Cadaveric revelation of medial cutaneous nerve of the arm traversing the axillary vein.

A rare unilateral anatomical variation was observed in the left arm of a 62-year-old female cadaver. The medial cutaneous nerve of the arm pierced the axillary vein, arising from the medial cord of the brachial plexus and coursing posterior to the axillary artery. The nerve traversed the vein over a short segment, entering at approximately 6.5 cm and exiting at approximately 7.5 cm from the coracoid process. This unusual relationship has significant clinical implications in medical procedures, particularly in axillary venous access. Failure to recognize these alterations during axillary lymph node dissections or brachial plexus procedures increases the probability of iatrogenic nerve damage or venous trauma. This case highlights the importance of preoperative imaging and vigilant dissection techniques to accommodate anatomical variability, ultimately enhancing procedural safety and patient outcomes. Recognizing such variations is crucial to prevent sensory deficits, chronic neuropathic pain, and other complications.