Transcutaneous electrical stimulation (TEN) is primarily used to depolarize sensory nerves to modulate pain. Which nerves are targeted?

• A. Motor nerves
• B. Sensory nerves
• C. Autonomic nerves
• D. Mixed nerves

Answer: (B)

Transcutaneous electrical stimulation aims to influence pain by activating the sensory, or afferent, nerves in the skin. By depolarizing these large-diameter sensory fibers (like A-beta fibers), it engages the gate-control mechanism: the input from these fibers can inhibit or dampen the transmission of pain signals carried by other nerves at the spinal cord level, leading to analgesia without producing muscle contractions. Activating motor nerves would cause muscle twitching; autonomic nerves would shift autonomic functions; and mixed nerves would involve multiple fiber types with less selective effects. Therefore, the targeted nerves are the sensory nerves.