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ANAT242 2022 Module 1 > Lecture 8 - Cerebellum > Flashcards

Lecture 8 - Cerebellum Flashcards

1
Q

What is the reticular formation composed of?

A

Composed of clusters of gray matter scattered throughout midbrain, pons and medulla

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2
Q

What is the reticular formation involved in?

A

Habituation

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3
Q

What is habituation?

A

a process in which the brain learns to ignore repetitive, inconsequential stimuli while remaining sensitive to others

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4
Q

What is the reticular formation inhibited by?

A

by sleep centres located in the hypothalamus & other brain regions

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5
Q

What is the reticular formation depressed by?

A

depressed by alcohol, sleep-inducing drugs & tranquilisers

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6
Q

What does brainstem injury of reticular formation cause?

A

permanent unconsciousness
(irreversible coma)

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7
Q

What does the reticular formation govern?

A

The arousal of the brain via thalamus

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8
Q

Where is the cerebellum located?

A

posterior cranial fossa

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9
Q

What is the cerebellum posterior to?

A

Superior and inferior medullary velum
Brainstem
4th Ventricle
Cerebellar peduncles

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10
Q

What does the cerebellum consist of?

A

cortex, white matter and deep nuclei

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11
Q

What is the cerebellum primarily concerned with?

A

synchronised, precisely timed movement across multiple joints = synergistic multi-joint limb movement

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12
Q

What does the cerebellum recieve?

A

receives vast amount of sensory information, but does not give rise to conscious sensory perceptions

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13
Q

What % of neurons in the brain does the cerebellum contain?

A

50%

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14
Q

What does the cerebellum have more of, afferent or efferent?

A

40x more afferents than efferents

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15
Q

What informs the cerebellum of intent to start voluntary muscle contractions?

A

Frontal motor association areas (eg. premotor cortex) via the corticopontine-cerebellar tract

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16
Q

What does the cerebellum recieve information for?

A

Proprioceptors throughout body
Visual input
Vestibular (balance) input

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17
Q

What does the proprioceptive information to cerebellum include?

A

Tension in muscles and tendons and the position of joints

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18
Q

What does proprioceptive information allow the cerebellum to do?

A

Allows the cerebellum to evaluate body position and momentum = where the body is and where it intends to go

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19
Q

What is the role of the cerebellar cortex and deep cerebellar nuclei?

A

The cerebellar cortex and the deep cerebellar nuclei calculate the best way to coordinate the force of each muscle contraction to prevent overshoot, maintain posture & ensure smooth coordinated movement.

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20
Q

What does the cerebellum dispatch to the motor cerebral cortex?

A

Blueprint for coordinating movement

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21
Q

What does the primary motor cortex influence?

A

The primary motor cortex then influences motor neurons in the spinal cord to produce movement

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22
Q

What is the effect of cerebellar lesion?

A

A patient with a cerebellar lesion is usually capable of carrying out general outlines of movement, but each movement is executed with suboptimal coordination and precision.

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23
Q

What does the cerebellum need to be connected to to achieve function?

A

Cerebellum needs to be connected to the motor input from cerebral cortex, the various sensory inputs and needs to send its output or blueprint back to the cerebral cortex.

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24
Q

What are the right and left hemispheres of cerebellum connected by?

A

Vermis

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25
Q

What are folia?

A

Parallel surface folds of cerebellum made of grey matter

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26
Q

What is the regional anatomy of the cerebellum?

A

Grey matter (cortex)
White matter (arbor vitae) - tree of life
Deep nuclei

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27
Q

What are the two main inputs of the cerebellar circuits?

A

mossy fibers/axons
climbing fibers/axons

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28
Q

Where are the climbing fibers/axons from?

A

mainly from inf. olivary nucleus = proprioceptive input. One ION neuron to 1 PC

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29
Q

Where are the mossy fibers/axons from?

A

from spinal cord or brainstem neurons

30
Q

What do the mossy fibers/axons convey?

A

conveying motor or sensory input

31
Q

What do the climbing fibers/axons convey?

A

Proprioceptive input

32
Q

What do the climbing axons form?

A

Climbing axons form excitatory synapses directly with the Purkinje neurons/cells (PC) in the cerebellar cortex

33
Q

What do the mossy axons form?

A

Mossy axons form excitatory synapses with granule neurons in the cerebellar cortex.

34
Q

What does the granule neurons send their axon as?

A

The granule neurons send their axon as a “parallel fibre” to form excitatory synapses with the Purkinje neurons

35
Q

What is the sole output neuron of the cerebellar cortex?

A

Purkinje neuron

36
Q

What type of neuron is the Purkinje neuron in the cerebellar circuit?

A

Inhibitory

37
Q

What does the Purkinje neuron work with/do?

A

Works with input axons to regulate the firing frequency and amplitude of the neurons in the deep cerebellar nuclei = “blueprint” sent to motor cortex

38
Q

What do neurons in cerebellar deep nuclei integrate?

A

Synaptic input

39
Q

What is the structure of Purkinje cells?

A

Oval-shaped cell body
Elaborate flattened, fanlike dendrite tree (sagittal section)

40
Q

Where does the Flocculonodular lobe lie deep to?

A

Vermis

41
Q

What surface is the Flocculonodular lobe on?

A

Inferior surface of cerebellum

42
Q

What do the anterior and posterior lobes of cerebellum do?

A

Co-ordinate movement

43
Q

What is the FNL?

A

Flocculonodular lobe

44
Q

What is the role of the Flocculonodular lobe?

A

Balance

45
Q

What is on the superior surface of the cerebellum?

A

Anterior lobe
vermis
Posterior lobe
folia
FNL

46
Q

What are the zones on the superior surface of the cerebellum? and what do they correspond with?

A

Lateral to medial
Lateral zone
Intermediate zone
Vermis (median zone)

Corresponding to sagittal functional subdivisions

47
Q

What is the deep cerebellar nuclei composed of?

A

Fastigial
Interposed/interpositus nucleus:
- Globose
- Emboliform
Dentate

48
Q

What does the Vermis (median zone) project to?

A

Vermis (median zone) projects to the fastigial nucleus

49
Q

What does the Intermediate zone in deep cerebellar nuclei project to?

A

Intermediate zone projects to the interposed/interpositus nucleus

50
Q

What does the Lateral zone in deep cerebellar nuclei project to?

A

Lateral zone projects to the dentate nucleus

51
Q

What are the functional divisions of the cerebellum?

A

three sagittal functional regions, with the flocculonodular lobe being a 4th non-sagittal functional region

52
Q

What are the spinocerebellum divisions?

A

Vermis
Intermediate zone

53
Q

What is the cerebrocerebellum division?

A

Lateral zones

54
Q

What is the vestibulocerebellum division?

A

Flocculonodular lobe

55
Q

What is the overall function of the cerebrocerebellar circuits?

A

controls multijointed movements of limbs

56
Q

What is the function of the spinocerebellar intermediate zone circuits?

A

controls accuracy of movement of the limbs.
eg. precision at a joint

57
Q

What is the function of the spinocerebellar medial/median/vermal zone circuit?

A

Controls posture via influencing axial muscles in trunk

58
Q

What is the function of the vestibulocerebellar circuits?

A

maintain balance via axial and limb muscles

59
Q

What does the inferior cerebellar peduncle convey?

A

Sensory information to the cerebellum
From muscle proprioceptors throughout the body
From the vestibular nuclei of the brainstem (equilibrium & balance)

60
Q

What axons does the inferior cerebellar peduncle contain?

A

Contains both afferent (chiefly) & efferent axons

61
Q

What axons does the middle cerebellar peduncle contain?

A

Contains only afferent axons (crossed axons from contralateral pontine nuclei). Eg CPCT

62
Q

What does the superior cerebellar peduncle connect?

A

The cerebellum to the midbrain

63
Q

What is the superior cerebellar peduncle formed by?

A

Formed by axons that arise from deep cerebellar nuclei (main efferent pathway)

64
Q

Describe the fibres of the superior cerebellar peduncle

A

Fibres decussate at various levels
Crossed fibres ascend - either terminate in the red nucleus or continue rostrally to end within the thalamus (then to cerebral motor cortex)

65
Q

What does each cerebellar hemisphere primarily exert its influence on?

A

Each cerebellar hemisphere exerts its influence primarily on the ipsilateral half of the body

66
Q

What happens when there is cerebellar dysfunction?

A

Loss of co-ordination of muscle activity

67
Q

What is ataxia?

A

Inaccuracy in the speed, force and distance of movement (staggering gait, dysmetria, slurred speech)

68
Q

What is tremor?

A

Involuntary oscillation of the limbs or trunk

69
Q

What is nystagmus?

A

rhythmic involuntary oscillation of the eyes

70
Q

What is often the 1st symptom of cerebellar tumour?

A

Headaches and vomiting
Due to blockage of CSF drainage from 4th ventricle

ANAT242 2022 Module 1 (7 decks)

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