Ulnar nerve entrapment at the wrist.

MEDIAN nerve compression at the wrist is common and its treatment by decompression is usually successful. Ulnar nerve entrapment, on the other hand, is uncommon. The ulnar nerve as it enters the hand passes through and divides in the canal of Guyon, into its deep (motor) and superficial (sensory) branch. This ulnarcarpal tunnel is bounded proximally and medially by the pisiform, distally and laterally by the hook of hamate, anteriorly by the volar carpal ligament and posteriorly by a thick carpal ligament overlying the pisotriquetrial articulation. Proximal to the wrist the ulnar nerve gives off its dorsal cutaneous branch. Two cases of ulnar nerve entrapment at the wrist are described.