Clarification of the Distribution Pattern of the Twig(s) of Radial Nerve Innervating Brachial Muscle in Human

To clarify the distributional pattern of the radial nerve branches innervating the lateral lower part of the brachial muscle, 76 Japanese cadavers (152 sides) were examined, and the number and patterns of the branches were recorded and classified. The results showed that (1), the mean lengths from the lateral epicondyle to the point where the radial nerve pierces through the lateral intermuscular septum were 97.4 mm (range, 70-140 mm) and 96.7 mm (range, 65-126 mm) on the left and right sides, respectively (2), the mean lengths between the lateral epicondyle and the points of the first twig branching from the radial nerve were 64.7 mm (range, 25-130 mm) and 68.9 mm (range, 40-120 mm) on the left and right sides, respectively (3) ,the mean lengths of the branches were 16.6 mm (range, 3-37 mm) and 15.4 mm (range, from 3-80 mm) on the left and right sides, respectively, and (4) the distribution pattern on the brachialis muscle could be divided into 4 types. These data will be useful for clinical practice and helpful for medical students to understand double innervation of muscles.