<prompt> Posterior wall of axilla is formed byPectoralis majorPectoralis majorSubscapularisIntercostal muscles  <response>: Axilla armpitThe axilla is apyramidal space situated between the upper pa of the arm and the chest wall. It resembles afour 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 wall :- Formed by i Subcapularis, ii Teres major, and iii Latissimus dorsi.Medial thoracic wall :- Formed by i Upper four ribs with their intercostal muscles, and ii Upper pa of serratus anterior.Lateral humeral wall :- Formed by i Upper pa of humerus with bicipital groove lodging the tendon of long head of biceps, and ii Corachobrachialis and sho 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 pa of scapula and medially by outer border of first rib. The axillary aery and brachial plaxus enter the axilla through this canal. 