A-delta fibers are:

A-delta fibers are:

• A. Unmyelinated fibers that carry slow dull pain
• B. Myelinated fibers that transmit sharp fast, well-localized pain
• C. Fibers that carry touch
• D. Fibers that carry proprioception

Answer: (B)

A-delta fibers are small-diameter, myelinated nerve fibers that conduct impulses quickly, producing the initial sharp, well-localized pain you feel right after a noxious stimulus. The myelination speeds conduction, so these fibers deliver a fast “first pain” that lets you localize the source and react quickly. In contrast, unmyelinated C fibers carry slow, dull, diffuse pain that lingers. Signals for touch mainly travel through larger, myelinated A-beta fibers, and proprioception through the largest myelinated A-alpha fibers. So the description “myelinated fibers that transmit sharp fast, well-localized pain” best captures what A-delta fibers do.

A-delta fibers are small-diameter, myelinated nerve fibers that conduct impulses quickly, producing the initial sharp, well-localized pain you feel right after a noxious stimulus. The myelination speeds conduction, so these fibers deliver a fast “first pain” that lets you localize the source and react quickly. In contrast, unmyelinated C fibers carry slow, dull, diffuse pain that lingers. Signals for touch mainly travel through larger, myelinated A-beta fibers, and proprioception through the largest myelinated A-alpha fibers. So the description “myelinated fibers that transmit sharp fast, well-localized pain” best captures what A-delta fibers do.