Fig. 1

From bony to muscular edges of the axillary region. The axilla is an irregular-in-shape anatomical region (light blue) located between the ribs, the scapula, the clavicle (Cla) and the proximal humerus (Hum) (A). The pectoralis major (P Maj) and minor (P Min) muscle in the anterior compartment, the coracobrachialis (Cor B) and short head of the biceps brachii muscle (shBB) in the lateral section, the serratus anterior muscle (black arrowheads) medially; and the subscapularis muscle (SSC), the teres major and latissimus dorsi muscle (LD) in the posterior compartment, can be considered the “soft” anatomical landmarks to better define this complex anatomical space (B). Cor: coracoid; yellow asterisk: cervicoaxillary canal; black dotted lines: quadrants