<prompt> Posterior w all of axilla is formed by -Pectoralis majorSubclaviusSubscapularisIntercostal muscles  <response>: Ans. is c i.e., Subscapularis Axilla armpito The axilla is a pyramidal space situated between the upper part of the arm and the chest wall. It resembles a four sided pyramid, and has following : i an apex ii a base iii four walls anterior, posterior, medial and lateral.Anterior pectoral wall Formed by i Pectoralis major; ii Pectoralis minor, and iii Subclavius. The . latter two muscles enclosed by clavipectoral fascia.Posterior subscapular wallFormed by i Subcapularis. ii Teres major, and iii Latissimus dorsi.Medial thoracic wallFormed by i Upper four ribs with their intercostal muscles, and ii Upper part of serratus anterior.Lateral humeral wallFormed by i Upper part of humerus with bicipital groove lodging the tendon of long head of biceps, and ii Corachobrachialis and short head of biceps -Base Formed by Skin, superficial fascia and deep axillary fascia. It is directed downwards.Apex It is directed upwards and medially towards the root of neck. It communicates with supraclavicular triangle of neck, hence referred to as Cervicoaxillary canal. It is triangular in shape and is bounded anteriorly by clavicle, posteriorly by upper part of scapula and medially by outer border of first rib. The axillary artery and brachial plaxus enter the axilla through this canal. 