Sciatica is a pain that shoots along the sciatic nerve, radiating through the buttocks and down the back of the leg and as far as the foot. The two sciatic nerves (one on each side of the lower body) are the longest in the human nervous system, running all the way from the lower back through the thighs and calves to the feet.
Sciatica is caused by different types of pressure on the sciatic nerve in the lower back or buttocks. It can also be the result of damage to the nerve roots that feed into the sciatic nerve. Sciatica is usually felt only on one side of the body. The pain can occur along the entire length of the sciatic nerve.