Any of the bundles of fibers made up of neurons that carry sensory and motor information throughout the body in the form of electrical impulses. Afferent nerves carry information to the central nervous system, and efferent nerves carry information from the central nervous system to the muscles, organs, and glands. Efferent nerves include the nerves of the peripheral nervous system, which control voluntary motor activity and of the autonomic nervous system, which controls involuntary motor activity.