Study of anatomical variations of the sciatic nerve and it’s importance to clinicians and anesthetist

Sciatic nerve is the widest, thickest nerve of the body, arising from lumbosacral plexus. It is near about 2 cm wide. Sciatic nerve is formed by anterior and posterior divisions of spinal nerves L4, L5, S1, S2, S3. It has two components common peroneal and tibial components. It is formed in pelvic region, it emerges out from pelvis into gluteal region through greater sciatic foramena by passing below piriformis as a single nerve trunk. Then it courses in back of thigh and at the apex of popliteal fossa where it terminates into tibial nerve and common peroneal nerve. There are numerous variations in it’s course. The main variation is in relation to it’s exit from pelvis and division of sciatic nerve into terminal branches. These variations are of clinical importance and these may lead to compression of nerve called as sciatica. These variations are also important for anesthetist as this nerve commonly used for peripheral nerve block i.e. sciatic nerve block and variation in division and course may lead to failed block or sparing of block. The aims and objectives of present study are to find out variation in exit pattern of sciatic nerve and level of bifurcation of sciatic nerve and it’s clinical correlation of above variations. In our study, we found that single trunk of sciatic nerve coming out in gluteal region below piriformis 75%, piercing piriformis 3.33% cases. Two divisions of sciatic nerve coming out in gluteal region common peroneal and tibial nerve passing below piriformis 11.67%, common peroneal piercing piriformis and tibial nerve passing below piriformis 6.67%, common peroneal passing above pyrifomis and tibial nerve passing below piriformis 3.33% cases. Terminal divisions of sciatic nerve in pelvis 21.67%, in upper part of thigh 5% and at apex of popliteal fossa 73.33%. These variations are of clinical importance and these may lead to compression of nerve called as sciatica. These variations are also important for anesthetist as this nerve commonly used for peripheral nerve block i.e. sciatic nerve block and variation in division and course may lead to failed block or sparing of block.