Anatomie de la branche postérieure du nerf cutanée médial de l’avant bras — étude cadavérique

The posterior branch of the medial antebrachial cutaneous nerve (MACN) may be damaged during the cubital tunnel surgery. The purpose of this study was to identify the location of the posterior branch of the MACN. We performed an anatomical study on 20 limbs in 13 fresh cadavers. The nerve was dissected from 10 cm proximal to 10 cm distal to the medial epicondyle (ME). We measured the distance from the nerve to the medial epicondyle, and to the penetration of the ulnar nerve between the two heads of the flexor carpi ulnaris muscle. Measurements were performed on an elbow flexed at 45° and 90° as well as in pronation and supination. The posterior branch of the MACN exited the nerve and run anteriorly to the ME and then had an oblique direction toward the ulnar shaft. Average distances between the posterior branch of the MACN and the ME were 2.53 cm and 2.96 cm when the elbow was flexed at 45° and 90° respectively. Average distances between the posterior branch of the MACN and the crossing of the ulnar nerve with the flexor carpi ulnaris were 1.54 cm and 1.62 cm when the elbow was flexed at 45° and 90° respectively. The pronation and supination mobilizations did not significantly modify the measurements. Understanding the position of medial antebrachial cutaneous nerve branches during ulnar nerve release at the elbow may help to prevent iatrogenic injury to this cutaneous nerve. To prevent any nerve lesion, the incision and deep dissection should not be anterior to the medial epicondyle and be distal to the penetration of the ulnar nerve between both heads of the flexor carpi ulnaris nerve.