In vertebrates, the term motor neuron (or motoneuron) classically applies to neurons located in the central nervous system (or CNS) that project their axons outside the CNS and directly or indirectly control muscles. Motor neuron's often associated with efferent neuron, primary neuron, or alpha motor neurons. Anatomy and physiology Branch of NS Position Neurotransmitter Somatic n/a Acetylcholine Parasympathetic Preganglionic Acetylcholine Parasympathetic Ganglionic Acetylcholine Sym… (More on Motoneuron)