The neurons and nerve fibres which conduct nerve impulses from the central nervous system (CNS) to the peripheral organs and tissues are called efferent neurons and efferent nerve fibres respectively. Some of the neurons and nerve fibres conduct nerve impulses to the muscles and glands to stimulate or inhibit their activities. Many of these nerve fibres cause movements of muscles. So, such neurons and nerve fibres are known as motor neurons and motor nerve fibres, respectively. All motor neurons are efferent neurons, because they conduct impulses from the CNS system to the peripheral tissues viz. muscles and glands.