the cerebellum

Question 1

what are the main functions of the cerebellum?

Answer 1

the production of coordinated movement, maintaining balance, equilibrium and posture, coordinating appropriate time, force and duration of muscle contraction or synergy, may store instructions for patterns of movements and may have linguistic and cognitive functions

Question 2

how does the cerebellum act?

Answer 2

ipsilaterally

Question 3

where is the cerebellum?

Answer 3

it is found under the occipital lobes of the cerebral hemispheres

Question 4

what attaches the cerebellum to the brainstem?

Answer 4

three pairs of cerebellar peduncles

Question 5

what can be seen from a)dorsal/superior b)anterior / ventral and c) inferior views of cerebellum?

Answer 5

a) vermis, posterior and anterior lobes
b) nodule, flocculus and the tonsils
c) tonsils

Question 6

what are the subdivisions of the cerebellum?

Answer 6

the vestibulo/archicerebellum
the spino/paleocerebellum
the cerebro/neocerebellum

Question 7

what comprises the neocerebellum?

Answer 7

the lateral parts of the hemispheres

Question 8

what comprises the vestibulocerebellum?

Answer 8

the flocculonodular lobe and part of the vermis

Question 9

what comprises the spinocerebellum?

Answer 9

the rest of the vermis and the adjacent region of the hemispheres

Question 10

what is significant about the cerebellar homunculus?

Answer 10

it matches up to the function of the specific subdivisions

Question 11

what is the role of the spino?

Answer 11

coordinate muscles of posture and locomotion

Question 12

what is the function of cerebro?

Answer 12

coordinate movements of distal limbs, particularly fine, skilled and targeted movements of the hands, also involved in cognitive, linguistic and learning

Question 13

what is the role of the vestibulo?

Answer 13

coordinating muscles involved in balance and constancy of visual fields and receiving input from the vestibular apparatus of the inner ear
regulates balance and eye movements

Question 14

what is the the basis of the vestibulo

Answer 14

it receives ipsilateral information from balance - associated with the vestibular apparatus and nuclei and adjust muscles and eye movements in response to vestibular stimuli

Question 15

where does the cerebellum receive information from and send it to?

Answer 15

it receives information from the vestibulocerebellar afferents from the vestibular nuclei of the same side - this is through the ICP
also through the ICP it will send information back to the vestibular nuclei through cerebellovestibular efferents

Question 16

how does the vestibulo regulate eye movements?

Answer 16

via the vestibulospinal tract - coordinates actions of muscles that maintain equilibrium,
via the medial longitudinal fasciculus
coordinates the actions of the eye movement - this will also descend with the VST and has a similar role

Question 17

where is the vestibular nucleus?

Answer 17

it is in the open medulla

Question 18

where does information go after the vestibular nucleus?

Answer 18

to LMNs via the vestibulospinal tract or the neck LMNs or to III, IV, VI nerve via medial longitudinal fasciculus
cervical or lumbar cord

Question 19

what vestibular nuclei are there?

Answer 19

the lateral and the medial in the pons level / rostral medulla

Question 20

what is the function of the spinocerebellum and the basis of this?

Answer 20

it regulates the body and limb movements
it receives unconscious proprioception from the golgi organs and muscle spindle about the length of the muscle, level of tension and the speed of movement and adjust the muscle tone and execution of movement

Question 21

which peduncles does proprioception and other sensory information travel into the cerebellum through?

Answer 21

the ICP - spinocerebellar tract

Question 22

what is the cerebrocerebellar for?

Answer 22

controlling fine and targeted movements such as in the hands and also for cognitive, learning and linguistic functions

Question 23

how does the cerebrocerebellar work?

Answer 23

it receives information on intended movements that are in progress from the cerebral cortex using the cerebropontine fibres and the olivocerebellar fibres and then ensures a smooth and orderly sequence of muscle contractions with intended precision, direction and force which is particularly important for upper limb activities

Question 24

what are the connections for the cerebrocerebellum?

Answer 24

input from the motor cortex via the contralateral inferior olivary nucleus through the ICP (olivocerebellar afferents) and through contralateral the pontine nucleus through the MCP (pontocerebellar afferents) to the lateral hemispheres to the cerebellum

Question 25

where is the entry to the spinal cord for spinocerebellar?

Answer 25

enters through the dorsal horn after synapsing in the dorsal root ganglion

Question 26

what system is the spinocerebellum part of ?

Answer 26

the somatosensory

Question 27

what are the afferents and efferents for the spinocerebellum?

Answer 27

afferents - spinocerebellar via ICP | efferents - cerebellothalamic and cerebellorubral via SCP

Question 28

what is the influence of the spinocerebellum?

Answer 28

influences descending pathways to control muscle tone and execution of movement via the rubrospinal and corticospinal tracts

Question 29

where do the efferents if the cerebrocerebellar travel?

Answer 29

they travel via the SCP decussation via cerebellothalamic efferents to contralateral thalamus and then to the motor cortex

Question 30

what is the influence of the cerebrocerebellum?

Answer 30

influences descending pathways to ensure that the intended movements are precise corticospinal tracts, corticorubral/rubrospinal or corticoreticular/reticulospinal tracts

Question 31

what are the sizes of fibres entering the dorsal root?

Answer 31

medial divisions are large fibres and lateral are small fibres

Question 32

what are the two descending pathways involved in movement?

Answer 32

reticulospinal - voluntary movement, consciousness and breathing rubrospinal - controlling muscle tone

Question 33

what nuclei are involved in the reticulo and rubrospinal pathways?

Answer 33

reticulo - reticular formation in brainstem which is the pons and the medulla rubro - red nucleus in the midbrain

Question 34

what is the result of cerebellar damage?

Answer 34

there are predictable movements depending on the subdivision that is damaged but this will commonly be ataxia (no order) or incoordination - person can still move but in disordered manner

Question 35

what is the nucleus of the reticular formation in the medulla?

Answer 35

the nucleus reticularis gigantocellularis

Question 36

what is truncal ataxia?

Answer 36

it is the inability to stand or sit without falling over due to a midline lesion affecting the vestibulocerebellum and most commonly due to medulloblastoma

Question 37

describe medulloblastomas?

Answer 37

they most commonly occur in children in the roof of the fourth ventricle - they expand rapidly with signs of raised ICP (headache, vomiting, papilloedema and drowsiness). The tumour attacks the pathway from the vermis to the vestibular node meaning malfunction of the lateral vestibular nucleus and tract. Movements of the eye are also inaccurate. Treat with radiotherapy - very sensitive.

Question 38

what is gait ataxia?

Answer 38

it is when the lower limbs are affected most resulting in a wide based gait and staggering. It is due to a lesion in the spinocerebellum and is most common in chronic alcoholics due to degeneration of the cerebellar neurons in paravermal areas. There is pronounced shrinkages of the cortex in the anterior lobe. Head tremor and sensory ataxia are usually present.

Question 39

what is the result of lesions in the cerebrocerebellum?

Answer 39

incoordination of voluntary movements particularly in the upper limb - many causes that can be degenerative, trauma or vascular. The patients present with tremor of intent, adiadochokinesia, dysarthria and past point or dysmetria

Question 40

adiadochokinesia?

Answer 40

inability to perform rapid alternating movements

Question 41

dysmetria?

Answer 41

cannot coordinate movements - overshoot or under

Question 42

dysarthria?

Answer 42

slow or slurred speech | impaired phonation or articulation