The deep branch of the ulnar nerve in Guyon's canal: branching and innervation of the hypothenar muscles.

Thirty-seven embalmed, unpaired cadaver hands were dissected to delineate and classify the innervation of the hypothenar musculature. The deep branch of the ulnar nerve passed between the abductor digiti minimi and flexor digiti minimi and then pierced the opponens in all specimens. All branching occurred on the ulnar aspect of the deep branch of the ulnar nerve. A classification based on proximity of the different branches is prepared. Five different patterns have been noted.