The sciatic nerve is the major nerve of the lower limb and the largest peripheral nerve in the body. It arises from the sacral plexus with some additional contribution from the lumbar plexus (L4,5 S1,2,3). It passes out of the pelvis through the greater sciatic foramen and lies behind the hip joint where dislocations may injure it.
Above the knee it divides into two main branches (the common peroneal nerve
and the tibial nerve). The sciatic nerve and its two terminal branches innervate
the hamstring muscles of the thigh and all the muscles below the knee. In
addition, there is a cutaneous distribution to the foot and the lateral side
of the leg.