Auditory System

Question 1

the bony labyrinth houses what sense organs?

Answer 1

auditory and vestibular sense organs (inner ear)

Question 2

what fluid is the membranous labyrinth filled with?

Answer 2

endolymph

Question 3

where is perilymph found?

Answer 3

outside the membranous labyrinth in the space between the bony and membranous labyrinths

Question 4

cochlea is part of the?

Answer 4

auditory apparatus

Question 5

2 parts of the vestibular apparatus

Answer 5

1. 3 semicircular canals or ducts

2. pair of otolith organs called utricle and saccule

Question 6

order that vibration is conveyed through middle ear

Answer 6

from tympanic membrane the vibration is conveyed to the malleus, incus, and then to the stapes

Question 7

T/F air pressure in the middle ear is normally equal to atmospheric pressure

Answer 7

True

the auditory or eustachian tube connects the middle ear to the nasal cavity

Question 8

stapes is in contact with the incus and ?

Answer 8

the oval window which is an opening in the cochlea

Question 9

3 parts of the cochlea and fluid they are filled with

Answer 9

1. scala vestibuli (perilymph)
2. scala tympani (perilymph)
3. scala media aka cochlear duct ( endolymph)

Question 10

what houses the organ of corti?

Answer 10

the cochlear duct (scala media)

Question 11

what causes the inward/outward movement of the round window?

Answer 11

vibration of the stapes onto the oval window puts pressure on the fluid in the scala vestibuli which sends pressure waves up, around, and down the scala tympani to the round window

Question 12

where do the hair cells of the organ of cori sit?

Answer 12

on the basilar membrane between the scala tympani and the scala media

Question 13

where do the scala tympani and the scala vestibuli meet?

Answer 13

helicotrema

Question 14

what are the hair cells of in the organ of corti innervated by?

Answer 14

afferent and efferent axons of CN VIII

Question 15

what cells are responsible for the transduction of mechanical vibration to neural impulses?

Answer 15

hair cells in the organ of corti

Question 16

what happens when the basilar membrane moves?

Answer 16

the basal part of the hair cells cause the stereocilia (on the apex of each hair cell which is embedded in the overlying stiff tectroral membrane) to bend and undergo an angular displacement in relation to their fixed tips

Question 17

the movement of the hair cells causes a (1) ___________ deformation which opens (2) _____________ in the hair cells and by flow of (3) _____________ carried by cations, generates a (4) ________________ in the hair cell

Answer 17

1. mechanical
2. ion channels
3. inward current
4. receptor potential

Question 18

the hair cells also release a neurotransmitter which depolarizes the peripheral component of the auditory portion of ?

Answer 18

CN VIII

Question 19

where do the cell bodies of CN VIII auditory neurons lie?

Answer 19

the spiral ganglion and synapse in the cochlear nuclei (medulla)

Question 20

Higher freguency sounds have their peak apmlitude near?

Answer 20

the base of the cochlea near oval window

Question 21

lower frequency sounds have their peak amplitude near?

Answer 21

apex or the helicotrema of the cochlea

Question 22

T/F A particular sound frequency will excite different hair cells along the cochlea

Answer 22

True - where the oscillation of the basilar membrane is maximal for that sound frequency

Question 23

Where are the shorter stiffer stereocilia located?

Answer 23

in the hair cells at the base of the cochlea while at the apex they are twice as long

Question 24

There is a single row of inner (1)___________ that detect sound and excite most afferents of (2) ____________; and (3) _______ of outer hair cells which can alter their length resulting in a change in (4)___________ of the local region in the organ of corti

Answer 24

1. hair cells
2. CN VIII
3. three rows
4. sensitivity or tuning

Question 25

action potentials traveling down the cochlear nerve reach what nuclei?

Answer 25

the dorsal and ventral cochlear nuclei in the upper medulla

Question 26

how are the nuclei organized/maintained in the auditory pathway

Answer 26

tonotopically organized

Question 27

Most fibers decussate where and ascend through?

Answer 27

decussate in the lower pons and ascend in the lateral lemniscus (some will synapse on neurons in the superior olivary nuclear complex and some in the reticular formation)

Question 28

what happens to the fibers that dont decussate?

Answer 28

they ascend uncrossed in the ipsilateral lateral lemniscus

Question 29

a unilateral lesion of the central auditory pathway causes?

Answer 29

more marked hearing loss on the opposite side of the lesion

Question 30

after the fibers leave the lateral lemniscus, they synapse in the _____________ and then go to the __________ of the diencephalon

Answer 30

1. inferior colliculus | 2. medial geniculate

Question 31

from the medial geniculate, where are axons sent?

Answer 31

now called auditory radiations, they are sent to the primary auditory cortex

Question 32

what part of the central auditory pathway is for conscious hearing of sound?

Answer 32

primary auditory cortex

Question 33

what part of the central auditory pathway is for orientation/localization of sound

Answer 33

superior olivary nucleus and inferior colliculus

Question 34

what part of the central auditory pathway is for CNS activation/alertness

Answer 34

reticular formation

Question 35

middle ear muscle that dampens vibration of tympanic membrane in response to loud noise

Answer 35

tensor tympani muscle (CN V)

Question 36

middle ear muscle that functions to dampen vibration of stapes in response to lound noise

Answer 36

stapedius muscle ( CN VII)

Question 37

what is the name of deafness that is caused by interruption of the passage of sound wave through the external or middle ear?

Answer 37

conductive deafness

Question 38

3 types of conductive deafness

Answer 38

1. obstruction 2. otosclerosis (most common, fixation of stapes due to excessive bone growth) 3. otitis media (ear infection)

Question 39

nerve deafness or perceptive deafness

Answer 39

sensorineural deafness

Question 40

5 cause of sensorineural deafness

Answer 40

1. disease of the cochlea 2. drugs/toxins 3. rubella infection in utero 4. presbycusis (occurs with age) 5. acoustic neuroma (schwannoma maybe located in the cerebellopontine angle)

Question 41

due to damage of CN V or CN VII, or tensor tympani/stapedius muscle, increase acuity of hearing and hypersensitivity to low frequency sounds

Answer 41

hyperacusis

Question 42

abnormal ringing, hissing, roaring, buzzing, humming

Answer 42

tinnitus

Question 43

due to overproduction of endolymph or inability to absorb endolymph symptoms: tinnitus and vestibular disturbances

Answer 43

meniere's syndrome/disease

Question 44

T/F lesions of the auditory cortex disrupt the perception of sound?

Answer 44

False - they do affect the ability to localize sounds in space, we can still hear the sounds but cant process them

Question 45

unilateral lesion of ascending auditory pathway causes?

Answer 45

bilateral diminution of hearing, more marked on contralateral side

Question 46

T/F lesions of the cental auditory pathways do not lead to total deafness unless they are bilateral?

Answer 46

True