motor neuron
Quick Summary
A motor neuron is a nerve cell that transmits impulses from the central nervous system to a muscle, causing movement. These neurons are crucial for muscle contraction, which begins with a nerve impulse traveling from the brain to the spinal cord via upper motor neurons. The impulse then moves through lower motor neurons to the neuromuscular junction, where it triggers muscle fiber contraction.12
Neurons, the basic cells of the nervous system, process and transmit information through electrical and chemical signals. They consist of a cell body, dendrites that receive signals, and an axon that transmits signals away from the cell body. Motor neurons are one of three functional types, alongside sensory neurons and interneurons. Diseases affecting motor neurons can lead to muscle weakness and wasting.342
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nervous systemNervous systems…which makes contact with a motor neuron. The motor neuron carries efferent impulses to the effector, which produces the response. Three types of neurons are involved in this reflex arc, but a two-neuron arc, in which the receptor makes contact directly with the motor neuron, also occurs. In a two-neuron…
Read More…which makes contact with a motor neuron. The motor neuron carries efferent impulses to the effector, which produces the response. Three types of neurons are involved in this reflex arc, but a two-neuron arc, in which the receptor makes contact directly with the motor neuron, also occurs. In a two-neuron…
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human nervous systemCellular laminae…of clusters of large alpha motor neurons, which innervate striated muscle, and small gamma motor neurons, which innervate contractile elements of the muscle spindle. Axons of both alpha and gamma motor neurons emerge via the ventral roots. Laminae VII and VIII have variable configurations, and lamina VI is present only…
Read More…of clusters of large alpha motor neurons, which innervate striated muscle, and small gamma motor neurons, which innervate contractile elements of the muscle spindle. Axons of both alpha and gamma motor neurons emerge via the ventral roots. Laminae VII and VIII have variable configurations, and lamina VI is present only…
Read More- human nervous systemEnteric nervous system
…interneurons relay the information to motor neurons. Motor neurons in turn modulate the activity of a variety of target cells, including mucous glands, smooth muscle cells, endocrine cells, epithelial cells, and blood vessels.
Read More…interneurons relay the information to motor neurons. Motor neurons in turn modulate the activity of a variety of target cells, including mucous glands, smooth muscle cells, endocrine cells, epithelial cells, and blood vessels.
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spinal cord…matter contains cell bodies, unmyelinated motor-neuron fibres, and interneurons connecting the two sides of the cord. Gray-matter cells form projections called horns. Fibres exiting the spinal cord from the dorsal and ventral horns join in paired tracts to form the spinal nerves. Information travels up the ascending tracts of neurons…
Read More…matter contains cell bodies, unmyelinated motor-neuron fibres, and interneurons connecting the two sides of the cord. Gray-matter cells form projections called horns. Fibres exiting the spinal cord from the dorsal and ventral horns join in paired tracts to form the spinal nerves. Information travels up the ascending tracts of neurons…
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spinal nerveThe other, composed of motor fibres, leaves the spinal cord via the ventral root; its cell bodies lie in specific areas of the spinal cord itself.
Read MoreThe other, composed of motor fibres, leaves the spinal cord via the ventral root; its cell bodies lie in specific areas of the spinal cord itself.
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nervous system diseaseMotor neuron disease…and lateral sclerosis are both motor neuron diseases, progressive disorders of older people that affect neurons of the ventral horns, of the medullary motor nuclei, and of the corticospinal tracts. ALS, or Lou Gehrig disease, is characterized by muscle wasting due to loss of the ventral-horn cells (the lower motor…
Read More…and lateral sclerosis are both motor neuron diseases, progressive disorders of older people that affect neurons of the ventral horns, of the medullary motor nuclei, and of the corticospinal tracts. ALS, or Lou Gehrig disease, is characterized by muscle wasting due to loss of the ventral-horn cells (the lower motor…
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prenatal developmentCranial nerves…VI, and XII are pure motor nerves that correspond to the ventral roots of spinal nerves. The acoustic nerves (VIII) are pure sensory nerves, each with a ganglion that subdivides for auditory functions and functions having to do with equilibrium and posture; they correspond to dorsal roots. Nerves X and…
Read More…VI, and XII are pure motor nerves that correspond to the ventral roots of spinal nerves. The acoustic nerves (VIII) are pure sensory nerves, each with a ganglion that subdivides for auditory functions and functions having to do with equilibrium and posture; they correspond to dorsal roots. Nerves X and…
Read More- neuritis
The inflammation of motor neurons causes symptoms ranging from muscle weakness to complete paralysis. Muscles in the area served by the affected nerve lose tone, become tender, and may atrophy. Bell palsy, which causes a characteristic distortion of the muscles on one side of the face, is a…
Read MoreThe inflammation of motor neurons causes symptoms ranging from muscle weakness to complete paralysis. Muscles in the area served by the affected nerve lose tone, become tender, and may atrophy. Bell palsy, which causes a characteristic distortion of the muscles on one side of the face, is a…
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