Pectoralis Major

Description

Anterior thoracic anatomy is centered on the pectoralis major of an adult male, spanning from the medial clavicle and anterior sternum to a broad insertion on the lateral lip of the intertubercular sulcus (crest of the greater tubercle) of the proximal humerus. The clavicular head lies superior and blends inferolaterally with the larger sternocostal fibers, which sweep laterally over the ribs and costal cartilages toward the shoulder. Deep to the muscle, the rib cage and sternum define the thoracic wall, while the clavicle and scapula frame the superior border of the chest and the glenohumeral region sits lateral to the muscle’s tendon. Clear bony landmarks. Clinically, this anatomy matters because the pectoralis major tendon is a frequent site of rupture in weightlifting, classically during the eccentric phase of a bench press, and knowing the fiber direction and humeral insertion helps differentiate a tendinous avulsion from a musculotendinous junction tear. Surgical repair commonly uses a deltopectoral approach with attention to the deltopectoral groove and the relationship of the tendon to the proximal humerus, and the visible clavicular versus sternocostal portions also support teaching of segmental actions (flexion versus adduction and internal rotation). The broad sternal attachment and lateral convergence at the humerus make the “anterior axillary fold” concept easy to explain in the context of physical examination and mastectomy or axillary node dissection planning. Ideal for gross anatomy lab atlases, thoracic wall and upper limb modules, sports medicine teaching on pectoralis major injuries, and surgical education materials covering deltopectoral exposure and proximal humeral landmarks. It also fits radiology primers that correlate surface anatomy with MRI or ultrasound evaluation of the pectoralis major tendon. Anatomical accuracy verified by SciePro's Medical Advisory Board.