Cerebellum

Question 1

list the layers of the cerebellum

Answer 1

molecular layer
- fibers of the purkinje and granular cells

purkinje layer
- purkinje cells (mantle cell origin)

granular layer
- granular cells (external germinal cell origin)

white lamina
- deep cerebellar nuclei (mantle cell origin)

Question 2

mantle cells

Answer 2

germinal cells of cerebellum

do not divide, only grow and differentiate

• purkinje cells
• neurons of the cerebellar nuclei

Question 3

external germinal cells

Answer 3

germinal cell of the cerebellum

1. migrate to the external surface of the cerebeullum (folia)
2. divide (and grow?) until about 10-12 cells thick
3. migrate to the granular layer
4. differentiate to form granular cells

target of feline panleukopenia virus
- causes cerebellar hypoplasia

Question 4

cerebellar nuclei

Answer 4

lateral –> medial

dentate, interposital, fastigial

Question 5

general functions of the cerebellum

Answer 5

coordinate rate, range, and force of movement

maintain equilibrium (posture)

DOES NOT initiate movement

Question 6

spinocerebellar pathway

Answer 6

vermis - except the mid region

4 pathways

proprioceptors (muscle spindles, golgi tendon bodies, and joint receptors)
spinal cord
cerebellar cortex

Question 7

pyramidal system

Answer 7

cerebral cortex

pontine nuclei (pons)

~decussation~

cerebellar cortex

~decussation~

thalamus

cerebral cortex

Question 8

extra pyramidal system

Answer 8

1. indirect: via olivary nucleus

2. direct: via vestibular nuclei or tectum (vision and sound)

Question 9

mossy fibers

Answer 9

CNS origin

widespread

synapse with collateral deep cerebellar nuclei and granular neurons

granular neurons then send the signal into the molecular layer where they will likely communicate with purkinje fibers (?)

Question 10

climbing fibers

Answer 10

from olivary nucleus

synapse with collateral deep cerebellar nuclei and wrap around purkinje dendrites

Question 11

efferent cerebellar pathways

Answer 11

1. purkinje cell
   - primary cell responsible for cerebellar output
   - inhibitory
2. deep cerebellar nuclei neuron
   - pyramidal or extra-pyramidal systems

Question 12

pontocerebellum

Answer 12

feedback areas

pyramidal // extra-pyramidal systems

hemispheres and mid-vermis

Question 13

signs of cerebellar dysfunction (7)

Answer 13

ipsilateral (usually)

ataxia
dysmetria
- typically hypermetria 
menace response deficits 
postural reaction deficits 
vestibular signs (paradoxical)
anisocoria 
decerebellate postures

Question 14

abiotrophy

Answer 14

spontaneous premature neuronal death

often the purkinje cells
- susceptible to changes in metabolism

show progressive signs of cerebellar dysfunction

MRI: small cerebellum
necropsy: atrophy of cerebellum