SCIATIC NERVE AND ITS VARIATIONS: AN ANATOMICAL STUDY

Background and aims: The Sciatic nerve is the widest nerve of the body, consists of two components namely tibial and common peroneal components, derived from the lumbosacral plexus from the ventral rami of L4 to S3 spinal nerves. The Sciatic nerve usually enters the gluteal region under the piriformis muscle. The purpose of this study is to identify the variations in the course and branching pattern of the sciatic nerve and its relation to the piriformis muscle which may lead to various clinical manifestations like non-discogenic sciatica. Materials and methods: 50 gluteal regions and posterior compartment of thigh from 25 formalin fixed adult cadavers are used for this study, of which one is a female cadaver. Gluteal regions and the posterior aspect of thigh on both sides are dissected to expose the sciatic nerve. Variations in the sciatic nerve and their relationship to piriformis muscle are observed. Results: 41 gluteal regions and posterior compartments of thigh (82%) showed normal anatomy of sciatic nerve and also piriformis muscle. 9 regions (18%) showed variations in the sciatic nerve, of which 5 regions (10%) showed variation of sciatic nerve in relation to piriformis muscle. Other details are explained further in the article. Conclusion: A proper knowledge about the variations of sciatic nerve, its relation to piriformis muscle is must for medical professionals during posterior hip surgeries, sciatic nerve decompression, total hip replacement, sciatic nerve injury during deep intramuscular gluteal injections, failed sciatic nerve block during anaesthetic procedures etc.