Teres Major Muscle, Posterior View

Description

Arising from the posterior surface of the inferior angle and adjacent lateral border of the scapula, the teres major courses superolaterally to reach the proximal humerus, where its tendon inserts on the medial lip of the intertubercular sulcus (crest of the lesser tubercle). From a posterior perspective, its thick muscular belly sits inferior to teres minor and posterior to the glenohumeral joint line, forming part of the posterior axillary fold as it approaches the arm. The long head of triceps brachii would lie medial and deep to its proximal fibers, while latissimus dorsi runs inferiorly and often blends near the humeral insertion. Clear bony landmarks include the scapular spine and acromion superiorly and the humeral head laterally. Teres major often gets taught as a helper of latissimus dorsi, but this view clarifies a point that matters in practice: the muscle is not a rotator cuff component and does not stabilize the humeral head like supraspinatus or infraspinatus. Its line of pull explains why resisted shoulder extension, adduction, and internal rotation can reproduce posterior axillary fold pain in throwing athletes and climbers, and why tendon transfer planning must respect its proximity to the radial nerve and posterior circumflex humeral vessels in the quadrangular space region. A frequent teaching trap is confusing teres major with teres minor based on naming alone. Orientation fixes that. Use this illustration in gross anatomy lab guides, orthopedic and sports medicine texts discussing posterior shoulder mechanics, and physiotherapy materials on internal rotator strengthening and differential diagnosis of posterior shoulder pain. It also suits surgical education when describing the posterior axillary fold and dissection planes near the humeral surgical neck. Anatomical accuracy verified by SciePro's Medical Advisory Board.