The Middle Ear Disorders Flashcards
What is the purpose of the middle ear space?
It overcomes the impedance mismatch.
How does overcoming impedance mismatch occurs?
As sound transitions from an air-filled outer ear and middle ear to the fluid-filled cochlea, we will see a decrease in intensity. But since the size difference from our large TM to the small footplates of the stapes has the same amount of force being exerted on it, there’s going to be an increase the intensity
When does a 30dB drop occur?
When someone has missing ossicles and overcoming an impedance mismatch would not occur
What makes up the middle ear space?
- Malleus, Incus, Stapes
- Eustachian Tube
- Middle-ear cleft
- Cilia
What does the Eustachian Tube connect?
It connects the middle ear to the nasopharynx
What makes up the middle-ear cleft?
The eustachian tube + middle-ear
What is the middle-ear cleft lined with?
Mucous Membrane and Cilia
What’s the function of the cilia for the ME?
It has hairlike projections to help clean middle ear space
What does the cilia act like?
Cleaning conveyor-belt for the ME
For the Eustachian tube in adults, how is it positioned?
Downwards
For the Eustachian tube in children, how is it positioned?
What happens to their eustachian tube as they grow?
- It’s more horizontal
2. As their head grows, it will change and drop
What is the job of the eustachian tube?
It’s responsible for pressure equalization between outer and middle ear
For our eardrums, how should the pressure be?
Pressure should be the same behind the eardrum and in front of the eardrum
What allows our TM to move effectively?
If the pressure in front of and behind our eardrum is equal
Our eustachian tube is normally….
Closed
When does our eustachian tube open?
It opens when it realized the pressure behind our eardrum is not the same in front of ear drum
What are the natural ways our eustachian tube equalizes pressure?
- Yawning
2. Sneezing
What allows the equalization of the eustachian tube to happen effectively?
The angle of the eustachian tube
When the eustachian tube is horizontal, what occurs?
What does it mean for infections?
There isn’t good insertion of muscles to open and close the eustachian tube
We don’t have gravity on our side to drain the fluid from the eustachian tube
Is the mastoid part of the middle ear space?
Technically, no
How would you describe the mastoid?
As a “honeycomb” bone w/hundreds of air cells
What is the mastoid air cells lined with?
ONLY mucous membrane
What are two examples of non-auditory ME structures?
- Portion of facial nerve
2. Chorda tympani nerve
Why is it important to consider non-auditory ME structures?
IF things are going wrong with the ME space, anatomy needs to be considered to know that it’s not only hearing at stake
What are the muscles that exist in the ME?
- Stapedius Muscle
2. Tensor Tympani Muscle
Define the role of the stapedius muscle
Stapedius muscle contracts in the ME space when there’s sound.
Since the stapedius muscle contracts with sound, what happens when a loud sound is present?
The loud sound will tighten the ossicular chain and the loud sound wouldn’t get transferred
Which cranial nerve innervates the stapedius muscle?
Facial Nerve (CN VIII)
Which cranial nerve innervates the tensor tympani muscle?
Trigeminal Nerve (CN V)
When does the tensor tympani muscle tenses?
Only by tactile stimulation
When the stapedius muscle contracts it….
Attenuates low frequency sounds