An unreported pattern of musculocutaneous and median nerve communication with multiple variations of biceps brachii: a case report

Abstract

An unreported pattern of communication between musculocutaneous (Mcn) and median nerve (Mn) with multiple variations of biceps brachii (Bb) was observed during the dissection of a male cadaver. The first branch of the Mcn ended in coracobrachialis (Cb). The second was the main Mcn piercing the Cb and giving its motor branches to the muscles of the anterior compartment of the arm. It then continued as the lateral cutaneous nerve of the forearm. The largest third branch also pierced the Cb distal to the main Mcn and communicated with the Mn which was classically formed by relevant roots of the medial and lateral cords. Additionally, a third head of Bb was observed bilaterally. Slips from the pectoralis major were inserted on the tendon of the third head on both sides. The origin of the third head was the greater tubercle to the left and the joint capsule to the right. These extremely rare patterns of both variations which were seen concomitantly in the same subject do not exist in the literature. Lack of awareness of such variations with different patterns of communications between Mcn and Mn might complicate surgical repair of the nerves. Knowing different patterns of Bb variations also have clinical importance as they also may cause compression of neurovascular structures or confuse a surgeon during surgical procedures.