Lecture 43 4/29/24

Question 1

What is the function of the stria vasculare?

Answer 1

makes the endolymph for the cochlea

Question 2

What are the characteristics of the organ of Corti?

Answer 2

-sits on basilar membrane
-hairs come up to tectorial membrane

Question 3

Which structures are present within the cochlea?

Answer 3

-scala vestibuli
-scala media
-scala tympani
-tectorial membrane
-basilar membrane
-vestibular membrane
-organ of Corti

Question 4

What happens in the organ of Corti that allows for louder sounds to be perceived?

Answer 4

-higher amplitude sound wave causes more movement of the basilar membrane
-increased basilar membrane movement triggers more hair cells
-the more hair cells triggered, the louder the noise

Question 5

What are the characteristics of the basilar membrane near the oval window?

Answer 5

-“base”
-narrow
-stiff
-greater movement with high frequency sound waves

Question 6

What are the characteristics of the basilar membrane far from the oval window?

Answer 6

-“apex”
-wide
-flexible
-greater movement with low frequency sound waves

Question 7

What is tonotopic organization?

Answer 7

-brain can tell where along the basilar membrane the triggered hair cells are located
-helps with determining high vs low frequency

Question 8

What is the role of the spiral ganglion?

Answer 8

receive input from the tectorial membrane and transmit it to the brain

Question 9

What is the relationship between number of coils in the cochlea and the range of sounds heard?

Answer 9

the greater the number of coils, the greater the range of frequencies heard

Question 10

How does ear position impact ability to hear sound?

Answer 10

ears that are closer together on the skull are able to hear higher frequency sounds

Question 11

What are the potential diseases of the inner ear?

Answer 11

-labyrinthitis/otitis interna
-noise-induced degeneration
-age-induced degeneration
-chemical degeneration
-cochlear dysgenesis/agenesis

Question 12

What is sensorineural deafness?

Answer 12

deafness due to the inability of the inner ear to process sound

Question 13

What can cause sensorineural deafness?

Answer 13

-disease of inner ear
-congenital problems of inner ear

Question 14

How does treatment differ between degeneration disease and genetic cochlear disease?

Answer 14

-degeneration disease treated with hearing aids
-genetic cochlear disease treated with cochlear implant

Question 15

What is the auditory cortex?

Answer 15

part of the cerebral cortex where the conscious perception of sound occurs

Question 16

How is sound processed in the brain, based on which ear heard it?

Answer 16

-left auditory cortex processes sound heard in right ear, and vice versa

Question 17

Why is hearing considered a learned response?

Answer 17

the temporal lobe learns patterns of sounds

Question 18

What are the characteristics of albinotic deafness?

Answer 18

-associated with decreased pigmentation
-due to failure of neural crest cell migration; lack of stria vasculare
-unable to produce endolymph in cochlea

Question 19

What are the characteristics of abiotrophic deafness?

Answer 19

-spontaneous death of sensory hair cells after normal development
-later onset than albinotic deafness
-super rare form

Question 20

How can hearing be assessed?

Answer 20

-physical exam
-behavioral responses
-electrodiagnostics

Question 21

How is the inner ear formed?

Answer 21

invagination of ectoderm to form the otic vesicle, which becomes the inner ear

Question 22

Which type of embryologic tissue forms the tympanic cavity?

Answer 22

endoderm

Question 23

Which type of embryologic tissue forms the middle ear ossicles?

Answer 23

mesoderm

Question 24

Which type of embryologic tissue forms the external ear canal?

Answer 24

ectoderm

Question 25

How does the cochlea work?

Answer 25

-sound waves first move through the scala vestibuli
-turn around and move through scala tympani
-sound waves in scala tympani are able to move the basilar membrane and activate organ of Corti
-hair cells in the organ of Corti come up to the tectorial membrane and can transmit to the membrane when sound waves cause movement in the hair cells