Cochlear Anatomy
This bone houses the cochlea and osseous labyrinth.
What is the temporal bone?
This cochlear compartment is also known as the cochlear duct.
What is the scala media?
These sensory cells within the organ of Corti convert sound related mechanical stimulation into neural signals.
What are hair cells?
This term describes the systematic relationship between cochlear location and characteristic frequency.
What is tonotopic organization?
These cochlear cells exhibit electromotility, and contribute to active amplification.
What are the outer hair cells?
This central perforated bony core of the cochlea accommodates nerve fibers and blood vessels.
What is the modiolus?
These 2 scala contain perilymph.
What are the scala vestibuli & scala tympani?
These cochlear sensory cells occur in 1 row while their counterparts occur in 3 to 5 rows.
What are the inner hair cells?
These cochlear regions are most sensitive to high frequency sounds and are most sensitive to low frequency sounds, respectively.
What is the base & the apex?
This is the approximate positive electrical potential produced by the stria vascularis.
+80mV
This shelf like bony structure wraps around the modiolus and provides support for the basilar membrane.
What is the osseous spiral laminate?
This membrane separates the scala vestibuli from the scala media.
What is Reissner's membrane?
This protein acts as the motor protein responsible for outer hair cell electromotility.
What is prestin?
As you travel from the base towards the apex, the basilar membrane stiffness does this.
What is decrease?
As input sound level increases, this occurs to the cochlear amplifier.
What is cochlear amplifier gain decrease?
This ligament provides structural support along the lateral cochlear wall and may help maintain the ionic concentrations of cochlear fluids.
What is the spiral ligament?
This fluid has a high potassium concentration & a low sodium concentration.
What is endolymph?
During excitatory hair cell stimulation, this ion enters the hair cell from the endolymph and contributes to depolarization.
What is potassium?
This describes basilar membrane motion propagating across a spatial region of the cochlea.
What is a traveling wave?
Loss of outer hair cells can cause this combination of changes beyond reduced hearing sensitivity.
What is broader cochlear tuning / frequency sensitivity and poorer speech understanding in noise?
Identify the 3 structures that partition the cochlea into the scala tympani, scala media, and scala vestibuli.
What are the osseous spiral lamina, Reissner's membrane, and basilar membrane?
The scala vestibuli and scala tympani communicate at this cochlear landmark, allowing their perilymphatic spaces to connect.
What is the helicotrema?
Explain the sequence of events that links excitatory stereocilia deflection to neurotransmission from a cochlear hair cell.
Stereocilia deflection opens mechanically gated ion channels, potassium enters and depolarizes the cell, voltage gated calcium channels open, calcium entry promotes neurotransmitter release.
A sound frequency determines where the basilar membrane reaches its greatest response. Explain why a high frequency tone peaks near the base & a low frequency tone peaks near the apex.
The basilar membrane has a stiffness gradient with a stiff, narrow base tuned to high frequencies & the more compliant, wider apex tuned to low frequencies.
The second filter theory proposed this.
What is an explanation for the sharper frequency tuning observed in auditory nerve tuning/responses than in basilar membrane tuning?