Chapter 6 - Questions

Question 1

What are the 4 gross division of the auditory system?

Answer 1

Outer ear, middle ear, inner ear, central auditory nervous system

Question 2

What are the 3 functions of the outer ear?

Answer 2

Protection, amplification, and localization

Question 3

What is the mode of operation for the outer ear?

Answer 3

Air vibration

Question 4

What are the 3 functions of the middle ear?

Answer 4

Impedance matching, selective oval window stimulation, pressure equalization

Question 5

What is the mode of operation for the middle ear?

Answer 5

Mechanical vibration

Question 6

What are the 2 functions of the inner ear?

Answer 6

Filtering distribution and transduction

Question 7

What are the 3 modes of operation in the inner ear?

Answer 7

Mechanical, hydrodynamic, and electrochemical

Question 8

What is the function of the central auditory nervous system?

Answer 8

Information processing

Question 9

What is the mode of operation for the central auditory nervous system?

Answer 9

Electrochemical

Question 10

What 4 parts does the peripheral auditory system include?

Answer 10

Outer ear, middle ear, cochlea, and auditory nerve

Question 11

Where is the peripheral auditory system located?

Answer 11

Mostly in the temporal bone and cranium

Question 12

What 5 parts does the central auditory system include?

Answer 12

Cochlear nucleus, lateral leminiscus, inferior colliculus, medial geniculate body, and the auditory cortex

Question 13

What is the anatomy of the pinna?

Answer 13

It is attached to the side of the head at an angle of 15-30 degrees; mainly made of cartilage and ligaments, with some muscles

Question 14

What is the physiology of the pinna?

Answer 14

It helps to spectrally ‘shape’ the sound; may help attenuate or boost certain frequencies; helps in localization of sound

Question 15

What is the anatomy of the external ear canal?

Answer 15

begins at the concha and extends inward and upward; entirely lined w/ skin (osseocartilagenous junction; first 1/3 is cartilage and medial 2/3 is bony)

Question 16

What is the physiology of the external ear canal?

Answer 16

conducts sound to the TM; protects the TM from trauma (humidity and temperature control); acts as a resonator tube (boost in the 2500 Hz region)

Question 17

What is the anatomy of the tympanic membrane?

Answer 17

concave disk-like structure; 3 layers: endoderm, mesoderm, and ectoderm; fibrous middle layer has spiral and radial fibers and is most important for structure

Question 18

What is the physiology of the tympanic membrane?

Answer 18

converts acoustic energy to mechanical energy

Question 19

What is the physiology of the outer ear?

Answer 19

pinna collects sound w/ frequecies around 5000 Hz; shapes high frequency sounds, aids in localization (especially height) of sound; external canal acts as a resonator (around 2500 Hz)

Question 20

What are 2 hazards of cotton swabs?

Answer 20

impacted cerumen and puncturing the TM

Question 21

What are the 5 structures of the middle ear?

Answer 21

stapes, incus, malleus, eardrum, and eustachian tube

Question 22

What is the anatomy of the middle ear?

Answer 22

oval and air-filled space; 2 cm^3 volume; has 2 main areas, the tympanic cavity and the attic/epitympanic recess

Question 23

What is the anatomy of the eustachian tube?

Answer 23

at a 30-45 degree angle from the anterior wall of the middle ear cavity to the posterior wall of the nasopharynx; underlying tissue: superior 1/3 is bone and the inferior 2/3 is cartilage; at rest the cartilaginous portion is closed, but opens due to action of two muscles: levator veli palatini and tensor veli palatini

Question 24

What is the physiology of the eustachian tube?

Answer 24

it is normally closed and opens periodically; when it opens: fresh air is supplied to the middle ear cavity, pressure is equalized, and small amounts of fluid in the ME drain down into the nasopharynx

Question 25

What is the physiology of the ossicles?

Answer 25

provide an impedance-matching function (air to fluid)

Question 26

What are the two structures of the malleus?

Answer 26

Manubrium and head

Question 27

What are the two structures of the incus?

Answer 27

head and lenticular process

Question 28

What are the two structures of the stapes?

Answer 28

Head/neck, crura, and footplate

Question 29

Order these structures from most medial to most lateral: incus, pinna, malleus, oval window, tympanic membrane, external auditory canal, stapes

Answer 29

Oval window, stapes, incus, malleus, tympanic membrane, external auditory canal, pinna

Question 30

Why does there need to be an impedance match between outer ear and inner ear?

Answer 30

the middle ear helps overcome the impedance mismatch between the outer ear and inner ear

Question 31

What are the three processes of the middle ear that help overcome the impedance mismatch

Answer 31

1) area advantage of TM to oval window, 2) lever action of ossicular chain, 3) buckling action of the TM

Question 32

What is the area advantage of the TM to the oval window?

Answer 32

The surface area of the TM is 17 times the size of the oval window

Question 33

What is the lever action of the ossicular chain result in a mechanical advantage of?

Answer 33

1.3:1

Question 34

The combined effects of the surface area difference and the lever action result in what increase in pressure at the oval window?

Answer 34

23 fold

Question 35

How does buckling action of the TM work?

Answer 35

the TM is cone shaped and the buckling causes increased movement in the region of the umbo, which causes more movement of the ossicular chain, doubling the force of the mechanical vibration

Question 36

What are the two middle ear muscles?

Answer 36

Stapedius and tensor tympani

Question 37

What are the two problems of the ear that the ossicular chain solve?

Answer 37

1) impedance mismatch, 2) round and oval windows both deflect in the same direction

Question 38

What problem of the ear does the eustachian tube solve?

Answer 38

The middle ear cavity cannot be closed