Introduction: Median Nerve (MN) originated from medial and lateral cords of Brachial Plexus can be affected by anatomical variations which may lead to several diagnostic and therapeutic mistakes. This paper aim is to study about MN variations investigated by cadaveric studies.
Materials and Methods: This study is based on research in electronic databases. Full text of all relevant papers has been studied to extent our data.                                                  
Result: 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 branches 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 as the most important clinical challenge resulted from MN variations especially variation including third common digital nerve.