Sciatic nerve
The sciatic nerve is the largest nerve in the body. It is actually composed of two nerves, the tibial and common peroneal nerves, which are located within a common connective tissue sheath. The sciatic nerve emerges from the sacral plexus and contains fibres from spinal nerves L4, L5, S1, S2 and S3. The sciatic nerve enters the gluteal region by passing through the greater sciatic foramen. It then courses deep to the gluteus maximus to enter the posterior compartment of the thigh. Around the distal one third of the posterior thigh, the sciatic nerve loses its common sheath and divides into the tibial and common peroneal nerves. The exact location where this occurs is highly variable and the neural sheath may be lost anywhere in the gluteal or thigh region.