The axilla is a pyramid-shaped space located between the upper thorax and the arm. The axilla has a base, an apex, and 4 walls (anterior, medial, lateral, posterior). The base of the pyramid is made up of the axillary skin. The apex is the axillary inlet, located between the 1st rib, superior border of the scapula, and clavicle. The apex houses various vessels and nerves, including the axillary artery and its branches, the axillary vein and its tributaries, the branches of the brachial plexus, and the axillary lymph nodes.