Peripheral C nerve fiber (C fiber)

Peripheral C nerve fibers are a class of unmyelinated nerve fibers found in both the peripheral and central nervous systems, characterized by small diameter (0.2–1.5 µm), slow conduction velocity (<2 m/s), and grouping into Remak bundles surrounded by non-myelinating Schwann cells. They comprise both sensory (afferent, from dorsal root ganglia) and autonomic (efferent, postganglionic sympathetic and parasympathetic) varieties. Sensory C fibers mediate the transmission of slow, burning pain, heat, and itch via nociceptive, thermoreceptive, and pruriceptive modalities, while autonomic C fibers regulate blood vessel tone, sweat gland activity, and piloerection. They release neurotransmitters including substance P, CGRP, and glutamate, playing a central role in pain processing and neurogenic inflammation. Dysfunction of C fibers contributes to neuropathic pain syndromes and small-fiber neuropathy.

Other names

C-fiberC fiber neuronGroup C nerve fiberunmyelinated peripheral nerve fiber

Capsaicin: activates the transient receptor potential vanilloid 1 (TRPV1) present on C-fiber terminals, causing depolarization, Ca²⁺ influx, initial excitation then desensitization, and depletion of neuropeptides Local anesthetics: block voltage-gated sodium channels, inhibiting action potential propagation in C-fibers Neuromodulatory drugs: inhibit synaptic transmission of pain from C-fibers by various mechanisms