- either of a pair of nerves, the largest in the body, that originate in the sacral plexus of the lower back and extend down the buttocks to the back of the knees, where they divide into other nerves: the sciatic nerve and its branches innervate large areas of the pelvis, leg, and foot.
- A nerve that arises from the sacral plexus and passes through the greater sciatic foramen to about the middle of the thigh where it divides into the common peroneal and tibial nerves.
- A thick nerve that arises in the lower part of the spine and passes through the pelvis on its way to the back of the leg. It carries sensory information from the leg to the central nervous system and controls the action of many muscles. The sciatic nerve is the largest nerve in the body.