What is the Difference Between Upper and Lower Motor Neuron?

Upper and lower motor neurons are part of the somatic nervous system that controls voluntary muscular movements. They form a two-neuron circuit, with upper motor neurons originating in the cerebral cortex and traveling down to the brainstem or spinal cord, while lower motor neurons begin in the spinal cord and innervate muscles and glands throughout the body. The main differences between upper and lower motor neurons include:

• Origin: Upper motor neurons originate in the cerebral cortex, while lower motor neurons begin in the spinal cord.
• Function: Upper motor neurons transmit motor impulses from the brain to the synapses of the lower motor neurons, while lower motor neurons collect the transmitted motor impulses from the upper motor neurons and conduct them to the muscles or glands.
• Neurotransmitters: Upper motor neurons use glutamate, while lower motor neurons use acetylcholine as their neurotransmitters.
• Types: There are three broad types of lower motor neurons: somatic motor neurons, special visceral efferent (branchial) motor neurons, and general visceral motor neurons.

Understanding the differences between upper and lower motor neurons, as well as the pathway they take, is crucial for diagnosing and localizing neuronal injuries.

Comparative Table: Upper vs Lower Motor Neuron

Upper and lower motor neurons are essential components of the somatic nervous system, responsible for controlling voluntary muscular movements. Here are the key differences between them:

Upper motor neurons carry information down to activate interneurons and lower motor neurons. They are involved in the conscious control of muscle movement and the inhibition of muscle activity through the corticospinal tract. In contrast, lower motor neurons are responsible for directly connecting with muscles and transmitting impulses from the spinal cord to muscles. Damage to lower motor neurons can lead to muscle atrophy, decreased muscle tone, and variable patterns of weakness.