Hearing / Cochlear anatomy / Scala media
Scala media
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There are 3 critical functional regions in and around the scala media. The organ of Corti contains the sensory hair cells that transduce sound into a receptor potential. The spiral ganglion contains the cell bodies of the sensory neurons that send action potentials to the brainstem. The stria vascularis produces endolymph and generates the endocochlear potential. |
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http://www.siumed.edu/~dking2/ssb/EE004b.htm |
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http://www.siumed.edu/~dking2/ssb/EE001b.htm |
- organ of Corti:
- sits on top of the basilar membrane across its entire width: extends from the spiral limbus (inner sulcus region) to the spiral ligament of the lateral wall (outer sulcus region)
- moves when the basilar membrane vibrates
- given rigidity by an arch that separates the inner (type I) hair cells from the outer (type II) hair cells
- has numerous, varied supporting cells in addition to the hair cells
- spiral ganglion:
- found medial to the spiral limbus, inside the modiolus
- peripheral processes of the spiral ganglion neurons extend from the hair cells into the ganglion
- fibres are myelinated until they pass through the habenula perforata to reach the hair cells
- central processes form the auditory branch of the VIII cranial nerve
- stria vascularis:
- forms the medial boundary of the lateral wall, adjacent to the spiral ligament
- critical part of the potassium recycling system that moves K+ into the scala media in order to maintain the high K+ concentrations of the endolymph
- generates the endocochlear potential