Your inner ear is a three-part structure and the innermost part of your hearing system. Your inner ear has two tasks: Making it possible for you to hear and helping you keep your balance.
What we think of as the “ear” is actually a three-part structure. The outer ear is the part you see and your ear canal. The middle ear is a box-shaped area behind the tympanic membrane (eardrum) that includes the three smallest bones in your body. And the inner ear is just beyond the middle ear, in a small hole in the temporal bones that help make up the sides of your skull.
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Your inner ear has two tasks: Making it possible for you to hear and helping you keep your balance.
Your inner ear is the last stop that sound waves make in a carefully orchestrated journey that starts from your outer ear. These waves travel from your outer ear through your middle ear to your inner ear. In the inner ear, the sound waves are converted into electrical energy, which your hearing nerve delivers to your brain as sound, making it possible for you to hear.
At the same time, your inner ear monitors your movements, alerting your brain to changes so your brain can let your body know what to do to stay balanced.
Your inner ear has three main parts: your cochlea, semi-circular canals (labyrinth) and your vestibule. Your cochlea supports your hearing and your vestibule and semi-circular canals support your balance.
Your cochlea is filled with fluid and shaped like a snail, tapering from a wide end called the base to a narrow head called the apex. The base is most responsive to high-pitched sounds (like birds chirping) while the apex is most responsive to low-pitched sounds (like a bass drum).
The cochlea is split into three tubes by two thin membranes. One of these membranes — the basilar membrane — is like an elastic wall, on top of which sits the organ of Corti.
In the organ of Corti, there are tiny cells called hair cells. These cells are so small that the approximately 18,000 cells in your cochlea could fit on the head of a pin.
Stereocilia are on top of these hair cells. Stereocilia are delicate, hair-like projections that react to cochlea fluid movement. There are two kinds of hair cells — inner hair cells and outer hair cells. The inner hair cells are most responsive to louder sounds; the outer hair cells are most responsive to softer sounds.
Each hair cell also has a connection to the hearing nerve, but the inner hair cell is most responsible for sending sound through the hearing nerve to the brain. The outer hair cells alert the inner hair cells to softer sounds.
Here’s how the cochlea turns sound waves into sounds:
Semi-circular canals are tubes coiled within your inner ear. Like the cochlea, the canals are filled with liquid and lined with hair cells. Instead of sound waves, these tiny hairs react to body movements. They’re mostly responsible for rotary motion, or motion not in a straight line.
The utricle and saccule in the vestibule are mostly responsible for forward/backward and up/down motion.
Here’s how the vestibular system works:
Your hearing and your sense of balance rely on a healthy inner ear. Several conditions and disorders can affect your inner ear. Some inner ear conditions, such as acoustic neuroma or Ménière disease, can affect your hearing and your sense of balance.
Healthcare providers use several tests to diagnose inner ear problems, particularly problems with balance. Here are a few examples of inner ear tests:
There are several ways to protect your inner ears from hearing loss. Here are a few:
A note from Cleveland Clinic
Your inner ear is a complicated, delicate and essential part of your body. Every minute of every day, your inner ear turns sound waves into sounds that keep you safe and enrich your life. It also helps you stay balanced. Hearing loss and balance problems can come without warning and can get worse over time. Talk to your healthcare provider as soon as you suspect there might be something wrong with your hearing or balance.
Last reviewed by a Cleveland Clinic medical professional on 10/21/2022.
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