Long head of biceps brachii perforated by a duplicated musculocutaneous nerve

The musculocutaneous nerve (MCN) is characterized, in part, by its classic perforation of the coracobrachialis muscle. It has also been reported to occasionally perforate the short head of the biceps brachii and brachialis. However, comprehensive modern summaries of its anatomical variation do not include perforation of the long head of the biceps brachii as an MCN variant. We describe a rare case of a “duplicated” MCN that perforates the long head of the biceps brachii in a 92-year-old, Caucasian female cadaver. We provide the first description and photographic documentation of this variant and discuss its anatomical and clinical significance.