Difference Upper and Lower Motor Neurons

Table of Contents


The sensory and motor pathways in the spinal cord help in the conduction of sensory and motor impulses, respectively. Sensory pathways carry impulses from the sensory receptors to the brain and spinal cord, whereas the motor pathways carry impulses from the brain and spinal cord to the effector’s muscles. The upper motor neuron and lower motor neuron are the two basic sets of neurons present in the somatic motor pathways. Here in this article, let us look at the various difference between upper and lower neurons.

Upper Vs Lower Motor Neuron

Upper Motor Neuron Lower Motor Neuron
It is entirely located in the central nervous system. It is either located in the spinal cord grey matter or within the cranial nerve nuclei in the brain stem.
Transmits motor impulses from the brain to the synapses of the lower motor neuron. Collects the transmitted motor impulses from the upper motor neuron and conducts them to the muscles in the body.
Cell bodies of upper motor neurons are bigger than lower motor neuron cell bodies. Cell bodies are comparatively smaller than the upper motor neurons.
Classified on the basis of the pathways they are participating in. Classified on the basis of the type of muscle fibre they innervate.
They form synapses with the lower motor neurons. They form synapses with the muscles in the body.
Upper motor neuron lesions produce spastic hyperreflexia and muscle weakness. Lower motor neuron lesions result in muscular atrophy, flaccid muscle weakness, fasciculation and hyporeflexia.

What are the Upper Motor Neurons?

The term Upper Motor Neuron was first introduced by William Gowers. Upper Motor Neurons are found in the cerebral cortex and the brainstem, which carry information down to activate the Interneurons and the Lower Motor Neurons.

What are the Lower Motor Neurons?

The Lower Motor Neurons begin in the Spinal Cord and end in the Skeletal Muscles. In this condition, these lower motor neurons are lost, which leads to weakness, muscle twitching, and muscle atrophy.

Both the upper and the lower motor neurons make up the somatic nervous system that controls voluntary muscular movements. From the differences, we can conclude that the main difference between the upper and the lower motor neurons is their origin and function.

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Also, Read

Nervous System Co-ordination Central Nervous System
Peripheral Nervous System Reflex Action
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