sciatic nerve n.
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.
largest and thickest nerve of the human body that is the principal continuation of all the roots of the sacral plexus. It emerges from the spinal cord in the lumbar portion of the spine and runs down through the buttocks and the back of the thigh; above the back of the knee it divides into the tibial and the common peroneal nerve, both of which serve the lower leg and foot