Afferent Nerve Fiber

also centripetal, or sensory, fiber, the nerve cell outgrowth, or axon, that together with its membrane transmits excitation from the external and internal receptors to the central nervous system—specifically, to the spinal cord or the various sections of the brain. The nerve cells are located either in the receptor organ itself or in special sensory ganglia that are close to the central nervous system.

The afferent nerve fibers that constitute the afferent nerves are subdivided into groups corresponding to the particular sensory systems—for example, the visual, auditory, or olfactory system. While some of the afferent nerves consist of fibers from different receptors (for example, cutaneous and muscular), most nerves consist of fibers of a single sensory type. Nerves that are exclusively afferent are rare; the most common, or mixed, type of nerve also contains efferent nerve fibers that lead to the effector organs.