Teres Major Muscle

Description

Posterior upper-torso anatomy centers on the scapula and proximal humerus with the vertebral column and posterior ribs as the bony framework. Along the inferior angle and adjacent lateral border of the scapula, the teres major arises as a broad, fleshy band and courses superolaterally toward the medial lip of the intertubercular sulcus (crest of the lesser tubercle) of the humerus, lying inferior to teres minor and posterior to the glenohumeral joint capsule. Medial to it sit the thoracic spinous processes and costovertebral contours; laterally, the humeral head and surgical neck establish the proximal arm relationship. Orientation is clear. Teres major matters because it forms the posterior axillary fold with latissimus dorsi and becomes a practical landmark when working near the quadrangular space and radial nerve trajectory in the posterior shoulder. Functionally it adducts, extends, and medially rotates the humerus, so distinguishing it from the rotator cuff is key when teaching glenohumeral mechanics, examining weakness patterns, or describing altered scapulohumeral rhythm after shoulder injury. Its insertion beside the bicipital groove also helps explain why anterior shoulder pain workups often separate biceps tendon pathology from posterior axillary fold strain, despite their close humeral real estate. Ideal for gross anatomy teaching of the scapular region, kinesiology modules on glenohumeral motion, and surgical anatomy references that need a clean posterior landmark for the axilla and proximal humerus. Medical publishers can also pair it with shoulder MRI or ultrasound chapters to clarify what sits superficial to the joint versus what stabilizes it. Anatomical accuracy verified by SciePro's Medical Advisory Board.