What Is Sciatica? Sciatica is pain felt along the sciatic nerve. This is the longest nerve in the human body as it runs from the lower back down to the foot. Sciatica results from pinching or irritation of the nerve which can often come and go without needing to be addressed. When the pain begins to interfere with daily activities, a diagnosis is necessary to begin treatment. Diagnosing sciatica is usually quite simple, but identifying the source of the pain can be more diffi