15 - Cerebellum

Question 1

what is the function of the lateral hemispheres? motor pathways influenced?

Answer 1

motor planning for extremities; lateral corticospinal tract

Question 2

what is the function of the intermediate hemispheres? motor pathways influenced?

Answer 2

distal limb coordination; lateral corticospinal tract, rubrospinal tract

Question 3

what is the function of the vermis and flocculonodular lobe? motor pathways influenced?

Answer 3

1st part
proximal limb and trunk coordination

anterior corticospinal tract, reticulospinal tract, vestibulospinal tract, tectospinal tract

2nd part
balance and vestibulo-ocular reflexes

medial longitudinal fasisculus

Question 4

cerebellar lesions result in a characteristic type of irregular uncoordinated movement called _____?

Answer 4

ataxia

Question 5

how does ataxia affect the cerebellum?

Answer 5

Ataxia is ipsilateral to the side of a cerebellar lesion

Question 6

what is the affect if there are Midline lesions of the cerebellar vermis or flocculonodular lobes?

Answer 6

these mainly cause unsteady gait (truncal ataxia) and eye movement abnormalities

Question 7

if there are lesions lateral to the cerebellar vermis what is the affect?

Answer 7

ataxia of the limbs (appendicular ataxia)

Question 8

what are the Deep Cerebellar Nuclei?

Answer 8

Dentate nuclei
Emboliform & globose nuclei
Fastigial nuclei

Question 9

what are the Dentate nuclei?

Answer 9

receive projections from the lateral cerebellar hemispheres (active just before voluntary movements)

Question 10

what are the Emboliform & globose nuclei?

Answer 10

receive inputs from the intermediate part (active during and in relation to the movement)

Question 11

what are the Fastigial nuclei?

Answer 11

receive inputs from the vermis

Question 12

what are the two inputs into the cerebellum?

Answer 12

mossy fibers or climbing fibers

Question 13

how does input from the mossy fibers to the cerebellum work?

Answer 13

Mossy fibers (ascending tracts (origin)), ascend through the cerebellar white matter and form excitatory synapses on granule cells

Granule cells’ axons form parallel fibers, each of these fibers form excitatory synapses with numerous Purkinje Cells.

note that all output from the cerebellar cortex is carried by the axons of the purkinje cells and the Purkinje cells form inhibitory synapses onto deep cerebellar nuclei and vestibular nuclei

Question 14

in terms of input from mossy fibers, all output from the cerebellar cortex is carried by the axons of the _____? what inhibitory synapses do these cells form?

Answer 14

purkinje cells; inhibitory synapses onto deep cerebellar nuclei and vestibular nuclei

Question 15

how does input from the climbing fibers to the cerebellum work?

Answer 15

Climbing fibers (olivary nuclei (origin))arise from neurons in the contralateral inferior olivary nucleus. They wrap around the cell body and proximal dendritic tree of Purkinje cells, forming powerful excitatory synapses

A single climbing fiber will branch to supply about 10 Purkinje cells; however each Purkinje cell is excited by just one climbing fiber

Question 16

what are the cell layers of the cerebellar cortex?

Answer 16

molecular layer
Purkinje cell layer
Granule cell layer
white matter

Question 17

what do mossy fibers excite?

Answer 17

granule cells which excite the inhibitory Purkinje cells

Question 18

T/F, Climbing fibers excite Purkinje cells directly

Answer 18

T

Question 19

T/F, All axons projecting upward are excitatory

Answer 19

T

Question 20

T/F, All axons projecting downward are inhibitory

Answer 20

T

Question 21

T/F, The outputs of the deep cerebellar nuclei are excitatory

Answer 21

T

Question 22

all outputs from the cerebral cortex come form the?

Answer 22

purkinje fibers

Question 23

lateral hemispheres send signals to the_____?

Answer 23

lateral corticospinal tract

Question 24

the dentate nucleus is active _____?

Answer 24

just before voluntary movements

Question 25

lesions of the cerebellum are described as?

Answer 25

ipsilateral