| preganglionic motor neuron | See: motor neuron. (05 Mar 2000) |
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| autonomic motor neuron | See: motor neuron. (05 Mar 2000) |
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| ganglionic motor neuron | See: motor neuron. (05 Mar 2000) |
| visceral motor neuron | See: motor neuron. (05 Mar 2000) |
| motor neuron | Synonym for motoneuron. (18 Nov 1997) |
| motor neuron disease | <disease> Degenerative disease of unknown cause that affects predominantly motor neurons of spinal cord, cranial nerve nuclei and motor cortex. There is speculation that deficiency in ciliary neurotrophic factor may be involved. (18 Nov 1997) |
| postganglionic motor neuron | See: motor neuron. (05 Mar 2000) |
| somatic motor neuron | See: motor neuron. (05 Mar 2000) |
| upper motor neuron | Clinical term indicating those neuron's of the motor cortex that contribute to the formation of the pyramidal or corticospinal and corticobulbar tracts, as distinguished from the lower motor neuron's innervating the skeletal muscles. Although not motor neuron's in the strict sense, these cortical neuron's became colloquially classified as motor neuron's because their stimulation produces movement and their destruction causes severe disorders of movement. See: motor neuron, motor cortex. (05 Mar 2000) |
| upper motor neuron lesion | Injury to cerebral descending (corticonuclear) fibres above the brainstem or spinal motor nerve nucleus. Synonym: upper motor neuron lesion. (05 Mar 2000) |
| lower motor neuron | Clinical term used to indicate the final motor neuron's that innervate the skeletal muscles; distinguished from upper motor neuron's of the motor cortex that contribute to the pyramidal or corticospinal tract. See: motor neuron. (05 Mar 2000) |
| lower motor neuron dysarthria | Dysarthria caused by dysfunction of the motor nuclei and the lower pons or medulla, or other neural connections, central and peripheral to the muscles of articulation. (05 Mar 2000) |
| lower motor neuron lesion | Injury to motor cells in the brainstem or spinal cord, or of the axons derived from them. (05 Mar 2000) |
| autonomic fibres, preganglionic | Nerve fibres which project from the central nervous system to autonomic ganglia. In the sympathetic division most preganglionic fibres originate with neurons in the intermediolateral column of the spinal cord, exit via ventral roots from upper thoracic through lower lumbar segments, and project to the paravertebral ganglia; there they either terminate in synapses or continue through the splanchnic nerves to the prevertebral ganglia. In the parasympathetic division the fibres originate in neurons of the brainstem and sacral spinal cord. In both divisions the principal transmitter is acetylcholine but peptide cotransmitters may also be released. (12 Dec 1998) |
| preganglionic | Situated proximal to or preceding a ganglion; referring specifically to the preganglionic motor neurons of the autonomic nervous system (located in the spinal cord and brainstem) and the preganglionic, myelinated nerve fibres by which they are connected to the autonomic ganglia. (05 Mar 2000) |
| preganglionic fibres | A fibre whose cell body is located in an autonomic nucleus in the spinal cord or brain stem and whose axon terminates in an autonomic (motor) ganglion; found in nerves conveying sympathetic or parasympathetic fibres. (05 Mar 2000) |