For stimulation targeting a muscle, where should electrodes be placed?

For stimulation targeting a muscle, where should electrodes be placed?

• A. Muscle Belly or Motor Point
• B. Nerve Trunk
• C. Tendon Insertion
• D. Over Bone

Answer: (A)

To evoke a clean, efficient contraction, place the active electrodes over the muscle belly or at the motor point. The muscle belly contains many motor end plates and fibers, so stimulating there produces a broad, coordinated contraction with less current and better control. The motor point is where the nerve enters the muscle and where depolarization threshold is lowest, so a small amount of current reliably triggers the muscle. Other locations are less effective: placing over a nerve trunk tends to recruit several muscles and reduce precision; over a tendon insertion can be inefficient and may irritate the tendon; placing over bone is a poor conductor and yields weak or no contraction.

To evoke a clean, efficient contraction, place the active electrodes over the muscle belly or at the motor point. The muscle belly contains many motor end plates and fibers, so stimulating there produces a broad, coordinated contraction with less current and better control. The motor point is where the nerve enters the muscle and where depolarization threshold is lowest, so a small amount of current reliably triggers the muscle.

Other locations are less effective: placing over a nerve trunk tends to recruit several muscles and reduce precision; over a tendon insertion can be inefficient and may irritate the tendon; placing over bone is a poor conductor and yields weak or no contraction.