Hearing and Balance Flashcards
Tympanic Membrane
Border b/w external and middle ear
Innervation: CN V (trig), CN VII (facial), CN IX (gloss)
3 ossicles of the middle ear
Malleus
Incus
Stapes
2 types of hearing loss
Conductive (acquired or congenital)
* Outer ear
* Middle ear
Sensorineural (acquired or congenital)
* Inner ear
* Auditory nerve
* Higher brain centres involved in auditory
processing
gross anatomy of the ear
where are the hair cells
Auditory sensory receptors (hair cells) are in located in the cochlear
Scala vestibuli
Perilymph:
superior most duct of the cochlea duct
Scala media
Endolymph
Scala tympani
Perilymph:
where is the Reissner’s
membrane
between scala vestibuli and scala media
where is the tectorial/basilar membrane
between scala media and scala tympani
Two membranes that divide the cochlear into three compartments
Membranes:
Reissner’s (vestibular)
Basilar
Compartments:
Scala vestibuli
Scala media
Scala tympani
Three rows outer hair cells role
Detection, amplification of sound
One row inner hair cells role
Fine discrimination
Explain how sound waves energy enters the ear to
activate hair cells of the cochlea.
- Sound waves reach the tympanic membrane
- Ossicles (malleus, incus, stapes)
- Oval window
- Pressure waves in perilymph
- Vibration of basilar membrane
- Movement of hair bundles
- Generation of receptor potential
- Neurotransmitter release
- Activation of postysynaptic receptors on afferent terminal
- Electrical activity evoked in VIIIth nerve
Both hearing and balance are special senses
carried by ….
vIII
Name and locate the semicircular canals
(cristae ampullares), utricle, and saccule –
