Nerves of the leg
The sciatic nerve, about 2 centimetres wide, is the body's largest nerve. It gathers the fourth lumbar to third sacral nerves, leaves the pelvis through the buttock and runs down the back of the thigh. Above the knee it splits into the tibial nerve for the calf and sole and the common fibular nerve for the front of the leg.
Nerves of the right leg from behind: the sciatic nerve leaves the pelvis below the piriformis and divides into the tibial and common peroneal, or fibular, nerves, Gray's Anatomy, 20th edition, 1918, figure 832Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray832.png)
The common fibular nerve winds round the neck of the fibula, where crossed legs or a tight plaster can press it and leave the foot dropping. The front of the thigh belongs to the femoral nerve. Sciatica, pain down the back of the leg, usually comes from a slipped disc pressing on the fifth lumbar or the first sacral root.
Sources
- Susan Standring (ed.), Gray's Anatomy, 42nd ed. (2020), section on the pelvic girdle and lower limb.
Prev: Nerves of the armNext: The eye