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

Recording Site:  Extensor Indicis Proprius muscle (EIP)

Reference Site:  Dorsal and medial wrist, near the styloid process of the ulna

Ground:  Posterior forearm

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

Procedure:  The recording electrode (G1, black) is placed over the belly of the EIP.  The reference electrode (G2, red) is placed on the dorsomedial wrist, near the ulnar styloid process.  Distal stimulation occurs at the forearm.  Proximal stimulation is at the elbow, between the brachioradialis muscle and the biceps tendon; and distal and proximal to the spiral groove in the arm proper.  The patient’s upper extremity should be placed with the elbow flexed and the palm down.