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Ulnar Sensory Nerve - Recording the little finger (antidromic)

Last updated on Wednesday, April 29 2009 by blondarb

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

Recording Site:  Little finger

Reference Site:  Little finger

Ground:  Palm or top of hand

Stimulation Site:  Wrist
Procedure:  The recording electrode is placed on the proximal phalange of the little finger.  The reference electrode is placed on the middle phalange of the little finger.  A distance of 11 cm is measured from G1 to the distal wrist crease over the ulnar nerve.  The nerve is stimulated at the wrist, adjacent the flexor carpi ulnaris tendon.  The nerve can also be stimulated at the elbow, above the ulnar groove.

This study can also be performed orthodromically.  A bar electrode should be placed over the wrist site, with the recording electrode distal.  The finger electrodes are connected to the stimulator with the “G1” electrode acting as the cathode and the “G2” acting as the anode.

Useful for studying: Ulnar nerve lesions.  Lower trunk and medial cord brachial plexus lesions. Cervical radiculopathies.

Normal values *:

     Amp: >10 uV    

     Distal Latency: <3.1  mSec

     Conduction Velocity: >50 m/s 

     Temperature >32.0 C