Which fiber type transmits fast, sharp pain?

Which fiber type transmits fast, sharp pain?

• A. C fibers
• B. A-delta fibers
• C. A-beta fibers
• D. A-gamma fibers

Answer: (B)

Fast, sharp pain is carried by lightly myelinated A-delta fibers. Their myelin lets signals travel quickly, producing the initial, well-localized pain you notice right after a noxious stimulus. This is the “first pain” you feel. By contrast, dull, lingering pain comes from unmyelinated C fibers, which conduct more slowly. A-beta fibers are larger, myelinated fibers that convey non-painful touch and proprioception, not nociception. A-gamma fibers are motor pathways to muscle spindles and don’t transmit pain. So the fiber type that transmits fast, sharp pain is the A-delta fiber.

Fast, sharp pain is carried by lightly myelinated A-delta fibers. Their myelin lets signals travel quickly, producing the initial, well-localized pain you notice right after a noxious stimulus. This is the “first pain” you feel. By contrast, dull, lingering pain comes from unmyelinated C fibers, which conduct more slowly. A-beta fibers are larger, myelinated fibers that convey non-painful touch and proprioception, not nociception. A-gamma fibers are motor pathways to muscle spindles and don’t transmit pain. So the fiber type that transmits fast, sharp pain is the A-delta fiber.