<unk> s are any neurons that originate in motor region of the cerebral cortex and/or the brain stem and carry motor information down to the final common pathway, that is, any motor neurons that are not directly responsible for stimulating the target muscle. The main effector neurons for voluntary movement lie within layer V of the primary motor cortex and are called Betz cells. The cell bodies of these neurons are some of the largest in the brain, approaching nearly 100μm in diameter.
These neurons connect the brain to the appropriate level in the spinal cord, from which point nerve signals continue to the muscles by means of the lower motor neurons. The neurotransmitter glutamate transmits the nerve impulses from<unk>  to lower motor neurons where it is detected by glutamatergic receptors.
Upper motor neuron
Lower motor neuron
Spindle neuron
Interneuron
Postganglionic fibers
Dendritic spine
Free nerve ending
Cranial nerve nucleus