Exam #6: Cerebellum

Question 1

Define dysmetria.

Answer 1

Errors in range and force of movement–causes “past-pointing”

Question 2

Define hypermetria.

Answer 2

Voluntary muscular movement that over reaches intended target

Question 3

Define ataxia.

Answer 3

Loss of muscular coordination due to errors in range, rate, force, and direction of movement

Question 4

Define dysdiadicohokinesia.

Answer 4

Impaired rapid alternating movements

Question 5

Define dysarthria.

Answer 5

Disorder in articulating speech

Question 6

Define intention tremor/ action tremor.

Answer 6

Involuntary, oscillatory motion during a voluntary movement

Question 7

Define nystagmus.

Answer 7

Involutnary oscillatory movements of the eye

Question 8

Define hypotonia.

Answer 8

Diminished resistance to passive movement

Question 9

Define synergy.

Answer 9

Movements are coordinated over to or more joints to make a smooth movement

Question 10

Define asynergy.

Answer 10

Decomposition of complex movements

Question 11

Define decomposition of movement.

Answer 11

Errors in the timing of complex multi-joint movements; instead, these are performed in sequence

Question 12

Define pendular knee jerk.

Answer 12

Swinging back and forth of the leg on patellar tendon exam

Question 13

Define titubation.

Answer 13

Tremor of the entire trunk or head during stance & gait

Question 14

Define static tremor.

Answer 14

Tremor seen in patient with cerebellar lesion when holding limb up against gravity

Question 15

Define rebound phenomenon/ lack of check.

Answer 15

Inability of the agonist and antagonist to adapt to rapid changes in load

Question 16

What are the three functional divisions of the cerebellum? Draw and label a diagram of these functional divisions in horizontal section.

Answer 16

1) Spinocerebellum
2) Cerebrocerebellum
3) Vestibulocerebellum

Question 17

What nuclei do the three functional divisions of the cerebellum synapse with?

Answer 17

1) Spinocerebellum= interposed & fastigial
2) Cerebrocerebellum= dentate
3) Vestibulocerebellum= vestibular

Question 18

Where do the thee functional divisions of the cerebellum project after their nuclear synapses? What is the general function of these connections?

Answer 18

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

Question 19

What are the effects of a lesion to the vestibulocerebellum?

Answer 19

1) Ataxia
2) Cerebellar nystagmus
3) Deficits in smooth eye movements

*Patient will have a wide-based stance to compensate for balance disturbance

Question 20

What are the effects of a lesion to the spinocerebellum?

Answer 20

1) Hypotonia
2) Dysmetria
3) Intention tremor
4) Pendular reflexes

Question 21

What are the effects of a lesion to the cerebrocerebellum?

Answer 21

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

Question 22

Do lesions to the cerebellum cause ipsilateral or contralateral symptoms?

Answer 22

Cerebellar lesions cause IPSILATERAL symptoms

Question 23

Which cell type is the source of axons leaving the cerebellar cortex?

Answer 23

Purkinje cells are the only cell type to project out of the cerebellum

**Purkinje cells are always INHIBITORY

Question 24

Which cerebellar cortex cell makes excitatory synapses?

Answer 24

Granule Cell Layer

Question 25

What is the difference between mossy fiber and climbing fiber input?

Answer 25

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

Question 26

What is the effect of each type of input on the Purkinje cells?

Answer 26

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

Question 27

Deficiency of which vitamin is associated with atrophy of the anterior lobe of the cerebellum?

Answer 27

Thiamine B1 deficiency

*****This is associated with chronic alcoholism

Question 28

What is the association between MS & the cerebellum?

Answer 28

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

Question 29

What is Friedrich’s Ataxia?

Answer 29

Recessively inherited spinocerebellar ataxia

• Trinucloetide repeat expansion: GAA
• Chromosome 9