Vestibular Anatomy Flashcards Preview

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Flashcards in Vestibular Anatomy Deck (53):
1

Signs and Symptoms of Vestibular Dysfunction

Dizziness
Blurry Vision
Nystagmus
Tinnitus
Vertigo
Hearing loss
Loss of balance & possible falls
Broad-based stance (to accommodate for imbalance)
Sweating, nausea, and vomiting (due to ANS involvement)

2

What are the two main reflexes of the vestibular system?

VOR: Vestibulo-ocular Reflex
VSR: Vestibulo-spinal Reflex

3

What are head movements detected by?

cupula

4

Vestibulo Ocular Reflex

Stabilizes eye in space
Necessary to see while head is in motion

5

Components of VOR:

angular and linear VOR

6

Vestibulo-Spinal Reflex

Stabilizes body
Helps maintain desired orientation to environment

7

Cervical Reflexes

cervicoocular reflex
cervicocollic reflex
cervicospinal reflex

8

Cervicoocular Reflex (COR)

Weak reflex
Does not play direct role in gaze stability
May help VOR to compensate
Proprioceptors and somatosensory receptors
-C1-C2 dorsal nerve roots

9

Cervicocollic Reflex (CCR)

Provides head stability
Contraction of stretched muscles to align head

10

Cervicospinal Reflex (CSR)

acts in conjuction with the VSR
-provides postural stability through limb activation

11

Three axes of rotation:

roll
pitch
yaw

12

Three axes of translation

AP
lateral
vertical

13

Pitch:

up and down

14

Yaw

head movement side to side in horizontal plane (shaking head no)

15

Roll

lateral side bending

16

What do semicircular canals detect?

angular rate

17

What do otoliths (saccule and utricle) detect?

linear acceleration

18

Functions of peripheral vestibular system:

Stabilization of visual images on the fovea of the retina during head movement to allow clear vision
Maintain postural stability especially during movement of the head
Provide information used for spatial orientation

19

Peripheral vestibular components:

Semicircular canals (SCC)
Utricle
Saccule
CN VIII: Vestibulocochlear nerve

20

Orientation of semicircular canals:

Anterior/superior
Lateral/horizontal
Posterior/inferior

21

What are the components of the labyrinth?

bony
membranous

22

Bony labyrinth:

3 semicircular canals
cochlea
vesitbule

23

What is the bony labyrinth filled with?

perilymphatic fluid (similar to cerebral spinal fluid)

24

What is the membranous labyrinth?

suspended within the bony section and contains membranous portions of the canals and utricle and saccule

25

What is the membranous labyrinth filled with?

endolymphatic fluid (similar to intracellular fluid)

26

Ampulla:

contain the cupula (hair cells) which convert displacement into neuro firing thru bending of hair cells

27

What does ampulla detect?

linear/angular motion

28

Otolith Organ

(Utricle and Saccule): contain calcium carbonate crystals called otoconia

29

What does otolith organ detect?

gravity and acceleration

30

Sensory organ of angular VOR:

Semi-Circular Canals:
Horizontal
Anterior
Posterior

31

Which direction do eyes move with angular movement?

opposite

32

Pitch is sensed by what?

anterior/posterior canals

33

Yaw is sensed by what?

horizontal canals

34

Sensory organ of linear or translation VOR

Otoliths:Saccule and Utricle

35

Which direction do eyes move with linear movement?

opposite

36

What does the saccule detect?

Linear movement up and down (riding in elevator)

37

What does the utricle detect?

Linear movement horizontally (riding on a train on a straight track

38

Sensory organ of ocular tilt reflex:

Otolith:Utricle

39

What direction do eyes and head move in ocular tilt reflex?

opposite tilt of head

40

What does head tilt to the left cause?

elevation of the left eye, depression of the right eye, torsion of both eyes to the right and the tilt of the head on the body to the right.

41

What facial nerves does ocular motor nuclei travel for mediation of VOR?

III,IV,VI

42

What are the target for vestibular input?

Vestibular Nuclear Complex
The cerebellum

43

What does the cerebellum do?

back-up system for adaption of gain of VOR
Monitors vestibular performance and readjusts central vestibular processing if necessary

44

VOR (Vestibular Ocular Reflex):

generates eye movements, which enables clear vision while head is in motion

45

VSR (Vestibular Spinal Reflex):

generates compensatory body movement in order to maintain head and postural stability, thereby preventing falls

46

VCR (Vestibular Collic Reflex):

stabilizes the head in space

47

Function of vestibular system:

stabilizes vision when head moves (VOR)
balance control (VSR)

48

What does visual acuity depend on:

position of image on fovea
ability to hold image steady

49

Position of image: gaze shifting

for best vision, object within 0.5 of center of fovea
fovea must be moved to achieved proper poistion for vision
saccades, pursuits, vergence eye movement

50

Holding image steady, gaze holding

optokinetic, visual fixation, vergence and vestibular eye movements

51

Components of balance control:

gaze stabilization system
postural stabilization system

52

Gaze Stabilization System

maintains gaze direction of the eyes and visual acuity during activities involving active head and body movements

53

Postural Stabilization System

keeps the body in balance while an individual stands and actively moves in daily life