The dorsal branch of the ulnar nerve: an anatomic study.

The dorsal branch of the ulnar nerve was dissected in 24 cadavers. The nerve arose from the medial aspect of the ulnar nerve at an average distance of 6.4 centimeters from the distal aspect of the head of the ulna and 8.3 centimeters from the proximal border of the pisiform. Its mean diameter at origin was 2.4 millimeters. The nerve passed dorsal to the flexor carpi ulnaris and pierced the deep fascia. It became subcutaneous on the medial aspect of the forearm at a mean distance of 5.0 centimeters from the proximal edge of the pisiform. The nerve gave an average of five branches with diameters between 0.7 and 2.2 millimeters. A better understanding of the anatomy of this nerve may help prevent nerve injury during surgical procedures, and can help in locating the nerve for repair of lacerations or administration of local anesthetics for regional nerve blocks.