Term
| What are the functions of the ear? |
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Definition
- Hearing - External, middle, and inner
- Balance - only inner |
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Term
| What are the structures of the external ear? |
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Definition
- Auricle/pinna - directs sound waves into the ear canal
- External acoustic meatus - auditory canal. Contains hair and ceruminous glands to protect against foreign objects
- Tympanic membrane - vibrates w/ sound |
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Term
| What are the features of the middle ear? |
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Definition
- Vestibular and cochlear window
- Eustachian tube/pharyngotympanic connects middle ear to nasopharynx
- Ossicles - transmit vibrations from external ear to inner ear
- 3 bones: malleus, incus, stapes |
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Term
| What are the 2 muscles of the middle ear? |
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Definition
- Tensor tympani - attaches to malleus/hammer, tenses eardrum
- Stapedius - Attachest to stapes/stirrup, limits movement
**Protects from transmission of very loud sounds. |
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Term
| What are the features of the inner ear? |
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Definition
- Bony Labyrinth - contains perilymph
- Memranous labyrinth - suspended within bony labrynth, contains endolymph
- Peri and endolymph conduct vibrations for hearing and respond to position for equilibrium |
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Term
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Definition
| In the inner ear, the site of the maculae, which read the position of the head relative to GRAVITY and linear forces |
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Term
| What are the semicircular canals? |
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Definition
| In the inner ear - 3 loops. The ampulla reads changes in head position. |
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Term
| What are the features of the cochlea? |
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Definition
Three chambers:
- Scala vestibuli - continuous with vestibule next to oval window
- Scala media - houses organ of corti, which has receptors for hearing
- Scala tympani - terminates at round window |
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Term
| What membranes are part of the cochlea? |
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Definition
- Vestibular/stria vascularis - secretes endolymph. SITE OF OTOTOXICITY OF LOOPS
- Basilar - sound reception |
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Term
| What are the hair cells in the organ of corti? |
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Definition
- Inner hair cells - 1 row, for hearing
- Outer hair cells - 3 rows, protect inner hair cells
**Reversible ototoxicity: Salicylate/ASA
**Irreversible: aminoglycosides, Cisplatin |
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Term
| How does sound transmit in the ear? |
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Definition
- K causes depolarization, not sodium
- Stapes sets perilymph in scala vestibuli in motion
- Basilar membrane vibrates
**Short, stiff fibers near oval window = high frequency
**Long, limber fibers near apex = low frequency |
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