Inner Ear Flashcards
The inner ear sits in the _____ portion of the temporal bone
Petrous
The pathway for the VII and VIII nerves within the skull is called the
Internal auditory meatus
The _________ is the conjoining of the scala vestibuli and the scala tympani at the apex of the cochlea.
Helicotrema
The modiolus and osseous spiral lamina create the structure of the cochlea
True
The point of attachment for the tectorial membrane is known as the _____
Spiral Limbus
The oval window is located ________ in the middle ear and is covered by ______.
Superiorly
The stapedial footplate
The round window is located ________ in the middle ear and is covered by ______.
Inferiorly
A membrane
The central, perforated, bony core that the cochlea wraps around is called the…
Modiolus
Coiled canal throughout the bony labyrinth around the modiolus
tha houses the spiral ganglion
Rosenthal’s Canal
Small openings within the cochlea that allow neural fibers to pass into or out of the Organ of Corti through the Basilar Membrane
Habenula perforata
Name the three ducts of the membranous labyrinth of the cochlea
Scala vestibuli
Scala media
Scala tympani
The ionic composition of perilymph and CSF are _____ dominant, whereas endolymph is ______ dominant.
Sodium
Potassium
In comparison to the apical end, the basal end of the basilar membrane is _______, ______, and ______.
Thicker
Narrower
Stiffer
Describe the concept of an asymmetrical envelope and how it pertains to the traveling wave
When a traveling wave approaches it point of maximum displacement along the basilar membrane, that displacement dies down faster than it initially grew
The stereocilia of the outer hair cells are _____ whereas the stereocilia of the inner hair cells are ______
Embedded in the tectorial membrane
Suspended in the scala media
The barrier that separates the endolymph from all internal structures of the organ of corti is known as the ______.
Reticular Lamnia
Reissner’s membrane separates which two ducts?
Sacala vestibuli and scala media
What part of the organ of corti supplies the blood and nutrients to the cochlea, and likely manufactures endolymph?
Stria Vascularis
________ separates outer hair cells and inner hair cells within the organ of corti.
Tunnel of Corti
Inner hair cells are organized in _____ row(s). There are approximately ______ of them. Their stereocilia are ___-shaped and are ________ to the tectorial membrane.
One
3,500
U
Not attached
Outer hair cells are organized in _____ row(s). There are approximately ______ of them. Their stereocilia are ___-shaped and are ________ to the tectorial membrane.
Three to Five
12,000
W or V
Attached
Each inner hair cell synapses with _____ Type ___ fibers
10-20
I
Each outer hair cell synapses with _____ Type ___ fibers
Multiple
II
Efferent fibers communicate largely with _____ and there are much _____ of them compared to afferent fibers.
OHCs
Less
Afferent fibers communicate largely with _____ and there are much _____ of them compared to efferent fibers.
Both OHCs and IHCs
More
The majority of afferent fibers are type I radial fibers
True
The supporting cells directly inferior to outer hair cells are called ___________
Deiters Cells
When a traveling wave along the basilar membrane compresses, it deflects the basilar membrane ______, pushes the stererocillia towards the _________ fiber, pushes the stapes ______, pushes the round window ________, and results in ________.
Downward
Shortest
Inward
Outward
Hyperpolarization/Inhibition
When a traveling wave along the basilar membrane rarefacts, it deflects the basilar membrane ______, pushes the stererocillia towards the _________ fiber, pushes the stapes ______, pushes the round window ________, and results in ________.
Upward
Longest
Outward
Inward
Depolarization/Excitation
The direction of the travelling wave is due to the _____, _____, _____ and _____ of the basilar membrane.
Shape
Thickness
Stiffness
Mobility
The idea that frequency encoding is dependent on its place of maximum vibration along the basilar membrane is called….
Place Theory
The idea that frequency is encoded based on the timing and rate of neuronal firing patterns (i.e. if neurons fire 500 times a second, then the frequency you’re hearing is 500 Hz) is called….
Temporal Theory
The idea that frequency encoding is dependent on a population of neurons firing action potentials at a particular phase of the input frequency is called….
Volley Theory
Low frequencies have _____ tuning curves and ______ frequency specificity than high frequencies.
Broader
Less
Viscous drag is when ____
Fluid in the subtectorial space is pushed away or towards the inner hair cells’ stereocilia
Name two limitations of von Bekesy’s travelling wave theory
Tuning is too broad at lower frequencies
Doesn’t take into account active processes such as the cochlear amplifier
The cochlear amplifier increases the ______ level in the outer hair cells as a response to sound. This increases the ______ of the outer hair cells, which changes the motion of the _______, increasing ______ along the basilar membrane, which increases _______ to the inner hair cells, amplifying the sound.
Voltage
Motility
Traveling Wave
Displacement
Mechanical Input
As the travelling wave moves towards the apex, its amplitude ______ and its velocity ______.
Increases
Decreases
Define the travelling wave paradox
The traveling wave always moves from base to apex due to the biophysical characteristics of the basilar membrane
How is a complex signal encoded via the travelling wave?
The basilar membrane peaks at several places, each correlating to the frequency components of the signal, similar to an FFT
In regards to excitation and inhibition, _________ is a result of compression and _____________ is a result of rarefaction.
Inhibition
Excitation
What is the key anatomical difference of shearing action and viscous drag?
IHCs are not embedded in the tectorial membrane and thus cannot take advantage of shearing action to open ion channels, instead fluid dynamics cause the streocillia on the IHCs to move parallel with the fluid (endolymph).
Define OAEs and describe how they are evidence of nonlinearity of the cochlea
Sounds generated in the inner ear at a low intensity that are detected in the EAM
Are only present in cochleas with a healthy/functioning cochear amplifier
Name 3 anatomical factors that make shearing action possible
The tectorial membrane can pivot up and down
The basilar membrane can pivot up and down
Sterocillia can deflect towards or away from the tectorial membrane
Inner hair cells are innervated primarily by ______, transduce sensory information via _____ and are ______.
Type I Spiral Ganglion Cells
Viscous Drag
Not Motile
Outer hair cells are innervated primarily by ______, transduce sensory information via _____ and are ______.
Type II Spiral Ganglion Cells
Shearing Action
Motile
The cochlear amplifier results in _____ tuning
Sharper
Two pieces of evidence of the nonlinearity of the cochlea include _____ and ____.
Frequency Encoding being sharper at higher frequencies
Intensity Encoding being broader at higher intensities
Label the inner ear
Label the cochlear ducts
Label the bony labyrinth
Label the organ of corti
Label the scala media
Label the cross-section of the cochlea
