inner ear The structure in vertebrates, surrounded by the temporal bone of the skull, that contains the organs of balance and hearing. It consists of soft hollow sensory structures (the membranous labyrinth), containing fluid (endolymph), surrounded by fluid (perilymph), and encased in a bony cavity (the bony labyrinth). It consists of two chambers, the sacculus and utriculus, from which arise the cochlea and semicircular canals respectively.

in·ner ear • n. the semicircular canals and cochlea, which form the organs of balance and hearing and are embedded in the temporal bone.

inner ear (in-er) n. see labyrinth.