Hirsch - Cerebellum Flashcards Preview

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Flashcards in Hirsch - Cerebellum Deck (41):
1

function of cerebellum


compare motor plans with physical execution

make adjustments to keep movements coordinated, fluid, and on target

also involved in motor learning

2


cerebellar disorder

1. ataxia


reeling, wide based gait

3


cerebellar disorder

2. decomposition of movement (general)


inability to correctly sequence fine, coordinated acts

4


cerebellar disorder 2.1. dysarthria


inability to articulate words correctly with slurring and inappropriate phrasing

5


cerebellar disorder 2.2. dysdiadochokinesia


inability to perform rapid alternating movements

6


cerebellar disorder 2.3. dysmetria


inability to control range of movement (hypo or hypermetria)

7


cerebellar disorder 2.4. hypotonia


decreased muscle tone

8


cerebellar disorders 2.5. nystagmus


involuntary, rapid oscillation of the eyeballs in a horizontal, vertical or rotary direction with the fast component maximal toward the side of the cerebellar lesion

9

cerebellar disorders 2.6. tremor


rhythmic, alternating, oscillatory movement of a limb as it approaches a target (intention tremor) or of proximal musculature when fixed posture or weight bearing is attempted (postural tremor)

10

arbor vitae


whitematter of cerebellum

11


functional divisions of cerebellar cortex

cerebrocerebellum (neocerebellum)

spinocerebellum (paleocerebellum)

vestibulocerebellum

12


cerebrocerebellum


lateral

phylogenetically new

receive input from contralateral cerebral cortex

regulate complex sequence of movement including speech

13


spinocerebellum


paramedian and median (vermis zone)

phylogenetically older than neocerebellum

receive input from spinal cord

somatotopic organization

* paramedian: regulate distal muscles

* median: regulate proximal muscle and some eye movements

14


vestibulocerebellum


caudal and inferior lobes

phylogenetically ancient

receives input from vestibular nuclei (in brainstem)

regulate posture and balance including eye movements

15

deep cerebellar nuclei

dentate

interposed

fastigial

 

16


dentate nucleus

input from cerebrocerebellar zone

projects to:

1. contralateral premotor cortex

2. association cortices of frontal lobe involved in planning movement

17


Interposed nucleous


globose nucleus + emboliform nucleus

input from spinocerebellar zone

projects to:

contralateral motor cortex (aid executing movement)

18


Fastigial nucleus


input from spinocerebellar zone

projects to:

upper motor neurons (in ipsilateral brainstem)

to aid executing movement

19


vestibulocerebellum

project to vestibular nuclei

NOT to cerebellar nuclei

20


cerebellar peduncles

*afferent connection arrives

*efferent connection exits


fiber bundles carrying inputs and outputs

1. superior (brachium conjuntivum)

2. middle(info to cerebellum)

3. Inferior (restiform body

21


superior peduncles - cerebellar


efferent pathway exiting from deep cerebellar nuclei

22


middle peduncles


afferent pathway carrying information from the cortex via the pons

23


inferior peduncle


mixed;

afferent come from brainstem and spinal cord

efferent exit from vestibulocerebellum

24


know picture in (7/16) for structures associated with cerebellum


medial premotor cortex and primary motor cortex

VA/VL complex of thalamus

cerebellar cortex

deep cerebellar nuclei

pontine nuclei

vestibular nuclei

inferior olive

external cuneate nucleus

dorsal nucleus of Clarke

25

Inputs to cerebellum


1. from cerebral (frontal/parietal) cortex:

project to pontine nuclei (ipsilateral)

controls contralateral side of the body

2. cerebellar hemisphere:

receive ascending input from ipsilateral side of body

control movements on the same side of the body

** pathway from cerebral cortex to cerebellum cross at middle cerebellar peduncle

26

Ascending outputs of the cerebellum

cerebrocerebellum -> premotor cortex via dentate (motor planning);

part of it spreads to red nucleus parvocellular

spinocerebellum -> motor cortex via interposed nuclei (motor execution) 

27

descending outputs of the cerebellum

spinocerebellum -> brainstem via fastigial nucleus (motor execution)

vestibullocerebellum -> project directly to vestinular nuclei (motor adjustment, balance)

28

Cytoarchitecture of the cerebellum

three layers of cerebellar cortex from out to in

 

1. molecular layer (ML) - dendrites of purkinje cells and axons of granule cells (parallel fibers)

2. Purkinje cell layer (PL) - purkinje cells and basket cells

3. granule cell layer (GL) - granule cells have "claws"

29

cerebellar circuits

climbing fibers 

mossy fibers

climbing fibers - comes from inferior olive

mossy fiber - comes from pontine nuclei

30

climbing fiber and purkinje cell

purkinje cell receive input from a single clibing fiber (from  inferior olive) (ONE)

fires "complex spike" in response to input from a clibing fiber

31

inferior olive

makes single climbing fiber to purkinje cells

receives input from cerebral cortex, spinal cord, and "red nucleus"

32

mossy fiber and purkinje cell

come from pontine nuclei

synapse with granule cells

purkinje cell receives hundreds of thousands of inputs from parallel fibers (MANY)

purkinje cells fire "simple" spikes in response to input from parallel fibers

33

pontine nuclei

make mossy fibers to granulle cell (parallel fibers)

relay input from cerebral cortex, spinal cord and "vestibular nuclei"

34

motor learning: cerebellum can learn to compensate changes in the status quo

ex. normal vestibulo-ocular reflex (VOR) vs. VOR out of register using minifying glasses

---> VOR gain reset by moving eyes in smaller distance to compensate

movement adjusts to the vision

35

cerebellar loops

1. direct loop (deep excitatory)

2. cortical inhibitory loop

3. climbing fiber loop

36

direct loop; deep excitatory

from mossy fibers

(afferent information)

to deep cerebellar nuclei

"motor system - a reflex pathway"

37

cortical inhibitory loop

from mossy fibers

via parallel fibers

to granule cells

to purkinje cells

to ddep cerebellar nuclei and motor system

"to fine-tune reflexes"

38

climbing fiber loop

detect errors

correct them over longterm

"motor learning loop"

 

39

motor learning

climbing fiber loop & complex spike

important

40

climbing fibers derive from ______

mossy fibers come from ______

climbing fibers derive from inferior olive

mossy fiber come from pontine nuclei

41

know how to draw (16/16)

1. planning and programming

(sensory association cortex, basal ganglia, lateral hemisphere of cerebrocerebellum  ===>premotor cortical area)

2. movement

( ==> motor cortex, vermis and intermmediate hemisphere of spinocerebellum)

3. feedback signals

(vermis and intermediate hemisphere of spinocerebellum)