Which fiber type transmits fast, well-localized pain?

Which fiber type transmits fast, well-localized pain?

• A. C fibers
• B. D fibers
• C. A fibers
• D. B fibers

Answer: (C)

Fast, well-localized pain is carried by myelinated, relatively large-diameter fibers called A-delta fibers. Their myelin and size allow rapid conduction, so a sharp stimulus is felt immediately and can be pinpointed to its exact spot. In contrast, unmyelinated C fibers transmit slow, dull, diffuse pain that lags behind and is harder to localize. B fibers are associated with autonomic preganglionic signaling and aren’t the primary route for sensory pain. This distinction explains why the first, sharp pain you notice is linked to A-delta fibers.

Fast, well-localized pain is carried by myelinated, relatively large-diameter fibers called A-delta fibers. Their myelin and size allow rapid conduction, so a sharp stimulus is felt immediately and can be pinpointed to its exact spot. In contrast, unmyelinated C fibers transmit slow, dull, diffuse pain that lags behind and is harder to localize. B fibers are associated with autonomic preganglionic signaling and aren’t the primary route for sensory pain. This distinction explains why the first, sharp pain you notice is linked to A-delta fibers.