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Motor Control and the Descending Systems

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What is the best example of feed-forward control?

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A. A stretch reflex resisting forward sway when a person is pushed from behind

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B. Looking at a mouse before reaching for it

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C. Leaning forward before reaching forward

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D. Moving one finger while holding the wrist stable

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C. Leaning forward before reaching forward

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Which of the cortical motor areas is most likely to produce a corticospinal cell that synapses directly on an alpha motoneuron?

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A. Primary motor cortex

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B. Supplementary motor area

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C. Premotor cortex

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D. All are equal in this regard

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A. Primary motor cortex

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Which body area has a disproportionately small representation in the primary motor cortex?

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A. Face (mouth)

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B. Arm and hands

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C. Trunk

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D. Legs and feet

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C. Trunk

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>In which part of the spinal cord would we expect to find a complete absence of the ventral (anterior) corticospinal tract?

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A. Upper cervical

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B. Cervical enlargement

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C. Thoracic

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D. Lumbosacral enlargement

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D. Lumbosacral enlargement

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Which of the descending systems listed here has bilateral influence?

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A. Rubrospinal

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B. Lateral reticulospinal

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C. Medial reticulospinal

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D. Lateral vestibulospinal

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C. Medial reticulospinal

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A patient in a neurologic clinic has trouble moving the right side of her body, reaches with her right arm in a very limited way, and does not seem able to use her right hand. She can sit and can walk with a cane, but there is also some difficulty in the right leg. She is speaking and her eye movements and facial function seem fairly normal. Where would you most expect the lesion in this person’s nervous system to be found?

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A. Left cervical spinal cord

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B. Left motor cortex

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C. Left brainstem

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D. Left cerebellum

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B. ...

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