Lab 8.1: Cerebellum/Basal Ganglia
Terms
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- Do structures in the basal ganglia project fibers through the anterior commissure?
- No - even though this structure penetrates the basal ganglia, it carries primarily axons between the temporal lobes.
- Which limb of the internal capsule is used by the basal ganglia for projection of fibers?
- The anterior limb.
- What is hemiballismus?
- A ballistic flailing of limbs due to unilateral lesions to the subthalamus.
- Describe two functions of the basal ganglia.
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1.Initiation and planning of movements
2.Suppression of unwanted movements
3.Reinforces ongoing movements in the face of obstacles - What is athetosis?
- The symptomatic writhing motion, most often seen in HD patients.
- Describe the tremor caused by damage to the basal ganglia. How is this different from the tremor seen in patients with cerebellar damage?
- Basal ganglia damage results in a resting tremor that typically disappears when movement is initiated. Cerebellar damage causes an intention tremor that worsens as a movement is performed.
- What is the basic function of the cerebellum? Name three aspects of a movement that are monitored by the cerebellum.
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*Modification of ongoing movements
*Limb proprioception, motor programs from the cerebral cortex, and vestibular and ocular input concerning balance - What are the three cardinal signs of cerebellar damage?
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1.Ataxia
2.Nystagmus
3.Intention tremor - What kind of fibers are carried by the superior cerebellar peduncle? Where do these fibers decussate?
- The SCP carries primarily efferent fibers. Deccussation occurs at the level of the inferior colliculus.
- What kind of fibers are carried by the middle cerebellar peduncle? From where do these fibers come?
- The MCP carries almost exclusively afferent fibers that come in from the contralateral pons.
- Which cerebellar peduncle would be affected by an infarct in the PICA?
- The inferior cerebellar peduncle as it is passes through the dorsolateral mid-medulla.
- What kind of fibers are carried by the inferior cerebellar peduncle?
- The ICP carries both efferent (outgoing) and afferent (incoming) fibers.
- Which peduncle carries output from the fastigial nucleus? What functions does this nucleus attend to?
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*output goes to the inferior cerebellar peduncle
*posture and balance - What are the 2 interposed nuclei? Where do these nuclei send their output fibers? What functions do these nuclei attend to?
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*emboliform and globose
*output goes to the SCP
*coordination of limb movement - What is the function of the dentate nucleus?
- Motor planning.
- Describe the innervation provided by the Purkinje cells of the cerebellar cortex to the deep nuclei.
- It is always inhibitory.
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T/F:
Afferent fibers that synapse on the deep nuclei directly without contacting the Purkinje cells provide both inhibitory and excitatory stimulation. - False: these fibers provide excitatory stimulation only.
- What clinical emergency is often associated with the cerebellar tonsils?
- Increased intracranial pressure can cause the tonsils to herniate through the foramen magnum and compress the brainstem
- What parts of the cerebellar cortex comprise the spinocerebellar division? The main input to this area comes from where?
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*the vermis and intermediate hemispheres
*receives input from the below - i.e. regarding spinal activity (posture and balance and limb movement). - What portions of the cerebellar cortex comprise the cerebrocerebellar area? What function is this area involved with?
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*the lateral hemispheres
*involved with motor planning - Which portions of the cerebellar cortex make up the vestibulocerebellar area? What is its function?
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*the flocculus and nodulus
*balance and eye movement - What is a significant difference between the wiring of the cerebellar and cerebral cortex, especially in regards to localizing lesions?
- The cerebellar cortex is wired ipsilaterally while the cerebral cortex is wired contralaterally.
- Where do climbing fibers originate from?
- The inferior olivary nucleus.
- What five structures make up the basal ganglia?
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1.Caudate
2.Putamen
3.Subthalamus
4.Substantia Nigra
5.Globus pallidus - Name three symptoms seen with damage to the basal ganglia.
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1.Chorea
2.Athetosis
3.Bradykinesia
4.Rigidity
5.Resting tremor
6.Hemiballismus - In general, what information does output from the cerebellum provide?
- Refinement of movements.
- Where does the fastigial nucleus receive projections from?
- It handles projections from the spinal cord and the vermis of the spinocerebellar cortex, as well as from Purkinje cells in the FN lobe
- What part of the cerebellar cortex do the interposed nuclei receive projections from? How does this relate to their function?
- They receive projections from the intermediate hemispheres of the spinocerebellar cortex and thus are involved with limb movement.
- What part of the cerebellar cortex does the dentate nucleus receive projections from and how does this relate to its function?
- It receives projections from the lateral hemispheres of the cerebrocerebellar cortex and thus is involved with motor planning.
- What part of the cerebellum does the vestibular nucleus receive projections from?
- The flocculus and nodulus, and vermis.
- Which of the deep nuclei send their output through the SCP?
- The dentate and interposed nuclei.
- Which of the deep nuclei send their output through the ICP?
- The fastigial nuclei.