A motor neuron (or motoneuron) is a nerve cell (neuron) whose cell body is located in the spinal cord and whose fiber (axon) projects outside the spinal cord to directly or indirectly control effector organs, mainly muscles and glands.ypes of motor neurons are alpha motor neurons, beta motor neurons, and gamma motor neurons. There are upper motor neurons and lower motor neurons, with the cell type described above being a lower motor neuron.