Exam 2: Control of motor function II Flashcards Preview

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Flashcards in Exam 2: Control of motor function II Deck (51):
1

General Functions of the cerebellum

*electrical excitation of the cerebellum does not cause any conscious sensation and rarely causes any motor movement.

* Removal of the cerebellum causes body movements to become highly abnormal.

2

What are the two hemispheres of the cerebellum separated by? how is each hemisphere divided?

Separated by vermis, each is divided into an intermediate and lateral zone.

3

How is the cerebellum divided into 3 lobes?

Anterior to posterior:
Anterior lobe,
Posterior Lobe,
Flocculonodular lobe:
-associated with vestibular system.

4

What control functions are found in the vermis?

Muscle movements of the axial body, neck, shoulders, and hips.

5

What is the intermediate zone of the cerebellum concerned with?

controlling muscle contractions in the distal portions of the upper and lower limbs, esp. hands, feet, fingers, and toes.

6

What is the lateral zone associated with?

cerebral cortex with planning of sequential motor movements.

7

Transversely arranged narrow gyri called folia are associated with?

The cortex of the the gray matter of cerebellum

8

These fibers project in to the red nucleus and lesions in these nuclei lead to extremity ataxia:

Globose, Embolifom, Dentate Nuclei.

9

What would a lesion in the fastigial nuclei lead to?

Trunk ataxia

10

Fibers of this nuclei project to reticular formation and vestibular nuclei? What is it related to?

Fastigial nuclei. Related to postural activity and limb movements via reticulospinal and vestibulospinal tracts.

11

What are the four parts of the intracerebellar nuclei?

Dentate, Emboliform, Globose, and Fastigial.

12

What cells of the cerebellar cortex provide lateral inhibition on adjacent purkinje cells to prove damping?

Basket and Stellate Cells.

13

Cells of the cerebellar cortex:
Granular Cells-

Axons from parallel fibers in cortex (+)

14

Cells of the cerebellar cortex:
Golgi cells-

Project from parallel fibers to granular cell bodies (-)

15

Cells of the cerebellar cortex:
Basket cells-

Project from parallel fibers to purkinje axon hillock (-)

16

Cells of the cerebellar cortex:
Stellate Cells-

Project from parallel fibers to purkinje dendrites (-)

17

Cells of the cerebellar cortex:
Purkinje Cells-

-Extensive dendritic branching.
- Receive input from parallel fibers (20K synapses between parallel fiber and one purkinje cell. )
- Project to intracerebellar nuclei (-)
- ONLY output from cortex**********

18

Functional unit of Cerebellar Cortex:

- 30M functional units in cerebellar cortex
- Each Function unit (F.U) is centered on a Purkinje cell and a corresponding deep nuclear cell.
- output from F.U. is from deep nuclear cell.
- Afferent inputs to the cerebellum are mainly from the climbing and mossy fibers.

19

Where do all climbing fibers originate from?

the inferior olives.

20

Mossy fibers enter cerebellum from a variety of sources, what do they do?

send excitatory collaterals to deep nuclear cells and then synapse in granular layer with thousands of granule cells.

21

Where do granule cells send axons?

to outer cerebellar surface; axons branch in tow direction parallel to folia.

22

Dendrites of purkinje fibers project to these

parallel fibers.

23

Direct stimulation by _______ and _____ fibers excites deep nuclear cells. _______ cells signals inhibit deep nuclear cells.

Climbing and mossy. Purkinje.

24

Basket cells and stellate cells also function as

inhibitory cells.

25

Nervous system uses cerebellum to coordinate motor control functions at three levels

-vestibulocerebellum
-spinocerebellum
-cerebrocerebellum

26

What does the Vestibulocerebellum consist of?

flocculondular lobes and vermis. Evolved about the same time as vestibular system

27

Where does the vestibulocerebellum receive fibers from? Where does it send output primarily?

The vestibular system and oculomotor system (pontocerebellar fibers). Primary output is to the vestibular system.

28

Loss of flocculonodular lobes leads to

extreme disturbance of equilibrium and postural movements.

29

In the vestibulocerebellum system movements are often pendular and tend to overshoot. Why?

B/c of momentum. The damping system can stop movement precisely at intended point with appropriate learned subconscious signals from intact cerebellum.

30

Changes that occur when cerebellum is removed:

-movements are slow to develop
-force developed is weak
-movements are slow to turn off.

31

Spinocerebellum

consists mostly of vermis and intermediate zone.
-Receives info from motor cortex and red nucleus telling cerebellum intended sequential plan of movement for the next few fractions of a second.

-Feedback info from periphery telling cerebellum what actual movements results.

32

The spinocerebellum compares two sources of information and sends corrections to:

- motor cortex via thalamus
-Magnocellular portions of red nucleus.

33

Cerebrocerebellum:

-consists of lateral parts of hemispheres
-mostly associated with the premotor and the primary and association somatosenosry areas of teh cerebral cortex.
- Receives corticopontocerebellar projections.

34

The cerebrocerebellum is involved in coordination of skilled movements and speech. What is meant by it's "motor" imagery" ?

Plans as much as tenths of a second in advance of actual movements.

35

Dysmetria

refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia. It is sometimes described as an inability to judge distance or scale.

36

Ataxia:

the loss of full control of bodily movements.

37

past pointing:

means that in the absence of the cerebellum, a person ordinarily moves the hand or some other moving part of the body considerably beyond the point of intention. This results from the fact that normally the cerebellum initiates most of the motor signal that turns off a movement after it is begun; if the cerebellum is not available to do this, the movement ordinarily goes beyond the intended mark. Therefore, past pointing is actually a manifestation of dysmetria.

38

Dysdiadochokinesia

is a feature of cerebellar ataxia and may be the result of lesions to either the cerebellar hemispheres or the frontal lobe (of the cerebrum), it can also be a combination of both.

39

Dysarthria

difficult or unclear articulation of speech that is otherwise linguistically normal.

40

Cerebellar nystagmus

Tremor of the Eyeballs

41

hyptonia:

Decreased Tone of the Musculature

42

Path of afferent corticopontocerebellar:

Motor and premotor cortices/Somatosensory cortex --> pontine nuclei --> lateral divisions of cerebellum

43

Vestibulocerebellar afferent path

Terminates in flocculonodular lobes

44

afferent path of reticulocerebellar

terminates primarily in vermis

45

afferent path of spinocerebellar

dorsal and ventral.
transmits signals at 120 m/second

46

All of the afferent tracts to the cerebellum for the __________ that terminate on the ________ cells in the Cerebellar cortex (+)

mossy fibers, granule

47

What does the dorsal spinocerebellar apprise the cerebellum of momentary status of?

-muscles contractions
-degree of tension on the muscle spindles
-positions and rates of movement of parts of the body.
-forces acting on surfaces of the body.

48

Dorsal spinocerebellar pathway

muscle fibers ---> ipsilaterally in vermis and intermediate zones.

49

This afferent tract to the cerebellum terminates both ipsilaterally and contralaterally?

Ventral spinocerebellar.

50

What does the ventral spinocerebellar tell cerebellum?

- which motor signals have arrived at the anterior horns.
- this feedback= efference copy of the anterior horn motor drive.

51

How is the ventral spinocerebellar excited?

Excited by:
-Coretex via corticospinal and rubrospinal tracts
-internal motor pattern generators within spinal cord.