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49 Cards in this Set
- Front
- Back
Flocculonodular lobe |
-major input/output is with vestibular apparatus -oldest part phylogenetically -influences the vestibulospinal and recticospinal tracts -concerned with balance |
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Intermediate zone |
-major input/output is with the spinal cord -second oldest phylogenetically -influences the rubrospinal tract -concerned with posture & muscle tone |
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Lateral zone |
-major input/output is with cerebral cortex -influences the cerebral cortex via the thalamus and the rubrospinal tract -concerned with muscular coordination |
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Dentate, emboliform, globose, and fastigial nucleus |
contain large multipolar neurons whose axons form the cerebellar outflow in the superior & inferior cerebellar peduncles. |
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Dentate inputs |
are from lateral parts of cerebellar hemispheres |
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Globose/ emboliform receive inputs from |
intermediate part of hemisphere |
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Fastigial inputs |
from vermis and flocculondular lobe |
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The white matter is made up of 3 group fibers |
1. intrinsic 2. afferent 3. efferent |
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Intrinsic fibers |
-do not leave the cerebellum -connect different folia of the cerebellar cortex and vermis on the same side -some connect the 2 hemispheres |
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Afferent fibers |
-form the greater part of the white matter, and proceed to the cortex - in the cortex, they lose their myelin sheath and end as either climbing or mossy fibers |
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efferent fibers |
-are the output of the cerebellum -they are the axons of the neurons of the cerebellar nuclei upon which the axon of the Purkinje cells synapse |
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most of the afferent fibers pass through |
the inf. and the middle cerebellar peduncles |
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most of the efferent fibers pass through |
the sup. and the middle cerebellar peduncles |
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Climbing fibers |
-are the terminal fibers of the oliviocerebellar tracts -they enter the molecular layer of the cortex, where they branch and make multiple synaptic contacts with only one Purkinje cell. -a few side branches synapse with adjacent stellate and basket cells |
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Mossy fibers |
-are the terminal fibers of all the other cerebellar afferents -they have multiple branches and exert a much more excitatory effect -Ex: a single mossy fiber may stimulate thousands of Purkinje cells through the granule cells -the remaining cells in the cerebellar cortex, the Golgi, basket and stellate cells limit the area excited by Purkinje cells by inhibiting these |
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What are the cerebellar afferent fibers from the cerebral cortex? |
1. Corticopontocerebellar pathway 2. Cerebro-oliviocerebellar pathway 3. Cerebro-reticulocerebellar pathway 4. Vestibulocerebellar tract |
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Corticopontocerebellar function |
control from cerebral cortex |
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Cerebro-olivocrebellar func. |
control from cerebral cortex |
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Cerebro-reticulocerebelalr func. |
control of voluntary movements -cerebral cortex informs the cerebellum about initiation of the movement, so that can be monitored by the cerebellum |
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Vestibulocerebellar func. |
controlling the position and movement of the head. |
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Other afferent fibers |
-ant. and post. spinocerebellar tracts convey info about muscle and joints--> end as mossy fibers |
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Major input source |
-is corticopontine systems that originate in motor cortex, primary sensory cortex, and visual cortex and relay through pontine nuclei. -pontocerebellar fibers then decussate and enter cerebellum via middle cerebellar peduncle. |
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What are the cerebellar efferent fibers? |
1. Globose-emboliform-rubral pathway 2. Dento-thalamic pathway 3. Fastigial Vestibular pathway 4. Fastigial Reticular pathway |
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Globose-emboliform-rubral func. |
controlling ipsilateral motor activity
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Dento-thalamic func. |
controlling ipsilateral motor activity |
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Fastigial Vestibular func. |
controlling ipsilateral extensor tone |
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Fastigial Reticular func. |
controlling ipsilateral muscle tone. |
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Lesions of lateral cerebellum affect |
distal limb coordination |
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medial lesions affect |
mainly trunk control, posture, balance, and gait |
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cerebellar deficits occur__________ to the lesion |
ipsilateral |
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Acute lesions |
produce sudden, severe signs and symptoms, but there is considerable recovery perhaps due to compensation of loss of cerebellar function by other areas of the CNS |
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Chronic lesions |
such as slow growing tumor, produce much less severe symptoms and signs that those of acute lesions |
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Cerebellar lesion S&S |
-hypotonia -postural changes and alteration of gait -ataxia (disturbances of voluntary mov.) -intension tremor -Dysdiachokinesia -Disturbances of reflexes -Disturbances of ocular movement: nystagmus -Disorders of speech |
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Ataxia |
-refers to disordered contractions of agonist and antagonist muscles and lack coordination between movements at diff. joints typically seen in patients with cerebellar lesions -ataxia movements have irregular, wavering course consisting ofcontinuous overshooting, overcorrecting and then overshooting again around the intended trajectory. |
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Truncal Ataxia |
-caused by lesions in vermis (controls medial m. groups (posture/equillibrium) -produce wide-based, unsteady, staggering gait -patients often fall toward the side of the lesion -in severe cases patients cannot even sit up w/o assistance |
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Appendicular ataxia |
-lesions of intermediate and lateral regions of cerebellum -ex: finger to nose text |
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Common causes of acute ataxia |
-toxin ingestion -ischemic or hemorrhagic stroke |
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Common cause chronic ataxia |
-brain metastases -alcoholism -Multiple sclerosis (MS) -degenerative disorders of cerebellum |
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Sensory ataxia |
-occurs when dorsal column- medial lemniscus pathway is damaged -impaired proprioception occurs -function improves with visual input -worsens with eyes closed or in the dark |
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Chronic ataxia in children is often caused by |
-cerebellar astrocytma, medulloblastoma, or Friederich's ataxia |
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Vascular supply of cerebellum |
-post. inf. cerebellar a. -ant. inf. cerebellar a. -sup. cerebellar a. |
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Cerebellar a. infarcts are more common in |
-PICA, SCA, and AICA |
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symptoms of cerebellar infarcts |
vertigo, nausea, vomiting, horizontal nystagmus, limb ataxia, unsteady gait, headache |
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Lateral medullar infarct |
-can cause cerebellar symptoms due to damage of cerebral peduncles, however, in these cases, medullary symptoms will also occur including Horner's syndrome. |
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Why is swelling in post. fossa life threatening? |
Due to potential for brainstem compression |
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Cerebellar cortex is divided into 3 layers |
-Molecular layer (external) -Purkinje cell layer (middle) -Granular layer (internal) |
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Molecular layer |
-stellate cells -basket cells |
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Purkinje cell layer |
-large neurons -dendrites--> pass into molecular level -axons--> pass through granular layer |
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Granular layer |
-small granular cells -golgi cells--> send dendrites to the molecular layer and their axons synapse w/ the dendrites of the granular cells |