Physio Lecture 6 Flashcards
What is the conduction pathway sequence?
tympanic membrane… malleus…. incus…. stapes…. oval window
What is bigger typanic membrane surface or area of stapes?
Tympanic membrane surface area is about 17 times that of the surface area of the stapes… 55mm to 3.2 mm -This increases the force from the ossicular lever system to the cochlear fluid by 22X -Fluid has greater inertia than air and requires this increase in force in order to cause vibration in the fluid
What do tympanic membrane and auditory ossicles provide?
the impedance matching btw the air and the fluid
How would hearing sensitivity be affected in the absence of the ossicular system and the tympanic membrane?
….
What does the tympani muscle do?
pulls handle of malleus inward
What does the stapedius muscle do?
pulls stapes outward
What effect do the above two opposing forces cause the ossicular system?
They work together to add rigidity to the ossicle system.
See the QUESTIONS set of note cards.
What is the function of this system( the attenuation reflex)?
…See questions Note cards… Katie S answered all the misc questions from the lectures that were in the book.
What effect do these two muscles have on a person’s sensitivity to his or her own speech?
…answered in the QUESTIONS set of cards
What consists of three side by side coiled tubes?
cochlea
What are the major components of the cochlea?
scala vestiviuli scala media scala tympani reissner’s membrane
What does the Reissner’s membrane do? (vestibular membrane)
separates scala media from scala vestibuli
What does the reissner’s membrane maintain?
a special fluid within the scala media
Because of the thinness of Reissner’s membrane?
the scala media and vestibuli are considered to be a single chamber as far as sound conduction is concerned
What does the basilar membrane separate?
scala media from scala typani
What does the basilar membrane consist of?
contains 20,000 to 30,000 fibers that project from the modiolus of the cochlea to the outer wall
Can the fibers of the Bailar membrane vibrate?
Yes
How are the fibers in the basilar membrane attached?
Distal ends of the fibers are not fixed but are embedded in the basilar membrane.
What does the length of the basilar fibers do from the oval window to the apex of the cochlea (helicotrema)?
the length increases
What happens to the length of the fibers from the oval window to the apex of the cochlea?
The fibers decrease.
What is the result of the short fibers near the oval window?
The stiff short fibers near the oval window be at a high frequency
What is the effect of the long fibers near the oval window?
The long limber fibers near the apex of the vibration at a low frequency.
Where does the high-frequency residents of the basilar membrane occur?
Near the base