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Flashcards in 123. Middle_Inner ear Deck (14):
1

middle ear components

--tympanic cavity (3 compartments in dog, 2 cat)--tympanic membrane--auditory tube--nerves --ossicles connect tympanic membrane to inner ear (malleus, incus, stapes) and concentrate sound waves to inner ear fluid environment

2

tympanic cavity compartments in dog vs cat

dog 3--dorsal--epitympanum (smallest)--middle--mesotympanum--ventral--hypotympanum (largest)cat 2--rostrolateral (epi and mesotympanum--small)--ventral (hypotympanum--large)thin boney shelf separates --promontory bone is more prominent and exposed in cats than dogs (more prone to neuro damage/deficits)lining = contiguous with respiratory (nasopharyngeal) epith via auditory tube (cubodial/ciliated/some squamous cells)

3

inner ear components

vestibulecochleasemicircular canalsall contain fluid (endolymph) and receive concentrated sound waves from external ear thru the middle ear via ossiclesinnervated by vestibulocochlear nerve VIIIfx: sound perception and balance

4

3 ways bacT get into the ear

1. external ear canal/external auditory meatus**2. nasopharynx via auditory tube3. hematogenousothers: FB, bites, para-aural abscess

5

most common organisms in middle ear

staph intermediuspseudomonasmalessezia

6

middle ear polyps

sterile, inflammatory, non neoplasticyoung cats +/- viral infectionsoriginate from epith of tympanum or auditory tubecan go into nasopharynx, tympanic cavity, or out external ear canaltx traction (recur 10-50%)Tx VBO cats---LBO/TECA dogs

7

cholesteatomas

destructive, expanding keratinized squamous epith +/- infection +/- metaplasiabrachycephalic breedsRO neoplasiaTX: lateral or ventral BOprognosis guarded, recurrence occurs

8

primary secretory otitis media

cavalier king charles spanielsaccumulate mucinous material within tympanic cavity suspect congenital dysfunction of drainage of the auditory tube

9

cause of sterile otitis media

ciliary dyskinesis (congenital)

10

changes to the tympanic membrane that can be seen on otoscopy and lead to suspicious middle ear dz

--buldging--rupture--change of color--thickening/loss of transparencymay need myringotomy for cultures, cytology, biopsy if indicated

11

what does BAER stand for

brainstemauditoryevokedresponsehearing test (screen dalmatians)other test is impedance audiometry

12

name of tube for tympanostomy drainage

myringotomy, lavage (culture, histopath)Reuter Bobbin vent tube

13

T/Fdespite risks of ototoxicity with systemic use, topical amino glycosides (gentamicin) in the middle ear does not result in ototoxic concentrations in the vestibular apparatus

TRUE

14

complications following VBO in cats

hornersvestibular

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