Cerebellum

Question 1

What are the 3 main functions of the cerebellum?

Answer 1

1) Essential for the production of co-ordinated movements
2) Co-ordinates time, force and duration of muscle action - synergy
3) Is involved in maintaining balance and posture

Question 2

In addition to the 3 main functions of the cerebellum, what other additional functions have been proposed?

Answer 2

1) May store instruction for patterns of movement - getting in a car and knowing how to drive
2) May have linguistic and cognitive functions

Question 3

What are the main gross anatomical structures of the cerebellum?

Answer 3

1) Anterior lobe
2) Posterior lobe
3) Vermis
4) Tonsil (2)
5) Primary fissure separating anterior and posterior lobe
6) Flocculus (2)
7) Nodule (1)

Question 4

What are the 2 functional subdivisions of the cerebellum?

Answer 4

1) Archicerebellum or vestibulocerebellum: flocculonodular lobe and part of vermis (midline)
2) Paleocerebellum or spinocerebellum: comprises most of vermis and adjacent regions of hemispheres (strip in middle)
3) Neocerebellum or cerebrocerebellum
Comprises lateral parts of hemispheres

Question 5

What is the role of the vestibulocerebellum?

Answer 5

• Coordinates muscles involved in maintaining balance and constancy of visual fields
• Receives input from vestibular apparatus of inner ear

Question 6

What is the role of the spinocerebellum?

Answer 6

Co ordinates muscles involved in maintaining posture and locomotion

Question 7

What is the role of the cerebrocerebellum?

Answer 7

Co-ordinates movements of distal limbs, particularly fine skilled movements of the hand

Question 8

Which division of the cerebellum is thought to be involved in learning, linguistic and cognitive functions?

Answer 8

Cerebrocerebellum

Question 9

Is the cerebellum somatotopically mapped?

Answer 9

Yes to an extent - the vestibulocerebellum in midline controls balance, the spinocerebellum controlling muscles more proximally and the cerebrocerebellum controlling structures more distally

Question 10

Which part of the body detects movement of the head?

Answer 10

Vestibular apparatus in inner ear

Question 11

How does information about movement of the head pass to the vestibulocerebellum in order to maintain constancy of gaze?

Answer 11

Passes from the vestibule via CNVIII (vestibular part) to the vestibulocerebellum via the inferior cerebellar peduncle either synapsing in the vestibular nucleus in the medulla or straight to the cerebellum from the vestibule

Question 12

IS the influence of the cerebellum contralateral or ispislateral?

Answer 12

Ipsilateral

Question 13

By what 3 methods do we understand our position in space?

Answer 13

1) Eyes
2) Vestibular apparatus
3) Proprioception: muscle spindles or Golgi tendon organs

Question 14

The spinocerebellum receives what kind of information via what?

Answer 14

Receives info about what the muscles are doing - ie proprioception from the muscle spindles and Golgi tendon organs via the spinocerebellar tract which passes from the spinal cord into the cerebellum via the inferior cerebellar peduncle

Question 15

What kind of information does the cerebrocerebellum receive via what?

Answer 15

Information about the intended movements from the motor cortex
Receives this via the pontine nuclei which enters the cerebellum via the middle cerebellar peduncle
Also receives this via the inferior olivary nucleus which enters the cerebellum via the inferior cerebellar peduncle

Question 16

Does the spinocerebellum receive info from the ipsilateral side or the contralateral side?

Answer 16

Receives info from the motor cortex on the ipsilateral side

Question 17

Does the cerebrocerebellum receive info from the ipsilateral or contralateral side?

Answer 17

Receives info from the motor cortex in the contralateral side

Question 18

Once the spinocerebellum and cerebrocerebellum have received info, the output is to what 3 structures, via what?

Answer 18

Output to contralateral:
1) Motor cortex (Via thalamus)
2) Reticular nuclei
3) Red nucleus
All via the superior cerebellar peduncle
Output of the cerebellum ensures intended movements are coordinated and controlled

Question 19

What experiment suggested that the cerebrocerebellum has some role in motor learning?

Answer 19

• Puff of air at the cornea causes rabbits to blink
• A sound is made before puff of air
• Eventually rabbit blinks without puff of air purely on basis of sound
• Damage to this inferior olivary nucleus stops this and sound alone cannot produce a blink - inferior olivary nucleus sends info to cerebrocerebellum thus its though to be involved in learning

Question 20

What is meant by ataxia?

Answer 20

Incoordination - person is still able to move but not in a coordinated manner

Question 21

What is meant by truncal ataxia?

Answer 21

Inability to stand without falling over

Question 22

What part of the cerebellum is affected in truncal ataxia, what is the most common cause?

Answer 22

Midline lesion affecting vestibulocerebellum

Most commonly due to medulloblastoma

Question 23

What is gait ataxia?

Answer 23

Lower limbs affected - have a wide based, staggering gait

Question 24

Gait ataxia is caused by a lesion in which part of the cerebellum?

Answer 24

Lesion of the spinocerebellum

Question 25

Lesions of the spinocerebellum causing gait ataxia are most common in what group of people?

Answer 25

Chronic alcoholics due to degeneration of the cerebellar neurons in paravermal areas

Question 26

Give 3 common causes of lesions of the cerebellar hemisphere?

Answer 26

1) Vascular 2) Degenerative 3) Trauma

Question 27

Patients which lesions of the cerebellar hemisphere have in coordination of voluntary movement, what 5 signs do they show?

Answer 27

1) Tremor of intent 2) Past pointing or dysmetria 3) Adiadochokinesia (inability to perform rapidly alternating movements) 4) Dysarthria 5) Nystagmus

Question 28

What is the output of the vestibulocerebellum?

Answer 28

Sends out neurons via the ICP which synapses in the vestibular nucleus Then have outputs from vestibular nucleus to LMNs via the vestibulospinal tract Also have outputs from vestibular nucleus to neck LMNs and to CN 3,4,6 (via medial longitundinal fasiculus) All acts on the ipsilateral side

Question 29

Info from the vestibulocerebellum via the vestibular nucleus travels to CN3,4,6 via what tract?

Answer 29

The medial longitudinal fasciculus

Question 30

The spinocerebellum and cerebrocerebellum send info to the contralateral structures of the brain, how does the cerebellum still act ipsilaterally?

Answer 30

Because the motor cortex controls the contralateral body - so the information effectively crosses over again to same side as the cerebellum

Question 31

Midline lesions cause what symptom, what is the most common form in which groups?

Answer 31

Truncal ataxia | Most common cause is medulloblastoma in the roof of the fourth ventricle, most commonly occurs in children

Question 32

In addition to truncal ataxia, what are the 2 other sets of symptoms associated with medulloblastoma?

Answer 32

1) Signs of raised intracranial pressure - headache, vomiting, drowsiness, papillodema. 2) Nystagmus can also be illicited

Question 33

Anterior lobe lesions of the cerebellum result in what symptom?

Answer 33

Gait ataxia

Question 34

Anterior lobe lesions are most common in which groups?

Answer 34

Chronic alcoholics

Question 35

In addition to gait ataxia what other 4 symptoms can be the result of anterior lobe lesions?

Answer 35

1) Head tremor 2) Sensory ataxia (as the disease progresses peripheral neuropathy may result) 3) Tendon reflexes may be depressed 4) Hyperextension of the knee joint during standing (due to reduction of monosynaptic reflexes activity during walking resulting in damage to soft tissues)

Question 36

Lesions to which 3 parts of the cerebellum result in incoordination of voluntary movements?

Answer 36

1) Neocerebellar cortex 2) Dentate nucleus 3) Superior cerebellar peduncle