The purpose of this prospective study is to examine the anatomical variations of the branches of the medial antebrachial cutaneous nerve in Koreans encountered during cubital tunnel surgery.

Ninety two patients with cubital tunnel syndrome were treated with a standard approach from December 2008 to July 2012. The position of the branches of medial antebrachial cutaneous nerve was evaluated based on the medial humeral epicondyle with the elbows fully extended.

At least one medial antebrachial cutaneous nerve branch was found during the surgeries in all patients. The average number of crossing medial antebrachial cutaneous nerve branches per patient was 1.6. Thirty-eight percent of the cases showed that the medial cutaneous nerve branches cross proximal to the medial humeral epicondyle within 1 cm. Eighty-two percent showed that the medial antebrachial cutaneous nerve branches cross distal to the medial humeral epicondyle within 1.9 cm.

When using standard approach during cubital tunnel surgery, more than one medial forearm cutaneous nerve is found. Therefore, understanding the general position of medial antebrachial cutaneous nerve branches helps avoid iatrogenic damage to this nerve during cubital tunnel surgery.