The sciatic nerve is the longest and widest nerve in your body. It runs along the hip joint and down your leg. Sciatica is characterized by pain that originates in the lower back or buttock that travels into one or both legs. Weakness and numbness in the leg or foot may also occur. Sciatic nerve pain varies in intensity (minimal, moderate, severe) and frequency (occasional, intermittent, frequent, or constant). Sciatica is caused by irritation of the root(s) of the lower lumbar or lumbosacral spine.