroides, belongs 
to the encephalon. 

(The pia mater is extremely vascular on the surface of the cerebrum, and 
forms remarkable anastomosing loops in the intermediate spaces of the 
convolutions, which chiefly supply the grey substance. It is the nutrient 
membrane of the brain and spinal cord. Its nerves accompany its arterial 
branches, and are minute filaments from the sympathetic.) 


DIFFERENTIAL CHARACTERS IN THE ENVELOPING AND PROTECTIVE PARTS OF THE CEREBRO- 
SPINAL AXIS IN OTHER THAN SOLIPED ANIMALS. 


The oony canal that protects the spinal cord and brain does not present any note- 
worthy differences in the domesticated animals, and the subject has been already 
sufficiently studied in the osteology of the head and vertebral column. 

With regard to the meninges, their number and general disposition are the same in 
all the species. 


COMPARISON OF THE ENVELOPING AND PROTECTIVE PARTS OF THE CEREBRO-sPINAL 
AXIS OF MAN WITH THOSE OF ANIMALS. 


There is nothing particular to be said respecting the cranial cavity and spinal canal, 
nor yet the arachnoid and pia mater. The dura mater offers the folds described in 
Solipeds, and, in addition, a fala cerebellum, that extends from the tentorium of the same 
name to-near the foramen magnum. The meningeal granulations, or Pacchionian glands, 
are nearly constant in aged individuals, and their volume is sometimes so considerable, 
that by compression they thin away, and even perforate, the cranium at corresponding 
points. 


CHAPTER II. 


THE SPINAL CORD. 


Preparation.—Isolate the cranium and vertebral column from all the other parts of the 
body; open the spinal canal and the cranial cavity by their superior surface, as in 
figure 316, by raising with a chisel (or rogne-pied, the farrier’s “ toe-knife ”) and hammer, 
the roof of the skull and annular portion of all the vertebre. The organ may then be 
studied im situ in its bony case, and surrounded by its membranes; afterwards extract 
the whole cerebro-spinal axis inclosed in the dura mater, and open up the latter along 
the course of the cord, so as to completely expose that portion of the nervous system. 

(The saw and farrier’s pincers, or spine ratchet, will be found useful auxiliaries in the 
tedious and delicate operation of exposing the brain and cord; and particularly in lay- 
ing open the cranial cavity. An easy mode of obtaining access to the spinal canal and 
its contents, is to saw through tbe laminew of the vertebree on each side, at the roots of 
the transverse processes, and raise the arches with the chisel or toe-knife.) 


EXTERNAL CONFORMATION OF THE SPINAL CORD. 


General view —The spinal cord is that portion of the nervous centres which 
occupies the spinal canal. It is a thick, white, and irregularly cylindrical 
cord, commencing at the occipital foramen, where it continues the medulla 
oblongata, terminating in a point at the upper third of the sacral canal, or a 


667 


THE SPINAL CORD. 


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668 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


little beyond that, and giving rise at each side, during its course, to the 
superior and inferior roots of the spinal nerves. : 

Weight. —In medium-sized animals the weight of the cord is represented 
by the following approximate numbers : for the Horse, 103 ounces; the Ass, 
51 ounces; Cow, 7 ounces ; Sheep and Goat, 1? ounce; Pig, 24 ounces; 
Dog, 1} ounces; Cat, 45 drams. Reval 

Figure and volume.—The medullary cord is slightly depressed above and 
below, throughout its whole length; in whatever part we examine a 
transverse section of it, we will always find the lateral diameter greater than 
the vertical, and that this section appears regularly elliptical. 

Its volume is far from being uniform. In following it from before to 
behind, we at first remark that it presents the same dimensions to the fifth 
cervical vertebra, and that between this point and the second dorsal vertebra 
it forms an oblong enlargement, designated the brachial (brachio-rachidian ) bulb 
or enlargement. Beyond this, it assumes its primitive volume, and becomes 
gradually smaller even than in the cervical region. Towards the middle of 
the loins, it again augments to constitute the crural (lumbo-rachidian) bulb 
or enlargement, which extends to the entrance of the sacral canal. After 
this dilatation comes a conical prolongation, whose point represents the 
terminal extremity of the cord. 

If we compare the diameter of this medullary axis with that of the 
spinal canal, we will observe, as has been already said, that the capacity of the 
containing cavity is generally related to the volume of its contents, and that 
the former is, as a rule, most capacious at the cervical and lumbar enlarge- 
ments. It will even be noticed that the dilatation the spinal canal offers at 
these two points, is relatively more considerable than the excess in volume of 
the cord. This is because the mobility of the spine, which is justly very 
great in these two regions, requires this difference to secure the spinal axis 
from contusions during the movements executed by the vertebral column. 
This protective combination is also found elsewhere: at the atlas, for 
example, where we know the motion is considerable; and in the entire 
extent of the cervical region, which in this respect greatly exceeds the 
dorsal region. 

External surface of the cord.—Covered by the pia mater, this surface 
presents an extremely simple disposition. On its superior and inferior 
planes, at each side, we remark the double series of sensitive and motor 
roots of the spinal nerves, which are implanted in the same longitudinal 
line to right and left of the median plane, and are collected in fasciculi 
opposite the intervertebral foramina, 

In the middle line, and throughout the entire length of the organ, there 
are two deep and narrow fissures: one superior (fissura longitudinalis 
superior), the other inferior (fissura longitudinalis inferior), into which the 
pia mater enters. Four other fissures have been described at the point of 
emergence of the nerve roots, under the names of superior and inferior 


collateral fissures (or sulci); but the two superior alone exist, and even 
these are often scarcely noticeable. 


INTERNAL CONFORMATION AND STRUCTURE OF THE SPINAL CORD. 


In making a transverse section of any portion of the cord, we may 
convince ourselves that it has an internal cavity. This central canal is 
elliptical, and lined by cylindrical ciliated epithelium, resting on a thin 
connective membrane, the ependymis of Virchow. This section also shows 


THE SPINAL CORD, 669 


the two median fissures mention 
the inferior of which is wider a 
situation is scarcely perceptible. 

These two fissures advance one before the other, and do not meet 
so as to completely divide the 
cord into two lateral halves, but Fig. 318. 
remain separated by two thin 
horizontal and superposed bands 
of nervous matter, that pass from 
one end to the other of the me- 
dullary axis. The inferior, formed 
of white substance, corresponds to 
the bottom of the inferior fissure ; 
while the superior, composed of 
grey matter, meets the superior 
fissure. 

These bands are named the 
white and grey commissures of the 
spinal cord (Fig. 318). 

Notwithstanding the presence 
of these two commissures between 
the lateral halves of the spinal SECTION OF THE SPINAL CORD OF THE HORSE 
axis, these latter do not the less con- ee el a Da aaa 
stitute two symmetrical systems, 1, Superior median fissure; 2, Inferior median 
whose structure will now be fissure; 3, 3, Superior collateral fissures; 
studied. 4, 4, Inferior ditto; 5, Grey commissure; 6, 

Each medullary cord repre- White commissure; 7, 7, Superior grey cor- 
sents semi-cylin derof'white sub. 20": 8, 8, Inferior grey cornua; 9, Central 

. canal. 

stance, in the centre of which is 

amass of grey matter, that varies somewhat in quantity in different regions, 
but the arrangement of whichis everywhere the same. Thus, inwardly, this 
grey matter joins the grey commissure ; above, it sends off a thin prolongation 
which traverses the thickness of the medullary cord (superior grey cornu), 
to reach the bottom of the superior collateral fissure; below, it gives 
rise to an analogous, though a thicker and a more irregular, prolongation 
(inferior grey cornu), which is directed well in front of the inferior roots, 
but does not reach the surface of the cord. In consequence of this arrange- 
ment, the grey substance of the medulla forms altogether a kind of capital 
H, whose horizontal branch is perforated in the middle by the central] 
canal. 

This disposition of the grey substance causes the white matter to be 
divided, in each lateral moiety of the spinal axis, into three cords or 
secondary columns ; the superior of these is perfectly isolated, and is com- 
prised between the middle superior fissure and the origin of the sensitive 
roots ; another, the inferior, united to that of the opposite side by the white 
commissure, is limited, inwardly, by the inferior median fissure, and out- 
wardly by the line of origin of the motor nerve-roots; while a third, the 
‘lateral or intermediate, thicker than the others, is confounded superficially 
with the inferior, and formed by all that portion of the medulla situated 
between the lines of origin of the superior and inferior roots. Of these 
three columns of the medullary axis, the first is sensitive; the other two, 
which in reality are only one, are motor. : 

Srructure.—Independently of the epithelium mentioned when describing 


ed in describing the exterior of the cord, 
nd deeper than that of the superior, whose 


670 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


the ependymis, connective oe nerve tubes, nerve cells, and vessels enter 
i re of the medulla. fox ; 
ees LS Sane ee of the spinal cord is very delicate, rich in nuclei, and 
belongs to the variety that histologists have named “ reticular ” or “ adenoid. 

It appears to arise from the pia mater, and forms lamelle that penetrate 
the nerve-substance to meet and anastomose with each other, and finally 
become confounded with the ependymis around the central canal. This 
tissue, which is also named neuroglia, has been compared to a sponge, in 
whose spaces are deposited the other elements of the cord. This neuroglia, 
exists in the white and grey substances, but is more abundant in the superior 
than in the inferior grey cornua. It surrounds the upper extremity of the 
former in becoming softer and more transparent, and is here designated the 
gelatinous substance af Rolando (substantia gelatinosa). It constitutes, in 
great part, the grey commissure, and can be deeply stained by the carminate 
of ammonia. 


TRANSVERSE SECTION OF SPINAL CORD OF MAN THROUGH THE MIDDLE OF THE 
LUMBAR REGION, SHOWING ON THE RIGHT SIDE THE COURSE OF THE NERVE- 
ROOTS, AND ON THE LEFT THE POSITION OF THE PRINCIPAL TRACTS OF VESICULAR 
MATTER. 

A, A, Anterior or inferior columns; pP, P, Posterior or superior columns; 1, L, Lateral 
columns.—a, Anterior or inferior median fissure ; p, Posterior or superior median 
fissure; 6, 6, 6,, Anterior or inferior roots of spinal nerves; c, c, Posterior or 
superior roots; d, d, Tracts of vesicular matter in anterior column; e, Tracts of 
vesicular matter in posterior column ; f, Central canal; g, Substantia gelatinosa. 


The tubes and cells form, with the neuroglia, the whole of the grey 
substance. The cells have at least five prolongations, and the tubes are 
reduced either to the axis-cylinder (axis-fibre), or to this and a very thin 
layer of medullary substance. 

The cells are not uniformly distributed in the grey substance, but are 
arranged in small masses that constitute three longitudinal columns: two 


THE SPINAL CORD. 


in the inferior, and one in the superior grey cornu. 


respond to what Stilling 
mass of cells, the superior vesicular column 
of Clarke, or dorsal nucleus of Stilling, is 
observed at the point where the grey com- 
missure joins the cornua. The nerve-tubes 
(or tubules) affect longitudinal, transversal, 
oblique, and vertical directions. 

They bring the cells of one lateral 
moiety of the medulla into communication 
with: 1, The tubes of the white substance ; 
2, Each other ; 3, The cells of the opposite 
moiety, by passing into the commissures; 
4, The tubes of the white substance of the op- 
posite moiety, by following the same course. 

The neuroglia and uerve-tubes consti- 
tute the white substance, which is decom- 
posed, as we know, into three cords. All 
the tubes of this substance do not ascend 
to the brain, as was believed for a long time ; 
the opinion that the tubes of the spinal 
nerves formed the medulla and extended to 
the brain, has been abandoned since Volk- 
mann measured, comparatively, the section 
of all these nerves and that of the nervous 
spinal-axis, 

(Volkmann has established the fact, that 
the size of the medulla corresponds with the 
number of nerve-tubes given off at any point. 
He gives the weight of four segments, each 
2,5, inches in length, from the spinal cord 
of the Horse, and the relative extent of the 
grey matter in square lines; these are as 
follows 


Area Area 

Grains. of Grey of White 

Matter. Matter. 

From below 2nd Spinal Nerve, 219 13 109 
” 49 8th » 293 23 142 
e- — TBD 5 «6-182 11 89 
* ww Bot » 281 25 121) 


In the white substance the tubes are lon- 
gitudinal, oblique, or transversal ; the latter 
arise from the cells of the grey substance, 
and represent the roots of the nerves 
emerging either by the superior or inferior 
collateral fissure. 

The tubes of the anterior cords pass to 


671 


The columns cor- 


has named the nuclei of the nerves. A fourth 


Fig. 320, 


LONGITUDINAL SECTION THROUGH 
CERVICAL ENLARGEMENT OF SPINAL 
CORD OF CAT, 

AC, Inferior white columns; ac’, Por- 
tion showing the arrangement of 
the longitudinal fibres, pc, Pos- 
terior white columns; G, Grey 
substance between them (the vesicles 
being omitted to avoid obscuring 


the course of the fibres); A, Anterior roots of the nerves, P, Posterior roots, consisting 
of three kinds: the first, u, crossing the posterior columns horizontally, and then pass- 
ing obliquely downwards, across the grey substance, into the anterior columns; the 
second, 8, traversing the posterior columns horizontally, and then losing themselves 
in the grey substance; the third, c, for the most part becoming continuous with the 
longitudinal fibres of the posterior column; all, or nearly all, ultimately entering the 


grey substance. 


672 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


the cells of the grey substance, or reach the encephalon by remaining in the 
corresponding moiety of the medulla; for instance, the fibres of the right 
half of the medulla gain the brain without passing into the left half. 
Those of the lateral cords decussate, each cord sending to, and receiving 
from, the other, tubes which cross in the white commissures. The posterior 
cords contain fibres that extend directly to the brain: these are sensorial ; 
there are also found transverse fibres that enter the cells of the superior 
grey cornua, and others that pass into the cells of the inferior or motor 
cornua. 

Such is, in a few words, the disposition of the nerve-elements in the 
medulla. The subject is a very long and complicated one, which cannot 
be dealt with in a more detailed manner in a work on descriptive anatomy. 

Vessels.—The medulla receives arteries from the ramifications of the 
pia mater, The grey is richer in vessels than the white substance; the 
latter is penetrated everywhere by a large number of minute arteries; while 
the first is traversed by the divisions of an artery that is thrown off by the 
median spinal, and ascends towards the bottom of the inferior fissure. The 
veins follow the arteries, and constitute two somewhat voluminous vessels 
that pass along the grey commissure, to the right and left of the central 
canal. 


DIFFERENTIAL CHARACTERS IN THE SPINAL CORD OF OTHER THAN SOLIPED ANIMALS. 


In all the species, the white and grey substances affect the disposition above de- 
scribed; only some slight differences in the reciprocal volume of each have been 
remarked. As in the Horse, the spinal medulla does not extend beyond the sacral 
region; its length has no relation to that of the coccygeal region, as certain anatomists 
would, in principle, establish; in the rabbit, for example, the tail of which is very 
sliort, the spinal cord is prolonged into the coceygeal vertebre. 


COMPARISON OF THE SPINAL CORD OF MAN WITH THAT OF ANIMALS. 


The spinal medulla of the adult Man does not reach beyond the first lumbar vertebra, 
though in the foetus it is in the coceyx. It is rounder than in the Horse, and the grey 
substance is, relative to the white, more abundant than in the spmal cord of the domes- 
ticated animals. The posterior grey cornua are also larger and less elongated than the 
superior cornua in the Horse; and the roots of the nerves are also more voluminous. 


CHAPTER III. 
THE ENCEPHALON, 


Articte ]_—Tur Encepaanon as A WHOLE. 


Tux encephalon is that portion of the nervous system which is lodged in 
the cranial cavity. It succeeds, without any line of demarcation, the spinal 
cord, of which it may be considered, with regard to its figure, as a kind of 
efflorescence. ‘i 

General form and constitution.—In shape it is an ovoid mass, elongated 
from before to behind, and very slightly depressed from above to below. 

When it is viewed on its superior face (Fig. 321), we first see, behind, a 
white pedicle, the prolongation of the spinal cord, and a single lobe of a 
grey colour designated the cerebellum. In front of this is remarked two 
other lobes, separated from the first by a deep transverse fissure, into which 


THE ENCEPHALON. 673 


the tentorium of the cerebellum passes. Isolated from one another on 
the middle line by a shallower fissure, these two lobes constitute the brain 
and are usually named the cerebral hemispheres. 

In turning over the encephalon 
to examine its inferior face, we see 
that the posterior peduncle of the 
organ—a continuation of the spinal 
cord—is prolonged beneath the ce- 
rebellum, which is joined to the 
lateral parts of its superior face; 
this portion then enters the cere- 
bral hemispheres by their inferior 
face, behind two thick white cords— 
the optic nerves, which mark the 
anterior limit of this prolongation 
(Fig. 322). This is the isthmus of 
the encephalon: a name given to it 
because it actually forms an inter- 
mediate bond between the: three 
enlargements which form the prin- 
cipal mass of the encephalon. 

The cranial portion of the cen- 
tral nervous mass is, then, com- 
posed of three apparatus: the 
isthmus of the encephalon, a pro- 
longation of the spinal cord; and 
the cerebellum and cerebrum, bulbous 
lobes grafted on the superior face 
and anterior extremity of this pe- 
duncle. These three divisions are 
very well seen in their entirety 
and reciprocal relations in Figure 
829. We will study them sepa- 
rately and in succession. 


Fig. 321, 


Vi 1 th e halon — Con: GENERAL VIEW OF THE BRAIN; UPPER SURFACE. 
olume of the enceph he spina] 1 Medulla oblongata; 2, Middle lobe of the 
trary to what is found in the Spina. cerebellum ; 3, 3, Lateral lobes of ditto; 4, 4, 


cord, the dimensions of the en- Cerebral hemispheres ; 5, Interlobular fissure ; 
cephalon closely represent those 6, 6, Ethmoidal lobules. 
of the cavity containing them: the ¢ : 
visceral layer of the arachnoid lying everywhere immediately on the proper 
envelope of the nervous mass, the pia mater, except at the subarachnoid 
spaces; and, on the other hand, the arachnoid cavity can scarcely be said 
to exist while the dura mater is, as it were, glued to the cranial walls, and 
in reality constitutes their internal periosteum. _ 
The encephalon has, therefore, no room to move in its receptacle, but is 
‘maintained in it in an almost absolutely immovable condition, which 
coincides exactly with that of the sutures or cranial articulations. ; 
Weight.—The total weight of the encephalon, in average-sized animals, 
may be inferred from the following figures: Horse, 22 oz. 15 drams; Ass, 12 
oz. 11 drams; Ox, 16 oz. 15 drams ; Sheep and Goat, 4 oz. 94 drams; Pig, 
5 oz. 10 drams; Dog; 6 02, 53 drams; Cat, 1 oz. 1dram, 
In comparing these figures with those of the spinal cord, it will be seen 
that the relative weight of the medullary axis to that of the encephalic mass 


674 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


differs notably in the several animals, being highest in the Dog. The 
relations in each species, between the two divisions, are the following : Dog, 
1: 5,14; Cat, 1: 8,75; Sheep and Goat, 1: 2,60; Ass 1: 2,40; Pig, 1: 
2,30; Horse 1: 2.27; Ox, 1: 2,18. We give these numbers, as it has 
always been attempted to establish in the predominance of the encephalon 
the cause of the development of intelligence, and that the best measure of this 
predominance is really the relation of the spinal axis to the encephalic mass. 
Tt has also been attempted to measure this predominance of the encephalon by 
comparing its weight with that of the entire body; but it is sufficient to cast 
one’s eye over the tables drawn up with this view in several anatomical and 
physiological works, to be convinced that this basis does not possess all the 
value desirable. 


Preparation of the encephalon.—To study the encephalon, it is necessary to extract it 
from its bony receptacle; a result achieved in two ways. The first consists in opening 
the roof of the cranium by hammer and chisel, after removing from its exterior all the 
parts covering it, or which are in its vicinity. The dura mater is then excised with 
scissors, and the encephalon, which is thus directly reached, is completely isolated by 
raising its posterior extremity, and cutting from behind to before all the nerves passing 
through the foramina at the base of the cranium, with the pituitary stalk, as well as the 
extremity of the olfactory lobes. This method is very expeditious, but it sacrifices the 
pituitary gland, which remains firmly incrusted in the sella turcica: an inconvenience 
we obviate by resorting to the second procedure. In this, the cranium is opened by its 
base or floor, after separating the head from the trunk, cutting away the lower jaw, 
tongue, and os hyoides, and excising all the soft parts so as to expose the bony surfaces. 
The head, thus prepared, is held by an assistant, the roof of the cranium resting ona 
table or block. Armed with a chisel and hammer, the operator first removes the 
zygomatic arches and styloid processes of the occipital bone, then the condyles of this 
bone, the basilar processes, and the sphenoid, palate, and ethmoid bones, returning to the 
lateral portions of the cranium, which are chiselled away in succession from the occipital to 
the ethmoid bones. The encephalon being sufficiently exposed, is relieved from its dura 
mater as in the first method, and raised in the left hand to destroy, by means of scissors 
held in the right hand, the attachments which yet fix it to the cranial roof, and which 
are chiefly the veins that open into the sinuses of the dura mater. In afterwards ex- 
cavating the ethmoidal fossx with the point of a scalpel, the olfactory lobes are detached, 
and the nervous mass is free. This procedure is more difficult than the first, but 
possesses several advantages over it; for not only do we preserve the pituitary gland, but 
have the ethmoidal lobes more intact, and may also have, if desired, the ganglia of the 
cranial nerves, with a more or less considerable portion of the nerves themselves. 

After indicating the methods for extracting the encephalon from its bony ease, we 
ought to say some words as to the course to be pursued in order to study it successfully. 
To do this it is advantageous to have two brains; one of these should be hardened by 
steeping it for some weeks in alcohol (or methylated spirit), or in water to which has 
been added a tenth part of nitric acid. This hardening contracts the nervous substance, 
and causes the cavities and reliefs to appear more manifest. (It is a good plan to place 
the brain, base uppermost, in a suitable vessel, and if a piece of cloth be spread beneath 
it, its removal therefrom will be greatly facilitated.) 

We commence by examining rapidly the whole apparatus, and pass immediately to 
the study of the isthmus, of which it is necessary to have at first a well-defined idea. 
We therefore take a hardened specimen, and isolate this portion of the encepbalon in 
the manner represented in figure 323 ; to do this, it suffices to cut through the peduncles 
of the cerebellum, and excise the cerebral hemispheres upwards and backwards; the 
remains of these and the cerebellum should be preserved for an analysis of their 
structure. The isthmus thus isolated is fitted for an examination of itg external confor- 
mation and its internal cavities: the ventricle of the optic layers and the aqueduct of 
Sylvius, into which we may penetrate by a superior longitudinal incision. 

_ _ After the isthmus, the cerebellum is to be studied : in its external conformation, on an 
intact specimen ; and in its internal conformation and structure on the incised piece. 

__, We terminate with the cerebrum, Whose superficies is soon examined, and whose 
interior should be studied in the following manner :—It is necessary to begin by demon- 
strating the existence of ventricles in the olfactory lobes, and their communication 
with all the other internal cavities of the brain, which can easily be done by the in- 
flation of one of these organs by means of a straw (or dissecting-case tube) which 


THE ISTHMUS, 675 


raises the pituitary gland, the cerebral lobes, and the cerebellum. Then we pass to the 
corpus callosum, which is exposed, as in figure 330, by a horizontal section of the hemi- 
spheres across the centrum ovale. The corpus callosum of each side is afterwards 
excised on the median line to reach the interior of the lateral ventricles, and this great 
commissure of the brain ought, after studying the septum lucidum, to be eut acrossin the 
middle and turned over, as in figure 331, so as to show the cerebral trigonal (fornix). The 
foramen of Monro is next examined, then the corpus striatum, hippocampi, tenia semi- 
cireularis, choroid plexus, and velum interpositum, which are exposed by the ablation of 
the hippocampi and trigonal. Lastly, we return to the foramen of Monro to study its 
communication with the ventricle of the optic layers ; it will be well, also, to again ex- 
amine the latter, as well as the aqueduct of Sylvius and the ventricle of the cerebellum, 
which we arrive at in dividing the organ through the middle and separating the halves. 

Two longitudinal and vertical sections, one median (Fig. 327), the other at the side 
(Fig. 329), will not be without utility in the study of these particulars. They may be 
made by means of a saw, the brain remaining inclosed in the cranial cavity. 

(A long-useful implement for removing the bony casing of the brain without risk of 
injuring it, is a chisel whose thin cutting edge is slightly concave, the corners being 
smooth and rounded, and projecting beyond the cutting edge.) 


ArticLe I].—Tue Isrumus. . 


We will study in succession the external and internal conformation of 
this organ, and its structure. 


EXTERNAL CONFORMATION OF THE ISTHMUS, 


The isthmus is a prismatic prolongation of the spinal cord supporting the 
cerebellum, and terminating in the cerebral hemispheres; it increases in 
size from behind to before, and may be considered as having four faces and 
two extremities. st : 

The inferior face (Fig. 322), on which we can distinctly, and without any 
preparation, perceive the natural limits of the isthmus, is crossed nearly in 
its middle by a thick fasciculus of arciform fibres, which constitute the 
annular protuberance (protuberantia annularis), pons Varolit, or mesocephalon 
(or nodus encephali). All the portion lying behind this fasciculus belongs 
to the rachidian bulb (bulbus rachidicus or medulla oblongata). That in front 
forms the cerebral peduncles (crura cerebri). 

The superior face (Fig. 323), covered by the cerebellum and the 
posterior extremity of the cerebral lobes, is more mammillated than the pre- 
ceding. Passing from behind to before, on the superior face of the medulla 
oblongata, there is remarked the section of the peduncles of the cerebellum, the 
valve of Vieussens, the corpora quadrigemina, and the optic layers (thalami optict). 

The lateral faces (Fig. 824), concealed in their anterior part by the 
hemispheres of the brain, exhibit the profile of the medulla oblongata, pons 
Varolii, peduncles of the cerebellum ne ees cerebral peduncles 

72), corpora quadrigemina, an alami optici. 
ee bean of a isthmus belongs to the medulla oblongata, and 
continues the spinal cord, from which it is only distinguished artificially. 

The anterior extremity is enveloped, below and on each side, by the 
oblique fasciculi which form the two optic nerves, and beneath which are 
insinuated the fibres of the isthmus before they pass into that part of the 
cerebral hemispheres which bears the name of corpora striata. bos 

After this enumeration of all the organs whose aggregation constitutes 
the isthmus of the encephalon, we will examine them in detail, and in the 
following order: 1, Medulla oblongata ; 2, Pons Varolii ; 3, Crura cerebri $ 
4, Crura cerebelli; 5, Valve of Vieussens - 6, Corpora quadrigemina : 
7, Thalami optict. After these, we will describe the pineal and pituitary 


676 


glands : 


inferior face of the isthmus.’ 


1g. woe 
Fig. 322 


GENERAL VIEW OF THE BRAIN; LOWER 
SURFACE. 

1, Olfactory lobe; 2, Cavity of the olfactory 
lobe; 3, External root of olfactory lobe ; 
4,5, Cerebral hemispheres ; 6, Cerebellum ; 
7, Optic chiasma, or commissure ; 8, Pitui- 
tary gland; 9, Optic nerves; 10, Tuber 
cinereum; 11, Crus cerebri; 12, Third 
cranial nerve; 13, Fourth nerve; 14, Pons 
Varolii; 15, Fifth nerve; 16, Sixth nerve; 
17, Seventh and eighth nerves; 18, Me- 
dulla oblongata, the number being placed 
on the olivary body ; 19, Anterior pyramid ; 
20, Roots of ninth, tenth, and eleventh 
nerves; 21, Twelfth nerve. 


THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


small appended lobes placed one on the superior, the other on the 


Medulla Oblongata. 
824, 329.) 


The medulla oblongata constitutes 


(Figs. 323, 


the posterior portion of the encephalic. 


isthmus; it succeeds the spinal cord, 
and extends forward as far as the pons 
Varolii. It isa thick peduncle of a 
white colour, wider before than behind, 
flattened above and below, and having 
four faces—-an inferior, superior, and 
two lateral. 

Inferior face (Fig. 322).—This 
face rests in the channel of the basilar 
process. Convex from side to side, 
and limited anteriorly by a transverse 
fissure which separates it from the 
pons Varolii, posteriorly it does not 
offer anything to distinguish it from 
the medullary axis. 

On the middle line there is a well- 
marked fissure, a continuation of the 
inferior fissure of the cord, which lies 
between two very elongated promi- 
nences that are sometimes but little 
apparent, and from their form are 
named the pyramids of the bulb (corpora 
pyramidalia) (Figs. 822, 19; 338, b). 
The base of these pyramids touches 
the pons Varolii, and their apex is 
insensibly lost, posteriorly, on reach- 
ing the spinal cord. 

Outwardly is an almost plane sur- 
face, bordered anteriorly by a trans- 
verse band which lies immediately 
behind the pons Varolii; sometimes 
it is covered for the greater part of its 
extent by a very thin expansion of 
arciform fibres, between the anterior 
border of which and the transverse 


1 There is far from being any agreement as to the number of parts which ought te 


compose the encephalic isthmus, some authorities making more, some less. 


The limits 


of this small apparatus will, nevertheless, be found perfectly circumscribed if it be ex- 
amined in the lower animals, and particularly in the Horse. An antero-posterior section 
of the encephalon made to one side of the median plane appears to us all that is needed 
to definitely settle the point. This section, seen in figure 329, shows in the plainest 
manner that the encephalic prolongation of the spinal axis extends to the corpora 
atriata, and that it comprises the medulla oblongata, pons Varolii, cerebral and cerebellar 
peduncles (or crura), the corpora quadrigemina, and the thalami optici. All these, then, 
Yelong to one and the same system—the medullary peduncle, which serves as a bond 
of union between the three principal masses of the encephalon, and which we have 
designated the isthmus. It may be added that this manner of considering the encephalic 
istumus perfectly agrees with the teachings of physiology. 


THE ISTHMUS. 677 


band, and particularly in pieces that have been hardened by alcohol or 
acidulated water, is seen a slight oblong prominence which corresponds to 
what in Man is designated the olive} (corpus olivare); it is isolated from 
the pyramid by o longitudinal groove, whence emerge, in front, the roots 
of the sixth cranial pair, behind, those of the twelfth; outwardly, it is 
limited and separated from the restiform body by the origin of the majority 
of the roots belonging to the glosso-pharyngeal and pneumogastric nerves. 

Superior face.—Covered by the cerebellum, it is channeled in its middle 
by an excavation (Fig. 323, 5), which constitutes the floor of the fourth 
ventricle. This cavity is prolonged forward above the pons Varolii, between 
the cerebellar peduncles, and from its forming behind an angle resembling 
the point of a pen, it has been named the calamus scriptorius. 

_ Two thick cords, prolongations of the superior fasciculi of the medulla 
spinalis, border the calamus scriptorius on each side; these are designated 
the corpora restiformia. Lying together at their posterior extremities, they 
separate anteriorly, so as to represent the branches of a V (Fig. 323, 1). 

Lateral faces.—Much narrower than the other two, and showing two 
thick borders, these faces give the profile of the corpora restiformia (Fig. 
324, 2), corpora pyramidalia (4), and the fasciculus between these two. 


2. The Pons Varolii.. (Figs. 822, 14; 324, 5.) 


The pons Varolii, also named the tuber annulare or mesocephalon, is that 
part of the brain which stands out prominently across the isthmus, between 
the medulla oblongata and the crura cerebri, and-which is lodged in the 
anterior depression of the basilar process. ae? fa, 

It is a semicircular band of white transverse fibres thrown across, like 
bridge, from one side to the other of the cerebellum. “In every sense it is 
convex, wider in its middle than in its lateral portions, and crossed from 
behind to before by a shallow median groove for the basilar artery. On its 
free surface, whose principal features we have just described, it offers for 
consideration two borders and two extremities. 

The posterior border, slightly convex, is separated from the medulla 
oblongata by a faint groove. ; 

The anterior border, also convex, but indented in its middle, largely over- 
hangs the crura cerebri, which are limited on this side by a well-marked 
fissure. 

The extremities are bent upwards to enter the substance of the cerebellum, 
in the form of two thick cords, which constitute the middle crura cerebelli 
(Fig. 324, 6). They exhibit the apparent origin of the trifacial nerves. 

The pons Varolii does not exist in birds. 


3. The Pedunculi or Crura Cerebri. (Figs. 322, 11; 324, 7.) 


These are two very large white fasciculi, visible at the inferior surface 
and sides of the isthmus, covered superiorly by the corpora quadrigemina 
and thalami optici, and continuous, above the pons Varolii, with the fibres of 
the medulla oblongata ; while their anterior extremities enter the cerebral 


hemispheres. 
These peduncles (or crura) are separated from each other by a middle 


* This prominence corresponds to the corpus olivare of Man only in its position, for 
it has not its structure. 
4 


678 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


fissure—the interpeduncular, which bifurcates in front to cireumscribe the 
mammillary or pisiform tubercle (corpus albicans, bulbi fornicis) (Fig. 327, 
18): a small, single, and rounded elevation of a white colour, like the 
peduncles, covered by the pituitary gland, whose root is represented by the 
tuber cinereum, and is situated in front of this body. 

Behind, the crura cerebri are limited by the anterior border of the pons 
Varolii. In front, they are circumscribed by the optic nerves, which pass 
obliquely around their anterior extremity and join on the middle line before 
the tuber cinereum, to form a commissure called the chiasma of the optic 
nerves (Fig. 822,7). On the sides, their tissue is confounded with that of the 


Fig. 323. 


SUPERIOR VIEW OF THE ENCEPHALIC ISTHMUS 


1, 1, Corpora restiformia ; 2, Section of the middle 
cerebellar peduncles ; 3, Section of the posterior 
cerebellar peduncle; 4, Anterior cerebellar 
peduncle; 5, Floor of the posterior ventricle ; 
6, Valve of Vieussens; 7, 7, Tubercula testes ; 
8, 8, Tubercula nates; 9, 9, Thalami optici; 
10, Corpus geniculatum internum ; 11, Corpus 
geniculatum externum; 12, Corpus striatum ; 
13, Tenia semicircularis; 14, Pineal gland; 
15, Its peduncle; 16, Common anterior open- 
ing; 17, 17, Anterior pillars of the trigonal; 
18, Trifacial. nerve; 19, Facial nerve; 20, 
Auditory nerve ; 21, Glosso-pharyngeal nerve ; 
22, Pneumogastric nerve; 23, Spinal nerve. 


other two, related by its inner border 


corpora quadrigemina and thalami 
optici, which are superposed on the 
cerebral peduncles. It may be 
remarked that the part of their 
lateral face situated below the 
tubercula testes, forms a well- 
defined triangular space, designated 
the band of Reil, lateral triangular 
fasciculus, and lateral oblique fasci- 
culus of the isthmus. 


4. The Crura Cerebelli. 


The cerebellum is attached to 
the upper face of the isthmus by 
two short and thick lateral funiculi 
of white substance, between which 
is comprised the posterior ventricle; 
these constitute the cerebellar crura. 

Three distinct fasciculi enter 
into the composition of each of 
these cords: an anterior, a posterior, 
and a middle. 

The latter, or middle cerebellar 
peduncle (crus cerebelli ad pontem), 
is the largest of the three. It is 
formed by the prolongation of the 
extremities of the pons Varolii 
(Figs. 323, 2; 324, 6). 

The posterior cerebellar peduncle 
(crus ad medullam oblongatum), the 
most slender, is formed by the 
restiform body, one portion of which 
is reflected below the posterior root 
of the auditory nerve to reach the 
substance of the cerebellum. It 
is closely united to the preceding, 
from which it is with difficulty dis- 
tinguished (Fig. 323, 3). 

The anterior cerebellar peduncle 
(processus e cerebello ad testes) is a 
fasciculus very distinct from the 
to the middle peduncle, which ‘it 


THE ISTHMUS. 679 


obliquely crosses, loses itself in the cerebellum by its supero-posterior 
extremity, arriving behind the testes, and passing beneath these small organs 
by its antero-inferior extremity, along with the band of Reil or supero-lateral 
fasciculus of the cerebral peduncles. 

In studying the structure of the cerebellum, we will see how these 
peduncles comport themselves in its interior. 


5. Valve of Vieussens. (Fig. 323, 6.) 


This designation is given to a very thin, white lamella which unites, on 
each side, the two anterior cerebellar peduncles. In shape it is nearly a 
parallelogram. Its superior face is covered by the cerebellum ; the inferior 
concurs in forming the floor of the cerebellar ( fowth) ventricle. The two 
lateral borders are joined to the peduncles this valve unites; the anterior is 
attached behind the testes; while the posterior adheres to the anterior 
vermiform eminence (linguetta laminosa) of the cerebellum. 

Gall has considered this lamella as a commissure of the anterior cere- 
bellar peduncles, and we think rightly; for we see it formed almost 
exclusively of transverse fibres which run from one of these peduncles to 
the other. These fibres are most apparent in front, where the membrane is 
much thicker ; behind, they are mixed with some longitudinal fasciculi. 


6. Corpora Quadrigemina or Bigemina, (Fig. 823, 7, 8.) 


These are four round eminences, placed in pairs, which surmount the 
cerebral peduncles behind. The two posterior, the smallest, are also named 
the tubercula testes, and the anterior pair the tubercula nates. 

The posterior corpora quadrigemina, or tubercula testes, are related, in front, 
with the anterior eminences : behind, with the anterior cerebellar peduncles 
and the valve of Vieussens, from which they are separated by a transverse 
groove, from the bottom of which arise the pathetici nerves. An oblique 
band unites them, outwardly, to that portion of the optic layer designated 
the corpus geniculatum internum. 

The anterior corpora quadrigemina, or tubercula nates, are distinguished 
from the preceding not only by their larger volume, but by their colour, 
which is grey, that of the testes being white. They are also rounder, nearer 
each other, and covered by the cerebral hemispheres; while the posterior 
rather lie beneath the cerebellum. A curved groove isolates them, in front, 
from the thalami optici. 


7. Thalami Optict. (Fig. 323, 9.) 

This name is given to that part of the upper face of the isthmus which 
is situated in front of the corpora quadrigemina. These thalami are 
therefore placed above the anterior part of the cerebral peduncles. 

Larger altogether than the corpora quadrigemina, and more so before 
than behind, each exhibits a grey, slightly convex, and very irregularly 
quadrilateral surface, covered by the velum interpositum, which separates it 
from the cornu Ammonis (pes hippocampi), and from the posterior pillars of 
the cerebral trigonal (fornix). ; : 

Inwardly, they incline towards each other in forming on the median 
line a somewhat deep fissure, in which runs, from before to behind, two 
white longitudinal bands that will be noticed hereafter as the anterior 
peduncles of the pineal gland. This fissure enters, behind, into the comion 


680 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


posterior opening (foramen commune posterius) ; in front, into the common 
anterior opening (foramen commune anterius) : orifices which will be described 
with the interior of the isthmus. 

Outwardly, the thalamus optici shows two prominences called the corpora 
geniculata, from which arise the second pair of nerves ; placed one before 
the other, the posterior nearer the middle line than the anterior, these two 
projections are distinguished as eaternal and internal. The corpus genicu- 
latum externum is always more voluminous, better defined, and situated on a 


Fig. 324. 


LATERAL VIEW OF THE ISTHMUS. 


1, Medulla oblongata; 2, Corpus restiforme; 3, Lateral fasciculi of the medulla 
oblongata; 4, Inferior fasciculus, or corpus pyramidale; 5, Pons Varolii; 6, 
Middle peduncle of the cerebellum; 7, Cerebral peduncle; 8, Testis; 9, Natis; 
10, Corpus geniculatum internum ; 11, Corpus geniculatum externum ; 12, Optic 
nerve ; 13, Fourth nerve resting on the band of Reil; 14, Sensitive root of the 
trigeminal nerve; 15, Its motor root ; 16, Facial nerve; 17, Auditory nerve. 


more elevated plane than the internal corpus geniculatum, which is united to 
the ies corpora quadrigemina by an oblique band (Figs. 323, 10; 
324, 11). 

Behind, the thalami optici appear to be notched to receive the nates, 
which they slightly inclose. 

In front, they are separated from the corpus striatum by a groove, at the 
bottom of which is a narrow strip named the semicircular band (tenia semi- 
circularis). 


Pineal Gland or Conarium. (Fig. 823, 14.) 


This name has been given to a small tubercle of a reddish-brown colour, 
in the form of a pine-cone, enveloped by a duplicature of pia mater from 
the velum interpositum, with its apex upwards, and its base resting on the 
common posterior opening, which it closes, and around which it is attached 
by a circular lamella. 

From this lamella is detached, in front, two fibrous cords—the anterior. 


THE ISTHMUS. 681 


peduncles of the conarium (or habenw). These (Fig. 323, 15) are two 
narrow white bands, which commence at the base of the pineal gland, and 
are directed forward parallel to each other, in the bottom of the fissure of 
the thalami optici, to which they firmly adhere. On arriving at the anterior 
common opening, they become attached to the anterior pillars of the cerebral 
trigonal (or crura of the fornix). Sometimes they are very narrow and 
separated by an interval; but more frequently they are relatively wide, 
and immediately in contact on the median line. 

The conarium is far from always offering the same volume; it has 
been exhibited in its usual dimensions in Figure 323, and in Figure 327 
it is shown as incomparably larger. 

The structure of the pineal gland appears to be very simple, and only 
comprises one substance of a brownish-grey colour, apparently amorphous, 
and sometimes studded with calcareous granulations (acervulus), but with- 
out any internal cavities. 

This organ and that whose description follows, do not belong, properly 
speaking, to the system of the encephalic isthmus; but are rather, as we 
have already said, appended glands, which merit to be described apart, the 
same as the three immense cerebellar and cerebral ganglia. If we have 
studied them in this place, it was only for the sake of simplification. 


9. Pituitary Gland. (Figs. 322, 8; 327, 19.) 


The pituitary gland, also named the hypophysis cerebri and suprasphe- 
noidal appendage, is @ small disc-shaped tubercle, fixed to the anterior 
extremity of the interpeduncular fissure by the pituitary stem (infundibulum) 
and the tuber cinerewm. 

a. The tuber cinereum is a little ominence of a grey colour, situated in 
the middle line, between the corpus albicans and the chiasma of the 
optic nerves, at the anterior limit of the encephalic isthmus. This emi- 
nence is hollow, and its cavity is nothing more than a diverticulum of the 
middle ventricle. 

b. The infundibulum is only a short conical prolongation, whose base is . 
attached to the tuber cinereum, and its apex to the superior face of the 
pituitary gland. The cavity of the tuber cinereum is continued into the 
infundibulum, and terminates in. a cul-de-sac towards its summit. This 
prolongation, also formed of grey substance, is distinguished by its great 
fragility ; so that it requires some care to preserve it intact when opening 
the cranium at its base. : 

ce. The pituitary gland is lodged in the sella turcica, where it is en- 
veloped by the suprasphenoidal duplicature of dura mater; it is a small, 
nearly circular body, flattened above and below, and more or less thick, 
according to the subjects. ; 

Its inferior face rests on the sphenoid bone through the medium of the 
dura mater, to which it is strongly adherent ; the superior covers the corpus 
albicans, with a portion of the cerebral peduncles, and in front receives 
the insertion of the pituitary stem. Its circumference responds to the supra- 
sphenoidal duplicature, whose interior forms the cavernous sinus. 

There is no cavity in the pituitary gland. The matter composing it 
appears to be almost amorphous; it is yellow in the anterior half of the 
organ, and brown in its posterior portion. 


682 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


INTERNAL CONFORMATION OF THE ISTHMUS. (Fig. 327.) 


The encephalic isthmus is hollowed at the thalami optici by a central 
cavity, named the méddle (or third) ventricle, which is extended backwards 
beneath the corpora quadrigemina by a canal—the aqueduct of Sylvius ; 
this opens, below the valve of Vieussens, into the posterior (or fourth) ven- 
tricle—another cavity comprised between the cerebellum and medulla 
oblongata. These three diverticuli will be studied in succession. 


1. Middle Ventricle, or Ventricle of the Thalami Optici. (Fig. 327, 13.) 


The middle ventricle is an irregular cavity, elongated from behind to 
before, depressed on each side, and offering for study two walls, a floor, a 
roof, and two extremities. : 

The two walls are smooth, nearly plane, or very slightly concave from 
above to below. 

The floor is extremely narrow, and only forms a channel whose bottom 
corresponds to the interpeduncular fissure, which is nearer in front than 
behind, and_to the corpus albicans and tuber cinereum. The cavity of 
the latter (Fig. 827, 20), prolonged into the pituitary stem, communicates 
with the middle ventricle, and assists in its formation. 

The roof, as narrow as the floor, and, like it, nothing but a channel, is 
constituted by the two thalami optici which are joined to one another above 
the ventricle, forming a thick 
grey commissure (Fig. 827, 
16). It is terminated at its 
extremities by the two orifices 
already noted as the posterior 
and anterior common foramina. 
The posterior common foramen 
(Fig. 327,'15) commences be- 
hind the grey commissure, and 
terminates at the base of the 
pineal gland by an irregu- 
larly expanded cul-de-sac. It 
is limited behind by the pos- 
terior white commissure, a thin 
fasciculus of transverse fibres 
placed in advance of the cor- 
pora quadrigemina, above the 
TRANSVERSE SECTION OF THE ENCEPHALON aT entrance to the aqueduct of 

THE POSTERIOR COMMON FORAMEN, Sylvius, (or iter a tertio ad 


1, White substance of the hemisphere, or centrum quartum ventriculum) and whose 
ovale of Vieussens; 2, 2, Grey substance forming i 


the external layer of the convolutions; 3, Section extremities are lost in the sub- 
of the corpus callosum; 4, 4, Interior of the Stance of the thalami optic1 
lateral ventricles; 5, Section of the great vena (Fig. 325, 9). The anterior 
Galeni ; 6, 6, Cerebral peduncles; 7, 7, Section of common foramen also desig- 
the isthmus; 8, Posterior common foramen; 9, ted th oe Mi 
Posterior white commissure; 10, Entrance to the ®ve uo Sor Gen of Peed 
aqueduct of Sylvius, (and iter ad infundibulum) 
wie (Fig. 327, 14), is the medium 
of communication between the middle and lateral ventricles, and affords 


a passage to the vascular cord which unites the two choroid plexuses. It is 


THE ISTHMUS. 683 


pierced in front of the grey commissure, beneath the summit of the fornix, 
whose two pillars concur to circumscribe it, and between which is seen the 
anterior white commissure. This is a small band of white transverse fibres, 
analogous to that which constitutes the posterior commissure, but stronger, 
and passing in front of the anterior pillars of the fornix, its extremities 
entering and becoming lost in the corpus striatum on each side. 

The posterior eatremity of the middle ventricle, narrower than the 
anterior, and placed on a more elevated plane, is continuous with the 
aqueduct of Sylvius, whose entrance (Fig. 325, 10) is beneath the pos- 
terior commissure, towards the common foramen. 

The anterior extremity, more dilated than the posterior, is situated 
immediately above the optic chiasma, and is only separated from the bottom 
of the great interlobular fissure of the brain by a small and very thin grey 
lamina attached to that chiasma, and for this reason named by writers the 
grey root of the optic nerves. This lamina (lamina cinerea) is readily seen 
when the optic commissure is turned down on the pituitary gland; it is 
sufficient to traverse this to enter the middle ventricle. 

The ependymis, which lines the central canal of the medulla spinalis, 
also covers the walls of this cavity; through the aqueduct of Sylvius, it is 
prolonged into the posterior (or fourth) ventricle ; by the anterior common 
foramen into the lateral ventricles, and thence into the spaces in the middle 
of the olfactory lobes. 


2. Aqueduct of Sylvius. (Fig. 327, 6.) 
This is a longitudinal median canal passing beneath the corpora quad- 
rigemina, and above the peduncles of the brain. 
Its anterior extremity communicates with the middle ventricle, and the 
posterior opens below the valve of Vieussens into the cerebellar (or fourth) 
ventricle. 


8. The Posterior or Cerebellar Ventricle. (Fig. 327, 5.) 


This ventricle’ (or sinus rhomboidalis), situated beneath the cerebellum, 
between its peduncles, and above the medulla oblongata and pons Varolii, 
is a cavity elongated from before to behind, and almost entirely occupied 
by the vermiform processes. ; 

Its superior wall is formed by these two processes, the valve of Vieussens, 
and that of Renault. The inferior, or floor of the cavity, is represented by 
the excavation on the superior face of the medulla oblongata, and whichis 
prolonged in front, above the pons Varolii, to near the testes. ; 

The anterior extremity communicates with the aqueduct of Sylvius. 
The posterior occupies the summit of the calamus scriptorius. 


STRUCTURE OF THE ISTHMUS. 


The encephalic isthmus being only a prolongation of the spinal cord, 
ought to resemble it in its structure ; and this is, in fact, what is observed, 
particularly in its posterior part, the common features of their organisation 
disappearing as we approach its anterior extremity. ; 

After what has been said as to the external conformation of the medulla 
oblongata, we know that this organ presents, on each of its Jateral halves, 
traces of a division into three principal fasciculi: a superior, formed by 


1 Ag the cerebellum concurs in the formation of this cavity it would perhaps be 
better to defer its study until that organ has been described. 


684 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


the corpus restiforme ; an inferior, represented by the corpus pyramidale ; 
and the third, or intermediate of the other two. These three fasciculi are 
only the continuation of those we have recognised in the cord itself, and 
whose properties they share—the first being sensitive, and the others motor. 

The superior fasciculus, or 
corpus restiforme, lying, at its 
posterior extremity, beside its 
fellow of the opposite side, is 
separated from it for the greater 
part of its extent by the excava- 
tion that constitutes the floor of 
the fourth ventricle. It rests on 
the external part of the lateral 
fasciculus. At the extremity of 
the pons Varolii is given off a 
small branch that forms the pos- 
terior cerebellar peduncle; it 
then continues its course on the 
side of the posterior ventricle, 
soon joins the anterior cerebellar 
5 peduncle, which is above it, and 
DISSECTION OF THE MEDULLA OBLONGATA, sHowine With it passes beneath the cor- 

THE CONNECTION OF ITS SEVERAL FASCICULI, OR pora quadrigemina. 

STRANDS. The inferior fasciculus, the 
A, Corpus mae B, ool opticus ; C, D, raed thinnest of the three, comprises, 

adr . mmissure connectin: = : 

them ath the: eicitine F, Conor meat io as has been said, all that portion 

mia; P, P, Pons Varolii; st, st, Sensory tract ; of the bulb which constitutes 

mt, mt, Motor tract ; g, Olivary tract; p, Pyrami- the pyramid. But when this 

dal tract ; og, Olivary ganglion ; op, Optic nerve; eminence is null, or but slightly 

3m, Root of third pair (motor); 5s, Sensory root marked. we ought to recognise 

of the fifth pair. a: ; 6 

the limits which separate it from 

the lateral fasciculus by the line of insertion of the roots of the great 
hypoglossal nerve, supposed to be prolonged to the pons Varolii, near the 
point of emergence of the external motores oculorum nerve. Its fibres 

artly intercross with those of the opposite fasciculus, in the bottom of 
the middle fissure. They all pass above or across the transverse fasciculi 
of the pons, to constitute the inferior plane of fibres of the cerebral 
peduncles. 

The lateral or intermediate fasciculus of the bulb, comprised between the 
line of insertion of the hypoglossal nerve-roots, and those of the motor roots 
proper to the glosso-pharyngeal, pneumogastric, and spinal nerves, differs 
but little from the inferior cord. By a portion of its upper face it forms 
the floor of the fourth ventricle. After leaving the pons Varolii, like the 
pyramidal fasciculus, it goes fo assist in the formation of the cerebral 
peduncles, and particularly of their triangular oblique fasciculus. 

In examining, collectively, at these peduncles, the medullary fasciculi 
prolonged into the isthmus, we observe nearly the same order of superposition 
as in the bulb; but it is no longer possible to distinguish them clearly from 
each other, they being confounded with those of the opposite side. Their 
fibres can be seen prolonged in a mass beneath the corpora quadrigemina, 
across the proper substance of the thalami optici, and passing into the 
corpora striata, to disappear on each side, like a fine expanding sheath, in the 
middle of the cerebral hemispheres. 


THE ISTHMUS. 685 


To this important system of white longitudinal fibres—a prolongation of 
those of the spinal cord—is found annexed as complementary elements in the 
organisation of the encephalic isthmus, several systems of transverse fibres— 
also white—and masses of grey substance. The following is a summary 
exposition of the arrangement of these new elements. In proceeding from 
behind to before, we notice, among the white transverse fibres : 

1. The expansion of arciform fibres which sometimes covers the inferior 
face of the bulb (Fig. 338, 7): their superior extremity is lost in the 
corpus restiforme; the inferior is buried in the intermediate fissure of the 
pyramid and the lateral fasciculus. 

2. The proper fibres of the pons Varolii: they constitute a very thick 
semicircular fasciculus whose extremities form the middle cerebellar 
peduncles and enter the cerebellum; this fasciculus envelops, inferiorly 
and laterally, the longitudinal fibres of the isthmus; it is crossed by several 
superposed planes of transverse fibres. 

3. The transverse fibres of the valve of Vieussens and those of the white 
commissures, which have been already noticed. 

The grey substance of the isthmus, which now remains to be mentioned, is 
far from being so abundant as the white substance, and, as in the spinal 
cord, it is principally deeply buried in the texture of the organ. In the 
medulla oblongata none is found on the track of the superior and inferior 
fasciculi of fibres; but the lateral fasciculi are intermingled with it, 
and there is a layer on the floor of the fourth ventricle. It is also found 
in the cerebral peduncles, and particularly in the prolongation of the lateral 
fasciculi of the bulb. 

Each of the corpora quadrigemina is composed of a small mass of this 
grey substance, and is covered by a thin pellicle of white matter which is 
scarcely perceptible in the anterior eminences. The optic thalamus is a 
similar mass, though more voluminous, darker coloured, and without a layer 
of white substance on its superficial face. 

Lastly, nerve cells also exist between the various layers of transverse 
fibres of the pons Varolii, and between the tubes which constitute the valve 
of Vieussens. 


DIFFERENTIAL CHARAOTERS IN THE ISTHMUS OF OTHER THAN SOLIPED ANIMALS, 


Apart from its volume, the isthmus does not present any sensible differences in 
Ruminants and the Pig. In the Ox, it is remarked that: 1, The inferior pyramids of the 
medulla oblongata are ‘more prominent, and the transverse cords parallel to the pons 
Varolii more voluminous than in Solipeds; 2, The crura cerebri are short ; 3, The optic 
nerves are larger than in Solipeds; 4, There is a largely developed pituitary gland, 
excavated by a wide cavity, and flattened from above to below; 5, Lastly, the testes are 
more conical and less distinct from the nates than in the animals already studied. 

In the Carnivora, the fourth ventricle is very large and deep, and bordered by 
salient and detached corpora restiformia, Its floor is marked by some white transverse 
strie. The pons Varolii is large; the cords (or columns) of the medulla oblongata, parallel 
to its posterior border, are as developed as in the Horse, without taking into consideration 
the difference in size of the two species. The pyramids are voluminous, and the olivary 
bodies well defined. The testes are larger than the nates. 


COMPARISON OF THE ISTHMUS OF MAN WITH THAT OF ANIMALS. 


In human anatomy, the medulla oblongata and encephalic isthmus are described 
Bec an shows on its lower face a well-marked groove, a continuation of that of the 
gpinal medulla; it terminates anteriorly in a deep fossa named the foramen cxcum of 
Vicq-d' Azyr. The pyramids are well marked, The olivary bodies are much more 


686 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


prominent than in animals, and are also distinguished by the presence of a grey 
nucleus in their interior. ‘The medulla oblongata of Man has not the transverse band, 
bebind the pons Varolii, which we described in the Horse (Fig. 333). 

With regard to the isthmus proper, it contains the parts in front of the medulla 
oblongata already studied in the domesticated animals. The pons Varolit is very. large ; 
the crura cerebri are separated from each other by a groove, at the bottom of which are 
several small openings. The fourth ventricle is deep, is bordered by well-developed 
corpora restiformia, and inclosed posteriorly and laterally by the valves of Tarin (velum 
medullare posterius). On its floor are remarked transverse striz (linea transversx) named 
the barbs of the calamus scriptorius, which are also found in the Dog. ‘The testes are 
smaller than the nates; but the difference in their volume is less considerable than exists 
between Solipeds and Ruminants. Their structure is already known. 


Articte II].—Taer CEeresenium. 


The cerebellum, or posterior enlargement of the encephalon, is the 
single mass supported by the isthmus, separated from the cerebrum by the 
transverse partition constituting the tentorium cerebelli, and lodged in the 
posterior compartment of the cranial cavity, which almost exactly gives the 
measure of its volume. 


1. External Conformation of the Cerebellum. 


The cerebellum, isolated by dividing its lateral peduncles from the 
medullary prolongation on which it is fixed, presents the form of an almost 
globular mass, slightly elliptical, elongated transversely: while its external 
surface is furrowed by a great number of sulci, the two principal of which 
(sulci horizontalis) pass in a circular manner on each side of the middle line 
around the organ, dividing it into three lobes—a middle and two lateral. 

The three lobes of the cerebelium are not always readily distinguished 
from each other, in consequence of the shallowness and irregularity of the 
two sulci separating them. We will, nevertheless, study them in 
succession, and afterwards examine, in a general manner, the furrows on their 
superficies, , 

Middle lobe (Fig. 321, 2)—This has been compared to a silk-worm 
rolled in a circular manner around the middle portion of the cerebellum, 
and whose two extremities are joined, without being confounded, below the 
inferior face of the organ. 

This vermicular disposition is not well defined in the middle and 
superior portion of the cerebellum, where this lobe is always more or less 
subdivided into large multiple and irregular lobules; but it is better 
observed before and behind, in those points which correspond to the two 
extremities of the animal selected ag a term of comparison. There may 
be remarked two longitudinal eminences transversely annulated on their 
surface, and curved beneath the cerebellum in such a way as to come in 
contact with each other. These eminences constitute the anterior and 
posterior vermiform processes. Their extremities are lodged in the fourth 
ventricle, whose roof they concur in forming. 

On the anterior vermiform process the posterior border of the valve of 
Vieussens is inserted. 

The posterior vermicular process also receives the insertion of a valve 
already mentioned, and which must be again briefly referred to. This valve, 
described for the first time by M. Renault,’ forms a lamina of a certain 
thickness stretched above the calamus scriptorius. It has exactly the 
triangular form of this space, and presents a superior face covered by the 


( The late eminent veterinary teacher and director of the Alfort School.) 


THE CEREBELLUM. 687 


posterior vermiform process; an inferior face, studded in some points with 
small vascular loops ; a base fixed to the vermis, near the free extremity of that 
prominence, and to its lateral parts; two lateral borders, attached to the 
corpora restiformia on each side of the calamus scriptorius ; and a summit 
corresponding to the receding angle of the excavation, This lamina is, 
doubtless, nothing more than a septum formed by the external pia mater, 
and on which is extended the internal membrane that covers the walls of 
the cerebellar ventricle. Otherwise, it isin direct continuity, towards its base, 
with an evident dependency of the pia mater-—the pleaus choroides.' 


rior fora-- 
19, Ditto 


¢ from the velum 
h the middle ventricle; 21, 


bo) 
; 24, Septum lucidum ; 


jt is as voluminous as it 
pus albicans ; 


leni, proceedin: 


land ; 


from it are too much forward ;-8, 
Great vena Ga 
Foramen of Monro; 15, Common poste 


he cerebellum; 6, Aqueduct-of Sylvius ; 


Section of the cor 


o) 


3, Ditto of the crura cerebri; 4, Ditto of the 


11, 
Ditto of the corpus callosum 


m communicating wit 


? 


Section of the pineal g 


he line proceeding 
aken 


10, 


he figure and t 


5, Posterior ventricle covered by t 
Internal extremity of the hippocampus ; 


Section of the valve of Vieussens—t 


Natis 3. 9,. 


Ditto of the pons Varolii; 


9 
a 
Anterior white commissure; 18, 


Interior of the pituitary ste 


hiasma ; 22, Ditto of the fornix; 28, 


Section of the optic c 
25, Cerebral convolutions ; 


lexus, 12; 13, Middle ventricle ;; 14, 
17, 


MEDIAN AND VERTICAL SECTION OF THE ENCEPHALON. 
26, Olfactory lobule. 


1, Section of the medulla- oblongata ; 
from which this drawing was t 


cerebellum, showing the arbor vite ; 
interpositum and choroid p 


7, 
of the pituitary gland; 20, 


men;-16, Grey commissure ; 


was in the specimen 


i — d like two irregular 
Lateral lobes (Fig. 821, 3, 3). These are shaped hl rregu 
segments of a ee Their surface, fissured and lobulated in every direction, 
presents nothing interesting externally, superiorly, or posteriorly. It is by 
- 1 This septum is represented in the rudimentary state in Man, by the vavulz Tarini. 


688 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


their inferior part that the peduncles enter the substance of the cerebellum ; 
and behind this point, beneath their lateral parts, the cerebellar pleaus choroides 
is applied. . Sons ‘ 

The cerebellar choroid plecuses.— This name is given to two small reddish 
granular masses, formed of vascular loops, elongated from before to behind, 
depressed above and below, and comprised at their internal borders between 
the corpora restiformia and the inferior face of the lateral lobes of the 
cerebellum, to which they are strongly adherent by their superior face. 
These two plexuses are joined together by means of Renault’s valve, which 
is united to them towards its base. 

Sulei and lobules of the cerebellum.—On examining, in a general 
manner, all the sulci which intersect the external surface of the cerebellum, 
we see that they penetrate to very unequal depths in the substance of the 
organ, and that they divide it into successively decreasing segments, of 
which Figs. 324 and 327 may furnish a sufficient idea. 

There is at first a certain number of principal lobules, which are divided 
into secondary lobules; and these, again, are in their turn separated into short 
lamelle, representing the extreme limits of cerebellar lobulation. 


2. Internal Conformation and Structure of the Cerebellum. 


The cerebellum concurs, by its inferior plane and the internal face of 
its peduncles, to form the cavity already described as the posterior or cere- 
bellar ventricle; but in the mass of the organ itself there is no trace of 
excavation or other peculiarity. This is demonstrated in the most evident, 
manner by sections of its substance made either in an antero-posterior 
or in a transverse direction. We only sce in these traces of the sulci which 
divide the organ into lobules; and they also afford evidence as to the 
structure of the cerebellum, showing that, like all the other parts of the 
cerebro-spinal axis, it is formed of white and grey substance. 

The latter, spread over the entire surface of the organ, constitutes the 
cortical layer of the different segments of which it is composed. It is even 
prolonged into the convolutions which increase the surface-extent of the 
cerebellum ; in each lobule it may be decomposed into superposed layers, 
parallel to the lamina of white substance that forms the nucleus of the 
lobule ; between these layers of grey substance is a very thin mass of white 
matter. 

The white substance, enveloped on every side by the grey, forms two 
thick nuclei occupying the centre of the lateral lobes, and which are united 
and confounded on the median line in the texture of the middle lobe. 

These two nuclei, in continuity on each side with the cerebellar 
peduncles, are only their prolongations or intercerebellar portions. They 
send into the middle of each principal lobule a long and thick branch, which 
gives off smaller divisions that ramify in the secondary lobules, and from 
which escape a new series of ramuscules that enter the smallest segments ; 
this gives to the cerebellum a beautiful arboreal aspect, justly designated 
by the older anatomists the arbor vite. (See Figs. 324, 327, 329, for 
representations of the arbor vite cerebelli, 

In the interior of these nuclei, a little in front, there sometimes exists a 
small, slightly-grey spot; this is the trace of the corpus rhomboideum (or 
dentatum of Man). 

The nuclei of the white substance of the cerebellum are constituted, like 
the matter of the medulla, by nerve-tubes which are continuous on one side 


THE CEREBRUM, 


with the crura cerebelli, and on the other terminate in the cc 
substance. 


689 
Us of the grey 


In the grey spot that forms the corpus rhomboideum, is a great number of 


large nerve-cells, 

With regard to structure, the grey matter of the cere- 
bellum may be decomposed into two layers; the super- 
ficial is very rich in blood-vessels, has a greyish tint, and 
is composed of large nerve-cells and smaller rounded ele- 
ments; the deep layer is of a yellow colour, and also 
contains nerve-cells and round elements, though the latter 
are smaller than in the other layer, and have been sometimes 
mistaken for simple nuclei. 


DIFFERENTIAL CHARACTERS OF THE CEREBELLUM IN OTHER THAN 
SOLIPED ANIMALS, 


The external and inteinal conformation of the cerebellum offers 
the closest analogies in the domesticated mammifers. In all, its 
volume, compared with that of the other encephalic lobes, is not 
invariable. Thus, while the relation between the weight of the cere- 
belium and that of the brain of the Horse is as 1 to 7; with the Ox 
it is as 1 to9; with the Dog 1 to 8; with the Cat 1 to 6; and with 
the Sheep 1 to 3. These are the only ditterences to be noted 


COMPARISON OF THE CEREBELLUM OF MAN WITH THAT OF ANIMALS, 


In Man, the encephalic mass being enormous, the cerebellum 
is absolutely more considerable in volume than in the larger domesti- 
cated animals; though, in proportion to the cerebral hemispheres, it 
is smaller than in the Ox, its relation to the latter lobes being as 
1 to 8. 

It is wider than it is long, and projects much beyond the medulla 
oblongata. It has three lobes; but these are only visible on its 
lower aspect; on the opposite face, the median lobe is depressed and 
concealed beneath the lateral lobes, which are so large that they 
have been named the cerebellar hemispheres. The inferior vermis 
forms a free projection in which is the fourth ventricle; this is 
termed the wvula of the cerebellum. The uvula is connected at each 
side with the valves of Tarin: lamin of nerve-substance lodged for 
the most part in tle fourth ventricle, and hidden by the lower face 
of the cerebellar hemispheres. The latter constitute, on the sides of 
the medulla oblongata, two prominences situated one below the other, 
above the crura cerebelli; the first is designated the amygdala or 
tonsil, the second the pneumogastric lobule (or flocculus). 


Articte [V.—Tue Crereprum. 


The cerebrum, the principal portion of the encephalon, 
comprises the two anterior lobes or hemispheres of that 
apparatus: enlargements which are elongated in the direc- 
tion of the great diameter of the head and cranial cavity, 
lie beside each other on the middle line, and are united 
at their central part by a transverse commissure, and by 


Fig. 328 


SECTION OF THE 
CORTICAL  SUB- 
STANCE OF THE 
CEREBELLUM. 

ud, Meduliary sub- 
stance, showing 
its fibres; 6, Sub- 
stantia ferrugi- 
nea, composed of 
fibres and cell- 
nuclei; c, Grey 
surface, granu- 
lar at the sur- 
face, and contain- 
ing large mul- 
tipolar branch- 
ing cells near 
the substantia 
ferruginea. 


the encephalic isthmus, whose anterior extremity penetrates, inferiorly, 


into their substance. 
tion.) 


(See Fig. 329 for a good idea of this penetra- 


These two lobes together represent an ovoid mass, having its thick 
extremity adjacent to the cerebellum; it is depressed from above to below, 
deeply divided above, in front, and behind by a median antero-posterior 


630 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


iving i i its inferi the insertion of the 
fissure, and receiving in the middle of its inferior face 


cerebral peduncles. : ; 
This mass, seven to nine times more voluminous than the cerebellum, 


fills the anterior compartment of the cranial cavity, and thus occupies the 


rreater portion of that space. ve ees 
‘ It pclubite for study its external conformation, its internal conformation, 


and its structure. 


ANTERO-POSTERIOR. AND VERTICAL SECTION OF THE ENCEPHALON TO ONE SIDE 
OF THE MEDIAN LINE, 


1, 1, Isthmus of the encephalon; 2, Medulla oblongata; 3, Pons Varolii; 4, Cerebral 
peduncle; 5, 6, Corpora bigemina; 7, Optic thalamus; 8, Pituitary gland; 9, 
Pituitary stem; 10, Optic nerve; 11, Cerebellum; 12, 12, Cerebral hemisphere ; 
13, Ventricle of the hemisphere; 14, Corpus striatum: 15, Cornu Ammonis; 16, 
Olfactory lobe; 17, Ventricle of the olfactory lobe. 


EXTERNAL CONFORMATION OF THE CEREBRUM. 


Instead of examining the organ in mass, with regard to its external con- 
formation, we will first consider the great interlobular (or longitudinal) fissure 
which divides it lengthways; and afterwards study its two lateral halves, 
or cerebral hemispheres, which in reality constitute two symmetrical organs. 


1. The Longitudinal Fissure. 


This fissure exists throughout the vertical and antero-posterior cireum- 
ference of the cerebrum, but does not everywhere offer the same disposition. 
On the superior aspect of the organ it is very deep, and when the two 
hemispheres are separated to discover its extent, we see that it reaches to 
the upper face of the great commissure—the corpus callosum. Behind, it 
curves between the posterior lobes of the hemispheres, but without corres- 
ponding directly with the posterior thick rounded margin of the corpus 
callosum, above which there is a feeble adhesion established between the 
two halves of the cerebrum, forming a kind of bridge. But in front it passes 
to the anterior margin of this commissure, and is prolonged in the interval 
of the anterior lobes of the hemispheres to reach the inferior face of the 
organ. 

Examined inferiorly, the interlobular fissure is well defined in front, 


THE CEREBRUM. 691 


where it attains the anterior border of the corpus callosum; but behind, on 
leaving the chiasma of the optic nerves, and which marks the anterior limit 
of the isthmus, this fissure appears suddenly to stop. This is because it 
becomes considerably enlarged, and is changed into a vast notch which 
admits the anterior extremity of the isthmus: or rather, it bifurcates to pass 
on each side between the hemisphere and the anterior extremity of the 
medullary prolongation, at first crossing the optic nerve, then turning round 
the cerebral peduncles and corpora bigemina, above which its branches 
unite, and are confounded with the undivided part of the fissure, which 
separates the posterior lobes of the hemispheres. 

There exists, then, around the point of immergence of the isthmus in the 
cerebrum a well-marked line of demarcation, which constitutes, above and 
laterally, a very deep fissure in which is imbedded the vascular expansion 
known as the velum interpositum ; this aperture is designated the fissure of 
Bichat, or great (transverse) cerebral fissure. 

The interlobular fissure receives the longitudinal septum of the dura 
mater—or falx cerebri. It also lodges arteries and veins, among which it 
is necessary to distinguish the great vena Galeni, which ascends from the 
bottom of the fissure, after passing round the posterior border of the corpus 
callosum. 


2. The Cerebral Hemispheres, 


Each hemisphere or Jateral moiety of the cerebrum, represents an ovoid 
segment, in which we may consider four faces and two extremities. 

The superior face is convex, and is covered by the roof of the cranium, 
which is formed by the frontal and parietal bones. 

The external, equally convex and insensibly confounded with the 
adjacent faces, responds to the lateral walls of this cavity: that is, with the 
squamous portion of the temporal bone, the parietal and frontal bones, and 
the ala of the sphenoid. 

The inferior, irregularly mammillated, rests on the sphenoid bone. The 
internal is plane, and for the greater part of its extent is related to the other 
hemisphere through the medium of the falx cerebri; it is in its central and 
inferior portion that the union of the two halves of the cerebrum takes place, 
by means of the great cerebral commissure and the anterior extremity of the 
isthmus. 

The posterior extremity of the hemisphere corresponds to the cerebellum, 
which slightly depresses it, and from which it is separated by the transverse 
septum of the dura mater (tentorium). : ; 

The anterior extremity or lobe is lodged in the fossa formed on each side 
of the crista galli by the frontal and sphenoid bones. ' 

The anatomical peculiarities to be found in these different regions of the 
external surface of the hemisphere are: 1, On the inferior face, and from 
before to behind, a detached appendage constituting the olfactory or ethmoidal 
lobule, a transverse groove named the fissure of Sylvius, and an elongated 
eminence called the mastoid lobule; 2, Everywhere else, the cerebral convolu- 
tions—depressed elevations curved about in a thousand ways, and separated 

i ing depth. 
” a ae ee peculiarities in an inverse order to that of their 
n. 
ae Convotutions (Figs. 821, 322, 327 ).—The cerebral convo- 
lutions are constituted by the folding of the external surface of the brain, 
apparently with the intention of considerably augmenting the extent of that 


692 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


surface. These folds, which are very deep, are extremely irregular; on the 
surface of the hemispheres their disposition somewhat resembles the 
convolutions of the intestines, a circumstance to which they owe their 
designation. In Solipeds their number is considerable, and not inferior in 
this respect to those on the human brain. ; . 

Notwithstanding their great irregularity, the cerebral convolutions offer 
a somewhat constant arrangement; so that it is possible to describe them 
one by one. This has been done in human anatomy ; but it would be need- 
less to repeat the task in the case of the domesticated animals. 

2. Masror or Spxenor Losvtz (Fig. 285, u).—This is a large pyriform 
eminence, corresponding to what has been described in Man as the inferior 
(or middle) lobe of the hemisphere, and occupies the posterior part of the 
inferior face of the hemisphere. This eminence is curved upon itself, and 
shows its convexity outwards. Its internal border, which corresponds to 
the cerebral peduncle, concurs in the formation of the great transverse 
fissure. Its large extremity is turned forward, and margined by the fissure 
of Sylvius. The posterior extremity insensibly disappears on the inner 
side of the posterior lobe of the hemisphere. emi ; 

This eminence ought to be considered as a large projecting convolution. 
It is excavated internally by a cecal cavity, which constitutes the bottom 
of the posterior or reflected portion of the lateral ventricles. 

3. Fissure or Syztvius.—Thus is designated a transverse depression 
situated in front of the optic nerve and mastoid lobule, in which is lodged 
the middle cerebral artery. 

4, OuFactory or Erumorp Losure (Figs. 321, 6; 322,1; 327, 26; 
829, 16)—The appendage to which this name is given is detached from 
the inferior face of the hemisphere, where it arises by two white-coloured 
roots; the external of these is continuous with a long convolution that 
borders the outside of the mastoid lobule, while the internal, the shortest, 
originates on the inner face of the hemisphere, in advance of the optic 
chiasma. Between these roots appears a prominent surface of a triangular 
form, constituting the extra-ventricular nucleus of the corpus striatum (substantia 
perforata). The. appendage thus formed passes forward, terminating 
in an oval enlargement (bulbus olfactorius) extending much beyond the 
anterior extremity of the brain, to be lodged in the ethmoid fossa. 

The olfactory lobe possesses an internal cavity, a diverticulum of the 
lateral ventricle (Fig. 322, 2). Both lobes being regarded as the first pair 
of cranial nerves, we will return to their description when studying the 
encephalic nerves. 


INTERNAL CONFORMATION OF THE BRAIN. 


In separatingt he cerebral hemispheres py their upper face, we discover 
the great commissure known as the corpus callosum: the first object that 
presents itself for study in the internal conformation of the brain. 

If we afterwards remove, by a horizontal section, and with a sharp 
instrument, all that portion of the hemispheres which covers this commissure, 
and also if the latter be excised to a certain extent to the right and left of the 
median line, we will penetrate two symmetrically disposed cavities in 
the centre of each hemisphere. These cavities are the lateral or cerebral 
ventricles, 

They are separated on the middle plane by a thin partition—the septum 
lucilum, which is attached to the corpus callosum by its upper border, and 
fixed by its inferior border into the fornix, a kind of median arch beneath 


lal 


THE CEREBRUM. 693 


which is the foramen of Monro, or orifice communicating with the two ven- 
tricles. On the floor of these cavities is observed two large eminences, the 
corpus striatum and the hippocampus ; with a vascular and apparently granu- 
lated cord forming the cerebral choroid pleaus, a dependency of the velum inter- 
positum. 


It now remains to enter into some detail with regard to the anatomical 
characteristics of all these parts. 


1. The Corpus Callosum. (Figs. 327, 330.) 


The corpus callosum is a kind of arch thrown over the two lateral ven- 
tricles, while at the same time it is a commissure uniting the two hemispheres. 
It belongs exclusively to mammalia. 

Composed entirely of white substance, it affects a quadrilateral form, 
being elongated in an antero-posterior direction, and thus presents for study 
two faces, two borders, and two extremities. 

The superior face, free in the middle, and corresponding to the bottom 
of the interlobular fissure, is covered right and left by the substance of the 
hemispheres. It is traversed from before to behind by two white, and yy 
generally very delicate, cords, the tractus ‘longitudinalis (the chorde 
longitudinalis of Lancisii) of the corpus callosum, which lie together on the:" 
middle line. The inferior face is oe 
divided by the insertion of the sep- Fig. 330 A? 
tum lucidum into two lateral por- ; 
tions, each of which forms the roof 
of one of the cerebral ventricles. 

The two lateral borders of the 
corpus callosum disappear in the 
central substance of the hemis- 
pheres, where it is almost impos- 
sible to distinguish their limits. 

The posterior extremity appears 
at the bottom of the interlobular 
fissure, after the destruction of the 
adhesion usually established above 
it between the two hemispheres, in 
the form of a thick, rounded en- 
largement (splenium) folded in 
genu, below, and confounded with 
the middle part of the fornix. It 
is prolonged, laterally, above the 
ventricular cavities, by forming two. conpus CALLOSUM, AFTER REMOVAL OF 
angles (linew transverse) which are aye ypper PORTION OF THE CEREBRAL 
soon lost in the white central sub- HEMISPHERES. 
stance of the cerebrum. 1, Centrum ovale of Vieussens; 2, 2, Chorde 

The anterior extremity comports _longitudinales; 4, 4, Cornua, or angles of the 
itself in a similar manner between posterior extremity; 5, 5, Ditto of avterior 
the anterior lobes of the hemi °'"™'Y- 
spheres. ; . 

2. The Lateral or Cerebral Ventricles. (Figs. 825, 331.) 

The lateral ventricles are two large elongated cavities excavated in the 
hemispheres, lying against each other in their anterior moiety, and divergent 
in their posterior part, which is very much curved backwards, outwards, and 
downwards, to open into the substance of the mastoid lobule. 


AT 


694 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


This disposition permits the division of the cerebral ventricles into two 
regions : an anterior, and a posterior or reflected. 

The anterior region is separated in the median plane from the opposite 
ventricle, by the septum Iucidum and the summit of the fornix, beneath 
which is the foramen of Monro establishing a communication between the 
middle and the two lateral ventricles, and between these latter. Above, it 
offers a smooth wall formed by the corpus callosum. Below, on its floor, 
there is first remarked, in front, the corpus striatum; behind, the internal 
portion of the hippocampus; in the middle, an oblique groove running from 
behind to before, and without inwards, at the bottom of which floats the 
choroid plexus. The anterior extremity of this region, occupied by the 
base of the corpus striatum, is continued by a narrow opening into the 
interior of the olfactory lobe. The posterior is prolonged, without any line 
of demarcation, by the reflected portion of the ventricular cavity. 

The latter region occupies the most declivitous portion of the posterior 
lobe of the hemisphere, and presents a strongly curved canal whose con- 
cavity looks forward; this canal terminates in a cul-de-sac in the substance 
of the mastoid lobule. On the floor of this canal is delineated the-posterior 
portion of the hippocampus and the choroid plexus. 

A very fine membrane—the ventricular arachnoid—plays the part of a 
serous membrane and covers the walls of these cavities, being spread every- 
where over a layer of white substance, prolonged into the ethmoidal diverti- 
culum, and continuous, through the foramen of Monro, with that of the middle 
ventricle, This membrane secretes a limpid and transparent liquid, analogous 
to the cerebro-spinal fluid, though in health it is always in small quantity. 


3. The Septum Lucidum. (Fig. 327, 24.) 


This appellation is given to a thin median lamella, standing vertically 
between the two lateral ventricles, elongated from before to behind, widened 
considerably at its anterior extremity, terminating in a point at its posterior 
extremity, and inserted above into the corpus callosum, below into the back 
of the fornix. 

On the faces of this lamella, which is formed of white substance, is 
spread the proper membrane of the lateral ventricles. In the human species, 
a narrow ventricular cavity has been described as found in its substance; 
but this does not appear to exist in our domesticated animals. 


4. The Fornix (or Trigonum). (Fig. ais, 3.) 

Also named the vault of three or four arches, the fornix (arch) is a single 
and median body in the interior of the brain, concurring to separate the two 
ventricles, and serving to support the septum lucidum, It is depressed from 
below to above, and is of a triangular form; its apex, looking downward, stands 
in the median plane above the foramen of Monro and the thalami. optici 
though separated from the latter by the velum interpositum and the hippo- 
campi, and receives on its upper face the insertion of the septum lucidum. 
Behind, towards its base, and on the median plane, the fornix is confounded 
with the corpus callosum, which it supports; it is prolonged on each side 
by a lamina extending to the surface of the hippocampus, forming the 
cortical layer of this deep convolution of the brain, and with its congener 
constituting the posterior pillars (posterior crura, or corpora fimbriata) of the 
fornix. 

In front, at its apex, the fornix is also attached to the corpus callosum, 


THE CEREBRUM. 695 


and divides into two cords or anterior pillars (crura) (Fig. 323, 17), which 
pass in front of the anterior cerebral commissure, are inflected downwards 
and backwards, in traversing the optic thalamus, on the sides of the middle 
ventricle, and, finally, have their extremities confounded with the mammillary 
process (corpus albicans), 

These two crura limit, in front, the foramen commune anterius or foramen 
of Monro, over which the apex of the fornix is thrown across like an arch, 


The fornix is white throughout its whole extent, with a greyish tint 
towards its summit. 


5. The Hippocampi. (Fig. 331, 4.) 


The hippocampus or cornu Ammonis (from its resemblance to a ram’s 
horn, the crest of Jupiter Ammon), is an elongated projection, a veritable 
internal convolution of the brain (is, in fact, the internal surface of the 
gyrus fornicatus or convolution lying upon the corpus callosum, and which 
terminates at the fissure of Sylvius) ; it occupies the floor of the anterior 
region of the lateral ventricle, and is prolonged throughout its reflected por- 
tion, whose curvature it exactly follows. Considered together, the two 
hippocampi somewhat closely resemble the uterine cornua of the Cow. 

By their internal extremity, they are in contact with each other beneath 
the middle portion of the fornix, and above the optic thalamus, which is sepa- 
rated from them by the velum interpositum (Fig. 327, 9). Their external 
extremity occupies, in the mastoid lobule, the cul-de-sac of the reflected 
portion of the lateral ventricle. 

The central mass of this projection is formed by a nucleus of grey sub- 
stance, covered superficially by a cortical layer of white—a prolongation of 
the posterior crura of the fornix. 

Towards the concave border of the hippocampus, this white lamina 
offers a kind of wide hem, beneath which the choroid plexus passes; this 
hem constitutes a small curved band, like the cornu Ammonis, wider at its 
middle part than at its extremities, and is named the corpus fimbriatum, or 
tenia hippocampus. 


6. The Corpora Striata. (Fig. 331, 7.) 


The corpus striatum is another projection on the floor of the cerebral 
ventricle, occupying the anterior region of that cavity. . 

This eminence is pyriform in shape, and obliquely elongated from behind 
to before, and without to within. Its surface is smooth, and regularly convex. 
Its base, or anterior extremity, corresponds to the anterior cecum of the 
ventricle. The summit, or posterior extremity, disappears at the commence- 
ment of the reflected portion of the ventricular cavity. Outwardly, the 
corpus striatum is limited by a groove that forms the angle of union between 
the floor and roof of the ventricle. Inwardly, it is separated from the optic 
thalamus and cornu Ammonis by another sulcus, in which the choroid 
plexus floats, and which is oblique inwards and forwards, and shows at the 
bottom the tenia semtcircularis (Fig. 823,18). This is a flattened white 
cord, which disappears inwardly towards the foramen of Monro, and bends 
outwards along the optic nerve to within about 3-8ths of an inch from the 
chiasma; in this way forming a sort of circular band around the anterior 
extremity of the isthmus, beneath which all the fibres of the latter pass to 


reach the cerebral hemispheres. : : 
The corpus striatum owes its name to its structure, being composed of a 


696 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


thick nucleus of grey substance that crosses the longitudinal fibres of the 
encephalic isthmus in passing into the hemispheres ; these fibres appear in 
several pvints of this nucleus as very distinct white streaks. 
This deep nucleus, which is in- 
Fig. 331. termediate to the superior extremity 
of the isthmus and the principal 
mass of the hemisphere, comprises 
the entire thickness of the floor of 
the lateral ventricle, and projects 
outwards, beneath the inferior face 
of the hemisphere, between the two 
roots of the olfactory lobe, where 
it constitutes the extra-ventricular 
nucleus of the corpus striatum: so 
named in contradistinction to the 
oblong eminence in the interior 
of the ventricle, which is often de- 
signated the intra-ventricular nucleus 
of the corpus striatum. 


7. The Velum Interpositum and 
Choroid Plexus. (Fig. 331, 6.) 


ANTERIOR PORTION OF THE LATERAL VENTRI- The velum interpositum (velum 
CLES OF THE DOG, EXPOSED BY REMOVAL oF vasciulosum, tela choroidea) is a vas- 
THE ROOF. cular expansion dependent from the 

1, Corpus callosum; 2, Anterior part of the pia mater, which penetrates the 
corpus callosum, turned forward after destruc- rain by the transverse fissure, and 
tion of the septum lucidum, to show the fornix, . . . : 
3, 3; 4, 4, Hippocampi; 5, 5, Tenia semi- insinuates itself between the tha- 
circularis ; 6, 6, Choroid plexus; 7, 7, Corpora lamus opticus and the convolution 
striata, ofthe cornu Ammonis. The velum, 

on arriving beneath the tenia hip- 
pocampus, terminates in the choroid plexus: a red, granular-looking cord, 
which is suspended by its antero-external border, and projects into the 
interior of the lateral ventricle. 

The choroid plexuses of the brain extend from the anterior extremity of 
the corpus striatum to the bottom of the cecum in the mastoid eminence 
or lobule. In the anterior region of the ventricle, they occupy the oblique 
sulcus which traverses that part, to the inner side of the corpus striatum. 
In the posterior region, they float in front of the cornu Ammonis. Their 
anterior or internal extremity, more voluminous than the external, always 
forms 2 small appendage which remains quite free. They are united to 
each other, near this extremity, by an intermediate cord, which traverses 
the foramen of Monro in passing beneath the fornix. 

Like the velum interpositum, the choroid plexuses are formed by a net- 
work of arteries and veins. They are often incrusted in calcareous matter, 
and may be the seat of more or less voluminous cysts. 

The veins proceeding from this vascular apparatus are very voluminous, 
and by their union form the great vena Galeni, which bends round the 
splenium of the corpus callosum to reach the interlobular fissure, and pro- 
ceeds to the sinus of the falx cerebri. 


THE CEREBRUM. 697 


STRUCTURE OF THE OEREBRUM. 


; The structure of the brain is certainly one of the most interesting points 
in the study of the nervous centres; for on a perfect knowledge of it 
depends the solution of the most difficult problems in the physiology of the 
nervous system. — Numerous attempts have been made to dine lei its 
intimate organisation ; but we must here omit the multitude of secondary 
détails revealed by these researches, and limit ourselves to the essential 
and fundamental facts. 

The two substances enter into the texture of th i 
and both are exactly disposed as in the cerebellum. sac 

The grey substance extends over the entire external surface of the brain 
and dips into the sulci; thereby augmenting the extent of that surface and 
forming the cortical layer of the cerebral convolutions. This layer, ‘it is 
necessary to remark, though perfectly similar to that of the cerebellar 
lobules, is not homogeneous throughout its thickness, but may be decom- 
posed into several secondary stratified layers, between which are extremely 
thin. lamellae of white substance; one of these lamelle nearly everywhere 
forms the most superficial pellicle of the convolutions. 

According to Kdlliker, there are six layers in the cortical substance of 
the brain, and these are disposed as follows: 1, A superficial white layer ; 
2, Grey layer; 3, First white streak; 4, Yellowish-red layer, external 
portion; 5, Second white streak ; 6, Yellowish-red layer—internal portion. 
Tn all these layers are nerve-cells, but in proportion as 
they are pale, these cells are few and small; the cells 
themselves contain colouring matter in the reddish- 
yellow layers. Everywhere they are furnished with 
from one to five fine prolongations, which bring them into 
communication with the very fine nerve-tubes of the 
cerebral hemispheres. (Lockhart Clarke gives seven 
layers for this cortical substance.) 

In the middle of each hemisphere, the white substance 
constitutes a considerable nucleus, which, from its form, 
is named the centrum ovale of Vieussens (Figs. 325, 1; 
330, 1), and which is united to that of the opposite side 
by the great cerebral commissure, or corpus callosum, 
sending a prolongation into each convolution; thus ex- 
hibiting the exact disposition of the lateral white masses 
of the cerebellum, with which the nuclei of the hemi- 
spheres have also another point of resemblance, in that 
they are attached to the cerebral peduncles, as the first are 
to the cerebellar. But the latter peculiarity is less evident corricaL SUBSTANCE 
than the others—which are at once obvious in horizontal OF THE CEREBRAL 
and transverse sections of the brain—and can only be HEMISPHERES. 
clearly demonstrated by the manipulations necessary to % oe a a 
unravel the intimate texture of the white substance. pray Eye : a 

In studying this texture in brains hardened by nitric white streak, com- 
acid, washed in pure water, and exposed to dry air for posed of horizontal 
a day or two, we perceive that the white cerebral sub- fibres; d, Greylayer; 
stance is entirely composed of fine fibrous lamelle, ae white 
diverging in every direction, corresponding by their con- : 
centric extremity to the centre of the hemisphere, and abutting, by their 


Fig. 332. 


698 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. 


peripheral extremity, on the inner face of the grey covering of the con- 
volutions. soos ; 

The fibres of the white substance of the hemispheres are connected with 
those of the encephalic isthmus, through the latter being prolonged into the 
texture of the corpus striatum, where they appear either in the form of strie, 
or as an elongated nucleus, known as the double semicircular centre of Vieus- 
sens ; they then pass to the outside of the ventricular cavity, and plunge into 
the centrum ovale of the hemisphere, where they are manifestly continued by a 
portion of the fibres constituting it. It has been said that these fibres, instead 
of thus disappearing in the hemisphere, ascend at first to the right and left 
on the external side of the lateral ventricle, and are afterwards inflected in- 
wards above that cavity, to join on the median line; and in this way form the 
corpus callosum. I have searched for this arrangement in our domesticated 
animals, and particularly in the Dog, whose brain is well adapted for study- 
ing the corpus callosum, but without success. It has always appeared to 
me that the extremities of the transverse fibres which form this great com- 
missure are lost in the white substance of the hemispheres, some passing 
above, the others below; and I believe I have also seen some of the pedun- 
cular fibres radiating in the centrum ovale becoming insinuated between the 
extremities of the fasciculi of the corpus callosum, to gain the superior part 
of the hemisphere, without being continuous in any way with these fasciculi. 

Some of the nerve-tubes certainly terminate in the corpus callosum; 
but in this there is nothing extraordinary, as in that layer there are nuclei 
and some nerve-cells. 


DIFFERENTIAL CHARACTERS OF THE CEREBRUM IN OTHER THAN SOLIPED ANIMALS. 


The brain, in the animals now referred to, cffers some differences in volume, as might 
be inferred from what has been said regarding its relations with the cerebellum. In all, 
its development posteriorly is not so considerable that it covers the latter, which always 
remains exposed. 

Its general form varies a little. In the Ox, the hemispheres are proportionately 
larger posteriorly than in the Horse, but contract suddenly at the fissure of Sylvius, 
preserving their reduced dimensions in the anterior lobes; the latter are therefore more 
conical than in Solipeds. The cerebrum of the Dog is regularly ovoid, except at the 
extremity of the anterior lobes; there the hemispheres become much flattened from one 
side to the other, and form a kind of spur that enters the ethmoidal fossee. 

The cerebral convolutions are a little larger in the Ox than in the Horse, but they are 
also less numerous; they are still fewer in the Pig, and yet less in the Carnivora; we 
will see hereafter that they are absent in Birds. The particular features of the lower 
face of the hemispheres are the same in all the species; except that the olfactory lobes 
are more detached than in Solipeds; they are remarkably developed in the Dog. 

The ventricles are the same in all; the floor is always formed by the corpus striatum, 
hippocampus, and thalami optici, the roof by the corpus callosum. In the Or, the band 
of the hippocampus is remarkable for its width; in the Dog, the corpus striatum, pro- 
portionately voluminous, is of a deep grey colour on its surface. 


COMPARISON OF THE CEREBRUM OF MAN WITH THAT OF ANIMALS. 


The cerebrum of Man (Fig. 333) is distinguished by its regularly ovoid shape, and 
its great development, particulary behind, where it covers the cerebellum—a feature 
never observed in animals. 

Viewed superiorly, a cerebral hemisphere is clearly divided into three lobes: an 
anterior or frontal; a middle or sphenoidal, corresponding to the mastoid lobule of the 
Horse; and a posterior or occipital, covering the cerebellum. The two first are separated 
ly a narrow, deep, and sinuous fissure of Sylvius. 

The convolutions are larger, and separated by deeper furrows, than those of the 
Horse, but they are not more numerous. The olfactory lobes arise, as in animals, from 


two orders of roots, but they are small and entirely hidden beneath the inferior face of 
the frontal lobes. 


a 


THE CEREBRUM. 699 


The corpus callosum is ver i 
: ; ry developed, and, above the ventricle, forms, from befi 
Rie sl ta ) ‘ y , forms, from before to 
tion, oF Joreps major. prolongation named the frontal cornu and occipital prolonga- 
ere is nothing to note concerning the fornix and i 
Preece pie e g f and septum lucidum, except that there 
ities a = tc latter which communicates with the middle ventricle by a small 
The lateral ventricles offer remarkable differ i 

narka rences. They are not prolonged into the 
glaeiory lobes, Pa possess a diverticulum that enters ihe capil lobe, below the 
ee Ea oe his space is more or less developed, and terminates in a point ; it is 
named the ancyrotd or digital cavity, and shows on its floor a small convolution which 


Fig. 333. 


THE BASE OF THE HUMAN BRAIN. 

1, Longitudinal fissure; 2, Anterior lobes of cerebrum; 3, Olfactory bulb; 4, 
Lamina cinerea; 5, Fissure of Sylvius; 6, Locus perforatus anticus; 7, Optic 
commissure; 8, Tuber cinereum; 9, Third nerve ; 10, Corpus albicantium; 11, 
Fourth nerve; 12, Locus perforatus posticus; 13, F ifth nerve; 14, Crus cerebri; 
15, Sixth nerve; 16, Pons Varolii; 17, Portio dura of seventh nerve; 18, Middle 
lobe of cerebrum; 19, Portio molliss of seventh nerve; 20, Anterior pyramid ; 
21, Glosso-pharyngeal nerve; 22, Olivary body; 23, Pneumogastric nerve; 24, 
Lateral tract; 25, Spinal accessory nerve ; 26, Digastric lobe; 27, Hypo- 
glossal nerve; 28, Cerebellum; 29, Amygdala; 30, Slender lobe; 32, Posterior 
inferior lobe. 


has been designated the ergot of Morand (pes hippocampi). The diverticulum and con- 
volution do not exist in animals. The cornu Ammonis is slightly bosselated on its 
surface; it is limited, inwardly, by a band, and below this by a grey denticulated 
lamina, the gyrus fornicatus. 

The other portions of the human brain reserable those of animals; so that it is 
needless to allude to them. 


700 THE NERVES. 


THIRD SECTION. 
Tue NERVES. 


Tue nerves represent the peripheral portions of the nervous system, and 
are cords ramifying in every part of the body, having their origin in the 
medullary axis or its encephalic prolongation. Before commencing their 
special study, it is necessary to possess a summary notion of the principal 
distinctions of which they are susceptible, with regard to their origin, 
distribution and termination. 

Srructure.—The nerves are formed by an aggregation of the nerve-tubes 
already described. These are grouped in primary fasciculi, which are 
rectilinear or slightly undulating, and enveloped in a sheath of delicate con- 
nective tissue—the perineurium. These primary fasciculi are again assem- 
bled in bundles to compose secondary fasciculi, which are maintained by a 
layer of fibrous connective tissue thicker than the perineurium. Finally, 
these secondary bundles by their union constitute the nerve, around which 
the connective tissue becomes condensed, and found the neurilemma. 

Vessels traverse the connective tissue separating the fasciculi from each 
other ; they anastomose in a network whose elongated meshes are parallel 
with the nerve-tubes, and they are also surrounded by the nervi nervorum. 

On the track of certain nerves is observed a greyish enlargement, or 
ganglion. This is composed of a mass of nerve-cells, which are generally 
bipolar, and are situated on the course of the tubes. It is not quite known 
whether some of these tubes are not merely placed alongside the ganglion. 

Diviston.—Nerves are divided, with reference to their destination, 
into two principal groups: 1, The cerebro-spinal or nerves of animal life ; 
2, The ganglionic or nerves of organic life. 

CrrEpro-spinaL Nerves.—These emanate directly from the cerebro- 
spinal axis, and are divided into two secondary groups: 1, The cranial 
or encephalic nerves, which originate in the encephalon, and make their exit by 
the foramina at the base of the cranium, to be distributed almost exclusively 
in the head; 2, The spinal or rachidian nerves, arising in the spinal cord,. 
and passing to the muscular or tegumentary parts of the trunk and limbs, 
through the intervertebral foramina. 

After what has been said in regard to the apparatus of innervation, we 
know that the fibres composing these cords are distinguished, by their point 
of origin and their properties, into fibres of superior origin or of centripetal 
conductibility, and fibres of inferior origin or of centrifugal conductibility. ‘The 
first have a ganglion on their course. 

The cercbro-spinal nerves are exclusively formed of the first description 
of fibres, and are named sensitive nerves, as they conduct the stimulus which 
brings into play the sensibility of the brain. They are distinguished 
as nerves of general sensibility and nerves of special sensations (or sense). The 
first are destined to convey all stimuli except those determined by light, 
sounds, or odoriferous particles ; the second exclusively conduct the latter. 

The nerves which are composed only of fibres of the second kind are 
called motor nerves, because it is they which carry to the muscles the 
spontaneous stimulus to motion originated by the will. 

Those which are composed at once of motor fibres and fibres of 
general sensibility constitute the mixed nerves; these form the largest 
category. 


THE NERVES. 701 


Ganetionic Nerves.—These nerves, collectively represent ng the great 
sympathetic system, form below and on the sides of the spine, two long cords, 
rendered moniliform by the presence of ganglionic enlargements, and in 
the constitution of which nearly all the cerebro-spinal nerves concur; their 
ramifications, frequently ganglionic also, are destined to the viscera of the 
neck, the thorax, and the abdomen. 

In these nerves of organic life are found the two kinds of nerve-tubes, or 
fibres of centripetal and centrifugal conductibility. 

But these tubes appear to have only very indirect relations with the 
brain, for the will has no influence over the organs which receive their 
nervous fibres from the great sympathetic ; and, besides this, in health, the 
excitations developed in these organs are all reflected by the spinal cord, 
and do not provoke in any way the special activity of the encephalon—they 
are not felt. 

As the nerves of the great sympathetic system are principally formed of 
fine tubes, we ought perhaps to seek in this anatomical condition the cause 
of the special properties of these nerves; what tends to make this appear 
likely is the fact, that the cerebro-spinal nerves contain some of these 
tubes in their elements, and that they share, with the ganglionic ramuscules, 
the faculty of bringing into play the reflex power of the spinal cord. But 
this is only a probability, and is unsupported by any direct proof. 

However this may be, it must be remarked that the special anatomical 
and physiological characteristics of the sympathetic nerves should not cause 
them to be considered as a system independent of the first, or cerebro-spinal 
nerves. The fibres composing both have, in fact, a common origin in the 
medullary axis, or rather those of the ganglionic nerves emanate from the 
nerves of animal life. In the considerations which follow, we will therefore 
omit this distinction of the nerves into two groups. 

Oricin or THE Nerves.— We ought to distinguish in these cords their 
real or deep origin, and their superficial or apparent origin. ‘The latter is 
represented by the point of emergence of the roots of the nerves, which are 
ordinarily spread in a fan shape, then united, generally after a very brief 
course, into a single trunk, which offers at its commencement a ganglionic 
enlargement, if fibres of general sensibility enter into its constitution. 
Their real origin is the point of departure of these roots in the depth of 
the cerebro-spinal axis. This is not well known, perhaps, of any nerve, even 
of those whose radicles are easily followed into the substance of the nervous 
centres. 

Disrrizution or Nervss.—The nervous trunks, formed by the radicles 
of which we have just spoken, issue in pairs from the foramina at the base 
of the cranium or in the walls of the spine, to be distributed to all parts of 
the body by dividing into successively decreasing branches. Those among 
these branches which ramify in the organs of animal life, generally follow 
the track of the deep vessels or the subcutaneous veins, and are always 
found most superficial. Their ramescence is effected in a very simple 
manner, by the successive emission of the fasciculi composing the principal 
trunks, until they are completely expended. These branches pursue their 
course nearly always in a direct line; only some, as the ramifications of the 
two principal nerves of the tongue, describe very marked flexuosities, with 
the same protective intention as the arteries of that organ. Anastomoses 
sometimes join these branches to one another; and anastomoses, often 
enough complicated, unite many nerves together, and form what are called 
pleauses. But in these anastomoses, no matter how complicated they may 


702 THE NERVES. 


be, there is never any fusion of the nervous ramuscules, but simple aggrega- 
tion of their fibres, which always preserve their independence, characters, 
and special properties. These anastomoses, then, differ essentially from 
those of arteries, and never permit two trunks to mutually supplement each 
other when the course of one is interrupted. 

The nerves destined to the organs of vegetative life, and which arise 
from the two subspinal chains in whose formation nearly every pair cf 
nerves concurs, comport themselves in their distribution in a slightly 
different manner. They are enlaced around arteries, forming on these 
vessels very complicated plexiform networks, and yet the fibres composing 
them are as absolutely independent as in the anastomoses above described. 

TERMINATION OF THE NeRves.—This point should be examined separately 
in the case of the motor and the sensitive nerves: that is, in the muscles 
and the integumentary membranes. The distinction, however, is not quite so 
absolute as this, for the muscles always receive some sensitive tubes with 
their motor filaments. fo . ; 

In entering the muscles the motor nerves divide their branches, still 
appearing as double-contoured tubes. It was at one time believed that these 
fibres formed loops (Valentin) in the interior of the muscle, and returned 
to their starting point. This opinion has become obsolete since the 
ultimate termination of the nerves has been studied by Rouget, Krause, 


MUSCULAR FIBRES, WITH TERMINATION OF MOTOR NERVE; FROM THE 
GASTROCNEMIUS OF THE RANA ESCULENTA. 


a, Terminal pencil of a dark-bordered nerve-fibre; 6, Intramuscular naked axis- 
cylinder; c, Nucleus of the neurilemma; d, Clavate extremities of the nerve; e, 
Spaces of the muscle-nuclei; f, Terminal knob of nerve, with central fibres and 
vesicular dilatations of the nerve 


Kithne. Kélliker, Engelmann, Conheim (Beale), and others. What is known 
of this subject is as follows :—The voluminous, double-contoured nerve-tubes 
which, more or less, cross the direction of the muscular fibres, soon divide 
and form pale tubes on whose track are disseminated the nuclei. These 
tubes contain an axis-cylinder and a medullary layer. They pass on to a 
muscular fibre in the following manner: the nucleated sheath of the nerve- 
tube spreads, and is confounded with the sarcolemma; the medulla suddenly 
stops, and the axis-cylinder expands to form a minute granular mass named 
the terminal motor-plate. Is this plate situated without or within the 
sarcolemma? This question is differently answered by histologists; but, 


THE CRANIAL OR ENCEPHALIC NERVES. 703 


however this may be, this plate, which was discovered by Rouget, at first in 
reptiles, then in birds and mammals, has been studied by several micro- 
graphs, who are agreed as to its existence. There can, therefore, be no 
doubt that it is the ultimate termination of the motor-nerves. 

The mode of termination of the sensitive nerves varies as they are 
sensorial or general sensibility nerves. It appears to be demonstrated that the 
tubes of the sensorial nerves have at their extremity an elongated cell, 
analogous to that from which they started. An idea has been given of 
this arrangement in describing the olfactive portion of the pituitary mucous 
membrane. 

The other sensitive nerves have been supposed to terminate by peripheral 
loops, and again by free extremities passing into kind of cell elements. It 
is certain that these two modes exist simultaneously ; recurrent sensibility, 
which Claude Bernard demonstrated in some cranial nerves, proves 
that certain nerves terminate by loops. Our own experiments have 
shown: 1, That this recurrent sensibility is a general phenomenon belonging 
to the sensitive nerves of the limbs, and even to all the sensitive ramifications 
of the spinal nerves; 2, That the recurrent anastomotic loops are formed at 
different parts along the course of the nerves, either beneath the integument 
or in its texture. It is, then, proved that the peripheral loops constitute a 
mode of termination of the sensitive nerves. But this is not the only mode 
of termination observed. In the papille of the skin, in certain regions— 
hand, foot, lips, tongue, glands, clitoris—the corpuscles of Meissner, or tactile 
corpuscles, are found; these are composed of condensed connective tissue, 
and are conical, like a pine-cone, the summit towards the periphery. By their 
base enters one or more nerve-tubes, that ascend toward the apex in 
aspiral manner. In the conjunctiva, lips, etc., are also found rounded bodies 
analogous in their structure to the tact corpuscles, and which are named the 
corpuscles of Krause. Lastly, on the course of the collateral nerves of the 
fingers and in the mesentery of the Cat, are the Pacinian corpuscles: small 
globular or ovoid bodies formed of several concentric layers of connective 
tissue, and with a central canal into which penetrates and terminates, by one 
or more enlargements, a filament from the nerve-trunk (reduced to the axis- 
cylinder only).' 


CHAPTER I. 
THE CRANIAL OR ENCEPHALIC NERVES. 


Tar cranial nerves leave the encephalon in pairs, regularly disposed to 
the right and left, and designated by the numerical epithets of first, second, 
etc., counting from before backwards. ; ; 
Willis, taking for a basis the number of cranial openings through which 
the nerves passed, divided them into nine pairs, with which he described 
the first spinal pair, making it the tenth in the series of encephalic nerves. 
This division being faulty in some respects, it was sought to perfect it. 
Haller commenced by removing the first spinal or suboccipital pair of 
nerves to their proper region; then followed Scemmering and Vieg-d’Azyr, 


1 Arloing and Trépier. ‘Recherches sur la Sensibilité des Téguments et des Nerfs 
dela Main’ (Archives de Physiologie, 1869.) 


704 THE NERVES. 


who doubled the seventh pair of Willis, and reduced his eighth into three 
distinct ‘pairs, according to considerations derived from the destination and 
uses of these nerves. ‘The number of pairs of cranial nerves, their order of 
succession, and their nomenclature was then established in the following. 


manner: 


Ist pair or olfactory nerves. . corresponding to the Ist pair of Willis. 
2nd pair or optic nerves soe ee ew ew ee Qn pair _— 
3rd pair or common motores oculorum nerves. . . 8rd pair — 
4th pair or pathetici nerves... ee ee Ath pair _ 
5th pair or trigeminal nerves . . . . . . «Oth pair — 
6th pair or abducentes nerves. . . . . « « « ~ 6th pair —_— 
7th pair or facial nerves 6 ee ee et es } qth pair = — 
8th pair or auditory nerves). «6 1 + ew ew ee 
9th pair or glosso-pharyngeal nerves... 1 ee ; 

10th pair or pneumogastric nerves oe ee we). 8th pair _ 

11th pair or accessory or spinalnervs . . . 2. . . 

12th pair or great hypo-glossal nerves . . . . . . 9th pair _— 


In the following table, these nerves are classed according to their 
properties : 


olfactory nerves. . . . . . . . or Ast pair. 
1. pia of spe- optic ees gee ee Sg SB) Sg aw, de ee) ee 1G yas 
C1AMBEN SE auditory nerves. . . 1. 1 ee ee) Sth 
2. Mixed nerves trigeminal nerves . . . . . ..)) OSth 
with double glosso-pharyngeal nerves . . . wwe) 69th 
roots... pneumogastric nerves. . . . . . . 10th — 
common motores oculurum nerves . . . 3rd — 
pathetici nerves . . . . . . . .) O4th 
3. Motor nerves abducentes nerves . . . . . 66th — 
with single facial nerves . . . . . . 0 OUVth 
roots . accessory or spinal nerves. . . . . . llth — 


great hypo-glossal nerves . . . . . . I-th 


(Sir Charles Bell considered the fourth, seventh, and eighth nerves as 
forming a separate system, and to be allied in the functions of expression 
and respiration. In consonance with this view, he termed them respiratory 
nerves, and named that portion of the medulla oblongata from which they 
arise the respiratory tract.) 

One of the characteristics of the cranial nerves being their diversity, it 
is scarcely possible to study them as a whole, and it is only in their origin 
that they resemble each other in some points. We therefore confine 
ourselves to those general considerations which alone touch this part of 
their description. 

Do the cranial nerves proceed from the three principal apparatus com- 
posing the encephalon, or are they furnished by two, or even one of these? 
This is the question that should first be discussed. If it is evident to 
everyone that the isthmus gives rise to the majority of the encephalic 
nerves, and that the cerebellum hag nothing whatever to do with their 
emission, it is not agreed among anatomists as to the part the brain-proper 
takes in this emission. Two pairs of cranial nerves are indeed considered 
by several authors as emanating from the latter organ, while others regard 
them as derived from the isthmus. According to the first, only ten en- 
cephalic pairs of nerves belong to this prolongation of the spinal cord, the 
other two—the olfactory and optic nerves—proceed from the brain; while 
the second aver that all the cranial nerves without exception arise from the 
medulla oblongata. Let us endeavour to discover the truth. 

It is certain that this difference of opinion on a point apparently easy of 


THE CRANIAL OR ENCEPHALIC NERVES. 705 


solution, has its source in a misunderstanding, and is really not founded on 
facts, which are the same for everyone, their appreciation only varying. 
Nothing is more easy to prove. Look, in the first instance, at the optic 
nerve. This, according to some, proceeds from the corpora quadrigemina 
and thalami optici; it therefore arises from the brain. No doubt, if these 
two parts of the encephalon be considered as a portion of the hemispheres ; 
but this is far from proved, and in an anatomical and physiological point 
of view it is not so. As the corpora quadrigemina and thalami optici form 
part of the isthmus, it is natural to look upon itas the source from which 
the second pair of nerves arise. With regard to the first pair, their fibres 
are also connected with those of the isthmus, across the corpus striatum, as 
will be proved hereafter. But we are far from denying their connections 
with the hemispheres (see the description of the first pair), and which aro 
very intimate; though this proves nothing against our opinion. Therefore 
it is, that, in recognising in the disposition of the roots of the olfactory 
nerve conditions altogether special, we admit that the isthmus of the 
encephalon is the common point of departure for all the cranial nerves—an 
important and capital fact, and which constitutes, for the great category of 
encephalic nerves, a true family character. 
Among the other points relative to the origin of these pairs of nerves, 
are the following: All the encephalic nerves appear to be connected at 
’ their origin with the fasciculi of the isthmus, whose properties they share. 
All are equally connected with a centre of grey substance placed in the 
texture of the isthmus, and named by Stilling the nucleus of the nerves. 
The majority originate by converging filaments, the anterior of which come- 
from the brain, and the posterior from the side of the spinal cord. 


Preparation of the cranial nerves—Four preparations are necessary to study the 
cranial nerves : 

1. An encephalon extracted after opening the cranium by its base, and hardened 
by prolonged immersion in alechol or very diluted acetic acid. This piece permits the 
origin of the nerves to be studied (Fig. 322). 

2. The superficial nerves of the head; these are the auricular nerves, and the 
divisions of the subzygomatic plexus, with the suborbital and mental branches, as well 
as the superficial ramuscules of the three nerves of the ophthalmic branch of tl.e fifth 
pair (Fig. 110). 

3. A piece disposed asin figure 336, for the study of the maxillary nerves. To prepare 
it, the greater part of the masseter muscle should be removed in dissecting the masseterie 
nerve; the globe of the eye must be extirpated, the orbital and zygomatic procrs-es 
excised, the two maxillary sinuses opened, and the branch of the inferior maxillary bone 
chiselled off as in the figure. Lastly, the anastomosis of the facial with the sub- 
zygomatic nerve is dissected by cutting away the parotid gland. __ ; 

4, The deep nerves, including those of the globe of the eye ; this preparation should 
be made by following exactly the instructions given for dissecting the arteries of the 
head. Figure 335 will serve as a guide for details. ; a 5 ’ 

The pneumogastric and spinal nerves, which are not included in these considerations, 
should be prepared and studied at the same time as the great sympathetic. When 
treating of the latter, we will refer to them. 


1. First Pair, or Olfactory Nerves. (Figs. 827, 329.) 


The first cranial pair is constituted by the olfactory lobes, whose 
anterior extremities give off a great number of nervous filaments, which pass 
through the cribriform foramina to ramify in that part of the pituitary 
membrane lining the bottom of the nasal fosse. 

Each olfactory lobe is connected with the encephalon by two roots, an 
external and an internal, both composed of white substance (Fig. 322). 


706 THE NERVES. 


The external commences by a grey-coloured convolution which borders, 
externally, the mastoid lobule or inferior lobe of the hemisphere. The 
internal, followed from before backwards, turns round in the interlobular 
fissure, in front of the chiasma of the optic nerves, to mix with the cere- 
bral convolutions. These two roots circumscribe a triangular space oc- 
cupied by tho extra-ventricular nucleus of the corpus striatum, which they 
embrace. In brains which have been macerated for a long time in alcohol, 
it is easy to see that the fibres of these roots are continuous, in great part, 
with those of the corpus striatum, and commence with the fasciculi of the 
isthmus, which radiate and spread across the grey matter of that body. 

After the union of its two roots, the olfactory lobe is constituted by a 
wide white band that passes forward on the inferior face of the hemisphere, 
and soon terminates in a very elongated oval dilatation lodged in the 
ethmoidal fossa. This bulb is formed by grey substance on its inferior 
face and white substance on the superior. It is said to be a flattened 
ganglion applied to a band of white substance, which at first represents in 
itself the olfactory lobe. __ 

We have already seen that this lobe is hollow internally, and that it 
communicates with the lateral ventricles of the brain. This peculiarity, 
added to the special features of its external physiognomy, might, it appears 
to us, give rise to doubts as to the real nature of the lobes in question, 
It is evident that these are not nerves, but rather dependencies of the en- 
cephalon; and it is only conformable to custom that we describe them here 
as the first pair of encephalic nerves. 

The real olfactory nerves are the filaments which arise from the inferior 
face of the ethmoidal bulb or ganglion, and which traverse the cribriform 
lamella to gain the mucous membrane of the nose. Their number cor- 
responds with the ethmoidal foramina. At first very soft, delicate, and 
easily torn, they are enveloped on their passage through these apertures 
by a very strong neurilemma, which gives them great solidity. Some, in 
ramifying, descend on the septum nasi; others—and these are the most 
numerous—divide on the ethmoidal cells, where they form fine and more or 
less plexuous pencils, mixed up with the no less interesting divisions of the 
ethmoidal branch of the ophthalmic artery. Their terminal extremities 
do not descend below the upper third of the nasal fosse, but remain con- 
fined to the bottom of these cavities. 

These are the special nerves of smell. They receive the impression of 
odours and transmit them to the encephalon; and this function, which has 
been accorded and refused them time after time, has only been decided 
within the last thirty years. 


2. Second Pair, or Optic Nerves. (Fig. 329.) 


The nerves of vision present for consideration in their interesting study, 
their origin, course, termination, and properties, 

There has been much dispute, and there will probably be much more, 
with regard to the origin of the second pair. But without confining our- 
selves to an appreciation of the opinions which have pervaded science on this” 
matter, we will describe what we have observed in the domesticated animals. 

When the encephalic isthmus is isolated from the brain (Fig. 824, 12) 
and examined laterally, we recognise on its anterior limit the white band 
that constitutes the optic nerve. Studied at its origin, this band is con- 
tinued, in the most evident manner, with the external side of the thalamus 


THE CRANIAL OR ENCEPHALIC NERVES. 107 


opticus, where it forms the two enlargements known as the corpora geniculata. 
This thalamus ought, therefore, to be regarded as the point of departure of 
the nerve that bears its name. But as the external corpus geniculatum is 
in contact with the natis, and as the internal is united to the testis by a 
band of white fibres, lt is almost certain, according to several authorities, that 
the corpora quadrigemina concur in furnishing the constituent fibres of 
the optic nerves. 

At first wide and thin, the optic band (tractus opticus) is rolled round 
the cerebral peduncle from above to below and behind to before, and 
gradually narrows. Arrived at the inferior surface of the encephalon, it 
is changed into a funicular cord, which unites with that of the opposite 
side to form the commissure or chiasma of’ the optic nerves ; this is only a 
temporary fusion, as beyond it the two nerves reappear, and pass into the 
optic foramen, to reach the interior of the ocular sheath and the bottom 
of the globe of the eye. 

We will enter into some details on the relations of the optic nerves 
in the different points of the course we have indicated. 

In their flat portion, or origin, they are comprised between the cerebral 
peduncles and the hemispheres. From the point where they become free, 
at the inferior face of the encephalon, to the chiasma, they are covered by 
the pia mater, and adhere by their deep face to the superior extremity of 
‘the peduncles. 

The chiasma is lodged in the optic fossa, and receives on its deep face 
the insertion of the small grey lamina which bounds the third ventricle in 
front; for which reason this is generally described as the grey root of the 
optic nerves. But of all the proper connections of the chiasma, the most - 
important are certainly those which each nerve maintains with its congener 
at their junction. What becomes of the fibres of each nerve in this anas- 
tomosis? Do they cross one another to reach the opposite eye; or do they 
merely lie together, and afterwards separate, in order to go to the eye on 
their own side? Anatomy demonstrates that the fibres of the chiasma do 
not exclusively affect either of these arrangements; for in studying them 
in a specimen that has been macerated for some days, it is found that the 
majority cross each other in a very evident manner, but that a part regain 
the nerve corresponding to the side from which they came. It is there- 
fore seen that the nerves of the second pair are composed of one kind of 
fibres on this side of the chiasma, while beyond it they show two sorts— 
the fibres from the right and left sides. The majority, we have said, cross 
each other; and the proof of this is afforded in certain facts observed in 
pathological anatomy, which are of sufficient interest to be mentioned 
here. In the cases so frequently occurring in the Horse, where an eye is 
lost from the ravages of specific ophthalmia (fluxion périodique), the 
consecutive atrophy of the optic nerve nearly always stops at. the chiasma, 
though it sometimes happens that it gets beyond this ; and it is observed 
that it is usually the nerve opposite to the diseased eye which suffers the 
most. Otherwise, the arrangement just described is only a degree less 
advanced than that remarked in certain species—in the osseous fishes for 
instance—in which the optic nerves entirely cross each other without con- 
founding or mixing their fibres. ; : ; 

Beyond their commissure, the nerves of the second pair are in relation 
with the walls of the optic foramina, then with the posterior rectus muscle 
(retractor oculi), which envelops each nerve as in a sheath. In the orbits 
they are also related to some other nerves and vessels. 


708 THE NERVES. 


With regard to its ermination, the optic nerve enters the globe of the 
eye by piercing the sclerotic and choroid coats, towards the most de- 
clivitous part of its posterior surface, and in the form of a membrane which 
is described in the apparatus of vision as the retina. Before traversing the 
bottom of the eye, this nerve always becomes markedly constricted. ; 

The study of the structure of the optic nerve reveals some peculiar 
facts which it is well to know, though they are more curious than in- 
teresting. The upper part is entirely destitute of envelope, while: the 
inferior—that in front of the chiasma—has a double neurilemma. The 
external layer of this is only a dependency of the dura mater: a kind of 
fibrous sheath attached at one end to the margin of the optic foramen, and 
at the other to the sclerotica. The internal, which is analogous to the 
neurilemma of the other nerves, emanates from the pia mater, and presents 
a multitude of septa (forming the lamina cribrosa), which keep the fibres of 
this nerve apart from each other. To make this organisation manifest, the 
latter should be steeped in an alkaline solution for some days, and then washed 
in a stream of water to remove the softened nervous matter; the nerve is 
to be afterwards tied at one ot its extremities, inflated, tied at the opposite end, 
and dried. By means of some sections all the cunals that lodge the fasciculi 

of nervous tubules, and which 
are formed by the internal 
neurilemma, are then shown. 
Concerning the properties of 
the optic nerve, we will say 
nothing ; though they are analo- 
gous to those of the other nerves 
of special sense; it is destined 
to transmit to the encephalon 
the impressions furnished by 
the sense of sight, and mechani- 
w cal irritation of it does not cause 
pain. 


Fig. 335. 


3. Third Pair, or Common Oculo- 
motor Nerves. (Figs. 326, 335.) 


The nerves of the third pair 
emanate from the cerebral pe- 
duncles, near the interpedun- 
cular fissure, and at an almost 
equal distance between the 
corpus albicans and the pons 

SERIES OF mt deen Varolii. Their roots, seven or 

1, Ophthalmic branch of the fifth pair; 2, Palpebro- @lght in each, penetrate the 
nasal branch ; 3, Lachrymal nerve; 3’, Temporal texture of these peduncles, pass 
branch of that nerve, 4, Frontal nerve, 5, Ex- backwards, and may be traced 


ternal oculo-motor nerve, 6, Trochlear nerve to their nucleus, which Stillin 
8, 9, 10, 11, Branches of the common oculo-moter u 8 & 


nerve; 12, Superior maxillary nerve; 13, Its has placed above the anterior 
otbital branches: border of the pons Varolii, and 


; which is united to that of the 
opposite side by fibres intercrossing on the median line. 


From the union of these roots results a flattened trunk, which is at first 
carried outward, and is almost immediately inflected forward to enter, along 


THE CRANIAL OR ENCEPHALIC NERVES. 709 


with the sixth pair and the ophthalmic branch of the trigeminal nerve, into the 
smallest of the great suprasphenoidal foramina. The common oculo-motor 
nerve afterwards arrives, by the orbital hiatus, at the bottom of the ocular 
sheath, where it separates into several branches destined to the following 
muscles of the eye: the elevator of the upper eyelid, superior rectus 
internal rectus, inferior rectus, posterior rectus—except its internal fasciculus 
—and the small oblique. The branch to the latter is remarkable for its great 
length ; it reaches its destination in passing to the outside of, and then below 
the inferior rectus. The motor roots of the ophthalmic ganglion furnished 
by this nerve, are given off from the same point as the branch for the small 
oblique muscle. ‘ 

The nerves of the third pair are purely motor, as is shown by their 
connections with the inferior plane of the cerebral peduncles, and their 
exclusive distribution to contractile organs. They incite all the muscles 
lodged in the ocular sheath, except the external rectus, the great oblique, 
and posterior rectus. 

_ Cit also sends a motor filament to the lenticular ganglion, supplies the 
circular muscular fibres of the iris and ciliary muscle, and presides over 
contraction of the pupil.) 


4, Fourth Patr, or Pathetici. (Fig. 835, 6.) 


The pathetic or internal cculo-motor (or trochlearis) nerve is the smallest 
of all the cranial nerves. Its description is extremely simple. It arises 
from the band of Reil, immediately behind the corpora quadrigemina, by 
two short roots, which it has been impossible for me to follow very deeply 
in the substance of the isthmus. 

It is directed outwards, downwards, and forwards, to disengage itself 
from the deep position it at first occupies, and lies beside the superior 
branch of the trigemini, accompanying it to the suprasphenoidal foramina, 
the smallest of which it enters. This opening is exclusively intended for 
it, and carries it to the bottom of the ocular sheath, when it gains the deep 
face of the great oblique muscle, in which it ramifies, supplying that organ 
with the stimulant principle of muscular contractility. 

The physiological study of this nerve gives rise to some very interesting 
remarks, which we will sum up here in a few words. The two oblique 
muscles of the eye pivot the ocular globe in the orbit, without causing the 
slightest deviation either upwards, downwards, or otherwise, of the pupillary 
opening. But this rotatory movement is altogether involuntary, and is only 
accomplished in certain determinate conditions. “ Guerin, Szokalski, 
Hueck, and Hélie have remarked, that when the head is alternately inclined 
to the right or left, while the vision is fixed on any object, the ocular globes 
describe around their antero-posterior axis an inverse rotatory movement 
that has the effect of preserving a constant relationship between the object 
from which the luminous rays proceed and the two retin. In this 
rotatory motion the great oblique muscle of one side has for its congener 
the small oblique of the other side: thus, when the head is inclined on the 
right shoulder, the right eye revolves inwards and downwards on its axis, 
under the influence of the superior oblique muscle, while the left eye turns 
on itself outwards and downwards, through the action of the inferior 
oblique ; when the head is inclined on the left shoulder, an inverse move- 
ment takes place in the two eyes. ‘This simultaneous rotation of the ocular 


globes around their antero-posterior diameter, when the head is inclined to 
48 


710 THE NERVES. 


one side or the other, is necessary for the unity of perception of visual 
objects; if one of the two eyes remained fixed while the other turned on its 
axis, we would perceive two images, a superior corresponding to the healthy 
eye, and an inferior to the diseased one. These two images are visible 
when the head is vertical, and particularly when it is inclined to the affected 
side, they are confounded into a single one when the head is carried to 
the healthy side.” + 

The involuntary action of the oblique «muscles of the eye in this rotatory 
movement strongly attracts atttention to the nerves which these muscles 
receive, and stimulates a desire to learn the particular conditions which 
permit them to act as excito-motors independently of the will; although they 
as well as the muscles to which they are destined, belong to those of animal 
life. In the present state of science, nothing positive can be affirmed on go 
delicate a subject. There are, nevertheless, two interesting remarks to 
make the pathetic nerve is exclusively destined to the superior oblique 
muscle, and the long branch sent by the common oculo-motor nerve. to the 
inferior oblique does not give any filament to the neighbouring parts. This 
branch is, therefore, also the eaclusive nerve of the inferior oblique, and may 
be considered as a second pathetic. 

(Sir Charles Bell designated the fourth nerve the “respiratory nerve of 
the eye,” and asserted that it was large in all animals capable of much 
expression.) 


5. Fifth Pair, or Trigeminii. (Figs. 110, 322, 335, 336, 337, 338, 342.) 


The nerve we are about to describe has also been named by Chaussier 
the trifacial nerve. It is distinguished among all the cranial nerves by its 
enormous volume, the multiplicity of its branches, the variety of its uses, 
and its connections with the great sympathetic system. It therefore 
requires to be described as completely as possible; and in this description 
we will include the study of the cephalic ganglia of the great sympathetic 
system, which ought to be regarded as annexes of the fifth pair. 

Origin.—The trigeminus belongs to the category of mixed nerves, as it 
possesses two roots—one sensitive, the other motor. 

Sensitive Root (Figs. 337, 338, 1).—This is the largest root. It emanates 
trom the outside of the pons Varolii, near the middle cerebellar peduncle, 
and is directed forward and dvwnward to gain the anterior portion of the 
foramen lacerum, where it terminates in a very great semilunar enlargement 
constituting the Gasserian ganjlion. Flattened from above to below, and 
wider in front than behind, this root on the outer side is about 6-10ths of 
an inch in length, but the inner side is double that measurement because of 
the oblique position of the ganglion which continues it. 

If it be traced into the substance of the pons, it will be found that the 
fibres of the latter separate for its passage from the deep plane it at first 
occupies, The following is the manner in which it comports itself in this 
plane :—This root is separated into two orders of fibres, posterior and 
anterior. The first pass beneath the arciform fasciculi of the pons Varolii, 
to be continued with the restiform body, and consequently with the pos- 
terior columns of the spinal cord ; the second separate from each other, and 
soon become confounded with the cells amassed in the interior of the 
isthmus, at the anterior cerebellar peduncles, and above the intermediate 

: fasciculus.of the medulla oblongata. The fibres of the trigeminus, or the cells 


' Sappey. ‘ Anatomie Descriptive.’ 


THE CRANIAL OR ENCEPHALIC NERVES. 711 


which receive these fibres, are in communication with several cranial nerves, 
particularly the pneumogastric, glosso-pharyngeal, facial, and auditory. 

Semilunar or Gasserian ganglion—This ganglion, which receives the 
Sensitive root of the trigeminus, is crescent shaped, its concavity bein 
turned backwards and inwards. It may be said to be imbedded in the 
fibro-cartilaginous substance which in part closes the occipito-spheno- 
temporal hiatus, and divides it into several particular foramina, Its 
superior face is covered by the dura mater, and sends a number of filaments 
to that membrane. 

: The Gasserian ganglion is not continued by a single trunk, but imme- 
diately gives rise to two thick branches, one of which leaves the cranium 
by the foramen ovale—an opening formed by the above-named hiatus ; 
while the other is lodged in the external fissure in the intercranial face of 
the sphenoid bone, and passing along it as far as the entrance to the supra- 
sphenoidal foramina, bifurcates, 

Hence it results that the trigeminus is divided, even at its origin, into 
three branches: two superior—the ophthalmic branch of Willis, and the 
superior maxillary nerve, commencing by the same trunk; and an inferior, 
which constitutes the inferior maxillary nerve. 

Motor or small root (Figs. 337, 338)—This is a flattened band which 
emerges from the pons Varolii, at the inner side of the principal root. Its 
fibres may be easily followed to the interior of the pons Varolii, and in their 
direction they comport themselves like those of the large root, by becoming 
confounded with the substance of the antero-lateral fasciculus of the 
medulla oblongata. Leaving the pons, this root passes forwards on the 
inferior face of the Gasserian ganglion, which it crosses in a diagonal 
manner outwards, and beyond which it intimately unites with the fibres 
of the inferior maxillary nerve. The superior maxillary nerve and the 
ophthalmic branch do not receive any fibres from it. In the fifth pair, then, 
it is only the inferior maxillary nerves which are at the same time sensitive 
and motor, and are real mixed nerves. 

A. Oparuatmic Branon (Fig. 335, 1)—This is the smallest of the 
three divisions furnished by the Gasserian ganglion, and proceeds by a 
trunk common to it and the maxillary nerve, which will be described here- 
after. This branch enters the smallest of the large suprasphenoidal 
foramina, along with the common and external oculo-motor nerves, and 
in the interior of this bony canal divides into three ramuscules, which reach 
the bottom of the ocular sheath by the orbital hiatus. 

These ramuscules are : 


1. The frontal or supra-orbital (supratrochlear) nerve. 
2. The lachrymal nerve. 
3. The nasal or palpebro-nasal nerve. 


1, Fronrat Nerve (Fig. 335, 4).—This is a flat, voluminous branch 
placed on the inner wall of the ocular sheath, and proceeding nearly parallel 
with the great oblique muscle of the eye to the supra-orbital foramen, into 
which it passes along with the artery of the same name. Undivided before 
its entrance into this orifice, immediately after its exit from it, it separates 
into several ramuscules, which meet the anterior auricular nerve, and are 
expended in the skin of the forehead and upper eyelid. 

_ 2. Lacarymat Nerve (Fig. 335, 3).—This is composed of several 
filaments, which ascend between the ocular sheath and the elevator muscles 
of the eyelid and superior rectus, to enter the lachrymal gland. One of 


712 THE NERVES. 


these (Fig. 335, 3') traverses the ocular sheath behind the orbital process, 
and places itself, from before to behind, on the external surface of the Zygo- 
matic process, where it divides into a number of ramuscules, some of which 
mix with those of the anterior auricular nerve to form the plexus of that 
name, while the others pass directly into the anterior muscles and integu- 
ments of the ear. 

Panpepro-nasaL Nerve (Fig. 335, 2).—This describes a curve, like 
the ophthalmic artery, and passes with that vessel into the cranium by the 
orbital foramen. After coursing through the ethmoidal fissure that lodges 
the artery, it traverses the cribriform plate, and divides into two filaments—an 
internal and external, which ramify in the pituitary membrane on both sides 
of the nasal fossa. Before entering the orbital foramen, this nerve gives 
off a long branch (infratrochlear) that glides over the floor of the orbit to 
reach the nasal angle of the eye, where it is distributed to the lachrymal 
apparatus lodged there, as well as to the lower eyelid; it also detaches a 
long filament to the membrana nictitans and the sensitive roots of the 
ophthalmic ganglion, which will be noticed hereafter. 

B. Surrrtor Maxittary Nerve (Fig. 336, 15)—This nerve is the 
real continuation of the superior trunk given off by the Gasserian ganglion, 
where we will begin to follow it to its termination, examining briefly 
the ophthalmic branch already described as a collateral division of this 
trunk. 

Remarkable for its volume, and its prismatic and funicular shape, the 
superior maxillary nerve proceeds from the inner and upper section of the 
semilunar ganglion, and at first occupies the fissure on the internal face 
of the sphenoid bone, without the cavernous sinus, and is covered at this 
point by the dura mater. After sending the-ophthalmic branch into the 
smallest of the great suprasphenoidal conduits—the great sphenoidal fissure, 
it enters the most spacious of these openings—the foramen rotundum, arrives 
in the orbital hiatus beneath the sheath of the eye, and, with the internal 
maxillary artery, passes along the space filled with fat which separates that 
hiatus from the origin of the supramaxillo-dental (infra-orbital) canal, 
which it follows to its external orifice on the face. There it terminates 
in a number of branches named the infra-orbital ramuscules (or pes anserinus, 
from their resemblance to the claws of a goose’s foot). 

In its course, this nerve gives off a large number of collateral divisions, 
among which may be more particularly distinguished : 

1. An orbital branch. 

2. The great or anterior palatine nerve. 

3. The staphylin or posterior palatine nerve. 

4. The nasal or spheno-palatine nerve. 

5. The dental nerves. 

In addition to which are described : 

6. The infra-orbital, or terminal branches of the superior maxillary 
nerve. 

1. Orzrran Branow (Fig. 335, 13)—This ramuscule arises in the inte- 
rior of the suprasphenoidal canal, and enters the ocular sheath with 
the divisions of the ophthalmic branch. It almost immediately breaks up 
into two or three very slender filaments, which ascend to the temporal angle 
of the eye, passing between the fibrous lining of the orbit and the outer 
surface of the motor muscles of the eye, and are distributed to the eyelids 
and neighbouring integuments. 

2. Great orn Anterior Patatine Nerve (Fig. 148, 8)—It arises 


THE CRANIAL OR ENCEPHALIC NERVES, 713 


from the superior maxillary nerve at the orbital hiatus, from a trunk common 
to it and the nasal and staphylin branches; it passes into the palatine canal 
with the palato-labial artery, which it follows to the foramen incisivum, 
where it stops. 

During its course in the palatine canal, this nerve throws off two or three 
small filaments, which escape by particular foramina to the anterior part of 
the soft palate—median palatine nerve, Frequently they arise from a common 
trunk before the great palatine nerve enters its canal, and pass to their 
destination by particular openings. For the remainder of its extent on the 
roof of the palate, this nerve forms, around the artery it accompanies, a 
plexiform network similar to that of the ganglionic nerves; the filaments 
escaping laterally from it are sent to the soft parts of the palate, as well as 
to the gums. 

3. — or Posrerion Patatins Nerve (Fig. 148, 8).—The 
filaments composing this nerve are very easily separated, and frequently 
anastomose with those of the preceding nerve. They accompany the 
palatine artery in the canal of that name, bend in front of the pterygoid 
process to penetrate the soft palate between the glandular layer and the 
tunica albuginea. They then become inflected backwards, and ramify 
either in the mucous and glandular tissues of the velum pendulum, or the 
palato-pharyngeal and circumflexus-palati muscles. This destination, 
therefore, indicates in this nerve the presence of motor fibres; we will see 
hereafter whence they come. . 

4. Nasau or Spueno-paratinn Nervs.—Springing from the same 
trunk as the two preceding nerves, thicker than the staphylin, and nearly of 
the same volume as the anterior palatine, the nasal nerve passes with its 
artery into the nasal or spheno-palatine foramen, to penetrate the cavity 
of the nose, where it separates into two een and internal, 

ich are distributed to the pituitary membrane. 
~ Dinan Beenanna, lees a destined to the roots of the upper 
teeth, and proceed from the superior maxillary nerve during its ne 
maxillary course; some even arise before the entrance of that nerve into the 
bony conduit, which it passes through to reach the face. These Mie. 
analogous to the posterior dental nerve of Man, enter the canal with qd e 
parent branch, and throw the'r divisions into the roots of the - ot ar 
tooth, and sometimes also into the second last. One portion - : a 
plunges directly into the maxillary protuberance, to be expended in ‘ e 
mucous membrane lining that protuberance, after furnishing some fila- 

um. . : 
ee ee el branches given off from the maxillary nerve ae 
its interosseous course, some pass to the molars, and others to the ere an 
incisor teeth. The first, or middle dental nerves, separate = cae oo 
the maxillary trunk on its passage above the roots of ie pee 3 
they penetrate these roots after hae fae oo and give 80 

ane linin e maxillary si y ; 

a ante at first a single branch—the anterior sid ais 
which rises from the maxillary trunk rie oo i cal eee a pees 
sahara Soe et cua ae sense for the canine 
nee mene nS ; it is always accompanied by a very slender arterial 
ile, x Superton Maxi- 
6. Inrra-oRBITAL oR TERMINAL ee ie ean 
tary Nerve.— These ramuscules spread on the s 


2 


714 THE NERVES. 


ficent expansion, which may be looked upon as one of the richest nervous 
apparatus in the animal economy. Covered at its emergence from the infra- 
orbital foramen by the supermaxillo-labialis muscle, this fasciculus descends 
beneath the supernasalis-labialis and pyramidal muscle of the nose (super- 
maxillo-nasalis magnus) towards the nostrils and upper lip, which receive 
the terminal extremities of its constituent branches in the substance of their 
muscular and tegumentary tissues ; these branches are slightly divergent and 
flexuous, and for the most part anastomose with a large motor trunk furnished 
the facial nerve (Figs. 836, 15’). ; ; 
i C. INFERIOR ean ete Nerve (Figs. 336, 11; 110, 12).—At its exit from 


Fig. 338. 


GENERAL VIEW OF THE SUPERIOR AND INFERIOR MAXILLARY NERVES. 


The eye has been excised, after sawing through and removing the orbital and 
zygomatic processes. The maxillary sinuses have been exposed by means of a 
gouge or chisel, the masseter muscle removed, and the inferior maxilla opened to 
show the nerve in its interosseous course. 

1, Facial nerve ; 2, Origin of the posterior auricular nerve; 3, Filament distributed 
to the stylo-hyoid muscle; 4, Digastric branch; 5, Trunk of the anterior auricular 
nerve; 6, Origin of the cervical filament; 7, Plexus formed by the union of the 
facial and superficial temporal nerve; 7’, Branch of that plexus umted to the 
infra-orbital nerves, 15’; 11, Inferior muvillary nerve; 8, Superficial temporal 
nerve; 9, Masseteric nerve; 10, Gustatory nerve; 12, 12, Dental branches; 13, 
Mylo-hyoid nerve; 14, Buccal nerve; 15, Superior mawxillury nerve; 16, Spheno- 
palatine ganglion; 17, Staphylin (or palatine) nerve; 18, Common carotid 
artery; 19, Trunk of the occipital; 20, Trunk of the internal carotid; 21, 
External carotid; 22, Trunk of the posterior auricular artery embraced by a 
loop of the facial; 23, Trunk of the superficial temporal; 24, Internal maxillary 
artery ; 25, Trunk of the deep anterior temporal artery; 26, Orbital branch of 
the superior dental; 27, Buccal artery ; 28, Inferior dental artery. 


the cranium, this branch is situated immediately within the temporo- 
maxillary articulation, and from thence is directed forward and downward, 
passing at first between the two pterygoid muscles, then between the inner 
and deep face of the maxilla, arriving at the maxillo-dental foramen, through 
which it passes and runs along the whole course of the canal, escaping at 
last by the mental foramen to form an expansion of terminal branches 


THE CRANIAL OR ENCEPHALIC NERVES. 715 


similar to those of the superior maxillary nerve, and named the mental 
nerves. 

For the first third of its extent, the inferior maxillary nerve is a flattened 
band ; but beyond this it becomes thicker, and acquires a funicular shape. 

At its origin it gives rise to four branches : 

1. The masseteric nerve. 

2. The buccal nerve. 

3. The nerve of the internal pterygoid muscle. 

4. The superficial temporal or subzygomatic nerve. 


After its emergence from between the two pterygoid muscles, it furnishes: 


5. The gustatory nerve. 
6. The mylo-hyoid nerve. 


In its intermaxillary course, it detaches: 
7. The dental branches. 


Also a triple series of collateral nerves which we will study before 
describing the terminal branches; these are : 


8. The mental nerves. 


The trunk of the inferior division of the fifth pair represents a mixed 
nerve, because it is formed of sensitive and motor fibres. Is it the same for 
each of the branches just enumerated ; that is, do they all contain fibres of 
the two orders? This is a question on which the dissection of the two 
roots has taught us very little, for their fibres soon become confounded so 
intimately that it has always been found impossible to follow them separately 
into each nerve. But the study of the distribution of these branches, corrobo- 
rated by physiological experiments, has greatly enlightened us in this 
inquiry. We see among them nerves destined to the muscles, and others 
to glandular or integumental structures; the first are therefore chiefly 
composed of motor fibres, like all other muscular nerves; and the second 
exclusively contain sensitive fibres, or at least are deprived of voluntary 
motor fibres. In describing each branch in particular we will notice 
their special properties. . ; 

1, Massrreric Nerve (Figs. 336, 9; 342, 2).—It is detached from the prin- 
cipal trunk, in front, though close to, the base of the cranium, bends round 
the anterior face of the temporo-maxillary articulation, and passes through 
the sigmoid notch of the inferior maxilla to descend into the texture of the 
masseter muscle and there ramify. : 

At its origin, this nerve furnishes two filaments which often proceed 
from one very short trunk, and ascend into and expend themselves in the 
‘temporal muscle; this trunk is then the deep posterior temporal nerve. 

Before crossing the corono-condyloid notch, it detaches to this same 
temporal muscle a small branch which represents the deep middle temporal 


nerve. ; 
The destination of all these branches sufficiently proves that they are 


ee Nerve (Figs. 336, 14; 342, 4).—This nerve, which is twice the 
size of the preceding, arises from the same point, though slightly below it. It 
is directed forwards, traverses the external pterygoid muscle, and reaches the 
posterior extremity of the superior great molar gland; leaving which, it is 
placed beneath the buccal mucous membrane, and descends to the commissure 
of the lips, along the inferior molar gland and the inferior border of the 


alveolo-labialis muscle. 


716 THE NERVES, 


It gives some very fine filaments to the external ptérygoid, in its passage 
across that muscle. Beyond this, it furnishes a very slender ramuscule to 
the orbital portion of the temporal muscle—the analogue of the anterior deep 
temporal of Man. . : ; ; 

On the superior molar gland, it emits a fasciculus of branches to this 
organ and the alveolo-labialis muscle. In its submucous track it throws 
off, at certain distances, ramuscules of various sizes which go to the 
inferior molar gland and the buccal membrane ; while its terminal filaments 
are expended in the lining membrane and glands of the lips, near the 
commissure. 

The majority of the filaments given off by this nerve to the external 
pterygoid and temporal muscles are doubtless motor, but the other ramus- 
cules are sensitive; even those distributed to the alveolo-labialis muscle 
are no exception, for its submasseteric portion is supplied by the facial, as 
well as the superficial or anterior part. 

3. Internat Prerycor Nerve.—It forms, with the preceding nerves, 
a single fasciculus, which leaves the anterior part of the inferior maxillary 
nerve. After crossing, outwardly, the internal maxillary artery, it descends 
between the nervous trunk from which it emanated, and the external layer 
of the tensor palati muscle, to go to the inner side of, and become expended 
in, the internal pterygoid muscle. 

This nerve is the smallest branch of the inferior maxillary trunk, after 
the mylo-hyoid, and excites the contraction of the muscle receiving it. 

4, SuperricraL Temporat or Supzyeomaric Nerve (Figs. 336, 8 ; 342, 3), 
—This arises from the inferior maxillary nerve, at the opposite side of the 
fasciculus formed by the three preceding branches, or posteriorly. Placed at 
first at the inner side of the temporo-maxillary articulation, and between it 
and the guttural pouch, it is afterwards directed downwards and outwards, 
passes between the parotid gland and the posterior border of the inferior 
maxilla, and below the condyle; it then bends round the neck of that bony 
eminence to arrive beneath, and to the outside of, the precited articulation, 
where it terminates by anastomosing with the facial nerve. 

In its course it sends off numerous fine filaments to the guttural pouch, 
the parotid gland, and the integuments of the temporal region. Among 
the latter, it is necessary to notice more particularly those which accompany 
the superficial temporal artery. 

The superficial temporal nerve appears to be exclusively sensitive. 
Section of it, before it anastomoses with the facial nerve, does not really 
prevent contraction of the muscles which receive the divisions of the plexus 
formed by this anastomosis. 

5. Gustatory Nerve! (Figs. 111, 17; 336. 10; 342,5).—The gustatory - 
nerve, the principal branch of the inferior maxillary trunk, which it almost 
equals in volume, is detached at an acute angle from the anterior border of that 
nerve shortly after its exit from the pterygoid muscles. To accomplish its 
course, which it effects in describing a slight curve whose concavity is antero- 
posterior, it is directed forwards and downwards, passing between the 
internal pterygoid muscle and the branch of the inferior maxillary bone, 
and gaining the base of the tongue, where it is situated beneath the 
buccal mucous membrane. It afterwards descends more deeply, between 
the mylo-hyoid and hyo-glossus longus muscles, turns round the inferior 

' (Professor Chauveau designates this the lingual, or small hypoglossal nerve. To 


etal confusion I have, in preference, retained the usual designation given to it in this 
country.) 


THE CRANIAL OR ENCEPHALIC NERVES. 17 


border of the latter—including also Wharton’s duct, to enter the inter- 
stice separating the genio-glossus from the hyo-glossus longus and brevis 
muscles. From this point it continues to near the free extremity of the 
tongue, proceeding in a very flexuous manner, and giving off, on its course, 
divisions equally tortuous and which traverse the organ, but without 
detaching any ramuscules to the lingual muscles; these divisions terminate 
in the middle and anterior portions of the lingual mucous membrane. 

Before penetrating the mass of the tongue, this nerve furnishes: 1, At, 
and in front of, the posterior pillars of that organ, some small ramuscules 
which are sometimes plexiform, and are distributed to the mucous 
membrane at the base of the tongue; 2, Lower, and behind, one or two 
thin filaments which are carried to Wharton’s duct, and ascend with it 
to the maxillary gland; 3, A sublingual branch, whose divisions enter the 
gland of that name, as well as the mucous membrane covering the sides of 
the tongue. 

The gustatory nerve receives, near its origin, the tympano-lingual filament 
or chorda tympani—a branch of the facial nerve soon to be described. Its 
terminal divisions mix and anastomose with those of the great hypoglossal 
nerve, in the deep muscular interstice which lodges both. - 

Physiology teaches us that the gustatory nerve gives to the anterior 
two-thirds of the lingual mucous membrane ordinary sensation, and, in 
addition, that special sensibility (or gustatory power) by virtue of which 
that membrane enjoys the property of appreciating savours. This is its 
exclusive function. With regard to the tympanic filament from the facial 
nerve, and which is joined to the gustatory, M. Bernard is of opinion that it 
participates in the cxercise of this sense of taste. Its radiating fibres extend 
to the submucous muscular layer of which we have spoken, and on which 
the lingual papille rest, and endow it with the property of acting on these 
papille by adapting them, we may say, to the sapid substances brought into 
contact with them. Lussana goes further than this, and, basing his state- 
ment on observations made on Man and on experiments, asserts that the 
nerve of the tympanum passes to the mucous membrane, and endows it with 
the sense of taste. Vulpian, however, does not agree to either of these 
opinions, because, according to his experience, this nerve does not go to the 
tongue, but stops at the submaxillary ganglion. 

6. Myzo-nyow Nerve (Fig. 336, 13).—The designation of this nerve 
indicates its destination and uses. It goes to the mnscle bearing its name, 
and excites its contractility; it arises opposite to the preceding, and, like 
it, descends between the internal pterygoid muscle and the inferior max- 
illary bone, adhering somewhat closely to the latter. But arriving at the 
posterior border of the mylo-hyoideus, it passes to the outside of it, and 
meeting with the sublingual artery, ramifies on the external face of that 
muscle. 

7. Dentat Brancues (Fig. 336, 12).—These are of two orders: some 
passing to the molar, the others to the canine and incisor teeth. Their 
description does not merit any special indication. 

8 Mentat Nerves, on TERMINAL BRrancHEs OF THE TIyrertor MaxILLaRry 
Nerve.—Perfectly analogous to the infra-orbital ramuscules, these nerves 
form a fasciculus by diverging and flexuous branches, which leave the 
mental foramen to be distributed to the textures of the lower lip, after 
receiving a branch from the facial nerve (Fig. 336, 11’). 

D. Tus SymparHETic GANGLIA ANNEXED TO THE Firta Parr.—These 
ganglia, joined by filaments of communication to the anterior extremity 


718 THE NERVES. 


of the great sympathetic nerve, in reality belong to the special system 
formed by that nervous chain, as they possess the formation and properties 
of the other ganglia composing it. It is therefore necessary that we should 
have a motive sufficiently powerful to induce us to move them from their 
natural category, and mix up their description with a nerve so different to 
them in its nature and functions. This motive we find in the intimate 
relations of contiguity and continuity which these ganglia manifest towards 
the branches of the trigemini; in the fact that we sometimes find them united 
to these branches, and deeply mixed up with their fibres ; and also because, 
in certain cases, they seem to disappear entirely, and then their filaments 
of emission or reception are directly received or emitted by the fifth pair. 

The study we are about to undertake of each of the ganglia will fully 
justify what we have advanced. We will precede it by a few words of 
introduction as to the general facts relating to these small organs. 

The number of sympathetic ganglia annexed to the fifth pair is suscep- 
tible of variation, not only in different species, but also with individuals 
of the same species. 

In the domesticated mammifers, we somewhat constantly, though not in- 
variably, find three principal, placed on the course of the branches ema- 
nating from the Gasserian ganglion. Theseare: 1, The ophthalmic ganglion, 
belonging to the nerve of the same name; 2, The spheno-palatine ganglion, 
annexed to the superior maxillary branch; 3, The otic ganglion, which lies 
beside the inferior maxillary nerve. Anatomists describe other two, the 
submaxillary ganglion and the naso-palatine (or Cloquet’s) ganglion; but. 
their presence is not always constant in Solipeds, and their existence in the 
other domesticated animals is at least problematical. 

These small bodies possess those common characters which have been 
so clearly indicated by Longet, and to which we will briefly refer, All 
are in communication with the superior cervical ganglion by one or more 
generally very slender filaments, and all receive one or more ramuscules 
from a sensitive and a motor nerve: these ramuscules—the afferent branches 
of the ganglia—are considered as their roofs. All, finally, emit from their 
periphery a more or less considerable number of emergent branches or ramiji- 
cations which share the properties, more or less modified, of the two orders 
of roots. The description of each ganglion therefore includes, indepen- 
dently of its form, situation, etc., an indication of all these ramuscules: 
ramuscules of communication with the superior cervical ganglion; afferent 
ramuscules or roots ; and emergent ramuscules. This rule can be applied to 
all the ganglia, and renders their study perfectly methodical. 

1. Ornrgatmio (Crntary orn Lewricunar) Ganouion.—This ganglion 
is readily discovered, as it is always in contact with the common oculo- 
motor nerve, and united to it near the point where the branch passing to 
the inferior oblique muscle arises. It rarely exceeds the volume of a grain 
of millet, and is sometimes so minute that it would altogether escape ob- 
servation, did we not know exactly where to look for it. 

Its motor root is generally formed of two very short ramuscules coming 
from the third pair. Its sensitive root, much longer, proceeds from the 
palpebro-nasal nerve; it is usually through the medium of this root that 
the ophthalmic ganglion communicates with the superior cervical ganglion, 
by means of a thin filament it receives from the cavernous plexus. 

The emergent filaments leave the anterior part of the ganglion, and 
arrange themselves in a flexuous manner around the optic nerve to reach 
the sclerotica, bearing the name of ciliary nerves. Some emanate directly 


THE CRANIAL OR ENCEPHALIC NERVES. 719 


from the palpebro-nasal nerve, especially when the ganglion is rudim 
Their number is uncertain, though itis usually from 5 to 8. 

Reaching the sclerotica at the bottom of the eye, they traverse that 
membrane, and pass between its inner surface and choroid coat to the 
ciliary circle (or ligament), where each divides into two or three ra- 
muscules that anastomose with those of the adjacent ciliary nerves, and in 
this manner form a circular plexus. From the concavity of this nervous 
circle arises a series of plexuous divisions, which are spread over the iris, 
whose contractile property is submitted to their influence. 

2. _SPHENO-PALATINE, or Mecxet’s Ganetion.— The largest of the 
cephalic ganglia, nothing is more variable than the disposition of this small 
body. The following appears to be the most constant: in raising the 
superior maxillary nerve in its course across the space separating the 
orbital from the maxillary hiatus, we discover, lying on the upper border 
of the spheno-palatine nerve, a long, grey-coluured enlargement; this 
constitutes the ganglion we are about to describe. 

It is elongated and slender, irregularly fusiform, constricted at different 
points of its extent and dilated in others ; it is not attached to the spheno- 
palatine nerve by simple cellular adhesions or by some branches thrown 
from one cord to the other, but is intimately united to it by means of a 
most complicated intercrossing of fibres, in such a way that the spheno- 
palatine ganglion really forms part of the nerve of that name. 

Afferent branches.—It receives, posteriorly, the Vidian nerve, a com- 

- posite ramuscule which constitutes its motor root, and connects it with the 
superior cervical ganglion, This nerve will be described with the facial, 
as that trunk furnishes its principal portion. Its sensitive roots naturally 
come from the spheno-palatine nerve; they are as remarkable for their 
number as their volume, and also enter the posterior part of the ganglion. 

Emergent branches.—Four series of these are recognised: 

1. A very numerous series which is detached at a right angle from the 
superior border of the ganglion, and proceeds tuwards the ocular sheath. 
The majority appear to be lost in that fibrous membrane, but we have 
seen some pass through it, creep on the lower and inner wall of the orbit, 
and arrive at the margin of the orbital foramen. There they were manifestly 
united to the other filaments coming from the palpebro-nasal nerve, and 
formed a small plexus whose divisions seemed destined to the ophthalmic 
vessels, and even to some of the muscles of the eye, more especially the 
oblique ones. Among these divisions we have observed some which went 
to join the nerve of the membrana nictitans. = 

2. A second series proceeding from the opposite border, and establishing 
a union between the ganglion and the spheno-palatine nerve, or passing to the 
palatine nerves in a more or less complicated plexiform manner, to reinforce 
them. 

3. A group arising from the anterior extremity and immediately passing 
to the spheno-palatine nerve. : ; 

4, A last fasciculus detached from the posterior extremity to enter the 
two great suprasphenoidal canals. ; ; 

Such is the most usual arrangement of the spheno-palatine ganglion. 
We have found it divided into three small masses connected with each 
other by numerous filaments of a deep grey colour, and free from all ad- 
herences with the spheno-palatine nerve. The small posterior mass in this 
case received the Vidian nerve and the sensitive roots from the fifth pair. 
The distribution of the emergent branches was unaltered. 


entary, 


720 THE NERVES. 


Among the anatomo-physiological facts pertaining to. the study of thig 
ganglion, we may remark that the staphylin, or posterior palatine, nerve 
derives from it the motor property which permits it to excite the con- 
traction of the muscles in the soft palate. 

8. Oric (on ARNOLD'S) GANGLIon.—It appears to us that the presence 
of this ganglion is not constant, for we have sometimes found it replaced 
by a small plexus provided with some almost microscopic ganglionic 
granulations. ; 

When it does exist, it presents itself as a small fusiform enlargement 
placed within the origin of the inferior maxillary nerve, beneath the inser- 
tion of the Eustachian tube. To discover it, we have only to look for the 
commencement of the buccal nerve, to which it is joined by some filaments 
which are so short and thick, that we might imagine it to be fixed on that 
trunk. 

Its sensitive roots are represented by the preceding filaments. The small 
superficial petrous nerve, coming from the facial, constitutes its motor root. 
From the sympathetic ramuscule accompanying the internal maxillary 
artery, it receives its filament of communication with the superior cervical 
ganclion. 

Among its emergent ramuscules must be cited a superior filament, which 
enters the petrous portion of the temporal bone to disappear in the internal 
muscle of the malleus (tensor tympani), and two inferior filaments of a 
more considerable volume which separate in numerous ramuscules destined 
to the pterygoid muscles, the Eustachian tube, and the tensor palati 
muscle. 

PuysionocicaL Rusumé or THE Firra Patr.—The trigemini convey 
sensation to the skin covering the head, into the eyelids, the soft and hard 
palate, the nasal fosse and sinuses, the nostrils, the greater portion of the 
tongue, and into the salivary glands and cheeks, and the upper and lower lips. 
The enormous tuft formed by the terminal branches of the superior 
maxillary nerve, endow the upper lip with the attributes of an organ of very 
exquisite tact. 

The gustatory branch is, for the anterior two-thirds of the tongue, the 
essential instrument of the sense of taste. 

By its motor root, the inferior maxillary nerve provokes the contraction 
of the muscles that bring the jaws into apposition—all those composing the 
masseteric region, except the digastricus. This root is often designated, in 
consequence of its function, the masticatory nerve. 

The fifth pair also influences, as is demonstrated by vivisections and the 
observation of pathological facts, the secretion of the mucous membranes 
and glands receiving its filaments: undoubtedly by a reflex action which 
proceeds from the isthmus, and perhaps from the Gasserian ganglion. 

Finally, it is admitted that the nutrition of the tissues in which the 
trigeminus ramifies depends upon that nerve. But here there is an exagge- 
ration; for if nutrition be modified in these tissues, consequent on the 
section of the fifth pair, this effect is certainly due to paralysis of the 
capillaries, whose contractility is probably excited by the organic motor 
fibres mixed with the sensitive filaments of the fifth pair. 

The ramuscules sent by the sympathetic chain to the Gasserian ganglion, 
are perhaps not foreign to the part the fifth pair seems to play in the 
secretory and nutritive functions. 


THE CRANIAL OR ENCEPHALIC NERVES. 721 


6. Siath Pair (Abducentes), or External Oculo-motor Nerves. (Fig. 335, 5.) 


; The external oculo-motor originates from the medulla oblongata, imme- 
diately behind the pons Varolii, by from five to eight converging roots, 
which appear to issue from between the inferior corpus pyramidale and the 
lateral fasciculus of the medulla (Figs. 337, 338, h). 

It is directed immediately forward, leaves the pons Varolii in lying close 
to the inner side of the superior maxillary nerve, and traverses the sphe- 
noidal canal, which already lodges the ophthalmic branch of the fifth pair 
and the common oculo-motor nerve, to pierce the bottom of the orbit. It is 
entirely expended in the external rectus (or abductor) muscle of the eye, 


after giving off a small ramuscule to the external portion of the posterior 
rectus. 


7. Seventh Pair, or Facial Nerves. (Figs. 110, 336, 887, 888.) 


The facial (portio dura) is a nerve exclusively motor at its orgin, but 
which becomes mixed, during its course, by the addition of several sensitive 
branches. 

Origin.—It emanates from the medulla oblongata, immediately behind 
the pons Varolii, and appears to originate at the external extremity of the 
transverse band that margins the posterior border of that protuberance. 
But if we attempt to trace its origin in the substance of the medulla 
oblongata, we see the single fasciculus it constitutes, at its point of 
emergence, descend into the groove of separation between the pons Varolii 
and the above-mentioned band ; it then traverses nearly the whole thickness 
of the medulla, passing between the lateral cord or column, and that portion 
of the restiform body which is continuous with the large root of the fifth 
pair. Arrived near the bottom of the fourth ventricle, the facial nerve 
separates into several roots—some 
anterior, others posterior—which Fig, 337. 
are soon lost in the cells forming Sup Ped of Corebells 
the corresponding nucleus. Among EX 
these fibres are some which remain 
isolated from the preceding, and, 
passing the median line, enter the 
facial nucleus of the opposite side %¢Ze\\ 
(Fig. 337). 

Course.—Scarcely has _ the 
facial nerve left the medulla 
oblongata, before it is directed SECTION MADE THROUGH THE SUMMIT OF THE 
outwards, to pass into the internal = yepurna OvLONGATA, SHOWING THE DEEP 
auditory meatus, along with the ORIGINS OF THE FIFTH AND SIXTH NERVES, 
auditory nerve, which lies in con- AND PORTIO DURA OF THE SEVENTH, 
tact with it behind. It afterwards ; sata 
enters the aqueduct of Fallopius, courses along it, and follows its inflexions, 
which results in its forming a bend forward at a short distance from the 
internal opening of the canal, and a curve whose concavity is anterior, on 
its passage behind the cavity of the tympanum. On leaving the aqueductus 
Fallopii by the stylo-mastoid foramen, it 18 hidden beneath the deep face 
of the parotid gland, and continues to be inflected forward, passing between 
that gland and the guttural pouch, and reaches the posterior border of the 
inferior maxilla, where it issues from beneath the anterior margin of the 
parotid to become superficial, and place itself on the masseter muscle, 

' 


ed 
Grey nucleus 


of Trapex” 


792 THE NERVES. 


immediately beneath the temporo-maxillary articulation. There it ter- 
minates in two or three branches, which anastomose with those of the super- 
ficial temporal nerve from the fifth pair, thus forming the subzygomatic 
plecus (pes anserinus, Fig. 110). ; 
Disiribution.—a. In its interosseous course, the facial nerve successively 
furnishes : 
1. The great superficial petrous nerve (nervus petrosus superficialis major ). 
2. The small superficial petrous nerve (nervus petrosus superficialis minor). 
3. The filament of the stapedius muscle (tympanic branch). 
4. The chorda tympani. 


Té communicates, besides, with the pneumogastric nerve, by means of a 
voluminous filament described as : 


5. The anastomotic branch of the pnewmogasiric. 


b. The branches it emits on its course beneath the parotid gland arise 
either from its superior or inferior border ; they are: 


6. The oceipito-styloid nerve. 
7. The stylo-hyoid nerve. 
8. The digastric nerve. 
9. The errvical ramuscule. 
10. Filaments to the guttural pouch and parotid gland. 
The superior branches comprise : 
11. The posterior auricular nerve. 
12. The middle auricular nerve. 
18. The anterior auricular nerve. 


c. To this collection of collateral ramuscules are added the terminal 
branches, formed by their anastomoses with the superficial temporal nerve : 


14. The subzygomatic plexus. 


A. CotnateraL Brancues.—1l. Great Surerrician Petrovs Nerve. 
This is a very remarkable ramuscule, which is detached from the bend of 
the facial nerve to proceed to Meckel’s ganglion. The importance of the 
peculiarities attaching to the study of this nerve requires us to call special 
attention to its origin, course, and termination; though the details into 
which we are about to enter may be omitted by the student. 

Origin.— Ganglion geniculare.—The manner in which the great super- 
ficial petrous nerve comports itself at its origin is yet an obscure and 
controverted fact, on which however light is beginning to be thrown. The 
following is the most general opinion: This nerve arises from a small grey 
enlargement, the genicular ganglion (or intumescentia gangliformis), placed 
on the course of the facial nerve, at the summit of the angle which that 
nervous trunk describes after its entrance into the aqueduct of Fallopius; and 
the presence of this small ganglion on the seventh pair should assimilate the 
facial to a mixed nerve, whose sensitive root would be represented by the 
portio intermedia of Wrisberg—a thin filament comprised between the seventh 
and eighth pair, and which emanates directly from the medulla oblongata to 
pass into the posterior part of the ganglion geniculare. 

We have constantly found this ganglion in the domesticated animals. 
There exists, in fact, on this angle or elbow of the facial nerve, a very slight, 
grey, conical prominence, composed of ganglionic corpuscles which a micro- 
scopical examination readily reveals, and giving origin on its apex to the 
great superficial petrous nerve, This prominence, which, we repeat, is very 


TH. 
E CRANIAL OR ENCEPHALIC NERVES. 
f 723 


‘ 


small, for 
Eaten a a oes on ein 2 al 
base iat & & e have never seen the sh it only presents a ki 
at is feured in the majori the sharp and precise limitati ind of 
On the other hand a of iconographies of h é limitation of its 
acidulated by nitric , when, on portions steeped for uman anatomy. 
natvonls Meee eu acid, we have studied the several weeks in water 
For earls ss es its origin, we have found Pca er of the great 
bane aR eri —one internal, the other ext ormed of two fasciculi 
e geniculated ; ernal: the latt : 
nerve from before to behi ganglion; the oth er alone is 
the origin of the lens an , then it is suddenly Enfleotad lett sie 
ne aire ace eae ; mix with its fibres : ed Inwards to asc 
ine oe epee tae to the creduits en fasciculus cen he 
that of the prinaigal ey then appear as ata, into which its fibr 
principal ner us a small particul : a 
The great ve, and comprised heular trunk besid 
petrous nerve do prised between it and th states 
ganglion geniculare, ai es not, therefore, proceed ee 
L: er , 28 considerabl ore, proceed exclusively fr 
agape agen megan op pe tae 
: xternal fascicul : e facial : 
the acid shows ve asciculus, the separati i nerve. With 
ry plainly that th on of its fibres by th i 
almmostvexclusivel ly that the grey subst y the action of 
; their track: : ance of the ganglion i 
the precedin y on their track ; and if we tr ganglion is found 
r g fasciculus, int e trace these fibres, li 
that, instead of » Into the substance of the faci 8, like those of 
ae proceeding towards i OF EAS facial nerve, we will 
es its nee a ea rds its origin, they appear to be ai me 
explained by adimitfiae dhut th e circumstance, which we believ eee 
preumogastri they come from the anast i ae 
Ha this tm Ge we will speak ee Danaea 
fi ga it results th ° 
ge eee 2 Serer ‘though BES ee teh pee Bony Anists 
ie otor; the internal ed, roots: the internal 
sensitive root ; é al possesses the ganglioni Wy 
irom ; and the trunk they both form oe te peg of a 
As will be ob u eee 
Pecan € 0 served, our view of the gangli F 
hee sty t ee with regard to it nen peniculve Chey Bom 
xclusively to the great pet : as we make it bel 
fasciculi. On th ¢ petrous nerve, and not to th sade | 
sclcuil. e other hand, the portio i epee whole of the facial 
opin on, the sensitive root te abe oe of Wrisberg is not, in our 
mp or} bi demnut oven thakof tine wees ee sie : res we only look upon as 
ihe i at the ee be considered as only ee ace ines cgi eee 
auniiwonla te. extremely att ament. In the Hors 
tinguished at its origi y attenuated, and can scarcely, if ‘Ne 
: rigin from the filaments of peas 0 all be dae 
nerve; it is seen to enter th s of the lateral root of the audi 
1 e aqueduct of i si nape 4 
oF _gangliform enlargement) af ie eed ae sey onan Ne 
iminishing filaments, which are confounded ith. a eae) Sey 
0 What the ganglion geniculare with the proper fibres of this 
What a difference t 1 : 
Be Mee haie a ce there is between this arrangement and that of th 
hesit L roots opposite the ganglia placed on thei ue 
sitate to admit that this nerve of Wrisberg a on ee track | Why 
poms from the auditory nerve to the facial? Is I, be seagrass 
ifference in the properties of the two nerves? N : ecause of the radical 
closely together, does not appear to have taken i te oe fea hens Be 
and the reason for this anastomosis might be veer oe vale itorences 
the seventh pair maintains with the active poranavor th ee 
. Is it not the facial nerve that animates the stapedi = ae, 
ce manner, that of the malleus? Are all the canes of. ee rice nt mete 
not under its influence? In the present oe 
present state of science it would be difficult 


724 THE NERVES, 


to discover the functional relationship that may exist between the con- 
nections of the ear with the facial, and those of the latter nerve with the 
auditory: but the mind perceives this relationship, and that ought to suffice. 

The opinion which regards the nerve of Wrisberg as the sensitive root 
of the facial has, we believe, been more particulary accredited by the appa- 
rent impossibility of otherwise accounting for the sensibility this nerve 
possesses, even at its exit from the stylo-mastoid foramen—that is, before 
contracting any anastomosis with the fifth pair; but this sensibility belongs 
exclusively to the fibres of the communicating branch sent by the pneumo- 
gastric nerve, and not to the fasciculi of the facial, as is proved by stimu- 
lating the latter outside the aqueduct of Fallopius, after destroying the 
pneumogastric at its origin. If it is sought to regard the intermediate 
nerve absolutely as a branch distinct from the original filaments of the 
auditory, and if it be determined to make it a sensitive nerve, then it must 
at least be admitted that it does not carry its sensibility beyond the stylo- 
mastoid foramen, and that all its filaments disappear in the ramuscules 
furnished by the facial in its interosseous course. Otherwise, it is known 
that M. Longet considers this nerve as forming the small superficial petrous 
branch and the nervous filament of the stapedius muscle; but he makes it a 
motor branch destined to supply the muscles of the middle ear. His idea is 
very ingenious, and would assuredly be feasible if it were possible to follow 
the intermediate nerve from its origin to the lateral column of the medulla 
oblongata ; but, unfortunately, this is not the case, as the small ramuscule 
only appears to be an offshoot of the fibres proper to the auditory nerve. 

To sum up, the great superficial petrous nerve proceeds from the facial 
by two roots: one motor, the other sensitive, assimilable, to a certain point, 
to the roots of the spinal nerves. The first is furnished by the filaments of 
the seventh pair; while the second probably comes from the pneumogastric 
nerve, and has annexed to it on its course the ganglion geniculare. The nerve 
of Wrisberg perhaps concurs in the formation of this ganglion, but it is 
certainly not its principal source. 

Course and Termination.—The great petrous nerve, after being detached 
from the facial, and forming with it an obtuse angle opening outwards, 
enters the hiatus (or aqueduct) of Fallopius—a small passage running from 
behind forward, in the substance of the petrous bone, above the fenestra, 
rotunda, and cochlea. Arriving at the interior of the cavernous sinus, 
which it traverses, immersed in the blood that sinus contains, it receives a 
branch from the ganglionic plexus there, is lodged in the Videan fissure, then 
in the Videan canal, and in this manner gains the orbital hiatus, where it 
separates into several branches—most frequently two—which join the 
posterior part of Meckel’s ganglion. It constitutes the motor root and 
sympathetic filament of that ganglion. 

2. Smatt Surerricran Petrovs Nervr.—A very thin filament detached 
from the facial to the outside of the preceding, and likewise traversing the 
petrous bone from behind to before to enter the otic ganglion, whose motor 
root it is. 

3. Finament or tHe Srarepius Muscrn (Tympantc).— The facial 
nerve, in its passage above and in front of the stapedius muscle, closely 
adheres to it, and gives it one, perhaps several, extremely short filaments. 

4. Cuorpa Tympant (Fig. 342, 6).—This filament, also named the 
tympano-lingual nerve, arises at a very obtuse angle from the facial, near the 
external orifice of the aqueductus Fallopii. It penetrates the cavity of the 
tympanum by a particular opening, courses from its posterior to its 


THE CRANIAL OR ENCEPHALIC NERVES. 725 


anterior wall in describing a curve downwards, and passes among the 
chain of auditory bones, between the handle of the malleus and long branch 
of the incus. Escaping from the middle ear by a canal (fissura Glaser’) on the 
limits of the mastoid and petrous portions of the temporal bone, it proceeds 
forwards and downwards, and finally joins the gustatory nerve aftet a short 
course beneath the external pterygoid muscle, outside the guttural pouch. 


5. ANnasTomosixe Brancw or tux Pnevumoaasrnic Nerve.— (See the 
description of the tenth pair.) 


6. Occrprro-StyLoip Nerve. (Fig. 336, 3.) 

7. Styio-Hyoriw Nerve. 

8. Dicasrric Nerve (Fig. 336, 4).— These three spring from a 

common fasciculus at the stylo-mastoid foramen, and ramify in their 
respective muscles, after a certain course beneath the parotid gland. 
_ 9 Cervicat Branon (Figs. 336, 6).—-This nerve has its origin almost 
in the middle of the subparotideal portion of the facial, near a particular loop 
thrown by that nerve around the posterior auricular artery, and often from 
this loop itself. 

It afterwards traverses the parotid gland from within to without, and 
above to below, to descend at first on its external face, beneath the parotido- 
auricularis muscle, then into the jugular channel, where it is lodged below the 
deep face, or in the substance of the subcutaneous muscle of the neck, which 
receives its terminal divisions near the anterior appendix of the sternum. 

In its course this nerve communicates with the inferior branches of the 
second, third, fourth, fifth, and sixth cervical pairs by branches from them; 
it sends numerous collateral filaments into the texture of the subcutaneous 
muscle. 

10. Finaments or tHE Gutruran Povcn anp Parorip Gianp.— 
Remarkable for their number and tenuity, these filaments do not otherwise 
deserve particular mention. 

11. Posrrrion Avricunar Nerve (Fig. 336, 2).—It commences at 
the stylo-mastoid foramen, is directed upwards beneath the parotid gland, 
accompanying the posterior auricular artery, and is distributed to the 
posterior muscles of the external ear. It sometimes offers at its origin a 
loop analogous to that embracing the posterior auricular artery. 

12. Mipprz Avricutar Nerve.—Most frequently this arise from the 
same point as the preceding nerve—it might be said in common with it— 
ascends towards the base of the concha in traversing the parotid gland, and 
pierces the cartilage to supply the interconchal integument and the con- 
tractile fibres which cover its adherent face in some parts. 

13. Awrertor Avricutar Nerve (Fig. 336, 5).—This is the largest 
of the three auricular nerves. After being detached from the facial nerve, 
opposite the cervical branch, and after ascending across the parotideal 
tissue, it gains the external face of the zygomatic process, where it meets 
the superficial divisions of the lachrymal nerve; it continues forward 
beneath the external parieto-auricular muscle, reaches the base of the orbital 
process at the supra-orbital foramen, there crossing the terminal branches of 
the nerve of that name; it then descends vertically within the orbit to beiow 
the nasal angle of the eye, where it mixes with the superficial divisions of 
the palpebro-nasal nerve, and finally terminates on the face in the lachrymal 
and supernaso-labialis muscles. ‘ 

In its progress, it gives off numerous ramuscules to the anterior 
muscles of the car, the fronto-supra-orbital, and the orbicularis of the eye- 
lids, whose cuntractibility it excites. 

49 


726 THE NERVEs. 


This nerve is remarkable for the relations it maintains with the terminal 
ramuscules of the three branches of the ophthalmic nerve, or fifth pair. 
Although there do not exist any real anastomoses between it and these 
various branches, it is customary to designate the reticular mass they form 
in front of the ear and on the side of the face, as the anterior auricular pleaus, 

TerMinaL BrancHes oF THE FactaL Nerve orn Supzyeomatic Piexus 
(Fig. 110, 11, 12).—The facial nerve, as we have seen, terminates in several 
branches, usually two, on arriving beneath the temporo-maxillary articula- 
tion, where they join the superficial temporal nerve. After becoming sensory- 
mafor, they are continued on the external face of the masseter, covered by 
the subcutaneous muscle of the head, to which they give some ramuscules, 
and are united to each other by anastomosing branches of variable disposi- 
tion, which we need not stay to examine. It is always observed with regard 
to this arrangement, that the branches of the subzygomatic plexus, on 
arriving near the anterior border of the masseter, are divided into a series of 
divergent ramuscules which pass to the surface of the vascular or glandular 
canals situated in front of the masseter, to enter the tissues of the lips, 
cheeks, and nostrils. 

Among these ramuscules, the superior is remarkable for its great volume ; 
it passes beneath the zygomato-labialis muscle, lies close to the inferior 
border of the supermaxillo-nasalis magnus, beside the superior coronary 
artery, and afterwards runs below the supernaso-labialis muscle, where it joins 
the terminal ramuscules of the superior maxillary nerve, with which it is 
distributed to the textures of the upper lip and ale of the nose (Fig. 336, 7’). 

A second ramuscule—the inferior, smaller than the preceding—follows 
the inner aspect of the maxillo-labialis muscle, to mix by its anterior extremity 
with the terminal fasciculus of the inferior maxillary nerve, and ramify, 
with the proper filaments of that fasciculus, in the tissue of the lower lip. 

Between these two principal branches is a series of smaller ramifications 
destined to the alveolo-labialis muscle. Among these are some which 
become inflected on the inner face of the masseter, and reach the deep 
portion of the buccinator, where they anastomose with the filaments of the 
buccal nerve. Other ramuscules, situated below the principal inferior 
branch, are expended in the subcutaneous muscle of the face; one of them, 
after bending round the lower border of the inferior maxilla, reaches the 
intermaxillary space. 

Functions or tHe Factau Nerve.—This nerve excites the contractility 
of the muscles of the middle ear, external ear, the cheeks, lips, nostrils, 
orbicularis of the eyelids, and the cervico-facial subcutaneous muscle. By 
its great superficial petrous filament, it influences the movements of the 
muscles of the soft palate, and it is admitted, as already noticed when speak- 
ing of the gustatory nerve, that its tympano-lingual ramuscule acts as an 
excitant to the submucous muscular layer of the tongue. The facial nerve, 
also, without doubt, exercises its influence on the parotid gland; thus its 
action in this respect is not well determined; perhaps it is limited to pro- 
ducing the contractions of the excretory canaliculi which escape from the 
lobes of the gland. 

It is to be remarked that the facial nerve has no influence over the 
masseter muscle ; notwithstanding their intimate relations, it does not detach 
the smallest filament to it. 

It is necessary to say, that its anastomoses with the various branches of 
the trigeminus and pneumogastric nerves, while endowing its distributive 
ramuscules with great sensibility, in no respect modify its mode of action 


THE CRANIAL OR ENCEPHALIC NERVES. 727 


or its properties, because, notwithstanding these anastomoses, its proper 
fibres preserve their complete independence. 


8. Highth Pair, or Auditory Nerves. (Figs. 824, 338.) 


This.is the nerve of hearing, and affects a very simple disposition, which 
we will sum up in a few words. 

Origin —The auditory nerve (portio mollis) proceeds from the medulla 
oblongata by two roots, an anterior or lateral, and a posterior. The latter 
(Fig. 38238, 20) commences on the floor of the fourth ventricle by some 
convergent strize (linew transverse, strie medullares), as is admitted in .the 
majority of treatises on human anatomy, though we have never been able to 
discover these striz in the domesticated animals; it is afterwards directed 
outwards in winding round the posterior cerebe]lar peduncle, and unites with 
the anterior root on the side of the medulla oblongata. ‘he latter root 
(Fig. 838, g), consists of a single fasciculus joined with that of the -facial, 
and escapes from between the fibres of the corpus restiforme. The nucleus 
of the auditory nerve has been discovered by Schroeder Van der Kolk, a 
little below that of the facial nerve. 

Course and Termination—These two roots immediately unite into a 
‘single soft cord situated behind that of the seventh pair, with which it is 
directed outwards to reach the internal auditory hiatus (or meatus.) There 
it divides into two branches—an anterior and posterior, whose fasciculi 
traverse the foramina at the bottom of that hiatus: the former to gain the 
axis of the cochlea (the cochlear branch), and the latter the semicircular 
canals (vestibular branch.) The description of these two branches will be 
deferred till we come to the sense of hearing. 


9. Ninth Pair, or Glosso-Pharyngeal Nerves. (Figs. 338, 3; 342, 10.) 


The glosso-pharyngeal is a mixed nerve, which carries general sensation, 
with gustative sensibility, into the posterior third of the tongue, and excites 
‘ontraction of the pharyngeal muscles. 

Origin.—This nerve originates on the side of the medulla oblongata, 
hehind the eighth pair, by eight or ten fine roots, some of which are 
implanted in the corpus restiforme, while the others, the smallest number, 
escape, like the filaments of the facial nerve, from the interstice between 
that body and the lateral column of the medulla oblongata.t These roots 
soon unite in a single cord, which issues from the cranium by a particular 
orifice in the posterior foramen lacerum, and at this point exhibits a grey 
oval-shaped enlargement—the ganglion peirosum or ganglion of Andersch, in 
which it is somewhat difficult to distinguish the motor filaments of the 
nerve from those which arise between the lateral and superior columns of the 
medulla oblongata (Fig. 338, 2). 

Course and Termination.—Scarcely has the glosso-pharyngeal nerve 
escaped from the cranium, before it descends, in describing a curve whose 
concavity looks forward, behind the large branch of the os hyoides, included 
at first between a fold of the guttural pouch, then between the latter and 

1 is di iti sch is readily exposed in the Horse, appears to us sufficient to 
ee art pea puro in emia of a large number of anatomists, as to the 
nature of the glosso-pharyngeal nerve. It evidently possesses at its origin, as motor 
filaments, those arising from the same part as the facial nerve, and as sensitive filaments 
those from the corpus restiforme. Besides, we may object to the opinion which would 
also attribute the motor property of the glosso-pharyngeal nerve to the anastomosing 
branches passing between it and the seventh pair, on the ground that these anastomuscs 
are far from being constant, and that in some species they are always totally absent. 


728 THE NERVES. 


the internal pterygoid muscle. Lying beside the external maxillary 
artery in the latter part of its course, it passes with it along the posterior 
border of the large branch of the hyoid bone, and gains the base of the 
tongue with the lingual artery, by coursing beneath the hyo-glossus brevis 
muscle. The papille on the posterior portion of the lingual mucus mem- 
brane receive the terminal ramuscules of this nerve. (See the Sense of Taste.) 

Collateral Branches.—On its course it furnishes : 

1. Jacobson’s nerve (tympanic branch), a very thin filament springing from 
Andersch’s ganglion, proceeding upwards, and entering a particular foramen 
in the tuberous portion of the temporal bone, to be distributed more 
especially to the tympanum, sending also to the superficial petrous nerves 
two branches which are designated the deep great and small petrous nerves. 

2. Filaments of communication with the superior cervical ganglion, two 
or three in number, though sometimes replaced by a single ramuscule. 

3. A branch to the carotid plexus, which passes back on the guttural 
pouch to reach the terminal extremity of the common carotid, whence its 
filaments are sent, with those of the sympathetic nerve, either to the external 
carotid, occipital, or even to the common carotid artery itself. This branch 
communicates, by several anastomoses, with the numerous sympathetic 
branches which pass from the superior cervical ganglion to the surface of 
the guttural pouch, and which are either expended in that membrane, or 
join the posterior border of the great hypoglossal nerve. 

4. A pharyngeal branch (Fig. 342, 11), which is generally detached close 
to the pharyngeal artery, and forms, along with the pharyngeal filaments of 
the pneumogastric nerve, a remarkably intricate plexus (pharyngeal) on the 
upper wall of the pharynx, below the guttural pouch. This plexus reccives 
a filament from the hypoglossal nerve. 


10. Tenth Pair, Vagus, or Pnewmogastric Nerves. (Figs. 838, 342, 362.) 


The pneumogastric nerve is as remarkable for its extent, as for the 
multiplicity of physiological uses imposed upon it. 

It is prolonged to beyond the stomach, after distributing to that viscus, 
the cesophagus, pharynx, lung, bronchi, trachea, and larynx a large number 
of filaments on which depend the movements, secretory functions, and 
purely sensory phenomena of which all these organs are the seat. 

Origin.—The pneumogastric is 2 mixed nerve, and consequently arises 
from two kinds of roots; these we will successively describe before passing 
to its distribution, though it must be remarked that this subject has not yet 
been fully determined. 

Sensitive roots.—These arise from a nucleus of grey substance situated 
near the floor of the fourth ventricle, a little behind the glosso-pharyngeal 
nucleus, and in which the fibres of the antero-lateral columns of the medulla 
oblongata, or respiratory track of Bell, seem to be lost. In leaving the 
medulla, they form from four to ten bundles, which describe a slight curve 
whose convexity is upwards; the highest median fibres correspond to the 
groove that limits, superiorly, the respiratory tract, the posterior and ante- 
rior fibres bending down to the pyramids—the second more than the first. 

These roots proceed transversely outwards, mixed with connective tissue 
and some fine muscular ramifications, and leave the cranium by one of the 
openings (jugular foramen) in the posterior foramen lacerum, uniting in 


their passage through that aperture in a somewhat voluminous ganglion, 
called in Man the jugular ganglion. 


THE CRANIAL OR ENCEPHALIC NERVES. 729 


Motor roots.—Several anatomists and physiologists consider these as a 
portion of the accessory nerve of Willis, and give them the name of internal 
or bulbous root of the spinal nerve. They are situated a little behind the pre- 
ceding, and emanate from the respiratory tract; consequently they are not 
so elevated as the whole of the sensitive fibres. They are separated from 
the sensitive roots by a comparatively large vein, and are distinguished from 
them by their anastomotic tendency. Becoming longer as they are moro 
posterior, and frequently anastomosing with each other, the filaments 
forming these motor roots converge, and gain the posterior foramen lacerum ; 
this they pass through by one or two special openings to join the jugular 
ganglion, beneath and behind which we find them applied. A certain 
number of the most posterior of these filaments lie beside the medullary 
root of the spinal nerve; but they are soon detached to pass with the 
others to the jugular ganglion. 

Jugular or Ehrenritter’s ganglion.— Elongated from before to behind, 
and flattened on both sides, the jugular ganglion is embedded in the 
cartilaginous substance that fills the foramen lacerum. When it has been 
macerated for some time in dilute nitric acid, it may be resolved into two 
portions : one corresponding to the sensitive, the other to the motor roots. 
Some white nervous filaments appear to pass to its surface without becoming 
confounded with it. It is in relation, in front, with the ganglion of An- 
dersch ; behind, it crosses somewhat obliquely the medullary root of the 
spinal nerve. 

The jugular ganglion is also in relation with the spinal, glosso-pharyn- 
geal, and facial nerve. It communicates with the external root of the spinal 
nerve by the few radicular filaments indicated above. With the glosso- 
pharyngeal it is connected by: 1, An afferent filament coming from the 
highest roots of the ninth pair, and which meets it at its antero-internal 
angle; 2, By an efferent branch it sends to the ganglion of Andersch. 
Lastly, it is united to the facial by a branch we have named the anasto- 
mosing branch extending from the pneumogastric to the facial nerve. 

This anastomotic branch, on leaving the jugular ganglion, is somewhat 
considerable in volume, and it has appeared to us that, at times, among its 
radicles there were some in direct continuity with the sensitive roots of the 
pneumogastric nerve. This branch is directed forward, above the ganglion 
of Andersch, crosses Jacobson’s branch, traverses the tuberous portion of 
the temporal'bone, and arrives in the aqueduct of Fallopius ; here it meets 
the facial nerve, at the point where the latter gives off the chorda tympani. 
A small number of its fibres then lie beside the nerve of the seventh pair , 
in ascending towards the origin of that nerve, where, in our opinion, they 
constitute a large portion of the great petrous nerve—that which has at 
its origin the geniculated ganglion. Other fibres descend, on the contrary, 
in following the proper fibres of the facial nerve, and are lost among these ; 
but the largest number cross that nerve and continue their course in the 
substance of the temporal muscle, to be chiefly distributed to the membrane 
lining the internal auditory canal. . 

Coir and Relations Beyond the jugular ganglion, the trunk of the 
pneumogastric remains intimately allied with the spinal accessory for about 
8-10ths of an inch; at this point we have been unable to find the gan- 
gliform plexus described in Man, though, according to M. Bernard, it exists in 
the Rabbit. The two nerves then separate to allow the great hypoglossal nerve 
to pass between them : after which the pneumogastric nerve descends alone 
behind the guttural pouch, in proximity to the superior cervical ganglion, 


730 THE NERVES. 


Near the origin of the occipital artery it crosses to the inner side of 
that vessel, and beyond this is joined in the most intimate manner to the 
cervical portion of the sympathetic chain; the single cord resulting from 
this fusion follows the common carotid artery, above which it is situated, 
to near the entrance of the thorax. The two nerves then resume their 
reciprocal independence, the pneumogastric penetrating the thorax a little 


Fig. 338. 


ORIGIN OF THE NERVES SPRINGING FROM THE MEDULLA OBLONGATA, AND PAR- 
TICULARLY THAT OF THE PNEUMOGASTRIC, SPINAL, HYPOGLOSSAL, alp GLOSSO- 
PHARYNGEAL, 

a, Medulla oblongata; 6, Pyramids; c, Enlargement simulating the olivary body ; 
d, Lateral posterior fissure; ¢, Fissure limiting superiorly the respiratory tract 
of Ch. Bell; f, Corpus restiforme; g, Auditory nerve; A, External oculo-motor ; 
i, Trigeminus; j, Arciform fibres of the medulla oblongata.—1, Pneumogastric ; 
2, Spinal, inner root; 3, Glosso-pharyngeal; 4, Spinal, medullary column; 5, 
Inferior, or anterior, root of the great hypoglossal; 5’, Its ganglionic root; 6, 
Facial; 7, Jugular ganglion; 8, Anastomosis of the pneumogastric with the 
facial; 9, Ramuscule from the external branch of the spinal passing to the pneu- 
mogastric—From Toussaint’s Thesis on the ‘Anatomie Comparée du Nerf 
Pneumogastrique.’ Lyons, 1869. 


below the sympathetic, in passing among the lymphatic glands existing 
between the two first ribs. 

In this course, the two pneumogastrics affect nearly the same relations; 
though there is something special connected with the left, which corres- 
ponds with the cesophagus towards the lower part of the neck. 

Within the chest, however, these two nerves comport themselves a 


PNEUMOGASTRIC NERVE, 


a, Esoph 
Glosso- 


THE CRANIAL OR ENCEPHALIC NERVES. 731 


Fig. 339. 


= 


agus ; 


facial artery ; 1, 


WITH ITS BRANCHES IN THE UPPER PART OF THE NECK 


b, Trachea; c, Common carotid; d, Internal maxillary artery; ¢, 
1, Pneumogastric nerve ; 2, Spinal accessory ; 3, Glosso- 


THE NERVES. 


little differently. The right passes round the axil- 
lary artery very obliquely, upwards, outwards, and 
backwards beneath the mediastinal pleura, to follow 
the external face of the trachea to above the origin 
of the bronchi, where this nerve terminates. The 
left also passes below the brachial trunk ; but 
instead of turning round the trachea, it merely 
lies beside that tube, and reaches the root of the 
lung, after crossing, outwardly, the origin of the 
two aorta. 5 

When these nerves arrive above the bifurca- 
tion of the trachea, they terminate by forming 
the bronchial plexus and esophageal nerves—the 
- latter being prolonged to the stomach and the 
solar plexus. 

Beneath the jugular ganglion, but in the upper 
part of the neck, the pneumogastric receives fila- 
ments from the spinal accessory, ganglion of 
Andersch, sympathetic, hypoglossal, and the two 
first cervical. These different nerves cross each 
other in a very complex manner on the surface 
of the guttural pouch, the pharynx, and divisions 
of the carotids, and form the guttural, pharyngeal, 
and carotid plexuses. 

Distribution.—The branches furnished by the 
pneumogastric on its course are: 


1. Communicating filaments with the superior 
cervical ganglion. 

2. Pharyngeal branch. 

3. Superior laryngeal nerve. 

4, Communicating filaments with the inferior 
cervical ganglion. 

5. Inferior laryngeal nerve. 


We will pass in review these collateral divisions 
before studying the terminal branches, which are: 

1. Those forming the bronchial plexus. 

2. Those constituting the esophageal nerves. 


ORIGIN AND DISTRIBUTION oF 1,3, 4, Medulla oblongata ; 1, Corpus pyramidale of one 
THE EIGHTH ParR oF ‘side; 2, Pons Varolii; 3, Corpus olivare; 4, Corpus 
NERVES IN MAN. restiforme; 5, Facial nerve; 6, Origin of glosso- 

pharyngeal nerve; 7, Ganglion of Andersch; 8, Trunk 
of the nerve; 9, Spinal accessory ; 10, Ganglion of pneumogastric; 11, Its plexiform 
ganglion; 12, Its trunk; 13, Its pharyngeal branch, forming the pharyngeal plexus, 
14, assisted by a branch from the glosso-pharyngeal, 8, and one from the superior 
laryngeal, 15; 16, Cardiac branches; 17, Recurrent laryngeal branch; 18, Anterior 
pulmonary branches; 19, Posterior pulmonary branches; 20, Esophageal plexus; 
21, Gastric branches; 22, Origin of the spinal accessory nerve; 23, Its branches dis- 
tributed to the sterno-maxillaris and mastoido-humeralis; 24, Its branches to the 
trapezius muscle. 


pharyngeal nerve; 4, Great. hypoglossal nerve; 5, Superior cervical ganglion of the 
sympathetic ; 6, Pharyngeal nerve; 7, Superior laryngeal; 8, External laryngeal ; 
9, Inferior laryngeal; 10, Cord of the pneumogastric and sympathetic; 11, First 
cervical nerve, with the loop it sends to the hypoglossus.—From Toussaint’s work. 


THE CRANIAL OR ENCEPHALIC NERVES. 733 


CottaTeraL Brayouzs or THE Pneumocastrio Nerve.—l. Froaments 
or THE Iyrerion Cervican Ganerion.—Always very slender, these some- 
times come from the pharyngeal ramuscule. 

2. Puaryneuan Nerve (Figs. 339,6; 342, 15).—Originating from the 
pneumogastric nerve at the middle part of the superior cervical ganglion, 
the pharyngeal passes forwards and downwards on the side of the guttural 
pouch, and gains the upper face of the pharynx, where it terminates in 
forming a plexus with the pharyngeal branch of the ninth pair. This is a 
sensory-motor branch. It gives off a large division that passes backwards 
to the surface of the middle and posterior constrictor muscles, to which it 
gives branches, and, throwing off a filament to the external laryngeal nerve, 
reaches the commencement of the cesophagus; it descends on the outside 
of that canal by becoming distributed in its muscular tunic. This division, 
which we have named the esophageal branch of the pharyngeal nerve, may 
be traced on the cesophagus to the lower part of the neck, and in some 
subjects even into the thoracic cavity. 

3. Superior Larynezan Nerve (Fig. 339, 7)—More voluminous 
than the preceding, and arising a little lower, this nerve follows an 
analogous course to reach the side of the larynx, where it enters the 
aperture below the appendix of the superior border of the thyroid cartilage, 
to be almost entirely expended in the laryngeal mucous membrane, to 
which it communicates a very exquisite degree of sensibility. 

At the inner face of the thyroid cartilage, it presents several branches 
that are directed forward, upward, and backward. The first pass to the 
mucous membrane at the base of the tongue and the two faces of the epi- 
glottis. The second are distributed in the lateral walls of the pharynx. 
Of the third, some are destined to the mucous membrane of the arytenoid 
cartilages and that of the cesophagus; while others descend on the thyro- 
arytenoid and lateral crico-arytenoid muscles, to unite with the branches 
coming from the recurrent, and form an anastomosis analogous to the 
anastomosis of Galien (Fig. 341, 5). 

Before penetrating the larynx, and even very near its commencement, 
it furnishes a motor filament to the crico-pharyngeal and crico-thyroid 
muscles; this filament either arises directly from the pneumogastric nerve, 
or, as is most frequently the case, from the pharyngeal ramuscule ; this is 
the external laryngeal nerve of anthropotomists (Fig. 339, 8). It receives 
accessory branches from the superior cervical ganglion, the cesophageal 
branch, and the pharyngeal nerve, and is then distributed to the muscular 
tunic of the esophagus. It is to the union of this branch with the cesopha- 
geal branch of the pharyngeal nerve, that we have given the name of superior 
cesophageal nerves. 

4, Communrcating FInaMENTS WITH THE Inrerion Cervical, GANGLION. 
—These do not always directly enter this ganglion, for when the middle 
cervical ganglion exists they pass to it. They are not similarly disposed 
on both sides. The filaments of the right pneumogastric, two or three in 
number, are extremely short, though voluminous. The left pneumogastric 
usually only furnishes a single, long, thin ramuscule, which is detached in 
the region of the neck near the point where the pneumogastric commences 
to separate froni the cervical branch of the sympathetic, and reaches the 
inferior cervical ganglion by remaining alongside the principal nerve, 


\ 
1 Toussaint has seen this branch leave the cesnphagus to lie beside the recurrent; 
but its filaments always return to that canal as ascending twigs. 


734 THE NERVES. 


5. Inrertor LarynceaL Nerve (Fig. 362, 


27, 28).—Also named the 


recurrent, or tracheal recurrent, because of its disposition. It begins in the 
thoracic cavity and ascends along the trachea to the larynx, all of whose 
intrinsic muscles it animates, with the exception of the crico-thyroid. 


Fig. 341. 


DISTRIBUTION OF THE NERVES IN THE LARYNX OF THE 
HORSE, 

u, Base of the tongue; 6, Epiglottis; ¢, Arytenoid 
muscles; d, Section of the thyroid cartilage to show 
the parts it covers; ¢, Cricoid cartilage; f, Trachea; 
g, Esophagus; h, Thyro-arytenoid muscle; ¢, Lateral 
crico-arytenoid muscle; j, Posterior crico-arytenoid 
muscle; 2, Arytenoid muscle.—1, Superior laryngeal 
nerve; 2, Inferior laryngeal; 3, Branches of the supe- 
rior laryngeal passing to the epiglottis and tongue; 4, 
Branches of the superior laryngeal passing to the 
esophagus; 5, Very fine multiple anastomoses between 
the two laryngeals; 6, Tracheal branches; 7, Branch 
to the posterior crico-arytenoid muscle; a portion is 
distributed, through the muscles, to the subjacent 
mucous membrane; 10, Branch passing to the arytenoid 
muscle; 11, (sophageal branch of the pharyngeal 
nerve; it sometimes comes from the external laryn- 
geal.—F rom Toussaint’s work. 


Thetwo recurrent nerves 
are not quite symmetrical 
at their origin. That of the 
right side is detached from 
the pneumogastric below the 
axillary artery, nearly at the 
dorso-cervical arterial trunk, 
Tt is immediately reflected 
forward in embracing the 
origin of that trunk, which 
it crosses inwards to be 
laced against the trachea, 
in the middle of the prin- 
cipal cardiac nerves, with 
some of which it contracts 
intimate adherences. 

On the left side, it is 
only when the pneumogas- 
tric nerve arrives near the 
root of the lung that it 
gives off its recurrent. To 
be reflected forward, the 
latter turns from left to 
right behind the arch of 
the aorta, and arrives be- 
neath the inferior face of 
the trachea, among the 
cardiac nerves, with which 
it communicates like the 
right. 

The inferior laryngeal 
nerves are in this way 
mixed, at a greater or less 
distance from their com- 
mencement, with those sym- 
pathetic nervous branches 
which collectively constitute 
the tracheal plexus. They 
are soon disengaged, how- 
ever, and leave the chest, 
but always in proceeding 
along the inferior face of 
the trachea, then ascending 
on its sides, below the ca- 
rotid arteries, which they 
gradually approach, and 


finally attain the larynx in penetrating beneath the crico-pharyngeal 


muscle. 


According to Goubaux, the left recurrent must be situated more super- 


THE CRANIAL OR ENCEPHALIC NERVES. 735 


ficially than the right in the lower part of the neck, and for this reason 
should be more exposed to compression. He thus explains why, in chronic 
“roaring” the alterations observed are nearly always in the left muscles 
of the larynx. 

The terminal divisions of the recurrents are distributed to the posterior 
and lateral crico-arytenoid, and the arytenoid and thyro-arytenoid muscles, 
as well as to the subglottic mucous membrane. 

In their long course, they emit collateral ramuscules that also ascend, 
and are distributed to the mucous membrane and muscular layer of the 
trachea, as well as to that of the cesophagus, 

The recurrent esophageal ramuscules are all sensitive, and form five 
groups: the first and second arise, on the left side, close to the arch of the 
aorta, ascend on the sides of the trachea, and pass to the portion of the 
cesophagus lying between that canal and the thoracic section of the longus 
colli muscle. The third, more considerable, springs from a branch that is 
given off at the brachial trunks; it is markedly recurrent, and forms on 
the side of the trachea, with the second, a small plexus, and then lies 
closely alongside the cesophagus, which it accompanies for a distance of 
eight inches from the first rib. The branch constituting the fourth group 
is the longest of all; it is detached about two or two and a-half inches in 
front of the first rib, and after emitting several long tracheal filaments, it 
ascends on the side of the trachea close to the border of the cesophagus, 
where it generally disappears at about six or eight inches from the pharynx. 
The fifth group is composed of a branch detached from the recurrent, about 
the point where the preceding terminates; it goes entirely to the origin 
of the canal. 


TERMINAL BRANCHES OF THE PNEUMOGASTRIC NERVES. 


1. Broncntan Prexus (Fig. 362, 29).—The bronchial plexus is formed 
oy several branches from the pneumogastric, on the arrival of that nerve 
above the roots of the lungs, and which interlace in a network and ramify 
around the bronchial divisions following these into the texture of the 
pulmonary organ. It is these branches which give to the mucous membrane 
its great sensibility, and which provoke those evident contractions of which 
it is the seat. ean 

2. CisopHacean Brancnes (Fig. 362, 30, 31).— After emitting the 
ramuscules of the bronchial pléxus, each pneumogastric is continued along 
the cesophagus by two branches—a superior and inferior—making four 
branches for the two nerves. The two superior lie together, and are 
confounded in a single cord, either immediately, or after a certain course 3 
the two inferior comport themselves in the same manner with one another; 
making a double anastomosis, from which arise the two nerves we are 
about to describe, and which are designated the esophageal nerves, because 
of their gituation. The right nerve forms a large portion of the superior 
cord ; the left, especially, gives ramuscules to the inferior. 

Placed between the layers of the posterior mediastinum, these two 
nerves follow the esophagus for a certain distance, one above, the other 
below, giving off some ramuscules to that muscular canal, detaching one or 
two communicating branches, and traversing the opening in the right 
pillar of the diaphragm to penetrate the abdominal cavity. 

The inferior terminates in the parietes of the stomach, by forming 
on the small curvature, to the right of the cardia, a very rich plexus 


736 THE NERVES. 


which throws the majority of its ramuscules into the right sac of that 
viscus. 

The superior passes to the left of the oesophageal insertion, along with the 
gastro-pulmonary artery, and is lost in the solar plexus, after giving off 
numerous divisions on the left sac of the stomach, mixing with the 
sympathetic ramuscules that encircle the gastric artery, and anastomosing 
around the cardia with those of the inferior cord. It is very difficult to 
follow the filaments of this cord from the pneumogastrics after their arrival 
at the solar plexus; we nevertheless observe some of them passing to the 
liver, others accompanying the sympathetic branches that come from the 
solar to the posterior mesenteric plexus in following the small mesaraic 
vein; no doubt the others find their way among the filaments of the 
trisplanchnic nerve, which proceed with the anterior mesenteric artery. 

Functions or THE Pnevmoaastric.—Formed by the two orders of fibres, 
the pneumogastric is a sensory-motor nerve, and the seat of reflux currents 
which make it play a very important part in several acts of vegetative life, 
and bring it into relationship with the great sympathetic nerve, with which 
we have seen that the tenth pair maintains anastomotic connexions in several 
points of its course. 

It is the pneumogastric nerve that gives to the mucous membrane of the 
larynx the exquisite sensibility it enjoys. 

It stimulates the motor muscles of that organ into movement. 

To it is also due the sensibility of the broncho-pulmonary mucous 
membrane. 

It excites the contractions of the muscular fibresin the broncho-tracheal 
passages —contractions which are involuntary, and under the influence of the 
reflex power. 

It also provokes the movements of the cesophagus and stomach, which 
are also involuntary and due to reflex currents. 

Perhaps it acts in an analogous manner—by reflex action—in the 
secretion of the gastric fluid and the functions of the liver; but these are 
points which science has not yet decided upon. 

It appears proved that it does not exercise any direct influence on the 
essential phenomena of réspiration. 

It also appears proved that it acts on the heart in a very energetic 
manner, though this has been imperfectly determined. We only know that 
after its section in the region of the neck, the movements of the heart 
become very precipitate, and that we may diminish the force of these 


movements, or even completely arrest them, by galvanising the peripheral 
end of the nerve. 


11. Eleventh Pair, Spinal Nerves, or Accessory Nerves of the Pneumogastrics. 
(Fig. 338, 2, 4.) 


Tho spinal accessory is an exclusively motor nerve, which, at its exit 
from the cranium, is so intimately connected with the pneumogastric, that 
we might perhaps follow the example of Miiller, and describe the two as 
forming one and the same pair. 

Origin.—This nerve exhibits a singular disposition, in that it arises from 
the whole extent of the cervical spinal cord, and ascends in the spinal canal 
to near the pneumogastric, with which it leaves the cranium by the pos- 
terior foramen lacerum. It is also described as an encephalic nerve, in 
consequence of the latter peculiarity ; but trom its origin it is rather a 


THE CRANIAL OR ENCEPHALIC NERVES. 737 


spinal nerve, a fact which is sufficiently indicated by the name senorally 
given to it. 

In the interior of the spinal canal, it is a long cord measuring from 

27 to 31 inches in middle-sized animals. It commences, by a very fine 
point, at the cervical or brachio-rachidian bulb of the spinal cord, follows 
that organ in an ascending courso, lying close to its lateral column, and 
passing between the roots of the two orders of cervical nerves until it arrives 
at the medulla oblongata, where it is inflected outwards at the foramen 
lacerum posterius, into which it passes to leave the cranium. 
_ In this ascending track, it gradually increases in volume, as it at 
intervals receives additional filaments from the lateral column of the spinal 
cord, like the radicular extremity of the nerve itself. Before making its 
escape from the cranium, it receives, besides, some of'the posterior or motor 
roots of the pneumogastric nerve. In the foramen lacerum, it becomes 
applied against the ganglion (jugular) of that nerve, in the manner of motor 
fibres of mixed nerves, and gives it some of its proper filaments. 

The long cord here described as the root of the spinal accessory, 1s 
considered by some authorities as only a portion of this nerve, to which 
they give the name of external or medullary root of the spinal accessory. 
They designate as the internal or bulbous root of that nerve, the anastomosing 
filaments already described as the motor roots of the pneumogastric. 
According to them, this internal root only lies beside the pneumogastric for a 
very short distance, ultimately leaving it and forming the superior laryngeal 
and pharyngeal nerves, which seem to arise from the vagus rather than 
the accessory of Willis. 

Distribution.—Beyond the ganglion of the pneumogastric, the spinal 
accessory remains beside the trunk of the pneumogastrie for scarcely an 
inch; it then separates from it at an acute angle whose sinus is occupied 
by the great hypoglossal nerve, is directed backwards, passing beneath the 
superior extremity of the maxillary gland and levator humeri, gains the 
supero-posterior border of that muscle, and follows it to the front of the 
shoulder. Here it slightly ascends, crosses that region below the inner 
face of the cervical trapezius, and is distributed to the dorsal trapezius. _ 

On its passage it emits: 1. One or two thick filaments to the superior 
cervical ganglion, proceeding from the spinal by a small plexiform network 
where the nerve separates from the pneumogastric; 2, Near the maxillary 
gland, a thick branch to the sterno-maxillaris muscle ; 8, Slightly beyond 
this, another branch destined to the anterior portion of the levator humeri : 
4, A series of ramuscules to the cervical trapezius. ; 

In its course, the spinal accessory traverses the anterior part of the 
superficial cervical plexus, and receives additional ramuscules from the 
first, second, third, fourth, fifth, and sometimes even from the sixth cer- 

ical nerves. 
ee etaced to its medullary root, as has been described, the spinal 
accessory animates the muscles to which it is distributed, and through them 
has a share in expiration. By the contraction of these muscles, the ribs 
may be maintained raised fora certain period, and cause the air to be slowly 
expelled; also allowing the sounds or voice produced by its passage through 
the larynx to be modulated. Crowing is no longer possible in birds when 
the medullary root of the spinal accessory has been divided, as has been 


demonstrated by Bernard. 


738 THE NERVES. 
12. Twelfth Pair, or Great Hypoglossal Nerves. 
(Figs. 111, 22; 338, 5; 342.) 


The great, or simply the hypoglossal nerve, is exclusively motor, and 
animates the muscles of the tongue. 


Fig. 342. 


DEEP NERVES OF THE HEAD, 


1, Superior maxillary nerve at its exit from the foramen lacerum; 2, Trunk of the 
masseteric ; 3, Trunk of the subzygomatic; 4, Buccal; 5, Lingual or gustatory ; 
6, Chorda tympani; 7, Inferior maxillary, cut near where it enters the maxillo- 
dental canal; 8, Trunk of the mylo-hyoideus ; 9, Pterygoid; 10, Glosso-pharyngeal ; 
11, Its pharyngeal branch; 12, Its lingual branch; 13, Pneumogastric; 14, 
Superior laryngeal branch of that nerve; 15, Its pharyngeal branch; 16, Spinal 
accessory of Willis; 17, Great hypoglossal ; 18, Origin of the cervical cord of the 
great sympathetic; 19, The same after its union with the pneumogastric.—A, 
Common carotid artery; B, Accessory thyroid artery; C, Thyro-laryngeal artery ; 
D, Origin of the internal carotid artery—the vessel is concealed by the guttural 
pouch; 2, Occipital artery; ¥, External carotid artery; G, Internal maxillary 
artery; H, Pharyngeal artery (drawn too large); J, External maxillary artery ; 
J, Lingual artery; A, Origin of the maxillo-muscular artery; Z, Posterior 
auricular artery; J/, Trunk or origin of the superficial temporal artery; 0, 
Inferior dental artery; P, Posterior deep temporal artery; Q, Anterior deep 
temporal artery; R, Maxillary gland; S, Wharton’s duct; 7, Sublingual gland. 
The letter NW placed at the upper end of the large cornu of the hyoid bone has 
no signification. 


Origin —It originates at the lower face of the medulla oblongata, from 


THE CRANIAL OR ENCEPHALIC NERVES. 739 


the prolongation of the line of insertion of the inferior spinal roots, by a 
dozen converging filaments. These traverse the dura mater in two or 
three bundles, which enter -the condyloid foramen of the occipital bone, 
where they unite to form a single cord. Tho hypoglossal has also a 
ganglionic root which Toussaint constantly found in the Ass, Mule, Ox, 
und Dog, and which had been previously seen by Meyer and Vulpian. 
The ganglion of the hypoglossal in the Horse is fusiform, and the size of 
a small lentil (Fig. 338, 5’). It is sometimes absent. 

Distribution.—The hypoglossal nerve thus constituted, immediately after 
its departure from the condyloid foramen, communicates with the first 
cervical pair by means of a transverse ramuscule; it then passes between 
the spinal accessory and pneumogastric nerves, descends on the external 
face of the guttural pouch, where it is connected with the superior cervical 
ganglion of the sympathetic by numerous filaments, which in great part form 
the plexiform network called the “guttural plexus.” The nerve afterwards 
crosses to the outside of the external carotid artery, in proceeding forward 
and downward on the side of the pharynx and larynx, receiving at that 
point a slender ramuscule from the first cervical ; it then passes within the 
inferior extremity of the stylo-hyoid muscle and the glosso-facial artery, 
which it crosses very obliquely, is prolonged between the mylo-hyoid and 
hyo-glossus brevis muscles, sends numerous small filaments to the latter and 
a ramuscule to the genio-hyoideus, and finally terminates in a series of 
branches analogous to those of the gustatory nerve, and which mix with 
them. 

These branches are therefore reflected upwards, bending round the 
posterior border of the hyo-glossus brevis, and pass into the interstice between 
that muscle and the genio-glossus. They are distributed to all the muscles 
of the tongue. 

The hypoglossals, being motor nerves, cause the contraction of the 
muscles of the tongue during the movements proper to mastication and the 
production of the voice. Though they most frequently act together, yet 
they may de so separately, as in the unilateral movements of the tongue. 


DIFFERENTIAL CHARACTERS IN THE CRANIAL NERVES OF OTHER THAN SOLIPED 
ANIMALS, 


In the domesticated mammals, the cranial nerves offer the greatest analogies; their 
origin is the same in all, and it is only in their distribution that we find some variety, 
due to the difference in the form of the head. Consequently, in this comparative analysis 
we shal] not discover any fundamental differential characters, 

Ruminanrs.—There is no difference to note in the four first pairs. 

Trigeminal nerve-—Divided into three branches as in Solipeds. It has been stated 
that in Ruminants the ophthalmic branches are distributed to the majority of the muscles 
of the eye; in the Sheep we have only seen the palpebro-nasal nerve offering this relation- 
ship to the motor organs of that part. The anterior palatine nerve is relatively 

inous. at 
bag nerve-—Towards the middle of its subparotideal course, this gives off a large 
anterior auricular nerve: when it arrives at the middle of the posterior border of the 
masseter muscle, it divides into two branches. The inferior branch passes obliquely down- 
wards and forwards, towards the mental foramen, where it terminates as in the Horse ; 
it furnishes an anastomotic branch to the superior. The latter crosses the middle 
portion of the masseter, and becomes mixed with the suborbital ramu:cules of the fifth pair ; 
about the middle of its course it receives a filament from the superficial temporal nerve. 
We need not allude to the auditory and glosso-pharyngeal nerves, except to say that the 
latter communicates with the pneumogastric soon after its exit from the foramen lacerum. 

Pneumogastric nerve.—This offers uumerous differences in its rvots and distribution. 

In the Ox and Sheep, the sensitive roots arise from an irregularly elliptical surface 
comprising the whole of the respiratory tract. They are from fifteen to twenty in 


THE NERVES. 
Fig. 343 


740 


NERVES OF THE GUITURAL REGION IN THE OX. : 
a, Esophagus ; 8, Trachea; c, Common carotid artery ; d, Glosso-facial artery; 1, 
Pneumogastric nerve ; 2, Spinal accessory ; 3, Glosso-pharyngeal; 4, Great sym- 


THE CRANIAL OR ENCEPHALIC NERVES. 741 


number, and often join each other; they may divided into three principal fasciculi rising 
at slight distances. 


The motor roots are a little larger than in the Horse; before joining the sensitive roots 
they are confounded in a small ganglion that pertains to them. 

The jugular ganglion is voluminous, but apart from this it presents the same features 
as in the Horse, receiving all the proper roots of the pneumogastric and internal root of 
the spinal accessory, and even those which are united in their own ganglion. The 
portion of the ganglion that is more especially formed by the roots of the spinal accessory 
is rather an intrication of nerve-fibres than a real ganglion; it is impossible by the most 
minute dissection to separate it from the rest of the ganglion. ; 

The jugular ganglion also receives a division of the glosso-pharyngeal, and it gives 
one to this nerve and the external branch of the spinal accessory. 

The pneumogastric nerve, in the guttural portion, is much larger than in the Horse. 
This peculiarity is noticeable throughout its whole extent, and is indicated at its 
ruots. 

* The ganglionic plexus is absent in the Ox. The course and relations of the nerve in 
this portion are analogous to those observed in Solipeds. . : 

The pharyngeal nerve is voluminous, and the branch it sends to the cesophagus is the 
largest of its divisions: this branch passes backwurds to the surface of the constrictors 
of the pharynx, joins the external laryngeal, gives a large branch to the thyro-pharyngeus, 
anil is insinuated on the sides of the oesophagus, between it and the thyroid gland; theie 
it divides into two portions, one of which descends on the sides of the cesophagus where 
it forms a very rich plexus with the branches from the inferior laryngeal, while the other 
is lost immediately in the recurrent nerve at the thyroid gland. . 

The external laryngeal arises at a short distance above the superior laryngeal, where 
it receives a large branch from the glosso-pharyngeal and another from the sympathetic, 
and immediately passes alongside the ceoplageal branch of the pharyngeul nerve. 
With a little attention, we may dissect a fasciculus coming from the external laryngeal 
and passing to the crico-thyroid muscle, and the thyroid gland and its vessels, after receiv- 
ing a branch from the superior laryngeal. In the Sheep, the external laryngeal sometimes 
gives a branch to the cesophagus, and which anastomoses with ihe inferior laryngeal, or 
descends on the side of the tube, conjointly with the cesoplageal branch of the 

eal. ~ ALE 
ee eee laryngeal rises below the preceding: it is very voluminous, and ou 
municates with the sympathetic, either directly or through the medium of the pate 
plexus, and with the pharyngeal nerves and external laryngeal. Beneuth a u Be 
cartilage, a large division anastomoses with the inferior laryngeal, and is aie y lost . 
that nerve below the larynx. It is neue sare that a hee vives, in the cervica 

i umber of filaments to the wsophazus and trachea. : 
ee With ete of some insiguificant ee ane, the pneumogastric compoits 

i i ical and thoracic regions as in the Horse. ; : 
fag pei arise as in Balipeds, but their relations are soles st different A the 
cervical region. They are placed in the channel tormed by the trachea and eae bee 
and are separated from the pace a ae hese a pun ue bart a 
pneumogastrie by the very great width of the igre "only noteworthy featiiea 13 Whe 
muscles of the larynx takes place as in tho Horse; the only y sleet est 

i ve, end to end, with the superior laryngeal. In the whole of its 
ae ee to the cesophagus are more numerous and hye erage 
in Solipeds although they all have the same physiological office, except those that are 
derived from the branch of tle superior laryngeal, which are motor. : jefina, Ho 

“The differences remarked in the nerve in the abdominal cavity, are in relati 
the volume and form of the stomach and Be 5 et 

aie ee ee fate, the inferior esophageal nerve 
divides tuto raise principal branches: one passes to the left, ee ee ss oe 
a a a a cle feooof the paalrian, south te enbatonen 
a median, which is distributed to the an e of 1 ticceats aa finally 

é omasum, to which it sends some filaments, 
e ey meee eee nerves coming from a rich plexns that exists on ie 
Peeiseoe ace of the liver and gall-bladder ; it forms, conjointly with the divisions of the 


‘ ee lion; 5, Pharyngeal nerve; 6, External laryngeal; 7, Superior 
ues ae tana : 9, i. Gesophagesl branches of the pharyngeal and ex- 
<= ’ 5 
ternal laryngeal. 


50 


742 THE NERVES. 


solar plexus and superior csophageal nerve, a rich plexus, from which arise branches to 
the liver, abomasum, and duodenum. rn ; 

The superior esophageal nerve is chiefly distributed to the rumen. Before reaching 
the stomach, it gives several divisions to the plexus already mentioned—and which 
might be named the “hepatic plexus.” receives a large branch from the solar plexus, 
and sends to it a smaller one. It afterwards divides into two principal branches, the 
largest of which passes along the superior fissure of the rumen, along with the vessels of 
that organ. According to Lavocat, tlis branch forms a large plexus there, which has in 
its centre a ganglionic enlargement, whence emanate the ramuscules that go to the whole 
of the upper face, sides, and lower surface of the rum7n. In the Sheep we have not found 
a ganglion, but this does not prevent this branch from being distributed to all the parts 
indicated by Lavocat. ; 

The other branch is very large, and situated in the omentum until it arrives at its 
convex border, when it leaves it to be distributed to the left side of the abomasum; 
while the analogous nerve from the inferior cesuphageal passes more especially to the 
right face. 

© Seinal accessory.—T he origin of this nerve offers slight differences, which we have 
indicated in speaking of the motor roots of the pneumogastric. With regard to its dis- 
tribution in the Ox, it offers the following features: At the inferior extremity of the 
transverse process of the atlas it divides into two branches, a superior and inferior. The 
first is a little larger than the spinal accessory of the Horse, and comports itself as in 
that animal. The inferior branch is directed downward and backward, traverses the 
muscle we haye named the sterno-suboccipital, beneath a tendon that runs across the 
muscular fibres, and arrives between that muscle and the sterno-maxillaris. At this 
pint it separates into a certain number of ramuscules, the first three or four of which 
are slightly recurrent, and enter the upper part of the sterno-maxillaris ; the others are 
large and directed towards the sternum, to be distributed to the latter muscle, or to it and 
the sterno-suboccipitalis. 

These branches of the spinal accessory represent the branch which, in the Horse, passes 
exclusively to the sterno-maxillaris. In reflecting on the distribution they offer in the 
Oz, we are brought to the conclusion that the sternal band, which has been described as 
belonging to the first, forms, with the sterno-suboccipitalis, one and the same muscle— 
the analogue of the sterno-maxillaris or steino-mastoideus of Solipeds. These two 
muscular fasciculi are, otherwise, closely attached to each other, if not confounded near 
their origin at the anterior prolongation of the sternum. 

Lastly, the great hypoglossal nerve, before crossing the pneumogastric, communicates 
with the first ccrvical by a considerable branch; lower, it gives off a long ramuscule 
tl:at descends on the carotid artery. 

Pic.—We need not refer to the olfactory, optic, or motor nerve of the eye, neither to 
the glosso-pharyngeal, as what has been said about them in Solipeds holds good in this 

. animal, : 
| Trigeminal nerve—This also divides into three principal branches. The palpebro- 
nasal ramuscule of the ophthalmic branch anastomoses with a motor nerve of the eye on 
the deep face of the external rectus muscle. The superior mamillary nerve leaves the 
- cranium by the great sphenoidal slit, and immediately enters the superior dental foramen; 
_ its orbital course is therefore very short. 
its spheno-palatine branch passes at once below the alveolar tuberosity, where it 
‘divides into several ramuscules: one, entering the palatine fissure, forms the posterior 
pilatine nerve ; the otiiers pass into the palatine arch at various distances, to constitute 
the middle palatine nerves ; some of them even enter the palatine canal with the anterior 
_ palutine or palato-labial nerve. 

Facial.—Beneath the parotid gland, this divides into several branches, of which there 
are three principal. One is directed upwards, and passes in front of the ear; this is the 
smallest. The second proceeds forward, crosses the masseter near the zygomatic process, 
unites with the inferior branch, and is expended among the suborbital ramuscules of the 
superior maxillary. The third passes downward and forward, under the parotid gland, 
_ arrives in the intermaxillary space, is inflected in front of the masseter to become super- 
‘ficial, and terminates with the middle branch. Towards the maxillo-labialis muscle, 
this inferior branch gives off a ramuscule to the lower lip. 

Pnenmoyastric.—This joins the great sympathetic near the upper third of the neck, 
and at its point of union offers a greyish enlargement resembling the gangliform plexus 
of Man. Until the origin of the esophageal nerves, the pneumogastric of the Pig 
resembles that of the Horse. The Jatter is voluminous, and does not divide into two 
branches immediately beyond the bronchial plexus, but at some distance from it. 
“Numerous anastomoses exist between the two cesophageal nerves—superior and inferior, 


THE CRANIAL OR ENCEPHALIC NERVES. 743 


At their termination they differ much from each other in volume; the inferior is very 
swall, and terminates on the anterior face of the stomach; the superior, much larger, 


partly remains at the stomach, and partly crosses the small curvature of that viscus to 
enter the solar plexus. 


Spinal accessory.—This nerve commences and terminates as in Solipeds. After being 
inflected backward on the anterior border of the mastoido-humeralis, it divides into two 
ramuscules—a deep and superficial. The first is confounded with a cervical nerve, near 
tiie intervertebral foramen through which the later passes; the second goes to the 
trapezius muscle, in which it is expended. 


Near the base of the tongue, the hypoglossal gives off a filament that passes to the 
genio-hyvideus muscle. 

Carnivora.—In these animals, the majority of the cranial nerves do not offer any 
important differences. We will, therefore, say nothing concerning the first two pairs, 
the motores oculorum, spinal accessory, and glosso-pharyngeal, except that the motor 
nerves of the eye are mixed with the filament of the ophthalmic branch among the 
muscles of the orbit. 

Trigeminal nerve-—When the branch constituting the superficial temporal nerve 
reaches the posterior border of the maxilla, it divides into several ramuscules; one 
portion lies beside the middle branch of the facial, the other accompanies the anterior 
auricular nerve by becoming intimately united to it. We have also found, in the Dog, a 
branch that is detached from the inferior maxillary, almost immediately after its exit 
from the cranium ; it descends into the intermaxillary space, in company with the facial 
artery; at the posterior border of the mylo-hyoideus muscle it separates into two 
ramuscules: one is applied to that muscle, and follows it to near the symphysis of the 
jaw; the other is inflected outwards and upwards, in front of the masseter muscle, and 
Joins the inferior branch of the facial. Owing to this arrangement, each of the branches 
of the facial is provided with a sensitive ramuscule frum the fifth pair. 

Facial.—At its exit from the external auditory hiatus, it divides into four branches, 
three of which appear to form its termination. The first, the smallest, is directed down- 
wards across the parotid gland, and constitutes the cervical ramuscule. The other three 
are distinguished as superior, middle, and inferior. : 

The superior branch, the largest, ascends towards the forehead, and describes a curve 
whose convexity is upwards, turns round the orbit, and terminates near its nasal angle. 
In its course it furnishes: 1, An anterior auricular ramuscule; 2, Above the insertion of 
the masseter, several muscular filaments; 3, It is crossed, above the eye, by the super- 
ciliary filaments of the ophthalmic nerve. The middle branch accompanies Stenon’s duct 
to the surface of the cheek ; reaching the anterior border of the masseter, it anastomoses in 
a very flexuous manner with the ramuscule of the inferior branch, and terminates in the 
upper lip and the end of the nose. The inferior branch passes towards the ae 
fissure ; there it receives the sensitive ramuscule sent to it by the fifth pair, gives o 
filaments to the middle branch, and is then continued into the lower lip. ‘nae te Ol 

Pneumogastric.—The sensitive roots closely resemble, in their disposition, t east he 
Ox. The motor roots are separated into two series of filaments ; the et e ze : 
small ganglion, then pass into the jugular ganglion; the posterior He besi : 1e oo 
lary rot of the pil sensory, bu ve ta sit Ot a Peep Sere 

Below the foramen lacerum, the pneumogastr1 e Wile! leis Go belie 

ing the analogue of the plexiform ganglion of Man. This plexus , 
(eotee him, and - a cage eee re a mu oe Hd kane 
i mn. It is situated a little 1 
bility gloria. Whe eau es poe the superior laryngeal nerve, 

i i i ernal laryngea . mae z 

oes = es ame the shotsiecal nerve, its disposition being absolutely 

i s 
eae "Di ne ee laryngeal has a curious disposition. Lae ne moe Ae, to 
eax knowl ame been described. ‘Reaching the inner face of the thyroid cartilage, 1 site 
i 1 i to the glottis, epiglottis, base of the tongue, an 
off, as in the other animals, ee A aes ie ane Fyunle tie superion teryneeal ta 
Sl oat a Nee pone ith the inferior laryngeal ; it gives a large branch to the 
ete ies Ce ee ee to its surface, and then leaves the larynx to the inside 
Cae maine on Hie trachea as far as the entrance ioe ae ry that 
of the PeCUrrent: a i eal forms two divisions that com- 
cavity, the descending ae Pacis thet ae passing into this region. On the 
municate with the ont ait fon weeeined a voluminous branch from the inferior cervical 
right side, the Lee ca aeioon unite, and join the pneumogastric after it has turned 
pene beabial Wutls; a little behind the point of emergence of tha inferior Jary ngeal. 
roun i 


744 THE NERVES. 


On the left side the same arrangement is found ; the anastomoses are larger and more 
numerous than on the right side; the branch follows, in an inverse direction, the course 
pursued by the recurrent nerve, to join the pneumogastric at the part where the recurrent 
originates from the latter. } 

In this course, the branch gives large ramuscules to the oesophagus and trachea; 
those distributed to the former either pass along the muscular tunic and return again to 
the nerve, or continue along the surface of that tube. In all cases, there is found on the 
sides of the cesophagus a rich plexus formed by these filaments, as well as by those 
coming from the pharyngeal nerve. . ; 

This branch aie enters other peculiarities. Thus, it is very often found alongside the 
laryngeal nerve for some distance, and sometimes at several points. When this happens 
in the upper part, at the larynx, as occurs in many cases, it appears to have an anasto- 
mosis as in the Ox; but itis always easy to separate the two nerves, even in fresh 
specimens, and this separation is greatly facilitated if the piece has been steeped in 
water acidulated by nitric acid. : ; ; . ; 

In the cervical portion, the pneumogastric nerve is closely united to the sympathetic, 
the separation of the nerves being no longer possible as in the Horse and Ox. ‘ 

We have already described a portion of the inferior laryngeal nerve, in speakiny of 
the tracheo-csophageal branch of the superior laryngeal. Comparison with other 
animals requires that we should transfer the latter to the recurrent. In the Dog, the 
inferior laryngeal rises by two distinct branches, a short distance from each other, on the 
right and left sides; these may, or may not, lie together for some distance, but they never 
become fused. The external part of the nerve receives at intervals filaments proceeding 
from the superior laryngeal branch, and it rarely gives very fine twigs to the trachea 
and cesophagus. The communications with the cardiac and tracheal nerves are also 
chiefly made by the tracheo-cesophageal branch. 

The bronchial nerves are large and numerous. 4 : 

The cwsophageal plexus, which is furnished by the nerves of the same name, is larger 
-and finer than in the Horse. : 

There is nothing to note particularly in the termination of the nerves in the 
stomach. 

The hypoglossal gives a long branch that passes to the sides of the larynx, and enters 
the muscles on the anterior face of the trachea. 


COMPARISON OF THE CRANIAL NERVES OF MAN WITH THOSE OF ANIMALS. 


The few modifications offered by the cranial nerves of Man, when compared with 
those of animals, are dictated by the disposition of the parts and organs to which they 
are distributed. 

We have spoken of the olfactory lobes when studying the brain, so that we need not 
again refer to them. The three succeeding nerves offer nothing worthy of mention. 

Trigeminal nerve.—This has the same origin and divisions as in animals. 

The frontal nerve of the ophthalmic portion divides into two branches; these are 
inflected upwards on the margin of the orbit, and distributed to the skin of the forehead. 
These two branches, well developed in the Dog, are distinguished as internal and 
external. The latter anastomoses with a branch of the facial. The nasal nerve, after 
spreading over the surface of the turbinated bones and the meatus, gives otf a ramuscule 
.that becomes subcutaneous in passing between the inferior border of the nasal bone 
aud cartilage of the nostril; this is the naso-lobular nerve. 

The superior maxillary nerve leaves the cranium by the foramen rotundum, reaches 
the suborbital furrow, and spreads over the face by suborbital branches. Like that of 
animals, it gives rise to an orbital ramuscule, and posterior and anterior dental branches. 
Differences appear in the other branches which are furnished, in animals, by the 
superior maxillary nerve: in Man these branches leave Meckel’s ganglion. The fila- 
ments leaving this ganglion are: 1, The pharyngeal nerve of Bock which is distributed in 
the upper portion of the mucous membrane of the pharynx, in that of the Eustachian 
tube and the posterior orifice of the nasal cavities; 2; The palatine nerves—great or 
anterior—sent to the mucous membrane of the anterior portion of the palate; middle 
palatine, distributed to that of the soft palate, and posterior palatine, that goes to the two 
faces of the soft palate and its muscles; 3, The nasal or spheno-palatine nerve. 

The inferior maxillary nerve closely resembles that of animals, the only differences 
consisting in: 1, The deep middle temporal nerve rising direct from the maxillary; 
2, The Jmgual nerve is detached near the base of the cranium; 3, The superficial 
temporal nerve furnishes, independently of the filaments uniting it to the facial, un 


THE CRANIAL OR ENCEPHALIC NERVES. 745: 


auriculo-temporal branch that ascends in front of the ear, and terminates in the skin of 
the temporal region. 

In Man, there is annexed to the fifth pair the submazillary ganglion, which receives 
a sensitive branch from the lingual, a motor filament from the chorda tympani, and 
sympathetic filaments ; it gives off several emergent filaments, nearly all of which pass 
into the maxillary gland. ‘There is nothing to say of the internal motores oculorum. 

Facial.—In_ its collateral branches, the facial nerve of Man is absolutely the same as 
in animals. It has, however, a branch not described in them—the ramuscule of 


Fig. 344. 


Ati | i 7 i 


NERVES OF THE FACE AND SCALP, 

1, Attrahens aurem muscle; 2, Anterior belly of occipito-frontalis; 3, Auriculo- 

* temporal nerve; 4, Temporal branches of facial; 5, Attolens aurem muscle; 6, 
Supra-trochlear (5th); 7, Posterior belly of occipito-frontalis ; 8, Supra-orbital ; 
9; Retrahens aurem muscle; 10, Temporal branch of temporo-orbital ; 11, Small 
occipital ; 12, Malar branches of facial; 13, Posterior auricular (7th); 14, Malar 
branch of temporo-malar (5); 15, Great occipital ; 16, Infra-orbital branches of 
facial; 17, Facial; 18, Nasal; 19, Cervico-facial division of 7th ; 20, Infra- 
orbital; 21, Branches of digastric and stylo-hyoid ; 22, Temporo-facial division of 
7th; 23, Great auricular; 24, Buccal branches of facial; 25, Trapezius muscle ; 
26, Buccinator (5th); 27, Splenius capitis; 28, Masseter ; 29, Sterno-mastoideus ; 
30, Supermaxillary branches of facial nerve; 31, Superficial cervical; 32, 
Mental; 33, Platysma muscle; 34, Submaxillary branches of facial nerve. 


D 
a 


Bs 


1 ich reaches the base of the tongue, where it is distributed by mixing 
al ig nee ea The termination much resembles that of the Dog. Two 
principal branches have been named the temporo-factal and the cervico-facial, The 
first receives the superficial temporal nerve, and describes an arch from which are 
detached the temporal, frontal, palpebral, suborbital, and buccal ramuscules, which 
form the subparotideal plexus. The second, lodged in the parotid, passes towards the 
angle of the jaw, where it ey ane nag with the cervical plexus; it furnishes the inferior 

ical branches. 
ee ie nerve commences and terminates as in Solipeds, and has the 
same ee It furnishes the branches of the digastric and stylo-hyotd muscles, the 


746 


THE NERVES. 


DISTRIBUTION OF THE EIGHTH PAIR OF NERVES ON LEFT SIDE. 


1, Gasserian ganglion of 5th nerve; 2, Internal carotid artery; 3, Pharyngeal 
branch of pneumogastric; 4, Glosso-pharyngeal nerve; 5, Lingual nerve; 6, 
Spinal accessory; 7, Middle constrictor of pharynx; 8, Jugular (internal) vein, 
cut; 9, Superior laryngeal nerve; 10, Ganglion of trunk of pneumogastric; 11, 
Hypoglossal nerve on hyoglossus; 12, Ditto communicating with 8th and Ist 
cervical nerve; 13, External laryngeal nerve; 14, Second, cervical looping with 
the first, 15, Pharyngeal plexus or inferior constrictor; 16, Superior cervical 
ganglion of sympathetic; 17, Superior cardiac nerve of pneumogastric; 18, 
Third cervical nerve; 19, Thyroid body; 20, Fourth cervical nerve; 21, 21, 
Left. recurrent laryngeal nerve; 22, Spinal accessory communicating with 
cervical nerves; 23, Trachea; 24, Middle cervical ganglion of sympathetic; 25, 
Middle cardiac nerve of pneumogastric; 26, Phrenic nerve (cut); 27, Left 
carotid artery; 28, Brachial plexus; 29, Phrenic nerve (cut); 30, Inferior 
cervical ganglion of sympathetic; 31, Pulmonary plexus of pneumogastric; 32, 
[horacic aorta 33, (sophageal plexus; 34, Vena azygos superior; 35, Vena 
azygos minor , 30, Gangliated cord of sympathetic. 


THE SPINAL NERVES. 747 


filament of the stylo-glossus muscle, and, finally, the tonsilitic ramuscules that form, around 
the amygdala, the tonsilar plexus. ( 

Pneumogastric.—Formed by the union of the sensitive roots, the pneumogastric leaves 
the cranial cavity by the posterior foramen lacerum; in the interior of that foramen it 
shows the jugular ganglion; a little lower, it has a second fusiform enlargemeut, the 
qangliform pleaus, which is found in the Dog. Here it receives tle internal branch of 
the spinal accessory, or otherwise its motor roots. Beyond this gangliform enlargement, 
the pneumogastric is placed a little within the sympathetic, descends along the neck 
enters the chest, and terminates on the stomach and in the solar plexus. The relations 
of the two pneumogastrics in the thoracic cavity are the same as in animals. In 
terminating in the semilunar ginglion, the two pncumogastrics unite and form an arch 
named the memorable loop of Wrisberg 

The various anastomoses of the pneumogastric in Man offer nothing particular. 

The pharyngeal branches leave the gangliform plexus, and are constituted by the 
filaments carried to the pneumoyastric by the internal root of the spinal accessory. They 
are two, three, or four in number, and form the pharyngcal plexus. 

The superior laryngeal nerve also arises from the gangliform plexus, and offers, as in 
Ruminants, a Galieu branch that anastomoses, end to end, wilh a branch of the inferior 
laryngeal. The external laryngeal is furnished by this nerve; it is distributed to the 
inferior constrictor muscle of the pharynx, the crico-thyroid muscle, and the mucous 
membrane of the subglottic portion of the larynx and the ventricle of the glottis. 

The recurrent nerves affect a distribution analogous to that already made known. 

The pneumogastric also gives cardiac, pulmonary, aud csophageal branches. The 
cardiac lie beside those coming from the sympathetic and recurrents, and enter the 
ganglion of Wrisberg, situated at the base of the heart. The cesophageal branches are 
remarkable for their number and complexity, and form a veritable cesophageal plexus. 
The gastric branches are also very numerous. ; 

Spinal accessory.—It presents bulbous roots which are well known, and medullary roots 
which usually extend to the fifth cervical, and sometimes to the first dorsal. After its exit 
from the posterior foramen lacerum, it divides into two branches—an internal aud external. 
The internal branch, formed by the bulbous roots, enters the gangliform plexus of the 
pneumogastric, The external branch comports iteelf as in animals. 

The hypoglossal resembles that of Carnivora, and, like it, possesses a bianch for the 
hyo-thyroideus and genio-hyoideus. 


CHAPTER II. 


SPINAL NERVES. 


We designate as spinal, vertebral, or rachidian nerves, those which emanate 
from the spinal cord, and leave the vertebral canal by the intervertebral 
foramina to proceed to the various organs. 

They are estimated at 42 or 48 pairs, and are apportioned as follows in 
the five regions of the spine: cervical, 8 pairs ; dorsal, 17 pairs ; lumbar, 6 
pairs; sacral, 5 pairs; and coccygeal, 6 to 7 pairs. ; 

They differ from the encephalic nerves in closely resembling each other 
in the fundamental points of their constitution. All proceed from the lateral 
aspects of the spinal cord by two orders of roots: one motor, the other 
sensitive (Fig. 817). In all, these two roots unite in a very short trunk 
in passing through the intervertebral foramen ; and this trunk divides almost 
immediately into two terminal branches : a superior, destined to the spinal 
muscles and tHe integuments covering them; the other, inferior, passes to 
the lateral and lower parts of the trunk or to the members. All send, from 
their inferior branch, one or more ramuscules to form the great sympathetic. 

The roots of the spinal nerves offer everywhere the same disposition ; 
each nerve is formed by two fasciculi of converging filaments, superior and 
inferior, which are naturally more numerous and large when they belong to 


748 THE NERVES. 


voluminous trunks, as may be remarked in those proceeding from the two 
enlargements (or bulbs) of the spinal cord. The common axis of these two 
fasciculi affects a transverse direction in nearly all the spinal pairs; but 
that of the posterior nerves inclines more backwards as they reach the 
terminal extremity of the cord. 

The filaments of the superior fasciculi, or sensitive roots, are larger than 
the others, and emerge from the collateral sulcus of the spinal cord. They 
may be followed to the cells of the superior grey cornua. 

“The filaments of the inferior fasciculi, or motor roots, arise opposite 
to the preceding, on the lower face of the cord, at a short distance from the 
middle line, and on the limits of the inferior and Jateral columns. They may 
also be traced to the interior of the cord, as far as the inferior grey cornua. 

These filaments do not unite to form their common trunk until after 
they have passed through the dura mater; this is an extremely short trunk 
that occupies the corresponding intervertebral foramen, and presents on its 
upper face a ganglionic enlargement, which is exclusively placed on the 
course of its sensitive fibres; the motor filaments being simply laid 
beside them, and do not mix with them until beyond 
the ganglion. Immediately after this union, a small 
filament is given off that enters the spinal canal to 
be distributed to the sinuses and the vertebra. F 

After leaving the meningeal sheath, the radicular 
fasciculi of the nerves furnished by the terminal ex- 
tremity of the spinal cord, run a somewhat long 
course in the sacral canal, before finally uniting and 
passing into the tissues ; the common fasciculus they 
collectively form at the posterior extremity of the 
spinal canal is named the cauda equina. 

The distributive branches of the spinal nerves 
cannot be considered in a general manner, because of 
their diversity. We will study them successively in 
each region of the spine. 


Fig. 346. 


Article I—Crrvican Nerves (8 Pairs). 


Superior Brancues.—The first passes through 
GANGHION OF A SPINAL the superior foramen of the atlas, in company with 
NERVE FROM THE LUM- : . : . 
BAR REGION or 4 the cerebro-spinal artery. It arrives in the inter- 
PUPPY. stice between the small oblique muscle of the head 
du, Superior root; 8, In- and the posterior straight muscles, and divides imme- 
ferior root; c, Ganglion diately into several divergent branches which are 
a ee el oa pete distributed to the three above-named muscles, the 
fibres from the inferior ®terior extremity of the great complexus, and the 
and superior roots with Cervico- and temporo-auricular muscles. The ramus- 
P wv Pp eos 
those coming from the cule sent to the latter ascends within the concha, and 
ganglion. d, Superior breaks up into several filaments that supply the skin 
trunk of spinal nerve: of the external ear. 
e, Its inferior trunk. i x 
The second immediately furnishes some ramus- 
cules to the great cblique muscle, beneath which it is placed, as well as to 
the small oblique. It is afterwards directed backwards, comporting itself 
like the succeeding ones. 
These diminish in volume from the third to the eighth. All pass 
through the intertransversales-colli muscles, and divide into several 


THE CERVICAL NERVES. 749 


branches, which are distributed to ‘the muscles and integuments of the 
superior cervical region. Among these, the superficial, which are almost 
rudimentary in the two last pairs, reach the inner face of the splenius. The 
others, deep and more voluminous, cross the semispinalis colli, and, dividing, 
ascend between the great complexus and cervical ligament, to near the 
superior border of that large elastic lamina. They generally intercommuni- 
cate by several filaments, and in this way form a network on the inner face 
of the great complexus, which Girard named the deep cervical plecus. 
Inrertor Brancues.—These branches augment in size from the first to 
the last, and separate into two perfectly distinct groups. The divisions of 
the first six cover the lateral and anterior parts of the neck, as well as the 
muscles of the breast. Usually anastomosing with each other by long 
communicating branches, they in this way form a vast nervous network 
traversed by two important nerves—the spinal accessory and cervical 
filament of the facial ; this is the superficial cervical plecus. The other two 
are united with the preceding by a filament passing between the sixth and 
seventh, soon becoming confounded with each other, as well as with the 
two first branches of the dorsal region ; they constitute, in common with the 
latter, the brachial plexus. 
Without saying any more as to the disposition of this double plexus, we 
will pass to the particular description of each cervical pair of nerves. 
First.—Deeply situated beneath the transverse process of the atlas, this 
nerve leaves the anterior foramen of that vertebra, and accompanies the 
occipital artery and vein to place itself immediately between the anterior 
small rectus capitis and rectus lateralis muscles. It then crosses the anterior 
great rectus capitis andthe spinal accessory nerve, which it separates; and 
arrives, after describing a slight curve forward, near the thyroid gland, 
finally entering the subscapulo-hyoideus by several terminal divisions. 
Near its origin, this inferior branch of the first cervical nerve furnishes 
collateral ramuscules to the three recti muscles. Lower, it is in communica- 
tion with the superior cervical ganglion and the spinal accessory nerve by 
several filaments. At the carotid artery, it sends forwards, to the side of 
the larynx, a very fine branch that quickly divides into two ramuscules, one 
of which joins the great hypoglossal nerve, and the other goes to the thyro- 
hyoid muscle. It then throws off, from its convex side, several small descend- 
ing nerves, all of which are destined to the subscapulo-hyoid, sterno-hyoid, 
and thyroid muscles. _ 
One of these filaments, joined by a ramuscule from the second pair, is 
distinguished for its great length; it may be followed to near the sternum, 
where it is expended in the fleshy mass common to the four muscles that 
extend from that bone to the larynx and os hyoides. Its constant disposition 
should obtain for it the name of precervical nerve. 
Second.—This descends beneath the great oblique muscle (obliquus 
posticus), crossing the direction of the rectus anticus major. and ramifying 
therein by numerous branches. We specially indicate: 1, Those furnished 
to the latter muscle, and which are the shortest and deepest; 2, The atloid 
loop, a long, thick superficial branch, which enters the anterior portion of 
the levator humeri, and is directed forward and upward on the parotid 
gland, bending round the transverse process of the atlas: this ramuscule 
gives off filaments to the parotido-auricularis, as well as to the subcutaneous 
muscle of the face, and terminates in two branches of unequal volume, the 
largest of which ascends on the outer side of the concha, and the other, 
situated behind, reaches the cervico-auricular muscles ; 3, Another superficial - 


750 THE NERVES. 


branch, which passes over the jugular, near the junction of the glosso-facial, 
and divides into two ramuscules; these proceed forward with the glosso- 
facial vein to the intermaxillary space, where they are distributed to the 
skin and subcutaneous muscle; 4, Anastomosing filaments, which unite it 
to the two branches of the spinal nerve; 5, Accessory ramuscules to the 
cervical filament of the facial nerve; 6, Two communicating branches 
which pass beneath the rectus anticus major: one going to the first, the other 
to the third pair of nerves; 7, A deep branch going to join the precervical 
filament of the first pair, and directly throwing off some fine divisions to the 
subscapulo-hyoid muscle; 8, A last branch that arises at the intervertebral 
foramen, and passes at first, with the vertebral artery, into the trachelian 
(posterior) foramen of the second vertebra, and afterwards those of the 
succeeding vertebre, to enter the inferior cervical ganglion of the great 
sympathetic nerve, receiving on its course filaments from the 3rd, 4th, 5th, 
6th, and 7th pairs. 

Third, fourth, fifth, and siath—Each of these crosses the intertrans- 
versales colli by a different interstice to that through which the corresponding 
superior branch passes. They gain the inner face of the levator humeri, 
where they divide into deep and superficial ramifications. 

The first are distributed to the deep muscles of the sides and anterior 
part of the neck and shoulders. Among them ought to be distinguished 
those which form a communication between the four pairs, and the third 
with the second. Very long and thin, these filaments lie on the side of the 
large muscular column formed in front of the cervical stalk by the rectus 
anticus, longus colli, and scalenus muscles, where they form sometimes arches, 
and at other times anastomoses by convergence. Those of the fifth and sixth 
pairs, uniting at the anterior border of the scalenus with a branch of the 
brachial plexus, constitute the diaphragmatic nerve, which will be noticed 
hereafter. 

The superficial ramuscules gain the external surface of the levator 
humeri by traversing its substance, or passing between its two portions. 
Much more numerous and larger than the preceding, they are distributed, 
in front, to the subcutaneous muscle of the neck, behind, to the trapezius, or 
below, to the levator humeri and superficial pectoral. Those passing to the last 
two muscles are very long and voluminous; they represent the acromial and 
clavicular branches of the cervical pleaus of Man. It may be remarked that 
the posterior filaments generally communicate with the spinal accessory, 
while the anterior ones, in meeting the cervical branch of the facial nerve 
on the jugular, often give it some anastomosing fibres. 

Seventh.An enormous branch comes from the interstice between the 
two portions of the scalenus, to pass entirely into the brachial plexus. It 
usually receives an anastomosing twig from the diaphragmatic filament 
furnished by the sixth pair. 

Lighth.—This is thicker than the preceding, and comports itself like it. 
It directly furnishes its anastomotic branch to the inferior cervical ganglion. 


Articte IJ.—Dorsat Nerves (17 Pairs). 


These nerves, numbering seventeen pairs, comport themselves in an 
extremely simple and almost identical manner; so that their description is 
not nearly so complicated as that of the nerves of the cervical region. 

Superior Brancues.—They present two principal ramuscules destined 
to the spinal muscles, and to the skin of the dorso-lumbar region, One 


THE LUMBAR NERVES. 751 


ascends towards the summit of the spinous processes of the dorsal 
vertebra, by passing between the semispinalis and longissimus dorsi; 
the other is directed outwards, in traversing the substance of the latter muscle. 

Inrerior Brancuus.—These are more considerable in size than the 
preceding, and descend into the intercostal spaces, between the pleura and 
the internal intercostal muscles, or even in the texture of these. With the 
exception of the first, whose arrangement is different, they all pass at first 
over the head of the posterior rib to reach the convex border of the anterior 
one, and follow it to the extremity of the intercostal space. 

_ There they terminate in the following manner: those of the sternal 
ribs traverse the pectoral muscles, giving filaments to these, and are 
expended in the skin of the subthoracic region. Those of the asternal 
ribs enter the abdominal muscles, passing between the transversalis and 
rectus abdominis ; they also give cutaneous filaments to the skin of the belly. 

Near their origin, the inferior branches communicate with the great 
sympathetic, for the most part, by several filaments. 

In their course they furnish numerous fine ramuscules to the intercostal 
muscles, and, in addition, give off, about the middle of their length, a very 
thick division—the perforating intercostal branch, which traverses the costal 
muscles and descends beneath the panniculus carnosus, ramifying partly in 
that muscle and partly in the skin. The most anterior perforating branches 
alae anastomose with the subcutaneous thoracic branch of the brachial 
plexus. 

With regard to the first dorsal pair, its inferior branch enters the latter 
plexus ; but it nevertheless furnishes an intercostal branch, always extremely 
slender, which passes over the external intercostal muscle to be expended 
in its substance before arriving at the sternum. The second pair also concurs 
in the formation of the brachial plexus, though only by a small branch. 


Arricie II1.—Lumsar Nerves (6 Pairs). 


Superior Brancues.—Destined to the spinal muscles and the integu- 
ments of the loins and croup, these are larger than the corresponding 
branches of the dorsal region, and present an analogous disposition ; they 
give superior ramuscules to the muscles of the spine, and very long external 
divisions which pass through these muscles to be distributed to the skin of 
the croup. 

Inrerror Branones.—The first, comprised in the interval separating the 
last rib from the first lumbar transverse process, between the quadratus 
Jumborum and the psoas magnus, passes downwards and backwards until it gets 
between the transverse and internal oblique muscles of the abdomen, to which 
it gives filaments, and is finally distributed in the great rectus muscle. 

Above the superior border of the internal oblique muscle, it furnishes a 
perforating branch to the skin of the flank and the posterior part of the 
panniculus carnosus. 

The second, disposed in the same manner as the preceding, follows an 
analogous course, and breaks up into several divisions which are lost in 
the small oblique muscle. From one of these sometimes emanates a slender 
filament, which joins one of the inguinal nerves of the third pair. We 
must not overlook, in the enumeration of the branches emitted by this 
second pair of lumbar nerves, the two perforating branches which descend 
in front, and on the inside, of the thigh, to be distributed to the skin of the 
flank and the internal crural region. 


752 THE NERVES. 


The third, also passes outwards, above the psoas muscles, which receive 
from it several divisions, and ramifies in the muscles of the flank. It has 
also perforating nerves, destined to the inguinal region, and these comport 
themselves in a sufficiently interesting manner to merit particular mention. 
They are usually three in number: an internal and two external inguinal 
nerves. The three pass at first beneath the peritoneum, and are directed 
backwards, downwards, and outwards, towards the inguinal canal, which 
they enter, one to the inside, the other to the outside of the spermatic 
cord. They give off some filaments to the cremaster and‘ abdominal 
muscles, and at last ramify in the envelopes of the testicle, the sheath, 
and the skin of the inguinal region. The two external nerves are often 
confounded in a single trunk on their arrival at the cremaster muscle. The 
disposition they affect at their origin is extremely variable; sometimes they 
have each a distinct commencement, and separately traverse either the small 
or large psoas muscle, or the space between these ; and, at other times, the 
internal and one of the external inguinal nerves proceed from a common 
trunk at the intervertebral foramen, the second external nerve then arising 
alone towards the external border of the great psoas muscle. Most frequently, 
the internal nerve receives a branch from the fourth pair, and itis even 
sometimes entirely formed by that branch. This variation in arrangement 
is not, however, the exclusive appanage of the inguinal nerves; we have 
seen the third pair only supply these three nerves and the filaments of the 
psoas muscles, without being prolonged into the muscles of the flank. 

The fourth? pierces the small psoas muscle, and enters the space separating 
it from its congener—the great psoas. After passing between the peritoneum 
and the lumbo-iliac aponeurosis, it arrives below the angle of the haunch, 
and makes its exit from the abdomen ; it then descends within, and in front 
of, the fascia lata muscle, and accompanying the divisions of the circumflex 
iliac artery, it is prolonged to the stifle, where it is expended in the skin. 
At its origin, it abandons: 1, A thick, short branch to the great psoas 
muscle; 2, A large anastomosing branch which concurs in the formation of 
the lumbo-sacral plexus; 8, A filament that joins the internal inguinal 
nerve furnished by the third pair. We have already mentioned that this 
nerve sometimes emanates entirely from the fourth pair. 

The fifth and sixth, much more voluminous than the preceding, unite, 
and, with the three first sacral pairs, form the nervous plexus of the 
abdominal limb. 

All the inferior lumbar branches communicate with the great sympathetic 
by several filaments, which pass across the fasciculi of the small psoas muscle ; 
and all communicate with each other: the two last by fusion of their fibres, 
and the first five by means of more or less voluminous anastomotic branches 
which are far from being constant. 


Articte IV.—Saceat Nerves (5 Pairs). 


We describe, as sacral nerves, not only the four double cords which 
escape by the lateral foramina of the os sacrum, but also the nerve that 
passes through the intervertebral foramen between that bone and the last 
lumbar vertebra. 

Superior Brancuzs.—These are small ramuscules that pass through the 


? Representing the abdomino-genital and femoro-genital branches of Man. 
® The femoro-cutaneous branch of the lumbar plexus of Man. 


THE COMPOSITE NERVES. 753 


supersacral foramen, reach the muscles lodged on the sides of the sacral 
spine, and terminate in the skin of the croup. 

Ivrerion Brancuss.—Thick nervous trunks, which diminish in volume 
from the first to the fifth, and leave the sacral canal to pass downwards and 
backwards on the sides of the pelvic cavity. 

The first, second, and third are directed towards the great ischiatic opening, 
and are united into a wide nervous band that constitutes the pelvic portion 
of the lumbo-sacral plexus, to be described at another time. 

The fourth and fifth course along the side of the pelvic cavity, in the 
texture of the sacro-sciatic ligament, or even within it; united at their 
base by an anastomosing filament, they do not usually communicate in a 
direct manner with the fasciculus formed by the three first pairs. 

The fourth constitutes the internal pudic nerve, which passes between the 
two roots of the corpora cavernosa in bending round the ischial arch, where 
it lies nearly alongside its fellow of the opposite side. This nerve after- 
wards descends on the dorsal border of the penis in the midst of the magni- 
ficent venous plexus of that organ, describing flexuosities which allow it to 
adapt itself to the elongation of the penis. Arriving at the extremity of the 
organ, it terminates in numerous divisions in the proper erectile tissue of 
this part, or in the mucous membrane covering it. On its course it emits 
very long flexuous branches, whose ultimate ramifications enter the corpora 
cavernosa, or go to the urethral canal ; before leaving the pelvis, it gives off, be- 
hind, two thin ramuscules destined to the muscles and skin of the perineo-anal 
region. These ramuscules, like the principal trunk, receive anastomotic fila- 
ments from one of the ischio-muscular branches of the lumbo-sacral plexus. 

The fifth is the anal or hemorrhoidal nerve. It passes backward, above 
the preceding, and is distributed to the sphincter muscle and the surround. 
ing integuments. Before quitting the pelvis, it gives a ramuscule to the 
levator ani. 

The five inferior sacral branches emit, near their origin, a more or less 
slender filament that proceeds to the pelvic or hypogastric plexus. The 
anastomotic divisions, through which they communicate with the sympathetic 
chain, are generally thick, short, and multiple. 


Articie V.—Covcrezat Nervszs (6 to 7 Pairs). 


In the coccygeal region are found two pairs of nerves, one placed 
beneath the depressor muscle of the tail, the other below the lateral 
sacro-coccygeal muscle. These two nerves extend to the extremity of the 
tail, throwing off on their track some muscular and cutaneous filaments. 
They are formed by the superior and inferior branches of the coccygeal 
nerves, which gradually amalgamate to form the two trunks. ee 

These coccygeal branches are six or seven in number, and very distinct ; 
they diminish in volume from the first to the last. The first only gives a 
slender filament for the formation of each coccygeal trunk ; it is chiefly 
expended in the integuments and muscles at the base of the tail. 


Articte VI.—ComrosiTE Nerves FORMED BY THE INFERIOR BRANCHES OF 
cue SpinaL NERVES. 


Jready know that these nerves represent three groups : 1, The 
aorta ae ; 2, The brachial plexus; 38, The lumbo-sacral plexus. 
They will be studied in this order. 


iets 


754 THE NERVES. 


DIAPHRAGMATIC (OR PHRENIC) NERVE. 


The diaphragmatic nerve (the internal respiratory nerve of Bell) is formed 
by two principal branches, and a small accessory ramuscule whose presence 
is not constant. The latter comes from the fifth cervical pair; the two 
others proceed, one from the next pair, the other from the brachial plexus. 
The branch from the sixth pair pierces the inferior scalenus muscle from 
within to without, gives off a filament to the brachial plexus, and descends 
obliquely backwards to the surface of the muscle it passes through, to unite, 
at the entrance to the chest, with the branch of that plexus. This latter 
branch, generally shorter and thicker, comes exclusively from the seventh 
cervical pair. A 

The trunk of the diaphragmatic nerve, formed in this manner, after 
receiving the branch of the fifth pair—when it exists, passes within the 
axillary artery, along with the pneumogastric nerve, and often at this point, 
though not always, obtains a filament from the great sympathetic. It then 
gains the side of the base of the heart, passing beneath the pleura, and 
finally attains the phrenic centre, after a course of at least eight inches 
between the two lamin of the posterior mediastinum—the left nerve being 
in the proper mediastinum, while that of the right side lies in the serous 
septum intended for the posterior vena cava. 

Even before its arrival at the aponeurotic centre, this nerve divides into 
several branches, whose ramifications pass to the sides of the pillars of the 
muscle. 


BRACHIAL PLEXUS. 


This plexus comprises an enormous fasciculus of nerves, situated between 
the thoracic parietes and the inner face of the anterior member, formed by 
the inferior branches of the sixth, seventh and eighth cervical, and the two 
first dorsal pairs, and principally destined to the muscles and integuments 
of that limb. 

Mode of constitution—The sixth cervical pair only assists in the forma- _ 
tion of this plexus by the slender filament from its diaphragmatic branch; 
but the next two are entirely devoted to it, as well as the first dorsal, with 
the exception of a very thin ramuscule, which constitutes the first intercostal 
nerve. The root furnished by the second dorsal pair only represents a very 
small part of its inferior branch, the other portion forming a somewhat 
voluminous intercostal nerve. 

The various branches converge towards each other, and gain the interstice 
between the two portions of the scalenus muscle (if we consider it as one), 
where they unite, and become confounded into a single fasciculus by sending 
filaments and ramuscules to each other, this fasciculus soon separates into 
a certain number of divisions, whose disposition will be referred to presently. 
It will be remarked that the intercrossing of the branches composing the 
brachial plexus does not occur in a confused and irregular fashion, and 
if the reticulation of the ramuscules passing from one to another does not 
take place in a constant manner, it is, at any rate, far from being inextricable. 
It is easy to follow the filaments from any pair of nerves for a certain 
distance in the divisions given off by the brachial plexus, especially after 
maceration in dilute nitric acid. This originating fasciculus of the brachial 
plexus is very wide and short. It is at first comprised between the superior 
portion of the scalenus (or superior scalenus) and the longus colli. In 
passing between the two portions of that muscle, it bends round the first rib 


THE BRACHIAL PLEXUS. 155 


by, its posterior border, and corresponds inwardly to the vertebral artery and 
vein, as well as to the nervous vertebral filament proceeding to the sym pathetic 
and accompanying these vessels. , 
Mode of distribution. Immediately after leaving the interspace in the 
scalenus, the brachial plexus arrives beneath the shoulder, near the scapulo- 
humeral angle. There it divides into a certain number of branches cons eae 
which it is impossible to distinguish the terminal divisions and nollageral 
ramuscules. Without noticing this d'stinction, however, we will describe 
them in succession, commencing with those that pass to the trunk, and after- 
wards those which are destined fur the limb. The latter will be examined 
in the following order: first, the shortest, or those which proceed to the 
upper parts of the member, and uext, the longest branches, or those passing 
to the foot. 
All these divisions are named and classified in the following enumera- 
tion : 
1. Diaphragmatic branches. 
2. Angulares and rhomboideal branch. 
3. Serratus magnus or superior thoracic branch, 
4. Pectoral or inferior thoracic branches. 
5. Subcutaneous thoracic branch. 
6. Latissimus dorst or great dorsal branch. 
7 
8 
9 
10 


. Axillary nerve. 
. Adductor brachii or teres major branches. 
. Subscapular branches. 
. Superscapular nerve. 
11. Anterior brachial or musculo-cutaneous nerve. 
12. Radial nerve. 
18. Ulnar or cubito-cutaneous nerve. 
14, Median or cubito-plantar nerve. 


PRFPARATION OF THE BRACHIAL PLexvs.—The animal is placed in the first position, and 
slightly inclined to one side by allowing one of the anterior limbs to hang un- 
restrained. The pectoral muscles are then excised close to their insertion in the unfixed 
limb, and turned upwards, maintaining them in this position by the chain tentacula 
which are detached superiorly to a band that unites the extremities of the two 
suspensory diagonal bars. Care should be taken to separate the pectoralis magnus from 
the panniculis, in allowing the latter to fall on the table along with the limb. By tear- 
ing through the considerable mass of cellular tissue surrounding the nerves of the 
brachial plexus, these soon appear, and may be isolated with the greatest facility. It is 
advisable in this dissection to preserve the arteries; and it is also of importance to lave 
the perforating intercostal branches intact, in order to observe the anastomoses of these 
with the subcutaneous thoracic division. 

In this operation, the auterior limb is very much separated from the trunk, and the 
relations of the nerves are necessarily more or less changed; but it exhibits the whole of 
the plexus in the most perfect manner. : ’ 

To trace the divisions of the principal nerves from this plexus, a limb entirely 
removed from the body is made use of, and, if possible, with the arteries injected. The 
nerves are then found in their natural relations, and can be more readily dissected. 
Figures 347, 348 will guide the student in looking for these nervous divisions. 


1. Diaphragmatic Branches. 
See the description of the diaphragmatic nerve above. 


2. The Angularis and Rhomboideal Branch. (Fig. 347, 7.) 


Entirely furnished by the sixth cervical pair, this branch is directed 


upwards to the surface of the angularis (anterior portion of the serratus 


756 THE NERVES. 


magnus). It soon divides into several filaments, which are wholly expended 
in the substance of that muscle, the serratus magnus, and the rhomboideus, 
The filament supplying the Jatter is slender and very long, and, to reach its 
destination, passes through the angularis. 


3. Serratus Magnus, or Superior Thoracic Branch. (Fig. 347, 8.) 


This very remarkable branch proceeds by two principal portions from 
the fasciculus common to all the divisions of the brachial plexus: one 
emanating from the sixth cervical pair; the other from the seventh, and 
always traversing the last fasciculus of the scalenus before joining the first. 
The single branch resulting from the union of these two roots is thin and 
very wide. It passes back to the surface of the serratus magnus, crossing 
the direction of its fibres, and is expended in its substance, sending regularly- 
arranged ramifications upwards and downwards. 

This is the respiratory nerve of Bell. 


4. Pectoral or Inferior Thoracic Branches. 


Five principal are distinguished : 

1. One emanating from the sixth and seventh cervical pairs, particularly 
the former, and passing to the internal face of the sterno-prescapularis (or 
pectoralis), to ramify exclusively among its fibres, after dividing into two 
branches: an anterior, short and thick, and a posterior, long and slender 
(Fig. 347, 10). . 

2. A second branch, arising from the anterior brachial and cubito-plantar, 
or median nerves, by two roots, which join in forming an arch beneath the 
maxillary artery. 

It passes between the two portions of the deep pectoral muscle, and 
terminates in the superficial one, after furnishing some ramuscules to the 
pectoralis magnus by means of a long thin filament which is carried back 
to the external surface of that muscle (Fig. 347, 11). 

8. The other three, destined to the pectoralis magnus, generally come 
from the trunk that constitutes the subcutaneous thoracic branch. Com- 
prised between the serratus magnus, and pectoralis magnus, they are 
directed downward and backward, and enter the latter muscle. One of them, 
longer and thicker than the other, follows the course of the spur vein. 


5 Subcutaneous Thoracic Branch. (Fig. 347, 9.) 


This is a very remarkable nerve, arising from the brachial plexus by a 
trunk common toitand the ulnar nerve. Placed at first to the inside of that 
nerve, it soon leaves it to pass backward to the internal face of the caput 
magnum and the panniculus carnosus. In its long course, it acts as a 
satellite to the spur vein, above which it is situated. It may be followed 
to the flank, where its terminal divisions are lost in the substance of the 
subcutaneous muscle. Those it gives off are also destined to that muscle; 
they anastomose with the majority of the perforating intercostal nerves, 
forming an elaborate network on the inner face of the panniculus. 

One of its branches, along with a voluminous perforating nerve, 
bends round the inferior border of the latissimus dorsi, and passes forward 
to enter the scapulo-humeral portion of the subcutaneous muscle, 


THE BRACHIAL PLEXUS. 


Fig. 347. 


NERVES OF THE BRACHIAL PLEXUS. 


157 


1, Diaphragmatic branch of 
the sixth cervical pair, 
furnishing a branch to 
the brachial plexus; 2, 
Seventh cervical pair; 3, 
Eighth cervical pair; 4, 
First dorsal pair; 5, 
Second dorsal pair; 6, 
Great dorsal branch; 7, 
Angularis and rhomboid- 
eal branch; 8, Superior 
thoracic branch; 9, Sub- 
cutaneous thoracic branch, 
giving rise, near its origin, 
to the three inferior tho- 
racic branches; 12, Nerve 
of the adductor of the 
arm; 13, Axillary nerve ; 
14, Subscapular nerves; 
15, Superscapular nerve ; 
16, Radial nerve; 17, 
Anterior brachial nerve; 
18, Ulnar nerve; 19, Its 
internal cutaneous branch ; 
20, Median nerve; 21, 
Its antibrachial musculo- 
cutaneous branch ; 22, 22, 
22, Superficial ramuscules 


of that branch.—a, Humeral artery ; B, Posterior radial artery. 
51 


758 THE NERVES. 


6. Great Dorsal Branch. (Fig. 347, 6.) 


Formed of fibres, the larger portion of which come from the eighth 
cervical pair, this branch proceeds backwards and upwards to the internal 
face of the latissimus dorsi, and is soon expended in that muscle. It is long 
and thick. 


7. Awillary or Circumflex Nerve. (Fig. 847, 13.) 


Somewhat considerable in volume, this nerve is furnished directly by the 
eighth cervical pair. It passes backward and downward on the internal 
face of the subscapularis muscle, to the interstice between it and the adductor 
of the arm, where it crosses the subscapular artery. It proceeds behind 
the scapulo-humeral articulation, along with the circumflex artery, enters 
between the short abductor of the arm and the caput magnum and mediun, 
and arriving beneath the abductor brachii, it divides into several diverging 
branches, destined to the two abductors, the levator humeri, and-even to the 
integuments covering the anterior region of the arm. 

Before entering the space that lodges the subscapular artery, it sends 
filaments to the teres internus. 


8. Nerve of the Adductor of the Arm or Teres Major. (Vig. 347, 12.) 


This arises from the eighth cervical pair, like the preceding, by the 
same trunk, and passes backward, at first on the subscapularis muscle, 
then the adductor, in the substance of which it disappears by numerous 
filaments. © 


- 9. Subscapular Branches. (Fig. 347, 14.) 


These branches are two in number, and are generally derived from the 
trunk of the seventh pair. After a short course backwards, they divide 
into several ramuscules which pass among the fibres of the subscapularis 
muscle. 


10. Superscapular Nerve. (Fig. 347, 15). 


Very short and thick, this nerve is formed by the sixth and seventh 
cervical pairs. After a brief course backwards, between the angularis on 
the one side, and the pectoralis prescapularis and superspinatus on the 
other, it gains the space between the latter muscle and the subscapularis, 
and enters it a little above the super- or prescapular artery. It is then 
carried to the external face of the scapula, after bending round the anterior 
border of that bone, passes across the acromion spine, and ascends to the 
subspinous fossa, to expend itself in the muscle occupying this space. Onits 
passage beneath the superspinatus, it gives off several ramuscules to that 
muscle. 


11. Anterior Brachial or Musculo-cutaneous Nerve. (Fig. 847, 17.) 


This nerve proceeds from the seventh and eighth cervical pairs, descends 
to the internal face of the scapulo-humeral articulation, and meets the 
axillary artery, which it crosses outwardly, at an acute angle. It then 
joins the median nerve by a large short branch, that passes beneath the 
artery and forms a loop around it; descending in front of the median 
nerve, to the bifurcation of the coraco-humeralis, it insinuates itself between 
the two branches of that muscle, and breaking up into several ascending 


THE BRACHIAL PLEXUS, 


and descending _ramuscules, 
enters the substance of the 
coraco-radialis, It also fur- 
nishes filaments to the coraco- 
humeralis, before its passage 
between the two branches of 
that muscle. Besides this, it 
concurs, by a small branch, in 
the formation of one of the 
anterior thoracic nerves, 


12. Radial Nerve. (Figs. 347, 
16; 348, 3.) 


This is certainly the largest 
nerve furnished by the brachial 
plexus. It arises chiefly from 
the first dorsal pair, and is 
directed backwards and down- 
wards, on the inner face of the 
subscapularis and adductor mus- 
cle of the arm, whose direction 
it crosses. In this portion of its 
course, it proceeds parallel to 
the humeral artery, from which 
it is separated by the ulnar 
nerve. Arriving at the deep 
humeral artery, which it leaves 
on the outside, it passes behind 
the humerus with the divisions 
of that artery, and enters be- 
tween the large extensor and 
short flexor of the fore-arm. 
After creeping along the pos- 
terior border of the latter 
muscle, it gains the anterior 
face of the ulnar and radial ar- 
ticulations, where it is covered 
by the two principal extensors 
of the metacarpus and the pha- 
langes, and meeting the radial 
artery, accompanies it on to the 
oblique extensor of the meta- 
carpus. There it terminates by 
two branches which enter the 
texture of that muscle. 


1, Subscapular nerve; 2, Axil- 
lary nerve; 3, Radial nerve; 4, 
Superficial ramuscule of the 
musculo-cutaneous nerve; 95, 
Ulnar nerve; 6, Its terminal 
cutaneous branch.—a, Anterior 
radial artery. 


Fig. 348. 


EXTERNAL NERVES OF THE ANTERIOR LIMB. 


759 


760 THE NERVES 


In its course, it successively gives off: 

1. Before leaving the internal face of the limb, to pass beneath the mass 
of extensor muscles of the fore-arm, a very thick fasciculus, composed of 
several branches—descending and ascending. The latter bend round the 
terminal tendon common to the latissimus dorsi and teres internus, to 
become lost in the body of the great extensor; the others reach either the 
long and middle extensors, or the inferior portion of the principal muscle— 
the large extensor. 

2. Behind the arm, filaments to the short and small extensors of the 
fore-arm, and several cutaneous ramuscules, disengaged from beneath the 
short extensor, that descend beneath the skin on the anterior face of that 

art. 
: 3. In the antibrachial region, branches to the anterior extensor and 
external flexor of the metacarpus, and the two extensors of the digit. + 

In brief, we see that the radial nerve animates the whole mass of the 
extensor muscles of the fore-arm and foot, besides a flexor of the latter, and 
that it endows the integument of the anterior antibrachial region with 
sensibility. 


13. Ulnar, or Cubito-cutaneous Nerve. (Figs. 847, 18; 348, 5.) 


Chiefly formed by fibres from the dorsal pairs, this nerve, less consider- 
able in volume than the preceding, proceeds backward and downward, and 
places itself behind the humeral artery, which it accompanies to below the 
origin of the deep humeral. After crossing the latter vessel, it passes 
between the long and middle extensors of the fore-arm, and gains the inner 
side of the elbow, running over the epicondyle, below the ulnar band of 
the oblique flexor of the metacarpus. It follows the posterior border of that 
muscle to near the supercarpal or pisiform bone, where it terminates by 
two branches. In the latter part of its course, it lies beneath the anti- 
brachial aponeurosis, accompanied by a division of the epicondyloid 
artery. 

One of the two branches, the cutaneous (Fig. 348, 6), crosses the space 
between the terminal tendons of the external and oblique flexor muscles of 
the metacarpus, as well as the antibrachial aponeurosis, to spread itself in 
several ascending horizontal and descending filaments, beneath the skin of the 
fore-arm, the anterior face of the knee, and the external side of the cannon. 
The other branch, with a ramuscule from the median nerve, constitutes the 
external plantar nerve. 

In its course, the ulnar nerve gives off two fasciculi of collateral branches. 
The first (Fig. 347,19) is detached from the principal trunk a little above 
the epicondyloid artery, and passes backward and downward between the 
long extensor of the fore-arm and the pectoralis transversus, supplying some 
filaments to the latter, and traverses it to become subcutaneous, and to be 
distributed to the skin of the fore-arm, beneath the elbow. The second 
arises at the epicondyle, and is destined to all the muscles of the posterior 


antibrachial region, except the external and internal flexors of the 
metacarpus. 


14. Median, or Cubito-plantar Nerve. (Fig. 847, 20.) 


This nerve is composed of fibres coming from the dorsal and eighth 
cervical pairs. It is detached from the posterior part of the trunk of the 
plexus to proceed to the axillary artery, where it forms an anastomosis with 


THE BRACHIAL PLEXUS. 761 


the anterior brachial nerve, through the loop already noticed when deseribin 
that nerve as being formed by filaments passing from one cord to the other. 

Leaving this point, it is placed in front of the humeral artery, and 
accompanies it to its terminal bifurcation ; then it continues to descend on 
the inner face of the limb, along with the principal branch of that artery— 
the posterior radial—until it reaches the ulnar articulation, where it responds 
to the internal ligament of that joint, and where it crosses, at a very 
acute angle, the direction of its satellite vessel to become posterior, This 
position it inverts below the articulation, when it assumes, and preserves for 
the greatest part of its extent, its antibrachial course, remaining always a 
little more superficial than the artery. Above the lower third of the fore- 
arm, it bifurcates to form the plantar nerves. 

In its course, this nerve successively furnishes : 

1. Before its arrival on the axillary artery, one of the originating 
branches of the thoracic nerve destined to the superficial pectoral muscle. 

2. At the middle of the humerus, a long branch, represented in Man by 
that portion of the musculo-cutaneous nerve which proceeds to the anterior 
brachial muscle and the skin of the fore-arm. This branch enters beneath 
the coraco-radialis or biceps, and forms two divisions; one of which is 
expended in the short flexor of the fore-arm; while the other passes 
between that muscle and its congener, the long flexor, to become superficial 
and gain the internal aspect of the limb, when it breaks up into two 
principal filaments, which pass to the external face of the antibrachial 
aponeurosis, and accompany with their divisions the two subcutaneous 
veins of the fore-arm to below the carpal region (Fig. 347, 21, 22). 

3. In the antibrachial region, and at various elevations, but particularly 
below the ulnar articulation, ramifications to the internal flexor of the 
metacarpus and the two flexors of the phalanges. a 

Puantar Nerves.—These nerves, two in number, are distinguished as 
internal and external. 

The internal plantar nerve, one of the terminal branches of the median 
nerve, lies beside the collateral artery of the cannon, and follows that vessel 
along the perforans tendon to near the fetlock, where it ends in several 
digital branches. In its track it furnishes a number of cutaneous metacarpal 
ramuscules, and an anastomosing branch, which, after being detached from the 
principal trunk, about the middle of the cannon, bends obliquely behind the 
flexor tendons to join the external plantar nerve. This is formed by the 
union of two branches: one coming from the ulnar nerve, the other from 
the median, and joining the first at the upper border of the pisiform bone, 
after passing beneath the inferior extremity of the oblique flexor of the 
metacarpus. This nerve, which accompanies the external collateral vein of 
the cannon for its entire length, descends with it, and with an arteriole that 
concurs in forming the subcarpal arch, outside the flexor tendons, in a 
special fibrous channel of the carpal sheath. Near the superior extremity of 
the cannon, within the head of the external metacarpal bone, it sends on 
the posterior face of the suspensory ligament of the fetlock a deep plantar 
branch, chiefly destined to the fleshy portion of the interosseous muscles. 
It is the analogue of the deep palmar branch of the ulnar nerve in Man. 
Continuing its descending course along the perforans tendon, it throws off 
some superficial metacarpal ramuscules, receives the accessory branch 
supplied by the internal nerve, and terminates, like the latter, ina a aloes 
of digital branches on arriving at the fetlock; these it now remains for us 


to examine. : 


762 THE NERVES. 


The digital branches, or collaterals of the digit, and the terminal branches 
of the plantar nerves, are three in number on each side, and accompany the 
digital artery and vein, which, at some points, they cover with their divisions, 


NERVES OF THE DIGIT, 


P, Plantar nerve; B, Median branch; c, Anterior branch; D, Digital artery; H, 
Inconstant division given off to the cartilaginous bulbs; 1, 1, Branch to the 
plantar cushion; K, Transverse coronary branch; M, Podophyllous branch; 0, 
Preplantar branch; Q, Descending ramuscule to the fissure of the patilobes; R, 
Ramuscules accompanying the digital artery in the plantar fissure; v, Vein 
whose presence is not constant, and which sometimes accompanies the plantar 
nerve throughout its phalangeal course. 


THE BRACHIAL PLEXUS. 763 


They separate from one another nearly at the insertion of the Suspensory 
ligament into the sesamoid bones. One of them descends in front of the 
vein; another passes between the two vessels; while the third follows the 
artery behind. They may, therefore, be distinguished, according to their 
position, into anterior, middle, and posterior (Fig. 849, m, 0, R). 

The anterior branch distributes its collateral divisions to the skin on the 
anterior face of the digit, and its terminal ramuscules in the coronary 
cushion. 

The middle branch frequently anastomoses with the other two, par. 
ticularly with the anterior, and to such a degree as to be scarcely dis- 
tinguished from it; it enters the coronary cushion and the podophyllous 
tissue. 

The posterior branch, much more considerable than the preceding, and a 
veritable continuation of the plantar nerve, is at first superposed on the 
digital artery, then it is placed immediately behind that vessel. It descends 
with it to near the basilar process of the third phalanx, follows the pre- 
plantar ungueal artery into the lateral fissure of that phalanx, and, like that 
vessel, expends itself in the midst of the podophyllous tissue, as well as in the 
osseous structure. This branch gives off numerous ramuscules on its course. 
Of these there may be more particularly noticed: 1, Some posterior 
divisions, distributed behind the flexor tendons, especially at the fetlock ; 
2, A satellite branch to the artery of the plantar cushion; 3, A filament 
arising below the lateral cartilage, passing forward, in proximity to the 
anterior branch of the arterial coronary circle, and becoming lost in the 
meshes of the deep venous network of the cartilage; 4, A small podo- 
phyllous division, whose point of origin is placed at the same height as the 
preceding filament, but opposite it, and which descends on the retrossal 
process, where it traverses the cartilaginous tissue to pass to the podo- 
phyllous reticulation, after distributing posterior ramuscules to the plantar 
cushion ; 5, Several extremely fine filaments enlaced around the plantar 
ungueal artery, and with it penetrating to the interior of the os pedis; some 
of these filaments ascend to the nerve of the opposite side.! 


DIFFERENTIAL CHARACTERS IN THE BRACHIAL PLEXUS OF OTHER THAN SOLIPED ANIMALS, 


in the domesticated mammals, the nerves of the brachial plexus do not offer any very 
important differences in the upper part of the limb; these only become apparent in its 
last section. 

Ruminants.—The branches of the plexus, the same in number as in the Horse, are 
relatively more voluminous than in that animal. In the Ow they are often flexuous in 
their upper part. In the Sheep, we have found that the diaphragmatic nerve is formed 
by ‘a single filament, detached from the branch the sixth cervical nerve gives to the 
brachial plexus. There are no differences to signalise in the branch of the angularis and 
rhombotdeus, in the branches of the pectoral muscles, the subcutaneous thoracic branch, 
or the anterior brachial or musculo-cutaneous nerve. 


1 Jt is because we conform to established usages, and are unwilling to force analogies, 
that we preserve the designations of “plantar nerves,” and “ digital branches,” as well 
as the above manner of describing them. Comparative anatomy desires other names and 
a different description ; for it demonstrates that the external plantar nerve corresponds 
to the interosseous of the first space in pentadactylous animals; the internal plantar to 
the interosseous of the third space, and the branch extending from the internal to the 
external plantar, to the interosseous of the second space, and which only virtually exists 
in the Horse, in consequence of the fusion of the second and third metacarpal bone, and 
which is prolonged to the phalanges. It also shows that the digital branches are the 
exact representatives of the collaterals of the digits which result, in the pentadactylous 
species, from a bifurcation of cach interosseous nerve. 


764 THE NERVES. 


, the serratus magnus does not show the branch which, in the Horse, 
ge nerve ond one through the scalenus; but on the surtace of the 
serratus magnus it receives a filament from the branch of the angularis. The latter is 

at g 2 
ixth. : 
ee the great dorsal muscle and the axillary nerve are confounded at their 
origin, and also adhere to one of the two branches of the subscapularis nerve: The 
i=} ? 


Fig. 350. 


i y ) i j i 
Lh h 


NERVES OF THE DIGITAL REGION OF RUMINANTS; POSTERIOR FACE. 

M, Internal plantar nerve, a continuation of the median ; ©, Internal plantar nerve, 
a continuation of the ulnar; 1, Branch of the plantar, furnishing, 2, the internal 
collateral nerve of the internal digit ; 3, Branch giving off the internal collaterals 
of the digits; 1’, Branch of the internal plantar that joins the external plantar ; 
4, External collateral of the external digit, 


second branch of the latter is free throughout, and distributed in the muscle of the same 
name, along with some filaments furnished by the superscapularis. 
The radial nerve, when it reaches the teres major, divides into three branches: one is 


THE BRACHIAL PLEXUS. 765 
buried in the long extensor of the fore-arm ; the other traverses the middle extensor; 
and the third is inflected on the tendon of the great dorsal muscle, and passes between 
the middle and large extensor of the fore-arm. When the radial nerve turns outwards 
around the arm, and is placed between the anterior brachial and the mass of the 
olecranian muscles, it furnishes: 1, Muscular branches that pass immediately beneath 
the extensors of the metacarpus and phalonges; 2, A sensitive branch that leaves this 
muscular interstice to become subcutaneous. This cutaneous branch of the radial gains 
the inner face of the fore-arm, and divides in two branches that descend parallel to the 
median subcutaneous vein. One of these is lost around the carpus; the other is placed 
a little in front of the metacarpus, and reaches the metacarpo-phalangeal articulation, 
where it terminates by two principal filaments that constitute the dorsal collaterals of the 
digits; there is a third which crosses the interdigital to anastomose with the palmar 
collaterals. 

The ulnar and median nerve of Ruminants lie beside each other, as far as the middle 
of the arm. This double cord is situated at the surface of the humeral artery ; at the 
carpus te a nerves offer the same distribution as in the Horse, but beyond this there 
are some differences. 

The ulnar does not receive a branch from the median at the carpus, and it forms the 
external plantar nerve or interosseous palmar of the first space, placed at the external 
border of the flexor tendons. This nerve is reinforced by a filament detached from the 
external plantar, that joins it a little above the fetlock-joint ; it gives ramuscules to the 
ergot, and is then continued by the external collateral nerve of the outer digit, into the 

my claw. : 
ie The median is continued by the internal plantar, or interosseous palmar of the third 
space. Towards the inferior third of the metacarpus, it divides into three branches: the 
third passes to the external plantar; the second proceeds to the interdigital space, where 
it bifurcates to form the internal collateral palmar nerves of the external digit, and eaternal 
collateral of the internal digit; the third gives some filaments to the ergot, and passes 
along the digital region, where it constitutes the internal collateral of the internal digit. 

Pic.—Three fasciculi are Seine so ne pete me the posterior is the 

inous, and furnishes the radial, median, and cubital. : 
Se eee of the plexus that pass to the trunk and the first rays of the anterior 
limb much resemble those of Ruminants; the branch of the serratus magnus is remarkable 

i ngth and size. ; 
= oes nerve is disposed like that of Solipeds and Ruminants. as far as the carpus ; 
from this point it passes beneath the flexor tendons of the phalanges, gives filaments to 
the interosseous palmar muscles, and at the two rudimentary digits divides into four 
branches: the two upper are the smallest, and form the collaterals of the rudimentary 
digits; the inferior two are the ee eM — reach the principal interdigital space, 

ing collaterals of the two great digits. 

‘orn wate gives off, towards the middle of the arm, a branch that passes to the Ly 
at the ulna it furnishes several muscular branches. The nerve then bends aa : 
outside of the fore-arm, and on arriving above the pisiform bone, bifurcates: one branc 

: d d is continued by the collateral of the 
goes along the outer border of the flexor tendons, an ry oA 
external digit; the other is placed Se ripe eer koe Lek metacarpus, and also 

i i xternal digits their dorsal collatera h : ; 

Sea ne anes four last cervical and first dorsal compose the ig oe Beye in Ls 
Carnivora; the fifth cervical gives an insignificant filament. as t e plexus is un- 
ravelled, its principal branches are observed to send fibres to each other. i 5 te di 

The number of the distributive eae is the hgh ren beget mn a aie 

ition of the superior branches is so analogous as } ; 
ae desnuihe the enericr brachial. radial, median and cubital ugle Kiev dtented 

The anterior brachial, or apseip ouisreene is haeeolap Die ce a ee 
cervical and the more voluminous branches coming space Be OREN oe ees 
the axiilary artery, this cord arrives at the een ss sean rater Peer 
bifurcates: one of the branches passes forward to t e ve A A a 
the anterior border of the humeral artery, and terminates y g ged Rodent 

i ied i i ial muscle, and by a very fine filament that become: 
pe deca ee ers ae on the sunte border of the fore-arm to be lost 
aubsttancous ab He : The anterior brachial is, therefore, in these animals, a 
ee ae branch uniting it to the median nerve is situated a little 
Hal pig Barty cat humerus, instead of being beneath the axillary artery, as in 
Benet: i ag, is exclusively formed by the eighth cervical ; it receives 
ee te ieee and azillary nerve, and gives branches to these three, 


766 


THE NERVES. 


When it reaches the interstice of the triceps and anterior brachial, it crosses the limb 
above the outer face of the elbow, and divides into two series of terminal branches. 


Fig. 351. 


NERVES OF THE PALMAR FACE; DOG. 

A, Trunk of the median dividing into six 
branches; Bl, Branch of the superficial 
nervous arch; B2, Branch disappearing on 
a vessel; B3, B4, Branches uniting with 
the corresponding ramuscules of the ulnar ; 
B5, Branch forming the internal collateral 


of the index; 36, Rudimentary branch 
passing to the thumb; ¢, Collateral given 
off by the median; cl, 2, c3, c4, Colla- 
terals furnished by the median and ulnar. 
—a, Palmar branch of the ulnar; 6, Super- 
ficial branch giving off a filament to the 
hypothenar, and a second that forms the 
superficial nervous arch; 01, Deep branch 
passing to the muscles of the skin; m, Not 
anastomosing with the median; m1, m2, 
Anastomosing with the corresponding branch 
of the median; the innermost passes to the 
muscles of the thumb; ¢, ¢, ¢, Collaterals 
furnished by the ulnar 


in the internal and middle lobe of the large cushion of the paw. 


The muscular branch enters beneath 
the muscles on the anterior face of the fore- 
arm. The cutaneous bifurcates imme- 
diately: the smallest branch, passing in- 
wards, extends beyond the bend of the 
elbow, lies at the inner border of the median 
subcutaneous vein, und is distributed to the 
lower moiety of the fore-arm, the thumb, 
and internal border of the index digit. The 
largest lies at the outer side of the median 
subcutaneous vein; it sends a recurrent 
ramuscule to the bend of the elbow, and, at 
the elbow, detaches three filaments to the 
first, second, and third dorsal intermeta- 
carpal spaces; these filaments bifurcate at 
the dorsum of the digits to constitute the col- 
lateral dorsal nerves. The first metacarpal 
nerve anastomoses, by a fine transverse 
branch, with the ulnar ramuscule that 
constitutes the external dorsal collateral of 
the small digit. 

To resume: the radial of the Dog gives 
branches to the dorsal fuce of all the digits, 
except the external border of the first digit, 
or auricularis. 

In the Cat, there are some differences. 
The internal branch of the radial sometimes 
lies with the external branch ; it is placed 
at the inner border of the metacarpus, gives 
off a filament to the dorsal face uf the thumb, 
and afterwards forms the internal dorsal 
collateral nerve of the index. The external 
branch leaves the anterior face of the carpus, 
and is situated at the origin of the third 
interosseous space, where it divides in‘o 
three metacarpal branches; the external of 
these is very fine, and directed obliquely 
outwards, anastomosing with the dorsal 
branch of the ulnar, between the first and 
second digits. 

The median of the Dog is united to the 
ulnar as far as the lower fourth of the arm; 
it is situated behind the humeral artery, 
and the filament it receives from the mus- 
culo-cutaneous joins it at a short distance 
from the elbow-joint. Placed beside the 
radial artery, the median is, towards the 
lower third of the fore-arm, immediately 
below the posterior border of the great pal- 
mar tendon; it afterwards passes through 
the carpal sheath, giving a branch that 
constitutes the internal -palmar collaterals 
of the thumb, and external cf the index; it 
finally forms three branches, the first of 
which apvastomoses with the ulnar, at the 
surface of the palmar arch, and is lost on 
an artery; the other two, receiving a fila- 
ment from the ulnar at the origin of the 
digits, bifurcate to form the internal palmar 
collateral of the annularis, and collaterals of 
the medius and index. The second gives, 
in addition, a slender branch, that is lost 
In fine, the median of 


THE BRACHIAL PLEXUS. 767 


tie Doe ae branches to all the digits, except the auricularis and external border 
ris. 

In the Cat, the median traverses the bony canal at the lower extremity of the 
humerus, and separates below the carpal arch into three branches. ‘The internal 
branch _is destined to the rudimentary thumb, and the internal palmar border of 
the index. The middle branch descends in the third interosseous space, furnishes a 
filament to the large cushion of the paw, 
and divides to form the external palmar Fig. 352, 
collaterals of the index and internal of the 
medius. Finally, the external branch is 
placed in the second intermetacarpal space, 
and gives the following palmar collaterals : 
the external of the medius and internal of 
the annularis. 

The ulnar nerve of the Dog, below the 
elbow, lies beside the ulnar artery to the 
lower third of that vessel; there it forms 
two branches—a dorsal and palmar. The 
dorsal branch becomes subcutaneous, passes 
along the external border of the fore-arm, 
metacarpus, and small digit, and con- 
stitutes the external dorsal collateral nerve 
of the latter. 

The palmar branch leaves the carpal 
sheath, gives off, at the trapezoides, a ramus- 
cule that passes to the surface of the palmar 
muscles to form the external collateral pal- 
mar of the auricularis, and then, at the 
surface of the deep palmar arch, divides into 
eight terminal ramuscules. The smallest 
of these is expended in the rudimentary 
muscles of the thumb, the small digit, and 
interosseous muscles; the largest, three in 
number, lie on the interosseous arteries, and 
bifurcate. at the digits to form the palmar 
collaterals; the two internal ramuscules are 
previously confounded with the correspond- 
ing branches of the median. From this 
arrangement, it results that the ulnar nerve 
supplies the palmar surface of all the digits, 
except the internal yond of He ea 

The ulnar of the Cat also divides into a 
a dorsal and a palmar branch, but the dis- RERVES: OF THE BAUS E naan sean 
tribution of these is not the same asin the 4, Trunk of the median dividing into two 
Doe. branches; 3B, Internal branch, giving a 

The dorsal branch bifurcates at the car-  Tudimentary filament to the thumb; 81, 
pus: oneof the filaments forms the external External branch, receiving a filament, i 
dorsal collateral of the small digit; the om the ulnar; ¢, c, c, c, Collaterals fur- 
other reaches the first interosscous space, ished by the median.—a, Palmar branch 
receives a branch from the radial, and after- of the ulnar dividing into three branches ; 
wards gives off the internal dorsal collateral b, Internal branch, detaching ibe filament, 
of the small digit, and external of the f, to the median ; 61, External branch ; 62, 
sarieulati: Deep et c, ¢, e, Collaterals furnished 

The palmar branch does not extend to by the ulnar. 
all the digits asin the Dog. Passing within LAA 
the pisiform bone, it divides into several filaments; some of these are distributed to the 
muscles of the small digit and thumb; another follows the external border of the emall 
digit, and constitutes its external palmar collateral; one of the longest is lodged in the 
first intermetacarpal space, giving a filament to the large cushion of the paw, ani 
the internal palmar collaterals of the small digit and external of the annularis. 


COMPARISON OF THE BRACHIAL PLEXUS OF MAN WITH THAT OF ANIMALS. 


The brachial plexus of Man, like that of the Dog, is constituted by the anterior 
branches of the four last cervical, and the Jast dorsal nerves. The few variations observed 


768 THE NERVE. 


are very slight, and are to be ascribed to the difference in form of the regions to which 
the nerves are distributed. ; 

The shoulder of Man being short, and the other rays of the limb long and well 
detached, the branches of the brachial plexus can be divided into collateral and terminal. 

The collateral branches are: 1, The subclavian branch, which is not found in our 
animals, they having no subclavian muscle; 2, The nerve of the angularés ; 3, Nerve of 
the rhomboideus ; 4, Superseapular nerve ; 5, The serratus magnus ( posterior thoracic) 
nerve; 6, Subscapular, which is divided at its origin into two branches as in the Sheep 
and Carnivora ; 7, The nerves of the great and small pectorals (anterior thoracic); 8, The 


Fig. 353. 


THE NERVES OF THE AXILLA OF MAN, 


1, Scalenus medius; 2, Scalenus anticus ; 3, Cord formed by 5th and 6th cervical 
nerves; 4, Seventh cervical nerve ; 5, Superscapular nerve ; 6, Subclavian artery, 
cut; 7, Insertion of subclavius; 8, Cord formed by 8th cervical and 1st dorsal 
nerves ; 9, Pectoralis major, reflected; 10, Internal anterior thoracic nerve; 12, 
Origin of subclavius; 13, Pectoralis minor, reflected; 14, Internal cutaneous 
nerve; 15, Axillary artery, cut; 16, Posterior thoracic nerve, 17, Musculo- 
cutaneous nerve; 18, Origin of pectoralis minor; 19, Median nerve; 20, Nerve 
of Wrisberg; 21, Coraco-brachialis; 22, Intercosto-humeral nerve; 23, Ulnar 
nerve; 24, Subscapularis; 25, Brachial artery; 26, Lateral cutaneous branch of 
3rd intercostal nerve; 27, Middle subscapular nerve; 28, Short subscapular 
nerve; 29, Pectoralis major, cut; 31, Basilic vein; 32, Serratus magnus; 33, 
Latissimus dorsi. 


accessory nerve of the internal cutaneous, represented in quadrupeds by the subcutaneous 
thoracic ; 9, The nerve of the great dorsal ; 10, The nerve of the teres major. 

The terminal branches go to the arm, fore-arm, and hand. They are: 

1. The internal cutaneous, which in the Horse is furnished by the ulnar nerve. It 
becomes subcutaneous at the upper third of the arm, and a little above the elbow bifur- 
cates; the anterior is spread on the fiont face of the arm to the wrist; the posterior 


THE BRACHIAL PLEXUS. 769 


passes backwards, and is expended in the skin of 
the back, and inner part of the fore-arm. 

2. The musculo-cutaneous or perforans casserti, 
whose disposition is analogous to that of Carnivora. 

3. The avillary nerve, regarding which there is 
nothing to say. 

4. The radial nerve (musculo-spiral) passes as in 
animals, lies in the twisted furrow of the humerus, 
gives off an internal and external cutaneous branch, 
and reaches the antero-external part of the arm, in 
the space between the anterior brachial and long 
supinator, where it terminates by two branches. 
The anterior of these reaches the back of the hand, 
and gives off three ramuscules there, which are dis- 
tributed as follows: the first forms the external 
dorsal collateral of the thumb; the second bifur- 
cates, and constitutes the internal dorsal collateral 
of the thumb and external collateral of the index; 
lastly, the third supplies the internal collateral of 
the index and external of the medius. This branch 
always anastomoses with the dorsal branch of the 
ulnar. The posterior branch, motor, is expended in 
the muscles on the posterior and external aspect of 
the fore-arm. = 

5. The median nerve commences by two branches: 
one arises in common with the musculo-cutaneous 
or anterior brachial, and corresponds to the anasto- 
mosis found around the axillary artery of the Horse; 
the other is detached from the trunk common to the 
ulnar and internal cutaneous. The median rung 
along the biceps, passes in front of the elbow, and 
lies beneath the annular ligament of the carpus, 
where it terminates in furnishing: 1, A filament to 
the short abductor of the thumb; 2, Palmar ramus- 
cules to the thumb, index, and medius, and external 
border of the annularis. This disposition of the 
medius, therefore, much resembles that of the Cat. 

6. The ulnar nerve passes along the inner border 
of the arm and fore-arm, and divides, a little above 
the inferior extremity of the olecranon, into two 
terminal branches—a dorsal and palmar. The first 
is directed on the back of the hand, and separates 
into three metacarpal branches, which, in their course, 
furnish the dorsal collaterals of the auricularis and 
annularis, and internal collateral of the medius; the 
other parts of the hand are supplied by the radial. 
The second, or palmar branch, is superficial, and 
detaches the palmar collaterals of the little finger 
and internal collateral of the annularis, as well as 
a deep ramuscule that lies across the interosseous 
muscles, and isa motor nerve. To resume, we see 
that this distribution of the terminal branches of 
the brachial plexus of Man much resembles that 
described in Carnivora, and especially in the Cat. 


NERVES OF THE FRONT OF FORE- 
ARM AND HAND OF MAN. 


1, Supinator longus, cut; 2, Ulnar 
nerve; 3, Brachialis anticus; 4, 
Biceps; 5, Musculo-spiral nerve , 
6, Median nerve, 7, Posterior 
interosseous nerve, 8, Pronator 
teres and flexor carpi radialis, cut ; 
9, Extensor carpi radialis longior, 


cut; 10, Brachial artery; 11, Supinator brevis; 12, Flexor sublimis digitorum, cut ; 
13, 13, Radial nerve; 14, 14, Flexor carpi ulnaris; 15, Extensor carpi radialis brevior , 
16, Ulnar artery; 17, Radial origin of flexor sublimis digitorum, cut; 18, Flexor pro- 
fundus digitorum; 19, Tendon of pronator teres; 20, 20, Dorsal branch of ulnar 
nerve; 21, 21, Radial artery ; 22, 22, Deep branch of ulnar nerve; 23, Flexor longus 
pollicis; 24, Abductor minimi digiti; 25, Anterior interosseous nerve; 26, Digital 
branches of ulnar nerve; 27, Tendon of supinator longus; 28, One of the lumbricales 
muscles; 29, Pronator quadratus; 31, Tendon of flexor carpi ‘radialis; 33, Digital 


branches of median nerve; 35, Adductor pollicis, 


, 


770 THE NERVES. 


LUMBO-SACRAL PLEXUS. 


The last two lumbar pairs, and the three first sacral, in becoming fused 
together, form the lumbo-sacral plexus, which corresponds in every respect, 
by its constitution, as well as by its mode of distribution, to the plexus of 
the thoracic limb. 

It is usual, in human anatomy, to describe a lumbar and a sacral plexus, 
each formed by the inferior branches of all the spinal pairs, whose names 
they bear. In our opinion, this proceeding has two inconveniences: at first, 
if separates into two fasciculi the nerves of the abdominal member, and, 
besides, in including in the description of these nerves the first lumbar pair 
and the last sacral, elements are introduced in this description which are 
altogether foreign to it. It may be remarked, that the four first lumbar 
pairs, when they apastomose with each other, only do so by very slender 
filaments; that they only send some subcutaneous filaments to the posterior 
limb; that the two last sacral branches, principally destined to the genito- 
urinary organs and the posterior extremity of the digestive tube, are 
ordinarily without any direct communication with the others; that the two 
last lumbar pairs and the three first sacral are alone fused in the same manner 
as the brachial pleaus, and comport themselves like that plewus in the distribution 
of their branches, 

It is with some reason, then, that we have described, in a special manner, 
the inferior branches of the four lumbar pairs and the two last sacral, 
reserving the fasciculus formed by the five intermediate pairs for a special 
description, under the name of the lwmbo-sacral plexus. 

Mode of constitution.—In glancing at this plexus, we may perceive that 
it is divided into two portions—an anterior and posterior, each having a 
thick trunk in the centre. 

‘The first of these trunks is formed by the two above-named lumbar pairs, 
which join each other after a short course, and after receiving an accessory 
branch from the fourth pair. The second, wider and thinner than the 
preceding, comprises the fibres of the three sacral pairs which escape from 
beneath the subsacral vessels, and unite in a single fasciculus. These two 
trunks are connected with each other by one or two branches proceeding 
from the first sacral pair to the obturator nerve—one of the distributive 
branches of the first. 

Relations.—The anterior portion of the lumbo-sacral plexus is concealed 
beneath the small psoas muscle, and separated by the internal iliac artery 
from the posterior portion. The latter, placed above and on the side of the 
pelvis, at the great sciatic opening, corresponds, inwardly, to the subsacral 
vessels; outwardly, and in front, to the gluteal vessels. 

Mode of distribution—The anterior portion of the plexus at first gives off 
several small branches to the psoas muscle, and particularly to the iliacus: 
these branches were designated by Girard the ‘iliaco-muscular nerves; it 
then terminates in two large branches—the crural and obturator nerves. The 
posterior portion is continued by two important trunks, the great and small 
femoro-popliteal nerves. At the base of the latter, it emits the anterior and 
posterior gluteal nerves. These branches and their ramifications will be 
successively studied. 


Preparation of the lwmbo-sacral plexus—After removing the skin and abdominal 
visce a, the hind quarters are isolated by sawing through the vertebral column behind 
the last rib; then, by means of a section almost in tne middle of the pelvis, one of the 
limbs is cut off. and the pieces, disposed as in figure 355, should be maintained in th; 


THE LUMBO-SACRAL PLEXUS. 771 


LUMBO-SACRAL PLEXUS AND INTERNAL NERVES OF THE POSTERIOR LIMB. 

1, 1, Lumbo-sacral plexus; 2, Anterior femoral nerve; 3, Internal saphena nerve; 4, 
Obturator nerve ; 5, Originating fasciculus of the great and small femoro-popliteal 
nerves; 6, Superficial ramuscules of the posterior gluteal nerves; 7, Great 
femoro-popliteal nerve; 8, Internal pudic nerve; 9, Hemorrhoidal, or anal 
nerve; 10, Internal plantar nerve; 11, 12, Its digital ramifications. 


Note.—In the above figure is seen the posterior part of the plexus formed by the nervous branches which 
That which escapes from the foramen between the sacrum 


pass through the three first subsacral foramina, 

and last lumbar vertebra, only gives a fine branch to this part of the plexus, and sends the greater portion of 
its fibres, in two cords, to the anterior part, This arrangement is not rare, and is generally seen, we believe, 
when there ae only five lumbar vertebra: as is remarked in the Ass and Mule, and sometimes in the Horse. 
It will, therefore, be understood that the nerve described by us as the first sacral becomes the last lumbar. 


772 THE NERVES. 


first position: that is, with the croup resting on the dissecting table near one of the bars, 
and the limb suspended vertically, the foot upwards, by a cord attached to the ring of 


the bar. 
Afterwards, the preparation is executed in two stages. In the first, after tlie excision 


of the pelvic organs and the small psoas muscle, the whole of the plexus and its forma- 
tive branches are dissected, taking figure 355 as a guide. In the second, the posterior 
part of the plexus, with the nerves it gives off, are exposed on the external side, by 
excising the greater portion of the principal gluteal muscle and the anterior portion of 
the long vastus (abductor magnus, or triceps abductor femo.''s). as in figure 356, 

To follow the various divisions of the nerves emanating from the plexus, to their 
terminations, it is well to use the other limb, which, not being fixed, can be laid ona 
table, and in this way is more convenient than the first for this part of the operation. 


1. Iliaco-muscular Nerves. 


These nerves are of little importance. The principal one accompanies 
the iliaco-muscular artery across the substance of the iliacus muscle. 


2. Crural or Anterior Femoral Nerve. (Fig. 855, 2.) 


This is the largest of the branches arising from the anterior portion of 
the plexus. It descends between the psoas magnus and parvus, to the 
common conical extremity of the latter muscle and the iliacus, where it is 
covered by the long adductor of the leg ; there it terminates in a wide tuft of 
branches, destined to the mass of the triceps extensor cruris. 

Below the adductor, it successively emits two long branches, which 
deserve a particular description. 

The first represents the nervous fasciculus which, in Man, comprises the 
crural musculo-cutaneous branches. We have named it the accessory branch of 
the internal saphena. It reaches the interstice between the two adductors, in 
crossing the crural vessels very obliquely forward. ‘Leaving this space, it 
becomes subcutaneous in forming numerous divisions which surround the 
saphena artery and vein. 

The second, or internal saphena nerve, passes at first between the long 
adductor of the leg and the vastus internus, and parallel to the first, which 
is situated more inwardly and posteriorly. Near the inferior extremity of 
the interstice separating the two adductors of the leg, it escapes and becomes 
subcutaneous, dividing into a number of filaments which meet those of the 
accessory nerve. 

These two branches communicate by deep or superficial anastomosing 
loops. Before leaving the space between the adductors, they give some 
slender filaments to these two muscles, particularly to the anterior. Near 
their origin, they even distribute some to the iliacus. Becoming sub- 
cutaneous, their ramuscles cover the inner face of the thigh and leg; the 
longest of these accompany the saphena vein to the anterior aspect of the 
hock. 

It sometimes, indeed most frequently, happens that the internal saphena 
nerve and its accessory form only a single branch, whose muscular or 
cutaneous divisions otherwise comport themselves exactly like the above. 
This is exemplified in the dissection represented in figure 355. 


3. Obturator Nerve. (Fig. 355, 4.) 


Situated underneath the peritoneum, to the inner side of the iliac vessels 
which it accompanies to the origin of the obturator artery, this nerve follows 
the latter to the upper face of the pubis, and passes with it beneath the 
internal obturator muscle, to traverse the foramen ovale. In this way it 


THE LUMBO-SACRAL PLEXUS. 773 


arrives outside the pelvis, where it nevertheless remains deeply concealed by 
the muscular masses on the internal aspect of the thigh. Its terminal rami- 
fications are expended in the obturator externus, the adductors of the thigh, 
the pectineus, and the short adductor of the leg. Tue branch destined to 
the latter muscle is the longest; it leaves the space between the pectineus 
and the small adductor of the thigh, and descends backwards on the internal 
tace of the muscle to which it is distr: buted. 


4. Small Sciatic or Anterior and Posterior Gluteal Nerves. 


The small sciatic of the Horse is composed of several cords that issue 
from the pelvis by the upper part of the great ischiutic notch, and which have 


Fig. 356, 


POSTERIOR PORTION OF THE LUMBO-SACRAL PLEXUS. : 

1, Conjoining fasciculi of the three first sacral nerves; 2, 3, 4, E enlaee aie 
"nerves ; 6, 6’, 8, Posterior gluteal nerves; 7, 9, Branches whic a : e 
great sciatic ligament, and communicate between the posterior glutea oo 
and the divisions of the internal pudic nerve; 10, 11, 12, 13, ree a ic nerve 
and its crural branches; 14, Small femoro-popliteal nerve; 15 Its cutaneous or 


peroneal-cutaneous branch. 


been for a long time described as the anterior and posterior gluteal 

ne Th i ili i 3, 4, 5) are four 
1 or ilio-muscular nerves (Fig. 356, 2, 3, 4, 

A ea ase ‘sitter separately or in groups from the posterior 


i ber, and arise ‘ 
OF cena fhe Tabeanccl plexus. They appear to be more particularly 
Feeniahed by the two first sacral branches. All leave the pelvic cavity by 


the great sciatic opening, along with the anterior gluteal vessels. The 
52 


774 THE NERVES. 


principal branches are lost in the middle gluteal muscle. One of them 
(Fig. 356, 4,) crosses the neck of the ilium above the small (or internal) 
gluteal muscle, and passes outwards to be distributed to the muscle of the 
fascia lata (tensor vagine femoris). The last, which is the most slender, 
descends to the external surface of the gluteus internus, and is distributed in 
its substance (Fig. 356, 5). ; 

The posterior gluteal, or ischio-muscular nerves (Fig. 356, 6, 6’, 8), are 
usually two in number—a superior and inferior. 

The first escapes through the great sacro-ischiatic notch, along with the 
femoro-popliteal nerves, and is situated on the external surface of the ischiatic 
ligament. It passes backward, between this ligament and the gluteus 
medius, to beneath the anterior or croupal portion of the triceps extensor 
cruris, in which it is distributed by several filaments. Besides these, it. 
gives: 1, In passing beneath the gluteus medins, a slender, but constant 
filament to the posterior portion of that muscle; 2, Another, and more 
considerable branch, which bends round the posterior border of that 
muscle, to be directed forward and outward to the gluteus externus. 

The second nerve, situated beneath the preceding, appears to be detached 
from the posterior border of the great sciatic. It is placed at the external 
surface of the sciatic ligament, is directed backwards in passing below the 
croupal portion of the triceps cruris, traverses that muscle above the ischial 
tuberosity, descending underneath the sacral portion of the semitendinosus, 
soon to leave its deep track and become superficial. It escapes from between 
the latter muscle and the triceps cruris, and is lost beneath the skin covering 
the posterior part of the thigh. Its deep portion gives off collateral 
branches which reinforce the divisions of the internal pudic nerve, as well 
as filaments to the long branch of the semitendinosus muscle. 


5. Great Sciatic or Great Femoro-popliteal Nerve. (Figs. 135, 13; 357, 1, 2.) 


This enormous nervous trunk issues by the great sciatic opening in the 
form of a wide band, which is applied to the external face of the ischiatic 
ligament. Comprised at first between that ligament and the glutcus medius, 
it is directed backwards in passing over the fixed insertion of the gluteus 
internus, and arrives behind the gemini and quadratus femoris muscles. On 
leaving this point, it is inflected to descend behind the thigh, where it is 
lodged in the muscular sheath formed for it by the triceps cruris, the semi- 
tendinosus and membranosus, and the great adductor of the thigh. Arriving 
towards the superior extremity of the leg, it enters between the two bellies 
of the gastrocnemii muscles, passes along the posterior aspect of the 
perforatus muscle, and descends in the channel of the hock, beneath the tibial 
aponeurosis, following the internal border of the fibrous band that rein- 
forces the tendon of the hock. It finally terminates at the calcis by two 
branches ; the external and internal plantar nerves. 

From the point at which the great sciatic enters between the bellies of 
the gastrocnemii muscles, and as far as the furrow of the calcis, this nerve 
corresponds to the branch named in Man the internal popliteal—a branch 
that is continued by the posterior tibial, which terminates in the plantar 
filaments. 

In its long course, this nerve successively emits: 1, The external 
popliteal nerve ; 2, A branch to the muscles of the deep pelvi-crural region ; 
3, Another to the posterior crural muscles; 4, The external saphenous 
nerve; 5, A voluminous fasciculus to the muscles of the posterior tibial , 


THE LUMBO-SACRAL PLEXUS. 775 


region. All these branches will be studied, more especially the external 
popliteal ; which is so disposed in Solipeds, that Veterinary authorities have 
described it as a special trunk, by the name of the small femoro-popliteal, 


and even as the small sciatic nerve. We will afterwards pass to the ter- 
minal branches. 


COLLATERAL BRANOHES. 


1. Externat Sctatio-popLirzaL, oR SMALL Femoro-PorirreaL NERvE.— 
This nerve separates from the great sciatic at the gemini muscles of the 
pelvis. It is then directed forward and downward, proceeds between the 
triceps cruris and the gastrocnemius muscles, and arrives outside the superior 
extremity of the leg, behind the lateral ligament of the femoro-tibial 
articulation, where it terminates by two branches: the musculo-cutaneous, and 
the anterior tibial nerve. 

In the long course it follows from its origin to its bifurcation, the external 
sciatic popliteal nerve only furnishes a single collateral branch: this is the 
cutaneous nerve which is detached from the parent trunk above the gastro- 
enemius, and which traverses the inferior extremity of the triceps cruris, to 
terminate by divergent ramuscles destined to the skin of the leg. It might 
be named the peropeal-cutaneous branch. Before becoming superficial, this 
cutaneous nerve gives off a small descending filament which goes to reinforce 
the external saphenous nerve, after creeping over the aponeurotic layer of 
the external gastrocnemius. This branch, which might be designated the 
accessory of the external saphenous, sometimes proceeds directly from the 
popliteal, as may be remarked in Fig. 357. ; ms 

Terminal Branches—These two branches influence the contractility of 
the muscles belonging to the anterior tibial region, and endow the skin on 
the anterior face of the foot with sensation. oe 

The musculo-cutaneous nerve is situated beneath the tibial aponeurosis ; it 
first sends a bundle of ramuscules to the lateral extensor of the phalanges, 
and continues to descend between that muscle and its congener, the anterior 
extensor, to the middle of the tibia. It then traverses the fibrous envelope 
of the tibial muscle, becomes subcutaneous, and gains the anterior face of 
the metatarsus, where it is lost in the skin. Some of its terminal filaments 
may be followed to the fetlock, and even beyond it (Fig. 357, 6). ; 

The anterior tibial nerve passes in front of the preceding, to one side of 
the superior extremity of the leg, and then plunges beneath the anterior ex- 
tensor of the phalanges, giving to that muscle and the flexor of the a eh 
short, but thick, ramuscules. It descends to the front of the tarsus, a | 
covered by the anterior extensor of the phalanges, and placed at akg ate 

i f the anterior tibial vessels. When it arrives below the tibia, it lies 
rs oa tely alongside the pedal artery, and follows it, in its metatarsal 
faitton e ae the fetlock. It then separates from its satellite vessel, and 
passes on the side of the digit, where it ends by the emission of cutaneous 

ig. 357, 5). Ee ctok : 
ae ie this pase cones im its course, are cited those 

i influence to the pedal muscle. 
bar Tae oa: os me MosciEs oh THE Deze PELvI-cRURAL eee 
It is known that this region comprises the obturator internus, gemini, an 

: tus femoris muscles, The nervous branch sent to them is long and 
Ee ah? - it is detached from the sciatic trunk at the middle of the super-- 
sae fae ant descends with that trunk behind the coxo-femoral 
ereonletion, Go distribute its terminal divisions to the above-named muscles. 


776 


THE NERVES. 


The longest and thickest of these goes to the quadratus femoris. That 
passing to the obturator internus re-enters the pelvic-cavity by the small 
ischiatic notch, and ascends to the vicinity of the ilio-sacral articulation. 


EXTERNAL NERVES OF THE POSTERIOR 
LIMB. 


1, 2, Great sciatic nerve; 3, External saphena 
nerve; 4, External popliteal nerve; 5, An- 
terior tibial nerve; 6, Musculo-cutaneous 
nerve; 7, Origin of the peroneal-cutaneous 
branch ; 8, Accessory branch of the external 
saphenous nerve ; 9, External plantar nerve 
with its divisions, which cover the digital 
artery and vein. 


3. Branco to THE Iscuro-TrB1aAL 
or Posterior Cruran Muscirs.— 
This branch is thick and short; it 
arises from the bend formed by th« 
great femoro-popliteal nerve at th 
gemini muscles, and soon divides int 
several ramifications which are dis- 
tributed to the short portion of the 
triceps cruris, the middle and inferior 
parts of the semitendinosus, and into 
the semimembranosus. Some of the 
filaments destined to the latter muscle 
pass between it and the great adductor 
of the thigh, in which they partly 
terminate (Fig. 356, 12). 

4. ExrernaL Sappznovus Nerve. 
—This branch commences at from 2 
to 6 inches from the point where the 
great sciatic nerve dips between the 
gastrocnemli muscles. It is placed 
on the external gastrocnemius, and 
descends underneath the special apo- 
neurotic layer covering that muscle, 
to the origin of the tendon of the 
hock. It then receives its accessory 
nerve—the reinforcing filament which 
comes from the cutaneous branch of 
the small femoro-popliteal nerve, and 
is prolonged beneath the tibial apo- 
neurosis into the channel of the hock, 
accompanying the external saphenous 
vein, and following the external 
border of the fibrous band that goes 
to strengthen the tendo-Achillis, In 
this way, it occupies the same situa- 
tion outside the hock that the great 
sciatic does on the inner side. It 
afterwards passes over the tarsal 
region, and is expended on the outside 
of the metatarsus in several filaments, 
some of which descend to the outer 
aspect of the digit (Figs. 356, 18; 
357, 3). 

5. Fascrcunt to THE PosrErior 
Trs1at Mosctxs.—This fasciculus is 


composed of numerous branches, which are detached together from the 
sciatic nerve on its passage between the gastrocnemii muscles, in the form 
of a thick short trunk. The muscles of the superficial layer—the gastro- 
enemii, perforatus. and the thin fleshy band, improperly designated the small 
plantaris by Veterinarians—receive ramuscules which are remarkable for their 


THE LUMBO-SACRAL PLEXUS. 717 


large number and their shortness. Those of the deep layer are supplied by 
filaments from a single long and thick branch, which descends between the 
perforatus and the internal gastrocnemius, It may be remarked, that the 
filament going to the so-called small plantar muscle, passes underneath the 
external gastrocnemius, outside the perforatus, and that, by its position, it 
exactly represents the soleus ramuscule of Man. We are. therefore, with 
Vicq-d’Azyr, Cuvier, and others, justified in naming this little muscle the 
solearis (soleus), instead of continuing to designate it the small plantaris, 
which appellation is given to another muscular clement. 

6. In its course along the tendo-Achillis, the sciatic nerve emits some 
slender cutaneous filaments, which we do not consider worthy of further 
notice. 


TERMINAL BRANCHES, 


Puantar Nerves (Fig. 355, 10, 12)—These two nerves enter the 
tarsal sheath, behind the perforans tendon, along with the plantar arteries. 
Towards the superior extremity of the cannon, they definitively separate 
from each other; the external is carried outwards between the precited 
tendon and the rudimentary metatarsal bone; the internal is placed with 
that. tendon, and follows the posterior border of the inner metatarsal bone. 
Both afterwards descend on the fetlock, where they comport themselves 
like the analogous nerves of the anterior limb. 


DIFFERENTIAL CHARACTERS IN THE LUMBO-SACRAL PLEXUS OF OTHER THAN SOLIPED 
ANIMALS, 


As was the case with the brachial plexus, so with this: the differences observed 
being trifling in the upper part of the limb, but more numerous and important in the 
region of the foot, the complexity of arrangement varying with the species. 

Rumrwants.—The lumbo-sacral plexus of these animals is constituted by two lumbar 
and three sacral nerves, as in Solipeds; but the third sacral only gives a very fine 
filament, which reaches the second in passing downward and forward. 

At the femoro-tibial articulation, the branches of the plexus are similar to those in 
the Horse. Below that articulation, the following disposition lias been observed in 
the Sheep. 

The musculo-eutaneous branch of the popliteal is long and thick. It descends on the 
anterior face of the metatarsus, and at the metatarso-phalangeal aiticulation bifurcates, 
the brauches forming the dorsal collaterals of the digits. The anterior tibial nerve 
presents two branches parallel to the tibial vessels; one passes along the metatarsal 
region, and when it arrives at the bottom of the groove between tl:e condyles of the 
metatarsus, it divides into twc branches that constitute the deep collaterals of the 
digits; these collaterals furnish filaments to the posterior face of the digital region. 

The great sciatic resembles that of Solipeds. Its terminal branches, or plantar 
nerves, differ from those of the Horse in the absence of the transverse anastomosis that 
unites the two cords in the region of the tendons. 

Pic.—The lumbo-sacral plexus of this animal is composed of two lumbar and three 
sacral nerves: reckoning, of course, as a sacral nerve, the trunk that escapes from 
between the last lumbar vertebra and the sacrum. The plexus may be divided into 
two portions, the first furnishing a femoral and an obturator nerve. The tnternal 
suphenous branch of the femoral nerve is long and voluminous; at its origin it is as 
large as the branch passing to the anterior muscles of the thigh, and it descends on the 
inner face of the metatarsus, forming the dorsal collateral of the internal digit. 

The great sciatic is voluminous and round. The branches it gives fo the muscles 
of the pelvis and femur are disposed nearly as in Solipeds and Ruminants; but 
differences are observed in the eaternal popliteal and the terminal branches. ; 

The musculo cutaneous nerve reaches the metatarsnl region, where it separates into 
three branches, which form the dorsal collaterals of the digits. 

The anterior tibial nerve descends between the two principal metatarsals, and at the 
root of the middle digits divides to anastomose with the plantar nerves, Of th se the 
external is small, and gives collaterals to the two external digits; the internal, the 


778 THE NERVES. 


largest, descends between the two principal digits, where it bifurcates; above, it gives a 
branch to the internal digit. 

Carnivora.—lIn these animals, the lumbo-sacral plexus is formed by the last four 
lumbar and the first two sacral. 

The crural and obturator nerves, which arise from the fourth, fifth, and sixth lumbar 
nerves, offer nothing particular in their disposition. 

The internal saphenous branch is as long as in the Pig; it passes to the internal face 
of the tarsus, lies alongside the fourth metatarsal bone, and forms the internal dorsal 
collateral of the fourth toe. 

The great sciatic may be described as having, as in Man, two terminal branches 
which separate a little above the posterior face of the femoro-tibial articulation. The 
external popliteal nerve passes to the surface of the external gastrocnemius, enters 
between the common long flexor of the toes and the long lateral peroneal muscle, 
where it bifureates. The musculo-cutaneous branch descends beneath the latter muscle 
to the lower third of the leg, when it becomes superficial, and, accompanied by a vein, 
is lodged in the interspace between that muscle and the anterior tibial; it passes in 
front of the tarsus, and reaches the upper part of the metatarsus, where it divides into 
three divisions. It must be mentioned that at the tibio-tarsal articulation is thrown off 
a very fine cord, which is directed outwards, and forms the external dorsal cullateral 
of the first toe. Each of its three terminal branches courses along an intermetatarsal 
space, and at the metatarso-phalangeal articulations separates into two filaments, 
whence results the following distribution: the external branch forms the internal 
dorsal collaterals of the first toe and external of the second; the middle constitutes 
the internal dorsal collaterals of the second toe and external of the third; lastly, the 
internal furnishes the internal dorsal collaterals of the third toe and external of the 
fourth. The anterior tibial nerve accompanies the artery of that name, descends along 
the external face of the tibia, and terminutes in two branches at the tarsus. Of these, 
one is distributed to the tarsal articulations and the pedal muscle; the other, internal, 
enters the intermetatarsal space, and at the corresponding metatarso-phalangeal joints 
anastomoses with the internal branch of the musculo-cutaneous nerve, and is lost in the 
same parts. The internal popliteus forms the second terminal branch of the great sciatic 
nerve, and in the Dog and Cat represents that portion of the latter which, in the Horse, 
is situated behind the femoro-tibial articulation. It is continued by the posterior tibial 
nerve, which terminates by the two plantar nerves. During its course, the external 
popliteal furnishes articular and muscular filaments, as well as cutaneous twigs 
subsequently ; among the latter may be mentioned the eaternal saphenous, which arises 
by two branches, and is expended behind the malleolus, at the outer side of the tarsus. 
The plantar nerves are external and internal; the latter lies at the inner border of the 
tendon of the superficial flexor muscles of the phalanges, and when it joins the middle 
of the metatarsus, it detaches a fine filament that forus the internal plantar collateral 
of the fourth toe; it then passes obliquely towards the first toe, at the deep face of the 
above-named tendon, and successively gives off three filaments—one for each inter- 
metatarsal space. These filaments anastomose with the terminal branches of the 
external plantar, at the metatarso-phalangeal articulations; the first two filaments 
supply the large cushion of the paw. 

The external plantar nerve passes between the two flexor tendons of the toes, where 
it gives a filament that constitutes the external plantar collateral of the first toe. It is 
afterwards placed outside the deep flexor, then enters beneath the short flexor and 
divides into several branches, muscular and digital. Each of the latter, three in 
number, passes into a corresponding interosseous space and bifurcates at the metatarso- 
phalangeal articulations, receiving filaments from the internal plantar, and forming the 
following plantar collat-rals : the internal of the first toe, internal and external of the 
second, internal and external of the third, and external of the fourth digit. 


COMPARISON OF THE LUMBO-SACRAL PLEXUS OF MAN WITH THAT OF ANIMALS. 


It is usual, in human anatomy, to describe a lumbar and a sacral plexus. 

The lumbar pleaus is constituted by the anastomoses of the anterior branches of the 
five lumbar nerves 1 these are united by fine filaments, which are not intricately 
associated. The divisions of this plexus are distinguished as collateral and terminal 
branches. The first, destined to the upper part of the limb and the skin covering the 


C Wilson says the four upper lumbar nerves and the last dorsal; Heath gives the 
same constitution.) 


THE LUMBO-SACRAL PLEXUS. 779 


external genital organs, are represented in Solipeds by the ramifications of the lumbar 
nerves, which have been separately described. The terminal branches are the 
obturator crural, and anterior femural (or anterior crural), There is nothing to be said 
respecting the obturator nerve; 
it leaves the pelvis by the obtura- 
tor foramen, asin all the animals 
mentioned. The crural has 
been described as having four 
terminal branches: the internal 
and external musculo-cutaneous, 
the nerve of the triceps crureus 
(muscular branch), and the in- 
ternal saphenous. The two mus- 
culo-cutaneous branches have 
their analogue in the Horse, in 
the filament we have named the 
accessory branch of the internal 
saphenous, ‘The nerve of the | 
triceps is expended in the an- 
terior rectus, and the vastus 
internus and externus. ‘The 
saphenous descends between the 
muscles of the inner aspect of 
the thigh, beneath the aponeu- 
rosis, aud_ becomes superficial at 
a short distance from the con- 
dyle of the femur, giving a 
patellar branch that divides in 
the skin of the knee, and a 
tibial branch that is expended 
on the inner face of the tarsal 
articulations and the fovt. 

The sacral plexus comprises 
the first three sacral nerves, t» 
which is added a lumbo-sacral 
branch furnished by the lunibar 


Fig, 358, 


nerves, and a fine tilament that 
ascends from the fourth sacral. 

Ten collaterals and a ter- 
minal branch urise from this 
plexus. j 

The collateral branches are 
divided into intrapelvic and 
extrapelvic: they are five in 
each group. The first are des- 
tined to the muscles of the inner 
aspect of the pelvis, and t> those 
of the perineum and t e skin 
of this region, The second are 
distributed to the muscles on 


LUMBAR PLEXUS OF MAN. 


1, Right gangliated cord of sympathetic; 2, Abdominal 


aorta; 3, 3, Last dorsal nerves; 4, Psoas parvus; 5, 
Quadratus lumborum; 6, Psoas magnus; 7, 7, Ilio- 
hypogastric nerves; 8, Iliacus internus; 9, 9, Ilio- 
inguinal nerve; 10, Lumbo-sacral nerve; 11, Genito- 
crural nerve; 12, Gluteal nerve; 13, Iliac branch of 
ilio-hypogastric nerve; 14, Sacral plexus; 15, 15, 15, 
External cutaneous nerves; 17, Transversalis abdomi- 
nis; 19, Obliquus internus; 21, Obliquus externus, 
23, 23, Anterior crural nerves; 25, 25, Obturator 
nerves ; 27, 27, Crural branch of genito-crural nerve ; 
29, Genital branch of genito-crural nerve ; 31, External 
iliac artery ; 33, External abdominal ring. ‘ 


the outer aspect of the pelvis, 
and the skin on the posterior face of the thigh. They are: 

1. Visceral branches that descend on the sides of the rectum and are Jost in the 
hypogastric plexus; 2, Nerve of the elevator of the anus ; 3, Hemorrhvidal or anal nerve ; 
4, Nerve of the internal obturator that appears to arise, in the Horse, from the sciatic 
trunk; 5, Internal pudie, which has been described with the sacral nerves. In Man this 
nerve leaves the pelvis by the great sciatic notch (or foramen), and returns to it by the 
lesser; within the ischiatic tuberosity it divides into two branches: an inferior or 
perineal, and a superior or dorsalis penis nerve. The latter is placed on the dorsum 
of the penis, and reaches the mucous membrane of the glans and prepuce; the former 
does not go beyond the muscles and integuments of the perineum. 6, The superior 
gluteal nerve ; 7, Nerve of the pyramidalis, 8, Nerve of the superior gemellus; 9, Nerve of 
the inferior gemellus and quadratus cruralis , 10, The small sciatic, or inferior gluteal nerve, 
the inferior or femoral branch of which is very long, descending, as it does, to the middle 
of the posterior face of the thigh, beneath the crural aponeurosis, to the popliteal space, 
where it becomes superficial, and terminates in the skin of the upper portion of the leg. 


780 


NERVES AT THE POSTERIOR ASPECT OF 
HUMAN LEG. 

1, Popliteal artery; 2, Great sciatic nerve ; 
3, Adductor magnus; 4, Biceps; 5, Superior 
internal articular artery ; 6, External pop- 
liteal nerve; 7, Gastrocnemius, cut; 8, 
Anterior tibial artery; 9, Tendon of semi- 
membranosus ; 10, Peroneus longus; 11, 
Sural arteries and nerves; 12, Peroneal 
artery; 13, Internal popliteal nerve; 14, 
Tibialis posticus; 15, Portion of soleus ; 
16, Peroneus brevis; 17, Popliteus; 18, 
Flexor longus pollicis; 19, Posterior tibial 
nerve; 20, Calcanean branch of posterior 
tibial nerve; 21, Posterior tibial artery ; 
22, Tendo-Achillis; 23, Flexor longus digit- 
orum; 25, Tendon of tibialis posticus; 27, 
Plantar nerves; 29, Plantar arteries. 


THE NERVES. 


NERVES AT THE FRONT ASPECT OF HUMAN LEG, 
1, External popliteal nerve; 2, Anterior 


” 


tibial artery ; 3, Musculo-cutaneous nerve ; 
4, Anterior tibial nerve; 5, Peroneus 
longus; 6, Tibialis anticus; 7, Extensor 
longus digitorum; 8, Anterior annular 
ligament ; 9, Peroneus brevis; 10, Tendon 
of extensor proprius pollicis; 11, Extensor 
proprius pollicis; 12, Dorsal artery of foot ; 
13, Point at which the musculo-cutaneous 
nerve pierces the fascia and bifurcates; 14, 
Tendon of tibialis anticus;, 15, Internal 
branch of musculo-cutaneous nerve; 16, 
Cutaneous branch of anterior tibial nerve; 
17, External branch of musculo-cutaneous 
nerve; 19, Deep branch of anterior tibial 
nerve; 21, External saphenous nerve; 23, 
.Extensor brevis digitorum. 


THE GREAT SYMPATHETIC NERVOUS SYSTEM. 781 


The terminal branch of the sacral plexus forms the great sciatic Y 
distribution is the same as that of ace, The elise ramuscules of the pee 
sciatic are the brauch of the long portion of the biceps; the semitendinosus and 
semimembranosus branch; the branch to the great adductor ; and, lastly, that to the 
short portion of the biceps. It terminates by the external and internal popliteal, 

a anterior tibial, continuations of the external poplitens, 
comport themselves almost the same as in the Doe. The i rals 
third, fourth, and fifth toes, as well as to the second, eh creas aegis ae 

The énternal popliteal presents an external saphenons nerve that passes alon 
external border of the foot, and has, in addition, 4 branch that aeenile on the pas 
of that organ. The external saphenous furnishes the dorsal collaterals to the first toe 
and the external collateral to the second. The posterior tibial nerve continues the 
internal sciatic in the leg; it terminates in the plantar nerves. The internal plantar 
furnishes the collateral nerves to the fifth, fourth, and third toes, and the internal 
collateral of the second toe. The external divides into three branches: the two 
superficial branches form the collaterals of the first toe, and the external collateral of the 
second; the deep branch passes inwards, behind the interosseous muscles, and is 
expended in those of the fourth space, after. giving filaments to the oblique abductor of 
the large toe, transverse abductor, last two lumbricales, to the interosseous, and very 
fine filaments to the articulations of the tarsus with the metatarsus. 

It will therefore be seen that, in Man, the branches of the deep trunk of the 
external plantar join those of the internal plantar, to form the collateral nerves, 


CHAPTER III. 
THE GREAT SYMPATHETIC NERVOUS SYSTEM. 


PREPARATION OF THE GREAT SYMPATHETIC.—The same subject ought to suffice for the 
preparation of this, as well as the pneumogastric and spinal nerves. After placing the 
animal in the first position, the intestines are removed, one of the posterior limbs cut 
off, and the greater portion of the os innominatum cleared away by sawing through the 
symphysis pubis and the neck of the ilium; the dissection of all the abdomino-pelvic 
portion of the system, and that of the terminal branches of the pneumogastric nerve, is 
then proceeded with. The anterior limb of the same side should be afterwards 
detached, the scapula having been previously sawn across its middle part, and the 
thorax thrown open by the ablation of the entire costal wall, in sawing through the 
sternal cartilages below, and the ribs above, at their superior extremity All the 
thoracic portion of the ganglionic nervous apparatus, and the pneumogastric nerves 
may then be prepared. Nothing more remains to be accomplished except the dissection 
of the sympathetic and the vagus nerve in the cervico-cephalic region, with that of the 
spinal nerve; this operation is not attended with any difficulty, and should be preceded 
by the extirpition of a branch of the inferior maxilla. It is useful to inject the arteries 
previously ; as then the filaments of the sympathetic that lie alongside the vessels 
ot the different organs in the abdominal cavity can be more easily followed. 


The great sympathetic, also named the trisplanchniz system (ordavyvov 
—an intestine or viscus), because of its position and destination, is the nervous 
apparatus of the organs of vegetative life. 

As has been already shown in the general consideration of the nerves 
and the whole nervous system, this apparatus has for its base two long cords 
extending from the head to the tail, underneath the vertebral column, and to 
the right and left of the median line. Towards the last sacral vertebra, a 
portion of these two cords converge towards each other, and lie beside the 
median coccygeal artery. Some anatomists think that the great sympa- 
thetic does not stop at this point, but is prolonged beneath the coccygeal 
vertebree, where it enters a ganglion that has been described of late years 
as the “coccygeal gland,” and whose nature has been very much contested. 

Each cord presents on its course numerous ganglia, to whose presence it 


782 THE NERVES. 
owes its chain-like aspect ; they are usually elliptical in shape, though they 
may also be round or semilunar ; in all cases they are studded with prolonga- 
tions at their borders. Beneath each of the regions of the spine they are equal 
in number to the vertebra, with the exception of the cervical region, in 
which are only two—one at the top, the other at the bottom, of the neck. 
To this chain arrive afferent branches, by the union of which it is con- 
stituted; these branches are furnished by the nerves of the medulla oblongata 
and the inferior spinal branches, except those of the coccygeal region. The 
afferent branches join the sympathetic at each ganglion; but as there are 
only two ganglia in the region of the neck, the afferent filaments of the 
cervical nerves are grouped in such a manner as to reach the superior and 
inferior ganglion. 
ae sae which are given off from the ganglia to be distributed to 
the viscera, are named the efferent or emergent branches. They are interlaced 
around the arteries to reach their destination, forming plexuses on the surface 
of these vessels. ee 
This general idea of the disposition of the great sympathetic is sufficient 
to show that its double ganglionic chain does not represent two particular 
nerves arising at one determinate point, and ending at 
another. Properly speaking, they have neither origin 
nor termination: they are always giving off branches 
which are as frequently replaced by others: in this way 
they might be compared, in this respect, to the median 
spinal artery, which offers somewhat the same mode of 
constitution—with its afferents supplied by the spinal 
branches from the intervertebral foramina, and its efferents 
destined to the substance of the spinal medulla. 
Srructurr.—The ganglia of the great sympathetic 
differ but little in their structure from the spinal ganglia, 
whose constitution has been already made known. They 
have an envelope of connective tissue, which sends very 
fine septa into their interior. In the spaces are cells 
a little smaller and paler than those of the spinal gan- 
glia; they are round, or furnished with poles that bring 
them into communication with the afferent and efferent 


SYMPATHETIC GAN- nerve-tubes; there are also, in the ganglia, tubes which 
GLION FROM A only pass through it, and merely lie beside the cells. 
PUPPY. 


a, a, Trunk of the 
sympathetic nerve; 
b, Communicating 
branches from a 
spinal nerve; these 
divide into two fas- 
ciculi which pass 
upwards and down- 
wards 1n the trunk ; 
v, ¢, The ganglion 
composed of gan- 
glion cells; d, Small 
branch, probably 
destined to accom- 
pany an artery; ¢, 
Visceral branch. 


and otic ganglia, 


The afferent branches of the ganglia have the white tint 
of the cerebro-spinal nerves, and are named the grey 
nerves. They owe their colour to the fibres of Remak, 
which they contain in large quantity. With these 
nucleated fibres are associated fine nerve-fibres, and 
double-contoured fibres which proceed from the com- 
municating rami, or afferent filaments supplied by the 
spinal nerves; these fibres often leave the ganglia to 
pass directly to organs. 

In describing the sympathetic chain, it is divided into 


five sections: a cephalic, cervical, dorsal, lumbar, and 
sacral, 


1, Cephalic Portion of the Sympathetic. 


This is composed of the spheno-palatine, ophthalmic, 
all of which communicate with the superior cervical 


THE GREAT SYMPATHETIC NERVOUS SYSTEM. 783 


ganglion. Their description has been given with that of the fifth encephalic 
pair of nerves. 


2. Cervical Portion of the Sympathetic, 


The cervical section of the ganglionic chain is formed by two large 
ganglia placed one at the top, the other at the bottom, of the neck, and united 
to each other by an intermediate cord. 

A, Superior Curvican or Gurrurat Gancuion (Fig. 362, 1). -— This 
ganglion is a very elongated fusiform body, lying beside the internal carotid 
artery, comprised with it in a particular fold of the membrane forming the 
guttural pouch, and therefore situated in front of the transverse process of 
the atlas, in proximity to the glosso-pharyngeal, pneumogastric, spinal, and 
hypoglossal nerves, as well as the inferior branch of the first cervical pair. 
All these nerves communicate with the ganglion by slender filaments, and 
in this way form around it a veritable plexus, which has been designated the 
guttural plexus by Veterinary Anatomists. 

Arrzrent Brancues.—These are communicating filaments belonging to 
the nerves already enumerated. They do not possess sufficient importance 
to merit particular mention. We may notice the existence of the filaments 
supplied by the inferior branches of the first four cervical nerves. 

Emercent Brancues.—These are: 1, Branches accompanying the 
internal carotid artery into the cranium; 2, A thick fasciculus which 
reaches the origin of the three terminal divisions of the common carotid, 
3, Small filaments to the membrane of the guttural pouch and the wall of 
the pharynx. 

The following are the principal anatomical characters of these three 
orders of branches: 

a. The satellite branches of the internal carotid artery arise at the superior 
extremity of the ganglion. They may vary in number. We have generally 
found two of unequal volume—a posterior, and an anterior, which is the 
smallest. They interlace around the internal carotid in anastomosing with 
each other, and with that vessel enter the cavernous sinus, where they form, 
by their divisions, a little plexiform apparatus named the cavernous plexus, 
the diverse branches of which connect it with several of the encephalic 
nerves. Among these branches are remarked: 1, Some filaments joined to 
analogous filaments from the opposite side, on the transverse anastomosis 
which unites the two internal carotids in the cavernous sinus; 2, A branch 
lying beside the great petrosal nerve, and concurring in the formation of the 
Vidian nerve, which enters the spheno-palatine ganglion; 3, A ramuscule 
going to the ophthalmic ganglion, in company with fibres from the 
ophthalmic branch of the fifth pair; 4, Several filaments passing to the 
Gasserian ganglion; 5, Branches which mix with the fibres of the three 
motor nerves of the eye. 

b. The inferior carotid fasciculus, destined to the terminal extremity of 
the common carotid, escapes from the inferior part of the guttural ganglion. 
Frequently at its origin it is only a thick cord, but ordinarily it is composed, 
from its commencement, of several branches bound to one another by com- 
municating filaments. Reaching their destination, these branches meet 
ramuscules emanating from the glosso-pharyngeal and pneumogastric nerves, 
und anastomose with them to form, around the origin of the three terminal 
branches of the common carotid, the so-called carotid pleaus, whose rami- 
fications almost exclusively follow the external carotid, and the greater part 
of which are distributed to the glands and the salivary lobules. In Man, the 


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arf TOWNE ATINVE $WAISAS OTLAHLVAWA f 


VP AIND GAPYIOT, da 7? UMDIAMDY, LP, VE : 


THE GREAT SYMPATHETIC NERVOUS SYSTEM. 785 


division which follows the spheno-spinal artery passes to the otic ganglion ; 
the same takes place, no doubt, in animals. 

e. The guttural or pharyngeal filaments, arising from the anterior border 
of the ganglion and the inferior carotidean fasciculus, are generally very 
delicate. Those which reach the superior wall of the pharynx concur, with 
the glosso-pharyngeal and the pneumogastric, to form the pharyngeal plexus. 

B. Intermepiate Corp or tae Two Czrvican Ganeuia.—tThis cord 
leaves the inferior extremity of the superior cervical ganglion, lies close 
beside the pneumogastric nerve, which always surpasses it in volume, and 
descends to the entrance of the thorax, where it separates from the vagus 
nerve, and joins the inferior cervical ganglion. It neither receives or gives 
off any branch in its course. 

OC. Inrerion CrrvicaL Ganetion (Fig. 862, 2).— Generally thicker 
than the superior, this ganglion is placed within the costal insertion of the 
inferior scalenus. The right, always a little more anterior than the other, 
is applied immediately against the side of the trachea. That of the left side 
is separated from it by the cesophagus. Both are related, externally to the 
vertebral artery. . 

The inferior cervical ganglion is very liable to vary, and, become 
irregular in form. It is sometimes lenticular, at others more or less 
elongated, always stellate, and not unfrequently double. In the latter case, 
which is perhaps more frequent in the left than the right, its two portions 
are distinguished into anterior and posterior: the last forms the inferior 
cervical ganglion, properly called (Fig. 362, 2): the former is much smaller, 
and is bound to the other by a wide and short greyish band, constituting 
what has been designated in Man the middle cervical ganglion (Fig. 362, 3). 

Tn front, the ganglion which we are describing receives the cord inter- 
mediate to the two ganglionic enlargements in the region of the neck, either 
directly, or through the medium of the middle cervical ganglion, when that 
is present. It is continued backwards with the dorsal portion of the 
sympathetic chain. 

Aprrrrent BrancHEs.—These are two, proceeding from the cervical pairs. 

One is a thick nerve, satellite to the cervical vertebral artery, and lodged 
with it in the foramina of the cervical vertebra; it is formed by filaments 
emanating from the second, third, fourth, fifth, sixth, and seventh pairs of 


1 to 2, Cervical portion of the sympathetic chain ; 1, Superior cervical ganglion, in 
the middle of the guttural plexus; 2, Inferior cervical ganglion; 3, Middle 
cervical ganglion; 4, Intermediate cervical cord, intimately united at its middle 
portion with the pneumogastric nerve ; 5, Cardiac nerves; 6, Dorsal portion of the 
sympathetic chain; 7, Great splanchnic nerve ; 8, Lesser splanchnic nerve ; 9, 
Semilunar ganglion, centre of the solar plexus ; 10, Portion of the hepatic artery 
encircled by its plexus;,11, The splenic artery, ditto; 12, The gastric artery, 
ditto, 13, The anterior mesenteric artery, ditto; 14, Kidney, elevated, receiving 
the renal plexus; 15, The suprarenal capsule with its plexus; 16, Lumbo-aortic 
plexus; 17, Lumbar portion of the sympathetic chain ; 18, Posterior mesenteric 
plexus; 19, Branches from it passing to the anterior mesenteric plexus; 20, 
Spermatic plexus; 21, Branches going to the pelvic plexus; 22, Sacral portion of 
the sympathetic chain ; 23, Pelvic plexus; 24, Afferent branches furnished to the 
sympathetic by the spinal pairs; 24’, The cord which receives six of the cervicai 
yamuscules; 25, Pneumogastric nerve ; 26, Superior laryngeal ; the pharyngeal 
branch is seen to be detached from the pneumogastric a little below ; 27, Inferior 
laryngeal nerve of the right side; 28, That of the left side at the point where 
it bends round the arch of the aorta; 29, Nerves of the bronchial plexus; 30, 
Superior esophageal branch; 31, Inferior ditto; 32, Spinal nerve; 33, Hypo- 
glossal nerve; 34, Glosso-pharyngeal nerve, represented too thick. ; 


786 THE NERVES. 


cervical nerves, and thus carries in a mass, to the great sympathetic, the 

contingent of afferent nerve-fibres of the majority of these nerves 

(Fig. 362, 24’). ; ; . 
The other branch is an isolated one, proceeding from the eighth cervical 

air. 

: Besides these afferents, there ought to be noticed the filaments sent by 

the pneumogastrie nerve, and which join the middle cervical ganglion, when 

it is present. See the description of the pneumogastric nerve. 

Emercent Brancues.— These are detached from the posterior and 
inferior part of the ganglion, and for the most part proceed to the heart. 
Some extremely fine filaments go to the anterior mediastinum, or pass on to 
the collateral arteries of the brachial trunk. 

The cardiac nerves (Fig. 362, 5) cross the base of the pericardium, 
alongside the common aorta, and are then distributed to the tissue of the 
auricles and ventricles. Some follow the divisions of the pulmonary artery. 
and concur in the formation of the bronchial plexus. 

To arrive at the heart, these nerves accompany the axillary arteries and 
the trachea, giving rise, on the inferior face of the latter, to a very large 
fasciculus, named, in Veterinary anatomy, the tracheal pleaus ; this is single, 
and is traversed from behind to before by the two recurrent nerves, which give 
or receive from it numerous filaments. 

The cardiac nerves in the Horse are five in number; twa proceed from 
the left, and three from the right cervical ganglion. Of the first two, one is 
formed by easily-separated filaments, and is applied to the left brachial 
trunk of the anterior aorta, which it follows to its commencement. There 
it divides into several ramuscules; some of these pass into the furrow 
between the right auricle and the origin of the pulmonary artery; the 
others pass between the latter and the common carotid, to reach the root of 
the lung. This nerve furnishes very fine filaments to the anterior border of 
the heart. The second left cardiac nerve commences by two branches that 
leave the middle and inferior cervical ganglia; from their union results 
a long cord that is directed downward, backward, and to the right, crossing 
the lower face of the trachea; arrived at the right side of the posterior aorta, 
beneath the recurrent nerve, it is distributed to the heart and lungs. 

The cardiac nerves arising on the right side are thus disposed. The 
largest emerges from the middle cervical ganglion, and lies alongside the 
pneumogastric, bending with it beneath the axillary artery, and becoming 
detached a little beyond that vessel; here it receives ramuscules from the 
left recurrent and enters the base of the heart, after giving off some filaments 
that pass to the bronchial plexus. The second. much smaller, is also 
detached from the middle ganglion, receives some branches from the right 
recurrent, and is applied to the surface of the anterior aorta as far as the 
upper face of the auricles. Lastly, the third, as large as the preceding, 
proceeds from the right recurrent, the inferior cervical ganglion, and the 
pneumogastric ; it is imbedded in the heart, to the right of the aorta. 


3. Dorsal Portion of the Sympathetic Chain. 


__, The cord represented by this portion of the sympathetic chain leaves the 
inferior cervical ganglion, and extends from before to behind, towards the 
diaphragm, passing beneath the superior extremities of the ribs—or rather, 
below the vertebro-costal articulations, against which it is maintained by the 
pleura—and crossing the intercostal arteries. It is continued in the abdominal 


THE GREAT SYMPATHETIC NERVOUS SYSTEM. 787 


cavity by the lumbar portion, after passing through the arch of the superior 
border of the diaphragm, along with the psoas parvus. 

Along its course, this cord exhibits, at each intercostal space, a small 
fusiform ganglionic enlargement—seventeen in all. The two or three first 
are most frequently absent; but then the anterior extremity of the nerve 
has for some extent the appearance of a ribbon-shaped ganglion, which seems 
to be i ia the elongation, posteriorly, of the inferior grey mass of the 
cervical portion. 

ArrerEnt Branones.— Furnished by the inferior branches of the dorsal 
nerves, these ramuscules number from one to three for each ganglion. To 
proceed from the intervertebral foramina to the sympathetic, they traverse the 
superior extremity of the intercostal space, passing sometimes behind, some- 
times before, the arteries of that name. 

Emercent Brancnes.—A very few delicate branches pass to the pleure ; 
those which demand notice are the great and lesser splanchnic nerves. 

a. Great splanchnic nerves (Fig. 362, 7).— This commences to be 
detached from the dorsal chain towards the sixth or seventh ganglion, is 
directed backwards by the external side of that chain, receives an accessory 
branch from each of the enlargements it passes by. except the last two or 
three, and enters the abdominal cavity through the arch of the psoas parvus, 
where it usually looks like a small ganglionic mass; after which, it is 
inflected inwards, and terminates on the side of the aorta, between the cceliac 
and mesenteric trunks, by a second and enormously developed mass—the solar 
ganglion. The two solar, or semilunar ganglia, as they have also been 
designated, and which are the largest in the body, are elongated from before 
to behind, and flattened from above to below. They communicate with one 
another by means of a wide and thick greyish cord, which encircles, 
posteriorly, the trunk of the great mesenteric artery, and by a multitude of 
filaments which pass from the left to the right, in front of that vessel. From 
this arrangement results a single plexus situated at the inferior face of the 
aorta, between the origin of the two precited arterial trunks. ; 

This plexus, named the solar, receives some branches from the superior 
cesophageal cord of the pneumogastric nerve. It subdivides on its periphery 
into several secondary plexuses, which leave, as from a centre, the principal 
network, and whose ramifications, very large and numerous, proceed to the 
neighbouring organs in accompanying the arterial divisions, around which 
we see them interlacing and anastomosing in a very complicated manner. 
It is for this reason that there have been described separately: 1, A gastric 
plexus, going to the stomach, on whose parietes its branches anastomose 
with those of the pneumogastrics; 2, A hepatic plexus, destined to the 
liver, duodenum, pylorus, and pancreas; 3, A splenic plewus, one part of 
which passes to the spleen, the other to the | stomach ; 4, An anterior 
mesenteric plexus, the most considerable of all, is distributed to the same 
organs as the artery of that name; 5, A renal and a suprarenal pleaus : the 
latter two doubled, and scarcely distinct from each other, their terminal 
divisions arriving at the kidneys and suprarenal capsules. The termination 
of the filaments of these plexuses has been already described in the Splanch- 
i ee necessary to add to this rich nervous apparatus, the lumbo-aortic 
pleaus. formed by the large and numerous branches which spring from the 
solar plexus behind the great mesenteric artery, creep along the sides and 
the inferior face of the aorta, frequently anastomose with each other, and 
reunite at the posterior mesenteric plexus. 


788 THE NERVES. 


b. Lesser splanchnic nerve (Fig. 862, 8).—'This branch is composed of 
two or three tilaments that emanate from the last subdorsal ganglia, and 
which, instead of joining the great splanchnic nerve like the others, with 
which they communicate by one or two fine divisions, collect in a short thin 
cord, whose ramifications pass directly into the solar plexus, or are con- 
founded with the nerves of the kidney and the suprarenal capsule. 


4, Lumbar Portion of the Sympathetic. 


This is a cord similar to that of the dorsal portion, and provided with 
fusiform ganglionic enlargements equal in number to the pairs of lumbar 
nerves. This cord is applied against the psoas parvus, near the common 
inferior vertebral ligament, and is covered on the left by the aorta, on the 
right by the posterior vena cava. It is directly continued by the sacral 
portion of the sympathetic chain at the lumbo-sacral articulation. 

Arrerent BrancHes.—Furnished by the inferior branches of the lum- 
bar nerves, these ramuscules comport themselves exactly like those of the 
dorsal region. 

Emrercent Branowes.—These are short filaments, analogous to those 
which, by their union, constitute the splanchnic nerves. Their number is 
not constant, and is generally less than that of the ganglia. Two or three 
join the lumbo-aortic plexus; the others gain the origin of the small 
mesenteric artery, anastomose around it with the posterior extremities of 
the branches of that plexus, and thus form another single nervous network 
designated the posterior mesenteric pleaus (Fig. 362, 18). 

This plexus, in whose centre is a more or less voluminous ganglion, 
sends to the various branches of the small mesenteric artery ramifications 
destined for the walls of the small colon and the rectum. 

It supplies besides: 1. Two or three large branches which follow the 
posterior mesenteric vein, and join the anterior mesenteric plexus, after 
giving off some divisions to the tissue of the colic mesentery (Fig. 362, 
19). 

2. Satellite branches to the two spermatic arteries, constituting the 
plexus of that name (Fig. 362, 20). 

3. Two or thres long divisions (Fig. 862, 21) which enter on each side 
of the pelvis by passing beneath the external face of the peritoneum, and 
reach the lateral plane of the rectum, where they meet the filaments 
emanating directly from the inferior sacral nerves. From the anastomoses 
of these divisions results a rich nervous network, called in Man the hypo- 
gastric plexus, and which we have designated the pelvic plexus; this net- 
work is destined to all the organs contained in the pelvic cavity (Fig. 362, 
23). 


5. Sacral Portion of the Sympathetic. 


A continuation of the lumbar cord, this portion of the sympathetic chain is 
situated beneath the sacrum, to the inner side of the inferior sacral nerves. 
It offers four very elongated ganglia, which communicate with these nerves 
by one or more filaments, and which give rise to several very fine ramus- 
cules that are lost in the cellular tissue on the inferior face of the sacrum. 

Its posterior extremity, which terminates behind the great sympathetic, 
does not always comport itself in the same manner. We sometimes see it 
become attenuated to a very delicate ramuscule, which passes on to the 
median coccygeal artery, and anastomoses with that of the opposite side. 


THE GREAT SYMPATHETIC NERVOUS SYSTEM. 789 


But sometimes, also, this ramuscule cannot be distinguished, and the sub- 


sacral cord seems to be abruptly terminated by the filament of com- 
munication from the last sacral pair. 


Fonorrons.—The functions of the sympathetic are yet but little known, 
notwithstanding the labours of many physiologists, at whose head must be 
placed Claude Bernard. In a physiological condition, this nerve possesses 
an extremely obscure sensibility, but which may become very acute in 
pathological cases. It conveys to organs the unconscious motor exci- 
tations originating in the spinal cord; and through the filaments it 
furnishes to the vessels—the vaso-motor nerves—it holds under its control 
the circulatory phenomena, especially in the capillary plexuses, causing 
these canals to dilate or contract, and thus diminish or accelerate the flow 
of blood in them. By this action on the blood-vessels, it may have a 
secondary influence on the nutrition of the organs to which these vessels 
are distributed. 


DIFFERENTIAL CHARACTERS IN THE GREAT SYMPATHETIC OF OTHER THAN 
SOLIPED ANIMALS. 


In all the domesticated mammals, the general disposition of the great sympathetic is 
very similar; so that there are but few and slight differences to note. 

In the Ox, the cervical filament does not arise from the lower extremity of fhe 
superior ganglion, but from its middle portion; it is divisible into two or three filaments 
for a certain distance, after which it lies beside the pneumogastric. The ramuscule 
that leaves the lower end of the cervical ganglion is very large, and reaches the division 
of the common carotid, that which accompanies the internal carotid artery is also of a 
considerable size. (Ruminants have 13 thoracic and 6 lumbar ganglia. } 

In the Dog, the cervical sympathetic cord is closely united with the pneumogastric, 
and it is not possible to separate them from each other, as can be done in Solipeds and 
Ruminants. (In the Carnivora there are 13 thoracic and 7 lumbar ganglia.) 

The Pig has a superior cervical ganglion, which is fusiform and very long; at its 
lower extremity it gives off several filaments, one of which lies beside the pneumogastric 
in the cervical region, but separates from it to join the middle cervical ganglion, the 
others pass to the tenth nerve, and are confounded with it at the ganglionic enlargement 
it shows behind the pharynx. At the entrance to the chest, a branch separates from 
the pneumogastric, passes along with the axillary arteries, and finally enters the heart. 
This branch is perhaps formed by the filaments of the sympathetic that joined the 
. pneumogastric at the upper part of the neck. (The inferior cervical ganglion, according 
to Leyh, is completely isolated from the thoracic ganglion. The Pig has 14 thoracic 
and 7 lumbar ganglia. 


COMPARISON OF THE GREAT SYMPATHETIC OF MAN WITH THAT OF ANIMALS, 


It is divided and disposed as in animals. The cervical portion is composed of a 
superior fusiform ganglion, from which emerge many branches which have been studied 
with the greatest care. There are described: 1, Superior or intercranial branches; 2, 
External or anastomosing branches with the first four spinal nerves; 3, Internal or 
visceral branches, which mix with the pharyngeal and laryngeal filaments of the 
pneumogastric; 4, Anterior or external carotideal branches, which pass to the common 
carotid and the middle of a small ganglion, the intercarotid; 5, Posterior, muscular, or 
osseous branches. All these are present in the Horse. A cervical filament and two 
inferior ganglia—middle and inferior—complete this region, of which there is nothing 
more to be said. Oe he eee te hs : 4 : 

The thoraric portion is absolutely identical in its disposition with that of animals; it 
gives rise tu a great splanchnic nerve, and terminates in the semilunar ganglia. 

There are no differences to note in the lumbar and sacral portions. which we have 
described as the pelvic. 


53 


790 THE NERVES. 


CHAPTER IV. 


THE NERVOUS SYSTEM IN BIRDS. 


Protective Parts or .rHs Orrrsro-spinal Axrs.—The protective parts of the 
nervous centres are the same in all vertebrate animals; consequently, there is nothing 
to remark regarding those of Birds. The envelopes or meninges are three in number, 
isposed as in mammals. 

and ee falx cerebri is found in birds; in the Turkey it has the form of the segment of 
a circle, and extends from the middle of the interval of tie openings for the olfactory 
nerves to the tentorium cerebelli. The falx cerebelli is absent; the tentorium is small 
and sustained by a bony plate, and there are, in addition, two particular folds, one on 
each side, that separate the hemispheres from the tubercula quadrigemina.”—Cuvier. 
Owing to the absence of the falx cerebelli, the meninges of birds are closer together 
than those of Solipeds or Man. According to Leydig, the fulx cerebri is partially 
ossified in birds. 

Sprvat Corp.—In Birds, the spinal cord is perforated by a central canal, and also 
offers, as in mammals, two enlargements— a cervico-dorsal and lumbar. It is prolonged 
into the coccygeal vertebra, and thus furnishes anuther provf against the assertion of 
certain naturalists, who desire to establish a relation between the length of the spinal 
cord posteriorly, and the development of the coceygeal region. The two fasciculi of the 
ntedullary axis are separated from one another at the lumbar enlargement, and after- 
wards join in the sacral region. Between them is an elliptical space, the rhomboidal 
sinus, which is filled by transparent gelatinous connective substance—a kind of efflor- 
escence of the ependymis of the central canal. 

Encepuaton.—In a medium-sized Fowl, the encephalon weighs about 23 drams, and 
comprises the three portions present in the mammalia, — 2 eee 

The medulla oblongata is not divided into two sections by the pons Varolii, which is 
absent in birds; the crura cerebelli are immediately connected with the corpora 
restiformia. The lower face of the isthmus is very convex posteriorly, in front, the 
tubercula bigemina are united to each other by a comparatively large transverse cord, 
formed by the optic nerves intercrossing in the median line. The superior face is 
depressed above the cerebellum, so as to constitute a fourth ventricle, also shaped like 
the point of a pen: infront of this ventricle are the tubercula bigemina. ‘These are 
two voluminous tubercules separated from each other above, where they embrace the 
cerebellum, and salient on the sides of the iower fuce. They are hollow internally, and 
communicate with the aqueduct of Sylvius, the thalami optici are little developed. 

The cerebellum is almost reduced to the median lobe, the lateral lobes, situated 
behind and below it, being very small and conical. By its anterior extremity, this’ 
cerebral ganglion passes between the corpora bigemini, and touches the cerebral hemi- 

.spheres. The cerebellum is annulated transversely to its surface, and between the 
principal furrows are secondary ones, as in mammals. The white substance forms, in its 
interior, an arborisation in relation, by the number of its branches, with the simplicity 

observed on the surface of the organ. In the centre of the cerebellum of birds is a 
small cavity communicating with the fourth ventricles. 

The cerebrum, divided into two hemispheres by a shallow sulcus, has the shape of 
the heart on a playing card, more particularly when viewed on its lower face. The 
convolutions are absent on the upper and lateral faces of the organ, and on the inferior 
is a vestige of the fissure of Sylvius, which is directed obliquely forward and outward. 
The olfactory lobes are little developed, and are placed together in the median line. 

The two ventricles are confounded, there being ne corpus callosum nor septum 
lucidum. There is no reflected portion in the ventricle; consequently the hippocampi 
and mastoid lobules are absent; the corpora striata are, on the contrary. large and 

occupy nearly the whole floor of the ventricles. 

CeaniaL Nerves.—These are twelve pairs, as in mammals; and their origin is 
analogous, if not identical; the only trifling differences pertaining to the pons Varolii 
and the convexity of the lower face of the isthmus. 

Olfactory nerve.—We have mentioned above how this is formed at the anterior 
portion of the cerebral hemispheres. 

Optic nerve—It appears to be detached from the tubercula bigemini, and, after a 
very short course, to intercross with that of the opposite side. In certain birds, especially 
in the sna rapacious kinds, the optic nerves are constituted by fasciculi of undulating 

; nerve-tubes. 


THE NERVOUS SYSTEM IN BIRDS. 791 


Common motores oculorum.—Pathetici.—External motores oculorum.—There is nothing 
particular to be cited respecting these. 

Trigeminal nerve—This nerve divides into three principal branches, as in the 
domesticated animals. The ophthalmic branch has a nasal ramuscule that becomes 
superficial, and extends to the extremity of the beak; as well ag a third filament that 
is lost around the inferior orifice of the nasal cavities 

The superior maxillary issues from the cranium by the opening through which the 
lower maxillary nerve passes, creeps below the orbit, traverses the maxillary bone, and 
terminates on the sides of the beak by filaments that resemble the infra-orbital 
ramuscules of the Horse. 

The inferior maxillary furnishes two branches: one passes through the dental canal 
and arrives at the exteenity of the lower mandible; the other is tei in the sub- 
corneus integuments of the same. 

Facial nerve.—This is small in birds. “It is distributed to the muscles of the jaws 
and the small muscles which erect the ee of ue crest.” —Cuvier. 

Glosso-pharyngeal nerve.—This calls for no remark. 

Pneumogastric nerve-—There are few differences observed in this; it is as extensive 
as in mammals, and its anastomoses and relations are nearly the same. It is not en- 
tirely formed at its exit from the cranium, and always offers two or three constituent 
filaments that join it, and are sel he at some distance from the point of emergence. 
The recurrents furnish ramuscules to the crop. 

Spinal accessory nerve.—This likewise has a medullary root that appears at the 
third cervicul vertebra ; it runs along with the vagus nerve to become superficial. 

Hypoglossal nerve—The same origin as in quadrupeds. Where it crosses the pneu- 
mogastric, it detaches a long filament that passes along with the jugular vein towards 
the chest. On the sides of the larynx it bifurcates; one branch proceeds forward 
beneath the tongue, the other follows in the same direction, but on the upper surface of 
that organ. 

re Nerves.—We need only notice the nerves of the wing and pelvic limb, the 
others being disposed in a similar manner to those above described. 

Brachial plecus.—Three principal branches—the last cervical and first two dorsal— 
form this plexus in Palmipeds; in the Gallinacex there are four —the last three 
cervical and first dorsal. These branches anastomose beneath the deep face of the 
scapulo-humeral articulation. When fully constituted, the plexus gives off some col- 
lateral ramuscules, and terminates by two fasciculi of branches. ‘The first collateral 
goes to the deep pectoral muscle: another is distributed to the muscles. surrounding the 
head of the humerus, as well as to the articular capsule. The fasciculi of terminal 
branches may be distinguished, after their situation, as anterior and posterior. The 
latter represents the internal cutaneous and radial nerve; it gives off muscular and 
cutaneous ramuscules that extend to the digits at the extremity of the wing. The 
anterior fasciculus is larger, and is also extended to the whole of the limb, being ex- 
pended in motor and sensitive filaments; near its origin it furnishes ramuscules to the 
superficial pectoral muscle. This aes represents the median, ulnar, and anterior 

i cutaneous of mammals. . R 
ag eee pee ee lumbar and four sacral nerves constitute this plexus. 
In the Fowl it is distinctly divisible into two portions, an anterior and posterior, 
ST ete pata composed of the lumbar branches and a portion a Ls Eree 
sacral: their fusion takes place on the salient bony ridge that separates the lumbar 
from the sacral regions. It gives origin to four or five branches, among: haa are 
clearly discernible: 1, A filament to the fascia lata muscle i 2, - sige 2 Femor eK 5 
3, An internal saphenous nerve that descends to the leg; 4, An obturai ae - 
latter is very slender, and directed downwards and backwards, passing into the muscle 
urator foramen. 
CS ne comprises a portion of the first sacral, and the whole of the 
ae ding nerves. These are directed outwards, towards the sciatic notch, where 
i ae diericig their course in the interior of the pelvis, they are surrounded by the 
ey ae kid The distribution of this portion of the plexus resembles that of 
tesneaet Oe ina ce leaving the sciatic notch, it gives off the anterior and posterior 
the Horse. Ae ee pe lon 4 branches that lie together as far as the gemelli; these 
“boas — 1 “The great sciatic, with a ramuscule for the gemelli and the posterior 
eT Gaacleat 2, The external popliteal, which, outside the superior extremity of the 
leg, divides into the musculo-cutaneous and anterior tibial nevre 


BOOK VII. 


AppPaRATUS OF SENSE. 


Amone the nerves described in the preceding book, those which have been 
designated sensory nerves have for their principal, or even exclusive function, 
the carrying to the brain the excitations derived from the surrounding 
physical world. These nerves are, therefore, the essential instruments of 
sensation, and the organs to which they are distributed constitute the 
APPARATUS OF THE sENSES. These are admirably disposed for the re- 
ception of the cerebral excitations, and are five in number : the apparatus 
of touch, taste, smell, vision, and hearing. The principal charateristics of these 
will be briefly enumerated 


CHAPTER I. 


APPARATUS OF TOUCH. 


Tur sense of touch is destined for the appreciation of tactile sensations, 
and, incidentally, those resulting from variations of temperature. The 
apparatus composing it is formed by the peripheric radicles of the nerves 
of general sensibility distributed in the skin: the resisting membrane 
closely investing the whole of the body, and continuous, at the margin 
of the natural openings, with the mucous or internal membrane. 

The entire skin, therefore, represents the organ of touch; but, as in Man, 
this membrane has certain privileged regions which are more active than 
others in the exercise of this faculty : these are the four extremities and the 
lips. 

The structure of the skin, though pertaining to general anatomy, shall be 
studied here somewhat in detail, and then the arrangement of its appendages 
—the hair and horny productions—will be examined. 


Agticte I.—Tuer Sxin Proper. 


The skin, properly speaking, is composed of two layers: the derma and 
epidermis. 

Tue Derma.—The derma or chorion (corium cutis), forms nearly the 
entire thickness of the membrane. Its inner face adheres more or less 
closely to the subjacent parts, through the medium of a cellulo-adipose 
expansion. Its external face, covered by the epidermis, which it secretes (or 
forms), is perforated by openings through which the hairs pass, or through 
which the secretion of the sudoriparous and sebaceous glands is thrown out 
upon the surface of the skin; this external face also shows a multitude of 
little elevations termed papillw, in which the majority of the nerves terminate 


THE INTEGUMENTARY APPENDAGES. 793 


The derma is not of the same thickness everywhere, being much thinner 
where it is protected from external injury, as on the under-surface of the 
belly, the inner side of the legs, thighs, etc.; it is also thin around the 
margin of the natural openings, to permit the transition between the two 
membranes, and endow these apertures with their necessary dilatability. 


Fig. 363. 


SECTION OF HORSE’S SKIN; FROM WING OF THE NOSTRIL. 

E, Epidermis ; p, Derma; 1, Horny layer of the epidermis; 2, Rete mucosum; 3, 
Papillary layer of the derma; 4, Excretory duct of a sudoriparous gland; 5, 
Glomerule of a sudoriparous gland; 6, Hair follicle; 7, Sebaceous gland; 8, 
Internal sheath of the hair follicle 9, Bulb of the hair: 10, Mass of adipose 
tissue, 


Srructure—The derma is composed of fasciculi of conjunctival tissue 
interwoven and matted in a solid manner, and in the meshes of which are some 
smooth muscular fibres, which, by their contraction, produce the condition of 
the skin known as the cutis anserina (goose-skin). Somewhat loosely woven in 
its deepest part to form the reticular layer (or corium), the derma contains 
the roots of the pilous follicles, the sudoriparous (or sweat) glands, and small 
masses of adipose tissue ; superficially, its structure is very condensed, to 
constitute the papillary layer, whose uppermost 
limit forms an amorphous border. 

The papille are of two kinds—vascular 
and nervous, and are regularly arranged in 
parallel series: they are most numerous in 
those parts of the skin specially destined for 
the exercise of touch, as at the lips, in the 
keratogenous membrane (of the foot), and 
other parts where sensibility is very acute— 
such as the scrotum, sheath, and integuments 
of the penis. The papillary prolongations of 
the derma are conical or fungiform, and pedi- Ged oa a oe er 
culated; their dimensions are very variable ; 
measuring from +},th to s},th of an inch in length, and from —4,th to 


Fig. 364. 


794 THE APPARATUS OF THE SENSES. 


an inch in width at their base. The nervous papille are the 


1th of ; 
ne touch, and contain either the corpuscula tactis (or awile bodies) of 


organs of 


Meissner or of Kraiise. 
Fig. 365. 


The Srpacnous GLanps 
lie beside the hair follicles, 
each hair being flanked by 
two glands. These small 
organs are composed of a 
very granular epithelium, and 
are usually oval in shape. 
(They are imbedded in the 
substance of the derma, and 
present every degree of com- 
plexity, from the simplest 
follicle to the compound 
\ lobulated gland. In some 
\\ situations, their excretory 
ducts open independently on 
the surface of the epidermis. 
Those associated with the 
hairs are raceiform and lobu- 
lated, consisting of glandular 
vesicles, which open by short 
pedunculated tubuli into a 
common excretory duct, and 
the latter, after a short course, 
into the hair follicle. In some 
parts the ducts are short and straight ; in others, where the skin is thick, they 
are spiral, They are lined by an inversion of the epidermis, which forms a 
thick and funnel-shaped cone at its commencement, but soon becomes soft 
and uniform. Sebaceous glands are met with in all parts of the body, but 
are most abundant in those parts which are naturally exposed to the influence 
of friction, or require to be supple. Miller 
found in the Pig a special cutaneous gland, 
somewhat resembling the sebaceous glands. 
It is situated on the inner and posterior aspect 
of the knee, and is from 3ths to 2 inches in 
length, and from }$ to 4 inch in width. In the 
Sheep, there is found in the skin between the 
claws, a particular inversion of the integument 
that forms a small elongated pouch, curving 
upwards and terminating in a cul-de-sac. This 
is the interungulate gland, sinus, or biflea canal 
(sinus cutaneus ungularum) ; it secretes a viscid 
matter from glands which, according to Erco- 
lani, are analogous to the sebaceous glands. 
The pouch is lined with very fine hairs.) 


TACTILE PAPILLE FROM THE SKIN, SHOWING THE 
tactile corpuscles, OR “ AXILE BODIES.” 


A, In the natural state; B, Treated with acetic acid. 


INTERUNGULATE GLAND OF SHEEP, 

u, Inner aspect of first phalanx; b, 
Hoof, or claw; v, Interungulate 
gland; d, Orifice of its duct. 


The Suporrparous Guanps are deeper situ- 
ated than the last (passing even into the 
subcutaneous areolar tissue, where they are 
surrounded by adipose cells). They consist 
of a convoluted tube (or several tubuli pro- 


duced by dichotomous subdivision) imbedded in the reticular layer of the 


THE INTEGUMENTARY APPENDAGES. 795 


derma (or corium), and forming an elliptical glomerule, generally lying 
obliquely to the surfate of the skin in the Horse. The excretory canal is 


detached from this glomerule, and passes 
through the derma and epidermis in a spiral 
manner. 

The blood-vessels form a very rich network 
in the papillary layer of the derma, and also 
surround the sebaceous and sudoriparous 
glands. The lymphatics are disposed like the 
capillaries. 

The nerves are arranged in two layers: 
one loosely distributed in the corium , the 
other is very close, and is lodged in the papil- 
lary layer of the derma, which is traversed 
by recurrent fibres giving off tubes that pass 
into the nervous corpuscles of the papilla, 


VERTICAL SECTION OF THE SKIN TREATED WITH A 
SOLUTION OF CAUSTIC SODA, showing the branches of 
cutaneous nerves, a, 6, inosculating to form a terminal 
plexus, of which the ultimate ramifications pass into 
the papilla, ¢, ¢ & 


Eprwrrmis.—The epidermis is a thin pel- 
licle, covering the superficial face of the 
derma; it is destitute of nerves and blood- 
vessels, and is formed of cells which are 
being continually deposited on the corium ; 
these cells become flattened in layers as they 
are pushed up from the latter, and are des- 
troyed by friction on the surface of the skin. 
The deep face of the epidermis is moulded 
on the upper surface of the derma; con- 
sequently, it lodges the papilla, and dips into 
the follicles and excretory ducts of the glands 
of the skin; its external face is not a very 


Fig. 368. 


SUDORIPAROUS GLAND, MAGNIFIED 
40 DIAMETERS. 


u, u, Conterted tubes composing the 
gland, and uniting im two ex- 
cretory ducts, 6, 6, which joi 
into one spiral canal that per- 
forates the epidermis at c, and 
opens on its surface at d; the 
gland is imbedded in fat vesi- 
cles. @, 


+ repetition of the surface of the derma, and is covered with hair. The 
denne tends to equalise, and to fill up, the depressions existing between 


the papille. 


796 THE APPARATUS OF THE SENSES. 


Srructure.—The epidermis comprises two layers, which are not very 
distinct from each other in the Horsc. The deep lajer, or rete mucosum. is 
composed of soft, nucleated, pigmentary cells, which are round on the surface 
of the derma, and polyhedric elsewhere. The superficial, or horny layer, is 
constituted by hard, horny, flattened cells, which still contain some pigment- 
granules, and are insensibly confounded with those of the rete mucosum. 

(The theory of growth of the epidermis is believed to be as follows —a 
layer of plastic lymph is thrown out on the surface of the derma, and is 
converted into granules, which are termed cell-germs, or cytoblasts. These 
imbibe serum from the lymph and adjacent tissues, so that the outermost 
covering of the cytoblast is gradually distended ; the latter becomes a cell, 
and its solid portion, which always remains adherent to some point of the 
inner surface of the cell membrane, forms the nucleus of the cell. Within 
this nucleus one or more nuclei are developed; these are named nucleoli. 
The process of imbibition continuing, the cell becomes more or less spherical ; 
so that, after a certain time, the papillary layer of the derma is covered bya 
thin stratum of spherical cells pressed closely together, and corresponding 
with every irregularity of the papille. New cells being continually produced 
before the formation of the others has been quite completed, these are removed 
in layers further and further from the surface of the derma, and becoming 
subjected to the influence of physical laws, their fluid contents evaporate; 
they collapse, flatten, and gradually assume an elliptical shape; then they 
are a mass of completely flat cells, with an included 
nucleolated nucleus, and finally become a thin mem- 
branous scale, in which the nucleus is scarcely appa- 
rent). 

In Solipeds and other animals, the epidermis is 
generally dark-coloured, from the presence of pig- 
ment corpuscles, the number of which increases with 
their depth in the membrane. This coloration is 
intended to prevent the rubefacient effects of the 
heat of the sun’s rays, by augmenting the absorb- 
ing and dispersing power of the cutaneous surface. 
In the majority of cases, this coloration is absent in 
the Sheep, whose skin is protected by a thick fleece; 
and also in the Pig, whose habits in the wild, as in 
a domesticated condition, keep it out of the direct 


OBLIQUE SECTION OF EPI- 
DERMIS, SHOWING THE 
PROGRESSIVE DEVELOP- 
MENT OF ITS COMPO- 
NENT CELLS, 


a, Nuclei resting upon the 
surface of the derma, f ; 
these nuclei are gradu- 
ally developed into cells 
at}, c, and d, and the 
cells are flattened into 
lamellz, forming the 
outer surface of the epi- 
dermis, e. 


(The functions of t 


(The f he skin are, as we have seen, 
addition, it is eminently protective. 


action of the sun. 

(In some regions of the body of all animals, the 
skin forms folds, as at the junction of the fore-limb 
with the body, the flank, and between the thighs. 
In the Cow, it forms the large pendulous layer at 
the throat and breast, known as the “ dewlap ;” and 
in the Goat and Pig, it not unfrequently constitutes 
teat-like prolongations depending from the throat, 
which nearly always contain a small cartilaginous 
nucleus and some muscular fasciculi. The thickness 
of the epidermis is sometimes greatly increased by 
wear and friction, as we frequently see in the skin 
covering the knees of Sheep, etc.) 
tactile and secretory ; in 
Its secretory action is always more or 


less active, but the production of perspiration is greatest when the body is 


THE {NTEGUMENTARY APPENDAGES. 797 


at a high temperature, as during active exertion; at other times the perspira- 
tion is insensible. In this respect, the skin has intimate sympathetic relations 
with other organs which have somewhat analogous functions, such as the 
lungs, kidneys, intestines, etc., and when its function is disordered or 
checked, it induces alterations in the secretions of one or all of these organs. 
The skin is also the seat of a constant and important respiratory action, as 
it absorbs oxygen and throws off carbonic acid, and any interruption to this 
process is injurious.) 


ArticLe II.—Aprrenpacrs oF tHe SxEin. 


The appendages of the skin are hairs and horny productions, dependents 
of the epidermic layer. 
HAIRS, 


The hairs are the filaments which, collectively, form the external covering 
of the skins of animals. 

In the Horse, the bristly appendages known as horse-hair should be 
distinguished from the hair proper; the latter are fine and short, particularly 
in the regions where the skin is thin, imbricated on each other, and spread 
over the entire surface of the body in a continuous layer which is designated 
the coat ; the former are long and flowing, occupy the summit of the head, 
where they constitute the forelock, the upper border of the neck, where they 
form the mane, and cover the caudal appendage with a splendid tuft, the 
tail. Some of these also form special organs on the free margin of the 
eyelids, and are termed eyelashes; while others inserted about the lips and 
below the eyes, are named tentacula. (The eyelashes are chiefly implanted 
in the upper lid. The hairs of the tail are the longest and strongest in the 
body. These particular hairs also grow on the posterior aspect of the 
limbs, generally from about the knees and hocks to the hoofs; at the 
sesamoid bones they constitute a long tuft, the fetlock, which surrounds 
the horny growth named the “ergot.” "These “ foot-locks” are peculiar to 
the Horse, and vary in length and coarseness with the breed of the animal.) 

When the hair is fine, long, and wavy, it forms wool ; and when straight 
and rigid, as in the Pig, it is known as bristles. 

In the Ass and Mule, the forelock and mane are rudimentary or absent, 
and the hair of the tail is limited to a small tuft at the extremity of the 
organ in the former animal, while in the latter it is much less abundant than 
in the Horse. 

In the Ox, these hairs are not present, except at the extremity of the 
tail, as with the Ass. 

There are scarcely any other animals which have other hairs than those 
composing the coat. 

(The ordinary hair of the coat is soft and elastic, inclined in particular 
directions, and varies in length not only according to the regions of the 
body on which it grows, but also according to the season or climate. In 
the Horse, the direction of the hair of the coat gives rise to curiously-formed 
waves, lines, and circles, the most constant of which is on the forehead. . 

In the Cow, the hair is frizzly on the forehead ; on the posterior part of 
the thighs it has a particular direction, while on the outer side it passes 
downwards, and from the posterior part of the mamme it ascends as high ag 
the vulva; this characteristic disposition forms what the French have 
termed écussons, by which some have pretended to recognise the lactiferous 
qualities of the animal. 


( 


798 THE APPARATUS OF THE SENSES. 


In the Sheep, real hair, not wool, is found on the lower part of the face, 
and the extremities of the limbs. 

In the Goat, the hairs of the beard are very long, and compose a dis- 
tinctive tuft; this animal has also a fine crisp duvet or down beneath the 
ordinary hair. ; ; 

In the Pig, the bristles are very strong in the region of the back: in old 
animals they are usually bi- or trifurcated at their free extremity ; there 
also exists a fine soft hair on this animal. It has no tentacular hairs, 

In the Dog, the length, fineness, and consistency of the hair depends on 
the breed. 

In the Cat, the hair, in some breeds, as in the Angora, is remarkable for 
its length and softness. This creature has the tentacula enormously 
developed as a moustache. 

In none of these animals is there a “ foot-lock.”) 

Srructure.—The hairs are implanted in the texture of the derma, and 
sometimes even in the subjacent tissues, their base being enclosed in a 
follicle, at the bottom of which their elements are developed. It is therefore 
necessary to study: 1, The structure of the hair; 2, That of the hair- 
follicle. : 

1. The hair presents a free portion, the shaft, and another concealed in 
the follicle, the root; the latter widens at its base—the bulb of the hair—to 
embrace the papilla or hair-germ. 

Three superposed layers compose a hair. The epidermis is a thin 
lamella of horny flattened cells, imbricated like tiles on a roof. Its elements 
are marked on the surface of the hair by shaded lines anastomosing to form 
a network ; they enlarge, and become more apparent under the influence of an 
alkali. The epidermis belongs to the shaft and a portion of the root ; near the 
bulb it is replaced by soft nucleated cells, which are implanted vertically. 

The cortical substance forms the largest part of the thickness of the hair. 
It is striped longitudinally, and provided with pigment granules, whose 
number varies with the colour of the coat. In white hairs these granulations 
are absent, but there are found in them, as well as in coloured hairs, small 
spaces containing air, and which exhibit a dark colour under the microscope. 
Treated by potass or sulphuric acid, the cortical substance is reduced to 
elongated spindles, which again may be decomposed into epithelial lamellea— 
narrow, and with nuclei. On arriving at the root, the cells change their 
character, becoming polyhedric, filled with fluid, and exhibiting a perfectly 
distinct nucleus and more or less pigment. The medullary substance occupies 
a narrow irregular cavity in the centre of the hair, extending from the bulb 
or termination of the root, to the point. It has for its base rectangular, 
rarely circular, cells, which, according to Kélliker, contain fat granulations 
and air globules. 

2. The hair-follicle is a narrow cavity, slightly contracted at its orifice 
and dilated at the bottom, where the hair papilla is placed. It is a simple 
involution of the skin, as its structure demonstrates. It presents, externally, 
a loose conjunctival layer, analogous to the reticular layer of the derma; 
next, an internal dermic layer, dense and close like the papillary layer of 
the skin ; an amorphous limiting membrane; an epidermic zone, the external 
sheath of the hair, formed by cells, similar to those of the rete mucosum ; and 
a second epidermic zone, the internal sheath of the hair, which repeats the 
horny layer of the epidermis, and is confounded with the termination of the 
epidermis of the hair towards the lower third of the follicle. 

The papilla or hair-germ, is a small, conical, vascular, and nervous 


THE INTEGUMENTARY APPENDAGES. 799 


prolongation rising up into the hair-bulb. It furnishes tho hair with 
nutrition and the elements of growth. The walls of the follicles of the 
large hairs, or tentacula, which garnish the lips of the Horse, or bristle from 
those of the Cat, are provided with nervous ramifications which endow these 
appendages with a high degree of sensibility, and enable them to play an 
important part in the exercise of touch. 

Two sebaceous glands, and a smooth muscular fasciculus, are annexed to the 
pilous follicle. The sebaceous glands, which have been already described, 
open into the sheath of the hair by a small excretory canal, which traverses 
the fibrillous walls of the follicle. The muscular fasciculus is situated on 
the side to which the hair and its follicle are inclined ; it arises from the 
superficial face of the derma, and terminates at the bottom of the follicle, 
which it erects by contracting. When the fasciculi contract over a wide 
surface, the extent of the skin is diminished, and the hairs are erected and 
partially ejected from their tollicles (producing the cutis anserina). 

(The formation of a hair is identical with the formation of the epidermis 
by the papillary layer of the derma. The capillary plexus of the follicle 
throws out plastic lymph which is converted into granules, then into cells 
which become elongated into fibres. The cells that are to form the surface 
of the hair, are converted into flat scales that inclose the fibrous structure of 
the interior. As these are successively produced, they overlap those pre- 
viously formed, and give rise to the waving lines seen on the circumference 
of the hair; this overlapping also causes the roughness experienced in 
drawing a hair between the fingers from its point to the bulb. The latter 
is the newly-formed part of the hair, its expanded form being due to the 
greater bulk of the fresh-cells. 

The colour of the hair-is very varied in animals, ranging from black to 
white, red and brown, with all the intervening shades. The tint also 
changes at different periods of life, being sometimes altogether altered 
between the juvenile and adult periods; dark-coloured Horses becoming 
light-coloured as age advances. Besides. it is never uniform in the same 
animal ; black Horses not unfrequently having white patches and diverse tints, 
with other dissimilarities. The disease termed “ melanosis” is very common 
in old white Horses which were previously grey, and is supposed to be due 
to the localization of the black pigment at certain limited points. The hair 
grows according to the climate, seasons, food, etc.,and varies with the species 
and breed. The coat in every animal is shed at certain times, and is replaced 
by new hairs. 

The hair preserves the skin from unhealthy external influences—wet 
and cold for example. It is a bad conductor of heat, and therefore keeps 
the body warm. The tentacula are very useful as tactile organs: while the 
mane, forelock, and tail keep away insects, and the long hairs of the fetlock 
and pastern protect these parts from the injurious effects of cold and wet, 
and the action of foreign bodies.) 


HORNY PRODUCTIONS. 


(Preparation —The hoof and its contents may be examined by sections made in different 
directions. The hoof can be removed by prolonged maceration, or by roasting on a fire, 
when it may be cut and torn off by means of the farrier’s knife and pincers.) 

The horny tissues form several groups the first comprises the horns of 
Ruminants; the second, the so-called chesnuts of Solipeds; the third, the 
protective layer enveloping the digital extremities, and constituting the claws 
of Carnivora, the Pig, Ox, Sheep, and Goat, and the hoofs of the Horse, Ass, 


800 THE APPARATUS OF THE SENSES. 


and Mule. These latter productions, ranking as they do among the most 
important organs of the locomotory apparatus of Solipeds, will first receive 
notice. 


1. The Hoof of Solipeds. 


The hoof of Solipeds is an extremely important study, because of the 
numerous diseases which affect this region. Consequently, it has been the 
subject of several voluminous works, to which the student must be referred 
for a more complete description of its organisation ;' as we cannot do more 
here than give some essentially descriptive details, necessary to fill up the 
outline that we have traced out. 

We will at first glance at the parts contained in the hoof, returning 
afterwards to a description of the horny case itself. 


Fig. 370. a. The Parts Contained in the 
Hoof. 


Proceeding from within to 
without, we find, in the interior 
of the horny box: 1, The 
third phalanx, navicular bone, 
and lower part of the second 
phalanx, forming the articula- 
tion of the foot; 2, The four 
ligaments that bind this articu- 
lation; 3, The tendon of the 
common extensor of the pha- 
‘langes which covers the articu- 
lation in front, and that of the 
perforans which supports it 
behind, in becoming inserted 
into the pedal bone, after gliding 
over the posterior surface of 
the navicular bone; 4, The 
complementary apparatus of the 
third phalanx; 5, The matrix 
of the hoof, or keratogenous 

membrane—a continuation of 

ay Anterior extensor of the phalanges, or extensor the derma covering the digital 
pedis; 2, Lateral extensor, or extensor suffraginis ; : 

3, Capsule of metacarpo-phalangeal articulation ; region. To these parts must 

4, Large metacarpal bone; 5, Superficial flexor of be added the vessels and nerves. 

the phalanges, or perforatus; 6, Deep flexor, or The description of the bones 


perforans; 7, Sheath; 8, Bursa; 9, Sesamoid been given at pa 
bone ; 10, Ergot and fatty cushion of fetlock; 11, has a pages 84, a 


Crucial ligament; 12, Short sesamoid ligament ; 86 ; . . ' 
13, First phalanx; 14, Bursa; 15, Second pha- Of the articulation and its 
lanx; 16, Navicular bone; 17, Plantar cushion; ligaments, at pages 157, 158 ; 
18, Third phalanx; 19, Plantar surface of hoof; Of the tendon of the an- 
20, Sensitive or keratogenous membrane of third : 
ea a g terior extensor of the phalanges, 


at page 268 ; 


LONGITUDINAL MEDIAN SECTION OF THE FOOT. 


Of the perforans tendon, at page 286 ; 
Of the arteries, at pages 553, 554, 555; 


; * See particularly, among the most recent and complete French works, the ‘Traité de 
YOrganisation du Pied du Cheval.’ by M. H. Bouley. (See also the still more recent 
work by Leiserinz, ‘Der Futz des Pferdes,’ Dresden, 1870. Also a long series of papers 
by me on this subject in the ‘ Veterinarian’ for 1871-2.) 


THE INTEGUMENTARY APPENDAGES. 801 


Of the veins, at pages 612 to 616 ; 

Of the nerves, at pages 762, 763. 

It remains to notice the complementary apparatus of the third phalana, 
and the keratogenous membrane. 

A. Complementary APPARATUS oF THE PepAL Bonz.—-In the indication 
we gave of this apparatus at page 85, we’ said that it was composed of two 
lateral pieces—the fibro-cartilages, united behind and below by the plantar 
cushion : a fibrous, elastic mass, on which the navicular bone rests, through 
the medium of the perforans tendon. We will take this distinction as the 
basis of our study. 

1. Frero-cartTILaces OF THE PEDAL Bonz.—Each of these pieces re- 
presents a plate flattened on both sides, having the form of an oblique-angled 
parallelogram, and prolonged behind the third phalanx. The eaternal 
face is convex, and pierced with openings for the passage of veins; it 
slightly overhangs that of the pedal bone. The internal face is concave, 
channeled by vascular furrows, and covers, in front, the pedal articulation, 
and the synovial cul-de-sac which projects between the two lateral ligaments 
of that joint ; below and behind, it is united to the plantar cushion, either 
through continuity of tissue, as at the in- 
ferior border, or by fibrous bands passing 
from one to the other. The upper border, 
sometimes convex, sometimes rectilinear, is 
thin and bevelled like a shell; it is separated 
from the posterior margin by an obtuse. 
angle, in front of which this border is often 
broken by a deep notch that gives passage 
to the vessels and nerves of the digital por- 
tion. The inferior border is attached, in 
front, to the basilar and retrossal processes 
behind the latter, it is reflected inwards to 
become continuous with the tissue on the 
lower face of the plantar cushion. The 
posterior border is oblique from before to 
behind, and above to below, and joins the 
preceding two. The anterior border is 
oblique in the same direction, and is united = HORIZONTAL SECTION OF THE 
so intimately with the anterior lateral liga- HORSE'S FOOT, ; 
ment of the pedal articulation, that it cannot 1+ Front, or toe of the hoof; 2, Thick- 

j . ness of the wall; 3, Lamine; 4, 
be separated from it except by an artifice — Iysertion of the extensor pedis; 5, 
of dissection. It sends to this ligament,and 0s pedis; 6, Navicular bone; 7, 
to the tendon of the anterior extensor. of Wings of the os pedis; 8, Lateral 
the phalanges, a fibrous expansion that be- OL Pep cui Gee 
comes fused with that of the opposite side. of the wall, or “bar;” 12, Horny 

The fibro-cartilages comprise in their frog. ee : 
structure a mixture of fibrous and cartilagi- 
nous tissue, though the mixture of these is far from being perfectly homo- 
geneous, or everywhere in the same proportions. ; 

The cartilages of the fore-feet are thicker and more extensive than those 
of the hind ones. 

(The lateral fibro-cartilages are peculiar to Solipeds.) 

9, Puantar Cussion.—The plantar cushion is a kind of wedge, situated 
in the space between the two cartilaginous plates of the third phalanx, and 
between the perforans tendon and the lower part of the horny box. Its shape 


Fig. 371. 


802 THE APPARATUS OF THE SENSES. 


allows it to be considered as having an antero-superior and an infero-posterior 
face, a base, summit, and two lateral borders. 

The antero-superior face is moulded on the aponeurotic expansion of the 
perforans tendon, and is “covered by a cellulo-fibrous membrane, the proper 
tunic of the plantar cushion, which is continuous, on its inner face, with the 
fibrous septa by which this organ is traversed, and adheres by its external 
or anterior face to the reinforcing sheath interposed between it and the 
perforans tendon.”—Bouley. This expansion is prolonged, above, to the 
fetlock, where it is confounded with the superficial fascia of the meta- 
carpal region; it is margined, laterally, by two 
small, very strong ligamentous bands which, at 
their middle portion, cross, in a very oblique 
manner, the fasciculus formed by the vessels and 
nerves of the digit. Each of these bands is fixed, 
superiorly, to the base of the rudimentary digit 
known as the ergot, and to the knob of the lateral 
metacarpal bone; their inferior extremity is at- 
tached within the retrossal process. 

The infero-posterior face of the cushion is 
covered by the keratogenous membrane, and pre- 
sents at its middle the pyramidal body, a promi- 
nence exactly like that of the frog, to which it 
corresponds. It shows, then, in front, a single 
conical prolongation, and behind, two divergent 
prominences separated by a median excavation. 

The base of the apparatus lies behind, and is 
inclined upwards; it is divided by a depression 
into two lateral masses—the bulbs of the plantar 
cushion—on the inside of which the posterior 
prominences of the pyramidal body reach, and 
LOWER FACE OF THE norsr’s Which become confounded, outwardly, with the 

FOOT, THE HooF BEING Re- posterior and inferior angle of the cartilaginous 
MOVED. plates. This portion of the cushion is, like the 
1, Heel; 2, Coronary cushion; anterior face, covered by a cellulo-fibrous expan- 
3, Branch of the plantar gion, which separates it from the skin of the pas- 
aes bp oka | tern; this expansion is attached, by its lateral 
Velvety tissue of the sole. margins, to the posterior border of the cartilages, 
and continued, superiorly, on the surface of the 

anterior expansion, with which it soon unites. 

The summit (point or apex) forms a sharp border, more or less regularly 
convex; it is fixed into the plantar face of the pedal bone, in front of the 
semilunar ridge and the insertion of the perforans tendon, with which the 
plantar cushion mixes its fibres at this part. 

The lateral borders are wider behind than before, in consequence of the 
wedge-like shape of the whole organ; they are continuous with the inner 
face of the lateral cartilages, as already indicated in describing the latter. 

The organisation of the plantar cushion differs much from that of the 
cartilages. It has for its base a fibrous structure, continuous with that which 
constitutes the fundamental framework of these ; this structure is very close 
towards the infero-posterior part of the organ, and becomes gradually looser 
as it leaves this region; the meshes it contains are filled with a yellow pulp 
composed of fine, elastic, and connective fibres, in the midst of which some 
adipose cells are found. (I have attentively examined this yellow pulp, and 


THE INTEGUMENTARY APPENDAGES. 803 


can perceive that it is essentially constituted by adipose tissue.) Numerous 
blood-vessels and nerves complete this structure. 

B. Tue Keratocenovs Mremsrane, orn Suscornevs Intecument.—The 
keratogenous membrane envelops the extremity of the digit, by spreading 
over the terminal expansion of the tendon of the extensor pedis, through the 
medium of a fibrous fascia—a dependency of the lateral cartilages; and also 
over the inferior moiety of the external face of these cartilages, the bulbs of 
the plantar cushion, pyramidal body, anterior part of the plantar face of the 
third phalanx, and over the anterior surface of the same bone. It covers all 
these parts like a sock, and the hoof incloses it, asa shoe does the human foot. 

This membrane becomes continuous with the skin of the digital region 
at a circular line that intersects the middle portion of the second phalanx, 
and inclines obliquely downward from behind to before. Below this line, 
in front and laterally, the subungular tissues form a semicylindrical pro- 
tuberance, covered with villi, and designated the “bourrelet.” (This 
elastic prominence has received several most inappropriate names from 
English farriers and hippotomists, such as “coronary ligament,” “ coronary 
substance,” “ cutiduris,” etc. From its function, structure, situation, and its 
analogy to the plantar cushion, I have designated it the “ coronary cushion.” ) 

On the plantar cushion and the lower face of the pedal bone, this mem- 
brane is also a villous tunic—the velvety tissue, which is continuous, towards 
the bulbs, with the extremities of the coronary cushion. 

The portion spread over the anterior face 
of the third phalanx constitutes the laminal 
or “leafy tissue,’ so called because of the 
lamine or parallel leaves seen on its sur- 
face. 

The three regions of the keratogenous 
apparatus will be successively studied. 

1. Corowary Cusnion.—This part is the 
matrix of the wall of the hoof, and is lodged 
in a cavity excavated at the upper border of 
this part of the horny case. It forms, ac- 
cording to the expression employed by 
M. Bouley, a rounded prominence, which 
projects like a cornice above the podo- 
phyllous tissue. . : 

Its inferior border is separated by a white 
zone from the upper extremity of the lamine, 
which constitute this boundary. 

The superior border is limited by a 
slightly projecting margin named the peri- 
oplic ring, because it originates the horn of 
the periople. Between this margin and the | copa view or THE HORSE’s FOOT 
cushion is a sharply defined groove. ; AFTER REMOVAL OF THE HOOF. — 

The extremities, narrower than the middle 1, perioplic ring, dvided by a narrow 
portion, on arriving at the bulbs. of the groove from the coronary cushion, 
plantar cushion, bend downwards into the cles ek oe ba the 
lateral lacune of the pyramidal body, where = PAnr Tose oH sae fie 
they become confounded with the velvety — snedium of the white zone. 


shone, : ; . 
Rg surface of the organ shows filiform prolongations, a little constricted 


at their base, and named papille, villo-papille, villi, and villous loops, whose 


Fig. 373, 


804 THE APPARATUS OF THE SENSES. 


size is greatest towards the lower part of the cushion; those of the perioplic 
ring are smallest. Contained within the minute apertures at the upper part 
of the wall, these papille, considered as a whole, and when the hoof has been 
removed by maceration, form a tufty surface most perfectly seen when the 
foot is immersed in water. 

The structure of the coronary cushion resembles that of the derma, of 
which it is in reality only a continuation. It comprises a fibrous frame- 
work, remarkable for its thickness and its condensation, with a considerable 
number of vessels and nerves, whose ramifications may be followed to the 
extremity of the villi. It owes to its great vascularity the bright red colour it 
shows on its surface; this colour is sometimes masked by the black pigment 
belonging to the mucous portion of the hoof. 

(I have found a notable quantity of adipose tissue in the cushion.) 

2. Vutvety Tissuz.—Much thinner than the plantar cushion, the vel- 
vety tissue, the formative organ of the sole and frog, extends over the whole 
of the plantar region of the third phalanx, as well as the plantar cushion, 
whose bulbs and pyramidal prominence it covers by adapting itself exactly 
to the irregularities of this elastic mass. 

Its surface, which altogether resembles the general configuration of the 
plantar surface of the hoof, is divisible into two regions: a central, corre 
sponding to the pyramidal body and the frog, and continuous on the bulbs 
of the cushion with the extremities of the coronary cushion and the perioplic 
ring, but chiefly with the latter; the other, peripheral, is covered by the 
horny sole, separated from the podophyllous tissue by the plantar border of 
the foot, somewhat encroached upon posteriorly by the laminz corresponding 
to the bars, and is continuous, above these lamina, with the plantar cushion. 

The surface of the velvety tissue is studded with villi similar to those 
of the coronary cushion, and about the same in size. The longest are 
towards the circumference of this surface, and the shortest in the median 
lacuna of the pyramidal body ; all are lodged in the porosities on the inner 
surface of the horny sole and frog. 

This tissue shows the same organisation as the coronary cushion. The 
vascular corium, forming its base, is thickened at its peripheral portion by 
a fibrous network named the plantar reticulum, in the meshes of which are 
sustained the veins of the inferior face of the foot. 

8. Laminat Tissuz.—This part of the keratogenous membrane is also 
very frequently designated the poduphyllous tissue (and still more frequently, 
in this country, as merely the lamin). It is spread over the anterior face 
of the third phalanx, occupying the interval between the plantar border of 
that bone and the lower margin of the coronary cushion; its width is, 
therefore, greater at the anterior part of the phalanx than on its sides, where 
the extremities of the membrane are reflected below the bulbs of the plantar 
cushion on to the velvety tissue. 

This membrane owes its name to the leaves it exhibits on its superficies ; 
these are from five to six hundred in number, run parallel to each other, 
and are separated by deep channels, into which are dovetailed analogous 
leaves on the inner side of the wall of the hoof; they extend from the white 
zone that limits the inferior border of the coronary cushion—where they are 
not so salient—to the plantar border of the foot, where they each terminate in 
five or six very large villous prolongations, which are lodged in the horny 
tubes at the circumference of the sole. 

The leaves (lamine) of the podophyllous tissue increase in width from 
above to below; their free margin is finely denticulated, and, under the 


THE INTEGUMENTARY APPENDAGES. 805 


influence of any inflammatory cause (laminitis, ablation of the wall), these 
denticule become largely developed, and transformed into veritable papille. 
Their sides are traversed by folds, about sixty in number, which pass 
uninteruptedly from top to bottom. These secondary leaves, or lamella, 
are fixed obliquely on the sides of the lamin, as the barbules of a feather 
are attached to the barbs. 

The podophyllous tissue is not in immediate contact with that of the 
keraphyllous tissue, or horny lamine; between the two there is a mass of 
soft, elliptical cells, always destitute of pigment, easily stained with carmine, 
and appearing to stud the ramifications of the vascular lamine. A trans- 
verse section of the union of the hoof with these lamin, when treated with 
carmine, presents a very fine aspect, appearing as so many fern or acacia-of- 
Judea leaves placed between the keraphyllous lamine: the principal nerve, 
and the secondary nervules of the leaves, being represented by the lamina 
and its lateral ridges, the limb of the leaves by the young cells spread 
around the latter. 

The structure of the podophyllous membrane resembles that of the other 
parts of the keratogenous apparatus. Its corium is, like that of the peri- 
pheral portion of the velvety tissue, separated from the os pedis by a fibrous 
reticulum, which supports the veins, and forms, to some extent, the periosteum 
of the third phalanx. 

The leaves of the podophyllous membrane are immense lamellar papille, 
which should be included among the principal instruments concerned in the 
tactile sensibility of the Horse’s foot, and which play a really mechanical 
part, in concurring, by thcir dovetailing with the keraphyllous (or horny) 
laminz, to assure the solidity of the union of the hoof with the living parts. 
The cells which multiply on their surface have usually but little share in 
the formation of the horn. This will, however, be alluded to hereafter. 


b. Description of the Hoof. 


The hoof of the Horse, considered as a whole, represents a kind of box 
that envelops the inferior extremity of the digit, by fitting closely on the 
keratogenous membrane, to which it is united in the most intimate manner 
by a reciprocal penetration of the prolongations into the cavities that exist 
on the surfaces in contact. 

Its general shape is, as was demonstrated by Bracy Clark, that of the 
moiety of a cylinder cut obliquely across its middle, and resting on the 
surface of this section. In nearly all feet, however, it is slightly conical. 

Prolonged maceration separates it into three portions: the wall, sole, 
and frog. : 

Watt.—The wail, also named the crust, is that part of the hoof which is 
apparent when the foot rests on the ground. This thick plate of horn 
covers the anterior face of the foot, and, gradually narrowing in width and 
diminishing in thickness, passes round each side until it reaches the bulbs 
of thc: plantar cushion, when its extremities are sharply inflected inwards, 
between the frog and internal border of the sole, becoming confounded with 
the latter about its middle or anterior third, after being greatly reduced in 
breadth and substance. 

The middle, or anterior part, of this horny envelope is popularly known 
as the toe, the two sides of which are designated as outside and inside toe ; 
the lateral regions constitute the quarters ; the heels are formed by the angles 

54 


806 


THE APPARATUS OF THE SENSES. 


of inflexion of its extremities; while these extremities themselves, passing 
along the inner border of the sole, are termed the bars. 


HOOF JUST REMOVED FROM THE 
FOOT; SIDE VIEW. 

a, Inner surface of periople, or coronary 
frog-band, with some hairs passing 
through; a’, Outer surface of same 
at posterior part of foot; a’, A sec- 
tion through the wall to show its 
thickness; 6 to c, Quarter of the 
hoof, from 6 to the front is the out- 
side (or inside) toe; from ec to d the 
outside (or inside heel); e, Frog; f, 
Bevel on upper margin of wall for 
reception of coronary cushion; g, 
Keraphylla, or horny laminae. 


Examined with regard to the direction 


that it affects in its relations with the 
ground, this envelope is seen to be much 
inclined in its middle region or toe, and 
this obliquity gradually diminishes until 
the posterior part of the quarters is reached ; 
at this point the wall is nearly perpen- 
dicular. 


The following are the characters it 


offers in the conformation of its faces, bor- 
ders, and extremities : 


The external face, convex from side to 


side, and perfectly straight from the upper 
to the lower border, is smooth, polished, 
and shining: an appearance it owes toa 
thin horny layer, independent of the wall 
proper, designated the periople. 


This periople forms, on the upper part 


of the wall, a kind of ring, continuous with 
the bulbs of the plantar cushion, and with 
the frog, of which it is only a dependency ; 
responding, by its upper margin, to the 
perioplic ring, which secretes it; towards 


the lower part of the wall it is gradually 
lost, friction incessantly thinning and destroying it. 


Fig. 375. 


i Wlcutdtidiy 


ft’ 2 


hie 


HOOF, WITH OUTER PORTION OF THE WALL 


REMOVED TO SHOW ITS INTERIOR. 

a, a, Periople, or coronary frog-band; 8, 
Cavity in upper part of wall for coro- 
nary cushion ; c, Upper, or inner, surface 
of “bar ;” d, Vertical section of wall; d’, 
The same at the heel; ¢, Horizontal 
section of ditto; f’, Horny lamine of 
bar; f”, Ditto of wall; 7", Lateral aspect 
of a lamina; y, Upper, or inner surface 
of the horny sole; f, Junction of the 
horny lamine with the sole (the “ white 
line”); ¢, Toe-stay at the middle of the 
toe; k, Upper, or inner surface of the 
horny frog; 7, Frog-stay; m, Cavity 
corresponding to a branch of the frog; 
n, Ditto corresponding to the body of 
the frog. 


The inner face presents, over its entire 
extent. the white parallel leaves which 
dovetail with the lamine of the podo- 
phyllous tissue. Collectively, these are 
uamed the keraphyllous tissue. 

The superior border is bevelled-off, 
on its inner aspect, into a circular con- 
cavity, into which the plantar cushion is 
received. This excavation is named the 
cutigeral cavity, because of its relations ; 
it offers on its surface a multitude of 
minute openings—the commencement of 
the horny canaliculi which receive the 
villosities of the cutiduris. 

The inferior border, in contact with 
the ground, and subjected to wear in 
unshod animals, is united inwardly, and 
in the most intimate manner, with the 
circumference of the sole. 

The extremities, constituted by the 
reflected and re-entering prolongations 
known as the bars, form, outwardly, the 
external side of the lateral lacune of 
the frog: they are provided, inwardly, 
with laminz like the rest of the wall. 
The upper margin of these prolonga- 


THE INTEGUMENTARY APPENDAGES, 


* 


807 


tions is confounded with the frog and sole; the lower appears between*these 
two parts, and is effaced at a certain distance from the point of the frog. 
Sotz.—The sole is a thick horny plate comprised between the inner bor- 
der of the wall and its reflected prolongations; thus occupying the inferior 
face of the hoof. It offers two faces and two borders or circumferences. 
The inferior, or external face, forms a more or less concave surface, 


according to circumstances. 


The superior, or internal face, corresponds to 


the peripheral portion of the velvety tissue; it shows a multitude of little 
 pertures analogous to those of the cutigeral cavity, into which are inserted 


the papille of the keratogenous membrane. 


The eaternal border, or large circumference, is united, throughout its 


extent, to the inner contour of the lower border 
of the wall, by means of its denticule, which 
are reciprocally dovetailed into those on the 
jnner face of the wall near its inferior border. 
The internal border, or small circumference, is a 
deep, V-shaped notch, widest behind, which cor- 
responds to the bars, and at the bottom of which 
the point of the frog is fixed. 

Frog.—This is a mass of horn, pyramidal in 
shape, and lodged between the two re-entering 
portions of the wall. It offers four planes (or 
sides), a base, and a summit (or point). 

The inferior and the two lateral planes con- 
stitute the external surface of the organ. The 
first is hollowed by a longitudinal excavation, 
which is shallow in well-formed hoofs, and is 
named the median lacuna of the frog, separating 
the two salient portions, or branches, which di- 
verge posteriorly and join the heels. he other 
two planes are directed obliquely downwards and 
inwards; they adhere closely, at their upper third, 
to the external side of the bars, and anteriorly 
to the inner border of the sole. “This union 
is so close that no line of demarcation is appa- 
rent between these parts, and their separation 
can only be obtained by prolonged maceration. 
The non-adherent, or free portion, forms the inner 
side of the angular cavities known as the lateral 
lacunce, or commissures of the frog, whose external 


PLANTAR OR GROUND SURFACE 


OF A HOOF; RIGHT FOOT. 


The interval from a to @ repre- 
sents the toe; Froma to 4, 6, 
outside and inside quarters; 
c, 0, Commencement of bars ; 
d, d, Inflexions of wall at the 
heels, or “ buttresses ;” ¢, La- 
teral lacuna; f, f, f, Sele; 9, 
White line; g’, g’, Ditto be- 
tween the sole and bar; f, 
Body of frog; ¢, Branch of 
frog; &,&, Glomes, or heels of 
frog; 1, Median lacuna. 


side is constituted by the inferior face of the bars.” —-Bouley. 


The superior plane, 
with holes like that of 
body of the plantar cushion. 


forming the internal face of the frog, is cribbled 
the sole, and is exactly moulded on the pyramidal 
Tt also offers a triangular excavation, divided 


posteriorly into two Jatter channels by a prominence directed from before 


backwards, to which Bracy Clark gave the na: 


me of frog-stay, but which 


M. Bouley prefers to designate the spine or ridge (aréte) of the frog. 

The base or posterior extremity of the frog, constituted by the extremities 
of its branches, forms two rounded, flexible, and elastic eminences separated 
from each other by the median lacuna; they cover the angles of inflexion of 


the wall, and are continuous at 
Clark named them the glomes of the frog. 


With regard to 


this point with the perioplic band. Bracy 


the summit, or anterior extremity of the organ, it is a 


808 THE APPARATUS OF THE SENSES. 


point: wedged in the re-entering angle comprised between the two portions 
of the inner border of the sole. 

In the Ass and Mule, the hoof is always narrower, laterally, than that of 
the horse; the wall is always higher and thicker, the sole more concave, 
the frog smaller and deeper seated at the bottom of the excavation formed 
by the sole, and the horn is much more hard and resisting. 

(The angle of the wall of the hoof in front varies from 50° to 56°, 
though usually erroneously stated to be 45°, The inner face of the wall, 
at the middle of the toe, and in a line with the frog-stay, frequently shows a 
more or less salient and conical prominence—base towards the lower margin 
of the wall—which corresponds to a vertical depression in the os pedis. 
Vallada imagined that this projection served to unite the wall and sole more 
closely, but it is far more probable that its function is the same as that of 
the frog-stay—to maintain the position of the os pedis, and prevent its 
rotation within the hoof. I have, therefore, named it the “ toe-stay.”) 

Srructure or THE Hoor-norn.—The structure of the horn has been the 
object of a great number of researches; Gurlt, Delafond, Bouley, Gourdon, 
and Ercolani'! have given descriptions of it, and we have also some details to 
add to the labours of these authorities. 

The horny substance constituting the hoof of Solipeds, has a fibrous 
appearance; this is most conspicuous in the wall, less apparent in the frog 
and deeper portions of the sole, but impossible to distinguish in the 
superficial layer of the latter, where the disintegration continually taking 
place separates the horn in scaly fragments of varying thickness and 
extent. The consistence of the horn is always less in the frog than in the 
sole and wall. Its tint is in some hoofs black, in others white, and in 
others again a mixture of these two. The inner face of the wall, however, 
is never black; and when the lower part of the limb is partially or wholly 
white, we may be sure that all the thickness of the wall will either be white 
at corresponding points in the former, or entirely so in the latter. 

Except in the keraphyllous tissue, the minute structure of the hoof-horn 
always exhibits the same characters; everywhere it is perforated by cylin- 
drical canals whose upper end is funnel-shaped, and these contain the papille 
of the matrix, whether they belong to the coronary cushion or velvety tissue ; 
while the lower end reaches the inferior border of the wall, or lower face of 
the sole-and frog, according to their situation. It is rare to find them in the 
horny lamine. All are rectilinear, with the exception of those of the frog, 
which are somewhat flexuous; and all have the same oblique direction 
downward and forward, following the inclination of the anterior portion of 
the wall. They are, therefore, almost exactly parallel to each other, not 
only in the same, but’in the two different regions. Their diameter varies 
considerably, though the smallest are always those of the periople; in the 
wall, they are smaller as they approach the outer surface. 

These tubes are not mere canals hollowed out of the horny substance ; 
on the contrary, they have very thick walls which are formed of numerous 
concentric layers, one within the other, and the horny tissue connecting 
them has not the same apparent stratiform disposition. Filled by the 
papille of the keratogenous membrane at their superior extremity, these 


(The researches of Professor Rawitsch must not be omitted. They will be found in 
Volume xxviii. of the ‘Magazin fiir Thierheilkunde,’ and also in a little brochure 
entitled ‘ Ueber den feineren Bau und das Wachsthum des Hufhorns.” Berlin, 1863. 


Leisering must likewise be referred to. My own researches are published in the 
‘ Veterinarian’ for 1871.) 


THE INTEGUMENTARY APPENDAGES, 809 


canals are not empty for the remainder of their extent; but contain a. 
particular white substance, which is so opaque that it appears of a fine 
black hue when examined as a transparency in the microscope. This matter 
is not deposited in a uniform manner in the canals, but irregularly-looking, 
like a knotted cord or a necklet of beads; and, where it does exist, it 
does not always exactly fill the calibre of the tube, an interval being 
observed between the inner face of the latter and the intratubular deposit, 
Sometimes it is seen without the canals, among their concentric lamella, 
and even in the horny intertubular substance. 

If we are desirous of completing our knowledge of the minute organ- 
isation of the hoof-horn by studying the anatomical elements constituting 
it, we will find that it is formed of epithelial cells belonging to the kind 
most wide-spread in the economy—pavement epithelium. These horn 
epithelial cells are very thin, pale, polygonal, and generally oblong, have 
sharply defined borders and finely granular faces, sometimes showing a 
nucleus containing a single or multiple nucleolus. The nuclei sometimes 
occupy the centre, at other times another part of : 
the cells—even their margins; and they also con- a 
tain pigment granules more or less coloured and 
numerous. Acetic acid acts very slowly on them, 
and is limited to making them more transparent. 
Potass and soda at first softens, then distends 
them, causing their granulated aspect to disappear, 
and rounding their contours; afterwards, they be- 
come quite diaphanous, and finish by being com- 
pletely dissolved. 

Examined in their reciprocal relations, these 
epithelial cells are not seen to be agglomerated 
confusedly together, but are, on the contrary, dis- 
posed in a regular manner, forming a real frame- 
work that wonderfully concurs in assuring solidity 
and flexibility. In the walls of the tubes we see 
them arranged horizontally around the canal, and HORN-CELIS TROM THE SOLE 
stratified from within to without, so as to form OF an OOEs 
successive concentric layers. In the intertubular % ere cel lsiraen the BBE 

z 3 : fi surface of the sole; 8, Cells 
horn they are disposed differently, their stratifi- fom the lower ‘surface, or 
cation being no longer parallel to the direction of — dead horn of the sole. 
the tubes, but perpendicular to it, and piled upon 
each other in the intervals separating the latter. This change of direction 
does not occur suddenly; at the limits of. the tubes epithelial cells are 
seen lying obliquely. as 

In a transverse section of the wall, there are observed around the tubes, 
in the intertubular substance, as well as in the horny lamine, small 
irregularly elliptical spaces containing a solid denticulated mass of a 
brownish tint, which is easily stained with carmine. These bodies are 
more elongated in the intertubular substance than in the walls of the tubes, 
and have a certain resemblance to the cartilaginous capsules, but especially 
to the bone cavities filled by their contents. 

Independently of the hard, dry, and flattened cells, there is found an 
opaque substance that partly fills the tubes, and which is also sometimes 
met with in their walls. This material does not differ from the last in its 
nature; it is also fornied, as has been asserted by Gourdon and Ercolani, of 
irregular granular cells which are stained by the carminate of ammonia. 


810 THE APPARATUS OF THE SENSES. 


Pigmentary-corpuscles exist in the substance of the coloured horn, 
and are disposed singly, or in small masses, in the epithelial cells of the 
intertubular substance. ‘The presence of these corpuscles has been denied, 

and the coloration has been attributed to a greater 
Fig. 378. condensation, at certain points, of the epithelial 
¥ elements. Fine pigment-granules are disseminated 

A in the cells, but it is evident that beyond these there 

&% (j are at different points pigment-corpuscles ; for, after 

il treating a section of coloured horn with soda, the 
epithelial elements are distended, become pale, and 
disappear, leaving, however, here and there, masses 

b of black granulations. These pigmentary-corpuscles 

are absent in white horn. 

Devetorpuent oF THE Hoor.—The hoof being a 
dependency of the epidermis, is developed like it: 
that is, by the incessant formation of cells in the 
layer that corresponds to the rete mucosum, at the 
expense of the plasma thrown out by the numerous 
vessels in the keratogenous membrane. The velvety 
tissue forms the sole and frog; the perioplic ring the 
periople, and the coronary cushion the wall. In 
these different parts, the epithelial cells multiply, 
CONSTITUENT ELEMENTs 2nd become flattened in layers parallel to the surface 

OF THE WALL. that secretes them, and in proportion as they recede 
a, Horn-cells; 0, Horn- from that surface; so that the wall grows from its 

fibre from the hoof of superior to its inferior border, and the other two parts 
er meee res of the hoof from their internal to their external face. 
en veliowte The villosities of the coronary cushion and the 
velvety tissue are the organs around which the epi- 
thelial lamelle are grouped, and their presence determines the tubular 
structure of the horn; their function is completed by the exhalation of a 
particular fluid that maintains the flexibility of the hoof, and, probably, by 
the development on their surface of the irregular cells which cluster in 
the interior of the tubes. 

The leafy tissue, in a normal condition, does not concur to any extent 
in the development of the wall. The cells covering it are multiplied in 
describing a downward and forward movement; and though they are 
certainly applied to the inner face of the wall, yet they do not constitute 
the horny lamina. The latter are formed on the coronary cushion, at the 
commencement of the vascular lamine, and they descend with the wall in 
gliding along the surface of the layer of cells separating them from the 
latter; this downward movement is facilitated by the multiplication, in the 
same sense, of these cells. This opinion as to the function of the vascular 
lamin is based on comparative anatomy, on the presence of some lon- 
gitudinal tubes in the horny lamine, and on pathological observations. 

_ _When the podophyllous tissue is inflamed, whether or not it is exposed, 
its latent activity is quickly manifested, and it rapidly throws out a large 
quantity of hard consistent horn, traversed by tubes which, according to 
M. Gourdon, are directed obliquely backwards. These tubes are more 
irregular than those of the normal wall, are disposed in parallel series, and 
are formed around the villo-papille developed on the free border of the 
lamine. In this horn, “produced by the vascular laminew only, there are 
never observed between these latter the horny plates of cells—sharp and 


THE INTEGUMENTARY APPENDAGES. 811 


distinct in the midst of the other cells, as in those of the wall formed by the 
coronary cushion. 

The horn thrown out on the surface of the podophylle, immediately 
after the removal of a fragment of the wall, is not a definitive horn, but 
must be replaced by that from the coronet. This substitution is complete ; 
as a microscopal examination proves that the wall which descends from the 


Fig. 379. 


HORIZONTAL SECTION OF THE JUNCTION OF THE WALL WITH THE SOLE OF THE HOOF. 
a, Wall, with its horn-tubes; 6, 5, Horny lamine projecting from the wall; ¢, ¢, 
Horn-tubes formed by the terminal villi of the vascular laminae, the horn 
surrounding them and occupying the spaces between the horny lamina, con- 
stituting the “ white line;” d, Horny sole, with its tubes. 


cushion, and is furnished with horny Jamine, passes beneath the provisional 
wall, and glides downward—by the combined action already mentioned—over 
the surface of the soft cells of the vascular lamine. As soon as the latter 
are covered by the proper wall, their marginal papille become atrophied, 


and they again assume the limited function pertaining to their physiological 
condition. 


Fig. 380. 
c c ig co" a d 


HORIZONTAL SECTION OF THE WALL, AND HORNY, AND VASCULAR LAMINA, TO 
SHOW THE JUNCTION OF THE LATTER AND THE LAMINELL&, 

a, Inner portion of the wall with the laminz arising from it; b, Vascular lamine ; 
c, Horny lamina of average length; c’, c’, Unusually short lamine; ¢”, ¢”, 
Laminellw on the sides of the horny laminz; d, Vascular lamina passing between 
two horny ditto; a’, Vascular lamina passing between three horny lamine ; ai 
Lateral laminelle ; ¢, e, Arteries of vascular laminz which have been injected. 


(The description of the disposition of the epithelial cells given by 
Chauveau does not coincide with my own observations. As he correctly 


812 THE APPARATUS OF THE SENSES. 


states, these cells are formed in planes parallel with the surface that 
secretes them; consequently, around the papille they are more or less 
vertical, while between them they are horizontal. The walls of the tubes, 
or fibres, are therefore composed of cells disposed in a vertical manner; 
while in the interfibrous horny matter they are arranged in the opposite 
direction. The loose nodulated contents of the tubes is composed of cells 
thrown off from the termination of the papilla, and corresponds to the pith 
of feathers. The soft cells interposed between the vascular and horny 
lamine are carried down to the lower margin of the wall, where, with the 
elastic horn secreted by the papille which terminate the former, they 
constitute the peculiar light-coloured band, or “ white line,” which marks 
the junction of the sole with the wall (Fig. 379). This intermediate band 
of soft flexible horn at this point obviates tearing of the sole from the wall, 
and fracture of the former. The cells of the horny laminz are more or less 


fusiform. 

M. Chauveau has also evidently overlooked the presence of beautiful 
lateral leaflets on the sides of the horny laminz, corresponding to those on 
the vascular leaves. ‘These were observed by me in 1858; in 1862 they 
were described by Rawitsch and Ercolani, and, at a later period, by Colin of 
Alfort and Leisering of Dresden. They are very conspicuous in a well- 
prepared section (Fig. 880, d”). ; 

It should be observed that the growth of the wall of the hoof is 
indefinite, but that the sole and frog, after attaining a certain thickness, 
exfoliate. For complete details as to the physiology of the Horse’s foot, the 
student is referred to the ‘ Veterinarian’ for 1871.) 


2. The Claws of Ruminants and Pachyderms. 


In the Ox, Sheep, and Pig, the plantar cushion covers the bulb of the heel of each 
digit, where it forms a convex mass; it extends to the insertion of the deep flexor 
tendons of the phalanges, in becoming triangular in shape, and thinner. The horny 
envelope covering the extremity of the digits of these animals is a kind of cupola, 
having almost the form of the third phalanx; it is usually named the elaw. 

The claw of the Ox has an outer face resembling the wall of the Horse’s hoof, and an 
inner face which is slightly concave, and marked by undulating grooves; owing to this 
concavity, the two claws of each foot only touch at the extremities of their adjacent 
faces. The plantar region of the claw is slightly depressed, and but little developed ; 
it is chiefly made up of the plantar cushion, which is covered by a thin layer of supple 
tubular horn. On the interior of the claw is seen a wide shallow cutigeral cavity, 
perforated by very fine openings, and lamin thinner and more numerous than in the 
Horse’s hoof. The tubes of the claw-horn are very small, being surpassed in diameter by 
those of the periople and sole. 

Above and behind each claw are two little rudimentary horny capsules, which are 
named ergots. (Each contains a small bone, which is not attached to the skeleton in 
Ruminants. In the Pig, these rudimentary claws are larger, and are connected with the 
bones of the leg. In this animal the horn of the claws is altogether thinner, softer, 
and less resisting than in Solipeds. The ergot is the representative of those digits which 
are apparently absent in the solid and cloven foot.) 


8. The Claws of Carnivora. 


In these animals, the third phalanx of the digits is enveloped in a conical horny 
sheath that curves downwards like the bone itself. This covering is designated the 
claw or nail, and offers somewhat the same organisation as the horns of Ruminants; it 
is developed, and grows in the same manner, as the hoof of Solipeds, its matrix being a 
prolongation of the corium which extends over the third phalanx, after dipping into 
the circular furrow at the base of that bone. 

Placed at the extremity of the digital region, the claw in these animals is not 
utilised in locomotion, as the foot does not rest on the ground by the extremities of the 


THE APPARATUS OF TASTE. 813 


digits, but by the whcle plantar surface. Therefore it is, that we find on this face a kind 
of epidermic pad covering five fibro-adipose tubercles: four small ones placed along the 
four principal digits—the fifth or thumb not being sufficiently developed to reach the 
ground—and a large central one, cireumscribed in front by the others. This ar- 
rangement is destined to diffuse the pressure caused by the weight of the body (and, 
doubtless, to ameliorate the concussion arising from the exertions these animals make, as 
well as to insure their footsteps being noiseless in approaching their prey). In the Dog, 
the claws may be used for burrowing in the ground. 

In the Cat, the claws are very sharp and retractile; being capable of erection and 
depression in the interdigital spaces, by means of a small yellow elastic ligament 
passing from the second to the third phalanx. This animal’s claws constitute its most 
powerful weapon of attack and defence. 


4. The Frontal Horns. 


These are conical horny sheaths, more or less large, crooked. and annulated 
transversely, formed by concentric layers of epithelial cells and some pigment corpuscles, 
The horns grow like the epidermis and the hair, their elements being secreted by that 
portion of the corium spread over the osseous cores of the frontal bones, and which 
completely envelope these; this portion of the skin is remarkable for its great 
vascularity. 

(The length, direction, and general form of the horns varies in Ruminants, not only 
with regard to species, age, and race, but also thesex. The Buil, in the Bovine species, 
generally has short, thick, powerful horns; the Cow long and slender ones; and the Ox 
Jarge, long, and strong ones. Some breeds have no horns at all; the same with the 
Goat species, though generally the horns in these are long, flattened, and curved 
backwards and downwards. With the Ram, the horns are sometimes immense and very 
powerful, being of a spiral form. They are usually less, or altogether deficient. in the 
Ewe. In the Bovine species, the transverse rings on the horns serve to indicate the age, 
the first appearing after two years.) 


5. The Chesnuts. 


This name is given to a little horny (oval or round) plate found, in the 
Horse, on the inner face of the fore-arm—in the lower third of the region, 
and at the upper extremity of the inner face of the metatarsal bone. It is 
composed of a mass of epithelial cells, arranged in tubes like the horn of 
the hoof. In Solipeds, the chesnut is the representative of the thumb. 
That on the posterior limbs is absent in the Ass; in the Mule it is very 
small. 

(in fine-bred Horses, this horny production is much less developed 
than in the coarser breeds. It is always smaller in the hind limbs. 

In the hind and fore-legs, we also find a similar, but smaller corneous 
mass, growing from the skin of the fetlock, and named the ergot. Like the 
chesnut, it bears the same relative development in fine and coarse-bred 
horses.) 


CHAPTER II. 


APPARATUS OF TASTE, 


Tux sense of taste permits the appreciation of savours, or the sapid properties 
of bodies. a 

Two nerves—the chorda tympani and the lingual branch of the ninth pair 
—appear at present to be the only sensory filaments endowed with the 
exercise of this function. They ramify in the lingual mucous membrane, 
which is thus made the organ of taste, 


814 THE APPARATUS OF THE SENSES. 


The tongue and its investing membrane having been described at page 
385, their anatomy need not again be referred to; but we must glance at 
the organisation of the latter in considering it as the special apparatus of 
gustation. This will necessitate a few words on the free surface of the mem- 
brane which comes into contact with the sapid bodies, and some consider- 
ations on the terminations of the nerves which transmit the impressions 
produced by these bodies to the brain. ; 

Free Surrace or THE Lingua Mucous Memprane.—This surface is 
studded by a multitude of papillary prolongations, which are nearly all 
limited to the upper surface of the tongue, to which they give a tufty 
appearance. Their form and volume, as mentioned at page 336, are very 
variable, according to their situation: some are microscopic, while others 
form voluminous caruncles; others, again, are long, conical, and filiform ; 
another variety is round or depressed, representing a hemispherical tubercle 
scarcely projected beyond the general surface, or placed at the bottom of an 
excavation in the mucous membrane. The latter constitute the calyciform 
papille (p. circumvallate, p. lenticulares), and are considered the true organs 
of gustation ; the others are the fungiform (p. capitate) and filiform papille, 
which play a mechanical part on the surface of the tongue. ; 

The calyciform papille in the Horse are two in number, and situated near 
the base of the tongue; their diameter is so considerable that they have been 
named the blind or cecal openings (trous borgnes). They are the principal, 
but not the only organs of taste. Their surface is mammillated, each 
prominence corresponding to a single papilla, and being placed below the 
level of the raised border encircling them. A deep fossa surrounds them, 
and limits at their base a pedicle, which unites them to the other portions 
of the mucous membrane. 

The calyciform papille show, around their peduncle, a band of adenoid 
tissue ; and in their substance conglomerate glands, as in other parts of the 
mucous membrane. They are covered by an epithelium containing some 
scattered pigment granules, the thickness of which is much diminished at 
the bottom of the fossa circumscribing them. 

TERMINATION OF THE Gustatory Nerves.—The hypoglossal is the motor 
nerve of the tongue, the lingual the nerve of general sensibility, and the 
chorda tympani and glosso-pharyngeal the filaments of special sensibility : 
this appears to be clearly ascertained from the recent experiments and 
observations of Lussana. The lingual branch of the glosso-pharyngeal 
nerve gives gustatory sensibility to the posterior third of the tongue; the 
chorda tympani to the anterior two-thirds. 

The gustatory nerves present, as do all those of the organs of sense, a 
particular mode of termination. First indicated by Axel Key, their special 
manner of terminating has been carefully studied by Lowen and Schwalbe. 
According to these anatomists, the terminal nerve-tubes lose their medul- 
lary envelope and, reduced to their axis-cylindcr, are thrown out in small 
oval masses which might be termed gustative bulbs. These bulbs are more 
particularly placed around the pedicles of the calyciform papille, in the 
substance of the epithelium. They are fusiform, their inner extremity 
rests on the mucous derma, where they receive the terminal nerve-tubes ; 
and their external extremity reaches the epithelial layer, where they are seen 
either between two cells, or in an orifice pierced in a single pavement cell. 
Each bulb is composed of a small cluster of cells, which are distinguished 
from each other by their character and position; those occupying the axis 
of the organule are the gustative cells; they are in communication with the 


THE APPARATUS OF SMELL. 815 


nerve-tubes on one side, and on the other are furnished, for the most part, 
with rods which attain the free surface of the tongue. The superficial, or 
protective cells, completely envelop the preceding; they are a kind of 
epithelial-cells imbricated like the skins of an onion. 

These sensitive organs are very numerous in the walls of the calyciform 
papille. Schwalbe reckoned their number at 35,000 in the papille of the 
Ox. They are not met with in these papille only; Lowen has found 
them in a large quantity of fungiform papille, if not in all. There is 
nothing extraordinary in this, as the whole surface of the tongue may, in 
various degrees, appreciate savours. (Szabadfildy has described small 
oval or pyriform bodies, lying with their long diameter parallel to the surface. 
The axis-cylinders of the gustatory nerves enter these, and terminate at their 


lower part in a slight swelling; so that they resemble small Paccinian 
bodies). 


DIFFERENTIAL CHARACTERS IN THE APPARATUS OF TASTE IN OTHER THAN SOLIPED 
ANIMALS, 


In the domestic mammifers, the differences in this apparatus are found in the number 
and variety of forms of the papilla of the tongue. 

In Ruminants, the calyciform papille are disposed in two rows at the base of the 
tongue; they are smaller than in the Horse, but more numerous—about a dozen being 
counted in each row. In the Oz. the filiform papilla are covered by a horny sheath, 
which renders them hard to the touch. 

The Pig, like Solipeds, has only two calyciform papille. 

Inthe Dog and Cat, there are two principal papille, and in their vicinity some smaller 
calyces. The filiform papille are composite, and covered by a thick horny layer. 
Between them, regularly placed, are seen the fungiform papille, which have a brilliant 
aspect when looked at obliquely to the surface of the tongue. 


COMPARISON OF THE APPARATUS OF TASTE IN MAN WITH THAT OF ANIMALS. 


This has been already alluded to at page 364. 


CHAPTER ITI. 


APPARATUS OF SMELL. 


Pur sense of smell gives the appreciation of odorous emanations to animals. 
The active instruments of this sense are the filaments of the first pair of 
encephalic nerves, which ramify in the upper part of the pituitary membrane ; 
this becomes, with the cavities it lines, the olfactory apparatus, These parts 
have been already referred to at page 444. 

(The olfactory filaments, passing down from the olfactory ganglion, form 
a plexus upon the surface of the pituitary membrane. These filaments, as 
already noted, differ widely from those of the ordinary cephalic nerves, in 
containing no white substance of Schwann, but are nucleated and finely- 
granular in structure, and resemble greatly the gelatinous form of nerve- 
fibres. Their distribution is limited to the membrane at the upper third of. 
the nasal septum, the upper part of the turbinated bones, and the wall of 
the nasal cavities adjoning the cribriform plate of the ethmoid bone: all 
this surface being covered with an epithelium of a rich sepia-brown hue. 
As has also been mentioned, Schuitze divides these cells into two sets: 


816 
one (Fig. 382, a) 
Fig. 381. 


FIBRES OF ULTIMATE 
RAMIFICATIONS OF 
OLFACTORY NERVES 
OF DOG. 


THE APPARATUS OF THE SENSES. 


being described as terminating externally by truncated 
flat surfaces, which cannot be observed to be covered by 
any membrane separate from the contents of the cell, 
These contents appear to consist of protoplasma with a 
yellow granular aspect externally, while at the lower 
part an oval nucleus imbedded in transparent protoplasm 
can be easily seen. At their attached end, these cells be- 
come attenuated, and may be traced inwards for a con- 
siderable distance until they expand into a broad flat 
sheet or plate, which is never coloured, though it fre- 
quently presents a granular appearance. The processes 
passing off from this appear to be continuous with the 
fibres of the submucous connective tissue. Towards 
the margin of the true olfactory region, cells perfectly 
analogous to these are met with, the only difference 
being that they present a well-defined band or seam at 
their free extremity, which is surrounded by a circle of 
cilia (Fig. 382, c). The cells of the second set (Fig. 
382, b) are continuations of the nerves, and have been 
named olfactory cells. They are thin, fibrous, or rod-like 
bodies, terminating at the same level as the proper 


epithelial cells, and presenting, when traced inwards, a series of varicose 
swellings directly continuous with the prolongations of deeper-seated nerve- 
cells. Clarke states that the nerve-fibres, on reaching the base of the 
epithelial layer, divide into finer and finer branches, to form a network with 


Fig. 382, 


numerous interspersed nuclei, through which they 
are probably connected with the olfactory cells (Fig. 
382, f). The proper epithelial cylinders (d, e) are 
connected at their bases with the septa formed of the 
connective tissue belonging to the subepithelial glan- 
dular layer.) 


CHAPTER IV. 
APPARATUS OF VISION, 


Drsienep for the perception of external images ren- 
dered visible by the luminous rays, the sense of 
sight depends upon the excitability of the optic nerve, 
the terminal extremity of which is expanded as a thin 
membrane at the back of each eye. The latter is a 
globular organ lodged in the orbital cavity, attached to 
muscles which can move it-~in various directions, 
and protected by membranous and movable screens 


CELLS OF THE oLPAcTory known as the eyelids, whose play over the surface of 


MUCOUS MEMBRANE, 
a, b, c, After Schultze; 
d, e, f, After Lockhart 


Clarke, 


the eye is facilitated by the lachrymal fluid, which 
keeps their inner surface constantly moist. 

The essential organ of vision, or globe of the eye, 
will be first described; then, under the designation 


of the accessory portions of the visual apparatus, we will notice the receptacle 


THE EYE. 817 


of this globe, or orbitas cavity, the muscles that move it, the protective mem- 
branes or eyelids, the membrana nictitans or accessory eyelid, and, lastly, the 
lachrymal apparatus, which concurs in the protection of the ocular globe by 
the fluid it incessantly throws out upon its surface. 


Articte J.—Tuz Essnntian Orcan or Vision, on Ocunar Gtorz. 
(Fig. 383.) 
(Preparation —The eye should be as fresh as possible. All the fat and museles 
should be carefully removed with scissors, the optic nerve being allowed to remain.) 


The globe, or ball of the eye, is a spherical shell, whose interior is filled 
with fluid or semifluid parts, named the humours or media of the eye. The 
wall of this shell is formed by a continuous, very resisting, colourless 
envelope, limpid and translucid in its anterior portion, which constitutes the 
transparent cornea, and white and opaque for the remainder of its extent, 
known as the sclerotica. 

_ On the inner face of the sclerotica isa second tunic—the choroid : a black 
membrane that lines the posterior face of the retina, and which, near where 
the two constituent portions of the external envelope unite, projects into the 
interior of the eye an elliptical diaphragm with a large opening in its centre 
—the iris. Immediately behind this disc is suspended or set, like a rose- 
brilliant, in the centre of a circular zone depending from the choroid, 
a biconvex body—the crystalline lens, one of the media of the eye, and 
which divides the interior of its cavity into two compartments: a posterior, 
very large, occupied by the vitreous humour ; and an anterior, itself divided 
by the iris into two chambers of unequal dimensions, which contains the 
aqueous humour. 

Viewed externally, and as a whole, the organ resulting from the union 
of all these parts represents a globular body, the anterior region of which 
corresponds to the cornea, and is more convex than the other points: a 
circumstance that tends to increase the antero-posterior diameter of the eye. 
But as this ocular sphere, to which is added, in front, this segment of a 
smaller sphere, is sensibly depressed from before to behind, it results that 
the other two principal diameters— the vertical and transversal — offer 
about the same dimensions as the first; Girard has even stated that the 
latter is the least. With an eye hardened by chromic acid, we have 
found that the transverse diameter measured 0,036, and the vertical 0,040 
(1:417 x 1-575 inches). 

Two paragraphs will be devoted to the description of the constituent 
parts of the globe: one for the membranes, the other for the media, 


‘THE MEMBRANES OF THE EYE. 


1. The Sclerotic. (Fig. 388, b.) 


The sclerotic is a white, very solid membrane, forming in itself about 
four-fifths of the external shell of the eye. 

Its external face, in relation with the recti muscles and adipose tissue, 
receives posteriorly, though lower than the middle, the insertion of the 
optic nerve, which passes through it and the choroid to form the retina. Its 
internal face is loosely united to the choroid by vessels, nerves, and 


cellular tissue. - ; 
In front, the sclerotic shows an elliptical opening whose greatest diameter 


818 THE APPARATUS OF THE SENSES, 


is transversal, and whose border, bevelled on the inner side, is closely united 
to the circumference of the cornea. The substance of this membrane is 
traversed by numerous vessels and nerves, and is not of the same thickness 
throughout; at the back, around the entrance of the optic nerve, it is 
thickest . it then diminishes gradually towards the larger axis of the organ, 
and afterwards increases until it meets the cornea. 


Fig. 383, 


THEORETICAL SECTION OF THE HORSE’S EYE. 

a, Optic nerve; 6, Sclerotic, c, Choroid; d, Retina; ¢, Cornea; f, Iris; g, 4, Ciliary 
circle (or ligament) and processes given off by the choroid, though represented as 
isolated from it, in order to indicate their-limits more clearly; 7, Insertion of 
the ciliary processes on the crystalline lens, 7, Crystalline lens; %, Crystal- 
line capsule; J, Vitreous body; m, , Anterior and posterior chambers; 0, The- 
oretical indication of the membrane of the aqueous humour; », p, Tarsi; q, q, 
Fibrous membrane of the eyelids; 7, Elevator muscle of the upper eyelid; s, s, 
Orbicularis muscle of the eyelids; ¢, ¢, Skin of the eyelids; u, Conjunctiva; », 
Epidermic layer of this membrane covering the cornea; «, Posterior rectus muscle 3 
y, Superior rectus muscle, z, Inferior rectus muscle; w, Fibrous sheath of the 
orbit (or orbital membrane). 


StructurE.—The sclerotic is wholly composed of fasciculi of fibro- 
cellular tissue interwoven in a very close manner, with some elastic fibres and 
little masses of pigment, especially at its back part. Among these fasciculi 
a large number pass from before to behind, and these are intersected by 
others which are placed in a circular manner around the globe. The super- 
ficial fibres are continuous with the neurilemma of the optic nerve. (‘The 
optic nerve, at its entrance into the sclerotic, is very much constricted, 
and passes through a funnel-shaped, porous mesh of fibrous tissue named the 
lamina cribrosa, in the centre of which is a larger opening than the others, 
for the passage of the arteria centralis retinse—the porus opticus. The inner 


THE EYE. 819 


surface of the sclerotic is coated by a thin layer of areolar tissue siained 
with black pigment—the lamina fusca.) 

_. The arteries of the sclerotic are derived from the anterior and posterior 
ciliary arteries; the veins pass into trunks lying parallel to the ciliary 
arteries. Nerves have been found in the sclerotic of the Rabbit, but in none 
other of the domesticated animals. “It is frequently found that in the Ass, 
particularly when it is old, the back part of the sclerotic is encrusted with 
an unmistakable layer of bony matter. This fact was unknown to Carus, 
who states that in none of the mammalia does this membrane become 
ossified.”—TLecog. (In Birds, bony plates are found in this region, and 
some reptiles also have them.) 


2. The Cornea. (Fig. 383, e.) 


(Preparation.—The cornea should be removed with the sclerotic coat, by immersing the 
eye under water, and making a circular incision with scissors about a quarter of an inch 
from the margin of the membrane). 

The cornea is a transparent membrane forming the anterior part of the 
eye, to whose interior it allows the light to pass. It closes up the anterior 
opening of the sclerotic, and thus completes the external envelope or shell 
of the globe, of which it forms about a fifth part. 

Elliptical, like the opening it closes, the cornea presents: 1, Two faces, 
perfectly smooth—one eaternal, convex, the other internal, concave—form the 
external wall of the anterior chamber; 2, A circumference, bevelled on its 
outer edge, and received into the similar bevel around the sclerotic opening, 
like the glass of a watch into its case. 

Srructure.—Three layers enter into the composition of the cornea: an 
external, internal, and middle. 

Middle tayer.—This, the proper cornea, is remarkable for its thickness. 
When pressed between the fingers, its two faces can be easily made to glide 
over each other, a proof that its tissue is disposed in superposed and parallel 
planes; it is indeed possible to decompose the cornea into several lamin 
and lamelle, but as their number varies with the amount of skill employed 
in their separation, they should be considered as an artificial production of 
dissection. Microscopically examined, it is found to be formed by bundles 
of excessively fine conjuntival fibrille, slightly undulating, and arranged 
parallel to the surface of the cornea. These wavy fasciculi, when placed 
alongside each other, leave numerous spaces which are oval in a transverse 
section ; these communicate by means of fine canaliculi, and contain round 
cellular elements which may move from one space to another. 

Between the fasciculi of the cornea is found a fluid amorphous substance, 
“a kind of transparent serosity like the cornea itself, which maintains its 
flexibility, and which, like it, also loses its transparency under the influence of 
different causes. It is only necessary, in a fresh eye, to squeeze the globe in 
order to produce a degree of opacity in the cornea which will be more or 
less great in proportion to the amouut of pressure exercised. Is a similar 
effect produced by the swelling of the eye when the cornea becomes opaque 
in ophthalmia ?”—Lecog. 

The external layer is only the conjunctival epithelium spread over the 
anterior face of the cornea. This epithelium is stratified, flattened on its 
surface, but cylindrical below, where it rests on the middle layer, and from 
which it is not separated, as in many species of animals, by a proper 
limitary membrane. . 

The inner layer is a portion of the membrane of the aqueous humour. 


820 THE APPARATUS OF THE SENSES. 


It is composed of a membrane that becomes slightly fibrous at the 
periphery of the cornea, where it forms, in passing on to the iris, the 
pectinated ligament. It has also a covering of polygonal epithelial cells, 
which are provided with a large nucleus. ; 

(Some authorities give five layers to the cornea, the first being the 
conjunctival. The second consists of a very elastic tissue, perfectly 
structureless, and possessing a remarkable tendency to curl up; while 
boiling, or the action of acids, does not render it opaque as with the other 
layers ; very fine fibres pass obliquely between it and the next layer—the 
cornea proper—consisting of a large number of strata with branched 
fusiform cells. The fourth layer is also elastic and like the second, though 
thinner. The fifth layer consists of the epithelial cells already mentioned. 
Wilson says that the opacity of the cornea produced by pressure on the 
globe, results from the infiltration of fluid into the areolar tissue connecting 
its layers, and that this appearance cannot be produced in a sound living 
eye, although a small quantity of serous fluid (liquor cornew) is said to 
occupy the spaces in that tissue.) 

Vessels-—The cornea has but little vascularity. The vessels form loops 
around its borders, and in the Sheep they advance to near the middle of its 
surface. 

Nerves.—These were discovered by Schlemm. They penetrate by the 
periphery of the cornea, and form a network on its surface. According to 
Kiihne, Hoyer, and Conheim, the ultimate nervous ramifications pass into 
the epithelium of the anterior face, and arrive between the most superficial 
cells. 


3. The Chorotd Coat. (Fig. 383 c.) 


(Preparation.—If the cornea has not yet been removed, it and the sclerotic may now 
be dissected away from the choroid or second tunic. The connections between them are 
closest at the circumference of the iris, and at the entrance of the optic and ciliary nerves 
and arteries. Fine blunt-pointed scissors are necessary. A small portion of the 
sclerotic, near its anterior circumference, is pinched up and clipped off, the edge of the 
incision is raised, the circumference of the sclerotic divided, and that tunic removed 
piecemeal; a gentle pressure with the edge of the knife will remove it from its 
attachments around the circumference of the iris. This dissection is best conducted 
under water. The ciliary nerves and long ciliary arteries will be seen passing forward, 
between the sclerotic and choroid, to the iris.) 

The choroid is a thin, dark-coloured membrane spread over the inner 
face of the sclerotic, whose general conformation it repeats. It is divided 
into two zones by the ora serrata—a denticulated line which corresponds to 
the point where the retina changes its characters. 

Posterior or choroid zone-—Throughout the extent of this zone the 
choroid is uniformly thin, and corresponds, by its eaternal face, to the 
sclerotic ; by its internal face, it is in contact with the retina, but does not 
adhere to it. Posteriorly, it shows an opening through which the optic 
nerve passes. In front, at the anterior opening of the sclerotic, it is 
continuous with the anterior zone. ‘ 

The inner face of the choroid is not uniform in colour, being perfectly 
black in the lower part of the eye; this is abruptly terminated at a 
horizontal line that passes about the 8th or 9th part of an inch above the 
optic papilla. From this line, on the segment of a circle from 44, to 35 of 
an inch in height, it shows most brilliant colours: at first blue, then an 
azure-blue, afterwards a brownish-blue, and after this the remainder of the 
eye is occupied by an intense black. The bright portion is the tapetum. 

Anterior or ciliary zone.—This includes two parts: the “ciliary circle 


THE EYE. 821 


(or cen ” and the “ciliary body.” The ciliary circle, ligament, or 
muscle (annulus albidus) varies in width from one to two millimétres; its 
external face adheres closely to the sclerotic, and its internal is confounded 
with the ciliary body; the posterior border is continuous with the 
choroid zone, near the canal of Fontana (ciliary canal). The anterior 
border gives attachment to the greater circumference of the iris. Its 
structure and uses will be referred to hereafter. 

The ciliary body (corpus ciliare) forms a kind of zone or ring, wider than 
the ciliary ligament, and consequently overlaps the latter before and 
behind. It extends, on one side, on the inner face of the choroid, and on 
the other, on the posterior face of the iris. When the cornea and sclerotic 
are removed so as to expose the ciliary ligament, this zone is not seen; and 
to discover it, it is necessary to excise all the posterior part of the shell of 
the eye by a circular incision, and evacuate the vitreous humour. We then 
observe, around the crystalline lens, a wide, black circle, forming very 
regular radiating folds (ciliary processes) projecting inwards by their inner 
extremities, and appearing in the posterior chamber of the eye, after cutting 
away the iris; all abut by these extremities on the circumference of the 
lens, which they do not quite reach, although the latter is sustained by, and 
“set” in, the middle of the ligament. 

These radiating folds (Fig. 384, 4) are from 110 to 120 in number in the 
Horse, and are constituted by little parallel leaves, wider at their inner than 
their outer extremity; the furrows that separate them posteriorly are 
partly concealed by the prolongation of the retina that constitutes the 
zonula of Zinn. The coronet formed by the ciliary processes is usually 
asymmetrical. 

(Between the sclerotic, the cornea, and the c’liary ligament, exists a 
minute circular canal—the ciliary canal, 
canal of Schlemm, sinus circularis tridis, Fig. 384. 
circulus venosus orbiculi ciliaris, or canal of P 
Fontana, from its discoverer. It is sur- 
mised to be a venous sinus, as it can 
always be injected from the arteries.) 

Srructure.—The choroid zone is com- 
posed of four superposed layers: 1, The 
external is formed by a network of con- 
nective elastic fibres, among which are 
disseminated a great number of pigment 
cells; 2, The second layer is constituted by 
a network of large arteries and veins— 
the posterior ciliary—and a plexus of 
nerves (ciliary) accompanied by ganglia and 
some (stellate) pigment cells. (The veins 
are arranged with great regularity in droop- 
ing branches, to form the vasa vorticosa ses proce etn ies ee 
(Fig. 386, 2, 4); these are chiefly on the (yumay), sEEN FROM WITHIN. 
outer surface of the layer, the arteries 1, Divided edge of the three tunics, 
ramifying on the inner surface.) 8, The sclerotic, choroid (the dark layer), 
third layer, or tunica Ruyschiana, has for and retina; 2, Pupil; 3, Iris, the 
its basis an amorphous substance containing ila ee a ae 
a network of exceedingly fine capillaries jiting pene Ont ae 
extending to the ciliary processes); 4, The 
guternal layer is composed of hexagonal cells, regularly placed one upon the 

ps 


822 THE APPARATUS OF THE SENSES. 


other on the surface of a structureless laminw; the cells are provided with a 
nucleus, and contain pigment-granules which exclusively occupy their anterior 
moiety. (On the choroid this cell formation is single, but on the iris and ciliary 
rocesses there are several layers. A very delicate membrane— membrane 
of Bruch—has been described as lining the inner surface of the choroid, and 
retaining the pigment in its place; this membrane may be seen on the 
posterior surface of the iris, and it probably prevents 
Fig. 385. the pigment being removed by the aqueous humour.) 
The use of the choroid membrane is to convert the 
ocular globe into a veritable darkened chamber. (The 
pigment absorbs the rays of light which pass through 
the retina, and thus prevents their becoming reflected 
and confusing the vision. The brilliant metallic- 
coloured layer named the tapetum is more particularly 
observed in nocturnal animals, and especially in the 
Carnivora; it is due to the presence of a thick layer 
of wavy fibrous tissue outside the choroidal epithe- 
lium. By reflecting the rays of light a second time 
CELLS FROM PIGMENTUM through the retina, it probably enables the animal 
= ae anules *° 8€€ better at night. It is the cause of the glare 
of apuesalibpe ENR Ewes perceived in the eyes of Cats and other creatures in 
d, The nucleus distinct. the dark.) 

The ciliary ligament is a contractile body, being 
composed of unstriped muscular fibres which are arranged in orbicular 
fasciculi, or extend backwards (and are lost in the choroid, behind the ciliary 
processes). These fibres are intermixed in the plexus of ciliary nerves, on 
whose track small ganglia are formed. By its contractions, the ciliary 
muscle (or ligament) plays an important part in accommodating the eye to 
the perception of objects at different distances. (In Birds, the muscular 
fibres are striped.) 

The ciliary body or processes are formed by intercrossed fasciculi of con- 
nective tissue, vessels, and some unstriped fibres; their inner surface is 
covered by pigment, like that of the chorvid zone. 


4, The Iris, (Figs. 883 f; 886, 6.) 


The iris forms in the interior of the eye, at the anterior opening of the 
sclerotic, and in front of the crystalline lens, a veritable diaphragm pierced 
with a central opening—the pupil—which contracts or dilates according 
to the intensity of the light and the distance of the objects to which the 
vision is directed. This diaphragm divides the space between the cornea 
and the anterior face of the lens and internal extremities of the ciliary 
processes, into two compartments or chambers of unequal size: the anterior 
being the largest, and the posterior having only a virtual existence, the iris 
being close to the crystalline lens. 

In shape, the iris is elliptical, like the cornea and the sclerotic aperture. 

Its anterior face is flat or very slightly convex, and has very marked 
circular furrows and radiating strie, noticeable only at the outer cir- 
cumference of the membrane. It is diversely coloured, not only according 
to species, but also in individuals. In Solipeds, it has nearly always a 
brownish-yellow hue; though sometimes it is nearly white or bright grey, 
when the animal is said to be “ wall-eyed.” 

The posterior face, in relation with the lens and ciliary processes, is 


THE EYE. 393 


covered by a very thick layer of pigment named the wea: portions of 
which, supported by a small pedicle, frequently pass through the 
pupillary aperture and appear in the anterior chamber of the eye, where 


THE EYE (HUMAN) WITH THE SCLEROTIC COAT REMOVED. 
1, Sclerotic coat; 2, Veins of the choroid; 3, Ciliary nerves; 4, Veins of the 
choroid; 5, Ciliary ligament; 6, Ivis. 


they are known as “soot-balls” or corpora nigra. (There are frequently 
several of these black spongy masses, which are generally attached to the 
upper border of the pupil; on the lower margin, when present, they are 
much smaller. Their colour is a brownish-black. They are sometimes so 
large as to give rise to apprehensions of injury to the vision.) 


The larger circumference of the 
iris is attached to the ciliary liga- 
ment, which unites it to the 
choroid; it is also related to the 
margin of the cornea, as well as to 
that of the sclerotic opening. 

The lesser, or internal circwm- 
ference, is elliptical, and circum- 
scribes the pupillary aperture. 

Stzucture.—The organisation 
of the iris has been much dis- 
cussed; but at present it is ad- 
mitted that its principal element 
is unstriped muscular fibre. A 
proper membrane and two epi- 
thelial layers enter into its form- 
ation. The proper membrane has, 
for its framework, circular or radia- 
ting fasciculi of wavy connective 
tissue, with pigment cells. Be- 


unstriped fibres; these are disposed 
in a circular manner around the 


MUSCULAR STRUCTURE OF THE IRIS OF A 
WHITE RABBIT. 


tween the fasciculi are placed the +, Sphincter of the pupil ; }, b, Radiating fasciculi 


of dilator muscle; ¢, c, Connective tissue with 
its corpuscles, 


pupil to constitute the pupillary sphincter, and others radiate from the lesser 


824 THE APPARATUS OF THE SENSES. 


circumference towards the ciliary ligament to form the dilator of the pupil. 
The very fine radiating vessels are disseminated among these fibres, and 
pass to the anterior ciliary trunks. The nerves supplied to the iris are 
from the ciliary plexus. 

ODhe anderir epithelial layer is composed of the polygonal cells of the 
aqueous-humour membrane, already described as existing on the posterior 
surface of the cornea. : ; 

The posterior epithelial layer, or wvea, is constituted by pigment cells 
analogous to those of the choroid, but less regular in shape. 

In the foetus, the pupil is closed by a very thin transparent membrane— 
the membrana pupillaris. (It- is identical with the anterior layer of the 
capsule of the crystalline lens.) 


5. The Retina. (Fig. 383, d.) 


‘Preparation.—The choroid must be removed under water by means of forceps and 
scissors, after the lens and vitreous humour have been evacuated. A good view of the 
retina is to be had by looking through the vitreous humour, after the lens and iris have 
been excised from an eye ) 


The retina, the essential portion of the eye, considered as the terminal 
expansion of the optic nerve, extends over the internal face of the choroid, 
from which it is easily separated, and lies between that membrane and the 
vitreous humour. On arriving at the ciliary body, it is exactly moulded on 
the radiating folds of its posterior face, and with them is prolonged to the 
circumference of the crystalline lens, on the capsule of which it appears to 
become lost, after being closely united to it. It also adheres so firmly to 
the ciliary processes that, in the fresh eye, it is impossible to detach it. 
When the eye has been kept some time, however, the two are easily 
separated; the cornea is removed with a portion of the sclerotic; then 
dividing the iris into several pieces by diverging incisions, each is turned 
outwards by a slight traction that ruptures the ciliary zone and the 
choroid ; the retina being thus divested of the parts which cover it anteriorly, 
is $cen to form around the lens a kind of Elizabethan ruff, dovetailing with 
the ciliary processes. This plaited collar has been named the zonula of 
Zinn (zonula ciliaris, and ora serrata). The majority of anatomists, through 
having neglected to study this part in fresh eyes, have wrongly considered 
it as distinct from the retina, 

At the point where the optic nerve enters the eye, there is found on the 
retina a small oval elevation, whose larger axis is about } inch; this little 
prominence is the optic papilla or punctum ccecwm (papilla conica), From 
its centre emerge the vessels of the retina. 

Srrucrure.—tThe retina is the most important of the three tunics of the 
eye, and it is also the thinnest and most delicate. It forms a soft, pulpy, 
transparent expansion when quite fresh, but is white and opalescent soon 
after death. It is composed of connective tissue and nerve elements, 
which are arranged to form nine or ten superposed layers 

Coxnective Tissun—This is very delicate and nucleated, and forms 
two thin lamine named the external and internal limitary membranes ; these 
are connected by radiating fibres which pass through the nerve elements, 
and anastomose very closely in the molecular layer. 

Nerve Etemmnrs.—These are distributed in seven layers, which present 
the following characters : 


1. Layer of rods and cones. (Fig. 388, 1.)—This is also termed the mem- 


THE EYE. 825 


brana Jacobi (bacillary or columnar layer). It is situated between the inner 
face of the choroid and the external limitary membrane. 

Rods and cones, regularly mixed, make up its structure. Each of these 
comprises two portions or segments (separated by a bright transverse line), 
The outer segment (or shaft) is brilliant and f 
refractive, and consists of a small stalk termi- Besos 
nating in a point for the cones; with a shorter | VIN 
stalk than the inner segment for the latter, Mh : 
and equal in length to this segment for the iA i | 
rods. The inner segment is a small granular | i" WN 

tl 


oy 
Vi 


shaft for the rods, and an enlargement whose \\i! }i/ } 
base is towards the centre of the eye for the 4 i 
cones. The elements of this layer quickly 
alter after death. 

2. External granular layer (2).—This ig 
comprised between the external limitary and 
the intermediate membrane. It is formed by 
the granulations of the cones and those of the 
rods: small oval nucleated cells, furnished 
with an external prolongation that joins them 
to the base of the cones and rods, and an ex- 
ternal varicose prolongation which often en- 
larges on arriving at the intermediate layer. 

3. Intermediate layer (3).—This is very 
thin, and composed of flexuous fibrille, which 
are connected with the adjoining elements. 

4, Inner granular layer (4).—In this we 
find cells whose membrane is in contact with VRRIIGAT, BROPION, UE Rees 
the nucleus; these cells have minute prolong- 1, Baeillan Inverse 2, Uuder berate 
ments analogous to those of the external lar layer; 3, Intermediate fibrous 
granular layer, and which connects them with layer; 4, Inner granular layer; 
the surrounding layers. 5, Enel y-granalat grey layer; 

_ 5. Molecular layer (5).—One of the thickest, a levee eR ee 3 nee 
this layer (the grey vesicular) presents a tary membrane. 
granulous aspect; in its mass, the connective 
tissue forms a close mesh, in the midst of which are seen fine fibrille passing 
in every direction. 

6. Ganglionic layer (6).—This is composed of a single stratum of 
ramified nerve-cells, whose prolongations pass into the molecular layer, 
where they join the filaments of the next layer. 

7. Layer of optic-nerve fibres (7).—The fibres (ultimate fibrils) of the 
optic nerve, in passing through the sclerotic and choroid, énastomose with 
each other, and arrange themselves in a cone shape, whose apex corresponds 
to the papilla conica; at this point they suddenly spread out in every 
direction, between the ganglionic layer and the limitary membrane. 

To sum up, the retina comprises the following layers, reckoning from 
before to behind: 1, Internal limitary membrane; 2, Layer of optic-nerve 
fibres; 3, Layer of nerve-cells; 4, Molecular layer; 5, Inner granular 
layer; 6, Intermediate granule layer; 7, Outer granular layer; 8, Outer 
limitary membrane; 9, Columnar layer; 10, Pigmentary layer of the 
choroid, if this be attached to the retina, as Schultze proposes. 

It is to be remarked, that at the ora serrata all the nerve elements of the 
retina disappear, and the membrane, reduced to its connective tissue, is 


826 


continuous with the 


THE APPARATUS OF THE SENSES. 


posterior face of the ciliary processes, where it 


afterwards forms the zonula of Zinn. 


DIAGRAM OF THE STRUC- 
TURE OF THE RETINA. 
p, Pigment cell of the 
retina connected with a 
rod; n, Cone seated on 
the membrana limitans 
externa, the inner seg- 
ment containing a cone 
ellipsoid, and a needle; 
m, f, Proper fibre con- 
necting rod and cone 
with one of the cells of 
the membrana fenestra, 
whose cells are in com- 
munication with the 
membrana limitans in- 
terna, m, J, 7, by means 
of a thick radial fibre 
with an oval nucleus 
attached; g, g, Multi- 
polar ganglion of nerve 
elements; 0, p, Optic 
fibrilla; 9, 7, 7, Supposed 
connection of the nucleus 
with prolongation of a 

ganglion cell. 


(At the papilla conica, all the other elements 
than the nerve-fibres are entirely absent; hence this 
is presumed to be a 
“blind spot.”) 

Blood-vessels.—The 
retina possesses a par- 
ticular vascular distri- 
bution. The arteria 
centralis retin, with its 
vein, enters the optic 
nerve at ashort distance 
from the globe, and 
with it passes into the 
eye; they traverse the 
papilla, and immediate- 
ly divide into two 
branches, one of which 
is directed upwards,’ 
the other downwards. 
Close and fine anastomoses unite the vessels of 
the retina with the ciliary vessels at the back of the 
sclerotic. 


CAPILLARIES IN THE VASCULAR 
LAYER OF THE RETINA. 


THE MEDIA OF THE EYE. 
The Crystalline Lens. (Fig. 383, 7.) 


The lens, as its name implies, is a (solid) trans- 
parent body, sustained at the smaller circumference 
of the zone formed by the ciliary processes (behind 
the pupil, and partially imbedded in the vitreous 
humour). It is biconvex in shape, and flatter on its 
anterior than its posterior surface. We have mea- 
sured the lens of the Horse’s eye, and find the follow- 
ing dimensions: vertical diameter ;8,ths, and trans- 
verse diameter ;5,ths of an inch. The posterior face 
is evidently more convex than the anterior, for we 
found the transverse diameter of the last to be 4;ths, 
and that of the first _3,ths of an inch. 

Srrucrure.—The lens is enveloped in a trans- 
parent membrane, the capsule, which contracts no 
adhesions with it. Its thickness is uniform in the 
Horse, and its tissue is slightly striated transversely ; 


its internal face is lined by a layer of pavement epithelium. 

_ The proper tissue of the lens is disposed in concentric layers, which the 
microscope proves to be composed of fibres; the outer layers are almost 
fluid (gelatinous), but their consistence gradually increases towards the 


centre. 


Between the proper tissue and the epithelium of the capsule are 


two or three layers of round cells, whose dissolution some time after death 
forms the liquor Morgagni—which is consequently nothing more than the 
result of a cadaveric phenomenon. 

(The capsule of the lens is composed of tissue exactly similar to the 


THE EYE. 827 


elastic layer of the cornea. To examine the structure of the lens, it is best 
to boil it, or to immerse it in alcohol or nitric acid, which renders it hard 
and opaque. It is then found to be divided into three equal parts by three 
lines, which radiate from the centre to within one-third of the circumference : 
so that each of these portions is composed of hundreds of concentric layers, 
arranged within one another, like the coats of an onion. According to 
Kélliker, these fibres are tubular, and contain an albuminous fluid. If any 
single layer is examined with the microscope, it is found to be made up of 
these parallel fibres, which measure about soyoth of an inch in thick- 
ness, and are united with each other by finely serrated or scalloped borders 
that dovetail in the most beautiful manner. 

The lens is nourished by means of the extremely delicate layer of 
nucleated cells on its surface, which absorb nutriment from the capsule.) 

The lens receives neither vessels nor nerves. In the foetus, the arteria 
centralis gives off a branch which passes forward through the vitreous 
humour, and enters the posterior face of the lens ; but this vessel disappears 
long before birth. 

(The use of the lens is to bring the rays of light to a focus upon the 
retina, they being greatly refracted in passing through it.) 


2. The Vitreous Humour. (Fig. 383, 1.) 


The vitreous body, or humour, occupies all the cavity of the eye behind the 
lens (about two-thirds of the interior of the eye). 

It is a kind of colourless, transparent jelly, much more fluid than the 
lens, and entirely amorphous, according to Ch. Robin; though the majority 
of anatomists add some embryonic cells. At the surface of the vitreous 
mass is a very thin structure, the hyalotd membrane, which is in contact, 
externally, with the retina and the posterior face of the lens. 

(This hyaloid membrane forms cells, in which the watery fluid consti- 
tuting the humour is contained; the cells communicate freely, and are 
rendered apparent by freezing the eye or steeping it in chromic acid, when 
it is found that the humour is intersected by a large number of delicate 
partitions, with a cylindrical space in the axis for the passage of the central 
artery in the foetus. The membrane is firmer on the surface than else- 
where, so that it serves as a capsule for the humour, and suffices to keep it 
in shape after the outer envelopes of the eye are removed. As mentioned, 
the lens is maintained in situ by the zone of Zinn.) 

There has been described around the lens, between the hyaloid membrane 
and the zone of Zinn a circular passage named the canal godronne (canal of 
Petit), because of its form. I look upon this canal as an artificial production, 
and due to the means employed to demo strate it in mankind and animals. 

(This humour concurs in refracting the rays of light,) 


3. The Aqueous Humour. 


This is a liquid that owes its name to its great fluidity; it is contained 
jn the anterior and posterior chambers of the eye, in front of the lens. It is 
secreted by a particular membrane, the membrane of the aqueous humour, or 
membrane of Descemet or Demours; this is an extremely thin serous layer, 
easily distinguished on the posterior face of the cornea, and admitted to exist 
on the two faces of the iris, the ciliary processes, and anterior face of the 
capsule of the lens, where it is reduced to epithelium only. 


828 THE APPARATUS OF THE SENSES. 


(The chief function of this humour appears to be to maintain the con- 
vexity of the cornea, and to facilitate the movements of the iris and lens; as 
well as to assist, to some extent, in refracting the light that passes through it 
to thelens andretina. The rapidity with which this fluid can be regenerated 
is very striking; absorption also takes place very rapidly in the anterior 
chamber of the eye. The frequency of adhesions between the iris and lens, 
after attacks of ophthalmia, is accounted for by the small quantity of this 
fluid that exists between them, as owing to the smallness of the posterior 
chamber this is reduced to a mere film.) 


Arricty Il,—Accessory OnGaNs oF THE VisuaAL APPARATUS. 
ORBITAL CAVITY. 


Situated at the side of the head, at the point corresponding to the union 
of the cranium and face, the orbital cavity is circumscribed by a bony 
margin, in the formation of which the orbital process, frontal, lachrymal, 
malar, and a small portion of the zygomatic process of the temporal bone, 
concur. Posteriorly, however, there are no bony walls, and the cavity, in 
the skeleton, ig confounded with the temporal fossa. A fibrous membrane 
completes this cavity in the domesticated animals, and keeps it distinct 
from the fossa. 

Designated the ocular sheath (ocular membrane or periorbita), this fibrous 
structure is attached, posteriorly, to the border of the orbital hiatus, and 
anteriorly to the inner face of the orbit; being prolonged beyond the 
external lip of this osseous rim to form the fibrous membrane of the eyelids. 
Strong externally, the ocular sheath is thin within the cavity. It is 
traversed by vessels and nerves, and is composed of a mixture of elastic and 
inelastic fibres. (Unstriped muscular fibres have also been described as 
existing in this orbital periosteum.) 

Thus completed, the orbital cavity has the form of a regular hollow 
cone, open at its base, and closed at the apex, which corresponds to the 
orbital hiatus. 

In the ordinary position of the head, the opening of this cone is directed 
forwards, downwards, and outwards. 

Independently of the globe of the eye, this cavity lodges the muscles that 
move it, the membrana nictitans, and the lachrymal gland. 


MUSCLES OF THE EYE. (Fig. 391.) 


These are seven in number: five termed recti muscles, and distinguished 
as posterior, superior, inferior, external, and internal ; two named oblique—a 
large and small, 


(Preparation.—Detach the eyelids from the margin of the orbit, cutting away the lower, 
but leaving the upper. Saw through the zygomatic process of the temporal bone, in front 
of the temporo-maxillary articulation, also through the temporal process of the zygo- 
maticus, and the base of the orbital process of the frontal bone; remove the excised 
piece of bone, and the temporal fossa and ocular sheath are exposed. Cutting through 
the latter, the muscles of the eye are seen disposed in a conical manner around the 
globe; dissect away the fat lodged among them, in order to isolate them.) 


1. Posrzrion Reorvs Musoxe (or retractor oculi)—This muscle com- 
pletely envelops the extra-cranial portion of the optic nerve, being a 
muscular sheath resembling in shape the fibrous lining of the orbit. Its 
fibres are disposed longitudinally, arise around the optic foramen, and are 


THE ACCESSORY ORGANS OF VISION. 829 


inserted into the posterior part of the external face of the sclerotic. It is 
always more or less fasciculated, and is most frequently separated into four 
portions—superior, inferior, external, and internal. 

In contracting, it retracts the globe towards the back of the orbit. The 
physiclogical finality of this movement will be noticed hereafter. 

2. Superior, [wrerior, Exrernay, anp Internat Reorr Muscius.—These 
four muscles are placed longitudinally on the preceding, and repeat, on a 
large scale, the disposition of its four bundles. As their borders are in 
contact, they constitute a fleshy sheath around it, analogous to that which it 
forms around the optic nerve. Exactly resembling each other, these four 
muscles compose so natural a group, that they may be described together. 
Each is a flat band, formed of : 
parallel fibres, firmly attached Higheiets 
by its posterior extremity to tr 
the back of the sheath, and to 
the interior of the subsphe- 
noidal canal; anteriorly, it is 
inserted by a thin aponeurosis 
into the sclerotic, at the mar- 
gin of the cornea. Isolated 
from one another, and from 
the retractor, by the mass of 
fat belonging to the mem- 
brana nictitans, these small 
musclesare related, externally, 
to the ocular sheath. 

There is nothing par- 
ticular to be noted regarding 
them, their position bein MUSCLES OF THE EYEBALL, VIEWED FROM ABOVE. 


sufficiently indicated by their 1, Section of orbital process of frontal bone to which 


‘ 5 : the fibro-cartilaginous pulley, 4, of the superior 
names. Their function is to oblique muscle, 5, is attached; 2, Zygomatic 


bring the pupillary opening process of the temporal bone; 3, Portion of sphe- 
into contact with the rays noid bone into which the recti and superior 
of light, by inclining the oblique muscles are implanted ; 6, Pathetici nerve; 


. , i 7, Internal rectus ; 8, Superior rectus; 9, Levator 
colnies Hv aras them, either palpebrae muscle ; 10, External rectus; 11, Eye- 


upwards, downwards, inwards, ball; 12, Upper eyelid; 13, Lower eyelid; 14 
or outwards; or into inter- Inner canthus of eye. 

mediate positions, which 

happens when two adjacent muscles—the inferior and external rectus, for 
instance—combine their action at the same moment. 

3. Great Osiique Muscrie (trochlearis, or obliquus superior ocult).— 
Lying to the side of the internal and superior rectus, and formed, like them, 
of a fleshy band terminated by a thin aponeurosis, this muscle differs from 
the preceding in its interrupted course. Arising from the back of the 
orbit, and passing forward against the inner wall of that cavity, it reaches a 
strong fibro-cartilaginous, pulley-like, process—a dependency of the aponeu- 
rosis of the orbit—attached by its extremities to the frontal bone, at the 
base of the orbital process; it passes through this loop, and then bends 
outwards, to insinuate itself below the terminal extremity of the superior 
rectus, and become inserted into the sclerotic, between the latter muscle 
and the external rectus. 

This muscle pivots the eye inwards and upwards in the orbit, carrying 
the outer aspect of the globe upwards, and its lower part outwards; this 


830 THE APPARATUS OF THE SENSES. 


faculty it owes to its reflexion in the cartilaginous loop, as it acts as if its 
insertion was at the angle it forms there. : 

4, Smatu OsirqvE Muscun (obliquus inferior oculi)—Much thicker, 
though very much shorter than the preceding, and almost entirely fleshy, 
this muscle is placed in a transverse direction on the globe of the eye, being 
nearly parallel to the reflected portion of the great oblique. It arises in 
the lachrymal fossa, passes outwards, and terminates in the sclerotic, 
between the external and inferior recti muscles. 

It is an antagonist of the great oblique, pivoting the eye in a contrary 
direction. 

It is to be noted that the double rotatory movement executed by the 
oblique muscles is altogether involuntary, and that it is constantly produced 
when the animal inclines its head to one side: doubtless to maintain the 
visual axis always in the identical relations with the same point of the 
retina. This movement is well seen in Man when the head is brought 
round to either shoulder: the eye then pivots in the orbit in an inverse 
direction to that to which the head inclines, so that a mark placed at the 
upper part of the iris when the head is straight would occupy the same 
position after the lateral movement. Simultaneous in both eyes, this 
pivoting is executed by certain muscles in each; the great oblique for one, 
the small oblique for the other, according to the direction in which the 
head is turned. 

(A third, or middle oblique muscle, has been mentioned by the late 
Professor Strangeways, of the Edinburgh Veterinary School, as some- 
times, if not always, found between the superior and inferior oblique 
muscles. It has been described as arising by a fine tendon from a small 
depression in the upper part of the orbital process of the frontal bone, 
between the origin of the inferior oblique and the pulley of the superior 
oblique muscle. This tendon is succeeded by a fusiform fleshy mass, about 
three lines in diameter and an inch long, imbedded in adipose tissue; 
it passes obliquely upwards and outwards on the external face of the 
rectus muscle, and terminates in a thin flat tendon which accompanies the 
upper belly of the superior oblique for a short distance, and becomes con- 
founded with the tendon of that muscle as it runs beneath the superior rectus. 
It is supposed to be an accessory of the superior oblique, and to regulate 
and facilitate the gliding of that muscle through the acute angle formed by 
its pulley.) 


PROTECTIVE ORGANS OF THE EYE. 


1. The Eyelids. (Figs. 388, 391.) 


The surface of the eye is covered and protected in front, by two movable 
membranous curtains—the eyelids (palpebree) : one superior, the other inferior. 

Attached to the circumference of the orbit by their external border, the 
eyelids have a convex external face formed by the skin, and a concave 
énternal face, moulded on the anterior surface of the eye, and lined by the 
conjunctiva which is reflected above and below on the eyeball: the duplica- 
tures constituting the superior and the inferior conjunctival (or palpebral) 
sinuses. 
__ Hach lid has also a free border opposed to that of its fellow, with which 
it unites at an angle by its extremities, so as to form two commissures (or 
canthi). This border is slightly bevelled on the inner side, and shows a 
series of small openings—the excretory orifices of the Meibomian glands ; as 


THE ACCESSORY ORGANS OF VISION 831 


well as a row of erect hairs, the eyelashes: these will be described 
presently. ' 

When the two lids are closed by the approximation of their free borders, 
they completely cover the eye, and form a narrow fissure comparable to a 
closed button-hole. When they are separated, they circumscribe an oval 
space (fissura palpebrarum), whose greater axis is directed obliquely down- 
wards, forwards, and inwards. The upper lip or contour of this space, 
formed by the free margin of the superior eyelid, is always more curved 
than the lower. The superior commissure (or canthus) has also been named 
the temporat angle of the eye. The nasal angle, constituted by the inferior 
commissure, is always rounder than the other; it lodges the lachrymal 
caruncle (in the lachus lachrymalis). 

Structure or tHE Eye.ips.—A fibrous plate, terminated, towards the 
free border of the lid, by a small tendinous arch named the tarsus; a 
sphincter muscle, the orbicularis palpebree, in contact with the fibrous mem- 
brane; the levator palpebre,a muscle partly lodged in the ocular sheath, 
and terminated anteriorly by a very thin and wide expansion placed beneath 
the superior fibrous plate; a cutaneous envelope in two parts, containing 
the above: an external, the skin; and an internal of mucous membrane, the 
conjunctiva, joing at the free border of the lid;—these are the elements 
which enter into the composition of the protective coverings of the eye. 

1. Frsrous Mempranse.— Usually thicker in the lower than the 
upper lid, this membrane is attached, by its adherent border, to the rim of 
the orbit, where it is continuous with the periosteum and the fibrous wall of 
the ocular sheath. Its free border is margined by the tarsus. 

2. Tarsvs.—This is a fibrous lamella that forms a solid frame for the 
free border of the lid: it is elongated, narrow at its extremities, thin at its 
fixed border, where it is confounded with the fibrous membrane, and chan- 
neled on its inner face by several transverse parallel grooves which lodge 
the Meibomian glands. This small fibrous are regulates the contraction of 
the orbicularis muscle, and prevents the lid being drawn into wrinkles ; by 
the rigidity it bestows on the eyelids, it allows these to meet, border to 
border, without puckering, when that muscle is in action. 

8. Orzicutar Muscie or tHe Evens (musculus ciliaris)—This is a 
wide thin sphincter common to the two lids, applied to the fibrous mem- 
brane and the bone forming the rim of the orbit. Its external face is 
covered by the skin, to which it closely adheres. A small tendon that 
passes to the lachrymal tubercle of the nasal angle of the eye, is generally 
considered as the origin of the fibres of this muscle, the majority of which, 
directed upwards, are disposed in a circular manner in the substance of 
the upper lid; while the others go to the lower lid, both joining at the 
temporal angle of the eye. ; 

The contraction of this muscle causes the occlusion of the palpebral open- 
ing. (It is a prominent agent in defending the eye from external injury.) 
We may regard as an appendage of the orbicularis, a little short, flat fascicu- 
lus, usually designated the fronto-superciliary muscle from its attachments (or 
corrugator supercilii, from its function). It arises from the outer face of 
the frontal bone, passes downwards and outwards, and mixes its fibres with 
those of the latter muscle at the superorbital foramen, which it covers, and 
in the skin of the eyebrow. It has been erroneously considered an elevator 
of the upper lid, for when it contracts, it only corrugates the skin of the 
eyebrow by slightly drawing the nasal angle of the eye outwards; this it 
does as well when the lids are closed as when they are open. 


832 THE APPARATUS OF THE SENSES. 


4, Exevator Musctrz or tae Upper Eyetip, on ORBITO-PALPEBRALIS 
(Levator palpebree).—-When the ocular sphincter ceases to contract, the 
lower eyelid droops from its own weight ; the upper lid, however, requires 
some special muscular agency to raise it, and this it finds in the levator. 
This is a very thin, narrow, fleshy-band, lodged in the ocular sheath with 
the other muscles of the eyeball, and is related to the superior rectus, whose 
course it follows. On reaching the lachrymal gland, it expands into a wide 
aponeurotic membrane that passes between the conjunctiva and the fibrous 
plate of the eyelid, and terminates on the tarsus, . 

It will be seen that this muscle is inflected on the eyeball in a pulley- 
like manner, and it is owing to this disposition that it has the power of 
raising the lid. If the eyeball were not present, the muscle would draw the 
free margin of the lid towards the back of the orbit, instead of elevating it. 

5. Inrecuments or tuE Eyetrps.—The different layers enumerated are 
comprised between two tegumentary folds, the skin and conjunctiva, which 
are continuous at the border of the eyelids. We will examine these, with 
their appendages—the eyelashes and Meibomian glands. ; 

a. Skin—Intimately adhering, by its inner face, to the orbicularis 
muscle, this membrane is thin (smooth), and covered with numerous fine 
short hairs. In the foetus, it shows at the orbital arch, when the skin 
everywhere else is nude, a well-marked semicircle of hairs—the eyebrow. 
Fat is never found beneath it. 

b. Conjunctiva.—The conjunctiva, as its name indicates, joins the eyelids 
to the eyeball. Very fine and highly vascular, this mucous membrane is 
a continuation of the skin at the border of the lids, lines the inner face of 
each of them, envelops the anterior portion of the membrana nictitans in a 
particular fold, covers the caruncula lachrymalis, and enters the puncta ; 
it is then reflected, at the adherent border of the eyelids, on to the eyeball, 
extending over the sclerotic and terminal aponeurotic expansion of the recti 
muscles, On arriving at the margin of the cornea, it is impossible to trace 
it further; though it is represented by the thin layer of pavement epithelium 
already described. At the surface of the lachrymal caruncle, it shows 
some very fine hair bulbs. It possesses some papillae (on the palpebral 
portion only, the ocular reflection being thinner, and having none of these 
nervous processes), and tubular and aggregate glands, as well as closed 
follicles. We have found large numbers of the latter, whose volume was 
considerable; they form a corona around the cornea. 

The nerves of the conjunctiva terminate by small oval enlargements, 
the corpuscles of Krause. 

(The ocular portion has generally very few blood-vessels visible in health ; 
when inflamed it becomes intensely red and vascular.) 

ce. Hyelashes.—These are two rows of hairs (cilia) implanted in the free 
border of the lids, and destined to prevent the entrance of dust and small 
particles of foreign matter into the eye. They are much longer, and more 
abundant and stronger, in the upper than the lower lid, their presence there 
being more necessary, as extraneous particles are most likely to enter the eye 
when falling. Butif the eyelashes of the lower lid are few and rudimentary, 
this is compensated for by the presence on its surface of some long bristly 
hairs, scattered here and there, and exactly like the tentacula of the lips. 

Like all hairs, without exception, the eyelashes are flanked at their 
ean a two or three small sebaceous glands, whose duct opens into their 

ollicle. ° 


d. Meibomian glands.—These are little masses, analogous to sebaceous 


THE ACCESSORY ORGANS OF VISION. 833 


glands, which open alternately into a common, very long excretory canal. 
‘They are lodged in the transverse grooves observed on the inner face of the 
tarsal ligaments. The unctuous matter they secrete is thrown out on the 
free border of the lids, and enables these to retain the tears more easily 
within the ocular cavity. In sick animals, this secretion accumulates at the 
canthi and base of the lids. (Each gland consists of a central tube, with a 
number of openings round its sides leading to short cwcal dilatations. The 
secretion also facilitates the movements of the lids.) 

6. Vessets anD Nerves or tue Eveis.—These membranous curtains 
receive their blood, for the most part, by the supra-orbital and lachrymal 
arteries, and the orbital branch of the superior dental artery. The terminal 
extremities of the three sensitive nerves of the eye, formed by the ophthalmic 
branch of the fifth pair and the orbital filaments of the superior maxillary 
branch, ramify in them. The anterior auricular nerve endows the orbicularis 
muscle with contractility. The motor filaments of the levator palpebre are 
derived from the third pair. 


2. Membrana Nictitans. 


“This organ, which is also named the third eyelid, winking eyelid, etc., is 
placed at the great (inner) angle of the eye, whence it extends over the 
eyeball to relieve it from foreign bodies which may fall upon it. It has for 
its framework a fibro-cartilage —elastic—irregular in shape, thick and nearly 
prismatic at its base, and thin anteriorly where it is covered by the conjunc- 
tiva; it is continued, behind, by a strong adipose cushion, which is insinuated 
between all the muscles of the eye, and to which it is loosely attached. No 
muscle directly concurs in the movements of this body: they are entirely 
mechanical. When the eye is in its usual position, there is only per- 
ceived the fold of conjunctiva that terminates it in front; the remainder is 
concealed in the fibrous case of the eye. When, however, the latter is 
withdrawn into the orbit by the contraction of its recti muscles, the globe 
compresses the fatty cushion belonging to the cartilage; this cushion, 
pressing outwards, pushes the membrana before it, and the latter then entirely 
conceals the whole front of the globe. This movement is instantaneous, 
but it may be momentarily fixed by pressing gently on the eye when the 
animal retracts it within the orbital cavity. ; 

“The use of the membrana is, as will be seen from the above, to main- 
tain the healthy condition of the eye, by removing any matters that have 
escaped the eyelids; and what clearly demonstrates this function, is the 
inverse relation that always exists between the development of this body, 
and the facility with which animals can rub their eyes with their anterior 
limbs. So it is that, with the Horse and Ox, whose thoracic member cannot 
be applied to this purpose, the membrana is very developed ; and in the Dog, 
which may use its paw to some extent when it requires to brush its eye, it 
is smaller ; in the Cat it is still less; while in the Monkey and in Mankind, 
whose hands are perfect, it is rudimentary. In tetanus, the membrana 
nictitans often remains permanently over the eye, in consequence of the 
continued contraction of the recti muscles.”—F' Lecog. : 

(Towards the middle of the outer face of the membrana is a small 
yellowish-red gland, the gland of Harder, covered by a strong fibrous 
membrane, and surrounded by adipose tissue; it secretes a thick unctuous 
matter, which escapes by two or three small apertures on the inner face of the 


membrana.) 


834 THE APPARATUS OF THE SENSES. 


LACHRYMAL APPARATUS. 


« Thi ratus comprises: 1, A gland which secretes the tears; 2, A 
Pee a is that ey. the superfluous fluid to the external orifice of the 
mars eee gland.—This gland, situated between the orbital process and 
the upper part of the eyeball, from which it is separated by the superior 
rectus and levator palpebre muscles, is convex on its upper face, and concave 
inferiorly, in accordance with the parts it adjoins. But little developed, it 
is formed of very small granulations, united by fine connective tissue ; from 
these arise minute radicles, whose junction forms a certain number of very 
narrow ducts which open on the inner face of the temporal (outer) angle of 
the eyelids. These are the hygrophthalmic canals. 

«The lachrymal gland secretes the tears destined to lubrify the anterior 
surface of the eye. This fluid escapes upon the organ at the temporal angle 
of the lids, and is carried between them and the eyeball towards the nasal 
angle. Its secretion is incessant, but it is increased by anything that 
irritates the conjunctiva, and its character may even change under the same 
influences. 

«The lachrymal gland belongs to the category of conglomerate glands ; 
consequently, it is analogous to the salivary glands. (The gland is maintained 
in situ by a capsule formed by the fascia of the orbit. ) ; 

“The hygrophthalmic canals have a thin fibrous membrane for their 
walls; this is covered by cylindrical epithelium. ; 

“ Caruncula lachrymalis—This name is given to a small round (or fusi- 
form) body, frequently entirely, or partially black (or brown), slightly 
uneven, and situated in the nasal angle of the eye; it is nothing more than 
a small fold of conjunctiva covering some agglomerated follicles, and 
the bulbs of several fine hairs, which are readily seen on its surface. It 
may be regarded as designed to direct the tears towards the puncta, or to 
separate the extraneous particles that this fluid may carry towards it. 

“Tt has for its base a small mass of connective tissue, in the midst of 
which are some hair-roots, and some rather large glandules, lined by an 
epithelium charged with fat granules. Nerve-tubes ramify around the hair 
bulbs. 

“ Puncta lachryma'ia.—These are two little openings, situated one in each 
eyelid, a short distance from the nasal commissure, by which the tears pass 
from the oculo-palpebral surface into the lachrymal ducts. 

“ Lachrymal ducts—These are continuations of the last, and, like them, 
are very narrow; they carry the tears into the lachrymal sac. The superior 
is longer than the inferior duct, and arrives at the sac behind it. The 
mucous membrane lining these ducts is thin, and covered by a stratified 
pavement epithelium, similar to that of the conjunctiva. 

“ Lachrymal sac.— This little reservoir, lodged in the infundibulum that 
precedes the lachrymal foramen in the bone of that name, receives the tears 
from the two ducts, and passes them into the lachrymal canal. Its mucous 
membrane only differs from that of the ducts in being covered with ciliated 
epithelium. 

“ Lachrymal canal (nasal duct).—The tears accumulated in the sac flow 
into this long duct, which extends to the lower aperture of the nostril. 
About one half of its course is in the osseous canal of the lachrymal bone 
which protects it, and which terminates between the two turbinated bones. 
‘The remainder of the canal is beneath the nasal mucous membrane, whence 


THE ACCESSORY ORGANS OF VISION. 835 


it passes to the inner surface of the outer wing of the nostril; there it 
terminates by an orifice, sometimes two, that looks as if punched out of the 
membrane, towards the lower commissure, near the point where there is a 


line of demarcation between the dark colour of the skin, and the rosy tint 
of the mucous lining. 


“ This aperture constitutes the ‘ nasal outlet’ (égout nasal). 

“The epithelium of the membrane lining the canal is ciliated in its 
bony, stratified in its nasal, portion. On the surface of the membrane are to 
be seen the openings of the secretory ducts of some conglomerate glands, 
which are lodged in the walls of the canal. Throughout its extent, the 
canal is lined by a continuation of the mucous membrane of the lachrymal 
sac. In Solipeds, this canal opens on the cutaneous surface at the entrance 
of the nostrils; and it therefore happens that in these animals the con- 
junctiva, with its dependencies, forms a particular mucous membrane, really 
apart from the great gastro-pulmonary membrane. 

“In the Ass and Mule, the orifice of the Jachrymal canal is situated at 
the inner face of the outer wing of the nostril, and not near the inferior 
commissure, as in the Horse.” —F. Lecog : ‘ Extériewr du Cheval, ete. 

(Sometimes this outlet is double. The lachrymal secretion is not only 
useful in facilitating the movements of the eyelids over the eyeball, but it 
washes away dust and hurtful matter from off the surface of the cornea, 
keeping the latter clean, moist, and healthy.) 


DIFFERENTIAL CHARACTERS IN THE VISUAL APPARATUS IN OTHER THAN SOLIPED 
ANIMALS, 


EssENTIAL ORGAN oF Viston.—In the Oz, the eyeball resembles in shape that of the 
Horse ; but in small animals, particularly the Dog, it is much more spherical. In Birds, 
it is very convex in front; its largest diameter is the antero-posterior. 

Sclerotic.—This is the same in all the domesticated quadrupeds. In Birds, however, it 
has some curious features. Posteriorly, it has for base a cartilaginous layer, covered on 
both sides by fibrous tissue; this layer frequently ossifies around the optic nerve, where 
it forms the posterior sclerutic ring. Around the cornea, there is the anterior sclerotic 
ring, composed of small bony imbricated scales, capable of moving on each other, and 
modifying the shape of the globe of the eye. 

Cornea.—In the Dog and Cat, the structure of the cornea is similar to that of the 
Horse. (Kolliker states that he observed lymphatics in the cornea of a young Cat.) In 
the Ox, Sheep, and Pig, there are two limitary membranes ; one beneath the epithelium 
of the anterior face. In Birds, this limitary membrane is thickest in front. 

Choroid.—In mammiifers, there are some slight differences in the coloration of the 
tapetum. Thus, in the Oz, it is golden green, which becomes blue at the cireumference ; 
in the Sheep, it is a pale golden green; a golden yellow in the Cat ; and white, bordered 
with blue, in the Dog. (It is absent in the Pig.) In Birds, it is uniformly black ; this 
membrane has also a network of non-striped muscular fibres, and, in addition, “ Crampton’s 
muscle, which arises from the inner face of the osseous ring, and is inserted into the 
cornea.”—Leydig. (According to Hassenstein, in rapacious animals there is, behind the 
tapetum, a layer of corpuscles composed of lime salts; to this is owing the brilliancy of 
their eyes in the dark.) ; 

Tris.—In all animals the iris is muscular. In mammifers, the contractile fibres are 
non-striped ; in Birds, they are striped. (In the Oz, its anterior face has a brighter 
colour than in the Horse. In the Sheep it is a brownish-yellow; in the Goat blue.) In 
the Dog its colour is a more or less bright golden-yellow ; in the adult Cat green ; and 
in young animals a bright blue. The pupil is elliptical in the Ox, as in Solipeds (in 
the Sheep and Goat it is more elongated); in the Dog it is circular, and, when very 
much dilated, it is the same in the Cat; but, when contracted, it becomes elliptical 
vertically, and may be so narrow as to represent nothing more than a thin perpendicular 
slit. (In the Pég it is round.) . 

There are no differences worthy of note in the otlfer parts of the eye. 

ACCESSORY ORGANS OF THE VISUAL APppaRaTus.—The motor organs are nearly the 
same in all the other animals, 


836 THE APPARATUS OF THE SENSES. 


(The posterior rectus, or retractor muscle, is most developed in Ruminants, which, 
during their whole time of feeding, have the head in a dependent position. In most of 
the Carnivora, instead of this muscle forming a complete hollow cone, as in Ruminants, 
there are four distinct strips, almost resembling a second set of recti muscles, but deep- 
seated, and inserted into the posteaior, instead of the anterior, portion of the globe.) 

Muscles—Birds have only six muscles: four recti, and two oblique. The latter 
arise from the anterior wall of the orbit; consequently, the great oblique does not pass 
through a pulley. : : ; j 

Eyelids—The disposition of these is the same in all mammifers. In Birds, the lower 
lid is the largest, and is furnished with a particular depressor muscle; there are no 
Meibomian glands. There is a third eyelid, corresponding to the membrana nictitans of 
quadrupeds ; it is sufficiently extensive to cover the entire front of the eye. 

Glands.—In Ruminants, the Pig, and in Birds, there is found, annexed to the mem- 
brana nictitans, Harder’s gland—a conglomerate gland, with adipose epithelium in 
mammifers, and cylindrical and granular in Birds. It secretes a thick white matter, 
which is thrown out on the membrana by one or two orifices. Its use is, doubtless, to 
favour the movements of that organ over the surface of the eye, as well as those of the 
eyelids. (In the Oz, this gland and its ducts are large. The lachrymal gland is also 
voluminous and its nasal opening is situated higher in the nostril than with the Horse. 
In the Sheep, there are found, near the lachrymal fossa, several adipose follicles which 
do not properly belong to this apparatus, and which secrete a consistent, unctuous, 
yellow matter. In the Pig, the lachrymal ducts are separated, by a bony partition, 
into two sets, as far as the lachrymal sac.) 

(Orbital cavity.—In Ruminants, the frontal and superior extremity of the maxillary 
bones contribute largely to the formation of this cavity. In the Pig, the upper part of 
the orbit is not completed by the orbital process of the frontal bone, which is short; it is 
continued by a ligament. In the Dog, the superior portion of the cavity is entirely 
formed by a ligament, which replaces the orbital arch; in the Cat, this ligament is 
smaller, and the orbital process of the zygomatic concurs with that of the frontal bone 
to form the upper wall.) — 


COMPARISON OF THE VISUAL APPARATUS OF MAN WITH THAT OF ANIMALS, 


EssentraL Orncan or Viston.—The eyeball of Maw is almost spherical, as in the 
Carnivora. The sclerotic does not differ much. The cornea has two limitary membranes, 
and is much less elliptical than in Solipeds. The choroid has the same zones as in 
animals; it is uniformly brown. The ciliary processes, seventy to eighty in number, are 
a little longer than in the Horse, and do not exceed, in front, the ciliary ligament, to the 
inner face of which they adhere throughout their external border. The pupillary opening 
of the iris is always round. The retina is the same in structure ag already described, 
A little above the optic papilla, there is a circular or oval patch, about 3 of aninch in 
diameter, in the centre of which is a transparent spot; this is the yellow spot (macula 
lutea), with the fossa centralis of the retina (fovea centralis, foramen of Soemmering). 

At this patch, the tissue of the retina is slightly modified, especially at the fossa; 
there are only cones in the columnar layer, and all the other layers appear to be con- 
founded into one granular mass. (This spot only exists in animals which have the axes 
of ae men parallel with each other, as in Man, the Quadrumana, and some saurian 
reptiles. 

There is nothing particular in the aqueous humour, lens, or vitreous humour. 

Accussory ORGANS OF THE VisvaL Arparatus—The orbital cavity of Man is 
entirely inclosed_ by bony walls, and there is no fibrous sheath, (A fold of the orbital 
fascia has been described as separating the eye from its surrounding adipose tissue, and 
which, like a “ tunica vaginalis,” enables the globe to roll with rapidity and precision.) 
The muscles are six in number—four recti, and two oblique; the great oblique is the 
same as in animals. Only the rudiment of a caruncula lachrymalis is present. The 
nasal duct opens at some distince up on the surface of the inferior meatus, 


THE INTERNAL EAR OR LABYRINTH. 837 


CHAPTER V. 


AUDITORY APPARATUS. 


Tue sense of hearing, destined for the perception of sounds produced by the 
vibration of bodies, has for essential agents the auditory or eighth pair of 
encephalic nerves, whose terminal fibrille ramify in the membranous walls 
of a system of cavities forming the internal ear ; these cavities are excavated in 
the substance of the petrous bone, and communicate, externally, by means of 
two other systems of diverticuli, which constitute the middle and eaternal ear. 


Articte I.—Internat Ear, or Lapyrintu. 


(Preparation.—The dissection of this part, from its minuteness and complexity, as 
well as the density of the bone surrounding it, cannot be made with advantage by the 
student. He is, tuerefore, recommended to study it in special preparations, and in the 
following description.) 

The cavities which, together, compose this part of the auditory apparatus, 
being entirely channeled within the petrous portion of the temporal bone, 
have their walls, forming the osseous labyrinth, constituted by that bone. 
They contain the soft parts, named the membranous labyrinth, and fluids 
(endolymph). 

THE OSSEOUS LABYRINTH. 


This is composed of three portions: the vestibule, semicircular canals, and 


1. The Vestibule. 


This is a small, somewhat oval cavity, in the centre of the bone, and out- 
side the perforated bony plate that forms the bottom of the internal auditory 
hiatus. It is areal vestibule, with regard to the other parts of the labyrinth, 
which all open into it. 

On its external wall is the fenestra ovalis (fenestra vestibuli), an opening 
closed by the stapes. The inner shows the foramina through which the 
filaments of the vestibular branch of the acoustic nerve pass. Below, and in 
front, is a large orifice, the commencement of the scala cochlee; above, are 
five little apertures, the openings of the semicircular canals. 


2. The Semicircular Canals. 


Three in number, and very narrow, these canals owe their name to their 
form. They are placed above the vestibule, like three semicircular arches 
united in a triangular manner at their base, and are distinguished as superior 
or anterior, posterior, and eaternal. The first two open together, by their 
adjacent extremities, into the vestibule ; consequently, there are only five 
orifices of the semicircular canals in this cavity ; in addition, the adjoining 
openings of the posterior and external canals are so close to each other, 
that they appear to be sometimes united at the bottom of a short common 


canal. 
3. The Cochlea. 


Situated external to, and below the vestibule, at the inner wall of the 
cavity of the tympanum, the snail-shell or cochlea is well named, as it presents 
exactly the form of certain molluscs’ shells. It is a spiral conical canal, 


56 


838 THE APPARATUS OF THE SENSES. 


twisting downwards, forwards, and upwards, around a central conical axis 
(the modiolus) ; so that its centre nearly corresponds to the inner wall of the 


Fig. 392. 


SECTION THROUGH ONE OF THE COILS OF THE 
COCHLEA. 

ST, Scala tympani; sv, Scala vestibuli; cc, Canalis 
cochlez ; membrana of Reissner.—A/s to Isp, Lamina 
spiralis membranacea; //s, Limbus lamin spi- 
ralis; ss, Sulcus spiralis; gs, Ganglion spirale 
situated on nc, the nervous cochlearis indicated 
by the black line; /so, Lamina spiralis ossea; /, 
Membrana tectoria; 6, Membrana basilaris; co, 
Organ of Corti; dsp, Ligamentum spirale; cc, 
Cells of Claudius.—1, Rod of Corti of the first 
order; 2, Rod of Corti of the second order. 


tympanum. A partition—the 
lamina spiralis, spiral like the 
cavity—divides it into two dis- 
tinct sections or scale: a supe- 
rior and inferior ; this lamina is 
attached by its inner border to 
the central axis of the cochlea, 
but is free at its external margin, 
which does not quite reach the 
periphery of the cavity. The 
two scale, therefore, communi- 
cate, in the skeleton, by means 
of an opening (the helico-trema) 
that follows the free border of 
the lamina spiralis throughout 
its extent. 

The inferior scale (or scala 
vestibuli) enters the vestibule; 
the commencement of the supe- 
rior scale, or scala tympani, is 
formed by the fenestra rotunda 
(fenestra cochlee), which brings 
it into communication with the 
middle ear, without the presence 
of a membrane exactly closing 
that aperture. 


THE MEMBRANOUS LABYRINTH. 
The membranous labyrinth comprises three parts, corresponding to the 


three cavities of the osseous labyrinth: 
circular canals ; 3, The cochlea. 


1, The vestibule; 2, The semi- 


Fig. 393. 1. The Membranous Vestibule. 


SECTION OF THE COCHLEA PARALLEL TO 
ITS AXIS, THROUGH THE CENTRE OF 
THE MODIOLUS. 


This is composed of two sacs with thin, 
soft walls, lodged in the osseous labyrinth; 
the superior is the largest, is oval-shaped, 


1, Modiolus; 2, Infundibulum in which the mo- 
diolus terminates ; 3, 3, Cochlear nerve, send- 
ing its filaments through the centre of the 
modiolus; 4, 4, Scala tympani of the first 
turn of the cochlea; 5, 5, Scala vestibuli 
of the first turn; the septum between 4 and 
5 is the lamina spiralis; a filament of the 
cochlear nerve is seen passing between the 
layers of the lamina to be distributed in the 
membrane investing the lamina; 8, Loops 
formed by the filaments of the cochlear 


nerve on the lamina spiralis; 9, 9, Scala tympani of the second turn of the cochlea 5 
10, 10, Scala vestibuli of the second turn; the septum is the lamina spiralis ; 11, 
The remaining half turn of the scala vestibuli; the dome above is the cupola, the line 
passing through it leads to the remaining half turn of the scala tympani. The 
ossecus lamina forming the floor of the scala vestibuli curves spirally round to con- 
stitute the infundibulum (2); 14, The helicotrema through which a bristle is passed ; 
its lower extremity issues from the scala tympani of the middle turn of the cochlea. 


THE INTERNAL EAR OR LABYRINTH. 839 


ate ie the utriculus ; it communicates with the semicircular canals, of 
eer — Be ass The inferior is smaller, spherical in shape, and 
pian as 3 lt appears to be perfectly closed, though in contact with 
The membranous vestibule is composed of two distinct layers: an 
external, cellular, and an internal, epithelial, resting on an amorphous 
membrane. At the expansion of the nervous filaments, the latter is absent 
and is replaced by a white calcareous substance (minute crystalline particles 
of carbonate and phosphate of lime) which, in the domesticated animals, 
appears as a powder, and is named the calcareous powder of the vestibule, ear 
dust, or otoconites (otoliths). : 
(Some authorities give four layers: an external or serous, derived from 
the lining membrane of the labyrinth ; a vascular, with multitudes of vessels ; 
a nervous, formed by the expansion of the filaments of the vestibular nerve ; 
and an internal serous membrane, which secretes the limpid fluid contained 


in its interior. Spots of pigment are constantly found in the tissue of the 
membranous labyrinth.) 


2. The Membranous Semicireular Canals. 


These are three thin tubes, which correspond exactly with, though they are 
of smaller diameter than, the osseous semicircular canals ; they open into the 
utriculus in the same manner as the latter do into the bony vestibule. Hach 
has one of its two extremities dilated into a sac or ampulla (sinus-ampullaceus) ; 
for the two superior and external canals it is the anterior extremity, and 
for the posterior canal the outer extremity. 

In structure they resemble the vestibular sacs. 


3. The Membranous Cochlea. 


The membranous cochlea is represented by two membranes, which 
complete the lamina spiralis; they continue the osseous lamine of the 
latter, and are inserted into the external wall of the cochlea. 

They give rise to three cavities, or scales, in the interior of this portion 
of the ear: an inferior, or tympanic scala; a superior, or vestibular scala ; 
and a middle or auditive scala, in which the organ of Corti is lodged. The 
vestibular scale is itself divided by the membrane of Reissner into two canals 
—the proper vestibular scala, and Lowenberg’s, or the collateral scala ; so that, 
in reality, there are four cochlean scales. 

We do not, therefore, find in the cochlea, as in the other regions of the 
labyrinth, a system of membranous cavities included in osseous cavities. 

The structure of the membranes that limit the auditive scala is not 
perfectly known, and is still disputed by anatomists; but connective, epi- 
thelial, and nervous elements appear to form their base. : 

With regard to the organ of Corti, it is a very curious and interesting 
portion of the auditory scala, being formed by a series of solid and elastic 
arches resting by their extremities on the membrane—the basilar—that sepa- 
rates the auditory from the tympanic scala, their convexity being towards 
the superior, or membrane of Corti. These arches number about three 
thousand in Man, and are composed of two portions or articles: an external 
and an internal, united by a thickening in the vicinity of the membrane of 
Corti. To these elastic arches.are added conical or fusiform cells, whose 
nature is not yet determined. 


840 THE APPARATUS OF THE SENSES. 


FLUIDS OF THE LABYRINTH. 


These liquids are of two kinds: one is contained in the membranous 
labyrinth, the other in the osseous labyrinth. 

The fluid of the membranous labyrinth, or endo-lymph of Breschet, is con- 
tained in the sacs and tubes constituting the membranous vestibule and 
semicircular canals, It is limpid and fluid like water. The fluid of the 
osseous labyrinth, or peri-lymph of Breschet, fills the two scale of the cochlea, 
and bathes the external surface of the vestibule and membranous semi- 
circular canals, which it separates from the corresponding walls of the 


osseous labyrinth. 


DISTRIBUTION AND TERMINATION OF THE AUDITORY NERVE IN THE MEM- 
BRANOUS LABYRINTH. 


This nerve (the portio mollis of the seventh pair) divides, as we have 
said, into two branches: a cochlear and a vestibular. 

The cochlear branch, the largest, reaches the base of the cochlea, 
where it breaks up into a large number of fasciculi, one portion of which 
expands over the first turn of the lamina spiralis, the other on the second, 
and a third on the third ; the latter ramifications penetrate to the auditory 
scala, and terminate above or below on the organ of Corti. 

The vestibular branch divides into three portions, whose terminal fila- 
ments ramify in the wall of the sacculus, utriculus, and the ampulle at the 
extremities of the three semicircular canals. 

The precise manner in which these filaments of the auditory nerve 
terminate is doubtful. (Breschet says they communicate and form a series 
of minute arches. Some of the filaments of the other nerves pass into the 
sac, and come into contact with the otoconies or ear-dust in its interior.) 

(The membrane of the labyrinth is supplied with blood-vessels by a 
branch of the basilar artery, which passes with the auditory nerve to the 
bottom of the meatus, and divides into twigs corresponding with the nerve 
divisions ; its ultimate ramifications terminating, in the form of a fine net- 
work, on the membranous labyrinth and the spiral lamina of the cochlea. 
The blood is returned by the auditory vein, which enters the superior 
petrosal sinus.) 


Articte IJ.—Mrppie Ear or Tympanum. 


Excavated in the substance of the tuberous portion of the temporal bone, 
on the limit of the petrous and mastoid sections, but chiefly in the latter, 
the middle ear constitutes an irregular cavity, which we may consider as 
composed of two walls and a circumference. 

The eaternal wall is principally constituted by the membrane of the tym- 
panum. The internal wall, formed by the petrous bone, offers two openings—— 
the fenestra ovalis and fenestra rotunda, the one situated behind the other, 
and separated by a small eminence named the promontory. The circumference 
is occupied for nearly the whole of its extent by the mastoid cells, large 
open cavities in the tympanum. 

Internally, the tympanum contains a chain of small bones named the 
malleus, incus, os orbiculare, and stapes ; these bones form the medium of 
communication between the tympanum and the fenestra ovalis—from 
one wall to the other of the cavity of the tympanum, 

This cavity is lined by a fine mucous membrane, which is continuous with 


THE MIDDLE EAR OR TYMPANUM. 841 


that lining the pharynx by means of a cartilaginous canal—the Eustachian tube 
which conveys the external air to the middle ear. ; 

We will glance briefly at the anatomical characters of the parts enu- 
merated, and which enter into the formation of the middle ear. 


1. Membrana Tympani. 


S.tuated on the external wall of the middle ear, which it 
the bottom of the auditory canal, this membrane is oval in ig ts 
thin, dry, and capable of vibrating. Its tnner face, inclining inwards and 
slightly convex, is adherent to the handle of the malleus. Its eaternal 
face is slightly concave (towards the meatus). The circumference is fixed 
ina bony frame named the tympanal circle, which is sharply defined, but 


RIGHT TYMPANIC CAVITY OF THE HORSE'S EAR; ANTERIOR PLANE, VERTICAL 
AND TRANSVERSE SECTION. 


A, Auditory canal; B, Membrana tympani; c, Malleus; D, Incus; &, Os orbiculare ; 
F, Stapes; G, Mastoid cells; H, Fenestra ovalis; 1, Vestibule; J, K, L, Outline of 
the semicircular canals; M, Cochlea; N, Commencement of the tympanic scala. 


incomplete at its upper part, and enveloped by the mastoid cells, whose 
cavitics radiate around this circle. 
Although very thin, this membrane is composed of three layers: a 


842 THE APPARATUS OF THE SENSES. 


middle, of a fibrous (and muscular ) character (fibres radiating towards the 
centre, and also circular); an external, epidermic; and an internal, the 
mueous membrane of the middle ear. It has vessels and nerves in the 
external and internal layers. (This membrane receives those vibrations of 
the air which set in movement the chain of bones in the ear, and thus 
propagates them to the fenestra ovalis and labyrinth. ) 


2. The Promontory, Fenestra Ovalis, and Fenestra Rotunda. 


Placed in the upper part of the tympanic wall, the promontory is only a 
very small eminence separating the fenestra rotunda from the fenestra ovalis. 
(It is marked by grooves in which lie the branches of the tympanic nerves.) 

The fenestra ovalis ( fenestra vestibult), situated in front of the promontory, 
is an opening whose form is sufficiently indicated by its name. It is the 
opening of communication between the tympanum and osseous vestibule, 
and is closed by the base of the stapes and the lining membrane of both 
cavities, 

The fenestra rotunda (fenestra cochlee) is separated from the preceding 
by the promontory, and, placed behind this small projection, it is closed in 
the fresh state by a thin membrane (m. tympani secundaria), that forms a 
kind of diaphragm between the middle ear and the tympanic scala of the 
cochlea. (The aqueduct of Fallopius is a canal commencing at the internal 
ear, passing above the fenestra and promontory, and terminating at the 
mastoid foramen. It contains the facial nerve, which passes through the 
tympanic cavity.) 

3. The Mastoid Cells. 


These cells occupy all the circumference of the tympanic cavity, except 
above. They are small, more or less irregular, and deep spaces, separated 
by thin partitions radiating around the tympanic circle, and whose free 
margin is turned towards the centre of the cavity. 

In several animals, and particularly the Carnivora, the mastoid cells 
form a special compartment in the tympanic case, communicating with the 
latter by a single opening. (In the Sheep and Goat, the mastoid cells and 
their bony septa are entirely absent.) 


4. The Bones of the Middle Ear. (Fig. 895.) 


Four articulating bones (ossicula auditis) named the malleus, incus, os 
orbiculare, and stapes, compose the bony chain of the middle ear; this chain 
extends in a broken course from the external to the internal wall of the 
tympanum. The pieces are movable on each other, and are united by 
ligaments and moved by muscles. 

1. Mauixvus (hammer).—This is the longest of the bones, and offers a 
handle and a head. ‘The handle (manubriwm) is placed almost vertical, and 
firmly fixed to the inner face of the membrana tympani. The head, 
directed upwards, has a diarthrodial facet for articulation with the incus. 
The neck, or upper part of the handle, shows two small processes for insertion 
(processes gracilis and brevis), the innermost of which is very developed. 

2. Incus (anvil)—This bone presents a body or middle portion, and 
two branches, The body is channeled externally by a diarthrodial facet 
corresponding to that on the malleus. Of the two branches, the superior 
terminates in a blunt point; while the other, inferior, is united at its 
extremity to the os orbiculare. 


THE MIDDLE EAR OR TYMPANUM. 843 


3. Os Orpicutare.—This is a little, circular, discoid bone, included 
between the inferior branch of the incus and stapes. 

4. Srares (stirrup)—Remarkable for its shape, which is exactly that 
of a stirrup, this bone is placed almost horizontally. Its summit (or head) 
articulates with the os orbiculare; its middle part is divided into two 
branches, having between them an aperture that is closed by the tympanic 
mucous membrane. Its base is received into the fenestra ovalis, and re- 
sembles that cavity in shape; it is maintained in its position by the mucous 


Fig. 395, 


BONES OF THE MIDDLE EAR OF THE HORSE.—From an unpublished Drawing by Lavocat. 
M, Malleus; 1, Handle; 2, Head.—n, Incus; 1, Inferior branch ; 2, Superior branch ; 
3, Body.—t, Os orbiculare; Ef, Stapes; 1, Summit; 2, 2, Branches; 3, Base.— 
Me, Muscle of the stapes; 0, Bony nucleus in the terminal tendon. 


lining of the tympanum, which passes over the stapes, after being reflected 
around the margin of the fenestra ovalis. 

These bones transmit the vibrations of the membrana tympani to the 
fluid in the labyrinth.) 

5. Ligaments or tHe Avpirory Bonzs.—We need only mention the 
existence of these here, as they are too small and unimportant to merit a 
particular description. 

6. Muscnes or tHe Avpitory Bones.—Four muscles have been de- 
scribed : three destined to move the malleus, and one for the stapes. But 
two of these being extremely small, and their muscular character doubtful 
to many anatomists, we will only notice the internal muscle of the malleus 
and that of the stapes. 

a. The internal muscle of the malleus (tensor tympani, musculus internus 
mallet).—This is a little elongated fasciculus, lodged in a particular groove 
in the mastoid portion of the temporal bone, and arises near the superior 


844 THE APPARATUS OF THE SENSES. 


extremity of the Eustachian tube ; it passes downwards and backwards, and 
terminates by a tendon which is reflected outwards, in front of the fenestra 
ovalis, to be inserted into the neck of the malleus. ; 

b. Muscle of the stapes (stapedius)—Lodged in an excavation in the 
inner wall of the tympanum, near the fenestra vestibuli, on the course of 
the aqueductus Fallopii, this muscle is remarkable for its brevity, its 
relatively considerable thickness, and its conical shape. It terminates by a 
small tendon in front of the head of the stapes. In the Horse, Ox, and 
Sheep, a small bony nucleus is found in the tendon (Fig. 395, oF 

(The tensor tympani retracts the bones of the ear inwards. In con- 
tracting it draws the handle of the malleus towards the cavity of the 
tympanum, and this brings the membrane with it; consequently, the con- 
vexity of the latter is increased and its tension is augmented. In addition, 
while the handle of the malleus is carried inwards, its head is turned 
outwards by a pivoting motion, and this pulls the body of the incus also, 
the long process of which is raised and inclined inwards, pushing the os 
orbiculare and stapes towards the fenestra ovalis. The base of the latter 
bone being in contact with the fluid in the vestibule, this is stirred ; so that 
this muscle likewise acts indirectly in producing the undulations in this 
fluid. The muscles of the tympanum are classed as tensors and laxators. 
It is well to know that all are tensors and none of them act as relaxors ; 
relaxation of the membrane occurring when the muscles are not in action.) 


5. The Mucous Membrane of the Tympanum. 


Very fine and vascular, this membrane coversall the angularities of the 
middle ear, is reflected on the chain of bones, and continued into the 
mastoid cells. It is continuous with that lining the Eustachian tube, and 
thenceforward should be considered as a prolongation of the tegumentary 
membrane spread over the walls of the pharyngeal vestibule. It is covered 
by a simple pavement epithelium. 


6. Eustachian Tube. 


The Eustachian tube is a fibro-cartilaginous canal that communicates 
between the cavity of the middle ear and the pharynx. 

Extending in a straight line beneath the base of the cranium, from the 
tympanic case to the upper and lateral part of the pharyngeal cavity, this canal 
is also named the guttural duct of the tympanum ; itis nearly four inches long 
in Solipeds, “is flattened on both sides, and bordered by the stylo-pharyn- 
geus muscle. Its upper or tympanic orifice is narrow ; the inferior, guttural, 
or pharyngeal orifice, situated near and behind the guttural openings of the 
nasal cavities, is wide, and represents a great slit extending obliquely down- 
wards and outwards; the contiguous borders of this aperture are sustained 
by a cartilaginous plate—a kind of pavilion formed by the expansion of the 
tissue constituting the base of the tube. 

“In its length, the guttural duct is cleft inferiorly, and by this long 
aperture the mucous membrane escapes and descends to form the large sac 
peculiar to monodactyles, known as the guttural pouch. 


7. Guttural Pouches. 
in The mucous membrane lining the Eustachian tube is continuous,forward, 
with that of the pharynx; above and behind, it is prolonged into the tym- 
panic cavity, which it lines. Below, it is dilated and forms the guttural pouch. 


THE MIDDLE EAR OR TYMPANUM., 845 


“Two in number, one being on each side, the guttural pouches lie 
against each other in the median plane, and descend to the larynx, where 
they terminate in a cul-de-sac constituting their fundus. Before and behind 
they extend from the anterior part of the pharynx to the inferior face of the 
atlas. The capacity of each is about $ths of a pint; but in consequence of 
the extensibility of the mucous membrane, the extent and capacity of the 
guttural pouches are particularly variable. 

* Irregular in shape, like the space which it occupies, the guttural pouch 
corresponds, behind and above, to the base of the occipital and sphenoid 
bones. When this reservoir is distended, its lower part, or fundus, descends 
on the lateral portions of the pharynx and larynx, to the lower extremity of 
the parotid gland, in the loose cellular tissue of that region. 

« Externally, the guttural pouch contracts numerous different relations 
in the intermaaillary and parotideal regions, and in its posterior portion. 

“q, In the intermaxillary region, 1t is in relation with the tensor pulati, 
pterygoideus and hyo-pharyngeus muscles, as well as with the internal 
maxillary artery and lingual nerve; it envelops the large branch of the 
hyoid bone, and covers the inner face of the internal pterygoideus muscle. 

“b, In the parotideal region, the guttural pouch responds, above, to the 
inner face of the parotid gland, from which it is separated by the auricular 
vessels and nerves; a little lower, at the posterior angle of the hyoid bone, 
to the stylo-hyoideus muscle and the styloid process of the occipital bone ; 
here the auricular artery passes obliquely upwards and backwards, and 
the membrane of the pouch is more closely united to the parts covering it. 

“ Below this, the guttural pouch is in relation with the stylo-maxillaris 
muscle, external carotid, and the nerves forming the guttural plexus, such as 
the ninth and twelfth pairs, the great sympathetic, etc. Lower, it is related 
to the parotid gland, to the inferior extremity of which it may be prolonged. 

‘“¢, Posteriorly—The guttural pouch is in relation with the atlas, flexor 
muscles of the head, occipital artery, etc.; it forms a fold that envelops 
principally the pneumogastric and sympathetic nerves, and, anteriorly, 
another fold that incloses the internal carotid. 

“The mucous membrane of the guttural pouches is thicker and stronger 
than that lining the Eustachian tube and the cavity of the tympanum. 
Only slightly adherent to the adjacent parts, except at the branch of the 
hyoid, the inner face of the stylo-hyoideus, etc., it is smooth internally, and 
lubrified by the mucus it secretes. It may become the seat of purulent 
collections, which compress the larynx and obstruct the respiration, and it is 
in such cases that the pouch is punctured. This membrane receives 
numerous fine vascular and nervous ramifications from the neighbouring 
branches. 

“The guttural pouches communicate with the pharynx and cavity of the 
tympanum, and usually contain air ; the quantity of this may vary in health, 
according to the degree of dilatation of these membranous sacs. Their 
dilatation is chiefly produced by the palato-pharyngeus muscle, several 
fibres from which extend to their mucous membrane; and, besides, when 
the ear is erected this membrane is thrown into a state of tension, through 
the adhesion of the lower prolongation of the concha to its surface. 

«The functions of the guttural pouches are far from being known. It 
cannot be affirmed that they increase phonation ; indeed, their use appears 
to be rather related to audition, if it be considered that these annexes of the 
guttural duct of the tympanum coincide, in Solipeds, with a less development 
of the mastoid cells than in the other animals. 


846 THE APPARATUS OF THE SENSES. 


“With regard to the Eustachian tube, it serves to renew the air in the 
tympanic cavity, this renewal being indispensable to the perfect accomplish- 
ment of hearing.” —Lavocat. ; : 

(It is essential that the equilibrium between the external air and that 
in the cavity of the tympanum should be maintained, in order to avert 
irregular tension, and even rupture of the membrana tympani. Perosino 
states that the guttural pouches are filled with warm air during expiration, 
and that this is partly changed for cold air in inspiration.) 


Articie III.—Tue Externat Har. 


The external ear comprises the external auditory canal, and a widened 
appendage opening outwardly, designated the concha or pavilion. 


THE EXTERNAL AUDITORY CANAL. 


This canal (meatus auditorius externus), described in the osteology (as 
situated in the petrous bone), has at the bottom the membrana tympani, 
which separates it from the middle ear. Its entrance, the external auditory 
hiatus, gives attachment to the infundibulum of the conchal apparatus. Itis 
lined by a thin integumentary membrane intermediate in character between 
the skin and mucous membrane, and has in its substance a large number of 
glands and convoluted tubes, analogous to the sudoriparous glands, but here 
named ceruminous glands, as they secrete an unctuous matter, the cerumen. 


THE CONCHA OR PAVILION. 


The external trumpet-shaped appendage named the concha (concha auris) 
varies much in shape in the different animals, though in all it offers the 
same details in organisation: a cartilaginous framework composed of three 
pieces, muscles to move these, an adipose cushion to insure liberty of 
movement, and integuments covering the whole. 


1. Cartilages of the Concha. 


The three pieces composing the concha are: 1, The conchal cartilage ; 2, 
Annular cartilage ; 3, Scutiform cartilage. 

1. Concuat Carritace.—The principal portion of the pavilion, this 
cartilage determines its general configuration. In shape, it*resembles a 
trumpet with a wide opening on one side. Its entrance is elliptical, and 
elongated vertically, being circumscribed by two thin borders which unite 
above at a point that constitutes the summit (apex) of the organ. Its base, 
bulging in a cul-de-sac, terminates in front by a constricted infundibulum ; 
it is attached to the margin of the auditory hiatus by means of the annular 
cartilage, and to the surface of the guttural pouch by a pointed prolongation 
that descends outside this annular cartilage, beneath the parotid gland, and 
terminates by several fibrous filaments. This portion of the framework of 
the concha is a cartilaginous plate, rolled on itself in such a manner as to 
circumscribe, between its borders, the entrance to the ear, and to form, in- 
feriorly, the complete infundibuliform canal just mentioned. In Solipeds, 
this plate is rigid and erect, and much more developed in the Ass and Mule 
than in the Horse. (Externally, the integument of the ear is covered by 
ordinary hair, but internally there are long fine hairs, especially near the 
entrance ; these prevent the intrusion of foreign substances.) 

2. Annutar Cartinacs —By this name is known a little ring-shaped 


THE EXTERNAL EAR. 847 


plate, placed at the lower part of the conchal plate, intermediate betwee 
3 i . . . m 
it and the auditory canal. The internal integumentary membrane, with some 
yellow elastic fasciculi, unite this cartilage to the other two portions 
between which it is situated. Its relations with these are such, that it 
receives within its lower border the bony circular prominence forming the 
seine a the i we! rie while it may itself be received into the in- 
undibuliiorm canal of the conchal cartilage—an a i 
the tubes of a telescope. aii oageg 
3. Scurirorm Carritacre,—This is a small cartilagin i 
. . ous plate, situated 
in front of the base of the concha, at the surface of the tatapceal muscle; it 
is irregularly triangular, is attached to the conchal cartilage by some 
muscular fasciculi, and transmits to that cartilage the action of some other 
muscles which are fixed on the cranial bones. 
Aes arteries of the concha proceed from branches of the external carotid 
and the veins pass to a trunk of the same name; the ner divisions 
of the facial and the first cervical pair.) en 


2. Muscles of the External Ear. 


There are found, on the surface of the concha, within and without, some 
fleshy fibres, which are veritable intrinsic muscles. But the slight importance 
of these induces us to pass them over, in order to study exclusively the 
extrinsic muscles, which move the conchal apparatus. These are ten in 
number: in the first layer are the zygomatico-auricularis, temporo-auricularis 
externus, scuto-auricularis eaternus, three cervico-auriculares, and the parotido- 
auricularis; in the second layer, the temporo-auricularis internus, scuto- 
auricularis internus, and the mastoido-auricularis. 

1. Zyeomatico-auricuLaRis (attolens anterior — Percivall ; temporo- 
auricularis—Leyh. Figs. 110,53; 396).—This muscle is generally composed 
of two fleshy bands joined by cellular tissue, and rising from the zygomatic 
process of the temporal bone by means of an aponeurosis common to it 
and the orbicularis palpebre. The inferior of these two bands is inserted 
to the outside of the base of the concha, its fibres mixing with those of the 
parotido-auricularis; the superior band terminates on the outer border of 
the scutiform cartilage. 

Placed immediately beneath the skin, this muscle partly covers the 
superior extremity of the parotid gland, and the zygomatic process. 

It draws the ear forward. : 

2. Trmporo-avricuLaris Exrernus (attolens masximus—Percivall. Figs. 
110, 1; 396).—A very thin, wide muscle, covered by the skin, lying on the 
temporal muscle, united posteriorly to the superior cervico-auricularis, in 
front and outwardly to the zygomatico-auricularis, It arises from the 
whole of the parietal crest or ridge,’ mixing in its upper half or third with 
the muscle of the opposite side; it terminates, by one portion, on the inner 
margin of the scutiform cartilage, and by another, on the inner side of 
the conchal cartilage, by means of a thin fascia that covers part of the 
former cartilage and the external scuto-auricularis. . 

It acts as an adductor of the concha, drawing it inwards ; it also carries 
it forwards, and concurs in making it pivot on itself, so as to bring the 
opening of the ear forward. (In the Oz, the common muscles of the ear do 


1 Owing to this crest bordering the temporal fossa, Girard has thought proper to give 
to the two muscles of the ear attached thereto, the name of temporo-auriculares ; but it 
would be more appropriate to designate them the parieto-auriculares. 


848 THE APPARATUS OF THE SENSES. 


not join on the median line, but are placed at the sides of the head, below 
i F eieueeaee Exrernvs (anterior conche—Pereivall. Fig. 396). 
_Thig muscle may be said to be a dependency of the preceding, whose 
action it transmits to the conchal cartilage, and renders it more complete. 

Extending from the external face of the scutiform cartilage to the inner 
side of the concha, and generally composed of two fasciculi, it is covered by 
the skin and the conchal band of the external temporo-auricularis, while it 
covers part of the internal scuto-auricular muscle. 


Fig. 396. 


San 


MUSCLES OF THE EAR. 

1, Cervico-auricularis superficialis; 2, Temporo-auricularis internus; 3, 4, Tem- 
poro-auricularis externus ; 5, Scutiform cartilage; 6, Scuto-auricularis externus ; 
7, Posterior auricular artery ; 8, Portion of the zygomatico-auricularis ; 9, Orbital 
process ; 10, Temporo-auricularis internus; 11, Temporal muscle; 12, Scutiform 
cartilage; 13, Ditto; 14, Concha of the ear; 15, Scuto-auricularis externus; 16, 
Internal scuto-auricularis ; 17, Parotido-auricularis ; 18, Corrugator supercilii; 
19, Zygomatico-auricularis, 


When this muscle contracts, it principally participates in producing the 
rotatory movement that carries the opening of the concha outwards. 

4, Crrvico-auricuLarges.—(Percivall apparently makes one muscle of 
these three—the retrahentes aurem; Leyh designates them as the cervico- 
auriculares eaternus, medius, and internus. (Fig. 396). Three in number, 
and situated behind the ear, these muscles are broad, thin bands, extending 
from the cervical ligament to the conchal cartilage. With regard to their 
superposition at their origin, they may be distinguished as superficial, middle, 


THE EXTERNAL EAR. 849 


and deep ; the situation of their point of insertion in the concha also permits 
their being classed as superior, middle, and inferior. 

The superior, or superficial cervico-auricularis, closely united to the 
external temporo-auricularis, and covered by the skin, covers the middle 
cervico-auricular, and internal temporo-auricular muscles. Attached by its 
terminal extremity to the middle of the posterior face of the concha, it draws 
that cartilage backwards and downwards. 

The middle cervico-auricularis, comprised at its origin between the other 
two, and intimately attached to them, especially the deep one, is in relation 
with the skin for the greater part of its superficies. Its terminal extremity 
is very wide and thin, and passes over the upper end of the parotid gland, 
to be inserted outwardly into the base of the concha, after being slightly 
insinuated beneath the parotido-auricular muscle. ‘This is a rotator muscle, 
turning the opening of the ear outwards and backwards. 

The inferior, or deep cervico-auricularis, concealed beneath the upper 
extremity of the parotid, to which it adheres closely, is inserted at the base 
of the concha, Its action is similar to that of the middle muscle. 

5. Parormpo-auricutaris (abducens, or deprimens aurem — Percivall. 
Fig. 110, 7).—Lying on the external face of the parotid gland, this is a long, 
thin, ribbon-like band, narrower and thicker af its upper than its under 
extremity. It arises on the tissue of the gland, and terminates outside 
the base of the concha, below the inferior commissure formed by the two 
borders of that cartilage. 

Covered externally by a very thin portion of the cervico-facial cutaneous 
muscle, the parotido-auricularis is an abductor of the ear, inclining it 
outwards. 

6. Tumporo-auricuLaris IntERNUS (atfolens posterior—Percivall. Fig. 
110, 8).—Situated beneath the superficial muscle of this name, and partly 
covered by the superior cervico-auricularis, this muscle is long and triangular 
in shape, bright-red in colour, and extending transversely on the surface of 
the temporalis; it is attached, inwardly, to the sagittal or spur-like ridge of 
the parietal bones, and outwardly, by means of a small tendon, to the inner 
side of the concha, within the terminal insertion of the superficial cervico- 
auricularis. It is an adductor of the ear. 

(In the Oz, this muscle is not covered by the external temporo-auricularis. 

In the Sheep and Goat, it is placed between the parietal bone and that muscle, 
and, to reach the concha, it passes beneath the scutiform cartilage.) 
* 7, Scuro-auricuLanris Inrernus. (Posterior conche—Percivall, Leyh 
makes two muscles of it—small and great.)—This is a muscle composed of 
two short, pale fasciculi, which cross each other very obliquely, are concealed 
beneath the scutiform cartilage and the scuto-auricularis externus, and lie 
directly on the adipose cushion of the ear. They arise from the inner face 
of the scutiform plate, pass backwards, and terminate at the base of the 
coucha, behind the infundibuliform cavity which that cartilage forms at its 
root. This muscle is antagonistic to the superficial muscle of that name, 
as it turns the opening of the ear outwards, and even backwards. 

8. Masrorpo-avricuLaris.— This name is given to a very thin fasciculus 
lying vertically on the inner side of the cartilage, at the entrance to the ear. 
Arising from the margin of the auditory external hiatus, and attached to the 
base of the concha, this little muscle, in contracting, constricts the carti- 
laginous tube with which it is in contact. 


a 


850 THE APPARATUS OF THE SENSES. 


3. Adipose Cushion of the External Ear. 


This cushion, which is never absent, even in the most emaciated animals, 
envelops the base of the concha in front, inwardly, and posteriorly. It 
facilitates the movements of that organ. 


4. Integuments of the External Ear. 


The skin covering the concha is covered with fine close hairs. That 
lining its interior is very thin and vascular, adheres closely to the cartilage, 
and is furnished with long silky hairs, to prevent the entrance of dust into 


the ear. 


DIFFERENTIAL CHARACTERS IN THE AUDITORY APPARATUS OF OTHER THAN SOLIPED 
ANIMALS, 


There are no notable differences in the internal ear. 

In the middle ear, there are some modifications, either in the bones or accessory parts, 
In Ruminants, the auditory bones are like those of the Horse, except that the handle of 
the mulleus is more curved, and the body of the ineus is longer. In the Dog, the handle 
of the malleus 1s covered with small, pointed processes, and the branches of the stapes are 
long and thick. In the Pig, the branches of the latter are slight and inflected, and the 
base is wide and thin: in a word, the stapes of this animal bears no resemblance to a 
stirrup; the malleus is very much inflected forwards. In the last two animals, no osseous 
nucleus is found in the tendon of the stapedian muscle. 

It is needless to say that the fenestra ovalis varies with the base of the stapes. (The 
absence of the mastoid cells in the Sheep and Goat has been already noted.) 

The Eustachian tube exists in all the animals, but the guttural pouches are only 
found in Solipeds. 

In the external ear, the conchal cartilage varies much in shape. It is thin, inclined 
outwards, and widely opened in Ruminants. In the Pig, it differs a little, according to 
breed, though it is always much developed, sometimes erect, but most frequently 
drooping. It is always short, pointed, erect, and open in front, in the Cat. (In this 
animal a small duplicature of the external margin of the conchais often seen.) In Birds 
the external ear is limited to the auditory canal. ; 

(The differences in the muscular arrangement have been noted elsewhere.) 


COMPARISON BETWEEN THE AUDITORY APPARATUS IN MAN AND THAT OF ANIMALS. 


There is nothing to be said regarding the internal ear. The middle ear comprises 
the same parts as that of mammifers other than Solipeds. The handle of the malleus is 
straighter, the incus more voluminous, and the stapes thinner, proportionately, than in 
animals. There is no bony nucleus in the stapedian muscle. The muscle of the malleus 
is lodged in a distinct canal belonging to the Eustachian tube. 

The external ear is composed of only two cartilages: one, forming the base of the 
concha, represents that cartilage in animals; the other, belonging to the auditory canal. 
resembles the annular cartilage in the Horse. The concha is very irregular in shape and 
stands at an angle of from 15° to 45° from the temporal bone: it is convex snperiorly 
and terminates inferiorly by a small lobe. On its anterior face it presents prominences 
and depressions; the former are four in number: the helix, a fold encircling the ear 
behind and above; the antihelix, a concentric prominence, almost parallel “with the 
preceding 3 the tragus, a triangular, pointed process, covered with hair, situated in front 
of the auditory canal (meatus); the antitragus, opposite the tragus behind the canal 
and above the lobule. The depressions are: the concha, a wide cavity. limited by the 
antihelix ; the seaphoid fossa (fossa innominata) situated above the latter; and the "fossa 
nie easily between the nae and antihelix, ; 

; e pavilion of the ear is traversed by several muscular fasciculi i 

influence on its movements. The concha has also extrinsic oe keris 
cularis (attrahens aurem), auricularis superioris (attolens aurem), and the auricularis 
posteriores (retrahens aurem). The action of these on the concha is very slight. : 


BOOK VIII. 


GENERATIVE APPARATUS. 


Inprvipuats in the organic kingdom possess the faculty of reproduction, 
and thus perpetuate the species to which they belong: a grand and beautiful 
law of the vital force, which holds under its care the preservation of the 
organised world. In mammifers, the generation of a new being demands 
the concurrence of two individuals—a male and female—who have inter- 
course under certain determinate circumstances. The female furnishes a 
germ—the ovum, and the male a fertilizing fluid—the semen, which vivifies 
the ovum, and renders it capable of development. 

We have, therefore, to study separately the generative, or genital organs 
of the male, and those of the female. 


CHAPTER I. 


GENITAL ORGANS OF THE MALE. 


Tue semen is elaborated in the structure of the two testicles: lobular glands, 
each of which is provided with an exeretory duct, doubled a great number 
of times on itself at its commencement, to form the epididymis, and destitute 
of sinuosities for the remainder of its extent, which is named the deferent 
canal (vas deferens). This canal carries the fecundating fluid into the 
vesiculee seminales, reservoirs with contractile walls, where it accumulates, 
and whence it is expelled during copulation by passing through the 
ejaculatory canals (or ducts), and the urethral canal. The latter is a single 
canal common to the two apparatus of generation and urinary depuration ; 
it is provided in its course with three accessory glands — the prostate, and 
Cowper’s glands, and is supported by an erectile stalk, the corpus cavernosum, 
with which it forms an elongated organ, the penis, which, in the act of 
copulation, is introduced into the vagina, to the bottom of which it carries 
the spermatic fluid. : ; 

We will successively consider the secretory organs or testicles, and the 
excretory apparatus, comprising all the other organs. 


THE TESTICLES, OR SECRETORY ORGANS OF THE SEMEN. 


The testicles (testes) are two glands suspended on each side of the pines, 
between the thighs, where each occupies a particular serous pouch, the 
vaginal sheath (tunica vaginalis). We will commence by describing this 
cavity, and afterwards the organ it contains, 


852 THE GENERATIVE APPARATUS, 


1. Tunica Vaginalis. 


The tunica vaginalis, in the domesticated animals, is only a diverticulum 
of the abdominal cavity, the serous membrane of which—the peritoneum— 
becomes a hernia in the inguinal canal, passing through the upper (internal) 
inguinal ring, and prolonged below the inferior (external) ring, 80 as to 
form a serous sac, which is enveloped by membranous walls. 

We have to study, in the vaginal sheath: 1, Its tlerior; 2, The 
enveloping membranes which form the external walls, and to which we give 
the common name of scrotum. 

Interior. —The serous sac constituting the tunica vaginalis, is vertically 
elongated, and slightly inclined downwards, inwards, and backwards. Its 
inferior eatremity, forming the bottom, or cul-de-sac, is pear-shaped, and 
lodges the testicle and its epididymis. Its middle portion, contracted into a 
narrow canal, contains the spermatic cord. The superior extremity, or 
entrance, is open, to maintain communication with the abdominal cavity ; 
through it pass the spermatic vessels and vas deferens. 

As has been said, the peritoneum forms the vaginal sac. As in the 
abdomen, it is divisible into two layers—parietal and visceral. The latter 
(tunica vaginalis propria) covers the testicle and the cord ; while the former 
(tunica vaginalis communis, or reflexa) lines the innermost of the membranous 
coverings which serve as a wall to the tunica vaginalis, These two layers 
are made continuous by a serous frenum, analogous to the mesentery which 
sustains the floating colon ; like it, it is formed by the junction of the two 
layers. Flat, elongated from above to below, and extending vertically from 
one end of the sheath to the other, this frenum is attached, by its upper 
border, behind the spermatic cord; its lower extremity passes over the 
epididymis, and from it on to the testicle; above, it is continued into the 
abdominal cavity, in accompanying the different canals composing the cord. 

(A small quantity of serous fluid is usually present in the tunica 
vaginalis. When in excess it gives rise to hydrocele. ) 

Enve.oring Mempranes.—The stratified layers that form the external 
walls of the vaginal sheath, and which are generally described in anatomical 
treatises, with the two serous layers, as the envelopes of the testicle, are four 
in number. Reckoning them from within to without, they are the fibrous 
tunic, cremaster muscle, dartos, and scrotum. 

Fisrous Tunic (infundibuliform fascia).—This forms the most complete 
covering to the tunica vaginalis, extending, as it does, over the whole surface 
of the parietal serous layer, to which it is closely adherent. Very thin, 
especially at the points corresponding to the cremaster, this membrane is 
continuous, around the upper inguinal ring, with the transversalis fascia, of 
which it is only a dependency ; its external face is in relation with the 
cremaster and dartos. 

Cremaster.—This muscle is usually described as an envelope of the 
testicle, by the name of tunica erythroides. In the domesticated animals, it 
is a bright-red band, attached, above, to the inner or peritoneal surface of 
the ilio-lumbar aponeurosis; it descends into the inguinal canal, envelops 
outwardly only the middle portion of the sheath of the testicle, and expands 
below on the cul-de-sac, where its fibres terminate by small tendons, which 
are inserted into the external surface of the fibrous tunic. Therefore it is 
that the envelope the cremaster forms is very incomplete, the greater portion 
of the testicle, and the inner side of the cord, being left unprotected by this 
muscular tunic. It is in relation, inwardly, with the fibrous membrane, to 


THE MALE GENITAL ORGANS. 853 


which it is united by a plentiful cellular tissue ; externally, it responds to 
the posterior wall of the inguinal canal and the dartos. 

It is the contraction of the cremaster that causes the sudden ascent of 
the testicle. 

Dartos.—The tissue composing this tunic is contractile; it is con- 
stituted by a mixture of elastic and unstriped muscular fibres. The dartoic 
tunic does not reach the inguinal canal; consequently, it does not cover 
that part of the tunica vaginalis. It forms a pouch below the inguinal ring, 
and is spread from around the margin of this on to the neighouring parts, to 
which it adheres somewhat closely ; it is prolonged, gradually thinning, into 
the sheath of, and even on to the penis itself, and to the tunica abdominalis, 
as well as between the thighs. The two pouches it forms are quite in- 
dependent of each other, never becoming confounded, though placed in 
contact on the mesial line to form a double partition (septum scroti), whose 
leaves are separated above for the passage of the penis. The dartos is in 
relation, inwardly, with the fibrous and erythroid tunics, from which it is 
isolated by an abundance of lamellar cellular tissue, which is very condensed 
towards the globus major epididymis, and forms at this point a kind of cord 
that passes from the fibrous tunic to the dartos, adhering strongly to each. 
Externally, the dartos is covered by the scrotum. 

This tunic determines the vermicular movements of which the scrotum 
is the seat. ; 

Scrotum.—The different membranes enumerated above are double, one 
being for each tunica vaginalis; but the scrotum constitutes a single pouch, 
enveloping the two testicles at the same time. It is merely the portion of 
skin covering this region, and is thin, and so closely adherent to the dartos, 
that it can only with difficulty be separated from it. It is covered by 
very short fine hair, and the extremely numerous sebaceous follicles in its 
texture secrete an unctuous matter that renders its surface soft to the 
touch. 

(There are also numerous sudoriparous glands, and these, with the 
sebaceous glands, keep the skin soft and pliable, and modify the effects of 
friction during progression. On its surface it shows a raphé or seam in the 
middle, which is a trace of its primary division, and corresponds to the 
median septum separating the testicles.) 


2. The Testicles. (Figs. 897, 398, 401.) 


External Conformation—Each testicle is oval in shape, flattened on both 
sides, lodged in the cul-de-sac of the tunica vaginalis,’ and suspended at the 
extremity of the spermatic cord. The description of this organ is extremely 
simple ; it offers for study two faces, two borders, and two extremities. 

. The faces, external and internal are smooth and round. The inferior 
border is convex’ and free, like the faces; the superior, almost straight, is 
related to the epididymis, which adheres to it by its head and tail. 

Means of Attachment.—The testicle is freely pendent in the lower 
part of the tunica vaginalis, where it cannot readily be displaced, because of 
the narrowness of the space containing it. It is suspended, by its upper 


1 One or both testicles may be retained in the constricted portion of the tunica 
vaginalis, or remain in the abdomen; animals in which this occurs are named monorchids 
or cryptorchids. The absence of one or two testicles (anorchidism) is extremely rare. 
Ectopiz of the testicles is the designation applied to these organs when they are found 
elsewhere than in their ordinary situation. 


57 


854 THE GENERATIVE APPARATUS. 


border, to the testicular or spermatic cord :' a thick funiculus contained in the 
middle portion of the vaginal ie and formed by the aggregation of the 
i els with the vas deferens. 
eae itself sustained in the sheath by the frenum that unites the 
nics of that cavity. ; 
ee ane of the serous tunic that covers the exterior 
of the testicle, there enter into its structure a Jibrous membrane, lassue proper, 
and vessels and nerves. The excretory duct will be studied separately. 

Fibrous Membrane.—This membrane, designated the tunica albuginea, 
forms a strong resisting shell around tke testicle, and its texture is 
channeled by sinuous spaces which lodge the large spermatic vessels. It 
is covered by the visceral layer of the tunica vaginalis, to which it closely 
adheres ; its inner face sends thin septa into the proper substance of the 
gland, which divide the latter into the spermatic lobules. Towards the 
upper border of the testicle, and in front, the tunica albuginea is slightly 
thickened ; this part is named the corpus Higmori (or mediastinum testis), 
and at this point the seminal ducts pass through it to reach the epididymis, 

(This membrane is dense and inelastic, being composed of white fibrous 
tissue interlacing in every direction.) - 

Tissue proper—The proper substance of the testicle resembles a 
greyish-yellow pulp, contained 
in the tunic albuginea; it is 
uw divided by the prolongations 

which that tunic sends into its 
interior into small distinct 
] lobules (lobuli testis), independ- 
| 


Fig. 397. 


ent of each other. These 
lobules vary in number, from 
two to three hundred, and all 
have the same organisation, 
each being constituted by two 
or three extremely convoluted 
. filiform tubuli, about from one 
to two yards in length. These 
tubes, the tubuli seminiferi, 
anastomose frequently with 
each other: near their extremi- 
ties, twine together, and can be 
unwound like a ball of thread. 
One of their extremities ter- 
minates in a cul-de-sac, the 
ic other being detached from the 
ay) lobule, and enters a central 
A TESTICLE (HUMAN) INJECTED WITH MERCURY. system of excretory ducts which 
a,a, Lobules formed of seminiferous tubes; b, Rete will be referred to imme- 
testis; c, Vasa efferentia ; d, Flexures of the efferent diately. 
vessels passing into the head, e, e, of the epididy- . 
mis; f, Body of the epididymis; g, Appendix ; A, 
Cauda; i, Vas deferens ; 


\U 


TUS) 


When we cut through a, tes- 
ticle vertically and lengthways, 
so as to divide the corpus High- 
mori into two lateral portions, there is seen in its substance a whitish 


1 In surgical anatomy, there is sometimes included in the spermatic cord the middle 


port'on of the tunica vaginalis and all its envelopes—the serous, fibrous, and erythroid 
tunics, 


THE MALE GENITAL ORGANS. 855 


a ee Roe apparent, which, curving upwards at both 
ities, at body to the posterior end of the testicle, 
where it disappears ; from this are given off a large number of fibrille 
Nae ec testis), which diverge in all directions. A mercurial injection 

y the vas deferens, shows that this part of the testicle is chiefly formed 
by a ramifying system of rectilinear canals with very thin walls, which 
open into each other, and unite, on reaching the corpus Highmori, into 
about twenty principal trunks. These are named the straight canaliculi (vasa 
recta), to distinguish them from the convoluted tubuli; they receive the 
latter at their exit from the lobules, and are surrounded by numerous blood- 
vessels and sustained by the fibrous septa of the tunica albuginea, which 
appear to converge towards the point they occupy. At the corpus Highmori 
the vasa recta pass through that body, forming in its texture an anasto- 
mosing network, the rete testis, and are continued into the epididymis as the 
efferent canals (vasa efferentia). 

The seminiferous tubes inthe lobules Fig. 398. 
are from +}, to the ~4, of an inch in 
diameter. They are composed of a 
very thin fibrous membrane (firmer 
than that in the walls of similar gland 
canals elsewhere); slightly elastic, 
and made up of connective tissue 
with longitudinal nuclei, this mem- 
brane is lined internally by a proper 
amorphous membrane (basement) and 
epithelium. The latter almost com- 
pletely fills the tubuli; near the wall 
of the canal it is composed of polygonal 
cells, but towards the centre these in- 
crease in volume, become circular and 
transparent, and show several nuclei 
in various stages of transformation ; 
finally, in the axes of the tubuli can 
be perceived spermatozoa and the 
detritus of the spermatic cells. 

Vessels and nerves.—The blood is 
carried to the testicle by the spermatic 
artery, which is almost exclusively 
appropriated to it; this vessel, after 
describing a great number of very 
remarkable flexions, enters the upper VERTICAL SECTION OF THE TESTICLE 
border of the gland, a little behind Saale PASSING "THROUGH! THE CORPUS 
the epididymis. it does: mob maing- 1, Spermatic cord, with its serous covering ; 
diately plunge into its substance, how- 2, Sections of the flexuous vessels of the 
ever, but passes within the texture of cord; 3, Head of the epididymis, or globus 
the tunica albuginea, along the borders major ; 4, Tail of the epididymis, or globus 
of the testicle, and forms a complete miners 5, Vas deferens; 6, Corpus High- 

b i : : . mori; 7, Rete testis; 8, Tunica albuginea 
circle around it. From this circle it sending prolongations from its inner face: 
sends off divisions, which spread over and which divide the testicle into lobules ; 
the sides of the organ, detaching fine 9, Surface of the tunica albuginea. 
arterial ramifications that penetrate its 
proper tissue in accompanying the interlobular septa. (There is generally 
described a tunica vasculosa that forms one of the coverings of the testicle. 


856 THE GENERATIVE APPARATUS. 


This, in reality, is not a distinct coat, but merely the fine ramifications of 
the spermatic artery spreading beneath the tunica albuginea, and held 
together by delicate cellular tissue.) ; 

The veins are very voluminous and frequently varicose, and comport 
themselves like the arteries; they unite in a single trunk that enters the 
posterior vena cava, near the renal veins. (On the cord, in addition to their 
sometimes varicose condition, the spermatic veins have been observed to 
form a network,-named the pampiniform pleaus.) 

The lymphatics are most numerous beneath the serous layer and the 
tunica albuginea. They commence in the lacune between the seminal tubes 
and vessels, and terminate in the sublumbar glands. 

The nerves of the testicle are derived from the sympathetic (and pass 
from the abdomen with the blood-vessels); they form a small particular 
plexus around the artery. (The nerves pierce the membrana propria of the 
tubuli seminiferi, and end in a more or less pyramidal mass of protoplasm, 
in which le clear elliptical nuclei. The ends of the fibres, therefore, lie 
in close proximity to the outer layer of secreting cells.) 

Devetopment.—In the foetus, at an early age, the testicle floats in the 
abdominal cavity, being suspended from the sublumbar region, near the flank, 
by a wide peritoneal fold, at the anterior border of which are the spermatic 
vessels (Fig. 399, ¢.); the tunica vaginalis is not yet present. The 
mechanism of the formation of this is very simple, and easy to understand. 
The visceral layer of the tunica vaginalis, which envelops the testicle and 
the cord, being already formed, as well as the serous freenum that establishes 
continuity between this and the parietal layer in the adult animal, it only 
remains to explain how nature proceeds to construct the vaginal sac in which 
the gland is afterwards contained. 

We have remarked, that to the posterior extremity of the testicle is 
attached a thick round funicle, the other end of which passes into the upper 
inguinal ring, being enveloped by the peritoneum, and fixed to the posterior 
border of the serous layer that suspends the testicle. This funicle is the 
gubernaculum testis, and is continuous, by its inguinal extremity, with the 
dartos, whose structure it apparently shares, and which alone acts as the 
scrotal sac to it. The serous layer covering it has on its outer adherent 
face the cremaster muscle, which is attached to the ilio-lumbar aponeurosis 
in the vicinity of the inguinal ring, enters the serous tube formed by the 
peritoneal envelope of the gubernaculum, and advances by its terminal 
extremity to near the testicle. To this organ is due the principal share in 
the formation of the vaginal pouch. 

When the progress of development in the foetus pushes the testicle 
towards the inguinal region, the gubernaculum acts as a guide, as its 
picturesque name sufficiently indicates. It is the first to descend into the 
inguinal opening, drawing the testicle after it. But in performing this 
movement it also carries along its peritoneal covering, which eradually 
leaves it to become related, by its adherent face, to the walls of the 
inguinal canal; and thus this membrane becomes reflected, just as would a 
sock everted or turned down from the leg to the foot, the latter being 
supposed to represent the testicle. 

The parietal layer of the vaginal sac is, then, nothing more than the 
serous tube that, in the foetus, enveloped the gubernaculum testis while in 
the abdomen, and which is reversed on the testicle and cord after their 


descent into the scrotum, the cremaster muscle on its adherent face having 
become external. 


THE MALE GENITAL ORGANS. 857 


Tn all species, the descent of the testicle commences before birth: in the 
Bovide it is even achieved in the early months of intra-uterine existence. 
In Solipeds, however, the testicle most frequently remains in the inguinal 
canal until the animal is from six to ten months old. 


VHE INTERNAL GENITO-URINARY ORGANS, WITH THE STOMACH, LIVER, AND SPLEEN, 
IN THE FETUS OF A MARE. 

R, Left kidney; v, Bladder; T, Testicle; at, Spermatic artery; G, Gubernaculum 
testis; e, Epididymus—the letter is placed in the centre of the serous layer which 
suspends the testicle and spermatic vessels from the sublumbar region, and after 
the descent of the gland, forms the frenum between the two layers in the vaginal 
sheath; E, Stomach; F, Liver; f, Lobus Spigelii; Pp, Vena porte; ¢, Umbilical 
cord; 0, Umbilical vein ; 0’, Intrahepatic course of that vein, indicated by a double 
dotted line. 


Founcrion.—The testicles secrete the spermatic (or seminal) fluid. Pure 


semen, such as is derived from these glands, is a white, viscid, odorless, 


858 THE GENERATIVE APPARATUS. 


and slightly alkaline fluid. It contains a small quantity of liquid matter 
(liquor seminis), in which is an innumerable mass of spermatozoa. After 
the semen has passed through the genital canals, it is made much more 
aqueous by the addition of the fluids secreted by the walls of these excretory 
ducts, or by the glands annexed to them. 

The spermatozoa, zodsperma, spermatozoides, or spermatic filaments, are 
little elongated bodies from gf to yy Of a line in length. They have a 
pyriform, flattened, or lancet-shaped head, and a filiform tail terminating in 
a point; this tail is often furnished at its origin with an enlargement, or 
unilateral or bilateral ale. Their form is slightly modified during their 
course through the excretory ducts. (In the different species, though 
possessing certain fixed characters, the spermatozoa yet offer some curious 
diversities. Some of these are well exhibited in the annexed representations 
of these particles, found in the semen of very dissimilar animals.) 

The spermatozoa move b 


Fig. 400. undulations of the tail (Grohe 
attributes the motion to the 

6 = contractile protoplasm con- 

tained in the head). Their 


. movements persist for several 


a if days in the genital organs of 

the female ; they are suddenly 
7 arrested by water, acids, and 
y, A . the electric spark; on the 


contrary, they are animated 
by alkaline fluids. (The 
movements cease when the 
spermatozoa are exposed toa 
temperature of 120° Fahren- 
heit.) These bodies are de- 
veloped in the cells of the 
tubuli seminiferi by a modi- 


fication of their contents. 
rmatozoon of t rog; 2, Of the triton; 3 . 

: acy “L OF a fal ee 5 of the ies The cells (vesicles of “a 
hog; 6, Sheep; u, Head with nucleus; 2, Body; lution) become round in the 
¢, Tail. centre of these canals, and 

have from one to ten nuclei; 
the latter are elongated, and throw out a prolongation that gradually 
extends and forms the tail of the spermatozoon. When all the nuclei are 
thus transformed, the cell-wall ruptures and liberates the spermatozoa, which 
swim about in the minute quantity of fluid resulting from the destruction of 
the cells. 


EXORETORY APPARATUS OF THE SEMEN, 
1. The Epididymis and Deferent Canal. (Figs. 397, 398, 399, 401, 402.) 


Epmpipymis.—The organ thus named commences the excretory canal of 
the testicle. It is a body elongated from before to behind, placed against 
the upper border, and a little to the outside, of the spermatic gland. It has 
a middle portion and two extremities. 

The middle is contracted, flat on both sides, and free outwardly ; it is 
related, inwardly, to the spermatic vessels and the testicle, to which it ig 
attached by a very short serous layer. The extremities are expanded, and 
adhere intimately to the testicle. The anterior, the largest, is named the 


THE MALE GENITAL ORGANS. 859 


head of the epididymis or globus major. The. posterior, the tail of the epidi- 
dymis, or globus minor, is more detached from the testicle, and is curved 
upwards to be continued by the deferent canal (vas deferens). 

Srrvcrure.—The epididymis is constituted by a long duct doubled o, 
great number of times on itself, and whose convolutions, after injection with 
mercury, can be very readily seen through the serous membrane. This 
duct results from the union of from twelve to twenty small tubes, the 
efferent ducts, which, arising from the rete testis, open together, at a variable 
distance, into the globus major. Towards the globus minor there is only 
one duct, which is more voluminous and less flexuous, and finishes by 
becoming detached from the posterior lobe of the epididymis to constitute 
the vas deferens. é 

The organisation of the walls of these ducts is not the same throughout. 
‘Thus, in the efferent ducts, it comprises a simple ciliated epithelium, resting 
on a proper amorphous membrane, which again is placed on unstriped 
circular fibres attached to a thin fibrous tunic; while beyond, there is. 
observed a stratified ciliated epithelium, a proper membrane, two layers of 
unstriped fibres—circular and longitudinal—and also a fibrous tunic. The 
thickness of the muscular layers increases from before to behind. 

The epididymis receives its arteries and nerves from the same sources 
as the testicle. 

Dererent Canat (vas deferens).—This duct is about the thickness of a 
goose-quill, and is at first flexuous, then Fic, 401 
straight. It lies parallel with, but behind eres 
and to the inner side of, the spermatic vessels, 
as far as the opening of the tunica vaginalis ; 
passing through this opening, it enters the 
pelvic cavity, and crosses obliquely the ureter 
and obliterated cord of the umbilical artery. 
It is then inflected backwards, placed above 
the bladder, suddenly dilates, and is prolonged 
as far as the neck of that reservoir, where it 
terminates; after having penetrated beneath 
the prostate gland by a sudden contraction, 
at the origin of which, and outwardly, the 
vesicula seminalis opens, and is continued 
by the ejaculatory ducts. 

The vas deferens is sustained in the 
tunica vaginalis by a very short serous fold, 
a dependency of the freenum, whose two lay- 
ers envelope the spermatic vessels, within 
and behind which this duct is situated. In 


DIAGRAM OF THE TESTICLE 
(HUMAN). 


: aie 1, Mediastinum testis, containing 
the abdominal cavity, it is fixed by the pro- ‘the rete testis; 2, 2, Trabeculi; 


longation of this serous duplicature. Its 3, One of the lobules; 4, 4, Vas 
dilated or pelvic portion is in contact, — tecta; 5, Globus major ; 6, Globus 


i i i . inor; 7, Vas deferens. 
superiorly, with the vesicule seminales, and minor; 7, 


is finally united to its dilated homologue of the opposite side, which it 
has been gradually approaching, by means of a triangular peritoneal fold, 
that comprises between its two layers a small club-shaped cavity which 
will be alluded to again. 

The calibre of the vas deferens is very small in its vaginal and abdo- 
minal portions, but is greater towards the pelvic dilatation, where the walls 
of the duct offer a well-marked areolated disposition. 


860 


SrructurE.—The vas defe 
d with cylindrical epithelium, 
tile and a fibrous tunic. 
unstriped fibres: the deep and superficial planes have 
d the middle circular fibres. It is, proportionately, very 
of the duct, and it is to its great density that 


mucous membrane covere' 
externally, a contrac 
of three planes of 
longitudinal, an ; 
thick at the dilated portion 


THE GENERATIVE APPARATUS. 


rens is formed, internally, by a very fine 


and to this is added, 
The contractile layer is formed 


the vas deferens owes its consistence as & hard, rigid cord. The mucous 


membrane of the 


pelvic dilatation has tubular 


and acinous glands. 


2. The Vesiculee Seminales and Ejaculatory Ducts. (Fig. 326.) 


The vesiculcee seminales are two oval 
Fig. 402. 


SUPERIOR VIEW OF THE PELVIC POR- 


TION OF THE VASA DEFERENTIA, 
VESICULZ SEMINALES, PROSTATE 
GLAND, COWPER’S GLANDS, AND THE 
INTRAPELVIC PORTION OF THE 
URETHRA. 

1, Left vas deferens; 1’, Its pelvic 
dilatation; 2, 2, The same on the 
right side ; 3, 4, Vesicule seminales ; 
5, The third vesicula; 6, Serous 
layer uniting the vasa deferentia; 
7, That comprised between the two 
vesicule; 8, Prostate gland; 9, 
Bladder seen through the serous 
fold of the vasa deferentia; 10, 
Membranous or intrapelvic portion 
of the urethral canal, covered by 
Wilson’s muscle; 11, 11, Cowper’s 
glands enveloped by that muscle; 
12, 12, Ischio-cavernosus muscle; 
13, Accelerator urine muscle. 


pouches whose volume varies with 
their contents, and which are placed in the 
pelvic cavity, above the bladder and the vas 
deferens. Each vesicula has a middle portion 
and two extremities. The middle portion is 
enveloped by a loose abundant cellular 
tissue, and is in relation with the rectum 
above, and below with the bladder and vas 
deferens. 

The anterior extremity is the largest, 
and forms a rounded cul-de-sac, covered in 
almost the same manner as the bladder by 
the peritoneum, which at this point fur- 
nishes a very small triangular freenum (the 
recto-vesical fold) that unites the two vesi- 
cule. The posterior extremity tapers to @ 
narrow neck, which passes beneath the pros- 
tate gland, and joins at a very acute angle 
the terminal extremity of the vas deferens, 
to constitute the ejaculatory duct. 

The walls of this pouch are composed 
of three membranes: an internal mucous, a 
middle muscular, and an external fibrous. 
The mucous layer is continuous with that 
of the ejaculatory ducts, and is very thin, 
delicate, and follicular. It shows numerous 
folds, which disappear with distention of the 
duct. The middle layer evidently belongs 
to the class of muscular membranes; its 
identity with that of the bladder is complete. 
At the bottom of the cul-de-sac it gives off 
several fasciculi, which radiate on the ex- 
ternal surface of the peritoneum. (In addi- 
tion to these, the vesicula and vasa defe- 
rentia have a muscular covering whose fibres 
are arranged in a longitudinal and trans- 
verse direction, the latter being the most 
superficial. This muscular layer being con- 
tinuous over the vesicule seminales and vas 
deferens, when it contracts, will compress 
and shorten these ; consequently, it has been 
named the compressor vesicule ct ductus 


THE MALE GENITAL ORGANS. 861 


seminalis. The fibrous coat of the vesicule is merely condensed cellular 
tissue.) The mucous and muscular coats are supplied with blood by the 
vesico-prostatic artery (inferior vesical) ; their nerves are derived from the 
pelvic plexus. 

The richness in glands of the mucous membrane of the vesicule 
seminales, has led several anatomists to consider them as organs of secretion, 
and not as reservoirs for the semen. But the large cavity that each forms, 
appears to demonstrate that they serve as reservoirs and secretory organs at 
the same time. Their fluid production is added to the semen, as is the 
secretion of the prostate and Cowper’s glands. 

The ejaculatory duct is very short, and succeeds the narrow canal of the 
vesicula after the latter opens into the vas deferens. The two ducts pass 
between the prostate gland and urethra, and, after a brief course, terminate 
in the latter, on the side of the veru montanum—a tubercle which will be 
noticed presently. 

Near to, and in front of this tubercle, is a third very small orifice—the 
opening of the third pouch included between the serous duplicatures joining 
the vasa deferentia. (This is the sinus pocularis, or utriculus prostatia, 
vesicula seminalis tertia or media of Gurlt.) Improperly designated the 
third vesicula, or masculine uterus (Weber), this pouch (sometimes double) 
secretes a fluid which is thrown into the urethra. (This third vesicula is 
present in all the domesticated animals.) 

The ejaculatory ducts may become obliterated ; then the secretion of the 
vesicule seminales accumulates in their interior, and gradually distends 
them until they attain enormous dimensions. We found, in a Gelding, a 
vesicula which was nearly as large as the bladder; it contained a brownish, 
sticky fluid, holding in suspension epithelial cells, free nuclei, and mucus 
corpuscles, 

(The vesicule seminales, in addition to their own secretion, receive the 
semen conveyed by the spermatic ducts, and keep it in reserve until 
copulation ; when the contraction of its muscular apparatus expels it into the 
ejaculatory ducts, and from these into the urethral canal.) 


8. The Urethra. 


The urethra is a canal with membranous and erectile walls, commencing 
at the neck of the bladder, and terminating at the free extremity of the penis. 

Course—When followed from its origin to its termination, it is seen to 
proceed at first horizontally backwards, then bend downwards at the ischial 
arch to leave the cavity of the pelvis, placing itself between the two roots of 
the corpus cavernosum, and passing forward in the channel formed at the 
lower border of these, until it arrives at the head (glans) of the penis, where 
it terminates by forming a small (cylindrical) prolongation, named the 
urethral tube. In its track, the urethra is divided into two very distinct 
portions: the intrapelvic, the shortest, and the ewtrapelvic, the most ex- 
tensive, and supported by the corpora cavernosa, The latter division being 
alone enveloped by the erectile tissue that enters into the formation of the 
urethral walls, has been also named the spongy portion, the first being 
designated the membranous portion. 

Interior.—Internally, this canal has not the same width throughout. 
Very constricted at its origin, towards the neck of the bladder, it expands 
somewhat suddenly at the prostate gland; its dilatation, improperly named 
in Man the cul-de-sac of the bulb (bulbous portion), or, better, the ventriculus, 


862 THE GENERATIVE APPARATUS. 


extends to its curve over the ischial arch, where it gradually contracts, 
After this it preserves the same reduced dimensions throughout its course, 
though these dimensions may be increased during the passage of the urine 
or semen. There is, however, behind the urethral tube a small oval 
dilatation, named the fossa navicularis (Fig. 403). Even throughout its 
extrapelvic portion, the inner surface of the urethra offers, near the neck of 
the bladder, and on its upper wall, the excretory orifices of the prostate gland, 
and which form two lateral lines of minute perforated tubercles. Between 
these two lines is found the urethral ridge or veru montanum (caput gal- 
linaginus), a little eminence elongated from before to behind, on the sides of 
which the ejaculatory ducts open. Behind this are the excretory orifices 
of Cowper’s glands. ace ; 

Relations—The intrapelvic portion of the urethra is in relation, above, 
with the prostate, which adheres closely to it, and with the rectum, to 
which it is united by the abundant loose connective tissue in this part of the 
pelvis ; below, it lies on the internal obturator muscle ; laterally, it is related 
to the muscles and ligamentous or aponeurotic expansions that close in the 
sides of the pelvis. Without the pelvic cavity, the urethra is united in the 
most intimate manner to the corpora cavernosa, which embrace its anterior 
border. By its posterior border, it is related to the suspensory ligament of 
the penis. 

Srructurz.—The urethra is composed of: 1, Mucous membrane ; 2, An 
erectile envelope; 8, Muscles; 4, Vessels and nerves; and, 5, we will add 
some remarks concerning the perineal aponeuroses, which are in immediate 
relations with this canal. 

1. Mucous Mzmprane.—This is rather delicate, and forms the lining of 
the canal; it is continuous, posteriorly, with that of the bladder, and in 
front with the integument enveloping the head (glans) of the penis ; it is also 
prolonged into the excretory ducts of the glands annexed to the urethra and 
the ejaculatory ducts. It has longitudinal folds, and is always in contact 
with itself, except during the passage of urine or semen; it has scarcely any 
papillae, only a few being found near the anterior extremity of the canal. 

The epithelium of this membrane is stratified and cylindrical, but at the 
portion furnished with papille it becomes pavemental. 

2. Erecrire Envetore.—This envelope, lying outside the mucous mem- 
brane, does not cover the intrapelvic portion of the canal. It commences a 
little above the ischial contour, behind Cowper’s glands, by a very thick 
bulging portion, named the bulb of the urethra. In front, it terminates by 
another bulbous enlargement, into which the anterior extremities of the 
corpora cavernosa enter, named the head of the penis (glans penis). 

The tissue composing this envelope has the same organisation as other 
erectile apparatus, being a network of communicating cavities separated by 
elastic septa, the latter showing in their structure some contractile elements, 

3. Muscies.—Behind the prostate gland, the mucous membrane of the 
urethra is covered by a fleshy layer of circular fibres, forming Wilson’s 
muscle, Another muscular envelope, constituting the bulbo-cavernous or 
accelerator, also covers the erectile tissue of the urethra, accompanying it to 
near the glans, where it gradually disappears. To these two principal 
muscles of the urethra are added two pairs of secondary fasciculi—the 
ischio-urethral and transversus perinei. This is the description of the 
muscular apparatus : 

a, Wilson's muscle—This may be described as a single muscle com- 
posed of two portions, an inferior and superior. Both are formed by 


THE MALE GENITAL ORGANS. 863 


transverse fibres thrown over the membranous portion of the urcthra, and 
united at their extremities, which are attached by means of aponeurotic 
fasciculi, to the lateral walls of the pelvis. Behind, the superior fibres 
cover Cowper’s glands, and, like the inferior, are mixed with the accelerator 
urine. 

b. Accelerator Urincee.-Composed of transverse fibres encircling the 
urethra from the ischial arch to the free extremity of the penis, this will also 
be studied as a single organ, separated into two lateral portions by a median 
raphé passing along the whole posterior face of the urethra. ‘he fibres pass 
from this raphé to the right and left, enter the furrow of the corpora 
cavernosa, and reach the upper surface of the urethra, where they advance 
towards each other; they do not join; so that the circle formed by this 
muscle is necessarily incomplete. 

ce. Ischio-urethral muscle (compressor urethre).—This is a thin fleshy 
band, pair, situated below and at the side of the membranous portion of the 
urethra. Attached by some aponeurotic fibres to the ischial arch, this 
muscle passes forward on Cowpez’s gland, whose lower face it covers. At 
the periphery of that organ, it is confounded with the portion of Wilson’s 
muscle that envelops its upper surface. 

d. Transversus perinei.—This is a very thin ribbon-like fasciculus, often 
scarcely distinguishable from the ischio-anal muscle (levator ani), It 
extends transversely from the ischial tuberosity—to which it is attached 
through the medium of the sacro-sciatic ligament, to the mesial line of the 
perineum, where its fibres, confounded with those of its homologue on the 
opposite side, appear to be inserted in the accelerator urine at its origin. 

e. Action of the urethral muscles.—1. Wilson's muscle, when it contracts, 
compresses between its two layers the membranous portion of the urethra. 
It is a veritable sphincter, and opposes the escape of the urine; when the 
semen is thrown from the vesicule seminales into the urethra, it also 
prevents that fluid entering the bladder, by permitting the accelerator to 
empty, from before to behind, the initial dilatation of that canal. 2. The 
accelerator is correctly named from the part it plays in ejecting the semen 
from the urethra, it being the chief agent in this act. 3. The ischio-urethral 
muscle pulls back the membranous portion of the urethra, with Cowper's 
glands, and, like Wilson’s muscle, acts as a compressor to these. 4. The 
transversus perinei dilates the bulbous portion of the urethra, by drawing it 
out laterally. 

4, Vussets anp Nurves.—The urethra is supplied with blood by the 
bulbo-urethral arteries and the two pairs of arteries—the dorsal of the penis. 
Voluminous veins, frequently varicose, and satellites of the arteries, carry it 
away. The lymphatics form a very rich plexus beneath the mucous 
membrane; their trunks pass to the inguinal, and some to the sublumbar 
glands. The nervous filaments are from the internal pudie and great 
sympathetic. ; 

5. APONEUROSES OF THE PERIneUM.—In the perineal region, the urethra 
is covered by two superposed fibrous layers. The superficial aponewrosis 1s 
fibro-elastic, and appears to arise from the inner surface of the thighs, 
where it is mixed with the dartos; it covers the perineum, and its fibres, 
becoming disassociated, disappear on the sides of the sphincter ani, This 
membrane is in relation, externally, with the skin, and, internally, with the 
deep aponeurosis. On the middle of its external face, it receives the 
insertion of a muscular fasciculus, which is detached from the sphincter. 

The deep aponeurosis, formed of white inelastic fibrous tissue, adheres to 


864 THE GENERATIVE APPARATUS. 


the latter by its outer face, and to the accelerator and ischio-cavernous 
muscles by its inner face. Above, it is lost around the termination of the 
rectum; below, it expands between the thighs; it is seen insinuating itself, 
to the right and left, between the ischio-cavernous and semimembranosus 
muscles, to be attached to the ischiatic tuberosity. 


4, The Glands annexed to the Urethra. 


A. Prostate (Fig. 402, 8)—This single and symmetrical gland is 
situated at the commencement of the urethra, and lies across the neck of the 
bladder. A constriction in the middle divides it into two voluminous 
lateral lobes inclining slightly forward. Its upper face corresponds to the 
rectum, through the medium of the cellular tissue at the bottom of the 
pelvic cavity. Its inferior face, moulded on the neck of the bladder, 
embraces it above and laterally, and is closely attached to it; it covers the 
terminal extremity of the deferent and ejaculatory ducts, and the neck of 
the vesicule seminales. 

StructurE.—The tissue composing this gland forms a number of 
communicating cells, which are larger in the Ass than the Horse; in these 
is collected a quantity of viscid fluid (succus prostaticus) secreted by their 
walls, and which is ejected into the urethra by the two rows of orifices 
arranged on the sides of the veru montanum. These communicating cells 
are nothing more than conglomerate glands, which are distributed in a 
stroma of connective tissue and unstriped muscular fibres. 

B. Cowrzr’s Guanps.—In Veterinary anatomy, these are frequently 
named the small prostates. They are two globular bodies, denser in texture 
than the prostate gland, but otherwise the same in organisation, and are 
situated on each side of the urethra, in the perineal region, above the ischiai 
arch; they are completely enveloped by a somewhat thick fleshy cover- 
ing, formed by the fibres of Wilson’s and the ischio-urethral muscles 
(Fig. 402, 11). . 

The fluid they secrete is thrown into the urethral canal by numerous 
orifices disposed in several rows. It has the same physical properties as 
that of the prostate, and both are poured into the urethra in abundance 
immediately before ejaculation; the expulsion of the semen is by this 
means facilitated. 


5. The Corpus Cavernosum. 


The corpus cavernosum is an erectile stalk, which forms the base of the 
penis and supports the urethra; it is situated between the thighs, prolonged 
beneath the abdomen, attached behind to the ischial arch, and terminates in 
front by a free extremity, which is received into the erectile enlargement 
named the glans penis. 

External conformation.—Flattened on both sides, this body offers for 
study two lateral faces, two borders, and two extremities. The faces are 
plane, and present no interesting features. The superivr, or dorsal border, is 
the thickest, and is rounded. The inferior is channeled throughout its 
extent by a deep furrow which lodges the urethra, The posterior eatremity 
is bifurcated, the two branches constituting the roots (corpora or crura) of the 
penis ; they are fixed to the ischial arch, one to the right, the other to the left, 
and are covered by the two ischio-cavernosus (erector penis) muscles : short, 
thick, and strong masses intersected by numerous tendinous fibres, and partly 
concealed by the semimembranosus muscles. These erector penis muscles 


THE MALE GENITAL ORGANS. 865 


arise from the ischial crest, and terminate on the membrane enveloping the 
erura of the penis, which they cover posteriorly and externally. 

The anterior extremity of the corpus cavernosum forms a blunt point, and 
is surrounded by the spongy tissue of the glans. 

Mode of attachment of the corpus cavernosum.—The chief attachment is 
constituted by the insertion of the two crura into the ischial arch. There is 
also a double suspensory ligament proceeding from the ischio-pubic sym- 
physis, where it is confounded with the superior attachments of the short 
adductor of the thigh, and passes to the dorsal border of the corpus 
cavernosum, a little in front of the point of union of its crura. 

Srrucrure.—This erectile organ is composed, externally, of a white, 
elastic, fibrous envelope, remarkable for its thickness, especially on the 
dorsum; it gives off, from its inner face, a certain number of lamellar 
trabecule which partition the interior of the cavity it forms. One of these 
septa (septum pectiniform) is directed vertically from the upper to the lower 
border, and divides the corpus cavernosum into two lateral portions (corpora 
cavernosa), which would indicate that the crura are not one mass at their 
point of union, but merely joined to each other. In the Horse, this septum 
is generally very incomplete, and rarely extends the whole length of the 
organ. 

oThe lamellar prolongations sustain other elastic and contractile bands, 
which circumscribe the cavities in which is lodged the essential portion of 
the erectile tissue. According to Legros, the latter is composed of a 
network of capillaries interposed between the arterial and venous twigs, and 
which shows abrupt or regular dilatations of variable diameter. These 
successively dilated capillaries have very thin walls, which are adherent to 
the contractile prolongations of the envelope, and are lined by a very 
delicate pavement epithelium. In the areole of the cavernous tissue, 
particularly towards the base of the organ, the arteries offer a special 
disposition ; their walls are very thick, and they soon divide intoa bouquet of 
branches which enter the areola, where they terminate either by a cul-de- 
sac, or, which is most frequent, give off small free branches convoluted in a 
spiral manner. These are the arteriw helicine described by Miiller and 
Rouget. (The walls of the cells are composed of white and yellow fibrous 
tissue, and unstriped muscular fibres. The cells themselves are in reality 
venous sinuses. Kdlliker found a minute artery to proceed from each of 
the cecal terminations of the helicine arteries, and terminate, like the other 
capillaries, in the veins. The dilated vessels have been regarded by some 
anatomists as only vascular loops. The cells, during the erection of the 
penis, are distended with blood.) 

The arteries of the corpus cavernosum and dorsales penis pass into the 
erectile structure, and supply this organ with blood. The collateral veins of 
these arteries arise near the surface. The nerves come from the internal 
pudic and great sympathetic. 


6. The Penis. 


The penis is the male organ of copulation, and results from the union of 
the corpus cavernosum and the spongy portion of the urethra. These parts 
have already been described; it now remains to consider the organ in its 
entirety. as ; 

The penis commences at the ischial arch, passes between the thighs 
and the two dartoid sacs containing the testicles, and is prolonged beneath 
the belly, where it terminates in a free extremity. 


866 THE GENERATIVE APPARATUS, 


All the portion comprised between the ischial arch and the scrotum, is 
maintained and deeply covered by the surrounding textures, and is named 
the fixed portion of the penis. The remainder of the organ—its anterior 
moiety—is, on the contrary, its free portion, as it forms a detached appendage 
sustained by a cutancous fold, the sheath (or prepuce). 

The Frxep Portion occupies the perineal region and that between the 
thighs, where it is enveloped by the arteries, veins, and nerves already 
known, as well as by a large quantity of connective tissue (and the skin). 

The Free Portion is lodged in the sheath during the inactive condition 
of the organ, but protrudes from it when in a state of erection. It is then 
seen to be covered by a smooth, unctuous tegumentary membrane with 
numerous papille, and of variable colour, though most frequently it is 
black or variegated. Its 
base presents a slight circular 
enlargement, due to the ac- 
cumulation, beneath the 
mucous membrane, of a small 
annular mass of elastic and 
coutractile tissue. Its ea- 
tremity or glans is also a cir- 
cular enlargement limited 
behind by a salient collar— 
the corona glandis—which is 
notched inferiorly, and at 
the moment of ejaculation 
assumes a considerable de- 
velopment, its shape being 
then not unlike the rose of 
LONGITUDINAL SECTION OF THE FREE EXTREMITY oF & Watering-can, This en- 

THE HORSE’S PENIS IN A RELAXED STATE. largement has for ‘its basis 


1, Evectile tissue of the corpus cavernosum; 2, Urethra; the terminal expansion of 
3, Fossa navicularis; 4, Urethral tube; 5, Erectile the urethral erectile tissue, 


: . . Pas Ditt . . . 
Heo meth Date Oe loss 7 and presents on its anterior 
face: 1, In the centre, a 
rounded prominence due to the point of the corpus cavernosum; 2, Beneath 
this, the urethral tube encircled by a fossa; 3, At the bottom of the fossa, 
and below the urethra, the orifice of a bilocular cavity—the urethral sinus, 
which widens at the bottom, and in which accumulates sebaceous matter 
that sometimes becomes so hard as to prevent the flow of the urine by 
compressing the tube; 4, Inferiorly, the subwrethral notch. 

The skin covering the extremity of the penis is rich in nerves which, 
according to Kraiise, have round dilatations which he designates as 
“terminal genital corpuscles.” 

To complete the description of the penis, there only remain to be 
described: 1, Two suspensory and retractile cords which concur, with the 
natural elasticity of the fibrous envelope of the corpus cavernosum, to retura 
the organ to its ordinary position when the phenomenon of erection has 
ceased ; 2, The tegumentary fold, or sheath, which envelops the free portion 
of the penis when in its ordinary state of repose. 

A. Suspensory anp Rerractite Corps or tax Penis.—Two in number 
these cords arise from the lower face of the sacrum, descend as flat bands in 
front of the sphincter ani, between the retractor muscle of the anus and the 
rectum, to which they give numerous short fasciculi from their posterior 


Fig, 403, 


THE MALE GENITAL ORGANS. 867 


poniens they “then unite at the mesial line, below the anal opening, thus 
orming around the terminal extremity of the rectum a real suspensory ring. 
Lying together, and intimately united, they are continued on the accelerator, 
which they follow at the raphé, and are eventually lost in its texture near 
the free extremity of the penis. 

These cords are composed of unstriped muscular fibres. 

B. Sazara (prepuce)—The sheath is a cavity formed by a fold of the 
abdominal integument, and lodges the free portion of the penis; it is 
entirely effaced at the moment of erection, when the copulatory organ is 
lengthened and enlarged. The skin at the opening of the sheath’ enters its 
cavity, and, on arriving at the free portion of the penis, forms a circular 
cul-de-sac in becoming reflected over the organ, which it envelops. 

This lining integument of the sheath is fine, and very irregularly 
plicated ; it is destitute of hair, and holds a middle place, with regard to 
organisation, between the skin and mucous membranes. It contains in, or 
beneath, its substance a considerable number of sebaceous or preputial glands 
that secrete an unctuous fatty matter (exhaling a pecular odour, and dark- 
grey in colour, the smegma preputii), which is spread over the surface of 
the membrane. 

Above, the inner integument of the sheath is applied to the fibrous tunic 
of the abdomen. Below, and on each side, the cutaneous fold constituting 
this cavity contains between its layers an expansion of yellow elastic fibrous- 
tissue, the lateral portions of which, attached to the abdominal tunic, are 
named the suspensory ligaments of the sheath. 

In the Ass, there exists, near the entrance to the sheath, and on each side, 
a small tubercle which may be looked upon as a rudimentary teat of the 
female. 

(The prepuce protects the penis, and sustains it when in a flaccid state. 
In certain Horses, a gurgling sound is produced in trotting, from the air 
entering and leaving the sheath suddenly.) 


DIFFERENTJAL CHARACTERS IN THE MALE GENITAL ORGANS OF OTHER THAN SOLIPED 
ANIMALS. 


Rouminants.—esticles—In these animals, the testicles are very voluminous, oval, 
and vertically elongated. They, with their envelopes, form a pendant mass that occupies 
the inguinal region. The scrotum is always of a pale colour. In the interior of the 
testicle, the corpus Highmorianum and the rete testis are very marked. (The proper 
tissue is yellow, and the septa formed by the prolongations of the tunica albuginea are 
not very distinctly seen.) <, Oe Genk 

Epididymis.— Vas deferens.—The head of the epididymis is wide and flat, and partly 
covers the anterior border of the testicle. The middle portion, smaller than in Solipeds, 
represents a narrow cord lying outside the posterior border of the seminal gland. The 
tail is a little free appendage, inflected inwards and upwards to become continuous with 
the vas deferens. The latter is dilated, as in the Horse, when it arrives above the bladder, 
and lies beside the duct of the opposite side. The two, thus joined, increase from before 
to behind, leave the neck of the bladder in passing above the vesicule seminales, then 
go beneath the prostate, and terminate in the urethra, on the summit of a ridge, by two 

ipti ifices. 
as oe the Bull, the vesicule seminales have not the same appearance 
ag in the Horse, and they have not so large a cavity in their interior. They are two 
elongated masses, lobulated on their surface, yellow in colour, and possessing quite a 
glandular aspect. They have sometimes been designated the Jateral prostates. ‘They 
are composed of aciniform glands, inclosed in a mass of connective tissue and unstriped 
fibres; they open into a common central canal which terminates in the vas deferens. 

Urethra —This canal is inflected like the letter 8. Its diameter regularly diminishes 
from its commencement to its termination, which is not provided with a urethral tube, 
as in Solipeds. Internally it presents: 1, Immediately beyond the neck of the bladder 


868 THE GENERATIVE APPARATUS. 


a short, but very salient veru montanum, which divides into two mucous columns, that 
gradually subside posteriorly ; 2, Towards the ischial arch, a valve whose free border, 
directed downwards, covers a cul-de-sac about 3-4ths to 1 inch deep. 

The structure of the urethra is also different. The walls of the membranous portion 
are thicker than in the Horse; they have a layer of erectile tissue, and a Wilson’s 
muscle, very thick below and laterally, and whose fibres are inserted in the middle of 
the upper surface, into an aponeurotic raphé. . 

At the ischial arch, when the canal bends downwards, the spongy tissue becomes 

more abundant to form the bulb of the 

Fig. 404. urethra ; but the prominence at this point 

is chiefly due to the accelerator urine, 

as is shown in figure 404, co, 4. This 

muscle is extremely powerful, but it 

soon ceases beneath the ischial arch. 

The transversus perinei is as strong as in 
Solipeds. 

Glands annexed to the urethra.— 
Cowper's glands are absent. The pros- 
tate gland is not voluminous, and forms, 
at the commencement of the urethra, 
a little transverse yellow mass, beneath 
which pass the vasa deferentia; it also 
lies beneath Wilson’s muscle, and is 
prolonged for some distance on the mem- 
branous portion of the urethra. 

Penis—In the Bull, the penis is long 
and thin, and carried well forward be- 
neath the belly. It is inclosed at the 
perineum in an aponeurotic sheath, 
which is covered by the ischio-tibial 
muscles. This sheath is double, its 
superficial layer being continuous with 
the dartos, and has the same physical 
characters; the deep layer is thin, white, 
and inelastic. 

In front of the pubis, the penis des- 
cribes two successive curves—the S of 
the penis—the first with its convexity 
forwards, the second backwards. It is 
at the second curve that the suspensory 
ligaments join the penis, and continue 
along its sides to its extremity. 

The free portion of the organ, very 
tapering, is covered by a fine, papil- 
lated, very sensitive, rose-coloured 
mucous membrane. 

1t is lodged in a narrow sheath that 
advances much more forward beneath 
the abdomen than in Solipeds, and hus 
at its opening a bunch of long stiff hairs. 

SECTIONS OF THE URETHRA OF THE ox at _his cutaneous sheath is moved by four 
DIRPERENE POINTE: bases muscles : two posterior or 

A, Intrapelvic portion; 1, Wilson’s muscle; 2, co o Pied ie 
Erectile tissue; 3, Urethral canal; 4, Prostate posing the penis ae the: moments a ri 
gland.—p, The middle of the penis; 1, Fibrous grection - a two anteriar on ‘i ie i 5 
cord of the corpus cavernosum; 2, Urethral mucclog ‘(Fig 405, 1) ae pre ae 
canal; 3, Its erectile tissue; 4, Envelope of choath forward ta ae rae i 
the corpus cavernosum.—o, At the crura of the The Jatter are found an, the Co post A as 
penis; 1,1, Crura of the corpus cavernosum; 54 appear to be of any use OU) BNE IO 

2, Urethral canal; 3, Its erectile tissue; The two constit ue oti f th 

4, Accelerator urine; 5, Ischio-cavernosus éopulator : MED’  DOruons 6 7 
aiasele. pulatory organ are not joined in the 
same manner as in Solipeds, the channel 

for the lodgment of the urethra being 

transformed into a complete canal by a narrow layer of the fibrous envelope of the corpus 


THE MALE GENITAL ORGANS. 869 


cavernosuin. The latter is little developed, and presents, internally, a longitudinal fibrous 
cord; it is not much dilated during erection. In this act, the penis is clongated by the 
straightening out of its curvatures, rather than by any real lengthening; when erection 
ceases, the organ is retracted into the preputial cavity by the contraction of the sus- 
pensory cords, which reform its double inflection behind the scrotum. 

In the Ram and He-goat, the disposition of these parts is somewhat similar. (In the 
former, the extremity of the urethra has the form of a narrow cyiinder curved backwards, 
its opening being a longitudinal slit. In Rumiuants, towards the extremity of the sheath 
are small teats; these, in the He-goat, are sometimes glandular, and scerete a fluid 
analogous to milk.) 


Fig. 405. 


PENIS AND MUSCLES OF THE SHEATH OF THE BULL. 


1, Protractor muscle of the sheath ; 2, Retractor of ditto; 3, Testicles in the scrotum ; 
4, The S of the penis; 5, Suspensory cords of the penis attached to the second 
curve: 6, Subcutaneous abdominal vein. 


Pic.—The testicles of this animal are round, and placed in the perineal region. The 
scrotum is narrow, and but little detached: the pouches of which it is composed 
appearing simply as two hemispherical prominences on the ‘surface of the perineum. 
There is nothing particular to be remarked in the epididymis and vas deferens ; (the 
tail of the first is very voluminous; the latter has no pelvic dilatation.) 

The vesicule seminales, with regard to disposition, are intermediate between those of 
the Horse and Ox Their walls are thick and very glandular, and their interior is 
diverticulated. (They are, proportionately, very large, and, in structure, closely re- 
semble those of Ruminants; indeed, in these animals they rather appear to be. organs for 
the secretion of a milky liquid that is mixed with the semen, than reservoirs for the 
fecundating matter, as that fluid never contains any spermatozoa.) There are two 
prostates: one disposed as in the Ox; the other placed across the neck of the bladder, 
‘as in Solipeds. The penis resembles that of Ruminants, except in the absence of the 
muscles of the sheath; it has also a particular preputial sheath, which has been studied 


58 


870; THE GENERATIVE APPARATUS. 


by Lacauchie. (When flaccid, the penis of the Pig is twisted in a spiral manner at the 
extremity. he sheath is narrow, and longer than in Ruminants. At the upper part of 
its opening is the special pouch mentioned by Chauveau, and which is formed by a fold 
of the skin It opens into the sheath, and secretes, in the Boar, an unctuous fluid, 
possessing a particularly disagrecable smell, and which is mixed with the urine. The 
odour of the secretion even taints the flesh of this creature.) ; 

Carnivora.—The testicles of the Cat are formed like, and placed in the same situation 
as, those of the Pig; those of the Dog are more oval, and are pendent. 

The Carnivora have no vesiculz seminales. The prostate gland surrounds the neck 
of the bladder ; it is of a yellow colour, concave on its upper surface, and divided iuto 
two lateral lobes on its lower face. Cowyper’s glands are absent in the Dog; they exist in 
the Cat (in which they are very small, and excrete their secretion by separate efferent 
canals). The urethra (in its pelvic portion) is very long; towards the ischial arch it 
shows an enlargement or bulb, though this is less, proportionately, than in the Ox; the 
accelerator muscle is continued -for a longer distance around it. (The spongy portion is 
thinner in the Cat than the Dog.) . ; 

“In the Dog, the penis is long and pointed. The posterior half is constituted by the 
corpus cavernosum, which is little developed, and has not « complete middle septum, 
The anterior moiety has for its base a bone, found in several other mammifers, which 
is intended to favour the introduction of the penis into the genital organs of the female. 

“The penien, or penial, bone is elongated, conical, and iucurvated, so as to constitute 
a furrow inferiorly, in which is lodged the urethra when it leaves the fibr us channel of 
the corpus cavernosum; its apex, anteriorly, partly forms the point of the )-enis; its base 
is intimately united to the anterior portion of the corpus cavernosum: the median 
septum, which is very dense, is fixed in this bone, as is the fibrous envelope which mixes 
with its periosteum. : 

‘The penial bone almost entirely constitutes the base of all that portion of the penis 
included within the sheath ; in addition, this part possesses two distinct erectile enlarge- 
ments—an antertor and posterior. The first is analogous to that of the glans penis of the 
Horse, and is formed by an expansion of the erectile tissue of the urethra; club--haped 
at its anterior base, it has there a point suddenly bent downwards, beneath which is 
pierced the urethral orifice ; posteriorly it is thin, and partially covers the other erectile 
mass. The latter is supplementary ; it begins at the base of the free portion of the 
penis, where the integument of the sheath is folded in a circular manner around it. 
From 1 to 13 inches long, it embraces the upper border and sides of the bone; pyramidal 
in shape, its base, which is posterior, is # to 14 inches thick ; in front, it thins away beneath 
the erectile tissue of the head. 

“Such arethe two erectile masses, whose summits overlap, so that the free portion of the 
penis, bulging in front, and still more so behind, is narrowest in the middle. Although 
contiguous, these two vascular dilatations are independent of each other; the posterior 
has, likewise, no communication with the corpus cavernosum, and possesses two parti- 
cular veins which pass backward in a lateral groove. Each is erected separately during 
copulation, when they assume a large size; the great volume of the posterior enlarge- 
ment prolongs the duration of this act, until flaccidity ensues. This peculiarity is a 
consequence of the absence of the seminal reservoirs (the vesicule seminales). 

“In the Dog, two small muscles are found which appear to be destined to elevate the 

“penis and direct it during its introduction into the sexual parts of the female, as its 
erection is always feeble. These are two fasciculi which proceed from the crura of the 
penis, and pass forward to unite in a common tendon implanted on the dorsal border of 

‘ the organ; they thus resemble the chord of an are. 

“The subpenial muscular cords exist as in the other animals. The sheath is narrow 
and long, and, as in the didactyles, has protractor muscles: the integument is thin and 
rose-coloured, like that covering the free portion of the penis. 

“In the Cat, the penis is short, and directed backwards; but in a state of erection it 
is inclined forwards for copulation. Its free portion presents some peculiarities. It is 

- conical, and its summit, near which is pierced the urethral opening, has for its basis a 
small incomplete penial bone, that encloses a layer of erectile tissue—an expansion of 
that of the urethra. This free portion is covered by an integument studded with some- 
what rigid papille directed backwards, and capable of being made erect durine 
copulation. These points, which are met with in nearly all the Cat kind, are analogous 

to he wae wes ih Bee ee see jibe cartilaginous saws, of certain other 
animals, and which appear to be related to the degree of iti 
sextial organs.” A. Tnaadd, g. sensitiveness of the female 


THE MALE GENITAL ORGANS. 871 


COMPARISON OF THE GENITAL ORGANS OF MAN WITH THOSE OF ANIMALS, 


Coverings of the testicles—The scrotum, dartos, tunica j i 
Cove Th erythryoidea, and tw 
vaginalis have the same organisation as in Solipeds, The Scat ‘2 rieh in ebansotia 
aa ala ae Alege aoe is Cue aee bya serous layer from the peritoneal cavity. 
; esticles—These are ovoid, and situated in an oblique direction d 
=e ; ee largest curvature is forwards. ‘ pai acaba Aclae 
e epididymis offers the same arrangement as already noticed, except that the vas 
deferens, in being detached from the globus minor, is bent somewhat saidenly to reach 
the abdominal cavity. There are several diverticuli annexed to the epididymis, named 
the pediculated hydatid of Morgagnt, non-pediculated hydatid aberrant vessels, and corpus 
innominatum of Giraldés. : 


Fig. 406, 


aN 
a 
I 


SECTION OF PELVIS TO THE LEFT OF THE MEDIAN LINE AT THE PUBES, AND 
THROUGH THE MIDDLE OF THE SACRUM. 

1, Section of left pubic bone; 2, Peritoneum on bladder; 3, Left crus penis; 4, 
Pelvic fascia forming anterior hgaments of bladder; 5, Part of accelerator 
urine; 6, Posterior layer of triangular ligament forming the capsule of the 
prostate; 7, Anterior layer of triangular ligament ; Between 6 and 7 are seen 
the membranous urethra, deep muscles of urethra (insertion), and Cowper’s gland 
of the left side; 8, Vas deferens; 9, Bulb of urethra; 10, Rectum; 11, Cut 
edges of accelerator urine and transversus perinei; 12, Left ureter; 13, Reflec- 
tion of deep layer of superficial fascia round transversus perinzi; 14, Left 
vesicula seminalis; 15, Cut edge of levator ani; 16, Rectum; 17, Prostate gland. 


The hydatid of Morgagnt is a little projection at the head of the epididymis, filled 
with a serous fluid which is never mixed with the semen. The non-pediculated hydatid 
is a small white mass which rises from the testicle at some distance from the globus major ; 
it has a cavity that communicates with the duct of the epididymis. The aberrant vessels 
are fine flexuous ducts given off from the globus minor, and soon terminate in a cul-de- 
sae. The corpus innominatum of Giraldes is a small mass of ramifying tubes included 
in the connective tissue uniting the globus major to the testicle. All these appendages 
of the testicle or epididymis, are the remains of the Wolffian body. : 

Vas deferens.— This is not united to its fellow by a peritoneal fold; it is slightly 
dilated on arriving at the neck of the bladder, as in the Horse. The vesicule seminales 
are elongated, and lobulated on their surface, as in Ruminants. 

Urethra.—This canal bas a fixed and a free portion: the first is slightly inclined 
downwards and forwards; the second is suddenly inflected, and, with the preceding, 
forms the prepubic angle, which disappears with erection. Its diameter increases a little 
at the bulb, and again at the meatus, to form the fossa navicularis. Its erectile envelope 
forms a considerable enlargement at its commencement—the bulb, and this is covered, 
as in the Ox, by the accelerator urine; it also composes another, the glans, that 


872 THE GENERATIVE APPARATUS. 


constitutes the head of the penis. On its inner surface are some valvular folds, some 
depressions, the lacunx of Morgagni, the veru montanum, and towards the summit of this 
a small pouch—the male uterus (sinus pocularis), which, on a very reduced scale, repre- 
sents the third vesicula of Solipeds. ‘The muscles of the urethra are the ischio-cavernosum, 
accelerator urine, Wilson’s muscle, and the transversus perinei—superficial and deep. On 
emerging from the pelvic cavity, the urethra traverses an aponeurotic membrane named 
the ligament of Carcassonne. : ‘ od 2 2h cae 

Corpus cavernosum.—This offers nothing particular in its disposition. 

Penis.—This organ is free, and is suspended in front of the pubis. It is enveloped 
by a fibrous covering —the superficial fascia, and a cutaneous cylinder—the sheath. Itis 
attached by two supensory ligaments: the superficial is elastic, and arises from the linea 
alba; the deep is inelastic, and is detached from the symphysis pubis and the anterior 
pillar of tie inguinal ring. (It is usual to describe only one ligament—the lgamentum 
suspensorium penis, separating to form two layers which give passage to the dorsal 
vessels, and nerves of the penis.) The glans is separated from the rest of the organ by a 
constriction lesignated the cervix, and around this the skin forms a (circular) fold—the 
prepuce, which covers the glans more or less cumpletely. It is attached to the middle of 
its lower face by a thin fold—the frenum preputti. The inner surface ot the prepuce 
has a large number of sebaceous glands. 


CHAPTER II. 


GENITAL ORGANS OF THE FEMALE, 


Tuxse organs resemble those of the male in their general disposition. Thus 
we find in the female: 1, Two secretory organs, the ovaries, analogous to 
the testicles, and charged with the elaboration of the germ; 2, The uterine 
(Fallopian) tube, disposed, like the epididymis and vas deferens, as a flexuous 
canal, through which the ovum passes on leaving the ovary; 3, The uterus, 
a single reservoir formed of two lateral moieties which may be compared to 
the vesicule seminales, as it is there that the germ remains until it is fully 
developed; 4, The vagina, a membranous canal analogous to the urethra, 
and giving passage to the foetus after it has been formed in the uterus: this 
canal, which receives the penis during copulation, also shows, at its exterior 
opening, the vulva, an erectile apparatus, and the clitoris, which is nothing 
more than a rudimentary corpus cavernosum of the male. The female has 
also certain glands, which, in many species, exist in a rudimentary form in 
the male: for instance, the mamme, organs for the secretion of milk, the 
first nourishment of the young animal. 

(The glands of Duverney, in the female vagina, seem to be analogous to 
Cowper’s glands in the male, as they are present in the females of all 
animals where the latter exist in the male, and their secretion appears to be 
of the same character.) 

It may be remarked, after this enunciation, that the male and female 
genital apparatus are constructed on the same type: a circumstance which is 
most clearly demonstrated at an early period of intra-uterine life, when it is 
impossible to distinguish the sexes. 


1. The Ovaries. (Fig. 411, 1.) 


Situation—Form— Relations.—The ovaries (testes muliebres), the essential 
organs of generation in the female, are two ovoid bodies, smaller than the 
testicles, though of the same shape, situated in the abdominal cavity,’ and 

‘ The ovaries sometimes leave this situation. Thus M. Dupont, of Plazac, has 


observed them, in four swine, occupying little cavities, analogous to those of the male 
scrotum, in the perineal region.—‘ Journal des Vétérinaires du Midi,’ December, 1869, 


THE FEMALE GENITAL ORGANS. 873 


suspended from the sublumbar region, where they correspond with the 
intestinal convolutions, a little behind the kidneys. Smooth on the surface, 
these organs present, in the middle of their upper face, a deep, and more or 
less oblique fissure, resembling the hilus of the kidney; this gives attach- 
ment to the pavilion of the tube. 

Means of attachment.—The ovary floats at the anterior border of the 
broad ligament ; it is also sustained by the vessels which enter it, and by a 
small cord of unstriped muscular fibres, the ligament of the ovary, which 
attaches it to the uterus. 

Srrvucture.—The organisation of the ovaries comprises a serous mem- 
Aabes a tunica albuginea, proper tissue, and the Graafian vesicles imbedded 
therein. 

Serous membrane.—This is a continuation of the broad ligaments; it 
covers the whole organ (except at the hilus), adhering closely to the tunica 
albuginea. 

Tunica albuginea. —This is similar to that enveloping the testicle, being 
a very resisting fibrous case which sends prolongations into the substance of 
the ovary. 

Proper tissue.—The proper tissue, or stroma, of the ovary is more con- 
sistent than that of the testicle ; it is hard, grates on being cut into, and 
is greyish-red in colour. It is divisible into two layers, distinguishable by 
their aspect and structure. 

1. The medullary layer, that nearest the hilus, is slightly red and 
spongy; it is formed by an interlacing of the connective fibres, unstriped 
muscular fibres, and a large number of vessels that radiate from the centre 
towards the periphery. 

2. The cortical layer has the elements of connective tissue for ifs base ; 
it is but little vascular, and contains in its substance the Graafian vesicles 
or follicles (ovisacs), and is consequently often named the ovigenous layer. 
These ovisacs are in various stages of development; the smallest are 
situated beneath the tunica albuginea, and gradually increase as they lie 
deeper. When fully deyeloped, they are filled with a transparent, citron- 
coloured fluid ; the ovigenous layer can then no longer contain them, and 
they protrude more or less from the surface of the ovary. 

A Graafian vesicle, in its perfect state, is composed of an envelope and 
its contents. The envelope comprises: a fibrous membrane (tunica fibrosa), 
which is confounded with the stroma of the ovary, and in it we may re- 
cognise two layers, the internal of which is rich in vessels; and an epithelium, 
or membrana granulosa, consisting of round or polygonal granular cells. 
At the bottom of the ovisac, this epithelium forms a small mass—the cumulus 
proligerus (or germinal eminence), in the centre of which is the ovulum or 
ege of the mammal. The contents (liquor folliculi) are a clear yellow fluid, 
which becomes red on admixture with blood when the vesicle ruptures. 

The ovulum or ovum is a cell about 1-100th of an inch in diameter, 
inclosed in the discus proligerus or cumulus proligerus. The ovulum is 
invested by an amorphous, thick cell-membrane—the zona pellucida (mem- 
brana vitellina); its granular contents are named the vitellus or yelk ; and 
its (vesicular nucleated) nucleus, designated the germinal vesicle, and lying 
at a certain point on the zona pellucida, has in its centre a white patch—the 
germinal spot. 8 hes i 

Vessels and nerves.—The thick, flexuous, arterial divisions are given off 
by the utero-ovarian artery; they ramify in the spaces formed by the tunica 
albuginea, before teaching the proper tissue by entering the hilus. The 


874 THE GENERATIVE APPARATUS. 


veins are of large calibre, and form a very rich network around the gland 

—the bulb of the ovary; they terminate in the vena cava, near the renal veins. 

The lymphatics pass to the sublumbar glands. The nerves emanate from 
senteric plexus. 

cs eee ean ovary of Solipeds is of great size in the foetus, 

being often nearly as large as in the adult animal. It becomes wasted in 

aged animals. ; . 

Funorions.—The productive organs of the germ or ovum, the ovaries 
are the testicles of the female. They form the ovulum, and then at a cer- 
tain period set it at liberty. As the ovule are contained in the ovisacs, 
it is necessary to study: 1, The development of these ovisacs ; 2, Their 
rupture or dehisence; 8, The phenomena occuring in them after this 
rupture. : ar a 

Development of the Ovisacs.—The ovisacs already exist in the ovary of 
the fetus and the young animal, but only assume their greatest activity at 
the age of puberty. They are not all formed at birth, but are incessantly 
re-developed, this development taking place beneath the tunica albuginea, 
(At puberty, the stroma of the ovary is crowded with ovisacs so minute, 
that in the Cow it has been computed that a cubic inch would contain two 
hundred millions of them.) : 

At first the ovisac consists of a small cell, which 
presents all the constituent parts of the ovulum. As 
it becomes developed it sinks into the cortical layer, 
being pushed deeper into it by the cells that grow 
outside it; and it is also surrounded by a granular 
membrane, formed at the expense of the nuclear 
elements of the adjacent connective tissue. This 
membrane soon separates at a given point into two 
layers, to form a cavity that gradually extends and 
becomes filled with fluid: this is the cavity of the 
ovulum. As the separation is not complete, the 
ovulum, enveloped by the internal granular membrane, 
remains beside the external granular membrane, and 
while the cavity is increasing, the tissue of the ovary, 
pressed around it, is condensed, constituting the 
fibrous wall of the ovisac, which afterwards receives 
a network of vessels. 

Rupture of the Ovisacs.—Until puberty, the ovisacs 
do not exhibit any very marked phenomena; at this 
period, however, the ovary becomes vascularised, and 

a certain number of Graafian vesicles increase in 

OVARIUM OF THE RaBLIT volume. At the period of cestrum, one or more of 
asian Oe ee Seeaey according to the species, participate in the 
various stacus or Change in the ovary, become vascular and distended, 
THE ExTRusiON or and finish by rupturing and evacuating the discus 
ova. proligerus and ovulum. The latter is received into 
the Fallopian tube and conveyed towards the uterus. 

Corpus Luteu.—After the rupture of a Graafian vesicle, its cavity is 
filled by a clot of blood which gradually contracts and loses its colour: at 
the same time the fibrous membrane becomes hypertrophied, and the granular 
layer is wrinkled and transformed into cylindrical epithelium. To 
this period of progression succeeds one of regression, during which the 
cylindrical cells become infiltrated with fat and are gradually absorbed. 


Fig. 407. 


THE FEMALE GENITAL ORGANS. 875: 


The term corpus luteum is given to the cicatrix resulting from the rupture of 
the ovisac. 


The progress of the phenomena of hypertrophy and regression is much 
slower when the escape of the ovuluri has been followed by impregnation ; 


Fig. 408, Fig. 409. 


h vi) 
CONSTITUENT PARTS OF MAMMALIAN OVUM. 


Fig. 408, Entire ovum; Fig. 409, Ovum ruptured, with the contents escaping ; mv, Vitelline 
membrane; j, Yolk; vg, Germinal vesicle; tg, Germinal spot. 


so that we have false corpora lutea (those which are independent of preg- 
nancy), and true corpora lutea, those of gestation, and which do not disappear 
until several weeks after parturition. (The true corpora lutea are recog- 


SUCCESSIVE STAGES IN THE FORMATION OF THE CORPUS LUTEUM IN THE GRAAFIAN 
FOLLICLE OF A SOW; VERTICAL SECTION. 


u, The follicle immediately after the expulsion of the ovum, its cavity being filled 
with blood, and no ostensible increase of its epithelial lining having yet taken 
place; at b, a thickening of this lining has become apparent; at c, it begins to 
present folds which are deepened at d, and the clot of blood is being absorbed and 
decolorized ; a continuance of the same process, as shown at ¢, f, g, 2, forms the 
corpus luteum, with its stellate cicatrix. 


nisable, after parturition, as small white or dark-coloured masses, the corpora 
albicans vel mgrum. The yellow colour to which they owe their name is 
due to the infiltration of the cylindrical cells with fat.) 

Such are, very briefly, the functions of the ovary. 


876 THE GENERATIVE APPARATUS. 


(Beneath the hilus of the ovary, and between the layers of the broad 
ligament and the round ligament, is found asmall body, usually described 
as the parovarium, consisting of a number of fine tubes with blind extremities. 
It is considered as the remains of the Wolffian body: a foetal structure that 
forms the epididymis in the male, and has been named the organ of Rosen- 
muller in the female. Chauveau does not mention its existence in the 
domesticated animals, though Leyh dves.) 


2. The Oviducts, or Fallopian or Uterine Tubes. (Fig. 411, 2.) 


The uterine tube is a little flesuous canal, lodged in the broad ligament, 
near its anterior border. It commences at the ovary by a free, expanding 
oxtremity—the pavilion of the tube (or ostium abdominale), and terminates 
in the cul-de-sac of tue uterine horn by opening into it (the ostium uterinum). 
Tts canal at the middle is so narrow as scarcely to admit more than a very 
thin straw, and its calibre is still less towards the uterine extremity ; near 
the ovary, however, it is wide enough for the passage of a thick goose-quill. 

The orifice of the uterine extremity opens in a small and very hard 
tubercle. The ovarian extremity, in all mammalia, offers a very remarkable 
arrangement. It opens into the peritoneal cavity, near the fissure of the 
ovary, and in the centre of the expansion named the pavilion of the tube, 
which is also designated the fimbriated eatremity (or morsus diaboli), 
This pavilion is attached to the external side of the ovary, and has a very 
irregular outline: notched as it is into several lancet-shaped, unequal pro- 
longations (fimbrie), which float freely in the abdomen. Here are, then, 
two important anatomical facts: the discontinuity between a gland and 
its excretory canal, and the communication of a serous cavity with the 
exterior. 

Srructure.—tThe oviduct is formed of a serous, a contractile, and a 
mucous tunic. The serous (external) is furnished by the broad ligament, 
and is derived from the peritoneum. The contractile (middle) is constituted 
by unstriped muscular fibres, which extend into the pavilion. (They are 
arranged as circular—internal, and longitudinal—external fibres, and are con- 
tinuous with those of the uterus; they are mixed with immature nucleated 
areolar tissue.) The mucous membrane is in longitudinal folds in the tube, 
but in the pavilion these folds are radiating; it is covered by a ciliated 
cylindrical epithelium (the vibrations of the cilia being towards the uterus.) 
(It has very few glands and no villi.) At the margin, or fimbrie, of the 
pavilion it suddenly ceases, and is continued by the peritoneum (a serous 
cyst is frequently found in this situation; at the other extremity the 
mucous membrane is continuous with that of the uterus). 

Foncrions.—The excretcry duct of the ovary, the uterine tube, seizes 
the ovulum expelled from the ovisac, and carries it to the uterus. It is 
therefore necessary that, at the moment of rupture of the ovisac, the fimbrie 
should be applied to the ovary, in order to receive the germ and bring 
it to the abdominal orifice of the tube. The application of the pavilion to 
the ovary is brought about either by the contraction of the muscular fibres 
it contains, or through the distention of the bulb of the ovary. Some- 
times this mechanism is insufficient, and the ovulum falls into the abdominal 
cavity, becomes fixed there, and is developed if it has been previously fecun- 
dated; this occurrence constitutes the most remarkable variety of extra- 
uterine gestation. 

The oviduct also conveys the seminal fluid of the male to the ovulum. 


THE FEMALE GENITAL ORGANS. 877 


3. The Uterus. (Figs. 411, 412.) ji 


The uterus is a membranous sac to which the ovulum is-carried, and in 
which it is developed. ‘ 

Situation.—It is situated in the abdominal cavity, in the sublumbar 
aay at the entrance to the pelvic cavity, where its posterior extremity ig 
placed. 

Form and relations—In its posterior moiety, the uterus is a single 
eylindrical reservoir, slightly depressed above and below; this is the body 
of the uterus. Its anterior moiety is bifid, and gives rise to two cornua. 
which curve upwards. , 

The body is related, by its upper face, to the rectum, which lies on it 
after passing between the two cornua; it receives, on the sides of this face, 
the attachment of the broad ligaments; its lateral and anterior faces are 
related to the intestinal convolutions. (Inferiorly, it is in relation with 
the bladder.) Its anterior extremity (or fundus) is continuous, without 
interruption, with each of the cornua; the posterior is separated from the 
vagina by a constriction of the neck (cervix) of the uterus. 

The cornua, mingled with the different portions of intestine which 
occupy the same region, offer: a free and convex inferior curvature; a 
superior curvature, to which the suspensory ligaments are attached; a 
posterior extremity, or base, fixed to the body of the organ; and an anterior 
extremily or summit—a rounded blind pouch looking downwards, and showing 
the entrance of the oviduct. 

Means of attachment.—Floating in the abdominal cavity, like the in- 
testines, the uterus is also, like them, attached by lamellar bands which 
suspend it to the sublumbar region, and which for this reason have been 
named the suspensory or broad ligaments of the uterus. 

These bands are two in number, are irregularly triangular in shape, and 
are more developed before than behind. Close to each other posteriorly, 
and separating in front like the branches of the letter V, they leave the 
sublumbar surface and descend towards the uterus, to be attached by their 
inferior border to the sides of the upper face of the body and the small 
curvature of the cornua. Their anterior body is free; they sustain the 
oviducts and ovaries, the former being placed between the two serous layers 
of the ligament, and the latter, placed within this ligament, receives a band 
detached from the principal layer, forming with it, beneath the ovary, a 
kind of small cupola. 

There is also another little narrow long band outside the broad ligament, 
and which can be traced as far as the upper inguinal ring. Anteriorly, it 
has a small enlarged appendix ; between the two layers forming this fold is 
found a thin muscle, altogether like the male cremaster before the descent 
of the testicle into the scrotum. This may be looked upon as the analogue 
of the round ligament of Woman. 

The uterus is also fixed in its situation by its continuity with the 
vagina. 

Interior.—The inner surface of this organ offers mucous folds, which 
exist even in the foetus; they are arranged in a longitudinal series, and are 
not effacable by distension; though they disappear during gestation, con- 
sequent on the enlargement that takes place in the uterine cavity. 

This cavity has three compartments: the cavity of the body, and those 
of the cornua. The latter are pierced, at their extremity, by the uterine 
orifice of the Fallopian tube; while the former communicates with the 


878 THE GENERATIVE APPARATUS. 


Fig. 411. 


wy hy 
Ww A 
ly \ \ 


GENERATIVE ORGANS OF THE MARE, ISOLATED AND PARTLY OPENED. 

1, 1, Ovaries; 2, 2, Fallopian tubes; 3, Pavilion of the tube, external face; 4, Ibid., 
inner face, showing the opening in the middle; 5, Ligament of the ovary; 6, Intact 
horn of the uterus; 7, A horn thrown open; 8, Body of the uterus, upper face; 
9, Broad ligament; 10, Cervix, with its mucous folds;' 11, Cul-de-sac of the 
vagina; 12, Interior of the vagina, with its folds of mucous membrane; 13, 
Urinary meatus, and its valve, 14; 15, Mucous fold, a vestige of the hymen; 16, 


Interior of the vulva; 17, Clitoris; 18, 18, Labia of the vulva; 19, Inferior 
commissure of the vulva. 


THE FEMALE GENITAL ORGANS. 879 


vagina by a narrow canal that passes through the posterior constriction of 
the uterus (cervix), and which is, in Human anatomy, named the cavity (or 
canal) of the cervix (os uteri, os eaternum, os tric). In all the domesticated 
animals, except the Rabbit, the uterine canal is prolonged to the bottom of 
the vagina, in something the same fashion as a tap is into the interior of a 
barrel ; and in this way it always forms a very marked projection in the vaginal 
cavity. Around this projection, the utero-vaginal mucous membrane is 
raised in transverse folds disposed in a circular manner, which give it the 
appearance of a radiated flower; in Veterinary anatomy, this projection of 
the cervix is consequently named the “ expanded flower ”*—_fleur épanouie ; it 
is the tench’s nose of the Human being. 

Strvcture.—The walls of the uterus are composed of three membranes : 
an external, serous; a middle, muscular; and an internal, mucous; with 
vessels and nerves. 

The serous tunic envelops all the organ; it is an expansion of the 
broad ligaments, which are prolonged backwards on the posterior extremity 
of the vagina, and are afterwards doubled in a circular fashion around that 
canal, to pass over either the rectum, the bladder, or the lateral walls of the 
pelvis. Between the two cornua this membrane forms a particular frenum, 
which is but slightly developed in Solipeds. 

The muscular layer comprises longitudinal (superficial), and circular 
(deep) fibres, analogous to those of the small intestine. Near the insertion 
of the broad ligaments, they give off a series of fasciculi which are pro- 
longed between the two layers of these ligaments. These are not the only 
muscular fibres met with in the ligaments, however; for Rouget has found 
others throughout their whole extent, but particularly in the vicinity of the 
ovaries! (Around the cervix uteri, the circular fibres are most dense and 
numerous. ) 

In the pregnant animal, the number of fibres composing this layer is 
much more considerable than in ordinary circumstances; and this increase 
has for its object to permit the dilatation of the uterus, without allowing 
its parietes to become too attenuated; they do become more or less thin, 
notwithstanding, according to the species. It has also been remarked that, 
during pregnancy, the muscular fibres present a manifest striation. (The 
elements of these fibres are short fusiform cells with long oval nuclei, mixed 
with a large quantity of immature nucleated areolar tissue.) 

The mucous membrane is thin, delicate, and raised into folds. It is 
covered by ciliated epithelium, which becomes cylindrical in the canal of 
the cervix, and pavemental around the os uteri. (The cilia vibrate towards 
the fundus of the organ. The membrane is closely connected with the 
muscular tunic, and is composed of immature nucleated areolar tissue 
without elastic fibres.) The uterine mucous membrane is destitute of 
papille (except at the cervix, where, according to Leyh, there are many 
highly vascular papille); but it lodges numerous simple or ramified glands, 
which are straight or slightly flexuous at their extremities. At the cervix, 
these glands enlarge at the bottom, and assume something of the appearance 
of acinous glands. 

(These mucous glands are designated simple and cylindrical. The first 
are most numerous towards the cervix; some, here and there, with their 
orifices closed, are enlarged, and form small vesicular tumours, the ovula 
Nabothi; they secrete the peculiar transparent mucus found here. The 


1 Unstriped contractile fibres are also found, in the male, along the spermatic cord, 
beneath the visceral layer of the tunica vaginalis. 


880 THE GENERATIVE APPARATUS. 


cylindrical, uterine, or utricular glands are closely clustered together, 
sometimes bifurcated, often twisted in a spiral fashion, and terminating in a 
cul-de-sac in the substance of the membrane. In structure they resemble 
other mucous glands, consisting of a membrana propria, an epithelium of 
spheroidal cells at the bottom of the tube, and of columnar cells in its duct. 
During gestation they are much enlarged, and receive the cotyledonal 
processes of the placenta. At the period of wstrum, the glandular secretion 
of the uterus is more active than at other times.) 

Vessels_—Nerves.—The blood brought to the uterus by the uterine and 
utero-ovarian arteries, is conveyed from it by veins corresponding to the 
latter. In animals which have been pregnant several times, the vessels are 
remarkable for their enormous volume and their tortuousness. (The 
arteries freely anastomose; they ramify through the muscular and mucous 
tunics, constituting coarse and fine networks which ultimately end in the 
veins. These are very large and have no valves; the plexuses they form 
are considerable.) 

The lymphatics that pass from the uterus are as remarkable for their 
number as their dimensions; they reach the sublumbar region. 

The nerves supplying the organ come from the small mesenteric and 
pelvic plexuses. (In the uterus there are several important nervous gan- 
glia; and during gestation it has been ascertained that the nerves, like the 
vessels, enlarge, and after parturition retura to their former size.) 

DeveLopment.—Narrow in the foetus, and in the adult which has not been 
impregnated, the uterus increases in size in animals which have had young 
several times. 

Functions.—The uterus is the sac in which the embryo is developed. 
The ovulum grafts itself upon the mucous membrane of the organ by its 
placental apparatus, in order to draw indirectly, from the maternal blood, 
the materials for its development. This function of the uterus gives rise 
to most interesting anatomical and physiological considerations, which will 
be referred to when giving the history of the ovum. 


4, The Vagina. (Figs. 411, 412.) 


The vagina is a membranous canal with thin walls; it succeeds the 
uterus, and terminates posteriorly by an external opening—the vulva. 

Situation and Relations—Situated in the pelvic cavity, which it passes 
horizontally across, the vagina is in relation with the rectum above, below 
with the bladder, and laterally with the sides of the pelvis and ureters. 
Loose connective and adipose tissue surround it posteriorly. 

Internal conformation.—The inner surface of the vagina is always lubri- 
cated by an abundance of mucus, and is ridged by longitudinal folds (co- 
lumne rugose). In front, at the bottom of the canal, is observed the 
projection formed by the cervix uteri ; posteriorly, this surface is continuous 
with that of the vulva. 

Srrucrure.—The vagina is formed of two tunics; an inner, mucous,.and 
an external, muscular. The mucous membrane (pale-red in colour) is con- 
tinuous with that lining the vulva and the uterus (and bladder); it is 
provided with papille, and is lined by stratified pavement (squamous) 
epithelium. (It consists of connective and elastic tissue, to which its 
extensibility and firmness are due.) 

The muscular coat is rose-coloured, and traversed by a large number of 
vessels ; it is surrounded, for the greater part of its extent, by an abundance 


THE FEMALE GENITAL ORGANS. 881 


of connective tissue which joins it to the organs contained in the pelvic 
cavity; in front, however, it is enveloped by the peritoneum which sur- 
rounds the vagina before passing to the uterus. (This connective tissue is 


10, Sphincter 


nt; 5, Rudi- 
ding the Rectum; 15, Kidney ; 


k; 4, Broad ligame 
Posteriorr ditto ; 


9, 


; 14, Circular fold of peritoneum surroun 


2. 


Anterior constrictor of the vulva; 


Fig. 412. 


with the pavilion of the tube hooked bac 
gina; 8, 


GENERATIVE ORGANS OF THE MARE tn situ. 
Rectum 


Cornua; 3, Ovary, 
6, Cervix uteri; 7, Va 
3, 


Bladder; 12, Ureter; 1 


16, Bulb of the vagina. 


9 
ee 


mentary round ligament ; 


1, Body of the uterus; 2 
of the anus; 11, 


gometimes designated the third or fibrous tunic of the vagina. The mus- 

cular fibres are unstriped, and arranged in circular and longitudinal series ; 

towards the posterior portion of the canal they are redder than in front.) 
Vessels and nerves.—The vagina is supplied with blood by the énternal 


882 THE APPARATUS OF GENERATION. 


pudic artery; this fluid is carried from it by numerous veins, which are 
disposed in a plexus around the canal, and enter the satellite of the 
artery. The nerves come from the pelvic plexus. (The lymphatics accom- 
pany the veins, and pass to the pelvic glands.) 

Funcrion.—The vagina receives the male organ during copulation, and 
through it the foetus passes during parturition. 


5. The Vulva. (Fig. 411.) 


The external orifice of the vagina, the vulva is situated in the perineal 
region, immediately below the anus. We will consider in succession its 
external opening, its cavity, and its structure. 

Exrernat Openinc.—This is a vertical elongated slit, presenting two 
lips and two commissures. The lips (labia vulve) are covered externally by a 
fine smooth, unctuous, and (almost) hairless skin, rich in colouring pigment, 
and lined internally by mucous membrane; on their free margin, the limits 
of these two membranes are well marked. The superior commissure is very 
acute, and almost meets the anus, from which it is nevertheless separated by 
a narrow space—the perineum. The inferior commissure is obtuse and 
rounded ; it lodges the clitoris. 

Cavity oF THE VuLva.—By all Veterinary authorities, this cavity is 
described as belonging to the vagina, to which it forms the entrance; but 
considering the analogies that exist between the genital parts of Woman and 
those of animals, this cavity must be distinguished from that of the vagina. 
It offers for study the hymen, which separates the two cavities, the meatus 
urinarius and its valve, and the clitoris. 

Tur Crrroris.—Exactly similar to the corpus cavernosum of the male, 
which it represents in miniature, and 2 to 3 inches in length, the clitoris 
commences by two crura fixed to the ischial arch, and covered by a 
rudimentary ischio-cavernosum muscle. After being attached to the 
symphysis by means of a suspensory ligament analogous to that of the 
male, it passes backwards and protrudes into the vulvular cavity, towards 
the inferior commissure. Its free extremity, lodged in that cavity, is 
enveloped by a mucous cap—the prepuce of the clitoris (preeputium clitoridis), 
which is folded in various directions, and excavated about the centre of the 
tubercle by a small follicular cavity that represents the extremity of the 
male penis. The organisation of the clitoris resembles in every particular 
that of the corpus cavernosum of the penis: a fibrous framework, erectile 
tissue, and cavernous vessels. It is the contact of the penis with this 
organ during copulation that chiefly occasions the venereal excitation. 

Tue Mzatus Uninarius anp its Vatve.—The urethral canal in the 
female is very short. It passes immediately beneath the anterior sphincter 
muscle of the vulva, and after a brief course in the texture of the floor of 
the vagina, it opens into the vulvular cavity by an orifice covered by a large 
mucous valve: this is the meatus urinarius and its valve. The urinary 
opening, placed at the bottom of the cavity, at from 34 to 5 inches from the 
external opening, is wider than the male urethra, and will admit sounds of 
somewhat large calibre, for the catheterism of the bladder. The valve has 
its free border inclining backwards, to direct the flow of urine towards 
the exterior, and prevent its reflux into the vagina. 

_ (The female urethra is composed of two tunics: a mucous, continuous 
with that of the bladder and vagina; and a muscular coat, also a con- 
tinuation of that belonging to these organs, and chiefly made up of circular 


THE FEMALE GENITAL ORGANS. 883 


fibres ; some flat fasciculi attach it to the periosteum of the ischia. The 
urethra is not surrounded by a spongy body as in the male.) . 

HE Hymey.—This membrane, when it cxists, distinctly separates the 
vulvular from the vaginal cavity. It is rarely present, however ; though 
we have observed it several times in the adult Mare. It forms a circular 
partition, fixed by its margin to the vulvo-vaginal walls, as well as to the 
valve of the meatus urinarius, and is perforated by one or more openings 
which establish 2 communication between the vulva and vagina. On many 
occasions we have found, in old brood-mares, pediculated appendages, the 
remains of this septum. 

StRvcTuRE or THE Vuitva.—The vulva offers for study in its structure: 
1, The mucous membrane lining its interior; 2, An erectile body lying on 
that membrane, and named the vaginal bulb ; 3, Two constrictor muscles— 
anterior and posterior ; 4, Two muscular ligaments ; 5, The external skin. 

_ 1. Mucous membrane.—Continuous with that of the vagina and bladder, 
this membrane has a rosy colour, which may become a bright-red at the 
period of heat. It often shows, near the free border of the labia, black 
pigment patches, which give it a speckled appearance. It has in its 
substance a greater quantity of mucous follicles and sebaceous glands. 
The latter exist near the free border, particularly about the clitoris, and es- 
pecially in the space between that erectile body and the inferior commissure 
of the vulva, where they meet in several small sinuses. (These glands 
secrete an unctuous matter possessing a special odour; they are most active 
during cestrum. 

2. Vaginal bulb—This is an organ entirely formed of erectile tissue 
with wide areole; it is divided into two branches (bulbi vestibuli), which 
arise from the vicinity of the crura of the clitoris and pass on the sides 
of the vulva, where they terminate in a round lobe. Covered by the 
posterior constrictor of the vulva, the vaginal bulb communicates, inferiorly, 
with the veins of the corpus cavernosum. The influx of blood into the 
cells of its tissue contracts the vulvular cavity, and concurs to render the 
coaptation of the copulatory organs more perfect during coition. 

3. Muscles of the vulva.—Imperfectly described and determined in books 
on Veterinary Anatomy, these belong to the category of voluntary muscles. 
We recognise two, which will be described as the posterior and anterior 
constrictors. : 

Posterior Constricror oF THE Vutva.—Analogous to the constrictor 
vagine of Woman, this muscle, included in the labia of the vulva, forms a 
veritable sphincter. Above, its fibres are mixed with those of the sphincter 
ani, and are attached to the sacrum through the medium of the suspensory 
ligaments. Inferiorly, the most anterior are fixed to the base of the clitoris ; 
the middle are prolonged to between the thighs, and are inserted into the 
inner surface of the skin. . ; 

Inwardly, it is in relation with the. vaginal bulb and the mucous 
membrane of the vulva. Its external face is separated from the skin of the 
labia by a very vascular cellulo-fibrous tissue capable of contraction, and 
in the midst of which are always found isolated red fasciculi—dependencies 

incipal muscle. 
i he Hae in contracting during copulation, constricts the aperture of 
the vagina and compresses the penis; and as, in consequence of its attach- 
ment to the clitoris, it cannot act without raising that erectile body, it 
applies this to the male organ and causes a greater degree of excitement. 
With animals in heat, the movements of the clitoris are frequently observed 


884 THE APPARATUS OF GENERATION. , 


to propel that organ outwards, especially after micturation ; in this case, the 
fibres of the constrictor attached to the clitoris erect it by its base, while 
those which are fixed into the skin between the thighs depress the inferior 
commissure of the vulva. This double action necessarily exposes the 
erectile tubercle lodged in that commissure. 

Anterior Constrictor or THs Vutva.—Analogous to Wilson’s muscle 
in the male, this constrictor is formed of arciform fibres which envelop, 
below and laterally, the vaginal walls at the entrance of the canal; its 
extremities are continued, by means of aponeurotic fascia, to the sides 
of the rectum, where they are lost. By its posterior border, this muscle 
is mixed with the preceding. 

4, Muscular ligaments of the vulva.—Traces of the suspensory cords of 
the male penis, these ligaments are disposed in the same manner at their 
origin. After becoming united beneath the rectum, they descend in several 
fasciculi into the labia of the vulva, and disappear among the fibres of the 
posterior constrictor. 

5. External skin.—This is fine and black (or light-coloured), destitute of 
hair, smooth and unctuous, and adkeres closely to the subjacent tissues. 


6. The Mamme. 


The mammee are glandular organs, which secrete the fluid that should 
nourish the young animal during the early months of its life. They are 
rudimentary in youth, and become developed with the advent of puberty, 
assuming their greatest development towards the end of gestation; they are 
most active after parturition, and cease their function, as well as diminish 
in volume, when the period of lactation has terminated. 

Situation —These glands are two in number, placed beside each other in 
the inguinal region, where they occupy the situation of the scrotum in the 
male. 

Form.—They are two hemispherical masses, separated from each other 
by a shallow furrow, and showing in their centre a prolongation called the 
teat, nipple (dug), or mammilla, which is pierced at its free extremity by several 
orifices for the escape of the milk; it is by this prolongation that the young 
animal effects: suction. 

The two glands are fixed in their position by the skin which covers 
them, and which is thin, black, covered with a fine down, and altogether 
destitute of hair in the vicinity of, or on, the teat, where the cutaneous 
surface is smooth, greasy, and supple. They are also attached to the 
tunica abdominalis by several wide, but short, elastic bands, which resemble 
the ligaments of the sheath in the male. 

Srructure.—Structurally, the mammary glands offer for study: 1, A 
yellow (elastic) fibrous envelope; 2, Glandular tissue; 3, The galactoferous 
reservoirs or sinuses ; 4, The excretory canals or mammary ducts. 

The elastic envelope, placed in the middle, beside its fellow of the 
opposite side, is mixed with the suspensory bands that descend from the 
abdominal tunic, and sends into the substance of the gland a number of 
septa, which are interposed between the principal lobules. 

The glandular tissue is 2 compound of gland vesicles or acini, clustered in 
groups around the lactiferous ducts. (The gland vesicles are made up of 
an amorphous membrane, membrana propria, lined with spheroidal nucleated 
cells. They are about 1-200th of an inch in diameter.) The lactiferous 
ducts commence by blind extremities, and run into each other to constitute 


THE FEMALE GENITAL ORGANS. 885 


a certain number of principal canals: these open into the galactoferous sinuses 
(each a sacculus vel sinus lactiferus). The glandular culs-de-sac are lined 


with o polyhedral epithelium, which becomes spherical and infiltrated with 
fat during lactation. 


Fig. 413, 


GLAND-VESICLES, WITH THEIR EXCRETORY ULTIMATE FOLLICLES, OR GLAND VESICLES, 
DUCTS TERMINATING IN A DUCTUS LAC- WITH THEIR EPITHELIUM OR SECRETING 
TIFEROUS: FROM A MERCURIAL INJECTION ; CELLS, a, @, AND NUCLEI, 8, b. 
MAGNIFIED FOUR TIMES. 


Placed at the base of the teat, the galactoferous sinuses or reservoirs are 
generally two in number, but sometimes there are three, and even four; 
they nearly always communicate with each other, and are continued into the 
mammilla by an equal number of independent excretory canals—the definitive 
ducts, whose orifices are very small, and are seen beside each other at the free 
extremity of the teat. A fine mucous membrane lines the inner face of this 
excretory apparatus; it is doubled in the teat by a thick layer of tissue, 
which again is covered by the skin that adheres closely to it. (Between 
the external and internal tunic of the teats, are found numerous fasciculi 
of unstriped muscular fibres, arranged in a circular and longitudinal manner 
around these ducts.) 

Connective tissue, vessels and nerves, complete this organisation. (The 
arteries are from the external pudic trunk; the veins are very numerous, and 
pass to the trunk of the same name; 
the nerves are derived from the first 
lumbar pair.) 

Fcyerions.—The mamme secrete 
the milk; they undergo remarkable 
modifications at puberty and at the 
end of each gestation—modifications 
which are related not only to their 
volume and secretion, but also to 
their minute structure. After ges- 
tation, the gland-vesicles shrink: 
become, as it were, atrophied, and 
have only a polygonal epithelium. 
At the termination of gestation, they 
are enlarged, new vesicles are de- 
veloped, and the epithelium changes 
its character: filling the gland cavi- 
ties, assuming a spherical shape, and 
becoming charged with fat granula- MICROSCOPIC APPEARANCE OF MILK, WITH AN 
tions. The period of lactation being inrerMrxruRE OF COLOSTRIC CORPUSULES 
completed, the mamma take on their AT 4, a, AND ELSEWHERE. 
former character. (In Mares which 
have not been bred from, the mamme# are hard and small, the teats but 
slightly prominent, and the glandular tissue scanty. In old brood-mares, 

59 


886 THE APPARATUS OF GENERATION. 


on the contrary, they are flaccid and pendant, and the teats somewhat 
lengthened. The milk secreted by the mammary glands is a white fluid, 
possessing a sweet taste, and composed of an albuminous water containing 
caseine in solution, milk sugar, salts, and fatty matter in globules—the 
butter, Usually a small quantity is secreted some days before parturition ; 
that which is yielded for a short time after that period is named colostrum ; 
it is rich in white corpuscles and has purgative properties. The colostrum 
is of a rich yellow colour, less fluid than the milk of a later period, of 
a higher specific gravity, slightly acid, and containing large oil-globules, a 
few irregular flakes, probably epithelium scales, a little granular curd-like 
matter, and a small number of granular corpuscles.) 


DIFFERENTIAL CHARACTERS IN THE FEMALE GENITAL ORGANS OF OTHER THAN SOLIPED 
ANIMALS. 


Certain organs offer some differences worthy of notice, while others are formed as in 
Solipeds. 

Rees Oba temaln the Cov, the ovaries are relatively much smaller than in 
the Mare, but their form and structure are identical. (The Graafian vesicles are visible 
through the tunica albuginea.) 

Uterus.—The uterus of the Cow, compared with that of the Mare, offers but few 
differences with regard to its general disposition in the pelvic and abdominal cavities, 
except that it is not so advanced in the latter. Supposing the uterus ta be perfectly 
horizontal, a transverse line drawn through the plane of the abdomen, before the externil 
angle of the ilium, is exceeded by the extremity of the cornua about 14 to 2 inches; so 
that if the animal were on its back, the uterus would be only prolonged to the fourth or 
fitth lumbar vertebra. 

With regard to form, the uterus of the Cow presents a very remarkable disposition, 
which it is necessary to note: the concave curvature of the cornus looks downwards, 
while in the Mare it looks upwards; though in both the sublumbar ligaments are 
attached to this concavity. Therefore it is that in the Cow, if we consider the uterus as 
freely suspended in the abdomen, the extremity of the cornua is twisted outwards and 
upwards, while the base, although drawn in the same direction by these ligaments, 
maintains its direction, because it is in a manner fixed by the body of the uterus. The 
latter receives, like the cornua, the insertion of the broad ligaments on its lower plane, 
so that it overlaps them, while the uterus of the Mare projects below them. Otherwise, 
these ligaments are very ample. especially at their anterior border; they are wide apart in 
front, towards their lumbar attachment, which is prolonged even on the parietes of the 
flink. The ligaments may be altogether compared to a triangular cravat, one angle of 
which is attached to the bottom of the pelvic cavity, and the other two to the tuberosities 
of the ilium. On this cravat lies the body and part of the cornua of the uterus. 

The uterine cornua are thin and tapering at their anterior extremity. The budy is 
short aid narrow. 

The interior of the uterus of the Cow is less ample than that of the Mare. Its 
surfuce is studded with rounded tubercles, known as cotyledons, which will be studied 
hereafter. It is only necessary to say here that they are numerous in the cornua, but 
small and few in the body of the organ. 

The cervix uteri, about from 2% to 81 inches long, is narrow and irregular. The 
“expanded flower,” more finely plicated than in the Mare, is almost cartilaginous, 
Three other plicated rings, each smaller than the other, are échelonned in the cavity of 
the cervix, from the external orifice to the body (corresponding to the plice palmatz or 
arbor vitz uterina of Woman), 

In structure, the muscular layer is generally thicker than in Solipeds. 

In the Sheep and Goat, the arrangement is the same as in the Cow, except tl.at the 
cotyledons are hollowed like a cup in their centre, and deserve their name. (The cornua 
are longer and more pendent than in the Cow.) 

Vagina.—In the Cow, the sides of the vagina are traversed, for a certa‘n distance, by 
a mucous canal that opens into the vulvular cavity, beside the meatus urinarius. These 
ducts, the use of which is unknown, are designated the canals of Gertner. They are 
not present in the Sheep or Goat. (In Ruminants, the vagina is longer and its external 
tunic thicker than in the Mare. Leyh describes the canals of Geertner as present in the 
Mare, though rarely.) 


Yulva.—This has thick lips in the Cow. The inferior commissure is acute, and 


THE FEMALE GENITAL ORGANS. 887 


furnished with a tuft of hair. (The corpus cayernosum of the clitoris is longer, thinner, 
and more flexuous, and the gland much smaller than in the Mare.) The meatus 
urinarius is disposed as in the mare ; but there exists, on the floor of the urethra, a valve 
whose free border is directed backwards. This valve surmounts a small cul-de-sac 
which it is necessary to avoid in catleterism of the bladder. At about an inch from the 
entrance to the vulva, there are found in the texture of the labia thé yulvo-vaginal glands 
(glands of Bartholine). Discovered by Duverney, described by Bartholine, and 
recently by Colin,' these glands (two in number) are about the size of a large almond ; 
their wide extremity is directed upwards, and the narrow end, situated in the vicinity 
of the ischio-clitoridis muscle, gives origin to the excretory canaliculi. They are 
racemose, and their ducts unite to form a kind of sinus, which at length opens in the 
vagival cavity, about 4 inches from the labia of the vulva. (These glandulz vaginz are 
supposed to be analogous to the prostate glands, and are covered by muscular fasciculi. 
They are composed of pyriform glandular vesicles, lined by squamous epithelium, and 
surrounded by a dense nucleated connective tissue; the excretory ducts are invested by 
columnar epithelium, and surrounded by a thin layer of smooth muscle-cells, disposed 
longitudinally. Their secretion is a clear, yellowish, viscid mucus.) 

(in the Sheep and Goat, the labia of the vulva have several folds externally, and the 
inferior commissure terminates in a point.) 

Mammz.—In the Cow, each lateral mammary mass, although enclosed in a single 
fibrous capsule, is composed of two distinct glands, each having its teat ; so that this 
animal really has four mammz and four teats. There are also frequently found behind 
these, two rudimentary imperforate (sometimes, though very rarely, perforate) teats. 

In the centre of each gland, at the base of the teat, is a single galactoferous sinus, the 
general confluent of all the lactiferous ducts—a wide cavity opening at the extremity of 
the teat by a definitive excretory canal. (The mamme of the Cow occupy the same 
region as those of the Mare, and the teats are longer and thicker.) 

In the Sheep and Goat, there are only two mamme, as in the Mare and Ass, though 
they are formed as in the Cow. The Goat has frequently two posterior rudimentary 
mamme. ; ee 

Pic.—The ovary of the Sow has a lobulated aspect, like the ovary of birds This 
appearance is due to the ovisacs which, when they are well developed, project beyond 
the surface of the ovarium, instead of remaining encysted in its stroma. The oviduct 
is less flexuous, but its length is proportionately greater than in the other species. The 
body of the uterus is short, but the cornua are very long and folded, and float_ amongst 
the intestinal convolutions. (Its cervix does not project into the vagina, and the two 
cavities, vagina and uterus, are continued into each other without any marked limit 
between them. The mucous membrane is very loose, soft, and fine to the touch, and its 
surface is gathered up into numerous folds of various forms. The broad ligaments 
resemble the mesentery, and the cornua join the F allopian tubes without apy very 

erceptible limit. . 

: The vagina oa Gertner’s canals, as in the Cow. (Its mucous membrane — 
numerou. longitudinal folds anteriorly ; and in front a multitude of fine ee " i 

are the excretory ducts of small glands analogous to the prostates. On the si a oe : 
meatus urinarius are two small fossettes surrounded by a ring. There is no reas valve. 

The inferior commissure of the vulva is more acute than in Ruminants. T a 
are ten in number, disposed in two rows, extending from the inguinal ons : nee 
the chest. They have no galactoferous reservoirs, a8 10 the larger ae a Hie 
lactiferous ducts uniting directly into a variable number of Epes a : at p' i 
through the teat, to pierce ils exteamntg by tae es Me ten orifices. (There are, 

e, ix glands in each row, each with its ‘ . . ee 
Me ee the Dog and Cat, the page = ce iis Se cate ae 
the ovaries (are situated behind the kidneys, an Rest lodge ee ae cic 
brow? Tigamants, which ieee Pane! d ate at tie turerier commissure. The 
vagina, The vulva of the Dog is triangular, anc acule ten in number in the Dog, and 
Cat has a small bone in the clitoris. The oo oe eat amen ae an 
eight in the Cat, they are distinguished, as in the Pig, into inguinal, al, 
pectoral. (Bach eat has from eight 10 ten ae, ular bres of ais external 
the vulva than towards the uterus. ‘Dcsia DEE ele aed weistowtey, (ELE tOUeH 
coat, it has white ea te ie Se deo folds; the valve of the meatus 
peeve ti Ce ee of the uterus projects into the vagina, and is even 
ie Lind Hin She the body, which is short; it is hard to the touch.) 


1 «Praité de Physiologie Comparée des Animaux Domestiques.” Paris, 1871. 


888 THE APPARATUS OF GENERATION. 


COMPARISON OF THE GENERATIVE ORGANS OF WOMAN WITH THOSE OF ANIMALS. 


Ovaries.—These organs are oval, about 13 inches long and 8-10ths of an inch broad, 
and are lodged in the posterior layer of the broad ligaments. They are attached to the 
uterus by the ligament of the ovary, and united to the Fallopian tubes by the Fallopio- 
ovarian ligament. Their structure is the same as in animals. A Graafian vesicle 
usually ripens every month; its rupture corresponds with the menstrual period, 
Annexed to the human ovary is found the organ of Rosenmiiller, composed of from fifteen 
to twenty tortuous tubes opening into a transverse branch; these tubes are lined by 
ciliated epithelium, and filled with a yellow fluid; they form a closed system included 
in the broad ligament, between the ovary and oviduct. ee : 

Oviduet.—Placed at the upper border of the broad ligament, it is nearly straight, and 
terminates by a pavilion notched into about fifteen unequal fringes. : 
Uterus —The human uterus is situated between the bladder and rectum, being inclined 


Fig, 416. 


UTERUS WITH ITS APPENDAGES, VIEWED FROM THE FRONT. 

1, Body of the uterus; 2, Fundus; 3, Cervix; 4, Os uteri; 5, Vagina, with its 
columna and transverse ruge; 6, 6, Broad ligament of the uterus; 7, Convexity 
of the broad ligament formed by the ovary ; 8, 8, Round ligaments of the uterus; 
9, 9, Fallopian tubes; 10, 10, Their fimbriated extremities; 11, Ovary; 12, 
Utero-ovarian ligament; 13, Fallopio-ovarian ligament; 14, Peritoneum of 
anterior surface of uterus; it is removed at the left side, but on the right is 
continuous with the anterior layer of the broad ligament. 


slightly downwards, from before to behind. Its form is very different from the uterus of 
the animals we have described, being that of a flattened gourd; its volume varies with 
age and the number of gestations ; it weighs about two ounces. It is described as having 
a body and cervix. The body is triangular, and at the extremities of its upper border 
the oviducts open into it. The cervéa is fusiform ; the projection it makes at the bottom 
of the vagina is the tench’s nose—a transversal slit bordered by two unequal lips. The 
inner face of the cervix shows the plic# palmate, arborisations formed by the mucous 
membrane. 

There is nothing special to be noticed in its structure. 

The broad ligaments comprise a quantity of muscular fibres between their layers, 
and which accumulate at certain points to form accessory folds; among these the most 
important are the round ligaments. These leave the anterior face of the uterus, pass 
forward and outward, enter the inguinal canal, and terminate in the connective tissue of 
the mons Veneris. 

Vagina.—This canal is about 23 inches wide; it is in contact with the rectum, and 
responds in front, by connective tissue, to the bladder and urethra. Its internal face 
has longitudinal folds, the columne of the vagina, which are intersected by transverse 
folds. Below the orifice of the urethra is the entrance to the vagina, a circular opening 
partially closed by the hymen in virgins. Rarely complete, this membrane may affect 
different shapes, and consequently receive various names, as horse-shoe, bilabial, 
semilunar, annular, and fringed hymen. When ruptured, it retracts very much, but 
there always remain some vestiges of it, and which are designated carunculx myrtiformes. 

Vulva.—This presents a cavity and an orifice, as in the domesticated animals; but 
the cavity is not so deep, and is named the vestibule; it extends to the hymen or its 
debris. The entrance to the vulca occurs in the middle of a cuneiform prominence 
which is confounded, above, with a kind of eminence, the mons Veneris, which appears to 
protect the pubic symphysis. It is margined by two folds: one cutaneous, the labia 


THE GENERATIVE APPARATUS OF BIRDS, 889 


majora; the other mucous, the labia minora (or_nymphex). The labia majora are 
convex externally, continuous above with the mons Veneris, and unite below to form an 
acute angle, named the fourchette ; they are covered externally with hair. The labia 
minora, more or less developed, leave the fourchette, and extend around the entrance to 
the vagina, uniting above the clitoris, and forming the prepuce of that organ. 

The clitoris is lodged in the superior commissure of the vulva; its point is directed 
downwards, especially during erection; its base is attached, on each side, to the two 
erectile lobes which constitute the bulb of the vagina (bulbi vestibuli). 

Two racemose glands, the vulvo-raginal or glands of Bartholine, pour their secretion. 
over the walls of the vestibule. 

Mammez.—These are pectoral, and two in number. In their centre, they present an 
enormous papilla—the nipple—into which the excretory canals open ; it is surrounded by 
a brown circle, the areola of the nipple. 


CHAPTER III. 
GENERATIVE APPARATUS OF BIRDS, 


1. Male Generative Organs. 


THE generative organs of the male are the testicles, and an excretory apparatus much 
simpler than that of mammals. ; ; ; 

Testicles—These organs are placed in the sublumbar region of the abdominal cavity, 
behind the lungs, and below the anterior extremity of the kidneys. Their form is 
usually oval, and their volume varies with the different species, as well as at different 
seasons ; at the breeding season they are greatly developed. ; er . 

Ecretory Apparatus.—In birds there is not, properly speaking, any epididymis. The 
vas deferens passes from within the posterior extremity of the testicle, is directed in a 
flexuous manner backwards, draws near to the ureter on its own side, going along the 
kidney with it, and arriving at the cloaca, where it terminates by an oritice to be alluded 
to hereafter. In the Duck, it has near its termination a small oval vesicle, always filled 

ith spermatic fluid. ie 

ee of Copulation.—This varies with the species. In the Gallinaex, it is only 
asmall papilla placed below, near the margin of the cloacal opening, and between the 
two orifices of the deferent canals. This papilla is traversed by a furrow through which 
the semen flows. In the Palmipedes, this organ is much more developed, and is 
peculiar. Contained within a tubular cavity in the cloaca, it is protruded externally at 
the moment of copulation by the eversion of this cavity, like a finger out of a glove; it 
then appears as a long pendant appendage, twisted like a cork-screw. 


2. Generative Organs of the Female. 


of the young animal taking place external to the female, the 
Ree een aia limited A that producing the ovum, and the duct through which it 
vary. : ; 
Dg eee only one ovary, which is situated on the left side, the bleh 
one becoming atrophied very early in nearly all species. This ovary is siimaited,, vee e 
testicles, in the sublumbar region of the abdominal cavity, and constitutes a ae or He 
voluminous body, composed of a variable number of ovules in process of we opmen 
some very young, little, and white; others more advanced in age, Reine on 
yellow in colour. The ova are enveloped in a very vascular cellular mem sea Ww. a . 
when they are ripe, splits in a circular manner, following an equatorial line, and permits 
the escape of the essential part of the egg—the yellow (yell), or vitellus. Cities: 
Oviduct.—This duct is long, very wide and dilatable, and very flexuous. ane 
near the ovary, by an unfringed pavilion, and terminates in the cloaca by a oe a 
narrow orifice, which is considerably widened when the egg passes through it. T e egg, 
composed, on entering the oviduct, of the fundamental part named the yelk, or vite - is 
enveloped in an albuminous sphere during its progress towards the cloaca, and after- 
wards with a protecting shell. The oviduct of birds is, therefore, something more than 
an excretory canal, as it participates in the formation of the ovum. It is composed of 
three membranes: an external, serous, maintains the tortuous tube; a middle, muscular: 


and an internal, mucous. 


BOOK IX. 


EMBRYOLOGY. 


Empryotocy has for its study the modifications to which the ovulum is 
submitted, from the moment when it is fecundated until it is transformed 
into a new being capable of living in the external world. 

The points of this subject belonging to the domain of anatomy, will be 
divided into three chapters. In the first, the transformations of the ovulum 
which produce the ovum and embryo will be examined. In the second, the 
various portions of the ovum—the annexes of the foetus—will be studied ; 
and the third will be occupied with the development of the foetus. 


CHAPTER I. 
THE OVULUM AND ITS MODIFICATIONS AFTER FECUNDATION. 


ArticLe I.—Txe Ovuium. 


Tue ovulum of the domestic mammifers is a vesicle about 1,5, of an 
inch in diameter (the germinal spot being from gg/5q to gzyq of an inch), 
contained in the ovisac, in the midst of the cumulus proligera. It possesses 
all the elements of a complete cell, comprising: 1, An amorphous, trans- 
parent enveloping membrane, named the vitelline membrane, or zona pellucida ; 
9, A hazy viscous fluid, holding in suspension a large number of dark 
granulations and fat globules: this is the vitellus or yelk; 8, The ger- 
minative vesicle, a spherical, transparent nucleus lying to one side of the 
vesicle, and readily altered; 4, The germinal spot, a kind of very brilliant 
nucleolus seen in the centre of the nucleus. According to Balbiani, there 
also exists in the ovulum of all animals, from insects up to mammals, 
beside the germinative vesicle, a second nucleus—named Balbiani’s or the 
embryogenous vesicle—which plays a very important part in the nutrition of 
the ovulum and the phenomena succeeding fecundation. 


Agticte I].—Mopirtocations IN THE OvuLUM UNTIL THE APPEARANCE OF 
THE EmpBRyo. 


These include the segmentation of the vitellus, the formation of the 
blastoderm, and the appearance of the embryo. 

1. SzeMENTATION OF THE ViTELLUs.—Several times spermatozoa have 
been seen in the vitelline zone of the fecundated ovulum. This fact is merely 
alluded to, as we have to speak of the consequences of fecundation, and not 


THE FQ@TUS. 891 


of fecundation itself. After it has taken place, the germinal vesicle is not 
perceived ; has it disappeared, or changed its character if it does yet exist? 
This question cannot be answered; all that is known is that it has ceased 
to be visible. Then the contraction of the vitellus begins; it leaves its 
enveloping membrane, becomes depressed in a circular manner, and ends by 
forming two independent masses, each provided with a nucleus. These two 
globes of segmentation (or cleavaye masses)—for such is the name given to 


PROGRESSIVE STAGES IN THE SEGMENTATION OF THE YOLK OF THE MAMMALIAN OVUM. 
A, Its first division into halves, with the spermatozoa around its circumference ; 


B, Subdivision of each half into two; c, Further subdivision producing numerous 
segments. 


them—are, in their turn, divided into other two globes, the number now being 
four. These four are once more divided, and these again subdivided, until 
the whole mass of the vitellus is completely transformed into globules 
(or embryo-cells), composed of a nucleus covered by a thin membrane. 


Fig. 418. 


LATER STAGE IN THE SEGMENTATION PROCESS. 
‘A, Mulberry mass formed by the minute subdivision of the vitelline spheres; B, A 
further increase has brought its surface into contact with the vitelline membrane, 
against which the spherules are flattened. 


This is the segmentation of the ovulum: an operation that is always 
preceded by the retraction of the vitellus, and the appearance of one or two 
small globules about the point where it commences to be depressed; these 
Robin has designated polar globules. 


392 EMBRYOLOGY. 


2, ForMATION oF THE BLasTopeRM.—Soon a fluid is formed at the centre 
of the ovulum, in the midst of the mass of vitelline globules, or rather the 
mass of young cells that take the place of the vitellus. This fluid presses 
the globules outwards against the inner face of the vitelline membrane, and 
the pressure increasing as it augments, these become flattened like the 
elements of pavement epithelium, until, finally, they constitute a membrane 
lining the zona pellucida. This is the blastoderm. 

The blastodermic vesicle (as it has been termed) does not remain 
simple, but soon divides into two layers: an ewternal and internal blas- 
todermic layer, which are readily recognisable, as the elements of the first 
are pale or slightly granular, while the cells of the second are filled with fat 
granules, and consequently are less distinct and darker coloured. 

3. APPEARANCE OF THE Empryo.——-While the blastoderm is dividing into 
layers, there is observed another modification taking place in the ovulum, 
from which results the first lineaments of the embryo. As soon as tho 
blastodermic vesicle is formed, a small round thickening takes place at a 
point of its surface, due to a multiplication of cells. This mass destroys the 
transparency of the blastoderm, and is designated the embryonic spot or 
area germinativa. 

The area germinativa is the centre where commences the separation of 
the blastoderm into external or internal layers. The middle layer, which 
is to form the feetal organs, does not extend beyond this area. 

By a proliferation of the elements of the external and middle layers, the 
areca germinativa increases in surface and thickness; it becomes dark, 
prominent, and buckler-shaped, and is named the opaque area ; this is soon 
transparent in its centre—the area pellucida. The area pellucida becomes 
elongated and constricted in its middle to form the embryonic area ; in the 
middle of this appears a dark line, the primitive trace or furrow, and below is 
perceived a round cord—the chorda dorsalis—which develops the spinal 
axis. 

The inner layer, in its turn, becomes two layers at the point cor- 
responding to the embryo, and this gives rise to the middle layer. 

In fine, towards the twelfth day after fecundation, the ovum, having 
arrived in the uterus, measures from 54,th to z4,th of an inch in diameter, 
and is composed of four shells contained one within the other, three of 
which are complete, viz: 1, The zona pellucida; 2, The external layer of 
the blastoderm; 38, The middle layer; 4, The internal layer. At this 
time the first membrane, destined to become the chorion, is already studded 
with fine villosities. 


ArtioLe IIJ.—D£vELOPMENT oF THE Buastopermic Layers. 


By ulterior metamorphoses, the layers of the blastoderm give rise to the 
annexes of the foetus and its various organs. Therefore it is that these 
layers receive other names than those which designate their situation. 
Thus the external, or serous, isnamed the sensitive layer, because it forms the 
skin and organs of sense; the middle is the vascular or germinative, as it 
contains the principal vessels of the embryo, and in its substance are 
developed the organs of locomotion; lastly, the internal layer is termed the 
mucous or intestino-glandular, in consequence of its constituting the mucous 
membranes, and its chief portion forming the intestines and their glands. 

_ Each blastodermic layer, then, in becoming developed, furnishes the 
intrafcetal and extrafctal parts. We will study this development, having 


THE FQ@TUS. 393 


the extrafcetal parts particularly in view, and reserving the others until wo 
come to examine the development of the foetus. 


EXTERNAL LAYER. 


a. Intrafeetal parts—The external or sensitive layer (serous stratum- 
epiblast) forms several parts belonging to the foetus; these are: 1, The 
epidermis and its dependencies, such as the hair, hoofs, horns, glands of the 
skin; 2, The central nervous system: the organs of the senses, such as the 
retina and the labyrinth. ; 

b. Extrafetal parts—S8o long as the foetus is represented b i 
shield at a given point of the blastodermic ee the stiansl Frere = 
everywhere continuous, and extends to the inner face of the chorion and the 
surface of the embryo without any line of demarcation. But the embryo 
soon becomes inflected at its two extremities; the external layer of the 
blastoderm is depressed so as to give rise to two layers: the cephalic hood 
which covers the cephalic extremity, and the caudal hood, which envelops 
the other extremity of the embryo. 

The lateral parts of the foetus also become inflected towards one another 
as may be proved by a transverse section; thus closing-in, laterally the 
thoraco-abdominal cavity of the young creature which, during this move- 
ment, is more deeply placed in the serous layer. The latter soon comes into 
contact with itself, above the back of the embryo. 

A short pedicle, the superior umbilicus, unites the two portions of the 
blastodermic layer. This pedicle is not long before it becomes obliterated 
then breaks, when the foetus is found to be inclosed in an independent gac, 
which is nothing more than the amnion. : 


Fig. 419. 


vig 


TRANSVERSE SECTION THROUGH THE EMBRYO OF THE CHICK AT THE CLOSE OF THE 
FIRST DAY OF INCUBATION; MAGNIFIED ABOUT 100 DIAMETERS. 


ch, Chorda dorsalis; 4, External serous, or corneal layer; m, Medullary position of 
serous layer; Pr, Primitive groove between the dorsal lamina, Rf and m; dd, 
Intestinal epithelial, or glandular layer (mucous layer); wwp, Prevertebral mass, 
in which the primary, or protovertebra, are formed, and which is continuous 
with the middle lamina, sp; wwh, Fissure in the middle lamina, presenting the 
first indication of the pleuro-peritoneal (thoraco-abdominal) cavity, and of the 
subsequent division of the middle lamina into two layers. 


The sensitive layer is therefore resolved into two sections: an internal, 
the amnion ; and an external, the serous vesicle (false amnion of Pander, the 
serous covering of Von Baer), which is applied to the inner face of the zona 
pellucida, and concurs in forming the chorion. 


MIDDLE LAYER. 


All the parts to which the middle layer gives rise, belong to the organs 
of the fetus; the development of this layer will be more appropriately 
studied in the chapter devoted to the foetus. 


894 EMBRYOLOGY. 


INTERNAL LAYER. 


a. Intrafetal parts—The mucous layer of the blastoderm forms the 
epithelium of the intestines, the glands annexed to them, the respiratory 
apparatus, the kidneys, and the bladder. These organs are developed at the 
same time as the extra foetal portions, and will be referred to presently. : 

b. Extrafeetal parts.—In incurving on itself, the embryo incloses in its 
cavity a portion of the internal blastodermic layer. The union between the 
free and the imprisoned portions is extensive; but before long it is only 
represented by a narrow canal that occupies the inferior umbilical ring. 
The mucous layer is then divided into two distinct portions: the intestinal 
groove, or intrafoetal portion; and the umbilical vesicle (vesicula alba), or 
extrafoetal portion; they communicate by the omphalo-mesenteric or vitelline 
duct. 


Fig, 421, 


Fig. 420. 


< 


DIAGRAM OF OVUM AT THE FORMATION 


PLAN OF EARLY UTERINE OVUM. OF THE AMNION. 
Within the external ring, or zona pellucida, a, Chorion; b, Yolk-sac; vc, Embryo; d ande, 
are: the serous lamina, a ; the yolk, b; and Folds of the serous layer rising up to form 
the incipient embryo, c. the amnion. 


The umbilical vesicle is filled with a granular fluid, which is conveyed, 
for the nutrition of the foetus, by the omphalo-mesenteric vessels. When 
this alimentary reserve is nearly expended, the allantois appears. 

The allantois commences by a small enlargement, which is thrown out by 
the intestinal furrow on the inferior abdominal wall. This bud becomes 
elongated, and gradually enlarges by drawing the umbilical vessels to its 
border: appearing as a small vesicle that at length extends through the 
umbilicus, and spreads itself over the inner face of the chorion, between it 
and the amnion. 

This new organ is divided into two sacs by a neck—the wrachus—at 
the umbilical ring; the internal is the smallest and forms the bladder, and 
the external, the most voluminous, constitutes the allantois proper. 


THE FCQTUS. 895 


CHAPTER II. 
THE F@TAL ENVELOPES OF SOLIPEDS. 


We have seen, in the preceding chapter, that the vitelline membrane lined by 
the serous vesicle forms a complete shell around the developing ovum; and 
we have also noted that the layers of the blastoderm, in becoming meta- 
morphosed, constitute three membranous sacs, which contain the foetus. 
These various membranes are described as the envelopes or anneaes of the 
foetus. There are also added to these the cord of vessels and the capillary 
ramifications which establish the relations that exist between the mother 
and the young creature. 

The annexes of the fetus comprise: 1, A membranous envelope exactly 
moulded on the uterus, and known as the chorion; 2, A second ovoid sac 
included in the first, and directly containing the foetus: this is the amnion ; 
8, The allantois, a membrane formed of two layers spread over the inner 
surface of the chorion and the external face of the amnion, as well as 
covering the parts between these two envelopes; 4, A small pyriform bladder 
constituting the umbilical vesicle; 5, he placenta, a collection of vascular 
tufts which graft the young creature to the mother; 6, The umbilical cord, 
composed of vessels that attach the foetus to the envelopes surrounding it, 
and which ramify in the placental tufts. 


1. The Chorion. (Fig. 422.) 


The outermost envelope of the ovum, the chorion is a vast membranous 
and perfectly-closed sac, whose shape exactly corresponds to that of the uterus. 


Fig. 422. 


EXTERIOR OF THE CHORIAL SAC; MARE, 
A, Body; B, c, Cornua. 


body and two cornua. The latter, when inflated, are plicated and 

Hpuecead hike the cecum, and are always unequal in volume : that in which 
the foetus is developed having by far the largest dimensions. 

The external face is studded with small red tubercles, formed by the 


896 EMBRYOLOGY. 


placental tufts. It adheres to the internal surface of the uterus. Between 
the two membranes there is found a small quantity of sanguinolent fluid. 

The internal face, lined by the external layer of the allantois, is united 
in the closest manner to that membrane, except at the umbilical cord, where 
there exists a kind of conical infundibulum occupied by the umbilical 
vesicle. 

Srructure.—The chorion is a delicate fibrous membrane, traversed by 
the vascular ramifications of the placenta. It is formed by the vitelline 
membrane, to the inner face of which the serous vesicle is applied. It is 
stated that the zona pellucida, or primitive chorion, as it is called, disappears 
when the serous vesicle, the definitive chorion, becomes 
independent of the amnion. 

The chorion is destitute of vessels until the 
allantois is developed. 


2. The Amnion. (Figs. 423, 424.) 


The second sac enveloping the foetus, the amnion 
floats freely in the interior of the chorion, to which 
it is only united at one point through the medium of 
the umbilical cord. It contains the young creature, 
geist Bic Pagid which is also attached to its inner face by the vessels 

xiow AND attantors, Of the cord. It is oval in shape, and has thin trans- 
ua, Umbilical vesicle; 6, parent walls. 
Amniotic cavity; c, Al- Its eaternal face is covered by the inner layer of . 
lantois. the allantois, to which it adheres slightly. The 
internal face is perfectly smooth, and is applied more 
or less directly to the skin of the fetus. It exhales a fluid in which the 
latter floats—the liquor amnit. 

Liquor amnii—tInclosed with the foetus in the 
cavity of the amnion, this fluid is more or less abun- 
dant, according to the period of gestation ; its relative 
quantity being always less as the foetus is advanced 
in development. At an early period it is somewhat 
milky in appearance, but later it assumes a citrine or 
slightly reddish tint. It has a salt taste, and con- 
tains 99 per cent of water, with albumen and salts, 
the principal of which are chloride of sodium and the 
sulphate and phosphate of lime. 


Fig, 424, 


FECUNDATED EGG OF FOWL zt 7 
is apes eter rest on 3. The Allantois, (Fig. 423.) 
COMPLETED. The allantois is a membrane that covers the inner 


d, Inner lamina of am- face of the chorion, and is folded around the insertion 
oS ee i oer of the umbilical cord, to spread itself over the whole 
Point where the amnjo. €Xternal surface of the amnion. It thus transforms 
tic folds come in contact the chorial sac into a kind of serous cavity, in which 
with each other; the the amnios is inclosed as a viscus. 
ores ig seen’ “pene The inner, or amniotic lamina, is attached to the 

rating between the 7 ee oe ‘ : 3. 
inner and outer laminn @®mMnios “so slightly that dissection, and especially 
of the amniotic fold. insufflation, easily destroys its adhesion. When the 

second of these measures is resorted to, in order to 


separate the two membranes, the allantoid surface assumes a bosselated 


THE FATUS. 897 


or blistered appearance, due to the numerous cellular bands that attach it to 
the amnion. These bands rupture when the inflation is forced, and a noise 
is heard analogous to that produced by the rumpling of parchment. With a 
little care, the whole of this portion of the allantois, whose extent equals 
that of the amnion, may be entirely detached. 

“The degree of adhesion of the chorial allantois is more marked. 
Ordinary dissection, which is easy along the first divisions of the cord, is 
much more difficult towards the chorion, and soon becomes, if not im- 
possible, at least very arduous, if we desire to separate it. But here, again, 
inflation demonstrates the existence of the membrane, and its continuity 
with the portion so easily dissected from the amnion. If, after opening the 
allantoid sac by cutting through the chorion and the lamina lining it, a 
tube is introduced between the two membranes—which is readily done near 
a large vessel, by a slight inflation the air enters between the allantois and 
chorion, though it only follows the track of vessels of a certain size, to the 
sides of which there is but little adherence. If the inflation is pushed, the 
air, following the smallest vascular ramifications, renders the membrane 
more apparent, though without detaching it from the points where the 
vessels have almost become capillaries. 

“Tf, instead of injecting the air towards the ramifications, it is directed in 
the opposite direction, it will soon be perceived to extend towards the 
allantoid portion of the umbilical cord, and insinuate itself between the 
amnion and the allantois covering it: an evident proof of the continuity 
of the two layers which have been separated for the purpose of studying 
them, but which are, in reality, only two portions of the same membrane 
that forms a complete sac.” + 

The cavity of this sac communicates with the bladder by means of the 
urachus, a narrow canal contained in the amniotic portion of the umbilical 
cord, and expanding towards the origin of the allantoid part (at p, Fig. 425), 
where its walls are continuous, one part with the amniotic layer of the 
membrane, the other with the chorial layer, after being prolonged as a 
sheath around the cord (8). This arrangement shows the true character of 
the allantoid cavity, which is evidently a kind of urinary reservoir, a 
dependency of the bladder, whose fundus is prolonged to the umbilicus to 
constitute the urachus. The latter follows the umbilical vessels in the 
amniotic portion of the cord, and soon expands in forming the allantoid 
cavity. 

e uormia “ihe allantois arises from the intestinal furrow, or otherwise 
the included portion of the internal blastodermic lamina. It comprises a 
slightly fibrous framework, and an epithelial layer. It carries the umbilical 
vessels to its surface, from the umbilicus to the chorion. 

Atxantor Fivrm.—This cavity contains a fluid. analogous to the liquor 
amnii, and which has almost the same physical qualities. Analysis 
demonstrates that, during the early months of fcetal life, this fluid contains 
a somewhat large proportion of sugar; this gradually diminishes, and at last 
disappears altogether. The fluid has been considered, towards the termina- 
tion of gestation, as the urine of the fcetus. 

Hipromanus.—This name is given to small brown masses, more or less 
numerous—though often there is only one—which float in the allantoid fluid, 
“These bodies, of the consistency of gluten, and elastic like it, are flattened, 
thinner at the borders than towards the centre, oval or irregularly circular, 
and about the diameter of a five-franc piece. It is difficult to explain the 

1 F, Lecog. ‘Des Annexes du Fetus.’ 


898 EMBRYOLOGY. 


presence of the hippomanes in the allantoid sac. Nothing in its appearance 
indicates that it may be formed at the expense of the liquid contained in this 
membrane. Sometimes pediculated hippomanes are found, and these may 
assist in explaining the formation of the free hippomanes. Bourgelat speaks 
in his ‘ Anatomie’ of pediculated hippomanes, and I have been able to make 
the following observations, through having met with a large number on a 


foetus : 


FETUS OF THE MARE WITH ITS ENVELOPES. 


A, Chorion; c, Amnion removed from the allantoid cavity, and opened to expose the 
fetus; D, Infundibulum of the urachus; B, Allantoid portion of the umbilical 
cord.—, Point of the external surface of the chorion, destitute of placental 
villi, and corresponding tc the part where the three pediculated hippomanes are 
attached, 


“Besides the free hippomanes found floating in the allantoid fluid, there 
were remarked, on the outer wall of the sac, a great number of small tear- 
shaped bodies of variable size, adhering by a pedicle which was more or less 
narrow as the mass was more developed. ‘Their colour was the same as 


THE FAQTUS. 899 


that of the principal hippomanes, and if pressed between the fingers, the 
brown matter coutained in a thin-walled sac escaped by the pedicle, and 
spread itself over the external surface of the chorion. There the villosities 
ot the placenta were absent at the margin of the opening, which was 
surrounded by a whitish areola (Fig. 425, b). 

“ Might it not be admitted, from this disposition, that the hippomanes ig 
developed between the placenta and the uterus, and is carried inward, by 
pushing before it the chorion and layer of the allantois covering it, until, 
on reaching the allantoid cavity, it becomes detached, like certain fibrous or 
cartilaginous bodies in the synovial or serous cavities ?’—F. Lecoq. 


4. The Umbilical Vesicle. 


The umbilical vesicle is a small fusiform or pyriform pouch, lodged in the 
infundibulum at the extremity of the umbilical cord. Its fundus adheres to 
the chorion; the opposite extremity is prolonged to a variable depth in the 
substance of the cord, and is even continued, in the very young foetus, to the 
abdominal cavity, by a narrow canal that communicates with the terminal 
portion of the small intestine. 

This pouch has a red colour, from its great vascularity; its walls 
receiving a special artery derived from the anterior mesenteric, the 
corresponding vein passing to the portal vein. These are the two omphalo- 
mesenteric vessels. ij 

In the last months of foetal life, the umbilical vesicle is always more or 
less atrophied; its cavity has disappeared, and it is no more than a thin 
reddish-brown cord. Its vessels also become atrophied in the same manner, 
and nearly always nothing is found but the artery reduced to the dimensions 
of a thread. 


: 5. The Placenta. 


In Solipeds, the placenta is composed of a multitude of small tubercles, 
spread uniformly over the external 
surface of the chorion, which they 
almost completely cover. These 
small tubercles are formed by an 
ageregation of extremely vascular 
villi, which implant. themselves in 
the follicles of the uterine mucous 
membrane. The terminal ramifi- 
cations of the vessels of the cord 
constitute the vascular apparatus of 
these villi (Fig. 426). ; 

Srrvcturs.—The villosities Of portion of THE ULTIMATE RAMIFICATIONS 
the placenta are composed of ® oF THE UMBILICAL VESSELS, FORMING THE 
small quantity of delicate nu-  F@TAL VILLI oF THE PLACENTA. 
cleated connective tissue (and a pare 
basement membrane), covered by simple epithelium; at their centre, they 
present the capillary ramifications of the vessels of the cord, which generally 
form loops that return towards the base of the papilla (Fig. 427). ; 

The villous tufts penetrate the maternal uterine mucous membrane, in 
such a manner that the two capiilary systems of mother and foetus are only 
separated by the very thin walls of the vessels and the epithelium of the 


900 EMBRYOLOGY. 


villi. The fusion of these two systems has never been observed, and all the 
interchanges between the female and its young take place through the 
capillaries by osmotic force only. 


6. The Umbilical Cord. 


The cord is formed by the vessels which, in the foetus, carry the 
blood to the envelopes, and chiefly to the 
placenta. It is divided into two portions: 
an amniotic, the longest, which is always 
twisted on itself like a cord, and covered 
externally by the amnion that is prolonged 
on its surface, to be continued with the 
skin around the umbilicus; the other, the 
allantoid portion (Fig. 425, 8), much 
shorter and less twisted, is enveloped by the 
sheath that continues the two lamine of 
the allantois, and is inserted into the supe- 
rior wall of the chorion, between the two 
cornua. , 

Three vessels compose the cord: two 
arteries and a vein; these are covered by 
a layer of embryonic tissue, the gelatine of 
Wharton, which makes them appear much 
larger than they really are. 

The Umsrnican Arteries arise from 
the internal iliac, and pass along the sides 
of the bladder; escaping by the umbilicus, 
they arrive at the terminal extremity of 
the amniotic portion of the cord, and 
giving off some branches to the amnion, 
they are continued to the extremity of the 
allantoid portion, where they end in an 
PORTION OF ONE OF THE FETAL VILLI, expansion of placental ramifications. The 

peeae ani Seen amniotic divisions of these arteries are 
u, a, Its cellular covering; 6, 6, b, Its few, and extremely flexuous ; they ene: a 

looped vessels} ¢, e, Its basis of con cluded between the allantoid layer and the 

nective tissue. amniotic membrane, within which they 

ae may be seen. The placental or chorial 
divisions, infinitely larger and more numerous, leave the end of the cord, 
and pass in every direction between the chorion and external lamina of the 
allantois, beneath which they project. By their anastomoses they form a 
very rich network, from which proceed the capillary twigs that enter the 
villosities of the placenta. Observation demonstrates that these twigs do 
not communicate with the maternal vessels, and that they are continued by 
venous radicles, the origin of the following vessel. 

The Umpmican Vern commences by these capillary radicles of the 
placental villosities, which unite between the chorion and amnion to form a 
network of more voluminous divisions and complexity than that of the 
arteries. Two principal branches are, finally, the result of the coalescing ; 
and these soon unite into a single trunk, which accompanies the two 
arteries in the cord. On reaching the umbilicus, this, the umbilical vein, 
bends forward on the inner face of the abdominal parietes, where it is 


THE F@TUS. 901 


covered by the peritoneum, and arrives at the liver, into which i 

; : A f ch it enters and 
opens directly into the vena porte ; the junction of the two vessels giving 
rise to a single canal from which proceed the hepatic veins. In other 
animals than Solipeds, this vessel gives off a particular trunk of somewhat 


Fig. 428, 


A F@TUS OPENED ON THE LEFT SIDE TO SHOW THE COURSE OF THE UMBILICAL 
VESSELS IN THE BODY. 


A, Umbilical cord; B, Umbilical vein; c, Umbilical artery; D, Bladder; x, Testicle; 
F, Kidney; G, Spleen; u, Liver; 1, Intestine, J, Lung; x, Heart; L, Pulmonary 
artery ; M, Ductus arteriosus; N, Thymus gland. 


considerable volume, which passes directly to the posterior vena cava, 
forming what is named the ductus venosus (Figs. 429, 430). 

Such are the umbilical vessels, and it will be seen that they form a part 
of the circulatory system of the young creature which will be more com- 


pletely studied hereafter. ‘ 


DIFFERENTIAL CHARACTERS IN THE ANNEXES OF THE FETUS OF OTHER THAN SOLIPED 
ANIMALS, 


1, Rummwanrs.—Placenta.—The placental apparatus of the Cow is not uniformly 
spread over the outer surface of the chorion, but is constituted by a variable number of 
vascular bodies, about sixty on an average, disseminated here and there, and dovetailed by 
reciprocal penetration of prominences and cavities, into analogous bodies on the inner 
surface of the uterus, designated cotyledons. These are only thickened points of the 
mucous membrane, the follicles of which are enormously enlarged. They exist, we have 
seen, before gestation ; but observation demonstrates that they may be afterwards formed 
or entirely renewed, especially in those cases in which accidental Circumstances have 
rendered those present insufficient for their office. The largest are found in the body of 
the uterus; in the cornua they are smaller as they are nearer the extremity. Their 
form is generally elliptical, and they are attached to the uterine surface by a wide mucous 


60 


902 EMBRYOLOGY. 


Fig, 429. 


OCH KRL.LOGR « 


BLOOD-VESSELS IN THE LIVER OF AN EQUINE FETUS AT MID-TERM. 


A, Umbilical vein; B, Its anastomoses with the portal vein, c; pD, Ductus venosus ; 
E, Posterior vena cava. 


? Fig. 430. 


LIVER OF A LAMB AT BIRTH. 


A, Posterior vena cava; B, Vena porte; c, Umbilical vein; D, Anastomosis of 
the umbilical vein with the vena porte. 


THE FQTUS. 903 


pedicle; their surface is convex, and perforated by numerous openings, into which the 
placental tufts pass. They have always a yellowish colour which, added to their 
external characteristics, gives them the appearance of a moril mushroom. 

With regard to the placentzx, they repeat, on the surface of the chorion, the disposition 
of the cotyledons on the uterus. They are vascular, concave patches, closely embracing 
the cotyledons, and showing on their surface a multitude of long ramifying papille, 
which bury themselves in the cotyledonal cavities. They are attached to the chorion by 
a very thick, short, vascular pedicle. 

In the Sheep and Goat the arrangement is the same, except that the cotyledons are 
hollowed out in their centre, like a cup, and into this cavity the placenta is inserted. 

Chorion.—This membrane corresponds to the inner face of the uterus, in the inter- 
placental points; its internal surface is united by lamellar connective tissue to the 
amnion and allantois. Its general form is a repetition of that of the uterine cavity. 

Allantois—Very different trom that of the Mare, and otherwise much less com- 
plicated, the allantois of Ruminants is a very elongated cavity, whose middle portion 
receives the insertion of the urachus, and whose extremities are prolonged into the two 
cornua of the chorion. This sac, which is an expansion of the urachus, is always 
reversed on one of the sides of the amnion. At times the hippomanes is found floating 
in the liquid it contains. 

Amnion.—Altogether like that of Solipeds, this membrane is readily resolved into 
two lamina, and presents on its inner surface a great number of little, yellowish-white, 

epidermic patches, more especially visible on the amniotic covering of the cord. 

. Umbilical cord.—This comprises two arteries and two veins; the latter forming one 
trunk on their entering the abdomen. To reach the chorion, these vessels only traverse 
the amniotic cavity. They are accompanied by the urachus, which at their extremity 
presents the dilatation that results in the allantoid sac. 

Umbilical vesicle—This pouch disappears at an early period, and not a vestige of it 
is to be found after the formation of the abdominal parietes. 

_. 2. Pig.—The placenta is formed by an expansion of the villous tubercles, as in 
Solipeds. ' 

The chorion has not a body and two cornua, but is merely an elongated sac, whose 
two extremities are in relation with the adjacent foetuses. The inner tuce corresponds, 
as in Ruminants, with the amnion and allantois. The latter is the same as in the Cow, 
though it is very much shorter. ; 

The umbilical vesicle, amnion, and cord are also the same as in Ruminants. 

3. Carnivora.—The placenta is a thick cincture, surrounding the middle portion of 
the chorion. The latter resembles that of the Pig. 

The allantois is disposed, in principle, as in Solipeds. 

The umbilical vesicle, which remains very developed at all periods of foetal life, 
resembles in shape the allantois of the Pig : being a transversely elongated sac included 
between the amnion and the inner allantoid lamina, and provided at its middle portion 
with a narrow pedicle, which is prolonged into the umbilical cord; its walls are 
extremely vascular. : ; : 

The amnion is lined, internally, by the inner lamina of the allantois. 

The umbilical cord has, as in Solipeds, an allantoid portion; but it is extremely 
short, and enveloped in a wide fold of the allantois. ates 

Resvubts.—The comparative examination of the disposition of the placenta may 
furnish valuable indications as to the procedure to be adopted in practising artificial 
delivery ; as the surgical manceuvres should necessarily vary with the extent and disposi- 
tion of the points of union existing between the uterus and the foetal envelopes. _ 

With this practical object in view, we believe that it is useful to divide the 
domesticated animals into two groups: those which have a simple, and those which 
pave a multiple placenta. The first group may be subdivided, according as the simple 

a is general or local. : 
— aiaion is summed up in the following table: 


General. . . . ioe 


. Bitch. 
Local and Circular . { Cat. 


Simple Placenta 


Animals 
Cow. 

Multiple Placenta . . «ss ee e | Sie 

Goat. 


904 EMBRYOLOGY. 


COMPARISON OF THE ANNEXES OF THE HOMAN FETUS WITH THOSE OF ANIMALS. 


footus, like that of the domesticated mammals, is enveloped by an amnion 
Be geen anh are generally identical in disposition with those already described. 
‘The umbilical vesicle submits to the same change as in the Mare, becoming so quickly 
atrophied that scarcely any traces of it can be found at birth. It is impossible to 


isolate the amnion from the inner face of the chorion ; so that some anatomists only 
admit its presence by analogy with what is observed in animals. 


Fig. 431. Fig, 432. 


DIAGRAM OF A HUMAN OVUM IN SECOND 
DIAGRAM OF AN EARLY HUMAN OVUM, MONTH, SHOWING THE COMPLETION OF 


SHOWING THE AMNION IN PROCESS OF THE SAC OF THE AMNION, AND A FUR- 
FORMATION, AND THE ALLANTOIS BEGIN- THER DEVELOPMENT OF THE ALLANTOIS. 


NING TOVAEP EAR, al, Smooth portion of the chorion; a2, Its 


a, Chorion; 6, Vitelline mass, surrounded by villous portion; %, 4, Elongated villi col- 
the blastodermic vesicle ; c, Embryo; d, ¢, f, lecting into placenta; b, Vitelline, or um- 
External and internal folds of the serous bilical vesicle ; c, Embryo; f, Amnion, inner 
layer, forming the amnion; g, Incipient’ layer; A, Its outer layer coalescing with 
allantois. the chorion. 


The umbilical cord offers nothing particular. The placenta is circular; its diameter 

at the termination of pregnancy being from 6 to 8 inches, and its thickness from 1 to 14 

inches. There is distinguished the fetal placenta, in the midst of which the umbilical 

cord arrives; and the maternal placenta, whose villosities dovetail with those of the 
former. 

The insertion of the placenta takes place towards the fundus of the uterus, near one 
of the Fallopian tubes. When there are more than one foetus, there are a corresponding 
number of placentz. 

Independently of those annexes, which are the same in all, there is described for the 
human foetus a special envelope, external to the chorion; this is the membrana decidua. 
This is formed by the hypertrophied mucous membrane, which is doubled around the 
ovum, when the latter is lodged in the uterine cavity. Consequently, there results the 
division of the decidua into two parts: the true decidua (decidua vera) which covers the 
uterus, and the reflected decidua (decidua reflexa) which envelops the chorion. These 
present the characters of the hypertrophied uterine mucous membrane. 


CHAPTER III. 


DEVELOPMENT OF THE F@TUS. 


In the two preceding chapters, we have seen how the fecundated ovulum 
is modified to furnish the earliest lineaments of the foetus and the organs 
annexed to it; this chapter will be devoted to an examination of the manner 
in which the foetus is developed. 

The young creature #s designated an embryo during the early period of 
gestation, before it has assumed any definite shape; but as soon as it exhibits 
the form of the species to which it belongs, it is named a fetus. The 
transition between these two states, though they have different names, is 
altogether inappreciable; so that we content ourselves with studying the 
first phases of development under the heading of the formation of the 
embryo, and the last under that of the development of the organs. 


ArticLte I.—Formation or THE EmBryo. 


When the embryo has assumed the form of an elongated streak, and 
shows in its middle the primitive groove, there appear in the middle lamina 
2 the blastoderm the chorda dorsalis, the vertebral lamince, and the lateral 
amine. 


DEVELOPMENT OF THE CHORDA DORSALIS AND VERTEBRAL LAMINAE. 


The chorda dorsalis is a cylindrical cord, slightly attenuated at 
both extremities, which is developed beneath the primitive groove. On 
its sides is a series of small opaque quadrangular masses—the vertebral 
lamince—which are nothing more than the protovertebre, or first traces of 
the foetal vertebre. Each of these little masses is soon perforated by an 
opening, and is then divisible into three portions : the protovertebral cavity, 
the muscular lamina, situated above the cavity, and the protovertebree, placed 
below it. 

The muscular lamine, in augmenting in volume, are inflected upwards, 
and unite in the middle line of the back. They form, in great part, the 
muscles of the vertebral furrows; they also give off, below, prolongations 
which concur in the development of the intercostal and abdominal muscles, 
as well as those of the extremities. 

The protovertebree curve upwards and downwards in such a fashion as to 
surround the protovertebral cavity or medullary canal, and the dorsal cord. 
The superior ring is the rudiment of the annular portion of the vertebra, 
and the inferior ring and dorsal cord constitute the vertebral bodies and 
the discs uniting them. 


DEVELOPMENT OF THE LATERAL AND CEPHALIO LAMINAE. 


The lateral lamine is the name given to that part of the middle lamina 
of the blastoderm which is placed to the right and left of the vertebral laminew. 
‘In the region of the trunk, these lamine are separated for a certain period 


906 EMBRYOLOGY, 


from the vertebral laminew; in the cephalic region they always remain 
adherent tc them, and at this point they are named the cephalic lamine. 

1. The proper lateral lamine are divided into two layers: an external and 
an internal, united by the middle lamina, and including between them a 
cavity which becomes that of the pleura and peritoneum—the pleuro- 
peritoneal cavity. It is after these primary modifications that the lateral 
lamine are fused to the vertebral laminz. 

The internal lamina, also named the fibro-intestinal lamina, envelops the 
deep portion of the blastodermic layer or intestinal furrow, the umbilical 
vesicle, and the allantois. It constitutes the fibrous and vascular part of 
these membranes, and carries the vessels to the inner face of the chorion. 

The eaternal or cutaneous lamina is developed in two directions. Above, 
it passes between the muscular lamine and the foetal portion of the external 
layer of the blastoderm, to form the skin of the back. Below, it separates into 
two other laminew, which receive between them the prolongations of the 
muscular lamine, destined to the formation of the intercostal and abdominal 
muscles and the ribs. Of these two secondary lamine, the external forms 
the skin of the trunk, and the internal the parietal layer of the peritoneum, 

The cutaneous lamine also have an extra-feetal prolongation—the fibrous 
layer of the amnion. : 

Fig. 433, 


ret i, 


4 
Nag 


panei 


THE EARLY STAGES OF THE DEVELOPMENT OF THE BODY OF A FOWL. 

A, The first rudiment of the embryo; a, Its cephalic, and 8, its caudal end; c, The 
primitive groove-—s, The embryo further advanced; a, 6, c, As before; d, The 
dorsal laminz as yet developed only in the cephalic region, and not quite united 
in the middle line; ¢, The protovertebra.—c, The letters as before. The dorsal 
lamine have united throughout the greater part of the cephalic region, and are 
beginning to unite in the anterior spinal region.—p, Embryo further advanced, 
the dorsal lamine having united throughout nearly their whole length; the 
ee have increased in number, and the omphalo-mesenteric veins, Ss 
are visible, 


With regard to the middle or mesenteric lamine, they are confounded in 
the mesial line, and in their texture are developed the Wolffian bodies and 
the principal vessels of the trunk. 


THE FQ@TUS. 907 


2. The cephalic lamince always remain adherent to the vertebral lamine, 
and are inflected inwards with them -to form the anterior portion of the 
cephalo-intestinal cavity. The latter is divided into two parts: the pharyn- 
geal and the wsophageal cavities, 

The pharyngeal cavity opens externally by the mouth; it is partially 
closed, lateral; » by the pharyngeal arches. The cesophageal cavity soon 
offers a diverticulum, which shortly after communicates with the pleuro- 
peritoneal cavity; this diverticulum lodges the heart, and is named the 
cardiac cavity. 

The cephalic laminz also form the derm of the cranium, and the fibrous 
layer in which some of the cranial bones are developed. 


Articte II.—Drvetorment or tHE VARIOUS ORGANS OF THE ANIMAL 
Economy. 


DEVELOPMENT OF THE NERVOUS SYSTEM. 


We will at first glance at the development of the nervous centres—the 
brain and spinal cord ; then their peripheral parts, the nerves, 

1. Devetorment or THE Braiy.—We have seen in the preceding 
article how the primitive groove appears, and afterwards the medullary 
cavity. The latter, the first trace of the nervous centres, offers an en- 
largement at each of its extremities; the posterior, or rhomboidal sinus, gives 
off the nerves of the sacro-lumbar plexus; the anterior gives rise to the 
brain. 

The latter enlargement is resolved into three successive dilatations—the 
cells or cerebral vesicles—distinguished as anterior, middle, and posterior. 
They are filled with fluid, and the middle slightly surmounts the other two, 
which gives the three together a triangular shape. 

The vesicles increase irregularly in volume; their walls are gradually 
developed, and form the nervous tissue; while their cavity persists, and 
becomes the ventricles of each portion of the encephalon. Thus, the 
anterior vesicle represents the cerebral hemispheres, the thalami optici, and 
the lateral ventricles. The middle vesicle forms the cerebral crura, the 
corpora quadrigemina, and the aqueduct of Sylvius or middle ventricle. 
The posterior vesicle gives rise to the medulla oblongata, pons Varolii, 
and the fourth ventricle. 

The middle vesicle is that which, at first, increases most rapidly in 
volume; it soon, however, ceases, to allow the anterior cell to become 
developed, when the encephalon assumes its ovoid form, with a predominance 
of the anterior part. 

Towards the end of the first third of intra-uterine life, nearly all the 
parts of the brain are distinct: the two hemispheres have become isolable 
by the development of the septum lucidum; the convolutions appear on their 
surface; the corpora quadrigemina and cerebral crura are distinctly defined. 
It is not until a little later that the cerebellum is distinguishable, as well 
as the pons Varolii, medulla oblongata, corpora restiformia, and corpora 
pyramidalia. . 

2. DrveLopmentT or THE Spina Corp.—The medullary (spinal) canal 
is the first trace of the spinal cord; it occupies the whole length of the 
vertebral column, and its cavity communicates, in front, with the fourth 
ventricle. When the spine is developed, the marrow does not increase 
proportionately in quantity, and appears to ascend in the vertebral canal ; 


908 EMBRYOLOGY. 


it stops about the middle of the sacrum in the equine foetus, but ascends 
higher in the other species. During this apparently ascensional movement 
is developed the filum terminale, and the nerves of the cauda equina. 

The walls of the medullary canal, at first very thin, increase in thickness 
by the appearance of the nervous matter of the cord. Soon they divide 
into two layers: an internal, the epithelium of the central canal; the other 
external, the grey substance of the cord, Gradually the canal contracts, and 
the marrow is seen, with its longitudinal furrows. 

At the end of the first month, the inferior roots are in existence, as well 
as the spinal ganglia ; the latter are developed at the expense of the proto- 
vertebrae, as will be shown presently. The superior roots are formed some 
time afterwards. 

The envelopes of the cerebro-spinal centres are furnished. by the proto- 
vertebral laminw ; they are developed after the sixth week, progressing with 
the growth of the parts they are destined to cover. 

3. DeveLopMENT oF THE NERVES.— 
The development of the nerves is some- 
what obscure. The motor roots seem to 
arise from the cord; but the spinal gan- 
glia are formed separately in the pro- 
tovertebre, and perhaps originate the 
sensitive roots. The nervous ramifica- 
tions begin by elongated ramifying cells, 
which become fused to each other by their 
extremities; the nuclei of the cells lying 
at the periphery becoming the nuclei of 
TRANSVERSE SECTION OF THE EMBRYOOF the white substance of Schwann, the 

A FOWL AT THE BEGINNING OF THE proper nervous tissue being afterwards 
THIRD DAY OF INCUBATION X 90-100. es : & ‘i 
ch, Chorda dorsalis; wwh, Position of a grad ually deposited between the axis- 

> 9. ’ 

thinning, or cavity in the protoverte- cylinder and the envelope. ‘ 

bral mass, dividing it into an anterior The great sympathetic is early seen 
and posterior portion; Ap, Parietal as a nodulated cord. It is probably de- 


lamina; df, Intestinal fibrous lamina, yeloped in the same manner as the other 
dd, Intestinal glandular lamina; dr, 

Primitive intestinal groove; 4, Corneal nerves. 
lamina; mr, Medullary tube—spinal 
cord; m, Muscular lamina; p, Pleuro- 
peritoneal cavity; af, Fold of the 


ce oe wean ee be The principal portion of the organs of 

Duct of the Welfian body. sense belong to the dependencies of the 

nervous system, and are developed with it; 

the other parts belong to the external epithelial lamina, the skin, and the 
germinative lamina. 

1. Visuan Apparatus,—From the anterior cerebral vesicle are given off 
two tubular prolongations, which are directed forward, and terminate by the 
primitive eye-vesicles, traces of the ocular globes. The hollow protrusions 
form the optic nerves; the vesicles furnish the retina and choroid. The 
crystalline lens, vitreous humour, cornea, and sclerotica arise from the 
external blastodermic layer. These modifications take place in the follow- 
ing manner: 

_ The external integument of the foetus passes over the front of the 
primitive ecye-vesicles. Here it shows a slight depression on its outer 
surface, and on its inner face a cellular protrusion (Fig. 435, 1, 0), which, 
becoming developed, surrounds the external depression, completely closes it, 


DEVELOPMENT OF THE ORGANS OF SENSE. 


THE FQTUS. 


909 


and constitutes the commencement of the crystalline lens (Fig. 435, 2, 1), 


The latter, thus formed, presses 
backwards (2), and gives rise to a 
becomes the retina, and the posterior wall the choroid. 


therefore, a dependency of the 
epithelial lamina ; the cells com- 
posing it become elongated into 
fibres in the centre, and are dis- 
posed at its circumference as a 
primary amorphous envelope— 
the crystalline capsule—and after- 
wards as a secondary envelope 
rich in vessels. : 

The portion of the integu- 
ment which is not doubled to 
form the lens envelops the 
globe, and gives rise to the 
sclerotica and cornea; the epi- 
dermis furnishes the epithelium 
of the latter, which becomes 
distinct from the sclerotica in 
the course of the fourth month. 

An aperture—the sclerotic 
clefi—is made at the lower part 
of the fibrous envelope of the 
eye; this is connected with the 
development of the vitreous body : 
a prolongation of the derm—a 

_ Kind of conjunctival bud passing 


on the primitive eye-vesicle, pushes it 
secondary eye-vesicle, whose anterior wall 
The lens is, 


Fig. 435. 


LONGITUDINAL SECTION OF THE EYE OF EMBRYO 
FOWL. 

1, From an embryo at about the 65th hour of incu- 
bation; 2, From an embryo a few hours older; 
3, From an embryo at the 4th day of incubation, 
—h, Corneal lamina; J, Lens in Fig. 1, still con- 
nected with the corneal lamina, and possessing 
a small cavity, o, in its interior (in Figs. 2 and 
3 it is seen detached, but still hollow); 7, Intro- 
verted portion of the primitive optic vesicle, sub- 
sequently becoming the retina; a, Posterior part 
of the optic vesicle, which, according to Remak, 
probably becomes the choroid coat, ciliary pro- 
cesses, and iris, and in Figs, 1 and 2 is still con- 
nected with the brain by the hollow optic nerve ; 
a, Thickening of the corneal lamina around the 
spot from which the lens has detached itself; 
g!, Vitreous body, or humour, 


through this opening, and placing 

itself between the crystalline lens and the anterior wall of the secondary 
eye-vesicle (3, gl), where it is developed and transformed into the vitreous 
body. At first it is encircled by vessels like the lens, but these disappear 
before the termination of gestation. 

The optic nerve is developed in the pedicle uniting the eye-vesicle to the 
anterior cerebral vesicle. The retina is furmed by the inner lamina of the 
secondary eye-vesicle; it extends to the lens in changing its character 
anteriorly. According to Remak, the choroid is constituted by the posterior 
lamina of the eye-vesicle; it advances at first to the lens, and then becomes 
inflected in front to form the iris. The borders of the pupil are attached 
to the vascular envelope of the lens, and this gives rise to the pupillary 
diaphragm, which disappears before birth. 

The motor and protective organs of the eye are gradually developed 
around the globe. The eyelids are small cutaneous folds that appear 
towards the first third of uterine life; they increase, and unite at their 
margin until immediately before, or soon after birth, when they separate. 

The lachrymal gland is a dependency of the epithelial lamina which is 
pushed in above the globe. At first solid, it gradually becomes channeled 
out by cavities, from which arise the excretory ducts. 

2. Auprrory Apparatus.—The internal ear, auditory nerve, and middle 
ear, are developed separately. The labyrinth appears in the shape of a 

vesicle, which is not in direct relation with the posterior cerebral cell ; it is 
-constituted by a depression of the epidermic lamina, the auditory fossa, which 


910 EMBRYOLOGY. 


is gradually developed, and at last become a closed cavity. At this time, 
the wall of the labyrinth is only a simple epithelial membrane ; this is soon 
covered, outwardly, by a vascular connective membrane that separates into 
three layers: an internal, joined to the epithelium to form the membranous 
labyrinth ; an external, that lines the cartilaginous labyrinth; and a 
middle, whose soft, embryonic, connective tissue disappears, and is replaced 
by the perilymph. At the same time that these changes of structure are 
occurring, the vesicular form of the labyrinth is modified, and shows the 
cochlea, semicircular canals, utriculus, and sacculus. 

The middle and ewternal ear arise from the first pharyngeal (branchial) 
cleft, which is never completely closed, while the others disappear. At 
first, then, we find a cavity communicating externally with the pharynx; 

: this cavity contracts, and is separated into 
two portions by a partition that spreads 
across its middle, and which becomes the 
membrana tympani; the internal portion is 
the middle ear and Eustachian tube; the 
external portion is the eaternal auditory 
canal. 

The ossicula auditéis appear in a cartila- 
ginous state towards the third month ; they 
gradually ossify, and have scarcely acquired 
their definitive volume at birth. The ex- 
ternal ear (concha) is developed above the 
integument after the second month. 

3. Otracrory Apparatus.—This com- 
ie paleete: (GRAM) de: SOU mences by two depressions of the epidermic 

WEEKS ENLARGED anour Taree /®mina, analogous to the auditory fossa and 
TMS. that of the lens. These two olfactory fosse 
a, Vesicle of corpora quadrigemina; ®ppear below the ocular vesicles, and become 
b, Vesicle of cerebral hemispheres ; more and more distinct, being margined by 
e, Vesicle of third ventricle; ¢, small projections which increase their depth. 
Vesicle for cerebellum and medulla Behind, they communicate with the pharynx. 
oblongata, e, Auditory vesicle ; ts Thew 2 f th lat ane 

Olfactory fossa; A, Liver; **, - ppearance of the palate separates them 

Caudal extremity. in front from the buccal cavity, and from 

this period the nasal fosse are constituted. 
They are completed by the development of the bones of the face. 

The olfactory bulbs and nerves are primarily hollow, and joined to the 
anterior cerebral cell. The nostrils are formed, in the young foetus, by a 
mass of mucus and epithelium; towards the middle of gestation they are 
open. 

4, Gustatory Apparatus.—See, subsequently, the development of the 
tongue in digestive apparatus. 

5. Tactite Apparatus.—The skin and its dependencies—The skin is 
developed at the expense of the epidermic lamina of the middle layer of 
the blastoderm. The cutaneous lamine, by the modification of their ele- 
ments, form the derma, in which the blood-vessels are very apparent at the 
third month. In the epidermis, the mucous and the horny layers are soon 
distinguished ; in the first, the pigment is visible at the commencement of 
the fifth month in the larger quadrupeds. When the fcetus increases in 
volume, the epidermis exfoliates and its débris floats in the liquor amnii. 

In the third month, the hairs are seen in the foetus of the Mare and Cow; 
they appear at first on the eyebrows, lips, and the joints of the limbs; at 


Fig. 436. 


THE FATUS. 911 


the sixth or seventh month they cover the body. They may be sh 
renewed before birth. They are developed ae feel a of a = 
dermic lamina, which is imbedded in the substance of the derm ; itis 
shaped like a little bottle, and is composed of a mass of cells; in its centre 
these cells are modified and collected together to form a small cone, whose 
hase covers the growing papilla. This cone becomes elongated touches the 
surface of the epidermis, doubles under the effort to push through it, and 
a as its exit, after which it can grow freely. 
e sebaceous and sudoriparous glands are develo i 

towards the middle period ot tacit existence. Pegs anes 

“The horny productions—the claws, hoofs, er —hbegi 
show themselves early. Towards the end : ioe pola ie ate 
foetus of the Cow, there is perceived, at the extremity of each ‘limb, a 
small, pale, translucid, conical tubercle, which is the rudiment of the hoof 
At the commencement of the fourth month, or thereabouts, the hoof. better 
defined, has become firm and opaque, and has assumed a fine yellow tint, At 
mid-term, brown or black patches are manifest if the coronet is provided 
with pigment; it is only about the end of gestation that the hoof towards 
the coronet begins to have the greenish hue peculiar to horn destitute of 
pigment, but the remainder of this production, especially at the inferior 
part, preserves its yellow colour until birth. In Solipeds, the “ chesnuts ” 
are shown at mid-term in the shape of thin brown plates, which are soon 
darker-coloured,”? 

The horn of the hoof is not at first tubular; after birth it is shed and is 
succeeded by a more consistent tubular horn, which had been forming 
beneath it. 


DEVELOPMENT OF THE LOCOMOTORY APPARATUS. 


1. Tun Sxeteron.—We have seen at page 16 how the development and 
growth of the bones takes place; it is therefore needless to recur to this 
subject here; so we will limit ourselves to an examination of the mode of 
development of the principal sections of the skeleton. 

A. DEVELOPMENT OF THE VerTeBRaL Cotumy.—The vertebral column is 
the first portion of the skeleton manifested in the embryo; it is represented 
by the chorda dorsalis, a stalk constituted by a mass of cells situated in the 
jnterior of a transparent sheath. The protovertebre appear on each side of 
the chorda dorsalis; in becoming developed, these parts encircle the latter 
and the medullary canal ; from this results the external theca of the cord, and 
the superior uniting membrane. From this time the vertebral column exists in 
the shape of a membranous axis. 

Soon this membranous spine is segmented to give rise to the vertebre, 
and its various portions gradually become cartilaginous. Each persistent 
vertebra docs not exactly correspond to a protovertcbra ; in_ reality, the 
latter takes a share in the formation of two vertebre, and divides into two 
portions: an inferior, which constitutes the posterior moiety of a permanent 
vertebra; and a superior, which forms the anterior moiety of the persistent 
vertebra immediately behind the preceding and the intervertebral disc. 

The bodies of the vertebra are developed more rapidly than their spinal 
portion : thus, towards the end of the second month, all the vertebral bodies 
are already cartilaginous, while the vertebral lamine are yet membranous. 


1 Colin. ‘Traité de Physiologie Comparée des Animaux. 2nd Edition, Paris, 1873. 


912 EMBRYOLOGY. 


It is only in the third month that ossification begins in the vertebral 
column. The number of osseous nuclei, primary and complementary, is 
not the same in all species; they have been enumerated at page 20. In 
a large number, the spinous process is regarded as the result of the joining 
together of the two moieties of the vertebral arch; in the Sheep, on the 
contrary, the spinous process forms a nucleus altogether independent of the 
vertebral arches. Thomas has noted this disposition, and he considers it 


Fig. 437, 
Fig. 438, 


DIAGRAM SHOWING THE POSITION OF THE 


DIAGRAM SHOWING THE ATTENUATION OF CHORDA DORSALIS IN THE BODY OF THE 
THE CHORDA DORSALIS IN THE MIDDLE OF VERTEBRA, AND THE FORMATION OF THE 
THE BODIES OF THE VERTEBRA, WHILST NEURAL ARCHES. 


PRESERVING ITS ORIGINAL DIAMETER IN ch, Chorda dorsalis; cv, Body of the verte- 


THE INTERVERTEBRAL SPACES. bra; u, Neural arch, or neurapophysis ; 
ch, Chorda dorsalis; v, Body of vertebra; c, Rib; pr, Transverse process. 
Ui, Intervertebral spaces. 


as peculiar to animals whose anterior dorsal vertebree are furnished with 4 
long spinous process. 

During ossification, the chorda dorsalis disappears, except between the 
vertebre, where it is developed to form the intervertebral substance or 
discs. 

B. Devetopment or THE Cranium anD Facz.—The encephalon is en- 
veloped by a membrane formed at the expense of the protovertebral lamina. 
This cranial membrane becomes partly cartilaginous, partly fibrous; the 
cartilage exists at the base of the cranium, and seems to prolong the bodies 
of the vertebre into this region; indeed it is known that the skull may be 
resolved into four portions, each corresponding to a vertebra, The cartilage 
is insensibly transformed into bone; while the fibrous part, composing the 
roof of the skull and its lateral walls, passes directly into an osseous state. 

The bones of the face are developed at the expense of the pharyngeal 
arches. This designation is given to four laminew (or lamelle) which spring 
from the anterior extremity of the chorda dorsalis, and double downward and 
inward to join those of the opposite side. They are also named the branchial 
and visceral arches, and the spaces between them are called the pharyngeal 
clefts. The upper jaw, mouth, nasal cavities: i.e. the nasal, maxillary, and 
palate bones, are furnished by the first arch. Meckel’s cartilage, which arises 
from the handle of the malleus to pass towards the inferior maxilla, is also a 
dependency of this branchial arch ; it disappears towerds the sixth or seventh 
month. It is to be remarked that, at the commencement, the mouth com- 
municates with the nasal cavities; the palate is developed in two moieties 


THE FQTUS. 913 


which advance towards each other, though they remain a long time apart; 
so that at this time the young animal really has a hare-lip. The second 


pharyngeal arch forms the stapes, the pyramidal process of the temporal 
bone, styloid arch, and 


branch of the hyoid. The Fig. 439, 
third develops the hyoid 
with its cornua; while the 
fourth arch only constitutes 
the soft parts of the neck, 

C. DEVELOPMENT OF THE 
Txuorax.—The ribs are de- 
pendencies of the proto- 
vertebral lamina, which 
curve towards the lower 
face of the vertebral column. 
The true ribs are most 
rapidly developed, and 
before attaining the middle 
line are united by their 
internal extremity, and 
form a moiety of the ster- 
num. A fissure separates 
the costal arches of the 
right side from those of mm, The malleus; #, Incus; zy, The tympanic; H, The 
the left; this gradually hyoid; sq, The squamosal; pd, Pterygoid; p/, Palatine; 
contracts, and finally dis- 1, Lachrymal; pms, Premaxilla; ‘N, Nasal sac; Eu, 
appears, and the sternum Eustachian tube. 
is then formed. The ribs 
are, after the petrous bone, the parts of the skeleton which are most 
promptly ossified, ossification commencing in the middle ribs. 

The costal arches do not belong exclusively to the dorsal vertebra, but 
have a tendency to form along the whole length of the spine; and it is not 
rare to see, attached to the lumbar vertebra, a small cartilaginous nucleus 
which is soon lost in the texture of the abdominal walls. This nucleus 
assumes large dimensions on the last cervical vertebre of birds. 

The form of the thorax varies with the species; in some it is circular, 
in others it is flattened laterally; and in all cases it is less developed in the 
foetus and young avimal than in the adult. It is in the latter that the 
thoracic cavity presents, proportionately, its greatest dimensions. 

D. Devetorment or THE Liwes.—The limbs do not show themselves 
until after the formation of the spinal column, the pharyngeal arches, and 
the thoracic parietes. They appear as four little prolongations from the 
thorax and pelvis, and are slightly enlarged at their origin and constricted 
in the middle. Their free extremity is flattened, and either divides or 
remains single, as the animal has one or more apparent digits. It is in 
these prolongations that the cartilaginous rays are developed, which, at a 
later period, become the bones of the limbs. For the manner in which ossi- 
fication is carried on in each bone, reference must be made to Articles IV. 

., pages 71 and 91. 
an The muscles are developed around the bones when these 
have become perfectly distinct. They may be divided into four groups: the 
vertebral muscles, which come from the muscular lamine of the protovertebree ; 
the visceral muscles—thoracic and abdominal cavities, neck and jaw—having 


THE HEAD OF A FETAL LAMB DISSECTED TO SHOW 
MECKEL’S CARTILAGE. 


914 EMBRYOLOGY. 


the same origin; the cutaneous muscles, which are developed at the expense 
of the cutaneous lamine of the middle layer of the blastoderm; and the 
muscles of the limbs, whose development is not yet perfectly known. 

Tt was at one time believed that the muscular fibres were formed by the 
junction, end to end, of several elongated cells; but it is now known that 
they are constituted by a single cell which lengthens, and whose nuclei 
multiply and lie at the surface, while its contents are transformed into a 


substance which offers the characteristics of contractile tissue. 


Fig. 440. 


DIAGRAM OF THE FORMATION OF THE VEN 
OMPHALO-MESENTERICA AND UMBILICALES. 


1, At the time of the first appearance of the um- 
bilicales, and the commencement of the om- 
phalo-mesenterice ; 2, At the time of the first 
appearance of the branches to and from the 
liver, and the diminution of the omphalo- 
mesenteric vessels; 3, 4, At the period of com- 
plete fetal circulation in 1, Omphalo-mesenteric 
trunk; in 2, 3, Remains of it; in 4, Vein of the 
yolk sac alone: om’, Right, and om’, Left vena 
omphalo-mesenterice ; u, Trunk of the um- 
bilical vein; wu’, Right, and w”, Left vena une- 
bilicalis; de, Ductus Cuvieri; j, Jugularis; c, 
Cardinalis; 7, Liver; ha, hepatica advehentes ; 
hr, Hepatic revehentes; m, Mesenterice; da, 
Ductus venosus Arantii; ci, Cava inferior; p, 
Vena porte; 7, Lienalis; m, Mesenterica su- 
perior, 


The sar- 
colemma is formed after the fibre, 
by a modification of the con- 
nective tissue surrounding it. 


DEVELOPMENT OF THE CIRCULATORY 
APPARATUS. 


During the first days which 
follow the appearance of the em- 
bryo in the substance of the blas- 
todermic layer, there is no trace 
of vessels in the area germinativa. 
It is not long, however, before the 
heart and some blood-vessels are 
seen in the middle layer, the 
vessels extending to the surface 
of the umbilical vesicle, which 
gradually shows itself. While 
the contents of the vitelline vesicle 
are being absorbed by the embryo, 
the heart is being completed, the 
vessels are developing, the allan- 
tois is formed, and the placental 
circulation, which continues until 
birth, is established. From this 
time the circulatory apparatus has 
acquired its definitive disposition. 

1. APPEARANCE OF THE Heart. 
—CircunaTion In THE UMBILICAL 
VexstcLe.— The pleuro-peritoneal 
cavity of the embryo presents, 
anteriorly, a diverticulum, the car- 
diac cavity, in the interior of which 
the heart is developed. This 
organ appears at first as a small 
mass of cells, the innermost of 
which become separated from each 
other to create a cavity and con- 
stitute the blood-globules. As soon 
as it shows itself, the heart con- 
tracts and dilates alternately, the 
movements being very slow, though 
they gradually become quicker. 
Towards the twelfth day, the 


central organ of the circulation has the form of a contractile cylindrical tube. 


THE FOETUS. 915 


From its anterior part spring two branches, the aortic arches (arcus aorte), 
which are directed towards the head of the embryo, and are afterwards in- 
flected downwards and backwards. They join together to constitute the single 
aorta, which, in its turn, divides into two trunks, the arterie vertebralis or 
primitive aorte, These vessels pass along the lower surface of the embryo, 
parallel to each other, and furnish during their course four or five divisions, 
the omphalo-mesenteric arteries, which ramify in the area germinativa, and 
open into a limitary vein named the sinus (or vena) terminalis. From the 
network of the area and the sinus arise two vessels, the vencee omphalo- 
mesenterice, which enter the posterior extremity of the heart. 

The circulation in the umbilical vesicle is somewhat ephemeral in 
several species, and it has been already stated that the vesicle is atrophied at 
an early period of foetal life. In birds it is most extensive ; and its presence 
may be noted in the Carnivora during the whole term of uterine existence. 

2. DEVELOPMENT OF THE HEART AND VESSELS.— PLACENTAL CIRCULATION.— 
The heart which, until now, was a cylindrical tube, is considerably modified 
before it attains its complete development. In its different phases, it 
successively offers all the forms known to exist in vertebrate animals. The 
first change consists in an inflexion; the tube curves in an § manner, so 


HEART OF THE EMBRYO OF THE SAME, SEEN FROM BEHIND. 
RABBIT, SEEN FROM, BEFORE. a, Vene omphalo-mesenterice; 4d, 
ta, Truncus arteriosus; J, Left ven- Right, auricle ; ¢, Bulbus seus ‘ f 
tricle; +, Right ventricle; u, Au- The six aortic arches; c, Atrium ; 
ticle; v, Venous sinus. b, Auricule 


that its inferior part becomes superior ; it then dilates at three ar 
the anterior and superior dilatation situated at. the origin © - e 
aorta is named the aortic bulb (bulbus aorte) ; the middle sang os he 
ventricular cavity ; and the posterior dilatation, the auricular cavity. a er : 
passage is the name given to the constriction between san auric sh 

ventricle, which at this time are single. They do not remain long 50, ea 
ever. The ventricular cavity is the first to be divided ae ys compart- 
ments, and the division is marked externally by a groove whic rae oF 
the surface of the heart of the Ovine embryo towards the plage ay, a 

on the twenty-fifth in the Equine foetus. This groove aa 0 - a er 
ventricular septum which insensibly rises from the bottom o! the sue ne 2 
when it reaches the auricles it concurs 12 forming the sails or 
openings. The margins of these openings are provided with a he slig y 
salient lip, which afterwards, in developing, originates the mitral an ie : 
valves. The heart has now three cavities: two ventricles and an auricle, bu 

ina brief period the latter is doubled, and the compartments are then four in 
number. Externally, there is observed a depression which shows the division 


916 EMBRYOLOGY. 


in the auricles; at a point corresponding to it, a septum is developed in 

their interior which remains incomplete during the whole of foetal life, being 

perforated by the foramen of 

Fig. 443, Botal. With regard to the 

aortic bulb, it contracts and 

divides into two vessels, the 
aorta and pulmonary artery. 

The arteries are developed 
partly at the expense of the 
vessels of the primary circula- 
tion, and partly in the vascular 
lamina of the embryo. The 
heart, when it was only a simple 
cylindrical tube, presented at 
its anterior extremity two aortic 
arches, which curved backwards 
and united to form the single 
aorta, then the vertebral or 
common aorte. The aortic 
arches are situated at the inner 
face of the two first pharyngeal 
arches; afterwards more are 
developed, which are placed 
within the other pairs of arches, 
until the number is increased to 
five, though they never all exist 
atthe same time. Some atrophy, 
HEART OF AN EQUINE F@TUS. THE RIGHT AURICLE while othersare being developed: 

AND POSTERIOR VENA CAVA HAVE BEEN OPENED the two first entirely disappear ; 
TO SHOW THE FORAMEN OF BOTAL. : ; 

: : : ' the third form the carotids: the 

s, oe ee oe ventricles 2, inte a fourth the axillary arteries and 

piv oo ie Pp ee EE Ne Ble eral of EHS aorta ; the fifth 

atrophies‘ on the right, and on 

the left originates the pulmonary artery, the ductus arteriosus, and the aorta. 

The latter is continued along the spine by the fusion of the two primitive 

aorte ; they present, at their posterior extremity, the pelvic vessels, which 

are very small, and the umbilical arteries, which are, on the contrary, 

remarkable for their volume. 

The peripheral arteries arise, independently of the central vessels, on the 
interior of the vascular lamina. They appear in the form of solid cellular 
branches, which are hollowed in the centre by a cavity in which the cells 
become free. In proportion as these new vessels are developed, the omphalo- 
mesenteric vessels disappear, until at last there only remain one or two ducts 
that pass to the umbilical vesicle.’ 

The umbilical veins are developed immediately after the formation of the 
omphalo-mesenteric veins ; they enter the common trunk of the latter, and 
when its ramifications diminish in volume, the umbilical veins increase 
rapidly ; when the liver is formed around them, they throw into it branches, 
which are the rudiments of the hepatic network. Between the hepatic and 
subhepatic veins, the umbilical vein communicates with the vena cava by 
the ductus venosus of Aranzi, which, according to M. Colin, does not exist in 
the foetus of Solipeds in the last moiety of uterine life. 

The veins of the embryo form four principal trunks at first: two anterior, 


THE FQTUS. 917 


the anterior cardinal veins ; and two posterior, the posterior cardinal veins. 
The veins of the same side unite in twos, from which regult the Cuvierian 
ducts ; these open transversely into the omphalo-mesenteric trunk close to 
the auricular cavity. 

: The anterior cardinal veins issue from the cranium; they form the 
jugular veins, and communicate by an anastomosis that extends transversely 


Fig. 444, 


~ 


PLAN OF THE AORTA AND ITS ARCHES AT AN EARLY PERIOD. 


1, Truncus arteriosus, with one pair of aortic arches, and dotted lines indicating the 
position of the second and third pairs. 2, The same, with four pairs of aortic 
arches, and indications of the fifth. 3, The same, with the three posterior pairs 
of aortic arches, from which the permanent vessels of the embryo are developed, 
with dotted outlines showing the position of the two (now) obliterated anterior 
arches. 4, Permanent arteri2l trunks in their primitive form, the obliterated 
portions still shown in dotted outline, 1-5, Primitive aortic arches.—a, Aorta; p, 
Pulmonary artery; p’, p”, Branches to the lungs; aw’, Root of thoracic aorta 
(ad) on left side; aw, Obliterated root springing from right side; s”, s', Subclavian 
artery; v, Vertebral; ax, Axillary; c, Common carotid; c’, External carotid; 
ce”, Internal carotid. 


from left to right. Below this anastomosis, the left vein gradually atrophies, 
as does the Cuvierian duct of the same side; but the canal on the right side 
increases, and becomes the anterior vena cava. 

The posterior vena cava appears behind the liver towards the fifth month; it 
receives the veins of the kidneys and Wolffian bodies, and, behind, it anasto- 
moses with the cardinal veins. The latter disappear in their middle portion, 
and are replaced by the vertebral veins, the right of which forms the vena 
azygos. ‘Phere only remain the two extremities of the cardinal veins; the 
anterior enters the Cuvierian duct, and the posterior constitutes the hypo- 
gastric and crural veins. From this disposition, it will be seen that at first 
the venous system of the foetus is perfectly symmetrical, but that in the adult 
animal it becomes asymmetrical. ; ; 

Tn consequence ofthese successive developments, the placental circulation 
ig instituted, and continues the same until the termination of intra-uterine life. 
The heart is always the organ that propels the blood, and this passes into the 
arteries, reaches the umbilical arteries, and is carried to the placenta. There 
it is renewed, becomes arterial through contact with the maternal blood, and 
is returned by the umbilical veins. In the substance of the liver it is mixed 
with the venous blood of the intestines and posterior extremities, through 
the medium of the ductus venosus, and at last arrives at the right auricle, 
then the right ventricle, from which it is propelled by a contraction. Instead 
of going to the lungs, which do not act as respiratory organs, the blood, 
being pressed by the contraction of the right ventricle, passes into the aorta 


61 


918 EMBRYOLOGY. 


Fig. 445. by the ductus arteriosus. To sum up, the foetus never 
receives pure arterial blood into its organs, this being 
always mingled with venous blood, the mixture taking 
place at several points: 1, By the foramen of Botal ; 2, 
Jn the aorta by the ductus arteriosus; 3, In the liver 
by the ductus venosus. The head and neck are the 
parts which receive the purest arterial blood, a fact 
which explains the predominance of the anterior over 
the posterior portion of the body of the foetus. 

At birth, the conditions of existence being suddenly 
changed, marked modifications take place in the cir- 
culatory apparatus. The lungs become the organs of 
respiration, and rapidly increase in capacity; the pul- 
monary artery dilates to give passage to the blood that 
flows to them; while the ductus arteriosus is obliterated, 
in order to isolate the arterial from the venous blood. 
This separation of the two fluids also takes place in the 
liver by the atrophy of the ductus venosus, and in the 
heart by the occlusion of the foramen of Botal; though, 
according to M. Goubaux, that orifice frequently remains 
open in young animals. Its persistence has also been 
noted in the human adult. Notwithstanding the pre- 
sence of this foramen, the circulation cannot be much 
disturbed; as when the heart contracts, the auricles 
become isolated by the constricting of the orifice and 
the raising of a valve. 


. 


DIAGRAM OF THE CIR- 
CULATION AT THE 


COMMENCEMENT OF 

EVELOP 
fe ae ie D: OPMENT OF THE RESPIRATORY APPARATUS. 
THE PLACENTA : Observers are not unanimous as to the develop- 


SEEN FROM THE 
FRONT. 


ment of the lungs. According to Reichert and Bischoff, 

re See ee they arise from two small solid cellular masses lying on 
cetving all Gheceys- the surface of the anterior portion of the intestinal 
temic veins;b, Right canal, These become channeled out into numerous 
auricle; 6’, Left ramifying cavities (by the deliquescence or fusion of the 
ee re , Ve internal cells), which communicate with the trachea. 
ventricles a Hulbus Costa states that they commence by a median, bud-like, 
aorticus,subdividing hollow process that opens into the cesophagus. The 
into, ¢, ¢’, e", Bran- walls of the communicating aperture elongate consider- 
peed mame tick » ably, and at a later period form the trachea and larynx; 
famed by their con. While the hollow bud divides into two pyriform sacs, 
fluence; g, g', Vena ach of which becomes broken up into a multitude of 
azygos superior; /, subdivisions to constitute the pulmonary lobes, with their 
h’, Confluence of the vesicles and infundibula. 
po 9 ronan The trachea is completed by the development of the 
inferior; , k', Vena Cartilaginous rings in the tube that binds the lungs to 
azygos inferior; m, the cesophagus. They appear at the commencement of 
Descending | aorta; the third month. 
fd aaa 2 The a is developed in the same manner at the 
it; 6, o', Umbilical Pharyngeal opening ; it is always somewhat undefined 
veins; g, Omphalo- 
mesenteric vein; 7, Omphalo-mesenteric artery distributed on the walls of the vitelline 
vesicle, ¢; v, Ductus venosus; y, Vitelline duct; 2, Chorion, 


THE FATUS. 


919 


during youth, and its definitive volume is not acquired until the period of 


puberty. 


The thymus gland appears asa process of the respiratory mucous mem- 


brane; it seems to be formed at the 
larynx, and gradually descends along 
the trachea to the entrance of the 
thorax. 


DEVELOPMENT OF THE DIGESTIVE 
APPARATUS. 


In this paragraph, the develop- 
ment of the alimentary canal will be 
first studied, then that of the organs 
annexed to it. 

A. ALIMENTARY Canat.—We have 
seen how the embryo, in becoming 


Fig. 446. 


FIRST APPEARANCE OF THE LUNGS ; 
a, In a Fowl at four days; 6, At six days; ¢, 
Termination of bronchus in a very young 
Pig. 


incurvated, divides the blastodermic vesicle into two parts which com- 


municate by a large pedicle. 


The external portion is the umbilical vesicle ; 


the pedicle is the omphalo-mesenteric duct, and the inner part the intestinal 


cavity. 


The latter may be decomposed into three portions: the anterior intestine, 


Fig. 447. 


EMBRYO OF DOG, TWENTY-FIVE DAYS AFTER LAST COPULATION. 


u, a, Nostrils; , , Eyes; ¢, ¢ 


First visceral arches, forming the lower jaw; d, d, 


Second visceral arches; ¢, Right auricle; f, Left auricle; g, Right ventricle; 


h, Left ventricle; ?, Aortic bulb; 2, 
seen the divided 
communicating with ili 
lantois; g, g, Anterior extremities ; 


k, Liver, between the two lobes of which is 
orifice of the omphalo-mesenteric vein ; 1, Stomach ; m, Intestine, 
the umbilical vesicle, n,m; ¥, 0, Vorp 
1, , Posterior extremities. 


Corpora Wolffiana; p, Al- 


ich forms the pharynx and cesophagus ; the posterior intestine, that gives 
Lee dhe aera Be the middle intestine, which becomes the stomach 


and intestines. 


920 EMBRYOLOGY. 


The middle intestine appears at first as a uniform cylindrical tube, whose 
diameter’is afterwards modified to constitute the organs comprised between 
the cesophagus and rectum. _ 

1. Mouth—It begins by a depression limited by the maxillary buds; 
this blind pouch gradually enlarges inwardly, and proceeds to meet the 
pharynx, from which it is only separated, at a certain period, by a thin 
membrane; this is at last absorbed, and the two cavities then communicate, 
Until the third month, the mouth is confounded with the nasal cavities ; at 
this time the palate appears, and eventually isolates them. 

2. Tongue.—Appearing at first as a small prominence from the maxillary 
buds, the tongue is completed by the addition to it of a bud from the second 
branchial arch. Its epithelium and glands come from the external blas- 
todermic lamina; they are developed in the third and fourth months. 

3. Pharynx and CHsophagus—These two organs become enlarged and 
elongated as the foetus grows. The cesophagus communicates at first with the 
trachea ; but it slowly closes, and finally separates completely from that canal. 

4. Stomach.—This is formed by the dilatation of the anterior part of the 
iniddle intestine; this dilatation is fusiform, and its largest axis lon- 
gitudinal ; it soon incurvates, and its longest axis is then transversal. In 
Ruminants, the stomach is at its first appearance simple; but before long it 
shows grooves on its surface, and in its interior septa, as in the normal 
state. During foetal life this organ is small; but after birth, when solid 
food begins to be taken, it angments rapidly in volume. During lactation 
in Ruminants, there is remarked a predominance of the fourth over the 
other gastric compartments; but immediately the young animal commences 
to consume fibrous aliment, the rumen quickly increases in size, and it is 
not long before it becomes the most considerable division. 

5. Intestines—The intestinal tube is primarily of a uniform calibre, 
though in a short time there can be distinguished the various regions of 
which it is composed. According to A. Baer, the cecum is early seen in 
hoofed animals, and is situated in the vicinity of the omphalo-mesenteric 
duct. This duct detaches itself from the extremity of an intestinal loop, 
which is drawn towards the umbilical ring; when the latter is becoming 
atrophied and progressing towards complete obliteration, this loop re-ascends 
into the abdominal cavity. 

The intestines are smooth on their inner face during the first two 
months; but during the third they show their villosities and the glands of 
Lieberkiihn. The Brunnerian and solitary glands are a little later in 
showing themselves. 

6. Rectum—This is derived from the posterior intestine, and is de- 
veloped like the other portions. 

7. Anus.—Towards the caudal extremity of the foetus is observed a 
depression analogous to the buccal cul-de-sac. This gradually deepens, and 
is joined to the rectum and genito-urinary organs. Later, it is separated 
from the latter, and then belongs exclusively to the alimentary canal. 

B, Anvexes or THE ALIMENTARY Canat.—These are the salivary glands, 
teeth, liver, pancreas, and spleen. 

1. Salivary glands.—These are developed in a solid cellular bud, which 
is related to the epithelium at the commencement of the digestive apparatus. 
This bud increases, and at the same time is hollowed into glandular pouches. 
The submaxillary gland is the first to appear; according to Bischoff, it is 
entirely formed in the foetus of a Cow only an inch in length. The parotid 
gland is the last to be formed. 


THE FQTUS. 921 


2. Teeth These organs are developed in the interior of a cavity, 
named the dental follicle or sac, by means of the elements of three germs: 
one belonging to the ivory, another to the enamel, and a third to the 
cementum. 

Follicle-——The dental follicle is an oval cavity with walls composed of 
two layers: the external is fibrous and complete; the internal, soft or. 
gelatinous, is allied at the bottom to the wory germ. The latter is a 
prominence which is detached from the bottom of the follicle, and has the 
exact shape of the tooth. Its structure comprises, in the centre, delicate 
connective tissue provided with vessels and nerves, and on the surface a 
layer of elongated cells. At the summit of the follicle, facing the ivory 
germ, is the enamel germ; it is exactly applied to the dental pulp which it 
invests like a cap, and is composed of a small mass of mucous connective 
tissue covered by a layer of cylindrical cells, joined to the buccal epithelium 
by the gubernaculum dentis. The cementum organ manifestly exists in the 
Foal, according to M. Magitot. The base of the ivory germ has been found, 
but it disappears rapidly after having performed its function. 

How are the different parts of the dental follicle developed? On the 
free borders of the maxille the epithelium of the buccal mucous membrane 
forms an elongated eminence—the dental ridge. Below this ridge, the 
epithelium constitutes a bud which develops in size, and is sunk in the 
mucous membrane: this is the enamel germ; it has a layer of cylindrical 
cells on its deep surface, and in its centre are round cells. After a certain 
time, it is only joined to the epithelium by a very thin line of cells—the 
gubernaculum dentis. While this enamel germ grows downwards, it covers, 
by its base, a connective bud which rises from the mucous derma. The 
two buds are reciprocally adapted to each other, and around them the 
connective tissue condenses, and gives rise to the walls of the follicle. It 
will therefore be seen, that the enamel organ is a dependency of the 
epithelium, and the ivory organ a production of the mucous derma. 

Formation of the ivory, enamel, and cementum.—The ivory and enamel 
are developed by the modification of the elements situated at the surface of 
their germ. 

It has been shown that the germ of the ivory, or dental pulp, had 
exactly the form of the future tooth ; consequently the ivory which arises 
from its periphery offers the shape of this tooth. The ivory (dentine) is 
constituted by the cells of the germ, which elongate, send out prolongations 
—the dental fibres—that ramify and anastomose, and by an intercellular 
substance which is impregnated with calcareous matter, 1s moulded around 
these fibres, and forms the dental canaliculi. ; : 

The enamel is derived from the deep cells of its germ, which are 
elongated and prism-shaped, and are calcified in becoming applied to the 
ce of the ivory. ; 
ar he armenia de developed at the expense of the walls of the follicle, 

according to the mode of ossification of the connective tissue. — 

Eruption.—As the ivory is formed, the tooth increases in length and 
presses the enamel germ upwards; the latter, constantly compressed, 
becomes atrophied, and finally disappears when the tooth has reached the 
summit of the follicle. In the same way the young organ pierces the 
dental follicle and gum, and makes its eruption externally. 

Such is the mode of development of the caducous teeth, and the per- 
manent ones are formed in the same manner. There is seen, during the 
development of the enamel germ of the temporary tooth, a bud detaching 


922 EMBRYOLOGY. 


itself from this germ, and passing backward to serve, at a later period, in 

forming the persistent tooth. 

3. The liver—This gland commences to be developed very early in all 
the species. It appears on the surface of the duodenum in the form of two 
or more buds, according to the number of lobules in the adult liver. To 

these external buds are correspond- 

Fig, 448. ing internal ones, arising from the 

intestinal epithelium. The first 

enlarge and envelope the omphalo- 

mesenteric vein; the second ramify 

in their interior, and form the 
system of biliary canals. 

The liver grows rapidiy, and, 
towards the third month, almost 
entirely fills the abdominal cavity ; 
= at a later period its growth is less 
ORIGIN OF THE LIVER FROM THE INTestrnaL Marked, although at birth it is yet’ 

WALL IN THE EMBRYO OF THE FOWL, oN THE proportionally larger than in adult 
FOURTH DAY OF INCUBATION. life. 

a, Heart ; 6, Intestine; c, Everted portion, giving 4, Pancreas.— The pancreas 
origin to liver; d, Liver; e, Portion of vitel- first appear, like the salivar 
line vesicle. Pear, ry 

glands, in the form of a solid 
cellular bud, which afterwards is channeled into ramescent cavities. 

5. Spleen.—According to Bischoff, this body is developed, during the 
second month, on the large curvature of the stomach. Arnold states that it 
is formed at the same time as the liver, in a strip extending from the 
stomach to the duodenum. It subsequently separates from the pancreas and 

becomes fixed to the stomach, where its elements 
Fig. 449. assume the character of spleen tissue. 


DEVELOPMENT OF THE GENITO-URINARY APPARATUS. 


The development of the genital is related to that 
of the urinary organs, as the apparatus they form 
have some parts in common. 
; Immediately after the formation of the intes- 
tines, the genito-urinary organs are supplied by the 
Wolffian bodies. These, also named the primordial 
kidneys and bodies of Oken, are glandular in structure, 
and extend in front of the vertebral column from the 
heart to the pelvis. They are composed of small 
transverse canals, filled with a whitish fluid, which 
enter 2 common excretory duct that lies parallel to 
the spine, and opens inferiorly into that portion of 
state or THE cenrro- the allantois that becomes the bladder. The Wolf- 
URINARY APPARATUS IN fian bodies are placed behind the peritoneum, and 
ae a EMBRYO OF are attached by two serous folds: an anterior, the 
Pee ova wreltiaae 1b diaphragmatic ligament, and a posterior, the lumbar 
They exoretory ducts: ligament of the corpora Wolfiana. The organs furnish 
c, Kidneys; d, Ureter; a liquid analogous to the urine; though it is not 
¢, 2, Testes, long before their secretion undergoes great modi- 
fications ; indeed, these bodies soon atrophy, and dis- 
appear more or less rapidly, according to species. One portion serves for 


THE FQ@TUS. 923 


the development of the genital organs; the other gives rise to organs whose 

signification is unknown—such as the organ of Rosenmiiller, which is very 

OTE in the Mare, and the canals of Gaertner, visible in the Cow (Mare, 
nd Pig). 

A. Urinary Oraans.—We have seen above how the allantois is derived 
from the terminal portion of the intestine; it has now to be stated that the 
bladder is derived from the allantois. This reservoir is the result of the 
dilatation of the abdominal portion of the allantois. During fotal life, the 
bladder is extended by the urachus to the umbilical ring; but after birth 
the urachus is obliterated, and the bladder is withdrawn into the pelvic 
cavity. Hereafter we shall study the urethra. 

The kidneys appear a long time after the Wolffian bodies, in the shape of 
two blind pouches constituted by a pushing back of the upper wall of the 
small vesicle of the allantois. These little culs-de-sac ramify, and are 
afterwards replaced by solid buds, in whose interior are developed the 
uriniferous canals and Malpighian bodies. According to certain observers, 
the kidneys subsequently communicate with the ureters, which are developed 
separately in the middle layer of the blastoderm. 

(In the female, the Wolffian bodies do not entirely disappear; the 
canals of Gaertner and the bodies of Rosenmiiller, situated in the broad 
ligaments, between the ovaries and Fallopian tubes, are their remains in 
adult life; traces of them are also found in the male, near the head of the 
epididymis, where they constitute the vas aberrans of the testicles. The 
suprarenal capsules are very large in the Equine foetus, being nearly one 
half the size of the kidneys.) 

B. Gentrrat Orcans.—The genital apparatus of the male and female are 
at first very much alike ; indeed, during a certain period it is impossible to 
distinguish the sexes; so that some authorities have proposed to term this 
period the “indifferent state of the genital organs.” Later, the sexes are 
defined ; and this period of development may be studied in the internal and 
external organs. 

iL: Indifferent state of the internal genital organs.—Towards the sixth 
week, there is observed on the lower face, and near the inner border of the 
Wolffian bodies, a little white cord, which increases in volume and maintains 
almost the same position. This is the genital gland, which is attached to 
the Wolffian body by serous folds, and is formed by a mass of young cells 
sustained by an enveloping membrane. ; 

The development of this gland is accompanied by the formation of the 
genital or Miiller’s duct, which is seen to the inside, and in front of, the 
Wolffian duct. Miiller’s duct is at first a solid cellular column, which 
afterwards becomes a canal; it terminates above in a blind pouch, and 
opens, below, into the bladder, near the Wolffian duct. 

Development of the internal genital organs of the male—These result from 
modifications of the genital gland and Miiller’s duct. The testicle arises 
from the gland, which shortens and widens a little, while its tissue is 
transformed into seminiferous canaliculi. The head (globus major) of the 
epididymis is formed by the middle portion of the Wolffian body; the tail 
(or globus minor), vas deferens, and ejaculatory duct, are derived from the 
Wolffian duct. Lastly, the vesiculce seminales and the origin of the urethra 
are formed by the posterior extremity of Miiller’s ducts, which join and 
open into the uro-genital sinus, as the very short canal is named which 
communicates between the bladder and cloaca. The developed testicle 
remains in the abdominal cavity, or descends through the inguinal canal 


924 EMBRYULOGY. 


into the scrotum. The mechanism of this descent has been already 
explained. . . ; 

(It may be only necessary here to state, that in the Equine species the 
testicles do not usually descend into the scrotum until some time after 
birth—about six months; while in other animals they reach that sac during 
foetal life. In the Bovine species, the testes are in the scrotum about the 
twentieth week of gestation, and in the Sheep and Goat about the fifteenth 
week; indced, it has been observed that in all Ruminants their descent is 
effected before the skin is covered with hair. In the Carnivora, they are 
usually in the scrotum a few days before birth.) 

Development of the internal genital organs of the female.—The ovary is 
derived from the genital gland, whose anatomical elements are so disposed 
as to form the stroma, Graafian follicles, and ovules. The Fallopian tube 
and its pavilion are formed by the anterior part of Miiller’s duct, whose 
extremity shows a small linear orifice. The uterus and vagina arise from 
the posterior part of Miiller’s ducts. These lie beside each other, and end 
by joining behind to constitute a single canal; this fusion giving origin 
to the body of the uterus and the vagina. 

The two diverging portions of the ducts comprised between the point of 
junction and the Fallopian tubes, compose the cornua of the uterus. 

The uterus and vagina are at first placed end to end, without any 
apparent separation; but towards the sixth month the neck of the uterus 
commences to be defined. 

2. Indifferent state of the external genital organs.—The intestine is 
terminated by the cloaca, a cavity into which the digestive canal and 
bladder open by the uro-genital sinus. This confusion quickly ceases by 
the development of a transverse septum that divides the cloaca into two 
compartments: the anal opening, and the wro-genital canal. At the inferior 
end of the latter appears the genital tubercle, a rudiment of the penis or 
clitoris, and which is surrounded by cutaneous folds—the genital folds. 
This tubercle increases in volume, and has a furrow passing from behind to 
before. Up to this moment it is impossible to distinguish the sexes. 

Development of the external genital organs of the male-——The male sex is 
marked by the rapid development of the genital tubercle, which becomes 
the penis, the extremity of which enlarges to constitute the glans. The 
genital furrow closes posteriorly, and forms the urethra. The folds draw 
round to each other below the penis, unite in the middle line, and thus 
produce the scrotum. Owing to these modifications, the digestive ap- 
paratus is completely separated from the genito-urinary organs, and the 
urethral canal is connected with the bladder and the excretory ducts of the 
testicle. 

Development of the external genital organs of the female—The indifferent 
state of the genital organs is readily succeeded by the feminine type. The 
uro-genital sinus forms the vulvular cavity or vestibulum of the vagina, 
which is so marked in the lower animals. The genital tubercle becomes 
the clitoris; the genital furrow closes at a certain part to constitute the 
perineum; while the genital folds form the labia of the vulva. The 


mamme, dependencies of the generative organs, appear after the first month 
of uterine life. 


CHAPTER IV. 
THE OVA OF BIRDS. 


Ir has been, stated, with regard to the ovaries of birds, that the ovules 
compose nearly the whole mass of these organs. When it leaves the ovary, 
the ovum presents the same parts as that of mammals, only differing in 
volume, which is enormous in birds. It is in passing through the oviduct 
that it is covered with a thick layer of albumen and enveloped in a white 
membrane, and then a shell, to compose what is usually known as an egq. 
It is therefore composed of the ovulum and accessory parts (Fig. 450). 

Ovutum.—There is found in the ovulum: 1, A vitelline membrane (2) 
thinner, proportionately, than that of mammals; it is fibrous, and shows on 
acertain point of its surface: 2, The cicatricula (8), a yellowish-white disc, in 
the centre of which exists, 3, Purkinje’s vesicle, or the germinal vesicle; the 
yolk or vitellus (1), which fills the enveloping membrane. In the mass of the 
vitellus is seen what appears to be a bottle-shaped cavity, the long neck of 
which is applied to the cicatricula. 

The vitellus of the egg of birds differs from that of mammals in its 
anatomical composition, being 
entirely composed of what are 
designated vitelline globules. 
These globules are white in 
the centre of the egg, and have 
only a few nuclei; in the re- 
mainder of the mass they are 
much more voluminous, and 
contain a large number of 
granulations which give them 
their yellow colour. It is the 
presence of the clear vitelline 
nucleated globules in the centre 
of the egg, which has given 
rise to the surmise that the 


Fig. 450. 


SECTIONAL VIEW OF FOWL’S EGG. 
1, Yellow yolk composed of successive layers; 2, 
Vitelline membrane; 3, Layers of albumen; 4 
bettle-shaped figure, named Two principal layers of the lining membrane of 
the latebra (9) by Purkinje, is the shell; 5, Calcareous shell; 6, Chalaze ; 7, Air- 


a cavity. lie bo aaietrager ig = = me 8, 
icatricu 1 its nucleus enea’ whic. 1s 
ACCESSORY Parts.—These is the el leading down to th: white yolk 
comprise: 1, the white or cavity, or latebra, 9. 
albumen (3), disposed in three 
layers of different densities, and which are deposited around the yolk at 
three different periods during its course along the oviduct; 2, The 
chalaze (6), species of albuminous ligaments twisted in a spiral manner, 
and attaching the yolk to the testaceous membrane; 8, The testaceous or 
shell-membrane (4), which offers towards the obtuse pole a doubling into 
two layers, between which are found: 4, The air-chamber (7), so named 
from the air it contains ; 5, The shell (5), decomposable into several layers. 
The testuceous or shell membrane is composed of a closely woven fibroid 
tissue; it owes its opacity to the air it contains in its meshes. 


926 EMBRYOLOGY. 


The shell is very solid, and impregnated with calcareous salts; it is 
perforated by a multitude of cavities opening on its surface. When 
closely examined, it is found to have a more or less shining aspect, and in 
its mass fine sand-like particles. 

Landois, who has completed the researches of Wittich on the ovum of 
birds, distinguishes several layers in the shell; otherwise their number 
varies with the species. The shell, acting merely as a protecting covering, 
is all the more solid and complicated as the eggs are more exposed to 
the inclemency of the weather. 

Independently of the testaceous membrane which Landois attaches to 
the shell as a fibrous layer, this authority also recognises the uterine gland 
layer and the spongy layer. The former is much impregnated with cal- 
careous salts, and deeply studded with little round bodies which are the 
remains of the uterine glands, and give to the shell its sandy appearance. 
The spongy layer is structureless, and analogous to solidified mucus. 

This description demonstrates that the ovum of birds is distinguished by 
the considerable volume of its vitellus, and the addition to it of those 
accessory parts which give the egg its large dimensions and solidity. 
These differences will readily be understood, when it is remembered that the 
embryo must find in it all the materials necessary for its development, 
which takes place external to the parent. It is from the vitellus and the 
albumen that the young creature derives the elements which the mammal 
finds in the uterine mucous membrane to which it is fixed. 


ABDOMEN 

Abdominal aorta 

—- cavity . 

comparison of ‘ 
—— —— differential characters in 
divisions of . 

of inferior 
lining membrane of 
regions of 
reservoirs 

rings of . 
viscerain . , 
Abdominal salivary —_ . 
Abomasum i 

structure of 

Absorbent vessels 


Accessory portion of visual appar atus, 81 816, 817 


Acervulus - 

Adipose cushion of ear . 

Adrenals. 

‘Affluents of thoracic duct 

Aggregate follicles . 

Air-cells of lungs Be. hy wee ok 

Air-chamber of egg . 

Alimentary canal 

Allantoid fluid 

Allantois. . 

chorial 

structure of 

Alveoli of glands 

lymphatic . c 

Alveolo-dental periosteum . 

Amnii, liquor 

Amnion . Be BE Hh 

Parsee gy sey Sy 

Amniotic lamina 

Amphiarthroses te aE 

classification of 

Ampulla of Vater . oe 

Amygdale . . 3. ax” 

Amyegdaloid cavity . ae Xe 

Anastomoses io ey Se 
by arches. . 7 eee 

inosculation : . 

composite. . « 

convergent 

—mixed. . ‘ 

transverse communicating é 

ofnerves . 2 6 + + + 


‘394, 


INDEX. 


oe 
PAGE 
380 | Anatomical elements . . 
524 | Anatomy 
380 comparative 
385 definition of 
384 descriptive 
381 general r 
238 | —— philosophical 
881 | —— physiological 
a. regional . 
481 Special... . 2 2 « 
241 surgical : 
385 topographical . 
427 transcendental 
399 veterinary, 2 , 
wb, | Ancyroid cavity 
627 | Andersch’s ganglion 
Aneurism leg 
681 | Angiology 
850 | Animal amidon . 
494 | Annular cartilage 
637 protuberance . 
404 | Annulus albidus 
468 ovalis . ‘ 
925 | Anomalies in arteries 
385,400 | Anorchidism 
897 | Ansiform tube of Henle 
895, 896 | Anterior antibrachial region 
« 897 aorta 
» 0, brachial region 
. 890 cerebellar peduncle 
652 crural region . 
347 mediastinum 
- . 896 peduncles of conarium 
. 893,896 | —— tibial region 
. 893 white commissure of brain 
896 | Anus 
129 development of 
. 1% | Aorta 
425, 428 anterior 
335 common 
a. comparison of . 
517 | —— of anterior ‘ 
wb. | —— differential characters in . 
i. | — carnivora , 
ib, | ——————- pig. 
- mB | —— ruminants 
ib. parietal branches of . 
0. posterior . . . 
. 701 | ——preparationof . . 


. 


928 


INDEX. 


PAGE 
Aorta, visceral branches of 526 
Aorta, primitive 915 
Aortic heart 506 
Aponeurosis . 179 
antibrachial 261 
contentive 183 
— crural . 241 
— internal . ab. 
— fascia lata . 284 
—— gluteal 280 
—— perineal 863 
— deep . ib. 
— superficial bo te 5 AOS 
—- plantar . 268, 308 
tibial 297 
Apparatus 5 
cir culatory, i in ‘mammalia 498 
— in birds . 647 
—— digestive, in mammalia 325 
— in birds . 435 
—— generative 851 
—— innervation, of 650 
—— olfactory 815 
—— respiratory, in mammalia 439 
— birds . . . 475 
sense, of 792, 815, 
smell, of oo» » 815 
taste, of 813 
touch, of . 792 
urinary 484 
vision, of . 816 
Appendix auricularis 503 
Aqueduct of Fallopius . 842 
of Sylvius . . 682, 683 
Aqueous humour . 827 
membrane of ib. 
Arachnoid membrane 663 
cranial 664 
— spinal 663 
—— —— structure ib, 
ventricular 694 
Avantius, nodule of . . 505 
Aranzi, duct of . . 901, 916 
Arbor vite cerebelli . 688 
Arciform fibres of bulb . 685 
Arch of aorta 523 
hemal . 119 
—— ischial 96 
—— ischiatic ib. 
— neural , 114 
pharyngeal 912 
Arcus aorte, 915 
Area germinativa 892 
pellucida ab. 
Arm, bones of . 73 
Arms of pelvis of kidney 486 
Arnold’s ganglion 720 
Arterial zones of heart . 508 
Arteria helicine ‘ 865 
vertebralis ‘ 915 
Arteries . a ee 515 
anastomoses of 517 
anomalies, 520 
course 516 


PAGE 
Arteries, direction 516 
dissection 521 
form . ‘ 515 
general considerations ib. 
—. form ab, 
injection . 520 
mode of distr: ibution. 517 
— of origin 515 
preparation 520 
— relations . 516 
—- structure. 518 
termination . 518 
vessels and nerves 520 
— abdominal, anterior 563 
es posterior 547 
— subcutaneous 548 
— accessory thyroid . 576 
—— anterior dorsal of penis 548 
— tibial 551 
—— asternal ee 563 
--—— atloido-muscular . 577 
—— auricular, anterior 586 
— posterior 585 
—— axillary 559 
— collaterals 560 
— comparison of : 574 
— differential characters in 570 
—— basilar . 578 
brachial 559 
-—— bronchial 526 
—— br oncho-cesophageal é ib. 
—— bade , . 589 
bulb ; 540 
—— cecal 531 
—— cardiac 523 
— left ib. 
— right a. 
— carotid, common ' 575 
— collateral branches . 576 
— comparison of 29% 579 
—— ——- differential characters in 590 
— external . 581 
— internal . 579. 
— primitive » . 915 
— centralis retine . 588, 826 
—— cerebellar, anterior 578 
— posterior ib, 
—— cerebral, anterior , 581 
— middle tb. 
— posterior 579 
— cerebro-spinal 578 
cervical, deep . 561 
— inferior 564 
—. superior . 561 
cervico-muscular ad. 
— transverse 560 
ciliary . . 588 
circumflex, of coronary cushion | 554 
— anterior, of shoulder 565 
—— posterior, of shoulder 564 
or inferior, of foot . 554 
circumflex iliac 545 
coccygeal, lateral. . 541 


middle . . . . 


Arteries celiac . 


colic, direct or right ‘ 
left or retrograde 
collateral of the cannon 
branches 

of the digit . 3 
colon, first of small colon 
coraco-radial 

coronary 

coronary circle 

corpus cavernosum 
crémasterie . 
erural . " 

dental, inferior 

superior , 
diaphragmatic 

digital . 

dorsal , 

anterior of penis 
posterior of penis 
duodenal 

elbow, external collateral 
internal collateral 
emulgent . 

epicondyloid 

epigastric 

external pudic 

facial 

femoral 

femoro-popliteal 

gastric 

gastro- epiploica dextra 
sinistra 
glosso-facial 

gluteal 

great posterior of thigh 
testicular 
gutturo-maxillary 
helicine 

hepatic 

humeral 
collateral branches : 
deep 

iliac, external 
comparison of 


internal . 
comparison of 


iliaco-ceecal 

femoral . 

ilio-lumbar 

—-muscular 

inferior circumflex of foot 

communicating ,, 

vesical 

innominata : 

innominate branches of great me- 
senteric . . . 

intercostal a «Ay . 

internal pudic ‘ 

of female . 

of male 

interosseous, of fore-arm . 


| 551, 569 


INDEX. 


PAGE 
527 
531 

tb. 


569 
552 
532 
566 
584 
554 
543 
535 
545 
587 
589 
526 
552 
560 
wb, 
543 
528 
565 
566 
534 
566 
547 
ab, 
581 
547 
549 
528 
ab. 
ib. 
581 
542 
548 
534 
586 
865 
528 
565 
ab, 
ib. 
545 
557 


differential characters in, 555 


538 
546 


differential characters in, 545 


531 
543 
541 

a. 
BSS 

ib. 
861 
559 


Arteries, interosseous anterior , 
metacarpal , 

posterior . . 
intestinal, small . . 


LL 


ischiatic , 

—— labial, inferior 
superior , 
lachrymal . é 
laminal, anterior . 
lateral sacral . 


—— middle 


lingual 

lumbar 

mammary . 
external , 
internal , 
masseteric . 
mastoid 

maxillary, external 
internal . 
maxillo-muscular F 
median-spinal . 
meningeal, great . 
mesenteric, great . 
anastomoses 
anterior . 


VL 


| 


small 
metatarso-pedal 
muscular, deep 
great anterior 
small 
superficial 


eee 


nasal 

obturator . 

occipital : 
collateral branches . 
—— occipito-muscular 
—— esophageal 

omental 

omphalo- -mesenteric 
ophthalmic 

palatine 

palato-labial 
pancreatic . 

pedal 

-— perforating 
perpendicular . 

—— pharyngeal 

—— phrenic 

plantar 

cushion . 
interosseous . 
ungual 
popliteal. . ‘ 
posterior auricular 
communicating . 
dorsal of penis 
tibial 


— —— — collateral branches 


collateral } branches 


terminal br: anches 


of left fasciculus i 
of right fasciculus 
innominate branches . 


INDEX. 


930 
PAGE 
Arteries, posterior tibial terminal branches 2b. 
prehumeral . . 565 
preplantar ungueal . 554 
—— prepubic . 547 
—— prevertebral . 577 
profunda femoris. - . 548 
pterygoid . 587 
—— pulmonary. . . 52l 
— preparation of . od. 
— pyloric x . 528 
——— radial, anterior . . 566 
pees posteri jor . 567 
renal . 534 
— retrograde . 577 
—— sacral, lateral . . 540 
—— sacra media » 626 
-—— saphena . 549 
— scapulo-humeral . 564 
— small testicular . 535 
—— spermatic . . . 534 
—— spheno-palatine . 589 
— spinous . 587 
—— staphylin . 589 
— subcostal . 561 
——— sublingual , . 584 
— subsacral . . 540 
—— subscapular . 564 
—— subzygomatic . . 586 
—— superficial temporal . 985 
—— superscapular . . 564 
—— supra-orbital . . 588 
temporal . . 585 
— deep anterior . 588 
— posterior . 587 
—— terminalis . « 915 
testicular, great 534 
————small . . 535 
— thoracic, anterior . 563, 
— external . ib. 
—— —— inferior ib. 
—_— internal . . ab. 
— — terminal br. anches ib, 
— thyro-laryngeal 576 
~— trachelo-muscular 564 
——- transverse-cervical 560 
tranverse of face . 586 
——tympanic. . . 587 
—— ulnar 566 
—— umbilical . 538 
—— uterine. 535 
—— utero-ovarian . ib. 
—— vasa brevia Peat 528 
— intestini tenuis . 529 
vertebral . 561 
— vertebralis. . 915 
vesico-prostatic . 540, 861 
Arthrodia . 128 
Arthrology . 123 
Articular car tilages . 2. 
surfaces 121 
Articulations ib. 
in general ib. 
in particular 129 
nomenclature 128 


Articulations, anterior limbs, of 


atlo-axoid . . ‘ 
calcaneo-astr: agaloid 
carpal. . « ¢ 


carpo-metacarpal ‘ 
chondro-costal 
chondro-sternal 
transverse @ 
vertebral . . 
coxe . 
coxo-femoral 
elbow . . 
femoro-tibial . 
head 

humero- radial 
—— hyoideal 
interchrondral 
interhyoideal . 
intermetacarpal 
interphalangeal 
first . 

second 

third 
intertarsal 
intervertebral 
ischio-pubic , 
laryngeal cartilages, of 
metacarpo-phalangeal. 
occipito-atloid 
pedal 

pelvic . . 
posterior limbs 
radio-carpal 

ulnar 
sacro-iliac . 
scapulo-humeral 
tarsal . 

tarso- metatarsal 
temporo-maxillary 
hyoideal 
— thoracic 

—— tibio-fibular 

tarsal 
Arytenoid cartilages 
Auditive scala 

Auditory ens 
Auricles . 

Auricular facet . 

mass. 
Auriculo-ventricular opening 
zones 

Axile bodies . 

Axillary region . 

Axis, celiac . 

cylinder 

of arteries 


AIT 


eee 


| 


Baccated fibres of tooth .  . 
Bacillary layer of retina . . 
Balbiani’s vesicle . . . 
Band of Reil’ . 2... 
Barbs . pao 

Bars of hoof . ‘ ie ah 
Bartholine, glands : 


"140, 142 


505, 507 


Basement membranes 
Basilar membranes . 
process of os pedis 
Bauhini, valvula 
Bellini’s tubes 
Bicipital tuberosity . 
Bicuspid valve 
Biflex canal . 
Biliary ducts 3 
Bipolar nerve-cells . 
Bladder 

attachments 
development 
form 

functions 
interior 
position 
relations 
structure . 
weight 
Blastema 


Blastoderm, formation of 


development 
Blind spot 

Blood 

Bones, in general 


absolute form 


blood-vessels . 


cells of 


—— cavities 


configuration 
confor mation, inter: nal 


development . 
— direction 
eminences 


—— imprints . 


—— lymphatics 
medulla 
names 
nerves 
—— number 
—— nutrition . 
periosteum 
regions 
relative form 
situation . 
structure 
in birds 


astragalus - 
atlas. . 
axis . 
calcaneus . 
calcis 

capitatum . 
carpus . 

cervical vertebra . 


LTT 


coccyX¥. + + 
coste . + 
coxe - 


a 


external peculiarities 
general principles 


internal conformation 


anterior maxillary 


. . 


coccygeal vertebrae 


. 


» 493, 923 


INDEX. 


PAGE 
5, 327 
839 
85 
402 
487 
256 
507 
794 
423 
. 653 
. 491 
ib, 


491 
493 


16, 17 


Bones cuboid 
cuneiform . | 
dentata 

dorsal vertebra 
ethmoid 
falciform 
femur . 

—— fibula . 

—— first metacarpal 
frontal 

great cuneiform 
hamatum . 
heart, of 

—— humerus 
—hyoid . 

ilium . 
incisive 

incus 


intermasillary 
interparietal 
ischium 
lachrymal . 
large cuneiform 


lunare . 
magnum 
malar . 
— malleus 


superior . 
metacarpals 
metacarpus 
metatarsus 


nasal 
navicular . 
occipital 
os corone . 


—— — orbiculare . 
—— — pedis 
—— — penis 
palate . 
parietal 
patella 
pedal 
pelvis . 
penial . 
—— peroneus 
pisiform 
premaxilla 
prominens . 
pterygoid . 
pubis : 
—— pyramidal . 
radius - 
—— ribs 

sacrum 


of tarsus 
second phalanx 
semilunar . 
sesamoids . 


inferior maxillary 


—— lumbar vertebre . 


maxillary, inferior 


—— middle cuneiform . 


— — innominatum . 


scaphoid of carpus 


932 


Bones, small cuneiform . 


sphenoid 

w= shapes. « 

-—— sternum 

-—-— styloid 

—— supercarpal 
superior maxillary 

——~ supermaxilla 
tarsus . 


~{_ temporal 

—— third phalanx . 
—— tibia 5 
trapezium . 
trapezoides 
tricuspid 

—— turbinated 
ulnar 

unciform 
vertebra dentata . 
prominens 
tricuspid 
vertebrae 
cervical . 
coccygeal 
dorsal 
lumbar 
vomer , 
zygomatic . 
Botal, foramen of 
Bourrelet 

Brachial bulb. 
Brachio-rachidian bulb . 
Brain s 
Bristles . 

Bronchi . x 
cartilages . 
disposition 
form 

glands . 
relations 
structure . 
volume 7 
Bronchial cartilages 
glands . 

tubes A 
Bruch, membrane of 
Brunner’s glands 


Buccal mucous membrane . 


Bulbi fornicis 

vestibuli 

Bulb of ovary : 
of plantar cushion 
— of urethra 
Bulbus aorte 
olfactorius 
rachidicus . 
Burse, serous 


Caducous teeth , 
Caecum ae 
of mastoid lobule 
of Morgagni 
pharyngeal, 


small sesamoid +. 


INDEX. 


PAGE 
104 
86 
39 
842 


47 
503, 916 
803 
668 
ab, 
672 
727 
460 
461 
460 
461 
642 
461 
ib. 
ib, 
ab. 
642 


Calamus scriptorius 


Calcareous powder of vestibule. 


Calices 7 ‘ 
Calyciform papillae . 
Canal, biflex . 

Fr ontana 

—— Gertner 
godronne 

—— Haversian . 
—— hygrophthalmic 
inguinal . . 
Jacobson 
perivascular 
Petit 

Schlemm 
spinal . 
Sylvius 

Canine teeth 

Canthi of eyelids 
Capillaries 

Capillary system 
Capsular ligaments . 
Capsule of Glisson 
of lens . 
Capsules, suprarenal 
Caput gallinaginus . 
Cardiac cavity 
ligament 
orifice . 
septum 

Carpal sheath 
Carpus 

articulations 
bones 
movements 
Cartilage A 
of the tongue : 


Cartilages, complementary fibro- 


incrustation . 
interarticular 
interosseous . 
~ stratiform 
cariniform 

costal . 

ensiform 


semilunar , 
—— Wrisberg, of . 
xiphoid 
Cartilaginification 
Caruncula lachrymalis . 
sublingualis 
Cauda equina 

Cava, vena 
Cavernous sinus . 
Cavities 

Cell-germs 

Cells . 


bone 
calcigerous 
connective . 
hepatic 
medullary . 


. 907, 914 


interarticular of jaw P 


multiplication of. 


PAGE 
. 677 

. 839 

. 497 

, 836, 814 
794 

821 

886 

827 

13 

834 

242 

443 

665 

827 

821 

659 


682, 683 
| 344, 352 


831 
519 
518 
125 
422 
826 
494 
862 


389 


950 INDEX. 


PAGE ed 
Pes hippocampi. . . © » « + 679 | Plexus, carotid . ie ony NE 
Petit, canalof . . 2. . . . . 827 capillary, of Tungs. soe ee AE 
Petrosal sinuses. . . . . . . 606 cavernous. . ‘ ca AE 
Peyer’s glands . . . 1)... 404 cervical,deep. . . . 74 
Phalanges . " ~ « »« 82,105 | —— superficial : Bo ae ws A 
Pharyngeal arches % ao @ = 82 choroides . . 2. « « 6& 
cecum - « « « © # « SA, — = cerebellar . . . 68 
clefts ee oe a ew coronary (venous) . . » 612, 61 
Phar ynx e . *e ee 5 He gastric <« * &« « « « 
development of is lage ope Bess 3 SO) gubhural: 4 5 & « « = « %8 
—— disposition a ae ae” 372 | ——hypogastric . . . . . . %8 
TORN. «3. - ip BO RG ¥ ib. lumbo-aortic . . 1. we O78 
functions eS, Oe . 576 5 —— sacial 2 4 = % = « 8% 
muscles Ps . . 874 | ——lymphatic. .. ye a 362) 
relations eo - « OFe —— mesenteric, anterior . . . . 78 
structure . rs Yc posterior Spee eo ES. 
Phillips’s muscle 2 « » « 264 | —--myenterie. « « » . 40 
Phrenic centre . . . “46 | -——pampiniform . . . * « 8a 
Piamater . 1. o ¢ ~ « €65 Pelvie x 2 = % sie eee ES 
cranial - oe +. . | ——pharyngeal . 2 we WERT 
— spinal . . . . «ot, | —— podophyllous, venous. . . 612,61 
Pigment cells .. ~ & B21) ———senal 2. ws ws . 78! 
Pigmentary corpuscles of horn - . 810 | ——solar, venous . , ie ge 
granules .. > 3 » «© 822) ———gplenic . , - 78 
Pigmentum nigrum. » .  . 822.) ——subzygomatic. . «ay P22 TU 
Pillars of diaphragm. » . 247 | ——superticial cervical . .. 74 
of fornix, anterior . 695 | —— suprarenal . . 78h 
— posterior =... . 694 | —— sympathetic 3 eo 78: 
ofheart . Sg . 503 | ——tracheal . . eK - 78e 
of inguinal canal. : . 242 vaginal. 4 oe oe 42: 
ofrumen . . . . . 395 venous oe ae! ag ee ee 
of soft palate. .. . 3841 | Plice palmate . . . 886 
— anterior . . . . = #. | Pneumogastric lobule : oR wm @ 6R8 
—— posterior . - .  %. | Podophyllous tissue . . . . . 80¢ 
-—— of tongue, anterior . .  . 385 -sPons Valorii — . e 4 875, 674 
posterior . . 7. | Popliteal glands : 64( 
Pineal gland a ar ee ee - 680 | Portio dura . ee 721 
Pisiform tubercle . ¥ . 678 mollis . : : : j 794 
Pituitary fold of dura mater 662,663 | Porus opticus . ? : : . Bit 
elandk 36 <j gees » . 681 | Pouches, guttural . : c 84 
membrane. 2 4 = « - 444 | Poupart’s ligament Bm Gs : 241 
— glandsof .. - . 445 ) Preputial glands. ‘ : 867 
— neryes‘of « 5 4 4 i. | Preputium clitoridis . . , 88% 
stalk 2... . . . ) . . 681 | Precervical nerve. . 794 
Placenta. . . . ., . 895,899 | Precrural glands cw we : 64 
structure of . - . 899 | PREPARATION :—arteries , 52¢ 
= aultiple: ak ee « 903 dissection . | 521 
simple, . 2. 4 ¢ ‘ th, injection Seg: 520 
Plantar arcade or arch . « + 555 arteries, anterior tibial . | 551 
cushion, to » . 801 | —_ aorta, posterior eae te 
————bulbsof 2 >. |) 02 | —— suing ¢ % « » B24 
— structureiof 4 ¢ « « db | es funeral By ey ae te Be 
— tunic, of. 2. ADR. Il see head, of aes a 
nerves. + eS oe ilaeciiteragtt oo 
reticulum. . |... 612,804 | —_ re ao ork Re 
Bleue sg ge ow ew 464 | —_ popliteal Beis Ce" 
structure. « « « « «» « 465 | —— posterior tibial || 2 
Pleuritis, effusion of . . . . . 466 | —_ pulmonar ude: Eee ca 
Pleuro-peritoneal cavity . . . . 906 | —____ tibial, ea a eo ee 
Plexus, general anatomy . . . 701 | —— oe eel 
anterior auricular 2... 726 antiedlation: ey Pee 
Se mesenteric . 2. 2... 787 | — atlo- axoid See ee 
brachial, 5 «4 = @ 2 749,754 | —_ sal Be SA a de 
bronchial «oe ce oe . 732, 735 te r » + 148, 14¢ 
— chondro-sternal oy @ Tet 


Omentum, gastro-colic . 
gastro-splenic . 
ereat + 
Omphalo- -mesenteric duct 
vessels 
Opaque area 
Ophthalmic nerve 

Optic chiasma 
commissure 

layers . 

nerves . 

papilla . 

thalami 

Ora serrata . 
Orbiculare, os 

Orbital cavity 

Organ of Corti 

of Jacobson 

of Rosenmiiller 
Organic life, nerves of . 
Organs 

hollow . ‘ 
structure of . 


solid 


structure of 
Os orbiculare 
externum . 
—— tric 

uteri 

Osseous labyrinth 
Ossicula auditus 
Ossification, centres of . 
Osteo-dentine 

desm 
Osteogeny 
Osteology 

Ostium abdominali is. 
uterinum . 
Otoconites 

Otoliths . 

Ova of Birds 
Ovaries 
development 
functions 
situation 
structure . 
Oviducts . 

Ovisacs 
development 
rupture 
structure . 
Ovula Nabothi 
Ovulum . 
modifications i in 
Ovum 


Pacchionian glands 
Pacinian corpuscles . 
Palate 
hard 


functions of . 
structure 


sott 


functions of 


68 , 


INDEX. 


PAGE 

. 382, 389 
. 383, 429 
. 382, 389 
7 = 160% 
. 899, 915 
892 

711 

707 

ib. 

675 

706 

824 

» « 675 
. 820, 824 
. . 843 
. 817, 828 
. 839 

. . 443 
. 876, 923 
. 652, 653 
5 


‘ 703, 
332, 356, 359 


333, 356, 359, 360° 


334 

- 833 

340, 357, 359, 360 
‘ 343 


Palate, soft, muscles 
structure 
Palatine glands . 
Palatum molle 

Palmar arch 

Palpebrae 

Palpebral sinuses 
Pampiniform plexus 
Pancreas 

development 
excretory apparatus 
form yO RCO # 
functions . 
relations 
situation. 
structure , 
Pancreatic ring . 

Papilla cornica . 
Papille 


of foot 

of skin 
of tongue 
calyciformes 
capitate 
circumvallate 
—— filiformes . 
fossulate 
fungiformes 
lenticular es 


Parieto-temporal confluents 


Parotid duct 
gland 
Parovarium . 
Pathetici nerves 


Pavilion of Fallopian tube . 


Pecklin’s glands 
Pecquet, cistern of 
Pectoral cavity . 
Pedunculi cerebelli . 
cerebri 

Pelvis 

difference in sexes 
in general , 


Penis. 
Peptic glands 


Perforans tendon, sheath of 


Pericardium . 

muscle of . 

Perilymph 

Perimysium . 

Perineum 

aponeuroses of 

Perineurium 

Periople . 

Perioplic ring 

Periorbita 

Periosteum 

Peritoneum . 

structure of 

Perivascular canals 

Perspiration . ; 

Perspiratory ducts . 
glands. . . 

Pes anserinus . . 


. 803 
; 792, 793 
. . 336 
: 336, 814 


» = oo 
. 336, 814 
db. 

608 

» « Boe 
865, 370, 371 
867 

709 

876 

404 

634 


. 675, 677 


948 INDEX. 


r i r288 ; 717 
Nerves, maxillary, superior. . . . 712 | Nerves, sublingual. . . . : * 716 


subzygomatic . 


Median, 5 « « = 2 « « “4d 757 

—— mental ey me RM A te HG superscapular,-. . + ae 
musculo-cutaneous . . . 774,757 temporal, anterior deep . does 
spiral . =. a w « « #68 |-—= middle deep . ‘ = 

—. = syle ral ry 00 A posterior deep . . . aw. 
Hasal 2 = es & g « « WS} —— superficial . . - 716 
obturator. 2...) .) .).) 6o771=«|:~ —— thoracic, inferior... ee 755 
occipito-styloid 2. 2... . 725 | —— subcutaneous © fe o 
oculo-motor, common e = | = superior a ee 0. 
—_— external . .. 731 tibial, anterior sy cian Se 8 ue 


tnternal . 4 « «© 709 | —— posterior . . . 
esophageal . . . . . 732,735 tracheal, recurrent . . . . 734 
recurrent . . . . . 735 | —~—trifacial . 2. 2. 2. 2 2 e 7 10 
superior. ©. 2. 2... «6733 trigeminus . . . . . « %@ 


olfactory . > @ » « 05 trochlearis . . . . . « 709 
ophthalmic of Willis 6 o« @ GUL | tympanic ~« 42 wm A ee oe 2k 
optic . . = « = # 206 tympano-lingual . 2.) . 717,724 
orbital 2 &e @ — 6 » @ 4120 s—ulpr ys 2 ow we we Rk oe 1 959 


palatine, anterior. 2. 2...) vestibular. . . . . . 727,840 
posterior . . . . . 713 | —— Vidian c= *& & we © we Tee 
palmar oo» @ « «© # « « “766 Wrisberg, of . ee ae. See ZS 
palpebro-nasal » 2. 4. . « 712 | Nerve-tubes of spinal cor rd eo « « OPT 
pathetici . . . . . ) . « 709 | Nervouscolline. . . 2. . . . 180 
pectoral . & esa) OD glands, « « «© « # « « 495 
perforating inter costal « « w» 750 medulla . . . . . . «(652 
peroneal cutaneous . . . . 774 sheath. @ «2 # © ¥% « « 


petrous, great deep . . . . 728 system. by 7850 
a superficial . 2. . 722 | —— general comformation | | 651 
—— smalldeep . . . . . 728 San of Birds. . . . . « 790 
— superficial « « » G24 TISSUC! 5: eR ew oS 5 

pharyngeal . « « » 483 | Neuralarch. « « « « «© « « B19 
—phrenic . . . . . . . 753 | Neurilemma . ., . . . , 653, 700 

plantar. . . wy 760,766 | Neurility . 2. . . . . . , 655 
— external . ¢ » « 760: Neuroglia « « 5 « « wu « 670, 671 
renee’ deep. . . . . . . % | NoduleofArantius. . . , . , 505 
— internal. . . . . . %&. | Nodusencephali . . . , , . 675 

pnheumogastric th. GS. Ba See ae ES Nomenclature . a 4s @& « B26 

popliteal, external . . . . 9774 | Non-medullated fibres | - «+ « 652 

portio-dura Se . 721 | Nostrils . . » 2 . . 489, 440 
—_ intermedia... . . 722 framework . . . . . ) , 440 
— mollis. , : - 727 functions . 2, » oo. . 441 

pterygoid, internal - » . 716 | Nucleated nerve-fibres . . . , , 652 
—— pudic, internal +. 4 +752 | Nuclei of corpus striatum . . . . 696 

Tadial we kk we ee OEDEIVES 6 4 ex em OTL 705 

recurrent. . . . 1. O84 i 
— -esophageal. . . . , 735 | Obturator foramen . 3 aw = 98 
—respiratory =. . . . . . 755 | Occipito-atloid sinus, | - . . 606 
— internal. . . . . . 753 | Ocular membrane , ae ae 822 

rhomboideal » >) ) ] 1 54 gig. tg 1 828 

sacral. . + 6 6 . . 751 | Esophageal CIeeve yk we x 397 

saphena, external. ee oe 805 Esophagus a a a ae 377 
— internal. 2... O77 COUTSE . 5 a 4 6 ape 0. 
— accessory . ~ “OTL form ee 7 ab. 

sciatic, great ©... 78 functions , . . , |]! 380 
— small . . . . . «(772 | ——relations ne a 377 

spheno palatine . 2... 713 structure , ‘ : 379 


spin). 2... . 746,752 | Oken’s bodies 


— accessory . . . . . «6736 | Olfactory ae ole tee Xt ee 
—— splanchnic, great. . . 2. 786 cells . y ipa te) ce 445, 816 
————leser ] Df 787 lobules . . . ) ] ! 691’ 699 
— staphylin . « « « Gs MOVES ay sl a 705 


stylo-hyoid 


: ~« « « 4285 | Omasum aut Sod 
—— subclavian Son S @ ee sBOR 


» . . 67 | ——structure . . 899 


INDEX. 


PAGE 
Muscles, temporo-auricularis internus. 849 
tensor palati sw... . B48 
tympani so 6 ew ee 843 


— vagine . . . . . , 880 
—— teres major . 249, 253 
— minor . . . . 250 
—— thyro-arytenoideus 454 
— pharyngeus . 374 
tracheal. » . . 459 
transversalis abdominis oo. 6 244 
— costarum . . . . , 208 
—_— — hyoidei Oe ae ge se a) 2228 
— nasi. . » «= » 28t 
transverse of abdomen ne Bee 
— of ribs. » 236 
— spinous of back and loins » 209 
transversus perinei . . . = , 863 
trachelo-mastoideus_ . . . . 191 
trapezius .. » «6 » 203 


triangularis of sternum e « = BoP 
— triceps extensor brachii . . . 258 
trochlearis > + + « «& =» BEB 
ureters, of . . . . . . 490 


— wrethra, of - 6 @ & 862 
——uterus,of. 2. . . . «879 
vagina,of. . . . 1. . 880 


—— Wilson’s muscle - . 493, 862 
zygomatico-auricularis . . . 847 
zygomatico-labialis . . . . 219 
zygomaticus . . . wD 
Muscular cell-ibres . . . . . 429 
fibre . 4 4,178 
insertions, table of <s * «© = 815 
lamina. 4, « « » « « « 905 
tissue 2 ws 4 * & & s 5 
non-striped . 2, 2. aD 
striped » « © » « «= 9% 
ofheart. « «+ 2 «» « 508 


Musculi papillares . . 2. . . «503 
pectinatiy ~ 2» + « « « « 606 
Myeloplaxes Se . 4,15 
Myolemma . : S @ oo & 198 
Nasal cavities, soe e . 489, 440 
duct. mt ee me BBE 
{09825 4 5 «& & = a » SAL 
meatuses » © @ &© «© « 442 
Navicular sheath . . 2. .) .) 269 
Navicularthritis . . . . . . 158 
Nerve-cells fe ste ch a 4, 652 
corpuscles. -, . . . . . 652 
DT OS) sw te RB Ss Se 4 
tubes .. « cao Ge, ye “B82 
NERVES :—cerebro- -spinal Rg ge elo SOO 
Ctanial . ow we sw ROB 
distribution . . . . . TOL 

division: ¢ . <u. % « .«, 700 
ganglionic -  . 652,701 
—mixed. ® a ow ws 700) 


organic life, re 
ONgIN. ago sg 2 2 4 «= OL 
—— structure . . . . . 700 
termination. . . . . 702 
vegetative life, of . . . 652 


947 

PAGE 

Nerves, in Birds . . , , . |. 789 
abducentes . . «oe POT 
—— accesory of external saphena . 774 
— of internal anh eg 1 
acromial ,  , soe «2 » 749 

aad; ec ee ee TBD 
angularis . , soe. 754 
anterior brachial . oe = « 959 
— femoral. 4 a 8 e771 
— gluteal. . . . . . (772 
— tub TALS 9 sae aa! ash. Wot! og 
auditory .. e » @ =» FT 


auricular, anterior ee « « FS 
middle << oe ee og ib, 
posterior . . . . tb, 
axillary .. woe ee a SF 
—— brachial, anterior . em ee 
buccal. os 2 e @ @ «= « TIS 
cardiac i * & £ © woe FBS 
chorda-tympani 
CUANy gg a me aw NS 
circumflex + @ &@ & « BB 


clavicular. . 2. 2... 749 
coccygeal. . . . . . . 752 
cochlear . 5s © «© ty 797 
collateral-dorsal . . , 765 
crural, se we ee ee 
cubito-cutaneous ¢ 2 = » Bee 
—. plantar. . . eB 
dental . - 9 713, 717 
— anterior. 2... 1. 718 
——nmidde ...,...., a. 
— posterior, «§ =» « 3 . #0 
diaphragmatic, . . . . 749,753 
digastric. A «@ 4 - 725 
dorsal, collateral st & = 765, 
—. greabi a 4 af we = wi OR 
facial .. ew em ee TOL 
femoral, anterior Soy ee oe 
femoro- -popliteal, great . . . 773 
— small... 74 
frontal ‘ ' % & & @ FE 
glosso-pharyngeal ae ae ee 
—— gluteal, anterior . 2 2)... (772 
—_ posterior . . . . . 9738 
——“ gustatory; 9 2 = a « » AIG 
— hemorrhoidal a ee ee 752 
-—— hypoglossal . . . . . ) . 987 
— great os se oe oe em we HS 
— small 5 5 « « » « 416 


iliaco-muscular ae WEL MES 
inguinal,external . . . . 751 


— internal. 2. » s = # ib, 
infra-orbital . . ~ @LO 
——infratrochler, . . . . . 712 
—ischio-muscular . . . . ) . 773 
—=Jacobson’s, « « « » « « 428 
lachrymal, 2 «© «© « «© « “WL 
laryngeal, external . . . . 733 
— inferior . . » « « « 434 
ee superior + ¢ » «© « WES 
lingual 5 os se ew ee FTG 


masseteric . . . . . . 715 
maxillary, inferior . . . . 714 


INDEX. 


946 
PAGE 
Muscles, obliquus oculi superior 822 
obturator externus 292 
—_ internus . ab. 
occipito-styloideus 227 
cesophageal 379 
omo-brachialis 254 
_— hyoideus 198 
orbicularis oculis . 832 
— oris 217 
— palpebree 831 
orbito-palpebral 832 
panniculus carnosus . 186 
— palato-glossus . » » 8389 
== pharyngeus . . 342, 374 
— staphyleus 342 
palmaris magnus . 266 
pectineus . 289 
-— pectoralis magnus. 233 
— parvus 234 
as tramsversus . 231 
— pedal > = BLL 
perforans . "968, 302, 568 
—— perforatus : 267, 304 
— pericardium 512 
—— peristaphyleus externus 343 
— internus . tb. 
peroneus : 298 
pharyngo-glossus . 339 
_—_ staphyleus » » » 842, 374 
— plantaris co ” 304 
~--— popliteus wb. 
——— postea spinatus 251 
—— posterior constrictor of vulva 883 
—_— great rectus of head 195 
— medius 222 
— ulnaris 7 265 
—— protractor of sheath . 868 
psoas magnus . 212 
Soe parvus 214 
pterygoideus internus 224 
pterygo-pharyngeus 374 
quadratus cruralis 292 
— lumborum , & ley Ge QE 
—- retractor ani 414 
— oculi 827 
—— of sheath 868 
— rectus . 284 
— abdominis 243 
—— —— capitis anticus major 199 
—_ — minor ab, 
—_— —. posticus major 195 
— —_ minor . , tb. 
— — oculi externus 829 
—_ — inferior ab, 
—_— — internus ab. 
— -— posterior 828 
— superior « « «= » 829 
—— retractor oculi . . . 828 
rhomboideus 188 
sacro-coccygeal 215 
— coceygeus inferior 216 
—_ —-. lateral ib. 
—_—_— superior ab. 
-—— —— lumbalis 214 


PAGE 
Muscles, sartorius . . - «+ ete 
sealenus  . m8 348 
scuto- auricularis externus . 
internus 849 
semimembranosus 288 
semispinalis dorsi . 209 
semitendinosus 287 
serratus magnus 236 
short abductor of arm 250 
adductor of leg . 289 


extensor of fore-arm r 
flexor of forearm . . . 256 
small adductor of thigh . . . 291 
anterior rectus of head. . 199 


anterior serrated 205 
complexus . . » ¢ 19D 
extensor of fore-arm 269 
hyoglossus 330 


lateral rectus . ; s » 200 
oblique of abdomen . . 242 


MTT TET 


of head se 2 104 
posterior rectus . . . 195 
serrated 205 
psoas 214 
seapulo-humeralis 254 


ATINTTNUTTNNTNNT ORIN 


supermaxillo-nasalis . . 221 
solearis dp 1) fn fe 
SOLEUS sae se A cae ANS 
sphincter ani . ENS ity 
vagine 2 « 2 «+ « « -880 


I 


spinalis colli . . . 1... (198 
— dorsi ow we oe, e209) 
splenius ew we 2 3 = 189 
square crural. . . » . 292 
— of loins x 2 « « 21 
stapedius . . . . . . . 848 


sterno-aponeuroticus. . . . 232 
costales . 5 @ 2 «= « 287 
humeralis . 2... 232 
———hyoideus . . . . , 198 
masillaris . . . . . Oh 
— prescapularis le, of 
c— thyro-hyoideus. . . . 198 
——thyroideurs . . . 1. od 
trochigeus 
stylo-glossus in) Grenier vo 16 
hyoideus . . . . , 27 


— maxillaris s » 226 
— pharyngeus . . 343, 375 
—— subcutaneous of neck a 196 


sublimis of phalanges é 
subscapularis . 5... 259 


subscapulo-hyoideus - 198 
——subspinatus 2... L, B 
—— supercostals .  . , es « (23% 


superficialis costarum. . . , 205 
superficial gluteus a> Cs > 280 
flexor of phalanges .  , 267, 304 
pectoral . - 231 
superior constrictor of pharynx » 374 
supermaxillo-labialis , Sy 
——~superspinatus.  . | | |, oy 
—— temporal + 223 
—— tempor o-auriculari is exter nus. - 847 


INDEX. 


PAGE 
Muscles, depressor labii superioris 222 

diaphragm 246 

digastricus 225 
— dilatator naris anterior 221 
— lateralis ab, 

erector clitoridis . 882 
— coceygeus 216 
— penis 864 

extensor metacarpi magnus 262 
—. obliquus - . 263 
— pedis . 263, 298 
—_— suffraginis . 264 

external flexor of metacar pus 265 
— intercostals . 237 
— oblique of abdomen 240 
— obturator 292 
— — pterygoid 224 
— vastus 285 

extrinsic of tongue 337 

fascia lata . 284 
—— fleshy panniculus . 186 

flexor brachii . ‘ 255 
— metacarpi externus . 265 
we internus 266 
— — medius ib. 
— —— metatarsi 300 
—_ — parvus 311 
_— pedis é 305 
— — accessorius 306 
—_— — perforans . 268 
-— perforatus 267 
—— fronto-superciliar y 431 

gastric Ge 389 

gastrocnemii . . ge 302 

gastrocnemius externus ib. 
—_— internus . 304 
— gemelli of pelvis . 293 
— of tibia . 302 
—— gemini ae ee ee 293 
— genio-glossus 338 
— hyo-glossus . ab. 
a hyoideus a oa 226 
—— gluteus externus . 280 
— internus . 282 
— maximus 281 
— medius ib, 
— gracilis. 289 
— great adductor of thigh ‘ 291 
— anterior straight of head 199 
— complexus > ie 191 
— dorsal 203 
—— —— hyo-glossus . 337 
—— oblique, of abdomen. 248 
— — of head 193 
— psoas. * 212 
— rectus, of abdomen ‘ 243 
— serratus . 236 
— supermaxillo-nasalis 5 221 
—— heart, of eo ai 509 

humeralis externus 3h: Asse. aps OU 
— hyo-epiglottideus . » + « 453 
— glossus brevis . . . 3837 
— — longus 2. we 
—_— pharyngeus. . . « . 374 


Muscles, hyo-thyroideus 

hyoideus magnus . 

parvus 

iliac psoas . 

iliacus . 

ilio-spinal . ‘ 
internal flexor of metacarpus 
intercostals . 

oblique of abdomen 
obturator 

—— pterygoid 

vastus 

interossei . . a 
intertransversales Jumborum 
intertransverse of loins 
of neck 

intestinal . 

intrinsic of tongue 
ischio-cavernosus , 
coccygeus 
urethral 
kerato-glossus 
kerato-hyoideus 
labialis. 

lachrymal. . 
lachrymo-labialis . . 
large extensor of fore-arm 
lateral extensor of phalanges 
lateralis sterni . 
latissimus dorsi 

levator ani 

humeri 

labii superioris 

menti 

palpebree 

Jevatores costarum 

lingualis 

super ficialis . 

long abductor of arm 
adductor of leg . 
extensor of fore-arm 
flexor of fore-arm 

of neck 

longissimus dorsi . 

longus colli 

— lumbrici 

masseter - 
mastoido- auricularis 
humeralis 

— maxillo-iabialis 

— mento-labialis Bees ate 
—— middle extensor of fore-arm . 
— mylo-hyoideus 

nasalis brevis . 

longus 


TTT 


"402, 


| 


flexor of metacarpus 
of phalanges 
obliquus capitis anticus 
inferior 
superior 
externus abdominis 
internus abdominis 
—— —oculiinferior . . 


212, 


264, 


oblique extensor of metacarpus ‘ 


944 


Molar teeth. . . 
Monorchids . 
Monro, foramen of . 
Mons veneris 
Morgagni, caecum of 
hydatid of . 
liquor of 
Morsus diaboli 
Motores oculorum 
Mouth ‘ 
development of 

in general . 

Mucous derm 

corium 

—membrane. . 

of bladder 

of bronchi 

of cheeks 

of Fallopian tubes 
of guttural pouches. 
of internal ear 

of intestines, large . 
small... 

of Jarynx 

of lips 

lymphatics in 

of mouth 

—— —— of esophagus 
olfactory 

of pharynx . 

of sinuses of head 

of soft palate 

of stomach . 

of tongue 

of trachea 

of tympanum 

of ureters 

of uterus 

of vagina 

of vulva . 

Miiller’s duct Pac 
Multipolar nerve-cells . 
Muscle-plasma 

Muscies :—striped in general . 
action ery 
attachments... 
appendages . 
classification . 
contractility . 
development . 

—— direction . 

form. . P 
general table of . : 
in Birds , : 
insertions 
lymphatics 

mauner of studying . 
nomenclature 


352, 359, 361 
853 
"682, 693, 694 
888 


’ 


) 181, 913 


—— physico-chemical proper ties. 


— physiological properties . 
preparation of 
preservation of . 
—relations, . . 

——— situation. . . . - 


. 


INDEX. 


one PAGE 
Muscles, structure . 178 
tissue ~ % w. 
uses. 182 
vessels and nérves 180 
335 volume 174 
871 unstriped . . 174, 328 
826 accelerator urine . . 862, 863 
876 Doe 
708 adductor femoris . 291 
330 | —— longus . ab. 
920 | —— tibialis 287 
355 alveolo-labialis 218 
327 anconeus . o> 260 
ib. angularis scapulee a> 189 
326 antea-spinatus 251 
493 anterior constrictor of vulva 884 
461 | —— extensor of metacarpus . 262 
331 | ———— of phalanges . . 263, 298 
876 | —— medius . 222 
845 | —— straight of thigh 284 
840 | —— ulnaris 266 
410 arytenoideus 455 
402 aryteno-pharyngeus 375 
455 basio-glossus . 337 
331 biceps abductor femoris 286 
629 brachial biceps . . . 255 
355 | —— bronchial eh 461 
379 buccinator 218 
444 | —— bulbo-cavernous a 862 
374 caput magnum . . . 258 
447 | —— medium . 259 
343 | —— parvum . ib, 
390 ciliaris 821 
335 circumflexus palati 342 
459 | —— common intercostals . 208 
844 | ——complexusmajor. . . . . 191 
490 | —— minor 195 
879 | ——— compressor coccygis 217 
880 | —— urethra . 863 
883 | —— vesicule 860 
923 | —— constrictor of phar ynx, ‘first middle 374 
653 | —— inferior 1. 
181 | ———— second middle ib, 
174 | ——- —— superior ib. 
182 | —— vagine ; 883, 
175 | —— vulve, anterior 884 
183 | —— posterior . 883 
ib. | ——coraco-brachialis . ‘ 254 
181 | —— humeralis 4 ab. 
—— corrugator supercilii . 831 
175 | ——  cremaster 852 
174 | —— crico-arytenoideus lateralis 454 
315 | —— posticus ab. 
313 | — pharyngeus . 374 
175 | —— thyroideus 453, 
180 crotaphitic 223, 
183 crural triceps . 284. 
176 curvator coccygis . 216 
480 dartos 2. 853 
a. deep flexor of phalanges -  . 268, 305 
1sé | —— gluteal F * og9 
185 | —— pectoral . is 233 
176 depressor coccygeus Be Se 216 
174 | —— labii inférioris 222 


Lymphatics, muscle, in. 
nervous tissue, in. 
nostrils, in. 
ovary, in 

penis, in 
peritoneum, in 
—— pharyngeal 

pia mater, in . 
— pituitary 

popliteal 

— precrural . 

—— prepectoral 

—— prescapular 
rectum, in 

—— serous membranes, in 
—— skin, in 

— small intestines, in 
— spleen, in . 

—— stomach, in 
subglossal , 
sublumbar 
submaxillary . 
suprarenal capsules, in 
testicle, in : 
thorax,in. . . 
— thymus gland, in. 
— thyroid gland, in . 
—vurethra,in . . 
— uterus, in . 
vagina, in , 
vessels, in. 
Lymphatic sheaths . 
sinuses . 


Macula lutea . 2... 
Malleus . .. wi 
Malpighian cor puscles 
glomerules 

Mamme SER” aay 2 oe 

form 

functions 

situation 

structure . 
Mammary ducts 

glands . 

Mammilla , 
Mammillary tuber cle 
Manubrium . 

Manyplies 

Masculine uterus 

Mastoid cells of ear . 

-— lobule of brain 

Matrix of hoof . . 
Maxillary gland 

Meatus auditorius externus 
nasal ‘ 
urinarius, female ‘ 
valve of . 
Meckel’s cartilage 

ganglion , 
Meconium 

Median lacuna of frog 

sinus . . . 
Mediastinal pleura © eo 


° 


INDEX. 


PAGE 


. 180, 630 


630 
441 
874 
863 
384 
643 
665 


1 446, 447 


640 

ib. 
645 
644 
640 
630 


+ 629, 795 


406 


. 431, 642 
. 392, 641 


644 
638 


644° 


494 
856 
642 
473 
472 
863 
880 
882 
630 


+ 520, 630 


632 


836 
842 


. 430, 487 


489 
884 
ab. 
885 
884 
ab. 
ib. 
ab. 
ab. 
687 
842 
ao7 
861 


* 340, 842 
691,692 


800 
367 
846 
442 
882 

ib, 
912 
719 
427 
807 
606 
464 


Mediastinum, anterior ,  , 
posterior 

testis . 

Medulla of bones 

Medulla oblongata 
Medullary cells . 

layer of kidney 
Medullated nerve-fibres. 
Medullo-cells 

Meibomian glands 

Meissner, corpuscula tactus of . 
Membrana dentata , 
granulosa . 

Jacobi . 

nictitans 

pupillaris . 

—— tympani 

secundaria 
vitellina 

Membrane of aqueous humour . 
basilar 

Bruch, of . 

choroid 

conjunctival 

Corti, of e * 
Demours, of . . 
dentated . . . 
Descemet, of 

eye, of . x * «% 
fenestrated . . . 
—— hyaloid 

keratogenous . 
mucous 

Reissner, of 

serous . 

Membranous cochlea 
semicircular canals 
urethra 

vestibule 

Meningeal granulations 


Meninges of cerebro-spinal axis 


Meniscii, interarticular 
Mesenteric glands . , . 
Mesenteric Jamina 
Mesentery 

colic 

proper 

Meso-caecum 

Mesocephalon 

Meso-colon 

Meso-rectum =. 
Metacaxpo-phalangeal sheath 
Metacarpus . é 
Metatarsus . 

Middle cerebellar peduncle . 
ear < 
septum of nose 
ventricle of brain . 
60) er ee 
Milk-fountains . 2... 
Mitral valves 

Mixed nerves ae 
Modiolus ei Ne * 
Molar glands . . . 


© 6 © © © © © we 


: 675,676 


4,15 
487 
652 


4,15 


"330, 831, 


” 904, 


383, 
383, 384, 
; 883, 

| 675, 


832 
794 
666 
873 
825 
833 
909 
841 
842 
873 
827 
839 
822 
820 
832 
839 
827 
662 
827 
817 
519 
827 
803 
326 
839 
328 
839 

ab. 
861 
838 
663 
660 
163 
641 
906 
401 
413 
383 
407 
677 
383 
4135 
267 

81 
105 
678 
840 
444 
682 
885 
625 
507 
700 
838 
369 


942 
PAGE 
Ligaments, odontoid. 2 ~ 186 
ovarian . 384, 873 
patellar 164 
pectinated . 819 
peripheral, inferior 140 
Poupart’s . 241 
pubio-femoral . 162 
radio-carpal 149 
radio-ulnar, interosseous . 147 


peripheral, . . . ab, 
external transverse . ab. 
round, of uterus , . . . 384,877 


sacro-iliac . 159 
— ischiatic . 160 
—. Sciatic « « 4 & a & ab. 

scaphoido-cunean . 171 

sesamoid s 8 153 
—- infetion . 9 2 # « « ib, 
— lateral 154 

spleen, of . 429 


stellate . . . . . . 140,141 


— inferior . 142 
subflava 133 
superdorso- lumbar 132 
superspinous cervical a = = ob 
suspensory of fetlock . » . 154 

— of penis . 865, 866, 872 

— of sheath 867 

——- of uterus 877 
tarsal , ‘ 168 
tarso- metatarsal, posterior 172 
teres. 162 
tibio-fibular 167 
tracheal 459 
transverse . 136 

—— umbilical . 491 


uterine, broad : 384, 877 
POWTG tl foe ty ag! ge ag HDR 


— oe 877 
vulvular 3 884 
Wolffiani, of corpora : 922 

Limbs in general r 109 
their parallelism . 110 

Limitary membranes 5, 327 

Linea alba ‘ . 239, 240 

Linex transverse 693 

Lingual canal 334 
glands . 370 
glandule 335 
Tacune 335 
mucous membrane 814 

Linguetta laminosa . . 679 

Lips . zis 330, 356, 359 
functions of + * ae 
structure of 3381 

Liquor amnii 896 
cornese 820 
folliculi 873 
labyrinthi . 840 
Morgagni . - 826 
seminis < » @ 58 

Liver 6 8 ~ » » 419 
attachments oe La 420 
development >» » 427, 92° 


INDEX. 


PAGE 

Liver, direction . . 419 
form a. 
functions 426 
proper tissue . 422 
relations 420 
situation 419 
structure . 422 
weight 419 
Lobes of liver . 420 
Lobular bronchial tube 468 
Lobulated glands 329 
Lobule, anterior of lung 467 
Lobuli testis ‘ 854 
Lobulus pheumogastricus 467 
Lobus Spigelii é 420 
Locomotory apparatus . 6 
Longitudinal fissure of brain . 690 
Lowenberg’s scala 839 
Lumbar nerves . 751 
vertebrae . $ 25 
Lumbo-rachidian bulb ; 668 
Lumbo-sacral plexus » «A980 
Lungs F . 466 
development 470, 918 
form . 466 
functions 470 
—— fundamental tissue 467 
general disposition . . 466 
relations ab. 
serous envelope 467 
situation 466 
structure . 467 
Lymph . . 498 
Lymphatic glands and vessels : 628 
course 631 

—_ — form 628 
— — number . ib, 
—_—_ — origin ib, 
—_ —. plexuses . 629, 631 
—— —— —— preparation of 663 
—_— — rete mirabile, . 631 
—_—- structure . 628, 633 
— termination . 631 
Lymphatics, Birds, in 649 
bladder, in . 493 
bone, in 15, 630 
—— brachial c= « B44 
bronchial . . 642, 461 
cecum, in . 641 
colon, large, in ab. 
— small, in 640 
guttural 643 
heart, in . 511 
hepatic sian in 494 

iliac ‘ 640 
inguinal, deep 638 
— superficial hs 
intestines, in . "641, 406, 410 
—— kidneys, in 489 
laryngeal , 455 
—— lips, in 331 
liver, in 425 
lungs, in 470 

—— mucous membranes, i in 629 


Lachrymal ducts . . 


gland . : 
BOVVE e = 2. we 
sac. eg 


Lachus lachrymalis 
Lacteal vessels 
Lactiferous ducts 
Lamelle of foot . 
Lamina cinerea . 
cribrosa 
fusca 

spiralis 
Lamine of foot . 
Lamiual tissue 


Lancisii, chord longitudinalis of . 


Large intestine . 
Larynx . 
articulations ‘ 
development 

entrance . 
external surface . 

form 

functions . ree 
internal surface . . 
muscles . . 

nerves . 

situation 

structure , 

ventricles . 

vessels 

Latebra . 

Lateral columns of spinal cord 
fibro-cartilages 

lacune of frog 

lamina of embryo 


— triangular fasciculus of isthmus . 
. 692, 693 


ventricles . 

Left auricle of heart 
ventricle of heart 
Leg, bones of 

muscles of 

Lens, crystalline 
capsule of 
structure of, 
Lenticular ganglion 


glands 

papilla 
Leucocytes 
Lieberkiihn’s follicles 

glands . 
LiGAMENTS . . . 4 

— capsular . 

funicular. 


general considerations 
interosseous . 
membraniform 
peripheral 
—— white. 

yellow . . 
anterior of carpus 
arteriosum 
astragalo-metatarsal . 
atlo-axoid, inferior 
superior 


INDEX. 


PAGE 
834 
ib. 
711 
834 
831 
402 
884 
850 
683 


| 708, 818 


819 
838 
804 

ab, 

693 
407 
449 
451 
918 
456 

3 ab. 
. 449 
456 

ib. 

453 


| 455, 734 


449 
450 
456 
455 
925 
669 
801 
807 
905 
678 


507 
506 
100 
288 
826 
826 

ab. 
718 
404 


. 336, 814 
4 


Ligaments, auditory 
bladder, of. 

DPOad wo ee eae, 
calcaneo-astragaloid 
caleaneo-metatarsal 


of carpal 

of costo-sternal 
of coxo-femoral 
of femoro-patellar 
of humero-radial 
of hyoideal 


” 


of occipito-atloid 

of scapulo-humeral 
of temporo-maxillary 
of vertebral 
cardiac . 
carpo-metacarpal . 
carpal, anterior 
cervical 
chondro-xiphoid 
ciliary . 

common car pal 
infevior vertebral 
superior cervical 
superspinous 
costo-sternal, inferior 
superior 
costo-transverse, anterior 
posterior . 


areca eee 


PePanaeeee 


cotyloid 
coxo-femoral 
crico-trachealis 
cruciform . 
cuboido-cunean 
cuboido-scaphoid . 
denticulated 
—— diaphragmatic. 
Fallopii 
femoro-patellar 
—— glosso-epiglottic 
hepatic 
hepatico-renal 


| 


internal lateral 
ilio-sacral, inferior 
superior 


interarticular costo-ver srtebr al 


— interannular 


intercarpal 

interlamellar . 
interosseous of carpus 
radio-ulnar . 
interphalangeal, first . 
second 
intersesamoid . 
interspinous 5 
intervertebral . . 
latum pulmonis . . . 
nuche i ee 
lobus Spigelii, of | 

lumbar of corpora Wolffiani 
metacarpo-phalangeal =, 


of metacar po-phalangeal % 


humero-radial, exter nal lateral 


capsular of atlo-axoid ar ticulation 


. 148, 


TL 
136 
151 
141 
162 
165 
146 
139 
154 
137 
143 
138 
134 
382 
150 
149 
132 
142 
822 
151 
131 
ab. 
132 
142 
141 
ab, 
ib. 
162 
ab. 
453 
137 
171 
ib, 
665 
922 
241 
165 
335 
420 
383 
145 
ib. 
159 
ab. 
133 
140 
150 
133 
149 
147 
15% 
ib. 
153 
133 
131 
467 
133 
383, 
922 
154 


940 
Hilum pulmonis, . . . a 
Hippocampus . . . . . 693, 
Hippomanes . ‘ 
Hollow organs 
structure of 
Honeycomb glands . 
Hoof... * 
contents of 2 
description of . 
development of 
structure of 
wall of. os 
Hoof-homm . . 1. . ee 
structureof . . . . 
Hornecells . 2. 1 we 
Horns, frontal 
Horny production 
Horse-hair oy 38 
Humours of eye . . 817, 
Hyaloid membrane . x 
Hydatid of Morgagni 
ep ualay canals 
Hymen 
Hyoideal region . 
Hypochondriac region 
Hypogastric region ¥ 
Hypophysis cerebri. . 
Tleo-cecal valve .  “y2t02, 
Tleum: swe www 
Imprint . 
Incisor teeth 344, 349, ‘357, 359, 
Incus 
Inferior umbilical ring . 
Infundibuli of lungs 
Infundibuliform fascia. . . 
Infundibulum . . . 
Inguinal canal »« . ww 
hernia. -: 4 Mw «2 % 
ving. bP ds. te 
Injection « of arteries. oe 
ofveing 2. 6 6 ws 
Inosculation. .. = 
Tnsule ¥ we dds 
Tnteguments of external ear . 
Interarticular meniscii - 
Interauricular partition 
Intercarotid ganglion $ 
Interglobular spaces of Czermak 
Interlobular fissure . 
veins Oo 4» Fi a8 
Internal crural region . 
ear og 
nerves of . 
Interosseous cartilages . 
Interpeduncular fissure ap! Ga 
Interstitial substance . . . . . 
Interungulate gland Z 
Interventricular septum ; F 
Intervertebral fibro-cartilages . F 
foramen . 2. 1. . 
Intestinal groove . . . 
Intestines ee er ae 4 
development . . . . 


INDEX. 


PAGE 
466 
695 
897 
326 

ab. 
404 
800 
800 
805 
810 
808 
805 
808 

ib. 
809 
813 
799 
797 
827 
827 
871 
834 
883 
225 
381 

ib. 
681 


408 
401 

11 
361 
842 
894 
468 
852 
681 
242 
547 
242 
520 
599 
517 
635 
850 
163 
503, 
789 
345 
690 
423, 
288 
837 
840 
124 
678 
178 
794 
503 
130 

24 
894 
400 
920 


large 

Intestines, large, " attachment 
capacity 

—— —— dimensions . 
direction 
functions 
interior . 
relations 
situation 
structure 


—— small 


attachment . 
course 
development 
form 
functions 
interior . 
relations f 
structure 
Intralobular veins 

Iris 


structure of ; . 
Ischiatic spine ; 
Isthmus of encephalon . 


structure of , 
of fauces 
Iter ad infundibulum 


Ivory . . are 


Jacob’s membrane 
Jacobson, nerve of . 
organof . . we 


Jejunum F by = Sb, 20 
Jugular channel aa de 
vein. 


Keraphyllous tissue 
Keratogenous membrane 
Kidneys 3 

conformation, external 
internal . 
development . 
functions . 
primordial, 
—— proper tissue , 
—relations . . . 
—— situation . 

—— structure . 
tunic 
weight zi 
Krause, corpuscles of i 
terminal genital 


ry e 


Labia vulve 


Labial glands oof 
Labyrinth eS . 
osseous. son % 
membranous . . 
Lachrymal apparatus. , 
cmal., . 2. 4 


673, 675, 676 


external conformation of 
internal conformation of 


quartum ventriculum . 
» 345, 921 


oe ee ee 


eo 8 © © ee 


» 489, 


INDEX. 


PAGE 
Glands, laryngeal . . 2 . ) . ) . 455 | Glottis 
lenticular. . . 2). .) . 404 | Gluteal aponeurosis ” 
—— lLieberkithn’s. . . . , 403,410 region . 
lingual =... . . . 335,370 | Goose-sicin 
liver . . . . . ) .) , 419,642 | Graafian vesicles 
lobulated . . . 1... «829 Granules, fat 
—— lymphatic . . . . . . 632 pigmentary . . 
Mammary. . . . . . . 884 proteic . fog « 
——maxillary. . . . ) .  , 367,371 | Great lymphatic vein 
——Meibomian . . . . . . 832 sympathetic system 
molar. . » «# @ BOSGTE | a structure . 
mucous of stomach >= = a « Jol transverse cerebral fissure 
NGOS. as a a Ge ay a BFE Grey nerve-fibres 
odoviferous . . . . . 445 root of optic nerves 
Pacchionian . . . . . 668 substance of isthmus . 
palate, soft . . . . . 343,370 | Gubernaculum dentis 
pancreas . . 427 testis i 
parotid . . . ‘363, 370, 371 | Gum. 
Pecklin,of . . . . . . 404 | Gustative bulbs . 
peptic. . 2. . © « » « 891 éélls 
perspiratory . . . . . . 794 | Guttural pouches 
Peyer's. 2 2 1 . « ) . 404 | Gyrus fornicatus 
——pharyngal . . . 2. . 643 
pinesl. . . . «6680 | Habenm . . 
—— pituitary . . . . . . 445,681 | Hemalarch. . 
popliteal . . . 2. . .) . 6640 | Hamaties 
preputial. 2 . . . . . 867 | Hairs 
precrural. . . 2 . 1. 640 
prepectoral . . . . . . 648 
prescapular . . 2.) . (644 
prostate . . . 2... 864 
racemose. . . . . . 329,339 horse, of . 
rectum,of . . . . . . 640 sheath of . 
salivary . . . «. . « . 864 | Haller’s passage 
simple. . . . . . . . 829 | Hand =. 
—— socia purotidis . . . . . 3872 | Harder, glands of 
— solitary . 2... .., 404, 410 Har Rania suture 
—splen,of. . .. . . . 642 Haversian canals 


. . 


follicles 
formation of . 
functions , 
germ of 


staphylines . . . . . . 3870 | Head, bones of . 
stomach,of . . . . . . 641 
subglossal . . . . . . 644 | Heart 

sublingual . . . .) . 869,371 action . 

sublumbar. . .. 638 capacity 
submaxillary... 367, 371, 644 | —— direction 

sudoriparous . . . ww 794 external conformation 
thoracic 2 «4 « « » «» « 642 form . i 


ingeneral. . 2. . 


——thymus . . . . . . . 473 | —— general sketch. 

=——thyroid , 2. «@ «© « « « 472 | ——~ interior x i 
tracheal . 2... «. « . 6489 nerves and vessels ‘of 3 
tubulat’ . 1 «6 «© « « « 829 serous membrane . 
uterine. . . . .) . ) . ) . 879 | —— situation 
utricular . . . ) .) .) .))6 880» | ——structure . 
vulvo-vaginal,. . 2 . .) . 6887 volume 

Glandular culs-de-sac . . 1 1. 865 weight. 
tIssle ow we 4 ee 4 | Helicine arteries 

Glans clitoridis . . . . . . . 882 | Helico-trema “ 
penis: 2 sk os . . 862 | Hemispheres, cerebral , 


Glenoid cavity . . . . . « « 73 | Hepatic cells 


Glisson, capsuleof . . 2 2. . 422 ducts 

Globes of segmentation. . . . . 891 lobules eck 

Globus major i aa - . » . 859 | Hernia, inguinal . et, ae 
minor. . a oe = tb Herophilus, wine-press of : 


Glomes of frog . . . . . ~ . 807 | Highmorianum, corpus . 
Glomeruli of kidney » oo. « « . 488 | Hilum of kidney 


INDEX. 


938 
PAGE 
Foramen obturator. . . . «. + 93 
occipital 5 a, 8% 
ovale - 40,503 
rotundum . a 220) 
Soemmering, of 836 
spinal é 19 
spinosum . 40 
stylo- -mastoid . 43 
subpubic 93 
subsphenoidal 40 
superciliary 36 
supersacral a 27 
supra-orbital . . . 36 
trachelian 34 
vertebral . wb. 
—— Vidian 39 
Winslow 383 
Forceps major 699 
Fore-arm, bones of . 75 
Fore-foot, bones of . 7 
Fore-lock P 797 
Formation of embryo » 905 
Fornix . . ‘679, 692, 694 
Fossa centralis retinze . . . 836 
ovalis . 506 
navicularis . 862 
Fossulate papille 336 
Fourchette ‘ 889 
Fourth ventricle of brain : 679 
Fovea centralis . 836 
Frenum lingue . 335 
preputii 872 
Frog of hoof ay ae 807 
Frog-stay . . . . . 807 
Frontal horns i 813 
sinus. 446 
Functional vessels of lungs” 470 
Fundus of bladder » . 491 
Fungiform papille . . 836, 874 
Funicular ligaments . 125,126 
Furrow, primitive . 892 
Galactoferous ducts . . . . 884,885 
sinuses $i ab. 
Galeati’s glands . ‘ 403 
Ganglia . é 780 
structure ib, 
Andersch’s 727 
—— Arnold’s or 720 
—— cervical, inferior . 784 
— middle ib. 
— superior , 782 
ciliary. . 718 
—— Cloquet’s . ib, 
—— Ehrenritter’s . wu, 929 
Gasserian . - 710, 711 
geniculare 722 
guttural . . 782 
-—— hypoglossal . . 739 
inferior cervical P 784 
intumescentia « s « 
jugular 5 . 728,729 
lenticular . > » 418 
Meckel’s i . 719 


Ganglia, middle cervical 
naso-palatine . 
ophthalmic 

OHe « « » # 
petrosum . 

semilunar . 

solar i 
spheno-palatine 
submaxillary . 

superior cervical. . 
Ganglion cells 

Ganglion, intercarotid . . . 
Ganglionic nerves . 2 1 
Gasserian ganglion. . . . 
Gastro-colic omentum . 
Gastro-hepatic omentum 
Gastro-splenic omentum 
Gelatine of Wharton 
Gelatinous substance of Rolando 
Gemmation . 

Generative apparatus 

ot Birds , 

Genital duct 

gland . Arad 

organs of female . 

of male . 

tubercle aa 
Genu of corpus callosum . 
Germ of hair 

Germinal eminence . 


spot 

vesicle i 
Ginglymus 
Glandule agminate 

solitari ie 


Glands = ie sey coe a ab de 
agminated . 2. . 
Bartholine, of 
brachial. 

Brunner, of 

—— cecal 

—— ceruminous 
—— cheeks, of . 
—— coccygeal . 


colon,of . . 
conglomerate . 
Cowper’s ‘ 
cutaneous, of Pig . 
duodenal . 
Duverney, of . 
follicular . 
Galeati’s . 
gastric. . 
genital. . 
—— guttural 
Harder’s 
honeycomb, 
iliac * 
inguinal, deep . 
superficial 
intestinal . 
interungulate of Sheep 


ae ig os a? ES 


oe © © © © ee He we eee ee he ee 


labial 
—— lachr ymal 


PAGE 
784 
718 
786 
720 

« baa 
711, 786 
| 786 
» aa 
» ¥% 
782 
653 
789 


» 652, 701 
. 710, 711 
| 382, 389 


. 
. 
. 
. 
. 
. 
. 
. 
. 
. 
. 
. 
° 


389 
383 
900 
670 

3 

851 
889 
923, 

ib, 

872 
851 
924 
693 

. 798 
. 873 
ib. 


* 93, 905 


. 128 
404 
404 
329 
404 
887 
644 
403 
641 
846 
332 
781 
641 
329 
B64 
794 
403 
. 872 

339 

403 

391 

923 

643 
3, 836 

404 
- 640 
- 638 


We © «© « « 


8 


ib, 
641 
794 


i 331, 339, 370 


- 834 


INDEX. 


PAGE 
Embryonic area... * a @ 892 
Emergent veins of spinal sinuses . . 609 
Eminences . . . . - dil 
Enamel 345, 346, 921 
Enamel organ ‘ 347, 921 
Enarthrosis . gy shod 
Encephalic arachnoid 664 

duramater . 2. . 1. 1. (662 

piamater. 2. 2. . 2. . . 666 
Encephalon . . . eos Se ae TORE 


asawhole . . ... . ab, 
constitution . . . . . Oo, 


general form . . . . ad. 
isthmus . . . . «6673 
volume . 2... OD 
WEIGH ew mI 
Endocardium . . . . . . . S11 
Endolymph . ee we ae « BEF, 840 
Ensiform cartilage 4 - oe 67 


Envelopes of cerebro-spinal. axis . . 660 


Ependymis of ee cord . 668, 683 
Epidermis  . b&w we 9S 
growth ae i's) Uae) Lao SESE: 
— structure . ge ie GP fan bee. GA 
Epididymis . . 2. 2. 1. . . 858 
structure, . . . . . . 859 


Epiglotttis 2. 2. 2. . 1. 1 451 
Epithelial cells . 2. . 2. ww, 4 


m——f1S0 . s % % 2 » & 8 4 
Epithelium . . 2. . . . . 827 
ciliated 2 g 8 ww & & ab. 
columnar. . . . . ab 


cylindrical 2. 2. 2...) 
pavement. « «© « «© « » 
simples =. 6 oo» 8 «© «© » (Be 
spherical . 4 6 3 « «& 
squamous. . . . . . .  % 


stratified . 2. 2. . 1 1 ot 
Erectile tissues . 2... - . 578 
Ergot . 797, 802, 812 
Ergot of Morand io. 8 = « 699 


Essential organ of vision . 2. . . .816 
Ethmoidal lobule . . 691, 692 
SINUS 3 os @ a w & wm AST 
Eustachian tube . 841, 844 
valve , » . . 506, 514 
External auditory hiatus » 1... 846 
Hye. 2 « « ¢ | = # so o 81% 
Eyelashes . . . . . 1... 832 
Eyelids ‘ . 816, 830 

commissures F - 830 
integuments . . . . . . 832 
structure. . . . . . . 831 
Eye-vesicles, primitive. . . . . 908 


Faleiform ligament Bo See ae Si ee BBB 
Fallopian tubes. 2 2. . 1 1). «876 
functions . 2. . 1.) 
structure . 2... .) 


False glands se . 633 
nostril. . . - 6 2 « 440 
Falx cerebelli . o «& » @ G66 
geerebhvT oo» « « ¥ 662 


Fang of tooth oe a 345, 350 


937 

: f PAGE 
Fascia infundibuliform. . . . . 852 
Lata a see uk 2 Ren fe Ge gh ne ORE 
transversalis 242, 245 


Fasciculus, primitive . : : : « 178 
Fatty nucleus of Baur. . . .. 337 


WAUCES os 6. eo eS ee ae. ag 375 

isthmusof . . . . . .) Oo. 
Femoral region. . . 1 283 
Fenestra cochlea . . . . . 838 


ovalis. . . . . 837, 840, S42 


rotunda , 838, 840, 842 
vestibuli a8 . 837, 842 
Fenestrated membrane. . . 519 
Betlocks i. 5. gy ye we ee we OT 
Fibres . $3 Se 4 
of Remak . 652, 782 


Fibro-cartilages, complementary » . 124 
intervertebral . 2. . . 130 
pedal bone . 2. 2). . 801 
Fibro-intestinal lamina, . . . . 906 
Fibrous tissue . 2... js 4 
Fibrous zones of heart . 2... 508 
Filiform papille, . . . . , 336,814 
Filum terminale  . 98 665, 908 
Fimbria of Fallopian tube. - . 876 
Fimbriated extremity of oviduct .  . ib, 


Fissure of Bichat . 2... . 691 
interlobular . 2... 690 
interpeduncular . . . . . 678 

=——splantar ~ = « 2 » & « 85 
of Sylvius . x « -2 697,692: 

Fissura glaseri . » = ¥ O8F 
longitudinalis, inferior . . . 668 

— superior . 2. 2 . . OD 
palpebrarum . 2... 881 

Flocculus . gre ae Oe oe Vy 89) 

Fluid of labyrinth ee» @ & » » BY 

Fetus, development of. . . . . 905 


circulationin, . 2. . . . 915 
Follicles, in soe e ee B05 


closed - . « . 840 
hair « es &® 4 » = “798 
Lieber kithn . 403 
mucous 327, 391 


simple, « « « « « »« » 403 
solitary . . . . . . 329,404 
structure of . . . . . 329,402 
ultimate . 2... 1). . (865 
Follicular glands . 2... . «839 
cavity of clitoris . . . . . 882 
Fontana, canalof . . . . . . 821 
Foramen of Botal ss 
cecum of Morgagni . . . «335 
of Vicq-d’Azyr. . . . 6858 
commune anterius . » 
posterius . . . . . 682 
condyloid . . 2 2 1 ew ew) 84 
infraorbital . . . . . . 44 
intervertebral . 2. «6 . . 24 
lacera basis cranii, . . 2.) O40) 
lacerum, anterior os « « « S4 
posterior «we @ se 
Monro, of. . . . 682, 693, 694 
putiient « « « » » « « 1 


936 INDEX. 
PAGE PAGE 
Differential characters, scapulo-humeral 144 | Differential characters, thyroid pee 744 
sternal . . . . 142 urinary apparatus . 495 
—_ — tarsal... . 172 | — venous system » . 625 
aa temporo-maxillary 139 | —— vertebral column . . . 29 
—_ —— tibio-fibular 168 visual apparatus . 835, 836 
— auditory apparatus . 850 | Digestive apparatus . 325, 330 
— axillary arteries 570 of Birds . . 435 
— brachial plexus . 763 | Dilator of the pupil. 824 
— carotid arteries . . . 590 | Dissection of arteries » 2 . 873 
— cerebellum . . . . . 689 | Discus proligerus . . . . . . 521 
— cerebrum . . . . . 698 | Dorsal nerves ; 750 
— cranial nerves 739 nucleus of Stilling . 671 


envelopes of cerebro-spinal 
axis. - . 666 


— external iliac arteries 555 
— genital organs of female 886 
— of male . . 867 
—— — great aionaong os - 789 
— head... « 4 150 
— heart . 513 
——— intestines 414 
— internal iliac arteries 543 
— isthmus of brain 685 
— liver 432 
— lumbo-sacral plexus T77 
—— — lungs . 470 
—_ — lymphatic system ® 645 
—— —- mouth . 356 
—— —— muscles . 

— -— abdominal - region 245 
—_— — anterior foot . . . 279 
—=——— arm. . 260 
—_ —. axillary region 235 
— — cervical region . . 201 
—_— —_— — inferior, . . ad 
—_ —_ —. superior . . 7%. 
— — costal region . 238 
— diaphragm 248 
—_— — facial region . 228 
—_— — forearm . 270 
— — — gluteal region 283 
— —. head . 2. 1. 228 
—— — — hyoid region . 230 
— — lee. a, . 306 
—— —— — masseteric region » 229 
—_ — panniculus carnosus . 187 
— — shoulder 254 
— —— spinal region . 209 
— — sublumbar region 215 
—— — — thigh . : 294 
— — tunica abdominalis 240 
— nasal cavities 448 
= cesophagus 380 
— pancreas 434 
—— —— pharynx i 376 
— posterior aorta . 535 
—_—_ —. limb 105 
— salivary glands . 370 
—— —— spinal cord 672 
Sora spine s 135 
—— — spleen » . 4384 
—- stomach . P 393 
— thorax . . 7 0, 466 
—— —— thymus gland oe! = eS 


vertebre .. oli! an ee 


Double-contoured nerve-fibres . 652 
Double semicircular centre of Vieussens 698 
Duct of Stenon . 367 
of Stenson 443 

of Wharton 369 

of Wirsung » . «428 
Ducts, accessory pancreatic. Seer er ab. 
biliary 423 
Cuvierian . 917 
genital 923 
—— guttural 844 
mammary . 884 
—— Miiller’s 923 
omphalo-mesenteric 894 
parotid 367 
perspiratory » . T94 
salivary . 367, 369 
—— thymic 474 
Ductus ad nasum » . 834 
arteriosus . . 470, 916 
choledochus . 424 
—— course 424 
—. structure 425 
cysticus » . 432 
ejaculatorius . - 860, 861 
galactoferus . 884 
hepaticus . 423 
lactiferus 884 
—— lymphaticus dexter » . 614 
pancreaticus minor - « 428 
prostaticus : 864 
—- Riviniani . 7 oe  « BES 
—— thoracicus . . © 2 w (684 
venosus of ‘Avanzi. » «  « 901, 916 
Duodenal glands ‘ . 403 
Duodenum 2 oe . 401 
Dura mater . + « 660, 661 
structure . 661 

Duverney, glands of - 872 
Ear, external ‘ - . 846 
internal nerves of - 887, 840 
middle ~ © » « « B80 
Ear-dust - . 839 
Ectopie of testicles | » 853 
Effluent canals of dura mater sinuses - 608 
Ejaculatory ducts - 860, 861 
Elastic fibres 4 Ge : 4 


Embryo-cells 
Embryogenous vesicle 
Embryology 


fe ae gg BOL 
s 2 2 6. 890 
soe oe ew) OB 


INDEX. 


PAGE 
Corpus rhomboideum » . 688 
: striatum . . . 693, 695 
Corpuscula tactus » . 194 
Corpuscles of Krause »  . 703, 832 

of Meissner . . . . . 703,794 

Pacinian 703 

terminal genital 866 
Cortical layer of kidney 487 
Corti, membrane of . 839 


Organsof os eee eS 


Coste . foe @ « # -» 6F 
Costal cartilages. eR wm oe ew on 368 
pleura . ‘ 464 
region , 235 


Cotyledons . ; ; . : . oe 
Cotyloid cavity. . 2. 2. . . OL 


Cowper’s glands 864 
Cranial arachnoid . . 1. 664 
cavity . 660 
dura mater 662 
membrane . 912 
nerves , 703 
— origin of. 704 
pia mater . 666 


Cranium, bones of . sk be ee 


Cremaster Be ae ot 852 
Cricoid cartilage . . . . 450 
Crico-thyroid membrane 452 
trachealis ligament 453 
Crown of tooth . 345 
Crura cerebelli . » « 678 
cerebri , . 675, 677 
offornix . . . . .  . 694, 695 

of penis a 864 
Crural aponeurosis . . . . . . 241 
apes oy es ey ee Ss as Gs 

bulb 668 
internal region 288 
Ting’. 241 

Crus ad medullam oblongatum 678 
cerebelli ad pontem Be oe 678 
Crusta petrosa 346 
Crypte mucose . 403 
Cryptorchids 853 
Crystalline lens . . 817, 826 
capsule of . 826, 909 

structure of . . 818, 826 

Cumulus proligeius 873 
Cuneiform cartilages 451 
Cutaneous gland of Pig 794 
lamina . 906 
Cuticle 792 
Cutiduris 803 
Cutigeral cavity. - . 806 
Cutis anserina . 793, 799 
Cuvierian ducts . 917 
Cysterna chyli 634 
Cytoblasts e 796 
Czermak, interglobular spaces of . 345 
Dartos hs Ger G5 853 
Deciduous teeth . ee . 348, 358 
Deferent canal é . 858, 859 
structure of. |), 860 


935 
PAGE 
Deglutition . 376 
Demours, membrane of . 827 
Dental follicle . 847, 921 
germ . 348, 921 
—— pulp 345, 347 
tubuli ci 345 
Dentated membrane 662 
Dentine . ia a Row me OHS 
Derma . Ce en ee er 
structure of . |, i = 998 
Descemet, membrane of —, 827 
Development of annexes of alimentary 
canal 920 
of auditory apparatus | 909 
— of brain ‘ 907 
—— of cephalic lamine | » . 905 
—— of chorda dorsalis ee ee 
—— of circulatory apparatus . 914 
— of cranium and face 912 
of digestive apparatus 919 


of fetus yas 905 
of genital organs . . . 923 
of genito-urinary apparatus . 922 
of gustatory apparatus 910 
—— of heart and vessels 915 
—— of lateral lamine . 905 
—— of limbs . ‘ 913 
— of locomotory apparatus r 911 
—— of lungs q 918 
—- of muscles 913 
—— of nerves 908 
—— of nervous system | 907 
—— of olfactory apparatus. 910 
—— of respiratory iid m 918 
—— of skeleton 911 
of spinal cord . 907 
of tactile apparatus 910 
of thorax ; 915 
of urinary organs . 923 
of vertebral column 911 
—_ lamina . 905 
of visual apparatus & se 1208: 
Dewlap . .. a Sig) ae Ba co OG, 
Diaphragmatic pleura 464 
region . 245 
Diarthroses , 123 
Diastole of heart ay nb get IOS: 
Differential characters in abdominal 
cavity . 384 
— air-tube . 3 461 
— annexes of fetus . 901 
— anterior limbs . . . . 86 
— apparatus of taste . . . 815 
— articulations. 
— — atlo-axoid . . 135 
— —. carpal . : _155 
—_— — chondro-costal 142 


coxo-femoral . « 162 
femoro-tibial & % Wee 


—_ — humero-radial_—. 146 
— —— interphalangeal, first. 157 
——————— second 158 


occipito-atloid . . 137 
— —— ——radio-ulnar . . . 147 


934 


Commisures of vulva . . 
Common aorta 


Comparison of abdominal cavity 


of abdominal limb . 

of annexes of fetus 

of aorta 2 
of apparatus of taste . 
articulations, carpal . 
coxo-femoral 
humero-radial 
interphalangeal . 
radio-ulnar . 
scapulo-humeral 
tibia-fibular 
auditory apparatus 
axillary arteries 
bromchi  . a 
carotid arteries 
cerebellum 
cerebro-spinal axis 
cerebrum , i 
external iliac arteries 
genital organs, female 
male 


ee 


head 

heart 

—— internal iliac arteries . 
intestines . 5 
isthmus of brain . 
larynx . 

liver . . 

lungs 

mouth . 


arm . 

back . 

costal region 
diaphragm 
fore-arm 

—— gluteal region 
hand 

head . 

leg. 

shoulder 
sublumbar region 
thigh 

nasal cavities . z 
nerves, brachial plexus 
cranial 


OeU eee e ee aaal 


cesophagus 

pancreas 

pharynx 2 
salivary glands 

spleen . 

—— spinal cord 

stomach . 
thoracic limb. , 
thotax., « « « « 
— thymus gland. . . 
—thyroid gland. . 
trachea. . 
—— urinary apparatus | 


muscles of abdominal region $ 


great sympathetic : 
lumbo-sacral plexus 


INDEX. 


PAGE 
882 
522 
385 
187 
904 
538 
814 
156 
163 
147 
159 
148 
144 
168 
850 
574 
472 
595 
689 
666 
698 
557 
888 
871 
63 
514 
545 
417 
685 
471 
434 
472 
362 
245 
260 
209 
238 
248 
274 
283 
279 
230 
310 
255 
215 
295 
449 
767 
740 
789 
778 
380 
434 
377 
372 
435 
672 
400 
89 
Gly 
475 
ad. 
472 
496 


PAGE 
Comparison, venous system  . . . 626 
vertebral column. . . . «82 
visual apparatus . . 836 
Complementary 4 2 cals of pedal ‘pone 801 
Composite nerves . : 753 
Compressor vesicule . . . . . 860 
@onaviam . « « « «© « » » 680 
Concha auris. . Cee . . 846 
cartilages yom a me ae be 

muscles. . . 0. «oo 

Conchal cartilage . 2. . . we 
Confluent of jugulars . «ewe BOL 
Confluents of subarachnoid fluid | . 664 
Congestion of liver. . . . «427 
Conglomerate glands... »  . 829 
Conjunctive. . . . . . . . 832 
Conjunctival tissue. 2. . 1 4 
Connective cells. 2 2. 2. 1.) Oo 
fibres oe ee ep > we ODE 
ISSUCL sie ae ae GMD Wa cd at DR 
Consistence . . . 2 . ww (829 
Contractilecells . 2. . . . . 4 
fibrille . . ‘ - 18 
Convoluted tube of kidney . : . 488 
Coracoid process . . . . . . 73 
Corium cutis - . 792, 793 
Cornea... pb ls SG® Neo ba ABD 
structure of pl ae ig RS ag edt. SDs 
Cornu Ammonis . 679, 695 


Cornua of spinal cord pide hen as eee 
Of uterus: 6 we a ey | 8 
ofventricles . . . . . . 695 


Corona glandis . . . . . .) .) 866 
Corone tubulorum . . . . .  . 404 
Coronaria ventriculi . . . . . 527 
Coronary cushion . 2. 1... 808 
ligament ee § 6 we OB 
substance . . 1 www eB. 
structure . . . . . 804 

Corpora albicans vel nigrum . . 875 
cavernosa. . » oe . 6865 


—— fimbriata of fornix ‘ eg ae “69H 
geniculata. . . . . . « 680 
Malpighiana Se El eh ae SSS) 


———MISTa 8% ye a a we 829 
—— pyramidalia . 676, 684 
quadrigemina . . 675, 679 
restiformia . 677, 684 
Corpus albicans . 4% ow & 848,695 
Arantius . . . . . . . (505 
callosum » 692,693 
cavernosum . 864, 865 


external conformation » « 6G¢ 
structure . . . . . 865 


Clare se es we he a ww BOL 
dentatum . . . . . . , (688 
—fimbriatum . . 3 « & “69S 
geniculatum, externum » . « 680 
— internum . , . . 679,680 
—— Highmorianum, e y « » S854 
luteum < ar 874 
— false . ee ew a 85 
— HTUG so @ 8 Be wD 
OMUVENE: as - « 677 


INDEX. 


PAGE 
Cells,nerve. . . . 4, 652 

olfactory . Pe 445 
Cellular tissue . 2. 2. 2. . we 4 
Cementum ‘ : 345, 346, 921 
Central canal of spinal cord . . . 668 


Central suprahepatic veins . ‘ 
Centres of ossification . . . . . 16 


Centrifugal conductibility . 656 
nerves... ee ab. 
Centripetal conductibility Be wigs 1 Sai ag THD 
merves., . a ae ib. 
Centrum 118 
ovale of Vieussens 607 
Cephalic hood és 893 
lamine 907 
Cerebellar crura 678 
peduncles . 675 
ventricle 679, 683, 688 
Cerebellum . . 672, 686 
external conformation 686 
internal conformation 688 
Cerebral hemispheres ~ . 673 
peduncles . . 675, 677 
— trigonal 679 
ventricles . 692 
vesicles 907 
Cerebro-spinal axis . 651 
nerves 700 

Cerebrum » » G8 
convolutions . 689, 691 
external conformation x « « weO 
hemispheres . . 689, 691 
structure . 697 
Cerumen 846 


Ceruminous glands Mette ee Gg ye ge SO 
Cervical ganglia 782 
nerves , ei 784 
vertebra «| 2 = « «= « » @L 


Cervix of bladder . . . . 491 
of uterus ¥ 877 
Chalaze . < & 925 
Chambers of the eye : «= ¢, SEF 
Cheeks . . ‘ 332, 356, 359, 360 
functions . . 332 


structure. . . 6. 1 + - 
Chesnuts 

Chiasma of optic nerves a 
Chorda dorsalis. . . . . . 892,905 


Chord longitudinales 693 
tendine . . . 504 
vocales ao ee MS 452 
Willisti 2. 2. 1. 1. ee . 606 

Chorion of skin ae ae te 792 
offetus . 2. 1. . 895 

definitive. . « + 896 
primitive acy ge de ee Ws 

Choroid membrane or coat. . . . 820 

— anterior one a RDS 

—_ — posterior . . . wd. 

— structure . 821 


plexus, cerebral . . ‘ : 693, 696 


Zoue. « « » & & © « « 820 
Chyle . . 6 6 ef e 8 498 
Cicatricula . 2 6 2 ee we 925 


62 


933 
ee ae 
Ciliary body. . 2. ee. 821,822 

COMAL gos A Re es BP ey BOE 
circle. oe we a we oe 1820 
ligament . XG . 821, 822 
—— processes . . 6 « » 821,822 
zone, yi te ve ote hae “B20 
Ciliated epithelium Sys HF 1 9a, he Grn Se SO 
Circulation, adult 498 
fetus “ % 914 
Circulatory apparatus . 498 
in birds . , . 647 

Circulus venosus orbiculi ciliaris 821 
Circumvallate papilla . 336, 814 
Cistern of Pecquet . ‘ 634 
Clark, vesicular column of . 671 
Claws . . . 812 
Cleavage masses 891 
Clefts, pharyngeal 912 
Clitoris tt de 882 
pr eputium eae anne! 
Closed follicles . - 340 
Coat. . 797 
Coceygeal gland . 781 
muscles 215 


nerves . msde Ke 753 
vertebra . 6 6 1 ew we le OF 


Cochlea . ‘ 837 
membranous . 839 
Ceeliac axis : 527 
Cohesion we te ae ae ee, 9889 
Colic mesentery. . . . . . 383,413 
Collateral scala. «2 . 839 
vessels . a 517 
Colon sh @ igh br Sey retard, es HALO 
double. . . i ow: cad: car. CWDS 
— attachments Se) Sen ey ee OL 
— capacity. . . 410 
— course « « « 411 
— form . a Ata Sr 008 
— functions oo te 413 
—- length 410 
—_ relations 411 
—— structure ‘ 412 
— small... & «2 2 ee 808 
— attachment . 413 
— course : ‘i 412 
— form . fe Sis i a. 
— interior . eo i 8 413 
— length cy ; 412 
— relations . . . » 
structure 413 

Colostrum . * 886 
Column carne kt Sen 4 503 
papillares. 2. 2. 2. 1 + 
rugose =. sa & = « 2880 
Columnar epithelium s & & « B2F 
Columns of spinal cord. , . . 669,671 
Commissures of frog . . » >» + 807 
ofinguinal canal. » . « » 242 
oflips. . . » + + 83l 

of nostril . . 440 

of optic nerves . . . 707 

of spinal cord 5 669 


Preparation, articulations, costo-sternal 
coxo-femoral 
femoro-tibial 

—— first interphalangeal 
—— humero-radial 

—— hyoideal ‘ 
interphalangeal, fir st 
second é 
metacarpo-phalang’ eal 
occipito atloid 

pelvis é 
scapulo-humer: al 
spine, of 

tarsus 
temporo- maxillary . 
auditory apparatus 
brachial plexus 

bronchi 

choroid coat 

cornea , 

cranial nerves 

ear, internal 

encephalon 

eye. 

great syinpathetic nervous s system 
heart : ‘ 


CETTE 


structure ae 


hoof 

internal ear 

intestines . 

larynx . 

liver 

lumbo-sacral plexus 

lungs . 

lymphatics 

maxillary gland 

mouth 

muscles : 

abdominal region, inferior 

alveolo-labialis . 

anterior brachial region 

crural region . 

medius 

axillary region . 

brachial region, anterior 

posterior 

cervical region, inferior 

superior 

costal region 

crural region 

anterior . 

internal . 

posterior 

—— —— diaphragmatic region 
external scapular region 

eye e i 

femoral region “ 

flexor, short, of fore-arm 

for earn, of 

—— —— gluteal region 

—— —— hyoideal region . 

inferior abdominal region 

cervical 

lumbar region 


INDEX, 


PAGE 
141 
161 
163 
156 
144 
139 
156 
157 
153 
137 
159 
143 
130 
168 
138 
837 
755 
460 
820 
819 
705 
877 
674 
817 
781 
503, 
507 
799 
877 
400 
449 
419 
770 
466 
633 
367 
330 
184 
220 
218 
255 
283 
231 

ib, 
255 
258 
196 
187 
235 
283, 

ab, 
288 
286 
245 
249 
828 
283 
256 
261 
280 
225 
239 
196 
211 


951 
PAGE 
Preparation, muscles, internal scapular 
region . 252 
— labialis 217 
—= 16S pe 297 
se lumbar region, inferi ior. 211 
—— —— masseteric region 223 
—— —— mastoido-humeralis . . 196 
— medius, anterior « 222, 223 
— panniculus . 186 
— scapular region, external 249 
SSS internal . 252 
— spinal region of back and 

loins 203 

— sublumbar region 211 
— superior cervical tae aE 
— temporo-maxillary region , 223 
—— nasal cavities . ee 440 — 
— esophagus . , 377 
—— palate . 332 
—— pancreas 419 
parotid gland . 365 

—— pericardium 512 
—— pharynx 372 
retina . 824 

soft palate 340 
spinal cord 666 
spleen . 419 
stomach a ee 385 
submaxillary gland. 5 367 

——- sympathetic nervous system . 781 
— thoracie duct . : 643 
tongue 334 
trachea 457 
urinary apparatus 484 

veins % 8 599 
Prepuce . ‘ 867 
of clitoris . 882 
Preservation of muscles 185 
Primitive aorta . 915 
band of Remak 652 
chorion 896 
eye-vesicles . 908 
fasciculus . , 178 
furrow... 892 

trace P a. 
Primordial kidneys . ‘ 922 
Processes e cerebello ad testes % _. 678 
Promontory of ear . 840, 842 
Properties of nervous system . 655 
Prostate gland 864 
structure ab. 
Protoplasm ¥ 3 
Protuberantia annularis . . 675 
Protovertebre . .  . 905, 911 
Protovertebral cavity a> ab . 905 
Pulmonary artery . . o 521 
heart : Ske 503 

lobes . . . 466 
lobules ‘ * 468 
opening of heart fe 505 
ple. so oS ew 464 
tissue . 1. & 467 
vesicles a er ee 468 
Puocta lachrymalia . . . . 834 


952 


Punctum cecum 

Pupil : 

Pupillary membrane 

sphincter 

Purkinje’s vesicle 

Pylorus . 

Pyramidal eminence ‘of os pedis 
Pyramids of the bulb 


Racemose clands 
Rachidian bulb . 
Raphe of scrotum 
Receptaculum chyli 
Recto-vesicle fold 
Rectum . 
attachment 
development 
relations 
structure . 
Recurrent sensibility 
Reflex power 
Reil, band of 
Reissner, membrane of 
Remak, primitive band of . 
Renal glomerules 
pelvis . 
Reseau admirable 
Reservoir of thymus gland . 
Respiratory apparatus . 
of Birds . 
of Mammifers 
nerves 
Rete mirabile 
mucosum ,. 
ophthalmicum . 
testis 
Reticular layer of the derma 
Reticulum . 
structure . 
processigerum 
Retina 
Retrossal process of os pe lis 
. Rhomboidal sinus 
Ribs : 
Right auricle of heart 2 
ventricle ,, 
Rima glottis 
Ring, inguinal 
pancreatic : 
umbilical, inferior 
Vieussens, of . 
Rings of trachea 
Rivinian ducts 


Rolando, gelatinous substance of 


Root of lungs 
Rosenmiiller, organ of 
Rudimentary sinuses 
Rumen 

structure of 


Sacculus ofear , 
Sacral nerves 
Sacrum , 7 
Salivary glands 


"590, 591, 


593, 594, 631 


INDEX. 


PAGE 
824 
822 
824 
823 
925 
388 

85 
676 


. 329, 339 
675 
853 
634 
860 
413 
413 
920 
413 
414 
650 
657 
678 
839 
652 
488 
486 
593 
473 
439 
475 
439 
704 


796 
595 
855 
793 
397 

ab, 

613 
824 

85 

907 

67 

505 
503 
456 
242 
427 
894 

506 
468 
369 

. 670 
461, 466 
: 866, 923 
606 
394 
396 


839 
752 

26 
364 


Salivary glands, development of 


ducts 
lobules 

Saphena veins 
Sarcolemma 7 
Sarcous elements 

Scala, auditive . 
collateral . 
Lowenberg’s 
— tympani 

vestibuli 

proper 
Schindylesis 
Schneiderian membrane 
structure of 


Schwann, white substance of . 


Sclerotica 

Sclerotic cleft 

Scrotum ‘ 
Scutiform car tilage | 
Sebaceous glands 
Secondary dentine 
Segmentation of vitellus 
Semen 

Semicircular anastomoses 
band 

canals . 

ganglia 

valves 


Semilunar crest of p pedal bone . 


fibro-cartilages 
Seminiferous tubes ¢ 
Sensitivo-motor centre . 
Sensorial functions 
Septum auricularum 
lucidum 
pectiniforme 

scroti . 
ventricularam. 
Serous burse 

membrane - 
stratum of epiblast 
vesicle ‘ 
Sesamoid bones . 
Sheaths, arteries of 

hair of 

—— lymphatic : 
metacarpo- phalangeal 
navicular sop 
ocular 

penis, of 

perforans tendon, of . 
Schwann, of 

tarsal . 

Shell, ege of 

membrane 
Shoulder, bones of 
Sigmoid valves . 
Simple follicles 

glands 

placenta 

Sinus ampullaceous 
aortici 

cireularis iridis 


‘ 838, 839 

‘ b. 

e « Bog 
129 
dit 


; ol 445 


652 
817 
909 
853 
846 
794 
347 
890 
857 
555 
680 
837 
711 
505 
84 
163 
855 
657 
658 

. 603 
692, 694 
. 865 
853 
503 


72 

505, 507 
404 

329 

903 

839 

522 

821 


INDEX. 


PAGE 


Sinus cutaneous ungularum » 724 
lactiferus - 884, 885 
pocularis » » 861 
renalis x « . . 486 
rhomboidalis . . 683, 907 
terminalis ~ » STS 
Valsalve .. 522 

Sinuses, structure of 597 
aortic e 522 

—— dura mater, of 605 

— in general 606 


in particular. 2. i 


cavernous. . . 2. . we) oD 
falxcerebri, of . . . . . oa. 
—median . ane: > Bet, “ABs 
occipito-atloid | 2: SS, fee wb, 
petrosal . 2 1. ww. Ot 
rudimentary . . . » th 
sphenoidal : 447 
spinal in particular 608 
transverse - 606 
—— galactoferous . 884, 885 
head, of z 446 
— development of 447 
— functions of 448 
— ethmoidal 447 
— frontal . 446 
—— —— maxillary, inferior . 447 


superior . . 2. . ot. 
sphenoidal . . . 2.) OD 


lymphatic 532 
palpebral . 850 
renal 486 
rhomboidal 683, 907 
—— subarytenoid : 456 
subepiglottic . 2. . 2. . . ot 
terminalis 915 
Valsalva, of 522 


Skeleton a eLN9 Gn fos er an 7 


Skin ny daa? Jin 792 
appendages of 797 
derma BL ORS tee ret og 9) OS, 
epidermis . 795 
functions . 796 


structure... »  . 792,796 
Small intestines : 


Smegma preputii 867 
Smell, apparatus of 815 
Socia parotidis 372 
Soemmering, foramen of « » 836 
Soft palate Zo Bes 340, "357, 359, 360 
Sole of hoof ee te zi . 807 
Solid organs. . 328 
structure of. . 328, 329 

Solitary glands . . 404, 410 
Speculum Helmontii 246 
Spermatic cord 856 
Sphincter ani 414 
pupillaris . - . 823 
vagina . 880, 883 
Spinal arachnoid 663 
canal 659 

cord . . 6 2 666 
— external surface of . 668 


953 

PAGE 

Spinal cord, figure . ib, 
general view of 666 

— internal conformation 668 
a structure a 668, 669 
— volume . i 668 
— weight : ab, 
—— dura mater j 661 
—— marrow ; 651 
—— nerves a A 747 
— constitution . 748 
—— nerve-tubes of . 671 
pia-mater . 665 
Spine, the, in general 28 
Splanchnology 326 
Spleen 428 
attachment 429 
development 922 
direction 428 

form id. 
functions . 431 
relations 428 
situation . ib. 
structure . 429 
weight wb. 
Splenic corpuscles 430 
pulp . . 429 
Spongy portion of urethra 4 862 
Spontaneous voluntary movements 657 
Stapes : : 843 
Staphyline glands f 370, 371 
Stars of Verheyen . 489 
Stenon’s duct 367 
Stenson’s duct . ‘ 443 
Stilling, dorsal nucleus of . 671 
Stomach in Solipeds 385 
development 920 

— dimensions . 386 
— form ib. 
— functions 393 
— interior 388 
—— —— ligaments 389 
—— —— muscular membrane tb, 
— orifices 388 
— situation 886 
— structure 389 
— Carnivora . 393 
— Pig ib. 
Ruminants ib. 
functions « ogo 
Subarachnoid fluid . 663, 664 
Subarytenoid sinus 456 
Subcorneous integument 803 
Subcutaneous region 106 
Subepiglottic sinus 456 
Subhepatic veins 423 
Sublingual crest 334 
gland . . 369, 371 
Sublobular veins . 424, 425 
Sublumbar reservoir . 2 634 
Submaxillary gland : . 567, 371 
Subpodophyllous reticulum 613 
Subsphenoidal confluents 608 
Substantia gelatinosa 670 
ostoidea 346 


954 INDEX. 


PAGE 
Substantia perforata . . » 692 
Suburethral notch , 2 «6 « 866 
Succus prostaticus . . «6 =» 864 
Sudoriparous glands . «6 « 794 
Sulci horizontalis 2 8 8 686 
Superior umbilicus re 893 
Suprarenal capsules rane 494 

development . . 495 
— form se 494 


functions . « « 495 
relations . . . . . 494 


situation < £ © & ab. 
structure. -— *« # ab. 
Suprasphenoidal appendage . . . 681 
Suspensory ligament of fetlock . . 154 
penis 865, 866, 872 

— sheath o-% . 867 
uterus vos 2 es 8a? 

Sylvius, fissure of . 691, 692 
Sympathetic nervous system .  .  . 781 
functions + 489 

— Strwcture, x» a «26> 
Symphyses . 3 & ig x 1g ARO 
Synarthroses . fe oe WB 
classification of . . . . . 129 
Synovia . . ®t {Ete le Ses SR 
Synovial capsules a 3 ge Ue AS 
fOss@ 2 x 4 8 2% oy WB 
fringes 4 2 oe = dee 
Syntonine * ¢o6 @ @ « « AL 
Systole of heart be OS Se ve eS SOS: 
Tactile corpuscles Sa ee ee 708 
Tenia hippocampi . . . . 2. . 695 
semicircularis » » « 680, 695 

Wath a Me. Be hal bg 797 
Tapetum . . . 1. we 820, 822 
Tarin, valves of - 687, 689 
Tarsal sheath aig 0D 
Tarsi $. &. +881 
Tarsus s « 102 
Taste, apparatus of « « <813 
Teats eM - « 884 
Teeth Soo wl oe we ep 844 
characters of . . 2. tb 
development of . 847, 921 

— disposition of . . . . 344 
——eruptinof . . . . . 921 
—— external conformation , . 344 
structure e » « 9845 
ofCarnivora . . . . . . 261 
—Pig ....... . 859 
—— Ruminants ss « « 857 
Solipeds 2. . 2. . 1. . 4 849 
Tegumentary membranes . . . 5 
Temporal fossa . ow Pe we D. 
Yelachoroidea . . . . . 2.) . 696 


Tendinous sheaths a 
synovial membranes, . . . ib. 
Tendo-Achilles . . . . . ).) . 302 
Tendons , s « « 199 
anterior extensor of metacarpus 262 
common, of abdominal muscles , 240 
deep flexor . . . 1 4 . 268 


Tendons, extensor pedis 


flexor, of metatarsus 
hock . 
gastrocnemii 

great dorsal 


middle ,, 
oblique flexor 
perforatus 
perforans . 
prepubic 
Tentorium cerebelli_ 
Tentacula 

Terminal genital cor ‘puscles 
motor plate 
vessels 
Testaceous membrane 
Testes cerebelli . 
muliebres . 


Testicles 


—— descent of 48 
—— development of 

—— ectopix of 

—— envelopes of 

—— external conformation 
—— function of 

structure of 
Testicular cord . 

Thalami optici 

Thebesius, valve of . 

Theca vertebralis 
Thiernesse’s muscle 

Third ventricle of brain 
Thoracic aorta 


cavity . 
—— duct ae 
— affluents of . 
— course of 
— extent 
— origin 
— termination 

varieties in . 

Thorax 

functions of 

in general . 


situation 

Thymic ducts 

Thymus gland 
development 
functions 
structure 
Thyroid cartilage " 
Thyro-hyoid membrane . 
Thyroid gland 

functions 
structure 
Tibial aponeurosis , 
Tissues c . 
Toe-stay. . 2 6 « 


large extensor of fore-arm 
lateral extensor of phalanges . 264 


tuberoula . « « « 


attachment on 6) a 


internal conformation 


PAGE 
» . 263 


external flexor of metacarpus « 266 


300 
302 
ab. 
294 
258 


259 

« « B06 
. 267, 304 
267, 268, 305 
240 

. 662, 663 
. 797, 798 
. . 866 
. 180, 702 
517 

925 

- 678 
872 

» . 679 
. 851, 853 
853 

ve 94S 
» 856, 923 
853, 

852 

853, 

857 

854 

ig hoy ab. 
. 675, 679 
506 

661 

264 

682 

524 

462 

634 


Tongue 

conformation of 
development of 
functions of 
—— muscles of. 
—— pillars of . 
situation of 
structure of 
Tonsils i 
of cerebellum ‘ 
Torcular Herophili . 
Trabecule of spleen . 
testis 

Trachea . 
course... 
development 
form 

relations 
structure . 
Trace, primitive . 
Tracheal glands . 
Tractus longitudinalis 
opticus 
respiratorius 
Transverse sinuses 
Tricuspid valves 
Trifacial nerve 
Trigeminii 
Trigonum vesice 
Trisplanchnic system 
Trochlea . 
Trochlearis nerve 
Tuber annulare . 
cinerium 
Tubercula nates 
quadrigemina . 
testes 
Tuberculum Loweri 
Tubular glands . 
Tubuli seminiferi 
uriniferi 

Tuft of chin . i 
Tunic of plantar cushion 
Tunica abdominalis . 
albuginea of ovary 
of testicle 
erythroides 
Ruyschiana 
vaginalis 
communis 
propria . 
reflexa 
vasculosa testis 
Tympanal circle 
Tympanic scala . 
Tympanum . 
Ultimate follicles 


Umbilical cord . 
arteries. 
region . 

veins 

vesicle 
Umbilicus, superior . 


INDEX. 


307, 359, "360 
334 
920 
340 
336 
335 
334 
335 
835 
689 
606 
429 
855 
457 
ab. 
918 
457 
ab. 
458 
892 
459 
693, 

« WOT 
- 704 
606 
504 
710 
ab. 
493 
781 
128 

» F09 
« O77 
681 
679 
ab. 

tb, 
506 
322 
854 
487 
331 
802 
B39 
873 
854 


. 895, 900 

. 900 

. 381 

. 900 

894, sue 
893 


Unipolar nerve-cells . . 


Uniting tube of kidney . 


Unstriped muscular fibres . 


Urachus . 

Ureters 

direction 

form 

origin . 
structure . 
termination 
Urethra . 

male, of 
course 
interior , 
relations, 
structure 
female, of . 
Urethral ridge 

sinus 

Urinary apparatus 
Uro-genital sinus 
Uterine glands 
tubes 


functions of . 
structure 


Uterus 
attachment 
development 
form 
functions 
interior 
—— masculine . 
situation 
structure . 
Utricular glands 
Utriculus of ear 
prostatic 
Uvula of cerebellum 


Vagina 
functions 


situation 
structure 

Vaginal bulb 

sheath . 

synovial membrane 
Valsalva, sinus of 
Valves, Bauhin, of . 
bicuspid 
Eustachian 
ilio-ceecal . 
Kerking, of 

—— lymphatic . 
meatus urinarius , 
miltral 2s 

—— Renault, of 
semicircular 
sigmoid 

Tarin, of et Os 
— Thebesius, of . , 
tricuspid 


—— Vieussens, of . 


internal conformation 


veins,of . . , 4 


955 


PAGE 

. » 653 
oe 6 «6488 
. 327, 328 


506, 514 
" 402) 408 


Gg ge BOB 
. 505, 507 

. 687, 689 
506 

504 

. oe. 597 
.. 675, 679 


956 


Valves, vulvo-vaginal 
Valvule conniventes 
Varolii, pons 

Vasa afferentia . 


efferentia .  . 
inferentia . 
recta 
vasorum 

— of veins . 
vorticosa 


Vascular blood glands 

Vas deferens 

atrictore of 
Vegetative life, nerves of 
VEINS :—definition . 
external conformation 
general considerations 
injection of “ 
internal confor: mation 
structure 
abdominal, subeutaneous . 
alveolar 

angular of eye 
auricular, anterior 
posterior 
axillary 

basilic . 

basium vertebrarium | 
— buccal . 

cecal 

cardiac . 
cardinal, anterior’. 
posterior 
cephalic 

central of foot 

of retina 
cervical, superior . 
circumflex of foot 
collateral of cannon, external 
internal 
coronary, great 

-—— small 

of foot 

dental, inferior 
superior . 
diaphragmatic. 

—— digital . 

dorsal . 

femoral 

Galeni . 

gastric, anterior 
gastro-epiploic, left 
right 

— glosso-facial 

— hemorrhoidal 

— humeral 

iliac, common . 
external 
internal . 
ilio-cecal . 
innominate 
interlobular of liver 
interosseous 

—— intralobular of liver 


: 682, 855 


603, 


INDEX. 


PAGE 
887 
402 


* 675, 677 


632 


632 
855 
520 
598 
821 
330 
859 
860 
652 
596 
ab. 
wb. 
bog 
DoT 
599 
625 
602 
ab, 
604 
602 
609 
611 
131 
605 
620 
599 
917 
tb, 


, 611 


613 
825 
600 
613 
611 
tb. 
599 
ib, 
614 
605 
603 
617 
625 
600 
623, 
608 
621 
621 
tb. 
602 
621 
610 
622 
623 
622 
620 
603 
423, 
612 
424 


Veins, intra-osseous of foot, 616 
jugular F 601 
labial 603 
lingual 605 

—— mammary, internal 600 

—— maxillary, external 602 

—_— internal . 601, 605 

—— mazxillo-muscular . 601 

— median spinal . 608 

— subcutaneous 611 

—— mesenteric, great . 620 

— small 621 
meseraic, anterior. 620 

— posterior 621 

—— metacarpal 611 

—— metatarsal 624 


deepen. a4 a 4s 9 ie 
external, « « «© «# « ib. 


— internal . ib. 
nasal 603 
occipital : 602 
omphalo-mesenteric 915 

-——pelvi-crural . 2 1... 622 

—platt ... 603 
podophyllous . 613 
popliteal 623 
portal . i 617 
posterior communic: iting, of foot 615 

—— pterygoid . 605 

= pulmonary, - . 599 

—— radial, anterior . 610, 611 

— subcutaneous 611 

—— renal 621 

—— saphena, exter nal . 624 

— internal. . 2. - wb 

—— solar 612 

—— spermatic « 621 

—— splenic wb. 

—— Spry 610 

— subcutaneous, abdominal r 625 

— internal . 611 

— thoracic . 610 

—— subhepatic 619 

—— sublingual 603 

—— subscapular 610 

—— subzygomatic . « i 1605 

—— superficial temporal . 601, 603 

—— suprahépatic 619 
temporal, deep » . 605 

— superficial » 901, 603 
testicular . 622 

—— Thebesii 599 

—— thoracic, internal . 600 

—— thyroid 603 
tibial, anterior 623, 

—= posterior 624 
ulnar 610 
umbilical . 916 
ungual 612 

—— utero-ovarian . + . 622 
vertebral . oy Cas . 600, 917 
cava, anterior. 2. . 2. 1 ot 

posterior ab. 


Velum interpositum : 691, 696 


e 


INDEX. 957 


PAGE 


Velum pendulum palati 340 
vasculosum —, . . 696 
Velvety tissue of foot » 803, 804 
Vena azygos, great . 600 
small ab. 
—— cava, antewor 600 
—_— posterior » « 617 
—— Galeni . . 691, 696 
porte , 617 
Vene comites 508: 
vorticosa ‘ . 821 
Ventricles of brain . 682, 683, 692, 693 
cerebellar 688 
— cerebral . = « 693 
—- lateral . 692, 693 
—— —— middle 682 
ere posterior 683 
—— —— third 682 
— thalami optici of 628 
of heart 500 
of larynx : 456 
Ventricular arachnoid . 694 
mass of heart . 500 
Vermiform appendix 418 
processes of cerebellum 686 
— anterior ib. 
posterior ab. 
Vermis of cerebellum 687 
Vertebrz ‘ 18 
characters common n to 19 
— proper to . 21 
development 20, 911 
structure . 5 20 
Vertebral column 18 
development of . 911 
constitution of skeleton 118 
lamine 905 
Vertebro-costal channels 462 
Veru montanum 861 
Vesicle, serous 893 
umbilical . 899 
Vesicles, Graafian 873 
pulmonary 468 
Vesicula alba 894 
seminalis tertia 861 
Vesicule seminales . 860 
Vestibular scala 839 
Vestibule of ear 837 
Vibratile cilia 327 
Vibrisse 449 
Vieq-d’Azyr, cecum of . 658 


PAGE 
Vidian canal «wl, ‘ 724. 
fissure . . . . ‘ tb. 
nerve. . s @ @ W19 
Vieussens, centrum ovale of . 697 
Villi, intestinal pn eo 402 
Villosities . . soe oe vy 327 
Villo-papille of foot |)... 808 
Villous loops of foot 2. ww. ot 
Vitellus a a ce . 873, 890 
Vitreous body . .. : 827 
humour . . © 4 ab. 
Viseetw sw « , s -¢ & B25 
Visceral pleura. . . . , . . 464 
Vision, apparatus of . . , . . 816 
Vitelineduct . 2. 2 1... 894 
globitles: «ge a ow ow 9S 
Vocal cords) « 2 s 3 « « « 402 
superior . . 453 
Voluntary movements. . . . . 658 
Vulva: 2 8 os we ew wt wm ws 882 
cavity of .. a a ge ag 18s 
external opening aoe le a. 
structure. . . . . .) . 883 
Vulvaofbrain. . . . 699 
Vulve, labia 2... . 882 
Wall of hoof 805 
angle BE tak tas Um a. 
structureof . . . . a 
Wharton’s duct - 2 2 2 : « 868 
gelatineof . .. » . 900 
White line of hoof . . . . 812 
substance of Schwann. ww 652 
— spinal cord... j 671 
longitudinal fibres of brain 685 
transverse 9 5 ie ae, aDs 
Wilson’s muscle ‘ é 862, 863 
Winepress of Herophilus : « » O06 
Winslow, foramen of . ‘ 383 
Wirsung, duct of 2. 2. 2. 1... 428 
Wolffian bodies . fo) 922, 923 
Wrisberg, nerve of : . . 728 
Xiphoid appendage of sternum . 67 
Yelk 2. 2... . 873, 890 
Yolk of egg . » + 925 
Zona pellucida . . 873, 890 
Zouula ciliaris ‘ . 821, 824 
of Zinn B, (aee ruey ae Oe tb, 
Zojsperma . . Sa a ae F888: 


Siesgete 


y va 

Vesa 
Catt 
nie