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20 Cards in this Set
- Front
- Back
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What is another name for the pre central gyrus? |
primary motor cortex
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Which is more important: UMN or LMN? Why? |
UMN, because it tells LMN what to do |
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Where is the primary motor cortex located? |
frontal lobe |
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What is the primary motor cortex responsible for? |
precise control of complex voluntary movements |
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How is the body mapped in the primary motor cortex? |
as the motor homunculus |
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What are neurons in the primary motor cortex called? |
upper motor neurons (UMN) |
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What do axons from upper motor neurons form? Targeting what? |
the corticospinal and corticonuclear tracts (pyramidal tracts) that target LMNs in the brainstem and spinal cord |
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How are the corticospinal fibers often referred to as they descend through the CNS? |
by regional names |
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Axons from UMNs descend through a white matter tract that... |
changes names in different regions. |
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How do we refer to pyramidal tract fibers in the subcortical region? What type of fibers are found here? |
-corona radiata and internal capsule
-contains both ascending sensory and descending motor fibers |
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How do we refer to pyramidal tract fibers in the midbrain? What type of fibers are found here? |
-the cerebral peduncles
-almost exclusively motor fibers |
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How do we refer to pyramidal tract fibers in the pons? |
corticospinal fibers |
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How do we refer to pyramidal tract fibers in the medulla? What type of fibers are found here? |
-pyramids
-almost exclusively motor fibers |
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How do we refer to pyramidal tract fibers in the spinal cord? What type of fibers are found here? |
-lateral corticospinal tract or medial corticospinal tract
-motor |
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Where do upper motor neurons synapse on lower motor neurons (or interneurons)? |
in the ventral grey of the spinal cord (VIII & IX) or cranial nerve motor |
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What is the pyramidal decussation? |
refers to fibers of the corticospinal pathway that, at the caudal medulla, cross to the contralateral side |
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What percentage of the corticospinal fibers are involved in the pyramidal decussation? |
~90% |
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How do the pyramidal decussation fibers rearrange themselves in the medulla, and what tract do they form? |
-as they cross, they move from an anterior position (pyramids) to a more posterolateral position
-lateral corticospinal tract |
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What pathway is one of the biggest proponents of upper limb flexion? |
rubrospinal pathway |
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What tract mediates reflex postural movements in response to visual input in order to move the head and neck in a position to visualize an object? |
tectospinal tract |
