4. Cerebellum Flashcards
Where is the cerebellum found?
In the posterior cranial fossa
What are ‘folia’?
A folia is the equivalent to a gyrus but is found in the cerebellum
Does the cerebellum cross the midline of the brain?
Yes
What is the path of the folia, when looking at the cerebellum from above?
The folia run medio-laterally - from inside to the out vice/versa
What is the vermis?
This is the midline connection of the two cerebellar hemispheres - where the folia meet centrally
This is a worm-like structure
What are the divisions of the vermis?
There is an anterior lobe and a posterior lobe
This division occurs via the primary fissure
What are the different divisions of the cerebellum?
The cerebellum is divided into three lobes - the first two are the same as that of the vermis
Anterior
Posterior
The third is the flocculonodular lobes - this is a tiny lobe but is very important
Where are the different lobes of the cerebellum visible?
Anterior and posterior lobes are visible from the and anterior and the posterior view of the cerebellum
The flocculonudular lobe is only visible from the anterior view
What is the function of the anterior and posterior cerebellar lobes?
These function to coordinate body movements
Medial portions - motor activities of the trunk
Lateral portions - motor activities of limbs and skilled movements
What is the function of the flocculonodular lobe?
Receives input from the inner ear for the maintenance of balance and posture
What is the relation of the flocculonodular lobe to the ventricular system?
This lobe is present on the ventral surface of the cerebellum
This lobe forms part of the roof of the fourth ventricle
Where are the cerebellar tonsils located?
These are just lateral to the vermis, at the inferior surface of the cerebellum
What is the significance of the cerebellar tonsils?
No functional significance but have a pathological significance - herniate out and compress blood vessels around spinal cord and the reticulospinal tract in cases of raised ICP
Tonsillar herniation –> damage to spinal cord
What is the blood supply to the cerebellum?
Posterior inferior cerebellar artery and the superior cerebellar artery
What infarct location is the most common form of damage to the cerebellum?
The hairpin bend in the PICA - very common site for a clinical infarct
Where does information enter and leave the cerebellum from?
Via the cerebellar peduncles
What are the different cerebellar peduncles and what passes through them?
Superior CP - output Middle CP (largest) - input from contralateral cerebral cortex and cranial nerves via pons Inferior CP - input from spinal cord via dorsal and ventral spinocerebellar tracts
Is the spinocerebellar tract contra or ipsilateral?
Dorsal spinocerebellar tract is ipsilateral
Ventral spinocerebellar tract is contralateral
What information does the spinocerebellar tract convey?
Dorsal - information from proprioceptors
Ventral - information about state of reflexes and interneurones in the spinal cord
What is the role of cerebellar nuclei and what are they called?
Deep cerebellar nuclei control what is entering and leaving the cerebellum, rather than the cerebellar cortex
Fastigial - controls the anterior lobe and the vermis
Globose - controls the anterior lobe
Emboliform
Dentate - controls the posterior lobe (the cerebral hemispheres)- this is the largest
What is the floculonodular lobe controlled by?
This is not controlled by one of the deep cerebellar nuclei and instead is controlled by the vestibular nuclei of the pons
How does damage to the cerebellum present?
Overall clumsiness in the individual
Abnormal fatigue
Instability of movement
Damage to eye movements
What is the tract between the cerebral cortex and the cerebellum?
The corticocerebellar tract
What are the three functional zones of the cerebellum?
Vestibulocerebellum - flocculonodular lobe
Spinocerebellum - anterior lobe and the vermis
Cerebrocerebellum - posterior lobe (cerebellar hemispheres)
What is the function of the vestibulocerebellum?
Coordinates head and eye movements to ensure stability of gaze
Balance of head via medial vestibulospinal tract nad balance of body via lateral
What is the function of the spinocerebellum?
Controls locomotion and limb coordination
Vestibulospinal and reticulospinal tracts
What is the function of the cerebrocerebellum?
Coordinates movements initiated by the motor cortex
Speech, voluntary movements of hands and arms, hand-eye coordination
How does flocculonodular syndrome present?
What is a common cause?
Poor balance, disordered eye movements, ataxic gait, nystagmus
Medulloblastoma in the fourth ventricle
How does anterior lobe syndrome present?
What is a common cause?
Incoordination of the limbs Ataxic gait Hypotonia Depressed reflexes Dysdiadochokinesis
Often seen in alcoholics due to malnutrition and lack of B vitmains
How does neocerebellar syndrome present?
What are common causes?
Loss of hand-eye coordiantion
Intention tremor
Dysdiadochokinesis
Slurred speech
Stroke, tumour, degenerative diseases, trauma
What is a cerebellar stroke?
This is when the whole cerebellar cortex on one side lacks perfusion
What are the global signs of cerebellar stroke?
Headache, vertigo, nausea, vomiting Eye changes Dysarthia and dysphagia Ataxia Arm weakness and incoordination
What is a common differential diagnosis for cerebellar stroke and why?
Alcohol intoxication mimics many features of cerebellar damage
This is because alcohol seems so selectively effect GABA-ergic neurones and these are heavily involved in the cerebellum
What is the arbor vitae?
(Tree of life)
This is a leaf-like structure - distinctive pattern of white matter in the cerebellum
What is the general function of the cerebellum?
Modulates and refines motor movements using feedback from proprioceptors and other sensory organs
