Motor neuron

Motor neurons (also known as 'motoneurons' or 'efferent neurons' ) convey impulses from the central nervous system to muscles, glands, or other effector tissues. The term motor neurons classically applies to neurons with their cell body (perikarya) located in the grey matter of the brainstem or spinal cord and their efferent axons exiting from the CNS through the ventral root of a spinal nerve or corresponding part of a cranial nerve and directly or indirectly reaching their effectors. Motor neurons are multipolar.

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The motor neuron impulse reach their effectors directly or indirectly.
For skeletal muscle the axons from motor neurons run undisrupted to the muscle fibres forming a direct, one neuron pathway.
For smooth muscle, cardiac muscle and glands the axons from motor neurons synapse first on motor ganglia in the peripheral nervous system (PNS). From the ganglia axons are send to th effector cells, forming an indirect, two neuron pathway.

Motor unit

A single motor neuron may synapse with one or more muscle fibers. The motor neuron and all of the muscle fibers to which it connects forms a motor unit.

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