What is the primary function of the brachial vein?

The primary function of the brachial vein is to form the axillary vein in conjunction with the basilic vein. This process occurs as the brachial vein, which runs alongside the brachial artery, collects blood from the arm and forearm. As the brachial vein ascends, it converges with the basilic vein—another significant vein in the upper limb—thereby forming the axillary vein. This venous structure is vital as it serves as a major conduit for blood returning to the heart from the upper extremities.

While other options may mention important functions of veins in the upper limb, the specific role of the brachial vein in forming the axillary vein distinguishes it as the correct answer. The connection of the ulnar and radial veins is more about drainage from the forearm rather than the primary function of the brachial vein itself. Additionally, those veins serve different drainage roles, and the short-term vascular access refers more to specific approaches or devices rather than the foundational anatomical function of the brachial vein.