An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see
spelling differences), is a long, slender projection of a nerve cell, or
neuron, in vertebrates, that typically conducts electrical impulses known as
action potentials away from the
nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain
sensory neurons (
pseudounipolar neurons), such as those for touch and warmth, the axons are called
afferent nerve fiber
Afferent nerve fibers are the axons (nerve fibers) carried by a sensory nerve that relay sensory information from sensory receptors to regions of the brain. Afferent projections ''arrive'' at a particular brain region. Efferent nerve fibers a ...
s and the electrical impulse travels along these from the
periphery to the cell body and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction can be the cause of many inherited and acquired
neurological disorder
A neurological disorder is any disorder of the nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord or other nerves can result in a range of symptoms. Examples of symptoms include paralysis, muscle weakn ...
s that affect both the
peripheral
A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...
and
central neurons. Nerve fibers are
classed into three types
group A nerve fibers,
group B nerve fiber
Group B nerve fibers are axons, which are moderately myelinated, which means less myelinated than group A nerve fibers, and more myelinated than group C nerve fibers. Their conduction velocity is 3 to 14 m/s. They are usually general visceral affe ...
s, and
group C nerve fibers. Groups A and B are
myelinated, and group C are unmyelinated. These groups include both sensory fibers and motor fibers. Another classification groups only the sensory fibers as Type I, Type II, Type III, and Type IV.
An a