Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
66 Cards in this Set
- Front
- Back
|
acoustic energy |
outer ear |
|
|
mechanical energy |
middle ear |
|
|
fluid energy |
middle ear
|
|
|
temporal bone |
contains the sensory organs of hearing, balance and the human ear |
|
|
outer ear anatomy |
auricle/pinna ear canal/external auditory meatus outer layer of ear drum (tympanic membrane) |
|
|
auricle/pinna |
skin covered cartilage of outer ear, no fatty layer underneath |
|
|
helix of pinna |
upper rim |
|
|
lobule of pinna |
ear lobe |
|
|
concha |
bowl of pinna at entrance of ear canal |
|
|
osseocartilaginous junction |
connection between cartilaginous portion and bony portion of external auditory meatus |
|
|
first 1/3 of EAM |
skin covered cartilage |
|
|
inner 2/3 of EAM |
skin covered bown
|
|
|
size of EAM |
2.3-2.9 cm in length, .7 cm in diameter |
|
|
EAM shape |
has a downward bend at the auricle to protect the eardrum from outside substances |
|
|
diameter of TM |
.9cm, slightly larger than EAM because of a 55 degree angle |
|
|
shape of TM |
concave and slightly inward like a cone shape |
|
|
pars flaccida |
superior portion, 1/10 of TM more flexible portion/less strong does not have a middle fibrous layer does not participate largely in transduction of acoustic signal |
|
|
pars tensa |
9/10 of TM very strong, made of tightly woven fibers to protect ear drum |
|
|
annulus |
thickened fibrocartilagenous ring fixed to tympanic bone surrounding membrane 3/4 of the way around it |
|
|
otoscopic evaluation |
a cone of light is present that reflects of the malleus (umbo) in the tympanic membrane |
|
|
two parts of malleus that connect to the TM |
umbo (lower part) manubrium of malleus (more central part) |
|
|
part of incus attached to TM |
long arm of incus |
|
|
outer ear physiology |
collect and resonate sound assist in sound localization protect the middle ear |
|
|
resonant freq of ear canal |
2700 Hz |
|
|
resonant freq of pinna+ concha together |
5000 Hz (high freq) |
|
|
total enhancement of resonant freqs of outer ear |
+20 db around 3500 Hz |
|
|
head related transfer function |
-the way sounds bounce off diff parts of body may contribute to sound localization (diffraction and reflection properties of head, pinna torso before reaching ear) -use timbre differences from sounds coming from diff directions -sounds will lose some freq when they hit body parts |
|
|
interaural time difference (ITD) |
calculate the difference in time each ear hears the sound to determine where its coming from -best for lower freq sounds because they can bend and won't lose intensity (will arrive at opposite ear at same intensity but diff time) |
|
|
interaural intensity difference (IID) |
calculate the difference of intensity of the sound at each ear to determine where the sound came from -best for higher freq sounds because they can't bend when presented with an obstacle and will lose intensity when it reaches the farther ear (inverse square law) |
|
|
cerumen |
sebaceous glands in ear canal secrete cerumen -protects skin/prevents foreign objects from entering ear canal -antibacterial/antifungal properties |
|
|
cilia |
hairs in outer 1/3 of ear canal point outward toward the pinna
|
|
|
middle ear anatomy |
-middle/inner layers of tympanic membrane -ossicles/middle ear bones (malleus, stapes, incus) -eustachian tube -ligaments/muscles -oval/round windows |
|
|
three layers of TM |
-outer epithelial layer -inner mucosal layer -middle fibrous layer |
|
|
outer epithelial layer of TM |
continuous with skin lining of ear canal |
|
|
inner mucosal layer of TM |
continuous with mucous of middle ear |
|
|
middle fibrous layer of TM |
encloses handle of malleus has 3 types of fibers-radial, circular and parabolic |
|
|
tympanic membrane physiology |
separates outer ear from middle ear -transmits acoustic sounds from air to ossicles by vibrating (mechanical) -malleus is connected to ear drum at the umbo and short arm of the malleus |
|
|
two parts of middle ear cavity |
-tympanic cavity -attic/epitympanic recess |
|
|
tympanic cavity |
opposite tympanic membrane (part of middle ear cavity) |
|
|
epitympanic recess/attic |
above the level of the tympanic membrane contains upper half of malleus and greater part of incus |
|
|
middle ear cavity characteristics |
-irregular shape -filled with air (from nasopharynx through eustachian tube) -houses the ossicular chain (connected from lateral wall/malleus to medial wall/stapes) |
|
|
tegmental wall of middle cavity |
"roof" formed by a thin plate of bone ceiling of epitympanic recess (upper part of malleus/incus) |
|
|
jugular wall of middle cavity |
"floor" separates tympanic cavity from the jugular fossa |
|
|
medial wall |
-opening to the cochlea -fenestrae vestibuli (oval window) and rotunda (round window) -promontory of the cochlea (between the windows) and the facial nerve VII |
|
|
anterior wall (towards front of face) |
tendon of the tensor tympani muscle (connected to malleus) -opening to the auditory tube/eustachian tube |
|
|
posterior wall (towards back of head) |
attachment of stapedius muscle (connected to stapes) -access to mastoid bone air cells through aditus and antrum |
|
|
lateral wall (closest to outer ear) |
contains tympanic membrane |
|
|
ossicles |
3 smallest bones in the body (malleus incus stapes) -connect TM on lateral wall to oval window of the cochlea on medial wall -have true articular joints |
|
|
malleus |
manubrium and short process (umbo) connected to TM -attached to lateral wall by lateral ligament -head of the manubrium is attached to the body of the incus |
|
|
incus |
attached to posterior wall via superior ligament -long process is attached to head of stapes |
|
|
stapes |
sealed to the entrance of the cochlea/inner ear by annular ligament + footplate |
|
|
eustachian tube |
connects middle ear to nasopharynx -equalizes pressure(pressure changes of middle ear impact TM) -drains fluid -normally closed, opens during swallowing/yawning -beings in anterior wall 36mm in length |
|
|
eustachian tube in children |
it is more horizontal in infancy children unable to drain fluid as easily -common for children to have fluid in ears secondary to ear infections |
|
|
acoustic reflex |
middle ear muscles that contract in response to a loud sound |
|
|
stapedius muscle |
attached from posterior wall to stapes -primary muscle of acoustic reflex, only one measured in audiology -contracts pulling stapes backwards(towards TM) -decreases movement of stapes, dampens hearing sensitivity |
|
|
tensor tympani |
attached from anterior wall to malleus -contracts pulling TM inward in response to internal sounds (chewing) and non auditory stimuli (puff of air to the eye) -TM stiffens, doesnt vibrate as easily, dampens hearing sensitivity |
|
|
physiology of the middle ear |
1. three impedence matching mechanisms 2. pressure equalizer 3. protection
|
|
|
impedance matching device |
middle ear carries mechanical energy from TM to fluid filled inner ear (change of resistance from air-fluid) -if sound pressure waves were applied directly to inner ear 99.9% of acoustic energy because of fluid -even with ossicles there is a loss of 33dB -middle ear has to account for this |
|
|
middle ear increases pressure to match impedence by |
1. increasing force 2. decreasing area 3. both 1 and 2 at the same time |
|
|
middle ear impedence matching mechanism TM to footplate (area ratio) |
-area of the TM is 17x greater than the footplate of the stapes -decrease in size from TM to the footplate without change in force results in a 17x increase in pressure (+25dB)
|
|
|
middle ear impedence matching mechanism malleus to incus (lever action) |
-length of manubrium of malleus is 1.3x length of incus -pivot point (connection) of malleus/incus is closer to incus and therefore the malleus uses less force to move it (like a seesaw) -results in an increase in pressure on the incus (+2dB) because of force applied to a smaller incus, therefore applied to oval window |
|
|
middle ear impedence matching mechanism TM shape (buckling) |
-flexible/cone shaped TM curves from its rim at both ends to its attachment at the umbo -results in greater movement/displacement of the TM and not the malleus manubrium/ umbo (higher pressure) -product of force/displacement must be equal on both sides of TM -+6dB gain |
|
|
total gain from middle ear impedance matching |
33 dB (25dB+2dB+6dB) -about as much that would be lost by converting from mechanical energy (middle ear) to hydraulic energy (inner ear) |
|
|
middle ear transfer function |
doesn't transmit all freqs equally, better sensitivity to mid freq range (900-5kHz) -gain of pressure/dB depends on freq, resonancy characteristics, and phase diff between pressure wave at oval window and phase at TM |
|
|
pressure equalizer |
eustachian tube equalizes pressure between middle ear cavity and external auditory meatus by opening and letting in air from nasopharynx -if unable to open, negative pressure in ME can suck in TM and make it stiff/resistant to vibration |
|
|
contraction of auditory reflex |
bilateral contraction of middle ear muscles (tensor tympani and stapedius) primarily stapedius -contraction increases w increased intensity (AR growth) to a point (plateau) -85 dB causes the contraction in both ears even if loud sound is only presented to one ear -dampens sounds by stiffening ossicle chain (low freqs) |
