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50 Cards in this Set
- Front
- Back
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What are the three sections of the cerebellum?
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Midline vermis Paravermal Hemisphere Lateral Hemisphere |
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What sections of the cerebellum are anatomically arranged? |
Vermis and anterior lobe |
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Where do the sections of the cerebellum transmit information? |
Vermis and paravermis (spino/vestibulocerebellum) to spinal cord Lateral lobe (cerebrocerebellum) to cortex |
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Describe the cerebellum |
Little brain Input exceeds output Large role in motor control and learning |
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How does the cerebellum coordinate movement? |
By comparing actual motor output with intended movement and then adjusting accordingly Uses both feedforward and feedback mechanisms |
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What are the general functions of the cerebellum |
Motor Plan - which muscles should be moving and how Position sense - Compares intended movement with actual movements, smooths movements and improves accuracy Feedback - Messages back to motor cortex to adjust movements |
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What are the functions of the different sections of the cerebellum? |
Vestibulocerebellum - Equilibrium --Allows for smooth eye movements, coordinates responses to balance reactions Spinocerebellum - Gross limb movements --Coordinates postural and automatic adjustments Cerebrocerebellum - Fine Distal Movements --Coordinates voluntary fine motor movements in distal extremities --Planning of movements, timing |
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What are mossy and climbing fibers? |
Afferent information carried on mossy or climbing fibers Mossy - set moment to moment firing rate of purkinje cells Climbing - Cause purkinje cells to fire only a few complex action potential per second ---too slow to convey ongoing information |
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What are the two types of tracts in the cerebellum? |
Internal Feedback Tracts --Receives information about movement commands before it reaches the muscles Spinocerebellar Tracts --Monitors response of muscles to commands --Unconscious and automatic adjustments to movements and posture |
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What are the Internal Feedback Tracks |
Rostrospinocerebellar Tract Anterior Spinocerebellar Tract |
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Describe the Rostospinocerebellar tract |
IFT Trasmits information from cervical SC to ispilateral cerebellum Enters cerebellum via superior cerebellar peduncles |
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Describe the Anterior Spinocerebellar Tract |
Information from the T/L SC with cell bodies in lateral and ventral horns Axons cross and ascend in contralateral Ant SpinoCerebellar Tract to midbrain Enter cerebellum via superior cerebellar peduncles Most recross midline before entering cerebellum |
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Lesion in the Anterior SpinoCerebellar Tract |
Loss of information on what the contralateral side is doing Loss of movement on ipsilateral side. |
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What are the High Fidelity (Somatotopic) Pathways |
Cuneocerebellar Tract - arms and upper body Posterior Spinocerebellar tract - Legs and lower body |
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Describe the Cuneocerebellar Tract |
Primary Afferents from dorsal column to lower medulla Synapse in lateral cuneate nucleus Second-order neurons from cuneocerebellar tract Enter ips inferior cerebellar peduncle --> cerebellar cortex |
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Describe the posterior spinocerebellar tract |
Primary afferents in dorsal column to thoracic or upper lumbar SC Synapse in dorsal gray matter Second order neuron forms tract Remains ipsilateral to cerebellar cortex |
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Input to the Cerebellum |
Cerebral cortex Vestibular apparatus Vestibular and auditory nuclei Spinal Cord Descending motor tracks |
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Output to the cerebellum |
Vestibulospinal Reticulospinal Rubrospinal Corticobrainstem Corticospinal |
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Function of the Medial Zone/Flocculonodular Lobe |
Controls ongoing movement - modulation of efferent activity -- Vestibular neurons are more active during stance - inc extensor muscle activity -- Reticular neurons are more active during swing - inc flexor activity |
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What was learned from animals studies on lesions in the medial/floccuolnodular lobe |
-Abnormal upright posture -Poor sitting and standing balance -Impaired righting response -Backward falls and toward side of lesion -Difficulty walking --Abnormal limb timing ----Ips limb flexion and adduction ----Contra limb extension and abduction ----Dec Stride Length |
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Function of the intermediate zone lesions |
Possible fq modulation to regulate the rate and magnitude of muscle activity during locomotion ---Greatest activity occurs during the t ranistion between ipsilateral stance and swing phases Controls relative timing, amplitude and trajectory of limb movements especially when precision is req |
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What was learned from animals studies on lesions in the Intermediate zone |
-No impairment of upright posture and balance during standing or walking -Abnormal timing in navigating treadmill or ladder --Ips limb - inc swing with hypermetria, dec stance --Contra limb - Dec swing, increased stance |
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What is the function of the lateral zone? |
Modulating motor cortical activity during visually guided locomotion Less important for level walking Important in making adjustments - precise limb placement and when visual guidance is req |
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What was learned from animals studies on lesions in the lateral zone |
Misplacement of ipsilateral limbs when beam walking Inc errors in response to behaviorally relevant visual cues |
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Describe effects of anterior lobe lesions |
-Inc AP sway (high velocity, low amp) -Hypermetric Postural responses --Overshooting, larger torque responses, prolonged muscle activity -Postural tremor -Inc intersegmental movements of head, trunk, and legs |
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Describe effects of vestibulocerebellar lobe lesions |
Omnidirectional sway (low feq, high amplitude) No inc intersegmental movemnts |
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Describe effects of Neocerebellar (lateral) lesions |
Slight postural instability indistinguishable from controls |
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Balance deficits with cerebellar lesions |
-Cerebellar gait ataxia -Reduced joint excursions -Inc stride to stride variability in joint angles -Decomp between ankle and knee joints -Reduced walking speed |
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Intersegmental coordination deficits |
-No gait ataxia -Leg kinematics indistinguishablefrom control subjects on level surface, decomposition effect will increase withincline or need for precision -Leg hypermetria has not been examined as contributor to gait ataxia |
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What contributes more to cerebellar gait ataxia during uninterrupted level walking? |
Balance deficits contribute more than visually guided leg control deficits |
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What was learned from the studies on cerebellar lesions and motor learning? |
1) Cerebellar subjects were unable to learn to use predictive feedfoward during expected perturbations 2) Cerebellar subjects can adjust speed to match the treadmill but use different strategies than healthy subjects 3) Cerebellarsubjects demonstrate reduced amplitudes of after-rotation; diminished capacityto store novel orientation (walking straight after spinning) 4) Cerebellar patients do not improve to the same extent or rate to alterations in visual input. |
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How does the cerebellum influence the pattern of gait |
-Generates the pattern of reciprocal flexor/extensor muscle activity -Contributes to modulation of timing rate and force of muscle activity controlling pattern -Maintains intersegmental and interlimb coordination |
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How is equillibrium/posture effected with a cerebellar lesion? |
Impaired sitting, standing, and walking balance Abnormal postural tone Frequent falling during locomotion Gait ataxia |
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How can cerebellar dysfunction affect adaptability |
Difficulty making short term adjustments based on external sensory feedback Making more complex motor adaptations based on trial and error practce |
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Describe laterality in the cerebellum |
Cerebellar efferents to descending tracts remain ipsilateral Cortical projections from cerebellum go cont ralateral cerebral cortex and red nucleus |
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Describe Ataxia |
Common to all lesions of the cerebellum --Uncordinated voluntary movement --Normal Strength --Jerky --Inaccurate Not caused by spasticity or contracture |
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What are the types of ataxia |
Truncal - Flocculonodular lobe Gait and Limb ataxia - paravermal lesions Hand ataxia - Lateral cerebellar lesions |
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Describe the ataxia differential |
Impaired -Somatosensation -Proprioception -Vibration sense -Ankle reflexes |
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Vestibulocerebellar symptoms |
Nystagmus Dysequilibrium - cannot maintain upright balance Difficulty maintaining sitting and standing balance (truncal ataxia) |
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Paravermal and CerebrocerebellarSymptoms |
Dysarthria Spinocerebellum Ataxic gait Chronic alcoholism damages the anterior lobe of the spinocerebellum |
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Spinocerebellar symptoms |
Ataxic gait Limb Ataxia –Dysdiadochokinesia –Dysmetria –Actiontremor Compensation with decomposition of movement |
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Describe spinocerebellar action tremor |
-Onsetand offset of muscle activity are delayed –Agonistburst is prolonged; onset of antagonist breaking is delayed -Resultsin overshooting target -Ascorrection is attempted, repeated overshoot |
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Cerebellar symptoms |
Impaired fine motor coordination of finger movements Impaired ability to -Play musical instruments -Fasten buttons -Type on a keyboard |
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TIM VaDeTuCoNe |
Trauma Inflammation Metabolic Vascular Degenerative Tumor Congenital Neurogenic |
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What is Friedrichs Ataxia |
Degenerative neuromuscular disorder Autosomal Recessive -Limits production of frataxin, which is important in function of mitochondria; causes neuronal degeneration Onset between 10-15 |
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Symptoms of Friedrich Ataxia |
–Ataxiain arms and legs –Fatigueand weakness –Lossof sensation (vibration and position sense are lost early) –Aggressivescoliosis –Otherconsiderations ---Visionimpairment, hearing loss, slurred speech ---Diabetesmellitus ---Hypertrophiccardiomyopathy and arrhythmias ---Nointellectual effects |
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Prognosis for Friedrich Ataxia |
Loss of ambulation 5 - 15 years after onset Avg lifespan 30-40 years after Dx Cardiac disease and diabetes greatest risk |
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What is Ataxia - Telangiectasia |
-Multisystemdisorder characterized by -progressive neurologic impairment -Autosomal recessive - affects DNA resistance to stress -Predominately cerebellar form of spinocerebellar degeneration -Delayed onset of incomplete pubertal development; early menopause |
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Symptoms of Ataxia - Telangiectasia |
–Relentlesslyprogressive –Ataxiais notable early –Oculomotorapraxia –Dysarthria,drooling –Involuntarymovements –Signsof spinocerebellar degeneration with loss of DTRs and spinal muscle atrophy –Othersymptoms •Weakensthe immune system •Vulnerableto infections, malignancies •Telangiectasia– blood vessels over sclera and on sun-exposed areas of skin •Diabetes •Chroniclung disease |
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Prognosis for Ataxia - telangiectasia |
–Inabilityto walk by 10 or 11 years old –Difficultyswallowing, poor nutrition, poor weight gain –Lifeexpectancy highly variable; approximately 25 years after diagnosis –Mostcommon causes of death are lung disease and cancer |
