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66 Cards in this Set
- Front
- Back
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Where are all the structures of the inner ear located? |
The temporal bone |
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What are the three structure of the inner ear? |
Semicircular canals Vestibule Cochlea |
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Name the semicircular canals |
superior (anterior) Posterior (inferior) Lateral (horizontal) |
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SC canals open into... |
Vestibule/utricle + saccule |
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What comprises the vestibular system? |
SC + Saccule + utricle |
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Which is the bony labyrinth? Which is the membranous labyrinth? |
Bony = Blue Membranous = red |
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Modiolus characteristics |
Located in the inner ear, the modiolus is a conical-shaped bony core around which the cochlea winds (two and a half times). It contains the spiral ganglion, which is made up of nerve cells whose axons form the auditory nerve (or cochlear nerve). The spiral ganglion in the modiolus receives acoustic information from the hair cells in the organ of Corti situated in the cochlear duct (scala media) of the cochlea and then send it to the brain temporal lobe through the auditory nerve. |
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Osseous spiral lamina |
Shelf of bone (inner wall) that projects from modiolus, helping to separate SV from ST |
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Spiral ligament |
covering of outer wall |
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Basilar membrane is between... |
spiral ligament and osseous spiral ligament |
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Cochlear nerve fibers go to... |
hair cells of organ of corti |
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Stria vasularis to... |
Endolymph |
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Cell body of cochlear nerve are called.. |
spiral ganglion
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Reissner's membrane is also called the |
vestibular membrane |
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Cochlear structures |
Stria vascularis Reissner's membrane Basilar membrane |
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Stria vascularis |
Covers outer wall of cochlea Dense layer of blood capilaries Provides basic metabolic control of cochlear |
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Reissner's membrane |
divides S.V. from S.M. |
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How long is the basilar membrane uncoiled? |
35 mm |
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The scale vestibuli is high in |
Sodium (Na+) |
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scala media is high in |
potassium (k+) |
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High freqeuncies are at the _______ of the basilar membrane and low frequencies are at the _______ of the basilar membrane |
1. basal end 2. apical end |
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At the apical versus the basal end... |
The apical end is floppy allows for the LF generation The basal end is narrow, and stiff which allows for the HF to generate |
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When a HF travels along the basilar membrane, the vibrations.... |
go to the basal end |
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When a LF travels along the basilar membrane, the vibrations |
travel along the basal end |
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Which type of HC are embeded in the tectorial membrane? |
The tallest OHC |
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Rows of IHC and OHC |
3 rows of OHC 1 row of IHC |
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the lining of the stereocillia |
reticular lamina |
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What divides the inner/outer portions of the organ of corti? |
Pillars/rods |
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IHC & OHC slant... |
toward each other |
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Inner tunnel of corti |
Space between rods and contains cortilymph |
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Deiters/Hensen cells buttress |
OHC |
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Border cells buttress |
IHC |
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IHC characteristics |
– Cilia arranged in shallow U – Cilia not in contact with tectorial membrane – Pear shaped – Centrally located nucleus – Completly surrounded by supporting cells |
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OHC |
– Cilia arranged in shape of V or W –Tips of tallest row of cilia in contact with tectorial membrane – Cylindrically shaped – Nucleus near base – Contact supporting cells ONLY at the very bottom & top |
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The tectorial membrane is attached along... |
• One edge to the spiral limbus near inner wall |
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What are structures 7 & 9? |
7 = Deiters' cells 9 = Hensen's cells |
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The organ of corti is... |
Where we get transduction of mechanical to electrical impulse |
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What causes fluid to vibrate? |
The stapes |
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What causes displacement of basilar membrane? |
The vibrations of fluids |
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How is a neural impulse initiated? |
Cilia of HC bend |
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How is the basliar membrane's vibratory pattern established? |
By basilar membrane's width/elasticity |
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The traveling wave that occurs on the BM always travels from which end? |
basal to apical |
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What happens after peak amplitude traveling wave is reached? |
the amplitude dampens, rapidly |
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On B.M. the frequency of vibration is ________ as the stimulus |
the same |
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Cochlear Fourier/spectral analysis |
for complex signal; each frequency creates max displacement at different B.M. sites |
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Traveling wave travels to.. |
Helicotrema
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Throughout the cochlea, sound is ____________ immediately because the _______ is relatively incompressible and ______ ______ is high |
1. disturbed 2. fluid 3. sound velocity |
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1. Traveling wave paradox 2. Why does this occur? |
1. traveling wave would go from base to apex direction even if stapes (driving force) at apical end 2. This is due to to differences in physical characteristics of B.M -- not because OW first stimulates basal end |
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which is stimulated first basal end or apical end of basilar membrane? |
BASAL end |
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What drives the wave moment of LF/HF when traveling along the basilar membrane? |
The mass and stiffness of the membrane; the physical characteristics |
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Where do the hair cells and the ORGAN of corti rest? |
on the basilar membrane |
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What causes the shearing action of the hair cells with the tectorial membrane? |
the upward displacement of the basilar membrane from the traveling wave |
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What does the shearing cause? |
It causes the stereocilia to bend or pivot at the base |
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The bending of the stereocilia open what? |
The "ion channels" |
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Once the ion channels have opens, what occurs next? |
an electrical current flows into the cell |
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So, action potential, is generated by what? |
The shearing of the stereocilia |
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How does the current generated from the shearing action for the IHC and OHC differ? |
*For the OHC, current causes the hair cells to exhibit "motility" or spontaneous and independent movement *Motile OHC change shape (lengthen or shorten which generates force *For the IHC, current causes the cell to release neurotransmitter which elicits responses in primary auditory neurons and are NOT motile |
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Inside the stereocilia cells, the current flowws does what to the voltage? |
Makes it more positive |
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OHC motility |
*OHC motility generates force *Force changes the motion of the traveling wave, increased mechanical input to the IHC *OHC process leading to increased basilar membrane vibration is called cochlear amplifier *compressive non-linearity *ensures that soft wounds are amplified more strongly than loud sounds |
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Cochlear amplifier |
OHC process leading to increased basilar membrane vibration |
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cochlear amplifier characteristics |
*increase in input *improves sensitivity (lowers the threshold) of the basilar membrane *improves frequency selectivity of the basilar membrane *sharpens tuning curves |
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Cochlear non-linearities |
Traveling wave does not fully explain cochlear mechanics *does not explain perception of combination tones when 2 tones presented simultaneously -- even though they are not present in signal *perception of these combination tones suggest presence of significant cochlear non-linearities |
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modiolus |
bony central axis |
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