APA Dictionary of Psychology

pl. n. any small bones, but particularly the auditory ossicles: the chain of three tiny bones in the middle ear that transmit sound vibrations from the tympanic membrane (eardrum) to the oval window of the inner ear. They are the malleus (or hammer), which is attached to the tympanic membrane; the incus (or anvil); and the stapes (or stirrup), whose footplate nearly fills the oval window. The ossicles allow efficient transmission of sound from air to the fluid-filled cochlea.