Formation of the Median Nerve and its Relation to the Axillary Artery: A Cadaveric Study from A Central Indian Population

Abstract

Background: The median nerve's mode of formation — the number and origin of its contributing roots and its relation to the axillary artery — shows well-documented but population-variable anatomical variation, with direct relevance to axillary brachial plexus block and to plexus exploration after trauma. Combined, statistically compared cadaveric data addressing this variability remain scarce for Central India.

Methods: Thirty embalmed cadavers (60 upper limbs) were bilaterally dissected at a single institution. The number and origin of the roots forming the median nerve, its relation to the axillary artery, and the length and diameter of any supernumerary root were recorded using a standardised proforma. Findings were compared between right and left sides and between sexes using the chi-square test.

Results: The classical two-root pattern was present in 66.7% of limbs (40/60), with a supernumerary root in the remaining 33.3% (20/60) — three roots in 30.0% and four roots in 3.3%. Where present, the supernumerary root arose most often from the musculocutaneous nerve (50.0%), followed by the lateral cord (40.0%) and posterior cord (10.0%), with a mean length of 20.31 ± 5.30 mm and diameter of 1.36 ± 0.31 mm. The nerve's formation lay lateral to the axillary artery in 68.3% of limbs, anterior in 21.7%, and medial in 10.0%. No statistically significant difference in supernumerary root frequency was found between sides (30.0% vs. 36.7%; p = 0.784) or sexes (31.8% vs. 37.5%; p = 0.918).

Conclusion: One in three limbs in this Central Indian cadaveric sample showed a supernumerary root to the median nerve, most often from the musculocutaneous nerve, with no significant side or sex difference — findings with direct relevance to regional anaesthesia and brachial plexus surgery in this population.