Anatomy of the medial antebrachial cutaneous nerve and its significance in ulnar nerve surgery: An anatomical study

Background: During cubital tunnel surgery, the medial antebrachial cutaneous nerve (MACN) may be injured, causing painful scars, neuromas, hypaesthesia or hyperalgesia. As the literature on the anatomy of crossing branches in this area is contradictory, this study aimed to re-examine the anatomy of the MACN in this region.

Methods: Forty upper limbs were dissected. We looked specifically from 5 cm proximal to 6 cm distal to the medial epicondyle (ME) and documented the number of crossing branches and the distances between the crossing points and the ME; we also measured the length of each limb.

Results: The most common location for crossing branches was 2 cm distal to the ME. Twenty-seven branches (∼23%) were found proximal to or at the level of the ME, and 91 branches (∼77%) were distal to it. The average distance between the proximal crossing points and the ME was 1.7 cm, the mean number of crossing branches was 0.7 and at least one crossing branch per limb was found in 16/40 cases. For the distal crossing points, the average distance to the ME was 2.9 cm, the mean number of crossing branches was 2.3 and at least one crossing branch per limb was found in all cases. There was no correlation between the limb lengths and the number of crossing branches.

Conclusion: Because the incidence of posterior branches of the MACN crossing the course of the ulnar nerve is 100%, it is important to take the anatomy of the MACN into consideration when undertaking ulnar nerve surgery.