Sciatica is the name given to any sort of pain caused by irritation or compression of the sciatic nerve. The sciatic nerve is the longest nerve in your body. It runs from the back of your pelvis, through your buttocks, and all the way down both legs, ending at your feet. The pain of sciatica is usually felt in the buttocks and legs. Most people find it goes away naturally within a few weeks, although some cases can last for a year or more.