ANATOMY AND INTERNAL TOPOGRAPHY OF THE MUSCULOCUTANEOUS NERVE - THE NERVES TO THE BICEPS AND BRACHIALIS MUSCLE

One hundred twelve musculocutaneous nerves from 56 cadavers were exami ned to determine branching patterns of innervation and internal neurot opography. There were 3 distinct types of branching patterns for bicep s innervation: in 62%, there was 1 branch only; in 33%, 2 branches; an d in 5%, 3 branches. The origin of the first branch averaged 130 mm fr om the acromion regardless of branching type. The maximum distance bet ween the first and second branch was 53 mm. In 92%, there was only 1 b ranch to the brachialis muscle. It always emerged from the main trunk distal to the nerve to the biceps and averaged 170 mm from the acromio n. Internal topography was studied from 1-mm-thick serial sections of the musculocutaneous nerve in 5 fresh cadaver arms. The group of fasci culi of the nerve to the biceps, the nerve to the brachialis, and the lateral cutaneous nerve of the forearm were constantly located from la teral to medial. The fasciculi of the nerve to the biceps traveled pro ximally in the musculocutaneous nerve for an average distance of 63 mm . Copyright (C) 1998 by the American Society for Surgery of the Hand.