Chapter 2

Question 1

outer ear

Answer 1

consists of the auricle and ear canal

Question 2

middle ear

Answer 2

the air-filled cavity behind the eardrum (aka tympanic cavity)

Question 3

ossicular chain

Answer 3

made of the malleus, incus and stapes, act as a bridge from the eardrum to the oval window, which is the entrance to the inner ear

Question 4

conductive system

Answer 4

the outer and middle ear together. primary function is to bring sound signal from air to inner ear

Question 5

sensorineural system

Answer 5

composed of the cochlea and 8th cranial nerve

Question 6

temporomandibular joint

Answer 6

the articulation with the mandible joint

Question 7

mandibular fossa

Answer 7

a depression located just below the base of the zygomatic process, accepts the condyle of the mandible to form the temporomandibular joint anterior to the ear canal

Question 8

petrous part

Answer 8

forms the base of the cranium, contains the inner ear and the internal auditory meatus through which the 8th cranial nerve travels to the brainstem

Question 9

mastoid part

Answer 9

composes the posterior portion of the temporal bone, contains an intricate system of interconnecting air cells

Question 10

helix

Answer 10

the ridged rim along most of the perimeter of the pinna

Question 11

intertragic incisure

Answer 11

the space or angle between the tragus and the antitragus

Question 12

manubrium

Answer 12

long, lateral process of the malleus, attaches almost vertically to the eardrum

Question 13

cone of light/light reflex

Answer 13

relection seen as a bright area on the anteroinferior surface of the eardrum

Question 14

middle ear tympanum/ tympanic cavity

Answer 14

the cavity in the temporal bone behind the tympanic membrane

Question 15

tegmen tympani

Answer 15

the thin bony plate that separates the tympanic cavity from the brain cavity above

Question 16

cochleariform process

Answer 16

a curved bony projection on the anterior/medial wall that points into the middle ear space

Question 17

stapedius muscle

Answer 17

the smallest skeletal muscle, contained within pyramidal eminence of tympanic cavity, innervated by facial (7th cranial) nerve

Question 18

acoustic reflex

Answer 18

the reflexive middle ear muscle contraction that occurs in response to high levels of sound stimulation

Question 19

protection theory

Answer 19

suggests the acoustic reflex protects the inner ear from potentially damaging sound levels
but this is unlikely because the reflex has a delay that would make it ineffective in protecting against sudden sounds

Question 20

fixation theory

Answer 20

holds that the middle ear muscles maintain the appropriate positioning and rigidity of ossicles

Question 21

accommodation theory

Answer 21

states the muscles modify the characteristics of the conductive system so that the absorption of sound energy is maximized

Question 22

eustachian tube

Answer 22

provides for the aeration and drainage of the middle ear system and makes it possible for air pressure to be the same on both sides of the eardrum (almost horizontal in young children)

Question 23

isthmus

Answer 23

the meeting point of the bony and cartilaginous portions of the eustachian tube

Question 24

ear canal resonance effect

Answer 24

sounds entering the ear will be enhanced if they are close to the resonant frequency range, resulting in a boost in the sound level pressure (SPL) reaching the eardrum

Question 25

head-related transfer function (HRTF)

Answer 25

shows how the sound reaching the eardrum is affected by the direction of the sound source relative to the head, shows how the spectrum is changed by the acoustical path from loudspeaker to eardrum

Question 26

basilar membrane

Answer 26

a fibrous membrane that runs horizontally from the osseous spiral lamina to the spiral ligament

Question 27

organ of Corti

Answer 27

the sensory organ for hearing and sits on the basilar membrane

Question 28

Resonance place theory

Answer 28

Helmholtz proposed that the basilar membrane was constructed of segments that resonated in response to different frequencies, and that these segments were arranged according to location along the length of the basilar membrane

Question 29

Temporal/frequency theories

Answer 29

claimed that the entire cochlea responds as a whole to all frequencies instead of being activated on a place-by-place basis

Question 30

volley principle

Answer 30

proposed that several neurons operating as a group could fire in response to each cycle of a high frequency sound, even though none of them can do so individually

Question 31

threshold

Answer 31

the faintest sound level that induces a response from a neuron

Question 32

characteristic frequency

Answer 32

the frequency at which the lowest threshold of a neuron occurs

Question 33

maculae

Answer 33

receptor organs of utricle and saccule

Question 34

phase locking

Answer 34

even though a neuron may not fire very often, when it does fire, it will do so in synchrony with a certain phase of stimulus

Question 35

traveling wave envelope

Answer 35

the overall shape of traveling wave displacement pattern along the basilar membrane

Question 36

instantaneous displacement

Answer 36

the moment-to-moment displacements of basilar membrane at various phases of the wave cycle

Question 37

compound action potential of auditory nerve

Answer 37

the combined response of a very large number of neurons firing synchronously in response to a sudden brief sound, like a click

Question 38

tonotopic organization

Answer 38

arrangement of frequency by place, occurs at all levels from the cochlea up to the cortex

Question 39

ampulla

Answer 39

widening at bases of semicircular canals

Question 40

crista

Answer 40

receptor organ of the ampulla

Question 41

cupula

Answer 41

gelatinous mass on crista blocks endolymph like swinging door in ampulla. Hair cell cilia extend into cupula

Question 42

distortional mechanism

Answer 42

primary inner ear mechanism, scala bestibuli has larger volume than scala tympani, so distortions of fluid-flilled capsule causes compensatory up and down displacements of basilar membrane

Question 43

compressional mechanism

Answer 43

supplements distortional mechanism, when compressed fluids push outward at oval and round windows, the traveling wave bulges more because it is more compliant. Hence, fluid is displaced downward toward the scala tympani, thus displacing the basilar membrane