Sciatica is a common condition that causes discomfort along the path of the sciatic nerve, which runs from your lower back through your hips, buttocks and down each leg. This pain may come with numbness, tingling or muscle weakness. It usually happens when the nerves that form the sciatic nerve become irritated or experience pressure, often from a herniated disc, spinal stenosis or another spine-related issue.
The sciatic nerve is the longest and thickest nerve in your body—about 2 centimeters wide, roughly the size of a penny. Despite being called a single nerve, it's actually made up of a group of nerves that branch from five nerve roots in your lower spine.
You have two sciatic nerves, one on each side. Each one travels through your hip and buttock, down the back of your leg and ends just below your knee. From there, it branches into smaller nerves that reach your lower leg, foot and toes.