Which statement best describes 1A fibers?

Which statement best describes 1A fibers?

• A. They are the FASTEST conducting nerve fibers
• B. They are slowest conducting
• C. They are unmyelinated
• D. They do not participate in proprioception

Answer: (A)

Conduction velocity in peripheral nerves scales with axon diameter and myelination. 1A fibers are large-diameter, heavily myelinated A-alpha fibers that carry rapid sensory input from muscle spindles. That combination makes them among the fastest conducting fibers in the peripheral nervous system. They primarily transmit proprioceptive information to the spinal cord and are central to the monosynaptic stretch reflex. So this statement is the best description: they conduct impulses quickly. They are not slowest, they are not unmyelinated, and they do participate in proprioception.

Conduction velocity in peripheral nerves scales with axon diameter and myelination. 1A fibers are large-diameter, heavily myelinated A-alpha fibers that carry rapid sensory input from muscle spindles. That combination makes them among the fastest conducting fibers in the peripheral nervous system. They primarily transmit proprioceptive information to the spinal cord and are central to the monosynaptic stretch reflex. So this statement is the best description: they conduct impulses quickly. They are not slowest, they are not unmyelinated, and they do participate in proprioception.