Morphologic study on the patterns of communication between median and musculocutaneous nerves in humans

Several patterns of communication between the median nerve (MN) and the musculocutaneous nerve (MCN) have been described along with a number of classification systems. However, some atypical patterns of communication find no place in the existing classification systems. Knowledge about these variable communications is crucial for the accurate clinical management of peripheral nerve lesions of the upper limb.

48 formalin-fixed dissected specimens of upper limb (36 right and 12 left) were examined for presence of communications between MN and MCN. The observed gross anatomical features were recorded and photographed using a digital camera. Measurement of length and thickness of communications was done using a non-stretchable measuring tape and digital Vernier callipers.

A total of 8 communications were observed, all unilateral, extending from MCN to MN and located either in the axilla or in the arm. Five communications were on the right side and 3 on the left. Five communications adhered to typical previously reported patterns, while three were novel and atypical. Most communications arose from the MCN after it traversed the coracobrachialis (CRB) muscle, only one arising proximal to the CRB.

Eight cases of unilateral MN-MCN communication were found among the 48 upper limbs examined, including three atypical cases that cannot be categorized in any existing classification system and may therefore be easily missed during surgery. Their identification is crucial to avoid inadvertent damage during surgical procedures.