Cerebellum Flashcards
Where is the cerebellum located
Posterior cranial fossa
Does the cerebellum cross the midline
Yes
What is the vermis
The part that lies along the midline
What divides the vermis and the lateral cerebellum into anterior and posterior lobe
Primary fissure
What branches mainly provide the cerebellum
Superior cerebellar artery
AICA
PICA
What is the most common site of infarct in the posterior circulation
PICA
What forms the roof of the 4th ventricle
Nodulus
medial part of flocculonodular lobe
Describe the outer molecular layer of the cerebellum
Pale with mostly axons and only a few cells
Describe the middle layer of the cerebellum
Single row of purkinje cells
Describe the inner layer of the cerebellum
Granule layer
Thick and contains granule cells
Describe the dendritic field of purkinje cells
Dendritic field extends into molecular layer- fields are flat and lie across axis
What drives granule cells in the granule layer
Afferents from the cerebellum
Where do granule cell axons project to
What do they synapse with
Molecular layer
Purkinje cells
Where do purkinje cell axons project to
Deep nuclei of the cerebellum
What 2 things do mossy fibres activate in cerebellar circuitry
Granule cells
Deep nuclear cells
What do granule cells form and what is the result of this
Form parallel fibres that activate purkinje cells
Are purkinje cells excitatory or inhibitory
Inhibitory
What do purkinje cells inhibit and why
Deep nuclear cells
To modify their response to mossy fibre input
What kind of ‘loop’ in basic cerebellar circuitry
Feed forward inhibition loop
What are climbing fibres
Separate input system only into purkinje cells
Modify synapses between parallel fibres and purkinje cells
Input and output to cerebellum are via the…
Cerebellar peduncles
Does the superior cerebellar peduncle have input or output fibre,s or both?
From/ to where are fibres
Output only
Mainly to VL thalamus
Does the middle cerebellar peduncle have input or output fibres or both?
From/ to where are the fibres
Input coming from contralateral cerebral cortex and cranial nerves pia pons
Does the inferior cerebellar peduncle have input or output fibres or both?
From/ to where are the fibres
Input from spinal cord via dorsal and ventral spinocerebellar tracts
Is the dorsal spinocerebellar tract ipsilateral or contralateral
Ipsilateral
What does the dorsal spinocerebellar tract carry information from
Proprioceptors
Is the ventral spinocereberllar tract contralateral or ipsilateral
Contralateral
What information is carried by the ventral spinocerebellar tract
State of reflexes in spinal cord
Describe the crossings of the ventral spinocerebellar tract
Contralateral in spinal cord
Recrosses in braintem to end up on same side
Where do the deep cerebellar nuclei lie
White matter below the cortex
The outputs from which nuclei are the only output of the cerebellum
Deep cerebellar nuclei
Name the deep cerebellar nuclei from medial to lateral
Fastigial n
Glubose n
Emboliform n
Dendate n
Which 2 nuclei are also known as the interposed nuclei
Glubose and emboliform
What areas of the brain connect to the dendate nuclei
Cerebellar hemisphere and lateral part of anterior lobe
What deep cerebellar nuclei processes data from the vermis and medial parts of hemispheres
Fastigial and interposed nuclei
What does the flocculo-nodular lobe connect to
Lateral vestibular nuclei on pons
Name the 3 ‘functional’ zones of the cerebellum
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
What makes up the vestibulocerebellum
Flocconodular lobe and associated deep nuclein
What makes up the spinocerebellum
Vermis
Cortex- just lateral to vermis
Associated deep nuclei
What makes up the cerebrocerebellum
Lateral parts of cerebellar hemispheres (both anterior and posterior lobes)
What are the functions of the vestibulocerebellum
Coordinates head and eye movements to ensure stability of gaze
How does the vestibulocerebellum control balance of head on the body
Via the medial vestibulospinal tract
How does the vestibulocerebellum control balance of the body on the ground
Lateral vestibulospinal tract
Where are the motor commands to the neck and eye muscles sent
Via the medial longitudinal fasciculus and its caudal extension (medial vestibulospinal tract)
Where do motor commands to the legs travel
Via lateral vestibulospinal tract
Where are motor programmes for tasks to do with vestibulocerebellum stored
Flocculo-nodular lobe
What is the function of the spinocerebellum
Controls locomotion and limb coordination
Where does the spinocerebellum receive input from
Spinocerebellar tracts
Where does the spinocerebellum tract send its commands down
Vestibulospinal and reticulospinal tracts
What is the function of the cerebrocerebellum
Coordinates movements initiated by the motor cortex
Speech, voluntary movement of hands and arms and hand eye coordination
How are flocculonodular syndromes characterised
Poor balance
Disordered eye movements (nystagmus, ocular dysmetria and poor visual persuit)
What is truncus ataxia
Syndrome where a person is unable to sit on their bed without steadying themself
Common cause in young children to have flocculonodular syndrome
Medulloblastoma
Do people with flucculonodular lesions fall on side or opposite side to the lesion
On the same side
What characterises spinocerebellar syndrome
Ataxia
Hypotonia
Tendon reflex changes
What is ataxia
Loss of balance and coordination while walking
Patients experiencing ataxia as if intoxicated
What is hypotonia
Generalised muscle weakness and fatigue
In which group of people is spinocerebellar syndrome often seen
Chronic alcoholics due to lack of vit b
What is neocerebellar syndrome
Damage to cerebellar hemispheres
Name 7 symptoms of neocerebellar syndromes
Loss of hand eye co-ordination Dysmetria Dysdiadochokinesis Intention tremor Dysarthria
What is dysmetria
Inaccurate reaching out with intention tremor
What is dysdiadochokinesis
Irregular performance of rapid alternating movement
What is dysarthria
Slurred speech due to loss of coordination of muscles
What are the causes of neocerebellar syndrome
Stroke
Tumour
Trauma
Degenerative diseases
Why is it thought that alcohol intolerance mimims features of cerebellar damage
GABA-ergic inhibitory interneurones
Purkinje cells are GABA-ergic
