Teres Major Muscle, Posterior View

Description

Arising from the dorsal surface of the inferior angle and adjacent lateral border of the scapula, the teres major forms a thick muscular band that runs superolaterally to insert on the medial lip of the intertubercular sulcus of the humerus, just medial to the latissimus dorsi tendon. From a posterior perspective it sits inferior to teres minor and the infraspinatus, while the posterior fibers of the deltoid drape laterally over the glenohumeral region. Along its inferior margin, teres major helps define the posterior axillary fold, with the long head of triceps brachii descending medial to it toward the olecranon. Fiber direction is easy to appreciate. This posterior angle matters because teres major is more than a “rotator” in the casual sense: it is a powerful adductor and internal rotator that couples with latissimus dorsi, and its relationship to teres minor creates the anatomical boundaries clinicians use to orient around the quadrangular space and triangular interval when tracking axillary nerve or posterior circumflex humeral artery course. It also comes up in the operating room when surgeons plan tendon transfers (latissimus dorsi and teres major transfer) for irreparable posterosuperior rotator cuff tears, where recognizing the plane between teres major and the scapular rotator cuff reduces confusion and iatrogenic injury. Small muscle, big consequences. Use this illustration in shoulder and back anatomy teaching to contrast teres major with teres minor and infraspinatus, and to reinforce tendon insertion on the proximal humerus in relation to the bicipital groove. It also supports surgical education materials on posterior shoulder approaches and axillary fold landmarks for physical examination and rehabilitation planning. Anatomical accuracy verified by SciePro's Medical Advisory Board.