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Outer, Middle and Inner Ear Structures, Cochlear Mechanics, Transduction

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Skin cells migrate from the tympanic membrane the the ___ ___ ___.   external auditory meatus  
what is the resonant frequency of the ear canal?   2,000 Hz  
what is the resonant frequency of the corona?   5,000 Hz  
The combined primary resonant frequency is   2,500 Hz  
The ear drum is also known as the   tympanic membrane  
Middle ear cavity is also known as the   tympanum  
Name the three ossicles:   Malleus, Incus and Stapes  
The outer thickened area of the TM is called the ______, which fits into a groove in the bone, the tympanic ________.   annulus, tympanic sulcus.  
Name the three layers of the TM:   1) Skin layer, 2) Middle fibrous layer, 3) Mucus membrane  
The main part of the TM, that makes up the tense portion, is called   Pars Tensa  
Schrapnell's membrane, which doesn't have as many fibers and is less tense is called   Pars Flaccida  
Which Pars is a part of the pressure regulating mechanism for ME?   Pars Flaccida  
What is the first bone in the chain of ossicles?   Malleus  
The _____ of the malleus attaches to TM on outer side and makes it into a cone shape which has a tip that is called the ______.   manubrium, umbo (umbrella)  
A hole in the temporal bone that houses the ossicles is called the   ME Cavity  
Above head of malleus and most incus is called _______ _______.   epitympanic recess (aka attic)  
A hole that leads to another cavity which is the tympanic antrum is called the _______ _________.   tympanic aditus  
Inside this bump, ________ _______, is very porous bone and these are called mastoid air cells. If they get infected this might lead to a chronic disease.   tympanic antrum  
Another name for the nasopharynx or auditory tube is the   Eustachian tube  
This seperates ME Cavity from cranial cavity, a thin sheet of bone. If infected, get meningitis, life threatening disease.   tegmen tympani  
What is the name of the bump on the medial wall?   Promontory  
Above the Promontory is a hole that connects to the inner ear, which is called the ____ ______.   oval window (which leads to inner ear and fluid)  
The whole below the promontory is called the ______ _______.   round window  
The ______ ________ contains tendon of stapedius muscle, which attaches to stapes.   pyramidal eminence.  
A branch of the VII cranial facial nerve, which runs just behind manubrium of malleus is called the ______ ________. It carries taste from front of tongue (anterior 2/3 taste sensation) to brain and also has nerves that innervate the salivary glands.   Chora tympani  
Chorda tympani has _____ and _________ neurons   afferent and efferent  
carries info towards CNS of brain   afferent  
carries info from CNS to PNS, so away from brain   efferent  
This tube is slopped down and back and is more subject to collapse to infection in babies than adults because it is more horizontal and the milk accumulates in it.   Eustachian tube  
Eustachian tube has two parts:   Osseous part and cartilaginous part  
which part is mainly opened by the tensor palatini (forms part of soft palate) and connects to sphenoid bone and hooks at pterygoid hamulus?   cartilaginous part  
When tensor palatini contracts it ______ tube and replenishes air in the ME cavity.   opens  
TM moves best when pressure of ME and OE is   equal  
Describe PEC > PME   Pressure is negative inside the ME cavity because the TM is pushed inward by the external air pressure. (ex: sitting in class and not moving)  
Describe PEC < PME   Pressure is positive inside the ME cavity compared to the external air pressure. (Ex: plane flight going up)  
The head of the malleus articulates with the   incus  
The articular facet joins with the   malleus  
what are the two middle ear muscles, which are both pennate muscles?   stapedius muscle, tensor tympani muscle  
pennate means that the muscle is   "feather" like  
When the stapedius muscle contracts it stiffens the ossicular chain therefore acoustic air doesn't travel through as readily, this is called the _____ _________.   acoustic reflex  
What muscle contracts when there is a "startle"?   tensor tympanic muscle  
function of middle ear transfer sound _____ of air into fluids of inner ear.   energy  
area with relatively low impedance   air  
area with relatively high impedance   cochlear fluids  
impedance mismatch between air and cochlear fluids is much like mismatch between _____ and _________. How much sound energy is lost?   air and water, 99.9%  
In the Area ratio hypothesis, if you reduce area, pressure   increases  
pressure is much greater at tip of thumb tac because the _____ is over a larger area, same with TM and stapes   force  
The boost of energy given by the malleus and incus is called the   Lever Hypothesis  
The ______ ___ is located in the petrous portion of the temporal bone   Inner Ear  
Houses the utricle and saccule   Vestibule  
area that looks like a snail and where organ of corti is located.   Cochlea  
each has a widened portion called ampulla inside is sensory cells, which give us info on position of our heads (containing an organ of balance).   semi-circular canal(s)  
What inner ear structure is 35 mm long, 2 1/2 turns in humans?   Cochlea  
In the membranous labyrinth the outside is ______ and the outside is _______.   perilymph, endolymph  
Perilymph is low in _____ and high in ______   K+, Na+  
Endolymph is low in ___ and high in ______   Na+, K+  
The middle part of the Cochlea is called the   modiolus (core of the cochlea)  
Each turn of the cochlea is divided into 3 sections by membrane, these are called   1) Scala vestibuli 2) Scala meida (cochlear duct) 3) Scala tympani  
Which one(s) are filled with perilymph?   Scala vestibuli and scala tympani  
Which one(s) are filled with endolymph?   Scala media  
What structure connects Scala vestibuli and Scala tympani?   Helicotrema  
This structure separates scala vestibuli from scala media   Reissner's Membrane  
This structure separates scala media from scala tympani   Basilar membrane  
The Organ of Corti sits on top of Basilar membrane and has holes that are called ______ ________. These lead from spiral lamina into scala media   Habenula perfarata  
Outer hair cells sit in cup shape indentation of _____ cells.   deter  
nerves from cochlear nerve run through this ______ _______ _______   osseous spiral lamina  
a neural impulse/discharge which is a small change in voltage that travels along axon is known as an   action potential  
cochlear neuron is 1 axon and 1 dendrite, which is   bipolar=95% of cochlear neurons  
axon and part of dendrite have ____ sheath   myelin  
dendrite emerges through habenula perforata hole and becomes myelinated after the Organ of Corti, so this means that before it is not   myelinated  
cochlear nerve (cochlear branch of the VIII) and Vestibular nerve together create the ______   cranial nerve VIII (Auditory nerve)  
entire inner ear is filled with   fluid  
malleus articulates w/incus>incus w/stapes, when ossicular chain vibrates>ossicles vibrate when oval window is pushed inward by ____ footplate, the _____ window bulges outward. Reissner's & Basilar's membrane are pushed down in scala ______ when pushed in   stapes, round, media  
How does the cochlear partition move?   cochlear mechanics (hydromechanics b/c fluid system)  
process of fluid being moved in inner ear   cochlear partition  
What is another name for the scala media?   cochlear partition/duct  
Bekesy discovered that the tension along Basilar membrane is held more ____ in base than apex. So it is more ____ in apex   stiffly, flaccid  
When the stapes pushes down on Basilar membrane (cochlear partition) the compressional wave moving from the base > apex because of tension characteristics of Basilar membrane is a movement called the   traveling wave  
For high frequencies/pitch sounds, the greatest displacement is towards the ____ of the cochlea.   base  
For low frequencies/pitch sounds, the greatest displacement is towards the ___ of the cochlea.   apex  
Displacement is across whole system, but has places of higher displacement and our system can tune into this, this is called _________ _________   hydromechanics filtering  
frequency is organized according to   place pr spacially  
What causes a traveling wave? ______ and _______   compressions and rarefactions (takes 5 ms from base > apex)  
What if the Basilar membrane was equal in stiffness all the way along?   The whole membrane would move downward as a unit and go back to original position when stapes moves outward basilar membrane moves up.  
However it does not move with an equal stiffness and the traveling wave is not equally ______ along membrane   displaced  
the dotted line for a traveling wave that is plotted for the maximum displacement of a tone is called the   envelope  
an envelop plots the _______ displacement, each displacement plotted has a different envelope   maximum  
For low frequency sounds the maximum displacement is at the ___ of the basilar membrane   end (apex)  
For high frequency sounds the maximum displacement is at the ____ of the basilar membrane.   beginning (base)  
What forms the ionic barrier between endolymph and perilymph?   reticular lamina  
Inner and outer hair cells are bathed in   perilymph  
Inner and outer hair cilia are bathed in   endolymph  
The highly vascularized tissue that plays an extremely important role in function of cochlea. Inside it are iron pumps that maintain ion concentration of K+ and Na+ in Scala media.   Stria Vascularis  
Discovered that many born deaf, system of replenishing potassium, _____ ______ is not working.   Stria vascularis  
K+ results in positive charge of +____mV above reticular lamina   +80mV  
Inside hair cell charge of -____mV   -40mV  
When cilia bend towards outer wall of cochlea, causes K+ ion channels to ____ and K+ moves _____ hair cell, depolarizing hair cell. Charge moves from -40mV to zero. This results in release of ___ into cell which leads to discharge of neuron.   open, down into, NT  
When cilia go back to original position ___ channels close.   K+  
Depolarization causes influx of ____, which causes opening of ___ channels.   Ca++, K+  
Summary of Hair cell: 1)Cilia bend>K+ channels open, 2) K+ enters hair cell> causing it to ____. 3) This causes Ca++ channels to ___in membrane of cell and causes release of NT at ___ of hair cell. 4) Ca++ causes K+ to ___ in base of hair cells. 5) K+ ___   depolarize, open, base, open, leaves the cell and cell then becomes repolarized (resting potential)  
Tops of cilia are filaments that are called   Tip links  
Little further down cilia are filaments that tie cilia together and they are called   side links  
In transduction the ear tranduces sound to mechanical energy in the form of vibrations of the _____ ________.   cochlear partition  
The mechanical energy is transduced into ________ energy by hair cells.   electrical  
When basilar membrane vibrates, hair cell ________ are sheared or bent by the tectorial membrane.   stereocilia  
Ion channels are located in the ____ of hair cells   cilia  
Tip links are part of a mechanical system which opens ___ ______.   ion channels  
The filament (tip links) is believed to attach to a molecule on the cilium that acts like a ____ ____.   trap door.  
When the tallest row of cilia are bent in one direction, the "trap doors" in cilia in the next (shorter) row are ____, allowing K+ ions to flow through the cilia into the hair cell. The system is called "____ _____" mechanism.   opened, "gating spring" mechanism  
The cochlea is not simply a passive device receiving sound energy, rather it is an ____ system, which adds _____ energy to the transduction process   active, mechanical  
This energy from the cochlea is added by the outer hair cells changing their _____. That is, when an area of the basilar membrane vibrates, contraction and elongation of outer hair cells add a boost of _____ energy.   shapes, vibratory  
Presenting a low level tone in the ear causes an increase in the ____ of vibration of the BM at the point of its maximum displacement. So the peak of the traveling wave increases in size (also sharpness).   amplitude  
This results in an increase in selective stimulation of ____ hair cells of that area. Hallowell Davis coined the term "_____ ______" to describe this mechanism.   inner, cochlear amplifier  
Vibration of the TM results in sound being radiated into the ear canal this sound is called   otoacoustic emission  
acoustic energy is fed into the system, and the system returns...   acoustic energy  
low amplitude transient sounds that occur a few ms after a transient stimulus such as a click presented to the ear   Transient Evoked OAEs  
sounds that occur in the ear canal without acoustic stimulation. These sounds originate in the cochlea and are present even when an external stimulus is not being presented to the ear.   Spontaneous OAEs  
The cochlear nerve courses from the modiolus of the cochlea through the _____ ____ ____   internal auditory meatus  
Before entering the meatus it is joined by the two branches of the vestibular nerve; collectively the ____ and ____ nerves from the VIII cranial nerve   vestibular and cochlear  
Axons of the cochlear nerve enter the brainstem at the _______ ____   cerebellopontine angle.  
All of the axons _____ neurons in the cochlear nucleus that is located in the ______ ______ of the brainstem   synapse, medulla oblongata  
The cochlear nucleus is the "lowest" point in the ____ ______ of the brainstem.   auditory pathway  
This pathway consists of a series of nuclei or groups of ______ ______, and fiber tracts, or groups of _____.   cell bodies, axons  
Cell bodies in the cochlear nucleus send some axons to the ipsilateral superior olivary complex, but most cross the midline in a fiber tract called the _____ _______.   trapezoid body  
Many of the axons that cross the midline synapse at the SOC on the _______ side   contralateral  
The SOC is the ___ major center on the pathway, and is the first level at which there is bilateral input of auditory ______.   2nd, information  
The SOC is known to be involved in the _______ of sound.   localization  
Other nuclei in the pathway are:   inferior colliculus and medial geniculate body (MGB)  
Nerve fibers course from the MGB along a pathway called the _________ _________ to the auditory _______.   auditory radiations, auditory cortex  


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