CNS - Cerebellum

Question 1

What does cerebellum mean?

Answer 1

Little brain

Question 2

Where is the cerebellum?

Answer 2

Caudal to the forebrain - cerebral hemispheres
dorsal to medulla oblongata and the pons
sits above 4th ventricle, partially forming it’s roof

Question 3

What are the 3 lobes of the cerebellum?

Answer 3

Caudal, rostral, and Flocculonodular lobes

Question 4

What are the folds in the cerebellum called?

Answer 4

Folia (NOT SULCI(furrows) AND GYRI(ridges))

Question 5

What is the arbor vitae?

Answer 5

‘Tree’ shape formed by white matter (axons) within the cerebellum

Question 6

What is the function of the cerebellar peduncles?

Answer 6

Attaches the cerebellum to the rest of the brain.

Allows communication between cerebellum and the rest of the brain via white matter

Question 7

What is the function of the caudal peduncles?

Answer 7

afferent from vestibular nuclei (in the brain stem) and proprioceptors (via the spinocerebellar tract (ipsilateral - same side)

Question 8

What is the function of the middle peduncles?

Answer 8

afferent from motor cortex via pontine nuclei - what do i plan to do

Question 9

What is the function of the rostral peduncles?

Answer 9

mainly efferent to contralateral red nucleus (goes to motor neurones via here) and thalamus (goes back to cortex so perception of what is going on)

Question 10

Which two fibres communicate with both the cerebellar cortex and deep cerebellar nuclei

Answer 10

Mossy fibres from pontine motor nuclei

Climbing fibres from vestibular organs and proprioceptors

Question 11

How does the cerebellar cortex communicate with the deep cerebellar nuclei?

Answer 11

Purkinje Cell Axons. Signals from the cerebellar cortex are always inhibitory to deep cerebellar nuclei

Question 12

How do the deep cerebellar nuclei affect the UMN tracts?

Answer 12

The deep cerebellar nuclei are always excitatory to the upper motor neurone tracts

Question 13

What will happen if there is damage to the cerebellar cortex?

Answer 13

Exaggerated movement.
Constant excitatory stimulation.
No damping by cerebellar cortex via purkinje cell axons

Question 14

What is the function of the cerebellum?

Answer 14

Balance, coordination, and refinement of movement.
Compares input from motor planning centres with input from vestibular and proprioceptive organs.
Corrective signals sent back to motor planning centres via thalamus and directly to UMN nuclei

Question 15

How can the cerebellum be divided according to it’s functional anatomy?

Answer 15

Vestibulocerebellum - Flocculonodular lobe
Spinocerebellum - centre of cerebellum alongside and including the vermis
Cerebrocerebellum - cerebellar hemispheres

Question 16

What is the role, input, and output of the Vestibulocerebellum?

Answer 16

Balance and eye movement
Input = vestibular and visual
output to vestibular nuclei (vestibulospinal tract - vestibular nuclei has output to extraoccular muscle)

Question 17

What is the role, input, and output of the Spinocerebellum?

Answer 17

Muscle tone and movement/motor execution
Input = vestibular, visual, auditory, and proprioceptive
Output to UMN nuclei

Question 18

What is the role, input, and output of the Cerebrocerebellum?

Answer 18

Planning of limb movements/motor planning
Input = motor and somatosensory cortices
Output to motor cortex via the thalamus

Question 19

What is the lingula, and what is it’s function?

Answer 19

Small process on rostral portion of the cerebellum/vermis. It is concerned with tail movement. Animals with a large or prehensile tail have a pronounced lingula

Question 20

How does the cerebellum vary between species?

Answer 20

Animals with complex limb movements have larger cerebellar hemispheres (e.g. mammals)
Animals which rely on axial muscles and symmetrical limb movements have a well developed vermis.

Question 21

How does cerebellar development differ between species such as the horse and the dog?

Answer 21

Precocial animals such as horses have a well developed cerebellum at birth - need to be able to run with the herd immediately after birth.
Altricial animals such as cats or dogs have a poorly developed cerebellum at birth - kept safe in a den/burrow for some time after birth

Question 22

Give examples of symptoms of cerebellar dysfunction

Answer 22

Comparative motor adjustments are not made - results in ataxia = uncoordinated gait and poor balance
Often wide-based gait as animals try to maintain stance
Dysmetria is seen - under or over shooting target whilst moving
Swaying, falling to the side and nystagmus may be seen if vestibulocerebellum affected
Damage to the cerebellar cortex reduces UMN inhibition and can cause increased tone (spasticity) and hypermetria (a goose-stepping gait)
Intention tremor seen in deliberate movements e.g. reaching for a food bowl