Unique Transligamentous Variant of the Recurrent Motor Branch of the Median Nerve.

This case report presents a 72-year-old female with a unique anatomical variation of the median nerve recurrent motor branch that has not been described in the literature. During her open carpal tunnel release, the recurrent motor branch was found to divide from the median nerve within the carpal tunnel, pierce the proximal aspect of the transverse carpal ligament in a transligamentous fashion, and then immediately divide into one branch that pierced the thenar muscles and another branch that traveled superficial to the transverse carpal ligament before piercing the thenar muscles more distal. This variation in anatomy stresses the importance of thoughtful incision design and direct visualization of all structures during carpal tunnel release.