Chapter 11 Part 2 Flashcards Preview

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Flashcards in Chapter 11 Part 2 Deck (39):
1

What percentage of neurons of CNS are on the cerebellum?

50

2

What does the cerebellum do?

Coordinates movement and postural control by comparing actual motor output with the intended movement and then adjust the movement as necessary

3

What else is cerebellum involved in?

Is involved in learning timing and rhythm of movements, synchronization of movements, and learning to correct motor errors

4

Three layers of the cerebellum:

outer layer
middle layer
inner layer

5

What are the neurons of the crerebellum?

principal: purkinje fibers
interneurons

6

What are the afferent fibers of the cerebellum?

mossy fibers
climbing fibers

7

Mossy fibers:

from spinal cord, reticular formation, and vestibular system ; convey information regarding sensory, equilibrium and motor information

8

Climbing fibers:

from inferior olivary neucleus; convey information regarding movement error

9

Three lobes of cerebellum:

Anterior
Posterior
Flocculonodular

10

Three groups of peduncles of cerebellum:

superior cerebellar peduncles
middle cerebellar peduncles
inferior cerebellar peduncles

11

Superior cerebellar peduncles

to midbrain

12

Middle cerebellar peduncles

receives input from pons

13

Inferior cerebellar peduncles

bidirectional

14

Cerebellar nuclei from medial to lateral are

Fastigial nucleus
Globose
Emboliform
Dentate

15

Vertically, the cerebellum can be divided into sections:

Midline vermis
Paravermal hemisphere
Lateral hemisphere

16

What are the three anatomic regions or functional divisions ?

vestibulocerebellum (flocculonodular lobe)
spinocerebellum
cerebrocerebellum

17

Three broad classes of human movement:

Elquilibrium
Gross movement of limbs
fine, distal, voluntary movement

18

Equilibrium:

Is regulated by the vestibulocerebellum (flocculonodular lobe) that receives information from vestibular receptors, and sends information to the vestibular nuclei; influence eye movements and postural muscles

19

Gross movements of limbs:

Are coordinated by the spinocerebellum which receives proprioceptive information from muscle spindles and visual and auditory information; control ongoing movements through medial and lateral motor tracts

20

Fine, distal, voluntary movements:

Are coordinated by the cerebrocerebellum that is related to processing in the cerebral cortex and coordinate movements via lateral motor tracts

21

Unilateral lesions of cerebellum affect:

same side of the body

22

Why are cerebellar signs ipsilateral?

1. output paths of medial tracts remain ipsilateral
2. cerebellar efferents project to contralateral cerebral cortex and red nucleus whose descending tracts cross the midline

23

Ataxia:

describes the uncoordinated voluntary, normal-strength, jerky, and inaccurate movements that are not due to hypertonia or contracture

24

What results in truncal ataxia?

Lesions to vermal and flocculonodular lobe

25

What do prarvermal lesions result in?

gait and limb ataxia

26

What do lateral cerebellar lesions result in?

hand ataxia

27

Limb ataxia resulting from spinocerebellar lesions has what manifestations:

dysdiadochokinesia
dymetria
action tremor

28

Dysdiadochokinesia

inability to rapidly pronate and supinate the forearm

29

Dysmetria:

inability to rapidly move an intended distance

30

Action tremor

shaking of the limb during voluntary movement

31

What can also produce ataxia?

Interference with transmission of somatosensory information to the cerebellum, either by lesions of the spinocerebellar tracts or by peripheral neuropathy,

32

What can also produce ataxia in lower limbs?

Sensory deficits or paravermal cerebellar lesions

33

How is cerebellar and somatosensory ataxia differentiated?

Romberg test, tests of proprioception, vibration sense, and ankle reflexes

34

What is the Romberg test:

Measures the ability to use proprioceptive information for standing balance

35

How is Romberg test performed?

Patient stands with his or her feet together, first with eyes open for 30 seconds and then with eyes closed for 30 seconds
pass or fail

36

What is criteria for failure of the Romberg test?

moving the arms to maintain balance, opening the eyes during the eyes closed section, beginning to fall, or requiring assistance

37

How do cerebellar limb ataxia individuals present in the Romberg test:

unable to stand with feet together, with or without vision, and have normal vibratory sense, proprioception, and ankle reflexes

38

How to sensory ataxia individuals present?

are able to stand steadily with feet together with eyes open for 30 seconds, but balance is impaired when the eyes are closed

39

What is impaired with sensory ataxia?

Conscious proprioception and vibratory sense are impaired, ankle reflexes are decreased or absent