Physiology of Hearing and balance

Question 1

What causes sound?

Answer 1

Oscillating molecules

Question 2

What does frequency dictate?

Answer 2

Pitch

Question 3

What does amplitude dictate?

Answer 3

Intensity

Question 4

What frequencies can humans perceive?

Answer 4

20Hz - 20,000Hz

Question 5

How does the middle ear act as an amplifier mechanism?

Answer 5

Ossicular chain acts as piston or lever arm with varying efficiency depending on frequency of sound transmitted

Question 6

What is the tympanic membrane: OW ratio?

Answer 6

18:1

Question 7

What is the eustachian tube?

Answer 7

Ventilation pathway for middle ear mucosa

Question 8

What is the eustachian tube made up of?

Answer 8

Bone and Cartilage

Question 9

What opens the eustachian tube?

Answer 9

Tensor veli palatini

Levator palatine muscles

Question 10

What can eustachian tube dysfunction lead to?

Answer 10

MIddle ear negative pressure

Question 11

What are the oval and round windows?

Answer 11

Openings of the cochlea to the middle ear

Question 12

What do the windows permit?

Answer 12

Transmission of pressure wave in enclosed canal and vibration of the basilar membrane

Question 13

Where is the scala media found?

Answer 13

Suspended in between scala tympani and scala vestibuli

Question 14

What is the cochlea?

Answer 14

Coiled tubes of liquid

Question 15

Which part of the cochlea has a different ionic composition?

Answer 15

Scala media

Question 16

Where is the auditory area?

Answer 16

Primary auditory cortex in the temporal lobe

Question 17

When can a foetus hear sound?

Answer 17

18 weeks

Question 18

When can a foetus respond to sound/voice?

Answer 18

26 weeks

Question 19

What % of infants have profound hearing loss?

Answer 19

1/1000

Question 20

How does the universal neonatal screening test hearing?

Answer 20

The outer hair cells produce sounds which will respond to stimulus

Question 21

What should children be able to do by 3 months?

Answer 21

Cooing

Recognising mothers voice

Question 22

What should children be able to do by 6 months?

Answer 22

Babbling
Turns to sound or eyes towards sound
Makes happy and sad sounds

Question 23

What should children be able to do by 12 months?

Answer 23

May make simple noises, mama/dada

Turns to sound

Question 24

What should children be able to do by 18 months?

Answer 24

Says a few words
Colours
Animal sounds
Recognises body parts
Simple commands

Question 25

What should children be able to do by 24 months?

Answer 25

Two word phrases, 50+ words | Understands questions and follows commands

Question 26

What should children be able to do by 36 months?

Answer 26

Use 3 word sentences, aware of rhyme, start with adjectives, understand order, positioning

Question 27

What 6 systems contribute to balance?

Answer 27

``` Visual Proprioceptive Vestibulospinal tract Cardiovascular Vestibular Vestibulo-ocular reflex ```

Question 28

What does the Superior vesicular nerve supply?

Answer 28

Lateral/Anterior SCC and utricle

Question 29

What does the Infetior vesicular nerve supplY?

Answer 29

Posterior SCC and saccule

Question 30

What are the 2 hair cells of the inner ear?

Answer 30

Kinoclium and stereocilia

Question 31

What is the resting potential of the hair cells of the inner ear?

Answer 31

Resting potential 90 spikes/sec

Question 32

How are otolith organs oriented?

Answer 32

At right angles to eachother

Question 33

Where is the capula found?

Answer 33

Ampulla of SCC

Question 34

What causes deflection of the SCC?

Answer 34

Movement of the perilymph

Question 35

What causes the stereocilia to deflect?

Answer 35

Bending

Question 36

What happens when one side is excited?

Answer 36

The other is inhibited

Question 37

What is the vestibulo-ocular reflex involved in?

Answer 37

Focusing on an object when the head is moving

Question 38

When would the brain percieve rotation when stationary?

Answer 38

When a patient has lost one ear Brain sees high stimulus from the working side and no stimulus from the other side, so eyes flicker causing the patient to become dizzy

Question 39

What do the central pathways have outputs to?

Answer 39

Vestibulospinal tract Medial longitudinal fasciculus and ocular muscles Medial lemniscus and thalamus to cerbrum