The anatomy of the inner ear is dominated by large fluid-filled spaces. The inner ear consists of a complex series of tubes, running through the temporal bone of the skull. The bony tubes (sometimes called the bony labyrinth) are filled with a fluid called perilymph. Within this bony labyrinth is a second series of tubes made out of delicate cellular structures (called the membranous labyrinth). The fluid inside these membranous structures is called endolymph, The different spaces of both the perilymphatic and endolymphatic compartments are interconnected by a series of ducts.