The sciatic nerve
Sciatic nerve · nervus ischiadicus
The widest and longest nerve in your body, running from your lower back down the back of each leg.
What it does
The sciatic nerve forms from roots in the lower back and sacrum, leaves the pelvis below the piriformis and runs down the back of the thigh. Above the knee it divides into the tibial and common fibular nerves, which supply almost all the muscles and skin below the knee.
Surprising fact
At its widest the sciatic nerve is about as thick as your thumb, making it the largest nerve in the body.
Why it matters
"Sciatica", pain shooting down the back of the leg, usually comes from a slipped disc irritating one of the nerve's roots in the lower back rather than the nerve itself.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.