Pectoralis Major Muscles Beneath the Skin, Anterior View

Description

Prominent on the anterior thoracic wall, the paired pectoralis major muscles form broad, fan-shaped sheets immediately deep to the skin, spanning from the medial clavicles and sternum toward the proximal humeri. Superiorly, the clavicular head lies adjacent to the infraclavicular region, while the sternocostal fibers sweep inferolaterally from the manubrium and body of the sternum toward the lateral lip of the intertubercular sulcus. Medially, the right and left muscles approach the sternal midline, and laterally they taper toward the anterior axillary fold at the junction with the arm. Fiber direction is clear. Anterior surface anatomy of pectoralis major matters because it sets the contour of the chest and defines the anterior axillary fold, a landmark used in examination and in operative planning around the axilla and upper arm. Clinically, the fan-like architecture helps explain common injury patterns, including tendon rupture near the humeral insertion during bench press, where patients often present with bruising, weakness in adduction and internal rotation, and loss of the anterior axillary fold. This view also supports teaching of pectoralis major transfer principles and the relationship of its heads to the deltopectoral groove, a standard interval for surgical access to the proximal humerus and shoulder. Useful for gross anatomy and kinesiology instruction when introducing shoulder girdle movers, and for sports medicine, orthopedics, and plastic surgery materials covering pectoralis major tears, chest wall reconstruction, or implant pocket anatomy. It also fits patient-facing education on male chest musculature and postoperative expectations after tendon repair. Anatomical accuracy verified by SciePro's Medical Advisory Board.