Auditory System

Question 1

What bone is the ear found in?

Answer 1

The petrous portion of the temporal bone

Question 2

What is the function of the outer ear?

Answer 2

Capture sound and focus it on the tympanic membrane
Amplify some frequencies via resonance in the canal
Protect the ear from external threats

Question 3

What is the function of the middle ear?

Answer 3

Focusing vibrations from large surface area to smaller surface area (this increases pressure)

Question 4

What is the function of the inner ear? What structure performs these functions?

Answer 4

The cochlea:
Transduces vibration into nervous impulses
Analyses frequencyand intensityof the sound

Question 5

What are the 3 parts of the cochlea?

Answer 5

Scala vestibuli
Scala tympani
Scala media

Question 6

What in the cochlea contains perilymph? What are the characteristics of perilymph?

Answer 6

Scala vestibuli and typmani, perilymph is high in sodium

Question 7

What in the cochlea contains endolymph? What are the characteristics of endolymph?

Answer 7

Scala media, endolymph is high in potassium

Question 8

Where is the organ of corti located?

Answer 8

In the scala media in the cochlea

Question 9

What is the basilar membrane?

Answer 9

Where the organ of corti lies

Question 10

How is the basilar membrane arranged? What does this mean

Answer 10

Arranged tonotopically

It is sensitive to different frequencies at different points along its length

Question 11

What 2 types of hair cells are found in the organ of corti? How are they arranged?

Answer 11

Inner hair cells arranged in one column

Outer hair cells arranged in 3 columns

Question 12

How are hairs in the organ of corti deflected?

Answer 12

The tectorial membrane lies above them and allows deflection which then depolarises the cell

Question 13

What information do the inner hair cells carry and what is their function?

Answer 13

Afferent info

Their function is the transduction of the sound into nerve impulses

Question 14

What information do the outer hair cells carry and what is their function?

Answer 14

Efferent info

Their function is modulation of the sensitivity of the response.

Question 15

What hairs of hair cells in the ear called?

Answer 15

Stereocilia

Question 16

Describe how transduction of sound occours in relation to hair cells?

Answer 16

Stereocilia deflect towards the longest cilium, opening K+ channels
Inflow of K+ depolarises the cell and neurotransmitter is released
Louder sounds causes greater deflection

Question 17

Describe the auditory pathway

Answer 17

Spiral ganglions from the cochlea project to the ipsilateral cochlear nuclei, the info crosses at the superior olive level then all connections are bilateral

Question 18

What is the human range of hearing for frequency?

Answer 18

20–20,000Hz

Question 19

What is the human range of hearing for loudness?

Answer 19

0 dB to 120 dB

Question 20

What are the main assessments for hearing?

Answer 20

Audiometry
Tuning fork
Central processing assessments

Question 21

When are tuning forks used as an assessment for hearing?

Answer 21

To establish absence or presence of hearing when audiometry isn’t available

Question 22

What is pure tone audiometry?

Answer 22

Measuring hearing acuity for variations in sound intensity and frequency performed using an audiometer

Question 23

What is a central processing assessment?

Answer 23

Assessment of hearing abilities other than detection

Question 24

What is tympanometry?

Answer 24

Examination used to test the condition of the middle ear and mobility of the eardrum (tympanic membrane) and the conduction bones

Question 25

What are otoacoustic emissions (OEAs)?

Answer 25

The low intensity sounds a cochlea produces

Question 26

How are OEAs used in newborns?

Answer 26

They are assessed in newborns to screen their hearing ability or measure progression of hearing loss

Question 27

What type of electrical activity does electrocochleography measure?

Answer 27

From the cochlear and vestibulocochlear nerve

Question 28

What type of electrical activity does auditory brainstem response measure?

Answer 28

From the vestibulocochlear nerve and brainstem nuclei/tracts

Question 29

What type of electrical activity do late responses measure?

Answer 29

From the primary auditory and association cortex

Question 30

What are the 3 types of hearing loss?

Answer 30

Conductive Sensorineural Mixed

Question 31

Where is the problem located in conductive hearing loss?

Answer 31

Outer or middle ear

Question 32

Where is the problem located in sensorineural hearing loss?

Answer 32

Inner ear or auditory nerve

Question 33

Where is the problem located in mixed hearing loss?

Answer 33

Affects more than one part

Question 34

What about sound is effected in mixed hearing loss?

Answer 34

Conduction and transduction

Question 35

How can hearing loss be classified?

Answer 35

Mild, moderate, severe or profound

Question 36

What are some causes of conductive hearing loss?

Answer 36

Wax or foreign body Otitis (bubbles in eardrum) Otosclerosis

Question 37

What are some causes of sensorineural hearing loss?

Answer 37

Presbycusis Ototoxicity Nerve VIII tumor

Question 38

What are the 3 main treatments for hearing loss?

Answer 38

Hearing aids Cochlear implants Brainstem implants

Question 39

What do hearing aids do?

Answer 39

Amplify sound but do not replace any structure

Question 40

What do cochlear implants do?

Answer 40

Replaces the function of the hair cells by receiving sound, analysing it, transform it into electrical signals and sending an electric impulse directly to the auditory nerve

Question 41

What do cochlear implants need to work?

Answer 41

A functioning auditory nerve

Question 42

What do brainstem implants do?

Answer 42

The electrical signals can be sent to a set of electrodes placed directly into the brainstem

Question 43

When are brainstem implants used?

Answer 43

When auditory nerves are affected

Question 44

How risky are brainstem implants?

Answer 44

Very risky, should only be used if people have bitemporal auditory nerve damage