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Science Series Part 9: The Ossicles

Emily Martinson, AuD, PhD

Just when you least expect it, the Science Series is back!  If you recall previous Science Series posts, we have been working our way through the human ear one step at a time.  So far, we’ve covered the outer ear, ear canal, and eardrum.  Our next step is the middle ear, which is composed of two parts: the bony ossicles, and the Eustachian Tube.  Today we will focus on the ossicles.

The middle ear is an air-filled cavity that separates the eardrum from the inner ear (more on the inner ear later).  Inside that cavity are the three smallest bones in the human body: the hammer, the anvil, and the stirrup.  The scientific name for these bones are the malleus, incus, and stapes, and the entire chain of bone is known as the ossicles.

The ossicles serve a very important role in hearing.  The end of the malleus (hammer) is connected to the eardrum.  When the eardrum vibrates, it also vibrates the malleus.  Because the malleus is connected to the incus (anvil), and the incus is connected to the stapes (stirrup), when the malleus vibrates the whole chain starts to move.

The end of the stapes is connected to the inner ear, which brings the vibration from the bone all the way to the inner ear hearing organ.

While the middle ear ossicles work very well for most of us, it is possible to have a break in these bones, or to have an issue with the bone that may require surgery. There are even some medical conditions that can impact the ossicles.  Stay tuned to the Science Series for more on anatomy!