The anatomy of the dorsal cutaneous branch of the ulnar nerve.

We investigated the anatomy of the dorsal cutaneous branch of the ulnar nerve in 32 upper limbs in cadavers. The dorsal cutaneous branch of the ulnar nerve originated on average 5.1 cm proximal to the ulnar styloid process and 1.9 cm palmar and radial to the subcutaneous border of the ulna. It crossed the subcutaneous border 0.2 cm proximal to the ulnar styloid process. In all cases it displaced further away in full pronation. We recommend cautious dissection when approaching within 2.5 cm of the ulnar styloid process. We also recommend making the initial incision in full pronation and just along the dorsal aspect of the subcutaneous border of the ulna.