Accessory brachialis muscle: a case report

Variations of arm flexors are not uncommon with the exception of brachialis muscle. The role of brachialis is critical as it is the primary flexor of the elbow joint. Variations of brachialis are rare in literature. We present a case of an accessory-brachialis muscle (AcBr), found during routine cadaveric dissection. The AcBr originated from the lateral aspect of the brachialis muscle and lateral intermuscular septum. During its course towards the elbow, it crossed over the radial nerve and the distal tendon splits into two. The medial slip ran over the ulnar artery and merged with the deep fascia covering the pronator teres muscle, whereas lateral slip was inserted to the fascia covering the supinator. In the ipsilateral arm, an additional lateral cutaneous nerve of forearm (LCNF) was found coursing over the brachialis muscle medial to the LCNF. Clinical consideration of the present variations has been discussed. The present variation should be considered in the etiology of radial-tunnel syndrome (RTS).