What is Sciatica? Sciatica is a persistent pain that is felt along the sciatic nerve; it runs from the lower back down to the feet. It controls the muscles to the legs and provides sensation to the thighs, legs and bottoms of the feet. Sciatica occurs most often in people between the ages thirty through fifty. It usually is caused by repetitive use type of conditions, such as sitting for long periods of time, or normal wear and tear. It is rarely caused by an acute injury.