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