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26 Cards in this Set
- Front
- Back
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1. From where do somatic motor nerves receive data from?
Input to motor nerves includes what? |
Multiple sources
Pyramidal tracts from motor cortex **responsible for fine, intentional movements |
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2. Where are extrapyramidal tracts?
What are the two tracts? What is the origin for each tract? |
Reticular formation
1. Pontine reticulo-spinal tract -origin is w/in pons 2. Medullary reticulo-spinal tract -origins is w/in medulla |
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3. What is the function of the pontine reticulo-spinal tract?
When this tract is isolated from cortex and medulla what does it cause in humans? What is the function of the medullary reticulo-spinal tract? |
Stimulation of all somatic muscle motor nerves, esp extensors
Causes opisthotonus in humans and decerebrate rigidity in animals Function is inhibition of all somatic muscle motor nerves, esp extensors |
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4. What is the origin and function of the rubro spinal tract?
What is the origin and function of the lateral vestibulo-spinal tract? What is the origin and function of the tecto-spinal tract? |
O: red nucleus
F: stimulation of flexor & inhibition of extensor motor nerves O: lateral vestibular nuclei F: stimulation of extensor, inhibition of flexor motor nerves O: superior colliculi F: control of neck muscle motor nervs |
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5. What is the basal ganglia?
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System of several interconnected nuclei
1. Globus palladus 2. Caudate nucleus (together = striatum) 3. Subthalamic nucleus 4. Substantia nigra |
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6. What is the function of the basal ganglia?
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1. Maintain posture
2. Initiate and maintain repetitive movement (walking, chewing, etc.) **controls spinal cord pattern generators |
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7. What does overall stimulation of the basal ganglia cause?
What is dyskinesias? What are the two circuits via which the basal ganglia functions? |
Lessening of muscle tone
Difficulty in performing voluntary movements (principle is "disinhibition") 1. Putamen circuit (indirect pathway) 2. Caudate circuit (direct pathway) |
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8. What is the input of the putamen circuit?
What is the output? What is the function? What type of feedback does it use? What does the putamen circuit inhibit? |
I: caudate n. has cortical input, putamen has motor input
O: g. pallidus and reticular nuclei of S. nigra F: generates proper muscle tone for posture Uses negative feedback control systems Generally inhibits somatic motor nerves (reduces overall energy expenditure) |
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9. What is the input of the caudate circuit?
What is the output? What is the function? |
I: motor and sensory cortex to g. pallidus and reticular nuclei of s. nigra
O: thalamus and thence to cortex F: initiates and regulates "gross" intentional but repetitive movements |
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10. What is the function of the striatum?
What does lesions in GABA secreting nerves result in? |
Initiates gross intentional movements
1. Reduces inhibition of the striatum 2. Results in uncontrolled movements (circuits are released from inhibition) **Huntington's chorea, chorea, athetosis, dystonia |
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11. What is the function of the globus pallidus?
What does a lesion to it result in? |
Maintains posture
Reduce ability of trunk muscles to maintain posture |
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12. What is the function of the subthalamic nucleus?
What does a lesion to it cause? |
Inhibition of tone related balance
Dyskinesias showing flailing movements termed hemiballism or ballism |
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13. What causes Parkinson's disease?
What are the symptoms? How can function be restored? |
Interruption of dopamine nerves from the pars compacta of substantia nigra to striatum
1. Rigidity 2. Hypokinesia 3. Resting tremors **most common symptoms associated w/ basal ganglia lesions Restored w/ L-Dopa |
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14. What is the mechanism for Parkinson disease?
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Production of abnormal amounts of protein alpha-synuclein which clumps and kills dopamine producing neurons
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15. What do lesions in fibers from s. nigra to striatum cause?
What can cause dyskinesia (chorea, athetosis)? What do lesions in fibers from subthalamus that stimulate GABA nerves in thalamus cause? What do lesions in GABA ergic nerves from striatum inhibit and cause? |
Releases putamen from inhibition (parkinsonism)
**lack of transmitter dopamine Dopamine antagonists can cause tardive dyskinesia Ballismus Inhibit g. pallidus and Huntington's chorea |
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16. What is the overall function of the cerebellum?
What else does the cerebellum do? Anatomically, what are the three lobes of the cerebellum? What are the three lobes physiologically? |
Maintain posture and balance (i.e. position) in 3-D space
**unlike basal ganglia, cerebellum cannot initiate movement Refines ongoing movements 1. Posterior 2. Anterior 3. Flocculonodular 1. Paleo or spino cerebellum 2. Neo or cerebro cerebellum 3. Archi or vestibulo cerebellum |
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17. What is the input for the neocerebellum (lateral portion of posterior lobe)?
What is the function of it as demonstrated by lesions? |
I: cerebrum
-multiple data input from most of the afferent cortex 1. Fine motor skill deficit 2. Decomposition of movement 3. Intention tremor, dysmetria, adiodochokinesia, dysarthria |
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18. Where is the paleo (spinal) cerebellum?
Where does it receive input from? What is the function? |
Medial cerebellar cortex
I: spinal cord Not clear in humans but may have multiple integrative functions |
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19. Where is the vestibulo or archi cerebellum?
Where does it receive input from? What is the output demonstrated by lesions? |
Flocculonodular lobe
Input: 1. Vestibular nuclei 2. Proprioceptors 3. Vision Ataxia |
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20. Circuitry of cerebellum devovles to an input-output involving what fibers?
Where does input to the cerebellum come from? |
Purkinje fibers
1. Spinocerebellar tract 2. Inferior olivary nuclei |
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21. What does the spinocerebellar tract do?
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1. Direct whole organism proprioceptive input and cerebral input
2. Stimulates granular cells which weakly stimulate many Purkinje cells 3. Stimulates basket cells and stellate cells both of which inhibit Purkinje cells |
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22. What does the inferior olivary nuclei receive input from?
What does it feed into? What do these fibers do? |
Proprioceptive input from whole organism
Feeds into climbing fibers (distinct short lived response) Climbing fibers strongly stimulate single Purkinje cell |
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23. What is the output from the cerebellum?
What does the inhibitory output function to do? What does this in turn do? |
Stimulation of Purkinje cells results in strong inhibition of deep cerebellar nuclei and lateral vestibular nuclei
Functions to modulate thalamic and medullary output This modulates motor output and applies appropriate timing of muscle groups to fit ongoing actions |
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24. What processing function does the cerebellum have?
What is the input for this function? Where is the output directed towards? |
Mid level processor which modulates ongoing motor activity
Input involves many pathways Out put directed to: 1. Thalamus and motor cortex 2. Pontine nuclei 3. Motor cortex, basal ganglia & reticular formation |
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25. How does the cerebellum act as a comparator?
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Acts as a comparator w/ the power to adjust the action to a set point of preset norms
Takes various input data from newly initiated or ongoing motor activity and compares it to the set point Output adjusts the ongoing motion so that it matches or approximates the set pt of preset or desired norms |
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26. In essence why does the cerebellum modulate ongoing motor activity(ies)?
What is a newly implicated cerebellar function? Why is this suggested? |
To ensure that balance is appropriate to that action(s) being performed
Cerebellum has been linked to pain perception Pain receptors are found on cerebellar neurons suggesting that prolonged pain mechanism may interact w/ the cerebellum |
