and becoming tendinous as they reach the humerus, by a strong flattened
tendon insert to the ulnar crest of the humerus on the proximal margin
at about a middle point of the pneumatic fossa.
_Relations._—Externally, with the pectoralis major; interiorly, with the
pectoralis secundus; internally, with the fascia of the subclavius and
the sternum.
_Shape._—Fleshy, fusiform.
_Action._—Assists the pectoralis secundus in elevating the humerus.
MUSCLES OF THE SCAPULAR REGION
Coraco-humeralis
Scapulo-humeralis
Supraspinatus
Subclavius
Coraco-brachialis
Teres minor
Levator scapulæ
Thoraco-scapularis
Subscapularis
=Coraco-humeralis.= _Location._—The scapulo-humeral region.
_Origin._—From the outer side of the head of the coracoid,
supero-laterally to the long head of the biceps.
_Insertion._—To the palmar part of the head of the humerus just inside
of the insertion of the pectoralis major.
_Shape._—A delicate subcylindrical muscle.
_Relations._—Superior to the head of the humerus.
_Action._—Aids in extending the humerus.
=Scapulo-humeralis= (Fig. 14, No. 10). _Location._—The scapulo-humeral
region.
_Origin._—From the inner side of the neck of the scapula just within the
head of the deltoid.
_Insertion._—Passing over the top of the shoulder-joint it is inserted
to the palmar part of the humeral head between the insertion of the
pectoralis major and the pectoralis secundus.
_Shape._—Narrow, flat ribbon.
_Relations._—Along the upper margin of the larger portion of the
deltoid.
_Action._—Aids in extending the humerus.
=Supraspinatus= (Fig. 19, No. 22). _Location._—Scapular region.
_Origin._—From the superior surface and outer third of the scapula.
_Insertion._—To the lower border of the pneumatic fossa of the humerus.
_Shape._—Thin, flat, triangular.
_Relations._—Externally, with the trapezius and posteriorly, with the
teres et infraspinatus.
_Action._—If the scapula is the fixed point it will pull the humerus
upward and backward.
=Subclavius.= _Location._—Anterior sternal region.
_Origin._—From the entire outer surface of the sternal process of the
sternum and the adjacent outer surfaces of three or four of the
hemapophyses.
_Insertion._—To the inferior margin of the coracoid bone, the longer
fibers passing over to the fossa in the lower third of the posterior
part of the coracoid.
_Shape._—Rather small, fleshy.
_Relations._—Overlapped by the pectoralis tertius.
_Action._—Pulls the coracoid outward. Also aids in keeping the coracoid
in place.
=Coraco-brachialis= (Fig. 13, No. 15). _Location._—Along the coracoid
shaft.
_Origin._—By a delicate tendon from a small circular point on the
postero-mesial part of the shaft of the coracoid immediately above the
attachment of the subclavius and the fossa at that point.
_Insertion._—To the top of the ulnar tuberosity of the humerus. This
subcircular space is common to the teres minor and to this muscle.
_Shape._—Long, fusiform.
_Relations._—With the shaft of the coracoid between the teres minor and
subscapularis.
_Action._—To depress the wing.
=Teres Minor= (Fig. 13, No. 14). _Location._—The coraco-scapular region.
_Origin._—From under the side of the anterior tip of the scapula.
_Insertion._—Passing outward behind the coracoid head and beneath the
neck of the scapula, it is attached by a small tendon to the top of the
ulnar tuberosity of the humerus in common with the coraco-brachialis,
with which tendon it fuses.
_Shape._—Small, chunky.
_Relations._—Anteriorly, with the tip of the scapula and behind the
coracoid head. Posteriorly, with the coraco-brachialis.
_Action._—Aids in the downward stroke of the wing.
=Levator Scapulæ.= _Location._—Scapular region.
_Origin._—By two strong digitations, one from each of the lateral
processes of the first cervical vertebra.
_Insertion._—To the middle third of the inferior part of the blade of
the scapula.
_Shape._—Small and flat.
_Relations._—Inferior to the scapula.
_Action._—Pulls the scapula forward, and with it the entire shoulder
girdle, which articulates like a hinge-joint at the costo-sternal
juncture.
=Thoraco-scapularis.= _Location._—Lateral side of the chest.
_Origin._—From the outer part of the lower half of the first free rib,
the outer side of the next succeeding rib and its epineural appendage,
and from a similar surface on the next rib.
_Insertion._—By a broad, flat tendon which passes between the two
divisions of the subscapularis and inserts at a point at the juncture of
the anterior and middle third of the outer margin of the scapula.
_Shape._—Broad, flat.
_Relations._—Internally, with the ribs and the scapula.
_Action._—When the scapula is fixed it is a muscle of inspiration. When
the ribs are fixed, it draws the scapula downward.
=Subscapularis.= _Location._—Scapulo-humeral region.
_Origin._—From the anterior and outer half of the scapula.
_Insertion._—By a strong and subcylindrical tendon to the top of the
ulnar tuberosity of the humerus close to the combined tendons of the
coraco-brachialis and teres minor.
_Shape._—A large and powerful muscle.
_Relations._—The flat tendon of the thoraco-scapularis divides the
posterior portion of the belly into two portions.
_Action._—A powerful rotary muscle of the head of the humerus; aids in
keeping the humeral head in the glenoid cavity.
THE MUSCLES OF THE BRACHIAL REGION
Biceps
Triceps
Deltoid
Brachialis anticus
=Biceps= (Fig. 13, No. 8). (Synonym.—Biceps brachii.)
_Location._—The anterior brachial region.
_Origin._—By a broad tendon it covers the top of the shoulder-joint,
dividing into two heads, giving rise to the long and the short heads.
The long is inserted into the outer part of the head of the coracoid
just beyond the glenoid cavity; the short head to the distal angle of
the ulnar tuberosity of the humerus.
_Insertion._—To the ulna just in front of the articular cavity for the
trochlear surface of the distal extremity of the humerus.
_Shape._—Large, subfusiform.
_Relations._—On one side by the triceps and the other the deltoid and
anteriorly partially covered by the patagii muscles.
_Action._—A powerful flexor of the forearm.
=Deltoid= (Fig. 13, No. 12; Fig. 15, No. 8). _Location._—Occupying the
lateral side of the humerus; the brachial region.
_Origin._—Divided into two portions, the long narrow head extends from
the clavicular process of the scapula and from the adjacent surface of
the same bone. These fibers then extend around the back of the
shoulder-joint, and are joined by the fibers that arise from the entire
outer surface of the large os humero-scapulare. These latter fibers are
inserted upon an extensive area upon the anconal part of the bone beyond
the humeral articular head, and to almost the entire shaft below it.
_Insertion._—By a subcylindrical tendon to the proximal side of the
tubercle of the external condyle, and above the insertion of the
extensor metacarpi radialis longus.
_Shape._—Large, fleshy, with tendinous attachment.
_Relations._—On one side by the biceps and the other by the triceps also
the patagii.
_Action._—To extend the arm.
=Triceps= (Fig. 15, No. 7). (Synonym.—Triceps brachii.)
_Location._—The posterior humeral region.
_Origin._—By three portions: by the internal and external heads, and by
the long scapular head. The internal and the external heads are blended
except at their proximal extremities. Each head arises from the anconal
surface of the shaft of the humerus. The internal head being located
toward the deltoid attachment and the external head into the pneumatic
fossa. The long head extends from a circumscribed area just posterior to
the glenoid cavity of the scapula. The fibers pass around the
shoulder-joint, beneath the deltoid.
_Insertion._—The broad tendon passes over the elbow-joint and is
inserted to the entire under surface of the olecranon of the ulna.
_Shape._—Long, large, fleshy.
_Relations._—The supraspinatus passes between the internal and the
external heads. It is bounded by the biceps and the deltoid.
_Action._—An extensor of the antibrachial region directly antagonizing
the biceps.
=Brachialis Anticus= (Fig. 15, No. 9; Fig. 14, No. 5). _Location._—In
the flexure of the humerus and the ulna.
_Origin._—It arises fleshy from a circumscribed area on the inner side
of the anconal part of the distal extremity of the humerus.
_Insertion._—The fibers passing directly over the elbow-joint become
inserted to the lateral surface of the proximal end of the ulna close to
the margin of the sigmoid cavity.
_Shape._—Small, fleshy.
_Relations._—With the joint.
_Action._—Assists in flexing the forearm upon the arm. Protects the
structures in the anterior part of the elbow-joint.
THE MUSCLES OF THE FOREARM AND THE HAND
Extensor metacarpi radialis longior
Supinator brevis
Extensor digitorum communis
Pronator brevis
Flexor metacarpi radialis
Extensor ossis metacarpi pollicis
Pronator longus
Extensor indicis longus
Flexor digitorum sublimis
Flexor digitorum profundus
Flexor carpi ulnaris
Flexor carpi ulnaris brevior
=Extensor Metacarpi Radialis Longior= (Fig. 13, No. 17).
_Location._—Superior to the radius.
_Origin._—By two strong tendinous heads; the outer from the tubercle of
the external condyle of the humerus, just above the origin of the tendon
of the tensor patagii brevis; the inner and stronger portion from the
tubercle found above the oblique trochlear facet of the distal end of
the radius.
_Insertion._—Becoming a flat, broad, and strong tendon at about the
middle of the forearm, finally becomes inserted to the apex of the
anchylosed first metacarpal of the carpo-metacarpus.
_Shape._—A thick, fusiform belly, tendinous at both extremities.
_Relations._—By the side of the pronator brevis.
_Action._—Raises the hand, and draws it forward toward the radial margin
of the forearm and retains it on the same side.
=Extensor Digitorum Communis= (Fig. 15, No. 2). _Location._—The upper
metacarpal region.
_Origin._—Immediately below the tubercle of the external condyle of the
humerus.
_Insertion._—By a small tendon to the outer side of the base of the
pollex, and at a mid-point upon the anterior rim of the proximal phalanx
of the middle finger.
_Shape._—Small spindle-shaped, becoming tendinous at about the middle of
the forearm.
_Relations._—Occupies the middle of the group of muscles on the outer
side of the forearm.
_Action._—An extensor of the digit.
=Supinator Brevis= (Fig. 14, No. 7). _Location._—The superior part of
the radius.
_Origin._—From the external condyle of the humerus below the origin of
the tendon of the extensor digitorum communis.
_Insertion._—To the outer side of the shaft of the radius, for nearly
one-third of its length.
_Shape._—Thin, slender.
_Relations._—Inferiorly, with the bone.
_Action._—A supinator of the radial region, and antagonistic to the
pronators.
=Flexor Metacarpi Radialis= (Fig. 15, No. 10). _Location._—The lowest of
the group of three muscles on the outer part of the forearm.
_Origin._—By two tendinous heads, the longer from the external condyle
of the humerus, and the other just beyond the base of the olecranon.
_Insertion._—Becomes tendinous at about the middle of the shaft of the
ulna and inserts to a prominent process on the proximal third of the
posterior part of the shaft of the mid-metacarpal.
_Shape._—Fusiform.
_Relations._—Inferiorly, the anconeus and superiorly, the extensor
digitorum communis.
_Action._—A powerful flexor of the hand.
=Pronator Brevis= (Fig. 13, No. 18). _Location._—Supero-lateral side of
the forearm.
_Origin._—From just above the internal condyle of the humerus.
_Insertion._—The tendon passing obliquely across the interosseous space
and is inserted to the ulnar side of the shaft of the radius, just
beyond the juncture of the proximal and the middle thirds.
_Shape._—Fusiform.
_Relations._—Superior to the pronator longus.
_Action._—Pronates the forearm, and flexes the forearm upon the arm.
=Pronator Longus= (Fig. 14, No. 6). _Location._—Lateral side of the
radio-ulnar region.
_Origin._—From the middle of the internal condyle of the humerus.
_Insertion._—To the shaft of the radius just beneath the pronator
brevis.
_Shape._—Massive, ellipsoidal.
_Relations._—Between the pronator brevis and flexor digitorum profundus.
_Action._—A pronator.
=Extensor Ossis Metacarpi Pollicis= (Fig. 13, No. 23).
_Location._—Slightly interposed between the ulna and radius.
_Origin._—Immediately in front of the greater sigmoid cavity of the
ulna.
_Insertion._—To the palmar side of the base of the first metacarpal, in
common with the extensor metacarpi radialis longior.
_Shape._—Delicate, straight.
_Relations._—Superiorly, the extensor indicis longus, and inferiorly,
the anconeus and the flexor digitorum profundus.
_Action._—Extends the hand upon the forearm.
=Anconeus= (Fig. 15, No. 4). _Location._—Between the ulna and the
radius.
_Origin._—By a short, strong, subcylindrical tendon from the lower
posterior of the external condyle of the humerus.
_Insertion._—To the latero-radial side of the ulna somewhat beyond its
middle.
_Shape._—Fusiform.
_Relations._—Superiorly, the extensor indicis longus, and inferiorly,
the ulna.
_Action._—A flexor of the forearm.
=Extensor Indicis Longus= (Fig. 13, No. 22; Fig. 15, No. 13).
_Location._—Infero-lateral to the radius.
_Origin._—From about one-half the surface of the proximal portion of the
radius.
_Insertion._—Possesses a long tendon which passing over a groove at the
distal end of the ulna and receiving muscular fibers at the base of the
metacarpus, extends down the anterior part of the hand and is inclosed
in a sheath in front of the superior part of the first phalanx of the
index-finger. This tendon is inserted into the anterior upper rim of the
distal phalanx.
_Shape._—Small, thin.
_Relations._—Supero-laterally with the radius.
_Action._—Extensor of the digit.
=Flexor Digitorum Sublimis.= _Location._—The forearm.
_Origin._—From the internal condyle of the humerus.
_Insertion._—Passing over the wrist, it is inserted to the middle
phalanx of the hand.
_Shape._—A musculo-tendinous band, rather delicate and rudimentary.
_Relations._—Closely adhering to the integument that stretches from the
internal condyle of the humerus to the wrist.
_Action._—Assists these muscles. A flexor.
=Flexor Digitorum Profundus= (Fig. 13, No. 21). _Location._—Lateral side
of the ulna.
_Origin._—By two heads from the proximal extremity of the ulna, between
which the brachialis anticus passes.
_Insertion._—The two bellies uniting are attached to the under side of
the shaft of the ulna. It becomes tendinous about the middle of the
shaft, and inserts to the ulnar side of the base of the distal joint of
the index-finger.
_Shape._—A fleshy belly with long tendon.
_Relations._—Inferiorly, with the flexor carpi ulnaris, superiorly, with
the pronator brevis.
_Action._—A flexor of the digit.
=Flexor Carpi Ulnaris= (Fig. 13, No. 19). _Location._—Inferior part of
the forearm.
_Origin._—By two strong tendons; one from the side and posterior of the
internal condyle of the humerus, passing through the humero-ulnar pulley
at the side of the base of the olecranon process; the other, to the
posterior of the internal condyle of the humerus. It does not pass
through a pulley.
_Insertion._—A subcylindrical tendon extends back of the ulnare ossicle
of the carpus giving off a tendinous slip to the flexor digitorum
profundus, and becomes inserted to the anterior rim of the proximal
phalanx of the index digit. It has an attachment at the carpus.
_Shape._—A strong fleshy belly terminating in a long tendon.
_Relations._—The outermost inferior muscle of the forearm.
_Action._—A powerful flexor of the hand upon the forearm.
=Flexor Carpi Ulnaris Brevior= (Fig. 13, No. 20). _Location._—Inferior
part of the antibrachial region.
_Origin._—From a broad area on the middle third of the upper side of the
shaft of the ulna.
_Insertion._—Near the top of the outer edge of the anchylosed os magnum
of the carpo-metacarpus.
_Shape._—Thin, somewhat flat.
_Relations._—To the inside of the flexor digitorum profundus.
_Action._—Flexes the hand upon the forearm and rotates the hand toward
the body.
OTHER MUSCLES OF THE DIGITS
Extensor proprius pollicis
Flexor minimi digiti
Abductor minimi digiti
Interosseous palmaris
Flexor brevis pollicis
Flexor minimi digiti brevis
Interosseous dorsalis
Flexor metacarpi brevis
=Extensor Proprius Pollicis= (Fig. 13, No. 29a). _Location._—Anterior to
the radio-carpal joint.
_Origin._—From the ulnar side of the tendon of the extensor metacarpi
radialis longior.
_Insertion._—To the antero-ulnar side of the pollex.
_Shape._—Small, spindle-shaped; tendinous at both attachments.
_Relations._—Inferiorly, with the proximal and anterior part of the
metacarpus.
_Action._—An extensor of the pollex.
=Flexor Brevis Pollicis= (Fig. 13, No. 28a). _Location._—Anterior to the
pollex.
_Origin._—From the shaft of the mid-metacarpal bone, just below the
pollex.
_Insertion._—Distal apex of the pollex.
_Shape._—Short, small, fleshy.
_Relations._—Superiorly, with the inferior part of the pollex.
_Action._—Flexes the pollex.
=Flexor Minimi Digiti.= _Location._—Inferior side of the metacarpus.
_Origin._—From the posterior part of the median metacarpal close to the
os carpi ulnare. A few fibers extend to the ulna.
_Insertion._—Into the base of the median phalanx.
_Shape._—Small, slender, short.
_Relations._—Superiorly, with the metacarpal bone.
_Action._—A flexor of the digit.
=Flexor Minimi Digiti Brevis= (Fig. 13, No. 30). _Location._—Inferior to
the third, or small finger.
_Origin._—From the lower and posterior end of the median metacarpal and
from the adjacent tendon of the preceding.
_Insertion._—Inserted to the apex of the small finger.
_Shape._—Small and rather rudimentary.
_Relations._—Inferior to the small finger.
_Action._—Acts as a posterior ligament of this joint.
=Abductor Minimi Digiti.= _Location._—Supero-lateral side of the small
finger.
_Origin._—From the proximal extremity of the anterior aspect of the
third finger.
_Insertion._—To the posterior border of the proximal phalanx of the
second, or index-finger at a point just above the tip of the third
finger.
_Shape._—A few muscular fibers with some tendinous material.
_Relations._—At the base of the median segment of the index-finger and
to the side of the third.
_Action._—Antagonizes the powerful flexors on the back of the joint.
=Interosseus Dorsalis= (Fig. 13, No. 31). _Location._—By the side of the
metacarpus.
_Origin._—From the margin of the shaft of the median metacarpal.
_Insertion._—To the anterior part of the base of the distal phalanx of
the index digit.
_Shape._—Short, delicate, with long tendon.
_Relations._—Internally, the metacarpal bone.
_Action._—Extends the last bone of the middle finger.
=Interosseus Palmaris= (Fig. 13, No. 32). _Location._—On the opposite
side of the bone from the interosseous dorsalis.
_Origin._—From the shaft of the median metacarpal under the preceding.
_Insertion._—To the apex of the last joint of the second, or middle
finger.
_Shape._—Small, delicate, with long slender tendon.
_Relations._—Beneath the preceding and along the metacarpal bone.
_Action._—Flexes the terminal phalanx.
=Flexor Metacarpi Brevis.= _Location._—To the lateral side of the
metacarpal bone.
_Origin._—From the outer side of the distal extremity of the ulna.
_Insertion._—To the base, in front, and on the ulnar side of the
proximal phalanx of the index digit.
_Shape._—Delicate, with long slender tendon.
_Relations._—On the lateral side of the ulna and the metacarpal bone.
_Action._—Flexes the metacarpus.
MUSCLES OF THE POSTERIOR LIMB
Sartorius
Gluteus medius
Extensor femoris
Biceps flexor cruris
Semitendinosus accessorius
Femoro-caudal
Obturator internus
Abductor longus
Gluteus primus
Gluteus minimus
Vastus internus
Semitendinosus
Semimembranosus
Obturator externus
Gemellus
Adductor magnus
=Sartorius= (Fig. 23, No. 7). _Location._—Extreme anterior portion of
the thigh.
_Origin._—From the outer two-thirds of the superior surface of the
raised emarginations of the anterior border of the ilium, and by fascia
from the neural spines of the fourth dorsal vertebra.
_Insertion._—Obliquely by a semitendinous fascia to the inner edge of
the ligamentum patella, and to the inner and adjacent border of the
anterior half of the summit of the tibia.
_Shape._—Large, fleshy.
_Relations._—Posteriorly, with the gluteus primus and the vasti.
_Action._—Extends the leg, flexes and adducts the thigh.
=Gluteus Primus= (Fig. 23, No. 8 and 9). _Location._—The outer flat
massive muscle of the thigh.
_Origin._—By a thin fascia from nearly the entire length of the
supero-internal margin of the pre-acetabular portion of the ilium, above
the antitrochanter, and from the entire length of the post-acetabular
ridge.
_Insertion._—Near the patella it joins the tendon of the extensor
femoris, and by aponeurosis spreads over the knee and is inserted to the
crest of the upper border of the tibia, the patella being incorporated
in its aponeurotic ligament.
_Shape._—Triangular in shape, it is aponeurotic anteriorly and more
fleshy posteriorly.
_Relations._—Anteriorly, covers over the posterior portion of the
sartorius and the body of the gluteus medius; posteriorly, bordered by
the semitendinosus and the biceps.
_Action._—Abducts the thigh.
=Gluteus Medius= (Fig. 24, No. 11). _Location._—Supero-anterior part of
the ilium under the gluteus primus.
_Origin._—From the entire supero-internal margin of the pre-acetabular
surface of the ilium and the concave surface on the adjacent bone.
_Insertion._—By a strong tendon which passes over a bursa on the
anterior rim of the trochanter and is inserted obliquely to this
trochanter.
_Shape._—A fleshy muscle filling the concavity of the pre-acetabular
division of the ilium.
_Relations._—Superiorly, with the gluteus primus; inferiorly, with the
gluteus minimus.
_Action._—Abducts and pulls the femur forward.
=Gluteus Minimus= (Fig. 24, No. 12). (Synonym.—Gluteus profundus.)
_Location._—Beneath the medius and the smaller of the two.
_Origin._—To the anterior margin of the outer border of the ilium, and
from the supero-external surface of the last rib.
_Insertion._—The fibers extending downward and backward and outward
become tendinous and are inserted below the trochanter of the outer part
of the upper third of the femur.
_Shape._—Small, fleshy.
_Relations._—Inferiorly, with the bone and superiorly, with the gluteus
medius.
_Action._—Abducts and pulls the thigh forward.
=Extensor Femoris= (Fig. 24, No. 15). _Location._—Anterior femoral
region. It is divided into two parts: the vastus externus and the
crureus.
_Origin._—The vastus extemus (Fig. 24, No. 14) arises tendinous from the
base of the trochanter of the outer part of the femur and from this
point down the bone approximately to the condyle. The crureus (Fig. 24,
No. 13) originates by a tendon from the anterior upper prominent rim of
the trochanter, from this point extending down the antero-external part
of the shaft of the femur.
_Insertion._—Merges with the gluteus primus, and, by a fascia-like
arrangement, spreads over the front of the knee-joint inserts to the
patella and is also inserted into the crest of the tibia.
_Shape._—Large, fleshy.
_Relations._—Posteriorly, with the femur and anteriorly, with the
sartorius.
_Action._—Extends strongly the leg upon the thigh.
=Vastus Internus= (Fig. 16, No. 3). _Location._—Internal and lateral
side of the femur.