Are A fibers myelinated or unmyelinated?

Are A fibers myelinated or unmyelinated?

• A. Unmyelinated
• B. Myelinated
• C. Partially myelinated
• D. Not present in humans

Answer: (B)

Conduction speed in nerves hinges on myelination. Myelin insulation, with gaps called nodes of Ranvier, allows impulses to jump rapidly from node to node (saltatory conduction), vastly increasing velocity. A fibers are the fast, myelinated group of fibers, including A-alpha and A-beta (motor and fine touch) and A-delta (fast pain and temperature). Even though A-delta fibers are thinner, they’re still myelinated, which is why they conduct quickly. In contrast, C fibers are unmyelinated and carry slower, dull pain signals. Thus, A fibers are myelinated.

Conduction speed in nerves hinges on myelination. Myelin insulation, with gaps called nodes of Ranvier, allows impulses to jump rapidly from node to node (saltatory conduction), vastly increasing velocity. A fibers are the fast, myelinated group of fibers, including A-alpha and A-beta (motor and fine touch) and A-delta (fast pain and temperature). Even though A-delta fibers are thinner, they’re still myelinated, which is why they conduct quickly. In contrast, C fibers are unmyelinated and carry slower, dull pain signals. Thus, A fibers are myelinated.