Muscles of the Abdomen and Thorax Beneath the Skin, Lateral View

Description

Seen from the left lateral aspect beneath the skin, the pectoralis major dominates the anterior thoracic wall, its broad clavicular and sternocostal fibers converging laterally toward the proximal humerus. Posterior and slightly superior to the pectoral mass, the deltoid caps the shoulder, while portions of the biceps brachii and triceps brachii appear along the anterior and posterior compartments of the upper arm. Inferior to the thorax, the lateral abdominal wall forms a continuous muscular sheet, with superficial fascia draped over the contour to emphasize uninterrupted trunk coverage. Clinical teaching benefits from this angle because it clarifies how the pectoralis major sits anterior to the thoracic cage and overlaps the axillary region, a relationship that governs surgical dissection planes and surface landmarks. Keep the insertion in mind. Pectoralis major tendon repair after rupture, and subpectoral implant or expander placement, both depend on recognizing the muscle’s inferolateral border and its transition into axillary fascia, while anterior shoulder pain patterns often track along the pectoral and deltoid interface rather than the glenohumeral joint itself. Use this plate in gross anatomy lab guides, sports medicine texts on chest and shoulder mechanics, and procedural education that references palpation lines for the anterior axillary fold or safe approaches around the deltopectoral interval. It also fits well in patient-facing materials explaining pectoralis major strains and tears, where a lateral profile communicates bulk and fiber direction quickly. Anatomical accuracy verified by SciePro's Medical Advisory Board.