(2 of 3)
This pyramidal-shaped space is bounded by a base, apex, and four walls (Figure 5.2). The base is formed by the skin and associated fascia of the armpit. The apex of the axilla is directed toward the cervicoaxillary canal, a triangular-shaped space bounded by the 1st rib, clavicle, and the upper border of the scapula. The anterior wall is formed by the pectoralis major muscle and two muscles that are surrounded by the clavipectoral fascia, the pectoralis minor and subclavius muscle. The upper portion of the posterior wall is formed by the subscapularis muscle; the lower portion by the latissimus dorsi muscle and teres major muscle. The medial wall is formed by the upper ribs (2nd to 6th) and the serratus anterior muscle. The lateral wall is the bicipital groove of the humerus .