<P> The sciatic nerve ( / saɪˈætɪk / ; also called ischiadic nerve , ischiatic nerve , `` butt nerve '' ) is a large nerve in humans and other animals . It begins in the lower back and runs through the buttock and down the lower limb . It is the longest and widest single nerve in the human body , going from the top of the leg to the foot on the posterior aspect . The sciatic nerve provides the connection to the nervous system for nearly the whole of the skin of the leg , the muscles of the back of the thigh , and those of the leg and foot . It is derived from spinal nerves L4 to S3 . It contains fibers from both the anterior and posterior divisions of the lumbosacral plexus . </P>
where does the sciatic nerve run in the foot
on the posterior aspect