A specific pattern of leg pain that follows the course of the sciatic nerves. It is usually caused by injury to one or more of the sciatic root nerves within the lower spinal canal. The contributing nerves, the last two lumbar and first two sacral, exit sequentially through openings on each side of the spine. The individual nerves then enter common protective sheaths to become the sciatic nerves. Each one leaves the pelvis and runs down the back of the leg to the foot. Along the way branches supply the skin, particularly in the lower leg, and some of the muscles that move the hip and bend the knee. The sciatic nerves control all the muscles that enable walking on the heels and toes.