Thumb Abduction

Electrode Placement
Application Instruction by Dr. Lucinda Baker

Electrode placement for isolated thumb extension. The very small negative electrode is placed about two thirds of the way down the forearm over the extensor surface. The positive electrode is over the extensor tendons.

Thumb Abduction

Video Instruction
Audio Transcript:

Electrode placement for isolated thumb extension. The very small negative electrode is placed about two thirds of the way down the forearm over the extensor surface. The positive electrode is over the extensor tendons.

Stimulation results in isolated thumb extension, which would be graded three out of five in a muscle grade.

Thumb Abduction

Muscle Anatomy

Muscles involved in thumb abduction:

Abductor Pollicis Brevis
Origin: Transverse carpal ligament, the scaphoid and trapezium
Insertion: Radial base of proximal 1st phalanx and the radial sesamoid

Abductor Pollicis Longus
Origin: Posterior side of ulna, radius and interosseous membrane
Insertion: Base of first metacarpal

Thumb Abduction

Nerve Anatomy

Nerves involved in thumb opposition:

Abductor Pollicis Brevis
Nerve innervation: Median nerve
Nerve root: C8-T1

Abductor Pollicis Longus
Nerve innervation: Innervated by the posterior interosseous nerve, which is a continuation of the deep branch of the radial nerve after it passes through the supinator muscle
Nerve root: C7-C8