[TA] a series of cavities (for example, cochlea, vestibule, and semicircular canals) contained within the otic capsule of the petrous portion of the temporal bone; the bony labyrinth is filled with perilymph, in which the delicate, endolymph-filled membranous labyrinth is suspended. See also: otic capsule. Synonym(s): labyrinthus osseus [TA], osseous labyrinth