Variations in the level of exit and division of sciatic nerve

Introduction: The sciatic nerve divides normally into the tibial and common peroneal nerves at the apex of the popliteal fossa. But the division can occur at any level from the sacral plexus to the inferior part of the popliteal fossa. When it divides within the pelvis, the two branches may leave the pelvis through different routes and may be compressed by other structures, causing non-discogenic sciatica. The aim of this study was to determine the level of the exit and of the division of the sciatic nerve. Methods: Sixty inferior extremities were examined in 30 adult male cadavers in the Department of Anatomy, JNIMS, Imphal. Results: Sciatic nerve divided into tibial and common peroneal nerves at the apex of popliteal fossa in 58.3% of cases, below the apex in 13.3% and above the apex in 28.4%. In 5 cases (8.4%), it divided within the pelvis where common peroneal nerve passed through and tibial nerve below the piriformis in 3 cases, both the nerves passed below in 1 case and in another case, common peroneal nerve passed between and tibial nerve passed above the heads of the piriformis. Discussion: In sciatic neuropathy, the extent of neurological deficits depends on the level of the sciatic nerve division. Division at a higher level can result in the involvement of only one out of the two branches. On the other hand, it may result in failure of popliteal block anaesthesia. (C) 2016 Anatomical Society of India. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved.