The fourth and fifth lumbar nerve roots and the first two sacral nerve roots join
in the lumbosacral plexus to form the peroneal and tibial nerves that leave the pelvis
in an ensheathed single trunk as the sciatic nerve, the largest nerve in the body.
Disturbances anywhere along the course of the sciatic nerve can give rise to sciatica,
but the most common areas are at the sites of disk rupture and osteoarthritic
change