Vijayamma Kunnath Narayanan1, Ushavathy Padmanabhan2, Jude Jose Thomson3, Anjana Jayakumaran Nair4
The study of course and branching pattern of median nerve was done earlier by many researchers. The knowledge of median nerve in the hand got prime importance as it supplies motor and sensory branches to the thenar muscle and volar aspect of the hand. It passes through a restricted space under flexor retinaculum and is liable to get compressed. The nerve undergoes morphological changes under the retinaculum. It also shows variations in the course and distribution in the hand. This study is aimed at avoiding damage to the nerve and its main branches in hand surgeries like traumatic tendon surgeries, reconstructive hand surgeries and decompression procedures for carpal tunnel syndrome.
MATERIALS AND METHODS
Fifty cadaveric human hands were dissected and median nerve were traced after cutting the flexor retinaculum. Branches were identified and photographed and the findings tabulated.
The study of median nerve in fifty cadaveric hands show remarkable variation in the branching pattern. Median nerve shows flattening when it passes under flexor retinaculum. In 88% of hands, median nerve divides into medial and lateral branches distal to the flexor retinaculum, whereas 12% hands show early bifurcation proximal to flexor retinaculum. Thenar branches are given off from the lateral division and have an extraligamentous course in 80% of hands. Subligamentous course of thenar branch was seen in 12% of hands transligamentous course in 8%.Multiple accessory thenar branches were also observed arising from the base of proper digital branch to the thumb. Communicating branches were also observed with ulnar nerve seen in all cases at different sites. The first and second lumbrical muscles were supplied by median nerve, and in 10% hands, third lumbrical was also supplied by median nerve. Multiple thin vascular branches to superficial palmar arch were also observed.
This study throws light upon anatomical variations of median nerve while it passes under the flexor retinaculum, proximal to the retinaculum and distal to the retinaculum. Anticipation of such variations were helpful during hand surgeries to avoid iatrogenic damage of the nerve and its branches.
Median Nerve, Carpal Tunnel, Flexor Retinaculum, Thenar Branch, Carpal Tunnel Syndrome.