Cerebellum

Question 1

what is the function of the cerebellum?

Answer 1

regulation (improving/correcting) of motor control via upper motor neurons.

Question 2

Describe the peduncles in terms of input/output from the cerebellum:

Answer 2

superior peduncle provides output to midbrain
middle cerebellar peduncle provides input via pons
inferior provides input and output via medulla and brainstem

Question 3

fibers from the superior peduncle terminate in which regions:

Answer 3

contralateral red nucleus and thalamus

Question 4

the primary fissure separates:

Answer 4

anterior and posterior lobes of the cerebellum

Question 5

the posterolateral fissure separates

Answer 5

the posterior & flocculonodular lobes

Question 6

What is the significance of the cerebellar tonsil?

Answer 6

lies superior to the foramen magnum; w/ increased intracranial pressure, may herniate down and compress respiratory centers in medulla & spinal cord

Question 7

describe the role of the flocculonodular lobe:

Answer 7

vestibulocerebellum/archicerebellum: balance, regulation of eye movement, role in VOR

Question 8

describe the location, divisions and role of the spinocerebellum:

Answer 8

vermis + intermediate areas just lateral to vermis. Role in coordinating muscle tone of axial (vermis) and limbs (intermediate area). input from spinal cord.

Question 9

describe the input and role of the cerebrocerebellum:

Answer 9

neocerebellum/pontocerebellum: input from contralateral pontine nuclei. Planning and initiating skilled movement + learning of movement

Question 10

the deep cerebellar nuclei in the white matter of the cerebellum are, from medial to lateral:

Answer 10

fastigial, interposed, dentate

Question 11

the three layers of the cerebellar cortex are:

Answer 11

molecular, purkinje fibers, granular (out to in)

Question 12

there are __ types of neurons in the cerebellar cortex. They use ____ as a neurotransmitter. All except ___ are inhibitory. The ___ cell is the only output from the cortex. The most abundant type is ____ with long axons called ___ ____

Answer 12

5;
GABA; granule are excitatory;
Purkinji = output. Abundant = Granule; parallel fibers.

Question 13

Describe the relationship of the granule cells with purkinje cells:
where do purkinji fibers terminate?

Answer 13

granule cells have long axons that are collectively called parallel fibers. Many parallel fibers synapse on the dendrites of purkinje fibers in the molecular layer of the cerebellar cortex. purkinji fibers synapse in deep cerebellar nuclei (+ some to vestibulocerebellum to vestibular complex)

Question 14

describe mossy fibers:

Answer 14

one of major inputs to cerebellum. Coming from cerebrum via pons, spinal tracts etc. One mossy fiber contacts thousands of granule cells in the granular layer of the cortex. Excitatory.

Question 15

what is the course of the climbing fibers? what is their role?

Answer 15

extend from inferior olivary nucleus through inferior peduncle to contact purkinji fibers. ~ 1:1 ratio = highly specific. One of two major sources of input to cerebellar cortex. excitatory. Role is in plasticity - if active at same time as granule cells, those synapses will be diminished.

Question 16

the entire output of the cerebellar cortex is ____

Answer 16

inhibitory

Question 17

climbing fibers are activated when:

the outcome is:

Answer 17

expectations for the outcome of a movement or motor action are not met = message of error
outcome: every purkinji fiber synapse w/granule cells activated when climbing fiber is activated will be weakened

Question 18

contrast short and long term modification of synapses:

Answer 18

short term: phosphorylation of AMPA receptors

long term: internalization of AMPA receptors

Question 19

describe the input to the vestibulocerebellum/flocculonodular lobe:

Answer 19

from maculae and cristae in ears via vestibular nerve of CNVIII, and complex, via ipsilateral inferior peduncle.

Question 20

spinocerebellar input:

Answer 20

input = from spinocerebellar tracts monitoring muscle tone/stretch (cuneo from arms external cuneate nucleus, dorsal from legs, Clarke's nucleus) + visual information. enters via inferior peduncle
output = reg muscle tone and adjustment of movement.

Question 21

somatotopic organization of spinocerebellum:

Answer 21

vermis = trunk

intermediate areas = limbs

Question 22

spinocerebellar output from vermis:

Answer 22

vermis > fastigial nuclei >

1. vestibular nuclei & reticular formation > reticulospinal tracts for control of axial muscles inc head/neck &
2. Thalamus > motor cortex to control facial muscles/tongue

Question 23

describe spinocerebellar output from intermediate areas:

spinocerebellum controls ____ (ipsi/contrlateral) side of body:

Answer 23

intermediate area > interposed nuclei > superior cerebellar peduncle > decussate in caudal midbrain >
1. VL of thalamus > corticospinal tracts > control limb muscles
2. contralateral red nucleus > rubrospinal tract (decussates again )
double-crossing = Controls ipsilateral side of body

Question 24

Cerebrocerebellum function:

Answer 24

fine-tuning of highly skilled, voluntary movement; planning and initiating of movement

Question 25

input to the cerebrocerebellum is via:

Answer 25

cerebral cortex > pontine nucleus > middle cerebral peduncle

Question 26

output from cerebrocerebellum:

Answer 26

> dentate nucleus > superior cerebellar peduncle >
1. VL of thalamus > motor and pre-motor cortices (via dentatothalamic fibers)
& 2. parvocellular region of Red nucleus via dentatorubral fibers > inferior olivary nucleus > climbing fibers to cerebellar cortex

Question 27

what is the triangle of Molleret:

Answer 27

connection from dentate nucleus to superior cerebellar peduncle to inferior olivary nucleus and back to cerebral cortex. damage > incoordination