USMLE Neurology of Hearing
Terms
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the scala vestibuli lies where in the cochlea?
Contians endolymph or Perilymph? - superior to the cochlea duct and abuts the oval window and contains perilymph.
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the scala tympani lies where in the cochlea?
Contians endolymph or Perilymph? - inferior to the scala media and terminates at the round window and contains perilymph
- the scala media lies where in the cochlea?
- forms the membraneous cochlea duct containing the organ of Corti. It contains endolymph
- location where the scala tympani and the scala vestibuli merge?
- the helicotrema
- What membranes separates the scala vestibuli from the scala media
- Reissner's membrane
- What membrane separates the scala media from the scala tympani.
- basilar membrane
- What structure contains a cellular layer sitting on top of the basilar membrane which has sterocilia
- Organ of Corti
- What structure transmits to the fenestra ovalis (oval window) on the outside of the cochlea, which vibrates the perilymph in the scala vestibuli.
- Stapes
- The vibrating perilymph causes?
- endolymph in the scala media to vibrate, thus causing movements of the hair bundles of the hair cells
- The acoustic sensor cells that convert vibration into electrical potentials.
- bundles of the hair cells
- The hair cells in the organ of Corti are tuned to certain sound frequencies, being responsive to high frequencies near the ____ and to low frequencies near the ____.
- oval window (high frequency)and apex of the cochlea (low frequency)
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Very low frequencies (below 20Hz). Describe the route?
Note:do not activate the organ of Corti and are below the threshold for hearing. - the pressure waves propagate along the complete route of the cochlea - up scala vestibuli, around helicotrema and down scala tympani to the round window
- Higher frequencies do not propagate to the helicotrema but are transmitted through the?
- endolymph in the cochlea duct to the perilymph in the scala tympani.
- A very strong movement of the endolymph due to very loud noise may cause
- hair cells to die.
- The hair cells are arranged in four rows in the Organ of Corti along the entire length of the cochlear coil. Three rows consist of outer hair cells (OHCs) and one row consists of inner hair cells (IHCs). What is the role of each?
- The inner hair cells provide the main neural output of the cochlea. The outer hair cells, instead, mainly receive neural input from the brain, which influences their motility as part of the cochlea’s mechanical pre-amplifier.