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Curnrnings School of Veterinary Medicine at
Tufts University
200 VVestboro Road
Morih Grafton, MA 01 536

THE

ARTISTIC ANATOMY OF ANIMALS

ARTISTIC
ANATOMY

BY-EDOUARD-CUYER/SUPPLEMENTAKiP
PROPOFANATOMVATTHE-SCHOOLtOF-

FINEART-PARISyPROFOFANAlOMY
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LECTURERiONANArOMYATTHE'R^iAL

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PREFACE

A FEW lines will suffice to explain why we have compiled
the present volume, to what wants it responds, and what
its sphere of usefulness may possibly embrace.

In our teaching of plastic anatomy, especially at the Ecole
des Beaux- Arts — where, for the past nine years, we have
had the very great honour of supplementing the teaching
of our distinguished master, Mathias Duval, after having
been prosector for his course of lectures since 1881 — it is
our practice to give, as a complement to the study of human
anatomy, a certain number of lessons on the anatomy of
those animals which artists might be called on to represent.

Now, we were given to understand that the subject
treated in our lectures interested our hearers, so much so
that we were not surprised to learn that a certain number
repeatedly expressed a desire to see these lectures united
in book form.

To us this idea was not new ; for many years the work in
question had been in course of preparation, and we had
collected materials for it, with the object of filling up a
void of which the existence was to be regretted. But our
many engagements prevented us from executing our pro-
ject as early as we would have wished. It is this work
which we publish to-day.

Putting aside for a moment the wish expressed by our
hearers, we feel ourselves in duty bound to inquire whether
the utility of this publication is self-evident. Let it be
clearly understood that we wish to express here our opinion

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PREFACE vii

on this subject, while putting aside every personal senti-
ment of an author.

No one now disputes the value of anatomical studies
made in view of carrying out the artistic representation of
man. Nevertheless — for we must provide against all con-
tingencies— the conviction on this subject may be more or
less absolute ; and yet it must possess this character in an
intense degree in order that these studies may be profit-
able, and permit the attainment of the goal which is
proposed in undertaking them. It is in this way that we
ever strive to train the students whose studies we direct ;
not only to admit the value of these studies, but to be
materially and deeply convinced of the fact without any
restriction. Such is the sentiment which we endeavour to
create and vigorously encourage. And we may be per-
mitted to add that we have often been successful in this
direction.

Therefore it is that, at the beginning of our lectures, and
in anticipation of possible objections, we are accustomed
to take up the question of the utility of plastic anatomy.
And in so doing, it is in order to combat at the outset the
idea — as mischievous as it is false — which is sometimes
imprudently enunciated, that the possession of scientific
knowledge is likely to tarnish the purity and freshness of
the impressions received by the artist, and to place shackles
on the emotional sincerity of their representation.

It is chiefly by employment of examples that we ap-
proach the subject. These strike the imagination of the
student more forcibly, and the presentation of models of
a certain choice, although rough in execution, is, in our
opinion, preferable to considerations of an order possibly
more exalted, but of a character less clearly practical. Let
us, then, ask the question : Those artists whose eminence
nobody would dare to question, did they study anatomy ?
If the answer be in the affirmative, we surely cannot permit
ourselves to believe that we can dispense with a similar

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PREFACE ix

course. And, as proof of the studies of this class which
the masters have made, we may cite Raphael, Michel-
angelo, and, above all, Leonardo da Vinci ; and, of the
moderns, Gericault. And we may more clearly define
these proofs by an examination of the reproductions of
their anatomical works, chosen from certain of their special
writings.*

Accordingly, there is no scope for serious discussion, and
it only remains for us to enunciate the opinion that it is
necessary that we should imitate those masters, and, with
a sense of respectful discipline, follow their example.

Here, with regard to the anatomy of animals, we pursue
the same method, and the example chosen shall be that of
Barye. His talent is too far above all criticism to allow
that this example should be refused. The admiration
which the works of this great artist elicit is too wide-spread
for us to remain uninfluenced by the lessons furnished by
his studies. It is sufficient to see the sketches relating
to these studies, and his admirable casts from nature
which form part of the anatomical museum of the Ecole
des Beaux-Arts, to be convinced that the artistic tem-
perament, of which Barye was one of the most brilliant
examples, has nothing to lose by its association with re-
searches the precision of which might seem likely to check
its complete expansion.

In those sketches we find proofs of observation so scrupu-
lous that we cannot restrain our admiration for the man

* Mathias Duval and A. Bical, ' L'anatomie des Maitres.' Thirty plates
reproduced from the originals of Leonardo da Vinci, Michelangelo, Raphael,
Gericault, etc., with letterpress and a history of plastic anatomy, Paris,
1890.

The manuscripts of Leonardo da Vinci of the Royal Library, Windsor,
'Anatomy, Foliae A.,' published by Theodore Sabachnikoff, with a French
translation, written and annotated by Giovanni Piumati, with an introduction
by Mathias Duval. Edouard Rouveyre, publisher, Paris, 1898.

Mathias Duval and I-ldouard Cuyer, ' History of Plastic Anatomy : The
Masters, their Books, and Anatomical Figures ' (Library of Instruction of the
School of Fine Arts), Paris, 1898.

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PREFACE

XI

whose ardent imagination was voluntarily subjected to the
toil of study so profound.

If the example of Barye, with whom we associate the
names of other great modern painters of animals, can deter-
mine the conviction which we seek to produce, we shall be
sincerely glad. To contribute to the propagation of useful
ideas, and to see them accepted, gives a feeling of satisfac-
tion far too legitimate for us to hesitate to say what we
should feel if our hope be realized in this instance.

EDOUARD CUYER.

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CONTENTS
INTRODUCTION

I'AGE

GENERALITIES OF COMPARATIVE ANATOMY - - - I

CHAPTER I

OSTEOLOGY AND ARTHROLOGY :

THE TRUNK ----.. 4

THE POSTERIOR LIMBS - - - - "78

THE POSTERIOR LIMBS IN SOME ANIMALS - - 90

THE SKULL OF BIRDS - - - - . 127

CHAPTER II

MYOLOGY :

THE MUSCLES OF THE TRUNK - - - 131

MUSCLES OF THE ANTERIOR LIMBS - - - 162

MUSCLES OF THE POSTERIOR LIMBS - - - 200

MUSCLES OF THE HEAD - - . . 232

CHAPTER III

EPIDERMIC PRODUCTS OF THE EXTREMITIES OF THE FORE

AND HIND LIMBS - - - 247

CHAPTER IV

PROPORTIONS •

PROPORTIONS OF THE HEAD OF THE HORSE - • 273

CHAPTER V

THE PACES OF THE HORSE - - 282

Xlll

LIST OF ILLUSTRATIONS

1. A Human Skeleton in the Attitude of a Quadruped,

To GIVE A General Idea of the Position of the Bones

IN OTHER Vertebrates - - - - - 5

2. Size of the Atlas compared with the Transverse

Dimensions of the Corresponding Parts of the
Skull in Man ------ 7

3. Size of the Atlas compared with the Transverse

Dimensions of the Corresponding Regions of the
Skull in a Dog - - - - - 8

4. Lumbar Vertebra of a Quadruped (the Horse) :

Superior Surface - - - - - 9

5. A Transverse Section of the Thorax of a Man placed

Vertically — that is to say, in the Direction which
it would assume in a Man placed in the Attitude
OF A Quadruped (a Diagrammatic Figure) - - 13

6. A Vertical Section of the Thorax of a Quadruped

(Diagrammatic) - - - - - - 14

7. Sternum of a Bird (the Cock) : Left Side, External

Surface - - - - - - -17

8. Anterior Limb of the Bat ; Left Side, Anterior

Surface -- - - - - -20

9. Anterior Limb of the Seal : Left Side, External

Surface - - - - - - - 21

10. Situation and Direction of the Scapula in the

Human Being, the Trunk being Horizontal, as in
Quadrupeds. Vertical and Transverse Section
of the Thorax (Diagrammatic Figure) - - 22

11. Position and Direction of the Scapula in Quadru-

peds. Vertical and Transverse Section of the
Thorax (Diagrammatic Figure) - - - 22

12. Left Scapula of the Human Being, Posterior Surface,

placed in the Position which it would Occupy in

THE Skeleton of a Quadruped - - - 23

13. Left Scapula of a Horse : External Surface - 23

XV

xvi LIST OF ILLUSTRATIONS

MG. I'AGE

14. Vertical and Transverse Section, at the Site of the

Shoulders, of the Thorax of the Horse (Dia-
grammatic Figure) - - - - - 24

15. Vertical and Transverse Section, at the Plane

OF THE Shoulders, of the Thorax of the Dog (Dia-
grammatic Figure) - - - - - 24

16. Left Clavicle OF THE Cat : Superior Surface (Natural

Size) - - - - - - -26

17. Clavicle of the Dog (Natural Size) - - - 26

18. Skeleton of the Shoulder of a Bird (Vulture):

Antero-External View of the Left Side - - 27

19. Inferior Extremity of the Left Humerus of a Felid.^

(Lion) - - - - - - - 31

20. Inferior Extremity of the Left Human Humerus,

showing the Presence of a Supratrochlear Process 31

21. Skeleton of a Bird (Vulture) : Left Surface - -33

22. The Human Hand resting for its Whole Extent

ON ITS Palmar Surface : Left Side, External
Surface - - - - - - -35

23. The Human Hand resting on its Phalanges : Left

Side, External Surface - - - - 36

24. The Human Hand resting on the Tips of some of

its Third Phalanges : Left Side, External View - 36

25. Superior Extremity of the Bones of the Human

Forearm : Left Side, Superior Surface - - 39

26. Superior Extremity of the Bones of the Forearm

OF a Dog : Left Limb, Superior Surface - - 39

27. Superior Extremity of the Bones of the Forearm

OF the Horse : Left Limb, Superior Surface - 40

28. Inferior Extremity of the Bones of the Forearm

of a Man : Left Side, Posterior Surface, Position

OF Supination - - - - - - 41

29. Inferior Extremity of the Bones of the Forearm

OF A Dog : Left Side, Anterior Surface, Normal
Position — that is, the Position of Pronation - 41

30. Inferior Extremity of the Bone of the Forearm

OF the Horse : Left Side, Anterior Surface - 42

31. Skeleton of the Superior Limb of a Bird (Vulture) :

Left Side, External Surface - - - 47

32. Superior Limb of the Human Being, the Different

Segments being placed in the Attitude which the
Corresponding Parts occupy in Birds : Left Side,
External Surface - - - - - 48

33. Skeleton of the Bear : Left Lateral Surface - 50

34. Skeleton of the Dog : Left Lateral Surface - 52

35. Scapula of the Dog : Left Side, External Surface 53

36. Left Scapula of the Cat : External Surface - 53
^;/. Skeleton of the Finger of a Felide (Lion) : Left

Side, Internal Surface - - - -57

XI

LIST OF ILLUSTRATIONS xvii

FIG. PAGE

38. Skeleton of the Pig : Left Lateral Surface - 58

39. Skeleton of the Ox : Left Lateral Surface - 61

40. Skeleton of the Horse : Left Lateral Surface - 64

41. Flexion of the Humerus: Right Anterior Limb of

THE Horse, External Surface (after a Chromo-
photographic Study by Professor Marey) - - 74

42. Extension of the Humerus : Right Anterior Limb

of the Horse, External Surface (after a Chromo-
photographic Study by Professor Marey) - - 74

43. The Left Iliac Bone of the Human Being : Ex-

ternal Surface, placed in the Position which it
would occupy in the Skeleton of a Quadruped - 79

44. Left Iliac Bone of a Quadruped (Horse) : External

Surface - - - - - - - 79

45. Pubic Region of the Pelvis of a Marsupial (Pha-

LANGER, Fox) - - - - - - 8l

46. Pelvis of a Bird (the Cock) : External Surface,

Left Side - - - - - - 82

47. Posterior Limb of the Horse placed in the Position

which it should occupy if the Animal were a
Plantigrade : Left Limb, External Surface - 89

48. Skeleton of the Foot of a Bird (the Cock) : Left

Side, External Surface - - - - 90

49. Pelvis of the Dog, seen from Above - - - 91

50. Pelvis of a Felide (Lion), viewed from Above - 92

51. Pelvis of the Ox: Superior Surface - - 95

52. Tarsus of the Ox : Posterior Left Limb, Antero-

external Surface - - - - - 97

53. Pelvis of the Horse : Superior Surface - - loi

54. Tarsus of the Horse : Left Posterior Limb, An-

terior Surface . . . . . 104

55. Extension of the Leg : Right Posterior Limb of the

Horse, External Surface (after a Chronographic
Study by Professor Marey) ... 107

56. Human Skull : Measure of the Facial Angle by the

Method of Camper. Angle BAC = 8o° - - 110

57. Skull of the Horse : Measure of the Facial Angle

BY the Method of Camper. Angle BAC=i3° - no

58. Skull of one of the Felide (Jaguar) : Left Lateral

Aspect - - - - - - -113

59. Skull of the Lion: Left Lateral Aspect - - 113

60. Skull of the Dog: Left Lateral Aspect - - 115

61. Skull of the Pig: Left Lateral Aspect - - 1^7

62. Skull of the Ox: Left Lateral Aspect - - 119

63. Skull of the Horse : Left Lateral Aspect - 121

64. Skull of the Hare : Left Lateral Aspect - - 123

65. Skull of the Cock : Left Lateral Surface - - 128

66. Myology of the Horse : Anterior Aspect of the

Trunk ------- 132

xviii LIST OF ILLUSTRATIONS

KIG. PAGE

67. Myology of the Horse : Inferior Aspect of the

Trunk ------- 13-

68. Myology of the Dog : Superficial Layer of Muscles 141

69. Myology of the Ox : Superficial Layer of Muscles 143

70. Myology OF THE Horse : Superficial Layer OF Muscles 146

71. Myology of the Horse : Panniculus Muscle of the

Trunk ------- 148

72. Myology of the Horse — Shoulder and Arm : Left

Side, External Surface . - - - 155

Tl. Myology of the Dog : Left Anterior Limb. External

Aspect ------- 178

74. Myology of the Ox : Left Anterior Limb, External

Aspect - - - - - - -180

75. Myology of the Horse : Left Anterior Limb, Ex-

ternal Aspect - - - - - - 182

76. Myology of the Dog : Left Anterior Limb, In-

ternal Aspect - - - - - - 190

Tj. Myology of the Horse : Anterior Limb, Left Side,

Internal Aspect ----- ig)2

78. Left Anterior Limb of the Horse : Internal Aspect 194

79. Left Anterior Limb of the Horse : External Aspect 196

80. Left Anterior Limb of the Horse : External Aspect 196

81. Diagram of the Posterior Part of a Transverse

Section passing through the Middle of the, Left
Fore-limb of the Dog : Surface of the Inferior
Segment of the Section . - - - 198

82. Diagram of a Horizontal Section of the Middle

OF THE Forearm of the Left Leg of the Horse :
Surface of the Interior Segment of the Section - 198

83. Myology of the Horse : the Anterior Tibial Muscle

(Flexor of the Metatarsus), Left Leg, Anterior
View - - - - - - -214

84. Myology of the Dog : Left Hind-limb, External

Aspect - - - - - - -216

85. Myology of the Ox : Left Leg, External Aspect - 218

86. Myology of the Horse : Left Hind-limb, External

Aspect ------- 220

%"]. Myology of the Dog : Left Hind-limb, Internal

Aspect ------- 222

88. Myology of the Horse : Left Hind-leg, Internal

Aspect ------- 223

89. Myology of the Dog : Masticatory Muscles (a

Deeper Dissection than that shown in Fig. 90) - 233

90. Myology of the Dog : Muscles of the Head - 235

91. Myology of the Ox: Muscles of the Head - 237

92. Myology of the Horse : Muscles of the Head - 239

93. Claw of the Dog : Inferior Surface - - 249

94. Left Hand of the Dog : Inferior Surface, Plantar

Tubercles ------ 249

LIST OF ILLUSTRATIONS xix

FIG. I'AGE

95. Vertical Antero-posterior Section of the Foot of

A Horse .._.._ 250

96. Third Phalanx of the Horse : Left Anterior Limb,

External Surface - - - - -251

97. Left Anterior Foot of the Horse : Anterior Aspect 253

98. Left Anterior Foot OF THE Horse : External Aspect 254

99. Vertical and Transverse Section of a Left Human

Foot : Outline of the Surface of the Posterior

Segment of this Section (Diagrammatic Figure) - 255
100. Inferior Surface of a Fore-hoof of the Horse : Left

Side --____- 256
loi. Third Phalanx of the Horse : Left Anterior Limb,

Inferior View _ _ _ _ . 257

102. Third Phalanx of the Horse : Left Posterior Limb,

Inferior View . . . _ . 257

103. Inferior Surface of a Hind-hoof of a Horse : Left

Side --...-. 258

104. Left Posterior Foot of a Horse : External Aspect 259

105. Foot of the Ox : Left Side, Antero-external View 260

106. The Proportions of the Horse (after Bourgelat) - 265

107. Proportions of the Horse (after Colonel Duhous-

set) ------- 270

108. Proportions of the Head of the Horse, viewed in

Profile (after Colonel Duhousset) - - 274

109. The Same Design as that of Fig. 108, on which we

have indicated, by Similar Lines, the Principal
Corresponding Measurements _ - - 275

1 10. Proportions of the Head of the Horse, seen from

THE Front (after Colonel Duhousset) - - 276

111. The Same Figure as Fig. iio, on which we have

marked, by Similar Lines, the Principal Measure-
ments which correspond thereto - - - 277

112. Horse of which the Length contains more than

Two AND A Half Times that of the Head, and of
which this Dimension (A, B) exceeds the Height 279

113. Horse of which the Length contains more than

Two AND a Half Times that of the Head, and
OF WHICH this Dimension (A, B) exceeds the
Height ------- 280

114. Horse of which the Length contains more than

Two AND A Half Times that of the Head, and of
WHICH this Dimension (A, B) is Inferior to the
Height - - - - - - -281

115. Experimental Shoes, intended to Record the

Pressure of the Foot on the Ground - - 284

1 16. Runner furnished with the Exploratory and

Registering Apparatus of the Various Paces - 285

117. Tracing of the Running of a Man (after Professor

Marey) ------- 286

XX LIST OF ILLUSTRATIONS

KIG. I- AGE

ii8. Notation of a Tracing of the Running of a Man

(AFTER Professor Marev) . . . . 287

119. Notation of Various Modes of Progression of

A Man (after Professor Marey) - - - 287

120. Swing of the Raised Anterior Limb (after G. Colin) 289

121. Swing of the Anterior Limb on the Point of Pres-

sure (after G. Colin) . _ . _ 290

122. Posterior Limb, giving the Impulse (after G. Colin) 291

123. Notation of the Ambling Gait in the Horse (after

Professor Marey) ----- 292

124. The Amble : Right Lateral Pressure - - 293

125. Notation of the Gait of the Trot in a Horse (after

Professor Marey) ----- 294

126. The Trot : Right Diagonal Pressure - - 295

127. The Trot : Time of Suspension - - . 295

128. Notation of the Pace of Stepping in the Horse

(after Professor Marey) - - - . 296

129. The Step : Right Lateral Pressure - - - 297

130. The Step : Right Diagonal Pressure - - 297

131. The Gallop: First Period - - - - 298

132. The Gallop : Second Period - - - - 298

133. The Gallop : Third Period - - - - 299

134. The Gallop : Time of Suspension - - - 299

135. Notation of the Gallop divided into Three Periods

of Time (after Professor Marey) - - - 300

136. Notation of the Gallop of Four Periods in the

Horse (after Professor Marey) - - - ^oo

137. Leap of the Hare (after G. Colin) - - - 301

138. The Leap -._-.- 302

139. The Leap ---..- ^02

140. The Leap ._--.- 303

141. The Leap ...__. 303

142. TheJLeap _.--_- 205

143. The Leap _-.._- ^^05

THE ARTISTIC ANATOMY OF

ANIMALS

INTRODUCTION

GENERALITIES OF COMPARATIVE ANATOMY

Of the animals by which we are surrounded, there are some
which, occupying a place in our lives by reason of their
natural endowments, are frequently represented in the works
of artists — either as accompanying man in his work or in
his amusements, or as intended to occupy the whole interest
of the composition.

The necessity of knowing, from an artistic point of view,
the structure of the human body makes clear the importance
we attach, from the same point of view, to the study of the
anatomv of animals — that is, the study of comparative
anatomy. The name employed to designate this branch of
anatomy shows that the object of this science is the study
of the relative position and form which each region presents
in all organized beings, taking for comparison the correspond-
ing regions in man. The head in animals compared with
the human head ; the trunk and limbs compared to the
trunk and limbs of the human being — this is the analysis we
undertake, and the plan of the subject we are about to
commence.

Our intention being, as we have just said, the comparison
of the structure of animals with that of man, should we
describe the anatomy of the human being in the pages

2 THE ARTISTIC x\NATOMY OF ANIMALS

which fohow ? We do not think so. Plastic human
anatomy having been previously studied in special works,*
we take it for granted that these have been studied before
undertaking the subject of comparative anatomy. We
will therefore not occupy time with the elementary facts
relative to the skeleton and the superficial layer of muscles.
We will not dilate on the division of the bones into long,
short, large, single, paired, etc. All these preliminary
elements we shall suppose to have been already studied.

This being granted, it is, nevertheless, necessary to take
a rapid bird's-eye view of organized beings, and to recall the
terms used in their classification.

Animals are primarily classed in great divisions, based
on the general characters which differentiate them most.
These divisions, or branches, allow of their being so grouped
that in each of them we find united the individuals whose
general structure is uniform ; and under the n?me of verte-
brates are included man and the animals with which our
studies will be occupied. The vertebrates, as the name
indicates, are recognised by the presence of an interior
skeleton formed by a central axis, the vertebral column,
round which the other parts of the skeleton are arranged.

The vertebrate branch is divided into classes : fishes,
amphibians or batrachians, reptiles, birds, and mammals.

The mammals — from the Latin mamma, a breast — are
characterized by the presence of breasts designed for the
alimentation of their young. Their bodies are covered with
hair, hence the name pilifcres proposed by Blainville ; and,
notwithstanding that in some individuals the hairs are few,
the character is sufficient to distinguish them from all other
vertebrates.

We find united in this class animals which, at first, seem
out of place, such as the whale and the bat ; and, from their
external appearance alone, the former would appear to

* Mathias-Duval, ' Precis of Anatomy for the Use of Artists' : Paris,
1881. 'Artistic Anatomy of the Human Bo'ly,' third edition, plates by
Dr. Fau, text with figures by Edouard Cuyer : Paris, 1896. 'Artistic
Anatomy of Man,' by J. C. L. Sparkes, second edition, text with 50 plates :
Bailliere, Tindall and Cox, London, 1900.

INTRODUCTION 3

belong to the fishes, and the latter to birds. Yet, on study-
ing their structure, we find that, not only do these animals
merit a place in the class which they occupy, because they
possess the distinctive characters of mammals ; but, still
further, their internal structure is analogous to that of man
and of the other individuals of this class.

Notwithstanding this similarity of structure, the whale
is not without some points of difference from its neighbours
the horse and the dog ; therefore, in order to place each of
these animals in a position suitable to it, mammals are
divided into secondary groups called orders. The first of
these orders includes, under the name primates, man and
apes. The latter contain animals which approach birds in
certain characters of their organism, forming a link between
the latter and mammals.

We find, in studying the regions of the body in some of the
vertebrates, that, while they present differences from the
corresponding regions of the human body, they also offer
most striking analogies. We can, for example, recognise
the upper limb of man in the anterior one of quadrupeds,
in the wing of the bat, in the paddle of the seal, etc. It is,
so to speak, those variations of a great plan which give
such a charm to the study of comparative anatomy.

The division of classes into orders, which we have just
mentioned, being still too general, it was found necessary to
establish subdivisions — more and more specialized — to
which the names families, genera, species, and varieties were
given.

I — 2

CHAPTER I
OSTEOLOGY AND ARTHROLOGY

THE TRUNK

The Vertebral Column

We commence the study of the skeleton with a description
of the trunk.

The trunk being, in quadrupeds, horizontal in direction
(Fig. i), the two regions of which it consists occupy, for this
reason, the following positions : the thorax occupies the
anterior part, the abdomen is placed behind it ; the vertebral
column is horizontal, and is situated at the superior aspect
of the trunk ; it projects beyond the latter : anteriorly, to
articulate with the skull ; and, posteriorly, to form the
skeleton of the tail, or caudal appendix.

The number of the \ertebrae is not the same in all mam-
malia. Of the several regions of the vertebral column, the
cervical shows the greatest uniformity in the number of the
vertebrae of which it consists, with but two exceptions
(eight or nine in the three-toed sloth, and six in the manatee) ;
we always find seven cervical vertebrae, whatever the length
of the neck of the animal. There are no more than seven
vertebrae in the long neck of the giraffe, but they are very
long ones ; and not less than seven in the very short neck
of the dolphin, in which they are reduced to mere plates of
bone not thicker than sheets of cardboard. If the cervical
region presents uniformity in the number of its bones, it is
not so with the other regions of the column.

4

OSTEOLOGY AND ARTHROLOGY

The following table shows their classification in some
animals :

VERTEBR/E.

Cervical.

Dorsal.

Lumbar.

Bear

Dog

Cat

Rabbit

Pig

Horse

Ass

Camel

GiralTe

Ox

Sheep

7
7
7
7
7
7
7
7
7
7
7

14

13
13

12

14
i8
i8

12

13
13

6

7

7

7
6 or 7
6 or 5

5
7

5
6
6

Ei.CuyER
Fig. I. — A Human Skeleton in the Attitude of a Quadruped. To

GIVE A GENERAL IdEA OF THE POSITION OF THE BONES IN OTHER

Vertebrates.

It is worth}^ of notice that in birds the number of the
cervical vertebra? is not constant, as in mammals ; they are

6 THE ARTISTIC ANATOMY OF ANIMALS

more numerous than the dorsal. These latter are almost
always joined to one another by a fusion of their spinous
processes ; the two or three last vertebrse are similarly
united to the iliac bones, between which they are fixed. The
dorsal vertebrae thus form one piece, which gives solidity to
the trunk, and provides a base of support to the wings,
for the movements of flying. There are, so to speak, no
lumbar vertebree, the bones of that region, which cannot be
differentiated from the sacrum, having coalesced with the
bones of the pelvis.

Vertebra.

1

Cervical.

Dorsal.

Vulture

15

7

Eagle

13

9

Cock

14

7

Ostrich

18

9

Swan

23

10

Goose

18

9

Duck

15

9

In reptiles, the relation between the number of the cervical
vertebrae and that of the dorsal is very variable ; some
serpents are devoid of cervical vertebrae, having only dorsal
ones— that is, vertebrae carrying well-developed ribs.

Vertebra.

Cervical.

Dorsal.

Lumbar.

Crocodile

7

14

Caiman

7

12

5

Boa

3

248

0

Pvthon

0

320

0

Viper

2

145

0

Regarding the direction of the vertebral column in animals,
in which the trunk is not vertical, it is evident that the
spinous processes point upward, and that in comparing them
with those of man the}' must be arranged so that the superior
surface of the human vertebra will correspond to the anterior

OSTEOLOGY AND ARTHROLOGY 7

surface of that of the quadruped. Of the cervical vertebrae,
the atlas and axis call for special notice. Apropos of the
atlas, we find that it, in the human being, is narrower than
the corresponding parts of the skull, and is therefore hidden
under the base of the cranium (Fig. 2) ; in quadrupeds its
width is equal to that of the skull, and sometimes exceeds,
because of the great development of its wing-shaped trans-
verse processes, that of the neighbouring parts of the head

Fig. 2. — Size of the Atlas compared with the Transverse Dimen

SIONS OF THE CORRESPONDING PARTS OF THE SkULL IN MaN.

I, Atlas ; 2, mastoid process ; 3, external occipital protuberance ;

4, inferior maxilla.

(Fig. 3). On this account those transverse processes often
project under the skin of the lateral surfaces of the upper
part of the neck.

The axis is furnished on its anterior surface with the odon-
toid process, which articulates with the anterior (or inferior)
arch of the atlas, according to the direction of the neck.
The spinous process, flattened from without inwards, is
more or less pointed ; it is elongated from before backwards,
so as partly to overlap the atlas and the third cervical
vertebra.

We find that this process overlaps less and less the neigh-
bouring vertebrae when we examine in succession the bear,
the cat, the dog, the ox, and the horse. With regard to the
other vertebrae of this region, they diminish in width from

8

THE ARTISTIC ANATOMY OF ANIMALS

the second to the seventh ; and, in some animals, the anterior
surface of the body presents a tubercle which articulates
with a cavity hollowed in the posterior surface of that
of the vertebra before it ; this feature dwindles away in the
dorsal and lumbar regions.

The spinous process, slightly developed in the third
cervical vertebra, gradually increases in size to the seventh,
the spinous process of which, long and pointed, well deserves
the name of the prominent which is bestowed on it ;' but it
should not be forgotten that the spinous process of the axis
is equally developed.

y^\

Fig. 3. — Size of the Atlas compared with the Transverse Dimen-
sions OF the corresponding Regions of the Skull in a Dog.

I, Atlas, 2 ; zygomatic arch ; 3, external occipital protuberance ; 4,

inferior maxilla.

On the inferior surface of the body of each of the vertebrae
is found a prominent crest, especially well marked at the
posterior part ; this crest is but slightly developed in the
bear and in the cat tribe, and is not found in swine.

The transverse processes of the cervical vertebrae, from
their relation to the trachea, are known as the tracheal
■processes.

The most marked characteristic of the dorsal vertebrae is
furnished by the spinous processes. They are long and
narrow. As a rule, the_spinou3_ processes of the foremost

OSTEOLOGY AND ARTHROLOGY

dorsal vertebrae are the most developed and are directed
obliquely upwards and backwards. As we approach the
last vertebrae of this region, the processes become shorter
and tend to become vertical, and the last ones are even, in
some cases, directed upwards and forwards ; this disposition
is well marked in the dog and the cat. In the cetaceans, on
the contrary, the length of the spinous processes increases
from the first to the last.

In the horse the spinous processes of the first dorsal

II
?

E^,.C

Fig. 4. — Lumbar Vertebr.e of a Quadruped (the Horse) : Superior

Surface.

I, Spinous process ; 2, anterior articular process and transverse process
of the first lumbar vertebra of the left side ; 3, costiforni process.

vertebrae produce the prominence at the anterior limit of the
trunk, where the mane ends, which is known as the withers.

The lumbar vertebrae are thicker than the preceding ;
they are known by their short and latterly-flattened spinous
processes, and still more readily by their transverse processes,
which, as they are evidently atrophied ribs, it is more
accurate to denominate costiform processes (Fig, 4). These
are long, flattened from above downwards, and directed
outwards and forwards.

The true transverse processes are represented by tubercles

10 THE ARTISTIC ANATOMY OF ANIMALS

situated on the superior borders of the articular processes
of each of the vertebrae of the lumbar region. Apropos of
these different osseous processes, we arc reminded that they
are also present in the human skeleton.

In the horse the costiform processes of the fifth and sixth
lumbar vertebrje articulate, and are sometimes ankylosed,
one with the other ; the terminal ones articulate with the base
of the sacrum. Sometimes the processes of the fourth and
fifth are thus related ; this is the case in the figure (4) given ;
here the costiform processes of the fourth and fifth vertebrae
articulate, and the two terminal ones have coalesced.

In the ox, the same processes are more developed than in
the horse ; their summits elevating the skin, produce,
especially in animals which have not much flesh, prominences
which limit the flanks in the superior aspect. The costiform
processes of the last lumbar vertebrae are separate from each
other ; those of the latter are not in contact with the sacrum.

The Sacrum.* — This bone, single and median, is
formed by the mutual coalescence of several vertebrae, which
vary in number according to the species observed.

VertehrcB Constituting the Sacrum. — Bears, 5 ; dogs, 3 ;
cats, 3 ; rabbits, 4 ; swine, 4 ; horses, 5 ; camels, 4 ;
oxen, 5 ; sheep, 4.

The sacrum is situated between the two iliac bones ; with
which it articulates, and contributes to the formation of the
pelvis. It is obliquely placed, from before backwards, and
from below upwards ; immediately behind the lumbar
section of the vertebral column ; and is continued by the
coccygeal vertebrae, which form the skeleton of the tail.

It is triangular in outline, and is generally more narrow in
proportion than in the human being. All things considered,
it is more large and massive, and of greater density, in species
which sometimes assume the upright posture, rather than in

* In human anatomy, the sacrum and the coccyx are studied as part
of the pelvis ; we, therefore, in the study of the artistic anatomy of
man, study these bones with the bones of the lower hmbs. Here we do
not follow this plan. In animals the sacrum and the coccyx, as a matter
of fact, clearly continue the superior border of the skeleton of the trunk ;
hence we study them with the vertebral column.

OSTEOLOGY AND ARTHROLOGY ii

those which cannot assume that attitude ; for example, the
sacrum of the ape, of the bear, of the dog, and of the opossum
are proportionately larger than those of the horse.*

Its superior surface presents a crest, formed by the fusion
of the spinous processes of the vertebrae which form it. In
certain species these processes are attached only by their
bases, and are separated from each other superiorly. In
the pig they are wholly wanting.

The Coccygeal Vertebrae. — These vertebne, few in
number (and sometimes ankylosed) in the human being,
form in the latter a small series, the coccyx ; which is in-
clined forwards, that is to say, towards the interior of the
pelvis. In quadrupeds, on the contrary, their number is
large ; they are not ankylosed, and they form the skeleton
of the caudal appendix.

The first coccygeal vertebne — that is, those which are next
the sacrum — present characters which are common to those
of other regions : they have a body, a foramen, and pro-
cesses. As we trace them backwards, these characters be-
come gradually effaced ; and they become little more than
small osseous cylinders simply expanded at their extremities.

Direction and Form of the Spinal Column

The curves of the vertebral column are, in quadrupeds,
slightly different from those which characterize the human
spine. First, instead of their being, as in the latter, curves
in the antero-posterior aspect, because of the general attitude
of the body, they are turned in the supero-inferior direction.

The cervical region is not a single curve, as in the human
being. It presents two : one superior, with its convexity
looking upwards ; the other inferior, the convexity of which
is turned downwards. This arrangement reminds one of
that of a console.

* This is particularly striking only in those portions of the sacrum that
are not in relation with the other bones of the pelvis. We think that
the general form of this bone depends on the mode of its connexions with
the iliac bones and the extent of the articular surfaces by which it is in
contact with the latter.

12 THE ARTISTIC ANATOMY OF ANIMALS

The dorsal and lumbar regions are placed in a single curved
line, more or less conca.ve downwards ; so that in the lumbar
region there is no curve analogous to that which exists in
man ; a form which, in the latter, is due to the biped atti-
tude— that is to say, the vertical position of the trunk.
Briefly, there is in quadrupeds one dorso-lumbar curve ; and
not both a dorsal and a lumbar, with convexities in opposite
directions.

At the extremity of the dorso-lumbar region is the
sacrum and the caudal appendix, which describe a curve
of which the concavit}^ is directed downwards and forwards.

It is necessary to point out that it is not the curves of the
three anterior portions of the spinal column which deter-
mine the form of the superior border of the neck and
shoulders, and of the same part of the trunk. For the first
portion, there is a ligament which surmounts the cervical
region, and substitutes its modelling influence for that of the
vertebrae. It is the superior cervical ligament, which arises
from the spinous process of the first cervical vertebrae, and is
inserted into the external occipital protuberance on the
upper part of the posterior surface of the skull. The summits
of the spinous processes of the vertebrae alone give form to
the superior median border of the trunk. In this connection
we here repeat that it is not the general curvature of the
vertebral column which produces the withers, but the great
length of the ^spinous process of the first vertebrce of the
dorsal region.

The Thorax

1^ The dorsal vertebrae form the posterior limit in man, and
superior in quadrupeds, of the region of the trunk known
as the thorax. A single bone, the sternum, is situated at
the aspect opposite ; the ribs bound the thorax on its sides.
In its general outlines the thorax in quadrupeds resembles
that of man — that is to say, that, as in the latter, the anterior
portion — superior in the huma.n being — is narrower than the
part opposite. But the progressive widening takes place in
a more regular and continuous fashion, so that it presents

OSTEOLOGY AND ARTHROLOGY 13

a more definitely conical outline. This purely conical form
is nevertheless found in the human species, but only during
infancy ; the inferior portion of the thoracic cage being then
widely expanded, because of the development of the ab-
dominal viscera, which at that period are relatively large.

But the proportionate measurements of the thorax are
different. Indeed, we may recall that in man the thorax is
flattened from before backwards, so that the distance
between the sternum and the vertebral column is shorter
than the distance from the rib of one side to the correspond-
ing one of the opposite side (Fig. 5). In animals, on the
contrary, it is flattened laterally. Its vertical diameter —
measured from the sternum to the vertebral column — is
greater than the transverse measurement (Fig. 6).

Fi-G. 5. — A Transverse Section of the Thorax of a Man placed
Vertically — that is to say, in the Direction which it would
assume in a Man placed in the Attitude of a Quadruped (a
Diagrammatic Figure).

I, Dorsal vertebra; 2, sternal region; 3, costal region of one side;
3', costal region of the other side.

From this results a peculiar arrangement of the muscles
that we are able to bring directly into prominence, which
presents points of interest from the point of view of the con-
traction of the subcutaneous layer. Indeed, in man the
region occupied by the pectorals is very broad ; it is a wide
surface turned directly forward. In quadrupeds, this region
of the pectorals is narrowed. It is not spread out, as in the
preceding instances ; and the appearance it presents is
explained by the fact that the thorax is compressed laterally.
If we examine the thorax on one of its lateral surfaces, the
muscles, on the contrary, are more extended. We see the
contour of the vertebral column, and the median part of the
abdomen ; and, especially in the horse, between the great

14 THE ARTISTIC ANATOMY OF ANIMALS

dorsal and the great oblique of the abdomen, we find a large
space, in which the ribs, with the intercostals which join them,
are uncovered ; the muscles in question separate the one
from the other, under the influence, it would seem, of the
great dimensions of the lateral wall of the thorax.

The Sternum. — The sternum is, in quadrupeds, directed
obliquely downwards and backwards ; its form varies in
different species. In the carnivora, it consists of eight bones.

Fig. 6. — A Vertical Section of the Thorax of a Quadrux'Eu

(Diagrammatic).

I, Fifth dorsal vertebra ; 2, sternal region; 3, costal region of one side;
3', costal region of the opposite side.

irregularly cylindrical in form, being slightly flattened from
within outwards, and thickened at their extremities. They
remain separate, and this contributes elasticity and flexibility
to the thorax. The first nine costal cartilages articulate
directly with the sternum. The first of these cartilages
articulates with a nodule situated a little above the middle
of the first bone of the sternum.

In the horse the sternum is flattened laterally in its
anterior portion, and from above downwards in its posterior

OSTEOLOGY AND ARTHROLOGY 15

half. The six bones which form the sternum are connected
by cartilage. The keel-shaped piece, situated in front of the
sternum, is also cartilaginous. This process, but slightly
marked posteriorly, becomes more and more prominent in
front, and terminates at its anterior extremity by a prolonga-
tion, slightly curved backwards, which projects for some
centimetres beyond the cavity in which the first costal
cartilage is received. This process is known as the tracheal
process, or rostral cartilage. The posterior extremity of the
sternum, flattened from above downwards, ends in a car-
tilaginous plate ; concave superiorly, and convex inferiorly :
this is the abdominal prolongation, or xiphoid appendix.

In the ox, the sternum is formed of two distinct bones,
which are united by an articulation. One, the anterior, is
short, and forms the first portion of the sternum ; it is
slightly flattened from side to side, and vertical in direction.
The other, the posterior, is longer, and is formed by the
fusion of several small bones ; it is placed horizontally, and
is flattened from above downwards. At the level of articu-
lation of these two portions, and because of their different
directions, the bone is bent. This bend occurs at the point
of articulation of the second costal cartilage. On the
superior border of the anterior segment the cartilage of
the first rib is articulated. The xiphoid appendix, which
is cartilaginous, is attached to the extremity of a long
process of the last bone of the sternum.

The shape of the anterior extremity of the sternum is
influenced by the presence or absence of clavicles. We have
seen that in some quadrupeds the clavicles are wanting. In
the first case, this extremity is large, and approaches in shape
to the corresponding part of the human sternum, which is so
clearly designed to give a point of support to the anterior
bone of the shoulder. In the second, on the contrary, this
extremity is narrow.

The sternum in birds is very different from that in mam-
malia, which we have been studying. It varies greatly in
extent and shape, under the influence of certain conditions.
To understand the cause of these variations it is necessary
to remember that in man (as, indeed, in other animals ; but

i6 THE ARTISTIC ANATOMY OF ANIMALS

the example of man, for that which follows, will be more
striking, on account of the mobility of his upper limbs) the
sternum gives origin to the pectoral muscles, and that these
muscles are inserted into other parts of the thoracic limbs,
designed by their contraction to draw the arms downwards,
forwards, and inwards — that is, when these are in a state of
abduction and in a horizontal direction, they draw them
towards the anterior surface of the thorax and downwards.
Now, this movement is similar to that made by birds
during flight. It is necessary to add that, in the latter
case, the more the displacement of the upper limbs has
of force and extent, the more the pectoral muscles are
developed.

For these reasons, birds, in which, during flight, the move-
ments of the thoracic limbs — the wings — are necessarily
energetic, present a great development of the pectoral
muscles ; having consequently, because an extent of surface
for the origin of the muscles commensurate with their de-
velopment is necessary, a very large and peculiarly shaped
sternum (Figs. i8, 6 ; and 21, 6). Indeed, not only is the
sternum large, but, further, in order to form a deeper surface,
proportionately adapted to the muscles which arise from and
cover it, its anterior surface presents, in the median line, a
prominent crest known as the keel. This prominence forms
two lateral fossae. We cite as examples, the sternum of the
eagle, the vulture, the falcon, and the hawk.

All birds are not, however, equally adapted to flight, for
in the domestic cock, which flies but a short distance, and
badly, the sternum is less developed (Fig. 7) ; it is also
diminished by slots, which diminish its surface. These slots,
two on each side, are called from their position the internal
and external slots. They are bounded by narrow, elongated,
bony processes, an internal and an external ; the expanded
lower extremity of the latter overlaps the last inferior ribs
(see p. 19). The part of the external border which surmounts
this external process is hollowed out into grooves, which
receive the inferior ribs, and terminates superiorly in an
osseous projection known as the costal prominence.

In the ostrich, the cassowary, and the apteryx, which run,

OSTEOLOGY AND ARTHROLOGY

17

but do not fly, the sternum has the form of a plate of bone
sHghtly convex, but without a keeL

The shape of the sternum, correlated to the faculty of
flight (or of swimming ; apropos of which we may cite the
penguin, of which the rudimentary wings resemble fins,
and perform their functions only), or the absence of this
faculty, has furnished the division of birds into two groups.
In one are included, under the name Carinates {carina, keel),
those in which the sternum is provided with a keel ; in the

7'\

Fig. 7. — Sternum of a Bird (the Cock) : Left Side, External Surface.

I, Keel ; 2, internal slot ; 3, external slot ; 4, internal process; 5, external
process ; 6, inferior ribs ; 7. costal process ; 8, surface for articulation
with the coracoid bone.

other division are those in which the sternum is not furnished
with one. These latter, on account of their unique mode of
progression, are more nearly allied to the mammals.

The keel is developed in flying mammals (bats).

Ribs and Costal Cartilages. — There are on each side
of the thorax as many ribs as there are dorsal vertebra; .
In animals, as in man, the ribs which articulate with the
sternum by their cartilages are called true, or sternal ribs ;
those whose cartilages do not articulate with the sternum

i8 THE ARTISTIC ANATOMY OF ANIMALS

are called false, or asternal. The longer ribs are those
situated in the middle region of the thorax.

The ribs are directed obliquely downwards and backwards,
and this obliquity is more marked in the posterior ones than
in the anterior. They are, however, less oblique than in
the human being ; what proves this is that the first rib in man
is oblique, while in quadrupeds it is vertical.

The curvature of the ribs is less pronounced in quadrupeds
than in the human being, but this is not equal in all animals.
The ribs of the bear are more curved than those of the dog ;
the latter has ribs more curved than those of the horse.

Each rib, at its vertebral extremity, presents, from within
outwards, a wedge-shaped head for articulation with two
dorsal vertebrae, a neck, and a tuberosity. External to the
tubercle are found some rough impressions, for muscular
attachments, which correspond to the angle of the human
rib.

In the following table, we give the number and classifica-
tion of the ribs of some animals :

Number of the Ribs on Each Side of the Thorax.

Sternal.

Asternal

Bear

... 14

d

vided

into

9

and

5

Dog ...
Cat
Rabbit ...

1 J

I '^

9
9

7

4

4

5

Pig
Horse

... 14
... 18

7
8

7
10

Camel

12

8

4

Ox
Sheep

... 13
... 13

8
8

5
5

The costal cartilages, by which the first ribs are united to
the sternum (sternal ribs), whilst the latter are united one
to the other without being directly connected with the
sternum (asternal ribs), are, as a rule, in quadrupeds, directed
obliquely downwards, forwards, and inwards ; each forms,
with the rib to which it belongs, an obtuse angle more or less
open anteriorly. Their length is proportionate to that of
the ribs. The cartilages, which are continued from the
asternal ribs, unite and form the borders, directed obliquely
downwards and forwards, of the fossa which is found at the

OSTEOLOGY AND ARTHROLOGY 19

inferior and posterior part of the thorax, and which forms
the lateral limits of the epigastric region. In the dog and cat
the ribs are thick and almost cylindrical ; the costal car-
tilages are thicker at the margin of the sternum than at their
costal extremity. In the ox, the ribs are flattened laterally
and are very broad, the more so as we examine a portion
further from the vertebral column. From the second to the
twelfth they are quadrangular in the superior fourth, and
thicker than in the rest of their extent. The first costal
cartilage is vertical ; the following ones are progressively
more oblique in a direction downwards and forwards. The
four or five cartilages which succeed the first unite with slight
obliquity to the sternum ; their union with that bone gives
the impression of a very strong, well-knit apparatus. The
costal cartilages which unite with the sternum are flattened
laterally in the portions next the ribs, and flattened from
front to back in the rest of their extent.

In the horse the ribs increase in length from the first to the
ninth ; they are flattened from without inwards, and increase
in width from the first to the sixth or seventh, and the fol-
lowing ones become narrower. The costal cartilages, from
the second to the eighth, are, as in the ox, at first flattened
laterally, near the ribs ; while near the sternum they are
flattened from front to back.

In birds, the ribs are each furnished with a flat process
(Fig. 18, 10), which springs from the posterior border, is
directed backwards, and overlaps the external surface of
the succeeding rib. These processes are not found, as a rule,
on the first or last ribs

As for the costal cartilages, they are, as a rule, ossified,
and receive the name of inferior ribs (Fig. 18, 11), united to
the preceding (superior ribs ; Fig. 18, 9) by articulation ;
by the other extremity they are joined to the sternum ; the
first superior ribs generally want them. Sometimes the last
inferior rib becomes connected with the one that precedes it,
not articulating with the sternum ; and thus recalls the
relations of the asternal ribs which we have noticed in our
study of the mammals.

In the bat, as in birds, the costal cartilages are ossified.

2 — 2

20 THE ARTISTIC ANATOMY OF ANIMALS

THE ANTERIOR LIMBS^

The anterior limbs, homologous to the upper limbs in
man, are formed, as in the latter, of four segments : the
shoulder, the arm, the forearm, and the hand. These limbs,
considered in the vertebral series, present themselves under
very different aspects, which are determined by the functions
they are called upon to perform.

They constitute the forepaw in terrestrial mammals ; in
aerial vertebrates they form wings ; in aqueous mammals
they act as paddles. In whatever series we study them,

Fig. 8. — Anterior LiMr; of the Bat : Left Side, Anterior Surface.

I, Clavicle ; 2, scapula ; 3, humerus ; 4, radius ; 5, cubitus ; 6, carpus ;
7, thumb ; 8, metacarpus ; 9, phalanges.

we can readily find the relationship of the different parts ;
it is very easy to recognise the same bones in the upper limbs
of the human being, the wings of the bat (Fig. 8) and of
birds (Fig. 21), and in the anterior paddles of the seal (Fig. 9)
and of the dolphin.

In quadrupeds, the shoulder and arm are hidden, the
latter more or less completely, in the muscular mass which
binds it to the lateral wall of the trunk ; so that the anterior
limbs only present ; free from the trunk : the elbow, forearm,
and hand.

The Shoulder

In some vertebrates, the shoulder is formed of two bones —
the scapula and clavicle ; in others of only one bone — the
scapula ; the clavicle in this case does not exist.

* Consult Fii^s. 21, ^t,, 34, 38, 39, 46.

OSTEOLOGY AND ARTHROLOGY

21

The Scapula or Omoplate. — The scapula is situated
on the lateral surface of the thorax, and is directed obliquely,
from above downwards and from behind forwards.

We must first recall, so as to be able to make a comparison,
that in man this bone is placed at the posterior surface of the
thoracic cage ; so that if we look at the human thorax
on one of its lateral aspects we see chiefly the external
border of the scapula ; it is the external surface (homo-
logous to the posterior surface of the human scapula) which
we see in its full extent when we look on the same surface
of the thorax in quadrupeds.

Fig. 9. — Anterior Limb of the Seal : Left Side, External Surface.

I, Scapula ; 2, humerus ; 3, radius ; 4, ulna ; 5, carpus ;
6, metacarpus ; 7, phalanges of the fingers.

To sum Up, if we fancy the human being in the position
of the quadruped, the scapula will have its surfaces almost
parallel to the ground (Fig. 10) ; while in quadrupeds, the
surfaces are situated in a plane which is almost perpendicular
to the ground (Fig. 11). This position of the scapula in an
almost vertical plane is designed to give the necessary point
of support to the osseous columns that form the skeleton
of the other portions of the anterior limbs.

Because of this position of the scapula (Figs. 12 and 13),
the spinal border is superior, the cervical, anterior, and the
axillary, posterior. In direct contrast to what obtains in the
human scapula, the spinal border is the shortest of the

22

THE ARTISTIC ANATOMY OF ANIMALS

three ; except in the bat, and the majority of the
cetaceans.

In certain animals (in the ungulates [hoofed*] — pigs, oxen,
sheep, horses) the superior, or spinal, border of the scapula is
surmounted by a cartilage called the cartilage of prolongation.

This is the cause why the border to which it is fixed is so

Fig. io. — Situation and Direc- Fig. ii. — Position and Direction

TioN OF the Scapula in the
Human Being, the Trunk being
Horizontal, as in Quadrupeds.
Vertical .\nd Transverse Sec-
tion OF THE Thorax (Diagram-
matic Figure).

Contour of the thorax; 2, 2, the
scapula.

OF THE Scapula in Quadrupeds.
Vertical and Transverse Sec-
tion OF THE Thorax (Diagram-
M.\Tic Figure).

Contour of the thorax ; 2, 2, the
scapula.

slightly noticeable under the skin in these animals ; indeed,
in the upper part, the bone and cartilage are not distinguish-
able in the contour of the corresponding region of the back ;
being applied to the lateral surfaces of the spinous processes,
the prominence formed by the extremities of which is directly
continuous with the plane of the scapula (Fig. i6).

For the definition of the word hoofed, see p. 2-

OSTEOLOGY AND ARTHROLOGY

23

In quadrupeds whose scapula, on the contrary, is wanting
in the cartilage of prolongation (in the clawed,'^ such as the
cat and dog), the superior border of the scapula is visible,
especially when the animal is resting on its fore-limbs, par-
ticularly when it crouches ; at such a time the skin is mark-
edly raised by that border ; and the spinous processes of
the vertebrae, beyond which it projects, occupy the bottom

1

Fig. 12. — Left Scapula of
THE Human Being, Pos-
terior Surface, placed
IN THE Position which
it would Occupy in the
Skeleton of a Quad-
ruped.

I, Cervical border; 2,
spinal border; 3, axillary
border; 4, supraspinous fossa;
5, subspinous fossa; 6,
scapular spine ; 7, glenoid
cavity; 8, coracoid process;
9, acromion process.

Fig. 13. — Left Scapula of a Horse:
External Surface.

I, Cervical border; 2, spinal border —
the scapula here represented, being from
a hoofed animal, has a cartilage of exten-
sion attached to its spinal border ; 3,
axillary border ; 4, supraspinous fossa ;
c, subspinous fossa ; 6, spine of the
scapula ; 7, glenoid cavity ; 8, coracoid
process. The scapula of the horse has no
acromion process, but it is easy, if we
compare the human scapula, to judge of
the position which this process would
occupy if it were present.

of a fossa (Fig. 15). The internal surface of the scapula
is turned towards the ribs ; it is known, as in man (in whom
this surface is anterior), as the subscapular fossa.

Its external surface is divided into two parts by the spine
oi the scapula ; which, in some animals, terminates inferiorly
in a flat and clearly distinct process, the homologue of the

* For the definition of this word, see p. 37,

24

THE ARTISTIC ANATOMY OF ANIMALS

acromion process of the human scapula. The two regions
separated by the spine are known as the supraspinous fossa
and the infraspinous fossa. The supraspinous fossa is anterior
to the spine, and the infraspinous is posterior to it. The
surfaces of the scapula are, in quadrupeds, flatter than
in the human being, and in particular the subscapular fossa,
which is also less concave. Some authors attribute this to
the lesser curvature of the ribs in quadrupeds. A few words

Fig. 14. — Vertical and Transverse
Section, at the Site of the
Shoulders, of the Thorax of the
Horse (Diagrammatic Figure).

I, Outline of the thorax at the level
of the third dorsal vertebra; 2, 2,
scapula ; 3, spinal border of the
scapula ; 4, cartilage of prolongation ;
5, contour of the skin.

Fig. 15. — Vertical A.ND Trans-
verse Section, at the Plane
OF THE Shoulders, of the
Thorax of a Dog ^Diagram-
MATic Figure).

I, Outline of the thorax at the
level of the third dorsal vertebra ;
2, 2, scapula; 3, spinal border of
the scapula; 4, contour of the skin.

will suffice to prove that there must be another reason.
The scapula is not in immediate contact with the ribs ; the
subscapular fossa is not moulded on them. Besides, the
form of the scapula is, as in other parts of the skeleton,
dependent on the disposition of muscles, and the develop-
ment of these latter is correlated to the extent and energy
of the movements which the individual is able or required

OSTEOLOGY AND ARTHROLOGY 25

to execute. But the movements which those muscles
produce (more especially the rotation of the humerus) are,
in quadrupeds, less extensive than in the human being ;
and, consequently, the muscles which produce them are,
proportionally, less strongly developed. The inferior angle
(superior and external in man), situated at the junction of
the cervical and axillary borders, presents the glenoid
cavity, which, looking downwards, receives the articular
surface of the superior extremity of the bone of the arm —
that is to say, the head of the humerus. Above this
cavity, on the lower part of the cervical border, is situated
a tubercle which reminds us of the coracoid process of
the human scapula. The region occupied by the glenoid
cavity is separated from the body of the bone by a constric-
tion— the neck of the scapula.

In birds the scapula is elongated in a direction parallel to
the vertebral column, and very narrow in the opposite
(Fig. 18) ; it is also flat, and has no spine. Its coracoid
process is represented by a peculiar bone — the coracoidean
or coracoid bone — which we shall describe later on when
we come to the study of the clavicle and of the anterior
region of the shoulder (see p. 26).

The Clavicle. — The clavicle is found only in the human
being, and in animals whose anterior limbs, possessing
great freedom of movement in all directions, require
that the scapula should possess a point of support which,
while affording this, can be displaced with it, or draw it
in certain directions. Now, this point of support is
furnished by the clavicle.

In S.nimals possessed of hoofs (ungulates), such as the
sheep, ox, and horse, the clavicle does not exist. Indeed,
in them the freedom of movement of the anterior limbs is
limited ; they move by projection in the forward and
backward directions only ; they merely fulfil the functions
of giving support to and carrying about the body. The
clavicle is rudimentary in the cat and the dog ; in the cat
it is a small, elongated bone (Fig. 16), 2 centimetres in
length, thin and curved, connected with the sternum and
the scapula by ligamentous bundles. In the dog it is

26 THE ARTISTIC ANATOMY OF ANIMALS

represented by a small osseous plate only (Fig. 17),
which is not connected with any of the neighbouring
bones.

It is on the deep surface of a muscle which passes from
the head and neck to the humerus (mastoido-humeral, a
muscle common to the arm, neck, and head) in which this
rudimentary bone is found to be developed.

The clavicle exists in perfect state in mammals which
use their limbs for digging, grasping, or flying ; the insecti-
vora (hedgehog, mole) and some rodents (squirrel, wood-
chuck) are provided with it.

The cheiroptera (bats) possess an extremely well-developed
clavicle, on account of the varied movements which their
thoracic limbs execute.

This formation of the shoulder which favours flight in
the bat is even more remarkable in birds. In these latter

Fig. 16. — Left Clavicle of the Cat: Fig. 17. — Clavicle of tup,
Superior Surface (Natural Size). Dog (Natural Size).

I, Internal extremity ; 2, external ex-
tremity.

(Fig. 18) the clavicles, fused together by their lower extremi-
ties, form one bone, having the shape of the letter V or U,
which is known as the fourchettc ; this bone, acting as a
true spring, keeps the shoulders apart, and prevents their
approximation during the energetic movements which flight
necessitates.

In birds whose power of flight is strong, the two limbs
of this bone are widely separated and thick, and the four-
chette is U-shaped. Those whose flight is awkward and
but slightly energetic have the limbs of the fourchette
slender ; they unite at a more acute angle, and the bone is
V shaped.

Furthermore, a bone named the coracoid joins the scapula
to the sternum ; this bone, often fused with the scapula,
where it contributes to the formation of the glenoid cavity,
represents in birds the coracoid process of the human

OSTEOLOGY AND ARTHROLOGY

27

scapula. If we fancy this process directed inwards, and
sufficiently lengthened to join the sternum, we shall have
an idea of the disposition of the bone we are now discussing,
and the reasons for which the name has been chosen by
which it is designated. The coracoid bone, like the fourchette

Fig. iS. — Skeleton of the Shoulder of a Bird (Vulture) : Antero-
ExTERNAL View of the Left Side.

I, Left clavicle ; 2, inferior portion of the right clavicle, forming b}' its
ankylosis with that of the other side the fourchette; 3, coracoid bone ;
4, scapula; 5, articular surface for humerus; 6, superior half of the
sternum ; 7, keel of sternum ; 8, spinous process of the dorsal vertebrae ;
9, superior ribs ; 10, process of one of these ribs ; 11, inferior ribs.

which it reinforces, offers to the wings a degree of support
proportionate to the efforts developed by those limbs ; for
this reason it is thick and solid in birds of powerful flight.

The superior extremity of each branch of the fourchette,
at the level of its junction with the coracoid and the scapula,
bounds, with these latter, a foramen which gives passage to

28 THE ARTISTIC ANATOMY OF ANIMALS

the tendon of the elevator muscle of the wing, or small
pectoral. The importance of the fourchette being, as we
have seen, in proportion to the movements of flying, it is
easy to understand that the bone is not found in the ostrich.

The Arm

A single bone, the humerus, forms the skeleton of this
portion of the thoracic limb.

The Humerus. — The bone of the arm is, in quadrupeds,
inclined from above downwards and from before backwards.

It is, with relation to other regions, short in proportion
as the metacarpus is elongated, and as the number of digits
is lessened. In the horse, for example, whose metacarpus
is long, and in which but one digit is apparent, the humerus
is very short. The slight development in length of the
humerus explains its close application to the side of the
animal as far as the elbow.

In animals in which the humerus is longer, the bone is
slightly free, as well as the elbow, at its inferior extremity.
Later on we will return to the consideration of this
peculiarity and of the proportions of the humerus, after
we have studied the other parts of the fore-limbs.

The humerus in quadrupeds is inflected like the letter S ;
in man this general form is less accentuated, the humerus
being almost straight. On its body, which appears twisted
on its own axis, we find the musculo-spiral groove,* which
crosses the external surface, and is very deep in some animals.
Above this groove, and on the external surface, there exists
a rough surface which is the impression of the deltoid. In

* It would be going outside our province to tliscuss whether the
humerus is really twisted on its axis. This question, often discussed, has
been solved in some recent works in the following manner : the humerus
has undergone torsion at the level of its superior extremity, and not
at the level of its body ; this does not authorize us further to accord any
definite sense to the denomination ' groove of torsion ' (musculo-spiral
groove). That which we must especially remember in connection with
this fact, is, as we shall afterwards see, the difference of direction which the
articular head presents according as the torsion has been more or less
considerable; because this is established, according to the same order, in
man and in quadrupeds.

OSTEOLOGY AND ARTHROLOGY 29

some species this rugosity is very prominent, and is called
the tuberosity of the deltoid ; it is prolonged downwards by
a border which forms the anterior crest of the musculo-spiral
groove and limits this latter in front. The external border
of the bone, or posterior crest of the groove, limits it behind.

The superior extremity is enlarged, and remarkable in
three portions which it presents ; these are : an articular
surface and two tuberosities.

The articular surface, or head of the humerus, smooth and
round, is in contact with the glenoid cavity of the scapula.
This head in the human skeleton is directed upwards and in-
wards ; in quadrupeds its direction is upwards and back-
wards. The inferior extremity, having in both one and
the other its long axis directed transversely, and the point
of the elbow looking backwards in all, the result is that the
head of the humerus is not situated vertically above the
same regions ; in the first, it is almost directly above the
internal part of this extremity ; in the latter, it is situated
above its posterior surface, or the point of the elbow in
the complete skeleton This difference of direction is corre-
lated with the position of the scapula, the glenoid cavity
of which, as we have already seen, is in man turned out-
wards, whereas in quadrupeds it looks downwards. In
the latter case the scapula consequently rests on the head
of the humerus ; and this position is most favourable for the
performance of the functions which the anterior limbs have
to fulfil in these latter.

Of the tuberosities of the head of the humerus, one is
situated on the external aspect — it is the great tuberosity, or
trochiter ; the other is placed internally — it is the small
tuberosity, or trochin. The great tuberosity is divided into
three parts — summit, convexity, and crest ; these different
parts give insertion to the muscles of the shoulder. We
recollect that the facets (anterior, middle, and posterior) of
the great tuberosity of the humerus in man give attachment
to the muscles of the same region. The head of the humerus
in the human body projects above the tuberosities. We
shall see afterwards, when dealing with some special quadru-
peds, that in some of these, on the other hand, the tubero-

30 THE ARTISTIC ANATO^LY OF ANIMALS

sities are on a higher level than the articular head of the
bone. Between the two tuberosities is the bicipital groove.
In man, the superior extremity of the humerus, although
covered by the deltoid, reveals its presence by elevating
the corresponding portion of the latter. In quadrupeds, the
anterior part of this extremity, although similarly covered by
muscular bundles, produces a prominence under the skin.
This prominence is situated at the summit of the angle
formed by the opposing directions of the scapula and the
bone of the arm, and constitutes what is known by
the name of the point of the shoulder, or of the point of
the arm.

The inferior extremity, transversely enlarged, presents an
undulating articular surface, which reminds us of the trochlea
and the condyle of the human humerus ; on which, how-
ever, the condyle is more sharply defined from the trochlea.
In the human skeleton, the internal lip of the trochlea
descends lower than the external ; and also lower than the
condyle. In the bear, the cat, and the dog, it is the same.
In the ox and the sheep, the condyle is lower than the
trochlea, but only very little lower. In the horse the
arrangement is still the same, but a little more accentuated.
On the lateral parts of this extremity we find : internally,
a prominence, the epitrochlea ; and, externally, another,
the epicondyle. It is from this latter that the crest arises,
which, passing upwards, forms the posterior limit of the
groove of torsion.

The two prominences, which we have just described from
a general point of view, present special arrangements which
it is necessary to point out. When we examine the form
of the outline of the inferior extremity of the humerus in
man, the bear, the cat, the dog, the ox, and the horse, we
find in following this order that the extremity tends to
become narrow transversely, and that the epicondyle and
the epitrochlea are less and less prominent on the external
and internal aspects respectively. These two processes,
indeed, project backwards ; the epitrochlea always remain-
ing more developed than the epicondyle. Because of this
projection backwards, the cavity situated on the posterior

OSTEOLOGY AND ARTHROLOGY

31

surface of the inferior extremity, the olecranon fossa, is
very deep, more so than in the humerus of man. Its borders
being thus formed by the two processes, are very prominent.
In front we find the coronoid fossa, wliich is less deep than
that of which we have just spoken.

There exists in some mammals an osseous canal, situated
above the epitrochlea, and known as the supratrochlear
canal (Fig. 19). It is bounded by a plate of bone which
at its middle portion is detached from the shaft of the
humerus, and blends with the latter at both its extremities.

'L^.Ci

Fig. 19. — Inferior Extremity of
THE Left Humerus of a Felide
(Lion).

I , Epitrochlea ; 2, supra-epitrochlear
foramen.

E5>.C.

Fig. 20. — Inferior Extremity of
the Left Human Humerus,
showing the Presence of a
Supratrochlear Process.

I , Epitrochlea ; 2, supra-epitrochlear
process.

The brachial artery and median nerve pass through the
foramen.

A similar condition is sometimes found, as an abnormality,
in man, which presents itself under the following aspect
(Fig. 20) : an osseous prominence more or less long, in the
shape of a crochet-needle — supra-epitrochlear process —
situated 5 or 6 centimetres above the epitrochlea ; the
summit of this process gives attachment to a fibrous band,
which is inserted by its other end into the epitrochlea and
the internal intermuscular aponeurosis. The fibro-osseous
ring thus formed gives passage to the brachial artery and the

32 THE ARTISTIC ANATOMY OF ANIMALS

median nerve, or in case of a premature division of this
artery to the ulnar branch of the same.*

There is also found in some mammals a perforation of
the thin plate of bone which, in others, separates the ole-
cranon fossa from the coronoid. This perforation is some-
times found as an abnormality in the human humerus.

As does the sternum and the skeleton of the shoulder, the
humerus of birds presents differences correlated to the
functions which the thoracic limbs are destined to fulfil.
Lying on the side of the thorax, directed obliquely down-
wards and backwards (Fig. 21), it is proportionately longer
in individuals of powerful flight than in those which fly
less or not at all. In the vulture it projects beyond the
posterior part of the pelvis ; in the cock it does not even
reach the anterior border of the same. To these differences
in length are added differences in volume and in the develop-
ment of the processes which serve for muscular attach-
ment, which are more considerable in birds of powerful flight.

The humerus is so placed that the radial border, external
in man and quadrupeds, looks upwards, with the result that
the surface of the bone of the arm, which in these latter is
anterior, in the former looks outwards. The humeral head,
which is turned forwards and a little inwards, is convex
and elongated in the vertical direction. Behind and above
this head is found a crest for the insertion of muscles. It is
the same for the region below, where there is a tuberosity
whose inferior surface presents a pretty large opening
which looks inwards to a fossa from the floor of which a
number of minute openings communicate with the interior
of the bone. This is the pneumatic foramen of the humerus.

It is of interest to remember in connection with this subject
that in birds, in keeping with the conditions of flight, every
system of organs is adapted to diminish the weight of the
body. We particularly draw attention to the osseous
framework, the structure of which is such that the weight

* For further details of this anomaly, see Testut, ' The Epitrochlear
Process in Man ' (International Journal of Anatomy and Physiology, 1889) ;
A. Nicolas, ' New Studies on the Supratrochlear Process in Man ' (Review
of Biology of tlie North of France, t. iii., 1890-18Q1).

OSTEOLOGY AND ARTHROLOGY

33

of the animal is greatly lessened. This condition is secured
by the pneumaticity. The bone consists of a cover of
compact tissue, which, instead of enclosing marrow, is

lb 10 n

EA.C.

Fig. 21. — Skeleton of a Bird (Vulture): Left Surface.

I, Cranium ; 2, face ; 3, cervical vertebrae ; 4, spinous processes of
the dorsal vertebrae ; 5, coccygeal vertebrae ; 6, sternum ; 7, keel ; 8,
superior ribs; 9, inferior ribs; 10, clavicle; 11, coracoid bone (for the
details of the skeleton of the shoulder, see Fig. 18) ; 12, humerus; 13,
radius ; 14, ulna ; 15, carpus ; 16, hand (for details of the skeleton of
this region, see Fig. 31); 17, ilium; 18, ischium; 19, pubis (for the details
of the pelvis, see Fig. 46) ; 20, femur ; 21, tibia ; 22, fibula ; 23, osseous
nodule, which some anatomists think represents the calcaneum ; it is
the sole vestige of the tarsus ; 24, metatarsus ; 25, foot ; 26, first toe (for
the details of the skeleton of the foot, see Fig. 48).

hollowed out by cavities which contain air, and communicate
with special pouches, the air-sacs, which are appendages of
the lungs.*

* The presence of air in the bones does not seem to be always associated
with the pov.'er of flight ; as a matter of fact, we find air spaces in the bones
of some birds which do not fly (E. J. Marey, ' The Flight of Birds,' Paris,
1890, p. 51).

3

34 THE ARTISTIC ANATOMY OF ANIMALS

The antibrachial extremity of the humerus is flattened
from without inwards. It terminates in two articular
surfaces, which articulate with the radius and ulna.

The olecranon process of the ulna being slightly developed,
it follows that the olecranon fossa is not large ; neither is
the coronoid.

General View of the Form of the Forearm and Hand

We now proceed to the study of the two regions of the
fore-limbs which present the greatest variety in regard to
the number of bones and also in regard to form and pro-
portions. These two regions are the forearm and the hand.
It is first of all necessary to say that in man, when the
fore-limb hangs beside the body, and the dorsum of the hand
looks backwards, the two bones of the forearm are parallel,
and that this position is known by the name of supination.
It is also necessary to remember that there is another
attitude, in which the radius, crossing the ulna, and carrying
the hand with it, displaces the latter in such a way that the
palmar surface looks backwards. This second position is
known as pronation.

Let us now suppose that a man wishes to walk in the
attitude of a quadruped. It will be necessary, in order that
his upper limbs, being for the moment anterior ones, may act
as members of support, to place the forearm in pronation, in
order that, as is more normal, the hands may rest on the
ground by their palmar surfaces. In this position the radius,
being rotated on its own axis at its upper extremity and
around the ulna in the rest of its extent, shall have its
inferior extremity situated on the inner side of the corre-
sponding extremity of the latter.

Such is the situation of the bones of the forearm and the
attitude of the hand in quadrupeds. In short, quadrupeds
have their anterior members in the position of pronation.

The individual whom we have just supposed placed in the
attitude of a quadruped would be able to maintain this
position by pressing en the ground more or less extensive
portions of his hands ; the whole palm of the hand may
be applied to the ground (Fig. 22) ; or the fingers only —

OSTEOLOGY AND ARTHROLOGY

35

that is to say, the phalanges (Fig. 23) ; or the extremities of
the fingers only — that is to say, the third phalanges (Fig. 2.|).
This last position, which is certainly difficult to maintain,
should here be regarded rather as theoretical.

We shall meet with each of these modes of support in
certain groups of animals. Thus, the bear, badger, and the
majority of rodents, have the paws applied to the ground
by the whole extent of the palmar surface of the hand, from
the wrist to the tips of the fingers. They are therefore called
plantigrade, from the analogy, in this case, of the palm of
the hand to the plantar surface, or sole of the foot.

Fig. 22.-

EJ^.C.

-The Human Hand resting for its Whole Extent on its
Palmar Surface : Left Side, External Surface.

In others, such as the lion, tiger, panther, cat, wolf, and
fox, the support is made no longer on the whole extent of
the palmar surface, but on the corresponding surface of the
fingers only — the metacarpus is turnea back, and, conse-
quently, the wrist — that is to say, the carpus — is removed
from the ground. These are the digitigrades.

Lastly, the ruminants (sheep, oxen, deer, etc.), and also the
pig, ass, and horse, rest on the third phalanx only. In
them not only is the metacarpus turned back, but also the
two first phalanges. The wrist is very far removed from
the ground. In these animals, the third phalanx is
enclosed in a case of horn, a nail (the hoof), and because

3—2

36 THE ARTISTIC ANATOMY OF ANIMALS

the support of the hmb is on that nail, the name of unguH-
grades lias been given them. Nevertheless, as the point
of support is on the third phalanx, which is also known by
the name of phalangette, we are of opinion that, in order to
specify definitely, although they walk on their fingers, as
do the digitigrades, the support is provided not by the

Fig. 23. — The Human Hand rest-
ing ON ITS Phalanges : Left
Side, External Surface.

Fig. 24. — The Human Hand rest
ing on the Tips of some of its
Third Phalanges : Left Side,
External View.

whole extent of those appendages, they might receive
the name of phalangettigrades.

It is necessary among the ruminants to make an exception
of the camel and the llama, which are digitigrades.

Just in proportion as the hand is raised from the ground, as
we have just seen in passing from the plantigrades to the
digitigrades and unguligrades, the number of bones of that
region diminishes, the bones of the forearm coalesce, and

OSTEOLOGY AND ARTHROLOGY 37

the ulna tends to disappear ; the hand becomes less and less
suitable for grasping, climbing, or digging, so as to form
an organ exclusively adapted for walking and supporting
the body.

Thus, the bear (plantigrade) has five digits, and the
power of performing the movements of supination and
pronation. Indeed, we know with what facility this animal
is able to move his paws in every direction, and climb a tree
by grasping it with his fore-limbs. It is well known,
however, that no animal except the ape can perform the
movements of rotation of the radius around the ulna
with the same facility as man ; and that none possesses the
same degree of suppleness, extent, and variety of move-
ments of the forearm and hand.

In the digitigrades there is one finger which is but slightly
developed, and which is always removed from the ground —
that is, the thumb : there is also a little less mobility of the
radius around the ulna.

In the ungulates the limbs are simply required to
perform the movements of walking, and form veritable
columns of support, which become the more solid as
they are less divided. The bones of the forearm are fused
together ; there is therefore no possibility of rotation
of the radius around the ulna. The metacarpus is
reduced to a single piece, which in the horse consti-
tutes what is known as the canon. The number of digits
becomes diminished, so that in ruminants there are not
more than two, and in the horse but one. We should,
however, add that, up to the present, we have taken into
account only perfect digits, those that rest on the ground.
We shall see further on that there exist supplementary
digits, but that they are only slightly developed, and are
represented in some cases by mere osseous spurs ; it is this
fact that has permitted us to ignore them in the general
study which we have just made.

Because, as we have already said, the unguligrades have
the inferior extremity of the digit encased in a horny sheath,
which forms the hoof of the horse and the corresponding
structures [onglons) in the ox, those animals have been

38 THE ARTISTIC ANATOMY OF ANIMALS

placed in a special group, which is based on that peculi-
arity-— that is, the group of ungulate mammals.

The plantigrades and digitigrades, of which the paws
have their surfaces of support strengthened by an epidermic
sole and fatty pads, have the free extremities of the third
phalanges covered on their dorsal surface by nails or claws ;
hence they are named ungniculate mammals.

The bat and birds have the bones of the forearm so
arranged that the radius cannot rotate around the ulna. This
is necessary in order that during flight, when the wing is
being lowered, the radius and hand shall not be able to turn ;
for, if such rotation took place, each stroke of the wing would
place it in a vertical position, which would occasion a loss of
resistance incompatible with the effect to be obtained.

The Forearm

The skeleton of the forearm in quadrupeds is vertical in
direction ; consequently, it forms with the arm an angle
open anteriorly ; this is well seen on examining the lateral
surface. If we examine it on its anterior surface, we find
a slight obliquity directed downwards and inwards. In
animals in which the bones of the forearm are separate —
that is to say, susceptible of supination and pronation —
we find a more close resemblance to those of the human
skeleton. The ulna, the superior extremity of which always
projects beyond that of the radius, has a shaft which gradu-
ally narrows from above downwards. Its inferior extremity
is terminated by a round head in those animals in which the
ulna is fully developed ; in others, as it is atrophied, it ends
in a thin, long process.

The ulna presents at its superior extremity a posterior
process, the olecranon, which forms the point of the elbow.
We find on the anterior surface of the same, another process,
the coronoid.

It is necessary to dwell on the relations of these parts.
In man the head of the radius is situated at the anterior
part of the external surface of the superior extremity of the
ulna (Fig. 25) ; indeed, the small sigmoid cavity with which

OSTEOLOGY AND ARTHROLOGY

39

the head articulates is situated on the outer side of the
coronoid process, and this apophysis is placed in front.
In the plantigrades and digitigrades the head of the radius
is placed still more forward, so much so that it is situated
almost in front of the superior extremity of the ulna (Fig. 26).
In the unguligrades it is placed directly in front of this
latter (Fig. 27).

Further, the displacement of the radius is made at the
expense of tlie superior extremity of the neighbouring bone ;
the radius appears to appropriate more and more the parts
which in man belong exclusively to the ulna — for example,
the coronoid process. '- In the plantigrades and the digiti-

FiG. 25. — Superior Extremity of
THE Bones of the Human Fore-
arm : Left Side, Superior Sur-

FACE.

Fig. 26. — Superior Extremity of
THE Bones of the Forearm of
THE Dog: Left Limb, Superior
Surface.

I, Radius; 2, ulna; 3, olecranon i, Radius; 2, ulna; 3, olecranon
process ; 4, coronoid process. process ; 4, coronoid process.

grades half of the process still belongs to the ulna and the
remainder to the radius. In the ungulates — the horse, for
example — the coronoid process belongs to the radius ; the
ulna, situated behind the latter, is correspondingly dimin-
ished in size.

In brief, when we study this region of the skeleton in
plantigrades, then in digitigrades, and finally in unguligrades,
we find a kind of progressive absorption of one of the two
bones (ulna) by the other (radius), which thus becomes the
more developed.

It is easy to explain this partial disappearance of the
ulna. When the forearm is capable of performing the

40

THE ARTISTIC ANATOMY OF ANIMALS

movements of pronation and supination, the ulna is com-
pletely developed, for it is in its small sigmoid cavity that
the head of the radius revolves, and it is around its inferior
extremity, the head, that the corresponding extremity of
the radius turns. But when the movements of rotation
of the forearm do not exist, the inferior extremity of the
ulna becomes functionally useless and disappears. As to
its role in the movements of the region of the wrist.

Fig. 27. — Superior Extremity of the Bones of the Forearm of
THE Horse : Left Limb, Superior Surface.

I, Radius ; 2, ulna ; 3, olecranon process ; 4, coronoid process.

that is nil, for we may remember — we will observe it again
when we come to treat of the articulations — that the hand
articulates with the radius alone (radio-carpal articulation) ;
this is the reason that, when the forearm possesses the
fullest mobility, the hand follows the movements which
that bone makes around the ulna.

It is not so with the articulation at the elbow- joint ; there
it is the ulna, which, with the humerus, forms the essential
parts (humero-ulnar articulation) ; its olecranon process

OSTEOLOGY AND ARTHROLOGY

41

limits the movement of extension of the forearm. It is for
this reason that, even in those quadrupeds in which the ulna

Fig. 28. — Inferior Extremity of the Bones of the Forearm of a
Man : Left Side, Posterior Surface, Position of Supination.

I, Radius ; 2, ulna ; A, groove for the long abductor and short extensor
muscles of the thumb ; B, groove for the radial muscles ; C, groove for the
long extensor of the thumb ; D, groove for the special extensor of the index
finger and of the common extensor of the fingers ; E, groove for the proper
extensor of the little finger ; F, groove for the posterior ulna.

is atrophied, the olecranon process presents a relatively
considerable degree of development.

We know that on the posterior surface of the inferior

Ei^C

Fig. 29. — Inferior Extremity of the Bones of the Forearm of the
Dog : Left Side, Anterior Surface, Normal Position — that
is, the Position of Pronation.

I, Radius; 2, ulna; A, groove for the long abductor and for the short
extensor of the thumb ; B, groove for the radials ; D, groove for the long
extensor of the thumb, the special extensor of the index-finger, and the
common extensor of the fingers ; E, groove for the special extensor of the
little finger.

extremity of the bones of the human forearm are grooves
in which pass the tendons of the posterior and external

42

THE ARTISTIC ANATOMY OF ANIMALS

muscles which, belonging to this regicn, arc directed for
insertion towards the hand.

In animals, because of the movement of rotation of the
radius, the surface of this bone, which is anterior, corre-
sponds to the posterior surface of the same in man. (To
p( ssess a clear conception of this, it is necessary to remember
that, in this latter, the bones of the forearm are always
described as in the position of supination ; they are thus
represented in Fig. 28. The direction of the surfaces of
the radius is the reverse of that in animals, since the latter
have the radius always in a state of pronation.)

Consequently it is on the anterior surface of the bone that

Fig. 30. — Inferior Extremity of the Bone of the Forearm of the
Horse : Left Side, Anterior Surface.

I, Radius ; A, groove for the long abductor and the short extensor of
the thumb ; B, groove for the radials ; D, groove for the common extensor
of the digits ; E, groove for the special extensor of the httle finger.

we find the grooves concerning which it is necessary to give
some details. Regarding them in passmg from the radius
towards the ulna, those grooves give passage to the tendons
of the muscles whose names occupy the columns on p. 43.
The letters which are referred to each serve to define their
order, and to facilitate reference to Figs. 28, 29, and 30.

We should mention that the groove E is situated, both in
man and in the dog, at the level of the inferior radio-ulnar
articulation ; but that in the horse, as the ulna does not
exist at that level, the groove is situated on the external
surface of the inferior extremity of the radius. It is neces-
sary to add that, in some horses, the ulna is, nevertheless,

OSTEOLOGY AND ARTHROLOGY

43

Man.

A. Long abductor
of the thumb,
and short ex-
tensor of the
thumb.

B. First and
second external
radials (extensor
carpi radialis lon-
gior and brevior).

C. Long extensor
of the thumb.

Dog.

D. Special exten-
sor of the index
finger and the
common exten-
sor of the
fingers.

E. Special exten-
sor of the little
finger.

F. The posterior
ulnar {extensor
carpi nlnaris).

A. Long abductor of the
thumb and short ex-
tensor of the thumb
united as one muscle,

the oblique extensor of
the metacarpus.*

B. The two radials blended
superiorly, distinct
inferiorly ; this is the
anterior extensor of the
metacarpus.

C. Long extensor of the
thumb and special ex-
tensor of the index
finger united superi-
orly. These muscles
pass in the following
groove.

D. Common extensor of
the digits and the two
preceding muscles.

Horse.

A. Oblique extensor of the
metacarpus, the homo-
logue of the long ab-
ductor of the thumb
and the short extensor
of the thumb, united as
one muscle.

B. The radials represented
by a single muscle, the
anterior extensor of the
metacarpus.

C. The long extensor of
the thumb and the
special extensor of the
index are absent.

D. Anterior extensor of the
phalanges, the homo-
logue of the common
extensor of the digits.

E. Extensor of the third,

fourth, and fifth digits,

or the lateral extensor of

the digits, the homo-

logue of the special ex-
tensor of the little finger.
There does not exist on the forearm a groove for the

posterior ulnar muscle, or external flexor of the

metacarpus.

E. Lateral extensor of the
phalanges, the homo-
logue of the special
extensor of the little
finger.

represented in this region by a tongue-like process of bone ;
and in such cases the groove is situated in front of this
process, at the level of the line of coalescence, which there
represents the articulation.

It is also useful to note, with reference to the groove F,
in which passes, in man, the tendon of the posterior ulnar
muscle, that, when the forearm is in pronation, the radius
alone being displaced, we can only see this groove on the
surface which looks backwards ; and that it is then separated
from the groove which contains the tendon of the special
extensor of the little finger by an interval equal to the thick-

* The words printed in itaUcs are the names used in veterinary
anatomy.

44 THE ARTISTIC ANATOMY OF ANIMALS

ness of the head of the ulna.* When the forearm is supin-
ated, the two grooves are found, on the other hand, one
beside the other : and the tendons which they contain are
very naturally in contact.

In birds the forearm is flexed on the arm, and the latter
being directed downwards and backwards, the former is,
consequently, directed upwards and forwards. Further,
because of the position of the humerus, which, as we men-
tioned on p. 32, has its inferior extremit}' so turned that
the surface which is anterior in man becomes external, the
radius, instead of being outside the ulna, is placed above it.
This latter is larger than the radius, but its olecranon process
is very slightly developed.

The Hand

The hand in animals, as in man, is formed of three parts —
the carpus, metacarpus, and fingers. In man, the forearm
and the hand being described in the position of supination ;
the bones of the carpus are named in passing from the most
external to the most internal — that is to say, from that
which corresponds to the radial side of the forearm to that
which corresponds to the ulnar side. In animals in which,
as we know, but it is not unprofitable to repeat, the hand
is in pronation, the radial side of the forearm being placed
inside, we enumerate the carpal bones in counting the
most internal as the first ; this is the only method which
permits us, in taking our point of departure from the human
skeleton as our standard, to recognise the homologies of the
bones of the carpal region.

These bones, eight in number, are arranged in two trans-
verse rows, of which one, the first, is superior or anti-
brachial ; the other, the second, is inferior or metacarpal.
Each of these rows contains four bones. Considered in
the order we have indicated above — that is to say, proceeding
from the radial to the ulnar side — they are thus named :
scaphoid, semilunar, cuneiform, and pisiform, in the first

* Edward Cuyer, ' Shape of the Region of the Wrist in Supination and
Pronation ' (Bulletin de la Scciitc d'Anthropologie, Paris, 1888).

OSTEOLOGY AND ARTHROLOGY 45

row ; trapezium, trapezoid, os magnum, and unciform, in
the second. The number of these bones is not the same
in all animals on account of the coalescence or absence of
some. In each row the bones are placed side by side, with
the exception of the pisiform, which being placed on the
palmar surface of the cuneiform, produces a small pro-
jection in man, but a very pronounced one in quadrupeds.

The pisiform is called the hooked hone in some veterinary
anatomies. If we consider the hook which it forms, we
may recognise that the name is appropriate ; but from
the point of view of comparison with the human carpus,
the name is unfortunate, for it creates confusion between
the true pisiform (the fourth bone in the upper row), and
the last bone in the lower row, which is the veritable unci-
form bone. We do not here seek for similarity of form, but
homology of regions ; and it is only by using the same
names to denote the same things that we can succeed in
determining such homology.

Taken as a whole, the bones of the carpus form a mass
which, by its superior border, articulates with the bones
of the forearm, and by its inferior border is in relation with
the metacarpal region. Its dorsal surface (anterior in
quadrupeds) is slightly convex ; its palmar surface (pos-
terior in quadrupeds) is excavated, and forms a groove in
which pass the tendons of the flexors of the fingers. This
last, in man, has the appearance of a gutter, because of the
prominences caused by the projection of the internal and
external bones beyond their fellows.

In quadrupeds the palmar groove is especially determined
by the pisiform bone, of which we have just mentioned the
great development.

The region occupied by the carpus, in the unguligrades,
is known as the knee ; it would have been more appropriately
named had it been called the wrist.

The number of the metacarpal bones in mammals never
exceeds five, but it often falls below it ; the same is true
for the digits. The first are generally equal in number to
the latter ; an exception is met with in ruminants, whose
two metacarpals coalescing soon after birth, form but

46 THE ARTISTIC ANATOMY OF ANIMALS

one bone ; this, the canon bone, articulates with two
digits.

The number of metacarpals and digits diminishes in pro-
portion as the limbs cease to be organs of prehension, and
become more exclusively organs of support and locomotion.

The number of phalanges is two for the thumb and three
for each of the other digits ; except in the cetaceans, in
which they are more numerous.

In the bat, the metacarpals and phalanges are very long,
and form the skeleton of the wing ; these phalanges are
not furnished with nails ; the thumb, which is very short,
is alone provided with one (Fig. 8).

With regard to the relative dimensions of the bones of
the metacarpus, it is necessary to remember that, in the
human being, the second metacarpal is the longest ; then,
in the order of decrease, come the third, fourth, fifth, and
first. In quadrupeds we shall also find differences in
length (see the chapter relating to the anterior limbs in
certain animals), but the order ol decrease is not always
that which we have just mentioned.

In man the articular surface, situated at the inferior ex-
tremity of each of the metacarpals, is rounded, and is
called the head. This allows the first phalanx, which is
in relation with that surface, to be displaced in every
direction ; indeed, this phalanx can not only be flexed and
extended, but it can also be moved laterally ; this latter
movement allows of the fingers being separated and drawn
together.

In quadrupeds which can only perform the movements of
flexion and extension of the digits — for example, the horse
— the inferior extremity of the metacarpal has not a rounded
head of a regular outline ; it is marked by a prominent
median crest, directed from before backwards, so that the
articular surfaces, which fit more exactly, form a sort of hinge
which allows of backward and forward movements only, and
permits no lateral displacement. In man, at the level of the
inferior extremity of the first metacarpal, in the vicinity of the
articulation of this bone with the first phalanx of the thumb,
we find two sesamoid bones — small bones developed in

OSTEOLOGY AND ARTHROLOGY

47

the fibrous tissue which surrounds the articulation. We
also meet with such structures, but more rarely, at the level
of the corresponding articulation of the index and auricular
digits ; and, more rarely still, at those of the middle and
ring fingers. In quadrupeds, these bones are normally
developed, and we shall see afterwards that in some
animals, as they reach a considerable size, they are able to
influence the external outlines ; we shall see this, for example,
in the horse.

The hand, in birds, is directed obliquely downwards and
backwards (Fig. 31). For the better understanding of its

Fig. 31. — Skeleton of the Superior Limb of a Bird (Vulture):
Left Side, External Surface.

I, Humerus ; 2, radius ; 3, ulna ; 4, radial bone of the carpus ; 5, ulnar
bone of the carpus ; 6, first metacarpal ; 7, second metacarpal ; 8, third
metacarpal ; 9, first digit, the homologue of the thumb ; 10, first plialanx
of the second digit; 11, second phalanx of the second digit; 12, third
digit.

position in relation to the forearm, we should remember
that this latter, as we have described (p. 44), directed
obliquely upwards and forwards, has the radius placed
aboVe the ulna ; the hand being oblique in the opposite
direction and placed under the forearm is, by this arrange-
ment, inclined towards the ulnar border of the latter.

For the rest, in order to be able to distinguish readily the
corresponding parts in the hand of a bird and that of a man,
we merely have to place the human forearm obliquely, in a
direction upwards and forwards (Fig. 32), the radius being
above ; this position we can obtain by semi-pronation ;

48 THE ARTISTIC ANATOMY OF ANIMALS

then, to incline strongly tlie hand downwards and back-
wards, moving the ulnar border of the hand towards
the ulna ; the thumb is then anterior, the little finger
posterior, and the palm of the hand is turned towards the
trunk.

The carpus in birds is formed by two bones only, with
which the skeleton of the forearm articulates. That
which is in contact with the radius is called the radial hone
of the carpus ; and that with which the ulna articulates
is named the ulnar hone.

The metacarpus is formed of three bones ; the first,
which is very short, is fused at its superior extremity with

Fig. 32. — Superior Limb of the Human Being, the Different
Segments being placed in the Attitude which the Corre-
sponding Parts occupy in Birds : Left Side, External Surface.

the adjoining one ; this latter and the third, both longer than
the first, but of unequal size, are fused at their extremities.
The metacarpal, which articulates with the radial bone of
the carpus, is larger than the one which is in line with the
ulna. To the metacarpus succeed three digits, of which the
central is the longest, and is formed of two phalanges ; the
other two are formed each by a small, stylet-shaped bone.
The middle finger, situated on the prolongation of the
metacarpal, which articulates with the radial bone of the
carpus, has its first phalanx large and flattened transversely ;
this phalanx seems to have been formed by the union of
two bones of unequal development ; the second phalanx

OSTEOLOGY AND ARTHROLOGY 49

is styloid in form. As to the other two fingers, they are
placed, one in front and the other behind ; the first, which
articulates with the short metacarpal, fused at its upper
end with the principal bone of the metacarpus, in position
represents the thumb. The other, which is the third
finger, articulates with the inferior extremity of the thinnest
bone of the metacarpus ; it is sometimes closely united
to the corresponding border of the first phalanx of the large
- — that is to say, of the median — digit.

The Anterior Limbs in Certain Animals

Plantigrades : Bear (Fig. 33). — The scapula of the bear
approaches in shape to a trapezium, of which the angles
have been rounded off. The anterior border (cervical) is
strongly convex in the part next the glenoid cavity. The
junction of the superior (spinal) and the cervical border
forms almost a right angle, the summit of which corre-
sponds to the origin of the spine. At its posterior angle
there is a prominence, directed downwards, the surface of
which is hollowed and is separated from the infraspinous
fossa by a crest, so that at this level a third fossa is added to
the infraspinous one. The neck of the scapula is but slightly
marked. The acromion is prominent, and projects a little
beyond the glenoid cavity.

The clavicle is rudimentary, but, as an example of the
complete development of this bone in plantigrade quadru-
peds, we may cite the marmoset.

The humerus is furnished at its superior extremity with a
large tuberosity, wide, and situated in front of the head of
the bone ; the effect of this is that the bicipital groove is
internal. As in man, the great tuberosity does not reach so
high as the humeral head, but it approaches more nearly
to that level. The deltoid impression is very extensive,
and descends pretty far down on the body of the bone. The
epitrochlea is prominent ; the epicondyle is surmounted by
a well-marked crest, curved and flexuous in outline.

The articular surface, which is in contact with the
radius, is not a regularly formed condyle ; it is a little

4

50

THE ARTISTIC ANATOMY OF ANIMALS

U '-J c .

to i-i O N U <^

OSTEOLOGY AND ARTHROLOGY 51

flattened on its anterior surface, and presents at this level
a slight depression which corresponds to a small eminence
on the anterior aspect of the superior extremity of the
radius. The surface which articulates with the ulna, viewed
on its anterior aspect, has the shape of a slightly-marked
trochlea ; except at the level of the internal lip, which, as
in man, descends lower than the surface for articulation
with the radius (condyle). Behind, the trochlea is more
clearly defined.

The bear possesses a considerable power of rotation of
the radius ; the bones of the forearm are joined only at
their extremities, while in the remainder of their extent
they are widely separated. The ulna terminates below in
a head and a styloid process ; these articulate with the two
last bones of the first row of the carpus — viz., the cunei-
form and pisiform. The bones of the carpus are seven
in number, the scaphoid and the semilunar being fused
together.

The metacarpals, five in number, differ very little from
one another in regard to length, though they increase in
size from the first to the fifth ; this may be demonstrated
by looking at the palmar surface of the hand. It is the
reverse of that which we find in man, for the fifth meta-
carpal is the thickest of all, and the first is the most
slender.

At the level of each metacarpo-phalangeal articulation
are two sesamoid bones.

The third digit is the longest. The terminal phalanges
present two very different portions : one, the anterior, is
curved and pointed ; it serves to support the nail, whose
shape it assumes ; the other, posterior, forms a sort of
sheath into which the base of the nail is received.

The inferior portion of the posterior surface of this latter
part articulates with the second phalanx in the case of
each of the last four digits, but with the first phalanx in
the case of the thumb.

Digitigrades : Cat, Dog (Fig. 34).— In these animals the
anterior (cervical) border of the scapula is convex ; the
posterior (axillary) border is straight or slightly concave.

4—2

THE ARTISTIC ANATOMY OF ANIMALS

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OSTEOLOGY AND ARTHROLOGY

53

The' supraspinous and infraspinous fossae are of equal extent
(Figs. 35 and 36). The neck is short. The spine of the

E^.C.

Fig. 35. — Scapula of the Dog : Left Side, External Surface.

I. Posterior or axillary border ; 2, superior or spinal border ; 3, anterior
or cervical border ; 4, spine of scapula ; 5 , coracoid process ; AA^, length
of spinal border.

scapula becomes more and more prominent towards its
inferior extremity, where it ends in a twisted and inflexed
portion, which represents the acromion process ; this pro-

E^.C

Fig. 36. — Left Scapula of the Cat : External Surface.

I, Posterior or axillary border ; 2, superior or spinal border ; 3, anterior
or cervical border; 4, spine of the scapula; 5, coracoid process; AA^,
length of the spinal border.

cess terminates at the level of the glenoid cavity. The
coracoid process is represented by a small tubercle, slightly

54 THE ARTISTIC ANATOMY OF ANIMALS

curved inwards ; this tubercle is situated above the glenoid
cavity, at the inferior part of the cervical border.

In the dog, the posterior angle, formed by the junction
of the axillary and the superior (spinal) borders, is obtuse ;
the spine rises perpendicularly from the surface of the bone.
The width of the scapula, measured at the level of the
spinal border (from A to A', Fig. 35), equals about half the
length of the spine. We must, however, make an excep-
tion for the turnspit dog, in which the superior border
equals three-fourths of that length. The scapula is, in this
case, of a more compact type ; it is broader, but shorter.
In the cat, the anterior outline of the scapula, formed by
the union of the cervical border and the corresponding half
of the spinal, is more convex ; the posterior angle is not
obtuse, as in the dog. The spine is bent slightly down-
wards and backwards ; before terminating in the acro-
mion process it presents a triangular projection, the apex
of which is directed downwards. The tubercle which re-
presents the coracoid process is curved inwards more
strongly than that of the dog, thus resembling more
closely the appearance of this process in the human
being.

All proportions considered, the scapula of the cat is
broader than that of the dog ; its width, measured along
the length of its spinal border (from A to A', Fig. 36),
equals three-fourths of the length of the spine.

The clavicle is rudimentary ; it is, however, better de-
veloped in the cat than in the dog. The clavicle of the cat
is represented by a small, elongated bone, curved in out-
line, the convexity being turned forward ; it is united to
the acromion and the sternum by ligamentous fibres ; that
of the dog is merely a scale-like osseous plate situated on
the posterior surface of a muscle of this region (see Figs. 16
and 17).

The humerus is long and twisted in the shape of an S. The
inferior articular surface has the form of a simple pulley,
for the condyle is very slightly marked. The internal part
of this articular surface descends lower than the external ;
this condition resembles that found in the human being,

OSTEOLOGY AND ARTHROLOGY 55

where the inner Hp of the trochlea is lower than the
condyle.

In the dog, the olecranon fossa communicates with the
coronoid by an opening.

In the cat, there is a supra-epitrochlear canal (see Fig. 19),
but no olecranon perforation.

The bones of the forearm articulate at their extremities.
The body of the radius is united to the body of the ulna by
a short, thick, interosseous hgament ; the fibres of this
ligament, though short, do not prevent the production of
some movements at the articulations of the bones.

The radius so crosses the ulna that above, it is in
front and external to the latter, while below, it is internal.
This bone is flattened from front to back, and slightly
convex anteriorly. Its superior extremity is formed,
externally, of a portion which represents the head of the
radius in man ; internally, by another portion which
represents half of the coronoid process of the ulna, which,
in the human being, belongs exclusively to the latter (see
p. 39, the encroachment of the radius on the ulna). This
extremity is surrounded with a vertical articular surface
which is placed in contact with a small cavity which is
hollowed out on the ulna (the lesser sigmoid cavity) ; and
presents at its superior aspect a surface which articulates
with the inferior extremity of the humerus. The shaft of
the bone has on its internal border rugosities analogous to
the imprint of the pronator radii teres of the human skeleton ;
these rugosities, indeed, give insertion to a muscle of the
same function, and bearing the same name. The inferior
extremity, broader than the superior, is hollowed on its
external aspect by a small cavity which receives the in-
ferior extremity of the ulna ; its inferior surface (concave)
articulates with the carpus ; its anterior surface (the homo-
logue of the posterior surface of the corresponding extremity
of the human radius) presents grooves which serve for
the passage of the tendons of the muscles which pass
from the forearm to the back of the hand. (For the
names of the muscles whose tendons pass in these grooves,
see Fig. 29.)

56 THE ARTISTIC ANATOMY OF ANIMALS

The ulna is furnished at its superior extremity with an
olecranon process, which is more prominent than that of
the human ulna ; this process is compressed laterally, and
its internal surface is hollowed ; there we also find a great
sigmoid cavity, and a coronoid process situated at the
internal part of the anterior surface, a process which, as we
have previously shown, it shares with the radius.

The shaft of the bone, prismatic and triangular, diminishes
in thickness as it approaches the lower extremity, which
articulates with the corresponding extremity of the radius.
In the dog, the ulna terminates interiorly in a blunt point,
without enlargement, analogous tc the head of the human
ulna ; in the cat, by a head which is prolonged into a
styloid process, by which it articulates with a portion of
the carpus.

The carpus consists of seven bones — three in the superior
row and four in the inferior. In the superior row the
scaphoid and semilunar bones are fused together. The
pisiform is elongated and expanded at its two extremities ;
it forms a prominence which, directed backwards, projects
beyond the level of the other bones of this region.

The metacarpal bones are five in number ; they are enume-
rated from within outwards ; they articulate with the carpus
and with each other. The inferior extremity of each meta-
carpal bone presents the form of a condyle in front ; and is
divided behind so as to form two lateral condyles, which are
separated by a median crest ; on these posterior condyles
are applied two small sesamoid bones. The metacarpal
bone of the thumb is very short ; the third and fourth are
the longest. The metacarpus, as a whole, is directed verti-
cally.

The phalanges are three in number for each finger, except
the thumb, which has but two. The first phalanx, directed
almost horizontally forwards, is the longest ; the second is
directed downwards and forwards ; the third consists of
two portions : a posterior part, which forms a sort of sheath
into which the base of the nail is received ; and an anterior,
conical in form, and curved in crochet shape, which forms a
support for the nail (Fig. 37).

OSTEOLOGY AND ARTHROLOGY

57

The third and fourth digits are the longest ; the second
and iifth are of equal length ; the thumb is the shortest ;
it does not touch the ground, and does not even reach the
articulation of the metacarpal bone and first phalanx of the
second finger.

In the cat, the metacarpal bone of the thumb, although
shorter than any of the others, is quite as thick. The
third digit is a little longer than either the second or
fourth. In animals of this genus, the claws, in the condi-
tion of repose, are retracted, and removed from the
ground ; this prevents their being worn, and thus pre-

tax.

Fig. ■^j. — Skeleton of the Finger of a Felide (Lion) : Left Side,

Internal Surface.

I, Metacarpus ; 2, sesamoid bones ; 3, first phalanx ; 4, second phalanx ;
5, third phalanx ; 6, gutter for the reception of the base of the nail; ■j ,
prominent osseous crest formed to lodge in the concavity of the nail.

serves their sharpness. At such times the third phalanx
is received into a groove which is found on the external
surface of the second phalanx. In the dog, the claws are
not tractile.

Unguligrades: Pig (Fig. 38). — The scapula is markedly
narrowed in the region above the glenoid cavity. The
spine is atrophied at both its extremities, so that at its
inferior part we do not find the acromion process. In
its middle portion the spine is prominent, and presents a
triangular process which turns backwards, overlapping a
part of the infraspinous fossa ; this latter is much larger

58

THE ARTISTIC ANATOMY OF ANIMALS

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OSTEOLOGY AND ARTHROLOGY 59

than the supraspinous. The spinal border is surmounted
by the cartilage of prolongation, the superior margin of
which is convex ; this cartilage extends posteriorly beyond
the posterior (axillary) border of the bone.

The small tuberosity of the superior extremity of the
humerus is but slightly developed ; the great tuberosity, on
the contrary, is very large. The bicipital groove is situated
internal to this. The deltoid impression is scarcely marked.

The forearm is short, directed obliquely downwards and
inwards, thus forming with the hand an angle, of which the
apex is directed inwards. The two bones of the forearm
are strongly bound to one another by an interosseous liga-
ment, which is formed of very short fibres. The radius
appropriates, at its superior extremity, the coronoid
process of the ulna. The latter is, notwithstanding, well
developed in the rest of its extent ; it has a flattened
shaft which almost completely overlaps the posterior
surface of the radius ; its inferior extremity reaches to the
carpus.

The carpus is formed of eight bones — four in the superior
row, and four in the inferior. The third bone of the
superior row (cuneiform) is more in contact with the ulna
than with the radius.

There are but four metacarpal bones ; there is no meta-
carpal of the thumb. The two median metacarpal bones
are the longest ; they are those which correspond to the
digits which alone touch the ground. The internal digit
and the external one are thin and short ; they are function-
less, as a rule, taking no part in supporting the limbs on
the ground. Notwithstanding this, they are formed, as
the other digits, of a number of phalanges, which give
them the semblance of perfect digits. (We shall soon see
that in certain animals there exist digits which, being in-
complete with regard to the numbers of their constituent
bones, more accurately merit the name of imperfect
digits.)

The third phalanges are each enclosed in a horny hoof,
to which the name of onglon has been given.

We have alreadv drawn attention to the smaller lateral

6o THE ARTISTIC ANATOMY OF ANIMALS

digits, and noted the general fact that they do not come in
contact with the ground. It is necessary to modify this
statement by adding that under certain conditions they
give a sHght amount of support ; for example, when the
individual is the subject of excessive obesity, the limbs
yield under the weight, and the nails of the lateral digits
may touch the ground.

A similar fact may be noticed in pigs of ordinary bulk at
the moment when, during walking, each of the fore-limbs
commences to bear the weight — that is to say, when it is
directed obliquely downwards and forwards ; then all the
digits are in contact with the ground.

Unguligrades (Ungulates) : Sheep, Ox (Fig. 39). — The
scapula, which is of elongated form, is very narrow in the
vicinity of the glenoid cavity. The spine, which becomes
more and more salient towards its inferior part, terminates
abruptly in a border, which, forming an acute angle with the
crest, produces a projection which represents the acromion
process — a very rudimentary acromion, for it does not reach
the level of the glenoid cavity. The supraspinous fossa is
much smaller than the infraspinous ; it hardly equals one-
third the extent of the latter. The anterior border, thin and
convex in its superior portion, is concave in the rest of its
extent ; the posterior border is thick and slightly concave ;
the spinal border is surmounted by the cartilage of pro-
longation. In the ox the spine of the scapula, in its middle
portion, is flexed a little backwards on the infraspinous
fossa.

The great tuberosity of the humerus is highly developed ;
its summit, very prominent, is flexed over the bicipital
groove ; a prominence of the small tuberosity also bends
over the groove, with the result that at this level the latter
is converted into a sort of canal. At the inferior extremity
the condyle, although not large, is recognisable ; for it is
separated from the trochlea by a depression in form of a
groove. In contrast to the condition found in man, the
condyle descends to a level a little below that of the in-
ternal lip of the trochlea. (For the arrangement of the
epicondyle and the epitrochlea, see p. 30.) In the sheep,

OSTEOLOGY AND ARTHROLOGY

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62 THE ARTISTIC ANATOMY OF ANIMALS

the deltoid impression is but slightly marked ; in the ox,
it is more evident.

The forearm is directed obliquely downwards and in-
wards, so as to form, with the hand, an angle of which the
apex is internal ; this angular outline of the knee (wrist) is
so characteristic of ruminants that the corresponding region
of the horse, when salient inwards, receives the name of
ox-knee. The radius bears the coronoid process, and the
larger part of the articular surface which comes in contact
with the inferior extremity of the humerus ; the condyle
and the trochlea articulate with the radius in front ; while
behind, the trochlea articulates with that part of the sig-
moid cavity which belongs to the ulna. The posterior
surface of the shaft of the radius is flattened ; its anterior
surface is slightly convex. The inferior extremity articu-
lates with the carpus by a surface which is directed obliquely
downwards and inwards. The shaft of the ulna is very
slender, and fused in its middle third with the body of the
radius ; it terminates below, at the level of the external
part of the inferior extremity of the radius, by a slightly
expanded portion which, fused with this latter, forms the
articular surface for the carpal bones.

In the ox the forearm is short ; in the sheep it is propor-
tionally longer.

The bones of the carpus are six in number — four in the
upper row, and two in the lower ; they form an irregular
cuboid mass which contributes to the formation of the
region known as the knee in ruminants, as in the horse ; we
have already remarked that the name ' wrist ' would be
more accurate. The anterior surface in its foremost part
is veiticai, and is slightly convex from side to side. At its
posterior and external part the pisiform bone forms a pro-
minence.

The metacarpus consists of two bones only — one, well
developed, which is known as the principal metacarpal, or
the canon bone (this is the name given to the' region in the
hoofed animals) ; and a rudimentary one, which is situated
at the superior and external aspect of the preceding meta-
carpal. Sometimes there is found a third metacarpal

OSTEOLOGY AND ARTHROLOGY 63

at the internal aspect ; but, when present, it is but very
shghtly developed.

The principal metacarpal consists of two metacarpals
fused together ; on this account the bone is longitudinally
marked in the median line by a slight depression which
marks the junction of the two bones of which it is
formed. In some ruminants (certain species of chevrotains)
the coalescence does not take place, and the two meta-
carpals remain separate.

The anterior surface of the principal metacarpal is convex
transversely; its posterior surface is flattened. The superior
extremity of this bone articulates by two facets with the
two bones of the inferior row of the carpus ; on the internal
part of the anterior surface of this extremity is found a
tubercle. The inferior extremity is divided into two parts
by a fissure or notch ; each part is articular, and consists
of two separate condyles, which are separated from each
other by an antero-posterior crest ; on each side of this
crest, and behind, are found two sesamoid bones. As for
the external rudimentary metacarpal bone, it is nothing
more than a small, short tongue of bone ; which, in goats
and sheep, is often absent.

The division of the inferior extremity of the principal
metacarpal into two parts is correlated with the two perfect
digits which give the foot of the ruminant its forked appear-
ance. Each digit consists of three phalanges, which are
directed obliquely downwards and forwards ; further, these
phalanges are inclined a little outwards from the axis of
the limb, so that the two digits diverge from each other as
they descend.

The first phalanx, which is the longest, articulates
superiorly with the principal metacarpal ; its inferior
extremity terminates in a trochlea, and the lip of this,
which is situated towards the axis of the limb, descends
lower than that of the opposite side ; this arrangement is
correlated with the divergent direction of the digits. The
second phalanx has its superior extremity moulded on the
trochlea which terminates the extremity of the first ; its
inferior extremity is articular, and elongated from before

64 THE ARTISTIC ANATOMY OF ANIMALS

backwards. On the posterior surface of this extremity is
found a sesamoid bone.

With regard to the third phalanx, it presents the form
of a triangular p^Tamid, and displays a postero-superior
concave surface with which the second phalanx articulates ;
an anterior, convex surface, which terminates in a point
on its anterior part ; and an internal surface, which is
flattened. The third phalanx of each digit is contained
in a hoof (onglon).

There is also found in ruminants two imperfect rudimen-
tary digits, which are represented by two small bones
situated behind the articulation of the metacarpal and the
digits which we have just been studying. These rudi-
mentary digits are each enveloped in a layer of horn ; they
constitute the spurs. The two digits of the ruminants
represent the third and fourth fingers of the human hand ;
the two lateral digits, greatly atrophied, are the homo-
logues of the second and fifth fingers ; the thumb is not
present.

It is the same as regards the metacarpal bones, which form,
by their union, the principal metacarpal ; the external repre-
sents the fourth metacarpal, and the internal the third. It is
to the latter that the tubercle, of which we have already
made mention, belongs ; and with the signification of which,
because it gives attachment to a muscle, we shall concern
ourselves in the section on myology (see Radial Muscles).

Unguligrades : Horse (Fig. 40). — The scapula is narrow,
compared with that of the animals we have just been con-
sidering. The anterior border is convex in its superior
portion, and concave in its inferior ; the posterior border
is slightly hollowed out. The supraspinous fossa is less in
extent than the infraspinous ; but the difference is less than
that between the same fossae in the ox and the sheep ; in
the ox, as we have already indicated, the proportion is one-
third ; in the horse, one-half. The spine, which disappears
at the extremities, is rough and thick in its middle third,
there forming a kind of tuberosity — tuberosity of the spine.
Above and in front of the glenoid cavity is found a strong
process consisting of a rugous base, and a summit which is

3 4

Fig. 40.— Skeleton of the Horse: Left Lateral Surface.

n Jrr'^^'^^^^'' ^-^^^^l 3. atlas; 4, axis; 5, seventh cervical vertebra; 6, first dorsal vertebra; 7, eighteenth and last dorsal vertebra; 8, lumbar vertebrse ;
nf ptf pn^^„ ' ™'^'^^^! . I*^"^*^ ' II' sternum; 12, xiphoid appendix ; 13, eighteenth and last sternal rib ; 14, costal cartilage ; 15, scapula; 16, cartilage

of extension

A?p"r^ii^,l»fff ^''^^iP ' 36. anterior tuberosity of the tibia ; 37. the fibula; 38, tarsus astragalus ; 39, calcaneum ; 40, principal metatarsal ; 41, rudimentary
external metatarsal ; 42, large sesamoids ; 43, first phalanx ; 44. second phalanx ; 45, third phalanx. ^ f f -* y

To /ace p. 64.

OSTEOLOGY AND ARTHROLOGY 65

directed inwards. This forms a kind of hook curved
towards the inside ; it represents the coracoid. process.
The scapula is surmounted by tlie cartilage of prolonga-
tion, of which the superior border, which is thin and curved,
is parallel to the superior border of the prominence of the
withers ; the cartilage forms, consequently, the lateral
surface of this region. The cartilage of prolongation
undergoes ossification in old horses. The humerus is short ;
the bicipital groove, situated on the anterior surface of the
superior extremity, separates the greater tuberosity from
the lesser, and is divided into two parts by a median ridge ;
it is this portion of the humerus which forms the prominence
known as the fioint of the shoulder, or point of the arm. The
deltoid impression well deserves the name of tuberosity
which has been given to it, for it is very prominent ; the
musculo-spiral groove is very deep.

At the inferior extremity, the trochlea is large ; the
portion corresponding to the condyle of the humerus in
man is, in proportion to the latter, of small extent. The
olecranon fossa is deep. The epicondyle and the epitrochlea
are somewhat different from those of the human bone. In
the latter, the epitrochlea is salient towards the inner side,
causing an increased transverse diameter of the inferior
extremity of the humerus. In the horse — it is the same in
ruminants — this tuberosity projects backwards, folds on itself
in forming the internal boundary of the olecranon cavity,
and exceeds in diameter, in the antero-posterior direction,
the prominence of the epicondyle, which presents a nearly
similar arrangement. This latter has, however, a part
which, projecting externally, is situated at the inferior
part of a crest, that forms the posterior boundary of the
musculo-spiral groove. The result is that, contrary to the
condition found in the human being, the epicondyle is more
prominent transversely than the epitrochlea, but this latter
is more salient on the posterior aspect. The epitrochlea
and the epicondyle offer a larger surface for the origin of
muscles of the forearm than the same prominences in the
human bone do for the analogous muscles of the same
region.

5

66 THE ARTISTIC ANATOMY OF ANIMALS

Some veterinary anatomists have given to the inferior
and external articular surface of the humerus the name of
trochlea ; and to the internal one, that of condyle. On
this account they designate the external prominence as the
epitrochlea, and the internal one as the epicondyle. In
addition to the fact that this point of view is not legitimate,
it produces inevitable confusion when comparing the parts
with those of the human humerus, and this confusion exists,
not alone in describing the bone, but also in the description
of the muscular attachments, and in the comparison of the
muscles of the forearm of quadrupeds with the correspond-
ing muscles in the human species.

The radius is placed in front of the ulna ; its body,
slightly convex forwards, has the anterior surface convex
transversely, and the posterior surface plane in the same
direction. It is to the external part of this latter that the
ulna is applied, which is completely fused with the radius.

The superior extremity of the radius is a little larger than
the inferior. Its superior aspect, concavo-convex, moulded
on the inferior articular surface of the humerus, presents
internally two cavities, which receive the lips of the trochlea,
and, externally, another, smaller, cavity, which receives the
condyle. The radius articulates with the trochlea and the
condyle, having appropriated a portion of the ulna, as is
proved by the presence of the coronoid process, which belongs
to the former. This superior extremity presents, internally,
a tuberosity into which the biceps is inserted ; this is the
bicipital tuberosity ; and on the other side is another tuber-
osity, which is a little more prominent than the preceding.

The inferior extremity, which is flattened from before
backwards, is furrowed on its anterior surface by grooves for
the passage of muscles (the names of the muscles whose
tendons pass in these grooves have already been given on
p. 43). It articulates at the lower end with the superior
row of the carpus, and it terminates laterally in tuberosities :
one, external, on which is found a groove for the tendon of
the lateral extensor of the phalanges, the homologue of the
special extensor of the little finger ; the other, internal, is a
little more prominent than the one we have just described.

OSTEOLOGY AND ARTHROLOGY 67

These tuberosities are visible under the skin which covers
the superior and lateral parts of the region known as the
knee ; but which, we again repeat, is no other than the
wrist.

The ulna has a triangular shaft, situated at the posterior
surface of the radius, with which it is fused. It disappears
completely at the level of the inferior third of the forearm.
Occasionally, in some horses, the ulna is abnormally long,
in the form of a slender tongue of bone ; and extends to the
neighbourhood of the external tuberosity of the inferior
extremity of the radius (see Fig. 79, p. 196). Its superior
extremity is chiefly represented by the olecranon process,
which is voluminous in bulk, and forms the projection known
as the point of the elbow. This process is flattened laterally ;
its internal surface is excavated ; the anterior surface, which
is concave, forms a part of the great sigmoid cavity ; the
remainder of the cavity is formed by the radius.

In the ass, the ulna is a little longer than in the horse —
that is to say, it descends lower ; and the radius is a little
more convex anteriorly.

The carpal bones are seven in number — four in the superior
row, and three in the inferior. The trapezium is wanting in
the latter. Sometimes, however, in certain varieties of horses
the trapezium is developed, but then it is no more than a very
small osseous nodule. The pisiform bone, situated at the
external part of the first row of bone, is prominent pos-
teriorly. It is of rounder form and flattened from without
inwards. It articulates with the trapezium and the radius.
It presents, on its external surface, a groove for the passage of
the tendon of the posterior ulnar muscle, which is named by
veterinary anatomists the external flexor of the metacarpus.

The carpus, as a whole, is of an irregularl}^ cuboid shape ;
its anterior surface, slightly convex from side to side, forms
the skeleton of the region of the knee (wrist). The meta-
carpus is formed of three bones : the principal metacarpal
and the two rudimentary ones.

The principal metacarpal, which forms the region of the
canon, is directed vertically ; its anterior surface is slightly
convex transversely. This surface is covered by a number

5-2

68 THE ARTISTIC ANATOMY OF ANIMALS

of tendons, which shghtly alter its appearance ; so that it is
the principal base of this part of the fore-limb. Its posterior
surface is flattened. The superior extremity of this metacarpal
presents plane surfaces, variously inclined, with which the
bones of the inferior row of the carpus articulate. On the
anterior surface, and a little to the inner side, is found a
tuberosity, which is destined for the insertion of the anterior
extensor of the metacarpus, the hcmologue of the radial
muscles. The inferior extremity is formed by two condyles,
an internal and an external ; between which is found a
median crest.

This extremity, the superior extremity of the first phalanx,
which articulates with it, together with two sesamoid bones
— ^the great sesamoids — which are situated on its posterior
surface, collectively form the region which from its rounded
outlines is called the ball.

With regard to the rudimentary metacarpals, external
and internal, to which some authors give the name of fibulcB,
they are applied to the sides of the posterior surface of the
principal metacarpal. They are elongated bones, of which
the superior extremity, which is a little thickened, is called
the head ; the lateral bones of the second row of the
carpus partly rest on the heads of these. They become
more slender as they descend, and terminate opposite
the inferior fourth of the principal metacarpal. Each ends
in a slight swelling, to which the name button has been
given. The internal one is the better developed.

The rudimentary metacarpals are vestiges of atrophied
digits, as will be explained further on.

The single finger of the horse consists of three phalanges.
The first phalanx, which is directed obliquely downwards
and forwards, corresponds to the constricted region situated
below the ' ball,' and known as the pastern. It is flattened
from before backwards ; its anterior surface is convex trans-
versely, while the posterior surface is plane. Its superior
extremity is moulded on the inferior extremity of the
principal metacarpal, and its inferior extremity, which is
smaller, presents a trochlea with which the second phalanx
articulates. This is also directed downwards and forwards.

OSTEOLOGY AND ARTHROLOGY 69

and is shorter. It corresponds to the region which, situated
between the pastern and the hoof, is known as the cornet.

The third phalanx, situated entirely witliin the hoof,
has the same direction as the first and second. It is
large and broad, and presents three surfaces separated by
well-marked angular borders (see Fig. 96). The anterior
surface is oblique downwards and forwards ; it is convex
transversely. The inferior surface is slightly hollowed,
and is in relation with the sole, or plantar surface of the
hoof.

The superior surface, which is articular, is divided by a
median ridge into two lateral cavities, which correspond to
the trochlea on the inferior surface of the lower extremity
of the second phalanx. The inferior border corresponds
in shape with the hoof. The superior border presents
in its median part a projection, the Pyramidal eminence,
which prolongs at this level the anterior surface of the bone.
Finally, the posterior border, which is concave, is in contact
with a sesamoid bone, the lesser sesamoid, which increases
the superior articular surface behind, and is also in contact
with the second phalanx.

As we have just seen, the horse possesses but one digit.
In the ancestors of the animal — that is, in the prehistoric
species which are now extinct {orohippus, miohippus, proto-
hippus, or hipparion) — the number of digits was larger ; this
fact conclusively proves that the rudimentary metacarpals of
the existing horse are vestiges of digits which have dis-
appeared through want of use. In the first of those ancestors
— orohippus — there were four digits ; all save the first, the
thumb, being then developed. In the others of the series
there existed but three digits. It must, however, be noted
that in those animals it is always the digit which corresponds
to the middle finger of the pentedactyl hand that is longest.
In other less ancient species the lateral fingers are reduced
to the condition of mere splints of bone. It follows from
what has been said that the digit which persists in the equine
species should be considered as the third finger, and that the
rudimentary metacarpals represent lateral digits considerably
atrophied.

70 THE ARTISTIC ANATOMY OF ANIMALS

This disappearance of the lateral digits cannot excite
surprise when we consider the functions of the organs.
Becoming useless, they must undergo gradual atrophy from
want of use.

There undoubtedly is, in this former existence of supple-
mentary digits in the horse, something analogous to what
we still find in the pig ; where the two principal digits are
accompanied by two shorter ones, which very probably,
from their infrequent use, are destined to disappear in a
more or less distant future.

Proportions of the Arm, the Forearm, and the

Metacarpus

As a supplement to the study of the anterior limbs which
we have just finished, it appears necessary to give some
indications of the relative proportions of certain of the
segments which form these limbs in the plantigrades, the
digitigrades, and the ungulates.

First, we would remark that, in following this order of
classification, the scapula becomes less and less narrow,
and assumes a form more and more elongated. In order to
convince ourselves of this, it will be sufficient to study the
bone first in man, then in the bear, the cat, dog, ox, and
finally in the horse.

As to the proportions of length, which are those we
should chiefly study, we shall commence with the
comparison of the forearm and arm — that is to say,
the radius and the humerus. The radius is found to
be longer in proportion to the humerus, as the number
of digits is smaller, and the hand loses more and more the
functions of an organ of prehension. In man, the radius is
shorter than the humerus ; in the horse, on the contrary, it
is longer.

To give an idea of this proportion, we shall employ what
is known as the antibrachial index. This index gives the
relation which exists between the length of the forearm and
that of the humerus ; the length of this latter, whatever
may be the actual measurement, is represented by a fixed

OSTEOLOGY AND ARTHROLOGY 71

figure, the number 100. A very simple arithmetical opera-
tion gives the proportion —

— = , the quotient obtained furnishes the index.

humerus

The index is less than 100 if the forearm is shorter than
the bone of the arm. The index is more than 100 if, on the
contrary, the forearm is longer.

In man, the radius is shorter than the humerus; indeed,
in adult individuals of the white race the average index is 74.

In the bear, the length of the radius approaches closely
to that of the humerus ; tlie index is about 90. In the
skeleton of a bear in the anatomical museum of the Ecole
des Beaux-Arts, the humerus is 33 centimetres in length,
and the radius 30 centimetres.

In the cat, the radius is very little shorter than the
humerus. In the dog they are equal. The antibrachial
index of the latter is, accordingly, 100.

In the horse, the radius is longer than the humerus ; the
index is therefore above 100. Thus, in the skeleton of the
horse which we have in the museum of the Ecole des Beaux
Arts, the index is 113 — length of humerus, 29 centimetres;
length of radius, 33 centimetres. In other skeletons which
we have measured we found : in one, 108 — humerus, 34
centimetres ; radius, 37 centimetres ; in another, 116 —
humerus, 25 centimetres ; radius, 29 centimetres.

The metacarpal bone undergoes, relatively to the humerus,
a proportional elongation, analogous to that of the forearm.

In man, the length of the metacarpus is contained about
5^ times in that of the humerus ; in the bear, it is contained
4 times ; in the dog, 2} times ; in the horse, i^ times only.

It is well known that the proportions vary according to
race, and that what we have here given are but the general
indications.

The Articulations of the Anterior Limbs

The knowledge of human arthrology which we presume
the reader to have previously acquired makes it unnecessary
for us to enter into numerous details regarding the configura-

72. THE ARTISTIC ANATOMY OF ANIMALS

tion of the articular osseous surfaces and the disposition of
the fibrous bands that retain them in position. Accordingly,
in the description which follows, and also in that of the articu-
lations of the posterior limbs, we shall occupy ourselves but
very briefly with the details above referred to, so as to devote
ourselves especially to the indication of the movements —
that is to say, of that which, while easily comprehended
on recollection of former studies, presents the greatest
interest from the artistic standpoint in these studies in
comparative anatomy.

The Scapulo-Humeral Articulation. — The head of the
humerus and the glenoid cavity of the scapula being in
contact, the two bones are bound together by a rather loose
articular capsule, which is strengthened by the muscles of
this region which fulfil the function of active ligaments.

This articulation, so movable in every direction in the
human species, is not so much so in quadrupeds ; the arm in
the latter, as also the shoulder, being kept in contact with
the lateral region of the thorax by the numerous muscles
which surround it.

Of the movements performed by the humerus, flexion and
extension are the most extensive ; those of abduction and
adduction are much less so.

It is necessary, before proceeding further, to determine
what the two principal movements which we have just
mentioned really are, viz., flexion and extension.

We know that in man the displacements of the humerus
which take place in the antero-posterior direction are known
as movement or projection forwards, and movement or pro-
jection backwards, respectively. We do not say that
the humerus is flexed or extended, because, in reality, on
account of the position which the skeleton of the shoulder
occupies, it is not able to flex or place itself on the line of
prolongation of the scapula with which it articulates.

In quadrupeds it is not so. The humerus and the scapula
are contained in almost the same vertical plane ; and the
bone of the arm can take, in relation to the latter, the
positions characteristic of flexion and extension — that is, of
approach to the scapula and removal from it.

OSTEOLOGY AND ARTHROLOGY 73

What makes the meanings of these terms a httle con-
fusmg is that, in human anatomy, some authors consider the
backward movement of the humerus as extension, and the
forward movement as flexion ; in order to be able to
compare these movements to those that the femur executes
in relation to the pelvis.

Now, in our opinion, the indication of this correspondence
is not absolutely necessary ; since it ceases to be exact if
we wished, from the point of view of the direction given to
other segments of the skeleton, to establish the same relation
between the elbow and the articulation of the knee.

It is therefore indispensable, when discussing quadrupeds,
to discontinue these terms, in order the more readily to
recognise that : in flexion the inferior extremity of the
humerus is directed backwards ; in extension, on the con-
trary, it is directed forwards. In the first case the humerus
approaches the scapula ; in the second, on the contrary, it
moves away from it.

These movements, which take place during walking, are
executed in the following manner : When one of the anterior
limbs is at the end of that stage of progression which is called
support (see p. 289, Displacements of the Limbs) — that is to
say, during the time that the foot remains in contact with the
ground, whilst the trunk is moving forward — the direction of
this limb becomes more and more oblique downwards and
backwards. At a certain moment the limb is raised from
the ground, to be carried forwards, in order to be again
pressed on the ground, and recommence a new resting stage.
In these different phases the humerus is flexed. But at
the moment that the limb, when carried forwards, is about
to resume its contact with the ground it becomes directed
obliquely downwards and forwards ; then the humerus is in
the position of extension.

During these movements of the humerus, there exists an
essential factor — that is, the scapular balance. (It is the
same as what occurs in man when he balances his arm in
the antero-posterior plane.) When the humerus is flexed,
the scapula moves in such a way that the superior portion
projects forwards ; when it is extended, the scapula, on the

74

THIi ARTISTIC ANATOMY OF ANIMALS

other hand, is inchned more backwards. But it is necessary
to add that, during these displacements, the scapulo-
humeral angle varies ; it tends to close during the flexion
of the humerus, and becomes more open during extension.

The movements and the relations of the humerus and
the scapula are clearly represented in Figs. 41 and 42,
reproduced from the chromophotographic studies of Professor
Mare}' — studies relative to the analyses of the movements
of the horse.* They show clearly the movements of flexion
and extension of the humerus, also the balancing of the
scapula which accompanies the movements.

Fig. 41. — Flexion of the
Humerus : Right Anterior
Limb of the Horse, External
Surface (after a Chromo-
photographic Study by Pro-
fessor Marey).

Fig. 4.>. — Extension of the
Humerus : Right Anterior
Limb of the Horse, External

SURFACE (after A ChROMO-

photographic Study by Pro-
fessor Marey).

The Articulation of the Elbow, or the Humero-ulnar
Articulation. — In this articulation, which is constructed in
the form of a true hinge, the movements of flexion and ex-
tension alone are possible. In flexion, the forearm, directed
forwards, is folded on the arm, with which, in certain circum-
stances, it comes in contact. For example, in a horse of

* E. J. Marey, ' Analyses of the^Movements of the Horse by the Chromo-
photograph ' {La Natura, June 11, 1898).

OSTEOLOGY AND ARTHROLOGY 75

mettle which leaps over an elevated obstacle, the animal
forcibly raises his fore-limbs by flexing them. Flexion is
produced to the same extent, and even more so, and for a
longer period, in felides which crouch.

In extension, on the contrary, the forearm is carried back-
ward. This movement being limited only by the contact of
the tip of the olecranon with the bottom of the olecranon
fossa of the humerus, the forearm is enabled, in this case, to
move until it is in line with the arm. For example, during
walking, when one of the anterior limbs, having reached the
end of its resting stage, is considerably inclined downwards
and backwards.

The apex of the olecranon process — that is to say, the point
of the elbow — forms a marked prominence, more salient in
flexion than in extension, as in the corresponding region of
the human elbow.

The Radio-ulnar Articulation. — It is in the dog and
the cat, in which the two bones of the forearm articulate by
their extremities only, and remain separate in the rest of
their extent, that the articulations call for special notice.

In the upper part, the radius rotates on itself ; while
below, it rotates around the ulna. It follows that the fore-
arm, which in all quadrupeds is in a state of permanent
pronation, can, in carnivora, take the position of supination,
or rather, of demi-supination. In fact, whatever be the
mobility of the two bones of the forearm, the movement is
not able to bring the palmar surface to the front, but only to
direct it towards the median line.

The Articulation of the Wrist. — Here are found, as in
man, three superimposed articulations : the radio-carpal,
intercarpal, and carpo-metacarpal.

If we remember the movements which take place at the
plane of these articulations in man, and take account of the
fact that the mobility of the limbs is reduced just in proportion
as they are simplified in structure so as to become organs of
support only, we can easily comprehend that, in the horse and
the ox, and, in a word, animals that have a canon bone, the
movements of the wrist are little varied in character, while
in carnivorce, on the other hand, they are relatively more so.

76 THE ARTISTIC ANATOMY OF ANIMALS

We will remember that in the ox and the horse the region
of the wrist is called the knee.

In flexion, the hand is bent backwards ; in extension it
is carried forwards. These two movements take place
especially in the radiocarpal and intercarpal articulations.
In the first of these articulations, it is the superior row of
the carpus which glides backwards and forwards on the
corresponding articular surface of the forearm. In the
second articulation, it is the second row which moves ;
gliding on the inferior articular surfaces of the row above
it. This inferior row carries the metacarpus with it ; for
the carpo-meta carpal articulation is much less mobile than
either of the other two.

In flexion, the articular surfaces are separated from one
another in front ; and the changes of form which result
from this are noticeable on the anterior surface of the
' knee.' Moreover, at that moment this region contrasts
markedly in its outlines with the parts above it and below
it — that is to say, with the corresponding surfaces of the
forearm and of the canon bone.

As for the lateral movements, by which the hand is
inclined outwards and inwards in its movements at the
wrist, they exist to an appreciable extent in the cat and the
dog only ; in order to understand this, it is enough to com-
pare the shape of the articular surfaces of this region in
carnivora and the horse, for example. In the latter, those
surfaces are almost plane ; in the cat, on the contrary, the}/-
are curved (inferior surface of the forearm, concave ; superior
border of the carpus, convex). These latter, then, are, in
form, similar to those which exist at the same level in the
human being ; this explains the possibility of analogous
movements of the whole hand — that is to say, of the mo\-e-
ments of abduction and adduction.

The Metacarpo-phalangeal Articulations. — With regard
to the mobility, it is in these articulations, as in those of the
wrist — that is to say, although in all quadrupeds the first
phalange? can be flexed and extended on the metacarpus,
it is only in the cat and dog that lateral movement is possible.
Indeed, in the horse, in which the principal metacarpal ter-

OSTEOLOGY AND ARTHROLOGY 77

minates inferiorly in two convex surfaces, which are separ-
ated by a crest ; and where the whole articulates with a
cavity on the superior extremity of the first phalanx ;
because of the hinging of these surfaces, there can only
be movements of opening and closing of this articulation.
The first phalanx is directed backwards during flexion
and forwards during extension. In the dog and the cat the
digits can be separated from each other, and also drawn
together — that is to say, abducted and adducted ; but, as
in man, these movements can be made only when the first
phalanges are in the state of extension. During flexion
they are impossible, because of the tension of the lateral
ligaments, which increases as the flexion is more pronounced.
This can be demonstrated, for example, in the cat, which,
in order to separate the digits, opens the hand widely
— that is to say, forcibly raises the first phalanges.

The Interphalangeal Articulations. — The phalanges
are in contact with one another by surfaces, which,
on one side, are of trochlear form, and, on the other, are
moulded on these trochleae ; accordingly, at the level of
these articulations, the movements of flexion and extension
only can take place.

In the felidae, the claws which the third phalanges bear
cannot be utilized when the latter are in a state of extension,
at which time, being forcibly raised, they are, in fact,
placed on the outer sides of the phalanges, which are
grooved to receive them. But when the animal wishes
to use them, it flexes those third phalanges, of which
the terminal extremity is then projected forward, and
the claws are ready to fulfil their function. But at
the same time it extends the first phalanges, to produce
a certain tension of the flexors of the digits, and thus
enable the latter to act with greater efficacy, with a
minimum of contraction. We can demonstrate this action
experimentally on ourselves. It is enough to carry the
first phalanges forcibly into a state of extension ; the
third, phalanges then become flexed, quite spontaneously,
by the tension of the tendons of the flexors which are
inserted into them.

78 THE ARTISTIC ANATOMY OF ANIMALS

At the same time, if we examine the felidae which we have
taken as examples, when the first phalanges are in the state
of extension, the digits will be found to be separable, as we
have already indicated in connection with the metacarpo-
phalangeal articulations, with the result that the claws are
then able to lacerate a wider surface.

The extension of the ungual phalanx, which determines
the retraction of the claw and stops its action, is the
mechanical result of an elastic, fibrous apparatus which is
attached to each of the third phalanges, and has its origin
of the second.

THE POSTERIOR LIMBS*

The posterior limbs are divided, as are the inferior limbs
of the human being, of which they are the homologues, into
four parts : pelvis, thigh, leg, and foot.

The Pelvis

The pelvis, which incompletely limits the abdominal
cavity, inferiorly in the vertical position of the body and
posteriorly in the normal attitude of quadrupeds, is formed
by the iliac bones and sacrum — the coccyx forming a pro-
longation of the latter. We have already described the two
latter (pp. lo and ii) in connection with the vertebral
column, of which they form the inferior or posterior por-
tion or segment, according to the attitude of the individual.

The Iliac Bone. — The iliac or coxal bone, is a paired or non-
symmetrical bone, united below to its fellow of the opposite
side, while it is separated from it above by the sacrum.

In all animals, as well as in man, the iliac bone, at the
beginning of life, consists of three parts, which afterwards
unite and fuse together and join at the middle of the bottom
of a deep cavity which is situated on the outer aspect of the
bone — the cotyloid cavity.

Of those three portions when examined in the human iliac
bone, that above the cavity is the ilium ; that on the inside
is the pubis ; and the last, the lower one, is the ischium. In

* Examine Figs. 21,33, 34, 38. 39- 49-

OSTEOLOGY AND ARTHROLOGY

79

quadrupeds, the iliac bone being, in its entirety, directed
much more obhquely downwards and backwards, the relative
position of these constituent parts is a little modified : the
ilium is in front, the pubis is still internal, but in a more
inferior position, and the ischium is behind the cotyloid
cavity. We notice this peculiarity of the development of
the iliac bone because it is customary to continue to apply to

6 8

Fig. 43. — The Left Iliac
Bone of the Human
Being : External Sur-
face, PLACED IN the POSI-
TION WHICH it would
OCCUPY IN THE SKELETON

OF A Quadruped.

I , Cotyloid cavity ; 2, ilium ;
3, iliac crest ; 4, anterior iliac
crest ; 5, posterior iliac spine ;
6, pubis ; 7, tuberosity of the
ischium; 8, obturator fora-
men ; 9, ischiadic spine.

Fig. 44. — Left Iliac Bone of a
Quadruped (Horse) : External

Surface.

I, Cotyloid cavity; 2, ilium, external
iliac fossa (directed upward in the horse);
3, iliac crest ; 4, anterior iliac spine
(directed inwards in the horse, it is the
angle of the haunch) ; 5, posterior iliac
spine (directed inwards in the horse ; it
is the angle of the haunch); 6, pubis;
7, tuberosity of the ischium ; 8, obtu-
rator foramen ; 9, ischiadic spine, or
subcotyloid foramen.

the osseous regions which correspond to these parts the
names by which they were known when independent bones.

The bones which form the skeleton of the pelvis of quad-
rupeds are proportionally more elongated and less massive
than those of the human pelvis (Figs. 43 and 44).

We find, on the external surface of the iliac bone, the
cotyloid cavity, whose border is interrupted by the cotyloid
notch ; a deep notch which looks downwards.

8o THE ARTISTIC ANATOMY OF ANIMALS

In trout of this cavity is the ihum. This portion, narrow
in the part wliich is next the cavity, is directed forwards and
upwards, expanding more and more as it passes upwards.
It presents an external or superior surface (external in some
animals, superior in others), wliich recalls the external
iliac fossa ; and an internal cr inferior surface, at the superior
part of which is found the auricular surface for articulation
with the sacrum.

The anterior border of the ilium is rough ; this is the iliac
crest, at the extremities of which we find, below or outside,
a prominence which corresponds to the anterior superior
iliac spine of man ; and internally another projection which
corresponds to the posterior iliac spine.

Immediately above the cotyloid cavity is a rough crest,
which is known as the supracotyloid crest, which is, how-
ever, no other than the homologue of the sciatic spine. In
front of this prominence, the border of the ilium, which is
notched, forms the great sciatic notch.

If, still taking the cotyloid cavity as the point of
departure, we proceed inwards — that is, towards the median
line of the body — we find the pubis ; if in a posterior
direction, the ischium. These two portions, pubis and
ischium, limit an oval orifice, the subpubic foramen.

In the human skeleton, the pubis of one side is united
to that of the opposite side, to form the pubic symphysis.
In the animals w^hich we are now studying a portion of the
ischium enters into the formation of the symphysis ; in
other words, it is formed, not only by the body of the pubis,
but also by the descending branch or ramus of the pubis
and a portion of the ascending branch or ramus of the
ischium, which are fused with those of the opposite side. It
results that, thougli in the human being the symphysis
is short and the ischio-pubic arch large, in quadrupeds it
is the opposite. In them the arch is a mere slot, and being
formed by the ischium alone, merits the name of the
ischial arch. The ischio-pubic symphysis is very large, and
forms a horizontal surface relatively extensive, a sort of
floor, on which rest certain organs which occupy the
cavity of the pelvis.

OSTEOLOGY AND ARTHROLOGY

8i

The posterior and external angle of the ischium is rough
and prominent ; it is the tuberosity of the ischium. This
forms a projection under the skin ; it also does in man when
the trunk is strongly inclined forwards, while the thighs are
maintained in the vertical position. In marsupials — opos-
sum, kangaroo, and phalanger — the pelvis at its pubic
region is surmounted by two bones, situated one on each side
of the median line, and arranged in the form of a fork of two
prongs (Fig. 45). These, which are called marsupial hones,
support the pouch which, in animals of this genus, lodges

E^.C,

Fig. 45. — Pubic Region of the Pelvis of a Marsupial (Phalanger,

Fox).

I, Symphysis pubis ; 2, obturator foramen ; 3. marsupial bones.

their young, which, at the time of birth, are incapable of
supporting a separate existence, their development being
absolutely incomplete.

In the cetaceans — for example, the dolphin — because of
the absence of posterior limbs, the pelvis is represented
by two separate bones only, which have no connection with
the vertebral column. In birds, the pelvis is remarkable
for its elongated form (see for its form Fig. 21, and for
details Fig. 46). The cotyloid cavity is pierced by an
opening, and presents on its posterior border, which is

6

82

THE ARTISTIC ANATOMY OF ANIMALS

here a little prominent, a surface with which the great
trochanter is in contact.

The ilium is very highly developed, and is fused in the
median line with the ilium of the opposite side, the last dorsal
vertebrae, the lumbar vertebrae, and the sacrum. Because
of these relations with the dorsal vertebrae, it is in contact
anteriorly with the last ribs, which consequently emerge
from each side of the iliac region of the pelvis.

The ischium forms a plate of bone which, in part, closes
the external portion of the cavity of the pelvis. Its superior

Fig. 46. — Pelvis of a Bird (the Cock) : External Surface, Left Side.

I, Ilium; 2, ischium; 3, pubis; 4, inferior extremity of the pubis;
5, sciatic foramen; 6, oval foramen, homologous to the obturator; 7,
coccygeal vertebrae.

border is separate for a certain distance from the external
border of the ilium ; there is thus left an opening of more
or less considerable size, which represents or takes the place
of the great sciatic notch.

The pubis, long and slender, is in connection with the
inferior border of the ischium, of which it follows the general
direction ; and circumscribes with this latter, below the
cotyloid cavity, an oval orifice, which is the homologue of
the obturator foramen. Its inferior extremity reaches
beyond the corresponding part of the ischium, bending

OSTEOLOGY AND ARTHROLOGY 83

towards the middle line, but without joining the pubis of
the opposite side. On this account there is no symphysis
pubis in birds. Nevertheless, an exception must be noted
in the case of the ostrich, the pubic bones of which meet in
the middle line, and are articulated in form of a symphysis.

The Thigh

A single bone, the femur, forms the skeleton of this
portion of the lower limb.

The Femur. — The bone of the thigh is, in man, directed
downwards and inwards ; this obliquity, we may remind
the reader, is due to the difference in length of the two
condyles which form its inferior extremity ; the internal
is the more prominent, the result of which is that when
the femur is held vertically, the internal condyle descends
lower than the external. Now, as those two articular
expansions rest on the horizontal plane formed by the upper
extremity of the tibia, it follows that the superior part of
the femur inclines towards the side of the shorter con-
dyle— that is to say, outwards — and that, the leg being
vertical, it and the bone of the thigh unite in forming an
angle, of which the apex is directed towards the inner side
of the knee.

In many mammals the two condyles are equally pro-
minent, the result of which is that the femur inclines neither
inwards nor outwards, but is contained in a plane parallel
to the axis of the trunk ; while the leg is included in the
same plane. Nevertheless, although contained in the
plane which we have just indicated, the femur is obliquely
placed, and directed downwards and forwards ; it accord-
ingly forms, with the pelvis, an angle, of which the opening
is directed to the anterior aspect of the body.

In reptiles and in birds the femur and leg are both placed
in the same plane, but this plane is not parallel to the
axis of the trunk. This is the result, on the one hand, of
the thorax being wide, and, on the other hand, of the femur,
which is directed forwards, being in contact by its anterior
extremity with the lateral aspect of the costal region, it is

6—2

84 THE ARTISTIC ANATOMY OF ANIMALS

thus necessarily placed in a direction forwards and outwards,
and the knee is further removed from the axis of the trunk
than is the articulation which unites the thigh with the
pelvis.

The femur, like the humerus, is almost completely en-
veloped by muscular masses, which bind it to the lateral
walls of the abdomen. Its inferior extremity alone is free,
and is always the more so in proportion to its elongation —
that is to say, as it belongs to an animal whose foot is more
divided. The femur in this respect conforms to the law
which we have indicated in cormection with the bone of the
arm, in which the development, as to length, is in propor-
tion to the division of the hand.

If we compare the femur of certain animals with that
of man, we see that the corresponding details of form
are readily recognisable, but they are slightly modified.
Thus, on examining the superior extremity, we find there
a head, a neck, a great trochanter, and a lesser ; but the
neck is usually short and thick, and the great trochanter
does not occupy the same level with regard to the articular
head of the bone. In man, the great trochanter does not
rise to the level of the head of the femur ; in the dog and
the cat it approaches that level ; in the horse and in
ruminants it rises above it.

With regard to the inferior extremity, its surfaces
undergo modifications which are further accentuated as
we pass from the digitigrades to the ungulates, or un-
guligrades. We know that in man the femoral trochlea
is continuous behind, without interruption, with the con-
dyles— that is to say, that each of the condyles is the con-
tinuation of one of the lips of the trochlea. We have just
said that the trochlea is continuous without interruption
with the condyles ; this is accurate. Nevertheless, we
must remark that, at the level of the junction of these
surfaces, the bone presents a slight constriction, which is
more marked on the external than on the internal aspect.
This constriction, which is but slightly marked in man, is
accentuated in the dog and the cat ; in the ruminants and
the solipeds it is still more pronounced so that we may

OSTEOLOGY AND ARTHROLOGY 85

say that in these latter the trochlea and the condyles are
almost completely separated.

There is another modification in regard to the promi-
nence and extent of the two lips of the trochlea. In
man, the external lip of the trochlea reaches higher than the
internal, and it is more prominent in front. In the dog,
these lips are equal with regard to thickness, but the
external still reaches higher than the internal ; in the
cat, they are equal in every respect ; in ruminants and
solipeds the internal lip is wider, thicker, and rises higher
than the external.

In animals the trochlea is, as a general rule, narrower
than in man, and the condyles are more prominent pos-
teriorly ; so that, when viewed from one of the lateral
aspects, the inferior extremity of the femur is, in them,
better developed in the antero-posterior direction.

In birds, the femur is shorter than the bones of the leg ;
its great trochanter is in contact with a prominence which
occupies the posterior part of the border of the cotyloid
cavity. Instead of articulating at the level of the knee,
with the knee-cap and tibia only, as in man, it articulates,
in addition, with the superior extremity of the fibula. A
similar arrangement is found in marsupials and reptiles.

The Knee-cap. — This bone, developed in the thickness of
the tendon of the triceps muscle of the thigh, is in contact,
by its posterior surface, with the femoral trochlea. The
two articular surfaces which are applied to the lips of the
trochlea present, with regard to their extent, an inequality
which is in proportion to the arrangement which we have
above indicated — that is, while in man it is the external
surface which is the larger, in the horse it is the internal.
We shall see what the general form of the knee-cap is
when we come, later on, to study more particularly the
posterior limbs of some animals.

The Leg

The skeleton of the leg consists of two bones : the tibia
and the fibula. The tibia is the more internal and the

86 THE ARTISTIC ANATOMY OF ANIMALS

larger of the two ; the fibula is slender, and situated on the
outer side, and a little posterior to, the preceding. The
fibula is more or less developed according to the species ;
in some it is complete, in others it is very much atrophied.

This peculiarity may be compared with that which we
have drawn attention to regarding the development of the
ulna ; but here the seriation is less distinct. Not only in
the different species, but even in the individuals of the same
species, the development of the fibula presents little regu-
larity. In quadrupeds, the bones of the leg are directed
obliquely downwards and backwards, so that they form,
with the femur, which is directed obliquely downwards
and forwards, an angle, the apex of which is placed at the
anterior surface of the knee.

Tibia. — The tibia of quadrupeds is readily comparable
with that of man ; as in the case of the latter, its shaft has
three surfaces — an external, which is hollowed out in its
upper portion, and becomes anterior below ; an internal,
slightly convex and subcutaneous ; the posterior, which
presents, in its superior part, a crest, the oblique line of the
tibia, and some rugosities. The borders separate the
surfaces. The anterior border, or crest of the tibia, is
prominent in its superior part ; below it gradually dis-
appears in passing towards the internal aspect of the
inferior extremity. The external and internal borders
separate the corresponding surfaces from the posterior one.

The superior extremity is thick, and expands in forming
three tuberosities : two lateral and an anterior. The
anterior tuberosity, situated at the superior part of the
crest of the tibia, is very prominent ; for this reason the
superior extremity is very much expanded in the antero-
posterior direction — hence it results that this diameter is
equal to the transverse, and sometimes even greater. In
man, it is the latter which is the larger. The anterior
tuberosity is visible under the skin.

The inferior extremity, less thick, is prolonged internally
by a prominence which corresponds to the internal mal-
leolus of man. In animals whose fibula is but slightly
developed the tibia presents, on the external part of its

OSTEOLOGY AND ARTHROLOGY ?>7

inferior extremity, a small prominence, which replaces the
fibular malleolus. The ruminants must, however, be ex-
cepted, in which we find in this region a special bone, which
certain authors look on as the inferior part of the fibula
(see p. 97). The inferior surface of this extremity of the
tibia is articular ; and is in contact with one of the tarsal
bones, the astragalus. Because the superior surface of
this latter has the form of a pulley, a pulley much more
marked than that on the human astragalus, the correspond-
ing surface of the tibia, which has the opposite form,
presents two lateral cavities, separated by a median ridge,
which is directed forwards and slightly outwards ; this
ridge projects into the groove of the pulley.

The Fibula. — This bone, situated at the back of the
external surface of the tibia, is, as we have said, more or
less developed. Its superior extremity, or head, articu-
lates with the external tuberosity of the tibia. Its inferior
extremity, when it exists — it is this which disappears in
animals which have the fibula incompletely developed —
forms a prominence which, placed on the external surface
of the inferior extremity of the tibia, articulates with the
astragalus, and recalls the external malleolus of man.

We have stated above that it is the inferior extremity
of the fibula which disappears when the bone is incom-
pletely developed ; it is necessary to except the bat, in
which the fibula, fairly well developed at its inferior
extremity, by which it articulates with the tibia, thins
off in its superior portion, and does not reach the corre-
sponding extremity of the latter. Further, as in this
animal the surface of the knee, which corresponds to the
anterior surface of the same region in other animals, is
turned backwards, the result is that the fibula is situated
on the inner side of the tibia, instead of being placed on
the outer.

The Foot

The foot, in animals, as well as in man, is formed of three
portions, which, as we pass from the part which articulates
with the leg towards the terminal extremity, are: the tarsus,

88 THE ARTISTIC ANATOMY OF ANIMALS

the metatarsus, and the toes. These three portions are the
homologues of the carpus, the metacarpus, and the fingers,
which, as we have already seen in the case of the hand, are
the osseous groups which form its skeleton. The tarsus
is formed of short bones, as the carpus is ; these are, in
man, seven in number. The bones are arranged in two
rows : one, the posterior, formed of two bones superimposed —
the astragalus, by which the tarsus articulates with the leg,
and the calcaneum, which forms the prominence of the heel ;
and an anterior row formed of five juxtaposed ones — the
cuboid, situated externally, and the scaphoid internally, in
front of which are found the three cuneiforms. To the
tarsus succeeds the metatarsus, whose form reminds us very
much of that of the metacarpals.

With regard to the toes, which we enumerate in proceeding
from the most internal to the most external, they are formed
of phalanges, which are three in number for the four outer
toes ; but the number is reduced to two in the case of the
first — that is, the so-called great-toe.

The bones of the tarsus are not seven in all animals ; they
are fewer in ruminants and solipeds. We already know
that, in the latter, the metacarpals and the digits are
equally reduced in number ; the same is the case for the
metatarsals and the toes. We will analyze these differences
w^hen dealing with the species individually.

When we studied the anterior limbs, we saw in passing
from the plantigrades to the digitigrades, and finally the
uugulates, or unguligrades, as the hand became hyperex-
tended, the carpus was raised and more and- more re-
moved from the ground. We shall estabhsh the existence
of the same condition in the posterior limbs ; in the
plantigrades the tarsus rests on the ground ; in the digiti-
grades it is removed from it ; while in the unguligrades the
distance which separates it from the point of support is
still more considerable ; and it is, indeed, necessary to
imagine that if these latter were plantigrades, would
occupy the position on the ground which is indicated by
Fig. 47.

In veterinary anatomy the tarsus is called the ham ; a

OSTEOLOGY AND ARTHROLOGY

89

name we adopt in conformity with usage, but which we
cannot but regret, as in human anatomy the ham is the
region of the posterior surface of the knee.

The general arrangement of the region of the digits of the
posterior hmbs in birds, presents some points of interest.

We shall merely say with regard to the metatarsus, that
it is formed by a single bone, which in the cock is furnished
towards its inferior third with a pointed process, the spur.
At the inferior part, there is, however, found another, which
is but very slightly developed, and with which the first
phalanx of the innermost toe articulates.

The toes are, in the majority of species, four in number :*

Fig. 47. — Posterior Limb of the Horse placed in the Position which

IT SHOULD occupy IF THE AnIMAL WERE A PLANTIGRADE : LeFT LiMB,

External Surface.

I, Tibia; 2, astragalus; 3, calcaneum ; 4, metatarsus ; 5, first phalanx;
6, second phalanx ; j , third phalanx.

an internal, which is directed backwards, and corresponds to
the great - toe ; the others are directed forwards. This
arrangement is constant in grallatores (wading birds), galli-
nacese t (domestic fowls), and raptores (birds of prey).
In climbing birds (parrots, woodpeckers, and toucans), the

* In spite of the fact that the custom is to dssignxte the terminal por-
tions of the foot of birds by the nam 3 of digits, we prefer to employ here
the terms foot and toes. In adopting tliis decision we believe we are
acting according to a more didactic method. Homology of names should,
in our opinion, always accompany homology of regions.

f With regard to the gallinaceae, we must add that in certain varieties
the number of toes is five ; those which are directed forwards are three
in number ; the internal one which passes backward, is double. The two
toes which are the subject of this special arrangement are placed very
close together, and are nearly always superimposed. This condition is
found in the Houdan and Dorking breeds.

90

THE ARTISTIC ANATOMY OF ANIMALS

innermost toe is not only directed backward, but the external
toe accompanies it in that direction ; consequently, there are
two posterior and two anterior toes. Sometimes they are
aU directed forwards ; this disposition is found in the
martins. In some birds, the number of toes is reduced to
three : the cassowary shows this reduction ; in others, the
number is still further diminished — the ostrich, for example,
has but two.

Further, we find that, in general, the number of the
phalanges increases, when we examine the toes in com-

FiG. 48. — Skeleton of the Foot of a Bird (the Cock) : Left Side,

External Surface.

I, Metatarsus ; 2, spur , 3, rudimentary metatarsal ; 4, first toe ;
5, second toe ; 6, third toe ; 7, fourth toe.

mencing with the most internal (Fig. 48) : this has two ;
then the following one three ; that which comes next in
order has four ; and the most external toe has five. The
phalanges of this last are short ; so that, although it is
formed by a larger number of bones, it is not the longest of
the toes.

THE POSTERIOR LIMBS IN SOME ANIMALS.

Plantigrades : Bear (Fig. 33, p. 50). — The external
iliac fossa is very deep. The femur is longer than the
bones of the leg ; the great trochanter does not reach the

OSTEOLOGY AND ARTHROLOGY

91

level of the head of the femur. The fibula is well developed ;
it is united to the tibia at its superior and inferior extremities
only.

The foot, which, as in the case of the hand, rests on the
ground by the whole extent of its plantar surface, presents
five toes ; the shortest of these is the internal — that is, the
toe which corresponds to the great-toe in man ; the third
and fourth are the longest, and they are almost equal ; there
is a very slight difference in favour of the fourth, which is
slightly superior in dimensions to the third.

Digitigrades : Cat, Dog (Fig. 34, p. 52 ). — The ex-
ternal iliac fossa, which looks outwards, is deep ; the iliac

e.:^.c.

Fig. 49. — Pelvis cf the Dog, seen from Above.

X, Iliac crest ; 2, external iliac fossa , 3, sacrum ; AA.', bi-iliac diameter ;

BB', bi-ischial diameter.

crest is convex anteriorly, the convexity is continued from
one iliac spine to the other.

In the dog, the distance which separates the anterior
iliac spines is less than that which separates the ischia
(Fig. 49). On a skeleton which we measured, the transverse
diameter, the distance from the anterior iliac spine of one
side to that of the opposite side, was 8 centimetres, whilst the
distance which separated the ischia was 105 millimetres ;
on another skeleton, the first measurement was 127 metres,
and the second was 146 millimetres. It seems to us unneces-
sary to multiply examples.

In the cat, the iliac spines are but slightly marked ; the

92

THE ARTISTIC ANATOMY OF ANIMALS

result is that the ihac crest is almost confounded with the
inferior and superior borders of the ihum. The two dia-
meters referred to above are almost equal (Fig. 50).

We draw particular attention to what we have just
noted in regard to the transverse proportions of the
iliac and ischiatic regions of the dog and the cat. These
relations are evidently of importance with regard to shape,
since the iliac crests and the ischia are noticeable beneath the
skin.

In the dog, the shaft of the femur is slightly convex in
front ; but in the cat it is straight. The borders of the shaft
are slightly marked, so that it is almost cylindrical. The linea

Fig. 50. — Pei.vis of a Fei.ide (Lion), viewed from Above.

I, Iliac crest'; ?., external iliac fossa; 3, sacrum ; AA', bi-iliac diameter ;

BB', bi-ischial diameter.

aspera, less prominent than in man, gains in width what it
loses in elevation ; it constitutes what may almost be called
a rough surface. This surface is narrower in its middle
portion than at its extremities, where it bifurcates to go
upwards to the two trochanters, and downwards to the two
condyles. At the superior extremity, the neck is short, the
great trochanter reaching almost to the level of the head of
the femur ; the digital cavity, which is situated on the in-
ternal surface of the great trochanter, is very deep. At its
inferior extremity it projects strongly backward. The
trochlea is narrow ; in the cat its two lips are equally pro-
minent, while in the dog the external is a little more elevated

OSTEOLOGY AND ARTHROLOGY 93

than the internal, which on its part is a httle thicker. The
trochlea is still more independent of the condyles than in the
human femur ; it is separated from these latter by a slight
constriction.

The knee-cap is long and narrow.

The tibia of the dog is slightly curved from before back-
ward : it has the form of an elongated S ; this conformation
is in great part due to the very marked projection of the
anterior tuberosity and of the superior portion of the crest,
which, a little below that tuberosity, turns abruptly back-
wards, and thus describes a curve the concavity of which
is directed forward. The superior part of the external
surface is very much hollowed out.

The superior extremity is much thicker than the inferior
one. It is not only wide in the transverse direction, but is
more especially extended from before backwards ; the promi-
nence of the anterior tuberosity is the cause of the elongation
of this antero-posterior diameter. On the posterior part of
the external tuberosity is found a surface to which the
superior extremity of the fibula is applied.

The inferior extremity presents an articular surface, which
is formed of two lateral cavities, separated by a crest, which
is directed obliquely forwards and outwards. The internal
part is prominent, and forms the internal malleolus.

With regard to the fibula, it is united to the tibia by its
extremities and by the inferior half of its shaft. This latter
is more expanded below than in its upper part. The
superior extremity is flattened from without inwards. The
inferior extremity projects beyond the articular surface of the
tibia, and forms the external malleolus, which, instead of, as
in man, descending further than the tibial malleolus, stops
at the same level, and even descends a little less than does
the latter.

In the cat, the curve of the tibia is less pronounced ; this is
due to the fact that the crest, instead of being concave in its
middle portion, is slightly convex anteriorly. The fibula, less
flattened than that of the dog, is united to the tibia by
its extremities only, and is separate in the rest of its extent.

The bones of the tarsus are seven in number, and arranged

94 THE ARTISTIC ANATOMY OF ANIMALS

as in man, with this difference (which is easily comprehended),
that their general relations are changed on account of the
vertical direction of the tarsus. For example, the astragalus,
instead of being above the calcaneum, is situated in front of
it ; the cuneiform bones, instead of being situated in front
of the scaphoid, are found below it, etc.

These animals have but four well-developed metatarsals ;
that which corresponds to the great-toe is represented merely
by a small style-shaped bone, situate at the internal part of
the region.

Nevertheless, we find this toe fully developed in some dogs.
Notwithstanding this, the bones which form it are, however,
but rudimentary, and much smaller than those of the inner-
most digit of the fore-limb.

Sometimes it is double ; this condition is demonstrable
in individuals belonging to breeds of large size. The median
metatarsals are more fully developed than the other bones
of the same region which are next them. Viewed as a whole,
the metatarsal bones are a little longer than the metacarpals ;
the result is that the distance which separates the tarsus
from the ground is a little greater than that which separates
the carpus from the plane on which the anterior limbs rest.
The length of the calcaneum still further exaggerates this
difference, and, as in the animals with which we shall occupy
ourselves later on, the projection which this bone forms is
distinctly higher than that which is produced by the pisi-
form.

The metatarsus, as a whole, is a little narrower than the
metacarpus ; not only on account of the presence of a thumb
in the anterior limb, but, further, because the bones of this
latter region are wider than those of the corresponding part
of the posterior limb.

The phalanges closely resemble those of the anterior
limbs.

Unguligrades : Pig (Fig. 2^, p. 58). — The pelvis in
this animal presents a few of the characters which we
shall again meet with in the ruminants and the solipeds ;
however, the posterior (or internal) iliac spines are relatively
more widely separated from one another than in the latter.

OSTEOLOGY AND ARTHROLOGY

95

This arrangement reminds us of that found in the cami-
vora.

The femur presents nothing very special. The knee-cap
is thick, and ovoid in outhne.

The fibula is completely developed, as in the carnivora ;
and is connected with the tibia at both its extremities.

The tarsus consists of seven bones. The astragalus and
the calcaneum differ slightly from those of ruminants.

The foot, like the hand, has two median digits which rest
on the ground by their third phalanges ; and an internal and

Fig. 51. — Pelvis of the Ox : Superior Surface.

1, Iliac crest : 2, externa! iliac fossa ; 3, sacrum ; AA', bi-iliac diameter ;

BB', bi-ischiadic diameter.

an external digit, which are removed from it. The meta-
tarsals are a little longer than the metacarpals,

Unguligrades : Sheep, Ox (Fig. 39, p. 61). — ^The
pelvis of ruminants of this group closely resembles that of
the horse, which we will study later on (see p. 99). That
which we must at once point out is that, with regard to
the ratio formed by a comparison of the bi-iliac and bi-
ischiatic diameters, it may be placed between the ratio
obtained in comparing those diameters in the pelvis of the
carnivora and that of the solipeds. Indeed, in the rumin-
ants, the distance which separates the ischia exceeds the
width of one iliac only, and does not equal, as in the
fehde, the total width of the anterior part of the pelvis

96 THE ARTISTIC ANATOMY OF ANIMALS

(Fig. 51). In the skeleton of the ox, which forms part of the
anatomical museum of the Ecole des Beaux-Arts, the bi-
ischiadic diameter is 39 centimetres, whilst the width of one
iliac crest is 29 centimetres, so that, in contrast to that which
we find in the dog, the width of the ischiadic region is less
than that formed in front by the addition of the iliac crests.

The great trochanter is large, and extends beyond the level
of the plane in which the head of the femur is found.

In the ox, the linea aspera, instead of being a narrow crest,
is spread out, and forms in reality a surface ; the posterior
surface of the femur. At the inferior and external part of this
surface is situated a cavity which surmounts the corresponding
condyle, and is known as the supracondyloid fossa. On the
internal part of the same region there are a series of tubercles,
which, because of their position in relation to the corre-
sponding condyle, constitute the supracondyloid crest.

The internal lip of the trochlea is much thicker and much
more prominent than the external.

The details which we have just now examined in connec-
tion with the ox are less marked in the sheep.

The trochlea, narrow a,s a whole, is clearly separate from
the condyles by a very marked constriction.

The patella, which is thickened in the antero-posterior
direction, has the shape of a triangular pyramid with the
base upwards. Its posterior surface, which articulates
with the trochlea, presents an arrangement which is adapted
to the disposition of this latter — that is to say, the sur-
face which is in contact with the internal lip is larger
than that which articulates with the lip of the opposite
side.

The tibia of the ox is proportionately shorter than that of
the sheep. The shaft of this bone is flattened from before
backwards, in its inferior half. The median crest of the
articular surface of the inferior extremity is the most pro-
minent part of that region.

The fibula is extremely atrophied. The shaft and superior
extremity of this bone are represented merely by a simple
ligamentous cord, which is sometimes ossified. There re-
mains of the fibula, as a portion well and distinctly developed,

OSTEOLOGY AND ARTHROLOGY

97

the inferior extremity only. This presents itself under
the form of a small bone situated in the region ordinarily
occupied by the inferior extremity of the outer bone of the
leg — that is to say, the external part of the inferior ex-
tremity of the tibia ; this little bone articulates with the

Fig. 52. — Tarsus of the Ox : Posterior Left Limb, Anteko-external

Surface.

I, Tibia; 2, coronoid bone of the tarsus; 3, superior articular surface
of the astragalus ; 4, inferior articular surface of the astragalus ; 5,
calcaneum ; 6, cuboido-scaphoid bone ; 7, great cuneiform bone — the
small cuneiform bone is situated at the back of the latter ; 8, principal
metatarsal — the small, or rudimentary, metatarsal bone is very small ;
it is situated at the back of the preceding, and is not to be seen in the
sketch. It would be visible if the view were directly lateral, but then
the superior and inferior articular surfaces of the astragalus would be less
apparent.

astragalus and the calcaneum. Some authors consider it
to be a tarsal bone, and describe it under the name of the
coronoid bone of the tarsus (Fig. 52, 2). It is not, perhaps,
quite legitimate to describe it as a bone of this region, for

7

98 THE ARTISTIC ANATOMY OF ANIMALS

it has not a homologue in the tarsus of other animals. Its
external surface is rough ; its superior border is furnished
with a small pointed process occupying a depression which
is provided for it by the tibia. It reaches lower down than
the latter, and forms in this way a sort of external malleolus,
which frames, on the outer aspect, the mortise in which the
astragalus is maintained.

The tarsus, as a whole, has an elongated form ; it is formed
of five bones : the astragalus, calcaneum, cuboid and scaphoid,
which coalesce, to form a single bone, and two cuneiform
bones, which correspond to the second and third cuneiform
bones of the human foot. These cuneiforms are called, from
their size, commencing internally, by the names small and
great cuneiform.

The calcaneum is long and narrow ; it is longer than that
of the horse ; it is on the anterior and external part that
the bone (coronoid tarsal bone) which represents the inferior
extremity of the fibula is situated. It forms the prominence
known as the point of the ham, a prominence which is no
other than the heel, which, in the unguligrades, is, as we
have already said, very far removed from the ground.

The astragalus, which is elongated in the vertical direc-
tion, has three articular surfaces disposed in the form of
trochleas : a superior trochlea, which is in contact with the
skeleton of the leg, and which is present in all animals ; an in-
ferior, which replaces the articular head found on the anterior
aspect of the astragalus in man ; this articulates with the
portion of the scaphoido-cuboid that corresponds to the
scaphoid ; and, lastly, a posterior trochlea with which the
-calcaneum articulates. Of these three trochlese, the superior
,is the most strongly marked. Between this latter and the
inferior is found, on the anterior surface of the astragalus,
a deep depression, which, during flexion of the foot on the
leg, receives a prominence which the inferior extremity of
the tibia presents in its median portion.

We can easily recognise the trochleae which we have been
discussing, in the little bones which children use ' to play
at bones ' ; these bones are no other than the astragali of
'.sheep.

OSTEOLOGY AND ARTHROLOGY 99

We have already mentioned that the scaphoid and the
cuboid are ankylosed ; they form by their union an irregular
bone, on which the astragalus and calcaneum are sup-
ported.

The cuneiforms articulate with the internal half of the
superior extremity of the principal metatarsal ; the ex-
ternal half of this metatarsal articulates with the portion of
bone which represents the cuboid.

The metatarsus is represented by a principal metatarsal,
formed by the coalescence of two metatarsals ; we also find
in this region a very small rudimentary metatarsal.

The metatarsus is a little longer than the metacarpus ; its
transverse measurement is a little less ; on the other hand,
it is a little thicker in antero-posterior direction ; from these
two differences it results that the body of the metatarsus
is quadrilateral, whereas the metacarpus presents only an
anterior and a posterior surface.

The rudimentary metatarsal is a very small roundish
bone, situated at the back of the superior extremity of the
principal metatarsal.

The phalanges closely resemble those of the anterior limbs ;
nevertheless, the first and second phalanges differ from the
latter in the fact that they are a little longer and narrower.

At the back of the metatarso-phalangeal articulations, as
in the corresponding region of the anterior limbs, are found
the sesamoid bones. Such also exist at the articulations of
the second and third phalanges.

Unguligrades: Horse (Fig. 40, p. 64). — The pelvis of
the horse presents a general form which sharply differentiates
it from that of the carnivora ; in fact, the ilium is twisted in
such a way that the external iliac fossa does not look outwards,
but upwards. It results from this twist that the anterior
iliac spine, which we have seen to be directed downwards in
the carnivora, has become external ; and this prominence is
much farther removed from the vertebral column than in
the dog or cat. On the other hand, the posterior iliac spine,
which is directed upwards in the carnivora, has become
internal ; it is also placed nearer to the vertebral column,
with the result that the distance which separates this spine

7—2

100 THE ARTISTIC ANATOMY OF ANIMALS

from that of the bone of the opposite side is proportionately
less.

The internal iliac spine, which is conical in shape, and
curved upwards, forms a prominence known as the angle of
the crupper ; the external iliac spine, thick and provided
with tuberosities, forms a clearly-defined prominence ; this is
the angle of the haunch.

The iliac crest, extending directly from one spine to the
other, is curved, its concavity being turned upwards. The
external iliac fossa, which looks upward, is limited anteriorly
by this crest, and is, like the latter, slightly hollowed. The
portion of the bone which connects the ilium to the region
occupied by the cotyloid cavity is extremely narrow ; pos-
teriorly, the bone enlarges again to form the ischial and
pubic portions.

The tuberosity of the ischium, thick and curved upwards,
but less so than in the ox, forms the most prominent part of
the posterior border of the region of the thigh ; this project-
ing portion, so sharply defined in spare subjects, is known
as the point or angle of the buttock. Contrary to what we have
indicated in the case of the dog, the distance which separates
the ischiatic tuberosities is inconsiderable in proportion to
that which we find between the external iliac spine of one
side and that of the opposite. The bi-ischiatic diameter
does not even equal the width of one iliac bone measured
at the level of its crest (Fig. 53). On the skeleton of the
horse in the Ecole des Beaux- Arts, the distance which sepa-
rates the tuberosities of the ischia is 225 millimetres ; that
between the two spines of each iliac bone is 25 centimetres.

The anterior region of the crupper is thus much broader
than that occupied by the ischia.

The femur is relatively short. Its shaft is rectilinear, and
does not present the anterior convexity which is found on
the human femur, and which we indicated when discussing
that of the dog. The shaft of the bone, instead of being
prismatic and triangular, presents four surfaces ; the
anterior, internal, and external, almost pass into each other,
being separated one from the other merely by rounded
and slightly marked borders ; the posterior surface, which

OSTEOLOGY AND ARTHROLOGY

lOI

is plane, replaces the linea aspera, which in the horse, instead
of presenting the appearance of a crest, is considerably
widened. The numerous irregularities which this surface
presents give insertion to the muscles which correspond to
those attached to the linea aspera.

Between this posterior surface and the external is found
a rough prominence which curves forward ; this was desig-
nated by Cuvier the third trochanter ; it replaces the external
branch of the superior line of bifurcation of the linea aspera ;
other authors call it the infratrochanteric crest, because it is
situated below the great trochanter. At the inferior part of
the same region is found a deep fossa, the borders of which
are rough ; this is the supracondyloid fossa.

Fig ^2- — Pelvis of the Horse : Superior Surface.

I, Iliac crest ; 2, external iliac fossa ; 3, sacruni ; A A', bi-iliac diameter ;

BB', bi-ischiatic diameter.

Between the posterior surface and the internal are found :
above, the lesser trochanter, which is long and rough ;
below, at the level of the supracondyloid fossa, an equally
rough surface known by the name of the supracondyloid
crest.

The superior extremity is flattened from before backwards.
The neck is not well marked. The great trochanter is very
prominent, and projects beyond the level of the head of the
femur. We divide the great trochanter into three parts :
the summit, which is the most elevated portion ; the con-

102 THE ARTISTIC ANATOMY OF ANIMALS

vexity, which is situated in front ; and the crest, formed by
muscular impressions, situated outside and below the con-
vexity. The digital fossa is situated behind and below the
summit of the great trochanter. With regard to the lesser
trochanter, it is placed so far down that it really forms
part of the shaft of the bone, with which, besides, we have
described it.

On the inferior extremity of the femur are two condyles
and a trochlea ; the condyles are clearly separated from this
latter by a marked constriction.

The trochlea is directed with a slight obliquity downwards
and inwards ; its internal lip is much thicker and more
prominent than the external ; this is, accordingly, a con-
dition exactly the opposite of that which characterizes the
corresponding region of the human femur.

The knee-cap is lozenge-shaped ; its superior angle pro-
jects upward, and produces a prominence at the part which
corresponds to the base of the human patella, the part
which is here the thickest portion of the bone. Its anterior
surface is convex and rough. Its posterior surface presents
two lateral articular facets, separated by a crest ; this
surface is in contact with the trochlea of the femur, and,
as it is the internal lip of the latter which is the more
developed, it results therefrom that the internal articular
surface of the knee-cap is larger than the external.

The knee-cap contributes to the formation of the region of
the posterior limb which is called the stifle.

The tibia is large in its upper portion ; in its inferior part
it is flattened from before backwards. The posterior surface
of the shaft presents an oblique line, below which are found
vertical rough lines for the insertion of muscles. The ex-
ternal surface is hollowed out in its upper part. The
anterior tuberosity of the tibia rises just to the level of the
flat articular surface ; it is hollowed in its median portion
by a vertical groove of elongated form, which receives the
ligament that binds the knee-cap to the tibia. The external
tuberosit}'' is more prominent than the internal ; in it is
found a groove for the passage of the anterior tibial muscle.
The inferior extremity, flattened from before backwards,

OSTEOLOGY AND ARTHROLOGY 103

presents a surface which is moulded on the trochlea of the
astragalus ; the median crest of this surface is thick, and
descends lower posteriorly than the tuberosities which are
situated on the external and internal aspects of this
extremity.

Of the two tuberosities, that which is internal is com-
parable to the internal malleolus of man, the one on the outer
side forms a sort of external malleolus ; but this latter here
belongs to the tibia, and not to the fibula.

The fibula, in fact, does not reach the inferior extremity
of the tibia ; it is a poorly developed bone, elongated and
terminating interiorly in a point, at the middle of the shaft
of the tibia or at its lower third. Its superior extremity,
which is slightly expanded, articulates with the tuberosity
which occupies the outer aspect of the corresponding ex-
tremity of the tibia.

The bones of the tarsus are six in number : the calcaneum
and astragalus form the upper row ; the cuboid, scaphoid,
and two cuneiforms form the lower (Fig. 54).

The astragalus has not, as in ruminants, an inferior
trochlea for articulation with the scaphoid ; this portion of
the bone presents a surface which is slightly convex. It
articulates with the tibia by a trochlea that occupies not only
the superior surface, but also the anterior. This trochlea,
which is directed slightly obliquely downwards and outwards,
has a very pronounced form ; its lips, which are extremely
prominent, determine by their anterior part one of the
features which we recognise on the anterior aspect of the
ham — a feature which is still more accentuated when the
metatarsus {canon) is extended on the leg. On the internal
surface of the astragalus is found a tubercle, which forms a
projection in the corresponding region of the ham.

The calcaneum, which is not quite so long as that of
the ox, forms by its summit a prominence which is called
the point of the ham.

The cuboid is small ; the scaphoid is large, and flattened
from above downwards. Of the two cuneiforms, the more
external is the larger ; it closely resembles the scaphoid ;
it is flattened from above downwards as is the latter ; but

104 THE ARTISTIC ANATOMY OF ANIMALS

it is a little smaller in size. The small cuneiform, which
occupies the inner side of the tarsus, is the smallest bone in
this region ; it is sometimes divided into two parts ; this
raises the number of the cuneiforms to three, and that of the
bones of the tarsus to seven.

The bones of the metatarsus and the phalanges are equal

Fig. 54.

T\

-Tarsus of the Horse : Left Posterior Limb, Anterior
Surface.

I, Tibia ; 2, internal tuberosity of the inferior extremity of the tibia
(homologue of the internal maHeolus of man); 3, external tuberosity
of the inferior extremity of the tibia (homologue of the external malleolus) ;
4, median crest lodged in the groove of the pulley of the astragalus ; 5,
pulley of the astragalus ; 6, internal tuberosity of the astragalus ; 7,
calcaneum ; 8, cuboid ; 9, scaphoid ; 10, great cuneiform, the small cuneiform
is placed behind this latter; 11, principal metatarsal; 12, external
rudimentary metatarsal. The internal rudimentary metatarsal, being
more slender than the external, does not appear in the figure.

in number to the corresponding bones in the anterior limbs ;
they are formed on a type analogous to that of these latter.
Accordingly, we shall merely indicate the differences which
characterize them.

The principal metatarsal is longer than the metacarpal of

OSTEOLOGY AND ARTHROLOGY 105

the same class ; its shaft is more cyHndrical ; its inferior
extremity is somewhat thicker. The external rudimentary
metatarsal is better developed than the internal ; in the
metacarpus the reverse is the case.

The phalanges so far resemble those of the anterior limb
that, as differential characters, we need point out only the
following : the first phalanx of the hind-foot is a little
shorter than that of the fore-foot ; its inferior extremity
is a little narrower, and its superior extremity a little
thicker. The second phalanx is a little less expanded
laterally.

The difference in appearance which the three phalanges,
anterior and posterior, respectively present are to be borne
in mind ; for they are correlated to the general form of the
fore and hind feet. We will establish this point when we
come to study the hoof (see Figs. loi and 102, p. 257). In
•the fore-foot the ungual phalanx has its inferior surface
limited externally by a circular border, while the same bone
of the hind-foot has this surface a little narrower, more con-
cave, and limited by two curved borders which unite
anteriorly to form an angle — an arrangement which gives to
the general outline of this region the form of the letter V.

Articulation of the Posterior Limbs

The Coxo - femoral Articulation. — The head of the
femur is received in the cotyloid cavity ; these are the osseous
surfaces in contact in this articulation. Thev are main-
tained in position by a fibrous capsule and a round ligament.
To this latter is found attached, in the horse, a fasciculus
which, commencing, as does the round ligament, at the de-
pression on the head of the femur, emerges from the cotyloid
cavity by the notch which is present in its circumference,
and is attached to the anterior border of the pubes, to blend
with the tendon of the rectus muscle of the abdomen. This
is the pubio-femoral ligament.

The movements which this joint permits are the same in
the quadrupeds as in man, but less extensive. They are :
flexion and extension, abduction and adduction, the two

io6 THE ARTISTIC ANATOMY OF ANIMALS

latter being much more limited than the former. There is
also rotation.

By flexion, the inferior extremity of the femur is directed
forwards ; the bone of the thigh then takes a more oblique
direction than the normal. This movement takes place, for
example, when the animal carries forward one of its hinder
limbs. Extension, which takes place in an inverse sense, is
produced when the foot is fixed on the ground, while the
body is projected forward. It is also produced in the
action of kicking.

As for the lateral movements — viz., abduction and ad-
duction— they are less extensive than the preceding move-
ments. The absence of the pubio-femoral ligament in other
quadrupeds than the horse explains why in them abduction
is less limited than in the latter. Indeed, it is the tension of
this ligament, occasioned by the abduction of the thighs,
which arrests more quickly the movement in question.

Articulation of the Knee. — This articulation, as in man,
is formed by the femur, the patella, and the tibia.

In the horse the ligament of the patella is not single, but
consists of three parts, designated, on account of their
position, by the respective names of external, internal, and
median patellar ligaments. The two former come from the
angles on the corresponding borders of the knee-cap ; the
median springs from the anterior surface and inferior angle of
the same bone. They all three pass to their termination on
the anterior tubercle of the tibia. The external ligament
is the strongest, and the internal ligament the least
developed.

In the dog, the cat, the pig, and the sheep, the patellar
ligament consists of a single band. The articulation is
further strengthened on the sides by lateral ligaments — an
internal and an external.

With regard to the principal movements, these are flexion
and extension, to which may be added movements of rotation
of limited extent. In flexion, the leg bends on the thigh ;
its inferior extremity is directed upwards and backwards ;
the angle which the tibia naturally forms with the femur
becomes less obtuse.

OSTEOLOGY AND ARTHROLOGY 107

But it should be understood that one part of this de-
scription—that which has relation to the leg — holds good
only when the femur is in its normal condition, or in flexion.
Indeed, at the close of the movement in which, during a step,
the foot is in contact with the ground — that is, at the termina-
tion of the resting stage — the inferior extremity of the tibia
is directed backwards. But the femur is then in a state of
extension, and in regard to this latter the attitude of the
leg is unchanged.

At this moment, notwithstanding the direction, which

Fig. 55. — Extension of the Leg : Right Posterior Limb of the
Horse, External Surface. (After a Chronographic Study by
Professor Marey.)

recalls that which it has at the time of flexion, the leg is not
bent on the thigh ; on the contrary, it is almost in the line
of its continuation (Fig. 55). As we have done in connec-
tion with the articulations of the anterior limbs, we borrow
this figure from the interesting chronophotographic studies
of Professor Marey.*

The Tibio-tarsal Articulations and of the Bones of the
Tarsus. — In the region which veterinary anatomists call the
ham, the articulations of the leg and foot alone call for special

* E. J. Marey, ' Analysis of the Movements of the Horse by the Chrono-
photograph ' {La Natitra, June ii, 1898).

io8 THE ARTISTIC ANATOMY OF ANIMALS

study in the case of the horse. The articulations of the
bones of the tarsus, and of these with the metatarsus, do not
offer any interest with regard to mobihty, this being almost
wholly absent at that level.

The leg and the astragalus, in a general way, are placed in
contact by such articular surfaces that the resulting joint,
which is a true hinge, permits movements of flexion and ex-
tension only. Indeed, as we have indicated above, the tibia
is furnished, on the inferior surface, with a crest that fits into
the deep groove which is situated on the corresponding
surface of the astragalus.

During flexion, the anterior surface of the foot tends to
approach the anterior surface of the leg, the angle formed
by these two segments becoming more and more narrowed.
The displacement in the opposite direction characterizes
extension.

In other quadrupeds, the articulations which bind together
the bones of the tarsus possess a little more freedom of move-
ment. The shape of these bones, and particularly the shape
of the surfaces of the astragalus, which are in contact with
them, allow movements in this region, in the case of the dog
and cat, which, without being so extensive as those of the
human foot, in the subastragaloid articulation, neverthe-
less, recall the mobility which we find in the human species
at this level — that is to say, rotation, abduction, and
adduction of the foot.

As for the articulations of the metatarsus with the
phalanges, and of the phalanges with one another, they re-
semble those of the anterior limb too closely that it should
be necessary to study them here. Such a study would
be, in this case, but a repetition (see p. 76, a description of the
articulations in question).

THE HEAD IN GENERAL, AND IN SOME
ANIMALS IN PARTICULAR.

When we compare, by the examination of one of their
lateral aspects, the skull of man and the same region in other
mammals, it is easy to observe that the relati\-e develop-
ment of the cranium and face is entirely different. In the

OSTEOLOGY AND ARTHROLOGY

109

case of man the cranium is large, and the face relatively
small ; in animals the face is proportionally much more
highly developed. The measure of the facial angle permits
us to note these differences, and the figures relative to the
value of this angle are sufficiently demonstrative to induce us
to indicate those which are, in a general way, connected with
some of the forms in individuals which here occupy our
attention. In the first place, we must remember that the
angle in question is more acute, as the cranium is less de-
veloped in proportion to the facial region (Figs. 56 and 57). It
is especially to this character that we wish to draw attention.

-80°

Man

Cat

Dog

Sheep

Ox

Ass

Horse

70

28^

-25'

20

l8°-20°
I2°-l6°

II°-I

o

Besides, in animals the cranium is very prominent
superiorly, and the face, more or less elongated, is sharpty
projected downwards and forwards ; in man the cranial region
occupies not only the superior, but also the posterior part ;
the face is short and of a compact form. The human head,
in its general aspect, may be compared to a sphere, while
the skull of the quadrupeds presents the aspect of a quad-
rangular p57ramid, with the base turned upwards and the
summit at the incisor teeth.

Direction of the Head. — Before entering on the study
of the bones of the head, it is necessary, in our opinion, to
agree as to the position in which we shall suppose it to be
placed.

The question may seem to be one of little importance ;
nevertheless, it cannot be regarded as indifferent, since
authors are not all agreed on this subject.

Some suppose it to be placed vertically — that is, with the
incisor teeth turned directly downwards. Others, on the
contrary, suppose it to be placed horizontally, resting on tlie
whole length of the lower jaw, the face being then turned
upwards. These two extreme methods of arrangement appear

no THE ARTISTIC ANATOMY OF ANIMALS

to us to possess inconveniences — at least, lor comparison
with the human head.

Indeed, if, when the head is vertical, the same regions of the

Fig. 56. — Human Skull : Measure of the Facial Angle by the
Method of Camper. Angle BAC = 8o°.

The internal wall of the cranial cavity is marked bj' the dotted line.

c

Fig. 57. — Skull of the Horse : Measure of the Facial Angle by
THE Method of Camper.* Angle BAC = I3°.

The internal wall of the cranial cavity is shown by the dotted line.

face (forehead, nose) are, in the case of animals as well as man,
turned forward, the lower jaw ceases to merit its appellation,
as it is then situated, not below, but behind the upper.

* We have indicated on this sketch of the skull of the horse the facial
angle measured bythe method of Camper, in order that the correspondence
with Fig. 56 mav be more complete. But it is certain that the procedure
here employed is in practice not satisfactory, since the apex of the angle,
as we can demonstrate, is found to be situated within the contour of

OSTEOLOGY AND ARTHROLOGY iii

Furthermore, if this position is chosen, for example, for model-
ling or drawing, it cannot be obtained without difficulty
when we have to deal with an isolated piece of the skeleton,
on account of the absence of equilibrium, which it is necessary
to obviate. It is true that the question of convenience
should not take precedence of all others, and it suffices for
us in this connection to recall, in regard to the human pelvis,
that, although the older anatomists used to represent it as
resting commodiously on the three angles which terminate
it at its lower part (ischial tuberosities and coccyx), this
attitude being false, it is customary now to incline the
superior aspect forwards, inasmuch as this arrangement
more nearly conforms to reality, in spite of the fact that it
is a little more difficult so to dispose an isolated pelvis.
Further, to return to the head ; if its vertical direction can
be demonstrated, for example, in many horses, it is not suffi-
ciently general to be adopted as the classic position.

In regard to the facility of placing in position, the hori-
zontal direction is certainly to be preferred ; but this is also
far removed from the natural position in the animal while in
the state of repose. On the other hand, the mind is not
satisfied with the idea that certain regions of the face,
such as the nose and the forehead, are then directed upwards.
And yet it is necessary to come to a decision, seeing that
what we are now investigating applies also to the position
to which it is necessary to give the preference in placing the
skeleton of the head when we wish to draw it in profile.
That which we adopt is a compromise, but to us it seems
more rational.

The position of the head of the horse, to be normal,

should be such as to give it an inclination of 45°. In this

1 .

the head, and that, consequently, it is rather difficult to localize it precisely
in the case of a given skeleton. Further, because of the absence of the
base of the nose in the complete skull, the auriculo-nasal hne cannot
be accurately fixed. It would be the same for most other animals. This
is why the method employed for these latter is preferably that of Cuvier,
or, again, that of Cloquet. In the former, the apex of the angle of
Camper is transferred to the free border of the upper incisors, but these
teeth may be absent, and, on the other hand, ruminants are destitute of
them. In the second, the same apex is placed at the alveolar border,
and the angle then becomes fairly easy to appreciate.

112 THE ARTISTIC ANATOMY OF ANIMALS

case the lower jaw is still posterior ; and, for this reason, we
see in adopting this position some inconveniences from a
didactic point of view. Accordingly, we will suppose the
head brought a little nearer to the horizontal, and this, from
the imaginative point of view, has certainly an advantage
which we cannot afford to neglect when addressing artists.

Indeed, let us suppose that to a clay model of a human
head we wish to give the aspect of the head of a quadruped.
We should elevate the occiput ; and then, taking hold of the
lower part of the face, we should lengthen it, not in a direction
precisely antero-posterior, but downwards and forwards. It
is obviously this latter procedure which, on the other
hand, is carried out when a person wishes to give to his
own face some resemblance to the muzzle of a quadruped.

It is true that, in the position we have adopted, the face
is directed obliquely downwards and forwards, and that there
may result a certain confusion in describing the position
of its different parts. On this account, with the object
of not making complications, we purpose, for the present,
to substitute, for example, for the term 'antero-superior '
— which when speaking of the position of the forehead and
nose would be more exact — the term ' anterior,' which is
sufficiently comprehensible. The mouth will be, for the
same reason, referred to as being situated at the inferior
part of the face, and not the antero-inferior.

The Skull, — The elevation of the cranial region becomes
especially appreciable when we examine the occipital
bone. Before verifying this fact, it is not superfluous to
recall the general arrangement which this bone presents in
the human skull. A portion of the occipital bone occupies
the base of the skull ; but this base in man is horizontal ; to
this region succeeds the shell-shaped portion of the occipital
bone, which, passing vertically upwards, forms with the
preceding portion an angle situated at the level of the ex-
ternal occipital protuberance, and of the curved line which
starts from it on each side. In animals a portion of the
occipital bone is horizontal, it is true ; but this bone being
sharply bent at the level of the occipital foramen and condyles,
the result is that the portion which surmounts these latter

OSTEOLOGY AND ARTHROLOGY

113

16 7 90

Fig. 58.— Skull of one of the Felid.^ (Jaguar)
I, Posterior surface of the occipital bone

Left Lateral Aspect .

2, external occipital
protuberance ; 3, condyle of the occipital bone ; 4 jugular process ;
5, parietal bone'; 6, frontal bone; 7, orbital process; 8, orbital cavity ;
9, squamous portion of the temporal bone ; 10, external auditory canal,
in front of which is situated the zygomatic process ; 11, tympanic bulla ,
12, superior maxillary bone ; 13, intermaxillary or incisor bone ; 14,
nasal bone; 15, anterior orifice of the nasal cavity; 16, malar bone;
17, ungual or lachrymal bone ; 18, inferior maxillary bone ; 19, condyle
of the inferior maxillary bone ; 20, coronoid process ; 21, incisor teeth ;
22, canine teeth ; 23, molar teeth.

Fig. 59. — Skull of the Lion : Left Lateral Aspect.

This figure is intended to show that in the lion the contour of the face
between the nasal bones and the cranial region is more flattened than
in other fehda?, such as the tiger, jaguar, panther, and domestic cat.
This difference is shown by comparison of this figure with the preceding
one (Fig. 58). We are indebted to M. Tramond, the well-known
naturaUst, for the indication of this differential character which, from
the artistic plastic point of view, is one of real interest.

8

114 THE ARTISTIC ANATOMY OF ANIMALS

looks backwards, and is limited above by the external
occipital protuberance, which forms the culminating
point of the skull ; this point is situated between the
ears.

This protuberjince, prolonged on each side by the superior
curved line of the occipital bone, is so much the more
prominent as this bone bends sharply a second time, so
as to form a third portion, which, looking forwards, forms
part of the anterior aspect of the skull, and proceeds to
articulate with the parietals. On this third portion is
found a crest which, proceeding from the occipital pro-
tuberance, is continuous in front with the parietal crests,
to which we will again refer in speaking of the parietal
bones.

On the inferior surface of the human occipital bone are
found, at the level of, and external to, the condyles two bony
elevations which bear the name of jugular eminences. They
are long in quadrupeds, and constitute what are desig-
nated by some authors the styloid processes, but they must
not be confounded with the processes of the same name
which in the case of man form part of the temporal bone.
These processes are very highly developed in the pig, horse,
ox, and sheep.

In the ox, the occipital bone is deprived of the pro-
tuberance, and is not bent on itself in the anterior portion,
neither does it form the most salient part of the skull ; this
latter, which is situated at the level of the horns, belongs
to the frontal bone. In the pig, also, the occipital bone
is not bent upon itself in its anterior portion, but forms
the summit of the head. The occipital protuberance,
hollowed on its posterior surface, rises vertically, and
rests upon the parietal bone, with which it forms an acute
angle.

The parietals, two separate bones in the dog and the
cat, but fused in the median line in the ox, sheep, and horse,
are of special interest in regard to the two crests which, in
the carnivora, and also in the pig and the horse, occupy
their external surface, and, after diverging from one
another, are continued by a crest which crosses the frontal

OSTEOLOGY AND ARTHROLOGY

115

bone and ends at the external orbital process of the latter
bone.

These crests, known as the parietal or temporal crests,
recall both in position and relations the temporal curved
line of the parietal bone of man. They contribute, as in
the case of the latter, to the formation of the boundaries
of the temporal fossa.

In the carnivora, these crests are situated, throughout their

f^.Cuves^

Fig. 60. — Skull of the Dog : Left Lateral Aspect.

I, Posterior surface of the occipital bone ; 2, external occinital pro-
tuberance ; 3, occipital condyle ; 4, jugular process ; 5, parietal bone ;
6, frontal bone ; 7. orbital process ; 8, orbital cavity ; 9, external auditory
canal, in front of which is found the zygomatic process ; 10, tympanic
bulla ; II, superior maxillary bone ; 12, intermaxillary or incisor bone ;
13, nasal bone ; 14, anterior opening of the cavity of the nasal fossee ;
15, malar bone ; 16, lachrymal bone ; 17, inferior maxillary bone ; 18, con-
dyle of the inferior maxillary bone ; 19, coronoid process ; 20, incisor
teeth ; 21, canine teeth ; 22, molar teeth.

J

whole length, in the median line, the temporal fossae being,
accordingly, as extended as they possibly can be. In certain
species, the development of these crests is such that they
form by their union a vertical plate, which, in separating the
two temporal fossae, gives them a greater depth. In the pig,
the parietal crests, analogous in this respect to the temporal
curved lines of the parietal bones of man, are separated by^

8—2

ii6 THE ARTISTIC ANATOMY OF ANIMALS

an interval, proportionately less extended, however, than
that of the human skull. The parietal bone in the ox and the
sheep does not enter into the formation of the anterior surface
of the skull ; it is formed by an osseous plate, narrow and
elongated transversely, which, with the occipital bone, con-
stitutes the base of the region of the nape of the neck. It is
bent upon itself at the level of its lateral portions so as to
occupy the temporal fossa.

The anterior surface of the frontal bone, which is depressed
in the median line in the dog, but plane in the horse, is
limited by two crests, which, situated on the prolonga-
tion of the parietal crests, diverge more and more from one
another in proportion as they occupy a lower position.
This surface terminates externally in two processes, which
are the homologues of the external orbital processes of the
human frontal bone.

The superior border of these orbital processes, situated
on the prolongation of the corresponding parietal crests,
contributes to limit the temporal fossa. Each of these
orbital processes terminates in the following manner : In the
bear, dog, cat, and pig, in which the orbital cavities are in-
completely bounded by bone, this process, slightly developed,
is not in connection, by its inferior extremity, with an}^ other
part of the skeleton of the region. In the ox and the sheep,
it articulates with a process of the malar bone. In the
horse, it articulates with the zygomatic process of the
temporal bone. The inferior margin of this process forms
a part of the boundary of the anterior opening of the orbital
cavity.

The supra-orbital foramen, which does not exist in carni-
vora, occupies in the horse the base of the orbital process. In
the ox, it is situated a little nearer the middle line ; and its
anterior orifice opens into an osseous gutter which is directed
upwards towards the base of the horn, while inferiorly it
meets the inferior border of the frontal bone ; in the sheep this
groove is but slightly developed. In this latter, as in the ox,
it is the frontal bone which forms the most elevated portion
of the skull. In fact, being bent upon itself at a certain level,
its external surface is formed of two planes : one, posterior,

OSTEOLOGY AND ARTHROLOGY

117

which is indined downwards and directed backwards; the
other, anterior, is also incHned downwards, but with a forward
obhquity. At the union of these planes the bone forms an
elbow, on either side of which are found the osseous pro-
cesses on which the horns are mounted.

Elk.Cuy£\

0 El 17

Fig. 61. — Skull of the Pig : Left Lateral Aspect.

I, Occipital bone ; 2, condyle of the occipital ; 3, jugular process
4, parietal bone ; 5, parietal crests ; 6, frontal bone ; 7, orbital process ;
8, orbital cavity ; q, external auditory canal ; 10, zygomatic process ;
II, superior maxillary bone; 12, intermaxillary or incisor bone; 13,
nasal bone ; 14, anterior orifice of the cavity of the nasal fossae ; 15,
malar bone; 16, lachrymal bone; 17, inferior maxillary bone; 18, con-
dyle of the inferior maxillary bone ; 19, incisor teeth ; 20, canine teeth ;
21, molar teeth.

In the bear, the anterior margin of the frontal bone is
prolonged by two small tongues of bone, which, descending
on the lateral borders of the nasal bones, articulate with the
superior half of the latter.

The temporal bone is, as in man, furnished with a squamous

ii8 THE ARTISTIC ANATOMY OF ANIMALS

portion, from which springs the zygomatic process, which
is directed towards the face, to terminate in the following
manner : in the carnivora, the pig, and ruminants, it
articulates with the malar bone by its inferior border ;
in the horse, it insinuates itself as a sort of wedge between
the malar bone and the orbital process of the frontal bone,
with which it articulates, as we have already pointed out,
and contributes, by a portion situated in front of this
articulation, to form the boundary of the anterior opening
of the corresponding orbital cavity. As in man, the zygo-
matic process arises by two roots : one, transverse, behind
which is situated the glenoid cavity of the temporal bone ;
the other, antero-posterior, which proceeds to join above
with the superior curved line of the occipital bone.

Behind the glenoid cavity is found the external auditory
canal, and, further back still, the mastoid process. This
latter, but slightly developed in the carnivora, a little more
so in the ruminants, and still more in the horse, has its
external surface traversed by a crest, the mastoid crest,
which, after becoming blended with the antero-posterior
root of the zygomatic process, proceeds with this latter to
join the superior occipital curved line.

Below the auditory canal is situated a round prominence,
highly developed in carnivora ; this is the tympanic bulla,
also called the mastoid protuberance ; it is an appendage of
the tympanum.

The Face

The bone of this region, around which all the others come
to be grouped, is, as in man, the superior maxillary. The
relations of this maxillary with the neighbouring bones is
not exactly the same in all animals ; for example, in the ox,
sheep, and horse, in which the bones of the nose are wide in
their upper part, and in which the lachrymal bone, which is
very highly developed, encroaches on the face, the superior
maxillary does not meet the frontal bone ; it is separated
from it by the above-named bones. It unites with it, on the
other hand, in the dog and the cat. In the bear, it is separated
from the bones of the nose by a small tongue of bone which

OSTEOLOGY AND ARTHROLOGY

119

springs from the anterior border of the frontal — a process
which we have noticed in connection with this latter.

In the pig, ox, sheep, and horse, the external surface is
traversed, to a greater or less extent, by a crest which is
situated on the prolongation of the inferior border of the
malar bone. This crest, which is straight in the horse, but
curved with its convexity upwards in the ox and the sheep,
is known as the maxillary spine or the malar tuberosity : it

Fig. 62.

18 15

-The Skull of the Ox

E i . c -> E \

Left Lateral Aspect.

I, Occipital condyle; 2, jugular process; 3, parietal bone; 4, frontal
bone; 5, osseous process, which serves to support the horn (horn-core);
6, orbital cavity; 7, external auditory canal, in front of which is found
the zygomatic process ; 8, temporal fossa ; 9, superior maxillary bone ;
10, intermaxillary or incisor bone; 11, nasal bone; 12, anterior orifice
of the cavity of the nasal fossae ; 13, malar bone ; 14, lachrymal bone;
15, inferior maxillary bone ; 16, condyle of the inferior maxillary bone ;
17, incisor teeth ; 18, molar teeth.

gives attachment to the masseter muscle, and, in the horse,
is distinctly visible under the skin. It does not exist in the
camivora. On the same surface is situated the sub-orbital
foramen.

The inferior border is hollowed out into alveoli, in
which are implanted the superior molar and canine teeth.
This border is prolonged forwards from the alveolus.

120 THE ARTISTIC ANATOMY OF ANIMALS

which corresponds to the first molar tooth, to terminate,
after a course more or less prolonged, at the alveolus
of the canine. This space, more or less considerably ex-
panded, which thus separates these teeth is called the inter-
dental space ; but this denomination is not applicable to
ruminants, because these latter possess neither canine nor
incisor teeth in the upper jaw (see p. 125, dentition of the
ox and sheep). The superior maxillary bone of one side and
that of the opposite side do not meet in the median line in the
region which corresponds to the incisor teeth ; they are sepa-
rated by a bone which, in the human species, is present only
at the commencement of life, and aftersvards coalesces with
the maxilla ; this is the intermaxillary or incisor bone.
This bone, which is paired, is formed of a central part, which
bears the superior incisor teeth ; it is prolonged upwards
and backwards by two processes : one, external, which in-
sinuates itself between the superior m^axillary and the nasal
bone, except in the sheep, in which it remains widely separ-
ated from the latter ; the other, internal, which is united to
that which belongs to the bone of the opposite side to form
part of the floor of the cavity of the nasal fossae ; the external
border of this process, which is separated from the body of the
bone by a notch, forms the internal boundary of the corre-
sponding incisor opening or the incisor slit. Owing to the
absence of superior incisors in ruminants, the intermaxillary
bone presents no alveoli.

The malar bone, and the os unguis or lachrymal, are
more or less developed according to the species considered.
With regard to the malar bone, it is most important to
notice the part which it takes in the form^ation of the
zygomatic arch, and that its inferior border contri-
butes to form the crest to which is attached the masseter
muscle.

As for the nasal bones, they present differential characters
which, as they affect the form of the region which they
occupy, are worthy of notice.

Their dimensions in length are proportional to those of
the face. Very small in man, they are more developed
in carnivora. We recognise in the latter the two curves

OSTEOLOGY AND ARTHROLOGY

121

which characterize them in the human species, and which
we clearly notice when we view them on one of their
lateral aspects : a concavity above, and a convexity below.
These curves are more or less accentuated— very strongly
marked in the bulldog, and scarcely at all in the greyhound.
Moreover, in the carnivora also the nasal bones are wider

IL^.Cu^f \

Fig. 63. — Skull of the Horse : Left Lateral Aspect.

1, Posterior surface of the occipital bone ; 2, external occipital pro-
tuberance ; 3, occipital condyle ; 4, jugular process ; 5, parietal bone ;
6, frontal bone ; 7, orbital cavity ; 8, zygomatic process of the temporal
bone; 9, external auditory canal; 10, mastoid process; 11, superior
maxillary bone or maxilla; 12, intermaxillary or incisor bone; 13, nasal
bone; 14, malar bone: 15. lachrymal bone; 16, inferior maxillary
bone or mandible ; 17, inferior maxillary fissure ; 18, condyle of the inferior
maxillary bone ; 19, coronoid process of the inferior maxillary bone ;
20, incisor teeth ; 21, canine teeth ; 22, molar teeth.

below than above, and form, by their junction, a semi-
circular notch which limits, in its superior portion, the
anterior opening of the cavity of the nasal fossae. In the
horse they present an opposite arrangement with regard to
their dimensions in width ; broad above, each terminates

122 THE ARTISTIC ANATOMY OF ANIMALS

below by forming a pointed process which, separated from the
intermaxillary bones, is prolonged in front of the nasal orifice.

The inferior maxillary bone is, as in man, formed of a
body and two branches. But among the many special
characteristics of form and size which sharply differ-
entiate it from the human bone, one detail must be
indicated ; this is the absence of a mental prominence.
Hence it results that the anterior border of the body of the
lower jaw, instead of being directed obliquely downwards
and forwards, is, on the contrary, oblique downwards
and backwards, and that in certain animals this border is
actually found alm.ost exactly on the prolongation of the
inferior border of the body of the bone.

On the external surface of the body are found the three
mental foramina. The superior border is hollowed out by
alveoli.

With regard to the branches {rami), they terminate in two
processes : one, the posterior, is the condyle ; the other,
situated more forwards, is the coronoid process, which gives
insertion to the temporal muscle. These two processes are
separated by the sigmoid notch.

For reasons which we will explain further on (see p. 127,
movements of the lower jaw), the condyle presents differ-
ences of form. In the carnivora, it is strongly convex from
before backwards, expanded transversely, and firmly mor-
tised in the glenoid cavity of the temporal bone ; in the
ruminants, it is less convex from before backwards, it is
more slightly concave in the transverse direction ; in the
rodents — we give as an example the hare (Fig. 64) — the
condyle is still convex from before backwards, but it is
flattened from without inwards.

In the animals in which the muscles of mastication are
very highly developed, and especially in the carnivora, the
osseous regions occupied by these muscles are more extensive
and more deep than in the human species. The length of
the coronoid process, the depth of the temporal fossa, the
extent of the zygomatic arch, the appearance of the external
surface of each of the rami of the lower jaw, deeply hollowed
out for accommodation of the masseter, and to provide ex-

OSTEOLOGY AND ARTHROLOGY

123

tensive surfaces of insertion for this rnuscle, are sure proofs
furnished by the skeleton of the occasionally enormous de-
velopment of the muscles of mastication.

In the carnivora, a rather strong process, which is directed
backwards, occupies the angle of the inferior maxilla ; it is,
accordingly, situated below the region of the condyle.

The teeth which the jaws carry vary in number, and even
in appearance, according to species ; it is useful to note their
differences. In order to establish the nature of these latter
more effectively, we will first recall the fact that in man the

F.Ji CuyC[\

17 U

Fig. 64. — Skull of the Hare : Left Lateral Aspect.

I External occipital protuberance ; 2, occipital condyle : 3, parietal
bone; 4, frontal bone; 5, orbital process; 6, orbital cavity; 7, zygo-
matic process ; 8, external auditory canal ; 9, superior maxillary bone ;
10, intermaxillary or incisor bone ; 11, nasal bone ; 12, anterior opening
of the nasal fossa; 13, malar bone; 14, inferior maxillary bone; 15,
condyle of the inferior maxillary bone ; 16, incisor teeth ; 17, molar
teeth.

teeth, thirty-two in number, are equally distributed between
the jaws, and are divided into incisors, canines, and molars,
of which the arrangement is thus formulated :

5w.

IC.

2i.

21.

IC.

5m.*

5w.

IC.

21.

2i.

IC.

5m.

32.

* I.e., i, incisors ; c, canines ; m, molars.

124 THE ARTISTIC ANATOMY OF ANIMALS

We also note that the incisors are edged, the canines are
pointed, and that the molars, cubical in shape, have their
surface of contact provided with tubercles.

The teeth of the cat are thirty in number ; they are thus
arranged :

4m. ic. 3». I 3*. ic. 4m.
3w. IC. 3?. I 3i. IC. 3m.

Those of the dog number forty-two :

30.

6m. IC. 3z.

ym. IC. 3^.

3*. IC. . 6m.
3^'. IC. ym.

= 42.

In these animals, the incisors, such as are not damaged by
use, are furnished, on the free border of their crown, with
three tubercles, of which one, the median, is more developed
than those which are situated laterally. We denote these teeth,
commencing with those nearest the median line, by the names
central incisors or nippers, intermediate and corner incisors.
The canines, or fangs, are long and conical; they are curved
backwards and outwards. The upper canines, which are
larger than those of the lower jaw, are separated from the most
external of the incisors {cornier) by an interval in which the
canines of the lower jaw are received. The lower canines, on
the other hand, are in contact with the neighbouring incisors,
and are each separated from the first molar which succeeds
them by a wider interval than that which is situated between
the corresponding teeth in the upper jaw.

The molars differ essentially from the teeth of the same
class in the human species. Their crown terminates in a
cutting border bristling with sharp-pointed projections ; this
formation indicates that these teeth are principally designed
for tearing. During the movement of raising the lower jaw,
which is so energetic in the camivora, they act, indeed, in
the same manner as the two blades of a pair of scissors. The
largest molars are : in the dog, the fourth of the upper jaw,
and the fifth in the opposite one ; in the cat, the third both
above and below.

OSTEOLOGY AND ARTHROLOGY 125

The pig has forty-four teeth disposed in the following
manner :

44.

ym.

IC.

?>i-

3*-

IC.

ym.

ym.

IC.

3^'-

3»-

IC.

ym.

Of the incisors, the nippers and the intermediate ones of the
upper jaw have their analogues in those of the horse ; in the
lower jaw, the corresponding teeth, straight, and directed for-
ward, rather resemble the same incisors in rodents. The
corner incisor teeth are much smaller, and are separated from
the neighbouring teeth. The canine teeth, also called tusks
or tushes, are greatly developed, especially in the male. The
molars increase in size from the first to the last ; they are not
cutting, as in the carnivora, but they are not flattened and
provided with tubercles on their surfaces of contact as in the
herbivora.

In the ox and the sheep the teeth are thirty-two in
number :

6m. oc. o*.
6m. oc. 4*'.

oi. oc. 6m.
4*. oc. 6m.

As we see from this dental formula, the incisors are found
only in the lower jaw ; they are replaced in the upper jaw
by a thick cartilaginous pad on which the inferior incisors
find a surface of resistance.

These have their crowns flattened from above downwards,
and gradually become thinner from the root to the anterior
border, which is edged and slightly convex. These teeth
gradually wear away. In proportion to the progress of this
wear, on account of the fact that it involves the anterior
borders and upper surfaces of the incisor teeth, and that
these teeth are narrower towards the root than at the oppo-
site extremity, the intervals which separate them tend to
become wider and wider ; and when the roots become ex-
posed by the retraction of the gums, they are then separated
from one another by a considerable interval. The molars
have their grinding surface comparable to that of the horse ;
they increase in size from the first to the sixth.

6m.

IC.

3*.

3«'.

IC.

6m.

6m.

ic.

3«.

3«-

IC.

6m.

126 THE ARTISTIC ANATOMY OF ANIMALS

The teeth of the horse are forty in number ; they are
thus distributed :

= 40.

As they become worn, these teeth continue to grow, and as,
on the one hand, this phenomenon takes place throughout
the whole life of the animal, and, on the other hand, the
process of wear brings out and makes visible at the surface
of friction parts formerly deeper and deeper, and of which
the configuration varies at different levels, there result
special features which permit the determination of the age of
the animal by an examination of its jaws. The incisors are
called, commencing with those situated nearest the middle
line, central incisors or nippers, intermediate and corner in-
cisors. The canines, also designated as the fangs, exist only
in the male. It is exceptionalto find them in the mare, and
when they exist in this latter they are less developed than
those of the horse. The molars have cuboid crowns ; the
surface of friction is almost square in the case of the upper
molars, and is inclined so as to look inwards ; in the case of
the inferior ones, it is a little narrowed, and is inclined so
as to look outwards. In the upper jaw the external surface
of the crown is hollowed by two longitudinal furrows ;
in the lower jaw the same surface has only one furrow,
which at times is but slightly marked.

In the hare the teeth are twenty-eight in number :

6m. oc. 2i. I 21. 00. 6m.

. = 28.

5m. oc. li. I li. oc. 5m.

The four incisors of the upper jaw are divided into two
groups ; one of these is formed by the two principal teeth,
the other by two very small incisors which are placed behind
the preceding.

Having studied the jaws and examined the arrangement
of the teeth, we should say a few words on the move-
ments which the lower jaw is able to execute. In
man, these movements are varied in character : the jaw
is lowered and raised ; it can also be projected forwards

OSTEOLOGY AND ARTHROLOGY 127

and drawn backwards, or carried to the right or left side
by lateral movements. Owing to the different modes of
nutrition of animals, with which the shape of the teeth
is clearly correlated, being more specialized than in the
human species, the lower jaw is moved in a fashion less
varied and in the direction most suitable for the mastication
of the foods which form the aliment of the species considered.
Moreover, this is plainly shown in the skeleton by the shape
of the condyle of the lower jaw (see p. 122, different forms of
this condyle). In the carnivora, whose teeth, as we have
seen, are all cutting ones, the jaw rises and falls ; the food
then is, if we consider the two jaws, cut as by the blades
of a pair of scissors. In the ruminants, the incisors exist
only in the lower jaw, but the molars are thick and well
developed ; the food is ground by these latter as by mill-
stones, and the movements which favour this action are,
above all, the lateral. As for the rodents, in which the
incisors are formed for filing down and cutting through hard
resisting bodies, their lower jaw moves in the antero-posterior
direction, in such a way that the inferior incisors alternately
advance and recede beneath those of the upper jaw. The
free cutting border of these teeth effectively fulfils the func-
tion to which they are destined ; their constant wear pre-
serves and revivifies the chisel edge which characterizes
them, without leading to their destruction, for the incisors
in rodents are of continuous growth.

THE SKULL OF BIRDS

The Skull of Birds (Fig. 65). — If, because it is less
important from the artistic point of view, we do not con-
sider it necessary to describe in detail the skull of birds,
we yet think it useful to indicate, in their general lines, the
peculiarities it presents.

In this group the skull is generally pear-shaped ; to the
cranium, of which the bones are arranged in such a way
as to give it a form more or less spherical, succeeds a face
more or less elongated, according as the bill is more or less
developed.

In general, the bones of the skull coalesce very early, with

128 THE ARTISTIC ANATOMY OF ANIMALS

the result that it is only in very young individuals that we
can determine their presence.

We find the skull to consist of an occipital bone, two
parietals, a frontal, etc. ; we will indicate but one detail in
connection with these bones : it is the presence of a single
condyle for the articulation of the occipital bone with the
atlas. We also note the quadrate bone, which is situated on
the lateral part of the cranium, is movable on this latter,
and acts as an intermediary between it, the bones of the face,
and the lower jaw. The quadrate bone is regarded as a
detached portion of the temporal ; on the signification of
this we do not now propose to dwell.

A 3

7 13 8 ^^ Cuyc,^

Fig. 65. — Skull of the Cock : Left Lateral Surface.

I, Occipital bone ; 2, parietal bone ; 3, frontal bone ; 4, ethmoid bone ;
5, cavity of the tympanum ; 6, quadrate bone ; 7, superior maxillary
bone; 8, malar bone; 9, nasal bone; 10, 10, intermaxillary bone; 11,
nasal orifice ; 12, os unguis or lachrymal bone ; 13, inferior maxillary bone.

On the anterior portion of the face we find the nasal bones,
which, articulating with the frontal on one side, circumscribe,
on the other, the posterior border of the nares. The nasal
bone of the one side is separated from that of the opposite by
the intermaxillary or premaxillary bone, which forms the
skeleton of the superior mandible.

The superior maxillaries, which are rudimentary, are
situated on the lateral parts, and prolonged backward by an
osseous style which articulates with the quadrate bone ;
this styloid bone, the homologue of the malar, is designated
by certain authors as the jugal or quadrato-jugal bone.

It is with the quadrate bone also that the inferior
maxillary articulates.

CHAPTER II

MYOLOGY

The first point to decide in commencing this study is the
order in which we shall consider the different muscles which
we have to examine. It must not be forgotten that in the
present work we compare the organization of animals with
that of man, which we already know, and that it is on the
construction of this latter that, in these studies, the thought
must at each instant be carried back in order to establish
this comparison. Now, the general tendency which we
notice in our teaching of anatom\^, when one regards the
region of the trunk in the human figure (a living model or
a figure in the round), is first to consider the anterior aspect.
It is the latter that, for this reason, we study at the very
beginning ; we next deal with the posterior surface of the
trunk, because it is opposite ; lastly, the lateral surfaces,
because they unite with the preceding surfaces, the one to
the other.

In studying an animal, it is usually by one of its lateral
aspects that one first observes it ; it is, in fact, by these
aspects that it presents its greatest dimensions, and that the
morphological characters as a whole can be more readily
appreciated. Hence, possibly, the order of description
adopted in most texts, or in the figures which accompany
them. The first representation of the human figure as a
whole, in a treatise on anatomy, represents the anterior
aspect ; the first view of the horse as a whole, in a treatise
on veterinary anatomy, for example, is, on the other hand,
a lateral view.

129 g

130 THE ARTISTIC ANATOMY OF ANIMALS

We break with this latter custom, and, without taking into
account the tendency above indicated, we will commence
our analysis with the study of the aspect of the trunk,
which corresponds to the anterior aspect of the same region
in man.

The first muscles usually presented for study to artists
being the pectorals, it is their homologues that we will first
describe here. We will afterwards describe the abdominal
region, then the muscles which occupy the dorsal aspect
of the trunk. With regard to the lateral surfaces, they will
be found, by this fact alone, almost completely studied,
since the muscles of the two preceding (back and abdomen),
spreading out, so to speak, over them, contribute to their
formation. Nothing further will remain but to incorporate
with them the muscles of the shoulder ; but these will be
studied in connection with the anterior limbs, from which
they cannot be separated.

The neck, in man, may be considered in an isolated fashion,
because, on account of its narrowness in proportion to the
width of the shoulders, it is clearly differentiated from the
trunk ; for this reason we combine the study of it with
that of the head. In animals, because of the absence or
slight development of the clavicles, the neck is generally
too much confounded with the region of the shoulders to
make it legitimate to separate it from that region in too
marked a fashion. It will, accordingly, be considered next.

We will then undertake the study of the muscles of the
limbs, and end with the myology of the head.

MYOLOGY 131

THE MUSCLES OF THE TRUNK

We shall divide them into muscles of the thorax, of the
abdomen, and of the back.

Muscles of the Thorax

The Pectoralis Major (Fig. 66, i, 2 ; Fig. 67, 3, 4 ;
Fig. 68, 7 ; Fig. 69, 10 ; Fig. 70, 11). — Further designated
by the name of superficial pectoral, this muscle is described
in treatises on veterinary anatomy as formed of two por-
tions : an anterior one, called the sterno-humeral muscle ;
the other, situated below and behind the preceding, bearing
the name of sterno-aponeurotic.

It occupies the region of the breast, and, as a whole, it
takes origin from the median portion of the sternum, from
which it is directed towards the arm and forearm.

The anterior portion (sterno-humeral muscle) — thick,
forming an elevation under the skin, and really constitut-
ing the pectoral region — is directed downwards and outwards
to be inserted into the anterior margin of the humerus
— that is to say, to the ridge which limits in front the spiral
groove of this bone.

The other part (sterno-aponeurotic muscle) is situated
more posteriorly, and corresponds to the region known in
veterinary anatomy as the inter-fore-limb space, which is
limited laterally on each side by the superior portion of
the forearm, of which the point of junction with the trunk
bears the name ars. Arising from the sternum, as we
have above indicated, this portion is directed outwards,
to be joined with the terminal aponeurosis of the sterno-
humeral, and with that which covers the internal surface
of the forearm.

All things considered, the sterno-humeral muscle may be
regarded as the representative of the upper fibres of the
great pectoral of man, of which the attachments, owing to
the more or less complete absence of the clavicle in the
domestic mammals, the fibres must be concentrated on the

9—2

132 THE ARTISTIC ANATOMY OF ANIMALS

sternum ; the sterno-aponeurotic portion then representing
the inferior fasciculae of the same muscle.

The great pectoral muscle of one side is separated from
that of the opposite side along the median line, and especi-
ally above and in front, by a groove which is more or less
deep, according as the muscles are more or less developed.
At the bottom of this groove, suggestive of that which

L^s C

Fig. 66. — Myology of the Horse : Anterior Aspect of the Trunk.

I, Pectoralis major (sterno-humeral) ; 2, pectoraUs major (sterno-
aponeurotic) ; 3, mastoido-humeralis ; .4, point of the shoulder ; 5, sterno-
mastoid or sterno-maxillary : 6, inferior portion of the platysma myoides
of the neck, divided ; 7, triceps cubiti ; 8, brachiahs anticus ; 9, radialis
(anterior extensor of the metacarpus) ; 10, scapular regiop.

exists in the corresponding region in man, is found, as in
this latter, the median portion of the sternum.

The preceding description particularly applies to the
arrangement which the great pectoral presents in the horse ;
in other animals it is marked by some distinctive characters.
In the pig, it is inserted into the sternum as far only as the
level of the third costal cartilage ; in the ox and sheep, it

MYOLOGY 133

extends as far as the sixth ; in the dog, it is attached to the
two first sternal pieces only — that is to say, as far as the
third costal cartilage. Moreover, in the latter, as in the
cat, the two portions which we have indicated are less
readily distinguished.

The great pectoral, by its contraction, draws the
fore-limb towards the middle line — that is to say, ad-
ducts it.

The Pectoralis Minor (Fig. 67, 6 ; Fig. 68, 8 ; Fig. 69,
II ; Fig. 70, 12, 26). — This muscle, also called the deep
pectoral, is, in animals, larger than the superficial pectoral,
therefore certain authors prefer to give to this muscle and
the preceding one the names of deep and superficial pectoral
respectively. This nomenclature is evidently legitimate,
and conforms more to reality, since it does not bring in
the notion of dimensions which here is found in contradic-
tion to nomenclature ; but, in order to establish more
clearly the parallelism with the corresponding muscles in
man, we think it better, nevertheless, to give them the
names by which it has been customary to designate them
in connection with the latter.

We will recall at the outset that the lesser pectoral
muscle in man is completely covered by the great. In
animals this is not the case ; the lesser pectoral being
very highly developed, projects beyond the great pectoral
posteriorly, and occupies to a greater or less extent the
inferior surface of the abdomen.

It also consists of two parts : one anterior, which we
designate by the name of sterno-prescapular ; the other,
posterior, bearing that of stev no-humeral.'^

The sterno-prescapular muscle, being covered by the
sterno-humeral, has little interest for us. It arises from

* This division of the pectorals certainly complicates the nomenclature
of these muscles ; nevertheless, it introduces no insuperable difficulty
from the mnemonic point of view. But where the studj^ becomes less
profitable, and comparison with the corresponding muscles in man
more complicated, is in adopting the nomenclature of Bourgelat.
Indeed, the great pectoral is designated by this author the ' common
muscle of the arm and forearm,' while the lesser pectoral (or deep
pectoral) is called^ the ' great pectoral ' in its sterno - trochinian and

134 THE ARTISTIC ANATOMY OF ANIMALS

the sternum, and is directed towards the angle formed by
the junction of the scapula and humerus ; then it is re-
flected upwards and backwards, to terminate on the
anterior margin of the shoulder by insertion into the
aponeurosis, which covers the supraspinatus muscle.

We can, especially in the horse after removal of the skin,
recognise it, at the level of this region, in the interspace
limited by the superficial muscles (Fig. 70, 26).

In the dog and cat this portion of the muscle does
not exist. The other division of the muscle, the sterno-
trochinian, is more interesting. It arises from the abdo-
minal aponeurosis and the posterior part of the sternum ;
hence it passes forward, turns under the superficial pectoral,
and is inserted into the lesser tuberosity (trochin) of the
humerus.

In the pig, dog, and cat, it is inserted into the greater
tuberosity (trochiter) of the bone of the arm.

The superior border of this muscle is in relation with
a superficial vein, which is distinctly visible in the horse —
the subcutaneous thoracic vein, which in this animal is
called the vein of the spur.

The sterno-humeral muscle, in contracting, draws the
shoulder and the whole anterior limb backwards.

Serratus Magnus (Fig. 67, 2 ; Fig. 69, 8 ; Fig. 70, 9).
— ^This muscle, which is situated on the lateral aspect of
the thorax, is covered to a considerable extent by the
shoulder, the posterior muscular mass of the arm, and by
the great dorsal muscle.

It arises by digitations from the external surface of the
dorsal vertebrae ; from the first eight in the horse, ox, and
dog.

The muscular bundles, converging as they proceed, to-
wards the scapula, pass under this bone, to be inserted
into the superior portion of the subscapular fossa, near

' lesser pectoral ' in its sterno-prescapular portion. We do not consider
it necessary to give the other theories relative to the homologies of these,
notwithstanding the very real interest which they present from the
purely anatomical point of view, as they have but few appUcations in the
study of forms.

MYOLOGY

135

Lh -C.

Fig. 67. — Myology of the Horse : Inferior Aspect of the Trunk.

I, Anterior extremity of the sternum ; 2, point of the shoulder and
inferior portion of the mastoido-humeral muscle ; 3, pectoralis major
(sterno-humeral) ; 4, pectoralis major (sterno-aponeurotic) ; s- point of
the elbow ; 6, pectoralis minor (sterno-trochinian) ; 7, serratus magnus ;
8, external oblique ; 9, sheath of the rectus abdominis ; 10, hnea alba ;
II. the umbilicus; 12, external oblique divided in order to expose the
rectus abdominis ; 13, rectus abdominis.

136 THE ARTISTIC ANATOMY OF ANIMALS

the spinal border. The inferior portion of its posterior
digitations is visible in the ox and in the horse ; these
digitations are less visible in the pig. They are not seen
at all in the dog (Fig. 68) or cat, for in these animals the
great dorsal muscle covers them completely.

The great serratus muscle, by the position which it
occupies and the arrangement that it presents, forms with
the corresponding muscle of the opposite side a sort of
girth, which supports the thorax, and at the same time
helps to fix the scapula against the latter.

When it contracts, in taking its fixed point at the ribs,
it draws the superior portion of the scapula downwards and
backwards in such a way that this bone has its inferior
angle directed forwards and upwards. If it takes its fixed
point at the shoulder, it then acts on the ribs, raises them,
and so becomes a muscle of inspiration.

Because of the connections of the serratus magnus with the
levator anguli scapulae, some authors consider it as united
with the latter. But as the latter muscle is visible only
in the region of the neck (see p. 157), and as it is separately
described in man, we prefer to distinguish them from one
another. We shall recall the connections to which we
have just made allusion when describing the cervical
region.

Muscles of the Abdomen

The abdominal wall is, as in man, formed by four large
muscles : the external oblique, the internal oblique, and
the transversalis, which form the lateral walls, and the
rectus abdominis, situated on each side of the middle
line of the abdomen. This latter, because of the general
direction of the trunk in quadrupeds, has its superficial
surface directed downwards.

The arrangement of these muscles closely corresponds to
that which we find in the human species.

The External Oblique Muscle (Fig. 67, 8, 12 ; Fig. 68, 5 ;
Fig. 6q, 9; Fig. 70, 10). — This muscle arises, by digitations,
from a number of ribs, which varies according to the species,
the number of the ribs being itself variable for each of them,

MYOLOGY 137

as we pointed out in connection with the osteology of the
thorax. Indeed, the great obhque arises from the eight or
nine posterior ribs in the dog and the ox, and from the
thirteen or fourteen posterior in the horse. It is attached,
besides, to the dorso-lumbar aponeurosis.

These attachments are arranged in a hne directed obhquely
upwards and backwards, and the first digitations — that is
to say, the most anterior ones — dovetail with the posterior
digitations of origin of the great serratus muscle.

The fleshy fibres are directed downwards and backwards,
and terminate in an aponeurosis which covers the inferior
aspect of the abdomen, and proceeds to form the linea alba
by joining with that of the muscle of the opposite side,
and also to be inserted into the crural arch.

This aponeurosis of the external oblique is covered by
an expansion of elastic fibrous tissue, which doubles it ex-
ternally, and which is known as the abdominal tunic. This
latter is further developed as the organs of the digestive
apparatus are more voluminous, and their weight, con-
sequently, more considerable. ■ For this reason, in the
large herbivora, as the ox and the horse, this tunic is ex-
tremely thick, whereas in the pig, cat, and dog it is, on the
contrary, reduced to a simple membrane. Indeed, in these
latter, the abdominal viscera being less developed, the
inferior wall of the abdomen does not require so strong a
fibrous apparatus for supporting them. The great oblique,
when it contracts, compresses the abdominal viscera in all
circumstances under which this compression is necessary ;
it also acts as a flexor of the vertebral column.

The Internal Oblique Muscle.- — This muscle, which is
covered by the preceding, arises from the anterior superior
iliac spine (external angle in ruminants and solipeds) and
the neighbouring parts. From this origin its muscular
fibres, the general direction of which is opposite to that of
the fibres of the external oblique, diverging, proceed to
terminate in an aponeurosis, which contributes to the
formation of the linea alba, and to be attached superiorly
to the internal surface of the last costal cartilages. It
has the same action as the great oblique. What it presents

138 THE ARTISTIC ANATOMY OF ANIMALS

of special interest is the detail of form which it determines
in the region of the flank ; this detail is the cord of the flank.
It is characterized by an elongated prominence which,
starting from the iliac spine, is directed obliquely down-
wards and forwards, to terminate near the cartilaginous
border of the false ribs.

Often ver^^ apparent in the ox, and still more so in the
cow, the cord in question contrasts with the depression
which surmounts it ; this depression is situated below the
costiform processes of the lumbar vertebrae, and is called
the hollow of the flank. It is so much the more marked
as the mass of the intestinal viscera is of greater weight.

We sometimes meet with a case of the presence of this
hollow in the horse. But when in the latter, the flank
is well formed, the hollow is scarcely visible, and the cord
but slightly prominent. It is only in emaciated subjects
that these details are found clearly marked.

Transversalis Abdominis. — This muscle being deeply
situated does not present any interest for us. We will,
however, point out, in order to complete the series
of muscles which form the abdominal wall, that the
direction of its iibres is transverse, and that they extend
from the internal surface of the cartila.ges of the false
ribs, and the costiform processes of the lumbar vertebrae
to the linea alba.

The Rectus Abdominis (Fig. 67, 13 ; Fig. 68, 6). —
This muscle, enclosed, as it is in man, in a fibrous sheath
(Fig. 67, 9) formed by the aponeuroses of the lateral
muscles of the abdomen, is a long and wide fleshy band,
which, as in the human species, reaches from the thorax to
the pubis.

What distinguishes it in quadrupeds is that there are
costal attachments which extend further on the sternal
surface of the thorax, and the number of its aponeurotic
insertions, which, in general, is more considerable. These
are, indeed, six or seven in number in the pig and in
ruminants, and about ten in the horse.

It is true that we may find but three in the cat and
dog ; still, we often find as many as six. These intersections

MYOLOGY 139

are not marked on their exterior by transverse grooves,
such as we find in the human species in individuals with
dehcate skin and whose adipose tissue is not very much
developed.

The rectus abdominis is covered, in its anterior portion,
by the sterno-trochinian muscle (posterior segment of the
small pectoral). In contracting, this muscle brings the
chest nearer the pelvis, and as a result flexes the vertebral
column. It also contributes to the compression of the
abdominal viscera.

Pyramidalis Abdominis. — This unimportant little
muscle, which in man is situated at the lower part of tlie
abdomen, extends from the pubis to the linea alba. It is
not present in the domestic animals.

We consider it interesting, however, to point out, although
the fact is not a very useful one as regards external form,
that this muscle is distinctly developed in marsupials.

We know that in the opossum, the kangaroo, and the
phalanger fox, the young are brought forth in an entirely
incomplete state of development, and that, during a certain
period, they are obliged to lodge in a pouch which is placed
at the lower part of the abdomen of the mother. Now,
this pouch contains the mammary glands ; but the young,
being too feeble to exercise the requisite suction, the
pyramidal muscles come to their assistance. These muscles,
in contracting, approximate to one another two bones which
are placed above the pubis, the (so-called) marsupial bones
(see Fig. 80) ; by their approximation the bones in question,
which are placed behind and on the outer side of the
mammary glands, compress the latter, and thus is brought
about the result which the little ones, on account of their
feebleness, would, without that intervention, be incapable
of obtaining for themselves.

140 THE ARTISTIC ANATOMY OF ANIMALS

Muscles of the Back

Trapezius (Fig. 68, i, 2 ; Fig. 6q, i, 2 ; Fig. 70, i, 2). —
This muscle, more or less well developed, according to the
species, is divided into two portions, of which the names
indicate the respective situations — a cervical and a
dorsal.

These two parts, considered in the order in which we find
them, take their origin from the superior cervical ligament
and from the spinous processes of the first dorsal vertebrae.
From these different points the fibres are directed towards
the shoulder ; the anterior are, consequently, oblique
downwards and backwards, and the posterior are directed
downwards and forwards. They are inserted into the
scapula in the following manner : the fibres of the dorsal
portion are attached to the tuberosity of the spine ; those
of the cervical region are also fixed into the same spine,
but into a considerably larger surface.

The cervical portion occupies, in the region of the neck,
an area relatively smaller than the corresponding portion
of the trapezius in man. This diminished degree of de-
velopment results from the absence, complete, or nearly
so, of the clavicle in the animals which we are now con-
sidering. We remember, that the trapezius of man is partly
inserted into the clavicle, and the disappearance of this
latter cannot fail to bring modifications in the general dis-
position of the corresponding portion of the muscle. There
results a disconnection of this latter, and it becomes
united to other muscular fibres to form a muscle with
which we shall soon have to deal — the mastoido-humeral
(seep. 150).

As specific differences we should add that the trapezius
occupies a more or less extensive portion of the median
and superior regions of the neck ; terminating at a con-
siderable distance from the head in the dog and horse, it,
on the contrary, approaches it in the pig and in ruminants.
The cervical portion, when it contracts, draws the scapula
upwards and forwards, the dorsal portion draws it upwards

MYOLOGY

141

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142 THE ARTISTIC ANATOMY OF ANIMALS

and backwards. When tlie trapezius acts as a whole the
scapula is raised.

The Latissimus Dorsi (Fig. 68, 4 ; Fig. 69, 5 ; Fig. 70, 5).
— This muscle arises by an aponeurosis, the so-called dorso-
lumbar aponeurosis, from the spinous processes of the last
dorsal vertebrse (the seven last in the dog, fourteen or
fifteen last in the horse), from the spinous processes of the
lumbar vertebrce, and from the last ribs. Its fleshy fibres
are directed downwards and forwards, being more oblique
in direction posteriorly, and pass on the inner side of the
posterior muscular mass of the arm, to be inserted into
the internal lip of the bicipital groove of the humerus,
or, a little lower down, on the median portion of the
internal surface of the same bone. This latter mode of
insertion is met with in the horse and the ox.

The anterior fibres cover the posterior angle of the scapula
(as in man, where the corresponding angle, but in this case
inferior, is covered by the same muscle), and, a little higher
up, are in their turn concealed by a portion of the dorsal
fibres of the trapezius. It covers, to a greater or less
extent, the great serratus muscle. These relations are
similar to those found in the human species.

We find that the fleshy fibres of the great dorsal are
prolonged more or less backwards if we examine this muscle
in the dog, the ox, the pig, and the horse. Indeed, the fibres
reach to the thirteenth rib in the dog and the cat (that is
to say, the last rib), the eleventh in the ox, tenth in the
pig, and twelfth only in the horse, ^^'e say ' only ' in con-
nection with this last because it is necessary to remember
that the ribs are eighteen in number on each side of the
thorax of this animal, and that, accordingly, the fleshy
fibres of the great dorsal muscle are, relatively, of small
extent.

When this muscle contracts it flexes the humerus upon
the scapula, and helps to draw the whole of the anterior
limb backwards and upwards.

There is a muscular fasciculus which, because of its
relations wdth the muscle we have just been studying, is
known as the supplementary muscle of the latissimus dorsi.

MYOLOGY

143

unyj M .1-- N N

144 THE ARTISTIC ANATOMY OF ANIMALS

But as, on the other hand, this fasciculus is in relation
with the triceps, we shall in preference consider it in relation
witli this latter (see p. 173).

The aponeurosis by which the great dorsal arises from
the vertebral column covers, as in man, the muscles which
occupy the grooves situated on each side of the spinous
processes — the spinal muscles or common muscular mass,
if we regard them as a whole (Fig. 70, 7) ; the sacro-lumbar
and the long dorsal muscles covering the transverse spinal,
if we consider them as distinct.

It would be superfluous to enter here into a detailed
examination of these muscles.

If they are but little developed the spinous processes
become prominent under the skin ; if they are more so they
may by their thickness project beyond the level of these
processes, and these latter thus come to lie in a groove more
or less marked, which, on account of the division which is
determined by its presence, has caused the regions which
it occupies to be designated by the names double hack and
double loins.

The muscles are extensors of the vertebral column.

Under the aponeurosis of the great dorsal muscle there is
found in man another muscle, the serratus posticus inferior,
which, on account of being deeply placed and its slight
thickness, offers nothing of interest in connection with
the study of external form. It arises from the spinous
processes of the three last dorsal vertebrce and those of
the three first lumbar ; it then passes upwards and out-
wards, and divides into four digitations, to be inserted into
the inferior borders of the four last ribs. We repeat that
it is covered by the great dorsal muscle.

In the pig, ox, and horse, which have this latter muscle
less developed in its posterior portion, the same small
serratus muscle, known as the posterior serratus, is visible
in the superficial layer of muscles (Fig. 6g, 6 ; Fig. 70, 6).
The number of its digitations is more or less considerable
according to the species examined.

The Rhomboid Muscle (Fig. 70, 21). — In order to
make intelligible the position of the rhomboid in the super-

MYOLOGY 145

ficial layer in quadrupeds, it appears to us necessary to
recall the anatomical characters of the muscle as found in
man. The rhomboid arises from the inferior portion of the
posterior cervical ligament, from the spinous process of the
seventh cervical vertebrae and the four or five upper dorsal ;
thence passing obliquely downwards and outwards, it is in-
serted into the spinal border of the scapula, into the portion
of this border which is situated below the spine ; it some-
times extends to the middle of the interval which separates
this latter from the superior internal angle of the same
bone.

The portion of the muscle which arises from the cervical
ligament and the seventh cervical vertebra is often separated
from the lower portion by a cellular interspace. For this
cause some anatomists have described the rhomboid as
consisting of two parts — the superior or small rhomboid
and the inferior or large rhomboid, on account of the position
occupied by each, and of their difference in volume.

This muscle can only be seen in the region of the back, in
the space limited externally by the spinal border of the
scapula, below by the latissimus dorsi, and internally by the
trapezius, which covers it in the rest of its extent. It is
not in this space that it is seen in certain quadrupeds. As
we pointed out in the section on osteology, the spinal border
of the scapula is short, and it seems to be due to this
limitation in length that the trapezius and the latissimus dorsi
muscle are, at this level, in contact the one with the other
in such a way that they fill up the interval in which the
rhomboid is seen in man.

In the horse we can partly see it in the superficial muscular
layer, but in the region of the neck only, at the superior
border of the shoulder. Indeed, as we have already pointed
out, the trapezius does not reach the occipital protuberance ;
for this reason a part of the anterior portion of the rhomboid
may be seen — that is, the portion which corresponds to the
superior part of the human muscle.

But whether it be covered by the trapezius, or, as we
find in the cat and dog, by the masioido-hnmeral muscle
(see p. 150), which is very broad in this region, we do not the

10

146 THE ARTISTIC ANATOMY OF ANIMALS

; MYOLOGY 147

less recognise its presence ; and in the horse and ox, in par-
ticular, it forms an elongated prominence beginning at the
level of the scapula, and tapering as it ascends, towards
the posterior part of the head.

Its origins are similar to those which we have already
described in the human rhomboid. It arises from the cer-
vical ligament and the spinous processes of the foremost
dorsal vertebrae ; its fibres converge and pass to the scapula,
to be inserted into its superior or spinal border, or into the
internal surface of the cartilage of prolongation.

It assists in keeping the scapula applied to the thoracic
cage, and when it contracts, draws the scapula upwards
and forwards.

Taking its fixed point at the scapula, it acts on the neck
by its anterior fibres, and extends it.

We shall soon have occasion to mention this muscle again,
in connection with the study of the muscles of the neck.

The Cutaneous Muscle of the Trunk (Fig. 71). —
Immediately beneath the skin which covers the neck,
shoulders, and trunk is found a vast cutaneous muscle,
analogous to that which, in the human species, exists only
in the cervical region.

This thin muscle, whose function is to move the skin
which strongly adheres to it, and in this way to remove
from it material causes of irritation (insects, for example),
is of considerable thickness in the region of the trunk ;
where it constitutes what certain authors have designated
by the name of panniculus carnosus. In this region it extends
from the posterior border of the shoulder to the thigh, and,
in the vertical direction, from the apices of the spinous
process of the dorso-lumbar vertebrae to the median line of
the abdomen.

Arising above from the supraspinous ligament of the dorso-
lumbar and sacral regions (except in the carnivora ; see
below) by an aponeurosis which, posteriorly, covers the
muscles of the hind-limbs, its fibres are directed to the elbow,
on which they are arranged in two layers : a superficial,
which becomes continuous with the panniculus muscle of
the shoulder ; and a deep, which passes on the inner

ID — 2

148 THE ARTISTIC ANATOMY OF ANIMALS

side of the shoulder to be inserted into the internal surface
of the humerus ; this latter exists only in the dog and
cat.

The most inferior fibres, behind, at the level of the
knee-cap form a triangular process which in the horse
receives the name of the stifle fold, from the name
veterinarians give to the region of the articulation of the
knee. This fold of skin, which commences on the antero-
internal surface of this region, is directed upwards, and
then forw^ards, to end by gradually disappearing over the
corresponding part of the abdomen.

In the same animal the muscular fibres of the panniculus
of the trunk arise along a line which connects the stifle-joint
to the withers, a line which is, consequently, oblique up-

FiG. 71. — Myology of the Horse : Panniculus IMuscle of the Trunk.

wards and forwards. Now, as the fleshy layer is thicker
than the aponeurosis, the result is that the mode of con-
stitution of this muscle can be recognised under the skin.
Indeed, we can see in some animals, occasionally very dis-
tinctly, a slight elevation starting from the region of the
abdomen in the neighbourhood of the knee, and thence
directed obliquely upwards and forwards. This elevation
is produced by the fleshy portion of the panniculus.

In the carnivora, the panniculus of the trunk is not
attached to the supraspinous ligament ; it is blended with
the same muscle of the opposite side, passing over the
spinous region of the vertebral column.

From this arrangement results a great mobility of the
skin which covers the back. Further, it explains why it is

MYOLOGY 149

possible to lift up this skin along with the panniculus which
it covers, and to which it adheres, throughout the whole
extent of the dorso-lumbar column. As we pointed out
above, there is also a panniculus muscle of the shoulder
and one of the neck. We will deal with them when treating
of the regions to which those muscles belong.

The Coccygeal Region

As a sequel to the study of the muscles of the region of
the trunk very naturally comes the description 0 f those which,
belonging to the region of the coccyx, are destined for the
movements of the caudal appendix, of which this latter
constitutes the skeleton. The muscles may not seem to
be of much importance with regard to external form, but,
as they form part of the superficial muscular layer, and
as the mass of each is seen in the form of the tail in some
animals (the lion, for example), they merit our attention for
a moment. A few lines will suffice to give an idea of them.
They are : the ischio-coccygeal, superior sacro-coccygeal, lateral
sacro-coccygeal, and inferior sacro-coccygeal.

The Ischio-coccygeal (Fig. 18, 38 ; Fig. 69, 33 ; Fig. 70, 42).
— ^This muscle, triangular in shape, better developed in the
carnivora than in the horse, arises from the spine of the
ischium, or from the supracotyloid crest, which replaces
this latter in the solipeds and the ruminants. Thence its
fleshy mass is directed upwards, expanding as it proceeds to
be inserted into the transverse processes of the first two
coccygeal vertebrae after insinuating itself between two of the
following muscles, the lateral and inferior sacro-coccygeal.

In the dog and cat, the muscle is in great part covered by
the great gluteal. In the ox, by a peculiar arrangement of
the corresponding region of the muscles of the thigh — an
arrangement which we will examine in connection with the
study of the latter — it is more exposed than in the horse,
and gives origin to an outline which corresponds to its general
form in the region situated immediately below the root of
the tail.

It is a depressor of the whole caudal appendix.

150 THE ARTISTIC ANATOMY OF ANIMALS

The Superior Sacro-coccygeal (Fig. 68, 39 ; Fig. 69, 34 ;
Fig. 70, 43). — The fascicuH which form this rnuscle
arise from the crest of the sacrum, and proceed thence to
end successively on the coccygeal vertebrae. It is in con-
tact in the middle line with the corresponding muscle of the
opposite side.

It raises the tail and inclines it laterally ; if the muscle
of one side contracts at the same time as that of the other
the tail is elevated directly.

The Lateral Sacro-coccygeal (Fig. 68, 40 ; Fig. 69, 35 ;
Fig. 70, 44). — Situated on the lateral part of the caudal
region, this muscle arises, in the dog, from the internal border
of the iliac bone and the external border of the sacrum ; in
the horse, it arises from the crest of the sacrum. It is in-
serted into the coccygeal vertebrce.

It produces lateral movement of the tail.

The Inferior Sacro-coccygeal ( Fig. 68, 41 ; Fig. 69, 36 ;
Fig. 70, 43). — This muscle, which is fairly thick, arises from
the inferior surface of the sacrum and the corresponding
surface of the sacro-sciatic ligament ; it is inserted into
the coccygeal vertebrae.

It depresses the caudal appendix.

Muscles of the Neck

Mastoido - humeralis (Fig. 66, 3 ; Fig. 68, 9, 9, 10 ;
Fig. 69, 12 ; Fig. 70, 15). — One of the most important
muscles of the region of the neck in man is the sterno-cleido
mastoid. We recollect that, in its inferior part, it is divided
into two bundles, one of which arises from the manubrium
of the sternum, and the other from the inner third of the
clavicle, whence the denominations of the sternal portion
and clavicular portion. The muscle formed by the union
of these two portions is then directed obliquely outwards,
backwards, and upwards, to be inserted into the mastoid
process of the temporal bone and the two external thirds of
the superior curved line of the occipital bone.

Now, the animals which we are here considering have but
a rudimentary clavicle or are entirely without it. From

MYOLOGY 151

the absence of this item of the skeleton there necessarily
result modifications in the arrangement of the muscles of
this region, which we must at the very outset explain, before
undertaking the special study of the muscle which is the
subject of the present paragraph.

Let us suppose, for the more definite arrangement of our
ideas, that the clavicle is altogether absent, although we
do find it in a rudimentary state in some animals and
completely developed in others (marmot, bat), and we will
proceed to indicate what this absence determines.

The great pectoral muscle in man arises in part from the
clavicle ; this origin not being possible in animals which have
no clavicle, its attachments, as we have already seen, are
concentrated on the sternum. The trapezius in man similarly
arises in part from the clavicle ; for the reasons above indi-
cated its clavicular fasciculi cannot exist in distinct form in
the animals which have no clavicle.

. The sterno-clcido mastoid, whose inferior attachments we
mentioned above, cannot have a clavicular portion.

It is the same in the case of the deltoid, which, we know,
arises in part from the anterior bone of the shoulder.

Of the four muscles which have partial clavicular origins
in man, two are known to us in connection with animals —
the great pectoral and the trapezius. What has become
of the other two, the sterno-cleido mastoid and the
deltoid ?

It is this which we now proceed to investigate. After a
fashion simple enough, but which it is necessary to describe,
the clavicular fasciculi of the trapezius and the corresponding
fasciculi of the sterno-cleido mastoid are united the one
to the other ; the portion of the deltoid which in man
arises from the clavicle, by reason of the absence of this
latter, is also combined with the fleshy mass formed by
the preceding muscles. From this fusion results the
muscle known as the mastoido-humeral. This muscle,
which consists of a long fleshy band situated on the
lateral aspect of the neck, takes its origin, as a general
rule, from the posterior surface of the skull and the upper
part of the neck, from which it passes obliquely downwards

152 THE ARTISTIC ANATOMY OF ANIMALS

and backwards, covering the scapulo-humeral angle — that is,
the region known as the point of the shoulder or arm — and
is inserted into the anterior border of the humerus, the
border which, limiting anteriorly the musculo-spiral groove,
forms a continuation of the deltoid impression. On account
of the regions with which it is related, Bourgelat named this
muscle the muscle common to the head, neck, and arm.

It is at the level of the scapulo-humeral angle that the
vestiges of the clavicle are found.

This bone is represented in some animals — the pig, ox,
and horse — by a single tendinous intersection, more or less
apparent, which extends transversely from the scapula to
the anterior extremity of the sternum. In the dog and the
cat, we find, besides, on the deep surface of the muscle and
at the level of this tendinous intersection, the rudiment of
the clavicle of which we made mention in the section on
Osteology (see p. 25).

It is beneath the intersection, the existence of which we
have just pointed out, that is found that portion of the
mastoido-humeral muscle which corresponds to the clavicular
fasciculi of the deltoid ; that portion which is situated above
the intersection corresponds to the clavicular fibres of the
sterno-cleido-mastoid and of the trapezius.

The mastoido-humeral presents certain varieties in dif-
ferent animals.

In the dog and the cat, this muscle, which is blended above
with the sterno-mastoid (see p. 153), to be inserted with it
into the mastoid process and the mastoid crest, covers the
neck for a considerable extent from the superior curved line
of the occipital bone to which it is attached, to the trapezius
with which it unites posteriorly, but from which it separates
below. Between these two extreme points of its superior
portion it is attached to the cervical ligament.

In the pig and in ruminants, in which the trapezius
approaches more closely to the head, the mastoido-humeral
occupies, in consequence, a less extent of the cervical region.

In the horse, the mastoido-humeral neither covers the
neck nor joins the trapezius ; indeed, we have already
shown that it is separated by a considerable distance from

MYOLOGY 153

the head. In the hmited interval between these two
muscles a part of the rhomboid and parts of other muscles
are seen with which we shall soon be occupied.

This muscle, as regards the horse, is described by some
anatomists as consisting of two parts : one anterior, or
superficial ; the other posterior, or deep. In reality, the
first only corresponds to the mastoido-humeral, which
we are considering ; the posterior may be more exactly
regarded as representing a special muscle of quadrupeds,
but which is here a little deformed, the omo-trachelian (see

P- 155)-

When the mastoido-humeral contracts, taking its fixed
point above, it acts as an extensor of the humerus, and
carries the entire fore-limb forwards. If it takes its fixed
point below — that is to say, at the humerus — it inclines
the head and neck to its own side. If it contracts at the
same time as the mastoido-humeral of the opposite side,
then the head and the neck are carried into the position of
extension.

The Sterno-mastoid (Fig. 66, 5 ; Fig. 68, it ; Fig. 69, 15 ;
Fig. 70, 17). — Having described the clavicular portion of
the sterno-cleido-mastoid in connection with the mastoido-
humeral, because it forms a part of the la.tter, we have,
in order to complete the homologies of this muscle, to study
now that which corresponds to its sternal portion. This is
the sterno-mastoid muscle. In all the quadrupeds with which
we are here concerned this muscle arises from the anterior
extremity of the sternum ; narrow and elongated in form,
it passes towards the head in a direction parallel to the
anterior border of the mastoido-humeral, from which it is
separated by an interspace which, along its whole length,
lodges superficially the jugular vein ; hence the name of
jugular groove, which is given to this part of the neck
(Fig. 10, 18).

It is inserted, in the case of the dog and cat, into the
mastoid process, where it is united with the mastoido-
humeral ; in the ox it is divided into two portions — one
which goes to the base of the occipital bone, the other
passing in front of the masseter is b}^ the medium of the

154 THE ARTISTIC ANATOMY OF ANIMALS

aponeurosis of this latter attached to the zygomatic crest.
This latter part is considered by some writers as forming
a portion of the panniculus muscle of the neck.

In the horse it is attached to the angle of the lower jaw
by a tendon, which an aponeurosis that passes under the
parotid gland binds to the mastoido-humeral muscle and
the mastoid process.

By reason of this insertion into the jaw, in the case of
the solipeds, this muscle is further named the sterno-
maxillary.

When it contracts, it flexes the head, and inclines it
laterally. This movement is changed to direct flexion when
the two sterno-mastoid muscles contract simultaneously.

In man, the sterno-cleido-mastoid and the trapezius
leave a triangular space between them, which, being limited
inferiorly by the middle third of the clavicle, is known as
the supraclavicular region ; this region , being depressed,
especially in its inferior part, has also been given the name
of supraclavicular fossa — popularly called the ' salt-cellar.^

The muscles which form the floor of this region, passing
from above downwards, are : a very small portion of
the complexus, splenius, levator anguli scapulae, posterior
scalenus, and anterior scalenus ; then, crossing these latter,
and most superficial, is the omo-hyoid muscle.

An analogous region, but of only slight depth, exists in
quadrupeds ; its borders are formed by the mastoido-humeral
and trapezius muscles.

It is not limited below by the clavicle — we know, indeed,
that this, or the intersection which represents it, belongs
to the mastoido-humeral muscle — but by the inferior portion
of the spine of the scapula.

It is of greater or less extent according to the species
considered.

In the dog, cat, pig, and ox, it is narrow, for the muscles
which bound it approach one another pretty closely. It has,
as in man, the form of a triangle, with the apex above.
In the horse it is much broader, and, contrary to the
arrangement which it presents in the human species, the
widest part is directed upwards.

MYOLOGY - - 153

The muscles which we find there are, consequently, more
or less numerous. In the dog and cat they are : a portion
of a muscle v/hich we do not normally meet with in man —
the omo-trachelian — then in a decreasing extent : supra-
spinatus, levator anguli scapulae and splenius.

In the pig : the omo-trachelian, supraspinatus, and the
terminal portion of the sterno-prescapular — the anterior
part of the lesser or deep pectoral muscle.

In the ox : the omo-trachelian only.

But in the' horse we find the omo-trachelian, the supra-
spinatus, and the terminal extremity of the sterno-pre-
scapular ; then in a larger extent of area the levator anguli
scapulae and the splenius ; and, finally, the anterior portion
of the rhomboid.

Among the muscles which we have just enumerated are
some that we have already studied ; these are the sterno-
prescapular and the rhomboid. We will examine the supra-
spinatus muscle in connection with the region of the shoulder.

As to the scaleni muscles and the complexus, they are
deeply situated, whereas the omo-hyoid is visible in the
anterior region of the neck only.

There remain for us, accordingly, to examine, at the
present juncture, but the omo-trachelian, levator anguli
scapulae, and splenius muscles.

The Omo-trachelian Muscle (Fig. 68, 13 ; Fig. 69, 17 ;
Fig. 70, 20). — Also called the acromio-trachelian, levator
ventri scapulce,'^ the angnlo-verdral muscle, and the tvansvevso-
scapular,f etc., this muscle is described by some liippoto-
mists as belonging to the mastoido-himieral, of which it then
forms its posterior or deep portion (see p. 153).
, The omo-trachelian muscle is found in all mammalia,

. . -l • • :

f—

. * Ventri, because inserted into the inferior part of the spine of the
scapula, towards the acromion — that is, on the ventral side — by contrast
with the trapezius, which is attached higher up (dorsal side) on the same
process.

t Among the many names given to this muscle, Arloing and Lesbre
recommend the adoption of the name ' transverse scapular ' given by
Straus-Durckheim, or ' transyerse of the shoulder ' (Arloing and Lesbre,
' Suggestions for the Reform of Veterinarian Muscular Nomenclature,'
Lyons, 1898).

156 THE ARTISTIC ANATOMY OF ANIMALS

man alone excepted. It is, however, sometimes found in
the human being ; but it then constitutes an anomaly.

In the dog, pig, and ox, it arises from the inferior part
of the spine of the scapula, in the region of the acromion, and
terminates on the lateral portion of the atlas.

In the cat it is attached besides to the base of the occipital
bone. It is visible in the space limited by the trapezius
and the mastoido-humeral, the direction of which it crosses
obliquely.

In the horse it appears to be blended in clearly defined
fashion with the mastoido-humeral. Attached below, like
this latter, to the anterior border of the humerus, it covers
the scapulo-humeral angle ; and is attached by its upper
portion to the transverse processes of the first four cervical
vertebrae.

We remember that the transverse processes are often,
from their relation with the trachea, known as the tracheal
processes. Hence the word ' trachelian,' which forms part
of the name of the muscle with which we are now dealing.

By its contraction it helps to draw the anterior limb
forwards.

When this muscle, as an abnormality, exists in man, it
arises from the clavicle or the acromion process, traverses
the supraclavicular fossa, and is inserted into the trans-
verse processes of the altas or axis, or of both these
vertebrae, or of the cervical vertebrae below these latter.
It is then known by the names of the elevator of the clavicle
or elevator of the scapula, and, finally, as the cleido-omo-
transversalis (Testut).*

The Levator Anguli Scapulae (Fig. 68, 15 ; Fig. 70, 23). —
As we have pointed out (p. 136), the levator anguli scapulae,
because of its connections with the great serratus, is some-
times described with it. But inasmuch as in human anatomy
these two muscles are considered separately, and that, in
the superficial layer of muscles, they are seen in different

* L. Testut, ' Les anomalies mnsculaires chez rhomme expliquees
par ranatomie comparee,' Paris, 1884, p. 97. A. F. Le Double, ' Traite
des variations du systeme musculaire de Thomme et de leur signification
au point de vue de I'anthropologie zoologique,' Paris, 1897, t. i., p. 235.

MYOLOGY 157

regions — the great serratus in the thoracic, and the levator
anguh scapulae in the cervical — we prefer to study them
separately.

We remember that in man this muscle arises from the
transverse processes of the upper cervical vertebrae and is
inserted into the superior portion of the spinal border of the
scapula, into the portion of this border which is situated
above the spine; it also contributes to the formation of the
floor of the supraclavicular region.

When it contracts, it draws the superior portion of the
scapula forwards and upwards, and causes a see-saw move-
ment, for at the same time the inferior angle of the scapula
is directed backwards. Taking its fixed point at the
shoulder, it directly extends the neck if the muscle of one
side acts at the same time as that of the opposite ; but
if only one muscle contracts it inclines the neck to the cor-
responding side.

It is to be noticed that during movements a little more
active than the ordinary the levator anguli scapulae, as
moreover the other miuscles of the neck do, becomes very
distinct. W^e have, indeed, often remarked that, apart from
these movements, each time the support of one of the fore-
limbs is brought into requisition a brusque contraction of the
muscles of this region accompanies it.

This contraction gives the impression that, as on the one
hand, each support determines a momentary arrest of
progression, a jolt, and on the other hand, the head con-
tinues to be projected in the forward direction, the latter
should be retained. But it cannot be so except by an effort
in the opposite direction — that is to say, by the brusque
contraction which we have just pointed out.

Analogous contractions also take place in a man while
running at the beginning of each contact of the lower limbs
with the ground.

We may add, apropos of this latter, that displacements
of the head, sometimes in very pronounced fashion, take
place during simple walking, and that every time one of
the lower limbs is carried forwards the head is projected
in the same direction. These displacements, which we

158 THE ARTISTIC ANATOMY OF ANIMALS

also find take place in the horse in pacing, especially in
the region of the neck and head, seem then to have the
effect of aiding the progression of the body forwards.

They occur especially in animals when drawing a heavy
load, and in individuals whose walking movements are
executed with difficulty.

It is necessary to repeat that, in these cases, the individual
appears to assist the movement of his body by the impetus
which the projection of his head forward determines, in
order to add — and it is for this that we have referred to the
subject — that during the intervals between each projection
the head is carried backwards by a muscular contraction
similar to that above discussed.

The Splenius (Fig. 68, 14 ; Fig. 70, 22). — In man, this
muscle is attached in the median line to the inferior half
or two-thirds of the posterior cervical ligament, to the
spinous processes of the seventh cervical, and four or five
upper dorsal vertebrae ; it passes obliquely upwards and out-
wards, becomes visible in the supraclavicular region, passes
under the sterno-cleido-mastoid, and proceeds to duplicate
the cranial insertions of this latter ; and, further, the most
external fasciculi of this muscle are inserted into the trans-
verse processes of the atlas and the axis.

These separate superior attachments, and the division of
the muscle which results, have caused the splenius to be
regarded as formed of two portions : splenius of the head,
and splenius of the neck.

In the horse, this muscle, which is of voluminous dimen-
sions, arises from the superior cervical ligament, and the
spinous processes of the first four or five dorsal vertebrae ;
thence it proceeds to be inserted into the mastoid crest,
and the transverse processes of the atlas and three or four
vertebrae following.

The region occupied superficially by the splenius is re-
markable for the prominence which this muscle, with the
deeply-seated complexus, which is equally bulky, deter-
mines at this level ; it is situated above that region of the
neck, in which are seen in part the fasciculi of the levator
anguli scapulae. It terminates above and in front in the

MYOLOGY 159

ridge, which is sometimes very pronounced, which the
transverse processes of the atlas make on each side of this
part of the neck.

In the dog and the cat, the superior and anterior region
of the neck is thick and of rounded form, on account of the
development which the splenius presents in those animals ;
but it is covered by the mastoido-humeral.

This latter relation is also found in the ox, but the splenius
in this case is but slightly developed.

When the splenius contracts it extends the head and neck,,
while inclining them to its own side.

If the splenius of one side contracts at the same time as
that of the opposite, the extension takes place in a direct
manner — that is to say, without any modifying lateral
movement.

Infrahyoid Muscles

Having studied the lateral surfaces of the neck, we must
now examine the anterior part of this region. Here, between
the two sterno-mastoid muscles, we find a space broader
above than below, in which are situated the larynx and the
trachea, to the general arrangement of which is due the
cylindrical form which this region presents. This space
corresponds to that which in the neck of man is limited
laterally by the sterno-cleido-mastoid muscles, below by
the fourchette of the sternum, and above by the hyoid
bone. In animals, as in man, it is called the infrahyoid
region.

The hyoid bone in quadrupeds is situated between the two
rami or branches of the lower jaw. Owing to this disposi-
tion, the region above this bone, instead of having its surface
projecting a little beyond the inferior border of the maxillary
bone, is depressed. This is especially so in the horse. It
is there that we find in this animal the region known as the
trough {auge) ; the larynx corresponds to that part known as
the gullet.

The muscles which occupy the infrahyoid region are : the
sterno-thyroid, the sterno-hyoid, and the omo-hyoid. There

i6o THE ARTISTIC ANATOMY OF ANIMALS

is also a thyro-hyoid, but because of its deep situation and
its slight importance it offers no interest from our point of

view.

Sterno-thyroid and the Sterno-hyoid Muscles. — These
two muscles, long, narrow, and flat, arise from the anterior
extremity of the sternum ; then, covering the anterior
surface of the trachea, they proceed to terminate, the one
on the thyroid cartilage, and the other on the hyoid bone.
The sterno-hyoid is superficial ; it covers the sterno-thyroid,
which, however, projects a little on its outer side.

Omo-hyoid. — This muscle does not exist in the dog or
cat. It arises, in the horse, from the cervical border of the
scapula, where it blends with the aponeurosis that envelops
the subscapularis muscle, but in the pig and the ox it arises
from the deep surface of the mastoido-humeral muscle. It
is directed obliquely upwards and inwards, becoming super-
ficial at the internal border of the sterno-mastoid, and
is inserted into the hyoid bone.

The region in which are united the portion of the neck
which we have just studied and the neighbouring part
of the thorax — that is, the breast — has certainly, in our
opinion, a form less expressive than the corresponding
region in man.

In the latter, indeed, the fourchette of the sternum, with
the hollow which it determines, the heads of the clavicles,
and the sterno-cleido-mastoid muscles, by the elevations
which they produce, and the trachea, by the situation which
it occupies in the inferior part, constitute a whole in which
are admirably indicated, not only the forms of the organs
which constitute this region, but also the relations which
these organs have one with another; and, to a certain extent,
their respective functions.

In making an exception in the case of the ox, in which a
fold of skin, the deidap, which passes from the neck to the
breast, constitutes an element of form which possesses
some expressive value ; in the horse and in the dog, which
possess no sternal fourchette and no heads of clavicles, the
bones and the muscles are found nearly on the same plane.
This produces a uniformity which is evidently inferior, from

MYOLOGY i6i

an aesthetic point of view, to the modelHng of the corre-
sponding region of the human body. Such, at least, is our
impression.

Suprahyoid Muscles

As their name indicates, these muscles are found above
the hyoid bone ; amongst those which should arrest our
attention for a moment are the mylo-hyoid and the digastric.

Mylo-hyoid. — This muscle, forming a sort of fleshy sling
which contributes in great measure to form the floor
of the mouth, is situated between the lateral halves of
the inferior maxillary bone. Arising on each side from the
internal oblique line of the mandible, its fibres are directed
towards the median line, to be inserted posteriorly into the
hyoid bone, and, between this bone and the anterior part of
the mandible, into a median raphe which unites these latter.

Digastric. — This muscle arises from the styloid process
of the occipital bone and from the jugular process ; it
thence passes downwards and forwards, and terminates
variously, in different species. In the ox and the horse it
terminates in its anterior portion on the internal surface
of the inferior maxillary bone, close to the chin. But
in the horse a bundle of fibres is detached from the upper
portion of the muscle, to be inserted into the recurved
portion of the jaw. It is to this fasciculus that Bourgelat
has given the name of ^stylo-maxillary muscle.''

In the pig, dog, and cat, the digastric differs more from
the corresponding muscle in man ; it is not, as in the latter,
formed of two parts. The anterior portion only exists.
This consists of a thick muscular mass, which is inserted into
the middle of the internal surface of the lower jaw.

In the dog and cat it is clearly recognisable in the super-
ficial layer of muscles by the long and thick prominence
which it produces below the masseter, against the inferior
border of the mandible (see pp. 235 and 237, the two figures
showing the myology of the head of the dog).

By its contraction, it draws the lower jaw downwards and
backwards.

II

i62 THE ARTISTIC ANATOMY OF ANIMALS

Panniculus of the Neck, — This very thin muscle, which
cannot be recognised on the exterior, calls for little notice.

We shall merely point out that it duplicates the skin of the
cervical region ; but as the latter is only slightly adherent to
it, the panniculus of this region seems rather destined to
maintain in position the muscles which it covers than to dis-
place the cutaneous covering.

We recall the fact that in man, on the contrary, the muscle
is very evident at the instant of its contraction, and, for this
reason, it presents a very great interest with regard to
external modelling, and it plays an important part in the
expression of the physiognomy.

MUSCLES OF THE ANTERIOR LIMBS
Muscles of the Shoulder

Deltoid (Fig. 68, i6, 17 ; Fig. 69, 18 ; Fig. 70, 24). — This is
the first muscle we study in connection with the shoulde r in
human anatomy. Indeed, its wholly superficial position, and
especially the manner in which it is separated from the sur-
rounding muscles, its volume, and its characteristic modelling,
give it such an importance that, from the didactic point of
view, there is every indication for commencing with this
muscle in studying the region to which it belongs. If, in
regard to quadrupeds, we also commence with it, it is merely
in deference to the spirit of method, and for the sake of sym-
metry ; for it is far from presenting, in the latter, characters
so distinctive and so clearly defined.

It is necessary to remark, at the outset, that in quad-
rupeds, on account of the absence or slight development of
the clavicle, the clavicular portion of this muscle is, as we
have shown, united to bundles of the same kind belonging
to the stemo-cleido-mastoid and trapezius to form the mas-
toido-humeral (see p. 151). There exists, therefore, in an
independent form, the scapular portion only.

It is this latter which, by itself alone, forms the deltoid of
quadrupeds, a muscle known, in veterinary anatomy, as the
long abductor of the arm.

MYOLOGY 163

In the dog and the cat it consists of two parts, one of
which arises from the spine of the scapula ; the other from
the acromion process. Thence it passes to the crest of the
humerus, which Hmits the musculo-spiral groove anteriorly,
to be attached at a point which is found, as in other quad-
rupeds, to be the homologue of the human deltoid impression,
or deltoid V, of the human humerus.

In the ox, in which the acromion process, which is
very rudimentary, does not attain the level of the glenoid
cavity, the acromion portion is but slightly marked off
from that which takes its origin from the spine of the
scapula.

Still, in the horse, which is completely deprived of an
acromion process, the deltoid muscle is correspondingly
divided into two parts, separated from one another by
superficial interstices, but of which the arrangement differs
from that of the portions above indicated ; one part, the
posterior, arises above from the superior part of the posterior
border, and the postero-superior angle of the scapula (exactly
as if, in man, certain fasciculi of the deltoid took their
origin from the axillary border and inferior angle of the
scapula) ; the other, anterior, arises from the tuberosity of
the spine of the same bone. The two parts, united in-
teriorly, proceed to be inserted into the deltoid impression
or infratrochiterian crest of the humerus.

It is necessary to add that the deltoid is inserted into the
humerus, above the insertion of the mastoido-humeral.

This muscle flexes and abducts the humerus, and also
rotates it outwards.

With regard to the other muscles of the human shoulder,
subscapularis, supraspinatus, infraspinatus, teres minor and
teres major, they are also present in quadrupeds, but in a
form more elongated, as the scapula has its dimensions more
extended from below upwards — that is, from the glenoid
cavity towards the superior or spinal border.

Subscapularis. — This muscle occupies the subscapular
fossa, from which it takes its origin, leaving free the superior
part where the surface is found, to which are attached the
serratus magnus and the levator anguli scapulae. It passes.

II — 2

i64 THE ARTISTIC ANATOMY OF ANIMALS

towards the arm, to be inserted into the small tuberosity
of the humerus. It is an adductor of the arm.

The subscapularis does not offer any interest from the point
of view of external form, for it is completely covered by the
scapula.

We speak of it, however, because we mention it in
human anatomy, and that it affords us here a new oppor-
tunity of brmging into prominence the differences which exist
in connection with the mobility of the shoulder.

We remember that in man, when the arm is abducted, and
then raised a little above the horizontal, the scapula see-
saws, is separated, to a certain extent, from the thoracic cage
interiorly and externally, and that, on the superficial layer of
muscles, we are then able to see in the bottom of the arm-
pit, at the level of the deep portion of the posterior wall of the
latter, a small part of the subscapularis muscle.

In the animals with which we are here occupied it is not
the same ; for they are incapable of performing with their
fore-limbs a movement analogous to that to which we have
just referred, the humerus in their case being retained in
contact with the trunk by the muscular masses which
surround it.

Supraspinatus (Fig. 68, 19 ; Fig. 70, 25 ; Fig. 72, 7). —
This muscle, as its name indicates, occupies the supra-
spinous fossa — that is to say, that which, by reason of the
direction of the scapula in quadrupeds, is situated in front of
rather than above the spine. It arises from this fossa ; and,
further, from the external surface of the cartilage which
prolongs the scapula upwards in solipeds and ruminants. It
projects more or less beyond the supraspinous fossa in front.

After passing downwards towards the humerus, it is in-
that is to say, to a part of this osseous prominence which
serted into the summit of the great tuberosity or trochiter —
represents the anterior facet of the great tuberosity of the
human humerus, into which, as we know, the corresponding
muscle is inserted.

In solipeds and ruminants it is inserted, by a second
fasciculus, into the small tuberosity.

In the pig and the horse its anterior border is in relation

MYOLOGY 165

with the terminal portion of the sterno-prescapular anterior
portion of the small or deep pectoral.

The supraspinatus, which in man is completely covered
by the trapezius, is partly visible in the superficial layer of
the cat, dog, pig, and horse, in the lower part of the space
limited by the mastoido-humeral and the trapezius. It is
crossed by the scapulo-trachclian.

It is, in the ox, completely covered by these muscles, but
its form, notwithstanding this, is easily discerned by the
prominence which it produces. When it contracts, the
supraspinatus muscle carries the humerus into the position
of extension.

Infraspinatus (Fig, 68, 20; Fig. 72, 8). — This muscle,
which occupies the infraspinous fossa, which, in quadrupeds,
is situated behind the spine of the scapula, arises from the
whole extent of this fossa, and in solipeds and ruminants
encroaches on the cartilage of prolongation. Its fibres are
directed downwards and forwards, to be inserted into the
great tuberosity of the humerus — the trochiter — below the
insertion of the supraspinatus.

It is completely covered (ox and horse), or in part only
(cat and dog), by the portion of the deltoid which arises from
the spine of the scapula ; nevertheless, its presence is re-
vealed by the prominence which it produces.

It is an abductor and external rotator of the humerus.

In connection with this muscle, which, as we have just
pointed out, is less seen in the superficial muscular layer than
the supraspinatus, we will draw attention to the fact that
this arrangement is exactly the reverse of that which is found
in the human shoulder. In this latter it is the supraspinatus
which is not visible ; while, on the contrary, the infraspinatus
is uncovered in a considerable part of its extent. We
further notice that it is accompanied by the teres minor, and
that the teres major, situated inferiorly, forms with these two
muscles a fleshy mass which, below, ends on the superior
border of the great dorsal muscle.

In quadrupeds, in which the infraspinatus is so slightly
visible, the teres major and minor are not found at all in the
superficial muscular layer.

i66 THE ARTISTIC ANATOMY OF ANIMALS •

Accordingly, we will say but few words about them.

Teres Minor (Fig. 72, 9). — This muscle, also called in
veterinary anatomy the short abductor of the arm, arises
from the posterior border of the scapula (the external
border in man), and is inserted below the great tuberosity

cN.C.

Fig. 72. — Myology of the Horse — Shoulder and Arm : Left Side,

External Surface.

I, Cartilage of prolongation of the scapula ; 2, tuberosity of the spine
of the scapula ; 3, superior extremity of the humerus ; 4, inferior ex-
tremity of the humerus; c, radius; 6, ulna; 7, supraspinatus muscle;
8, infraspinatus; 9, teres minor; 10, biceps; 11, tendon of the biceps
passing over the anterior surface of the superior extremity of the humerus ;
12, brachiahs anticus; 13, triceps, long head; 14, external head of the
triceps divided; 15, external head of the triceps reflected, in order to
expose the anconeus ; 16, region normally occupied by the external head of
the triceps ; 17, anconeus.

of the humerus, between the attachments of the infra-
spinatus and deltoid.

It is covered by the deltoid and the infraspinatus.

Teres Major. — This muscle is known to veterinarians as

MYOLOGY 167

the abductor of the arm ; it arises from the postero-superior
angle of the scapula (the inferior angle of the human
scapula), from which it passes to be inserted into the internal
surface of the humerus.

It is covered by the latissimus dorsi and the posterior
muscular mass of the arm.

In brief, for the better understanding of the relations of the
teres major and minor muscles in quadrupeds, we may fancy
the corresponding muscles in man modified in the following
manner : The infraspinatus, thicker, covering the teres minor ;
latissimus dorsi, more extended in its superior part, covering
a large proportion of the teres major. As to the relations
of the teres minor with the deltoid, they exist in man,
seeing, in this case, the same muscle is, in its external
portion, covered by this latter. With regard to the relations
of the teres major with the posterior muscular mass of the
arm, they also exist in man, since the external surface of
this muscle is covered by the triceps.

These modifications are sufficient to render the small and
large teres muscles completely invisible in the superficial
layer.

The muscles of the shoulder which we have just been
studying fulfil, with regard to the articulation which they
surround, the function of active ligaments. This role
is made necessary by the laxity of the scapulo-humeral
capsule — a laxity which renders it incapable by itself of
maintaining the bones in contact at this joint.

The same condition exists in man.

Panniculus Muscle of the Shoulder. — This thin muscle
covers, as its name implies, the region of the shoulder, and
is the continuation forward of the panniculus muscle of the
trunk.

It arises, by its superior part, from the region of the
withers and from the superior cervical ligament ; thence its
fibres descend directly towards the elbow, to terminate at
the level of the region of the forearm.

The muscle is not found in the pig or in the carnivora.

i68 THE ARTISTIC ANATOMY OF ANIMALS

Muscles of the Arm

We should remember, at the outset, that in man the
muscles of the arm are divided into two groups : one
anterior, which contains the biceps, brachialis anticus, and
the coraco-brachialis ; the other, posterior, which is consti-
tuted by a single muscle, the triceps.

In animals, we find them in the same number and arranged
in analogous fashion — that is to say, in two groups — with
respect to the bone of the arm. But then we find that they
have undergone a transformation with regard to their length,
and it is the change of general aspect which results from this
modification that we proceed to examine.

We know that in quadrupeds, and especially in the
domestic animals, the humerus is relatively short in propor-
tion to the forearm. We have already seen, in dealing with
the bones, that whilst in the human species the humerus
is longer than the forearm, in the dog and cat these two
segments of the fore-limb are of equal length, and that the
humerus of the horse is, on the contrary, much shorter.
Now, let us suppose the human humerus to be shorter than
it is in reality ; the anterior muscles undergoing, very natur-
ally, the same reduction, will be uncovered only slightly by
those above — the deltoid and the great pectoral — or will
remain completely hidden by them. Thus would be found
realized the disposition which we meet with in quadrupeds
of the muscles of this region.

With regard to the posterior muscular mass of the arm, it
does not undergo the same change. The muscle which
constitutes it — the triceps cubiti — occupies, on the con-
trary, a greater area. Let us suppose, further — for it is
the best method of comprehending the homologies which
now occupy our attention — the humerus of man to be
shortened as before, and directed downwards and backwards
(as in quadrupeds), this bone would form an acute angle
with the axillary border of the scapula. Let us suppose
also that the long portion of the triceps, instead of arising
solely from the superior part of this axillary border, is
attached to the whole length of the latter, and that the

MYOLOGY 169

triceps fills the whole interior of the angle formed by the arm
and the shoulder. We then shall have an idea of what the
triceps is in quadrupeds. It is necessary to add that the
general resemblance would be still more complete if the arm
were firmly supported by the side of the thorax, because in
quadrupeds it occupies an analogous position, determined
by the arrangement of the muscles which, proceeding from
the trunk and neck, are attached to it.

Anterior Region

Biceps Cubiti (Fig. 68, 21 ; Fig. 72, 10, 11). —
This muscle, also called the long flexor of the forearm, does
not merit the name except by its analogy with the corre-
sponding muscle in man. Indeed, in the domestic animals
it is not divided into two parts ; it is represented by a
single fasciculus, long and fusiform, situated on the front of
the humerus, and directed obliquely downwards and back-
wards, as the latter, on its part, is also inclined.

It arises above from a tubercle at the base of the coracoid
process, which surmounts the glenoid cavity of the scapula.
Its tendon, which is highly developed in the solipeds, occu-
pies the bicipital groove. We remember that in these latter
the groove in question is divided into two channels by a
median prominence.

The tendon in which the muscle ends is inserted into a
tuberosity, situated on the internal surface of the superior
extremity of the radius — the bicipital tuberosity. In the pig,
the cat, and the dog, there is detached from the tendon to
which we have just referred a fasciculus of the same nature,
which, after having wound round the radius, is inserted into
the internal surface of the ulna, towards the base of the
olecranon process. From the inferior part of the muscle
arises a fibrous band, comparable to the aponeurotic ex-
pansion of the human biceps ; but, instead of passing down-
wards and inwards, as does the latter, it terminates on
the muscular mass which constitutes the antero-external
part of the forearm.

The biceps is not seen in the superficial layer, except in
the dog and cat (in which the humerus is, in fact, propor-

170 THE ARTISTIC ANATOMY OF ANIMALS

tionately long) ; and even in them only to the slightest
extent. It is covered partly in these latter, and completely
in other animals, by the great pectoral and the inferior
portion of the mastoido-humeral — that is to say, that part
of the latter which represents the whole of the clavicular
fibres of the human deltoid.

The biceps is a flexor of the forearm on the arm. It also
contributes to the movement of extension of the humerus.

Brachialis Anticus (Fig. 68, 22 ; Fig. 69, 19 ; Fig. 70,
27 ; Fig. 72, 12). — In veterinary anatomy further desig-
nated as the short flexor of the forearm, this muscle, which is
thick, occupies the musculo-spiral groove, and arises from
it, reaching upwards to just below the head of the humerus.
But it does not, as in man, extend to the internal surface of
the bone.

Situated on the outside of the biceps, it is directed towards
the forearm, and terminates by a flattened tendon, which,
dividing into two slips, passes below the bicipital tuber-
osity, on the internal surface of the radius, into which one of
these slips is inserted, while the other proceeds to terminate
on the ulna.

The inferior half of this muscle is visible on the superficial
layer, in the space limited posteriorly by the triceps brachi-
alis, and below by the muscles of the forearm, which corre-
spond to the external muscles of the human forearm, and in
front by the great pectoral and the mastoido-humeral. It
is in the upper part of the interspace which separates these
latter from the brachialis anticus that the deltoid insinuates
itself to proceed to its insertion into the humerus.

These relations precisely recall those which we meet with
when we examine the external surface of the human arm,
with this difference, however — that in the latter the anterior
brachialis anticus is extensively related, in front, to the biceps.
However, in animals it is not absolutely the same, since,
as we have shown above, the biceps is covered, more or
less completely, by the mastoido-humeral and the great
pectoral.

The brachialis anticus flexes the forearm on the arm.

Coraco-brachialis. — In man this muscle, which occu-

MYOLOGY 171

pies the superior half, or third, of the internal surface of
the humerus, is visible only when the arm is abducted,
and then especially when it approaches the vertical posi-
tion ; indeed, it is only in this attitude that the region
which it occupies is accessible to view.

But an analogous attitude not being possible in domestic
animals, in which the arm is fixed along the corresponding
parts of the trunk, the result is that the coraco-brachialis is
always covered, and that, consequently, it presents nothing
of interest from our point of view. We speak of it, then,
merely in order to complete the series of the muscles of the
anterior surface of the arm, among which we rank it, in spite
of the fact that in veterinary anatomy it is described as a
muscle of the shoulder.

It arises above from the coracoid process, and thence
passes downwards towards the internal surface of the
humerus into which it is inserted, more or less high up,
according to the species. The coraco-brachialis is an
adductor of the arm.

Posterior Region.

Triceps Cubiti (Fig. 68, 23, 24 ; Fig. 69, 20, 21 ;
Fig. 70, 28, 29 ; Fig. 72, 13, 14, 15, 16).— This muscle, which
is voluminous in the quadrupeds with which we are here con-
cerned, fits more or less completely the angular space between
the scapula and the humerus. Its bulk forms a thick
prominence, which surmounts the elbow and the forearm.
. We should say, with regard to this mass, that if the deltoid
does not constitute in quadrupeds a prominence sufficient to
remind one of that which this muscle produces in man,
the triceps, in producing an analogous elevation, seems to
replace in the general form of the body the relief which the
deltoid is incapable of producing.

The triceps is divided into three portions, which, as in
man, have the names middle, or long head ; external and
internal heads. But that which renders the nomenclature a
little complicated is that veterinary anatomists have given
other names to these three parts : that of great extensor of
the forearm (caput magnum) to the long head ; the short

172 THE ARTISTIC ANATOMY OF ANIMALS

extensor of the forearm (caput parvum) to the external head ;
and of medium extensor of the forearm (caput medium) to the
internal.*

It is more especially the long portion and the external
head which, being visible on the external surface of the arm,
contribute to the external form.

The long portion, which is triangular in shape and of
considerable development, arises in the cat and the dog from
the inferior half or two-thirds of the posterior border of the
scapula (axillary border) ; from the whole extent of that
border as far as the superior posterior angle in the pig, the
ox, and the horse ; it then passes downwards towards the
articulation of the elbow, to terminate in a tendon which is
inserted into the olecranon process. The portion of this
muscle which is next the scapula is covered by the deltoid.

The external head, situated below the long portion, is
directed obliquely downwards and backwards. It arises
from the curved crest which, from the deltoid impression
of the humerus, is directed upward to meet the articular head
of the same bone. This crest limiting the musculo-spiral
groove superiorly, and the brachialis anticus arising from the
whole extent of this groove, the result is that at this level
the external head is in relation with the brachialis anticus.
From this origin it is directed towards the elbow, to be
inserted into the olecranon, either directly or by the medium
of the tendon of the long portion. The part of this muscle
which arises from the humerus is covered by the deltoid.

As for the internal head (Fig. 76, 4), which, in the super-
ficial layer, is only visible in its inferior part, on the internal
aspect of the arm in those animals in which the elbow is
free of the lateral wall of the thorax (the dog and the cat,
for example), it arises from the internal surface of the
humerus, and thence proceeds to be inserted into the ole-
cranon.

* Other names given by certain authors to the parts of this muscle
which we have just enumerated still further complicate this nomenclature.

The long head is further designated by them under the names of the
long or great anconeus ; the external head under those of external anconeus,
or lateral or short anconeus ; whilst the internal head becomes the internal
anconeus, or median.

MYOLOGY 173

The triceps extends the forearm on the arm.

A fourth muscle exists, which veterinary anatomists
include in the study of the three portions of the triceps which
we have just been discussing, in giving it the name of
small extensor of the forearm. But, as this muscle is no other
than the anconeus, and as, in human anatomy, we de-
scribe the latter, according to custom, in connection with
the forearm, it is when on the subject of the latter that we
will concern ourselves with it. This grouping of muscles
cannot fail to give greater clearness to the description of the
muscles of these regions.

The Supplemental or Accessory Muscle of the Latis-
simus Dorsi (Fig. 76, 2 ; Fig. yy, i). — Because of the
relations, to which we have already referred (see p. 142),
of this muscle with the triceps cubiti, its description very
naturally follows that of the latter.

Indeed, this supplementary muscle of the great dorsal is
further designated in zoological anatomy under the name
of long extensor of the forearm ; and this name indicates that
its study may be united to that of the triceps.

Situated on the internal surface of the arm, it arises
from the external aspect of the tendon of the latissimus
dorsi ; it is very highly developed in the horse, in which it
also arises from the posterior border (axillary) of the
scapula ; then, covering in part the internal head of the
triceps and also the long portion, on the superior border of
which it is folded, it proceeds to be inserted into the ole-
cranon process and the anti-brachial aponeurosis.

It extends the forearm on the arm. Further, it makes
tense the aponeurosis into which it is inserted ; this explains
the name of tensor of the fascia of the forearm, which is some-
times given to it.

It seems to us interesting to add that, abnormally, we
sometimes find in man an analogue of this muscle. It is
given off from the latissimus dorsi, near the insertion of the
latter into the humerus ; it accompanies the long head of
the triceps and becomes fused with it. Sometimes it is
inserted into the olecranon process, at other times into the
antibrachial aponeurosis or the epitrochlea. It is on account

174 THE ARTISTIC ANATOMY OF ANIMALS

of its insertion into the last-mentioned, in some cases, that
it is also designated by the name of dorso-cpitrochlear
muscle.*

Muscles of the Forearm

Before commencing the special examination of each of
the muscles of this region, it is absolutely indispensable to
consider their general arrangement, and to determine very
clearly how we should study them. We are too well con-
vinced of the importance of this preliminary examination
to dismiss it without entering rather fully into it. Indeed,
the region on the myological study of which we are now
entering is, unquestionably, one of the most complicated
with which we have to deal. We know besides, in regard
to the study of the forearm in man, how much a definite
method is necessary in order that the arrangement of the
muscles of this region be fixed in the memory, and that we
are unable to obtain this result otherwise than by grouping
the twenty muscles which constitute it in clearly defined
regions.

We also know that these muscles are first studied with the
forearm in the position of supination, and that it is only
when they are well known after having considered them in
this position that we are able to analyze and comprehend
their forms when it is in pronation.

Now, as we have pointed out in the section on osteology
(see p. 34), the forearm in quadrupeds is always in the
position of pronation. Should we, then, in order to main-
tain the symmetry with human anatomy, first study the
forearm in the position of supination ? Evidently not.
Besides the fact that this would in some cases be impos-
sible since — as in the horse, for example — the radius and ulna

* L. Testut, ' Anomalies musculaires chez Thomme expliquees par
I'anatomie comparee,' Paris, 1884, p. 118. A. F. Le Double, ' Traite
des variations dn systeme musculaire de I'homme et de leur signification
au point de vue de I'anthropolo.Erie zoologique,' Paris, 1897, t. i., p. 203.
Edouard Cuyer, ' Anomalies musculaires ' (Bulletins de la Socicte Anthro-
pologique, Paris, 1893).

MYOLOGY 175,

are fused together, we should not gain any advantage ; this
position being never completely realizable even in those-
quadrupeds which have the radius relatively movable^as,.
for example, in the cat.

Accordingly, it is pronation which here, in connection.
with animals, becomes the standard attitude from the point
of view of description. This is why, supposing that the
reader knows well the muscles of the human forearm in the-
position of supination, we should recall what is the general
arrangement occupied by these muscles when it is in prona-
tion.

The fore-limb, being viewed on its anterior surface, pre-
sents above the anterior aspect of the region of the elbow ;.
but below, it is the posterior surface of the wrist which is
seen. Consequently, in the superior part, we see the ex-
ternal and anterior muscles limiting the hollow in front of
the elbow ; inferiorly are found the posterior muscles.

The long supinator, passing obliquely downwards and
inwards, divides, in fact, the forearm into two parts : one
supero-internal, the other infero-external. In the first we
see, but to an extent less and less considerable, the pro-
nator teres, the flexor carpi radialis, the palmaris longus,
and the flexor ulnaris ; as to the flexors of the digits, on
account of the rotation of the radius, they are only visible on
the opposite surface — that is to say, on the surface of the
wrist, which is now posterior. In the second part we see the
two radial extensors, the common extensor of the fingers,
the proper extensor of the little finger, and the ulnar extensor
which, inferiorly, remains behind, by reason of the position
of the ulna being unchanged, whilst the anconeus is wholly
posterior, since the direction of the elbow is not modified..
We also find, in this region, the long abductor of the thumb,
the short extensor of the thumb, the long extensor of the
thumb, and the special extensor of the index-finger, in the
region where these deep muscles become superficial.

So that, to summarize, the external and posterior muscles
occupy the anterior and external regions of the forearm,
whilst the anterior muscles occupy rather the internal and
posterior. It is in regarding them after this manner — that

176 THE ARTISTIC ANATOMY OF ANIMALS

is to say, arranged in these two regions — that we proceed
to study these muscles in quadrupeds.

Anterior and External Region

Supinator Longus. — We know that this muscle, which
is especially a flexor of the forearm on the arm, plays, not-
withstanding the name which has been given it, a part of
but little importance in the movement of supination.

It acts slightly, however, as a supinator, for, being very
oblique downwards and inwards at the time of pronation, it
is able, while tending to resume its vertical direction, to
carry the radius outwards ; it places, in fact, the forearm
in a position midway between pronation and supination.

We have just recalled these details, in order that it may
be more easy to understand why it does not exist in animals
in which the radius and ulna are fused together (horse, ox) ;
and why, on the other hand, we find traces of it in the cat
and the dog, in which the radius — to a slight extent, it is
true — is able to rotate on the ulna. This displacement
being a little more considerable in the felide, the long supi-
nator is a little further developed than it is in the canine
species ; but, notwithstanding, it is only rudimentary.

The long supinator arises, above, from the external border
of the humerus ; thence, in the form of a very narrow
fleshy band, it passes obliquely downwards and inwards,
to be inserted into the inferior part of the internal surface
of the radius.

It assists in turning the radius outwards and placing it
in front of the ulna, the movement of supination being
capable of being but little further extended.

First and Second External Radial Muscles: Extensor
carpi radialis longior and hrcvior (Fig. 73, 8 ; Fig. 74, 8, 9 ;
Fig. 75, 8, 9). — Fused together, these muscles form by their
union what veterinary anatomists call the anterior extensor of
the metacarpus. But we should add that these two muscles
are united so much the more intimately as we examine
them in passing successively from the cat to the dog, pig,
ox, and horse. Thus, in the cat they are often distinct ; in

MYOLOGY 177

the dog, they unite only at the level of the middle third of
the radius, and interiorly they have two tendons ; in the
pig, the ox, and the horse they are completely united, and
there exists but a single tendon.

The anterior extensor of the metacarpus, which is situated
behind the long supinator when the latter exists, occupies
the external aspect of the forearm ; its well-defined form
absolutely recalls the prominence on the superior part of the
external margin of the human forearm.

It arises superiorly from the portion of the external border
of the humerus which is situated above the epicondyle and
behind the musculo-spiral groove. Its fleshy mass appears in
the angular space bounded by the brachialis anticus and the
triceps. The superior portion is covered by the external head
of the triceps ; yet, in the dog, the superior portion of its
humeral attachment is the only part so covered. This muscle
is directed forward and downwards ; it is also inclined a little
inwards in such manner as to proceed to occupy the anterior
aspect of the forearm.

Its fleshy belly is narrowed below, and, towards the
inferior part of the forearm, is continued by a tendinous
portion which is situated on the anterior surface of the
carpus, after having traversed the median groove of the
inferior extremity of the radius.

In the cat and the dog, in which the union of the two
radial extensors is incomplete, the two tendons are
inserted into the front of the base of the second and third
metacarpal bones ; consequently, as in man, into the meta-
carpals of the index and middle fingers.

In the ox, the tendon, which is single, is inserted into the
internal and anterior half of the superior extremity of the
principal metacarpal.

In the pig, this tendon is attached to the base of the large
internal metacarpal.

In the horse, the corresponding tendon is attached to a
tubercle which is situated on the anterior surface of the base
of the principal metacarpal, a little internal to the median
plane of the latter.

In order to properly understand and remember the re-

12

178 THE ARTISTIC ANATOMY OF ANIMALS

Ei»X

Fig. 73. — Myology of the Dog : Left Anterior Limb, External

Aspect.

I, Mastoido-humeralis ; 2, biceps; 3, brachialis anticus ; 4, triceps, long
portion; 5, triceps, external head; 6, olecranon process; 7, epicondyle ;
8, radialis muscles (anterior extensor of the metacarpus) ; 9, extensor
communis digitorum (anterior extensor of the phalanges) ; 10, extensor
minimi digiti (lateral extensor of the phalanges, or common extensor of
the three external digits) ; 11, posterior ulnar (external flexor of the meta-
carpus); 12, pisiform bone; 13, anconeus; 14, extensor ossis metacarpi
pollicis and extensor primi internodii pollicis (oblique extensor of the
metacarpus) ; 15, radius ; 16, anterior ulnar (oblique flexor of the meta-
carpus) ; 17, external border of the hypothenar eminence (abductor of
the little finger).

MYOLOGY 179

spective positions occupied by these inferior insertions, it
must be remembered that the human forearm being in the
position of pronation, the tendons of the radials are attached
to the bases of the metacarpals nearest to the thumb — that
is to say, those occupying an internal position as regards
the fourth and fifth metacarpals.

As its name indicates, this muscle extends the metacarpus.
Consequently it is, in the horse, an extensor of the canon-
bone.

It is also an adductor of the hand in those animals (cat,
dog) in which the radio -carpal articulation, analogous
in form to the corresponding articulation in man, permits
lateral movements of the hand on the forearm. The union
of the fleshy bodies of the two radials is sometimes found
in the human species.

Supinator Brevis. — As in the case of the long supinator,
the short supinator is found only in animals in which the
radius can be rotated to a greater or less extent around
the ulna ; therefore this muscle is not found in the pig, the
ox, or the horse ; but it forms part of the forearm of the cat
and the dog.

Deeply situated at the region of the elbow, the short
supinator has little interest for us. All that we will say of
it is that it goes from the external part of the inferior ex-
tremity of the humerus to the superior part of the radius ;
and that it is, in carnivora, the essential agent in the pro-
duction of the movement of supination.

Extensor Communis Digitorum (Fig. 73, 9, 10, n ;
Fig. 74, 10, II, 12). — Also named in veterinary anatomy
the anterior extensor of the phalanges, this muscle is situated
external to and behind the anterior extensor of the meta-
carpus already described.

In the human being, the common extensor of the fingers
springs, in its superior part, from the bottom of a depression,
situated on the outer side of and behind the elbow, and limited
in front by the muscular prominence which the long supinator
and the first radial extensor form at that level. At the
bottom of this hollow or fossette is found the epicondyle,
which gives origin, amongst other muscles, to the common

12 — 2

I, Mastoido-hu-
meralis ; 2, pecto-
ral is major ; 3,
deltoid ; 4, brachi-
als anticus ; 5,
triceps ; 6, tri-
ceps, external
head ; 7, olecra-
non ; 8, radial ex-
tensors (anterioi
extensor of the
metacarpus) ; 9,
insertion of the
tendon of the anterior ex-
tensor of the metacarpus
to the tubercle of the supe-
rior extremity of the prin-
cipal metacarpal; 10, ir,
extensor communis digi-
torum (10, proper extensor
of the inner digits; 11,
common extensor of the
two digits) ; 12, tendon of
the common extensor of
the two digits; 13, band
of reinforcement from the
suspensory ligament of the fetlock ; 14, external tuberosity of the superior
extremity of the radius; 15, extensor minimi digiti (proper extensor
of the external digit) ; 16, tendon of the proper extensor of the external
digit ; 17, posterior ulnar (external ffexor of the metacarpus) ; 18, pisiform ;
19, extensor ossis metacarpi pollicis and extensor primi internodii poUicis
(oblique extensor of the metacarpus) ; 20, ulnar portion of the deep flexor
of the toes; 21, tendon of the superficial flexor of the toes (superficial
flexor of the phalanges) ; 22, tendon of the deep flexor of the toes (deep
flexor of the phalanges) ; 23, suspensory ligament of the fetlock.

Fig. 74. — Myology of the Ox : Left An-
terior Limb, External Aspect.

MYOLOGY i8i

extensor of the fingers. It is necessary to add that it is most
prominently visible during supination, and that it tends to
be effaced during pronation.

An analogous arrangement is met with in animals. But
the muscular prominence is formed by the united radial
extensors, and the fossette, because of the permanent pro-
nation of the forearm, is scarcely recognisable. Likewise,
with regard to the dog, we may say that it does not exist,
on account of the prominence which the epicondyle forms
in that animal (Fig. 73, 7).

In connection with this prominence of the epicondyle,
it is interesting to add that this detail recalls the relief
which the same process produces on the external aspect of
the human elbow when the forearm is flexed on the arm.
We know that, in this case, the epicondyle is exposed,,
because the muscles which mask it in supination (long supi-
nator and long radial extensor) are displaced and set it free
during flexion. But, in the dog, as in other quadrupeds
besides, the forearm is, in the normal state, flexed on the
arm ; the latter being oblique downwards and backwards,
and the former being vertical. Further, the epicondyle is
well developed.

The muscle with which we are now occupied, long and
vertical in direction, arises from the inferior part of the
external border of the humerus (there it is covered by
the anterior extensor of the metacarpus, from which
it is freed a little lower down) and from the external
and superior tuberosity of the radius. In the carnivora,
it arises from the epicondyle. Its fleshy body is fusiform
in shape, becomes tendinous in the lower half of the fore-
arm, and then divides into a number of slips, varying in
number according to the species ; this division is correlated
to that of the hand — that is to say, with the number of the
digits. Before reaching this latter, the common extensor
of the digits passes through the most external groove on
the anterior surface of the inferior extremity of the
radius.

In the cat and the dog, the four tendons which result
from the division of the principal tendon go to the four last

I , Mastoido - humeral ; 2,
pectoralis major; 3, deltoid;
4, brachialis anticus; 5, tri-
ceps, long head ; 6, triceps,
external head ; 7, olecranon ;

8, radial extensors (anterior
extensor of the metacarpus

9, insertion of the tendon of
the anterior extensor of the
metacarpus into the tubercle
of the superior extremity of
the principal metacarpal; 10,
extensor communis digi-
torum (anterior extensor of
the phalanges); 11, tendon
of the anterior extensor of the
phalanges ; 12, reinforcing
band arising from the suspen-
sory ligament of the fetlock ;
13, external tuberosity of the
superior extremity of the
radius ; 14, extensor minimi
digiti (lateral extensor of the
phalanges) ; 15, tendon of the
lateral extensor of the phalanges ; 16, fibrous band which this latter
receives from the tendon of the anterior extensor of the phalanges ; 17,
fibrous band which the same tendon receives from the carpal region ;
18, posterior ulnar (external flexor of the metacarpus) ; 19, pisiform ;
20, extensor ossis metacarpi poUicis and extensor primi internodii pollicis
(oblique flexor of the metacarpus) ; 21, ulnar portion of the deep flexor of
the digits ; 22, flexor digitorum profundus ; 23, 23, tendon of the flexor
digitorum sublimis (superficial flexor of the phalanges) ; 24, 24, tendon
of the flexor digitorum profundus (deep flexor of the phalanges) ; 25, sesa-
moid prominence ; 26, suspensory ligament of the fetlock ; 27, external
rudimentary metacarpal.

Fig. 75. — Myology of the Horse:
Left Anterior Limb, External
Aspect.

MYOLOGY 183

digits, and each of them is inserted, as in the human species,
to the second and third phalanges.

In the pig, the anterior extensor of the phalanges is rather
complicated in its arrangement. Its fleshy body is divided
into four bundles terminated by tendons, which in turn
divide and join certain digits ; whence the special names
given to each of these fasciculi, commencing with the most
internal, of : proper extensor of the great inner toe ; common
extensor of the two inner toes ; common extensor of the two
outer toes ; and proper extensor of the great outer toe.

In the ox, the same muscle is divided into two bundles :
the internal proceeds to the internal toe, the external is
common to the two toes.

In the horse, the tendon of the anterior extensor of the
phalanges is divided into two parts of unequal bulk. The
smaller of these tendinous slips, which is the more external,
unites at the level of the superior part of the metacarpus
with the tendon of the muscle which we are about to
study in the following paragraph (Fig. 75, 16). The larger,
after having reached the anterior surface of the digit, is
attached to the anterior aspect of the first and second
phalanges, and then forms a terminal expansion which is
inserted into the pyramidal eminence of the third.

At the level of the first phalanx this tendon receives on
each of its lateral aspects a strengthening band, which
proceeds from the terminal extremity of the suspensory
ligament of the fetlock,"^ and crosses obliquely downwards
and forwards over the surface of the first phalanx to join
the extensor tendon (Fig. 75, 12).

A similar arrangement is found in the ox.
This band is noticeable under the skin which covers the
lateral aspects of the ham.

As the name indicates, this muscle extends the phalanges,
one upon the other. It also contributes to the extension
of the hand, as a whole, on the forearm.

Extensor Minimi Digiti (Fig. 73, 10 ; Fig. 74, 15, 16 ;
Fig. 75, 14, 15). — ^This muscle, the lateral extensor of the
phalanges of veterinary anatomy, situated on the external

* See p. 200 or a description of this ligament.

i84 THE ARTISTIC ANATOMY OF ANIMALS

surface of the forearm., behind the common extensor
of the digits, arises, as a rule, from the epicondyle
(dog, cat), or from the external surface of the superior
extremitj' of the radius (horse). The tendon succeeding
to the fleshy body appears towards the lower third
of the forearm, and at the level of the wrist lies in a
groove analogous to that which in man is hollowed out
for the passage of the corresponding tendon at the level
of the inferior radio-ulnar articulation. This groove cor-
responds to the same articulation in animals in which the
ulna is well developed, such as the dog and the cat ; but
it belongs to the radius when the inferior extremity of the
ulna does not exist — for example, in the horse. Indeed,
in this animal the groove in question is found on the ex-
ternal surface of the carpal extremity of the radius.

In the dog, the tendon is divided into three parts, which,
crossing obliquely the tendons of the common extensor of
the digits, pass to the three external digits, to be inserted
by blending with the corresponding tendons of the latter
into the third phalanges of those digits.

Thus is explained the name of common extensor of the three
external digits which is sometimes given to this muscle.

In the cat, there is a fourth tendon, which passes to the
index-finger, so that the name common extensor of the four
external digits is in this case legitimate, and the lateral ex-
tensor of the phalanges is also a common extensor, as is
the anterior extensor of the phalanges, or common extensor
of the digits.

In the pig, the tendon, which is single, is inserted into
the external digit, for which reason it has received the
name of the proper extensor of the small external digit. This
muscle is, then, really the homologue of that which exists
in the human species.

In the ox, it is called the proper extensor of the external
digit ; it is as thick as the common extensor.

Finally, in the horse, the muscle is little developed. Its
fleshy body, thin and flattened from before backwards,
becomes distinctly visible only below the middle of the
forearm. Above, it is enclosed in a limited space, bounded

MYOLOGY 185

in front by the common extensor of the digits, and behind
by the posterior uhiar ; there these two muscles approach
each other so closely that from the point of view of external
form they seem to be nearly in contact.

The tendon, after receiving the small fasciculus from the
common extensor (Fig. 75, 16), as well as a fibrous band
emanating from the external surface of the carpus (Fig. 75,
17), is situated at the external side of the tendon of the
anterior extensor of the phalanges, and is inserted into the
anterior surface of the superior extremity of the first
phalanx.

This muscle extends the digit or digits into which it is
inserted. It also assists in the movement of extension of
the hand as a whole.

Posterior Ulnar {Extensor carpi ulnaris) (Fig. 73, 11 ;
Fig. 74, 17 ; Fig. 75, 18). — Designated by veterinary
anatomists as the external flexor of the metacarpus,'^ or
external cubital, this muscle is situated in the posterior region
of the external surface of the forearm, behind the lateral
extensor of the phalanges.

It arises from the epicondyle ; its fleshy body, thick but
flattened, is directed vertically towards the carpus, and its
tendon is inserted into the external part of the superior
extremity of the metacarpus, after having given off a
fibrous band, which takes its attachment on the pisiform.

It is inserted, in the cat and the dog, into the superior
extremity of the fifth metacarpal ; in the pig to the external
metacarpal ; in the ox to the external side of the canon-
bone ; in the horse to the superior extremity of the external
rudimentary metacarpal.

This muscle flexes the hand on the forearm, and in animals
in which the radio-carpal articulation permits, by its
formation, it inclines the hand slightly onwards — that is,
abducts it.

Anconeus (Fig. 72, 17 ; Fig. y-^, 13). — We have already
stated (p. 174) that the anconeus is included with the triceps

* Certain authors give it the name of ulnar extensor of the wrist. It is true
that in the human being this is its action ; but in quadrupeds, owing to its
insertion into the pisiform, it draws the hand into the position of flexion.

i86 THE ARTISTIC ANATOMY OF ANIMALS

brachialis in zoological anatomy, and that veterinary
anatomists give it the name of small extensor of the fore-
arm.'^

In the dog it recalls, as to position, the human anconeus,
but with this difference — that, in the latter, the anconeus,
triangular in outline, has one of its angles turned outwards
(the epicondyloid attachment) and one of its sides turned
towards the olecranon. Here it is entirely the opposite.
The anconeus, similarly triangular, is broader externally.
At this level it takes its origin from the external border of
the humerus, the epicondyle, and the external lateral liga-
ment of the articulation of the elbow ; thence its fibres
converge towards the external surface of the olecranon, to
be there inserted.

It is in relation, anteriorly and inferiorly, with the posterior
ulnar muscle. It is covered superiorly by the external head
of the triceps. In the cat the disposition of the anconeus
is analogous. But in the other quadrupeds with which we
are here concerned it is completely covered by the ex-
ternal head of the triceps. It really participates in the
formation of the triceps ; and seeing that it takes origin from
the posterior surface of the humerus at the margin of the
olecranon fossa (Fig. 72), and proceeds thence towards the
olecranon to be inserted, we can understand why veterinary
anatomists have connected its study with that of the
posterior muscular mass of the arm.

This muscle is an extensor of the forearm on the arm.

We proceed now to inquire what the deep muscles of the
posterior region of the human forearm become in quadru-
peds : the long abductor of the thumb, the short extensor
of the thumb, the long extensor of the thumb, the proper
extensor of the index. We know that in every instance
these muscles, which are deeply seated at their origin,
become superficial afterwards.

In quadrupeds, on account of the position in which the
forearm is placed — viz., pronation — the corresponding
muscles occupy the anterior aspect of this region.

Long- Abductor of the Thumb {Extensor ossis mctacarpi

* It is also called by some authors, the small anconeus.

MYOLOGY 187

poinds) and Short Extensor of the Thumb {Extensor primi
internodii pollicis) (Fig. 73, 14 ; Fig. 74, 19 ; Fig. 75, 20). —
United one to the other in man, blended in quadrupeds,
they form in the latter the muscles to which veterinary
anatomists give the name of oblique extensor of the meta-
carpus.

This muscle arises from the median portion of the skeleton
of the forearm. There it is covered by the common extensor
of the digits and that of the small digit (anterior extensor
and lateral extensor of the phalanges). Then, at the in-
ternal border of the first of these muscles, it becomes super-
ficial, passes downwards and inwards, crosses superficially
the anterior extensor of the metacarpus, reaches the inferior
extremity of the radius, and becomes lodged in the most
internal of the grooves situated on the anterior surface
of this extremity, passes on the internal side of the carpus,
and is inserted into the superior extremity of the most
interna] metacarpal — that is, to the first metacarpal, or meta-
carpal of the thumb — in the dog and cat ; to the internal
rudimentary metacarpal in the horse.

It is an extensor of the metacarpal into which it is in-
serted ; but as, if we recall the extreme examples given
above, in the dog the first metacarpal is not very mobile,
and in the horse the internal rudimentary metacarpal is
absolutely fixed to the bone which it accompanies, it is
more exact to add that this muscle is principally an extensor
of the metacarpus as a whole.

And yet, in the cat and the dog, it is also able to adduct
the first metacarpal bone. It must be understood that this
movement would be abduction, if the hand could be placed
in the position of complete supination, as in the human
species.

Long Extensor of the Thumb {Extensor secundi internodii
pollicis) a.nd Proper Extensor of the Index {Extensor indicts).
— These two muscles are blended together by their fleshy
bodies, so that the single name of proper extensor of the thumb
and index is preferable. This muscle is but of slight impor-
tance from our point of view, for it is extremely atrophied,
and so much the more as the number of the digits is lessened.

i88 THE ARTISTIC ANATOMY OF ANIMALS

It arises, as the preceding, from the skeleton of the fore-
arm, and there it is deeply placed. Below, towards the
carpus, its tendinous part becomes superficial, to end in the
following manner :

In the carnivora, the tendon divides into two very slender
parts, which are inserted into the thumb and the index.
In the pig, the tendon is blended with that of the common
extensor of the internal digits. Finally, in the ox and the
horse, it is sometimes regarded as being blended with the
common or anterior extensor of the phalanges. But to us it
appears more rational to say that it does not exist, which,
moreover, is explained by the digital simplification of the
hand.

Internal and Posterior Region

Pronator Teres (Fig. 76, 8). — This muscle, as may easily
be understood, undergoes, as do the supinators, a degree
of degeneration in proportion to the loss of mobility of the
radius on the ulna. In animals in which the bones of the
forearm are not fused it exists ; in those, on the other
hand, in which this segment has become simply a sup-
porting column, it is not developed — at least, in a normal
manner.

It is, consequently, found best marked in the dog and
the cat.

Forming, as in man, the internal limit of the hollow of the
elbow, the pronator teres has a disposition analogous to that
which characterizes the corresponding muscle in the human
species. It arises from the epitrochlea (internal condyle),
proceeds downwards and outwards, and is inserted into the
middle portion of the body of the radius.

It is into the hollow in front of the elbow, which this
muscle contributes to limit, that the biceps and the brachialis
anticus dip.

In the pig and the ox it is atrophied.

In the horse it does not exist. We may, however,
sometimes find it, but in an abnormal form. We were
able to demonstrate its presence in the form of a fleshy

MYOLOGY 189

tongue situated on the internal side of the elbow (Fig. y^)
m a horse which we dissected many years ago in the labora-
tory of the School of Fine Arts. Moreover— and the fact
seemed to us an interesting one — the forearm to which the
muscle belonged had an ulna of relatively considerable
development (Figs. 79 and 80).*

This muscle is a pronator.

Flexor Carpi Radialis (Fig. 76, 10 ; Fig. yj, 7). —
Called by veterinary anatomists the internal flexor of the
metacarpus, this muscle, which is found on the internal
aspect of the forearm, is situated behind the pronator
teres when this muscle exists, whilst in the animals which
are deprived of the latter the flexor carpi radialis has in
front of it the internal border of the radius, which separates
it from the anterior extensor of the metacarpus.

It is necessary to add that the flexor carpi radialis is
similarly separated from the anterior extensor of the meta-
carpus by the internal border of the radius in animals
in which the pronator teres exists, but then only in that part
of the forearm which is situated below this latter.

The flexor carpi radialis arises from the epitrochlea. Its
fleshy body, fusiform in shape, descends vertically, and
terminates in a tendon on the posterior surface of the
bases of the second and third metacarpals in the dog and
the cat, on the metacarpal of the large internal digit in
the pig, on the internal side of the metacarpus in the ox,
and on the superior extremity of the internal rudimentary
metacarpal in the horse.

We see clearly, in this latter, a superficial vein which, in
the shape of a strong cord, passes along the anterior border
of the flexor carpi radiahs ; it is the subcutaneous median
or internal vein, which, forming the continuation of the
internal metacarpal vein, joins the venous system of the
arm, after having crossed obhquely the corresponding part
of the radius.

Palmaris Longus. — ^This muscle, which exists distinctly in

* Edouard Cuyer, ' Abnormal Length of the Ulna and Presence of a
Pronator Teres Muscle in a Horse' {Bulletin de la Society d'Anthrnpologie,
Paris, 1887).

igo THE ARTISTIC ANATOMY OF ANIMALS

some animals, but whose absence is far from being rare in
the human species, is not developed as a distinct muscle in
any of the domestic quadrupeds.

Fig. 76. — Myology of the Dog : Left Anterior Limb, Internal Aspect.

I, Biceps ; 2, long extensor of the forearm (supplementary or acessory
muscle of the great dorsal) ; 3, triceps, long head ; 4, triceps, internal
head ; 5, olecranon ; 6, epitrochlea (internal condyle) ; 7, radial extensors
(anterior extensor of the metacarpus) ; 8, pronator teres ; 9, radius ; 10,
flexor carpi radialis (internal flexor of the metacarpus) ; 11, anterior ulnar
(oblique flexor of the metacarpus) ; 12, superficial flexor of the digits ;
13, deep flexor of the digits ; 14, flexor longus pollicis (radial fasciculus
of the deep flexor of the digits) ; 15, pisiform bone.

MYOLOGY 191

And yet some authors announce its presence in the
dog, and describe it as becoming detached, in the form
of a cyhndrical bundle, from the anterior surface of the
fleshy mass of the deep flexor of the digits (see p. ig6)
to proceed then by a tendon which divides into two parts,
to terminate in the palm of the hand, where it blends
with the tendons of the superficial flexor, which are destined
for the third and fourth digits.

These authors give to this muscle the name of palmaris
longus, and attribute to it the action of flexing the hand.

Anterior Ulnar {Flexor carpi ulnaris) (Fig, y-^, 16 ; Fig.
76, II ; Fig. yy, 8). — Called by veterinary anatomists the
oblique flexor of the metacarpus, or internal ulnar, this
muscle occupies the internal part of the posterior aspect of
the forearm in the ox and the horse, while in the dog it
occupies rather the external part.

This difference arises from the fact that in this latter, as
in man, the anterior ulnar is separated from the flexor carpi
radialis by an interval in which we see, on the internal aspect
of the forearm, just at the level of the elbow, the flexors of
the digits. This interval is so much the wider as there is
no palmaris muscle to subdivide its extent (Fig. 81). In
the horse, the interval in question does not exist. In this
animal, indeed, the anterior ulnar is in contact with the
radial flexor, so that this muscle can occupy only a region
belonging rather to the internal surface of the forearm
(Fig. 82).

In the dog the anterior ulnar is in contact with the pos-
terior ulnar. This relation recalls that which is found in man,
where the two muscles are merely separated by the crest of
the ulna (Fig, 81). But in the horse, in which the anterior
ulnar has, so to speak, slid towards the internal aspect,
this muscle is separated above from the posterior ulnar,
and it is in the interval separating these two muscles that
we are able to perceive, but this time at the back of the
forearm, the muscular mass of the flexors of the digits
(Fig. 82).

The anterior ulnar arises above from the epitrochlea and
the olecranon ; thence it is directed towards the carpus.

192 THE ARTISTIC ANATOMY OF ANIMALS

E^.C

Fig. yj, — Myology of the Horse : Anterior Limb,

Internal Aspect.

Left Side,

I . Long extensor of the forearm (supplementary or accessory muscle of
the latissimus dorsi) ; 2, radialis muscles (anterior extensor of the meta-
carpus) ; 3, tendons of extensor ossis metacarpi poUicis and extensor
primi internodii pollicis united (oblique extensor of the metacarpus);
4, tendon of extensor communis digitorum (anterior extensor of the
phalanges) ; 5, strengthening band from the suspensory ligament of the
fetlock ; 6, internal surface of the radius ; 7, flexor carpi radialis (internal
flexor of the metacarpus) ; 8, anterior ulnar (oblique flexor of the meta-
carpus); 9, pisilorm bone; 10, 10, tendon of the superficial flexor of the
digits (superficial flexor of the phalanges) ; 11, 11, tendon of the deep
flexor of the digits (deep flexor of the phalanges) ; 12, sesamoid prominence;
13, suspensory ligament of the fetlock; 14. internal rudimentary meta-
carpal.

MYOLOGY 193

to be inserted into the pisiform bone. It proceeds there-
fore from the inner side of the elbow to the outer side
of the upper part of the hand ; it consequently crosses the
posterior surface of the forearm obliquely. This is why, as
we have pointed out above, it receives the name of the
oblique flexor of the metacarpus.

It is not unprofitable to recall in this connection that
there is an internal flexor of the metacarpus, which is the
flexor carpi radialis ; and an external flexor of the meta-
carpus, which is the posterior ulnar (in human anatomy,
extensor carpi ulnaris). It is between these two muscles
that we find the oblique flexor— the anterior ulnar which we
have just been studying.

This muscle flexes the hand on the forearm.
Superficial Flexor of the Digits [Flexor digitorum sub-
limis) (Fig. 76, 12 ; Fig. jy, 10, 10). — This muscle arises from
the epitrochlea ; thence it passes towards the hand, becomes
tendinous, passes in a groove on the posterior aspect of the
carpus, and terminates on the palmar surface of the phalanges
in furnishing a number of tendons proportioned to the digital
division of the hand. Whatever the number, to which we
will again refer, each tendon is attached to the second phalanx,
after bifurcating at the level of the first, so as to form a sort
of ring, destined to give passage to the corresponding tendon
of the deep flexor. This ring and this passage have gained
for the muscle the name of perforated flexor.

In the dog and the cat the principal tendon is divided
into four parts, which go to the four last digits.

In the ox it is divided into two parts only ; as, more-
over, in the pig, whose superficial flexor is destined for
the two large digits only, the lateral digits receiving no
part of it.

Finally, in the horse the tendon is single.
We have previously pointed out that in the carnivora
this muscle is visible on the internal and posterior aspects
of the forearm, in the interval which is limited in front by
the flexor carpi radialis and behind and outside by the
.anterior ulnar.

Certain details are still to be added to the description of

13

194 THE ARTISTIC ANATOMY OF ANIMALS

this muscle. We will enter on an analysis of them after we
have given some indications relative to the following muscle :
Deep Flexor of the Digits {Flexor digitorum profundus)
(Fig. 75, 21, 22 ; Fig. 76, 12 ; Fig. 77, 11, 11). — This muscle
is covered by the superficial flexor. It arises from the
epitrochlea, from the radius, and from the ulna, either from
the olecranon process — as in the ox, pig, and horse — or from

Fig. 7S. — Left Anterior Limb of the Horse : Internal Aspect.

I, Internal flexor of the metacarpus or great palmar ; 2, inferior part
of the biceps ; 3, inferior part of the brachialis anticus ; 4, internal lateral
ligament of the elbow ; 5, pronato teres muscle.

almost the whole extent of the shaft of the same bone, as in
the cat and dog.

The radial fasciculus represents in the domestic quadru-
peds the long proper flexor muscle of the thumb in man.
For this reason we shall describe the muscle afresh in the
following paragraph :

The fleshy bundles of which we have just spoken termi-
nate in a tendon which afterwards divides into slips, the

MYOLOGY 195

number of which is in proportion to the digital division of
the hand. These sHps then pass through the sHt or button-
hole in the tendon of the superficial flexor, and proceed
to terminate on the third phalanx ; hence the name of
perforating, which is also given to the deep flexor of the
digits.

In the dog and the cat the tendon is divided into five
portions, each of which proceeds to one of the digits. The
internal tendon, which is destined for the thumb, termi-
nates on the second phalanx of this digit.

In the pig the tendon divides into four tendons destined
for the four digits.

In the ox there are but two tendons.

In the horse the tendon is single.

As their names indicate, these muscles, both superficial
and deep, flex the digits. In addition to this, they flex
the hand on the forearm.

We mentioned above that certain details relative to
the superficial flexor must be analyzed in a special way.
We now add that this should also be done with regard to
the deep flexor. The point in question is the arrangement
which the tendons of these muscles present at the level of
the palmar region of the hand.

It is easy, in the case of the dog or the cat, to picture to
one's self this arrangement, especially if we recollect that
which exists in the human species. The tendons of the
flexors are placed on a kind of muscular bed formed by the
union of the muscles of the region, but, moreover, from the
point of view of external form, these tendons are not of very
great importance.

But in the ox and the horse it is quite otherwise. From
the simplification of the skeleton of the hand, and the
reduction of the number of movements which the bones
that form it are able to execute, there naturally results a
diminution of its muscular apparatus. Apart from the
existence of muscular vestiges of but little importance, we
can say that, in reality, the hand does not possess any
muscles. On its palmar aspect are found only the tendons
of the flexors of the digits, and as these tendons are

13—2

196 THE ARTISTIC ANATOMY OF ANIMALS

large, and the hand long, they give origin to external
forms which it is necessary to examine.

In the horse, which we take as a type, the tendons
of the flexors, after being retained in position at the carpus
by a fibrous band, the carpal sheath, which recalls the anterior
annular ligament of the human carpus, and having passed

9a^

_i

Fig. 79. — Left Anterior Limb
OF THE Horse : External
Aspect.

I, Ulna of abnormal length.

Fig. 80. — Left Anterior Limb
OF THE Horse : External

Aspect.

I, Normal ulna.

this region, descend vertically, remaining separated from
the posterior surface of the metacarpus, so that the skin
sinks slightly on the lateral parts in front of the thick cord
which these tendons form. This cord is known by the name
of tendon.

The flexors then reach the fetlock, and occupy the groove

MYOLOGY 197

formed by the peculiar arrangement of the two large sesa-
moid bones. They are retained in position at this level by
a fibrous structure, which forms the metacarpo-phab.ngeal
sheath. They then reach the phalanges, being directed
obliquely downwards and forwards, as, moreover, the latter
are also inclined. Then the tendon of the superficial flexor
divides into two slips, which are inserted into the second
phalanx, between which slips passes the tendon of the deep
flexor, which in its turn goes to be inserted, in the form of an
expansion, into the semilunar crest, by which the inferior
surface of the third phalanx is divided into two parts.*

The part which these tendons play is of great importance
in the large quadrupeds.

These tendons, in fact, in addition to the action deter-
mined by the contraction of the fleshy fibres to which
they succeed, maintain the angle formed by the canon-
bone and the phalangeal portion of the hand, and prevent
its effacement under the weight of the body during
the time of standing. Their strong development, and the
position they occupy, make this understood, without it
being necessary to insist on it further.

We mentioned above that the ' tendon ' descends verti-
cally from the carpus towards the fetlocks. This is as it
should be. But, in some horses, it is oblique downwards
and backwards, so that the canon, instead of being of equal
depth from before backwards in its whole length, is a little
narrower in its upper part.

This results from the fact that the tendons of the flexors,
too firmly bound by the carpal sheath, gradually separate
as they pass from the metacarpus, going to join the fet-
lock ; hence the obliquity pointed out above. This abnor-
mality producing a deleterious result, in the sense that the
tendinous apparatus acts with less strength as an organ of
support, it constitutes a defect of conformation which is
expressed by saying that the tendon has ' failed.'

Long Proper Flexor of the Thumb {Flexor longus

* See, as regards this crest, in the paragraph relative to the hoof of the
solipeds, the ligures which represent the third phalanx, viewed on its
inferior surface (Figs. loi and 102, p. 258).

198 THE ARTISTIC ANATOMY OF ANIMALS

poinds) (Fig. 76, 14). — As wc have already pointed out,
this muscle is represented in quadrupeds by the radial
bundle of the deep flexor of the digits, so that the two
muscles are in reality blended the one to the other. This
union is sometimes found, but only as an abnormality, in
the human species. We have met some examples of this
in the course of our dissections.

Pronator Quadratus. — This muscle conforms to the general
law which we have already pointed out in connection with
those which have for their action the rotation of the radius

EJiC

Fig. 81. — Diagram of the Pos-
terior Part of a Trans-
verse Section passing
through the middle of
THE Left Fore-limb of the
Dog : Surface of the
Inferior Segment of the
Section.

. I, Radius; 2, ulna; 3, pos-
terior ulnar ; 4, anterior ulnar ;
5, great palmar (flexor carpi
radidlis) ; 6. flexors of the digits.

Ei C.

Fig. 82. — Diagram of a Hori-
zontal Section of the
Middle of the Forearm of
THE Left Leg of the Horse :
Surface of the Inferior
Segment of the Section.

I, Radius ; 2, ulna; 3, posterior
ulnar ; 4, anterior ulnar ; 5, great
palmar (flexor carpi radialis) ; 6,
flexors of the digits.

around the ulna. We remember, indeed, that when the
bones of the forearm are fused with one another, the muscles
which are destined to produce a mobility which has then
become impossible disappear at the same blow.

For this cause we do not find the square pronator in
either the ox or the horse, but can demonstrate its presence
in the dog and the cat.

It is very deeply situated. This is why, and also on
account of the plan which we have traced lor ourselves, we
will simply say that it is situated on the postero-internal

MYOLOGY 199

aspect of the skeleton of the forearm, and that it extends
from the ulna to the radius.

It seems to us, however, sufficiently interesting to add
that, instead of occupying, as in the human species, the
inferior fourth of the two bones, it extends, particularly in
the dog, over their whole length, with the exception of their
superior and inferior extremities.

Muscles of the Hand

We will first recall that, in man, the palm of the hand
is divided into three regions : a median palmar region,
which is occupied by the tendons of the flexors of the
digits, the lumbricales, and, deeply, by the interosseous
muscles ; an external region, or thenar eminence, formed
by the muscles destined for the movements of the thumb ;
an internal region, or hypothenar eminence, which contains
the muscles proper to the small digit and the palmar
cutaneous muscle.

These muscles are found, more or less developed, in the
dog and the cat.

In the ox and the horse we meet with no vestige of the
muscles of the thenar or hypothenar eminences. Never-
theless, in these animals we find the muscles which belong
to the central region of the palm. We refer to the
lumbricales and the interosseous.

Although this fact has no relation to the object of our
study, it appears to us interesting to announce that there
are traces of the lumbricales found in the solipeds.
These muscles are represented by two fleshy bundles,
situated one on each side of the tendon of the deep flexor,
above the ring of the tendon of the superficial flexor.
These small muscles are continued as slender tendons,
which become lost in the fibrous tissue of the spur, which
is the horny process situated at the posterior part of the
fetlock, and which is covered by the hairs, more or less
abundant, which constitute the wisp.

As for the interosseous muscles, they are represented by
the suspensory ligament of the fetlock, and by two other

200 THE ARTISTIC ANATOMY OF ANIMALS

small muscles, tendinous throughout, which are situated
between the principal metacarpal and the rudimentary ones.

The suspensory ligament of the fetlock is considered an
interosseous muscle, on account of the red fleshy striations
which it contains, and from certain relations which it forms
with the tendon of the common extensor of the digits or
anterior extensor of the phalanges. This ligament (Fig. 75,
26 ; Fig. 77, 13), which plays an important part in the
standing position as a support of the foot, is a fibrous
band situated between the tendons of the flexors of the
digits and the principal metacarpal. It arises above, from
the second row of the carpals, descends towards the fetlock,
where it divides into two branches, which are inserted into
the large sesamoid bones. At the same level, this ligament
gives off two fibrous bands which, passing downwards and
forwards, join the tendon of the anterior extensor of the
phalanges, blending with it, after having each crossed one
of the lateral aspects of the pastern. We have already
referred to these bands (p. 183).

It is with these latter that are blended the long and
slender tendons which form in a great measure the two
other interosseous muscles previously described.

A ligament of the same kind is found in the ox
(Fig. 74, 23).

MUSCLES OF THE POSTERIOR LIMBS

Muscles of the Pelvis

The muscles which specially interest us in this region,
because of their superficial position, are the gluteus maximus
and the gluteus medius. As for the gluteus minimus, it is
deeply situated, and more or less sharply marked off from
the second of the preceding muscles.

Inasmuch as the gluteus medius is more simple in arrange-
ment than the maximus, and will aid us in arranging our
ideas in connection with the latter, it is with the study of it
that we will commence.

Gluteus Medius (Fig. 68, 29 ; Fig. 69, 26 ; Fig. 70. 35).

MYOLOGY 201

— This muscle, as in man, occupies the external iliac fossa.
But this latter being directed differently in the digitigrades
and the ungulates, as we have pointed out in the section
on osteology (see pp. 91 and 99), the muscle in question
has consequently not the same direction in the two groups
of animals, being turned outwards in the first, and upwards
in the second.

It is the thickest of the glutei, and gives to the region
which it occupies a rounded form.

From the iliac fossa from which it arises the fleshy fibres
are directed towards the femur, to be inserted into the
great trochanter. It is covered by an aponeurosis, and
in part by the great gluteal. It completely covers the
small gluteal, which veterinary anatomists designate by
the name of the deep gluteal.

In the carnivora it does not pass in front of the iliac
crest, but, in the ox, and more particularly in the horse, it is
prolonged anteriorly, and thus covers, to a certain extent,
the muscles of the common mass.

When it contracts, taking its fixed point at the pelvis,
the gluteus medius extends the thigh, which it is also able
to abduct. If, on the other hand, its fixed point is on
the femur, it acts on the trunk, which it raises, producing
oscillating movements of the pelvis. It contributes in
this way to the action of rearing. We also see it dis-
tinctly appear by the prominence which it produces in
the dog, which, according to the time-honoured phrase.
fait le beau.

Gluteus Maximus (Fig. 68, 28 ; Fig. 69, 25 ; Fig. 70,
33' 34)- — The great gluteal muscle, further designated in
veterinary anatomy the superficial gluteal, is proportionately
less developed in quadrupeds than in man. Indeed, in the
latter, where it is of very great thickness, its volume is
due to the important function which it fulfils in maintaining
the biped attitude.

In quadrupeds it contributes to form the superficial part
of the crupper and the external surface of the thigh. It is
divided into two parts : one anterior, the other posterior.

With regard to this latter, it will be necessar}^ to indicate

202 THE ARTISTIC ANATOMY OF ANIMALS

how it has been sometimes regarded, and to what portion
of the muscular system in man it corresponds. But we
believe that it is better to see beforehand, without any pre-
conceived idea, how these two parts are arranged.

In the dog, the anterior portion of the gluteus maximus
arises from the sacrum, while some fibres situated further
forward arise from the surface of the gluteus medius, near the
ihac spine, and from the tensor of the fascia lata with which
these fibres are blended. The posterior portion, united to
the preceding — that is lo say, to those of its fibres which
arise from the sacrum — takes its origin from the lirst
coccygeal vertebra. These two portions are directed
towards the femur, to be inserted into the great trochanter,
and to the external branch of the superior bifurcation of
the linea aspera.

In the cat, the posterior bundle is less definitely blended
with the anterior. By a long and slender tendon which,
behind, turns around the great trochanter, and passes along
the surface of the fascia lata, it proceeds to join the knee-cap.

In the pig, the posterior portion is much more de-
veloped.

In the horse, the anterior portion arises from the internal
iliac spine (posterior in man), from the external iliac spine
(anterior in man), and, between these two osseous points,
from the aponeurosis, which covers the gluteus medius.
Between these two origins the muscle is deeply grooved,
so that the tendency is to divide into two portions, each of
which is directed towards one of the iliac angles. In this
groove the gluteus medius is to be seen.

The fleshy bundles converge, and are directed towards the
external aspect of the femur, to be inserted into the osseous
prominence known as the third trochanter, after passing
beneath the fleshy fibres of the posterior portion. The
latter, which is more considerable than the preceding por-
tion, arises above from the sacral crest, from the aponeurosis
which envelops the coccygeal muscles, from the sacro-
sciatic ligament, and from the tuberosity of the ischium.
From this origin it passes downwards, expands, then,
describing a curve with the convexity behind, it becomes

MYOLOGY 203

narrowed, and proceeds to be inserted by a deep fasciculus
into the third trochanter, to the fascia lata, and, lastly,
to the knee-cap by the inferior part of its tendon.

Above, its posterior border is covered by the semi-ten-
dinosus ; interiorly, the same border is in relation with the
biceps femoris.

In the ox, the two parts of the great gluteal muscle are
blended together.

The long and broad fleshy band which they form
arises in a manner corresponding to that which we have
just indicated in connection with the horse, except that it
has no attachment to the femur. The fascia lata adheres
strongly to its anterior border for a considerable length.
The form of the superior border of the great gluteal muscle
of this animal differs from that of the analogous portion
in the horse. This difference results from the peculiar
aspect which the corresponding region of the pelvis presents,
and from the fact that, in the ox, as the semi-tendinosus
does not cover the portion of the great gluteal which
arises from the tuberosity of the ischium, the attach-
ments of this muscle to the sacro-sciatic ligament are
uncovered.

Its descending portion, as a whole, has a rectilinear form,
and does not form a curve such as we indicated in the case
of the horse.

The anterior portion of the great gluteal flexes the thigh.
As regards the posterior portion, it extends the thigh, and
abducts it.

The action of this latter portion is particularly interesting
as regards the horse, because of the great development of
the muscular mass which this region presents in this animal.
If -the muscle takes its fixed point above, it acts, in the
extension of the thigh during walking, by projecting the
trunk forward during the whole time that the hind-limb to
which it belongs is in contact with the ground. If, on the
contrary, it takes its fixed point below, it makes the pelvis
describe a see-saw movement, upwards and backwards, on
the coxo- femoral articulation, and so contributes to the
action of rearing.

204 THE ARTISTIC ANATOMY OF ANIMALS

Now that we have a knowledge of the disposition of the
great gluteal muscle, the moment has come to inquire what is
the signification of its posterior portion. The action of the
anterior part being clearly comparable to the human great
gluteal, there can be no doubt as regards the homology of
this portion, so we will not insist on it further.

Of the posterior portion it is wholly different, for it is the
homologue of a fleshy bundle annexed to the great gluteal of
man, but which is not developed except as an abnormality-

Indeed, we sometimes find, placed along the inferior
border of the great gluteal, a fleshy fasciculus, separated from
this muscle by a slight interspace. This fasciculus, long and
narrow, takes origin from the summit of the sacrum, or
the coccyx, and goes to partake of the femoral insertions
of the muscle which it accompanies. We further note a
muscle of the same kind, and presenting the same aspect,
w^hich comes from the tuberosity of the ischium. Notwith-
standing the difference which exists, it is this abnormal
fasciculus of man which in the quadrupeds here studied is
considered as constituting the posterior portion of the great
gluteal.

Bourgelat, considering this posterior portion as belonging
to the biceps cruris, to which, it is true, it adheres, forms
of them a muscle which he designates under the name of
the long vastus. The anterior fasciculus of this long vastus
is none other than the posterior portion of the great gluteal
which we have just been studying.

Muscles of the Thigh

These muscles are divided into three regions : posterior,
anterior, and internal.

In a corresponding manner to that which we described
in connection with the arm, the thigh is applied to the side
of the trunk, and is free, more or less, only at the level of
the inferior part.

Further, by reason of this shortening of the femur, the
great gluteal muscle, which is elongated in the ox and the
horse, for example, occupies in part the region corresponding

MYOLOGY 205

to that which in man is occupied by the muscles of the
thigh, which here are reduced in length. In other words,
they are not superposed, as in the liuman species, but
juxtaposed. This is what we will verify further on.

The thigh, as a whole, is flattened from without inwards,
its transverse diameter being less in extent than its antero-
posterior. Its external surface is slightly rounded ; that
is, of course, in quadrupeds with sufficiently well-developed
muscles. Its internal surface is known as the flat of the
thigh.

Muscles of the Posterior Region

It is not unprofitable to recall to mind what muscles
form the superficial layer of this region in the human being.
They are the biceps cruris, semi-tendinosus, and semi-
membranosus. We now proceed to discover their analogues
in quadrupeds.

Biceps Cruris (Fig. 68, 30 ; Fig. 69, 27 ; Fig. 70,
36). — It is this which, according to Bourgelat, forms the
central and posterior portions of the long vastus muscle
which we have mentioned above.

We know that the biceps of man is so named from
the two portions which form its upper part. In domestic
quadrupeds, and also in the majority of the mammals, this
muscle is reduced to a single portion, that which comes from
the pelvis. It is therefore the portion which arises from
the femur which does not exist. This condition is some-
times found as an abnormality in the human species.

The biceps arises from the tuberosity of the ischium ;
hence it is directed, widening as it goes, towards the leg,
where it terminates by an aponeurosis which blends with
the fascia lata and the aponeurosis of the leg, and then pro-
ceeds to be attached to the anterior border or crest of the
tibia. By its inferior portion it hmits externally the pos-
terior region of the knee — the popliteal space.

A fibrous intersection traverses the biceps in its whole
length, with the result that the muscle looks as if formed of
two portions, one of which is situated in front of the other.

2o6 THE ARTISTIC ANATOMY OF ANIMALS

In the dog and the cat it also arises from the sacro-sciatic
ligament. At this level its contour is distinguishable from
that which corresponds to the gluteal muscles, so that we
there iind two prominences one above the other. The
superior is formed by the gluteal muscles ; the inferior cor-
responds to the tuberosity of the ischium. The two pro-
minences are separated by a depression, from which the
biceps emerges. We draw attention to this form, the
character of which is so expressive of energy in the car-
nivora.

In these animals the biceps is inserted, by its anterior
fibres, into the articulation of the knee, while in the rest of
its extent it covers in great measure by its aponeurosis the
external aspect of the leg.

, In the pig, the biceps is but slightly marked off from
the posterior part of the great gluteal. In the ox, the
division between these two muscles is a little more distinct.

In the horse, the sciatic origin of the biceps is covered by
the semi-tendinosus, so that it only becomes free lower
down, to appear in the space limited behind by the semi-
tendinosus, and in front by the posterior part of the gluteus
maximus.

When the biceps contracts, taking its fixed point from
above, it flexes the leg and helps to extend the thigh. If,
on the other hand, it takes its fixed point from below, it
lowers the ischium, makes the pelvis undergo a see-saw
movement, and acts thus in the movement of rearing. It
is sometimes called, on account of one of its actions,
and the position which it occupies, the ' external flexor, or
peroneal muscle of the leg.'

Semi-tendinosus (Fig. 68, 31 ; Fig. 70, -^"j ; Fig. %"], i ;
Fig. 88, I ; Fig. 89, 28). — This muscle forms the contour of
the thigh posteriorly, so that when the latter is viewed from
the side, it is the semi-tendinosus above all that forms the
outline. But, as we shall soon see, it is in this case more
distinct above than below, because of the deviation which it
undergoes in order to occupy by its inferior part the
internal side of the leg.

In the dog, the cat, and the ox, the semi-tendinosus

MYOLOGY 207

arises from the tuberosity of the ischium only, as in the
human species. In the pig, it also takes origin higher up
from the sacro-sciatic ligament and the coccygeal aponeu-
rosis. In the horse, it extends still further, for it is also
attached to the crest of the sacrum.

The indication of these origins is of importance from the
point of view of external form, and to convince ourselves of
this it is sufficient to compare, in the ox and the horse, the
region of the pelvis situated below the root of the tail. In
the ox, whose semi-tendinosus arises from the tuberosity
of the ischium only, this region is depressed, and the cavity
which is formed at this level is limited behind by the tuber-
osity, which we know is very thick and prominent above.
This causes' the superior part of the crupper to be less
oblique than in the horse. This characteristic is more
especially marked in the cow, the bull having this region of
a more rounded form.

In the horse, on account of the semi-tendinosus ascending
to the coccyx, and even to the sacrum, the depression in
question does not exist, and the presence of the tuberosity
of the ischium is only slightly revealed.

Descending from the origin indicated above, and inclining
more and more inwards, the semi-tendinosus proceeds to
blend with the aponeurosis of the leg, to be inserted into
the anterior border of the tibia, after crossing over the
internal surface of the latter. It forms the internal boun-
dary of the popliteal space.

When this muscle contracts, taking its fixed point at the
pelvis, it flexes the leg. If, on the other hand, it takes its
fixed point at the tibia, it makes the pelvis describe a see-
saw movement, and acts accordingly in the movement of
rearing.

It is sometimes named the ' internal or tibial flexor of the
leg,' in opposition to the crural biceps, which, as stated above,
is then the external flexor of the same region.

Semi-membranosus (Fig. 68, 32 ; Fig. 87, 2 ; Fig. 88, 2).
— This muscle, situated on the inner side of the semi-ten-
dinosus, can be seen only when the thigh is regarded on
its posterior aspect.

2oS THE ARTISTIC ANATOMY OF ANIMALS

It is only by reason of the homology of situation with
the corresponding muscle in man that we give the name
under which we are studying it ; indeed, its structure is
different, for it does not present the long, broad, aponeurotic
tendon which, in its superior part, characterizes this muscle
in the human species.

It arises above from the inferior surface of the ischium,
and from the tuberosity of the same bone. In the pig,
and especially in the horse, it passes further upwards, to
arise from the aponeurosis of the coccygeal muscles. So
that if we compare it with that of the ox, which does not
extend beyond the ischium, we find that it is associated
with the semi-tendinosus in determining the difference of
aspect to which we have already called attention in connec-
tion with the region of the pelvis situated below the root of
the tail.

The semi-membranosus is then directed downwards and
forwards, to take its place on the internal surface of the
thigh, where it is partly covered by the gracilis muscle.
It is inserted in the following manner :

In the dog and the cat it is divided into two parts,
anterior and posterior. The first, the more developed, is
attached to the internal surface of the inferior extremity
of the femur ; the second to the internal tuberosity of the
tibia.

The same arrangement occurs in the ox.

In the horse it is inserted into the internal surface of the
internal condyle of the femur.

The semi-membranosus is an extensor of the thigh when
it takes its fixed point at the pelvis ; it is also an adductor
of the lower limb. If it takes its fixed point below it assists
in the action of rearing.

It is now necessary for us, especially as regards the horse,
to add some indications relative to the exterior forms of
the region constituted by the semi-membranosus and semi-
tendinosus. These two muscles form, by their union, a
surface contour, slightly projecting and of elongated form,
which occupies the posterior border of the thigh, the
contour corresponding to the region known as the hutiock, in

MYOLOGY 209

spite of the fact that none of the gluteal muscles take any
part in the structure of this region. But the appearances,
to a certain extent, justify the preservation of this name.
Indeed, because of the groove which separates the gluteal
region of one side from that of the opposite side, and
from the position of the anal orifice in the superior part of
this groove, we may admit the name which, in hippology,
has been given to this part of the thigh.

In addition to the reasons just given, and which are
justified especially by the position occupied by the muscular
mass formed by the union of the two muscles, there is
another which, this time, has a relation to a certain
detail of form. In the superior part of the convexit}^,
which the gluteal region describes in the greater part of its
extent, there is found a more salient point, greatly accentu-
ated in lean animals, due to the presence of the tuberosity
of the ischium ; it is the point or angle of the buttock. At
this level, and near the median line, the semi-membranosus,
not aponeurotic, but fleshy, and even thicker there than
anywhere else, sometimes produces a sharply localized
prominence. And as this prominence is situated on the
outer side of the anal orifice, the resemblance to a small
' buttock ' is still more marked.

In lean horses a deep groove separates the mass formed
by the semi-membranosus and semi-tendinosus from that
of the other muscles of the thigh situated more in front ;
this groove is known by a name which in this case is
remarkably expressive — that of the ' line of poverty.'

If we examine the gluteal region as a whole by looking
at the thigh from the side, we plainly see the graceful
curve produced by the general convexity above indicated.
We return to this point, in order to add that, in its lower
part, this curve alters its character ; that is to say, it
is replaced by a slight concavity. This, which is designated
under the name of the fold of the buttock, is situated close to
the level of articulation of the leg with the thigh-bone.

14

210 THE ARTISTIC ANATOMY OF ANIMALS

Muscles of the Anterior Region.

First we recall that in man the anterior muscles of the
thigh are : the triceps cruris, the tensor of the fascia lata,
and the sartorius.

Triceps Cruris (Fig. 8, 36 ; Fig. 69, 31 ; Fig. 70, 41 ;
Fig. 84, 2 ; Fig. 87, 3 ; Fig. 88, 3). — This muscle, which
occupies the greater part of the space between the pelvis
and the anterior aspect of the femur, consists of three parts :
an external, or vastus externus ; an internal, or vastus in-
temus ; and a median or long portion, or rectus femoris.
This division accordingly recalls that which characterizes
the human triceps cruris. Furthermore, as in the case
of the latter, the vastus externus and the vastus internus
take their origin from the shaft of the femur, while
the long portion arises from the pelvis. The vastus
externus arises from the external lip of the linea aspera
of the femur (or from the external border of the pos-
terior surface of this bone in the ox and the horse, in
which the linea aspera, considerably widened, especially
in the latter, forms a surface), and from the external sur-
face of the shaft of the femur. From this origin its fibres
pass downwards and forwards, to be inserted into the tendon
of the long portion of the muscle and into the patella.

In the dog and the cat the vastus externus is the most
voluminous of the three portions which constitute the
triceps muscle. It is covered by the fascia lata ; but not-
withstanding this, its presence is revealed by a prominence
which occupies the external surface of the thigh, and
surmounts, in the region of the knee, the more slightly
developed one which is produced by the knee-cap.

The vastus internus, situated on the inner surface of the
thigh, takes its origin from the corresponding surface of
the femur, and proceeds towards the patella.

The rectus femoris arises from the iliac bone, above the
cotyloid cavity ; its fleshy body, which is fusiform, and
situated in front of and between the two vasti muscles, is
directed towards the patella, into which it is inserted by
a tendon, which receives the other two portions.

MYOLOGY 211

It is covered in front by the tensor of the fascia lata, and
contributes with the vastus externus to form the upper
prominence of the knee.

The hgamentous fibres, which, as in man, unite the knee-
cap to the tibia, transmit to this latter the action determined
by the contraction of the triceps. This muscle is an exten-
sor of the leg. Furthermore, the rectus femoris, or long
portion, acts as a flexor of the thigh.

Tensor Fascia Lata (Fig. 68, 34, 36 ; Fig. 69, 30, 31 ;
Fig. 70, 40). — This muscle, generally larger in quadrupeds
than in man, is flat and triangular, and occupies the superior
and anterior part of the thigh.

It arises from the anterior iliac spine (inferior in carnivora,
external in the ox and the horse) ; it is prolonged down-
wards by an aponeurosis (fascia lata) which occupies the
external aspect of the thigh, proceeds to be inserted into
the patella and blend with the aponeurosis of the biceps
muscle.

It covers the rectus and vastus externus portions of
the triceps cruris ; it is also in relation with the gluteal
muscles.

The tensor of the fascia lata flexes the thigh, and serves to
raise the lower hmb as a whole.

Sartorius (Fig. 68, 35 ; Fig. 87, 4, 5 ; Fig. 88, 5).—
This muscle, long and flattened, is called by veterinarians
the long adductor of the leg.

Before beginning the study of its position in quadru-
peds, it is necessary to remember that in man, where
the thigh has a form almost conical, the sartorius com-
mences on the anterior face of this latter, and is directed
downwards and inwards to reach the internal surface of
the knee.

But now let us suppose the thigh flattened from without
inwards ; there will evidently result from this a change in
situation with regard to the muscle in question. In fact,
when this supposition is admitted, it is easy to imagine
that in a great part of the extent in which the sartorius
is normally anterior it will become internal. This is why,
these conditions being realized in quadrupeds, we shall

14 — 2

212 THE ARTISTIC ANATOMY OF ANIMALS

find that, in some of them, the sartorius is situated on the
aspect of the thigh which is turned to the side of the
trunk.

In the dog and the cat it arises from the anterior iliac
spine, and from the half of the border of the bone situated
immediately below it ; but the fibres from this second
origin being hidden by the tensor of the fascia lata, on the
inner side of which they are situated, viewing the external
surface of the thigh, the muscle seems to arise from the
iliac spine only.

The sartorius in these animals is divided into two parts,
which, in general, are placed in contact. One of these
fasciculi is anterior ; the other is situated further back. The
first is visible on the anterior border of the thigh, in front
of the tensor of the fascia lata, but below it inclines inwards ;
in its superior part also, a small extent of the internal sur-
face is occupied by it. The second, which, as we have said,
is situated further back, belongs wholly to the inner surface
of the thigh ; it is this portion which arises from the inferior
border of the ilium (this is the homologue of the anterior
border of the human iUac bone).

The two fasciculi then pass towards the knee, being in
relation with the rectus and the vastus internus of the tri-
ceps. The anterior fasciculus is inserted into the patella.
The posterior unites with the tendons of the gracilis (see
below) and semi-tendinosus, and then proceeds to be in-
serted into the superior part of the internal surface of the
tibia.

On account of their different insertions these two parts
receive the names of the patellar sartorius and tibial sartorius
respectively.

In the ox and the horse the sartorius is still more definitely
situated on the internal surface of the thigh. Consisting of
a single fasciculus, representing the tibial sartorius of the
cat and the dog, it arises in the abdominal cavity from the
fascia covering the ihac muscle, then passes under the
crural arch, and terminates, by an aponeurosis which blends
with that of the gracilis, on the inner fibres of the patellar
ligament. In short, the sartorius is of interest to us in the

MYOLOGY 213

carnivora only, and especially on account of its anterior or
patellar fasciculus.

It is an adductor of the leg and a flexor of the thigh.

Muscles of the Internal Region

The iHo-psoas pectineus and the adductors which we study
in man, in connection with the internal aspect of the thigh,
offer little of interest from the point of view of external form
in quadrupeds ; it is for this reason that we will disregard
them.

The gracilis alone merits description.

Gracilis (Fig. ^y, 9 ; Fig. ^S, 6). — Designated in veterinary
anatomy under the name of the short adductor of the leg,
this muscle, expanded in width, occupies the greater part
of the internal surface of the thigh, or flat of the thigh, as
this region is also called. Let us imagine, in man, the
internal surface of the thigh broader, and the internal
rectus more expanded, and we shall have an idea of the
same muscle as it exists in quadrupeds.

The gracilis arises from the ischio-pubic symphysis
and from the neighbouring regions ; thence it is directed
towards the leg to be inserted into the superior part of the
internal surface of the tibia, after being united to the tendons
of the sartorius and semi-tendinosus. We find, accordingly,
at this level, an arrangement which recalls the general ap-
pearance of what in man receives the name of the goose's
foot {pes anserinus).

It is between this muscle and the sartorius, at the superior
part of the internal surface of the thigh, in the region which
recalls the triangle of Scarpa, that we are able, especially in
the cat and the dog, to see the adductor muscles of the
thigh. We also partly see there, in these animals, the
vastus intemus and the rectus of the triceps (see Fig. 87).
The gracilis is an adductor of the thigh.

Muscles of the Leg

We will divide the leg into three regions : anterior,
externa.1, and posterior. With regard to the internal region,

214 THE ARTISTIC ANATOMY OF ANIMALS

there are no muscles which belong exclusively to it ; for it
is in great measure formed by the internal surface of the
tibia, which, as in man, is subcutaneous.

Muscles of the Anterior Region

We first note that in the human species the tibialis
anticus, extensor proprius pollicis, extensor longus digitorum

Fig. 83. — Myology of the Horse : the Anterior Tibial Muscle
(Flexor of the Metatarsus), Left Leg, Anterior View.

I, Femoral trochlea; 2, tibia; 3, tendinous portion of the tibialis
anticus; 4, cuboid branch of same ; 5, 5, its metatarsal branch; 6, fleshy-
portion ; 7, cuneiform branch of its tendon ; 8, metatarsal branch of
the same tendon ; 9, extensor longus digitorum (anterior extensor of
the phalanges turned outwards) ; 10, peroneus brevis (lateral extensor
of the phalanges).

and the peroneous tertius or anticus, form the subcutaneous
layer of this region. We now proceed to study these muscles
in quadrupeds.

Tibialis Anticus (Fig. 83 ; Fig. 84, 6; Fig. 85, 4; Fig. ^y, 10 ;
Fig. 88, 10, 11). — It is further named by veterinarians the
flexor of the metatarsus.

MYOLOGY 215

In the dog and the cat this muscb, which is rather large,
arises from the external tuberosity of the tibia and from the
crest of this bone. In its superior part it is flat, but lower
down it is thick and produces a prominence in front of the
tibia. Finally, it becomes tendinous, and passes towards
the tarsus ; thence it is directed towards the inner side of
the metatarsus, and is inserted into the great-toe, this latter
being sometimes well developed, but also often merely repre-
sented by a small bony nodule on which the muscle is then
fixed.

In the other animals with which we here occupy ourselves,
the tibialis anticus presents a complexity which would be
incomprehensible unless this muscle be first studied in
the horse.

In this latter the tibialis anticus consists of two distinct
portions, placed one in front of the other : a fleshy portion,
and a tendinous portion running parallel to it.

The muscle is covered, except on its internal part and
inferiorly, by a muscle with which we will occupy ourselves
later on — that is, the common extensor of the toes.

The tendinous portion of the tibialis anticus (Fig. 83),
especially covered by the extensor of the toes, arises from
the inferior extremity of the femur, from the fossa situated
between the trochlea and the external condyle ; thence it
descends towards a groove which is hollowed out on the
external tuberosity of the tibia, and is directed towards the
tarsus, where it divides into two branches, which are
inserted into the cuboid bone and the superior extremity of
the principal metatarsal. These two parts form a ring
through which the terminal tendon of the fleshy portion of
the same muscle passes.

This fleshy portion, situated behind the preceding, arises
from the superior extremity of the tibia, on the borders of
the groove in which the tendinous portion lies ; thence it
passes downwards for a short distance on the inner side of
the common extensor of the toes, which covers it in the rest
of its extent. It ends in a tendon which, after passing
through the tendinous ring above noticed, divides into
two branches. One of these branches is inserted into

2i6 THE ARTISTIC ANATOMY OF ANIMALS

E^ C.
Fig. 84. — Myoi.cgy of the Dog : Left Hind-limb, External Aspect.

I, Biceps cruris and fascia lata, divided in order to expose the upper
part of the muscles of the leg ; 2, inferior portion of the triceps cruris ;
3, patella ; 4, semi-tendinosus ; 5, inferior extremity of the femur ; 6,
tibialis anticus (flexor of the metatarsus) ; 7, extensor longus digitorum
(anterior extensor of the phalanges) ; 8, tibia ; 9, peroneus longus ; 10,
peroneus brevis ; 11, fifth metatarsal; 12, fasciculus detached from the
peroneus brevis and passing towards the fifth toe; 13, external head of
gastrocnemius; 14, tendo- Achilles ; 15, calcaneum ; 16, flexor digitorum
sublimis ; 17, 17, tendon of the flexor digitorum sublimis ; 18, flexoi longus
pollicis (portion of the deep flexor of the toes) ; 19, dorsal muscle of the
foot (short extensor of the toes).

MYOLOGY 217

the anterior surface of the superior extremity of the prin-
cipal metatarsal, the other into the second cuneiform bone.

In the ox the same two portions of the tibialis anticus
exist, but with this capital difference — that the anterior
portion is fleshy, superficial, and blended for a great part of
its length with the common extensor of the toes.

The portion which corresponds to that which is fleshy in
the horse arises from the tibia ; below, it ends on the inner
surface of the superior extremity of the metatarsus and the
cuneiform bones. That which represents the tendinous
part, which is also fleshy, as we have just pointed out,
arises above with the common extensor of the toes, from
the femur, in the fossa situated between the trochlea and
the external condyle ; whilst below, after having given
passage to the tendon of the preceding portion, as in the
horse, it is inserted into the metatarsus and the cuneiform
bones.

In the pig, the tibialis anticus presents an arrangement
nearly similar to that which we have just described.

It seems to us of interest to add that it has been sought
to ascertain to what muscle of the human leg the tendinous
part of the tibialis of the horse corresponds — a part which
has become fleshy in the pig and the ox.

According to some authors, it represents the peroneus
tertius ; but that muscle is situated on the outer side of
the common extensor of the toes ; and here the portion with
which it has been compared is placed on the inside. It has
also been likened to a portion of the common extensor
of the toes, but it does not pass to the latter. Lastly, it has
been considered as being the homologue of the proper
extensor of the great-toe ; but why, then, in the ox, which
has no great-toe, is it so highly developed ? Nevertheless,
its position and its relations sufficiently warrant this method
of comprehending it. The tibialis anticus is a flexor of the
foot. It is also able, in animals in which the tarsal articula-
tions allow of the movement, to rotate the foot inwards.

With regard to the tendinous part, called by veterin-
arians the cord of the flexor of the metatarsus, it serves, in
the horse, to produce the flexion of the metatarsus when

EV.C.

Fig. 85. — Myology of the Ox: Left Leg, External Aspect.

I, Gluteus maximus and biceps cruris; 2. semi-tendinosus ; 3, patella ;
4, tibialis anticus (flexor of the metatarsus) ; 5, extensor longus digitorum
(anterior extensor of the phalanges) ; 6, fasciculus of the extensor longus
digitorum, which is considered as the representative of the tendinous
portion of the tibialis anticus in the horse ; 7, peroneus longus ; 8,
peroneus brevis (proper extensor of the external toe) ; 9, external head
of gastrocnemius; 10, soleus ; 11, tendo-Achillis ; 12, calcaneum ; 13,
tendon of the extensor longus digitorum (superficial flexor of the phal-
anges) ; 14, flexor longus pollicis and tibialis posticus (deep flexor of the
phalanges); 15, tendon of the superficial flexor of the toes; 16, tendon of
the deep flexor of the toes ; 17, suspensory ligament of the fetlock.

MYOLOGY 219

the knee is already flexed ; it thus acts in a passive fashion,
which is explained by its resistance and the position which
it occupies in relation to these two articulations.

Extensor Proprius Pollicis. — This muscle exists only in
the dog and the cat, and there in a rudimentary condition.

It is covered by the common extensor of the toes and the
tibialis anticus, and passes, accompanied by the tendon of
this latter muscle, to terminate on the second metatarsal,
or the phalanx, which articulates with it. When the first
toe exists in the dog, it is inserted into this by a very
slender tendon.

Extensor Longus Digitorum (Fig. 83, 9 ; Fig. 84, 7 ;
Fig. 85, 5, 6 ; Fig. 86, 4 ; Fig. 87, 12 ; Fig. 88, 7).— It is also
called by veterinarians the anterior extensor of the phalanges.

In the dog and the cat this muscle is to be seen in the
space limited behind by the peroneus longus and in front by
the tibialis anticus. Above it is covered by this latter. In
the lower half of the leg, it is also in relation, on the inner
side, with the tibialis anticus ; but behind it is separated
from the peroneus longus by the external surface of the
shaft and inferior extremity of the tibia. This arrange-
ment, besides, recalls that which is found in man, the
peroneus longus of the latter diverging in the same way, at
this level, from the common extensor, and leaving exposed
the corresponding portion of the skeleton of the leg.

This muscle, fusiform in shape, arises at its upper part
from the external surface of the inferior extremity of the
femur, then its tendon passes into a groove hollowed on
the external tuberosity of the tibia. The fleshy body which
succeeds is directed towards the tarsus, but before reaching
it is replaced by a tendon. This tendon, at the level of the
metatarsal bones, divides into four shps, which pass towards
the toes, and are inserted into the second and third
phalanges of the latter.

In the horse it covers, to a great extent, the tibialis
anticus, so that it is the latter which forms the large fusi-
form prominence especially noticeable in the middle region,
to which the contour of the anterior surface of the leg
is due.

220 THE ARTISTIC ANATOMY OF ANIMALS

Fig. 86. — Myology of the Horse: Left Hind-limb, External Aspect.

I, Semi-tendinosus ; 2, biceps cruris; 3, patella; 4, extensor longus
digitorum (anterior extensor of the phalanges) ; 5, reinforcing band arising
from the ligament of the fetlock ; 6, peroneus brevis (lateral extensor of
the phalanges) : 7, external head of gastrocnemius ; 8, soleus ; 9, tendo-
Achillis ; to, calcaneum ; 11, tendon of the superficial flexor of the toes
(superficial flexor of the phalanges); 12, flexor longus pollicis and tibialis
posticus (deep flexor of the phalanges); 13, 13, tendon of the superficial
flexor of the phalanges ; 14, 14, tendon of the deep flexor of the phalanges ;
15, suspensory ligament of the fetlock; 16, principal metatarsal; 17,
external rudimentary metatarsal.

MYOLOGY 221

It arises above from the inferior extremity of the femur,
from the fossa situated between the trochlea and the ex-
ternal condyle ; therefore, it has a common origin with the
tendinous portion of the tibialis anticus, or flexor of the
metatarsus.

The tendon, which at the level of the inferior part of
the leg succeeds to the fleshy body, passes in front of
the tarsus, the principal metatarsal, and receives the ten-
don of the peroneus brevis which we will describe later on.
It then reaches the anterior surface of the fetlock. There
it presents an arrangement analogous to that which we
have pointed out in connection with the anterior extensor
of the phalanges — a muscle which, in the fore-limbs, corre-
sponds to the common extensor of the digits ; that is to say,
it is inserted, in form of an expansion, into the pyra-
midal prominence of the third phalanx, after having formed
attachments to the first and second, and having received
on each side a strengthening band from the suspensory
ligament of the fetlock.

In the ox the long extensor of the toes is united above,
and for a great part of its length, with the portion of the
tibiaUs anticus, which represents, albeit in the fleshy state,
the tendinous cord of the latter in the horse.

In common with this portion, it arises from the inferior
extremity of the femur. Thence it passes towards the tarsus
and divides into two fasciculi, internal and external, which
are continued by tendons. These pass towards the
phalanges, and, in case of the common extensor of the digits
belonging to the fore-limbs, the internal is destined for the
internal toe, and the external is common to the two toes.

In the pig the general arrangement of the muscle is
similar, but the tendons end in a manner which is a little
more complicated. Apart from the fasciculi which corre-
spond to the tendinous portion of the tibialis anticus
(fleshy here, as in the ox), the long extensor of the toes
at the level of the tarsus divides into three tendons : the
internal goes to the great internal toe ; the middle bifur-
cates in the upper part of the digital portion of the foot,
and each of its branches goes towards one of the great-toes ;,

222 THE ARTISTIC ANATOMY OF ANIMALS

7

LS C.
Fig. 87. — Myology of the Dog : Left Hind-limb, Internal Aspect.

I, Semi-tendinosus ; 2, semi-membranosus ; 3, triceps cruris (vastus
internus) ; 4, sartorius (patellar) ; 5, sartorius (tibial) ; 6. patella ; 7,
first or middle adductor; 8, small and great adductor united ; 9, gracilis;
10, tibialis anticus (flexor of the metatarsus); 11, tibia; 12, tendon of
extensor longus digitorum (anterior extensor of the phalanges) : 13. gas-
trocnemius, inner head ; 14, tendo-AchilUs ; 15, calcaneum ; 16, popliteus ;
17, superficial liexor of the toes ; 18, flexor longus pollicis (portion of the
deep flexor of the toes) ; 19, flexor longus digitorum (portion of the deep
flexor of the toes) ; 20, tendon of the tibialis posticus.

MYOLOGY

223

I, Semi - tendinosus ; 2,
semi-membranosus ; 3, triceps
cruris (vastus internus) ; 4,
patella ; 5, sartorius ; 6,
gracilis ; 7, extensor longus
digitorum common extensor
of the toes (anterior ex-
tensor of the phalanges) ;
8, tendon of the preced-

ing muscle ; 9, reinforcing

E.^.C. band given off by the sus-
pensory ligament of the
Fig. 88. — Myology of the Horse : Left fetlock; 10, tibialis anticus
Hind-leg, Internal Aspect. (flexor of the metatarsus),

its tendinous ■ portion ; 11, tibialis anticus (flexor of the metatarsus), its
fleshy portion ; 12, cuneiform branch of the tendon of this fleshy portion ;
13, internal head of gastrocnemius ; 14, pophteus ; i 5, tendon of the flexor
brevis digitorum (superficial flexor of the phalanges) ; 16, flexor longus
pollicis and tibiaUs posticus (deep flexor of the phalanges); 17, flexor
longus digitorum (oblique flexor of the phalanges) ; 18, 18, tendon of the
superficial flexor of the phalanges ; 19, 19, tendon of the deep flexor Oi
the phalanges; 20, suspensory ligament of the fetlock; 21, principal
metatarsal ; 22, internal rudirnentary metatarsal.

224 THE ARTISTIC ANATOMY OF ANIMALS

the external divides to pass towards each of the two small
toes, and towards the great ones ; but this latter disposition
is not constant.

By its contraction the muscle which we have just studied
extends the phalanges and flexes the foot.

Peroneus Tertius. — This muscle is not found in domestic
quadrupeds.

We should remember, nevertheless, that certain authors
consider as representing it the tendinous portion of the
anterior tibial of the horse, or the corresponding portion
now fleshy, of the same muscle in the pig and the ox. It
is by reason of this fact that it is called the third peroneal,
notwithstanding that in the numerical order of the peroneals
it is rather the first.

But that which still further complicates this question of
nomenclature is that some authors give this name of third
to a peroneal which, in the carnivora, is situated more de-
finitely in the group of external muscles (see below. Short
Lateral Peroneal).

Muscles of the External Region

In man, two muscles constitute this region ; they are
the peroneus longus and peroneus brevis.

Peroneus Longus (Fig. 84, 9 ; Fig. 85, 7). — This muscle
does not exist in the domestic animals ; only in the flesh-
eaters, the pig and the ox excepted.

It is in relation superiorly with the tibialis anticus, and
interiorly with the common extensor of the toes ; in the
ox, it is in contact with this latter muscle throughout its
whole length.

The peroneus longus arises from the external tuberosity
of the tibia ; towards the middle of the leg it is replaced by
a tendon. This proceeds towards the tarsus, but previously
it passes between the tibia and fibula. In the ox it is
situated in front of the coronoid tarsal bone ; we recol-
lect that this bone is regarded as representing the in-
ferior extremity of the fibula (see p. 97). Then it passes
into a groove belonging to the cuboid bone or to the cuboido-
scaphoid bone in the ox, traverses obliquely the posterior

MYOLOGY 225

aspect of the tarsus, and is inserted into the rudimentary
bone which represents the first toe ; or, if this does not exist,
into the innermost of the metatarsal bones.

This muscle is an extensor of the foot. It also rotates it
outwards in the animals in which the articulation permits
this latter movement.

Peroneus Brevis (Fig. 83, 8 ; Fig. 83, 10 ; Fig. 84, 10 ;
Fig. 86, 6). — In the dog and the cat, this muscle is covered
in part by the peroneus longus, and arises from the inferior
half of the tibia and the fibula ; at the level of the tarsus it
becomes tendinous, passes into a groove hollowed out on the
external surface of the inferior extremity of the fibula, and
terminates on the external aspect of the superior extremity
of the fifth metatarsal. A Uttle before this insertion it
crosses the tendon of the long peroneal in passing to the
outer side of the latter.

To the short peroneal muscle is found annexed a very
thin fasciculus which lies upon it. This fasciculus arises
from beneath the head of the fibula, and is soon replaced
by a thin tendon, which, accompanying that of the short
peroneal, proceeds towards the foot, after having traversed
the groove in the inferior extremity of the fibula ; passes
along by the fifth metatarsal (Fig. 84, 12) ; blends at the
level of the first phalanx of the fifth toe with the correspond-
ing tendon of the long extensor of the toes, and partakes
of the insertions of this tendon.

This fasciculus is designated by some authors under the
name of the peroneal of the fifth toe, or the proper extensor
of the same toe. But what makes still further complica-
tions is that other authors regard it as an anterior, or third,
peroneal. Now, these names are those which other anato-
mists have applied to the fasciculus of the anterior tibial,
which, in the pig and the ox, is fused in part with the
long extensor of the toes. Hence there results a confusion
which is truly regrettable.

In brief, we can, without inconvenience, consider it as a
fasciculus of the short peroneal muscle.

We sometimes find in man, but abnormally, an arrange-
ment which partly recalls that which we have just indicated.

15

226 THE ARTISTIC ANATOMY OF ANIMALS

It consists in a duplication of the tendon of the short pero-
neal, one of the branches of which goes to the fifth meta-
tarsal, and the other to the fifth toe ; it is sometimes a single
fasciculus which goes to the phalanges of this latter. We
have met with examples of these anomahes.* In the pig,
the short peroneal is situated on the same plane as the long.
It consists of two clearly distinct fascicuh, which arise from
the fibula. The tendon of the anterior fasciculus proceeds
to the great external toe — that is to say, the fourth, of
which it is the proper extensor. The posterior fasciculus
terminates on the small external toe, the fifth, of which it
is in like manner the extensor.

In the ox, the fleshy fibres of the short peroneal arise from
a fibrous band which replaces the fibula, and from the ex-
ternal tuberosity of the tibia. Situated behind the long
peroneal and on the same plane, it terminates in a tendon
which appears at the level of the inferior part of the leg ; it
passes in front of the canon, and is inserted into the external
toe, of which it is the proper extensor.

In the horse, it is the sole representative of the peroneal
muscles, and veterinary anatomists have given it the name
of the lateral extensor of the phalanges.

Its fleshy body arises above from the external lateral
ligament of the knee-joint, and from the whole length of the
fibula. In the middle third of the leg it is narrowed ;
lower down it is replaced by a tendon. This is lodged in
a groove hollowed on the external surface of the inferior
extremity of the tibia ; then after passing along the external
surface of the tarsus, it is directed forward, and proceeds to
blend towards the middle of the canon-bone with the ten-
don of the long extensor of the toes, or anterior extensor
of the phalanges, of which it shares the insertions. It
extends the phalanges into which it is inserted. It also
flexes the foot.

* Edouard Cuyer, ' Anomalies, Osseous and Muscular ' (Bulletins de la
Societe d'Anthropologie, Paris, 1891).

MYOLOGY 227

Muscles of the Posterior Region

It will not be unprofitable to recall to mind that, in man,
the muscles of this region are arranged in two layers :
a superficial layer consisting of the gastrocnemius and
soleus, to which is added a muscle of Uttle importance,
the plantaris, and a deep layer formed by four muscles —
the popliteus, flexor longus digitorum, tibiahs posticus,
and flexor longus pollicis.

The gastrocnemius and soleus, independent in their upper
portion, unite below in a common tendon ; they thus
form also a triceps muscle, which we designate under the
name of the triceps of the leg, or triceps suralis, because
it forms the elevation of the calf of the leg (from sura,
calf).

Gastrocnemius (Fig. 83, 9, 11 ; Fig. 84, 13, 14 ; Fig. 86,
7, 9 ; Fig. 88, 13). — The external and internal heads of
the gastrocnemius, distinct from one another only in their
upper portion, arise from the shaft of the femur, above
the condyles, on the borders of the popUteal surface, to a
relatively considerable extent in the great quadrupeds.

At this level they are situated in the popliteal region —
that is to say, in the space limited externally by the biceps,
and internally by the semi-tendinosus. But as they descend
to a rather low level on the leg in quadrupeds, and especially
in carnivora, they do not, properly speaking, determine a
projection of the calf of the leg. However, they pass from
this region but to be soon continued b}/ a tendon — the tendo-
Achillis, which is inserted into the calcaneum.

Now, the region of the tarsus is called by veterinarians the
ham, the posterior surface of which is angular, because of
the oblique direction of the leg with regard to the vertical
direction of the metatarsus and the presence of the
calcaneum ; the prominence which this surface presents has
received the name of the point of the ham, and the tendon
which ends there that of the cord of the ham.

But the tendo-Achillis does not alone form this cord.
Indeed, as we will soon see, the tendon of the superficial
flexor of the toes takes part in its formation.

15—2

228 THE ARTISTIC ANATO:\IY OF ANIMALS

We may add, with regard to the tendo-AchiUis, that it
is more clearly perceived as an external feature, because the
skin sinks in front of it, as it does in man, over the lateral
parts of the region which it occupies.

The gastrocnemius, when it contracts, extends the foot
on the leg.

It serves to maintain the tibio-tarsal angle in the standing
position, and during walking, to determine the steadying
of the hind-limbs, which then, after the fashion of a spring,
project the body forward.

By an analogous movement they take part in the pos-
terior projection of the hind-limbs in the act of kicking;
but they are not the only ones to act in this case, the
muscles of the buttock and thigh also being brought into
play.

Soleus (Fig. 83, 10 ; Fig. 86, 8). — This muscle, much less
developed in quadrupeds than in man, does not exist in the
dog.

With regard to the soleus in the pig. Professor Lesbre says :
' jNIeckel denied its existence ; we, however, believe that it
is united to the external head of the gastrocnemius, its
origin being transferred to the femur.'*

But in animals in which it exists, this muscle, of but little
importance, occupies the outer side of the leg. It arises
above from the external tuberosity of the tibia, and ter-
minates below in a tendon which is united with that of the
gastrocnemius.

The soleus has the same action as these latter.

Plantaris. — In quadrupeds this muscle is blended with
the superficial flexor of the toes, which we will study
afterwards.

Popliteus (Fig. 87, 16 ; Fig. 88, 14). — In man, this
muscle, which occupies the posterior surface of the tibia,
above the oblique line, is completeh^ covered by the gastroc-
nemius.

In quadrupeds, where it is more voluminous, it projects

* F. X. Lesbre, ' Essai de Myologie comparee de I'homme et des mam-
miferes domestiques en vue d'etablir une nomenclature unique et ration-
elle,' Lyon, 1S97, p. 169.

MYOLOGY 229

internally beyond the gastrocnemius, so that it is seen
in the internal and superior part of the region of the super-
ficial layer of muscles, immediately behind the internal
surface of the tibia, which, as we know, is subcutaneous.

The popliteus arises from the external surface of the
external condyle of the femur. Thence its fibres which
diverge pass to be inserted into the superior part of the
posterior surface and of the internal border of the tibia.
It is in this latter region that it projects beyond the
gastrocnemius, but we may add that there it is more or less
covered by the semi-tendinosus.

It flexes the leg, and rotates it forwards.

Superficial Flexor of the Toes (Fig. 83, 13, 15 ; Fig.
84, 17 ; Fig. 86, II, 13, 13 ; Fig. d>y, 17 ; Fig. 88, 15, 18, 18).
— In man, the homologue of this muscle is found in the sole
of the foot. It is called the short flexor of the toes. It arises
from the calcaneum, and passes to the four outer toes. In
quadrupeds, it rises as high as the back of the knee, and is
found blended with the plantaris.

Further designated by the name of the superficial flexor
of the phalanges, covered in part by the gastrocnemius, with
which it is in relation for a great part of the course which
it traverses, this muscle arises from the posterior surface
of the femur, on the external branch of the inferior bifurca-
tion of the linea aspera. In the horse, this origin takes
place in a depression situated above the external condyle,
in the supracondyloid fossa. Then it accompanies the
gastrocnemius, and becomes tendinous where the tendo-
Achillis commences. It then winds round the latter in
placing itself on its inner side, then on its posterior sur-
face, and reaches the calcaneum. It accordingly contri-
butes, as we have already pointed out, to form the cord of the
ham. After having become expanded, and having covered
as with a sort of fibrous cap the bone of the heel, it descends
behind the metatarsus, and presents there an arrange-
ment analogous to that which we pointed out in connection
with the superficial flexor of the digits — that is, it con-
tributes to form the tendon. This prominence, in the
form of a cord, we see behind the canon-bone in sohpeds

230 THE ARTISTIC ANATOMY OF ANIMALS

and ruminants. It finally terminates in the same way as
the muscle with which we have compared it (see p. 197).

In the horse, its fleshy body is but slightly developed,
so that its tendon alone is specially visible in the super-
ficial muscular layer, but in the dog and the cat it is
large. Hence it results that its fleshy body appears
on each side of the inferior half of the gastrocnemius,
and produces an elevation which recalls that which the
soleus produces on each side of the same muscles in the
human species.

The muscles which follow form, with the popliteus, which
we have already studied, the deep layer of the posterior
region of the leg.

Flexor Longus Digitorum (Fig. 87, 19 ; Fig. 88, 17). —
This muscle, in man, is the only common flexor of the toes
belonging to the muscles of the leg.

In comparison with the preceding muscle, it is a deep
flexor. Veterinarians have given it the name of the oblique
flexor of the phalanges.

Visible on the internal aspect of the superficial layer of the
muscles of the leg, this muscle arises above from the pos-
terior surface of the external tuberosity of the tibia, becomes
tendinous, passes towards the metatarsus, and blends with
the tendons of the posterior tibial and the long proper
flexor of the great-toe. In the dog and the cat it is blended
with this latter only.

Tibialis Posticus (Fig. 85, 14; Fig. 86, 12; Fig. 87, 20;
Fig. 88, 16). — This muscle arises from the external tuber-
osity of the tibia, and from the head of the fibula. Thence
it passes to the tarsus, and terminates in different fashion
in carnivora and other quadrupeds.

In the dog and the cat, it is inserted into the ligamentous
apparatus of the tarsus, or into the base of the second
metatarsal.

In the other quadrupeds with which we are here occu-
pied it is blended with the long proper flexor of the
great-toe.

It is accordingly in the carnivora that the mode of ter-
mination of the tibialis posticus most nearly resembles

MYOLOGY 231

that of this same muscle in the human species. From this
independence there results a special action.

It is an adductor and internal rotator of the foot.

Flexor Longus Pollicis (Fig. 84, 18 ; Fig. 85, 14 ;
Fig. 86, 12 ; Fig. ^y, 18 ; Fig. 88, 16). — This muscle, as
that in man, is the most external of the deep layer of the
leg. It is on the external aspect of the latter we perceive
it, between the peroneals and the gastrocnemius or tendo-
Achillis.

It arises from the fibula and tibia, and is thence directed
towards the tarsus. It unites with the long common flexor
of the toes to form with it the deep flexor of the -phalanges,
of which it is the principal fasciculus. We may add that in
the dog and the cat the posterior tibial remains independent
of this latter, but that in the pig, ox, and horse the posterior
tibial is united to the preceding to form with them the deep
flexor muscle.

Thus constituted, the deep flexor goes towards the
phalanges, where it terminates as the deep flexor of the
digits of the fore-limbs (see p. 197). In animals possessed
of a canon it contributes to form the tendon (Fig. 85, 16 ;
Fig. 86, 14, 14 ; Fig. 88, 19, 19).

Muscles of the Foot

We must remember that on the dorsal surface of the foot
in man we find but a single muscle — the dorsalis pedis.
The remaining subcutaneous structures of this region
consist of the tendons of the anterior muscles of the leg
which occupy this dorsal aspect.

Dorsalis Pedis (Fig. 84, 19).— Also called the extensor
brevis digitorum, the dorsahs pedis muscle is found in all
domestic quadrupeds ; but its development is so much the
less as the number of digits is more reduced.

In the dog and the cat it arises from the calcaneum, and
is inserted into the three internal toes (the first toe excepted)
by uniting with the corresponding tendons of the common
extensor.

In the pig its disposition is analogous.

232 THE ARTISTIC ANATOMY OF ANIMALS

As for the dorsalis pedis of the ox and the horse, it is
extremely rudimentary, and occupies the superior part of
the canon. It is a small, fleshy body, situated on the an-
terior surface of the metatarsus, which arises from the cal-
caneum, whence it passes to unite at its inferior extremity
with the tendon of the extensor of the phalanges.

As regards the muscles of the sole of the foot, we think it
unnecessary to occupy ourselves at any length with them be-
cause of their slight importance with regard to external form.

We will only recall that in the median portion of this
plantar surface we find in man the short flexor of the toes,
which in quadrupeds arises higher up, from the posterior
surface of the femur ; that it belongs to the muscles of the
leg ; and that it forms the superficial flexor of the toes,
which we have already studied.

We may further add that the suspensory ligament of the
fetlock in ruminants and solipeds represents, as in the fore-
limbs, the interosseous muscles.

MUSCLES OF THE HEAD

We will divide these muscles into two categories :
masticatory and cutaneous.

Masticatory Muscles

The muscles of this group which specially interest us are
the masseter and the temporal. As regards the pterygoids,
since they are situated within the borders of the inferior
maxillary bone, and consequently do not reach the surface,
we shall not require to occupy ourselves with them here.

Masseter (Fig. 89, 2; Fig. 90, i ; Figs. 91, 92). — For those
who have studied the masseter of man, it is not difficult to
recognise that of quadrupeds. Nevertheless, the particular
aspect which it presents in different species gives to its
study a certain interest.

Arising from the zygomatic arch, and passing downwards
and backwards, it is inserted into the external surface of
the ramus of the mandible and into its angle.

MYOLOGY

233

Its posterior border is in relation with the parotid gland
(Fig. 90, 14 ; Figs. 91, 92), this gland being situated between
the corresponding border of the lower jaw bone and
the transverse process of the atlas. Such are the general
characters ; the following are the particular ones :

In the carnivora it is thick and convex. In the horse it
is flat, but more expanded ; it forms the flat of the cheek.
In the ox it is flat, as in the latter ; but, while being less
thick, it is more prolonged in the vertical direction.

The form of the osseous parts which give it origin is,
besides, in relation with these differences, and explains the
peculiar characters which the masseter presents.

Fig. 89. — Myology of the Dog : Masticatory Muscles (a Deeper
Dissection than that shown in Fig. 90).

I, Zygomatic arch ; 2, masseter ; 3, temporal exposed by the suppres-
sion of the auricular and occipital muscles and the pinna of the ear ; 4,
auditory canal ; 5, inferior maxillary bone ; 6, digastric.

Indeed, in the dog and the cat the zygomatic arch,
strongly convex, springs up in a marked manner from the
plane of the lateral aspects of the skull.

In the horse the same arch, less prominent externally, is
prolonged by a rectilinear crest on the superior maxillary
bone, where it is continued in forming the zygomatic or
maxiUary spine.

In the ox the same crest ascends a good way towards the
inferior margin of the orbit in a curved direction with the

234 THE ARTISTIC ANATOMY OF ANIMALS

concavity inferior, to redescend afterwards on the external
surface of the superior maxilla.

The masseter is an elevator of the lower jaw. It acts, above
all, as in the human species, in the process of mastication.

Temporal Muscle (Fig. 89, 3). — The development of the
temporal is in proportion to the energy of the movements
of elevation which the lower jaw has to execute.

It arises from the temporal fossa, and is inserted into the
coronoid process of the inferior maxilla.

Its development, enormous in the carnivora, is such that
the muscle projects beyond its fossa. It is less voluminous
in the horse, and still less so in the ox. In the latter, indeed,
the temporal fossa, although deep, is of small extent (see
Fig. 62, p. 119) ; the frontal bone being large, it is found to
be thrown back on the lateral walls of the cranium, below
the osseous processes which support the horns and overhang
the fossa in question, as well as the muscle which it contains.

It is covered by the auricular muscles, and by the base
of the pinna of the ear.

Like the masseter, the temporal is an elevator of the
lower jaw.

Cutaneous Muscles of the Head

Occipito- Frontalis. — The epicranial aponeurosis is ex-
tremely thin. In the dog the occipital muscle occupies the
superior part of the head ; it overlies the temporal muscle.

With regard to the frontal muscle, which is of great extent
in the ox (Fig. 91, F), it is represented in the horse and the
carnivora by a small fleshy fasciculus only, the fronto-
palpebral muscle, similar to the superciliary muscle. This,
occupying the superior and internal part of the border of
the orbit, ends by blending its libres with those of the
orbicular muscle of the eyelids at the region of the eyebrow.

Orbicularis Palpebrarum (Fig. o, 92 ; Figs. 91, 92). — This
annular muscle surrounds the palpebral orifice, and takes
its origin on the internal part of the orbital region. In the
horse it arises, by a small tendon, from a tubercle which
occupies the external surface of the os unguis, or lachrymal
bone.

MYOLOGY

235

This muscle determines the narrowing and closure of the
palpebral orifice.

Pyramidalis Nasi. — The pyramidal muscle is not found
in the domestic animals. It appears to be blended with
the internal elevator of the upper Up and wing of the nose ;
this is easy of comprehension if we bear in mind the relative
position of these two muscles in the human species.

, 16 n

Fig. 90. — Myology of the Dog : Muscles of the Head.

I, Masseter ; 2, orbicularis palpebrarum ; 3, zygomaticus major; 4, lachry-
mal (this muscle is sometimes described under the name of the small
zygomatic) ; 5, levator labii superioris proprius ; 6, levator labii superioris
alaeque nasi; 7, caninus ; 9, buccinator; 11, zygomatico-auricularis ;
12, external temporo-auricularis ; 14, parotid gland; 15, parotido-auri-
cularis ; 16, inferior maxillary bone ; 17, digastric.

Corrugator Supercilii. — This muscle is represented by
the fronto-palpebral muscle noticed above, which is by some
Regarded as a vestige of the frontal.

Zygomaticus Major (Fig. 90, 3 ; Figs, 91, 92). — This is
the zygomatic-lahial of veterinarians. This muscle is of an
elongated form, and has a ribbon-like aspect.

In the dog and the cat it arises from the base of the pinna
of the ear, from the portion of this base which bears the
name of scutiform cartilage. (With regard to this cartilage,
see p. 242, Zygomatico-auricularis.) From this it is directed

236 THE ARTISTIC ANATOMY OF ANIMALS

downwards and forwards, to terminate, after having crossed
the masseter, on the deep surface of the skin of the cor-
responding labial commissure.

This mode of termination is the same in the ox and the
horse ; but where the muscle differs is at the level of its
upper extremity. There it ascends less than in the carnivora.
In the ox it arises from the zygomatic arch in the neighbour-
hood of the temporo-maxillary articulation ; in the pig and
the horse its origin is still lower, on the surface of the
masseter, close to the maxillary spine.

When it contracts, it draws upwards the labial
commissure.

Now, in man, we remember, it is the great zygomatic
that, by an action of the same kind, determines the essen-
tial characters of the expression of laughing.

There is, accordingly, a connection to be established
between those displacements which are similar and the
analogy of facial expression which necessarily results from
them.*

Zygomaticus Minor (Fig. 90, 4 ; Figs, 91, 92). — The
existence of this muscle has not been clearly demonstrated.
Nevertheless, Straus-Durckheim noted its presence in the
horse, and described it as ' a muscle arising by two heads,
of which one, the superior, arises from the malar bone below
the orbit, and passes downwards and forwards over the fibro-
adipose layer which supports the moustache. The second,
the inferior, arises from the alveolar border in front of the
second molar tooth, and passes forward to be inserted into
the same fibro-adipose layer.'f

In connection with other quadrupeds, it is described by
certain authors as a very thin muscle, arising below the
cavity of the orbit, where it is blended with the fibres of the
internal elevator of the upper lip and the ala of the nose ;
thence it proceeds to terminate below by uniting with the
subcutaneous muscle. But this muscle is regarded by other

* Edouard Cuyer, ' The ]\Iimic,' Paris, 1802.

t H. Straus - Durckheim, ' Anatomie descriptive et comparative du
chat,' Paris, 1845, t. ii., p. 210.

MYOLOGY

237

authors as the lachrymal muscle, which does not exist in
this state in man, but of which the development is par-
ticularly remarkable, as to extent, in the ox, in which it
descends as far as the buccinator.

According to other authors, some of the fibres of this
muscle constitute the small zygomatic.

Fig. qi. — Myology of the Ox : Muscles of the Head.

1, Masseter ; 2, orbicularis palpebrarum; F, frontalis; 3, zygomaticus
major ; 4, lachrymal (this muscle is sometimes described under the
name of small zygomatic); 5, levator labii superioris proprius ; 6,
levator labii superioris alseque nasi ; 7, levator anguli oris or caninus ; 8,
orbicularis oris ; 9, buccinator ; 10, maxillo-labial ; 1 1 , zygomatico-auricu-
laris ; 12, external temporo-auricularis ; 14, parotid gland; 15, parotido-
auricularis ; 16, inferior maxillary bone.

Levator Labii Superioris Proprius (Fig. 90, 5 ; Figs. 91,
92). — Also named by veterinarians the supramaxillo-lahial,
or again, the proper elevator of the upper lip, this muscle
arises from the external surface of the superior maxillary
bone, passes under the superficial elevator, which we shall
study in the succeeding paragraph, and goes to be inserted
into the thickness of the lip, to which its name indicates
that it belongs.

238 THE ARTISTIC ANATOMY OF ANIMALS

The peculiarities of this muscle in different animals are
the following :

In the dog and the cat it arises behind the infra-orbital
foramen.

In the pig it arises from a depression below the orbital
cavity, and its fleshy body is terminated in front by a strong
tendon in the upper part of the snout, in which it divides
into fasciculi.

In the ox it arises from the maxillary spine.

In the horse it arises below the orbital cavity ; then, after
having crossed the superficial elevator, it ends in a tendinous
expansion, situated in the median hne between the nasal
fossae. This expansion divides into fasciculi, which end in
the thickness of the upper lip.

By the contraction of this muscle, the hp is raised, on one
side only, if a single muscle contracts, or in its whole extent,
if the two muscles act simultaneously.

Internal Elevator (or Superficial) of the Upper Lip
and the Wing of the Nose {levator lahii superioris alceque
nasi) (Fig. 90, 6 ; Figs. 91, 92). — This is the muscle veteri-
narians designate the supranaso-labial.

Arising from the frontal and nasal bones, it thence passes
towards the upper lip, where it is inserted as well as into
the wing of the nose.

In the ox it is united above with the frontal muscle, and
below is divided into two fasciculi, between which pass the
elevator described above and the canine muscle.

In the horse it is also divided into two fascicuh ; but
the arrangement is the opposite as regards, their relations
with neighbouring muscles, in this animal and in the
preceding.

In the ox the external fasciculus is covered by the external
elevator and the canine, which pass under the internal
fasciculus ; in the horse the deep elevator passes under the
two fasciculi, and the canine passes under the external
bundle, and afterwards covers the internal.

In the pig, the internal elevator is wanting.

As its name indicates, it raises the upper lip and the wing
of the nose.

MYOLOGY

239

Transversus Nasi. — In the horse this muscle, which is
very thin, is situated on the dorsum of the nose, and pro-
ceeds to be inserted into the cartilaginous skeleton of the
nostrils. In the pig, it occupies an analogous situation.
It does not exist in the ox or in carnivora. The trans-
versus nasi is a dilator of the nostrils.

Fig. 92. — Myology of the Horse : Muscles of the Head.

I, Masseter ; 2, orbicularis palpebrarum; 3, zygomaticus major;
4, lachrymal (this muscle is sometimes described imder the name of the
small zygomatic) ; 5, external elevator (or deep) of the upper lip and ala
of the nose ; 6, internal elevator (or superficial) of the upper lip and of
the ala of the nose ; 7. levator anguli oris or caninus ; 8, orbicularis oris;
9, buccinator; 10, maxillo-labialis ; 11, zygomatico-auricularis ; 12, temporo-
auricularis externus ; 13, cervico-auricularis; 14, parotid gland ; i5,parotido-
auricularis ; 16, inferior maxillary bone.

Caninus (Fig. 90 ; Figs. 7, 91, 92). — This is the muscle
called by veterinarians the great supramaxillo-nasal.

In the dog and the cat it is situated below the inferior
border of the external elevator of the upper lip, of which it
follows the direction. It arises, as does this latter, from the
external surface of the maxilla, and goes also to terminate
in the upper lip by blending with the internal elevator

240 THE ARTISTIC ANATOMY OF ANIMALS

of this lip and of the aUe of the nose. It raises the
upper Hp.

In the ox, it arises from the maxillary spine, and then
divides into three parts ; the superior passes under the
internal portion of the internal elevator of the upper lip and
the alae of the nose, and goes into the nostril ; whilst the two
others, situated lower down, terminate in the upper lip.

In the pig, it is formed of two superimposed fasciculi,
which arise from the spine of the maxilla and the impressions
in front of it. These two fasciculi terminate in the snout,
which they move laterally.

In the horse, it is situated at a certain distance from the
external elevator ; in the preceding animals it is in contact
with the latter. Arising behind from the external surface
of the maxilla, in front of the maxillary spine, it is directed
towards the anterior part of the face, passes under the
external portion of the internal elevator (it is the oppo-
site of this in the ox), and proceeds, on expanding, to ter-
minate in the skin of the nostril. Bv its contraction it
dilates the latter.

Orbicularis Oris (Fig. 91, 8 ; Fig. 92). — This muscle, very
fleshy in the solipeds and the ruminants, is arranged as a
ring round the buccal orifice, in the thickness of the lips,
where it is blended with the other muscles of this region.

Having for its function the narrowing of the orifice it
surrounds, it acts during suction and in the prehension of
food.

Triangularis Oris. — This muscle does not exist in
domestic quadrupeds.

Quadratus Menti. — In the pig and the carnivora, it
arises from the anterior part of the body of the inferior
maxillary bone, and passes at the other end to terminate
in the corresponding portion of the lower lip, which it
depresses by its contraction.

In the ox and the horse this muscle does not exist ; it
is replaced for the depression of the lower lip, which it
affects in other animals, by supplemental fibres of the
buccinator.

The Prominence of the Chin. — Below the lower lip in

MYOLOGY 241

the horse is situated the so-called prominence of the chin,
limited posteriorly by the heard, a depressed region which
gives point to the curb of the bridle.

The prominence, which also exists in the ox, is a fibro-
muscular pad which blends with the orbicular muscle of the
lips, and receives on its superior aspect the insertion of the
two muscles {levator menti) by which it is suspended. These
arise, above, on each side of the symphysis of the inferior
maxillary bone. They raise the lower lip with force, and
they are the agents which, as we can sometimes observe in
the horse, make it click against the upper lip, suddenly
projecting it upwards. This action sometimes becomes a
habit, and its continuance constitutes a vice.

A corresponding structure is found in the pig and in the
carnivora, but in them it does not produce an external
prominence such as we have described.

Buccinator (Fig. 90, 9 ; Figs. 91, 92). — Further designated
by the name of alveolo-laUal, this muscle is situated on
the lateral portions of the face, in the thickness of the
cheeks. It consists of two layers, one superficial and the
other deep.

The deep portion arises from the portion of the alveolar
border of the superior maxillary bone which corresponds
to the molar teeth, and from the anterior border of the
ramus of the mandible. Thence it is directed forwards,
passes under the superficial layer, and blends with the
fibres of the orbicular muscle of the hps. To this part of
the buccinator some authors give the name of molar muscle.

The superficial portion is formed by fibres which pass
from the alveolar border of the superior maxillary bone to
the corresponding border of the opposite bone. It is very
highly developed in the herbivora.

This muscle acts especially during mastication ; it serves
to press back again under the molar teeth the portions
of food which fall outside the dental arch.

In the pig, the ox, and the horse, a muscle which is con-
sidered as supplemental to the buccinator is placed along
the inferior border of the latter.

This muscle, which we describe separately under the names

16

242 THE ARTISTIC ANATOMY OF ANIMALS

of maxillo-labialis (Fig. 91, 10 ; Fig. 92) and depressor of the
lower lip, is clearly distinct from the buccinator, especially
in the horse. It arises, behind, with the deep layer of the
muscle to which it is annexed, from the anterior border of
the ramus of the lower jaw ; in front it terminates in the
thickness of the lower lip.

In the ox, it is more intimately united with the buccinator.

It depresses the lip to which it is attached, and displaces
it laterally when it acts on one side only.

In the human species, the pinna of the ear being generally
immobile, the muscles which belong to it are, very naturally,
considerably atrophied. Accordingly, the auricular muscles,
anterior, superior, and posterior, are reduced to pale and
thin fleshy lamellse, whose action is revealed in certain
individuals, only in a way which may be said to be abnormal.

It is not the same in quadrupeds. The pinna of the ear
is extremely mobile, and its displacements have a real value
from the point of view of physiognomical expression.
It is therefore necessary to review the muscles which move
this pinna without giving them, at the same time, more
importance than they merit, since in themselves they do not
determine the formation of surface reliefs, which are suffi-
ciently apparent.

Notwithstanding that for certain of these muscles it is
possible to trace their analogy with those of the auricular
region of man, it is very difficult, because of their complexity,
to trace this analogy for all. This is why we shall not be
able here, as we have done for the other muscles of the
subcutaneous layer, to give at the head of each paragraph
the name of a human muscle, and then to group in the same
paragraph the muscles which correspond to it in different
quadrupeds. Therefore the nomenclature and the divisions
adopted for these latter must serve us as a base or starting-
point.

Because the pinna of the horse's ear is so very mobile, we
will first begin with a study of its auricular muscles.

Zygomatico-auricularis (Fig. 92, 11). — This muscle, which
is formed of two small bands of fleshy fibres, arises from the
zygomatic arch in blending with the orbicular muscle of the

MYOLOGY 243

eyelids ; thence it is directed towards the base of the pinna
of the ear, and is inserted into this base, and also into the
cartilaginous plate situated in front of and internal to this,
and resting on the surface of the temporal muscle ; this is
the scutiform cartilage.

The zygomatico-auricularis, which we look on as the
homologue of the anterior auricular of man, draws the
pinna of the ear forwards.

Temporo-auricularis Externus (Fig. 92, 12). — This, which
is thin and very broad, covers the temporal muscle.

It arises from the whole extent of the parietal crest,
blending in this plane, in its posterior half, with the muscle
of the opposite side. Thence it is directed outwards to-
wards the pinna of the ear, and is inserted into the
internal border of the scutiform cartilage and on the inner
side of the concha — that is to say, of the conchinian car-
tilage— which forms the principal part of the pinna. We are
supposing, in the description of the muscles which move it,
that this pinna has its opening directed outwards.

The external tempore - auricular, which recalls, from
its situation, the superior auricular of man, is an adductor
of the ear ; besides, it causes it to describe a movement of
rotation from without inwards, so as to direct its opening
forwards.

Scuto-auricularis Externus. — This muscle may be con-
sidered as supplementary to the external temporo-auricular ;
the concha fasciculus of this latter partly covers it.

Extending from the scutiform cartilage to the inner side
of the concha, it contributes to the movement of rotation
by which the opening of the pinna of the ear is directed
forwards.

rCervico - auricular Muscles (Fig. 92, 13). — These
muscles, three in number, are situated behind the pinna of
the ear ; they are called, from their mode of superposition,
the superficial, middle, and deep.

These arise, all three, from the superior cervical ligament,
and pass from there towards the cartilage of the concha.
They recall, as regards situation, the posterior auricular
muscle of man.

16 — 2

244 THE ARTISTIC ANATOMY OF ANIMALS

Superficial Cervico-auricular {Cervico-auricularis supe-
rior is). — This muscle, inserted into the posterior surface of
the concha, draws this cartilage backwards and downwards.

Middle Cervico-auricular {Cervico-auricularis medius). —
Situated between the two other muscles of the same group,
it proceeds, after having covered the superior extremity of
the parotid gland, to be inserted into the external part of
the base of the concha. It determines the rotation of this
concha in such a way as to direct the opening of the ear
backwards.

Deep Cervico-auricular {Cervico-auricularis inferior is).
— Covered by the preceding muscle and the superior por-
tion of the parotid, it is inserted into the base of the pinna
of the ear, and has the same action as the middle cervico-
auricular.

Parotido-auricularis (Fig. 92, 15). — This is a long and
thin fleshy band which arises from the external surface of
the parotid gland, and tapering as it passes upwards
towards the pinna of the ear, is inserted into the external
surface of the base of the concha, below the inferior part of
the angle of reunion of the two borders which limit its
opening.

It inclines the pinna outwards ; it is, accordingly, an
abductor of the pinna.

Temporo-auricularis Internus. — This muscle is covered
by the external temporo-auricular and the superior cervico-
auricular. It arises from the parietal crest, and is inserted
into the internal surface of the concha. It is an adductor
of the pinna of the ear.

There are, finally, an internal scuto-auricular muscle and
a tympano-auricular ; but they do not present any interest
for us ; we can simply confine ourselves to making mention
of them.

In the ox, because of the situation of the temporal fossa
and the fact that the external temporo-auricular muscle is
applied, as in the horse, over the muscle which this fossa
contains, this temporo-auricular muscle does not reach the
middle line (Fig. 91, 12).

But in the cat and the dog this muscle covers all the upper

MYOLOGY 245

part of the head (Fig. 90, 12). It is divided into two parts :
the interscutellar and the fronto-scutellar.

The interscutellar is a single muscle, thin and broad,
covering the temporal muscle and a portion of the occipital,
extending from the scutiform cartilage of the pinna of one
side to the same cartilage of the pinna belonging to the side
opposite. It approximates the two pinnae to one another
by bringing them each into the position of adduction.

The fronto-scutellar arises from the orbital process of the
frontal bone, and from the orbital ligament, which at this
level completes the interrupted osseous boundary of the
orbital cavity. Thence it is directed, widening as it proceeds,
towards the scutiform cartilage, and is there inserted by
blending with the corresponding part of the great zygomatic.
Its action is analogous to that of the preceding muscle ; but,
further, it directs the opening of the pinna forwards.

These are the muscles which act, for example, when the dog,
having his attention strongly attracted by any cause, pricks
up his ears and turns the openings forward, in order the better
to understand every sound which proceeds, or may possibly
proceed, from that which he observes. From this, which
may be extremely well seen in some individuals, results the
appearance of vertical wrinkles of the skin in the interval
between the pinnae of the ears, these being caused by the
folding of the integument, whilst the pinnae approach one
another. These movements, with which are associated
fixation of look and a widening of the palpebral fissure,
produce a peculiarly expressive look ; this is why they
merit our attention.

Zygomatico-auricularis (Fig. 90, 11). — Arises from the
internal surface of the great zygomatic, passes towards the
pinna of the ear, and goes to be inserted into the external
part of the base of the pinna, below its opening, to a promin-
ence which corresponds to the antitragus of the human ear.
It is to this antitragus, but proceeding from another
direction, that the parotido-auricular muscle is inserted
(Fig. 90, 15).

With regard to the cervico-auriculars, they are all three
present. The superior, or superficial, situated behind the

246 THE ARTISTIC ANATOMY OF ANIMALS

interscutellar portion of the external temporo-auricular, has
its origin on the median line of the neck ; thence it passes
towards the pinna of the ear, blending its fibres with those
of the interscutellar muscle, and is inserted into the scuti-
form cartilage and the internal surface of the pinna.

Such are the principal muscles of the ear in the carnivora ;
it would seem to us superfluous to dwell on the others of this
region, so that we will here conclude the study of the
muscles in general, and that of the myology of the head in
particular.

CHAPTER III

EPIDERMIC PRODUCTS OF THE TERMINAL
EXTREMITIES OF THE FORE AND HIND LIMBS

We will first recall to mind that among the quadrupeds
some are found of which the fingers and toes have their
third phalanges terminated by claws — these are the un-
guiculates ; and that in others the terminal extremity of
each limb is completely encased in a horny envelope, the
hoof — these are the ungulates.

In the first group, the claws remind us to a certain extent
of the arrangement of the nails in man ; the inferior aspect
of the paws is covered by an epidermic layer, thick and pro-
tective, which may be likened to the skin, correspondingly
thick, which covers in the greater part of its extent the
plantar surface of the foot in the human species.

In the second group, the surface by which the third
phalanx rests on the ground is correspondingly protected,
but this time by a layer of horn which belongs to the hoof.

After the preceding remarks, our study will be found to fall
into a natural division, and it is in the order which we have
just followed for the purpose of indicating its existence that
we now proceed to study the nature and form of the different
elements which complete or protect the digital extremities
of the thoracic and abdominal limbs.

Claws. — These horny coverings of the third phalanges,
which we have to consider only in the dog and cat, may be
compared with the nails of man, with which, however, they
present, as is well understood, characteristic differences.

The claws are compressed laterally, curved on themselves,
and are terminated in front by a sharp point in the felide,

247

248 THE ARTISTIC ANATOMY OF ANIMALS

but more blunted in the dog. Their superior border is
convex and thick. We may say, therefore, that a claw is
a sort of hollow tube, in the form of a cone flattened in the
transverse direction, in which the third phalanx is set, and
which is itself set in a groove formed by a kind of osseous
hood which occupies the base of this third phalanx (see

Fig- 37' P- 57)-

This definition is exact, as regards the general appear-
ance ; but, when more closely scrutinized, it is not
sufficient. The tube in question is not formed of a single
piece ; each of the claws is formed by a lamina later-
ally folded, but of which the borders are not exactly
joined together inferiorly ; they leave between them a
small interval, and this is filled by a layer of more friable
horny substance, to which has been given the name of
plantar nail. This arrangement, which is clearly defined
in the dog (Fig. 93), is comparable to that which we shall
afterwards meet with in connection with the sole of the
hoof of the horse (see Fig. 100, p. 257). In the dog and
the cat, the weight of the limb resting on the inferior
surface of the phalanges, it was necessary that the region
of the plantar surface of the foot corresponding to these
latter should be protected ; this is the function of certain
fibro-adipose pads, which are situated there, and which
are designated by the name of plantar tubercles.

Plantar Tubercles (Fig. 94). — These tubercles, or dermic
cushions, are divided, in each paw, into tubercles of the digits
(or of the toes), a plantar tubercle, and, on the fore-limbs, a
tubercle of the carpus.

The tubercles of the fingers (or of the toes) are of the same
number as the latter. That which belongs to the thumb
is but little developed, but the others are more so. They
are in relation with the plantar surfaces of the second and
third phalanges, so that when the paw is in contact with
the ground the articulation which, in each of the fingers or
toes, joins these phalanges, rests on the corresponding pad.

The plantar tubercle is larger than the preceding. It is
of a more or less rounded form ; sometimes it is triangular,
and then comparable in outline to the ace of hearts, the point

EPIDERMIC PRODUCTS

249

of which is, in this case, turned towards the claws ; its
margin being sometimes strongly indented, it may also have
a trilobate form. It is on it that rest the metacarpo-
phalangeal or metatarso-phalangeal articulations, according
to the limb studied. The tubercle of the carpus, situated
at the level of the posterior surface of this latter, is less
important than the preceding, the region which it occupies

'ii

Fig. 93. — Claw of the Dog:
Inferior Surface.

I , Horny lamina of the claw :
2, plantar nail ; 3, tubercle of
the corresponding digit.

Fig. 94. — Left Hand of the Dog : In-
ferior Surface, Plantar Tuber-
cles.

I, I, I, I, I, Tubercles of the fingers ;
2, plantar tubercle ; 3, tubercle of the
carpus.

not reaching the ground during walking. But it is not to
be neglected from the point of view of external form, because
of the prominence which it produces.

In the ungulates the terminal extremity of the limb is,
as we have above pointed out, enclosed in a homy envelope
which is no other than the hoof.

We will first study the hoof of the horse — a hoof which

250 THE ARTISTIC ANATOMY OF ANIMALS

is single for each of the limbs, inasmuch as in this animal
each of these has but a single digit.

Hoofs of the Solipeds. — We will first study the hoof as
regarded in a general way — that is, without taking into
account the limb to which it belongs. We wiU. afterwards
point out the differences presented when the hoofs of the
fore and hind limbs are compared.

In connection with the external forms of the horse, the
study which we are now commencing is of great importance.
But, before entering upon it, it appears to us necessary to
rapidly examine what the hoof contains (Fig. 95).

Fig. 95. — Vertical Antero-posterior Section of the Foot of a

Horse.

I, Third phalanx; 2, fibro-cartilage ; 3, podophyllous tissue; 4, in-
ferior part of the wall ; 5, section of the wall of the hoof ; 6, cutigerous
cavity; 7, tendon of the anterior extensor of the phalanges; 8, rein-
forcing band coming from the suspensory ligament of the fetlock ;
9, tendon of the superficial flexor of the phalanges ; 10, tendon of the deep
flexor of the phalanges.

In the interior of this horny box we find the third phalanx,
a small sesamoid bone placed opposite to the posterior border
of the latter, a portion of the inferior extremity of the second
phalanx, and the tendons, which terminate at this region.

To the third phalanx are added two fibro-cartilaginous
plates, flattened iateraUy, which prolong backwards the bone
to which they are annexed. The inferior border of each of
these fibro-cartilages is fixed by its anterior part to two
osseous prominences situated at each of the angles which
terminate the small phalanx behind ; these prominences

EPIDERMIC PRODUCTS 251

are : the basilar process and the retrorsal process (Fig. 96) ;
by its posterior part, this border is continuous with a
structure known as the plantar cushion (see further on).

The posterior border is directed obliquely upwards and
forwards. The superior border, which is convex or recti-
linear, is thin, and is separated from the posterior border by
an obtuse angle. Finally, the anterior border, which is
directed obliquely downwards and backwards, is united to
the ligamentous apparatus, which keeps the second and third
phalanges in contact.

These fibro-cartilages, at their upper extremities, project
beyond the hoof, and therefore assist in the formation of
the lateral regions of the foot,* at the part which is
called the crown. They project less above the hoof in the
posterior limbs.

Fig. 96. — Third Phalanx of the Horse : Left Anterior Limc,

External Surface.

I, Pyramidal eminence; 2, surface, for articulation with the inferior
extremity of the second phalanx ; 3, basilar process ; 4, retrorsal
process.

The posterior and inferior borders of these cartilages
meet at an acute angle. The angle so formed, or cartila-
ginous bulb, constitutes the base of the region, which is
commonly called the heel — a part of the foot which, as
its name implies, is situated posteriorly, but which we
must not confound, as we might be led to do, with the
region occupied by the calcaneum. We know from our

* Here, for the first time, apropos of the hoof, we use the word ' foot.'
As in osteology and in myology we have, for the sake of clearness of com-
parison, designated under this name the region limited above by the tarsus,
it is necessary to point out here that we employ the same word for a more
restricted region. This we did in conformity with the usage of veterinarians,
who so designate the region of the hoof. It is necessary to explain this
double employment of the word, and, further, to show the particular
meaning ascribed to it.

252 THE ARTISTIC ANATOMY OF ANIMALS

previous studies of comparative osteology that this latter
is situated much higher up.

The plantar cushion is a sort of fibrous wedge which
occupies the interval bounded by the fibro-cartilaginous
plates which we have just been studying. Its inferior surface,
the form of which we shall lind to be reproduced by a
portion of the corresponding surface of the hoof, is pro-
longed anteriorly into a point, while behind it is divided into
two branches, which, diverging from one another, join the
posterior angles of the iibro-cartilages. These two branches
are separated by a median excavation.

The different constituent elements which we have just
been discussing give elasticity to the foot.

To finish the examination of the parts contained in the
hoof, we will add that among them is also found what is
called the fleshy envelope, or fiesh of the foot.

We divide the latter into three regions : the podophyllous
tissue, striated or laminated flesh which is spread out over
the anterior surface of the third phalanx ; the pad, or the
hardened skin which corresponds to the upper border of the
hoof, and forms a prominence above the podophyllous
tissue ; and the villous flesh, or velvety tissue which covers
the plantar surface of the third phalanx and the plantar
cushion. These three tissues form as a whole the kerato-
genic membrane — that is to say, that which produces horny
tissue, and consequently regenerates the hoof.

It is this latter that we now proceed to study.

When we examine its anterior surface or the opposite one,
the hoof of the horse has the shape of a truncated cone
with the base below and the summit cut off obliquely
downwards and backwards (Fig. 97).

Viewed on one of its lateral aspects, it may be compared
to a truncated cylinder placed on the surface of the section
(Fig. 98). We particularly call attention to this latter com-
parison, for it singularly aids us in making a representation
of the foot of the horse when viewed laterally.

Notwithstanding that the hoof forms apparently a homo-
geneous whole, it consists of three parts, which may be
separated from one another by maceration. The indication

EPIDERMIC PRODUCTS

25

o

of such disunion, artificially produced, may seem useless.
It is not so, however, for this division of the hoof will
permit us to carry out the study of the latter in a clearer, and
consequently a more satisfactory, way. The three parts in
question are the wall, or crust, the sole, and the frog.

The wall is that portion of the hoof which we see when the
foot rests on the ground. It is a plate of horn which,
appUed to the anterior and lateral surfaces of the foot,
diminishes in height as it approaches the posterior part of the
region. Posteriorly and at each side the wall is folded on

ll,/'''"'''!i'

'™ -H.l'

Fig. 97. — Left Anterior Foot of the Horse : Anterior Aspect.

I, Outer side ; 2, inner side.

itself, and is then directed forwards to terminate in a point,
after having enclosed the frog, which we will soon study.

Although the wall forms a continuous whole, it has been
divided into regions to which special names are given. The
anterior part, from the superior border to the inferior, is
called the pince or toe for a width of 4 to 5 centimetres.
External to the toe, and on each side of it, for a distance
of 3 or 4 centimetres, is the nipple. Behind the nipples are
the quarters. Still further back, where the wall folds on
itself, forming the buttress, is found the region of the heels.

254 THE ARTISTIC ANATOMY OF ANIMALS

Finally, the portions of the wall which form its continuation
in passing forward are called the bars* These are only
visible on the inferior surface of the hoof (see Fig. lOo).

The wall, convex transversely, is, in its anterior part (viz.,
the toe) inclined strongly downwards and forwards. This
obliquity tends to become gradually effaced on the lateral
parts to such a degree that at the quarters it becomes
almost perpendicular to the surface of the ground.

The internal quarter is less rounded than the external ;
in addition to this (Fig. 97), it approaches more nearly to the
vertical direction.

Fig. 98. — Left Anterior Foot of the Horse : External Aspect.

I, Fetlock ; 2, spur or beard ; 3, pastern; 4, outline determined by the
epternal fibro-cartilage ; 5, acute angle ; 6, nipple ; 7, quarter ; 8, heel.

In our opinion, this latter difference clearly recalls certain
characters of the general form of the human foot. In fact,
the latter has its dorsal surface inclined downwards and
outwards, whereas its internal border may be said rather to
be vertical. A transverse section of the foot (Fig. 99) justifies
this comparison, which to us appears interesting, not only

* It is to the angle of inflexion or heel that some authors give the name
of buttress; it is the bars which other authors designate in this fashion.

EPIDERMIC PRODUCTS 255

as regards the resemblance which exists between these
organs of support, but, further, because it constitutes a
mnemonic which enables us, on condition that we remember
the form of the human foot, to recall the above-described
character of that of the horse.

The greater convexity of the outer portion of the hoof is
found equally on the human foot ; the external border of
this foot is more convex than the opposite one.

The inferior border of the wall (Fig. 100) is, in the case of
unshod horses, always in wear when in contact with the
ground. It is intimately united to the circumference of the
sole (see further on).

The superior border is hollowed on its internal surface by
a groove, the cutigerous cavity or basil, which lodges the

A

A'

Fig. 99. — Vertical and Transverse Section of a Left Human Foot :
Outline of the Divided Surface of the Posterior Segment
OF THIS Section (Diagrammatic Figure).

A A', Vertical axis passing through the middle of the leg and the second
toe ; I, outer side ; 2, inner side.

cushion (see Fig. 95). We have described this latter above,
in connection with the flesh of the foot.

The substance of the wall presents a fibrous appearance
which is pretty strongly pronounced. The constituent
fibres from which this appearance results are directed
from the superior border towards the inferior in parallel and
regular lines.

The sole is a horny plate which occupies the inferior surface
of the hoof (Fig. 100). It is situated between the inferior
border of the wall and the bars ; and, on account of the
oblique direction of these latter, it presents a strongly-
marked groove of a V-form, with the opening directed back-
wards. In this depression is lodged the frog.

256 THE ARTISTIC ANATOMY OF ANIMALS

The inferior surface is concave, and thus forms a sort of
vault, more or less deep, according to the individual. The
sole has a scaly, laminated aspect.

We have seen (Fig. 93, and p. 249) that on the inferior sur-
face of the claws of carnivora is found a small interval which
is filled by a plate of a more friable homy substance, to which
has been given the name of the plantar nail. It seems to us
that there is an interesting relationship between the said
plantar nail and the sole which we have just been studying.

Indeed, these two horny structures appear to be homolo-
gous. Is not the lamina of the claw comparable to the

Fig. 100.

EJk.C.
-Inferior Surface of a Fore-hoof of the Horse : Left Side.

I, Internal border of the wall (toe) ; 2, wall ; 3, quarter ; 4, heel ; 5,
bar; 6, sole; 7, frog; 8, median cavity; 9, prominence of the frog;
10, lateral cavity.

wall of the hoof ? And does not the interval which occurs
at the inferior part of this latter, and is fiUed by the sole,
recall that which, in extremely reduced form, is filled by
the plantar portion of the claws ?

The frog (Fig. 100) is a mass of horn, in form of a wedge,
with its apex in front, which occupies the space limited
laterally by the recurved portions of the wall (the bars) and
the posterior border of the sole.

It covers the plantar cushion previously described (p. 252)
and reproduces its form.

EPIDERMIC PRODUCTS

257

Its inferior surface is hoUowed out in the middle by an
excavation, which is known as the median lacuna. This
cavity separates the branches of the frog, which ter-
minate posteriorly by two swellings which are known as the
■prominences of the frog, forming two rounded elevations
situated above the claws. These same branches unite in
front of the median lacuna to form the body of the frog.
This latter, in its anterior part, gradually narrows, and
terminates in a point which occupies the bottom of the
hollow limited laterally by the bars of the wall and the
posterior border of the sole.

Between the lateral surfaces of the frog and the bars
are found two angular cavities — the lateral lacuncp,, or the
cofnmissures of the frog.

Fig. ioi. — Third Phalanx of
THE Horse : Left Anterior
Limb, Inferior View.

I, External border; 2, internal
border ; 3, semilunar crest ; 4, 4,
re-entrant processes.

Fig. 102. — Third Phalanx of
the Horse: Left Posterior
Limb, Inferior View.

I, External border ; 2, internal
border; 3, semilunar crest ; 4, 4,
re-entrant processes.

As an indispensable complement to the study which we
have just made, it is necessary to add that the hoofs of the
fore-limbs and those of the hind ones present differences
of form which cannot be ignored — differences which we are
already able to conjecture by looking at the respective third
phalanges which terminate those limbs, and especially at
their inferior surfaces (Figs. loi, 102).

The hoofs of the fore-limbs (see Fig. 100), viewed on their
plantar surface, are more rounded than those of the hind-
limbs (Fig. 103) — so that their external contour may be
compared to a semicircle — whilst the hind-hoofs, which are

17

258 THE ARTISTIC ANATOMY OF ANIMALS

narrow and of more oval shape, rather recall by their form
the aspect of an ogive.

This seems to result from the fact that the fore-limbs sup-
port the more considerable part of the weight of the animal.
The best proof which can be given of this overweighting is
the eagerness with which very often, when a horse is stopped
near the edge of a footpath, for example, he places his fore-
feet on the latter. In thus raising his fore-quarters, he
throws part of his weight backwards, and in this way
relieves his fore-hmbs.

With regard to the difference of form which we have
just pointed out, we have sometimes heard the follow-

FiG. 103. — Inferior Surface of a Hind-hoof of a Horse : Left

Side.

I, External border ; 2, internal border.

ing comparison made : the contour of the hoofs of the
fore-limbs, viewed from below, recalls that of an apple ;
that of the hoofs of the hind-limbs recalls the outUne of a
pear.

As a mnemonic this comparison is insufficient, for nothing
connects either of the forms indicated with the region to
which the hoofs belong.

We much prefer one made for us this very year by one of
the students of our course at the School of Fine Arts, after
the lecture in which we had just pointed out the differences

EPIDERMIC PRODUCTS 259

in question. Giving the idea of a semicircle and an ogive,
which we described above, he remarked to us that the idea
would perhaps be more easily fixed in the memory if we
associated with it the idea of the chronological order in
which the Roman and ogival art succeeded. Indeed, as
the Roman art preceded the ogival art, so the hoofs which
have the semicircular form precede those which have the
form of an ogive.

This interpretation appeared to us ingenious ; this is why
we wished to give it here a place which seems to us to be
merited.

Fig. 104. — Left Posterior Foot of a Horse : External Aspect.

The wall of the hoof of a fore-limb, viewed on one of its
lateral surfaces (see Fig. 98), is more oblique than that of one
of the hind-hoofs looked at in the same way (Fig. 104),
This difference, very marked especially at the region of tlie
toe, is correlated with that of the direction of the pastern.
In fact, in the anterior limbs this is a little more obUque
than in the opposite ones.

We have still to describe, in connection with the horse^
some epidermic tissues, which are known as chestnuts.

The chestnut is a small, horny plate which is found on.

17 — 2

26o THE ARTISTIC ANATOMY OF ANIMALS

the internal surface of each of the hmbs, at a level differing
on the anterior from that of the posterior ones.

On the anterior limbs the chestnut is situated on the
internal surface of the forearm, towards the middle part,
or the inferior third of this region. On the posterior limbs
it is developed on the back of the superior extremity of the
internal surface of the canon, towards the inferior part of
the ham — that is, the tarsus.

E^.C.

Fig. 105. — Foot of the Ox : Left Side, Antero-external View.
i.^Internal hoof; 2, external hoof; 3, internal surface of this latter;

.4., internal spur.

Inasmuch as some authors consider the chestnuts as being
vestiges of the thumb and the great -toe, we propose giving
a mnemonic which wall enable us to remember their situa-
tion, or, rather, their difference of level.

If we consider that the thumb, in the human species, is
longer than the first toe, we may easily remember that the
chestnut is placed higher in the anterior limbs than in the

EPIDERMIC PRODUCTS 261

posterior ones. Indeed, if we suppose a digit taking its
origin at these points, it will be longer in front (the thumb)
than behind (the first toe).

Hoofs of the Ox and the Pig. — The ox has four hoofs
on each foot — two which contain the third phalanges, and
two others, rudimentary, situated at the posterior aspect
of the limb, at the level of the inferior part of the canon ;
these latter bear the name of spurs. We will occupy our-
selves especially with the former (Fig. 105).

Each of the hoofs presents three faces which, if we consider
them in relation to the median axis of the limb to which they
belong, are : external, internal, and inferior. The external
surface resembles the wall of the hoof of the horse. The
internal surface is slightly concave from before backwards,
so that the external and internal hoofs of the same foot are
not in contact with each other, except by the extremities
of this surface, and that an interval separates them between
these two points. The inferior surface, slightly depressed,
ends behind in a swelling produced by the plantar cushion,
which covers a thin lamina of horn.

At the anterior part of the hoof these three surfaces unite
in forming a well-marked angle which, on account of the con-
cavity of the internal surface, is slightly curved towards the
axis of the foot.

The pig has also four hoofs — two for the great digits and
two for the lateral digits. They recall those of the ox.

CHAPTER IV

PROPORTIONS

Inasmuch as we have taken for granted, in connection with
the present volume, that before entering on the study of the
anatomy of quadrupeds the reader was prepared for it by a
sufficient knowledge of human anatomy, it is quite natural
that we should extend the same supposition to the study of
proportions.

For this reason, the definition of proportions, considered
from a general point of view, their signification, their
function and their utility, are questions which it would
be superfluous to enter upon here. We will content
ourselves by calUng to mind that the common measure
chosen by preference is the length of the head, and that,
ordinarily, it is with it that we compare the dimensions of
other parts.

Among the animals whose structure we have examined,
there is one of which the proportions deserve to be marked
in preference to every other : this is the horse.

Wherefore this preference ? In the first place, it is because
of the overwhelming position which this animal occupies in
the artistic representation of quadrupeds ; that it is more
frequently associated with man ; that, notwithstanding
its division into different races, its general proportions may
be referred to a special type.

It is also because the indications relative to these propor-
tions will suffice to show the way which the artist must
foUow in order to find for himself, at the time when the neces-
sity for it arises, the proportions which characterize the
other animals.

262

PROPORTIONS 263

Our intention is not, in connection with the subject which
now occupies us, to enter into a deep discussion on the
various opinions which have been set forth. We desire,
above all, to give some indications which, from the practical
point of view, can be utilized in the representation of the
horse, and at the beginning to demonstrate the advantages
of these indications. Now, there is a fact which we have had
occasion to note ; it is the following : almost invariably,
when a person who is little accustomed to represent the
horse, or not previously informed of certain proportions of
lengths, begins to draw from nature, the error generally
committed is that of making the head too small and the
body too long. Is it a preconceived idea which is the cause
that one regards them in this manner ? Perhaps. At all
events, certain artists who have made the representation
of horses their special study have even had this habit.
It is therefore necessary to be informed of the propor-
tions ; this is the object of the study which we are now
undertaking.

Bourgelat,* in the eighteenth century, fixed for the
first time and in complete fashion the proportions of the
horse ; it is he, consequently, who created the aesthetics
of the horse. It is but justice to recall the fact. His
system has a point of analogy with that which is employed to
determine the human proportions. Indeed, Bourgelat chose
the length of the head as a standard of measurement, and the
subdivisions of the head for measures of less extent. ' Since
beauty,' said he,t ' resides in the congruity and proportion
of the parts, it is absolutely necessary to observe the dimen-
sions, individual and relative, and in order to acquire a
knowledge of the proportions, to assume a kind of measure
which can be indiscriminately common for all horses. The
part which can serve as a standard of proportion for all the
others is the head. Take a measurement between two
parallel lines — one tangent to the nape of the neck or the

* Claude Bourgelat, founder of the veterinary schools in France. He
was born at Lyons in 1712, and died at Paris in 1779.

t Bourgelat, ' Elements de I'art veterinaire. Traite de la conforma-
tion exterieure du cheval,' Paris, edition of 1785, p. 133.

264 THE ARTISTIC ANATOMY OF ANIMALS

summit of the forelock, the other tangent to the extremity
of the anterior lip — a line perpendicular to these two
tangents will give you its geometrical length. Divide this
length into three portions, and give to these three parts a
special name, which may be applied indefinitely to all
heads — as, for example, that of prime. Any head whatso-
ever will, accordingly, in its geometrical length, always have
three primes : but all the parts which you will have to con-
sider, whether in their length, in their height, or in their
width, cannot constantly have either one prime, or a prime
and a half, or three primes ; subdivide, then, each prime
into three equal parts, which you wiU name seconds, and as
this subdivision will not suffice to give you a just measure of
all the parts, subdivide anew each second into twenty-four
points, so that a head divided into three primes will have, by
the second division, nine seconds, and two hundred and
sixteen points by the last.'

But where this system appears to us to have lost somewhat
of its unity is when the author transforms it, in pointing out
the following mode of procedure : ' But the head itself may
err by default of proportion. This part is not, indeed, con-
sidered as either too short or too long, too thin or too thick,
but by comparison with the body of the animal. Now, the
body, being required to have — whether in length, reckoning
from the point of the arm to the prominence of the
buttock, or in height, reckoning from the summit of the
withers to the ground — two heads and a half ; whenever
the head, by its geometrical length, shall give, in length or
in height, to the body measured more than two and a half
times its own length, it will be too short ; and if it gives
less, it will be too long.

' In the case in which one of these faults exists there would
be no further question of establishing by its geometrical
length the proportions of the other parts. Give up this
common measure, and measure the height or the length of
the body ; divide the length or the height into five equal
portions ; take, then, two of these divisions, divide them
into primes, seconds, and points, corresponding to the divisions
and subdivisions which you would have made of the head,

Fig. io6. — The Proportions of the Horse (after Bourgei at).

Tojace p. 265.

PROPORTIONS 265

and you will have a common measure, such as the head
would have given you if it had been proportionate.'*

We understand, up to a certain point, that Bourgelat may
have been able to give this advice which, generally speak-
ing, is sufficiently practical, since, in certain cases, he was
able to pronounce that such a head was too small or too
large. But it is always mischievous, with regard to the
effect produced on the reader, to propose to him, in the
application of a rule, to suppress the foundation on which
this rule is estabhshed. Besides, even if all the measure-
ments compared with the two-fifths of the length of the body
are proportionate with regard to one another, the animal,
in spite of this, since the head must be taken into considera
tion, will, in a strict sense, be none the less disproportioned.

The proportions given by Bourgelat are as foUows"}-
(Fig. 106) :

1. Three geometrical lengths of the head give :

The full height of the horse, reckoned from the forelock
to the ground on which he rests, provided that the head be
well placed. J

2. Two heads and a half (B)§ equals :

The height of the body from the summit of the withers to
the ground.

The length of the same body, those of the forehand and of
the hind-quarter taken as a whole from the point of the
arm to the point of the buttock inclusive.

3. An entire head (A) gives :

The length of the forepart from the summit of the withers
to the termination of the neck.

The height of the shoulders from the summit of the elbow
to the top of the withers.

The thickness of the body from the middle of the belly to
the middle of the back.

The width from one side to the other.

* Bourgelat, loc. cit., p. 135. | Ibid., p. 136, and onward.

X By ' the head being well placed,' Bourgelat means ' vertically posed,'
the outline of the forehead then coinciding with a vertical line, which at
the other end touches the anterior portion of the nose.

§ The letters in parentheses relate to the corresponding measures
marked by the same letters on the third diagram of Fig. 106.

266 THE ARTISTIC ANATOMY OF ANIMALS

4. A head measured from the top of the forelock to the
commissure of the lips (C). This measurement slightly
curtailed, unless the mouth is very deeply cleft, equals :

The length of the crupper, taken from the superior point
of the anterior angle of the ilium to the tuberosity of the
ischium, forming the point of the buttock.

The width of the crupper or of the haunches, taken from
the inferior points of the angles of the ilia.

The height of the crupper, viewed laterally, taken from the
summit of the posterior angles of the ilia to the point of
the patella, the leg being in a state of rest.

The lateral measure of the posterior limb, from the point
of the patella, to the lateral and salient part of the ham,
to the right of the articulation of the tibia with the
trochlea.

The perpendicular height of the articulation above named
above the ground.

The distance from the point of the arm to the angle
formed by the ] unction of the head and neck.

The distance from the summit of the withers to the junction
of the neck with the thorax.

5. Twice this last measure (C)* gives almost :

The distance of the summit of the withers to the tip of the
patella.

The distance of the point of the elbow to the summit of the
crupper or the posterior angles of the ilia.

6. Three times this measure, plus a half-width of the
pastern, the equivalent of two heads and a half, will
give :

The height of the body, taken from the top of the withers
to the ground.

Its length, taken from the point of the arm to the point
of the buttock inclusive.

7. This same measure, plus the entire width of the
pastern, gives :

The total length of the body, taken accurately.

* The proportions given in the two paragraphs 6 and 7 are, under
another form, the same as those pointed out in paragraph 2, with this
difference, that in this latter they are more clearly expressed.

PROPORTIONS 267

8. Two-thirds the length of the head (D) will equal :
The width of the chest, from the tip of one arm to that of

the other, from outside to outside.

The horizontal measurement of the crupper taken between
two verticals, of which one forms a tangent to the buttock,
and the other passes through the summit of the crupper
and touches the tip of the patella.

The third of the length of the hind-quarter and of the body
taken together, as far as the vertical from the withers,
touching the elbow.

The anterior length of the hind-limb, taken from the tuber-
osity of the tibia to the fold of the ham.

9. One-half of the length of the head (E) is the same as :
The horizontal distance from the tip of the arm to the

vertical line from the summit of the withers and touching
the elbow.

The width of the neck, viewed laterally, taken from its
insertion in the trough of the jaw to the roots of the first
hairs of the mane, on a line which forms with the superior
contour two equal angles.

10. One-third of the entire length of the head (F) gives :
The height of its superior part from the summit of the

forelock to a line which passes through the most salient
points of the orbits.

The width of the head below the lower eyelids.

The lateral width of the forearm, taken from its anterior
origin to the point of the elbow.

11. Two-thirds of this length* (G) gives :

The distance of the point of the elbow above the plane of
the lower surface of the sternum.

The depression of the back in relation to the summit of
th^ withers.

The lateral width of the posterior limbs near the hams.

The space or distance of the forearms from one ars\ to the
opposite.

* That is to say, two-ninths of the whole length of the head.

I We call the region where the superior and internal part of the forearm
is joined to the trunk the ' ars.' The space between the ars of one side
and the ars of the opposite side is called the ' inter-ars.'

268 THE ARTISTIC ANATOMY OF ANIMALS

12. One-half of the third of the entire length of the head *
(H) equals :

The thickness of the forearm, viewed from the front, and
taken horizontally from the ars to its external surface.

The width of the crown of the fore-feet whether from one
side to the other, or from before backwards.

The width of the croivn of the hind-feet, from one side to
the other only.

The width of the posterior fetlocks, taken from the front to
the origin of the spur.

The width of the knee seen from the front. Note : this
measure is a little too large.

The thickness of the ham. Note : this measure is a little
under the mark.

13. One-fourth of the third of the length of the headf
(I) gives :

The thickness of the canon of the fore-limb : that of the
hind-quarter is a little thicker.

14. One-third of this same measurej (K) equals :

The thickness of the fore-limb close to the knee in its
narrowest part.

The thickness of the posterior pasterns, viewed laterally.

15. The height from the elbow to the fold of the knee
(L) is the same as :

The height from this same fold to the earth.

The height from the patella to the fold of the ham.

The height from the fold of the ham to the crown.

16. The sixth part of this measure (M) gives :

The width of the canon of the fore-limb, viewed laterally, in
the middle of its length.

The fetlock, viewed from the front.

17. The third of this same measure (N) is very nearly
equal to :

The width of the ham, from the fold to the point.

18. A fourth of this measure (O) gives :

The width of the knee, measured laterally.

The length of the knee.

* That is to say, one-sixth of the total length of the head.
f That is, one-twelfth of the length of the head.
X That is, a ninth of the length of the head.

PROPORTIONS 269

19. The interval between the eyes from one great angle
to the other (P) equals :

The width of the hind -leg, viewed laterally, from the
cleft of the buttocks to the inferior part of the tuberosity
of the tibia.

20. One-half of this interval between the eyes (^ P)
gives :

The width of the posterior canon-hone, viewed laterally.

The width of the fetlock of the fore-limb, from its anterior
summit to the root of the spur.

Finally, the difference of the height of the crupper with
respect to the summit of the withers.

It is certain that the multiplicity of these proportions,
and above all the exaggeration of details into which
Bourgelat fell in indicating certain of the measures which
constitute the bases of some of them, may repel the
reader.

For this cause we desire to add to the preceding, and
also because the question which we are treating would be
incomplete without it, the results obtained and published
by other more modern authors, and in particular by Colonel
Duhousset.*

This author, one of whose constant occupations is
the measurement of the different regions of the horse,
has the incontestable merit of having drawn attention
to this question, and of having strained all his energies
in the propagation of the knowledge which until then was
little diffused. Among the proportions which he recom-
mends, there are some which are the result of his own
observations ; whilst others, which he has verified and
adopted, are the result of a judicious selection of those
given by Bourgelat, which we have just reproduced in the
preceding pages.

We join thereto also certain indications furnished by
MM. A. Goubeaux and G. Barrier,*!- distinguishing these
latter by the initials (G. and B.) of their authors (Fig. 107). t

* E. Duhousset, ' Le Cheval,' Paris, 1881.

t Armand Goubeaax and Gustave Barrier, ' De I'exterieure du Cheval,'
Paris, 1882.

270 THE ARTISTIC ANATOMY OF ANIMALS

The length of the head almost exactly equals:

1. Depth from the back to the belly, N, O,* the thickness
of the body.f

2. From the summit of the withers to the point of the
arm, H, E.

3. From the superior fold of the stifle to the point of the
ham, J', J.

4. From the point of the ham to the ground, J, K.

5. From the dorsal angle of the scapula to the point of
the haunch, D, D.

jDt-5o»y5'e^

Fig. 107. — Proportions of the Horse (after Colonel

Duhousset).

6. From the passage of the girth to the fetlock, M, I, or
higher in large horses and racers ; to the middle of the
fetlock or lower for small ones and those of medium size.

7. From the superior fold of the stifle to the summit of
the crupper in those specimens whose coxo-femoral angle is

* Look for the points indicated by these letters on Fig. 107, which is
related to the proportions which are here discussed.

I The proportion previously indicated by Bourgelat (see p. 265, para-
graph 3).

PROPORTIONS 271

very open. This distance is always much less in others
(G. and B.).*
Two and a half times the length of the head gives :

1. The height of the withers, H, above the ground. f

2. The height of the summit of the crupper above the
ground. J

3. Very often the length of the body, from the point of
the arm to that of the buttock, although for a long time
the type of Bourgelat had been set aside as a conventional
model, short and massive. §

And M. Duhousset adds to this :

' The drawing that we offer, which has two heads and
a half in height and length, is that of a horse which
we frequently meet with ' (see Fig. 107 ; see also p. 279,
where we again consider this question of the length of the
body of the horse).

' The crupper, from the point of the haunch to that of
the buttock, D, F, is always less than that of the head.
This difference varies from 5 to 10 centimetres. The
width of the crupper, from one haunch to the other, often
very slightly exceeds its length.' MM. Goubeaux and
Barrier add that frequently it equals it.||

' The crupper, such as we have just defined it, D, H, may
also be found to a fair degree of exactness, as regards length,
four times on the same horse.'

* A proportion relative to the same region, and which at the outset
might appear similar, is pointed out by Bourgelat (see p. 266, paragraph 4).
But there exists a difference, for Bourgelat compared the length of the
head, measured from the forelock to the commissure of the lips, and not
that of the entire head, to the distance which separates the summit of
the rump and the tip of the patella.

•]• This proportion is that given by Bourgelat (see p. 265, paragraph 2).

!j Consequently the withers and the crupper, being the same height, are
sTtuated on the same horizontal plane. Bourgelat, on the contrary,
points out a difference of level in connection with these regions. Accord-
ing to him the summit of the crupper is situated below the horizontal plane
passing the withers, and this distance equals half of the space which
separates the great angle of one eye from that of the other (see p. 269.
paragraph 20). § See p. 265, paragraph 2.

II If we refer to the proportions indicated by Bourgelat, we shall find
that the proportions relative to the crupper are also indicated there
(see p. 266, paragraph 4).

272 THE ARTISTIC ANATOMY OF ANIMALS

1. From the point of the buttock to the inferior part of
the stifle, F, P.

2. The width of the neck, a httle in front of the withers
to a little above the point of the arm, S, X.*

3. From this latter point to below the lower jaw, X, Q,
when the head is naturally placed parallel to the shoulders,
E, H.t

4. From the nape to the nostrils, n n'.%

The measure of half of the head also acts as a ^ood
guide for the construction of the horse, when we know that
it frequently applies to many of the parts — to wit :

1. From the forehead above the eyes, perpendicular to the
line which is tangent to the lower jaw, P, Q.

2. Outline of the neck at the level of the base of the head,

3. From the crown of the fore-foot to below the knee,
T, T;

4. In the legs, from the base of the fetlock to that of the
ham, U, V.

5. Finally, it is nearly of the length of the humerus from
the point E to the radius. |i

* MM. Goiibeaux and Barrier reolace this by the following : ' The width of
neck at its inferior attachment from its insertion into the chest to the origin
of the withers, S, X.' Bourgelat discovered the same proportion (see p. 266,
last line of paragraph 4).

f MM. Goubeaux and Barrier replace this by the following : ' From
the insertion of the neck into the chest to the lower border of the lower
jaw, X, Q, when the head is parallel to the shoulder.'

X MM. Goubeaux and Barrier add : ' Or to the commissure of the lips.'
It is thus, besides, that Bourgelat measured the head for comparison with
the crupper (see p. 266, paragraph 4).

§ Proportion indicated by Bourgelat (see p. 267, paragraph 9).

II MM. Goubeaux and Barrier replace these by the following :

1. 'From the most prominent part of the lower jaw to the profile
of the forehead above the eye, P, Q (thickness of the head).

2. ' From the throat to the superior border of the neck behind the nape,
Q, L (attachment of the head).

3. ' From the inferior part of the knee to the crown, T, T'.

4. ' From the base of the ham to the fetlock, U, V.

5. ' Finally, from the point of the arm to the articulation of the elbow
{approximate length of the arm).'

PROPORTIONS 273

PROPORTIONS OF THE HEAD OF THE HORSE*

Although it is very difficult, says M. Duhousset, when we
speak of measurements taken on the living animal, to
formulate other than approximations, we believe we have
determined with sufficient accuracy the following results,
which are the outcome of our numerous observations. The
head which we present is that of a horse which we have
frequently come across as a mean term between the highly
bred and the draught horse. Under this heading, it will not
be devoid of interest to accompany with dimensions the
two drawings to which are consigned the measurements
in question.

Head viewed in Profile (Fig. 108). — Length, A, B,
from the nape to the margin of the lips, o"6o metre.

Thickness, C, D, from the angle of the lower jaw to the
anterior surface (a half -head), 0*30 metre. This line passes
through the middle of the eye, taken perpendicularly, to
the profile of the anterior surface. Many common horses
present it, especially the heavier draught horses ; in finely-
bred subjects it is a little shorter (G. and B.).

Depth, I, H, of the neck in its narrowest part (a half -head),
0*30 metre. It is frequently greater ; this is noticeable
in aU instances where the superior parts of the neck
are deficient in fineness. It is this which we see in
draught horses, and in those which become too fleshy
(G. and B.).

Distance, O, R, of the internal commissure of the eye from
the superior border of the commissure of the nostril (G. and
B.) (a half -head), o"30 metre. It is more considerable on
the common head, and on that which is too long.

Distance, A, O, from the nape to the internal angle of the
eye, o"22 metre. This distance is equivalent to the thick-
ness of the head, P, Q, taken perpendicularly from the profile
of the anterior surface, and passing at the level of the
maxiUary fissure and spine.

* Extract from the work of MM. Goubeaux and Barrier on the exterior
of the horse. As before, the initials G. and B. of these authors are
added.

18

274 THE ARTISTIC ANATOMY OF ANIMALS

It is, again, equal to Q, O, from the internal angle of the
eye to the maxillary fissure ; and to P, G, from the middle
of the face to the commissure of the lips (G. and B.).

The distance, P, E, from the middle of the face to the
maxillary spine is about the sixth of the total length of the
head — o'lo metre.

Fig. io8. — Proportions of the Head of the Horse, viewed in
Profile (after Colonel Duhousset).

The line B, E, reckoned from the extremity of the lips to
the maxillary spine, is equal :

To E, F, from the maxillary spine to the external auditory
meatus, to be seen only on the skull ;

To H, G, from thei nsertion of the neck in the trough to
the commissure of the lips (G. and B.) ;

To Q, R, from the maxillary fissure to the superior com-
missure of the nostril (G. and B.) ;

PROPORTIONS

275

To Q, B, from the fissure of the maxilla to the border of the
lips (G. and B.) ;

To O, D, from the internal angle of the eye to the angle of
the lower jaw, provided that the line C, D be in proportion
(G. and B.).

Finally, very frequently to O, H, from the internal angle

Pig. 109. — The Same Design as that of Fig. 108, on which we have
indicated, by similar lines, the principal corresponding

Measurements.

Half the length of the head, and the dimensions which equal it ; distance
wliich separate the nape from the internal angle of the eye, and the
dimensions which equal it ; distance which separates the internal angle
of the eye from the border of the lips, and the dimensions which equal it.*

of the eye to the insertion of the throat into the maxillary
trough (G. and B.).

* It is thus that in our teaching, but by means of lines of different
colours, we present the proportions reproduced in Fig. 108. Experience has
demonstrated to us that this replacement of letters by conventional lines
renders the proportions more easily appreciable, and that these lines,
striking the eye more forcibly, then impress themselves better on the
memory. Fig. iii bears the same relation to Fig. no.

18—2

276 THE ARTISTIC ANATOMY OF ANIMALS

An equality still more frequent is that which exists between
the distances :

O, B, from the internal angle of the eye to the margin of
the lips ;

A, H, from the nape to the insertion of the throat into the
maxillary trough ;

And H, B, from this latter point to the margins of the lips.

Fig. 1 10. — Proportions of the Head of the Horse, seen from the
Front (after Colonel Duhousset).

The Head, Front View (Fig. no). — If, to continue our
examination, adds M. Duhousset, we regard the head from
the front, we find its greatest width at A, B, the extreme
points of the orbital arches.

This width is 22 centimetres.

It is again equal to :

A, C, from one arch to the nape ;

A, D, from one arch to the middle of the face.

PROPORTIONS

277

D, E, from the middle of the face to the margin of the lips.

From the auditory canal, G, to the maxillary spine, F.
is the same distance as from this point to the margins of the
lips, E, or, better, to the end of the teeth.

Fig. III. — The Same Figure as Fig. iio, on which we have marked
BY Similar Lines the Principal Measurements which corre-
spond THERETO.

Distance which separates one of the orbital arches from that of the
opposite side, and the dimensions which equal it ; distance which separates
the auditory meatus from the maxillary spine, and the dimensions which
equal it ; distance which separates one maxihary spine from that of the
opposite side, and the dimensions which equal it ; distance which separates
the lip of one side_ from that of the opposite, and the dimensions which
equal it.*

The line G, C, from the auditory meatus to the nape, is
equal to the sixth of the head, 10 centimetres ; the Hne A, G,
from the orbital arch to the auditory meatus, is a little
longer, and measures 12 centimetres.

* See the note relative to Fig. 109.

278 THE ARTISTIC ANATOMY OF ANIMALS

The distance F, I, comprised between the maxillary spines,
is i8 centimetres.

It is equal to :

O, O, the distance between the internal angles of the eyes
(G. and B.) ;

F, R, the distance from the maxillary spine to the superior
commissure of the corresponding nostril (G. and. B) ;

F, P, from the maxillary spine to the salt-cellar.'^

From the nape to the internal angle of the eye, C, O, is the
same distance as from this latter point to the commissure
of the lips, O, T ; and from the maxillary spine to the upper
lip F, S (G. and B.).

The distance apart, T, T, of the two commissures of the
lips gives, very nearly, the distance from the superior
border of the orbital arch to the base of the ear or the
auditory meatus. In the state of rest, the outer limit of the
separation of the nostrils does not exceed the width of the
knee ;f we frequently find the same distance intercepted
above the nape by the tranquil ears. In the figure (Fig.
no) we have intentionally represented them directed in
a different plane, in order to show that when the pinna is
turned backward, it none the less preserves the contour
of bracket form, more or less pronounced according to the
breeding of the subject, and characterizing in repose the
interior curves of the ear.

The extreme limit of the lips, M, N, but very slightly
exceeds that of the nostrils ; on many heads of harmonious
proportions this distance is found to be the half of A, B.

In order not to interrupt the course of the preceding exposi-
tion, we decided to withhold tiU afterwards some reflections
which have been suggested to us by certain of the proportions
which are there indicated. The proportions in question are
important — we may even say that they are fundamental, for
they have for object the relation which exists between the
length of the head, the height of the body, and the length
of the latter.

* We designate under the name salt-cellar a depression situated external
to the frontal region and above the eye.

f We remind our readers that the name ' knee ' is given by veterinarians
to the region occupied by the carpus.

PROPORTIONS

279

We have already seen that, according to Bourgelat, the
length of the head is contained two and a half times in the
length of the body, from the point of the arm to the point
of the buttock ; and, also, two and a half times in the
height measured from the apex of the withers to the
ground (see p. 265). We saw afterwards that M. Duhousset,
having adopted these proportions, pointed out, further,
that the same dimension was again found equally to exist
from the summit of the crupper to the ground — a height

Fig. 112. — Horse of 'which the Length contains more than Two
AND A Half Times that of the Head, and of which this
Dimension (A, B) exceeds the Height.

which Bourgelat considered as being of less extent. There
results, then, from the latter proportions, which we have just
recalled, this interesting fact : that they simplify very much,
from the point of view of design, the placing in position o f
the horse, on the condition always that this latter be always
viewed directly on one of its lateral aspects.

Indeed, in this case, if we except the neck and the head, the
body, inasmuch as its height and its length are equal, may be
inscribed in a square, of which one of the sides corresponds
to the withers and to the summit of the crupper, two of the
other sides to the point of the arm and to that of the buttock

28o THE ARTISTIC ANATOMY OF ANIMALS

the fourth being represented by the ground. This is simple,
but this simplicity even has its inconveniences.

It follows that this proportion, thus expressed, seems
to exclude from every artistic representation certain cate-
gories of horses, which upon the whole might be regarded
as beautiful, and the existence of which in any case it would
be a pity not to indicate.

Let us examine at the outset that which is relative to the
length of the body, equal to two and a half times the length
of the head. This proportion is sometimes met with, and
therefore may be considered exact ; but it is necessary to

Ei C

Fig. 113. — Horse of which the Length contains more than Two and
A Half Times that of the Head, and of which this Dimension
(A, B) exceeds the Height.

add that its existence is not discoverable in the majority
of cases. That for some authors it constitutes a perfect
model we wiU not gainsay, but it is our impression that,
when it exists, the head appears a little large, or, more
exactly, the body a little short.

Without attaining exactly to three times the length of the
head, as some authors (Saint-Bel, VaUon) have announced,
the body of the horse, nevertheless, measured as is stated
above, frequently contains it more than two and a half times.
We give in support of this some outline reproductions, exe-
cuted after photographs (Figs. 112, 113, 114).

PROPORTIONS

281

There still remains the question regarding the equality
of the height and of the length of the body of the horse.

This equality, after the proportions previously indicated,
would seem bound to appear in all the cases observed. Now,
if we measure the examples reproduced in Figs. 112, 113,
and 114, we shall see that sometimes the two dimensions
are unequal, the height being greater than the length, or
inversely.

It is the same, if we examine a certain number of speci-

FiG. 114. — Horse of which the Length contains more than Two
AND A Half Times that of the Head, and of which this
Dimension (A, B) is Inferior to the Height.

mens ; we are able to determine that the proportion chosen
in preference by authors is not exactly that which is oftenest
met with. It will, very probably, be objected that it is so
iof the most beautiful types, and that the indifferent ones
af e generally the more numerous. The essential thing would
be to know, above all, if the type of two heads and a half of
length and of height is really the only beautiful one. How-
ever that may be, of the fifty African horses measured by
M. Duhousset, only fourteen possessed the equality indi-
cated ; twenty-six were less long than high, and ten more
long than high.*

* E. Duhousset, ' The Horse,' Paris, 1881.

CHAPTER V

THE PACES OF THE HORSE

As a completion of the studies we have just been making,
some notions relative to the paces of the horse seem to us
to be absolutely indicated.

Let it be permitted to us to remind the reader in this
connection that we have already been for twenty-one years
occupied with this question, and that by means of an
articulated figure, a sort of movable mannikin, we have
endeavoured to demonstrate to artists the differences which
characterize the various paces of the horse.* The arrange-
ment then employed cannot, evidently, be used in the
present volume, but we will inspire ourselves, in the prepara-
tion of the present chapter, with the elements of demonstra-
tion which we have employed, and which, in the course of
our teaching, we have had the satisfaction of seeing favour-
ably received.

The progressive movements by which an individual

* Edouard Cuyer, ' Les Allures du Cheval,' demonstrated with the aid
of a coloured, separable, and articulated table, Paris, 1883.

This table was the subject of a note communicated to the Academy
of Sciences by Professor Marey ('Comptes rendus de I'Academie de
Sciences') at the meeting of June 26, 1882. On the other hand, it has
been the subject of a presentation which we have had the honour of being
permitted to make to the Academy of Fine Arts at the meeting of
November 4, 1882.

The fasciculus in question has been since united with a more complete
whole as regards the study of the horse. E. Cuyer and E. Alex, ' Le
Cheval: Exterieur, Structure et Fonctions, Races,' avec 26 planches
coloriees, decoupees et superposees, Paris, 1886.

THE PACES OF THE HORSE 283

transports himself from one place to another do not operate
according to a unique method and with a constantly
uniform velocity. These various modes of progression are
designated under the name of faces.

It is extremely difficult to analyze, by simple observation,
the movements which characterize these gaits. Let us, for
example, examine the displacements made by the limbs of
a horse during that of walking ; if we have no notion of these
displacements, it will be, so to speak, impossible to deter-
mine in what order they are executed. The sight of the
imprints left on the ground by the hoofs is not a sufficient
means of demonstration, especially for artists. The noise
made by the blows of these limbs, or by the little bells of
different timbre suspended from them, are absolutely in the
same case.

Processes enabling us to fix or to register the paces are
in every way preferable. Such really exist ; they are :
instantaneous photography and those which constitute the
graphic method of Professor Marey. The results given by
the photograph are certainly appreciable ; but, from the
didactic point of view, we give the preference to the graphic
method, the general characters and the mode of application
of which we now proceed to analyze.*

It is necessary to understand first of all, in this connec-
tion, that which relates to a man's walking pace.

The method of Professor Marey rests on the following
principle : Suppose two rubber globes connected with one
another by a tube. If we compress one of these globes, the
air which it contains will be driven into the other, and will
afterwards return when the pressure has ceased. Nothing
more simple, evidently ; but it is necessary to describe it in
detail in order the better to comprehend that which follows :
The walker who is the subject of experiment is furnished
with special shoes (Fig. 115), having thick indiarubber soles,

* We cannot too strongly recommend the reading of the excellent works
which Professor Marey has published, and which have for their object
the study of movements, as well as the exhibition of the procedures which
he has employed. E. J. Marey, 'La Machine Animale,' Paris, 1873;
'La Methode graphique dans les Sciences experimentales,' Paris, 1884;
' Le Vcl des Oiseaux,' Paris, 1890 ; ' Le Mouvement,' Paris, 1894.

284 THE ARTISTIC ANATOMY OF ANIMALS

liollowcd in the interior, so that the whole thus constituted
forms a sort of hollow cushion which is compressed under
the influence of the pressure of the foot on the ground. A
tube which is attached to a registering apparatus, which the
person who is walking carries in his hand, communicates
with this cavity (Fig. ii6). This apparatus is formed of a
metal drum, which is closed at its upper part by a flexible
membrane. Each time that one of the man's feet presses
on the ground, the air contained in the cavity of the sole
of the shoe is driven into the drum, which we have just
mentioned, and the flexible membrane of this drum is
elevated. To this membrane is attached a vertical rod
which supports a horizontal style.
When the membrane, as we have just seen, is elevated,

Fig. 115. — Experimental Shoes, intended to Record the
Pressure of the Foot on the Ground.

the style is lifted, and then descends when the pressure of
the foot ceases. It traces these displacements on a leaf of
paper, the surface of which is covered with a thin layer of
lamp-black, which it removes by its contact ; different parts
of this surface are successively presented to it, the paper
being rolled round a cylinder which is turned on its axis by
means of a clockwork movement. It is necessary to add
that the inscription is made, in the study of the walk of man,
by means of two styles, each corresponding to one of the
feet.

The tracings thus obtained, which are read from left to
right, are sufficiently simple ; but to understand them
properly, it is necessary to remember that the style under-
goes a movement of ascensional displacement during each
pressure of a foot, and that, on the other hand, it descends

THE PACES OF THE HORSE

285

when the latter is separated from the ground. We also see,
on the tracing which it leaves, a line which ascends and then
descends ; the meaning of this is that first the foot presses
on the ground, and is afterwards raised from it.

On the tracing (Fig. 117), the line D relates to the right
foot ; the line G, which is dotted so that it may not be con-
fused with the preceding, corresponds to the left foot. The

Fig. T16. — Runner furnished with the Exploratory and
Registering Apparatus of the Various Paces.

line G first ascends ; the meaning of which is that the left
foot presses on the ground ; afterwards it descends : this
indicates that the pressure of the foot has ceased. It is the
same for the right foot. As we see, the pressures succeed
each other ; when the left foot touches the ground, the right
is separated from it ; when the latter presses the ground,
it is the left which no longer rests there.
The line O is related to the movements ot the body, as

286 THE ARTISTIC ANATOMY OF ANIMALS

indicated by the oscillations of the head. We will neglect
these.

But this tracing, which serves us for an example, is not,
it must indeed be said, of very easy reading ; it would be
still less so if the paces of a horse were registered, for there
would then be four lines, the entanglement of which would
cause greater complication.

These difficulties of reading need be no longer feared, if
we transform the tracing into a notation by means of the
following diagram.

There are drawn (Fig. ii8) below the graphic tracing two
horizontal lines (i, 2). From the point where the line D
rises (commencement of the pressure of the right foot), and

Fig. 117. — Tracing of the Running of a Man (after
Professor Marey.)

D, Pressures and elevations of the right foot ; G, pressures and elevations

of the left foot.

from the point where this same line descends (end of the
same pressure), we let fall two vertical lines joining the two
horizontal ones mentioned above. At this plane, and
between the two vertical lines, we mark a broad white one
(a, h). This expresses, by its length, the duration of the
period of pressure of the right foot. In doing the same for
the line G, we obtain for the indication of a pressure of the
left foot an interval of the same kind, in which are marked
cross-lines, or which is tinted gray, in order to avoid all
confusion with the preceding tracing.

This notation can, with sufficient exactitude, be compared
to that which is employed in the musical scale. The hori-
zontal lines I and 2 represent the cofupass. We there also see
notes ; these are the bars indicating the pressure, of which the

THE PACES OF THE HORSE

287

value — that is to say, the duration — is represented by the
length of these bars. It is the same with regard to the in-
tervals of silence : these are expressed by the intervals which
separate the pressures, and correspond to the moments in

Fig. 118.

which, during certain paces, such as running, the body is
raised from the ground. Besides, we see intervals of this
kind on the notation reproduced (Fig. 118) relative to the
running of man.

In order to make the signification of these tracings still

Fig. 119.

better understood, we reproduce four varieties of them
(Fig. 119).

The first notation is that of ordinary walking. The
pressures succeed each other regularly.

288 THE ARTISTIC ANATOMY OF ANIMALS

The second shows what takes place during the ascent of
a staircase. At a certain moment, the weight of the body is
upon both feet at the same time, one of them not quitting
the lower step, until the other is already in contact with
the step above. Accordingly, there is thus produced an
overriding of the pressures.

The third is relative to running, and has already been
represented in Fig. ii8. The pressures of the feet are
separated by the times of suspension.

The fourth also represents running, but in this case
more rapid and characterized by the shorter pressures,
the slightly longer periods of suspension intervals, and the
quicker succession of movements.

Before putting aside the indications relating to the
walking movements of man — indications which it was neces-
sary to give in order to render intelligible those which are
connected with the paces of the horse — we have yet to fix the
value of that which we call ' a step.'

It is generally admitted that a step is constituted by the
series of movements which are produced between the corre-
sponding phases of the action of one foot and that of the
other — for example, between the moment at which the
right foot commences its pressure on the ground and that
at which the left foot commences its own. It is necessary
to adopt here another method of looking at it, and to
regard the preceding as being but a half -step. The step
should then be defined as being constituted by the series
of movements which are executed between two similar
positions of the same foot — as, for example, between the
commencement of a pressure of the right foot and the
similar phase of the following pressure of the same foot.
We shall soon understand the importance of this definition.

Before entering on the details of the paces of the horse,
it is necessary to see how the limbs of the latter oscillate
during the period of a complete step ; or, which is the
same thing, to determine what the displacements are which
a limb executes between two similar positions of its foot.

If we examine one of the limbs during a forward move-
ment of the animal, we see that this limb passes through

THE PACES OF THE HORSE

289

two principal phases : (i) It is raised from the ground ;
{2) it resumes contact with the ground. Each of these
phases is divided into three periods of time, which we
proceed to analyze in connection with the anterior limb.

The foot quits the ground (Fig. 120, c) ; this may be
called lifting ; the limb is obhque in direction downwards
and backwards. This same limb is flexed and carried for-
ward (Fig. 120, B), and, as it is supported by the action of
its flexors, this is the period named suspension ; the hoof
is vertical. Then the limb is carried still further forward,
becoming extended (Fig. 120, A) ; the heel is lowered, and

Fig. 120. — Swing of the Raised Anterior Limb (after G. Colin).*
C, Lifting ; B, suspension ; A, placing.

the foot, being oblique, is directed towards the ground ;
this is the placing.

Then takes place pressure (Fig. 121). The foot has just
been placed on the ground ; the limb is oblique in direction
downwards and forwards ; this we call conimencemejit of the
pressure (Fig. 121, A). Then the body, being carried for-
ward, whilst the hoof, D, is fixed on the ground, the limb
becomes vertical : this stage is mid-pressure (Fig. 121, B).

* G. Colin, ' Traite de Physiolotjie Comparee des Animaux,' third edition,
Paris, 1886.

19

290 THE ARTISTIC ANATOMY OF ANIMALS

Finally, the progression of the body continuing, the limb
becomes oblique downwards and backwards ; it is now at
the termination of pressure (Fig. 121, c), and proceeds to lift
itself anew if another step is to be made.

In conclusion, the inferior extremity of the limb describes,
from its elevation to its being placed on the ground, an arc
of a circle around its superior extremity (Fig. 121, D) ;
whilst, during the pressure, it is its superior extremity
which describes one around its inferior extremity, then fixed
on the ground (Fig. 121, D).

If we simultaneously examine the two fore-limbs, we

Fig. 121. — Swing of the Anterior Limb on the Point of
Pressure (after G. Colin). ^ ^^

A, Commencement of the pressure ; B, centre of the pressure ; C, termina-
tion of the pressure.

remark that when one of them begins its pressure the
other ends it, and vice versa.

As to the hind-limbs, the oscillations are similar to those
of the fore ones. In the second half of the pressure — that
is, when they are passing from the vertical direction (Fig. 122,
A) to extreme obliquity backwards (Fig. 122, C) — the effect
of their action is to give propulsion to the body.

The fore and hind limbs make the same number of steps,
and the steps have the same length.

The limbs of any quadruped— but we make special allusion

THE PACES OF THE HORSE

291

to those of the horse — are divided into groups in the
following manner :

The anterior pair constitutes the anterior biped. The
posterior biped is that formed by the posterior limbs.

The name of lateral biped serves to designate the whole
formed by the two limbs of the same side. The right fore-
limb and the right hind-limb form the right lateral biped.
The two others form the left lateral biped.

A fore-limb and hind-limb belonging to the opposite side
form a diagonal biped, which also takes the name of the fore-

- /
/

c

y

Fig. 122. — Posterior Limb, giving the Impulse (after G. Colin).

A, Commencement of pressure ; B, centre of pressure ; C, termination

of pressure.

limb which forms a part of it. Thus, the right diagonal biped
is formed by the association of the right fore-limb and the
left hind one. The left diagonal biped is, consequently, the
inverse.

It is necessary to remember well these preliminary indica-
tions ; it is the only means of comprehending with facility
that which is about to follow.

Let us first return to the grouping of the limbs. The
denominations anterior and posterior bipeds render clearly

19 — 2

292 THE ARTISTIC ANATOMY OF ANIMALS

perceptible the comparison which consists in regarding a
horse when walking as capable of being represented by two
men marching one behind the other, and making the same
number of steps. According as they move the legs of the
same side at the same time in ' covering the step,' or march
in contretemps step, we find reproduced all the rhythms
which characterize the different paces of the horse.

Professor Marey has studied these paces by a similar
method to that which he adopted for the walking of man,
and which we have already described. He employed hollow
balls fixed under the hoofs, and a registering apparatus
with four styles, each corresponding to one of the limbs.
The tracing obtained is rather complicated, since two sets
of lines are found marked. But a notation similar to

Fig. 123. — Notation of the Ambling Gait in the Horse (after

Professor Marey).

that of which we have spoken can be discovered, and its
exact signification should now be determined. For this
purpose, we have selected the most simple (see Fig. 123).
We there see, placed in two superimposed lines, the
pressure markings of the right feet (white bands), and of
the left feet (gray bands). On the upper line are found
those related to the fore-legs ; the lower lines contain those
associated with the hind-legs. It is, in brief, the super-
position of two notations of the human walking movements.
And seeing that, as we have previously pointed out, we may
make a comparison between a quadruped and two men
placed one behind the other, it is easy to understand the
significance of the superimposed notations, if we accustom
ourselves to look on them as the notations of two bipeds.

To read these notations — that is, to learn to know what
occurs at each of the movements of the pace — it is necessary,
indeed, to remember that they should be examined in

THE PACES OF THE HORSE 293

vertical sections ; it is to each of these sections — of these
vertical divisions — that each of the movements which we
more particularly wish to analyze corresponds.

We proceed to study first the pace of ambling, because it
is the most simple ; we shall then consider the trot, and,
finally, we shall examine that which is the most complicated,
viz., the step.

The Amble. — To give an exact idea of the general
character of the amble, let us fancy the two men whom
we discussed above marching one behind the other and
walking in step — that is, moving the legs of the same side

E\ c
Fig. 124. — The Amble : Right Lateral Pressure.*

simultaneously. They will thus represent the amble, which,
indeed, results from the alternate displacements of the
lateral bipeds ; the limbs of the same side (right or left)
execute the same movements in the same time.

This is what the notation indicates (Fig. 123). We there
see that the pressures of the right fore-foot, marked by the
white bands in the upper range, are exactly superposed on
those of the right hind one, which are marked by a similar
band on the lower hue ; this means that the pressures

* The figures which, in the present study, reproduce the different paces,
have been made from our articulated horse (see the note on p. 282).

294 THE ARTISTIC ANATOMY OF ANIMALS

took place in the same time. We there see also a similar
arrangement of the gray bands, which has a similar signifi-
cance for the left fore and hind feet.

And if we recollect the three phases of pressure (see
p. 289, and Figs. 121, 122), we shall comprehend, in
looking at the diagrams, that, at the initial stage (A),
the limbs are commencing their pressure, and are oblique
downwards and forwards ; that afterwards (B) the two
limbs are vertical, since they are at the middle of the
pressure stage ; and that finally (C) they are oblique
downwards and backwards, for it is then the termination
of their pressure (Fig. 124),

During the time that the right limbs are pressing
■(notation, white bands) the left limbs are raised ; after-

FiG. 125. — Notation of the Gait of the Trot in the Horse
(after Professor Marey).

wards these latter take up the pressure (gray bands), and
then the right limbs are raised in their turn.

During the pace of ambling the weight of the body, which
is wholly sustained by the limbs of one side only, is not
in equilibrium, so that the limbs which are raised return
by a brisk movement to the position of support in order to
re-establish it.

The Trot.— We have just seen that, in order to represent
the amble, the two marchers moved their right limbs
simultaneously, and then their left ones.

Let us suppose now that the hinder man anticipated
by half a pace the movement of the front one, then
wiU be found realized the association and the nature
of the displacements of the hmbs during the pace of the
trot.

By this anticipation of a half-step (we have defined,
p. 288, what is to be understood by the word step), it

THE PACES OF THE HORSE

295

follows that when the marcher who is in front advances
his right leg it is the left leg of the marcher who foUows

l\.C.

Fig. 1 26.— The Trot ; Right Diagonal Pressure.

E.\C.

Fig. 127. — The Trot; Time of Suspension.

him that is carried in the same direction. We should
thus conlcude from this that the trot is characterized
by a succession of displacements of the diagonal bipeds.

296 THE ARTISTIC ANATOMY OF ANIMALS

Indeed, if we examine the notation of this gait (Fig. 125),
we see that with the pressure of the right fore-foot is found
associated the pressure of the left hind-foot. It is, accord-
ingly, a typical diagonal biped (Fig. 126).

But it is necessary to add that these groups of pressures
do not succeed one another without interruption, except
in the slow trot. In the ordinary trot, or in that in which
the animal's strides are very long, the body between each
of the double pressures which we have just been consider-
ing is projected forward with such force that it remains for
an instant separated from the ground. This is what we
designate by the name of time of suspension (Fig. 127). The
notation in this case would be slightly different from that
which we reproduce above, in this sense : that between the
diagonal pressures there then would be found an interval.

L' D'

Fig. 128. — Notation of the Pace of Stepping in the Horse
(after Professor Marey).

L, Right lateral pressure ; D, right diagonal pressure ; L', left lateral
pressure ; D', left diagonal pressure.

since during the time the body is suspended none of the
feet can produce a pressure-mark (see, with regard to
these intervals, the notations of the running of a man,
Fig. 118, and Fig. 119,3,4).

The Walk. — Although slow, a feature which would seem
to make it possible to permit its analysis in a horse when
walking, this pace is difficult to comprehend without
sufficient preliminary study.

We saw above that in order to represent the amble the
marchers had to move the legs of the same side simul-
taneously. We have also just seen that in order to re-
present the trot the marcher at the back had to anticipate
by a half-step. Suppose, now, that this same marcher
anticipates the man in front by a quarter-step only, or by

THE PACES OF THE HORSE

297

a half-pressure period, and thus will be found realized the
order of succession of the limbs in the gait or pace called
the walk. The feet meet the ground one after the other,

Ek.C

Fig. 129. — The Step : Right Lateral Pressure.

El.C.
Fig. 130. — The Step : Right Diagonal Pressure.

smce they are each in advance by half the duration of a
pressure. The strokes are four in number during the period
of a step of this pace ; in the amble and in the trot they do

298 THE ARTISTIC ANATOMY OF ANIMALS

not exceed two, for then the limbs strike the ground in
lateral diagonal pairs.

z\c

Fig. 131. — The Gallop: First Period.

Fig. 132. — The Gallop : Second Period.

v-.\ . C

If we examine the notation of the pace of walking
(Fig. 128), we see that the right fore-foot commences its

THE PACES OF THE HORSE

299

pressure when the right hind-foot is in the middle of its
own, and that the hinder left begins in the middle of that

Fig. 133. — T?iE Gallop: Third Period.

Fig. 134. — The Gallop : Time of Suspension.

of the right fore-foot, and that it is itself at the midst of its
pressure when the left fore-foot touches the ground, etc.

J

00 THE ARTISTIC ANATOMY OF ANIMALS

In a word, the foot-fallings occur in the following order
and at regular intervals — the fore right foot is here con-
sidered as acting first : right fore, left hind, left fore, right
hind, and so on in succession.

As to the nature of the bipeds which succeed one another,
it is easy to understand them by means of the notation.
In reading this from left to right, we see that the associations

Fig. 135. — Notation of the Gallop divided into Three Periods
OF Time (after Professor Marey).

I, First period ; 2, second period ; 3, third period.

of pressure are first made by the two right feet, then by a
right foot and a left one, then by two left feet, and, finally,
by a left and right. It is, accordingly, a succession this time
of lateral and diagonal pressures.

Thus, we find at the start a right lateral pressure
(Fig. 129), next a right diagonal (Fig. 130), then a left lateral ;

Fig. 136. — Notation of the Gallop of Four Periods in the
Horse (after Professor Marey).

I, First period ; 2, second period ; 3, third period ; 4, fourth period.

finally, a left diagonal pressure. It is thus that the initial
letters L, D, L', D' further indicate the notations repre-
sented in Fig. 128.

The Gallop. — The ordinary gallop is a pace of three
phases. The first is characterized by the fact that one
hind-limb alone rests on the ground (Fig. 131) ; in the

THE PACES OF THE HORSE

301

second the animal is on a diagonal support (Fig. 132) ; in
the third it comes down on a fore-limb (Fig. 133). The
body is then raised (Fig. 134), and to this period of sus-
pension succeed anew the three modes of pressure indicated
above.

The gallop is said to be from either right or left. In the
gallop from the right, the right fore-leg is the more fre-
quently in advance of its neighbour ; it is the last to be
placed on the ground. The left foot of the posterior biped
is the one which commences the action.

An entirely opposite arrangement characterizes the
gallop from the left.

The notation reproduced in Fig. 135 corresponds to the

Fig. 137. — Leap of the Hare (after G. Colin).

gallop from the right. It is there seen, as we pointed out
above, that in the first phase the exclusive support of the
left hind-foot takes place (i) ; that afterwards, in the
second, commence simultaneously, the pressures of the left
fore and the right hind foot (2) ; this is the left diagonal
support ; and that finally, in the third, the body comes
down on a fore-limb, which is then the right (3) ; and
that for a moment it is on this limb alone that the animal
rests.

To these three phases on the notation succeeds an
interval ; this is the period of suspension.

The gallop of four phases only differs from the preceding

302 THE ARTISTIC ANATOMY OF ANIMALS

Fi3, 138. — The Leap.

Fig. 139. — The Leap.

THE PACES OF THE HORSE'

303

Fig. 140. — The Leap.

Fis. 1 4 1. —The Leap.

EJ^ C

304 THE ARTISTIC ANATOMY OF ANIMALS

in that the foot-faUings of each diagonal biped occur at
slight intervals, and give distinct sounds. The notation is
reproduced in Fig. 136.

The Leap. — The leap is an act by which the body is
wholly raised from the ground and projected upwards and
forwards to a greater or less distance.

It is prepared for by the flexing of the hind-limbs, which,
by being suddenly extended, project the body, and thus
enable it to pass over an obstacle.

This preparatory arrangement is very remarkable in the
leap of the lion, the cat, and the panther, which execute
springs of great length ; in the horse, in which the leap
is not an habitual mode of progression, this flexion of the
hinder limbs is less marked. With this animal the leap is
generally associated with the gallop ; nevertheless, it is
sometimes made from a stationary position. In observing
the hare or the rabbit, in which the leap is habitual, we
notice (Fig. 137) that the hind-limbs, being extremely
flexed, rest on the ground as far as the calcaneum, are
then straightened by the action of their extensors, become
vertical and then oblique backwards at the moment the
body is thrown forward into space by the sudden extension
of these limbs.

The action of the extensors is energetic and instan-
taneous, and their energy is greater than in ordinary pro-
gression, for it is required to lift the body and to project
it forcibly a more or less considerable distance. It is
the extreme rapidity of this action which enables the
animal to clear an obstacle, for without this condition
the body would be raised, but not separated from the
ground.

First of all, in reaching the obstacle to be cleared, the
horse prepares to leap by taking the attitude of rearing ;
the hind-limbs are flexed and carried under the body, the
fore-quarters are raised, and the different segments of the
fore-limbs are flexed (Fig. 138).

One sudden trigger action produced by the violent con-
traction of the extensors of the hind-legs then takes place,
and the animal is projected forwards, while he flexes the

THE PACES OF THE HORSE

305

fore-legs more and more (Fig. 139). He has then risen above
the obstacle (Fig. 140). Then while he makes the down-

Eik.C.

Fig. 142, — The Leap.

E^.C.

Fig. 143. — The Leap.

ward and forward balancing movement, and points his
fore-limbs in the same direction, he flexes the hind ones

20

3o6 THE ARTISTIC ANATOMY OF ANIMALS

(Fig. 141). Whilst the latter are further flexed, in order to pass
the obstacle in their turn, the fore-limbs which are extended
come into contact with the ground (Fig. 142). Finally, in
the last phase of the leap, the animal, raising himself in
front, after the impact of his hind-feet has taken place
(Fig. 143), prepares to continue the pace at which he
progressed before meeting the obstacle which he had to
clear.

THE END

London : Bailliire, Tindall and Co.x, 3, Henrietta Street, Covent Garden, W.C.

THE

ARTISTIC ANATOMY OF ANIMALS

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SECTIONAL INDEX

PAGE

Generalities of Comparative Anatomy ... ... ••. i

OSTEOLOGY AND ARTHROLOGY

The Trunk :

Vertebral Cohntin .. ... ... ••• ••• 4

Sacrum ... ... ... .■■ ... ••• 1°

Coccygeal vertebrae ... ... ... ... •■• n

Direction and form of the vertebral column ... ... n

Thorax ... ... ... ... ••• ••• ^-

Sternum ... ... ... ... ••• ••• I4

Ribs and costal cartilages ... ... ... ••• I4

The Anterior Limbs :

Shoulder ... ... ... ... ... ••• 20

Scapula ... ... ... ... •-• ••• 21

Clavicle ... ... ... ... ... ••• 25

Ar>Ji ... ... ... ... ... ... ■•• 28

Humerus ... ... ... .. ... ••■ 28

General view of the form of the forearm and hand ... ... 34

Forearm ... ... ... ... ... ... 3^

Hand ... ... ... ... ... ... 44

The Anterior Limbs in Certain Animals :

Phuitigrades : Bear ... ... ... ... ... 49

Digitigrades : Cat, dog ... ... ... ... ... 5^

Unguligrades : Pig ... ... ... ... ... 57

Sheep, Ox ... ... ... ... ... ... 60

Horse ... ... ... ... ... ... 64

Proportions of the arm, the forearm, and metacarpus ... 7°

Articulations of the anterior limbs... ... ... ... 71

Scapulo-humeral articulation ... ... ... ... 72

Humero-ulnar articulation, or elbow ... ... ... 74

Radio-ulnar articulation ... ... ... ... 75

Articulation of the wrist ... ... ... ... 75

Metacarpo-phalangeal articulations ... ... .. 76

Interphalangeal articulations ... ... ... ... 77

309

310 THE ARTISTIC ANATOMY OF ANIMALS

The Posterior Limbs pack

Pelvis ... ... ... ... ... ... ... 78

Iliac bone ... ... ... ... ... ... 78

The Thii^h ... ... ... ... ... ... 83

Femur ... ... ... ... ... ... 83

Knee-cap ... ... ... ... ... ... 85

The Leg ... ... ... ... ... ... 85

Tibia ... ... ... ... ... ... 86

Fibula ... ... ... ... ... ... 87

The Foot ... ... ... ... ... ... 87

The Posterior Limbs in Some Animals :

Plantigrades: Bear ... ... ... ... ... 90

Digitigrades : Cat, dog ... ... ••. x ••• •■• 9^

Unguligrades : Pig ... ... ... ... ... 94

Sheep, ox ... ... ... ... ... ... 95

Horse ... ... ... ... ... ... 99

Articulations of the posterior limbs ... ... ... 105

Coxo-femoral articulation ... ... ... ... 105

Femorotibial articulation, or knee ... ... ... 106

Tibio-tarsal articulation, and of the bones of the tarsus ... 107
The Head in General, and in Some Animals in Particular :

Direction of the head ... ... ... ... ... 109

The skull ... ... ... ... ... ... 112

The face ... ... ... ... ... ... 118

The skull of birds ... ... ... ... ... 127

MYOLOGY
Muscles of the Trunk :

Pectoralis major ... ... ... ... ... 131

Pectoralis minor ... ... ... ... ... 133

Serratus magnus ... ... ... ... ... 134

Muscles of the Abdomen :

External oblique ... ... ... ... ... 136

Internal oblique ... ... ... ... ... 137

Transversalis abdominis ... ... ... ... ... 138

Rectus abdominis ... ... ... ... ... 138

Pyramidalis abdominis ... ... ... ... ... 139

Muscles of the Back :

Trapezius ... ... ... ... ... ... 140

Latissimus dorsi ... ... ... ... ... 142

Rhomboid ... ... ... ... ... ... 144

The Cutaneous Muscle of the Trunk ... ... ... 147

The Coccygeal Region:

Ischio-coccygeal muscle ... ... ... ... ... 149

Superior sacro-coccygeal muscle ... ... .*. ... 150

SECTIONAL INDEX

311

The Coccygeal Region (contimied) :

I'AGE

Lateral sacro-coccygeal muscle

150

Inferior sacro-coccygeal muscle

150

Muscles of the Neck :

Mastoido-humeralis

150

Sterno-mastoid ...

153

Omo-trachelian ...

155

Levator anguli scapulae ... ... ...

156

Splenius

158

Infrahyoid Muscles:

Sterno-thyroid and sterno-hyoid ...

... 160

Omo-hyoid ...

... 160

Suprahyoid Muscles:

Mylo-hyoid

... 161

Digastric

... 161

Panniculus of the Neck

... 162

Muscles of the Anterior Limbs :

Muscles of the SJioulder ...

... 162

Deltoid

... 162

Subscapularis ... '

... 163

Supraspinatus

... 1 64

Infraspinatus

.. 165

Teres minor ...

166

Teres major

... 166

Panniculus muscle of the shoulder

... 167

Muscles of the Arm

... 168

Anterior region

... 169

Biceps ...

... 169

Brachialis anticus

... 170

Coraco-brachialis

... 1 70

Posterior region

... 171

Triceps

... 171

Supplemental or Accessory Muscle of the Latissi)n

US Dors/ 173

Muscles of the Forearm ...

... 174

Anterior and external region ...

... 176

Supinator longus

... 176

1 First and second external radial ...

... 176

Supinator brevis

... 179

Extensor communis digitorum

... 179

Extensor minimi digiti

... 183

Posterior ulnar ...

... 185

Anconeus

... 185

Long abductor of the thumb

... 186

Short extensor of the thumb

... 187

Long extensor of the thumb

... 187

Proper extensor of the index

... 187

312 THE ARTISTIC ANATOMY OF ANIMALS

Muscles of tJic Forcar})i {continued) : tac-.f

Internal and posterior region ... ... .. ... i88

Pronator teres ... ... ... ... ... 1 88

Flexor carpi radialis ... ... ... ... 189

Palmaris longus... ... ... ... .. 189

Anterior ulnar ... ... ... ... ... 191

Superficial flexor of the digits ... ... ... 193

Long proper flexor of the thumb ... ... ... 197

Pronator quadratus ... ... ... ... 198

Muscles of the Hand ... ... ... ... ... 199

Muscles of the Posterior Limbs :

Muscles of the Pelvis ... ... ... ... ... 200

Gluteus medius ... ... ... ^ ... ... 200

Gluteus maximus ... ... ... ... ... 201

Muscles of the Thigh ... ... ... ... ... 204

Muscles of the posterior region ... ... ... 205

Biceps ... ... ... ... ... ... 205

Semi-tendinosus . . ... ... ... 206

Semi-membranosus ... ... ... ... 207

Muscles of the anterior region ... ... ... 210

Triceps ... ... ... ... ... 210

Tensor fascia lata ... ... ... ... 211

Sartorius ... ... ... ... ... 211

Muscles of the internal region ... ... ... 213

Gracilis ... ... ... .. ... 213

Muscles of the Leg ... ... ... ... •■• 213

Muscles of the anterior region ... ... ... 214

Tibialis anticus ... ... ... ... 214

Extensor proprius poUicis ... ... ... 219

Extensor longus digitorum .. ... ... 219

Peroneus tertius ... ... ... ... 224

Muscles of the external region ... ... ... 224

Peroneus longus ... ... ••• ••■ 224

Peroneus brevis ... ... ... ■•• ■•■ 225

Muscles of the posterior region ... ... ... 227

Gastrocnemius ... ... ... .-. ••• 227

Soleus ... ... ... ... ■■• •■• 228

Plantaris ... ... ••• ••• ••• 228

Popliteus ... ... ... ••• ••• 228

Superficial flexor of the toes ... ... ... 229

Flexor longus digitorum ... ... ... •■• 230

Tibialis posticus ... ... ... ••• 230

Flexor longus pollicis ... ... ... ••• 231

Muscles of the Foot ... ... ■•• •■■ ••• 231

Dorsalis pedis ... ... ••• ••• ... 231

SECTIONAL INDEX 313

PAGE

Muscles of the Head ... ... ... ... ... 232

Masticatory muscles... ... ... ... ... 232

Masseter ... ... ... ... ... ... 232

Temporal muscle ... ... ... ... ... 234

Cutaneous muscles of the head ... ... ... 234

Occipito-frontalis ... ... ... ... 234

Orbicularis palpebrarum ... ... ... ... 234

Pyramidalis nasi ... ... ... ... 235

Corrugator supercilii ... ... ... ... 235

Zygomaticus major ... ... ... ... 235

Zygomaticus minor ... ... ... ... 236

Levator labii superioris proprius ... ... ... 237

Levator labii superioris alaeque nasi ... ... 238

Transversus nasi ... ... ... ... 239

Caninus ... ... ... ... ... 239

Orbicularis oris ... ... ... ... ... 240

Triangularis oris ... ... ... ... 240

Quadratus menti ... ... ... ... 240

Prominence of the chin ... ... ... ... 240

Buccinator ... ... ... ... ... 241

Ma.xillo-labialis

242

Zygomatico-auricularis .. ... ... ... 242

Temporo-auricularis externus ... ... ... 243

Scuto-auricularis externus ... ... ... 243

Cervico-auricular muscles ... ... ... 243

Cervico-auricularis superioris ... ... ... 244

Cervico-auricularis medius ... ... ... 244

Cervico-auricularis inferioris ... ... ... 244

Parotido-auricularis ... ... ... ... 244

Temporo-auricularis internus ... ... ... 244

Zygomatico-auricularis ... ... ... ... 245

EPIDERMIC PRODUCTS OF THE TERMINAL

EXTREMITIES OF THE FORE AND HIND LIMBS

Claws ... ... ... ... ... ... ,.^ 247

Plantar tubercles ... ... ... ... ... ... 248

Hoofs of the solipeds ... ... ... ... ... 250

Hoofs of ox and pig ... ... ... ... ... ... 261

Proportions ... ... ... ... ... ... 262

Proportions of head of horse ... ... ... ... ... 273

(front view)... ... ... ... ... 276

314 THE ARTISTIC ANATOMY OF ANIMALS

aces of the horse ...

I'AGE
282

Amble...

293

Trot ...

... 294

Walk

... 296

Gallop...

... 300

Leap ...

364

ERRATA

P. 105, Articulations of the Posterior Limbs.
P. 107, Tibio-tarsal Articulation.

THE END

London : Bailliere, Tindall and Cox, S, Henrietta Street, Covent Garden, IV.C.

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