upper motor neuron

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up·per mo·tor neu·ron

clinical term indicating those neurons of the motor cortex that contribute to the formation of the corticospinal and corticonuclear (corticobulbar) tracts, as distinguished from the lower motor neurons innervating the skeletal muscles. Although not motor neurons in the strict sense, these cortical neurons became colloquially classified as motor neurons because their activation produces movement and their destruction causes moderate to severe disorders of movement.
See also: motor neuron, motor cortex.

upper motor neuron

A motor neuron (actually an interneuron) found completely within the central nervous system that synapses with or regulates the actions of lower motor neurons in the spinal cord and cranial nerves. Lesions of these neurons produce spastic paralysis in the muscles they innervate. Synonym: upper motoneuron
See also: neuron


cranial; oral; rostral.

upper airway
upper respiratory tract. See also airway.
upper burner syndrome
in acupuncture terminology a chronic lung condition caused by an attack by a pathogen.
upper motor neuron
motor nerve pathway originating in the brain and terminating at a peripheral motor neuron. Damage to this pathway releases the peripheral nerve from central control. See also upper motor neuron.
upper respiratory tract (URT)
comprises the nasal cavities, pharynx and larynx. Some anatomists also include the upper segments of the bronchial tree. Inflammation of the URT is common to all species. It is usually caused by infection, most commonly viral, producing a syndrome of frequent, dry cough, serous or mucoid nasal discharge and pain on manual compression of the laynx, pharynx and trachea. It is a common precursor to more serious disease involving the lower respirtory tract.
upper respiratory tract virus disease
see Table 8.2.
References in periodicals archive ?
Spasticity: A condition characterized by increased muscle tone due to damage in the upper motor neuron.
ALS is a fatal degenerative disease resulting in relentlessly progressive weakness and wasting of voluntary muscles, affecting a combination of the upper motor neurons in the motor cortex and the lower motor neurons in the brainstem and spinal cord.
Denervation activity in the EMG of patients with upper motor neuron lesions: Time course, local distribution and pathogenetic aspects.
Some upper motor neuron bladder muscles spontaneously contract.
F response latencies and durations in upper motor neuron syndromes.
Conclusions: Increased repeater F waves reflect increased excitability of motor neuron pool and indicate upper motor neuron dysfunction in ALS.
At the cellular level, ALS is characterized by the combined degeneration of both upper motor neurons (UMN, or corticospinal motor neurons) whose cell bodies are located in the cerebral cortex, and that extend axons to the medulla and spinal cord, and lower motor neurons (LMN, or spinal motor neurons) whose cell bodies are located in the medulla and spinal cord, and that connect to the skeletal muscles.
This will be valuable in the study of upper motor neurons, which are increasingly seen as an important subset of affected neurons in ALS.
sup][4] We propose that the upper motor neurons might be damaged later than peripheral nerves and that the progression is slow.
Specifically, in the previous symposium, Levi-Montalcini was troubled by the implications of Brunelli's work because upper motor neurons (nerves within the spinal cord) and lower motor neurons (nerves that leave the cord to connect to muscles) use different neurotransmitters (chemicals released from a neuron ending that interacts with an adjacent neuron or muscle cell).
Upper motor neurons direct the lower motor neurons to produce movements such as walking or chewing.
Since the upper motor neurons (spinal-cord nerves controlling movement) and lower motor neurons (nerves that leave the cord to connect to muscles) use different neurotransmitters (chemicals released from a neuron ending that interact with an adjacent neuron or muscle cell), gene research should provide more definitive information on this function-restoring procedure's mechanism of action.

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