Bilateral variations of median nerve formation and endpoint variation of brachiales veins

Abstract

According to the descriptions in the classical books, brachial plexus is formed by the ventral rami of the cervical nerves (C5, C6, C7, and C8) and the first thoracic nerve (T1). The reported incidence of the brachial plexus variations, which can even differ between the upper extremities of the same person, is 13% and it is most commonly encountered between the median and musculocutaneous nerves. During a routine practice on the brachial plexus of a 65-year old male cadaver, we observed that the musculocutaneous nerve pierced the coracobrachialis muscle after giving the communicating branch in both extremities. According to the recommendation of Buch-Hansen, we decided that the communicating branch was originating from the lateral cord on the right side and from the musculocutaneous nerve on the left side. We detected a second variation after the deepening of the dissection. The medial brachial vein was terminating into the basilic vein after passing through two roots of the median nerve bilaterally. The presented anatomical variations have certain benefits regarding clinical practice. The presence of these and similar neural and vascular variations is important in respect of the possible nerve injuries, which may be caused by a piercing or cutting trauma in the upper extremity