The Anatomy
_of the_
Domestic Fowl
_By_
B. F. Kaupp, M. S., D. V. M.
Poultry Investigator and Pathologist in the North Carolina Experiment
Station, State Department of Agriculture, and the State College of
Agriculture; Formerly Director of Anatomy Laboratory, Kansas City
Veterinary College
Illustrated
_Philadelphia and London_
W. B. Saunders Company
1918
Copyright, 1918, by W. B. Saunders Company
PRINTED IN AMERICA
To
DAN T. GRAY, B. S., A. B., M. S.
CHIEF, ANIMAL INDUSTRY DIVISION, NORTH CAROLINA
EXPERIMENT STATION
AS A TOKEN OF RESPECT AND GRATITUDE THIS
VOLUME IS DEDICATED
BY
THE AUTHOR
FOREWORD
Advanced work in the study of poultry husbandry is now being done in
this country, to a greater or less extent, at all the two score and more
Agricultural and other Colleges and Experiment Stations. From these
institutions comes the demand for a text-book on the Anatomy of the
Domestic Fowl. No complete text-book on the subject, up to the present,
has existed. It is with the hope of meeting the demand that this book is
published.
In supplementing the information gathered from the books and articles
listed in the bibliography, the author has spent much time and effort in
obtaining the matter here presented. As this, however, is the initial
complete text on the subject necessarily much remains to be added and
corrected. The author would welcome suggestions and corrections from any
one into whose hands the book may come.
B. F. KAUPP.
THE NORTH CAROLINA STATE COLLEGE OF AGRICULTURE,
WEST RALEIGH, NORTH CAROLINA,
_September, 1918_.
CONTENTS
OSTEOLOGY
PAGE
OSSEOUS STRUCTURE 17
CLASSIFICATION OF BONES 20
COMPOSITION OF BONE 21
SKELETON OF THE FOWL 21
Axial Skeleton 23
Cranium and Face 23
Occipital 25
Ethmoid 27
Sphenoid 28
Frontal 29
Parietal 29
Temporal 29
Premaxilla 31
Maxilla 32
Nasal 32
Lacrimal 32
Palatine 33
Pterygoid 33
Zygomatic 33
Vomer 33
Jugal and Quadrato-jugal 33
Quadrate 34
Inferior Maxilla 34
Turbinate Bones 34
Hyoid 35
Vertebral Column 35
Cervical Vertebræ 35
Atlas 37
Axis 37
Dorsal Vertebræ 39
Lumbo-sacral Vertebræ 39
Coccygeal Vertebræ 41
Ribs 41
Sternum 42
Appendicular Skeleton 43
Shoulder Girdle 43
Fore Limb 44
Pelvic Girdle 48
Hind Limb 50
ARTHROLOGY
KINDS OF JOINTS 56
MOVEMENTS OF JOINTS 56
LIGAMENTOUS STRUCTURE 57
LIGAMENTS OF:
Ear 58
Jaw 58
Vertebræ 58
Ribs 59
Sternum 59
Shoulder-joint 61
Elbow-joint 61
Carpal Joint 62
Finger 64
Pelvis 65
Hip-joint 65
Knee-joint 65
Tibio-metatarsal Joint 69
Toes 69
MYOLOGY
KINDS AND STRUCTURE OF MUSCLES 70
FASCIA 71
MUSCULAR NOMENCLATURE 71
True Dermal Muscles 71
Dermo-osseous Muscles 73
Muscles of the Head 76
Muscles of the Tongue 79
Cervical Muscles 81
Muscles of the Air Passages 86
Superior Larynx 86
Inferior Larynx 86
Sternal Muscles 90
Abdominal Muscles 90
Dorsolumbar Muscles 92
Coccygeal Muscles 93
Costal Muscles 96
Anterior Pectoral Muscles 99
Pectoral Muscles 100
Muscles of the Scapular Region 101
Muscles of the Brachial Region 104
Muscles of the Forearm and Hand 105
Digital Muscles 109
Muscles of the Posterior Limb 111
Tibial Group of Muscles 117
Muscles of the Eye 124
Muscles of the Ear 128
FUNCTIONS OF MUSCLES 128
SPLANCHNOLOGY
DIGESTIVE APPARATUS 135
Mouth 135
Tongue 139
Pharynx 141
Glands Adjacent to Mouth and Pharynx 141
Esophagus 142
Crop 142
Stomach 143
Proventriculus 143
Gizzard 145
Small Intestine 147
Large Intestine 150
Cæca 151
Cloaca 151
COURSE OF THE FOOD 152
ACCESSORY ORGANS OF DIGESTION 152
Liver 153
Pancreas 155
Spleen 155
ABDOMINAL AND PELVIC CAVITIES 156
PERITONEUM AND MESENTERY 156
RELATIONS OF THE VISCERAL ORGANS OF THE DOMESTIC FOWL 158
RELATIONS OF THE VISCERAL ORGANS OF THE BABY CHICK 165
URO-GENITAL SYSTEM 169
Urinary Apparatus 169
Kidneys 169
Ureter 174
Male Generative Organs 175
Testicles 175
Vas Deferens 178
Female Generative Organs 178
Egg 180
Oviduct 182
Parts of the Oviduct 183
Ligaments of the Oviduct 188
DUCTLESS GLANDS 190
Thyroid Gland 190
Thymus Gland 190
Adrenal Gland 191
RESPIRATORY APPARATUS 193
Nostrils and Nasal Chambers 193
Pharynx and Superior Larynx 193
Trachea 194
Inferior Larynx 194
Bronchi and the Lungs 195
Air-sacs 199
ANGIOLOGY
CIRCULATORY APPARATUS 206
Heart 206
Structure of the Heart 207
Blood-vessels 209
Structure of the Capillaries and Arteries 209
Structure of the Veins 211
Arterial Trunks 211
Branches of:
Arteria Brachiocephalica 213
Arteria Carotis Cerebralis Interna 214
Arteria Carotis Externa 214
Arteria Carotis Facialis 214
Aorta Posterior 224
Venous Trunks 233
Branches of:
Venæ Cavæ Anteriores 234
Vena Jugularis 237
Vena Occipitalis Externa 239
Venous Sinuses of the Head 239
Veins of the Brain Cavity 241
Veins of the Neck 242
Branches of the Vena Subclavia 243
Veins of the Dorsal Region 243
Veins of the Thorax 244
Veins of the Fore Limb 245
Branches of the Iliaca 246
Branches of the Vena Iliaca Interna 247
Posterior Vena Cava 247
Veins of the Posterior Extremity 248
Branches of the Vena Cava Posterior 248
Veins of the Caudal Region and Pelvic Cavity 250
Veins of the Truncus Vena Iliaca Communis 252
Visceral Veins of the Posterior Vena Cava 252
Lymphatic System 254
BLOOD AND ITS FUNCTIONS 257
FATE OF THE ERYTHROCYTE 261
NEUROLOGY
NERVOUS SYSTEM 264
Cranial Nerves 265
Olfactorius 265
Opticus 267
Motoris Oculi 267
Patheticus 268
Trifacialis 268
Abducentes 270
Facialis and Acousticus 271
Vagus Group 272
Glosso-pharyngeus 272
Vagus or Pneumogastricus 273
Accessorius Spinalis 274
Hypoglossus 274
Spinal Cord 275
Structure of the Cord 275
Structure of the Nerve Trunks and Ganglia 277
Spinal Nerves 281
Brachial Plexus 282
Lumbo-sacral or Crural Plexus 285
Brain 288
Coverings of the Brain 288
Structure of the Brain 289
Divisions of the Brain 290
Sympathetic Nervous System 297
Functions of the Nervous System 300
ESTHESIOLOGY
SENSE ORGANS 303
Sight 303
Hearing 305
Smell 307
Taste 307
Touch 307
STRUCTURE OF APPENDAGES 309
EMBRYOLOGY
SPERMATOGENESIS 318
OÖGENESIS 319
FERTILIZATION 319
OUTLINE FOR LABORATORY STUDY OF THE CHICK 330
Living Embryo 330
Preparation for Study of Entire Embryos and Sections 330
Points to be Observed in the Study 332
DERIVATIVES OF THE GERM-LAYERS 342
PREPARATION OF STRUCTURES FOR STUDY 343
Directions for Dissecting Muscles 343
Directions for Study of the Viscera 344
Directions for Study of the Arteries 345
Study of the Structure of Bones 346
Special Technic for Dissection of Cranial and Spinal
Nerves 347
Directions for Study of Soft Structures 347
To Stain Sections of Liver for Study of Kupffer Cells 349
To Prepare Anatomical Specimens for Museum 349
To Make Specimens Transparent 350
EQUIPMENT FOR THE DISSECTION LABORATORY 351
BIBLIOGRAPHY 353
───────────────────────────────────────────────────────────────────
INDEX 355
ANATOMY
OF THE
DOMESTIC FOWL
OSTEOLOGY
=Osseous Structure.=—Bone is structurally modified connective tissue
which has become hard by being impregnated with calcium salts.
_Kinds of Bone Tissue._—There are two kinds of bone tissue: substantia
compacta, or compact bone tissue; and substantia spongiosa, or spongy,
cancellous bone tissue.
_Compact Bone Tissue._—The compact bone tissue forms the hard outer
layer of all bones. It is thickest in the shaft and becomes thin toward
the extremities. Through the compact bone tissue approximately parallel
with the longitudinal axis of the bone, run canals called _Haversian
canals_, through which pass blood and lymph vessels for the nourishment
of the bone and nerves. The Haversian canals are surrounded by
_concentric lamellæ_. The spaces between the cylinders thus formed are
filled with _interstitial lamellæ_; and both the exterior surface of the
bone and the interior surface surrounding the medullary canal, are built
up of peripheral, or circumferential lamellæ. Between the lamellæ,
somewhat irregularly placed, are minute reservoirs, called _lacunæ_,
which contain bone corpuscles. From the lacunæ radiate minute canals, or
_canaliculi_, which maintain circulation through the bone substance, and
which communicate with the Haversian canals. Complex anastomoses exist
among the canaliculi. Still other channels for the passage of
blood-vessels are Volkmann’s canals which pierce the peripheral lamellæ,
thus allowing vessels to pass from the periosteum to the Haversian
canals. Similar channels afford communication between the inner
Haversian canals and the medullary cavity.
The entire structure composed of an Haversian canal, its surrounding
lamellæ, lacunæ, and canaliculi, with their contained vessels, is called
an _Haversian system_.
_Cancellous Bone Tissue._—The cancellous bone tissue forms the bulk of
the short, flat, and irregular bones and of the extremities of the long
bones. It consists of delicate bony plates and spicules, which
intercross in various directions. The spaces between these plates and
spicules, called _cancelli_, are occupied by marrow except in the bones
that are pneumatic. The blood-vessels, lymphatics, and nerves course
through this marrow but are not arranged in an Haversian system.
[Illustration:
FIG. 1.—Longitudinal section of compact bone of the femur of the hen.
1, Haversian canals. 2, Lacunæ with their canaliculi.
]
_The Periosteum._—Covering the surface of bone, except at the articular
surface where it is covered with cartilage, is a membrane, the
periosteum, which consists of two layers: an outer, fibrous, protective
layer, and an inner, cellular, osteogenic layer. The outer layer
consists principally of white fibrous tissue. The inner layer contains
many more connective-tissue cells, which gradually become more closely
aggregated as we proceed toward the osseous surface; but there is no
sharply defined line of demarcation between the two periosteal layers.
[Illustration:
FIG. 2.—Transverse section of compact bone of the femur of the hen. 1,
The lacunæ and canaliculi. 2, The periosteum.
]
[Illustration:
FIG. 3.—Transverse section of compact bone of the femur of the hen
showing the lacunæ and canaliculi under high magnification.
]
The periosteum is firmly attached to the bone by trabeculæ of fibrous
tissue, called the _fibers of Sharpey_. These fibers of Sharpey
penetrate the bone at right angles to its surface and carry
blood-vessels.
_Marrow._—There are two kinds of marrow: yellow, or medulla ossium
flava, and red, or medulla ossium rubra.
The _yellow marrow_ occurs in all bones except the femur and proximal
portion of the tibia of adult fowls. It is composed of a network of
fibrous tissue carrying blood-vessels, fat cells, and myelocytes, or
marrow cells.
The _red marrow_ is found throughout the femur and the proximal portion
of the tibia, and in a few of the pelvic bones and vertebræ in the adult
fowl, and in certain other bones of the baby chick. Red marrow consists
of a delicate network of connective tissue supporting a dense capillary
plexus, a small amount of fat, and numerous cells. The cellular elements
of red marrow consist of marrow cells which contain large nuclei and
possess ameboid movement, red blood cells, giant cells containing one or
more nuclei, and various kinds of leucocytes, including eosinophiles,
mast cells, and also osteoclasts.
_Growth of Bone._—In the baby chick, only the shaft and a portion of the
extremities of the long bones are thoroughly ossified, the extreme ends,
and of the femur most of the articular head, being cartilaginous. The
bones grow in length by an increase in the cartilage, the cartilage
gradually becoming ossified. Growth in diameter is accomplished by the
constant deposition of new layers of bone beneath the periosteum. During
this process the osteoclasts absorb the bone from within. The formation
of the marrow cavity is thus effected.
=Classification of Bones.=—The bones of the fowl are classified as long,
short, flat, and irregular.
_Long Bones._—The long bones occur in the legs and wings, where they
serve as levers to sustain weight and make locomotion possible. A long
bone consists of a shaft and two extremities. The superior is called the
_proximal_ and the inferior the _distal extremity_. The expanded
articular surfaces in forming joints with adjoining bones afford ample
space for the attachment of ligaments. The shaft is cylindrical and
hollow.
_Short Bones._—Short bones occur in the feet and in the wings. Their
structure is similar to that of the long bones.
_Flat Bones._—The flat bones occur where extensive protection is needed,
as in the cranial region; or where large surface for muscular
attachments is needed, as in the costal and pelvic regions. Flat bones
are made up of two thin layers of compact bone with a variable amount of
cancellous tissue interposed.
_Irregular Bones._—The irregular bones include the vertebræ, the
patellæ, and the carpal bones.
=Composition of Bone.=—Bone consists of organic and inorganic matter.
Organic matter gives toughness and elasticity to the bone, and inorganic
matter hardness. The organic substance of bone is called ossein. When
boiled in water ossein is resolved into gelatin. The following tables[1]
give the results of an analysis of the femur, fresh, of a mature hen.
Footnote 1:
Grateful acknowledgment is hereby made to Dan M. McCarty, Chemist,
Animal Industry Division, North Carolina Agricultural Experiment
Station, for this analysis.
Fresh femur:
Water 18.23 per cent.
Dry matter 81.77 per cent.
Dry matter:
Organic matter 63.09 parts
Inorganic matter 18.68 parts
Salts in dry matter:
Calcium 6.970 per cent.
Magnesium 0.283 per cent.
Potassium 0.004 per cent.
Sodium 0.276 per cent.
Iron 0.020 per cent.
Phosphorus 3.210 per cent.
Sulphur 0.085 per cent.
Chlorine 0.520 per cent.
Carbon dioxid 0.550 per cent.
The inorganic matter of the femur of the hen consists of 18.68 parts or
22.84 per cent. of dry matter, and the organic matter of 77.16 per cent.
Stated in other words the femur, including its contained marrow,
consists of organic and inorganic matter in the ratio of 3.4,
approximately, to 1.
=The Skeleton of the Fowl.=—The skeleton of a bird is remarkable for the
rapidity of its ossification. It is worthy of note that other parts of
the bodies of adult birds also become ossified. Among such parts are the
tendons of the muscles of the legs, of the feet, and of the neck; the
plates of the corneal margin of the sclerotic tunic of the eye; and the
stapes of the ear. Ossification in birds at the attachments of the
semi-lunar valves of the aorta and of the pulmonary artery has been
reported by Owen.
The bony structure is compact, and the bones contain a greater
proportion of phosphate of lime than do the osseous structures of
mammals. Especially is this the case in those parts of the skeleton
which are permeated by air.
THE DIVISIONS OF THE SKELETON
( The Skull ( Cranium
( ( Face
The Axial skeleton ( ( Cervical region
( ( Dorsal region ( Ribs
( The Vertebral column ( ( Sternum
( Lumbar region
( Sacral region
( Coccygeal region
( Scapula
( Shoulder girdle ( Coracoid
( ( Clavicle
(
( ( Arm ( Humerus
( (
( Fore limb ( Forearm ( Radius
( ( ( Ulna
( (
( ( ( Carpus
The Appendicular skeleton ( ( Hand ( Metacarpus
( ( Phalanges
(
( Pelvic girdle ( Ilium
( (Hip bone) ( Ischium
( ( Pubis
(
( ( Thigh ( Femur
( Hind limb (
( Leg ( Tibia
( ( Fibula
(
( Foot ( Metatarsus
( Phalanges
The bodies of birds contain many air reservoirs to make them light that
flying may be more easy. Many bones have their weight in proportion to
size and strength thus greatly reduced. In very young birds the cavities
of bones contain, instead of air spaces, loosely arranged red marrow,
which is in most bones later absorbed. The air reservoirs in bones are
most capacious in the best flyers. In the non-flyers more of the bones
retain their red marrow.
The bones supplied with air spaces are relatively larger than in
mammals, and are provided with small transverse osseous columns which
cross in different directions and from side to side. These cross beams
give stability to the thin wall of the bone. The membranes lining these
cavities are very vascular.
THE AXIAL SKELETON
THE SKULL
The skull is divided into the cranial and facial portions. In these
parts we find present 31 bones: one occipital, two parietal, two
frontal, one ethmoid, one sphenoid, and two temporal; all of which
constitute the cranial group; two premaxillary, two maxillæ, two nasal,
two lacrimal, two palatine, two pterygoid, two zygomatic, one vomeral,
the two jugal, and two quadrato-jugal, which constitute the facial
group; two quadrati and one inferior maxillary, which constitute the
inferior jaw group.
The peculiarities of the skull are the long os incisivum and the single
condyle located on the occipital bone just below the foramen magnum. The
condyle articulates with the atlas.
The head of the bird is small in proportion to the size of the body, and
in front it is conical in shape.
THE CRANIUM
The cranial cavity, or cavum cranii, incloses the brain with its
membranes and vessels.
The dorsal wall, or roof, is formed by the frontal and the parietal
bones. In the median line of the cerebral portion is the internal
parietal crest. The roof of the cerebellar portion is marked centrally
by a groove.
The posterior wall of the cerebellum is formed by the occipital bone.
The lateral wall is formed chiefly by the temporal bone. It is marked by
a ridge which divides the cavity into the cerebral and cerebellar
compartments. The cerebral portion is marked by a depression which
receives the optic lobes. A crest divides this cavity from the optic
portion. The walls are marked by digitations and vascular grooves.
[Illustration:
FIG. 4.—The skeleton of the domestic fowl. 1, Os incisivum. 2,
External nasal opening. 3, Os nasale. 4, Os lachrymale. 5, Lamina
perpendicularis. 6, Os dentale. 7, Os palatine. 8, Os
quadrato-jugal. 9. Os pterygoideum. 10, Os quadratum. 11, Os
articulare. 12, External auditory canal. 13, Atlas. 14, Os carpi
radiale. 15, Radius. 16, First finger. 17, Os metacarpus. 18, Second
finger. 19, Third finger. 20, Os carpi ulnare. 21, Ulna. 22,
Humerus. 23, Thoracic vertebræ. 24, Scapula. 25, Os ilium. 26,
Foramen ischiadicum. 27, Caudal vertebræ. 28, Pygostyle. 29, Foramen
obturatum. 30, Os ischium. 31, Processus uncinatus. 32, Vertebral
rib. 33, Os claviculum or furculum. 34, Os coracoideum. 35, Os
femoris. 36, Os pubis. 37, Body of sternum. 38, Lateral internal
process of sternum. 39, Costal process of sternum. 40, Sternal
crest, cristi sterni, or keel of breast-bone. 41, Sternal rib. 42,
Lateral external process of sternum. 43, Os fibula. 44, Xyphoid
process of sternum. 45, Internal notch. 46, Os patella. 47, Os
tibia. 48, Os metatarsus. 49, Second toe. 50, Fourth toe. 51, Os
metatarsale. 52, First toe. 53, Second toe. 54, Second phalanx of
second finger. 55, Os metacarpus. 56, Air opening in humerus. 57,
Hypocledium. 58, External notch. 59, Cervical vertebræ. 60, Foramen
oblongum.
]
The ventral wall, floor, or basis cranii interna, may be regarded as
forming five fossæ. These are: one anterior, one middle, one posterior,
and two lateral. The _anterior fossa_ supports the frontal and olfactory
parts of the cerebrum. It lies at a higher level than the middle fossa.
The _middle fossa_, or _fossa cranii media_, is circular in outline and
extends into the lateral fossæ which lodge the olfactory lobes. Just
back of the middle fossa is the sulla turcica, upon which rests the
pituitary body. The _posterior fossa_, or _fossa cranii posterior_,
lodges the medulla oblongata.
=Bones of the Cranium= (Figs. 4, 6, 7, and 8).—The bones of the cranium
fuse early in the chick’s life. The sutures uniting the bones can
usually be seen in the fetus or in the baby chick soon after it emerges
from the shell. The major portion of the cranial bones become entirely
fused. Each cranial and each facial bone ossifies from a distinct center
or centers.
The cavity for the cerebrum is much larger than the cavity for the
cerebellum. The cranial cavities in birds are relatively larger than in
mammals. The bones are designated as in mammals. There are three single
bones, the occipital, the ethmoid, and the sphenoid. Those in pairs are
the frontal, the parietal, and the temporal.
=The Occipital.= _Location._—The occipital bone or os occipitale, is
situated at the posterior part of the cranium, of which it forms the
posterior wall. This part is called the base of the cranium. The
occipital bone articulates with or touches inferiorly, the sphenoid,
laterally, the temporal, and superiorly, the parietal.
_Development._—The occipital bone is developed from four centers of
ossification; the dorsal, or os occipitale superius, two lateral, or
ossa occipitales laterales, and the ventral, or os occipitale inferius,
all of which may be seen distinct in the baby chick (Fig. 5, Part II,
No. 1).
[Illustration:
FIG. 5.—Bones of the head and vertebra.
Part I.—1, The cranium. 2, The skull cap. 3, The ethmoid bone. 4, The
inferior maxilla. 5, The palatine bone. 6, The quadrato-jugal. 7,
The jugal. 8, The superior maxilla. 9, The premaxilla. 10, The horny
covering for the premaxilla. 11, The horny covering for the os
dentale. 12, The os quadratum. 13, The nasal bone. 14, The
pterygoid.
Part II.—1, The os occipitale (1, dorsal; 2, two lateral; 3, ventral
portions and 4, foramen magnum). 2, The fourteen cervical vertebræ.
(1, atlas; 2, axis). 3, The seven dorsal vertebræ. 4, The fourteen
lumbo-sacral vertebræ. 5, The seven coccygeal vertebræ. 6, The
pelvis (1, ilium; 2, ischium; 3, pubis; 4, cotyloid cavity or
acetabulum). 7, The vertebral column complete from the baby chick.
8, The parietal bone. 9, The temporal bone. 10, The frontal bone.
]
_Description._—In the center of the occipital bone is the _foramen
magnum_. Through this foramen the spinal cord extends into the cranial
cavity and connects with the medulla oblongata. The occipital bone has a
single condyle, which is located just below the foramen magnum and
articulates with the atlas. At the base of the condyle a small
_subcondyloid fossa_ receives the body of the atlas during extreme
flexion of the head. In the center of the lateral wing of the occipital
bone there is a small foramen through which passes the hypoglossal
nerve. Somewhat laterally from this foramen there is an opening through
which the vagus, or pneumogastric nerve passes. Laterally from these is
the _canalis caroticus et jugularis_. Between the os occipitale
superius, or dorsal portion, and the ossa parietalia is a space to which
ligaments are attached, called the fontanel.
[Illustration:
FIG. 6.—View of the frontal region of the skull of a hen. 1, Parietal.
2, Frontal. 3, Nasal. 4, Premaxilla. 5, Temporal. 6, Inferior jaw.
7, Jugal bone.
]
=The Ethmoid.= _Location._—The ethmoid, or os ethmoidale, forms the
anterior wall of the cranium, and the orbital septum. It is related
anteriorly with the vomeral, superiorly with the nasal and frontal,
posteriorly with the temporal, and inferiorly with the sphenoid, and
palatine.
_Description._—The ethmoid consists of a perpendicular and a horizontal
lamina. The perpendicular lamina, located between the orbital cavities,
is called the _septum interorbitale_. On each side of the septum
interorbitale and near the superior orbital roof are two foramina for
the passage of the olfactory nerves. In the horizontal plate, which
forms the anterior cranial wall, are located the _optic foramina_
through which pass the optic nerves.
[Illustration:
FIG. 7.—Side view of the skull of a hen. 1, Lamina perpendicularis. 2,
Foramen for the passage of the nerve of smell. 3, Foramen for the
passage of the optic nerve. 4, Nasal bone. 5, External nasal
opening. 6, Premaxilla. 7, Os dentale. 8, Superior maxilla. 9, Os
jugal. 10, Os quadrato-jugal. 11, Os quadratus. 12, Pterygoideus.
13, Os articulare. 14, Inferior maxilla. 15, Temporal. 16, External
auditory canal. 17, Parietal. 18, Frontal. 19, Palatine. 20, Orbital
process, posterior to which is the processus zygomaticus. 21,
Interorbital foramen and optic foramen for passage of optic nerve.
22, Attachment for inferior oblique; 23, for superior oblique; 24,
for levator palpebræ superioris; 25, for internal rectus; 26, for
superior rectus; 27, for external rectus; 28, for inferior rectus;
28, for inferior rectus; 29, for depressor palpebræ inferioris; 30,
for orbicularis palpebrarum; 31, for tensor tympani; 32, for
circumconcha.
]
=The Sphenoid.= _Location._—The sphenoid, or os sphenoidale, forms the
floor of the cranial cavity and articulates with or touches posteriorly
the occipital, laterally the temporal, and anteriorly the palatine, and
ethmoid.
_Description._—The sphenoid bone, the largest part of the cranial floor,
is formed by the fusion of the nasal and the cranial parts. It is a
three-cornered bone with two, thin, broad wings. These wings are divided
into two portions, orbital wings, or _alæ orbitales_, and temporal
wings, or _alæ temporales_. The temporal wing forms a cover for the
Eustachian tube trumpet, and for the canal coming from the sella
turcica, which latter gives passage to the intracranial carotid artery.
The orbital wing forms the lower portion of the posterior wall of the
orbital cavity, and lies directly before the os petrosum or temporal
bone where the second and third branches of the fifth pair of cranial
nerves emerge from the cranial cavity.
Anteriorly the sphenoid has a foramen for the passage of the Eustachian
tube, the _tuba auditiva_, and also a sharp-pointed projection, the
nasal portion, called the _rostrum_.
=The Frontal.= _Location._—The frontal bones, or ossa frontales, two in
number, form the forehead, a portion of the nose, and a portion of the
roof of the orbital cavities. They are related posteriorly with the
parietal, laterally with the temporal and zygomatic, and anteriorly with
the nasal and premaxillary. They touch inferiorly the ethmoid.
_Description._—Each of these bones has a _processus orbitalis_ which is
seen at the outer margin of the posterior and upper orbital wall and
just in front of the zygomatic process of the squamous portion of the
temporal. The frontal bone forms the anterior portion of the superior
wall of the cranial cavity. The two bones are thin, flat, and meet at
the median line of the forehead. The external surface is convex. The
inner surface has a ridge located longitudinally and in the center the
bone becomes narrow anteriorly.
=The Parietal.= _Location._—The parietal bones, or ossa parietalia, two
in number, form the posterior part of the roof of the cranial cavity.
They meet in the median line and are related posteriorly with the
occipital, anteriorly with the frontal, and laterally with the temporal
bones.
_Description._—The parietal bones are short and very broad (Fig. 5, Part
II, No. 8). Each bone is quadrilateral in outline and has two surfaces,
four borders and four angles. The external parietal surface is convex
and smooth and the internal, cerebral surface is concave.
=The Temporal.= _Location._—The temporal bones, or ossa temporales, two
in number, are located at the lateral portion of the cranium, and aid in
the formation of the cranial wall. The temporal bone is related
posteriorly with the occipital, superiorly with the parietal and
frontal, externally with the quadratus, anteriorly with the ethmoid, and
inferiorly with the sphenoid.
_Description._—The temporal bones consist of the fused squamous and
petrous temporals; they contain the essential organs of hearing.
[Illustration:
FIG. 8.—Inferior view of the skull of a hen. 1, Occipital. 2, Foramen
magnum. 3, Occipital condyle and just below the basi-occipital. 4,
Foramen for the passage of the hypoglossal nerve. 5, Foramen for the
passage of the vagus. 6, Canalis caroticus and jugulare. 7,
Sphenoid. 8, Temporal wings of the sphenoid. 9, Foramen auditiva.
10, Os articulare. 11, Os angulare. 12, Vomer. 13, Os dentale. 14,
Pterygoid.
]
The _squamous portion_ of the temporal bone possesses the long thin
zygomatic process sometimes called the _posterior orbitalis_. It forms a
small flattened tongue, directed forward, sometimes free, and at other
times united by its superior border to the summit of the orbital
process. This is especially true in the turkey. This process is seen
near the lower outer portion of the posterior orbital wall. The squamous
portion is also provided antero-laterally with an articular facet which
articulates with the quadrate bone. The large portion of the temporal
bone lies on the side of the cranium superior to the ala sphenoida
temporale. It extends outward and anteriorly over the rims of the
petrosum and ala sphenoida orbitale. The squamous part forms the upper
three-fourths of the cochlea, the inner auditory canal, the upper part
of the fenestra ovalis, the anterior vertical and the outer semicircular
canal, and the lower part of the posterior vertical semicircular canal.
The _petrous portion_ forms the posterior wall of the foramen ovale and
the fenestra ovalis in which lies the columella. The fenestra ovalis and
the fenestra rotunda are the only two entrances into the labyrinth. In
this region may be seen the fusion line between the os petrosum and the
os occipitale. Superiorly and posteriorly the petrous portion touches
the external parietalia and occipitalis; infero-laterally it unites with
the basi-sphenoid. The outer rim of the foramen ovale is broadened by
the ala sphenoida and mesially by the basi-sphenoid. This foramen gives
exit to the second and third divisions of the fifth pair of cranial
nerves.
The lateral surface of the temporal bone presents a short tube, the
_external acoustic process_, or _processus acusticus externus_, to which
is attached the concha of the ear. The process is directed outward. Its
lumen, the _external acoustic meatus_, or _meatus acusticus externus_,
conducts to the cavity of the middle ear in the bare skull, but is
separated from it by the tympanic membrane in the natural state.
BONES OF THE FACE
The bones of the face, or ossa faciei, are the premaxillary, or upper
mandible, the maxillæ, the nasal, the lacrimal, the palatine, the
pterygoid, the zygomatic, the vomeral, the jugal and the quadrato-jugal.
The vomer is single, the others are paired. In the inferior maxillary
group there are the quadrati, and the inferior maxillary, or lower
mandible. The turbinated and hyoid bones are also discussed with the
bones of the face.
The beak consists of the anterior portion of the upper and lower
mandibles which are covered with a horny structure.
=The Premaxilla.= _Location._—The premaxillæ, or ossa incisiva, or
mandibular structures, are located in the extreme anterior facial
region.
_Description._—The premaxillæ are long and the anterior end is pointed.
Each consist of two lateral halves which become fused before the chick
is hatched. They partly circumscribe the openings into the nose. This
bone is the base of the upper portion of the beak and determines its
form. It forms the anterior walls of the nasal cavity. It has between
the nasal bones, two processes which extend back to the anterior point
of the cerebral cavity. The posterior part of the incisivum and nasale
are flat, thin, and elastic. The extensions then are the _processus
maxillaris_, the _processus palatinus_, and the _processus frontalis_,
the first of which forms part of the jaw rim, the second, which aids in
forming the gum plate, and the last which reaches to the anterior
portion of the cranial wall.
=The Maxilla.= _Location._—The superior maxillaries, or ossa maxillares,
two in number, form the floor of the upper beak, a part of the palatine
roof and nasal walls.
Each maxilla borders laterally the premaxilla and the nasal; inferiorly,
the anterior point of the palatine; and posteriorly, the jugale.
_Description._—The maxillæ are thin, flat, bones. They have three
borders and three angles. The palatine processes of the two bones do not
meet in the median line, which results in a cleft in the median palatine
region. The bone-like gums are formed partly by the palatine processes
but more largely by lateral wings of the os incisivum. Each maxilla has
posteriorly a yoke-like extension, superiorly a small extension, and
also a palatine process. The latter articulates by a facet with the
vomer.
=The Nasal.= _Location._—The nasal bones, or ossa nasalia, two in
number, are located in the lateral facial region. The nasal bone
articulates posteriorly with the frontal; laterally, on the inner
border, with the processus frontalis of the premaxilla, and on the outer
border with the lacrimal; and inferiorly with the premaxilla, maxilla,
jugale, and vomer.
_Description._—The nasal bone, or os nasale, is broad, flat, and elastic
and forms the posterior wall of the nasal opening. Under this bone is
located the infraorbital sinus.
There are three extensions: first, the _processus intermaxillaris_,
which forms the upper wall of the nasal cavity; second, the _processus
maxillaris anterior_, directed downward and forward, which fuses with
the maxillary bone and forms the posterior rim of the nasal cavity; and
third, a _posterior processus frontalis_, which lies parallel with the
ethmoid.
=The Lacrimal.= _Location._—The lacrimal bones, or ossa lacrimalia, two
in number, are located at the outer border and at the junction of the
processus frontalis of the nasal, with the frontal bone.
_Description._—The lacrimal bone is small, and rather filiform. They
become fused with the nasal and the frontal bones, forming part of the
margin of each.
=The Palatine.=—_Location._ The palatine bones, or ossa palatina, two in
number, enter into the formation of the inner part of the bony gum and
hard palate, or roof of the mouth. They form the support for the hard
palate. Each palatine articulates posteriorly with the rostrum, or nasal
portion of the sphenoid, and with the pterygoid; and anteriorly with the
maxilla.
_Description._—The palatine bone is curled posteriorly and is thin at
the upper portion and thick at the lower border. Anteriorly it has a
long rather filiform projection.
=The Pterygoid.= _Location._—The pterygoid bones, or ossa pterygoidea,
two in number, are located back of the region of the posterior nares.
They extend diagonally outward and backward from the median region of
the sphenoid rostrum to the quadrate bone. They articulate anteriorly
with the sphenoid rostrum and the palatine, and posteriorly with the
quadrate.
_Description._—The pterygoid bones are slender and cylindrical, and are
expanded at the ends into an articular facet.
=The Zygomatic.= _Location._—The zygomatic, or ossa zygomatica, two in
number are situated below the orbital cavity and extend from the maxilla
to the quadrate bone.
_Description._—The zygomatic is small, slender, rod-shaped, and forms
the lateral portion of the upper jaw. The anterior portion of the
zygomatic represents the jugal and is fused with the maxilla and with
the anterior processus maxillaris of the nasal bone, the maxilla, and
the posterior portion, the quadrato-jugal, which articulates with the
quadrate bone.
=The Vomer.= _Location._—The vomer is located in the median nasal
septum. It articulates with the rostrum of the sphenoid, being connected
to it by a mass of ligaments. It touches anteriorly the posterior
portion of the maxilla.
_Description._—The vomer is a median bone and aids in the formation of
the septum nasi. It consists of a thin plate, thickest posteriorly and
diminishing toward the anterior edge.
=The Jugal and Quadrato-jugal.=—The jugal and quadrato-jugal are united
forming a long slender cylindrical bone called the zygomatic, lying at
the outer side of the upper jaw. They have been described under
zygomatic, which see.
=The Quadrate.= _Location._—The quadrate bones, or ossa quadrata, two in
number, are located antero-laterally to the temporal bones. Each
articulates inferiorly with the posterior articular portion, or pars
articulare, of the inferior maxilla and infero-laterally with the
quadrato-jugalare portion of the zygomatic. It articulates
antero-internally with the pterygoid and supero-posteriorly with the
temporal.
_Description._—The quadrate bone is anvil-like in shape. It has an
anterior process, the orbital process, for muscular attachments, and
posteriorly it affords attachment to the ear drum.
=The Inferior Maxilla.= _Location._—The inferior maxilla, lower jaw, or
os maxillare inferius, also called the mandibular bone, or pars dentis,
is analogous to the lower jaw of mammals. It articulates posteriorly
with the quadrate bone.
_Description._—The inferior maxilla is the largest bone of the face. It
is made up of a _right_ and a _left limb_ which are separate in the
fetus and which unite subsequently anteriorly, forming the inferior
portion of the beak. Each limb of the jaw is developed from five
elements: the _pars articularis_, which forms the jaw-joint and,
expanded, articulates with the quadrate bone; the _pars angularis_,
lying just in front of the pars articularis; the _pars supra-angularis_,
a slender bone lying just above the angularis; the _splenial_, a thin
plate of bone, lying along the inner surface of the mandible; and the
_pars dentalis_, which forms the anterior portion of the jaw.
=The Turbinate Bones.= _Location._—The turbinate bones, or ossa
turbinata, six in number, are attached to the lateral walls of the nasal
cavity (Fig. 26, No. A, 1 and 2). In each nasal cavity there are three
turbinate bones, one anterior and two posterior. Of the two posterior
the upper one lies supero-posterior to the inferior one. The turbinate
bones are attached to the lateral nasal walls, project into the cavity
and thus greatly diminishing its extent.
_Description._—Each turbinate bone is composed of a very thin lamina,
finely cribriform in many places, and in the fresh state, covered on
both sides with mucous membrane. These bones are curled and partly
membrano-cartilaginous structures which give greater surface in the
nasal passage for mucous membrane in which the olfactory nerve terminal
filaments are distributed.
=The Nasal Cavity.=—The nasal cavity, or cavum nasi, is a longitudinal
passage which extends through the upper part of the face. It is divided
into right and left halves by a median septum nasi. Its walls are made
up of the premaxilla, maxilla, nasal, vomer, and palatine bones.
=The Hyoid Bone.= _Location._—The hyoid bone, or os hyoideum, is
situated chiefly between the rami of the mandible, but its upper part
extends around the outer margin of the base of the skull. The hyoid bone
does not articulate with any bones of the skull, but is firmly attached
by strong fibrous structure.
_Description._—The hyoid bone consists of the following parts: the
_body_, or _basi-hyal_, which is subcylindrical and presents in front a
trochlear articular surface, convex transversely, and concave vertically
for articulation with the ewer-shaped portion of the glosso-hyal. The
anterior free portion, or lingual process, is called the _glosso-hyal_,
or _entoglossal bone_. The lingual process gives support to the muscular
and fibrous structures of the tongue. On either side of the basi-hyal
there is a limb passing posteriorly along the side of the superior
larynx, extending upward along the outer border of the occipital bone.
This is the _cornu_ of the os hyoideum and is divided into two elements,
first, the _basi-branchial_ which is bone and articulates with the
basi-hyal, and the second, the _cerato-branchial_, cartilaginous in
structure. In the center and projecting backward from the body of the os
hyoideum is a spur process called the _uro-hyal_, partly bony and partly
cartilaginous, and which rests upon the superior larynx.
THE VERTEBRAL COLUMN
The vertebral, or spinal column consists of 42 bones, as shown in the
following table:
Cervical region 14
Dorsal region 7
Lumbo-sacral region 14
Coccygeal region 7
——
Total 42
Many of the bones of the dorsal and lumbo-sacral regions do not have
free articulations. The cervical and coccygeal alone have free
movements.
=The Cervical Vertebræ= (Fig. 4, No. 59; Fig. 5, Part II, No. 2).
_Location._—The cervical vertebræ form the neck of the fowl.
[Illustration:
FIG. 9.—Os hyoidum and tongue muscles. 1, Glosso-hyal. 3, Basi-hyal.
4, Basi-branchial element of the cornua. 5, Cerato-branchial element
of the cornua. 6, Uro-hyal or spur process. 7, Genio-hyoideus. 8,
Cerato-hyoideus showing the slender tendon. 9, Hyoideus transversus.
10, Hyoideus transversus.
]
_Description._—The long cervical section of the spinal column is
S-shaped and is made up of fourteen vertebræ. The anterior segments move
freely forward, the middle ones backward and the posterior ones forward,
allowing the S-shaped curve of the neck. The neck is flexible so that it
is possible for the beak to reach the coccygeal oil gland. The bird is
enabled to reach the feathers on all parts of the body to cleanse and
oil them.
=The Atlas.= _Location._—The first cervical vertebra is called the
atlas. Anteriorly it articulates with the single condyle of the
occipital bone. Posteriorly it articulates with the axis, or second
cervical vertebra.
_Description._—The atlas is the smallest of the cervical vertebræ and is
ring-shaped. The anterior articular surface, half-moon in shape, forms a
deep articular cavity. The joint, called a ball-and-socket joint, makes
possible movements in all directions. The condyle of the occiput also
touches an articular end of the odontoid process of the axis, or second
cervical vertebra. Posteriorly there projects from the atlas two small
lateral wings possessing articular facets which articulate with similar
facets on the lateral wings of the axis. Posteriorly the body of the
atlas is also provided with an articular surface which articulates with
a similar surface on the anterior portion of the body of the axis.
=The Axis.= _Location._—The axis is the second cervical vertebra. It
articulates anteriorly with the atlas, and by a facet on the extreme
anterior end of the odontoid process, with the condyle of the occipital
bone. Posteriorly it articulates with the third cervical vertebra.
_Description._—The body of the axis is short. The upper anterior portion
of the body of the axis is provided with a tooth-like process called the
_odontoid process_. There are two anterior lateral wings provided with
small articular facets which articulate with similar facets of the
atlas. The anterior surface of the body of the axis forms a true
articulation with the body of the atlas.
The axis is provided with a _superior_ and an _inferior spine_. There
are two posterior articular processes which articulate with the
prezygapophyses, or anterior articular processes, of the third cervical
vertebra. The posterior part of the body of the axis forms a true
articulation with the body of the third cervical vertebra.
=Other Cervical Vertebræ.=—Beginning with the axis, the body of which is
relatively short, the body of each succeeding vertebra is longer than
that of the preceding. The articulations of each vertebra with adjoining
vertebræ are effected by means of diarthrodial facets, convex in one
direction and concave in the other.
[Illustration:
FIG. 10.—_A._ Diagram of three first dorsal vertebræ and scapular
arch-side view. _B._ Diagram of section through the hemal arch.
_A._ 1, First dorsal segment. 2, Second. 3, Third. 4 and 5, Hemal
arches. 6, The pleurapophyses or floating ribs. 7, The third
pleurapophyses or dorsal vertebral rib articulating with the
hemapophysis or sternal rib, 8, and this in turn with the wing of
the sternum form a hemal arch. 9, The sternum. 10, Intervertebral
foramen through which the nerves pass. 11, Articulation with the
body of vertebra parapophyses. 12, Articulation with transverse
process or diapophyses. 13, Oblique process or zygapophysis. 14, The
epipleural appendage.
_B._ 1, Hemal or inferior spine (hypapophysis). 2, The neural arch. 3,
The pleurapophyses or rib. 4, The superior or neural spine or
neurapophysis which aids in the formation of the anapophyseal ridge.
5, Parapophyseal surface for head of rib. 6, Tubercle of rib
articulating with the diapophysis. 7, Lamina of neurapophysis. 8,
Centrum. 9, Hemal arch.
]
Between the bodies of the vertebræ are pads of fibrous cartilage. Above
these bodies and inferior to the neural spines extends throughout the
spinal column the large _neural canal_ which is occupied by the spinal
cord. Between the vertebral segments the neural canal is exposed
superiorly, since here the neural arches do not completely bridge the
canal. These spaces are protected by intervertebral ligaments.
In addition to the superior neural spines and the inferior spines, from
the body of the vertebra project _lateral processes_, and anterior and
posterior _oblique processes_.
All cervical vertebræ except the atlas and the axis are made up of the
following parts: a body, or centrum, a neural canal, a neural arch, a
superior dorsal, or neural spine, or neurapophysis, which in most
cervical vertebræ is only slightly developed, two oblique processes, or
zygapophyses, two transverse processes, or diapophyses (Fig. 10, No. 12)
and in some vertebræ two tubercles, or anapophyses above the posterior
zygapophyses. The _prezygapophyses_ are directed upward and inward; the
_postzygapophyses_ are directed downward and outward. The inferior
spines are only well developed in the last two or three cervical
vertebræ.
Between vertebral segments, except the central sacral portion, on each
side, there is an _intervertebral foramen_ (Fig. 11, No. _A_, 4),
through which pass the spinal nerves. In the central portion of the
sacrum where the vertebræ have fused, there are two foramina on each
side for each original vertebra, one located above the other, the upper
giving passage to the sensory branch, the lower to the motor branch of
the nerve.
=The Dorsal Vertebræ= (Fig. 4, No. 23; Fig. 11, _A_). _Location._—The
dorsal, or thoracic vertebræ, or vertebræ thoracicales, aid in forming
the roof of the chest cavity.
_Description._—The dorsal vertebral section is made up of seven
vertebræ, with strong short bodies. The first and sixth dorsal segments
articulate as do the cervical, by the bodies and oblique processes.
(Fig. 11, No. _A_, 3, illustrates the oblique processes.) The seventh
dorsal is fused with the first lumbo-sacral vertebra. The second to the
fifth inclusive of the vertebræ are fused together, and the superior and
inferior spinous processes are fused into a prominent plate-like ridge.
The transverse processes of the dorsal vertebræ, from the second to the
sixth, are well developed and are bridged over with a thin layer of
bone. The ventral spines are partly fused and form a very prominent and
continuous ridge. (Fig. 11, No. _A_, 1, shows the fused superior spines;
No. 2, the fused inferior spines; and No. 4, the intervertebral
foramina.)
=The Lumbo-sacral Vertebræ= (Fig. 5, Part II, No. 4). _Location._—The
fused lumbo-sacral section of the spinal column forms the roof of the
pelvic cavity.
[Illustration:
FIG. 11.—Bones from the scapular arch.
_A._ Dorsal vertebra. 1, Superior spinous ridge, 2, Inferior spinous
ridge. 3, Oblique processes. 4, Intervertebral foramina. 5,
Articular facette for head of the rib. 6, Articular facette for
tubercle of the rib. 7, Articular portion of the body.
_B._ Outer surface of scapula.
_C._ Inner surface of scapula. 1, Thin caudal end. 2, Articular head.
4, Processus furcularis. 5, Processus humeralis. 6, Processus
coracoideus.
_D._ Outer surface of coracoid.
_E._ Inner surface of coracoid. 1, The furcular tuberosity. 2,
Articular facette for articulation with the sternum. 3, Articular
surface for humerus and scapula.