Radial Motor Nerve - Recording the Extenor Digitorum Communis (EDC)

Last updated on Tuesday, October 6 2009 by blondarb

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

Recording Site: Extensor Digitorum Communis muscle (EDC)

Reference Site: Above the wrist

Ground: Medial forearm

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

Procedure: The recording electrode is placed over the belly of the EDC. The reference electrode is placed on the forearm above the wrist. Stimulation occurs at the elbow, at the joint between the brachioradialis muscle and the biceps tendon, and at the spiral groove (high) in the upper arm. The patient’s arm should be placed with the elbow flexed and the palm down.

Related images:

Radial Motor Nerve - Recording the Extenor Digitorum Communis (EDC)
This cartoon shows the technique for studying the Radial Motor Nerve - Recording the Extenor Digitorum Communis (EDC).

Radial Motor NCS, Recording the Extenor Digitorum Communis (EDC), stimulating proximal to Spiral Groove
This photograph illustrates a radial motor nerve conduction study, recording from the Extenor Digitorum Communis (EDC) muscle. The stimulation site shown is on the posterior arm, proximal to the spiral groove.

Radial Motor NCS, Placement of electrodes on EDC
This photograph illustrates the placement of the recording electroded on the Extenor Digitorum Communis (EDC) muscle for a radial nerve motor study.

Radial Motor NCS, Recording the Extenor Digitorum Communis (EDC), stimulating at elbow
This photograph illustrates a radial motor nerve conduction study, recording from the Extenor Digitorum Communis (EDC) muscle. The distal stimulation site is at the elbow, between the brachioradialis muscle and the biceps tendon.

Radial Motor NCS, Recording the Extenor Digitorum Communis (EDC), stimulating distal to Spiral Groove
Another view of the radial motor nerve conduction study, stimulating distal to the spiral groove.

Radial Motor NCS, Recording the Extenor Digitorum Communis (EDC), stimulating distal to Spiral Groove
This photograph illustrates a radial motor nerve conduction study, recording from the Extenor Digitorum Communis (EDC) muscle. The stimulation site shown is on the posterior arm, proximal to the elbow, distal to the spiral groove.