Anterior Axillary Fold, Anterior View

Description

Arcing along the lateral thoracic wall, the anterior axillary fold is defined by the inferolateral border of pectoralis major as it converges toward its humeral insertion on the lateral lip of the intertubercular sulcus. Medial to the fold lies the anterior chest wall over the pectoralis major belly, while laterally the contour transitions into the proximal arm and deltopectoral region. Superior to the fold sits the apex of the axilla, with the underarm depression leading posteriorly toward the posterior axillary fold formed by latissimus dorsi and teres major. Surface anatomy, clearly legible. Clinically, this landmark anchors the bedside and operative map of the axilla: the floor of the axillary hair-bearing skin and the underlying axillary fascia sit immediately deep to it, and the axillary vein and cords of the brachial plexus lie just superior and medial as they pass toward the arm. Surgeons use the anterior axillary fold to plan incisions and dissection planes for axillary lymph node biopsy and clearance, and its relationship to pectoralis major matters during mastectomy, sentinel node procedures, and subpectoral implant pocket creation where the lateral border of pectoralis major defines the anterior limit of the dissection. Altered contour also flags pathology, including pectoralis major tendon rupture with loss of the normal fold, or axillary web syndrome after node dissection producing painful cord-like bands that tether the fold during shoulder abduction. Use this anterior perspective in gross anatomy and surface anatomy teaching to orient students to axillary boundaries and the pectoral region, and in surgical education materials covering breast surgery, axillary staging, and approaches to the brachial plexus and axillary vessels. It also fits patient-facing diagrams explaining underarm incisions and postoperative contour changes. Anatomical accuracy verified by SciePro's Medical Advisory Board.