You usually think of your ears for hearing, but did you know they also help you maintain your balance? In this lesson, you will learn about the structures of the inner ear and how they help support hearing and your sense of balance.
When your mom tells you, 'It's time to clean your room,' I'm sure you know that you use your ears to hear her. But did you know that her words have to be sent to your brain for interpretation in order for you to understand them? If your ears weren't working with your brain all you would hear would be 'blah blah blah blah blah blah.'
You see, your outer ear, which is the part you can touch, collects sound waves from the world around you, but your brain can't read sound waves, so your ear must change them into a language your brain understands, namely nerve impulses. To do this, your middle ear turns the sound waves into vibrations, which are then passed on to your inner ear. It is your inner ear that uses the vibrations to create nerve impulses that travel to your brain. Creating nerve impulses from the sounds that enter your ear is not the only thing your inner ear does, it also helps you keep your balance. In this lesson, we will take a closer look at how your inner ear helps support hearing and balance.
Cochlea & Hearing
To best understand the inner ear, let's take one step back and look at the three tiny bones of your middle ear, which are collectively referred to as the ossicles. They are the smallest bones of your body, with the smallest one of all being the stapes, or stirrup. It gets its name because it looks like the stirrup, or footrest, of a horse's saddle. This bone connects to the oval window, which is a membrane that separates the middle ear from the inner ear.
When the stapes vibrates, it makes the oval window move in and out. This movement pushes on fluid found in the cochlea of the inner ear. The cochlea is a fluid-filled tube that converts vibrations into nerve impulses. If you look at a picture of the cochlea it looks like a snail; in fact, cochlea means 'snail' in Latin, which is how it got its name. If we took a look inside the cochlea we would see that it's lined with tiny hairs. As the fluid in the cochlea gets pushed in and out, it moves the hairs, creating nerve impulses that your brain can read and understand. How exactly does your brain know that your mom said 'clean your room' and not 'blah, blah, blah'? Well, that's still something of a scientific mystery.
Semicircular Canals & Balance
The other end of the inner ear has three loops or semicircles. These are the semicircular canals and they help you with balance. Like the cochlea, they are filled with fluid and contain tiny hairs. When you tilt your head to the side, the fluid inside the semicircular canals moves as well, just like water moves when you tip over a glass. This movement of the fluid moves the hairs, creating nerve impulses that travel up to your brain and let it know that your head is off balance. Within a split second your brain gets on the phone with the muscles of your body so you are properly supported, otherwise the weight of your head could pull you over and make you fall.
Did you ever feel dizzy after spinning in circles for a while? You can blame your dizziness on the semicircular canals. When you spin, the fluid in your semicircular canals goes with you, but if you stop quickly, the fluid in the canals keeps going fooling your brain into thinking you are still moving. When the fluid stops flowing, your dizziness goes away, and you regain your balance.
Let's review. In order for you to hear and understand what you are hearing, your outer ear, collects sound waves, your middle ear turns the sound waves into vibrations and your inner ear uses the vibrations to create nerve impulses that travel to your brain. In this lesson, we focused on the inner ear and how it not only supports hearing, but also balance.
We learned that the oval window is a membrane that separates the middle ear from the inner ear. It moves in and out when the stapes that is attached to it vibrates. This movement pushes on fluid found in the cochlea of the inner ear, which is a fluid-filled tube that converts vibrations into nerve impulses. More specifically, as the fluid in the cochlea moves it moves tiny hairs within the cochlea, creating nerve impulses that your brain can understand.
The semicircular canals of the inner ear help you with balance. When you move your head, fluid inside the semicircular canals moves as well. This movement of the fluid moves the hairs of the canals, creating nerve impulses that travel up to your brain and let it know that your head is off balance. You don't fall over because your brain tells your muscles to support you.
After watching this lesson, you should be able to:
- Identify the main functions of the three parts of the ear
- Describe how the cochlea helps your brain interpret the sounds around you
- Examine the role semicircular canals play in helping with your sense of balance