Cerebellum Flashcards
Where is the cerebellum found?
Posterior cranial fossa
What is the midline of the cerebellum called?
Vermis
What is the vermis divided into?
Anterior and posterior obe
Which lobe of the vermis is larger?
Posterior
Is the posterior lobe superior or inferior to the anterior lobe?
More inferior
What is the sulcus called between anterior and posterior lobe?
Primary fissure
What is the 3rd, smaller lobe called in the cerebellum?
Flocculonodular node
What is the flocculonodular node contain and responsible for?
Flocculus
Vestibulo-ocular reflex
What are inferior on the cerebellum?
cerebellar tonsils
If ICP raises, what happens to the cerebellar tonsils?
They herniate trhrough foramen magnum
What happens if cerebellum tonsils hernaite?
Compress upper spinal cord blood vessels and tracts
What is separate to the vermis?
Nodulus lobe
What does nodulus lobe do?
Helps form part of 4th ventricle
What mainly supples blood to cerebellum?
Posterior inferior and superior cerebellar arteries
What else supplies blood to cerebellum?
Branches of basilar artery
Which is the most common site of an infarct in posterior circulation
PICA
How many layers are there to the cerebellum?
3 layers
Describe the outer layer of the cerebellum
Pale with mostly axons and only a few cells
What does the middle layer have?
purkinje cells
What does the inner layer have
Granular layer with cell bodies
Where do all inputs and outputs to the cerebellum go through?
Cerebellar peduncles
What does the superior peduncle contain?
output fibres only
What does the middle peduncle contain?
Input fibres from contralateral cortex and cranial nerves via the pons
What does the inferior peduncle contain?
Input fibres from spinal cord via the dorsal and ventral spinocerebellar tracts
Where are all inputs and outputs routed through to get to the rest of the brain?
Deep cerebellar nuclei which lies in white matter
From medial to lateral, what are the deep cerebellar nuclei?
Fastigial, Globose, Emboliform and Dentate (FGED)
Which nuclei does the vermis connect to?
Fastigial
Which nuclei does the anterior lobe of the cerebellum connect to?
Interposed nuclei (globose + emboliform)
The hemispheres connect to which nuclei?
Dentate nuclei
Where does spinocerebellar tract originate?
Spinal cord
Where does spinocerebellar tract terminate?
Ipsilateral cerebellum
What does the spinocerebellar tract convey information about?
Length and tension of muscle fibres
What does spinocerebellar tract control?
Unconscious proprioceptive sensation
Is the dorsal tract ipsilateral or contralateral?
Wholly ipsilateral
Where does dorsal tract pass up?
Passes up brain stem
How does dorsal tract enter cerebellum?
Via inferior cerebellar peduncle
What does dorsal tract do?
Carry information from proprioceptors
Is ventral tract contralateral or ipsilateral?
Contralateral but recrosses brainstem to become ipsilateral
What does ventral tract do?
Carries information about state of reflexes and interneurones in the spinal cord
What are the 3 function zones in the cerebellum?
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
What is the function of the cerebellum?
Help motor cortex produce accurate and smooth movements
How does cerebellum do its function?
Modulating and refining motor cortex commands using feedback from proprioceptors and other sensory organs
What does cerebellar damage cause?
Overall clumsiness
abnormal fatigue
Instability of movement
Extraocular eye muscles are affected
What does cerebellar white matter have the property of?
neuronal plasticity
Damage to what causes persistance of disability
deep nuclei
What does the vestibulocerebellum operate via
flocculonodular lobe
What is connected to the vestibulocerebellum?
Vestibular nuclei
What does vestibullocerebellum do?
coordinates head and eye movements to ensure gaze stability
What does vestibulospinal tract do?
controls balance of head on body
What does lateral vestibular tract do?
Controls balance of whole body
Where is information sent from to the vestibular nuclei?
Medulla/ pons
Motor commands to neck and eye muscles are sent via what?
Medial longitudinal fasciculus
Medial vestibulospinal tract
Motor commands to the legs go via?
lateral vestibulospinal tract
Motor programs for tasks are stored where?
cortex of the flocculo-nodular lobe
What is the spinocerebellum comprised of?
anterior lobe and vermis
What does verims connects to
fastigial nucleus
What is the anterior lobe connected to?
interposed nuclei
What does the spinocerebellum control?
locomotion and limb coordination
What does the spinocerebellum send motor commands down?
lateral vestibulospinal
reticulospinal tracts
What is the cerebrocerebellum comprised of?
posterior lobe (cerebral hemispheres)
What is the cerebral hemispheres connected to?
dentate nucleus
What does the cerebrocerebellum do?
coordinates movement initiated by motor cortex
(speech, voluntary movements of hands/arms and hand eye coordination
What are the 3 major cerebellar syndromes?
Flocculonodular
Anterior lobe
Neocerebellar
What characterises flocculonodular syndrome?
Poor balance and disordered eye movements
What is a common cause of flocculonodular syndrome?
Medulloblastoma
Where does a medulloblastoma usually ordinate?
Wall of 4th ventricle
What is medulloblastoma a form of?
cranial primitive neuroectodermal tumour (PNET)
What is the anterior lobe correlated with?
Damage to spinocerebellum
What is anterior lobe syndrome characterised by?
Incoordination of the limbs
Where is the anterior lobe syndrome usually seen in?
Alcoholics due to lack of B vitamins
What is the neocerebellum?
Cerebella hemispheres + dentate nuclei
What is neocerebellar syndrome symptoms?
Loss of hand-eye coordination
Loss of good speech due to loss of coordination of muscles involved
What is dysmetria?
Inaccurate reaching with an intention tremour
Causes of neocerebellar syndrome?
Loss of cognitive eye movement
Stroke
Tumour
Trauma
What does cerebellar stroke usually involve?
Whole cerebellar cortex on one side
What are signs of cerebellar stroke?
Headache Nausea/vomiting Eye changes (one eye + vertigo) Dysarthria Dysphagia Ataxia Arm weakness + coordination
What mimics cerebellar stroke
Alcohol intoxications
Why does alcohol mimic cerebellar stroke?
Cerebellum has many GABA-ergic interneurones sensitive to alcohol