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Neuro > Functional Anatomy Of The Cerebellum > Flashcards

Functional Anatomy Of The Cerebellum Flashcards

1
Q

The cerebellum functions as a …

A

Rapid, corrective feedback loop smoothing and coordinating movements

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2
Q

The motor plan leaves…

A

The cortex (intended movement) and goes to the basal nuclei and cerebellum (actual movement)

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3
Q

The cerebellum overvie w

A

Programmes ballistic movements - precise timing and appropriate patterns of skeletal muscle contraction
Compares intended and actual movement
Corrects ongoing movement
Activity occurs subconsciously
Motor learning patterns shift from the conscious to unconscious

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4
Q

Information from:

A

Somatosensory
Visual, auditory, vestibular, proprioceptive

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5
Q

Describe the anatomy of the cerebellum

A

Situated in post cranial fossa and covered superiorly by the tentorium cerebellum
Located dorsal to the pons and medulla
Accounts for 11% of the brain mass
Two cerebellar hemispheres L&R joined medially by the vermis
Internal white matter - arbor vitae
External grey matter folia - transversely arranged gyri
Each hemisphere divided in to 3 lobes by primary and posterolateral fissures

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6
Q

What are the 3 lobes of the cerebellum

A

Anterior
Posterior
Flocculonodular

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7
Q

A tier and posterior lobes are dived further into…

A

Zones
Vernal Zoe - occupies the vermis
Intermediate (paravermal) zone - lies on each side of the vermis, occupying the medial regions of the cerebellar hemispheres
Lateral zone - lies lateral to the intermediate zone

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8
Q

What are the cerebellar peduncles

A

Three paired fibre tracts connect the cerebellum to the brainstem
Superior - connect cerebellum -> midbrain
Middle - connect cerebellum -> post and to the axis of the brainstem
Inferior - connect cerebellum -> medulla

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9
Q

Describe the superior peduncles

A

To the midbrain
Fibres originate from neurons in the deep cerebellar nuclei and communicates with the motor cortex via the midbrain and the Diencephalon (thalamus)

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10
Q

Describe the middle peduncles

A

To the pons
Cerebellum receives info advising it of voluntary motor activities initiated by motor cortex

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11
Q

Describe the inferior peduncles

A

To the medulla
Afferent conveying sensory info from muscle proprioceptors thorughout the body and from the vestibular nuclei of the brainstem (medulla oblongata)

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12
Q

What are the 3 major function divisions of the cerebellum

A

Vestibulocerebellum - composed of the flocculonodular lobe
Spinocerebellum - composed of th vermis and paravermal zone
Cerebrocerebellum - composed of the lateral zones of the cerebellar hemispheres

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13
Q

Anterior lobe is responsible for …

A

The regulation of muscle tone, coordination of skilled voluntary movement

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14
Q

Posterior lobe is responsible for…

A

Planning and initiation of voluntary activity

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15
Q

Flocculomodular lobe is responsible for

A

Maintenance of balance, control of eye movement

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16
Q

What are the spinocerebellar tracts

A

Posterior (dorsal) - enters cerebellum via inf cerebellar peduncle
Anterior (ventral) - enters cerebellum via the superior cerebellar peduncle
Cuneoerebellar tract - enters cerebellum via inf cerebellar peduncle

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17
Q

Describe the inferior olivary nuclei

A

Receives info from cutaneous Afferents, joint afferents and muscle spindles and from here axons pass to the contralateral cerebellar Cortex via the inferior cerebellar peduncle
Wil also receive axons from the sensorimotor cortex directly and indirectly via the red nucleus

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18
Q

Describe the deep pontine nuclei

A

Primary route by which the cerebral cortex communicates with the cerebellum via the basilar pons

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19
Q

Describe the reticular formation

A

Regulates spinal reflexes - provides a key input to the cerebellum that relates to the manner in which reticular neurons regular extensor motor tone at any given time
Several of the nuclei within this receive input from the sensorimotor cortex serving as a relay for cerebral cortical inputs to the cerebellum

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20
Q

Describe the Tectum

A

Cerebellum also receives fibres arising from the sup. And inf. colliculi of the Tectum to provide visual and auditory information respectively
Do so by projecting to the pontine nuclei, which in turn go through the ,idle cerebellar peduncle to the cerebellar cortex

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21
Q

Describe the red nucleus

A

Serves as a relay from the sensorimotor cortex to the spinal cord via the rubrospinal tract
In a similar manner the sensorimotor cortex can provide signals to the cerebellar cortex via the red nucleus

22
Q

Describe the trigeminal system

A

Secondary proprioceptive fibres associated itch muscle spindle activity of the face and jaw reach the cerebellum through the mesencephalic trigeminal nucleus

23
Q

Describe the vestibular system

A

Via the ICP to the flocculonodular lobe

24
Q

What fibres does the middle cerebellar peduncle carry

A

Only afferent fibres

25
Q

Where do inputs go?

A

Deep cerebellar nuclei

26
Q

What are the deep cerebellar nuclei?

A

Separated from the cerebellar cortex by the white tater are underlying, deep, cerebellar nuclei whic are represented bi laterally. Moving laterally to medially:
Dentate nucleus
Emboliform
Globose
Fastigal
(Don’t Eat Greasy Food)

27
Q

Dentate nuclei

A

Project contralaterally though the superior cerebellar peduncle to neurons in the contralateral thalamus and from thalamus to motor cortex
Function: influence planning and initiation of voluntary movement

28
Q

Emboliform and Globose nuclei

A

Project mainly to the contralateral red nuclei and a small group is projected to the motor cortex
Function: Red nuclei -> rubrospinal tract control of proximal limb muscles

29
Q

Fastigial nuclei

A

Project to the vestibular nuclei and to the pontine and medullary reticular formation
Function: vestibulospinal and reticulospinal tracts

30
Q

Overview of cerebellar output/efferent

A

Cerebellar cortex ->deep nuclei _
->thalamus -> cerebral cortex
-> vestibular nuceli
-> inferior olive
-> red nucleus

31
Q

Cerebellar cytoarchitecture

A

Each folium - cortex and deep white matter (projections of Purkinje cell fibres to deep cerebellar nuclei)
3 layered cortex

32
Q

What are the 3 layers of the cortex

A

Molecular
Purkinje
Granule

33
Q

Describe the granular cell layer

A

Granule cells are abundant within this layer
Contains 3-5 dendrites arranged in a claw like appearance
Receive mossy fibre afferents.
Axons travel to the molecular layer where they branch in a T junction to form the parallel fibres.
Golgi cells are also found in the granular layer and their processes radiate to all other cell layers. They are inhibitory GABA-ergic interneurons and their cell body is usually located close to the Purkinje cell layer. Golgi cells synapse with granule cells and mossy fibres.

34
Q

Describe the Purkinje cell layer

A

Is one cell thick and contains the Purkinje cell
The Purkinje neuron is the largest cell in the cerebellar cortex.
Dendrites emerge from its neck and thick dendritic trees are directed into the molecular layer
They receive excitatory input from granule cells via parallel fibres and climbing fibres.
The axons of the Purkinje terminate in one of the deep cerebellar nuclei.
Purkinje cells located in the vermal region project to the fastigial nucleus,
Purkinje cells located in the hemispheres project to the dentate nucleus
Purkinje cells located in the paravermal region project to the interposed nuclei.
Purkinje cells are inhibitory

35
Q

Describe the molecular cell layer

A

contains the dendrites of Purkinje cells, parallel fibres (axons of granule cells) and two other cell types, basket and stellate cells.
Basket and stellate cells are inhibitory GABA-ergic cells that synapse with Purkinje cells.
Receive input from parallel and climbing fibres.

36
Q

What are mossy fibres

A

All cerebral afferents originating from all sources except the inferior olivary nuclear complex
Include afferents from the spinal cord, posterior column nuclei, trigeminal system, pontine ad vestibular nuclei
Synapse with Golgi cells and granule cell dendrites
Are excitatory fibres that utilise glutamate as their NT

37
Q

Describe climbing fibres

A

Arise from the inf olivary nucleus and ascend thorugh the granular and Purkinje cell layers to reach the molecular layer
Each individual fibre forms and excitatory synapse with one Purkinje cell
This one to one relationship is key in motor learning
Climbing fibres are excitatory and use aspartate as their NT

38
Q

Both mossy and climbing fibres…

A

Excite their target neurons in the cerebellar cortex but also provide excitatory collaterals to the deep cerebellar nuclei

39
Q

How does micro-cuitry work? Climbing fibres…

A

Excite the purkinje cells

40
Q

How does micro-cuitry work? Mossy fibres…

A

Excite the granule cells

41
Q

How does micro-cuitry work? Granule cells….

A

Make excitatory contact with the purkinje cells

42
Q

How does micro-cuitry work? Purkinje cells

A

Tonic inhibition on the activity of the neurons of the cerebellar nuclei
-> all excitatory inputs converted to he inhibition
-> removing the excitatory influence of the cerebellar inputs (erasing)

43
Q

All output from the cerebellar cortex is through the …… which is ……. Yet the output as a whole is….

A

Purkinje cell which is inhibitory to the deep cerebellar nuclei yet the output from the cerebellum as a whole is excitatory

44
Q

Climbing fibres and mossy fibres send….. which results in……

A

Send collaterals to the deep cerebellar nuclei which results in immediate activation of the cerebellar nuceli

45
Q

Activation of deep cerebellar nuclei is followed by

A

Inhibiton mediated by the Purkinje cell

46
Q

Purkinje cell activation is mediated by the action of the …

A

Golgi cells on the parallel fibres

47
Q

Excitation of the purkinje cell by the parallel fibres is …

A

Short

48
Q

When the excitation of the ……… ceases there is an increase in
deep cerebellar nuclei excitation

A

Purkinje cell

49
Q

Release of inhibition known as

A

Disinhibition

50
Q

Signals transmitted to the deep cerebellar nuclei to its target neurons in the brain stem/thalamus after mossy or climbing fibres consists of….

A

Initial activation then inhibition followed by disinhibition

51
Q

This pattern of discharge becomes the

A

Coded message transmitted from the cerebellum to its distal targets

Neuro (26 decks)

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