Motor Modulation - Cerebellum

Question 1

loss of coordination will produce what?

Answer 1

ataxia

Question 2

what are the functions of the cerebellum?

Answer 2

• coordination of timing between muscle groups to produce fluid movements
• ongoing adjustments of posture and balance
• correcting or avoiding movement errors
• motor learning

Question 3

when are cerebellar circuits active?

Answer 3

before a movement or while a movement is going on

Question 4

the cerebellum has two hemispheres connected by what?

Answer 4

vermis

Question 5

what are the three lobes of the cerebellum?

Answer 5

• anterior lobe
• posterior lobe
• flocculonodular lobe

Question 6

what are the white matter tracts of the cerebellum?

Answer 6

• middle cerebellar peduncles
• superior cerebellar peduncles
• inferior cerebellar peduncles

Question 7

where is the grey matter located in the cerebellum?

Answer 7

• on the external cerebellar cortex arranged in long parallel folds called folia
• in the white matter as deep nuclei

Question 8

what are the four deep nuclei of the cerebellum?

Answer 8

• dentate
• emboliform
• globose
• fastigial

*emboliform and globose are know collectively as “interposed nuclei”

Question 9

what fibers do the white matter tracts contain?

Answer 9

• inferior: both incoming and outgoing
• middle: only incoming
• superior: both incoming and outgoing

Question 10

what are the three main arteries that feed the cerebellum?

Answer 10

• superior cerebellar
• anterior inferior cerebellar
• posterior inferior cerebellar

Question 11

what does the superior cerebellar artery branch from and what does it supply?

Answer 11

• branches from rostral basilar artery
• supplies the superior portion of the cerebellum, deep cerebellar nuclei and superior cerebellar peduncle

Question 12

what does the anterior inferior cerebellar artery branch from and what does it supply?

Answer 12

• branches from the caudal basilar artery
• supplies the anterior strip of the cerebellum including superior vermis and middle cerebellar peduncle

Question 13

what does the posterior inferior cerebellar artery branch from and what does it supply?

Answer 13

• branches from the vertebral artery
• supplies the inferior cerebellum including the nodulus

Question 14

what is the location of the spinocerebellum and what is its nuclei?

Answer 14

• vermis and paravermis
• interposed nuclei and fastigial nuclei

Question 15

what is the location of the cerebrocerebellum and what is its nuclei?

Answer 15

• lateral hemispheres
• dentate nuclei

Question 16

what is the location of the vestibulocerebellum and what is its nuclei?

Answer 16

• flocculonodular lobe
• fastigial nucleus

Question 17

what does the spinocerebellum function in?

Answer 17

error correction: detects difference between motor plan and actual movement

Question 18

where does the spinocerebellum receive projections from?

Answer 18

• proprioceptors (muscle spindles/golgi tendons)
• inferior olive

Question 19

cortical neurons of the spinocerebellum synapse with the dorsal column nucleus and output to what two motor tracts?

Answer 19

• UMN of the medial motor tracts (vestibular nuclei and reticular formation)
• UMN of lateral corticospinal tract via the ventral lateral nucleus of the thalamus

Question 20

what does the vermis coordinate movements for?

Answer 20

central body

Question 21

what does the paravermis coordinate movement for?

Answer 21

distal muscles

Question 22

cerebellar lesions restricted to the medial cerebellum have what effects?

Answer 22

• bilateral loss of coordination of proximal muscles effecting balance posture and gait

Question 23

what is located in the medial cerebellum?

Answer 23

vermis and or fastigial nucleus

Question 24

cerebellar lesion in the lateral/intermediate zone can have what effect?

Answer 24

ipsilateral movement deficits
- loss of coordination (appendicular ataxia)
- inaccuracy in range and direction of movement (dysmetria)
- trouble with patterned movement (dysdiadochokinesia)

Question 25

what does the vestibulocerebellum function in?

Answer 25

- corrections in stability and balance (continuous and anticipatory) - vestibular ocular reflex and smooth pursuit

Question 26

where does the vestibulocerebellum receive projections from?

Answer 26

- vestibular nuclei and vestibular ganglia - inferior olivary nucleus

Question 27

where does the vestibulocerebellum output to?

Answer 27

- vestibular nuclei - reticular formation ' - bypasses the DCN

Question 28

what does the cerebrocerebellum function in?

Answer 28

- motor learning - calculating movement trajectories

Question 29

where does the cerebrocerebellum receive projections from?

Answer 29

- neurons in the base of the pons (pontine nuclei) - inferior olivary nucleus

Question 30

where does the cerebrocerebellum output to?

Answer 30

UMNs of lateral movement pathways vis the ventral posterior lateral nucleus of the thalamus

Question 31

where do the incoming fibers synapse in the cerebellum?

Answer 31

- on neurons of the deep cerebellar nuclei - on neurons called purkinje cells in the cerebral cortex

Question 32

what do the deep cerebellar nuclei control?

Answer 32

- excitatory input that stimulates these neurons to fire - error correction signals out to the CNS (deep excitatory loop)

Question 33

what do the Purkinje Fibers provide?

Answer 33

modularly inhibition to the deep cerebellar nucleus to adjust the outgoing signal

Question 34

where do mossy fibers originate from?

Answer 34

spinal cord, pontine nuclei and vestibular nuclei

Question 35

where do mossy fibers synpase?

Answer 35

on the deep cerebellar nucleus or on granule cells of the cortex

Question 36

what happens if a mossy fiber synapses with a granular cell?

Answer 36

granule cells send axons towards Purkinje cell dendrites and the axons then bifurcate into a T shape called a parallel fiber

Question 37

axons from the inferior olive enter the cerebellum as what fibers?

Answer 37

climbing