_Insertion_ (Fig. 82, _b_).--The fibres converge to the glenoid border, and the insertion is by a strong, flat tendon into the dorsal border of the lesser tuberosity of the humerus.
[Illustration: FIG. 77.--MUSCLES ON THE MEDIAL SIDE OF THE ARM.
M. epitrochlearis, M. clavobrachialis, and the breast-muscles have been removed. _a_, M. subscapularis; _b_, insertion of M. levator scapulæ and of M. serratus anterior; _c_, M. teres major; _d_, M. supraspinatus; _e_, M. latissimus dorsi (_e′_, cut edge of that part which becomes united with the bicipital arch); _f_, M. coracobrachialis; _g_, M. biceps brachii (the capsule of the joint has been laid open to show its tendon); _h_, cut insertions of pectoralis muscles; _i_, caput longum of M. triceps brachii; _j_, long portion of caput mediale of M. triceps brachii; _k_, intermediate portion of caput mediale of M. triceps brachii; _l_, short portion of caput mediale of M. triceps brachii; _m_, cut end of M. clavobrachialis; _n_, M. brachioradialis; _o_, M. extensor carpi radialis longus; _p_, M. extensor carpi radialis brevis; _q_, M. pronator teres; _r_, M. flexor carpi radialis; _s_, M. palmaris longus (_s′_, its tendons); _t_, M. flexor carpi ulnaris (_t_, ulnar head; _t′_, humeral head); _u_, third head of M. flexor profundus digitorum; _u′_, fifth head of M. flexor profundus digitorum; _u″_, one of the tendons of M. flexor profundus digitorum; _v_, M. pronator quadratus; _w_, M. abductor brevis pollicis; _x_, ulnar part of M. flexor sublimis digitorum. 1, transverse ligament of the wrist.]
_Relations._--Lateral surface with the scapula and the capsule of the shoulder-joint. Medial surface with the levator scapulæ (Fig. 73, _h_), serratus anterior (Fig. 73, _i_), part of the scalenus (Fig. 73, _f_), the transversus costarum (Fig. 73, _j_), and the coracobrachialis (Fig. 77, _f_). Cranial border with the supraspinatus (Fig. 77, _d_). Caudal border with the teres major (Fig. 77, _c_) and infraspinatus (Fig. 75, _c_).
_Action._--Pulls the humerus inward (mediad).
=M. teres major= (Fig. 75, _d_; Fig. 77, _c_).--A thick muscle, triangular in cross-section, lying parallel with the glenoid border of the scapula.
_Origin_ (Fig. 76, _j_; Fig. 78, _b_) from the vertebral one-third of the glenoid border of the scapula, and from fascia covering the subscapularis (Fig. 77, _a_) and the infraspinatus (Fig. 75, _c_) over a small area near the glenovertebral angle of the scapula. It may touch the insertion of the rhomboideus.