Word for the Day Archive

Ossicles

One might think that "ossicles" are formations caused by dripping water at freezing temperatures (when spoken with a southern accent). However, this is not the case. Ossicles (also known as auditory ossicles) are three bones (incidentally the smallest in the human body) contained within the middle ear. The function of the ossicles is to transmit sound to the cochlea, which is a fluid-filled tunnel that is curled in a spiral shaped like a snail shell. Named by the shape of the bones, the ossicles comprise the hammer, anvil, and stirrup (in order from the eardrum to the inner ear). They are also referred to by the Latin terms: malleus, incus, and stapes, respectively. Their function is as follows: As sound waves vibrate the eardrum, it in turn moves the nearest ossicle, the malleus to which it is attached. The malleus then transmits the vibrations, via the incus, to the stapes, and ultimately to the oval-shaped opening of the inner ear. If the sound waves were transmitted directly from the outer ear to the oval window, the resulting vibrations would be much smaller. By virtue of a lever action, the ossicles amplify the vibrations via mechanical advantage, which is the factor by which a machine multiplies force applied to it. According to theory, the muscles controlling the movement of the ossicles can contract to dampen the vibration of the ossicles in order to protect the inner ear from excessive SPL and to provide better frequency resolution at higher frequencies by reducing the transmission of low frequencies.