Coracobrachialis muscle morphology and coexisted neural variants. A cadaveric case series

Abstract

Purpose The current cadaveric case series evaluates and reports the morphology of the coracobrachialis muscle (CB), and the related musculocutaneous nerve (MCN) origin, course, and branching pattern, as well as associated adjacent muscular and neural variants. Materials and Methods Twenty-seven formalin embalmed cadaveric arms (24 paired from 12 cadavers and 3 unpaired), were dissected to identify the CB possible variants with emphasis on the MCN course and coexisted neural variants. Results Four morphological types of the CB were found: a two-headed in 62.96% (17/27 arms), a three-headed in 22.2% (6/27), a one-headed in 11.1% (3/27) and a four-headed in 3.7% (1 arm). A CB variant morphology was identified in 37.04% (10/27). A three-headed biceps brachii coexisted in 23.53% (4/17). Two different MCN courses were recorded: a course between CB superficial and deep heads (in cases of two or more CB heads) (100%, 24/24), and a medial course in case of one-headed CB (100%, 3/3). The interconnection of the lateral cord with the median nerve median root was identified in 18.52%, the MCN with the median nerve in 7.41% and of the radial with the ulnar nerve in 3.71%. Duplication of the median nerve lateral root was identified in 11.1%. Conclusions The knowledge of the morphology of the muscles of the anterior arm compartment, especially CB variant morphology and the related MCN variable course, is of paramount importance for surgeons. Careful dissection and knowledge of relatively common variants play a significant role in reducing iatrogenic injury.