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Anatomy of Audiology
Outer, Middle and Inner Ear Structures, Cochlear Mechanics, Transduction
| Question | Answer |
|---|---|
| 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 |
Created by:
rcheek
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