1.57 Cerebellum

Question 1

What is the function of the folia?

Answer 1

Increase surface area

Question 2

What are the 2 cerebellar hemispheres involved in?

Answer 2

Involved in planning

Question 3

What is the function of the vermis?

Answer 3

Ongoing monitoring of movement - motor control of the trunk musculature and some extremities

Question 4

What si the function of the flocculonodular node?

Answer 4

involved in balance and vestibulo-occular reflexes

Question 5

What is the function of the intermediate cerebellum?

Answer 5

distal muscles of the extremities

Question 6

What is the function of the lateral part of the cerebellum?

Answer 6

motor planning of extremities

Question 7

What part of the cerebellum projects into the dentate nucleus?

Answer 7

Lateral Hemisphere

Question 8

Where do pathways from the vermis project into?

Answer 8

festigal nucleus

Question 9

Which nuclei does flucconudlar nodule project into?

Answer 9

the vestibular nucleus

Question 10

What is the interposed nuclei made up of?

Answer 10

the embiloform and globose nuclei

Question 11

So what are the four deep cerebellar nuclei?

Answer 11

Dentate, emboliform, globose and fastigal

Question 12

Wha gives rise to climbing fibres?

Answer 12

fibres from the Inferior olivary nucleus to the cerebellum

Question 13

What do other afferent fibres terminate as?

Answer 13

Mossy fibres

Question 14

Which part of the cerebellum is related to the vestibulocerebellum pathway?

Answer 14

Flocculo-nodular lobe + part vermis

Question 15

Explain the vestibulocerebellum…

Answer 15

Inferior peduncle
Project onto the flocculo-nodular lobe
Input from vestibular nucleus, DSCT
Output to vestibular nuclei

Question 16

What is the function of the vestibulocerebellum?

Answer 16

Posture and balance

Question 17

Which part of the cerebellum is related to the spinocerebellar pathway?

Answer 17

vermis + fastigial nucleus + Intermediate part of hemisphere + globose, emboliform nuclei

Question 18

Explain the spinocerebellar pathway…

Answer 18

Motor cortex
Double decussation of the ASCT, enters through superioir peduncle, and no decussation of PSCT, enters through inferior peduncle
Pontine nuclei synapse
Fastigal and Globose nuclei
Red nucleus
Info back to thalamus and cortex and output to body
Olive - send fibres into the same bit of cerebellum - info of proprioception

Question 19

What is the function of the spinocerebellar pathway?

Answer 19

Updating ongoing movements

Question 20

Which part of the cerebellum is involved in the cerebrocerebellar pathway (neocerebellum)?

Answer 20

lateral part of hemisphere + dentate nucleus

Question 21

Explain the cerebrocellebelar pathway…

Answer 21

From non motor, planning cortex - frontal lobe etc
Input from posterior parietal cortex, inferior olivary nucleus
Synpases in the pons
The pontine nuclei send fibres across the pons to enter the contralateral cerebellum through the middle cerebellar peduncle
Dentate Nucleus
Output to premotor cortex, supplementary motor area via thalamus

Question 22

What is the function of the neocerebellum pathway?

Answer 22

Initiation and planning of movements, motor learning

Question 23

what are the inputs and outputs of the inferior olivary nuclei?

Answer 23

Inputs from all cortical regions and spinal cord

Outputs as climbing fibres to opposite cerebellum (through inferior cerebellar peduncle)

Question 24

How are purknje fibres arranged?

Answer 24

Flat - 1 plane

Question 25

Where are the purkinje fibres arranged?

Answer 25

These cells line up all long the folia - 2 inputs - mossy fibres (from everything except the olive).

Question 26

Explain the granule cell layer…

Answer 26

high density of cellular nuclei
deep to this layer is the white matter of the cerebellum, which contains axons ascending to the cortex as well as axobs (parallel fibres) descending from the cortex to the deep cerebellar nuclei. The axons from granule layer run across the foli and throught the dendritic cells - each one would contains thousands of purkinje cells

Question 27

Explain the climbing fibres…

Answer 27

each ends on one purkinje cell - 1:1 - purkinje layers info from pontine, largely planning, from inf. Olive they climb the dendritic tree - info from proprioception - excitatory

Question 28

What is the parkunje cells output onto the deep cerebellar nuclei?

Answer 28

Inhibitory

Question 29

When can deep cerebellar nuclei be excitatory or inhibitory?

Answer 29

Thalamus - excitatory

Olive - inhibitory

Question 30

How do parkunje fibres regulate the target nuclei?

Answer 30

when the parkunje fibres are activated, they can both inhibit or excite the target nuclei

Question 31

Explain simple learning - conditioned eye blink…

Answer 31

Excitation E.g. a puff of air arrives at cerebellum via V cranial
Excitation - sound - arrives via inferior olive climbing fibres
Coincidence on Purkinje cell results in enhanced inhibition of deep cerebellar nucleus
Enhanced inhibition of deep cerebellar nucleus removes Inhibition from red nucleus and permits eye blink in response to sound
Learning takes place on the Purkinje cells

Question 32

Projections of vestibulocerebellum pathway….

Answer 32

Fluccolonodular lobe + part of vermis
Fastigal nucleus
Reticular formation - reticulospinal tract
Lateral vestibular nucleus - vestibulospinal tract
Balance and control movements

Question 33

Projections of the spinocerebellum pathway…

Answer 33

Paravermal region
Emboliform and globose nuclei
Brain stem nuclei + red nuclei - axial and proximal muscles and distal limb muscles
Contralteral thalamus - control discharge of cortical neurones and planning movement and initiation

Question 34

Projections of the corticocerebellum pathway…

Answer 34

Cerebellar hemisphere
Dentate nucleus
Contraleteral thalamus - control discharge of cortical neurones and planning and movement initiation

Question 35

Why can cerebellar disease occur?

Answer 35

alcohol misuse, toxicity, genetic disorders or traumatic experiences

Question 36

What is a common symptoms?

Answer 36

Wide gait and difficulties balancing

Question 37

Which pathway would a midline lesion affect?

Answer 37

Vestibulocerebellar

Question 38

What would a lesion in the vestibulocerebellum pathway result in?

Answer 38

○ Typically occurs bilaterally
○ Staggering gait (ipsilateral – falling to affected side)
Nystagmus on lateral gaze (contralateral)

Question 39

What would a lesion in the spinocerebellum pathway result in?

Answer 39

Ataxia - uncoordinated movement - characterised by unsteady gait and uncoordinated limb movement
Smooth movement of limbs and coordination - touch nose then touch finger
Decomposition of movements (intention/action tremor))
Tremor of movement - not during rest

Question 40

What would a lesion in the corticospinal pathway result in?

Answer 40

Slow movement onset
Speech impairment (scanning/tremulous) - pauses between syllables’
Dysmetria -refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia.
Dysdiadochokinesis - often abbreviated as DDK, is the medical term for an impaired ability to perform rapid, alternating movements (i.e. diadochokinesia).
e.g Move head rapidly from one side to the other
Rebound phenomena is the emergence or re-emergence of symptoms that were either absent or controlled while taking a medication, but appear when that same medication is discontinued, or reduced in dosage.
Intention/action tremor
Nystagmus