cerebellum

Question 1

what is the most common site of infarct in the posterior circulation of the brain??

Answer 1

PICA

Question 2

what are the three (microanatomical) layers of cerebellar cortex? describe them.

Answer 2

1. Outer molecular layer: male; mostly axons
2. middle layer: single row of Purkinje cell
3. inner layer: thick granule layer containing vast numbers of granule cells

Question 3

which cerebellar peddle carries output fibres only?

Answer 3

superior cerebellar peduncle

Question 4

where does middle cerebellar peduncle receive its input from?

Answer 4

contralateral cerebral cortex and cranial nerves

Question 5

where does the inferior cerebellar peduncles receive its input from?

Answer 5

spinal cord

Question 6

what information does the dorsal spinocerebellar/Flechsig’s tract carry?

Answer 6

information from proprioceptors (muscle spindles, joints, Golgi tendons etc). it travels ipsilaterally

Question 7

what information does the ventral spinocerebellar tract carry?

Answer 7

transmit information about coordinated movement and posture of the entire lower limb (state of reflex)

Question 8

what are the 4 deep cerebellar nuclei?

Answer 8

1. fastigal
2. globose
3. emboliform
4. dentate

Question 9

describe the connections between the cerebellar cortex and the nuclei?

Answer 9

1. fastigal –> vermis
2. globose and emboliform –> anterior lobe
3. dentate –> hemispheres

Question 10

which nuclei does the flocculonodular lobe connect to?

Answer 10

lateral vestibular nuclei of the pons

Question 11

what is the role of cerebellum in movement?

Answer 11

help the motor cortex produce accurate and smooth movements by modulating and refining the motor cortex commands using feedback from proprioceptors & other sensory organs

Question 12

what is the vestibulocerebellum comprised of and what is its function?

Answer 12

1. flocculonodular lobe + lateral vestibular nucleus
   - coordination of had and eye movements
   - controls the balance of the head on the body (medial VST)and body on the ground (Lateral VST).

Question 13

describe the input and output pathways of the vestibulocerbellum.

Answer 13

Input: vestibular nerve (from vestibular apparatus) and the vestibular nuclei , afferents from neck muscles and extra-ocular eye muscles
output: medial longitudinal fascicles and medial VST (motor commands to neck and eye muscles). lateral vestibulospinal tract (motor commands to the legs)
motor programs are stored in the flocculonodular cortex

Question 14

what are the signs or symptoms of flocculonodular syndrome?

Answer 14

1. poor balance, tendency to fall toward side of lesion
2. disordered eye movements (nystagmus, ocular dysmetria, poor visual tracking)
3. little control of axial muscles
4. wide-based ataxic gait; reeling and swinging

Question 15

what is the most common cause of flocculonodular syndrome? where does it occur?

Answer 15

Medulloblastoma; grows in the wall of the 4th ventricle

Question 16

what type of tumour is a medulloblastoma?

Answer 16

primitive neuroectodermal tumour

Question 17

what is the spinocerebellum comprised of?

Answer 17

anterior lobe –> globose and emboli form nuclei

vermis –> fastigal nucleus

Question 18

wha tis the function of the spinocerebellum?

Answer 18

control of locomotion and limb co-ordination

sends motor commands via reticulospinal tract to cor-ordinate posture and movements

Question 19

how does anterior lobe syndrome manifest and occur?

Answer 19

occurs due to spinocerbellar damage (alcoholic and malnutrition - lack of vitamin b)
presentation: incoordination of limbs; ataxia and hypotonia, depressed reflexes

Question 20

what does the neocerebellum/cerebrocerebellum comrpise of?

Answer 20

(hemispheres) –> dentate nucleus
input: cerebral cortex–> middle cerebellar peduncle
output: superior cerebellar peduncle –> VL motor thalamus

Question 21

what is the function of the neocerebellum/cerebrocerebellum ?

Answer 21

co-ordination of voluntary movement initiated by the motor cortex

Question 22

describe neocerebellar syndrome?

Answer 22

loss of hand eye co-ordination

• dysmetria
• dysdiadochokinesis
• intention tremors
• slurred speech
• failure of eye movement programs –> selective attention and perception

Question 23

what are the signs of cerebellar stroke?

Answer 23

headache, vertigo, nausea, vomiting
eye changes (nystagmus, ptosis, miosis)
dysarthria and dysphagia 
ataxia
arm weakness and co-ordination