What Is Motor Neuron Disease?
2. Upper Motor Neuron Disease
Upper MND occurs when there is damage to nerve cells within the brain or spinal cord that conduct the signals responsible for movement of the body by the muscles. The upper motor neurons send signals to the lower motor neurons which then relay those signals to the muscles to either relax or contract.
UMNs located in the cerebral cortex play a key role in voluntary movement. Some of the neural pathways that the UMNs travel through the central nervous system are corticobulbar tract, corticospinal tract, rubrospinal tract, colliculospinal tract, reticulospinal tract, and vestibulospinal tract. An UMN lesion or pyramidal insufficiency would occur within or above the anterior horn of the spinal cord. UMN disease includes spinal cord injury, multiple sclerosis, acquired brain injury, stroke, and more. It results in symptoms such as clonus, spasticity, and inability to perform fine movements.
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