Cerebellum Flashcards

1
Q

What is the cerebellum a component of?

A

Motor system

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2
Q

What are the major functions of the cerebellum

A

• Major functions – coordination of movement, motor planning, motor learning

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3
Q

How does the Cerebellum influence motor system?

A

Does not directly influence LMNs
Rather, indirectly influences UMN groups

• Damage results in movement disorders – problems with co-ordination of movement → ataxia

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4
Q

Damage on one side - eg. unilateral damage (stroke or tumour) would case ?

A

Unilateral damage (eg stroke, tumour) to cerebellum causes ipsilateral symptoms

The left cortex talks to the right cerebellum; But left cortex → right side of body

Compared to the basal ganglia in which unilateral damage will cause contralateral motor symptoms

There are also degenerative disorders of the cerebellum (slowly progressive, bilateral symptoms)

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5
Q

How does the cerebellum influence LMNS? Explain the pathway

A

Cerebellum -> thalamus -> cortex -> UMN (CST) -> LMN

OR cerebellum -> UMN - > LMN

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6
Q

Describe the principal cerebellar inputs (4)

A
  1. Cerebral cortex via pons (pontocerebellar fibers cross)
  2. Spinocerebellar (uncrossed or crossed twice) – proprioception from limbs
  3. Vestibulocerebellar (uncrossed, some crossed) – eyes, balance
  4. Inferior olivary nucleus (crossed)
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7
Q

What do the principal outputs allow the cerebellum to do?

A

Allows cerebellum to compare the motor plan (what we intent to do) with what the body is doing, makes adjustments (ongoing & repetitive movements)

Right side of cerebellum receives input concerned with the right side of the body

Cerebellum gets information on ongoing movement from the same side of the body

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8
Q

What are the major cerebellar outputs? (5)

A
  1. CC via the thalamus (crossed)
  2. Red nucleus (crossed) – to rubrospinal tract, —> upper limb flexors
  3. Reticular nuclei (bilateral) – control of voluntary movement
  4. Vestibular nuclei (bilateral) - CN III, IV & VI, vestibular nuclei
  5. Inferior olivary nucleus (crossed) - if lesion in inferior olivary nucleus it would seem like you have destroyed the cerebellum
  • ie. GENERALLY right cerebellum sends outputs to parts of the brain associated with control of the right side of the body
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9
Q

What does the reticular nuclei control?

A
  1. Reticular nuclei (bilateral) – control of voluntary movement
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10
Q

What does the Red nucleus control?

A
  1. Red nucleus (crossed) – to rubrospinal tract, —> upper limb flexors
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11
Q

What does the vestibular nuclei control?

A
  1. Vestibular nuclei (bilateral) - CN III, IV & VI, vestibular nuclei
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12
Q

What does the inferior olivary nucleus control?

A

life?

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13
Q

What is the anatomy of the cerebellum?

A

It is located in the posterior cranial fossa

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14
Q

What separates the cerebellum from the occipital and temporal lobes?

A

TENTORIUM CEREBELLI

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15
Q

What does the cerebellum form the roof of?

A

the fourth ventricle

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16
Q

What are the lobes of the cerebellum?

A

ANT
PoST
FLOCULONODULAR

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17
Q

Where is the tonsil located? What would happen if there was an expanding mass inthe cerebellum?

A

xpanding mash in cerebellum will push tonsil towards medulla & s/c
Tonsilar herniation through foramen magnum
This would compress the junction between the medulla & spinal cord
Interferes with CV & respiratory centres – can be fatal

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18
Q

What part of the body does the vermiz/medial zone deal with?

A

• Vermis/medial zone (trunk) → Deals with the medial part of the body

19
Q

Wht does the paravermis deal with?

A

PARAVERMIS = LIMBS

20
Q

What does the lateral hemisphere/vermis/lateral zone control?

A

MOTOR PLANNING

21
Q

What is the blood supply to the cerebellum?

All from a main artery- what?

A

VERTEBROBASILAR SYSTEM

  • superior cerebellar aa
  • AICA
  • PICA
22
Q

What inputs/outputs run through the SUPERIOR CEREBELLAR PEDUNCLE?

A

Midbrain, thalamus

23
Q

What inputs/outputs run through the MIDDLE CEREBELLAR PEDUNCLE?

A

Pons

24
Q

What inputs/outputs run through the INFERIOR CEREBELLAR PEDUNCLE?

A

Medulla, spinal cord

25
Q

Inferior Cerebellar peduncle has inputs from the SPINAL CORD and MEDULLA - expand major INPUTS

A
  1. Vestibular ganglia, nuclei (right next to it (above)) - movement
  2. Posterior spinocerebellar tract & cuneocerebellar tract, sensory nuclei of V (proprioceptive upper & lower limb etc)
  3. Inferior olivary nucleus (sends axons across the midline to ICP)
  4. Reticular formation- regulation of sleep wake cycles
26
Q

Inferior Cerebellar peduncle has inputs from the SPINAL CORD and MEDULLA - expand major OUTPUTS

A

o Vestibular nuclei (UMN of VST)
o Reticular nuclei (UMN to reticulospinal tracts)
o Inferior olivary nucleus

27
Q

The MIDDLE CEREBELLAR PEDUNCLE has only INPUT from PONS- expand

A

‘movement’

Inputs from pontine nuclei (pontocerebellar fibers), which receive input from cerebral cortex (corticopontine fibers)

Motor, premotor, supplementary motor area, and somatosensory cortex

Also association cortex, limbic cortex, other areas

28
Q

Superiior Cerebellar Peduncle gets info from MIDBRAIN AND THALAMUS- what are some o th INPUTS?

A

o Anterior spinocerebellar tract (crosses twice)

o Tectum

29
Q

Superiior Cerebellar Peduncle gets info from MIDBRAIN AND THALAMUS- what are some o th OUTPUTs?

A

Outputs

  1. Red nucleus – UMN (and loop amongst red nucleus, inferior olivary nucleus, back to cerebellum)
  2. VA/VL thalamus (same nuclei processing info from the basal ganglia), then to the cerebral cortex (motor areas including UMNs & elsewhere)
  3. Superior cerebellar peduncle decussates in caudal midbrain
30
Q

What are the layers of the cerebellar cortex?

A

Highly folded, three layers:

  1. Molecular basket, stellate- few neuro
  2. Purkinje
  3. Granular
31
Q

Where do the purkinje fibres project?

A

project to deep nuclei, only output neurons from cerebellar cortex

32
Q

What are the fibre types in the cerebellum?

A

CLIMBING from inferior olive, direct to purkinje. Climb directly up purkinje neurons/dendritic tree. Purkinje does main processing of info within the cerebellum

MOSSY all other input, to granule cells, which project to Purkinje neurons via parallel fibers

33
Q

What are the deep cerebellar nuclei? (3 kinds)

A

Dentate
Interposed - Emboliform &Globose
Fastigial

34
Q

Inputs into cerebellum go-

A
  • Inputs to cerebellar cortex & collateral fibers to deep nuclei
  • Purkinje neurons of cerebellar cortex project to deep cerebellar nuclei
  • Deep nuclei then project directly or indirectly to UMN systems
35
Q

eg. give me an example of input from the vestibular trunk (pathway)

A

Vestibular trunk —-> inferior cerebellar peduncle –> either FLOCCULONODULAR node or VERMIS –> FASTIGIAL -> ICP -> Vestibular & reticular nuclei

36
Q

eg. give me an example of input from the LIMB (pathway)

A

Limb -> ICP -> Medial hemispheres (paravermis) -> interposal nuclei - > RED NUCLUS (motor coordinaiton)

37
Q

eg. give me an example of input from the PONS from. cerebral cortex(pathway)

A

Pons -> MCP -> lateral hemisphere ->dentate nucleus -> SCP -> V/A VL thalamus -> cerenra; cortex

38
Q

What is within the VERMIS ?

What does the VERMIS do?

A

fastigial deep nucleus

Compares sensory input (spinocerebellar = proprioception; vestibular) with motor plan (cortico-ponto-cerebellar output)

Makes adjustments to UMN activity to smooth, co-ordinate ongoing & repetitive movements of trunk & proximal limbs

39
Q

What would damage to the vermis do?

A

affects trunk (axial) & proximal limb muscles

Problems with equilibrium/balance → truncal ataxia - stance & gait uncoordinated, wide-based gait, frequent falls

Hyporeflexia & hypotonia – don’t know why – but normal strength

40
Q

Which parts of the cerebellum are involved with movements of the eye?

A

Flocculonodular lobe

  • Smooth pursuit (tracking) eye movements
  • Cancelling or changing of the vestibuloocular reflex
  • So from flocculonodular lobe → vestibular nuclei → not only to vestibulospinal tracts, but they also hook into CN III, IV & VI nuclei for the control of eye movements

Part of vermis
- Coordination of saccades

41
Q

What is the ‘intermediate’ cerebellum?

A

Paravermis (medial hemisphere) – interposed deep nuclei

  • Compare sensory input with motor plan
  • Makes adjustments to UMN activity to smooth, coordinate ongoing & repetitive movements of limbs
42
Q

What would damage to the paravermis cause?

A

Damage – affects distal limb muscles, leading to appendicular ataxia
o Intension (action) tremor
o Dysmetria (inaccurate reaching), overshoot
o Decomposition of movement – poor timing & coordination of complex movements involving numerous muscles
o Dysdiadochokinesia – difficulty performing rapidly alternating movements (flipping hands)

43
Q

What is the Lateral Cerebellum- functions and damage?

A

• Lateral hemisphere, dentate deep nuclei
o Planning movements
o Improves performance on subsequent repeated movements, encodes programs of learned skilled movements
o Cognitive functions (connections with association cortex)

44
Q

What would damage to the lateral cerebellum cause?

A

o Delays in initiating movements (planning of movements)

o Problems with motor learning (procedural memory)