Auditory and Vestibular System

Question 1

What is endolymph composition similar to?

What is perilymph composition similar to?

Answer 1

endolymph: extracellular fluid
perilymph: CSF (continuous with subarachnoid space thru the cochlear aqueduct)

Question 2

What do you call the part of the bony labyrinth that covers the utricle and the sacule?

Answer 2

vestibule

Question 3

What does the perilymph fill?

Answer 3

the bony labyrinth

Question 4

What does the endolymph fill?

Answer 4

the membranous labyrinth

Question 5

What is a possible cause for meniere’s disease?

Answer 5

obstruction of flow of endolymph

Question 6

What are they symptoms of meniere’s disease?

Answer 6

transient attacks of vertigo, nausea, hearing loss, tinnitus (ear ringing)

Question 7

What is the name for the tallest stereocilia of a hair cell?

Answer 7

kinocilium

Question 8

T/F: cochlear hair cells lack kinocilium.

Answer 8

True

Question 9

What does deflection of stereocilia away from the tallest stereocillium cause?

Answer 9

hyperpolarization of hair cell.

Question 10

What does deflection of sterocilia towards the tallest stereocillium cause?

Answer 10

depolarizes hair cell

Question 11

What does deflection of stereocilia towards the tallest stereocilium in a perpendicular plan cause?

Answer 11

no effect; no receptor potential results

Question 12

What does the stapedius muscle do?

Answer 12

pulls the stapes away from the oval window; stiffens the ossicular chain
blocks sound of own voice

Question 13

What innervates the stapedius muscle?

Answer 13

VII

Question 14

What does the tensor tympani do?

Answer 14

pulls the malleus in toward the middle ear; stiffens the ossicular chain
blocks chewing sound
can spasm - causing tinnitus at low frequency

Question 15

What innervates the tensor tympani?

Answer 15

V

Question 16

What is the primary ascending auditory pathway?

Answer 16

Lateral lemniscus

Question 17

Which colliculus is important in the auditory pathway? Superior or inferior?

Answer 17

inferior

superior is important for retina/visual cortex

Question 18

What nucleus is important for distinguishing sound location?

Answer 18

superior olivary nucleus

Question 19

Where do auditory fibers cross the midline?

Answer 19

trapezoid body

Question 20

Where might a defect occur when testing for air conduction?

Answer 20

outer, middle, or inner ear

Question 21

Where might a defect occur when testing for bone conduction?

Answer 21

likely a sensorineural problem or a result of ototoxic medications
(bone conduction bypasses ear as skull can transmit sound waves to fluid in labyrinth)

Question 22

What two different types of hearing loss are there?

Answer 22

conduction problem

sensorineural problem

Question 23

If there is normal bone conduction but not normal air conduction, what type of hearing loss does this suggest?

Answer 23

conductive hearing loss

middle ear infection

Question 24

What type of motion does the utricle detect?

Answer 24

forward-backward

side-to-sdie

Question 25

Wha type of motion does the saccule detect?

Answer 25

forward-backward

up-down

Question 26

How is the macula oriented in the saccule when the head is upright?

Answer 26

vertical

stereocilia face laterally

Question 27

How is the macula oriented when head is upright?

Answer 27

horizontally

stereocilia face up

Question 28

What makes the otolithic membrane denser than the endolymph?

Answer 28

calcium carbonate crystals
otoconia
otoliths

Question 29

What is the vestibular system responsible for?

Answer 29

maintaining posture

coordinate eye and head movements

Question 30

What do vestibulospinal fibers in the medial VS tract control?

Answer 30

stabilize head movement as we walk

coordinate head and eye movement

Question 31

What do vestibulospinal fibers in the lateral VS tract control?

Answer 31

postural changes to accomodate titles in body

Question 32

What is the vestibuloocular reflex?

Answer 32

controls eye movements while the head is in motion (naturally, there is always some slight movement of the head occurring) and prevents images from moving across the retina

Question 33

What is (are) the afferent limb for the vestibuloocular reflex?

Answer 33

VIII, vestibular division

Question 34

What is (are) the efferent limb for the vestibuloocular reflex?

Answer 34

III, IV, VI

Question 35

What are the inerneuronal connections associated with

Answer 35

vestibular nuclei to MLF to III, IV, VI and reticular formation

Question 36

If you begin to spin to the left, what will happen?

Answer 36

left semicircular duct is excited (right duct is hyperpolarized)
right lateral rectus and left medial rectus muscles contract
left lateral rectus and right medial rectus are inhibited (interneurons)

Question 37

What happens if the VOR can’t compensate for head movements?

Answer 37

VOR is interrupted by rapid eye movements in the opposite direction
(back and forth eye movements with a rapid phase in one direction and a slow phase in the other)

Question 38

What happens to balance as a result of alcohol consumption?

Answer 38

blood alcohol increases, EtOH leaves capillaries, infiltrates cupulae, density decreases relative to endolymph;
relative nystagmus results
creates illusion of movement (positional vertigo)

Question 39

What senses are needed for position sense?

Answer 39

vestibular, proprioceptive and visual systems

Question 40

What does the cochlea detect?

Answer 40

sound

Question 41

What do the semicircular ducts detect?

Answer 41

angular acceleration

Question 42

What do the saccule and utricle detect?

Answer 42

linear acceleration