Chapter 52

Question 1

Which window does the stapes push on?

Answer 1

Oval window

Question 2

What muscle (mainly) contracts to attenuate loud sounds?

Answer 2

Stapedius

Question 3

What are the three tubs that make up the Cochlea?

Answer 3

• Scala Vestibule
• Scala media
• Scala tympani

Question 4

What separates the vestibuli and the tympani?

Answer 4

-Reissner membrane

Question 5

What separates the tympani and the media?

Answer 5

the basilar membrane

Question 6

What is found within the basilar membrane?

Answer 6

Organ of corti

Question 7

What is the tonotopy, or layout of frequency sensitivity in the choclea as distance from the stapes increases?

Answer 7

• As disnace from the stapes increases:
• frequency decreases
• High frequency is heard at the base and low frequency at the helicotrema

Question 8

How does bending of the stereocilia towards the larger stereocilia result in depolarization?

Answer 8

• bending of the smaller cilia towards larger ones results in tugging of the smaller cilia out of the hair cell surface
• tugging on these tip links opens channels for K+ to influx from the surrounding scala and depolarize the hair cell

Question 9

How is frequency determined?

Answer 9

Tonotopy: stimulation of hair cells near the base of the cochlea indicate a high pitch sound while stimulation of the hair cells at the apex indicate a low pitched sound

Question 10

How is loudness determined?

Answer 10

• The higher the amplitude the more the basilar membrane vibrates, and the more the hair cells excite the nerve endings
• spatial summation allows for better judgement of loudness

Question 11

What are the two principle methods used to determine sound direction?

Answer 11

1. lag time between ears
2. difference in intensities between ears

Question 12

When does the lag time method of direction determination work best? How about intensity differences?

Answer 12

• frequencies below 3000Hz
• Higher frequencies

Question 13

What is nerve deafness?

Answer 13

-impairment of the cochlea, auditory nerve, or CNS

Question 14

What does it mean when someone has conduction deafness?

Answer 14

The cochlea is intact but the structures that conduct the sound to the cochlea are not.

Question 15

What type of sound is lost in old age deafness? (air conduction or bone conduction)

Answer 15

-Both air conduction and bone conduction of the higher frequencies

Question 16

What type of conduction is affected in middle ear sclerosis? At what frequencies?

Answer 16

-exclusively air conduction at lower frequencies