Basal Ganglia and Cerebellum

Question 1

What part of the cerebellum does the floccus belong to?

Answer 1

The flocculonodular lobe

Question 2

Where is the straight sinus located?

Answer 2

Within the tentorium cerebelli

Question 3

What attaches the cerebellum to the brainstem?

Answer 3

3 peduncles = superior, middle and inferior

Question 4

Where are the deep cerebellar nuclei located?

Answer 4

In the deep grey matter

Question 5

What are the three layers of the cerebellar cortex?

Answer 5

Molecular layer = outer
Purkinje cell layer = middle
Granule cell layer = inner

Question 6

Where do afferent projections to the cerebellum arrive from?

Answer 6

Spinal cord = from somatic proprioceptors and pressure receptors
Cerebral cortex = relayed via the pons
Vestibular apparatus = via the vestibular nuclei

Question 7

Where in the cerebellum do afferent projections arrive?

Answer 7

Via cerebellar peduncles and project mainly to the granule cell layer

Question 8

What is the only output from the cerebellum?

Answer 8

Via axons of Purkinje cells which mainly synapse on neurons of the deep cerebellar nuclei

Question 9

What do efferent projections from the cerebellum contribute to?

Answer 9

Co-ordinating the functions of all the motor tracts of the brainstem and spinal cord

Question 10

What happens to most efferent axons of the deep cerebellar nuclei?

Answer 10

Cross the midline and synapse in the thalamus = thalamus in turn sends fibres to the motor cortex

Question 11

Why do lesions of the cerebellum cause ipsilateral signs and symptoms?

Answer 11

The cerebellar hemispheres influence the ipsilateral side of the body (e.g right side influences right side of body)

Question 12

What happens if there is a unilateral cerebellar hemispheric lesion?

Answer 12

Disturbance of limb co-ordination = can result in intention tremor and unsteady gait in the absence of weakness or sensory loss

Question 13

What happens if there is a midline cerebellar hemispheric lesion?

Answer 13

Disturbance of postural control = patient will tend to fall over when standing/sitting despite preserved limb co-ordination

Question 14

What symptoms occur with bilateral cerebellar dysfunction?

Answer 14

Slowed slurred speech (dysarthria)
Bilateral uncoordination of arms
Staggering wide based gait (cerebellar ataxia)

Question 15

What does acute alcohol exposure cause?

Answer 15

Bilateral cerebellar hemisphere dysfunction and cerebellar ataxia

Question 16

What are the functions of the basal ganglia?

Answer 16

Facilitate purposeful movement
Inhibit unwanted movements
Role in posture and muscle tone

Question 17

What are basal ganglia?

Answer 17

Masses of grey matter located near the base of each cerebral hemisphere

Question 18

How do basal ganglia enhance normal movement?

Answer 18

Enhance outflow of the thalamus = pyramidal neurons under voluntary control issue command to move

Question 19

What kind of pathway is utilised by basal ganglia to enhance normal movement?

Answer 19

Direct pathway = endpoint of feedback loop which stimulates cortex to enhance the desired movement

Question 20

How do basal ganglia work with motor cortex to suppress unwanted movement?

Answer 20

Indirect pathway = inhibits outflow of thalamus

Question 21

What side of the body is affected by basal ganglia dysfunction?

Answer 21

The contralateral side to the lesion

Question 22

What symptoms are uncommon with basal ganglia lesions?

Answer 22

Paralysis, sensory loss, loss of power and ataxia

Question 23

What motor signs occur with basal ganglia lesions?

Answer 23

Changes in muscle tone and dyskinesias

Question 24

What are dyskinesias?

Answer 24

Abnormal involuntary movements

Question 25

What are some examples of dyskinesias?

Answer 25

Tremor = sinusoidal movements
Chorea = rapid asymmetrical movements usually affecting distal limb musculature
Myoclonus = muscle jerks

Question 26

What is Parkinson’s disease?

Answer 26

Degeneration of dopaminergic neurons of substantia nigra = akinesia, rigidity, resting tremor

Question 27

What is Huntington’s disease?

Answer 27

Autosomal dominant condition = progressive degeneration of basal ganglia and cerebral cortex

Question 28

What are some signs of Huntington’s disease?

Answer 28

Chorea and progressive dementia

Question 29

What are the three sections of the cerebellum?

Answer 29

Vestibulocerebellum, pontocerebellum and spinocerebellum

Question 30

What are some features of the vestibulocerebellum?

Answer 30

Consists of the flocculonodular lobe

Co-ordinates antigravity extensor muscles

Question 31

What are some features of the pontocerebellum?

Answer 31

Co-ordinates voluntary movement

Encompasses most of cerebellum

Question 32

What are some features of the spinocerebellum?

Answer 32

Consists of the vermis

Relates to posture