Teres Major Muscle Beneath the Skin, Posterior View

Description

Beneath a thin layer of superficial fascia, the teres major emerges on the posterior scapula, arising from the dorsal surface of the inferior angle and adjacent lateral border and coursing superolaterally toward the proximal humerus. Its muscle belly sits inferior to teres minor and inferior-lateral to the infraspinatus, while the posterior deltoid overlies the superior portion of the scapulohumeral musculature. Along the lateral margin of the scapula, teres major blends visually with the inferior fibers of latissimus dorsi as both converge to form the posterior axillary fold and insert near the intertubercular sulcus of the humerus. Trapezius frames the upper back, with the scapular spine and posterior shoulder contour guiding orientation. For teaching shoulder mechanics, this posterior cutaneous view clarifies how teres major functions as a powerful adductor and internal rotator rather than a true rotator cuff stabilizer, contrasting it with the highlighted teres minor, which contributes to external rotation and dynamic glenohumeral control. Injury patterns diverge: teres major strains are seen in throwing athletes and climbers, while isolated teres minor atrophy can point to axillary nerve involvement in the quadrilateral space or traction injury after anterior shoulder dislocation. Surface anatomy matters here. The posterior axillary fold is a palpable landmark during posterior shoulder approaches and axillary procedures. Orthopedic and sports medicine texts can pair this image with discussions of latissimus dorsi and teres major tendon transfers for irreparable posterosuperior cuff tears, where restoring external rotation depends on balancing teres minor function against internal rotators. Anatomy courses and radiology teaching files can also reference the scapular borders and posterior shoulder muscle layering when correlating with MRI of the rotator cuff interval and posterior soft tissues. Anatomical accuracy verified by SciePro's Medical Advisory Board.