(!!) Cochlea and Auditory Pathways

Question 1

(External ear)

1. The external auditory meatus (canal) is formed by what two cartilages? Short contribution from what bone?

Answer 1

1. auricular and annular cartilages; temporal bone

Question 2

(MIddle Ear)

1. Air filled tympanic cavity (including a ventrally expaned bulla) that features how many openings? How many are sealed are membranes?
2. What are the names of the four openings?

Answer 2

1. four, three

1) auditory tube
2) tympanic membrane
3) oval (vestibular) window
4) round (cochlear) window

Question 3

(Function of the Middle Ear)
1. Increases the efficiency of what?

2. Are pressure oscillations in air (sound waves) efficiently converted to pressure waves in fluid?
3. Middle ear components convert ____ amplitude, ____ force input into ____ amplitude, ____ force output (the middle ear matches ___ impedance input to ____ impedance output).

Answer 3

1. sound transmission
2. no
3. large, low, low, high, low, high

Question 4

(Functions of the Middle Ear Cont)
1. The tympanic membrane occupies a ____ area and undergoes a ____ excursion, offering ____ resistance to being vibrated by pressure waves.

2. The membrane of the oval window has a ____ area and makes ____ excursions against ____ resistance load (it must push against incompressible _____ fluid and the _______).
3. What do the ossicles form? What purpose do they serve?

Answer 4

1. large, large, low
2. small, small, high, perilymph fluid, round window
3. a lever system; collect energy from the large tympanic membrane and focus it on the small oval window membrane

Question 5

(Four Openings)

1) opening (not sealed) connects middle ear to the nasopharynx
2) separates tympanic cavity from external auditory meatus
3) separates the tympanic cavity from perilymph in the vestibule
4) separates tympanic cavity from perilymph in the scala tympani

Answer 5

1) auditory tube
2) tympanic membrane
3) oval (vestibular) window
4) round (cochlear) window