Bilateral variations of musculocutaneous nerves with rare pattern in a Korean female cadaver

Bilateral variations in the formation and branching of brachial plexus are rare. Variations between median and musculocutaneous nerves were observed on both sides during the dissection of an 87-year-old Korean female cadaver, whose cause of death was cholangiocarcinoma. The variations found were bilateral, in which each musculocutaneous nerve did not pierce the coracobrachialis muscle. The musculocutaneous nerve was rudimentary in the right arm and all branches arose from the median nerve separately, which corresponds to previous classification type 0-2. In the case of the left arm, the musculocutaneous nerve originated from the lateral cord, but had connections between median and musculocutaneous nerves below the coracobrachialis muscle, which corresponds to previous classification type 1-B-2. To the best of our knowledge, the bilateral variations between median and musculocutaneous nerves in this case have different features from other previous reports. Awareness of the possible variations between median and musculocutaneous nerves is important to both anatomists and clinicians.