ANATOMY

Detailed explanation-1: -During the tenth week of development, this cartilaginous shell undergoes vacuolization to create the two perilymphatic spaces of the cochlea, the scala vestibule, and the scala tympani. Two membranes separate the cochlear duct proper, which is also known as the scala media, from the scala tympani and scala vestibule.

Detailed explanation-2: -The scala vestibuli and scala tympani are filled with perilymph, which has a composition similar to that of the extracellular fluid (high in sodium, and low in potassium; Fig. 128.4A). The scala media is filled with endolymph, which has a similar composition to the intracellular fluid (low in sodium, high in potassium).

Detailed explanation-3: -The cochlea maintains two compositionally distinct fluid compartments, the scala vestibuli/tympani and the scala media, which are filled with perilymph and endolymph fluids, respectively (reviewed in Ferrary and Sterkers, 1998).

Detailed explanation-4: -The mechanical vibrations of the stapes footplate at the oval window creates pressure waves in the perilymph of the scala vestibuli of the cochlea. These waves move around the tip of the cochlea through the helicotrema into the scala tympani and dissipate as they hit the round window.

Detailed explanation-5: -Perilymph is an extracellular fluid located within the inner ear. It is found within the scala tympani and scala vestibuli of the cochlea. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid.