Level of division of sciatic nerve in fetuses

Objective: The sciatic nerve is the largest branch of the sacral plexus (L 4 -S 3 ) that is formed within the pelvis before its entry into the greater sciatic foramen. It leaves the pelvic cavity by passing through the greater sciatic foramen below the piriformis and descends along the back of the thigh, and usually divides into the common peroneal nerve and the tibial nerve just proximal to the knee. The present study aimed to study the level of division of the sciatic nerve. Materials and Methods: This study was carried out in 25 fetuses of 27-40 weeks of gestation obtained from the Department of Obstetrics and Gynecology, Regional Institute of Medical Sciences (RIMS), Imphal. The lower limbs of 25 fetuses were dissected and the sciatic nerve traced up to the level of the popliteal fossa. Results: In the present study, the lowest incidence of sciatic nerve division was found in the gluteal region (2%). In 12% of the fetuses the sciatic nerve was found to divide in the pelvic cavity before it entered into the gluteal region. The highest incidence of sciatic nerve division was found in the popliteal fossa (86%). Conclusion: Various possible variations of the sciatic nerve should be kept in mind during a surgical procedure or at the time of giving anesthesia to avoid any unwanted events. The high level of division of the sciatic nerve into the common peroneal nerve and the tibial nerve results in the involvement of only one out of the two divisions from sciatic neuropathy.