Term
| Where is the primary motor cortex located? |
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Definition
| in the precentral gyrus & the paracentral lobule |
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Term
| What is the difference between the corticobulbar tract and the corticospinal tract? |
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Definition
corticobulbar: axons terminate in the brainstem
corticospinal: axons terminate in the spinal cord |
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Term
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Definition
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Term
| lateral corticospinal tract |
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Definition
| the tract where a large majority of the axons in the pyramidal tract cross the midline at the caudal end of the medulla to enter the lateral columns of the spinal cord on the opposite side |
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Term
| ventral corticospinal tract/anterior corticospinal tract |
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Definition
| the 10% of axons in the pyramidal tract that enter the spinal cord without crossing the midline; axons terminate either ipsilaterally or bilaterally |
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Term
| 2 aspects of muscle use correlated with the activity of primary motor neurons |
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Definition
1. the magnitude of the force produced by muscles
2. the direction of the force produced by muscles |
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Term
| The activity of a number of different muscles is directly facilitated by _____ |
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Definition
| the discharges of a given upper motor neuron |
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Term
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Definition
| the peripheral muscle group controlled by a specific upper motor neuron |
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Term
| The activity of the upper motor neurons in the cortex controls _____, rather than individual muscles |
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Definition
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Term
| How does the premotor cortex influence motor behavior indirectly? |
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Definition
| through extensive reciprocal connections with the primary motor cortex |
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Term
| How does the premotor cortex influence motor behavior directly? |
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Definition
| via axons that project through the corticobulbar & corticospinal pathways to influence local circuit & lower motor neurons of the brainstem & spinal cord |
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Term
| Rather than directly commanding the initiation of a movement, the premotor neurons appear to encode the _____ |
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Definition
| intention to perform a particular movement |
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Term
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Definition
| a subset of neurons that respond not just in preparation for the execution of particular movements, but also when the same action is being observed |
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Term
| Is there a difference in the response of mirror motor neurons when an action is being pantomimed versus being legitimately carried out? |
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Definition
| mirror motor neurons respond much less well when actions are pantomimed without the presence of a behavioral goal |
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Term
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Definition
| critical for the production of speech; a rostral division of the lateral premotor cortex; has a special role in organizing vocal tract articulators that are involved in the production of speech sounds |
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Term
| How is the medial premotor cortex different from the lateral area? |
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Definition
medial: specialized in selection of movements with an internal cue ("spontaneous movements")
lateral: specializes in selecting movements with an external cue |
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Term
| upper motor neuron syndrome |
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Definition
| damage to the descending motor pathways anywhere along the trajectory of the upper motor neurons from the cerebral cortex to the lower end of the spinal cord |
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Term
| signs & symptoms of upper motor neuron syndrome |
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Definition
| weakness, spasticity, increased tone, hyperactive reflexes, Babinski's sign, loss of fine voluntary movements |
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Term
| signs & symptoms of lower motor neuron syndrome |
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Definition
| weakness, paralysis, decreased reflexes, hypoactive reflexes, decreased tone, fasciculations, fibrillations, severe muscle atrophy |
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Term
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Definition
| the initial period of hypotonia after upper motor neuron injury; reflects the decreased activity of spinal circuits suddenly deprived of input from the motor cortex & brainstem |
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Term
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Definition
| extension of the big toe/fanning of the other toes in response to stroking the sole of the foot; normal individuals should curl their toes as a response |
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Term
| Why is the Babinski sign apparent in normal human infants? |
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Definition
| their corticospinal pathway is not totally formed yet |
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Term
| What is the spasticity symptom of upper motor neuron syndrome? |
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Definition
| increased muscle tone, hyperactive stretch reflexes, & oscillatory contractions/relaxations of muscles in response to muscle stretching |
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Term
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Definition
| extensive upper motor neuron lesions may be accompanied by rigidity of the extensor muscles of the leg & the flexor muscles of the arm |
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Term
| Spasticity represents an abnormal increase in the _____ of the spinal cord stretch reflexes due to loss of descending suppression |
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Definition
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