Tracheo-lateralis. 3, Broncho-trachealis brevis. 4, Costal process
of sternum. 5, Right and left carotid converging and occupying same
sheath at 6. 7, The heart showing branches of coronary artery. 8,
Cervical air-sac. 9, Left brachio-cephalic artery. 10, Right
brachio-cephalic artery. 11, Trachea. 12, Inferior larynx. 13.
Subclavian artery. 14, Carotid trunk. 15, Internal thoracic artery.
16 Thyroid gland. 17, Anterior vena cava. 18, Auricular appendage.
]
[Illustration:
FIG. 21.—The inferior tracheal region. 1, Bronchialis anticus. 2,
Bronchialis posticus. 3, Broncho-trachealis posticus. 4,
Broncho-trachealis anticus.
]
_Action._—A tensor of the true or inferior larynx.
=Broncho-trachealis Anticus= (Fig. 21, No. 4). _Location._—Anterior
portion of the inferior extremity of the trachea.
_Origin._—The anterior branch of the bifurcated tracheo-lateralis.
_Insertion._—To the anterior extremity of the third half ring of the
bronchus of the same side.
_Shape._—A small fasciculus.
_Relations._—Internally with the trachea, and externally with the skin
and other integument.
_Action._—A tensor of the inferior larynx.
=Broncho-trachealis Brevis= (Fig. 20, No. 3). _Location._—Posterior part
of the inferior extremity of the trachea.
_Origin._—From just beneath the broncho-trachealis anticus muscle.
_Insertion._—Extends obliquely across the inferior larynx and is
inserted to the posterior end of the second bronchial ring.
_Shape._—Rather short, strong, straight, subcylindrical.
_Relations._—Internally with the trachea, and laterally with the
broncho-trachealis posticus.
_Action._—A tensor of the inferior larynx.
=Bronchialis Posticus= (Fig. 21, No. 2). _Location._—Supero-lateral side
of the anterior end of the bronchi.
_Origin._—From the lateral inferior margin of the last tracheal ring.
_Insertion._—Passing obliquely across the larynx it inserts to the
posterior extremity of the second half ring of the bronchus.
_Shape._—Small, thick, spindle-shaped.
_Relations._—Internally with the trachea, inferiorly with the
bronchialis anticus, and superiorly with the broncho-trachealis brevis.
_Action._—A tensor of the larynx.
=Bronchialis Anticus= (Fig. 21, No. 1). _Location._—Inferior to the
former muscle.
_Origin._—From the last ring of the trachea.
_Insertion._—The fibers pass obliquely forward and become inserted to
the rim of the arytenoid cartilage of the inferior larynx, and the
anterior extremities of the first and second half rings of the bronchus.
_Shape._—Thick, spindle-shaped; about twice the size of the bronchialis
posticus.
_Relations._—It is crossed at its origin by the broncho-trachealis
anticus and is related internally with the bronchus and end of the
trachea.
_Action._—A tensor of the larynx.
=Sterno-trachealis= (Fig. 20, No. 1). _Location._—The inferior region of
the trachea above the above-named muscles.
_Origin._—From the side of the trachea beneath the posterior border of
the broncho-trachealis anticus.
_Insertion._—Passes downward and backward across the cavity of the chest
and is inserted to the inner part of the costal process of the sternum.
_Shape._—A delicate cord of fibers.
_Relations._—Internally with the broncho-trachealis muscles.
_Action._—A relaxor of the larynx, and hence, of the tympanic membrane.
THE STERNAL GROUP
=Triangularis Sterni.= _Location._—In the floor of the thoracic cavity.
_Origin._—From the entire superior margin of the summits of the costal
processes.
_Insertion._—The fibers extend upward and backward, dividing into four
digitations which cover the inner surface of the three principal sternal
ribs, and are inserted to the first four as high as their articulations
with the vertebral ribs.
_Shape._—Flat and somewhat triangular.
_Relations._—Interiorly with the floor of the thoracic cavity.
_Action._—A powerful muscle of expiration. In contracting, lessens the
cubic content of the thorax.
=The Diaphragm= (Fig. 47, No. 10; Fig. 33, No. 9). _Description._—The
diaphragm in the domestic fowl is rudimentary. It consists of a thin
semi-transparent membrane, situated between and separating the thoracic
and the abdominal cavities. It readily conforms to the various organs
pressing upon it from each side. On each side are three rudimentary
muscles which extend from the vertebral heads of the second, the third,
and the fourth sternal ribs. The fibers of these muscles spread out in
fan-like upon the diaphragm, and are seen just above the digitations of
the triangularis sterni.
THE ABDOMINAL MUSCLES
Obliquus abdominis externus
Obliquus abdominis internus
Rectus abdominis
Transversalis abdominis
=Obliquus Abdominis Externus= (Fig. 22, No. 1). _Location._—The
outermost muscle of the lateral abdominal wall.
_Attachments._—By a delicate aponeurotic membrane, from the sides of all
the true dorsal ribs, from the posterior border of the last vertebral
rib and the adjoining margins of the pelvis, and from the entire
posterior surface of the inferior border of the post-pubic element of
the pelvis; by aponeurosis, blending with the fascia toward the root of
the tail and lower part of the abdomen; and by aponeurosis to the sides
of the sternum, to the under part of the pectoralis major muscle, and to
the zyphoid prolongation. Also by aponeurosis it meets its fellow from
the opposite side, at the linea alba.
[Illustration:
FIG. 22.—The abdominal muscles of a hen. Right side. 1, Obliquus
abdominis externus. 2, Obliquus abdominis internus. 3, Peritoneum
covering intestines. 4, Peritoneum covering the gizzard. 5, The
lungs (note how small they are from a relative standpoint). 6, The
great sciatic or ischiadic nerve. 7, Lumbar nerves. 8, Kidney. 9,
Brachial plexus. 10, Pericardium of the base of the heart. 11,
Anterior vena cava. 12, Oil gland. 13, Showing a sacculation of the
abdominal muscles. There is no tunica abdominalis in the fowl.
]
=Obliquus Abdominis Internus= (Fig. 22, No. 2). _Location._—Just
internal with regard to the external oblique.
_Attachments._—By aponeurosis, from the posterior third of the
post-pubic element of the pelvis; by muscular fibers, from the balance
of the bone; and by a few fibers, from the iliac border posterior to the
acetabulum. Anteriorly, these fibers are inserted to the entire
posterior margin of the last vertebral rib, and into the pleurapophysial
head of the last costal rib.
=Rectus Abdominis= (Fig. 13, No. 10 and Fig. 23, No. 1). _Location._—The
inferior median abdominal wall.
_Attachments._—By aponeurosis, from the distal extremity of the
post-pubic element of the pelvis and from the semitendinous ligament
which stretches from one post-pubic tip to the other. Attaches
anteriorly to the zyphoid margin of the sternum, and passes, by a broad
aponeurotic membrane, over the outer surface of the thoracic wall
beneath the external oblique.
=Transversalis Abdominis= (Fig. 25, No. _H_, 1).
_Location._—Infero-lateral portion of the abdominal wall.
_Attachments._—By a thin, tendinous attachment from the entire
post-pubic and iliac margins of the pelvis and from the interpubic
ligament. Its fibers cross the abdomen between the peritoneum, the
rectum, and the internal oblique. It is inserted over the entire pleural
part of the last two vertebral ribs, the intercostal muscles between
them, and the same surface of the hemapophyses connected below. Inserts
into the linea alba.
_Action._—The abdominal muscles give support to the abdominal organs,
aid in flexing the spine, draw the last rib backward, thus aiding in
respiration, and compress the abdominal organs to aid in defecation and
expiration.
THE DORSO-LUMBAR REGION
Sacro-lumbalis
Longissimus dorsi
=Sacro-lumbalis.= _Location._—The lateral lumbo-sacral region.
_Origin._—Tendinous from the anterior margin of the ilium, from the
angles of the last two vertebral ribs, and by tendinous slips, from the
outer ends of the transverse processes of the last three dorsal
vertebræ.
_Insertion._—By a few fleshy fibers into the angle of the first dorsal
rib and to the corresponding points upon the free cervical ribs, and by
a strong semitendinous insertion into the outer extremity of the
diapophysis of the twelfth cervical vertebra.
_Shape._—A close fitting, tendo-muscular sheet extending between the
anterior margin of the ilium and the root of the neck.
_Relations._—Intimately blended with the longissimus dorsi externally.
_Action._—Assists the longissimus dorsi.
=Longissimus Dorsi= (Fig. 24, No. 4). _Location._—The superior
dorso-lumbar region.
_Origin._—From the inner portion of the anterior margin of the ilium,
and from the various surfaces afforded by its walls and the walls of the
ilio-neural canal; by a series of short and distinct tendons alternately
from the anterior and posterior extremities of the summits of the neural
spines of all the dorsal vertebræ. From the diapophyses of the dorsal
vertebræ, from the crests of the neural spines of the last three dorsal
vertebræ, from the bodies of the dorsal vertebræ, and from the fascia
between them and the sacro-lumbalis; and also by a tendinous sheet
continuous with the origin of the longus colli posticus.
_Insertion._—By four fasciculi into the free posterior margins of the
oblique processes of the eleventh, the twelfth, the thirteenth, and the
fourteenth cervical vertebræ.
_Shape._—A large flat sheet.
_Relations._—Laterally, with the superior spinous processes of the
vertebræ, and with the superior surface of the ribs.
_Action._—Singly, flexes the back laterally; with its fellow, aids in
elevating the body upward.
THE COCCYGEAL MUSCLES
Levator coccygis
Levator caudæ
Transversus peronei
Depressor caudæ
Depressor coccygis
Lateralis caudæ
Lateralis coccygis
Infracoccygis
=Levator Coccygis= (Fig. 23, No. 2). _Location._—The superior part of
the caudal apparatus.
_Origin._—From a limited area of the ilium just beyond and to the side
of the anterior free caudal vertebræ.
_Insertion._—Into the tuberosity of the anterior margin of the
pygostyle.
_Shape._—Short, fleshy.
_Relations._—Superior portion of the coccygeal vertebræ.
_Action._—Elevates the tail.
=Levator Caudæ= (Fig. 23, No. 4). _Location._—Supero-lateral side of the
tail.
_Origin._—From the posterior surface of the post-acetabular area of the
pelvis, and from the superior surface of all the coccygeal vertebræ
except the pygostyle.
_Insertion._—To the four inner quill butts of the main tail feathers.
_Shape._—Long, spindle-shaped.
_Relations._—Internally, with the levator coccygis and externally, with
the lateralis caudæ.
_Action._—Powerfully elevates the four inner main tail feathers.
=Transversus Peronei= (Fig. 23, No. 3). _Location._—The posterior
abdominal region.
[Illustration:
FIG. 23.—Outer layer of muscles of the tail and thigh, 1, Rectus
abdominis. 2, Levator coccygis. 3, Transversalis peronie. 4, Levator
caudæ. 5, Lateralis caudæ. 6, Depressor caudæ. 7, Sartorius. 8 and
9, Gluteus primus. 10, Semitendinosus. 11, Gastrocnemius. 12,
Peroneus longus. 13, Flexor perforatus indicis secundus pedis. 14,
Flexor perforatus medius secundus pedis. 15, Lateral ligament of the
hock.
]
_Origin._—From the entire posterior margin of the ischium, and from the
posterior margin of the post-pubis extending beyond it.
_Insertion._—Becoming aponeurotic, it passes toward the coccyx and is
attached to the entire posterior margin of the ilium. Passes to the
median line, meeting its fellow in front of the anus.
_Shape._—Thin, sheet-like.
_Relations._—Infero-anteriorly with the anus. Posteriorly with the edges
of the ilium and of the ischium. Internally with the depressor caudæ.
_Action._—Gives support to the viscera in the post-anal region, and aids
in attaching the anus to the structures above.
=Depressor Caudæ= (Fig. 23, No. 6). _Location._—The infero-lateral side
of the tail.
_Origin._—From the lower half of the posterior border of the ischium,
and from the entire posterior border of the post-pubis beyond.
_Insertion._—To the quill butts of the three or four outer main tail
feathers.
_Shape._—Strong, conical.
_Relations._—Externally, with the depressor coccygis.
_Action._—Singly, pulls the tail downward and outward; with its fellow,
pulls the tail downward.
=Depressor Coccygis.= _Location._—The outermost of the infero-lateral
muscles of the tail.
_Origin._—From the lower half of the posterior margin of the ischium and
the anterior three-fourths of the posterior margin of the post-pubic
element of the pelvis beyond it.
_Insertion._—To the thickened rim of the inferior and expanded portion
of the pygostyle.
_Shape._—Flat, triangular.
_Relations._—Internally with the depressor caudæ.
_Action._—Singly, pulls the tail downward and to one side; with its
fellow, pulls the tail downward.
=Lateralis Caudæ= (Fig. 23, No. 5). _Location._—The lateral side of the
tail.
_Origin._—From the tip of the transverse process of the first free
caudal vertebræ.
_Insertion._—To the outer three quill butts of the main tail feathers.
_Shape._—Four fasciculi forming a fleshy belly.
_Relations._—Inferiorly, with the levator caudæ and superiorly with the
depressor caudæ.
_Action._—Singly, pulls the tail downward and outward; with its fellow,
pulls the tail downward. The outermost fasciculus contracting, spreads
the tail feathers.
=Lateralis Coccygis= (Fig. 25, No. _E_, 2). _Location._—The
infero-lateral side of the caudal vertebræ.
_Origin._—From the surface of the posterior end of the ilium and by
tendons from the under side of the ends of the first three or four
caudal vertebræ.
_Insertion._—To the side of the posterior margin of the expanded portion
of the pygostyle.
_Shape._—Subcompressed mass.
_Relations._—With the transverse processes of the caudal vertebra,
inferiorly.
_Action._—Controls the lateral movements of the tail and its feathers,
and the oblique downward movement.
=Infracoccygis= (Fig. 25, No. _E_, 1). _Location._—The extreme inferior
portion of the caudal vertebræ.
_Origin._—From the inferior surface of the diapophysis of the last
vertebra which anchyloses with the pelvic sacrum, and from all the free
caudal vertebræ.
_Insertion._—Into the lower side of the pygostyle.
_Shape._—Flat, somewhat triangular.
_Relations._—Superiorly, with the vertebræ, laterally, with the
lateralis coccygis, and mesially, with its fellow of the opposite side.
_Action._—Depresses the tail.
THE COSTAL REGION
Latissimus dorsi
Trapezius
Rhomboideus
Serratus magnus anticus
Serratus parvus anticus
Teres et infraspinatus
Intercostales
Levatores costarum
Appendico-costales
=Latissimus Dorsi= (Fig. 24, No. 7). _Location._—Supero-lateral portion
of the dorsal region.
_Origin._—From two portions, the anterior slip from the outer edge of
the superior margins of the neural spines of the second and the third
dorsal vertebræ, and the second portion from a similar point on all the
succeeding dorsal vertebræ. The second portion is fascia-like in its
attachments.
_Insertion._—The fibers converge toward the humerus and enter between
the deltoid the scapular head of the triceps and the remaining heads of
this muscle and is inserted to the anconal part of the humerus, just
within in the radial crest.
_Shape._—Thin, triangular.
_Relations._—Superiorly, with the skin. The most superficial of the
dorsal muscles.
_Action._—To elevate the humerus and thus flex the shoulder-joint. An
expiratory muscle when the wing is fixed.
=Trapezius= (Fig. 19, No. 20). _Location._—In the shoulder region, just
below the longissimus dorsi.
_Origin._—From the neural spines of the second, the third, the fourth,
and the fifth cervical vertebræ just below the latissimus dorsi.
_Insertion._—To the mesian upper border of the scapula.
_Shape._—A flat oblong layer of fibers.
_Relations._—The posterior part of the trapezius overlies the anterior
part of the rhomboideus. The posterior two-thirds is covered by the
latissimus dorsi. The anterior third is superficial.
_Action._—Draws the scapula forward.
=Rhomboideus= (Fig. 19, No. 19). _Location._—Supero-posterior scapular
region.
_Origin._—From the neural spines of the first four dorsal vertebræ
beneath the latissimus dorsi and trapezius muscles.
_Insertion._—The fibers passing outward and backward attach to the
posterior third of the mesial or upper border of the scapula.
_Shape._—Thin, flat, delicate.
_Relations._—Superiorly, by the latissimus dorsi and the trapezius.
_Action._—To draw the free end of the scapula upward and forward.
=Serratus Magnus Anticus= (Fig. 13, No. 16). _Location._—The
supero-lateral side of the thorax.
_Origin._—By three strong digitations: first, from the outer part of the
second true rib just above the base of the epineural appendage; the
other two, from similar locations on the two succeeding ribs, just above
the origin of the dermo-ulnaris.
_Insertions._—The first by tendinous attachment to the
interpleurapophysial membrane. The rest of the fibers pass upward and
slightly forward, and are inserted to the inferior surface of the apex
of the scapula.
_Shape._—Three flat, strong digitations.
_Relations._—Internally, with the ribs.
_Action._—If the scapula is fixed, it is a muscle of inspiration.
=Serratus Parvus Anticus.= _Location._—The outer and upper surface of
the anterior part of the thorax.
_Origin._—By three digitations from the outer surface of the first three
ribs above the origin of the serratus magnus anticus and the
thoraco-scapularis.
_Insertion._—The thin sheet of fibers passes upward and backward, and is
inserted to the inferior margin of the scapula.
_Shape._—Thin, flat.
_Relations._—Internally, with the ribs.
_Action._—If the scapula is fixed, it is a muscle of respiration.
=Teres et Infraspinatus= (Fig. 13, No. 11). _Location._—Scapular region.
_Origin._—From the superior surface and outer margin of the posterior
two-thirds of the scapula.
_Insertion._—The fibers pass forward and outward, and insert to the
humerus at the middle of the ulnar margin of the pneumatic fossa,
between the forks of the triceps.
_Shape._ —Flat, triangular-shaped.
_Relations._—Anteriorly, with the supraspinatus. Internally, with the
ribs.
_Action._—Aids in keeping the humerus in its socket. Assists in closing
the wing by drawing the humerus to the side of the body.
=Intercostales= (Fig. 24, No. 5). _Location._—Between the ribs of the
upper thoracic region.
_Origin and Insertion._—From the anterior border of one rib, the fibers,
passing obliquely upward and forward, and the lower portion downward and
forward, are inserted to the posterior border of the rib just in front.
_Shape._—They are best developed in the anterior portion of the thoracic
region and extend down as far as the sternal ribs.
_Relations._—Internally the pleura, and anteriorly and posteriorly the
ribs.
_Action._—The first rib being rendered fixed by the scalenus medius, the
muscles draw the ribs forward, thus aiding inspiration.
=Levatores Costarum= (Fig. 24, No. 2). _Location._—Supero-lateral
portion of the thorax.
_Origin and Insertion._—A series of muscles, the first of which extends
from the extremity of the transverse process of the twelfth vertebra,
the fibers passing downward and backward to the anterior free margin of
the upper third of the long posterior rib, and to the external surface
close to its margin. The others arise and insert in a similar manner
from the ends of the diapophyses of all the dorsal vertebræ and attach
to each succeeding rib. Those in front are best developed.
_Shape._—Thin and triangular.
_Relations._—External to the intercostales.
_Action._—Aids in respiration.
=Appendico-costales= (Fig. 24, No. 1). _Location._—The lateral side of
the thorax.
_Origin and Insertion._—From the posterior edge of an uncinate process
or epineural appendage, the fibers extending downward and backward to
the outer surface of the succeeding rib.
_Shape._—A series of thin triangular-shaped muscles.
_Relations._—Internally, with the intercostales.
_Action._—Aids in respiration.
THE ANTERIOR PECTORAL GROUP
Tensor patagii longus
Tensor patagii brevis
=Tensor Patagii Longus= (Fig. 15_C_, No. 1; Fig. 14, No. 2).
_Location._—Anterior shoulder region, in the triangular patagium of the
wing.
_Origin._—By a flat tendon common to it and the tensor patagii brevis
from the supero-mesial line of the head of the clavicle.
_Insertion._—By a long slender tendon extending in the duplicature of
the patagium, with which the fibers blend. Passing to the side of the
extensor metacarpi radialis longus, it extends over the end of the
radius and is inserted to the os carpi radiale, and to the fascia which
binds down the other tendons on the anterior part of the wrist-joint.
_Shape._—Cone-shaped belly terminating in a long tendon.
_Relations._—Externally, with the skin; by its tendon, with the border
of the extensor metacarpi radialis longior.
_Action._—Tenses the soft part in the fold of the wing, and aids in
flexing the forearm.
=Tensor Patagii Brevis= (Fig. 14, No. 3). _Location._—In the triangular
patagium of the wing.
_Origin._—From the head of the clavicle in common with the preceding.
_Insertion._—The tendon bifurcates, one branch blending with the fascia
of the extensor metacarpi radialis longior, the other inserting just
below the tubercle on the external condyle of the humerus.
_Shape._—Fleshy; somewhat broader and longer than the preceding.
_Relations._—Interiorly, with the preceding.
_Action._—Assists the tensor patagii longus in flexing the forearm.
THE PECTORAL MUSCLES
Pectoralis major
Pectoralis secundus
Pectoralis tertius
=Pectoralis Major= (Fig. 13, No. 5). _Location._—On the lateral side of
the sternum.
_Origin._—From the posterior portion of the lateral wing of the sternal
body, from the outer marginal third of the keel of the sternum, and from
the entire outer side of the limb of the furcula or clavicle.
_Insertion._—The fibers converging form toward the proximal third of the
humerus a broad tendon which by its insertion covers the entire palmar
part of the pectoral crest. A few of the tendinous fibers pass over the
shoulder-joint and blend with the long head of the biceps. Near this
point it receives the insertion of the dermo-humeralis.
_Relations._—Interiorly, with the skin; superiorly, in the sternal
region, with the pectoralis secundus and the pectoralis tertius.
_Shape._—Fleshy; largest of the pectorales.
_Action._—Powerfully depresses the humerus. The chief muscle of flight.
=Pectoralis Secundus= (Fig. 13, No. 9; Fig. 15, No. _A_, 6).
_Location._—The entire lateral side of the sternum.
_Origin._—From the anterior sternal extremity of the lower third of the
coracoid, from the keel and sternal wing, and by a tendon from a
membraneous expansion between the coracoid and the clavicular bones and
from the lower third of the coracoid.
_Insertion._—The fibers converge into a tendon, which passes upward
around the coracoid to its posterior through a canal formed by the
scapula, the coracoid, and the clavicle, the foramen triosseum (Fig. 15,
No. _A_, 7). This tendon then passes outward and downward, and becoming
flat, inserts to the humerus just anterior to the radial crest and
nearer to the humeral head than does the pectoralis major.
_Relations._—Internally, with the breast-bone; externally, with the
pectoralis major; and superiorly, with the pectoralis tertius.
_Shape._—Long, fusiform, fleshy.
_Action._—Raises the wing.
=Pectoralis Tertius= (Fig. 13, No. 6; Fig. 15, No. _A_, 5).
_Location._—On the antero-lateral side of the sternum.
_Origin._—From the anterior half of the exterior of the body of the
sternum, from the fascia of the subclavius on the outer border of the
costal process, and from the outer, lower third of the coracoid process.