Cerebellum

Question 1

Which ventricle does the cerebellum overly?

Answer 1

IVth ventricle

Question 2

How is the cerebellum connected to the brainstem?

Answer 2

Via the inferior, middle and superior cerebellar peduncles

Question 3

What is the cerebellum involved in?

Answer 3

Important role in motor control - coordination of movement and balance, therefore cerebellar dysfunction often presents with motor signs

Question 4

How is the cerebellum separated from the occipital and temporal lobes of the forebrain?

Answer 4

via tentorium cerebelli - tough layer of dura mater

Question 5

The cerebellum comprises two ovoid hemispheres joined in the midline by what?

Answer 5

vermis - worm like median ridge of tissue

Question 6

The surface of the cerebellum is highly convoluted - what are the folds called?

Answer 6

folia

Question 7

Describe the orientation of the grey and white matter of the cerebellum

Answer 7

Cerebellum consists of an outer layer of grey matter (cortex) and an inner core of white matter surrounding centrally placed aggregations of nerve cells (deep nuclei)

Question 8

The cerebellum can be divided into 3 lobes - what are they?

Answer 8

anterior lobe
posterior lobe
flocculonodular lobe

Question 9

What fissures separate the lobes of the cerebellum?

Answer 9

primary fissure
horizontal fissure
posterolateral fissure

Question 10

What does the primary fissure separate?

Answer 10

primary fissure is considerably deeper and more conspicuous than other fissures - separates the anterior and posterior lobes of each cerebellar hemisphere

Question 11

What does the posterolateral fissure separate?

Answer 11

On the underside the posterolateral fissure demarcates the location of small regions of the hemisphere (the flocculus) and vermis (nodule), which together form the flocculonodular lobe

Question 12

What does the horizontal fissure do?

Answer 12

Landmark which divides the cerebellar hemispheres into superior and inferior portions

Question 13

What is the flocculonodular lobe concerned with?

Answer 13

vestibular information

Question 14

Cerebellum can also be divided into functional divisions - what are the three functional areas?

Answer 14

cerebrocerebellum
spinocerebellum
vestibulocerebellum

Question 15

What is the cerebrocerebellum?

Answer 15

Largest division formed by the lateral hemispheres - involved in planning movements and motor learning. It receives inputs from the cerebral cortex and pontine nuclei and sends outputs to the thalamus and red nucleus. This area also regulates coordination of muscle activation and is important in visually guided movements

Question 16

What is the spinocerebellum?

Answer 16

comprised of the vermis and intermediate zone of the cerebellar hemispheres - involved in regulating body movements by allowing for error correction. It also receives proprioceptive information

Question 17

What is the vestibulocerebellum?

Answer 17

functional equivalent to the flocculonodular lobe - involved in controlling balance and ocular reflexes, mainly fixating on a target. It receives input from the vestibular system, and sends outputs back to the vestibular nuclei

Question 18

Where does the cerebellum receive its blood supply from?

Answer 18

Blood supply received from 3 paired arteries:
- superior cerebellar artery
- anterior inferior cerebellar artery
- posterior inferior cerebellar artery

Question 19

The superior cerebellar artery and the anterior inferior cerebellar artery are branches of what?

Answer 19

basilar artery

Question 20

The posterior inferior cerebellar artery is a branch of what?

Answer 20

vertebral artery

Question 21

What is the cerebellar tonsil?

Answer 21

prominent round swelling of the cerebellar cortex anteriorly on either side of the vermis

Question 22

Which region of the brainstem does the superior, middle and inferior cerebellar peduncles connect to?

Answer 22

superior - midbrain
middle - pons
inferior - medulla

Question 23

What are the 4 cerebellar nuclei embedded in the white matter of the cerebellum? Think ‘Dont eat greasy food’

Answer 23

dentate
emboliform
globose
fastigi

Question 24

What is the dentate nucleus?

Answer 24

Largest and most lateral of the deep cerebellar nuclei, important for the regulation of many aspects of voluntary motor activity, including its timing, planning and inception - only cerebellar nucleus that can be seen with the naked eye/represents a crinkled bag

Question 25

The dentate nucleus sends impulses to two main destinations - what are they?

Answer 25

thalamus and red nucleus

Question 26

What are the functional connections between the cerebellum and brainstem?

Answer 26

Connected to midbrain, pons and medulla via superior, middle and inferior cerebellar peduncles - these tracts carry information in both directions

Question 27

What pathways does the superior cerebellar peduncle carry?

Answer 27

efferent fibres from the dentate, emboliform and globose nuclei - send feedback to the motor cortex in the frontal lobe. Afferent fibres from the ventrospinocerebellar tract take unconscious proprioceptive information from the lower body

Question 28

What pathways does the middle cerebellar peduncle carry?

Answer 28

corticopontocerebellar information - copy of the information from the primary motor cortex which the pyramidal tract is carrying down to lower motor neurons

Question 29

What pathways does the inferior cerebellar peduncle carry?

Answer 29

vestibulocerebellar tract (vestibular impulses from labyrinths, directly and via the vestibular nucleus). Also unconscious proprioceptive information from the dorsospinocerebellar tract

Question 30

The dentate nuclei are the largest of the paired cerebellar deep nuclei. What role do they play? Where do efferent fibres from the nucleus go?

Answer 30

The dentate nucleus is responsible for the planning, initiation and control of voluntary movements.
Efferent fibres travel via the superior cerebellar peduncles through the red nucleus to the thalamus.

Question 31

Clinical link - what happens with a midline lesion of the cerebellum? eg - tumour

Answer 31

Leads to a loss of postural control, as a result its impossible to stand or sit without toppling over, despite preserved coordination of the limbs themselves

Question 32

Unilateral lesions of the cerebellum cause problems on what side of the body?

Answer 32

Ipsilateral side

Question 33

What happens with a unilateral cerebellar hemispheric lesion?

Answer 33

causes ipsilateral incoordination of the arm (intention tremor) and leg, causing an unsteady gait, in the absence of weakness or sensory loss

Question 34

What does bilateral dysfunction of the cerebellum, caused by alcoholic intoxication, hypothyroidism, inherited cerebellar degeneration/ataxia, MS or paraneoplastic disease cause?

Answer 34

slowness and slurring of speech (dysarthria)
incoordination of both arms and a staggering, wide-based, unsteady gait (cerebellar ataxia)

Question 35

Cerebellar lesions also impair coordination of eye movements - what problems might be experienced?

Answer 35

characteristic, involuntary and rhythmic to-and-fro motion = nystagmus
this is a common feature of MS

Question 36

The combination of nystagmus with which two other symptoms constitutes Charcot’s triad, which is highly diagnostic of MS?

Answer 36

intention tremor and dysarthria

Question 37

What are the three main inputs to the cerebellum?

Answer 37

1. corticopontine from primary motor cortex to middle cerebellar peduncle
2. vestibular to the inferior peduncle
3. spinal sensory to the superior (contralateral) and inferior (ipsilateral) cerebellar peduncles