The Sciatic nerve
(L4-5, S1-3) is the largest nerve in the body. It passes through the
the infrapiriformal area and between the ischiocrural muscles to the popliteal
fossa. At the superior boundary of the popliteal fossa the sciatic nerve physically
divides into the two main branches, the common fibular and tibial nerves. The
common fibular nerve innervates the fibular muscles and the extensors of the
foot, as well as their associated cutaneous skin. The tibial nerve innervates
the posterior leg musculature and plantar intrinsic muscles of the foot, as
well as the cutaneous skin of the posterior calf, heel, middle part of the sole
of the foot, and toes.
Spasm of the piriformis muscle may entrap the sciatic nerve (piriformis syndrome).