A case report on accessory brachialis muscle

Supernumerary heads or slips of brachialis (anticus) muscle is one among the most striking variations, described and encountered in the dissection routine. Very few studies are quoted in the list of its anomalies. We present a unique occurrence of an accessory brachialis muscle (acBr) that formed a fibro-muscular tunnel after blending with the medial intermuscular septum in the lower part of the arm. This tunnel contained the median nerve, the brachial artery and few additional twigs that innervated the neighboring muscles. Because of its intimate topographical relation with the neurovascular bundle, there is no doubt about its role, in the etiogenesis of various compression syndromes. Also, the brachial flexors received innervation from the median nerve, due to the absence of the musculo-cutaneous nerve. We discuss in this report the possible embryogenesis and the clinical application of this variation that can aid the physicians in their approach and required treatment.