Origin:  S1-S2 roots, sacral plexus, sciatic nerve, tibial nerve.

Recording Site:  Abductor Hallucis muscle (AH)

Reference Site:  Base of big toe

Ground:  Top of foot

Stimulation Sites:  Ankle and knee

Procedure:  The recording electrode is placed over the belly of the AH.  The reference electrode is placed over the proximal phalanx of the big toe.  Stimulation occurs at the hollow of the medial side of the ankle, between the medial malleolus and the Achilles tendon and at the back of the knee, directly under the knee cap in the fat pad located above the knee crease.  The distance between G1 and the distal stimulating site is 8-10 cm.