CSD 373
located in the outer ear, what part of the temporal bone is this?
Choose matching term
1
What dB is the most important for the purpose of this course (used to plot audiograms)
2
Mastoid process of temporal bone
3
Functions of the Eustachian tube:
4
squamous of temporal bone
Don't know?
Terms in this set (91)
Alphabetical
Adult's Eustachian tube
45 degree angle
Child's eustachian tube
flat and 180 degrees
Condensation sound waves
increased air pressure
cone of light
dB HL
- Hearing Level
- Used to plot audiograms
dB IL
Intensity level
dB SL
- Sensation Level
dB SPL
- Sound Pressure Level
Describe the cochlea in the inner ear
High Frequencies at the base and Low Frequencies at the Apex
ear canal/external auditory meatus
endolymph
Simliar to intracellular fluid (postive charge)
eustachian tube
Frequency theory
Pattern of discharge codes for frequency
Frequency Wavelengths
- Hz
- Cycles / Second
- High vs. low frequency
Functions of the Eustachian tube:
- pressure equalization
- fluid drainage
functions of the inner ear
- movement of the basilar membrane (tonotopic organization)
- Sheering of hair cells
- depolarization
functions of the middle ear
Acoustic Vibrations into Mechanical Vibrations
hair bundles/stereocilia
Hair cells
- View with tectoral membrane peeled away.
- OHC's are embedded in the tectorial membrane
- Bending of the stereocilia toward kinocillium creates the action potential inside the hair cell which begins the neural transmission to the brain.
Helicotrema
is at the apex of the cochlea. The helicotrema is where two of the three chambers of the inner ear combine (scala vestibuli and scala tympani... high frequency is the first part of hearing to go.
How does the energy change from the middle to the inner ear?
Mechanical Vibrations to Hydromechanical
how is the basilar membrane inside of the cochlea organized?
tonotopically-- high frequencies at base to low frequencies at the apex
Impedance matching in middle ear
33 dB gain/increase
incus
a small anvil-shaped bone in the middle ear, transmitting vibrations between the malleus and stapes.
inner hair cell characteristics
- 3500 in single row
- Chalice shaped
- Centralized nucleus; organelles throughout cell
- Only Afferent fibers synapse directly on the cell
Sends a majority of the afferent information to the brain
inner hair cells
1 row
inner hair cells of organ of corti
Is the Eustachian tube naturally closed or open?
closed
liquid in scala tympani
perilymph
Malleous
the tiny middle ear bone shaped like a hammer.
malleus
a small bone in the middle ear that transmits vibrations of the eardrum to the incus.
manubrium of malleous
Mastoid process of temporal bone
located in the middle ear, what part of the temporal bone is this?
nerve fibers
Organ of Corti
The Organ of corti is the true sense organ for hearing. When I talk about the parts of the organ of corti "inner" means toward modiolus: "outer" means toward stria vascularis.
Inner hair cells- 1 row
Outer hair cells- 3 rows
The cells that transmit the neural signal to the cochlea are pictured in orange above. The inner and outer hair cells can be differentiated a few different ways. In this photo you can ID the OHCs by the 3 distinct rows and the IHCs by the single row.
organ of corti
ossicular chain
outer hair cells
- 12,000
- 3 rows
- Cylindrical shaped
- Organelles along outer wall
- W appearance from the top
- Contract and elongate in response to basilar movement (cochlear amplifier)
- Efferent and Afferent fibers synapse directly on the cell
outer hair cells
3 rows, form a W
active process of cochlea
outer hair cells of inner ear
Pars flaccida
pars tensa
perilymph
- Similar to CSF- high sodium and low potassium
- Fills the bony portion of the cochlea
Period in wavelengths
how long it takes to complete one cycle
Petrous part of temporal bone
located in the inner and middle ear, what part of the temporal bone is this?
Phase locking
Neural discharges occur in the same phase as the stimulus- Valid up to 4000Hz
pinna
Place theory
Frequency info coded where peak of traveling wave occurs
Purpose of the acoustic reflex:
- protection
- reduction of distortion of a person's own voice
Rarefaction
decreased air pressure
Reissner's membrane
separates scala vestibuli from scala media
Scala media
which attaches to osseous spiral lamina (bony protrusions from the modiolus which you will see on the next slide) and contains the organ of Corti: Its borders are the basilar membrane and Reissner's membrane. It is bordered by the stria vascularis which provides blood flow, nutrients and electrical charge to the system. This is imperative for proper cochlear function.
scala media
Scala tympani
ends at round window and contains perilymph
scala tympani
scala vestibuli
which scala attaches at the vestibule and is located above Reisner's membrane. This scala is filled with perilymph.
scala vestibuli
semicircular canals
spiral ganglion
cell bodies of the auditory nerve that innervates the sensory hair cells
spiral ligament of inner ear
squamous of temporal bone
located in the outer ear, what part of the temporal bone is this?
stapes
stirrup; last of the three auditory ossicles of the middle ear
Stria Vascularis
external wall of cochlear duct composed of mucosa that secretes endolymph
tectorial membrane
temporal bone
bone that forms parts of the side of the skull and floor of the cranial activity. There is a right and left temporal bone.
tunnel of corti
Tympanic membrane
eardrum
tympanic part of temporal bone
located in the outer ear, what part of the temporal bone is this?
Umbo
vestibule of inner ear
Composed of the utricle, saccule, and semicircular canals
Wave forms: 180 degrees out of phase
Added together= Cancel each other out
Wave forms: complex waves
- Two simple waves combine= Complex wave
- Lowest frequency of complex wave is Fundamental Frequency
Wave forms: same starting phase
Added together=Increased amplitude
Wavelength
speed of sound/frequency
What are the 5 divisions of the ear
Outer
Middle
Inner
Auditory Nerve (8th nerve)
Central Auditory Nervous System
What are the functions of the outer ear
funnels sound, transfers function ( up to 15-20 dB), protects ear
What color is used for the left ear?
blue
What color is used for the right ear?
red
What dB is the most important for the purpose of this course (used to plot audiograms)
dB HL
What does the inner ear contain?
Cochlea
Vestibule
Utricle and Saccule
Semicircular Canals
- Anterior
- Posterior
- Horizontal
What is the function of the eustachian tube?
equalizes pressure
What is the normal state of the Eustachian tube
closed
What kind of energy is in the outer ear
acoustic energy
What kind of response is provided from the acoustic reflex in the middle ear?
bilateral response
what liquid is in scala media
endolymph
What liquid is in the scala vestibuli
perilymph
What occurs when two simple waves combine?
they create a complex waveform.
What occurs when two waveforms have the same starting phase?
they add to one another and result in a waveform with increased amplitude
What occurs when waveforms are 180 degrees out of phase?
they cancel one another out.
When two simple waves combine they create a _________ waveform.
complex
Where is the auditory nerve?
inner ear
8th nerve