Nerve cell process transporting outgoing or efferent information away from the cell body (or soma) in the form of an action potential toward a specific target (other neurons; gland; muscle) with which it connects by means of a synapse. Sometimes referred to as a nerve fiber. An axon of a motoneuron can be up to a meter long in humans, the longest axon being that of the sciatic nerve running from the base of the spine to the large toe of each foot, and which may extend for a meter or more (compared to the giraffe, this length pales into insignificance, with its primary afferent covering a distance of almost 4 meters from toe to neck). Typically, like dendrites, axons are about a one micrometer in diameter. In vertebrates, axons of neurons are sheathed in myelin. The axons of some neurons branch to form axon collaterals along which duplications of the axon potential travel simultaneously to more than one other cell. The anatomist and physiologist Rudolph Albert von Kalliker (1817-1905) coined the word ‘axon’ in 1896, and it began to appear as a neuroanatomical term in the early 1900s.
See Action potential, Axon collateral, Axon pathway selection, Axon retraction (or pruning), Boutons, Cell theory, Dendrite, Dorsal root ganglia (DRG), Guidepost cells, Motoneuron, Motor unit, Myelin, Neurite, Neuron, Nodes of Ranvier, Oligodendrocytes, Plexus, Synapse