Origin:  C7-C8 roots, middle and lower trunk and posterior cord of the brachial plexus, radial nerve.

Recording Site:  Extensor Digitorum Communis muscle (EDC)

Reference Site:  Above the wrist

Ground:  Medial forearm

Stimulation Sites:  Elbow and arm (below and above spiral groove)

Procedure:  The recording electrode is placed over the belly of the EDC.  The reference electrode is placed on the forearm above the wrist.  Stimulation occurs at the elbow, at the joint between the brachioradialis muscle and the biceps tendon, and at the spiral groove (high) in the upper arm.  The patient’s arm should be placed with the elbow flexed and the palm down.