Exam #2 Flashcards
Where are other places in the ear, that we can find/ measure a simple periodic wave? (They all mimic a sound wave)
TM, malleus, incus, stapes footplate, basilar membrane, and (if it were possible) hair cell movement.
What three things are determined by impedence?
- Mass
- Stiffness
- Friction of the medium
What is the equation for The Area Trick or Condensation Effect?
Pressure (E) = Force (F)/ Area (A)
The labyrinth contains what two sensory systems?
Vestibular System & Auditory System
The membranous labyrinth portion of the cochlea consists of what two membranes?
Basilar Membrane & Reissner’s Membrane
The tympanic membrane is composed of what three layers?
The Epithelium, The Mucous Membrane, & The Fibrous Layer
What are the six surfaces of the tympanic cavity, what are they?
Superior, Inferior, Anterior, Posterior, Medial & Lateral
Where is the superior surface of the Tympanic Cavity, and what structures are located on the surface?
The superior surface means “above” or “on top”.
Structures: NONE!!
Where is the lateral surface of the Tympanic Cavity, and what structures are located on the surface?
Lateral means “Away from midline of the body”.
Structures: The lateral wall is made up by the tympanic membrane with a section of bone superior to it in the attic portion of the middle ear.
Where is the posterior surface of the Tympanic Cavity, and what structures are located on the surface?
Posterior means
Structures: 1) A prominence parallel in height to the oval window called the Pyramidal Eminence.
2) The stapedius muscle is housed/and passes through the pyramidal eminence into the middle ear.
Where is the medial surface of the Tympanic Cavity, and what structures are located on the surface?
Medial means “closer to midline of the body”
Structures: 1) Oval window
2) Round Window
3) Stapes Footplate
4) Annular Ligament (connects the stapes footplate to the oval window)
5)Promontory (The first basal turn is jutting into the promontory creating the bulging effect)
6) Facial Nerve ( 7th Nerve- Superior to the oval window hidden by small bony ridge.)
7) Chorda tympani (branch of the facial nerve passes through the ossicles.)
Where is the inferior surface of the Tympanic Cavity, and what structures are located on the surface?
Inferior means “lowest portion”, “below”, “bottom”, “under” or “beneath”.
Structures: NONE!! (Separates the middle ear from the jugular vein)
Where is the anterior surface of the Tympanic Cavity, and what structures are located on the surface?
Anterior means the “nearer the front, especially situated in the front of the body or nearer to the head”
Structures:
1. cochleariform process (pyramid/”volcano”)
2. tendon of the tensor tympani muscle (Runs along eustachian tube)
3. Eustachian Tube
Where is the eustachian tube located?
Anterior surface of the tympanic cavity.
What muscles participate in the acoustic reflex?
1) Tensor Tympani
2) Stapedius
What are the three functional subsystems of the auditory system?
1) Conductive
2) Sensorineural
3) Central
What are the functions of the Eustachian Tube?
1) Equalize air pressure on both sides of the TM.
2) Allows for the air supply that is essential to the metabolism of the tissues of the middle ear.
3) Aids in drainage of middle ear secretions into the nasopharynx.
What portion of the malleus attaches to the tympanic membrane?
Manubrium
What is the functions of the Conductive System?
Transmission & Impedence Matching
What does it mean to say that there is an impedence mismatch between the outside air and the inner ear?
A sound wave is generated in air, low impedence medium, and transmitted to the fluid-filled cochlea, a high impedence medium. When the transfer of of sound is made from the low impedence of the middle ear to the high impedence of the fluid, a great deal of energy must be lost.
What are the functions performed by the sensorineural system?
Transducer, Frequency Analyzer, & Transmission
How does the middle ear overcome impedence mismatch?
With the Area Trick or the Lever Trick.
How large is the impedence mismatch?
1) Expressed as a ratio:
2) Expressed on a dB scale:
1) 1/1000th (?)
2) -30 dB or 30 dB of loss
What does the superior wall separate in the tympanic cavity?
It separates the middle ear from the brain.