Scala tympani

Scala tympani
Interior of right osseous labyrinth. (Scala tympani labeled at right, inside cochlea.
Cross section of the cochlea. (Scala tympani labeled at bottom, spelled as 'scala timpani'.)
Gray's	subject #232 1050
MeSH	Scala+Tympani
Dorlands/Elsevier	s_03/12721078

Scala tympani is the name of one of the perilymph filled cavities in the cochlear labyrinth. It is separated from the scala media by the basilar membrane, and it extends from the round window to the helicotrema, where it continues as scala vestibuli.

The purpose of the perilymph filled scala tympani and scala vestibuli is to transduce the movement of air that causes the tympanic membrane and the ossicles to vibrate, to movement of liquid which, depending of frequency, causes the basilar membrane to reach a peak amplitude at a specific site. This movement is conveyed to the organ of Corti inside the scala media, composed of hair cells attached to the basilar membrane and their sterocilia embedded in the tectorial membrane. The movement of the basilar membrane compared to the static tectorial membrane causes the sterocilia to bend. They then depolarise and send impulses to the brain via the cochlear nerve. This produces the sensation of sound.

Additional images

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  Transverse section of the cochlear duct of a fetal cat.

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  The cochlea and vestibule, viewed from above.

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  Diagrammatic longitudinal section of the cochlea.

External links

• Slide from University of Kansas
• Diagram at IUPUI
• Scala+tympani at eMedicine Dictionary
• Image at University of New England, Maine