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Middle ear
The correct Answer is
a) eustachian tube orifice
Middle ear
- Tympanic cavity
- Anterior wall – eustacian tube opens into anterior wall. Connects nasopharynx w/ middle ear
- Why this is good – equalizes pressure buildup, which could potentially rupture the tympanum
- Why this is bad – it’s a communication. This means infection can spread b/w the two areas
- Lateral wall – chorda tympani (CN VII) runs along lateral wall. Conveys taste from ant 2/3 of tongue and presynapic parasympathetics to submandibular ganglion
- Posterior wall – communicates w/ mastoid air cells, which means middle ear infections can spread there. Difficult to treat!
- Medial wall
- Oval window – transmits vibration from stapes to the perilymph of scala vestibuli
- Tympanic plexus – passes along tympanic bulla.
- Carries sensory info from tympanum and external auditory meatus (CN’s IX and X).
- Lesser superficial petrosal nerve – emerges from plexus. Carries p.p. of CN IX to otic ganglion
- Round window – functions to dampen pressure waves transmitted to scala tympani
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