The axillary vein is a major blood vessel located in the upper arm and shoulder area. It is formed by the convergence of the brachial veins and the basilic vein, and it plays a crucial role in draining deoxygenated blood from the arm and surrounding regions back to the heart. The axillary vein runs alongside the axillary artery, which supplies oxygenated blood to the arm. This vein eventually becomes the subclavian vein as it passes the outer border of the first rib. The axillary vein is important for various medical procedures, including the placement of central venous catheters, and it is often assessed in cases of vascular diseases or injuries.