Physiology of Hearing and Balance

Question 1

Which part of the ear is the sound collector?

Answer 1

external ear

Question 2

Which part of the ear is the mechanical force amplifier?

Answer 2

middle ear

Question 3

Which part of the ear is the transducer/analyser?

Answer 3

inner ear

Question 4

Which part of the ear is shaped to receive sound?

Answer 4

external

Question 5

In the middle ear, what does the ossicular chain act as?

Answer 5

“lever arm” with varying efficiency (depending on frequency of sound

Question 6

What is the name of the bony and cartilaginous tube which is a ventilation pathway for middle ear mucosa?

Answer 6

eustachian tube

Question 7

What is the resting state of the eustachian tube?

Answer 7

closed

Question 8

What causes the eustachian tube to open?

Answer 8

tensor veli palatani and levator palatine muscles

Question 9

What equalises the ear?

Answer 9

eustachian tube

Question 10

What does dysfunction of the eustachian tube lead to?

Answer 10

middle ear negative pressure

Question 11

What are the two openings of the cochlea to the middle ear?

Answer 11

oval window and round window

Question 12

What do the two windows allow?

Answer 12

transmission of pressure wave in enclosed canal, and vibration of the basilar membrane

Question 13

Which part of the ear has a curved spinal lamina with 2 and a half turns around its centre medially?

Answer 13

inner ear

Question 14

In the cochlea, the scala media is suspended between what?

Answer 14

scala tympani and scala vestibuli

Question 15

Where are the coiled tubes of liquid?

Answer 15

cochlea

Question 16

What is the function of hair cells (stereocilia)?

Answer 16

transduction

turns bending force into an electrical impulse

Question 17

How are stereocilia arranged?

Answer 17

in height order with tip links connection them together

Question 18

What happens when the stereocilia are deflected towards the longest?

Answer 18

depolarisation in organ of corgi

Question 19

What happens when stereocilia are deflected away from longest?

Answer 19

hyperpolarisation

Question 20

What does depolarisation lead to?

Answer 20

8th nerve stimulation and activity in superior temporal gyrus

Question 21

Describe the structure of the inner ear.

Answer 21

Complex labyrinth structure
bony and membranous
5 key vestibular end organs

Question 22

How many otolith organs are there and what are they called?

Answer 22

2, utricle and saccule

Question 23

What type of rotations do otolith organs perceive?

Answer 23

straight line

Question 24

How many semicircular canals are there and what are they called?

Answer 24

3

ampullae of lateral, posterior and superior semicircular canals

Question 25

What type of rotations do semicircular canal organs perceive?

Answer 25

head rotation (angular)

Question 26

What degree of orientation is there in otolith organs?

Answer 26

360’

Question 27

What degree of orientation is there in semicircular canal organs?

Answer 27

90’

Question 28

What happens to stereocilia in semicircular canals?

Answer 28

bending causes stereocilia to deflect

Question 29

What happens to stereocilia in otolith organs?

Answer 29

movements perceived by hyper or depolarisation of hairs - when movement stops, firing stops

Question 30

Where does the cupula sit?

Answer 30

ampulla of SSC

Question 31

What otoconia?

Answer 31

calcium carbonate crystals (related to otolith organs)

Question 32

What is a vestibular schwannama?

Answer 32

tumour of VIII nerve sheath (schwann cells)

Question 33

Why does imbalance occur in a vestibular schwannama?

Answer 33

slowly progressive loss of function