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Ulnar Motor Nerve - Recording the First Dorsal Interosseous (FDI)

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:  First Dorsal Interosseous (FDI or 1st DI)

Reference Site:  Base of thumb

Ground:  Palm or Top of Hand

Stimulation Site:  Wrist, below elbow and above elbow.

Procedure:  The recording electrode is placed over the belly of the FDI.  The reference electrode is placed over the proximal phalanx of the thumb.  Stimulation occurs at the wrist, adjacent to the flexor carpi ulnaris tendon.  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 stimulation sites to accurately compute the conduction velocity.  The patients arm should be in a flexed position at the elbow when performing proximal nerve stimulations.