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Neuroscience Unit 1 > Cerebellum > Flashcards

Cerebellum Flashcards

1
Q

What are the three general functions of the cerebellum?

A
  1. Coordinates all movements
  2. Maintains equilibrium, along with the vestibular system
  3. Maintains muscle tone by acting on reticular centers
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2
Q

What is meant by synergy in movement?

A

Muscles contract smoothly, in precise spatial and temporal sequences.

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3
Q

What is muscle tone defines as?

A

A state of partial contractility of muscles prior to onset of actual contractions

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4
Q

What are folia?

A

Longitudinal surfaces ridges on the hemispheres / vermis of the cerebellum

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5
Q

What is arbor vitae?

A

Deep inside the foliae, called the tree of life. It’s the organization of white matter inside

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6
Q

What are the deep cerebellar nuclei from medial to lateral?

A

Fastigial, globose, emboliform, and dentate

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7
Q

What are the three layers of gray matter in the cortex of the cerebellum? Which projects axons?

A

From pia surface to deepest part (arbor vitae)

  1. Molecular layer
  2. Purkinje cell layer - projects axons
  3. Granule cell layers
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8
Q

What do the axons of purkinje cells do?

A

Project to the deep cerebellar nuclei and mediate GABA inhibition onto deep nuclei cells (i.e. fastigial nucleus)

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9
Q

Where do axons of the deep nuclei cells go and do in general?

A

They leave the cerebellum and mediate excitation of motor targets in brainstem, i.e. red nucleus of midbrain and Ventral Lateral nucleus of thalamus.

Works via neurotransmitter glutamate.

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10
Q

What happens in the superior cerebellar peduncle?

A

Attaches the cerebellum to midbrain, comprised of efferent fibers FROM the cerebellum. Fibers cross in the caudal midbrain.

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11
Q

What is in the middle cerebellar penducle?

A

Composed of afferent fibers to cerebellum from the pons. It is 100% cross fibers from the contralateral deep pontine nuclei

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12
Q

What is in the inferior cerebellar peduncle? What is it also called?

A

Also called the restiform body, it communicates in the medulla level and is composed of afferent fibers to the cerebellum from the dorsal spinocerebellar, cuneocerebellar, and olivocerebellar tracts.

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13
Q

What is the juxtarestiform body?

A

Fibers between the superior and inferior cerebellar peduncles which connect the vestibulocerebellum with the vestibular nuclear complex. Can be seen at caudal pons level.

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14
Q

What are the three anatomical lobes of the cerebellum, and what subdivides them?

A
  1. Flocculonodular
  2. Anterior
  3. Posterior

Subdivided by primary and posterolateral fissues.

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15
Q

What is the oldest and middle functional zone of the cerebellum and what is it in? What does it do?

A

Vestibulocerebellum - consists of flocculus, nodule, uvula, anterior vermis, and fastigial nucleus. Maintains equilibrium via extensor muscles, especially around the trunk via LVST and MVST. Also called vermis zone.

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16
Q

What is contained in the spinocerebellum? What is its function?

A

Paravermis of anterior and posterior lobes, vermis of posterior lobe, globose and emboliform nuclei.

Functions to coordinate trunk + proximal limb flexor muscles through the red nucleus + rubrospinal tract. Cordinates with spinal cord.

17
Q

What is the lateral zone also called? What is in it and what is it’s function?

A

Neocerebellum, includes lateral anterior and posterior lobes + dentate nucleus. Coordinates with VL thalamus nucleus + motor cerebral cortex for skilled movements of digital / appendicular muscles.

18
Q

What signals are sent thru the dorsal spinocerebellar tract (DSCT) and cuneocerebellar tract(CCT)?

A

Unconscious proprioceptive impulses from infrafusal fibers + Golgi tendon organs.

19
Q

What is the path for DSCT afferent?

A
  1. Peripheral processes in intrafusal fibers + GTO from trunk and lower limb muscles, cell body in DRG. Central process enter into fasciculus gracilis.
  2. Central processes synapse on dorsal nucleus of Clarke from C8-L2 levels.
  3. Cell bodies in Clarke Nucleus send axons through DSCT in ipsilateral lateral funiculus, starting from L1 and going all the way up to C1.
  4. Axons enter inferior cerebellar peduncle, giving off collaterals to globose + emboliform nuclei. They terminate in spinocerebellum.
20
Q

What is the path for CCT afferent?

A
  1. Peripheral processes in intrafusal fibers + GTO from upper limb and neck muscles, cell body in DRG. Central process enter into fasciculus cuneatus.
  2. Central processes synapse on accessory cuneate nucleus of caudal and mid medulla levels.
  3. Cell bodies in accessory cuneate nucleus send axons through CCT from ipsilateral caudal medulla near the nucleus.
  4. Axons enter inferior cerebellar peduncle, giving off collaterals to globose + emboliform nuclei. They terminate in spinocerebellum.
21
Q

What does the pontocerebellar tract do?

A

Link the activities of the cerebral cortex with the cerebellum to help with skilled movements of appendicular appendages

22
Q

What is the course of the pontocerebellar tract?

A

Signal from cortex links to basilar / deep pontine nuclei. Axons from deep pontine nuclei send axons to contralateral middle cerebellar peduncle to communicate with the neocerebellum + dentate nucleus.

23
Q

What is the function of the olivocerebellar tract?

A

Consolidates motor skills that require trial + error, creating memory of our motor skills.

24
Q

What is the course of the olivocerebellar tract?

A

Originates in inferior olivary nucleus, receiving information from cortex. Axons pass to contralateral side and enter cerebellum through the inferior cerebellar peduncle. Tract synpases and gives collaterals to the spinocerebellum + neocerebellum, including globose, emboliform, and dentate nuclei.

25
Q

What deep cerebellar nuclei generally send axons for cerebellar efferents to the SCP? What are all their targets?

A

Globose, emboliform, and dentate nuclei.

Targets include: VL nucleus of thalamus, red nucleus of rostral midbrain, + descending fibers to reticular formation, basilar pons, and inferior olivary nucleus.

26
Q

What travels in the cerebello-rubrothalamic tract and what are its targets?

A

Glutamate releasing neurons which travel through SCP to contralateral side.

To red nucleus: globose, emboliform
To VL nucleus of thalamus: dentate

27
Q

What excites the neurons for the cerebello-rubrothalamic tract?

A

Purkinje cells from layer 2 which release GABA to stop release of glutamate from the deep cerebellar nuclei.

28
Q

What does the VL nucleus communicate with to do?

A

Projects to primary motor cortex (Brodmann’s area 4)

29
Q

What is the function of the cerebelloreticular fibers? What is the input of this system?

A

Control of muscle tone through the reticular formation.

All deep cerebellar nuclei cross SCP and terminate on reticular centers of pons and medulla.

30
Q

What do reticular centers do?

A

Send descending fibers called reticulospinal tracts to spinal motor neurons which control muscle tone.

31
Q

What is vestibulocerebellar syndrome and what usually causes it?

A

Damage to vermis / flocculonodular lobe usually caused by medullablastoma in children.

Signs: Trunkal ataxia (can’t maintain upright posture), rotational nystagmus.

32
Q

What is spinocerebellar syndrome and what usually causes it?

A

Lesions or atrophy of anterior lobe vermis / paravermis. Commonly caused by B1 deficiency in chronic alcoholism.

Symptoms: Locomotor ataxia, hypotonia, dysmetria (overshoot / undershoot in finger test, lack of coordination), abnormal heel-to-shin test

33
Q

What is neocerebellar syndrome and what usually causes it?

A

Tumors in lateral hemispheres which impinge on deep nuclei, or lesions of SCP (will be ipsilateral if caudal to decussation, since fibers recross via PT).

Symptoms: locomotor ataxia, hypotonia, dysdiadochokinesia, and dysarthria

34
Q

What is dysdiadochokinesia?

A

Inability to perform rapid, alternating movements

“bad, succeeding, movement”

35
Q

What is dysarthria?

A

Scanning or slurred speech. Arthria means joint or articulation, but they use articulation to mean how you pronounce words.

Neuroscience Unit 1 (20 decks)

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