Lower limb Motor NCS

Nerve	Origin	Active	Reference	Ground	Stimulation	Lat. (Max)	Amp. (Min)	NCV (Min)	F Lat. (Max)
Femoral to Quadriceps	L2,3,4	Center of vastus medialis	Quadriceps tendon near the patella	Between active & reference electrode	Needle electrode is used. A- Superior to the inguinal ligament just lateral to the femoral artery. B- Inferior to the inguinal ligament and lateral to the femoral artery.	8.5 7.5	0.5
Peroneal to Ext Dig Brevis	L5,S1	On extensor digitorum brevis muscle on the dorsum of the foot.	5^th MCP	Between active & reference electrode	A- 8 cm proximal to the active electrode, slightly lateral to the tibialis anterior tendon B- Posterior and inferior to the fibular head.	6.5	1.2	40	60
Tibial to Abductor Hallucis	S1,S2	Medial foot, slightly anterior and inferior to the navicular tubercle (at the most superior point of the arch	1^st MCP	Between active & reference electrode	A- posterior to the medial malleolus B- Mid-popliteal fossa	6	4	40	60
Tibial to Flex Dig Min Brevis	S1,S2	Midpoint of inferolateral edge of 5^th metatarsal.	5^th MCP	Between active & reference electrode	Posterior to the medial malleolus	8	1.2
H reflex to Calf muscle	S1	On the back of leg, Midpoint between popliteal crease and posterior calcaneus.	Posterior calcaneus	Between active & reference electrode	Mid-popliteal crease with the anode distal	35

An accessory peroneal nerve is commonly present (20–25% incidence). The accessory peroneal nerve passes behind the lateral malleolus to innervate the extensor digitorum brevis. Its presence should be suspected if the amplitude to proximal stimulation is greater than on ankle stimulation. Its presence can be confirmed by stimulating behind the lateral malleolus. If a response is recorded from the extensor digitorum brevis, an accessory peroneal nerve is present