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Upper motor neuron
Neurons (nerve cells) in the motor cortex (an area of the brain located in middle, top part of the brain) that help make up the following nerve tracts (paths): corticospinal tracts (paths from the brain to the spine) and corticobulbar tracts (paths from the top part of brain to the lower part of the brain called the brain stem, which looks like a bulb). The brainstem is an area in the lower part of the brain that connects it with the spinal cord. This area of the brain controls many functions crucial for life to continue. Unlike upper motor neurons, lower motor neurons send messages to the skeletal muscles.

The term "upper motor neuron" is actually misleading because upper motor neurons are not really motor neurons. They are called motor neurons because when they are stimulated they produce movement and when they are destroyed, severe movement disorders result. As an example, in upper motor neuron paralysis, paralysis (loss of movement and/or sensation) is caused by damage to the cell bodies and/or axons (parts of nerve cells that send messages) of the upper motor neurons. A cell is the smallest, most basic unit of life, that is capable of existing by itself. Although some people use the terms upper motor neuron, pyramidal tract, and corticospinal tract as if they were the same, the three terms are not interchangeable.

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