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47 Cards in this Set
- Front
- Back
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How much % of neurones are in the cerebellum? |
more than 50% |
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What are the functions of the cerebellum? |
-Regulator for motor input -Comparator - comparing what you intended to do with what you did do -Adjusts motor output -Regulates movement and posture indirectly |
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Does the cerebellum perceive sensation? |
-No, but it uses broad range of sensory input to evaluate, influence and modify motor behaviour |
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Does the cerebellum precipitate motor activity? |
No |
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Does a lesion to the cerebellum result in paralysis? |
No - rather a decomposition of movement that is purposeful or productive |
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What are the 3 main cerebellar arteries? |
-Posterior inferior cerebellar artery (PICA) -Anterior inferior cerebellar artery (AICA) |
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Where is the cerebellar located? |
-Under the occipital lobe -In the posterior cranial fossa -On the dorsal surface of the brainstem |
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What is the vermis? |
-A midline structure that divides the cerebellum into two hemispheres |
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Where is the flocculonodular lobe located? |
-Posterolateral fissue |
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Where is the anterior lobe located? |
-Anterior to primary fissure |
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Where is the posterior lobe located? |
-Posterior to primary fissure |
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Is the cerebellum somatotopically arranged? |
-Yes -Trunk in midline, limbs more lateral |
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What is so important about the deep nuclei of the cerebellum? |
-The deep nuclei are the sole output structure of the cerebellum |
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What are the three deep nuclei? |
-Fastigial nucleus -Interposed nucleus -Denate nucleus |
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What structures connect the brainstem to the cerebellum? |
-three cerebellar peduncles (large bundle of fibres) |
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What are the three cerebellar peduncles? |
-Superior cerebellar peduncle -Middle cerebellar peduncle -Inferior cerebellar peduncle |
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What is the role of the superior cerebellar peduncle? |
-Midbrain and above -Information out of cerebellum to cerebrum. -Primary cerebellar output |
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What is the role of the middle cerebellar peduncle? |
-Pons level of brainstem -Information to cerebellum from cerebrum |
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What is the role of the inferior cerebellar peduncle? |
-From spinal cord and medulla -Information to cerebellum |
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What is the cerebellum in communication with? |
-Cerebral cortex -Spinal cord - somatosensory -Vestibular system -Red nucleus -Thalamus -Reticular formation |
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What is the function of the cerebellum? |
-Massive amount of information enters the cerebellum and cerebellar output is vital for normal movement -Cerebellum acts as a comparator by comparing actual motor output with the intended movement and then adjusting movement as necessary -Integrates motor and sensory info to achieve accurate movement and adjusts UMN output accordingly |
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How does the cerebellum help to coordinate movement? |
-Direction -Timing /speed -Force -Helps to create synergistic muscle contractions |
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What does feedforward mean? |
-Cerebellum is able to make a prediction when you plan a movement of other motor commands the body will need to make to cope with that planned movement |
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What does feedback mean? |
-Cerebellum adjusts motor commands for output based on what actually is happening |
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What does the vestibulocerebellum/Archicerebellum include and what is its function? |
-Flocculus, nodule -Concerned with equilibrium -Connection to the vestibular system |
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What does the paleocerebellum/spinocerebellum include and what is its function? |
-Anterior hemispheres plus some vermis
-Concerned with propulsive, stereotyped movements |
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What does the neocerebellum/cerebrocerebellum include and what is its function? |
-Posterior hemispheres -Concerned with co-ordination of fine movements |
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What are the 3 cortical layers of cerebellum? |
-Molecular layer - few neurons (axons of granule cells/dendrites of Purkinje's) -Purkinje cells - single row of huge cells (unique to cerebellum) -Granular layer - numerous densely packed neurons |
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What are the two major input fibres to the cerebellar cortex and what are their functions |
1. Mossy fibres: active at high rates and with mass effect drives Purkinje cells to fire 2. Climbing cells: active at low rates by very powerful albeit less frequent input causes large powerful spikes in the Purkinje fibres. Climbing vine on dendrite of Purkinje cell |
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What is a Purkinje cell? |
is a sole source of output with the cerebellar cortex |
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Does the purkinje cell have a excitatory or inhibitory effect onto the cerebellar nuclei? |
-Inhibitory |
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What is the general circuitry of the cerebellum? |
-Enter cerebellum via cerebellar peduncles -Cerebellar cortex -Deep cerebellar nuclei -efferent output to other areas of CNS (leave cerebellum via cerebellar peduncles |
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Does the cerebellum have a direct effect on lower motor neurons? |
no, effect is indirect. -Exerts effect by influencing output of motor centres |
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Is the cerebellum's effect ipsilateral or contralateral? |
-Ipsilateral |
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How does the cerebellum help eliminate error ? |
-the circuit operates to reduce error in the motor output by reducing the strength of synapses that were active when error occurred |
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Do lesions of the cerebellum result in impaired movement with reduced coordination and postural control without loss of sensation or muscle strength? |
-Yes |
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What are the causes of cerebellar dysfunction? |
-Stroke -Tumour -Degenerative disease -Trauma -Structural/malformation -Hereditary -Toxicity -Infection |
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What does ataxia mean? |
-Incoordination of movements without overt muscle weakness -Stereotypical gait disorders - wide based -Posture and balance impairments |
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What is intention (action) tremor? |
-Involuntary tremor as patient approaches closer to intended target |
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What is dyssynergia? |
-Impairment of multijoint movements - movements not properly sequenced, or of proper range of direction |
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What is dysdiadochokinesia (DDK)? |
Difficulty with rapidly alternating movements (deficit in coordination with agonist/antagonist) |
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What is dysmetria? |
-Impaired ability to properly scale movement (hyper or hypometric) |
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What is dysarthria? |
-Poorly articulated/coordinated speech |
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WHat is nystagmus ? |
rapid involuntary eye movements |
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What is the function of the vestibulocerebellum and what happens if there is a lesion to this area? |
-Balance and eye movements -Influence lower motor neurons to adjust muscle tone -Influence gaze centres LESION: disturbance of equilibrium, dizzy; eye concerns - may lead to imbalance and nystagmus, impaired vestibular ocular reflex |
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What is the function os the spinocerebellum what happens is there is a lesion to this area? |
-Ongoing execution of movement -Adjusts motor output in response to proprioceptive inputs -Alters muscle tone during ongoing movt/initiation/planning and timing of movement LESION: hypotonia, gait ataxia, wide based gait, falls |
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What is the function so the cerebrocerebellum and what happens if there is a lesion to this area? |
-Compares intended with actual movements, and modifies motor output accordingly LESION: disorders of voluntary movement (DDK, dysmetria, decomposition). Delay in initiating and terminating movements, intention tremor and terminal tremor, disorders of temporal coordination, disorders of spatial coordination of hand and finger muscles |
