axillary walls, the four walls of the axilla. The anterior wall is formed by the lateral part of the pectoralis major muscle, the pectoralis minor and subclavius muscles, and the clavipectoral fascia. The medial wall is formed by the upper thoracic wall and the serratus anterior muscle. The lateral wall is formed entirely by the intertubercular sulcus of the humerus. The posterior wall is formed by the costal surface of the scapula, the subscapularis muscle, the distal parts of the latissimus dorsi and teres major muscles, and the proximal part of the long head of the triceps brachii muscle.
