A Rare Bilateral Variation in the Formation of Median Nerve

The median nerve is formed by fusion of lateral (C5-C7) and medial (C8,T1) cords from the brachial plexus. Bilateral variations in the formation of median nerve are very rare. One of such variations was observed during the dissection of the upper limb of approximately a 30-35-year-old man cadaver, according to Grants method. The median nerve was formed by the union of three roots on both sides. There was an additional lateral root on both sides, while the first lateral root was short. On the left side, the second lateral root was short and united with the main trunk of median nerve proximal to the insertion of coracobrachialis muscle to humerus bone. However, on the right side, the second lateral root was long and pierced the coracobrachialis muscle accompanying with musculocutaneous nerve. Then it joined to the main trunk of the median nerve distal to the insertion of coracobrachialis muscle to humerus bone. Since, topographical situation of brachial plexus, median nerve and its communicating branches with musculocutaneous nerve have a very important role in evaluation of their injuries and neurological signs, awareness of the normal and variant patterns of the brachial plexus branches might be of great importance for medical specialists particularly anatomists and surgeons.