Exam #6: Cerebellum Flashcards
Define dysmetria.
Errors in range and force of movement–causes “past-pointing”
Define hypermetria.
Voluntary muscular movement that over reaches intended target
Define ataxia.
Loss of muscular coordination due to errors in range, rate, force, and direction of movement
Define dysdiadicohokinesia.
Impaired rapid alternating movements
Define dysarthria.
Disorder in articulating speech
Define intention tremor/ action tremor.
Involuntary, oscillatory motion during a voluntary movement
Define nystagmus.
Involutnary oscillatory movements of the eye
Define hypotonia.
Diminished resistance to passive movement
Define synergy.
Movements are coordinated over to or more joints to make a smooth movement
Define asynergy.
Decomposition of complex movements
Define decomposition of movement.
Errors in the timing of complex multi-joint movements; instead, these are performed in sequence
Define pendular knee jerk.
Swinging back and forth of the leg on patellar tendon exam
Define titubation.
Tremor of the entire trunk or head during stance & gait
Define static tremor.
Tremor seen in patient with cerebellar lesion when holding limb up against gravity
Define rebound phenomenon/ lack of check.
Inability of the agonist and antagonist to adapt to rapid changes in load
What are the three functional divisions of the cerebellum? Draw and label a diagram of these functional divisions in horizontal section.
1) Spinocerebellum
2) Cerebrocerebellum
3) Vestibulocerebellum
What nuclei do the three functional divisions of the cerebellum synapse with?
1) Spinocerebellum= interposed & fastigial
2) Cerebrocerebellum= dentate
3) Vestibulocerebellum= vestibular
Where do the thee functional divisions of the cerebellum project after their nuclear synapses? What is the general function of these connections?
1) Spinocerebellum= UMN of the motor cortex
- Motor execution
2) Cerebrocerebellum= UMN of premotor cortex
- Motor planning
3) Vestibulocerebellum= LMN of the spinal cord
- Balance & equilibrium
What are the effects of a lesion to the vestibulocerebellum?
1) Ataxia
2) Cerebellar nystagmus
3) Deficits in smooth eye movements
*Patient will have a wide-based stance to compensate for balance disturbance
What are the effects of a lesion to the spinocerebellum?
1) Hypotonia
2) Dysmetria
3) Intention tremor
4) Pendular reflexes
What are the effects of a lesion to the cerebrocerebellum?
1) Delays in initiating and terminating movement
2) Problems with multi-joint movement (synergy)
3) Impairment of skilled sequences of movement e.g. speech & playing an instrument
Do lesions to the cerebellum cause ipsilateral or contralateral symptoms?
Cerebellar lesions cause IPSILATERAL symptoms
Which cell type is the source of axons leaving the cerebellar cortex?
Purkinje cells are the only cell type to project out of the cerebellum
**Purkinje cells are always INHIBITORY
Which cerebellar cortex cell makes excitatory synapses?
Granule Cell Layer
What is the difference between mossy fiber and climbing fiber input?
Mossy fibers= neurons from spinal cord/ brainstem to cerebellum
- Low-level excitation that must sum
- Causes Na+ dependent spikes
Climbing fibers= neurons from inferior olive of the brainstem to cerebellum
- Highly excitatory
- Causes Ca++ dependent spikes
*****Note that each climbing fiber contacts 1-10 purkinje cells
What is the effect of each type of input on the Purkinje cells?
Climbing fibers= excitation with enough force to cause spike in purkinje cell
Mossy= low level excitation that must sum for action potential in purkinje cell
Deficiency of which vitamin is associated with atrophy of the anterior lobe of the cerebellum?
Thiamine B1 deficiency
*****This is associated with chronic alcoholism
What is the association between MS & the cerebellum?
Cerebellar symptoms are commonly affected in patients with MS; specifically,
1) Cerebellum itself
2) Cerebellar peduncles
3) Afferent or efferent brainstem pathways associated with the cerebellum
What is Friedrich’s Ataxia?
Recessively inherited spinocerebellar ataxia
- Trinucloetide repeat expansion: GAA
- Chromosome 9
