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14 Cards in this Set
- Front
- Back
what are some types of movement and why are they interesting?
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reflexes
rhythmic: a little more complicated, involves initiation and termination. voluntary movement: complex fine: involves thumb opposition or independent finger movements. |
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list the indirect motor pathways:
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reticulospinal
rubrospinal tectospinal vestibulospinal note that these are unconscious, involved in reflexes and in keeping posture. |
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where are the upper motor neurons located...in what layer?
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in layer V pyramidal cells of the precentral gyrus (motor cortex)
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what are lower motor neuron symptoms if lesioned?
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atrophy, flacid paralysis
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what's a motor unit?
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all the muscle fibers innervated by a single lower motor neuron. this can be a lot of fibers or a few fibers. tend to have small motor units in the hands, large motor units in the legs.
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corticospinal tract: give a more detailed description of where the upper motor neurons are located:
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1/3 in premotor
1/3 in motor 1/3 in somatosensory cortex (post-central gyrus) |
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go through the pathway of the corticospinal tract:
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from the cortex, through the corona radiata, through the posterior internal capsule. through the cerebral peduncles, basalar pons, medullary pyramids, decuastion, spinal cord.
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what are some upper motor neuron lesion signs?
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hyper-reflexivia
spasticity hyper-tonia babinski sign eventual atrophy from disuse, not fast. |
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corticospinal tract - how is it somatotopically arranged?
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this is a little different. here, the medial parts innervate the medial-body (the muscles around the spinal cord, neck, etc). the outer portions of the tract innervate the distal muscles (hands, fingers, etc).
so at the level of the upper limb, the inner ones control the neck. the outer ones control the fingers. |
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in the internal capsule, how is the corticospinal tract somatotopically organized?
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FATL, starting at the genu and going backwards.
face, arm, trunk, and leg. all in the genu and posterior section of the internal capsule. |
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do lesions commonly affect both the corticospinal and corticobulbar tracts?
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yes. they travel together in the brain.
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tongue nerve - how can we tell upper vs. lower motor neuron damage?
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the 12th nerve decusates. so, if the injury is after the decusation, you lick the wound (toward the side of the lesion).
if it's above the decusation, you deviate contralaterally. |
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what's weird about facial muscle innervation?
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above the eyes, the muscles get dual innervation from both cortices.
below, it's contralateral and only get one. |
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so how can we use this to diagnose upper vs. lower motor neuron facial injury?
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if you damage the upper motor neurons, the face experiences paralysis on the contralateral lower side, while the forehead stays fine (dual innervation, afterall).
if you damage the lower motor neuron, get ipsilateral drooping of both the face and forehead, as this is the final common pathway. |