Cerebellum

Question 1

Structures in the cerebellum. What does each structure do?

Answer 1

vermis, paravermis which is lateral to the vermis, and the hemispheres. vermis coordinates the trunk. paravermis coordinates the proximal appendicular movements (ie. arm and leg), and the hemispheres do distal appendicular movements.

Question 2

What happens when someone has a cerebellar lesion? Ipsilateral or contralateral?

Answer 2

uncooordinated movements (ataxia)
difficulty judging distances when reaching for objects (dysmetria)
truncal instability
Ataxia is ipsilateral.

Question 3

Gross structure of the cerebellum

Answer 3

2 layers: cortex (grey matter)
deeper white matter. deep cerebellar nuclei are deep in the white matter adjacent to the 4th ventricle. Major output source.

Question 4

What are the 3 layers of the cerebellar cortex?

Answer 4

molecular cell layer. Outermost layer
purkinje cell layer
granule cell layer

Question 5

What is in the molecular cell layer

Answer 5

outermost layer of the cerebellum
dentdrites of Purkinje cells, parallel fibers from granule cells, climbing fibers from inferior olivary nucleus, and basket/stellate cells.

Question 6

What is in the Purkinje cell layer?

Answer 6

Purkinje cells. major output cells of the cerebellar cortex

Question 7

What is in the granule cell layer

Answer 7

granlue cells, mossy fibers, and golgi II cells.

Question 8

What is the function of the deep cerebellar nuclei?

Answer 8

major source of output for the cerebellum. 4 pairs of deep cerebellar nuclei

Question 9

What are the 4 pairs of deep cerebellar nuclei and their function?

Answer 9

1. Fastigial nucleus: source of outflow from the vermis
2. globose and emboliform nuclei: source of outflow from the paravermis
3. dentate nucleus: source of outflow from the cerebellar hemispheres.

Question 10

What are the 2 general inputs to the cerebellum?

Answer 10

spinal cord (proprioceptive info)
cerebral cortex (info about intended motor activity)
cerebellum compares the two and feeds info back to the cerebral cortex via the thalamus.

Question 11

What kinds of fibers give input to the cerebellum?

Answer 11

climbing fibers from the inferior olive only

mossy fibers from all other sources

Question 12

How do climbing fibers and mossy fibers give input to the cerebellum?

Answer 12

climbing fibers synapse directly on the Purkinje cell dendrites and send collaterals to the deep cerebellar nuclei
mossy fibers synapse on granule cells. axons of granule cells are called parallel fibers and they synapse on Purkinje cell dendrites.

Question 13

What cells regulate the input of climbing fibers, mossy fibers, and parallel fibers into the cerebellar cortex?

Answer 13

stellate cells, basket cells, Golgi II cells

Question 14

What is the major source of output from the cerebellar cortex, and what kind of output is it?

Answer 14

Purkinje cell

this is inhibitory and act directly on 4 deep cerebellar nuclei.

Question 15

What kind of adjustment occurs in each part of the cerebellum?

Answer 15

course adjust in deep cerebellar nuclei

fine adjust in cerebellar cortex

Question 16

What kind of output (inhibitory vs. excitatory) is seen from the cerebellar cortex, generally? Exceptions?

Answer 16

All cells of the cerebellar cortex are inhibitory except the granule cell, which is excitatotry

Question 17

What are the general inputs and outputs inviolving the cerebellar peduncles?

Answer 17

generally, inputs via infererior and middle cerebellar peduncles
outputs via superior cerebellar peduncle

Question 18

What tracts carry proprioceptive info from T6 and below to the cerebellum?

Answer 18

dorsal and ventral spinocerebellar tracts

Question 19

What tracts carry proprioceptive info from above spinal level T6?

Answer 19

cuenocerebellar and rostral spinocerebellar tracts

Question 20

What is special about the ventral spinocerebellar tract?

Answer 20

1. only tract that enters the cerebellum via the superior cerebellar peduncle
   it crosses twice: at the spinal cord level of entry
   in the midbrain at the decussation of the superior cerebellar peduncle