Variations of Median Nerve Formation in North Indian Population

Abstract

Introduction: The median nerve is usually formed by two roots contributed from the medial and lateral cords of the brachial plexus. Morphological variations of the median nerve can have clinical implications from the anesthetic and surgical points of view. In this cadaveric observation study, we report the variations of median nerve formation in the North Indian population.

Methods: We observed the formation of the median nerve in 40 human cadaveric upper limb specimens. The specimens belonged to 20 right and 20 left upper limbs. Variations in the formation of the median nerve were noted.

Results: Of the 40 dissected specimens, six (15%) had triple roots including a supernumerary root contributing to the medial nerve formation. The supernumerary root was a branch of the lateral cord in five cases, and it had an additional contribution from the medial cord in one case. The median nerve formation and continuation were located anterior or laterally in 39 specimens (97.5%) and medial in one (2.5%) in relation to the axillary artery.

Conclusion: We observed supernumerary roots of varying morphology contributing to the median nerve formation. These variations should be considered during the administration of regional anesthesia and during the management of brachial plexus injuries. Further large multi-region studies will help in a better understanding of these variations.

Keywords: anatomy; brachial plexus; dissection; median nerve; triple roots; upper limb.

Figure 1. A cadaveric specimen of left axilla with brachial plexus showing a thick tubular supernumerary root (SR, yellow arrowhead) originating from the lateral aspect of the lateral cord (LC) and blending distally with the median nerve (M) after its formation. The axillary artery (A), lateral root (LR), and medial root (MR) of the median nerve (M), musculocutaneous nerve (Mu), and ulnar nerve (U) can be seen in the adjacent region.

Figure 2. A cadaveric specimen of left axilla with brachial plexus showing a "Y" shaped supernumerary root (yellow arrowhead), arising from the lateral cord (LC) and the medial root (MR) of the median nerve (M). The axillary artery (A), lateral root (LR) of the median nerve, musculocutaneous nerve (Mu), and ulnar nerve (U) can be seen in the adjacent region.