Variation in the formation of the median nerve involving a communicating branch from the musculocutaneous nerve

Background: The brachial plexus has a complex anatomical structure from its origin in the neck, through its course in the axillary region. It is formed by the union of the ventral rami of the spinal nerves from C5 to T1. Anomalies in the formation of the cords of brachial plexus and the communications between its branches are common. Case Report: Anomalies of the brachial plexus in terms of the formation of the median nerve were observed during routine dissection of the right upper limb of the cadaver of a 55-year-old male. The branches of the lateral and medial cords of the brachial plexus were dissected carefully and the variation from the usual pattern was noted. The lateral root of the median nerve arose from the lateral cord and bifurcated after 2 cm. The upper part united with the medial root of the median nerve and the lower part united with the median nerve approximately 0.5 cm past the aforementioned unification. There was also a communicating branch originating from the musculocutaneous nerve that arose 6 cm distal to the origin of the lateral root. This communicating branch coursed medially and united with the median nerve. Conclusions: It is important to be aware of these variations when planning surgery and regional anesthesia of the axilla or upper extremity. In addition, the presence of anatomic variations of the peripheral nervous system is often used to explain unexpected clinical signs and symptoms