Which of the following walls of axilla is formed by shaft of humerus:

Lateral wall of the axilla is formed by the inteubercular sulcus of humerus Boundaries of Axilla 1. Apex: It is directed upwards and medially towards the root of the neck. It is truncated (not pointed), and corresponds to a triangular interval bounded anteriorly by the clavicle, posteriorly by the superior border of the scapula, and medially by the outer border of the first rib. This passage is called the cervicoaxillary canal. The axillary aery and the brachial plexus enter the axilla through this canal. 2. Base or Floor It is directed downwards, and is formed by skin, superficial and axillary fasciae. 3. Anterior Wall It is formed by the following: The pectoralis major in front. The clavipectoral fascia enclosing the pectoralis minor and the subclavius; all deep to the pectoralis major. 4. Posterior Wall It is formed by the following: Subscapularis above. 5. Medial Wall It is formed by the following: Upper four ribs with their intercostal muscles. Upper pa of the serratus anterior muscle. 6. Lateral Wall It is very narrow because the anterior and posterior walls converge on it. It is formed by the following: Upper pa of the shaft of the humerus in the region of the bicipital groove, and Coracobrachialis and sho head of the biceps brachii. Teres major and latissimus dorsi below Ref: BDC-I, 5th ed., p-52