motor neuron (redirected from Motor development)

neuron /neu·ron/ (noor´on) nerve cell; any of the conducting cells of the nervous system, consisting of a cell body, containing the nucleus and its surrounding cytoplasm, and the axon and dendrites. neuro´nal

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afferent neuron  one that conducts a nervous impulse from a receptor to a center.

efferent neuron  one that conducts a nervous impulse from a center to an organ of response.

Golgi neurons 

1. (type I): pyramidal cells with long axons, which leave the gray matter of the central nervous system, traverse the white matter, and terminate in the periphery.

2. (type II): stellate neurons with short axons that are particularly numerous in the cerebral and cerebellar cortices and in the retina.

motor neuron  motoneuron.

multisensory neuron  a neuron in the cerebral cortex or subcortical regions that can receive input from more than one sensory modality.

postganglionic neurons  neurons whose cell bodies lie in the autonomic ganglia and whose purpose is to relay impulses beyond the ganglia.

preganglionic neurons  neurons whose cell bodies lie in the central nervous system and whose efferent fibers terminate in the autonomic ganglia.

sensory neuron  any neuron having a sensory function; an afferent neuron conveying sensory impulses. The first in an afferent pathway is the primary sensory n. and the second is the secondary sensory n.

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motor neuron

n.

A neuron that conveys impulses from the central nervous system to a muscle, gland, or other effector tissue.

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Motor neuron

Nerve cells within the central nervous system that carry nerve impulses controlling muscle movement.

Mentioned in: Amyotrophic Lateral Sclerosis, Muscle Spasms and Cramps

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motor neuron,

one of various efferent nerve cells that transmit nerve impulses from the brain or from the spinal cord to muscular or glandular tissue. According to location, some kinds of motor neurons are the peripheral motor neurons and the upper motor neurons. Also called motoneuron. Compare sensory nerve. See also nervous system.

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motor,

n pertaining to a muscle, nerve, or center that produces or affects movement.

motor neuron,

n one of the various efferent nerve cells that transmit nerve impulses from the brain or from the spinal cord to muscular or glandular tissue.

motor neuron disease,

n a progressive disease that tends to affect middle-age men with degeneration of anterior horn cells, motor cranial nerve nuclei, and pyramidal tracts (e.g., amyotrophic lateral sclerosis).

motor output,

n the activity that results from the integrative phenomena associated with brain activity. It is expressed in function as muscle contraction of the smooth and striated muscle and as secretion of the exocrine and endocrine glands and, in effect, represents the total behavioral activity. Whereas sensory phenomena have many avenues that feed into the brain, motor activity is expressed in terms of the simple, direct state of muscle contraction and glandular secretion. Thus muscle activity is expressed in terms of locomotion, hand-learned skills, speaking, mastication, and all forms of activity that involve motion.

motor pathway,

n all reflex actions of muscle are achieved by the passage of nerve impulses through the final common pathway–the muscle fibers. The lower motor neuron (the motor route of the cranial nerve) is the final pathway for the structures that are innervated by the cranial nerves. Impulses traverse these nerves to their respective muscles from every level of the spinal cord, hindbrain, midbrain, and cerebral cortex. The cranial motor neurons collate these multiple stimuli and transmit sequences of stimuli to the motor end-plate, which in the normal muscle effects a smooth, continuous, controlled contraction.

motor skill,

n the ability to make the purposeful movements that are necessary to complete or master a prescribed task.

motor unit,

n the entity consisting of the lower motor neuron, motor end-plate, and muscle fibers supplied by the end-plate. The final motor activity resulting from a sequence of stimulations to the lower motor neuron is considered a function of the motor unit. The proportion of nerve fibers to the muscle fibers in motor units is designated as the innervation ratio. They may have ratios ranging from 1:4 to 1:150. The closer the ratio approximates unity, the greater the finesse of specificity of the muscular action. The eye muscles have the highest ratio of striated muscles, and the tongue, facial, masticatory, and pharyngeal muscles succeed in that order.

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motor neuron

a neuron having a motor function; an efferent neuron conveying motor impulses.

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motor neuron disease

see abiotrophy.

equine motor neuronn. disease

(EMND) a syndrome of mature horses of uncertain etiology, but possibly an oxidative disorder associated with insufficient green forage in the diet and a deficiency of vitamin E. Characterized by generalized weakness, muscle fasciculations and weight loss, despite a normal appetite, that is caused by neurogenic muscle atrophy. There is also a distinctive retinopathy.

lower motor neuron n's

peripheral neurons whose cell bodies lie in the ventral gray columns of the spinal cord and whose terminations are in skeletal muscles. Called also LMN. See also lower motor neuron.

peripheral motor neuron n's

neurons in a peripheral reflex arc that receive impulses from interneurons and transmit them to voluntary muscles.

upper motor neuron n's

neurons in the cerebral cortex that conduct impulses from the motor cortex to the motor nuclei of the cerebral nerves or to the ventral gray columns of the spinal cord. Lesions of the upper motor neuron interrupt the inhibitory effect that upper motor neurons have on lower motor neurons, resulting in exaggerated or hyperactive reflexes. This is called also extensor rigidity. See also upper motor neuron. Called also UMN.

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neuron

Structural unit of the nervous system consisting of the nerve cell body and its various processes, the dendrites, the axon and the ending (also called bouton, end foot or axon terminal). There are many types of neurons within the nervous system; some transmit afferent nerve impulses to the brain (e.g. those carrying information from the photoreceptors to the visual cortex), or to the spinal cord (e.g. those carrying information from the receptors in the skin to the spinal cord). They are called sensory neurons. Others transmit efferent motor nerve impulses to a muscle (e.g. those carrying information from the Edinger-Westphal nucleus to the sphincter pupillae and ciliary muscles). These are called motor neurons. Other neurons carry nerve impulses from one neuron to another (internuncial neurons). Note: also spelt neurone. See action potential; synapse.