Musculocutaneous and median nerve connections within, proximal and distal to the coracobrachialis muscle

Abstract

During dissection of the brachial plexus variations have frequently been observed in the formation and further ramification of the cords to form the musculocutaneous and median nerves (MCN and MN). The present study was undertaken to localise the connections (the communication pattern) of the MN and the MCN with respect to the point of entrance of the MCN to the coracobrachialis muscle. A total of 129 formalin-fixed cadavers were dissected for this purpose. For simplicity we classified the communication patterns as Types I, II, III and IV. In 82 (63.5%) of 129 cadavers 119 communications were found to be present. We were able to identify 4 different patterns of communication. Type I (54 communications, 45%): the communications were proximal to the point of entry of the MCN into the coracobrachialis, Type II (42 communications, 35%): the communications were distal to the point of entry of the MCN into the coracobrachialis, Type III (11 communications, 9%): the MCN did not pierce the coracobrachialis and Type IV (9 communications, 8%): the communications were proximal to the point of entry of the MCN into the coracobrachialis and additional communication took place distally. Precise knowledge of variations in MCN and MN communications may prove valuable in traumatology of the shoulder joint, as well as in plastic and reconstructive repair operations.