Introduction: Median nerve (MN), one of terminal branches of brachial plexus, is commonly associated with several variations. This research aimed to review the literature related to the variations of MN from axillary region to cubital fossa.
Methods: We searched Google Scholar, Science Direct, Springer, and PubMed electronic databases to compile reports related to the variation of MN published from 1990 to 2015.
Results: Variations in the origin, communication with other nerves, region of formation, pattern of innervations, and story of MN are common. MN in cases with abnormal origination forms by 3 roots (91.1%), 4 roots (7.5%), and 1 root (1.2%). The most common variation of MN has been detected in its communication with other nerves. These types of variations include 1 communication between MN and musculocutaneous nerve (MCN) (80.2%), 2 communications between MN and MCN (6%), fusion of MN with MCN (6.3%), and communication with other nerves (7.3%). The unusual regions of MN formation include arm (60.5%), medial to axillary artery (34.6%), and posterior to axillary artery (4.8%). Anterior compartment of arm and lateral side of forearm are either completely (45.8%) or partially (43.7%) the abnormal pattern of MN innervation. Other variations in MN innervation form 10.4% of cases. Entrapment (57.5%) and non-entrapment (42.4%) forms are 2 types of MN story variations.
Conclusion: The knowledge of these variations is crucial for medical experts such as anesthesiologists, radiologist, surgeons, neurophysiologists, and electromyographists to accomplish their duties properly.