Communication between the musculocutaneous and the median nerves and its clinical significance

Chung, In Hyuk; Yoon, Kwan Hyun; Ra, Jong Joo; Kim, Dong Hwan; Yim, Joong Hyuk; Tanaka, Shigenori

Abstract

The purpose of this study was to investigate variations in the communicating branch between the musculocutaneous and the median nerves and to discuss their clinical significance. Seventy two arms from 36 Korean adults were used. Twenty four cases (33.4%) among 72 arms had communications between the musculocutaneous and the median nerves. In 19.5%, a communicating branch ran from the musculocutaneous to the median nerves and in 4.2% of these a communicating branch formed a loop. A branch running from the median to the musculocutaneous nerves was observed in 6.9%. There were more than two communicating branches between two nerves in 5.6%. The average angle between the musculocutaneous nerve proximal and distal to the coracobrachialis was 159+/-9degrees at adduction of the arm. The musculocutaneous nerve did not pierce the coracobrachialis muscle in 2.8%. One case (1.4%) showed partial fusion of the trunks of the musculocutaneous and median nerves. The musculocutaneous nerve ran next to the median nerve after the coracobrachialis muscle and coursed laterally in 5.6% with or without a communicating branch. In these cases, the angle of the musculocutaneous nerve was more acute. The musculocutaneous nerve entrapment is discussed with this angle.