Variations in the formation pattern of median nerve

ABSTRACT

Knowledge of variations of peripheral nerves is very important for the Anatomists, Anesthesiologists, and clinicians especially to the surgeons, during their daily practice. To provide additional information about variation in the formation of median nerve on both sides, and to avoid injury to the nerve during surgical procedures of axillary region by using this knowledge. Brachial plexuses from 40 upper limbs of 20 cadavers [18 Males and 2 Females] ranging from [45-70 years old] were dissected and examined at the department of Anatomy, Nishtar Medical College, Multan. Variations of brachial plexus of both upper limbs were observed. We have found median nerve on both sides to be formed by one, or two additional roots from lateral cord or one additional root from medial cord, joining with usual roots in 15% cases. In one limb lateral cord was not formed but additional roots got origin directly from the anterior divisions of the upper and middle trunks, which joined with each other and to the medial root of the medial cord to form the lateral and medial roots of the median nerve respectively. The additional lateral or medial roots crossed third part of axillary artery very closely. Bilateral variation was found in four limbs [10%] while unilateral variation was in 2 [5%] limbs. The main trunk of the median nerve was formed in front of brachial artery in 5[12.5%] limbs. Knowledge of variation is very important during surgical exploration of axilla and arm region and during nerve block. The close course of unusual additional root of the median nerve with axillary artery may lessen the blood supply of upper extremity by compressing the vessel