Observations on the circulation in the cochlea.

A STUDY of the circulation in the labyrinth, to be complete, must include an investigation of the fluid circulation. The fluid system in the labyrinth is much more complex than that of the cerebrospinal axis. In the latter, the cerebrospinal fluid, produced by the choroid plexuses, circulates by known anatomical pathways and its main function is the protection of the brain. In the labyrinth, however, there are two separate fluids about whose circulation there remains some doubt, but whose purpose is much more important than mere protection of the inner ear. The endolymph, for example, is essential for the normal metabolic transfers between the blood and the structures on the basilar membrane, for the latter are not provided with blood vessels. The purpose of this paper is to deal, first, with the blood circulation mainly in the spiral ligament of the cochlea, then to consider the fluid systems, and, finally, to try to indicate how departures from the normal physiological states may contribute to pathological findings.