Variation of median nerve and lateral antebrachial cutaneous nerve: One case report

Abstract

During our routine dissection, we observed two variations in an old male cadaver. Firstly, the lateral root and the medial root that form the left median nerve descend in a longer distance than usual and converge into the median nerve trunk, and there is a communicating branch between the two roots. Secondly, the lateral antebrachial cutaneous nerve and the superficial branch of the radial nerve collectively dominate the area of the thumb-index web. This type of variations of the nerves is rare to see and should be considered to interpret atypical clinical presentations and avoid unusual injury during surgery. Case reportTwo anatomic variations are spotted during a dissection of peripheral nerves and vessels, which was conducted on an old male cadaver. The first anatomic variation is spotted at the left median nerve, where the lateral root and the medial root that form the left median nerve descend in a longer distance than usual and converge into the median nerve trunk. A communicating branch is also observed between the two roots. The second variation appears at the distribution of the lateral antebrachial cutaneous nerve, where the lateral antebrachial cutaneous nerve and the superficial branch of the radial nerve collectively dominate the area of the thumb-index web. The discovery of both variations is rare and reports on both at the same time have not been found. This report illustrates the two variations in details and explains the consequences they lead to. It also provides first hand anatomic data and great referential value for the future clinical work.According to the first variation in this case, the two unusually long roots of the left median nerve, the lateral root and the medial root, are emitted from the fasciculus medialis plexus brachialis and the fasciculus lateralis plexus brachialis. According to the measurements during the dissection, the lengths of the two roots are 10.76 cm and 12.05 cm, with diameters 2.44 mm and 2.87 mm respectively. As a result, the two axillary arteries descend and converge into the median nerve trunk in front of the brachial artery. The transverse diameter of the median nerve trunk is 3.66 mm after confluence. It goes down along the meidal bicipital groove with accompany of the brachial artery. In addition, a communicating branch is discovered between the lateral root and the medial root. The communicating branch starts from the medial root and terminates at a distance of 4.52 cm from the starting point of the lateral root. The length of the communicative branch is 4.28 cm, with a transverse diameter of 1.12 mm.There is another variation of distribution of the lateral antebrachial cutaneous nerve in this case. The left musculocutaneous nerve passes through the deep fascia from the lateral biceps tendon and transits to the lateral antebrachial cutaneous nerve. The ateral antebrachial cutaneous nerve has a diameter of 2.20 mm and is distributed under the lateral skin of the forearm. After going down 23.48 cm in distance, the end of the lateral antebrachial cuta...