Cerebellum Flashcards
What is the cerebellum important for?
Balance
Coordination
Refinement of movement
How does the cerebellum compare intended and actual movement?
Compares input from motor planning centres with vestibular and proprioceptive organs
If the cerebellum detects that actual movement was not the same as intended, what does it do?
Send corrective signals to motor planning centre
Via thalamus and directly to UMN nuclei
The cerebellum is good at refining simple movements. What do more complex movements require? Why?
Practice
To improve synapse efficiency
What may an animal with a damaged cerebellum look like?
Uncoordinated
Where is the cerebellum located? In relation to hemispheres, pons and medulla oblongata
Caudal to cerebral hemispheres
Dorsal to pons and medulla oblongata
What makes up the cerebellum?
Highly folded cortex of deep nuclei and grey matter
White matter in the cerebellum forms branching tracts. What are these called?
Arbor vitae (tree of life)
What do the arbor vitae consist of? Where do they synapse?
Purkinje cell axons
Synapse on deep cerebellar nuclei of grey matter
The cortex of the cerebellum is folded. What are these folds called?
Folia
What are the 3 lobes of the cerebellum called?
Rostral
Caudal
Flocculonodular
From a dorsal perspective, what is the cerebellum separated into?
2 hemispheres
Vermis in between hemispheres
What are the cerebellar peduncles? How many are there?
Stalks of white matter
Allow cerebellum to communicate with brain stem
3 on each side = 6
What are the names of the 3 pairs of the peduncles?
Caudal
Middle
Rostral peduncles
What fibres are in each pair of peduncles?
Caudal = afferent Middle = afferent Rostral = efferent
What are the 2 main sets of afferent axons in the cerebellum? (Fibres)
Mossy fibres
Climbing fibres
Where do mossy fibres get their input?
Motor cortex
Via nuclei in pons
Where do climbing fibres get their input?
Vestibular organs and proprioceptors
Are mossy fibres and climbing fibres excitatory or inhibitory?
Excitatory
Deep nuclei have excitatory output to the UMN tracts. What does this mean damage to the cerebellar cortex causes?
Excess motoractivity
What are the 3 sections of functional anatomy in the cerebellum?
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
Where is the vestibularcerebellum? What movements is it responsible for?
Flocculonodular lobe
Balance and eye
(Vestibular nuclei)
What is the function of the spinocerebellum?
Muscle tone and movement
Where is the cerebrocerebellum? What does it do?
Lateral part of cerebellar hemispheres
Planning of movements
Animals with complex limb movements have what adaptations to their cerebellum?
Large cerebellar hemispheres
Animals with symmetrical limb movements have what adaptations to their cerebellum?
Well developed vermis
Animals with a large tail have what adaptation tot heir cerebellum?
Large lingula
Where is the lingula?
Lobule at rostral end of cerebellum
Do altricial or precocial animals have a better developed cerebellum at birth? Why?
Precocial - need to be able to run with the herd
Why do altricial not have a well developed cerebellum? What is important to aid their cerebellar development?
In safe den for first few weeks of life
Playing improves synapse efficiency
What does cerebral dysfunction cause and why?
Ataxia = uncoordinated gait and balance
Due to motor adjustment not being made
Cerebral dysfunction can also cause wide based gaits (for balance) and dysmteria. What is dysmetria?
Hypo/hypermetria = over/undershooting when moving
What may be seen if the vestibulocerebellum is affected?
Swaying
What happens when there is damage to the cerebellar cortex?
Decreased inhibition of deep nuclei
Causes increased tone (spasticity) and hypermetria
What is an intention tremor?
Tremor when concentrating on deliberate movements e.g. reaching for food
Seen with cerebellar damage
Why do cats have larger cerebellar hemispheres than fish?
Cats have proper limbs - need more motor planning
What is the main function of the flocculonodular lobe?
Vestibular system
Vestibulocerebellum
What is car sickness caused by?
Vestibular and visual system mismatch
What signs might you expect in an animal with a lesion on the spinocerebellum cortex?
Exaggerated movement
Increased muscle tone
Hypermetria gait
Ataxia