Study of anatomical variations of the thenar recurrent branch of Median nerve.

Purpose: The Median nerve (MN) is one of the important nerves in Superior extremity and have a wide distribution up to wrist and palm. The course and branches of the MN in the wrist vary widely among the population. Awareness of anatomical variations of the median nerve at wrist is important in repair of traumatic injuries. It is essential to avoid iatrogenic nerve injury during treatments of it’s decompression surgery in Carpal tunnel release for Carpal tunnel syndrome. Due to significant differences in the reported cases of such variations, extensive knowledge on the anatomy of the MN is very helpful for the surgeons. Our aim was to find out the prevalence rates of anatomical variations of the MN in the carpal tunnel and wrist, along with the variations of the million dollar nerve of hand, the thenar recurrent branch of median nerve. Materials & Methods: 50 upper limbs of 25 well embalmed cadavers of both sexes above the age of 18 were dissected during routine UG dissections for 2 academic sessions 21-22 & 22-23 in West Bengal after taking institutional ethical clearance. All the variations of median nerve under the headings of, variation in branching pattern of median nerve in carpal tunnel,variation in origin course and termination of thenar recurrent nerve ,communication with ulnar nerve ,variations of common digital nerve was noted. Results: Thenar recurrent nerve is commonly presented as single nerve, in 96% cases and in 74% cases the nerve originated from the radial side of median nerve. Only in 2 out of 50 cases we noted accessory TRN was present. In 36 out of 50 cases course of TRN is extraligamentous variety ,which is the most common presentation, followed by transligamentous variety which was noted in 20% cases (10 out of 50) and the least common type was Subligamentous variety present in 8% cases. Conclusion: During release of flexor retinaculum for carpal tunnel syndrome or during other operative procedures involving the thenar muscles surgeons has to be more careful to protect thenar recurrent branch of median nerve as it is lying in intimate relation to flexor retinaculum and having varied origin & courses.