Dictionary > Motor neuron

Motor neuron

noun, plural: motor neurons
A type of neuron connected to a muscle fiber and originates from the central nervous system
The motor neuron is a type of neuron in which the cell body is in the spinal cord of the central nervous system. Its axon projects from the spinal cord and connected to a muscle fiber. The motor neuron is an efferent neuron since it transmits impulses away from the central nervous system towards the periphery.
The motor neurons may be divided into upper motor neurons and lower motor neurons. The upper motor neurons are those that originate from the motor region of the cerebral cortex or from the brain stem. The lower motor neurons are those found in the anterior grey column, anterior nerve roots, cranial nerve nuclei of the brainstem, and cranial nerves (i.e. with motor function).1 The upper motor neurons relay the motor information down to the lower motor neurons through synapses. The lower motor neurons are further classified as: (1) alpha motor neurons, (2) beta motor neurons, and (3) gamma motor neurons. The lower motor neurons effect muscle movement when neurotransmitters are released at the neuromuscular junction and activate muscle fibers.

  • motor neurone


  • motoneuron
  • See also:


    1 Fletcher, T.F. “Clinical Neuroanatomy Guide”. Retrieved from ://vanat.cvm.umn.edu/mLocLesGui/clinAnat.html.

    You will also like...


    Bryophytes (nonvascular plants) are a plant group characterized by lacking vascular tissues. They include the mosses, th..

    An artist's depiction of the origin of amphibians
    Amphibians & Early Reptiles

    Obtaining air outside an aquatic environment required species to acquire suitable adaptations, and this was the case of ..

    Plant biology
    Plant Biology

    Plantlife can be studied at a variety of levels, from the molecular, genetic and biochemical level through organelles, c..

    Plant Water Regulation
    Plant Water Regulation

    Plants need to regulate water in order to stay upright and structurally stable. Find out the different evolutionary adap..

    Birth Control and Contraception
    Birth Control and Contraception

    Different pregnancy and birth control and contraception strategies are described. Read this tutorial to learn each of th..

    Darwin's Finches - Natural Selection
    Darwin and Natural Selection

    This tutorial investigates the genetic diversity in more detail. It also delineates how certain alleles are favored over..