Teres Major Under the Skin, Gross Anatomy

Description

Arising from the posterior surface of the inferior angle and adjacent lateral border of the scapula, the teres major courses superolaterally toward the proximal humerus, forming a thick muscular band along the posteroinferior margin of the axilla. Deep to the dermal layer, it lies inferior to teres minor and posterior to the long head of triceps brachii, while its tendon converges with the posterior axillary fold in close relationship to latissimus dorsi. At the humerus, the insertion is on the medial lip of the intertubercular sulcus (crest of the lesser tubercle), just medial to the bicipital groove and adjacent to the tendon of the long head of biceps brachii. Posterior bony landmarks including the scapular spine, vertebral column, and posterior ribs provide orientation to the shoulder girdle. Teres major is a consistent landmark when teaching shoulder extension, adduction, and medial rotation, but its surgical relevance often gets overlooked because it blends visually with latissimus dorsi at the posterior axillary fold. That blend matters during posterior shoulder approaches and axillary dissection, where the quadrangular space (axillary nerve and posterior circumflex humeral artery) sits superior to teres major and the triangular interval (radial nerve and profunda brachii) lies inferior to teres minor and lateral to the long head of triceps. It also helps explain why tenderness or strain along the posterior axillary fold can mimic latissimus dorsi injury in throwing and climbing athletes. A short, stout muscle. Use this posterior upper back and shoulder rendering for gross anatomy lab practicals, kinesiology modules on glenohumeral mechanics, and surgical anatomy figures that need a clean correlation between scapular origin and humeral insertion under skin. It also fits musculoskeletal education content on posterior axillary fold contours and differential diagnosis of posterior shoulder pain. Anatomical accuracy verified by SciePro's Medical Advisory Board.