Teres Major

Description

Positioned on the posterior axillary fold, the teres major is shown as a thick, rounded muscle belly coursing from the inferior angle and lateral border of the scapula toward the proximal humerus. Superior and slightly lateral to it, the teres minor and posterior deltoid frame the posterior shoulder, while the latissimus dorsi lies inferiorly and blends toward the same humeral region, creating the familiar muscular contour of the posterior axilla. Medially, the trapezius spans the upper back toward the scapular spine, with rhomboid fibers implied deep to it, and the erector spinae columns track longitudinally alongside the thoracic spine. Fiber direction is explicit. Teres major matters because it shares insertional territory with latissimus dorsi at the medial lip of the intertubercular sulcus, a relationship that helps explain coupled adduction, extension, and medial rotation at the glenohumeral joint. For clinicians, this posterior view is practical when teaching palpation of the posterior axillary fold and when differentiating a true latissimus dorsi strain from a teres major injury seen in throwing athletes, climbers, or during resisted adduction and extension. Surgeons also reference this region when discussing tendon transfers and when orienting to the quadrangular and triangular spaces, where the nearby axillary nerve and posterior circumflex humeral artery, or the circumflex scapular artery, can be at risk. Use this asset in shoulder and upper limb anatomy labs, sports medicine content on posterior shoulder pain patterns, and operative teaching materials that contrast the posterior axillary fold with the rotator cuff interval and deltoid approach landmarks. It also reads well in rehabilitation manuals explaining strengthening progressions for latissimus dorsi and teres major without conflating them with teres minor or infraspinatus. Anatomical accuracy verified by SciePro's Medical Advisory Board.