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69 Cards in this Set
- Front
- Back
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what are the 5 parts of the temporal bone?
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squamous
matoid petrous tympanic styloid process |
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what are the components of the external ear?
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auricle
external auditory canal |
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what are the components of the middle ear?
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TM
middle ear cavity Ossicles |
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What are the components of the inner ear?
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cochlea
vestibule semicircular canals |
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what are the 2 parts of the TM?
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pars densa
pars flaccida |
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describe the origin of the pars densa.
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3 layers (ectoderm, endoderm, mesodermal layer w/ elastic fibers)
robust, majority of TM |
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where are most perfs on the TM?
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pars densa
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describe the pars flaccida
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2 layers (no mesoderm)
fragile origin for most cholesteatomas |
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cholesteatoma makes you think injury is where?
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pars flaccida
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what innervates the tensor tympani?
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CN V
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what innervates the stapedius?
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CN VII
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why do most people have taste changes after ear surgery?
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b/c the CN VII carries taste from anterior 2/3 of tongue and the chordae tympani courses through the ear
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what is the fcn of the inner ear?
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sound transmission and amplification to the inner ear
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what is the ratio of the size of the TM to the stapes footplate?
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'17:1
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how many turns is the cochlea in the human?
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2.5
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what nerves run in the membranous labyrinth?
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superior vestibular
inferior vestibular cochlear facial |
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where is the endolymph?
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membranous labyrinth
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perilymph is like...
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CSF (Na+ rich)
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endolymph is like ...
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Intracellular fluid (K+ rich)
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high freqencies are heard...
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at the base of the cochlea
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low frequencies are heard...
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at the apex of the cochlea
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the cochlear duct contains...
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endolymph
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perilymph is contained in...
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the scala tympani and scala vestibuli
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how does the organ of Corti work?
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mechanoelectrical transduction
shearing force from the wave is translated into K+ influx |
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where is the boundary b/w conductive and sensorineural hearing loss?
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footplate of the stapes
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where does the weber test lateralize?
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to the ear w/ conductive loss (away from the sensorineural loss)
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how do you interpret the Rinne test?
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if louder when fork on mastoid, conductive loss. (should be louder when held in front of ear canal)
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what's the hardest bone in the human body?
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petrous portion of the temporal bone!
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What is the dB range of human hearing?
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-10-20
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gap b/w bone and air conduction in pure tone audiometry -->
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conductive hearing loss
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T or F: speech audiometry is impaired in conductive hearing loss?
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False! Only in SNHL
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otoacoustic hearing loss is a function of __
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outer hair cells (first thing to go w/ hearing loss)
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how does Auditory brainstem response work?
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it's like an EEG after acoustic stimulation. The 5 waves represent different locations in central auditory pathway.
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what does a type A tympanometry imply?
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normal compliance (middle ear and EAC pressure similar)
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B-normal volume tympanogram -->
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fluid
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B-large volume tympanogram -->
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perforation
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What does a type C tympanogram imply?
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negative pressure (Eustachian tube dysfunction)
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what is otosclerosis?
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bone re-formation of otic capsule resulting in fixation of stapes footplate leading to progressive conductive hearing loss
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what is the inheritance of otosclerosis?
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AD w/ incomplete penetrance (20%)
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who gets otosclerosis?
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young female w/ hormonal changes
look for young woman w/ hearing loss after having a baby. |
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what are some Rx for otosclerosis?
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hearing aids, stapes sugery (stapedotomy)
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what is otitis media?
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inflammatory process of the middle ear space and mastoid air cell space (no reference to cause or pathogenesis)
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what is chronic suppurative OM?
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OM w/ ear canal discharge
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what is OM w/ effusion?
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OM w/ intact TM
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pt w/ chronically draining ear -->
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suppurative OM w/ cholesteatoma
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what is the main cause of chronic OM?
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eustachian tube dysfunction
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what is luminal obstruction w/ subsequent impairment of pysiologic gas homeostasis, drainage, ciliary clearance?
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eustachian tube dysfunction
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what are some causes of ETD w/ normal anatomy?
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extrinsic factors: adenoids, nasopharynx mass
intrinsic factors: edema, inflammation |
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what are some causes of ETD w/ abnormal tube?
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cleft palate, childhood tube
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an adult w/ normal hearing all their life and then has OM w/ effusion. what do you have to r/o?
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nasopharyngeal mass
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what are the most common causes of acute OM?
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S. pneumo
H. influenzae |
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Chronic suppurative OM w/o cholesteatoma -->
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TM perf
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what are some sx of chronic suppurative OM?
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chronic purulent otorrhea (w/ perf)
ongoing inflammation hearing loss |
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what causes atelectasis? (the TM becoming attached to the inner ear structure)
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longstanding ETD
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T or F: cholesteatoma is made of cholesterol
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False! It's keratin
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skin that has gained access to the middle ear that destroys bone by chronic inflammation -->
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cholesteatoma
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chornically draining ear --> you're thinking
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cholesteatoma or TM perf
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in what order do cells become damaged in sensorineural hearing loss?
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1. outer hair cells
2. inner hair cells 3. spiral ganglion cells 4. mechanical impairment |
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high or low: sudden SNHL
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usually high-freqs lost
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what are some causes of sudden SNHL?
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viral (infection or reactivation)
vascular occlusion (DM) vestibular schwannoma (1% of cases) |
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what is presbycusis?
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bilateral HL which is age related
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what are some causes of ototoxicity?
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aminoglycosides
cisplatin salicylates loop diruretics (furosemide) |
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what is an AR cause of hereditary SNHL?
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Pendred's (hypothyroidism)
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What is an AD cause of hereditary SNHL?
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Waardenburg
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What is an X-linked cause of hereditary SNHL?
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Alport's syndrome
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non-syndromic SNHL -->
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Connexin 26 mutation (AR)
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What is a vestibular schwannoma?
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benign tumor of CN VIII
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what are some sx of vestibular schwannoma?
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unilateral hearing loss, positional unsteadiness, occasional vertigo, imbalance
These are collectively called cerebellar pontine syndrome |
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unilateral SNHL, what do you do?
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get and MRI (r/o schwannoma)
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