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 ?
In summary, adult polyglucosan body disease should be suspected in patients with a late-onset progressive disorder of the peripheral and central nervous system, especially when upper motor neuron signs, dementia, or bladder impairment is present.
4) "as part of the upper motor neuron syndrome"--this is the site of the injury to the motor system that leads to spasticity, (i.
For instance, the rate of ejaculation in men with complete upper motor neuron injuries can be as low as 4 percent (Bors and Comarr, 1960).
Primary Lateral Sclerosis (PLS) is a group of ultra-rare neurological disorders caused primarily by degeneration of the upper motor neurons in the brain and spinal cord, which results in increasing spasticity and weakness of voluntary muscles.
Upper versus lower motor neuron weakness Upper motor neuron weakness Lower motor neuron weakness Muscle weakness Muscle weakness Less atrophy of muscles (may be Atrophy of muscles disuse) Increased tone, spasticity Low muscle tone Increased deep tendon reflexes Diminished or absent deep tendon reflexes No fasciculation Fasciculation Hemiplegic, quadriplegic or Specific distribution of paraplegic distribution of weakness, i.
ALS is a fatal progressive 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.

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