Morphological study of the communication between the musculocutaneous and median nerves.

We investigated the incidence of each pattern of the communications between the musculocutaneous and median nerves and discussed its morphological significance. The communications between both nerves were seen in 188 (41.5%) of 453 specimens. They were classified into five regular patterns according to their directions and formations. The incidence of the communication was significantly higher in those with excessive heads of biceps brachii than in those without them (p < 0.05). As a result, we established a classification of the regular pattern of the communications and revealed that the musculocutaneous and median nerves had the possibility of forming plexuses in the humeral area. The musculocutaneous nerves are regarded as the bundles that arise from the median nerve with the lateral cutaneous nerve of forearm and the branches to the biceps brachii and brachialis muscles.