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38 Cards in this Set
- Front
- Back
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Upper Motor Neurons
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- projection fibers that originate in motor strip
- highest level of motor control in the muscular system - many giant pyramidal cells work together |
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Do upper motor neurons exit the CNS?
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never
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What two pathways do upper motor neurons have?
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to the spinal cord or to the brainstem
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how many pathways do upper motor neurons have?
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2
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What are the names of the fibers that go to the spinal cord?
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- corticospinal aka pyramidal tract
- corticorubrospinal tract |
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What fibers go to the brainstem?
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- corticobulbar (go to the brain stem in general)
- corticopontine (go to pons) |
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Corticopontine are a type of ________ tract
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corticobulbar
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The corticospinal tract goes through and constitutes part of what?
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the internal capsule
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internal capsule
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a band of fibers on either side of the thalamus. white matter.
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the corticospinal tract makes up the _______ of the ________
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pyramids of the medulla
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What percent of corticospinal fibers cross over, and what descend ipsilaterally (but eventually cross over)?
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80% cross over, 20% descend ipsilaterally and then cross over
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What do corticospinal tract fibers synapse with?
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motor neurons in the spinal cord
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T or F- eventually all corticospinal tracts cross over, just at different levels
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T
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What terms would we use to describe corticospinal tracts?
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- descending
- direct tracts - asynaptic |
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What is the function of corticospinal tracts?
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- discreet, voluntary movements
- accurate, skilled, spatially oriented - responsible for accurate, quick voluntary movement - skilled movement- writing, walking, talking |
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Where do corticobulbar tracts go?
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midbrain, pons, or medulla
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Where do upper motor neurons to the brainstem terminate?
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at nuclei of cranial nerves
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Corticobulbar and corticopontine tracts have projection fibers from each cerebral cortex, so they have ___________
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bilateral representation
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How to corticobulbar and corticopontine tracts project?
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bilaterally to left and right motor nuclei in brainstem
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What affects would lesions on upper motor neurons cause?
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- would affect voluntary motor activity on opposite side of body
- muscles become spastic or hypertonic (too tight) - muscles become paralyzed or weakened - damage axons and fibers of muscles |
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Lesions on upper motor neurons will NOT cause what?
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- will not cause tremors (abnormal movement activity)
- will not cause muscle atrophy |
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Where do the cells of lower motor neurons originate?
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- in brain stem or in the ventral horn of the spinal cord
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What are the two types of lower motor neurons?
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- spinal nerves
- cranial nerves |
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Spinal Nerves
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go directly to skeletal muscles
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Cranial Nerves
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muscles of phonation, respiration, etc. .
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What do all lower motor neurons have in common?
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- the cell body is protected within the CNS
- the axons are NOT, they exit and make up the PNS |
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What are different terms for lower motor neurons?
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- alpha motor neurons
- gamma motor neurons - spinal nerves - cranial nerves - lowest common pathway |
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Dysarthria
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dysfunction of muscular activity due to some type of brain damage
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What muscles are affected with dysarthria that cause speech difficulties?
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- respiratory muscles
- articulatory muscles - phonatory muscles - resonance- velo-pharyngeal muscles |
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Spastic Dysarthria- what causes it?
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upper motor neuron damage
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What are symptoms of Spastic Dysarthria?
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-tight muscles=difficulty breathing, vocal folds, larynx
- strained-strangled voice, lip, jaw, tongue weakness, slow movements effect speech |
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Flaccid Dysarthria- what causes it?
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lower motor neuron damage
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What are the symptoms of Flaccid Dysarthria?
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- loose, flaccid muscles
- breathy voice, weakness, muscle atrophy |
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The extrapyramidal system is an _________ system, the pyramidal system is a _______ system
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indirect, direct
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Is the extrapyramidal system ascending or descending?
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ascending
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To adjust movement what does the extrapyramidal system have?
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- feedback loops aka side loops
-circuitous detours at many levels |
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In the extrapyramidal system where is there no direct pathway?
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from basal ganglia to spinal cord
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What diseases are associated with lesions of the extrapyramidal system?
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Disorders of movement like Parkinson's and Huntington's Chorea
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