Medial Accessory Belly of the Brachialis Muscle in the Korean Population: A Case Report

Abstract

The brachialis muscle (BR) is a powerful flexor located in the anterior part of the brachial region. It is supplied with blood from the brachial artery and is innervated by the musculocutaneous nerve. BR variation is rare, but tends to divide the muscle into two or more, or to attach the accessory belly to other muscles around it. Here, we reported an accessory belly of BR (AcBr) in Korean cadaver. Under the bicep brachii muscle, AcBr was originated from the medial side of the BR. It continued 151.8 mm more and inserted between the tendon of the biceps brachii muscle and the biceps aponeurosis. The length from the origin of the BR to the origin of AcBr was 30.1 mm. It crossed superficially the brachial artery and median nerve. This rare variation of BR cannot rule out the possibility of neuropathy, and may help improve our understanding of neuralgia. Here, we introduced rare variation of BR and discussed its clinical and embryological significance.