Ii-18: Intro To The Cerebellum

Front 1

What is the tentorium cerebelli?

Back 1

Dural reflection that covers the superior side of the cerebellum

Front 2

How is the cerebellum attached to the posterior brainstem?

Back 2

Inferior, middle, and superior cerebellar peduncles

Front 3

From where does the cerebellum receive its blood supply?

Back 3

vertebral-basilar system (PICA, AICA, and superior cerebellar a.)

Front 4

What are cerebellar folia?

Back 4

Multiple narrow, parallel ridges on external surface

Front 5

What is the cerebellar vermis?

Back 5

Midline, worm-like component

Front 6

Where are the flocculi?

What is the nodulus?

Back 6

2 tufts of parenchyma visible of ventral surface

Small subdivision of the cerebellar vermis

Front 7

What is the flocculonodlar lobe?

Back 7

flocculi + nodulus

Front 8

What are the cerebellar tonsils?

Back 8

Protrude from inferior surface

Become deformed by expanding intracranial mass

Front 9

What are the superior cerebellar peduncles?

Efferents?

Afferents?

Back 9

Major efferent pathway of the cerebellum

Efferents: fibers from deep cerebellar nuclei to red nuclei and VA/VL nuclei of thalamus

afferent: projections from ventral spinocerebellar tracts

Front 10

What do the middle cerebellar peduncles contain?

Back 10

Afferent axons from contralateral basal pons

Front 11

From where does the inferior cerebellar peduncle originate?

Back 11

Medulla oblongata

Front 12

What are the afferent fibers of the inferior cerebellar peduncle? (4)

Back 12

1. From contralateral inferior olive
2. From ipsilateral dorsal spinocerebellar tract
3. From ipsilateral cuneocerebellar tract
4. Small number from vestibular nuclei

Front 13

What are the efferent fibers of the inferior cerebellar peduncle?

Back 13

Small number of projections going to the vestibular nuclei from floculus, nodulus, and fastigial nuclei

Front 14

What are the cerebellar folia composed of?

Back 14

Thin layer of gray matter (cortex) supported by branching white matter cores

Front 15

What does cerebellar white matter contain? (2)

Back 15

1. fibers projecting from extra-cerebellar sites to the cortex
2. Fibers projecting from the cortex to deep cerebellar nuclei

Front 16

How does the amount of white matter at the vermis compare to that of the cerebellar hemispheres?

Back 16

Hemispheres have more white matter

Front 17

What are the four paired deep nuclei of the cerebellum (lateral to medial)?

Back 17

dentate, emboliform, globose, fastigial (don't eat gross food)

Front 18

Dentate nuclei
a. location
b. input
c. output

Back 18

a. deep within the white matter of each hemisphere

b. projections from cortex of hemispheres

c. fibers out --> superior cerebellar peduncles --> red nucleus and thalamus

Front 19

What are the interposed nuclei?

Back 19

Eboliform and globose nuclei

Front 20

Interposed nuclei...
a. location
b. input
c. output

Back 20

a. medial to dentate
b. projections from paravermal region of cortex
c. fibers out --> superior cerebellar peduncles --> red nucleus and thalamus

Front 21

Fastigial nuclei
a. location
b. input
c. output

Back 21

a. midline in the roof of the fourth ventricle
b. fibers from vermis
c. fibers out --> inferior cerebellar peduncle --> vestibular nuclei and reticular formation

Front 22

What are the three layers of the cerebellar cortex, microscopically?

Back 22

1. Molecular layer - hypocellular
2. Purkinje cells - large, pyramidal neurons
c. granule cell layer - densely cellular

Front 23

What 3 things are included in the granule cell layer?

Back 23

granule cells
Golgi cells
cerebellar glomeruli - hypocellular, fibrilar zones

Front 24

Granule cells
a. input
b. output

Back 24

a. dendrites receive excitatory input from mossy fibers and inhibitory input from Golgi cells

b. axons ascend into molecular layer as parallel fibers --> excite Purkinje and Golgi cell dendrites

Front 25

Golgi cells
a. location
b. input
c. output

Back 25

a. cell bodies and axons = granule cell layer; dendrites = molecular layer

b. excitatory impulses from granule cell axons in molecular layer

c. send inhibitory signals back to the granule cells

Front 26

What are cerebellar glomeruli?

Back 26

Small fibrillar pink areas in the granule cel layer

Front 27

What are cerebellar glomeruli made up of? (3)

Back 27

Granule cell dendrites
Golgi cell axons
Termination of mossy fibers

Front 28

What communication occurs in the cerebellar glomeruli?

Back 28

Golgi cell axons send inhibitory signals to granule cell dendrites

Front 29

Why are Purkinje cells the 'grand central station' of the cerebellar cortex?

Back 29

They are the ultimate target of all projections into the cerebellum, and the only source of output from the cortex

Front 30

From where does the excitatory input into the Purkinje cells come? (2)

Back 30

1. Climbing fibers (direct)
2. Mossy fibers (indirect)

Front 31

From where does inhibitory input to Purkinje cells come? (3)

Back 31

1. Basket cells - molecular layer (direct)
2. Stellate cells - molecular layer (direct)
3. Golgi cells - granule cell layer (indirect)

Front 32

From where do climbing fibers come?

How do they excite Purkinje cells?

Back 32

From contralateral inferior olive

Directly excite Purkinje dendrites in molecular layer by wrapping around them

Front 33

How do Mossy fibers excite Purkinje cells?

Back 33

Mossy fibers excite granule cells --> send parallel fibers into molecular layer --> excite dendrites of Purkinje cells

Front 34

How do Golgi cells inhibit Purkinje dendrites?

Back 34

Golgi cells inhibit granule cells --> diminishes number of excitatory signals that granule cells send to Purkinje fibers

Front 35

What is the nature of all Purkinje cell output?

Where do they send these signals (2)?

Back 35

Inhibitory

1. Deep cerebellar nuclei
b. Vestibular nuclei (minority of Purkinje cells send signal here)

Front 36

What are 5 components of the molecular layer?

Back 36

1. Stellate cell bodies
2. Basket cell bodies
3. Purkinje cell dendrites
4. Granule cell axons (parallel fibers)
5. Terminations of climbing fibers

Front 37

What is the nature of the signal from projections from the deep cerebellar nuclei to extracerebellar sites?

Back 37

Excitatory

Front 38

In comparison to the long axis of the cerebellar folium, how are the Purkinje dendrites and parallel fibers of granule cells arranged?

Back 38

Punkinje dendrites = perpendicular to long axis

Parallel fibers = parallel to long axis, can excite many Purknje cell dendrites

Front 39

What are the 3 functional divisions of the cerebellum?

Back 39

1. vestibulocerebellum
2. Spinocerebellum
3. Cerebrocerebellum

Front 40

Vestibulocerebellum
a. function
b. cerebellar and cortical components
c. input
d. output
e. Deep nuclei

Back 40

a. regulation of eye movements, balance, equilibrium

b. flocculi and nodulus

c. input from inner ear and vestibular nuclei --> inferior cerebellar peduncles

d. output to inferior cerebellar peduncle --> vestibular nuclei

e. none

Front 41

What are the divisions of the spinocerebellum and what is each composed of?

Back 41

Medial portion - vermis, fastigial nuclei

Lateral subdivision - paravermal cortex and interposed nuclei

Front 42

Spinocerebellum inputs? (4)

Back 42

1. Lower extremities --> dorsal/ventral spinocerebellar tracts --> in

2. Upper extremities --> lateral cuneate nucleus --> in

3. Sensory nuclei of V

4. Vestibular system

Front 43

What does the vermal portion of the spinocerebellum send out?

What does it control?

Back 43

Projections --> fastigial nucleus--> inferior cerebellar peduncle --> vestibular nuclei, reticular formation

Influences eye movements, proximal muscles, and balance

Front 44

What does the more lateral paravermal cortex of the spinocerebellum send out?

What does it control?

Back 44

Projections --> interposed nuclei --> superior cerebellar peduncle --> thalamus and red nucleus

Activity of more distal muscles

Front 45

What are the components of the cerebrocerebellum? (2)

Back 45

Cerebellar hemispheres, dentate nuclei

Front 46

What are the inputs to the cerebrocerebellum?

Back 46

Axons synapsing in basal pons --> cross midline --> middle cerebellar peduncles --> contralateral cerebellar hemisphere

Front 47

What are the outputs of the cerebrocerebellum?

What do they control?

Back 47

Purkinje cells in cerebellar hemispheres send axons --> dentate nuclei --> superior cerebellar peduncles --> red nucleus and thalamus

Fine motor control, planning, initiation, timing of movements

Front 48

What is ataxia?

Back 48

Unsteady, staggering gait due to cerebellar injury

Front 49

What is nystagmus?

Back 49

Abnormal eye movements due to cerebellar injury

Front 50

What is dysarthria?

Back 50

Slurred speech due to cerebellar injury

Front 51

If lesions affect only one side of the cerebellum, on what side would they manifest clinically?

Back 51

Ipsilaterally

Front 52

What are the excitatory inputs to Purkinje cells (2)?

Back 52

1. Climbing fibers - direct
2. Mossy fibers --> granule cells --> parallel fibers --> Purkinje

Front 53

What are the inhibitory inputs to Purkinje cels? (2)

Back 53

1. Golgi cells --> inhibit granule --> inhibit parallel fibers --> inhibit Purkinje
2. Basket and stellate (direct)

Front 54

To where do Purkinje cells send projections from the cortex? (2)

Back 54

1. Deep cerebellar nuclei (majority of cortex)
2. Vestibular nuclei (flocclus and nodulus)