Sciatica is irritation of the sciatic nerve that passes down the back of each thigh.
The sciatic nerve arises from the lower spine on either side and travels deep in the pelvis to the lower buttocks. From there, it passes along the back of each upper leg and divides at the knee into branches that go to the feet.
Sciatica typically causes pain that shoots down the back of one thigh or buttock. Sciatica pain is often burning, tingling, or numbness on one side of the leg. Pain may also be present on one side of the buttocks that worsens when seated for a long time.