audio-exam 1 Flashcards by v j

prevalence HL

In U.S., ≈ 10% with hearing loss
≈ 26 million hard-of-hearing (HOH)
Hearing loss makes communication difficult since speech is primary means of communication
≈ 2 million “deaf” individuals
Severe-to-profound bilateral hearing loss
Prevalence increases with age
17 in 1000 children under age 18
40 – 50% ≥ 75 years

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audiology vs otology

audiology- ear aids life

otology- life risked by ear?

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audiology specialties- PRIME

medical- evals, ototoxic monitoring, screenings
rehab- hearing aids, AR
pediatric- minimize effect, special kid/parent skills
educational- screen, eval, collab w teachers/SLP, rehab, consult (rm acoustics)
industrial- prevent HL by reducing, educating, protective etc

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peripheral vs central auditory

peripheral: outer =>middle => inner => cranial nerve 8

central- Cochlear nucleus in brainstem to auditory cortex

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branchial arches and grooves

5 arches=> head and neck
1st & 2nd=> inner ear, pinna
1st: mandible, malleus and incus
1st groove: Concha/ external auditory meatus/ TM outer layer
2nd:  face muscles, hyoid, stapes

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___derms

endoderm- middle ear space LINING, E tube
mesoderm- middle ear space, ossicles
ectoderm- outer ear covering

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outer ear: pinna parts and fn

cartilage and skin
from top: helix, triangular fossa, tragus, lobe, antitragus, concha cavum, anti helix, concha cymba
fn: acoustic imprint & resonance; localize, catch & direct sound into EAM

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outer ear: EAM size, parts, fn

pinna=> Tm
25 cm L by 9mm H by 6.5mm D
fn: protect, provide resonance
outer: cartilaginous, cerumen, sebaceous, hair
inner: osseous, tympanic portion of temporal bone

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outer ear: cerumen fn- TOCRAM

Repel water
Trap dust, sand particles, micro-organisms, and other debris
Moisturize epithelium in ear canal
Odor discourages insects
Antibiotic, antiviral, antifungal properties
Cleanse ear canal

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outer ear: EAM problems

osseocartilaginous junction of two: mandible fits into temporal bone TMJ=> otalgia
stenosis
fungal/bacterial infex- swimmers ear, wax impaction
all cause a CONDUCTIVE HL

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outer ear: tympanic membrane size, fn

border btw inner/middle ear
90mm^2, 17.5 mm diameter
conical loudspeaker- middle ear transformer system
middle ear pressure regulation
rich blood supply

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outer ear: tympanic membrane divisions

annulus- holds TM in place
pars flaccida- Top 15% of the TM, no fibers
pars tensa- all three layers Gives conical shape- cone of light reflection, Malleus

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outer ear: tympanic membrane layers

outer: extensionf of EAM, Cutaneous stratum, skin over osseous meatus
Fiberous stratum: tough CT, concentric and radial fibers
inner: Mucosa Stratum=> middle ear

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outer ear: tympanic membrane landmarks

manubrium (long portion) of malleus
cone of light
umbo- most depressed part of TM,
long process of incus
stapes

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outer ear: resonance

air filled cavities have natural/resonant frequencies
each structure increases the sound pressure of said frequency by 10-12 dB
primary structures: concha (10 dB, best @ 5 kHz) and EAM (10dB, best @ 3 kHz) = 20 dB amplification

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outer ear: localization

outer ear “encodes” vertical elevation of sound source in the amplification of the sound (+15 degrees azimuth= greater amp)
efficiency of sound collection encodes horizontal location (azimuth)- attenuation from back

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examination HOP

history: trauma, allergy/sick, fly/dive, dizzy, hearing, duration
observation: red, swell, drain, object, cuts etc
palpation: press on tragus, traction on lobe and helix

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otoscopic assessment procedure

1: sit, head down and away, cocked
2: largest comfortable speculum- snug, rest against
tragus
3. stabilize otoscope w ring and little finger “hammer or pencil”
4. pinna up and back to straighten canal
5. approach canal, watching through lens
6. rotate speculum to see TM
7. inspect color clarity position
8. identify landmarks
9. look for abnormalities

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otoscopic assessment points

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color: pearly gray
clarity: semitransparent
position: neither retracted nor bulging
landmarks: malleus, manubrium, short process, umbo, light reflex (cone), pars flaccida and tensa, annulus, stapes, incus
abnormalities: fluid, perforations

middle ear: parts and fn

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chamber
bones- malleus incus stapes=> impedance match
muscles- stapedial, tensor tympani=> protection, compression of loud sounds (acoustic reflex)
ET (tensor/levator veli palatini)=> equalize air pressure, drainage

TM innervation

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trigeminal>mandibular>Auriculo temporal nerve
Vagus nerve
Medial- glosspharyngeal nerve
Damage to facial nerve– may affect hearing as well
Damage to ear drum can also affect facial nerve- taste etc

middle ear bones (ossicles)

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malleus- contacts TM
incus- middle
stapes- smallest, inner most, footplate rests in membranous oval window
suspended by axial ligaments

middle ear muscles: O, I, Fn

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stapedius- O: posterior mastoid wall of tympanic cavity; I: stapes; CN 8-V; contracts w loud sound
tensor tympani- origin: anterior wall of cavity; insertion- malleus; CN 5-T; contracts with touch to lateral face, air pressure changes in EAM

ET specs

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1/3 bone, 2/3 cartilaginous, 35 mm L, 45 degree angle

smaller, less steep in kids= poor drainage/opening= infex

impedance matching mechanism

30dB sound loss air sound to fluid sound, must be transformed thru middle ear "machine" 1) TM movement/lever= not much 2) malleus/incus lever 1.3:1 3) area ratio, TM: nail head as footplate: nail point, 17:1 area ratio but doesnt move as one unit (membrane) P increase at stapes = 27.4 dB gain vs initial 30 dB loss

amplified frequencies

Little pressure amplification occurs for frequencies below 100 Hz or above 2000 to 2500 Hz, but 100-2500Hz is amplified The outer ear amplifies sound energy by 20 dB for frequencies from 2000 to 5000 Hz (3000)

middle ear muscle contraction- acoustic reflex

``` in response to loud sound/touch results in attenuation of sounds by: 1) tightened TM 2) reduced trasnmission 3) draw malleus back consensual- both ears respond .03s-.04s delay ```

inner ear: parts

``` petrous portion of temporal bone osseous labyrinth- bony outer casing semicircular canals (sup, lat, pos) vestibule> oval window & round window cochlea ```

inner ear: balance

utricle and saccule: linear motion | semi circular canals: rotary/angular motion

inner ear: cochlea fn

end organ for hearing breaks complex sounds into pure tones tune and amplify incoming sounds transmit info to central auditory nerve

inner ear: cochlea parts

snail shell, 2.5 turns around bony modiolus bony labyrinth>membranous labyrinth> three canals: scala vestibuli (PL)> oval window, reisner's mem scala media (EL)> reisner's mem, spiral ligament (clips), organ of corti, stria vascularis, basilar mem scala tympani (PL)> round window helicotrema port connects SV and ST

inner ear>cochlea>organ of corti

hearing organ supporting cells- pillar, deiters, henson, claudius sensory cells- single row of inner hair, more outer hair under tectorial membrane above basilar membrane

inner ear>cochlea>tectorial membrane

90% water, gelatinous projects from spiral limbus longest sterocilia projections from OHC embed here

sound transmission

stapes footplate>oval window vibrates and establishes wave along basilar membrane> wave crests and decreases> depression of SM >BM displaced, shear the tectorial-embedded cilia of OHC> contracts and pulls Tect Mem down which in turn presses IHC> electrochemical processes> auditory nerve fibers *lower frequencies move/travel entire membrane- stimulates most responsive place* rate of discharge increases with intensity, but maxes at 30-40 dB, then recruits other neurons to express loudness up to 140 dB, density of action potentials encodes loudnes

inner ear>cochlea>basilar membrane

varies in width/stiff from base to apex narrower and stiffer at base creates tonotopic map

OHC vs IHC

OHC- more #, weak afferent, strong efferent, motor | IHC- fewer, sensory

central pathway- cannibals

``` Eighth nerve- aud branch Cochlear nuclear complex Superior olivary complex Lateral lemniscus Inferior colliculus Medial geniculate body Primary auditory cortex ```

cranial nerves- viking

``` Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglossal ```

auditory nerve

cylindrical bundle outer- basal turn of cochlear (high freq) inner- apical turn (low freq)

cochlear nuclear complex- tooonic

dorsal ventral leave in 3 stria fibers: onset, offset, onset/offset, tonic

super olivary complex-Soccer ball

relay reflex- stapedius, tensor tympani bilateral input localization (from time/intensity differences)

lateral lemniscus- lilac

Ipsilateral IC projections but some to contra IC lower brainstem Pathway Afferent portion of auditory pathway Connects SOC to IC

inferior colliculus- SMITS

``` SOCs stim midbrain ipsi MGB projection tonotopic 400k synapse- 2nd oblig ```

medial geniculate body- thick pac

thalamic nuc 422k tonotopic cells primary aud cortex

primary auditory cortex- million TReeS

temporal lobes representation of freq 10 million tonotopic cells sylvian fissure

audio-exam 1 Flashcards

(45 cards)