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42 Cards in this Set
- Front
- Back
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where in the ventral cord are some LMNs located
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lamina 9 of the ventral horn
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LMNs connect ____ to _____
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CNS to skeletal muscle (final common pathway)
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LMN are ___polar
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multi
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where in the brainstem are LMN located
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motor nuclei 3, 4, 5, 6, 7, 9, 10 , 11, 12
(all but 1, 2, 8) |
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patient who cannot look up and in (CN affected and where located)
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4 (trochlear) midbrain
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problem with most eye muscles (CN affected and where located)
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3 (occulomotor) midbrain
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patient with problems chewing (CN affected and where located)
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5 (trigeminal) mid pons
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patient with problem looking inwards (CN affected and where located)
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6 (abducens) low pons
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patient with facial assymetry (CN affected and where located)
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7 (facial) low pons
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patient with problems of the uvula or pharynx (CN affected and where located)
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9 (glossopharyngeal)
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patient with problems of respiratory muscles (CN affected and where located)
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10 (vagus) medulla
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patient with problems of the upper cervical muscles (CN affected and where located)
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11 (accessory) medulla
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patient with tongue deviations (CN affected and where located)`
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12 (hypoglossal) medulla
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why does it matter that the LMNs are multipolar
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tells us there are many sources of convergence
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what is the baseline firing of LMN and skeletal muscles
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resting muscle tone
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what adjusts the movement of resting muscle tone
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reflexes from either spinal cord or supraspinal level
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how is controlled voluntary control for movement
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through descending pathways either directly to the LMN or through interneurons to adjust the contraction
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a DTR (sensory input required for mov't) would be exemplified by a reflexive hammer tap --> (pathway)
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tap --> afferent --> sc/brainstem --> efferent --> gastroc soleus complex
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what LMN innervate extrafusal muscle fibers
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alpha LMN
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what LMN accounts for the majority of muscle contraction
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alpha LMN
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______ are large, fast while _____ are smaller
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alpha = large, fast
gamma = smaller |
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what LMN innervates muscle spindle fibers (skeletal)
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gamma LMN
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what LMN is important for setting muscle tone
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gamma
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what are extrafusal muscle fibers
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fibers outside the spindle
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what would be the signs of a LMN disease
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- decreased stretch reflex
- weakness or paralysis - decreased resistance to passive movement - decreased muscle sign |
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what are the 3 types of PNS injuries that could affect the LMN
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1) pressure
2) trauma 3) injury |
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what is the hallmark sign in a LMN disease
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decreased muscle tone
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what is neuropraxia
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transient compression/interruption of blood flow
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what is axonotmesis
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compression causing lesion of axon but CT still intact
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what is neurotmesis
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complete lesion of axon and CT
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what must happen for paralysis to occur in a muscle
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all LMN to that muscle are cut
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what are fasciculations
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twitch of a motor unit (one LMN and ll mm fibers it innervates)
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what is a fibrillation
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twitch of an individual muscle cell
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what would demonstrate transient hyperexcitability
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fasciculations and fibrillations
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how long will muscle cells last without innervation
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denervation atrophy begins, after one year if no possibility of reinnnervation then the muscle cells will start to die off
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what is a common example of a LMN disease
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polio
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what is the etiology of polio
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virus attacks the ventral horn of the gray matter
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what are the S and S with polio
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- denervation
- atrophy - deformities - HYPOactive DTRs |
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what is the role of the UMN
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to drive the LMN providing voluntary control to the LMN
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what is the primary method of influencing a LMN for voluntary control
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use of a UMN
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UMN goes from ___ to ____
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spinal cord/brainstem to cortex
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what is the 2 neuron pathway
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the idea of the upper and lower motor neurons (with the some interneurons)
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