What structure does the cephalic vein pierce before entering the axillary vein?

The cephalic vein is an important superficial vein of the arm that ascends along the lateral aspect of the forearm and arm before draining into the axillary vein. As it approaches the axilla, it passes through a structure known as the clavipectoral fascia.

The clavipectoral fascia, also referred to as the costocoracoid membrane, is a sheet of connective tissue that lies deep to the pectoralis major muscle. It extends from the clavicle to the pectoralis minor muscle and helps support the vessels and nerves that pass between the axilla and the upper limb. The cephalic vein pierces this fascia to enter into the deeper structures of the axillary region, allowing its termination in the axillary vein to occur.

The other structures listed do not serve this function. The pectoralis major is a muscle rather than a fibrous structure through which the cephalic vein pierces. The anatomical snuffbox is an area on the dorsum of the hand associated with different anatomical landmarks and does not relate to the pathway of the cephalic vein. The subclavian vein is also a larger vessel that does not interact directly with the cephalic vein in this particular context prior to its