Cerebellum and Basal Ganglia

Question 1

functional divisions of cerebellum

Answer 1

1. Vestibulocerebellum
2. Spinocerebellum
3. Corticocerebellum

Question 2

Layer of the cerebellum

Answer 2

*People Pray to God

Plexiform / outer molecular layer
Purkinje layer
Granular layer

Question 3

Parallel fibers come from which layer?

Answer 3

Granule cells in granular layer

Question 4

the thinnest cerebellar layer is the

Answer 4

purkinje layer

Question 5

What forms the final common pathway of the cerebellum?

Answer 5

Purkinje fibers via the cerebellovestibular tract

Question 6

The number of interneurons in the granular layer is ___ the number of all neurons in the entire nervous system:

a) 1/4
b) 1/2
c) 2/3
d) 2/3

Answer 6

1/2

Question 7

Differentiate climbing fibers, parallel fibers, and mossy fibers

Answer 7

Climbing fibers originate from neurons of inferior olivary nucleus and end up synapsing with Purkinje cells

Parallel fibers originate from granule cells of granular layer and end up synapsing with Purkinje cells in the molecular layer (even though purkinje cells are found in the purkinje layer they send their dendrites to plexiform layer). their axons receive synapses from stellate and basket cells

Mossy fibers come from many different brain areas (cerebrum, medulla, pons etc.) and terminate in the granular layer

Question 8

The only excitatory cells of the cerebellar cortex are the

Answer 8

Granule cells

Question 9

Explain why the excitatory effect of climbing fibers is very strong on purkinje cells while the mossy fibers have weak effect.

Answer 9

Climbing fibers synapse with their own Purkinje cells so signal is concentrated
Mossy fibers synapse with many Purkinje cells so their signal diffuses

Question 10

How does the cerebellar cortex coordinate body activities?

Answer 10

By regulating signals coming from thalamus then sending them to cerebral cortex.
By regulating signals along the final motor pathway between cerebral cortex and spinal cord

Question 11

The oldest cerebellar nucleus is the

Answer 11

Fastigial nucleus

*“you old FArT**

Question 12

The largest tract in the body is the

Answer 12

Pontocerebellar tract/circuit

Question 13

Lesions to vestibulocerebellum and pathophysiology

Answer 13

Result in decrease in muscle tone (hypotonia) because they are no longer inhibiting the reticular formation. Reticular formation inhibits muscle tone so when it’s not being inhibited, muscle tone is inhibited.

Question 14

State the cerebellar nuclei

Answer 14

*MNEMONIC: Global Emissions Date Far back in the past.

1. Globossus
2. Emboliform
3. Dentate
4. Fastigial nucleus

Question 15

What major types of fibers (afferent or efferent) are in the superior, inferior, and middle cerebellar peduncles?

Answer 15

The superior cerebellar peduncle is mostly efferent.
The inferior and middle cerebellar peduncles are mostly afferent.

*THINK: The top gives the commands (efferent), those below receive commands (afferents).

Question 16

The major cerebellar area for receiving sensory inputs is the

Answer 16

Spinocerebellum

Question 17

largest funcitonal part of cerebellum

Answer 17

corticocerebellum

Question 18

The floculonodular lubule is a component of which functional part of cerebellum

Answer 18

Vestibulocerebellum

Question 19

Mechanism of corticocerebellum

Answer 19

1. Damping actions
   it cuts off extra impulses so movements are smooth and accurate
2. Control of ballistic movements
   - programs and plans timing and execution of skilled repetitive movements
3. Servomechanistic action
   - corrects any disturbances
4. Comparator function
   - receives both output commands from cerebrum and input feedback from muscles so it is able to integrate both pathways and modify them if needed

Question 20

How are body parts presented on cerebellum?

Answer 20

In an upright manner unlike that in the cerebral cortex

Question 21

Mechanism of spinocerebellum

Answer 21

Facilitates discharge of gama motor neurons of the spinal cord to increase muscle tone

Question 22

Why does lesion to spinocerebellum and vestibulocerebellum result in hypotonia?

Answer 22

Spinocerebellum works to cause increase in discharge of gama motor neurons so when it’s lesioned, there is no more excitatory signals to the motor neurons and they stop firing resulting in decrease muscle tone.

The vestibulocerebellum inhibits the reticular formation which is itself an inhibitor of muscle tone. So if the vestibulocerebllum is lesioned, the reticular formation is free to cause inhibition of muscle tone

Question 23

Why cerebellar lesions have ipsilateral effects

Answer 23

Because the fibers decussate twice.

Input fibers cross to reach the cerebellum, and cerebellar output fibers cross to reach their destination

Question 24

Diadochokinesis

Answer 24

normal condition in which one is able to do ballistic movements

Question 25

Name condition when a patient is unable to carry out ballistic movements.

Answer 25

Dysdiadochokinesia / Adiodochokinesia