Teres Major Under the Skin

Description

Positioned on the posterolateral thorax, the teres major is visible deep to the skin as it arises from the inferior angle and adjacent lateral border of the scapula, then runs superolaterally toward the proximal humerus. Its tendon converges anterior to the long head of triceps and inserts on the medial lip of the intertubercular sulcus (crest of the lesser tubercle), placing it medial to the greater tubercle and inferior to the shoulder joint capsule. Portions of the rib cage and thoracic vertebrae provide posterior midline context, while the scapula, clavicle, and proximal humerus define the shoulder girdle architecture. Skin and superficial soft tissues are kept light so the scapulohumeral relationships read cleanly. Clear landmarks. Teres major matters because it forms the posterior axillary fold with latissimus dorsi, a practical surface landmark when teaching axillary anatomy and when planning incisions or drains that traverse the axilla. Functionally, it adducts, extends, and medially rotates the humerus, and its close course to the quadrangular and triangular spaces makes it a useful orienting structure during posterior shoulder approaches and when discussing space-occupying lesions that can affect the axillary nerve or posterior circumflex humeral artery. Confusion with teres minor is common; the insertion on the humerus and the inferior scapular origin settle that quickly. Use this artwork in gross anatomy and kinesiology teaching to anchor scapular origins to humeral insertions, or in surgical texts discussing axillary landmarks, posterior shoulder exposure, and tendon transfers that recruit teres major in brachial plexus injury reconstruction. It also fits clinical education on shoulder mechanics and posterior axillary fold palpation in physical examination guides. Anatomical accuracy verified by SciePro's Medical Advisory Board.