Part 33

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.