antero-dorsal border of the ilium.
_Insertion._—Passing forward as a delicate band it spreads out and
becomes lost in the skin of the shoulder region.
_Shape._—Thin, delicate, and ribbon-shaped.
_Relations._—Superiorly with the skin.
_Action._—If the posterior end is fixed, it will cause the feathers to
lie close to the skin. Its action would then be opposite to the
dermo-dorsalis.
=Dermo-ulnaris.= _Location._—Outer surface of the anterior upper costal
and the posterior humeral region.
_Origin._—By a thin fascia from the outer part of the third and the
fourth true ribs at the base of their epineural appendages. Also from
the fascia between them.
_Insertion._—The fibers pass forward and upward as a thick muscular
bundle and is loosely attached to the skin at a point just back of the
humerus. The tendon later becomes spread out and attached to the fascia
as far as the elbow-joint. It covers the olecranon of the ulna.
_Shape._—At first rather thick, fascicular-like; later becomes
tendinous; and at its attachment it becomes spread out over the
olecranon.
_Relation._—Inferiorly with the ribs and humerus, and externally with
the skin.
_Action._—A depressor of the humeral region.
THE SKELETAL MUSCLES
THE MUSCLES OF THE HEAD
Temporal
Masseter
Biventer maxillæ
Entotympanicus
Pterygoideus internus
Pterygoideus externus
Digastricus
=Temporal= (Fig. 19, No. 4). _Location._—Occupies the temporal fossa.
_Origin._—From the mesian line of the sphenotic process, and the
adjacent wall of the orbit.
_Insertion._—The fibers passing downward and forward blend with the
fibers of the masseter. Inferiorly it inserts by a tendon to the
coranoid process upon the superior ramal margin of the mandible.
_Shape._—Fan-shaped with broad portion uppermost.
_Relations._—It occupies the temporal fossa. It is related superiorly
with the dermo-temporalis and skin. Inferiorly, with the biventer
maxillæ and the masseter.
_Action._—It aids in closing the jaw.
=Masseter= (Fig. 19, No. 1). _Location._—Occupies the supero-lateral
portion of the surface of the lower jaw.
_Origin._—In two portions: the first, by a broad and thin tendon from
the entire length of the bony ridge above the external auditory meatus,
from the squamosal process, and from the outer portion of the quadrate
bone; the second, from the side and under border of the zygoma.
_Insertion._—The first portion: The fibers pass downward and forward
beneath the zygoma; a few of the fibers blend with those of the
temporal; one tendon inserts to a small tubercle on the upper border of
the jaw behind the coronoid process, and by fleshy insertion to the
outer side of the ramus of the lower jaw, quite as far forward as the
horny portion of the beak. The second portion: by a small tendon to the
mandible on its upper border immediately in front of the articular
portion.
_Shape._—Flat, and elongate. Somewhat fleshy.
_Relations._—Superiorly with the temporal, and inferiorly with the
biventer maxillæ and stylo-hyoideus. Externally with the skin, and
internally with the jaw bone.
_Action._—Aids in closing the jaw.
=Biventer Maxillæ= (Fig. 19, No. 3). _Location._—Covers the outer
posterior portion of the mandible.
_Origin._—It arises in two portions: The first, from a ridge bounding
the posterior part of the auditory canal; the second, from a depression
of the mesial side. These two parts blend and extend downward and
forward.
_Insertion._—To the posterior part of the articular end of the mandible.
_Shape._—A curved fleshy mass.
_Relations._—Superiorly with the temporal and stylo-hyoideus.
Posteriorly with the digastricus and genio-hyoideus. Internally with the
jaw bone, and externally with the skin.
_Action._—It aids in opening the jaw.
=Entotympanic.= _Location._—Posterior to the pterygoid.
_Origin._—From the side of the basi-sphenoid and from the base of the
rostrum immediately beyond it.
_Insertion._—The fibers pass downward and forward, and insert by a
double tendinous slip. One slip inserts to a spine-like process on the
upper side of the pterygoid, and the other to the quadrato-pterygoidean
articulation.
_Shape._—Spindle-shaped.
_Relations._—Anteriorly with the pterygoid. Internally and posteriorly
with the basi-sphenoid. Externally with the pterygoideus internus.
_Action._—Aids in raising the upper mandible by pulling forward the
quadratus and pterygoidean against the palatines.
=Pterygoideus Internus= (Fig. 17, No. _B_, 5). (Synonym.—Pterygoideus
medialis.[4])
Footnote 4:
According to international veterinary nomenclature.
_Location._—A muscular mass at the roof of the mouth.
_Origin._—From the major part of the surface of the palatine bone and
the distal head and shaft of the pterygoid and the sphenoidal
projection.
_Insertion._—By a tendon to the antero-internal part of the articular
part of the mandible.
_Shape._—Fusiform with a thick fleshy belly.
_Relations._—Superiorly with the palatine, the pterygoid, and the
sphenoid bones. Inferiorly with the skin.
_Action._—It aids in closing the jaw.
=Pterygoideus Externus.= (Synonym.—Pterygoideus lateralis.)
_Location._—Supero-external to the pterygoideus internus.
_Origin._—From the outer part of the extremity of the orbital process of
the quadrate.
_Insertion._—The fibers pass downward, outward and forward and are
inserted to the inner part of the mandibular ramus.
_Shape._—A small round bundle.
_Relations._—Inferiorly with the pterygoideus internus. Externally with
the inferior maxilla.
_Action._—Aids in closing the jaw.
=Digastricus= (Fig. 17, No. _B_, 16). _Location._—Extends from the
basi-temporal to the side of the neck.
_Origin._—From the external lateral angle of the basi-temporal.
_Insertion._—Opposite the angle of the jaw the fibers spread out in
fan-like arrangement. The muscle meets its fellow of the opposite side;
extends longitudinally over the superior larynx, for some distance down
the neck.
_Shape._—Thin and ribbon-shaped.
_Relations._—Externally to the platysma myoides. The anterior fasciculi
blend with those of the mylo-hyoideus; internally with the larynx at the
upper part.
_Action._—To raise the trachea and hyoid apparatus against the pharynx.
THE MUSCLES OF THE TONGUE
Mylo-hyoideus
Stylo-hyoideus
Genio-hyoideus
Cerato-hyoideus
Sterno-hyoideus
Depressor-glossus
Cerato-glossus
Hyoideus transversus
=Mylo-hyoideus.= _Location._—The forepart of the inter-ramal space.
_Origin._—From the inner side of the lower jaw at a point just above the
lower border and the inturned edge of the horny sheath of the beak.
_Insertion._—By aponeurosis to the under side of the hyoid, on the
median line between the first and the second basi-branchial.
_Shape._—Thin, flat, and delicate.
_Relations._—Inferiorly with the skin. Thin and rather broad, it meets
its fellow of the opposite side. Laterally with the rami of the jaw.
Superiorly with the hyoid apparatus.
_Action._—Lifts the tongue upward against the roof of the mouth.
=Stylo-hyoideus= (Fig. 17, No. _B_, 6). _Location._—Supero-posterior to
the hyoid apparatus.
_Origin._—From the outer portion of the articular enlargement of the
lower jaw.
_Insertion._—By a tendon to the basi-branchial of the thyro-hyal.
_Shape._—A long transversely flattened fasciculus.
_Relations._—Supero-posterior part of the hyoid apparatus along side the
genio-hyoideus and the cerato-hyoideus.
_Action._—Singly, pulls the tongue to one side; acting with its fellow,
pulls the tongue upward.
=Genio-hyoideus= (Fig. 9, No. 7). _Location._—Supero-posterior to the
hyoid apparatus.
_Origin._—From the anterior portion of the inner side of the lower jaw.
_Insertion._—To the middle of the outer side of the basi-branchial of
the corner of the os hyoides which cornu it completely envelops.
_Shape._—A long, rather thick fasciculus.
_Relations._—With the stylo-hyoideus and cerato-hyoideus.
_Action._—Protrudes the tongue from the mouth.
=Cerato-hyoideus= (Fig. 9, No. 8). (Synonym.—Kerato-hyoideus.)
_Location._—Inferior to the hyoid apparatus.
_Origin._—By a delicate tendinous slip from the under side of the shaft
of the basi-hyal element of the hyoid apparatus.
_Insertion._—To a small elevation on the under side of the anterior end
of the glosso-hyal.
_Shape._—A small round muscular fasciculus becoming tendinous in its
anterior half.
_Relations._—Superiorly with the hyoid apparatus.
_Action._—Singly, pulls the tongue to one side; acting with its fellow,
depresses the tongue.
=Sterno-hyoideus.= _Location._—Inferior to the hyoid apparatus.
_Origin._—From the outer anterior surface of the thyroid bone of the
superior larynx.
_Insertion._—To the anterior part of the basi-hyal.
_Shape._—At first broad and rather fleshy, becomes contracted and
somewhat tendinous.
_Relations._—Inferior to the hyoid apparatus and superior larynx.
_Action._—When the larynx is fixed, acting alone deflects the tongue
laterally; acting with its fellow, depresses the tongue. If the base of
the tongue is fixed the two pull the larynx forward. Hence muscles of
deglutition.
=Depressor-glossus.= _Location._—Superior to the basi-hyal.
_Origin._—From the under portion of the basi-hyal.
_Insertion._—To under part of the glosso-hyal.
_Shape._—Small, short.
_Relations._—Superiorly with the basi-hyal and glosso-hyal bones.
_Action._—Depresses the tip of the tongue and elevates the base.
=Cerato-glossus.= _Location._—On the upper portion of the cornu of the
hyoid.
_Origin._—One-half of the surface of the first basi-branchial.
_Insertion._—To the upper side of the shaft of the cerato-branchial
element of the hyoid apparatus.
_Shape._—A small muscular fasciculus.
_Relations._—Supero-laterally to the cerato-branchial element.
_Action._—Elevates the cornua of the hyoid arches and presses them
against the skull.
=Hyoideus Transversus= (Fig. 9, No. 9 and 10). _Location._—Envelops the
spur process of the euro-hyal.
_Origin and Insertion._—It extends from the inner side of one cornu to
the spur process.
_Shape._—Thin, flat.
_Relations._—Posterior to the euro-hyal, which it envelops, and between
the cornua of the os hyoides.
_Action._—Approximates the cornua of the os hyoides.
THE CERVICAL MUSCLES
Complexus
Rectus capitis anticus minor
Flexor capitis inferior
Rectus capitis posticus major
Biventer cervicis
Longus colli posticus
Obliquus colli
Longus colli anterior
Rectus capitis lateralis
Trachelo-mastoideus
Interspinales
Interarticulares
Obliquo-transversales
Intertransversales
Scalenus medius
=Complexus= (Fig. 19, No. 5). _Location._—Supero-lateral portion of the
neck.
_Origin._—By three tendinous slips from the antero-lateral portion of
the transverse process of the fourth, the fifth, and the sixth cervical
vertebræ.
_Insertion._—The muscular fibers pass around the neck and meet their
fellows in the median line in a fascia formation. The thin tendinous
sheet inserts into the occiput just above the occipital ridge.
_Shape._—From point of origin this muscle expands into a broad sheet.
_Relations._—It overlies the muscles of the occipital region.
_Action._—It extends the head.
=Rectus Capitis Anticus Minor= (Fig. 19, No. 8). (Synonym.—Rectus
capitis ventralis minor.)
_Location._—Infero-lateral portion of the neck.
_Origin._—From the apices of the hyapophyses of the second, the third,
and the fourth cervical vertebræ.
_Insertion._—To the occiput just below the complexus.
_Shape._—A long and rather thick fasciculus.
_Relations._—Externally with the skin. The tendinous slips of origin
pass between the flexor capitis inferior and longus colli anterior.
_Action._—Extends the head.
=Flexor Capitis Inferior= (Fig. 19, No. 7). _Location._—Antero-inferior
part of the neck.
_Origin._—From the apices of the hyapophyses of the second, the third,
and the fourth cervical vertebræ.
_Insertion._—To the triangular area on the basi-temporal of the base of
the cranium.
_Shape._—At first tendinous, becomes somewhat fleshy as it passes
forward.
[Illustration:
FIG. 19.—Muscles of the head and neck. 1, Masseter muscle. 2,
Infraorbital sinus. 3, Biventer maxilla. 4, Temporalis. 5,
Complexus. 6, Rectus capitis posticus major. 7, Flexor capitis
inferior. 8, Rectus capitis anticus minor. 9, Biventer cervicis. 10,
Longus colli posticus. 11, Obliquus colli. 12, Intertransversales.
13, Longus colli anterior. 14, Lateral temporo-maxillary ligament.
15, Lateral ligament of the jaw. 16, Trachelo-mastoideus. 17, Rectus
capitis lateralis. 18, Scalenus medius. 19, Rhomboideus. 20,
Trapezius. 21, Location of scapula. 22, Supraspinatus. 23, Teres et
Infraspinatus.
]
_Relations._—Antero-inferior portion of the neck close to the rectus
capitis anticus minor.
_Action._—Flexes the head upon the neck.
=Rectus Capitis Posticus Major= (Fig. 19, No. 6). (Synonym.—Rectus
capitis dorsalis major.)
_Location._—Supero-lateral area on the anterior portion of the neck.
_Origin._—From the median anterior aspect of the second cervical
vertebra, and the supero-anterior border of the neural canal.
_Insertion._—To the crescent-shaped area at the back of the skull.
_Shape._—Short, thick, fleshy bundle.
_Relations._—Superiorly with the complexus; inferiorly with the
trachelo-mastoideus and the vertebræ.
_Action._—Singly, pulls the head to one side; acting with its fellow,
extends the head.
=Biventer Cervicis= (Fig. 19, No. 9). _Location._—Occupies the superior
part of the neck.
_Origin._—From the side of the neural spine of the first dorsal
vertebra, and from the adjacent tendon of the longus colli posticus.
_Insertion._—To the occiput.
_Shape._—Tendinous in the middle with a more or less spindle-shaped
belly at each end.
_Relations._—Superior to the longus colli posticus. It lies next to the
skin.
_Action._—Extends the head on the neck and elevates the neck.
=Longus Colli Posticus= (Fig. 19, No. 10). (Synonym.—Longus colli
dorsalis.)
_Location._—Occupies the superior part of the neck.
_Origin._—From the marginal edges of the summits of the neural spines of
the first two dorsal vertebræ.
_Insertion._—To the transverse process of the axis, and superior part of
the cervical vertebræ.
_Shape._—A long, somewhat narrow, flattened muscle, the inferior portion
of which is divided into five or six fasciculi.
_Relations._—Superiorly with the biventer cervicis and inferiorly with
the vertebræ.
_Action._—Raises the neck upward.
=Obliquus Colli= (Fig. 19, No. 11). _Location._—On the lateral side of
the neck.
_Origin and Insertion._—The first of the seven fasciculi originates from
the diapophysis of the eleventh cervical vertebra, winds obliquely over
the tenth, and is inserted into the posterior margin of the
postzygapophysis of the ninth vertebra. In its passage it receives the
slip from the longus colli posticus. The next fasciculus originates from
the transverse process of the tenth cervical vertebra, winds obliquely
over the ninth vertebra, and is inserted to the postzygapophysis of the
eighth vertebra. In its passage it also receives a fasciculus from the
longus colli posticus. The next three fasciculi originate in a similar
manner being attached to similar postzygapophyses and have slips
extending forward which slips are inserted to the neural spines of the
alternate vertebræ. The sixth fasciculus originates from the transverse
process of the sixth vertebra, passing obliquely up the neck is inserted
to the extremity of the diapophysis of the fourth vertebra, the outer
extremity of the transverse process of the third vertebra. The seventh,
or anterior, fasciculus originates from the transverse process of the
fifth vertebra, and is inserted to the extremity of the diapophysis of
the third vertebra.
_Shape._—Short, thick fasciculi.
_Relations._—Laterally with the vertebræ. Inferiorly with the
intertransversales. Superiorly with the longus colli posticus, and
externally with the skin.
_Action._—Flexes one vertebra on the other laterally.
=Longus Colli Anterior= (Fig. 19, No. 13). (Synonym.—Longus colli
ventralis.)
_Location._—Occupies the anterior portion of the neck.
_Origin and Insertion._—This muscle is divided into a vertical portion,
and a superior and an inferior oblique portion. The vertical portion
originates from the hypophyses of the tenth to the fifteenth vertebra
and is inserted by a tendon to the tubercle on the inferior portion of
the atlas. Small, slender tendons are given off and insert to the apices
of the parapophyses of the fourth to the tenth cervical vertebræ. There
is more or less attachment to the bodies of the cervical vertebræ
mentioned. The superior oblique portion originates from the diapophyses
of the third, the fourth, the fifth cervical vertebræ and becoming
tendinous is inserted to the tubercle on the inferior portion of the
body of the atlas. The inferior oblique portion originates from the
transverse processes of the fourth, the fifth, and the sixth cervical
vertebræ. It is inserted by a slender tendon to the apex of the
parapophysis of the third cervical vertebra.
_Shape._—A long fleshy muscle extending the entire length of the neck.
_Relations._—Inferiorly with the skin and superiorly with the cervical
vertebræ.
_Action._—Pulls the neck downward.
=Rectus Capitis Lateralis= (Fig. 19, No. 17). _Location._—The
infero-lateral anterior portion of the neck.
_Origin._—Originates tendinous from the diapophysis of the third, the
fourth, and the fifth cervical vertebræ.
_Insertion._—Passes obliquely upward in front of the spinal column to
the inner tubercle on the basal ridge of the basi-temporal bone, by a
subcompressed tendon.
_Shape._—A somewhat thick fasciculus.
_Relations._—Superiorly with the trachelo-mastoideus, inferiorly with
the longus colli anterior, and externally with the skin.
_Action._—Singly, pulls the head down and to one side; acting with its
fellow, pulls the head downward.
=Trachelo-mastoideus= (Fig. 19, No. 16). (Synonym.—Longissimus capitis
et atlantis.)
_Location._—Laterally on the anterior portion of the neck.
_Origin._—Semitendinous from the diapophyses of the second, the third,
the fourth, and the fifth cervical vertebræ.
_Insertion._—By subcompressed tendon to the base of the cranium, at the
outer tubercle of the basal ridge of the basi-temporal.
_Shape._—Flattened from side to side; broad at the posterior portion,
becomes angular at the anterior portion.
_Action._—Singly, pulls the head down and to one side; acting with its
fellow, pulls the head downward.
=Interspinales= (Fig. 17, _A_, No. 2). _Location._—Superior to the
vertebra.
_Origin and Insertion._—A series of muscles connecting the superior
neural spines of the cervical vertebræ.
_Shape._—Thin, flat.
_Relations._—Anteriorly the posterior border of the vertebræ in front
and posteriorly the anterior border of the succeeding vertebræ,
inferiorly by the vertebræ.
_Action._—To approximate the spinous portion of the vertebræ.
=Interarticulares= (Fig. 17, No. _A_, 4). _Location._—Supero-laterally
to the vertebræ. Between the postzygapophysis.
_Origin and Insertion._—From the posterior margin of the ring of the
atlas to the postzygapophysis of the axis. Then in the succeeding
vertebræ from the postzygapophysis of the vertebra to the same of the
succeeding vertebra.
_Shape._—Muscular bundle.
_Relations._—Inferiorly with the vertebræ. Supero-laterally with the
obliquo-transversales.
_Action._—Aids in approximating the vertebræ in a supero-lateral
direction.
=Obliquo-transversales= (Fig. 17, _A_, No. 1).
_Location._—Supero-lateral to the vertebræ.
_Origin and Insertion._—Passes obliquely from the transverse process of
one vertebra to the postzygapophysis of the vertebra beyond.
_Shape._—A thin fasciculus.
_Relations._—Inferiorly with the interarticulares and laterally with the
intertransversales.
_Action._—Aids in flexing the vertebræ supero-laterally.
=Intertransversales= (Fig. 19, No. 12). _Location._—Laterally to the
vertebræ.
_Origin and Insertion._—Extend between the transverse processes
beginning at the third cervical vertebra.
_Shape._—Short, thick.
_Relations._—Laterally the vertebræ. Superiorly the
obliquo-transversales.
_Action._—Aids in flexing the vertebræ laterally.
=Scalenus Medius= (Fig. 19, No. 18). (Synonym.—Scalenus.)
_Location._—Supero-laterally to the entrance of the thorax.
_Origin._—From the diapophysis and pleurapophysis of the eleventh
cervical vertebra.
_Insertion._—To the entire border of the first rib. A few fibers pass
over to the anterior free margin of the middle third of the second rib.
_Shape._—Rather pyramidal in shape with base uppermost.
_Relations._—Posteriorly with the levatores costarum. Internally with
the longus colli.
_Action._—When the first rib is fixed singly, turns the neck to one
side; acting with its fellow, extends the neck. When the neck is fixed,
by drawing the first rib forward, it acts as an inspiratory muscle.
THE MUSCLES OF THE AIR PASSAGES
The Superior Larynx
Constrictor glottidis
Thyreo-arytenoideus
The Inferior Larynx
Tracheo-lateralis
Broncho-trachealis posticus
Broncho-trachealis anticus
Broncho-trachealis brevis
Bronchialis posticus
Bronchialis anticus
Sterno-trachealis
=Constrictor Glottidis.= _Location._—Supero-anterior portion of the
superior larynx.
_Origin._—From the superior and longitudinal line of the thyroid plate.
_Insertion._—All along the inner margin of the arytenoid bone, and to
the apex of the mid-cricoidal segment.
_Shape._—Thin, flat sheet extending outward and upward, and then inward.
_Relation._—Interiorly with the larynx.
_Action._—The two muscles of this kind acting together, close the
glottis by drawing the apices of the arytenoids to the median line.
=Thyreo-arytenoideus.= _Location._—Supero-lateral portion of the
superior larynx.
_Origin._—From the entire outer margin of the thyroid plate and the
outer margin of the cricoid bone.
_Insertion._—All along the outer margin of the arytenoid bone and the
outer border of the central cricoid piece.
_Shape._—A thin, flat sheet.
_Relations._—Infero-laterally with the superior larynx.
_Action._—The two muscles of this kind acting together, open the glottis
by pulling the arytenoid bone outward.
=Tracheo-lateralis= (Fig. 20, No. 2). _Location._—Along the lateral side
of the trachea.
_Origin._—By the union of the bronchio-trachealis posticus and
bronchio-trachealis anticus, on the lateral side of the trachea, about
1½ centimeters from the bifurcation of the trachea.
_Insertion._—In delicate fan-like structure to the side of the trachea,
near the superior larynx.
_Shape._—Thin, ribbon-shaped, closely attached to the trachea.
_Relations._—Internally with the trachea, and externally with the skin
and other integument.
_Action._—Acts as a brace to the sides of the trachea, and contracting,
approximates the tracheal rings and thus shortens the trachea.
=Broncho-trachealis Posticus= (Fig. 21, No. 3).
_Location._—Postero-superior portion of the trachea. The fibers pass
downward and backward.
_Origin._—From the inferior end of the tracheo-lateralis.
_Insertion._—To the end of the third half of the bronchial ring of the
same side.
_Shape._—A small fasciculus.
_Relations._—Internally with the trachea, and externally with the skin
and other integument.
[Illustration: