Origin:  C8 root, lower trunk and lateral cord of the brachial plexus.

Recording Site:  Ring finger

Reference Site:  Ring finger

Ground:  Palm or top of hand

Stimulation Site:  Wrist

Procedure:  The recording electrode is placed on the proximal phalange of the fourth finger.  The reference electrode is placed on the middle phalange of the ring finger.  A distance of 13 cm is measured from G1 to the distal wrist crease over the ulnar nerve.  The nerve is stimulated at the wrist, adjacent to the flexor carpi ulnaris tendon.  The nerve can also be stimulated at the elbow, above the ulnar groove.

The same distance should be used when using the ulnar ring finger study as a comparison study to the median ring finger study.  This study can also be performed orthodromically.