Which type of nerve fiber is responsible for dull, aching pain?

Which type of nerve fiber is responsible for dull, aching pain?

• A. A-alpha
• B. A-gamma
• C. A-delta
• D. C

Answer: (D)

Dull, aching pain is carried by unmyelinated C fibers. These fibers conduct nerve signals slowly, around 0.5–2 m/s, and are typically polymodal nociceptors activated by chemical, mechanical, and thermal stimuli after tissue injury. Because they transmit more slowly, the resulting pain is diffuse, long-lasting, and burning or throbbing in quality. By comparison, fast, sharp pain is carried by lightly myelinated A-delta fibers, which transmit quickly to produce the immediate, well-localized sensation. Other fiber types like A-alpha and A-gamma are involved in motor function and muscle spindle activity, not primary nociception. So the dull, aching component of pain points to the C fibers.

Dull, aching pain is carried by unmyelinated C fibers. These fibers conduct nerve signals slowly, around 0.5–2 m/s, and are typically polymodal nociceptors activated by chemical, mechanical, and thermal stimuli after tissue injury. Because they transmit more slowly, the resulting pain is diffuse, long-lasting, and burning or throbbing in quality. By comparison, fast, sharp pain is carried by lightly myelinated A-delta fibers, which transmit quickly to produce the immediate, well-localized sensation. Other fiber types like A-alpha and A-gamma are involved in motor function and muscle spindle activity, not primary nociception. So the dull, aching component of pain points to the C fibers.