Study of Median Nerve Variations and Its Clinical Implications at the Distal Part of Upper Limb: A Review

Introduction: Median Nerve (MN) originated from medial and lateral cords of Brachial Plexus and can be affected by anatomical variations, which may lead to several diagnostic and therapeutic mistakes. This paper aimed to study MN variations investigated by cadaveric studies. Methods: This study is based on research in electronic databases. The full text of all relevant papers has been studied to extend our data. Results: variation of MN distribution in the palm, variation of MN innervation patterns, communication between MN and (Ulnar Nerve) UN and their branches in the forearm, communication between MN and UN and their components in the palm, variation in the course of MN are main MN variation categories containing several subgroups. However, communication between the third common digital nerve of MN and the fourth common digital nerve of UN is the most common MN variation at the distal of upper limbs. Conclusion: decompression of MN entrapped in the carpal tunnel can be considered the essential clinical challenge resulting from MN variations, especially variations including the third common digital nerve.