Sciatica is the sensation of pain, tingling, or numbness in the buttocks and/or legs produced by an irritation of the sciatic nerve. Multiple nerve roots extend from the spinal cord between the vertebrae and join to form the sciatic nerve, which branches as it descends into the buttocks and down each leg to the ankles and feet. The primary causes of sciatica are herniated, bulging, or degenerated discs, which induce pressure on the spinal nerve roots.
Other causes include small, bony growths on the spine (bone spurs) or compression of the nerves through injury. In rare cases, the sciatic nerve may be irritated by conditions such as piriformis syndrome, tumors, or pregnancy.