Vestibular Nervous System

Question 1

What are the 3 source of balance information?

Answer 1

1.) Vestibular organ
2.) Visual system
3.) Proprioception

Question 2

What fluid fills almost all of the vestibular structures?

Answer 2

Endolymph

Question 3

Where is endolymph secreted?

Answer 3

Endolymphatic sac into the labyrinth through the vestibular aqueduct

Question 4

What 3 things are the vestibular organ comprised of?

Answer 4

1.) Saccule
2.) Utricle
3.) Semi-circular canals

Question 5

What are the 3 semi-circular canals?

Answer 5

1.) Anterior
2.) Posterior
3.) Lateral/Horizontal

Question 6

What are the 3 types of rotational movement?

Answer 6

1.) Roll
2.) Yaw
3.) Pitch

Question 7

What movement is like a cartwheel?

Answer 7

Roll

Question 8

What movement is like a front flip?

Answer 8

Pitch

Question 9

What movement is like spinning?

Answer 9

Yaw

Question 10

What is the ampullae?

Answer 10

Bulge near the base of the semi-circular canals

Question 11

What is the cupula?

Answer 11

Gelatinous interior of the ampulla

Question 12

Where do hair cells sit inside of an ampulla?

Answer 12

On top of the crista

Question 13

What causes the cupula to change shape?

Answer 13

Endolymph movement caused by head movement

Question 14

What is the purpose of the shape change in the cupula?

Answer 14

Hair cell stereocilia deflection

Question 15

What is the resting charge of a vestibular hair cell?

Answer 15

-60mV

Question 16

What is depolarized and hyperpolarized with leftward yaw movement?

Answer 16

1.) Depolarization of left horizontal canal
2.) Hyperpolarization of right horizontal canal

Question 17

What are the otolith organs?

Answer 17

Saccule and Utricle

Question 18

What does the utricle respond to?

Answer 18

Horizontal acceleration

Question 19

What does the saccule respond to?

Answer 19

Vertical acceleration

Question 20

What is otoconia?

Answer 20

Calcium carbonate crystals that sit atop the gelatinous layer

Question 21

What are macula?

Answer 21

Surface of the otoliths that contain the HCs

Question 22

What do otoconia provide?

Answer 22

Inertial mass

Question 23

How are the HCs deflected in the saccule/utricle?

Answer 23

1.) HC stereocilia are embedded in the gelatinous layer
2.) Otoconia provide inertial mass
3.) As head accelerates, otoconia move and change shape of the gelatinous layer

Question 24

Where are otoconia not found?

Answer 24

Semi-circular canals

Question 25

Why do the otoliths respond to linear movement, but not the SCC?

Answer 25

The added mass contributed by the otoconia allow the otoliths to respond to linear acc

Question 26

What is BPPV?

Answer 26

Common vertigo diagnosis thought to occur from otoconia dislodging from otoliths that settle in SCC

Question 27

What is scarpa's ganglion?

Answer 27

Collection of vestibular afferent neurons that connect to HCs and are the neurons that comprise the vestibular nerve

Question 28

What does the superior portion of the vestibular nerve do?

Answer 28

Carries afferent info from utricle, anterior SCC, and lateral SCC

Question 29

What does the inferior portion of the vestibular nerve do?

Answer 29

Carries information from the posterior SCC and saccule

Question 30

Where does the vestibular nerve travel to?

Answer 30

Vestibular nuclei of the brainstem and cerebellum

Question 31

Where does the cerebellum output to?

Answer 31

Vestibulospinal tract?

Question 32

What are 8 places that the vestibular nuclei input/output with?

Answer 32

1.) Vestibular nerve 2.) Contralateral vestibular nuclei 3.) Cerebellum 4.) Reticular formation 5.) Spinal cord 6.) Eye motor nerves 7.) Limbic system 8.) Autonomic NS

Question 33

What are the 2 divisions of the vestibulospinal tract?

Answer 33

Medial and lateral

Question 34

What does the vestibulospinal tract do?

Answer 34

Maintains reflexive posture and balance Influence effectors through SC

Question 35

How does the medial pathway travel?

Answer 35

Bilaterally

Question 36

What does the medial pathway control?

Answer 36

Neck and trunk

Question 37

How does the lateral pathway travel?

Answer 37

Ipsilaterally

Question 38

What does the lateral pathway control?

Answer 38

The limbs

Question 39

What is the vestibulospinal reflex?

Answer 39

Helps maintain postural control through constantly changing muscle tension

Question 40

What does the vestibulo-ocular reflex do?

Answer 40

Stabilizes the retinal images during head movement

Question 41

How will the eyes travel with the VOR?

Answer 41

Eyes will move in direction opposite of head rotation

Question 42

What does VNG testing do?

Answer 42

Exploit the VOR to look for nystagmus

Question 43

What is nystagmus?

Answer 43

Rhythmic beating of the eyes

Question 44

What are 3 types of VNG testing?

Answer 44

1.) Oculomotor testing 2.) Positional/Postural testing 3.) Caloric testing

Question 45

What is caloric testing?

Answer 45

Stimulates the horizontal SCC to induce nystagmus and check suppressibility

Question 46

What is COWS?

Answer 46

Cold Opposite, Warm Same

Question 47

Why is the cerebellum crucial for motor learning in VOR?

Answer 47

The smallest instinctual movements made in the eyes to compensate for the movement of the head

Question 48

What is rotary chair testing used for?

Answer 48

Higher-end vestibular dysfunction testing; cerebellar dysfunction

Question 49

What is the vestibulocollic reflex?

Answer 49

Muscle action to stabilize head following impact or sudden movement

Question 50

What is VEMP testing?

Answer 50

Uses high level sound to stimulate the saccule to see if it reacts to an impact or sudden movement

Question 51

What is the sono-motor reflex?

Answer 51

Muscle action induced by sound stimulation