The superficial anastomosis on the palm of the hand between the ulnar and median nerves.

The communications between the median and ulnar innervated territories on the palm of the hand have been studied anatomically and microscopically. A communicating branch is well appreciated but its description has had little emphasis in anatomical or surgical literature. 50 cadaveric palms were dissected in both sexes and an anastomotic branch was found in 45 hands. In 43 of them it originated proximally from the ulnar nerve and proceeded distally to enter the third common digital nerve; in the other two hands it left the median nerve to reach the fourth common digital nerve. By microscopic dissection we have seen that the ulnar fibres of the anastomotic branch which join the median nerve may contribute to the sensory innervation of the radial half of the ring finger and ulnar side of the middle finger on its palmar surface. We have therefore described a cutaneous area on the palm where care must be taken to avoid surgical damage to this branch.