An unusual case of asymmetrical formation and distribution of median nerve

During routine dissection of upper extremity of a 70-year-old male cadaver, variation was found in the formation and distribution of median nerve on both sides. On right side, median nerve received contribution from lateral cord twice, once in the axilla as lateral root of median nerve-1 and again in the arm as lateral root of median nerve-2. Lateral root of median nerve-1 contributed most of its fibers to ulnar nerve. On left side, median nerve had its two roots as usual, lateral root of median nerve and medial root of median nerve. However the lateral root of median nerve crossed the axillary artery anteriorly and formed the median nerve medial to the axillary artery. There was total absence of musculocutaneous nerve on the left side. The muscles of the anterior aspect of the arm, received nerve supply from the median nerve.