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PBL SEM 3 > 7 - cerebellum and control of movement > Flashcards

7 - cerebellum and control of movement Flashcards

1
Q

what do LMN do and where are they?

A
  • in spinal cord and brainstem
  • innervate skeletal muscle for movement
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2
Q

where are UMN and what do they do?

A
  • cerebral cortex ad brainstem
  • control LMN
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3
Q

what does the cerebellum do?

A

coordinates movement

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4
Q

what does the basal ganglia do?

A

chooses appropriate movements

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5
Q

what do alpha motor neurons do?

A

innervate extrafusal muscle fibres

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6
Q

what do gamma motor neurons do?

A
  • innervate intrafusal muscle fibres (stretch receptors in parallel with muscle fibres)
  • control sensitivity of stretch reflex
  • increase sensitivity to externally imposed stretch
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7
Q

what causes LMN lesions and what do they cause?

A
  • paralysis
  • loss of tendon reflex
  • hypotonia, wasting, fasciculations
  • motor neurone disease, polio, peripheral nerve injury
  • symptoms are ipsilateral to location of lesion
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8
Q

what influence alpha and gamma motor neurones via descending tracts?

A

brainstem nuclei — vestibular, reticular, red nuclei

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9
Q

what pathways come from the vestibular, reticular and red nuclei and what do they control?

A
  • vestibulospinal
  • reticulospinal
  • rubrospinal

control reflexes, tone and posture

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10
Q

overall what do brainstem nuclei excite and what are they inhibited by?

A
  • excited by gamma motor neurones
  • inhibited by cerebral cortical efferent
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11
Q

what UMNs come from the cortex?

A

corticospinal (pyramidal) and corticobulbar tracts

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12
Q

what do corticospinal and corticobulbar tracts do?

A
  • innervate motor neuronal groups of spinal cord and brainstem, respectively
  • control fine, skilled movements
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13
Q

another name for skilled movements?

A

fractionated movements (highly controlled by cortical effernt fibres)

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14
Q

where is the decussation of the pyramids?

A

medulla oblongata

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15
Q

what do the corticospinal and corticobulbar tracts travel throguh before their decussation?

A

internal capsule

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16
Q

UMN lesions are commonly caused by what?

A

stroke in internal capsule

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17
Q

symptoms of UMN lesions

A
  • paralysis and +ve Babinski reflex
  • hypertonia and hyperreflexia
  • contralateral symtpoms to lesion location
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18
Q

what is paralysis and positive babinski reflex due to?

A

corticospinal tract damage

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19
Q

what are hypertonia and hyperreflexia due to?

A

loss of cortical inhibition of brainstem nuclei — increased sensitivity of stretch reflex

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20
Q

what are paralysis, hyperreflexia and hypertonia referred to as?

A

spasticity

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21
Q
A
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22
Q

what does the cerebellum do?

A
  • coordinates balance and movement
  • concerned with which muscles need to be activated to achieve a particular movement. timing, force
  • integrates info from the cerebral cortex (what movement is intended) (via pons) and peripheral sense organs (what is going on)
  • sends output to brainstem nuclei and cerebral cortex (via thalamus)
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23
Q

where is the cerebellum?

A
  • in posterior fossa
  • under occipital lobe
  • 4th ventricle is underneath
  • dorsal to pons and rostral part of medulla
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24
Q

how is the cerebellum attached to the brainstem?

A

CEREBELLAR PEDUNCLES

  • superior cerebellar peduncle to midbrain
  • middle cerebellar peduncle (largest) to pons
  • inferior cerebellar peduncle to medulla
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25
Q

what is embedded in the white matter of the cerebellum?

A

deep cerebellar nuclei

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26
Q

what is the largest nucleus and what is it important in?

A

dentate nucleus — important in output

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27
Q

what are the functional divisions of the cerebellum?

A
  • archicerebellum
  • paleocerebellum
  • neocerebellum
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28
Q

what is the oldest functional division in terms of phylogeny?

A

archicerebellum

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29
Q

which division is connected to vestibular system?

A

archicerebellum

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30
Q

what is the paleocerebellum particularly connected with?

A

spinocerebellar tracts

afferent to cerebellum from periphery

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31
Q

what is the neocerebellum particularly connected to via a relay in the pons?

A

cerebral cortex

32
Q
A
33
Q

which nuclei are the different divisions related to?

A

neo - dentate
paleo - emboliform and globose
archi - fastigial

34
Q

where does the cerebellar cortex project?

A

cerebellar nuclei

35
Q

what provides input to the cerebellum?

A
  • spinocerebellar tracts (from spinal cord)
  • vestibular nuclei (of brainstem)
  • cerebral cortex (via pontine nuclei)
36
Q

what are the spinocerebellar tracts lateral to in the brainstem?

A

trigeminal sensory nucleus

37
Q

label this section at the level of the decussation of the pyramids

A
38
Q

where are the vestibular nuclei?

A

in the medulla medial to the inferior cerebellar peduncles

39
Q

label this medulla at the level of the inferior olivary nucleus

A
40
Q

pontine nuclei give rise to fibres which what?

A

cross to other side via middle cerebellar peduncle

41
Q

where are pontine nuclei?

A

lie in pontine tegmentum

42
Q

label this pons

A
43
Q

where does the output of the cerebellum from the deep cerebellar nuclei go?

A
  • brainstem (vestibular, reticular and red nuclei)
  • some bypass nuclei and go straight to VL thalamus
44
Q

where is the red nucleus?

A
  • in rostral part of midbrain at level of superior colliculus
  • in mesencephalic tegmentum
45
Q

what are the 3 histological layers of the cerebellar cortex?

A
  • an outer, fibre-rich, molecular layer
  • an intermediate Purkinje cell layer (unicellular layer)
  • an inner granular layer (granule cells)
46
Q

input to cerebellar cortex from spinocerebellar tracts comes in via what?

A

mossy fibres

47
Q

where do mossy fibres terminate?

A

granule cells

48
Q

output from Purkinje cells goes whee?

A

to cerebellar nuclei

49
Q

describe mossy fibres

A

branch to supply several folia and end in the granule layer, in synaptic contact with granule cells

50
Q

describe the dendrites of Purkinje cells

A

transverse by numerous parallel fibres from which they receive excitatory synaptic input

51
Q

fibres from where wrap around the dendrites of Purkinje cells? what are these fibres called?

A

climbing fibres from inferior olivary nucleus

52
Q

what is circled?

A

inferior olivary nucleus

53
Q

describe the input of the archicerebellum

A

input comes from vestibular nerve into vestibular nuclei and from there via the inferior peduncle into the cerebellar cortex

54
Q

where do the Purkinje cells of the archicerebellum project to?

A

fastigial nucelus

55
Q

where does the fastigial nucleus project?

A

to the vestibular nuclei and also to the reticular nuclei of the brainstem

both of these have connections to reticulospinal and vestibulospinal tracts

56
Q

what does the archicerebellum control?

A

posture in relation to the maintenance of equilibrium

57
Q

where do they dorsal and ventral spinocerebellar tracts enter?

A

dorsal — inferior peduncle
ventral — superior peduncle

58
Q

where do the purkinje cells in the cerebellar cortex project to in the paleocerebellum?

A

globose and emboliform nuclei

59
Q

where do globose and emboliform nuclei project to (connections of paleocerebellum)?

A

throguh decussation of superior cerebellar peduncle to red nucelus in the midbrain (some fibres terminate here)

60
Q

what does the red nucelus give rise to?

A

rubrospinal tract

61
Q

where does the rubrospinal tract cross over?

A

ventral tegmental decussation

62
Q

the paleocerebellum receives fibres from _______ and projects to _______

A

fibres from spinocerebellar tracts and produces to red nucleus of midbrain

63
Q

what are the principle connections of the archicerebellum?

A

vestibular and reticular nuclei of brainstem

64
Q

which part of the cerebellum controls muscle tone and posture?

A

paleocerebellum

65
Q

describe the input to the neocerebellum

A

from cerebral cortex via pontine nuclei

fibres cross over after pontine nuclei and enter via the middle cerebellar peduncle and terminate in the cortex

66
Q

the cortex of the neocerebellum contains purkinje cells that project where?

A

to the dentate nucleus

67
Q

what do fibres of the dentate nucleus projects through?

A

superior peduncle (go through decussation of superior cerebellar peduncle)

68
Q

where do fibres from dentate nucleus go?

A

to VL nucleus of contralateral thalamus whcih then projects to ipsilateral cerebral cortex

69
Q

where does the cerebral cortex project to control muscle coordination (inc the trajectory and speed and force of movemtns)? (neocerebellum)

A

corticospinal tract

70
Q

what does a lesion in the midline or archicerebellum cause?

A

loss of postural control/balance

71
Q

what happens if there is a unilateral hemisphere lesion?

A

incoordination of arm (intention tremor) and leg causing unsteady gait. symptoms occur ipsilaterally

72
Q

how can an intention tremor be demonstrated clinically?

A

wobbling attempt at nose pointing test — very characteristic of a cerebellar hemisphere lesion

73
Q

what does a bilateral hemisphere cerebellar lesion cause?

A

slow, scanning speech (dysarthria), incoordination of limbs, staggering gait (when lower limbs affected) (ataxia)

74
Q

what is a typical sign of cerebellar dysfunction?

A

nystagmus

75
Q

what is ‘Charcot’s Neurological Triad’ and what is it highly diagnostic of?

A

nystagmus + scanning dysarthria + intention tremor = highly diagnostic of MS

PBL SEM 3 (49 decks)

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