The membranous contains two fluids called perilymph and endolymph. This tightening prevents the vibrations from disturbing the perilymph. This hammering causes the fluid within the cochlea (perilymph and endolymph) to be displaced. The electrochemical gradient makes the positive ions flow through channels to the perilymph. This can result in leakage of the perilymph into the middle ear. Both structures exist in a low potassium fluid called perilymph. The two outer are filled with perilymph and the inner with endolymph. The wave in the perilymph moves away from the footplate and towards the helicotrema. For the organ of Corti, the basilar membrane is permeable to perilymph. Both the scala vestibuli and the scala tympani contain an extracellular fluid called perilymph. The perilymph in the scala tympani has a very low concentration of positive ions. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid. They contain a clear fluid, the perilymph, in which the membranous labyrinth is situated. Perilymph is low in potassium and high in sodium. Perilymph is an extracellular fluid located within the inner ear.