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noun, plural: endolymphs

The body fluid in the membranous labyrinth of the inner ear


An endolymph is a body fluid that is contained in the membranous labyrinth of the inner ear. The membranous labyrinth is located inside the bony labyrinth. There is another body fluid found in the inner ear apart from the endolymph. It is called perilymph and is located between the outer wall of the membranous labyrinth and the wall of the bony labyrinth. Thus, endolymph should not be confused with the perilymph. The endolymph and the perilymph also differ in terms of ionic composition. The amount of potassium is higher than sodium in the endolymph, which accounts for the electric potential ranging from about 80 to 90 mV more positive in the endolymph than the perilymph. This is crucial during the mechanical stimulation of the hair bundle. Because of this electrical potential difference, potassium ions flow into the hair cells. The potassium ions in the endolymph come from the stria vascularis. The stria vascularis is that part located upper portion of the spiral ligament of the cochlear duct. 1

The fluid waves in the endolymph of the cochlear duct are associated with the sense of hearing. They stimulate the receptor cells, which translate the movement into nerve impulses of which the brain perceive as sound.1 Apart from hearing, the fluid waves in the endolymph is also associated with coordinating balance.


  • Scarpa's fluid

See also:

1 Endolymph. (n.d.) Retrieved from [1]