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Ulnar Motor Nerve - Recording the Abductor Digiti Minimi (ADM)

Last updated on Monday, April 27 2009 by blondarb

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Origin:  C8-T1 roots, lower trunk and medial cord of the brachial plexus, ulnar nerve

Recording Site:  Abductor Digiti Minimi muscle (ADM)

Reference Site:  Base of little finger

Ground:  Palm or top of hand

Stimulation Sites:  Wrist, below elbow and above elbow.

Procedure:  The recording electrode is placed over the belly of the ADM.  The reference electrode is placed at the proximal phalanx of the little finger.  Stimulation occurs at the wrist, adjacent to the flexor carpi ulnaris tendon and at the elbow, at the ulnar groove.  The distance between G1 and the distal stimulating site at the wrist is 4-6 cm.  Additional stimulation sites include below the elbow, above the elbow, axilla and Erb’s Point.  There should be at the minimum 10 cm between the above elbow and below elbow stimulations sites to accurately compute the conduction velocity.  The patient’s arm should be in a flexed position at the elbow when performing proximal nerve stimulations.