Troubles neurologiques

Classifying Musculocutaneous Nerve Variations Depending on the Origin

Abstract

Lina Leng, Huaying Liu, Tiantao Wang, Li Liu and Daowen Si

Variations of the musculocutaneous nerve (MC) are not common. Much has been reported on the relationship in between the MC and the coracobrachialis muscle as well as the connections between the MC and median nerve. However, the classification of MC variations according to the origin of MC is seldom seen. We observed and analysed a total of 160 upper limbs from 80 adult cadavers to record anatomical variations in the MC. These variations were classified into five groups depending on the origin of MC: Group 1: The normal type. Classic description found in textbooks (142 arms, 88.75%); Group 2: Multi-branch type. Two or three branches originated from the lateral cord of the brachial plexus, dominating the corresponding muscles. (3 arms, 1.87%); Group 3: Mixed type. The lateral cord of the brachial plexus and median nerve sent branches to constitute the MC respectively. (1 arm, 0.63%); Group 4: Absence type. The MC originated from the median nerve directly. (5 arms, 3.12%); Group 5: Combining type. The MC originated from the lateral cord of the brachial plexus, then gave branches to the corresponding muscles, and finally joined the median nerve (9 arms, 5.63%). The new classification proposed is thought to make easy our clinical practice and to avoid errors caused by anthropometric differences.