Pectoralis Major Muscles, Anterior View

Description

Centered on the anterior thorax of an adult male skeletal model, the paired pectoralis major muscles form broad, fan-shaped sheets spanning from the medial clavicle and anterior sternum to the proximal humerus. The clavicular head lies superior and slightly lateral to the sternocostal head, and their fibers converge laterally toward the bicipital (intertubercular) groove at the anterior shoulder. Deep to the muscle mass, the sternum and costal cartilages are visible in the midline, with the rib cage curving laterally and the glenohumeral articulation framed by the clavicle and scapula. Bilateral symmetry is clear. Anterior pectoralis major anatomy matters because its fiber direction explains function and common injury patterns: clavicular fibers bias flexion and horizontal adduction from an extended position, while sternocostal fibers drive adduction and internal rotation and are commonly stressed during the eccentric phase of a bench press. Ruptures typically occur at the humeral insertion or musculotendinous junction, leaving medial retraction and an altered anterior axillary fold, a physical exam finding surgeons correlate with MRI. The visible relationship to the clavicle, sternum, and proximal humerus also supports teaching the deltopectoral interval, a standard approach to the shoulder that tracks between deltoid and pectoralis major and preserves the cephalic vein. Use this asset in gross anatomy and kinesiology courses to map pectoralis major attachments onto palpable bony landmarks, and in orthopedic or sports medicine publications discussing pectoralis major tears, repair techniques, or postoperative rehab. It also fits patient education materials on chest wall musculature and shoulder mechanics. Anatomical accuracy verified by SciePro's Medical Advisory Board.