An unusual formation of sciatic nerve.

Sciatic nerve is the largest nerve and a branch of sacral plexus that controls hamstrings and all muscles of the lower limb below the knee. We are reporting a bilateral variant formation of the sciatic nerve found in a male human cadaver. The commencement of single sciatic nerve trunk formation was found to be in the lower gluteal region instead of the pelvic region. All the roots of the sciatic nerve, namely, the lumbosacral trunk (L4, L5), S1, S2, and S3 were observed to remain separate up to the lower part of the gluteal region. Incidence of this variation in general population needs to be investigated so as to create awareness among surgeons and anesthetists about the degree and extent of variation in sciatic nerve formation. Complete sciatic nerve blockages will fail even after multiple punctures and attempts if the sciatic nerve is present as separately sheathed bundles until the lower gluteal level.