Teres Major Muscle

Description

Positioned on the posteroinferior scapula, the teres major courses from the dorsal surface of the inferior angle and adjacent lateral border toward the proximal humerus, forming a muscular band along the posterior axillary fold. Superior to it sit the teres minor and infraspinatus on the scapular dorsum, while the deltoid caps the lateral shoulder and the trapezius spans the upper back medial to the scapular spine. Anteriorly and laterally, the muscle converges to insert on the medial lip of the intertubercular sulcus (crest of the lesser tubercle), lying medial to the long head of triceps as it descends from the infraglenoid tubercle. Clear scapular and proximal humeral landmarks anchor the attachments. Teres major is often taught as latissimus dorsi’s close partner for shoulder extension, adduction, and medial rotation, but its surface anatomy is just as practical. The posterior axillary fold is a reliable landmark during axillary examination and posterior approaches to the shoulder, and it helps orient the clinician to the quadrangular space and triangular interval, where the axillary nerve and posterior circumflex humeral artery, or the radial nerve and profunda brachii artery, can be at risk. Confusion with teres minor matters. One is a rotator cuff stabilizer, the other is not. Use this plate in gross anatomy and kinesiology teaching to contrast teres major with teres minor and to map posterior shoulder landmarks onto palpation and surgical corridors, or in atlases and rehab texts discussing scapulohumeral rhythm and resisted adduction testing. Anatomical accuracy verified by SciePro's Medical Advisory Board.