Which fiber type transmits slow, diffuse pain?

Which fiber type transmits slow, diffuse pain?

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

Answer: (C)

Pain signal speed and quality depend on the fiber type that carries the impulse. A-delta fibers are myelinated and larger, so they conduct quickly and convey the initial sharp, well-localized pain. In contrast, C fibers are unmyelinated and small, which makes their conduction slow. This slow transmission produces the dull, aching, diffuse pain that is poorly localized and lasts longer. C fibers are also polymodal, responding to thermal, chemical, and mechanical stimuli, and their signals recruit brain regions involved in the emotional aspect of pain, reinforcing the lingering, diffuse sensation. Therefore, the fiber type responsible for slow, diffuse pain is C fibers.

Pain signal speed and quality depend on the fiber type that carries the impulse. A-delta fibers are myelinated and larger, so they conduct quickly and convey the initial sharp, well-localized pain. In contrast, C fibers are unmyelinated and small, which makes their conduction slow. This slow transmission produces the dull, aching, diffuse pain that is poorly localized and lasts longer. C fibers are also polymodal, responding to thermal, chemical, and mechanical stimuli, and their signals recruit brain regions involved in the emotional aspect of pain, reinforcing the lingering, diffuse sensation. Therefore, the fiber type responsible for slow, diffuse pain is C fibers.