The inner ear: Anatomy, common health conditions, and more - Medical News Today

The ear is a complex organ consisting of the outer, middle, and inner ear. The inner ear is the deepest part of the ear, resting in the temporal bone. It is responsible for hearing, balance, and equilibrium.

A range of conditions may affect the inner ear, leading to hearing loss and balance problems.

Experts estimate that in the United States, as many as 35% of adults aged 40 years or older have had problems with the vestibular system. The vestibular system comprises the inner ear and the part of the brain that processes the sensory information involved in controlling balance and eye movements.

Keep reading to learn more about the anatomy of the inner ear, as well as about several health conditions that may affect this essential sensory organ.

The inner ear, or labyrinth, is the deepest part of the ear. It is located at the end of the ear canals, resting in a cavity in the temporal bone.

The inner ear consists of three parts:

• Cochlea: This small flexible, coiled structure, which is about 10 millimeters wide, supports the basilar and tectorial membranes. There are fluid-filled spaces on either side. Sound vibrations create waves in the cochlea fluid, sending signals to the brain.
• Semicircular canals: These three small fluid-filled tubes are responsible for balance. When the head moves, the liquid inside the canals creates waves and moves the tiny hairs inside them. The hairs translate the movement into nerve signals that travel to the brain.
• Vestibule: This area lies between the cochlea and semicircular canals and supports balance and equilibrium.

A range of factors can cause itchy outer ears, such as:

However, the factors that affect the inner ear are more limited.

One example is temporomandibular joint (TMJ) disorder. The TMJ is a sliding hinge joint connecting the jawbone to the skull.

TMJ disorders may cause pain, discomfort, difficulty chewing and ease symptoms such as pressure, tinnitus — or ringing in the ears — and vertigo.

An individual may experience inner ear pain due to several conditions, including:

• Autoimmune inner ear disease: This rare inflammatory condition causes a person's immune system to attack their inner ear. It can cause hearing loss, tinnitus, dizziness, and an uncomfortable feeling of ear fullness. The condition may also occur alongside other autoimmune diseases, such as rheumatoid arthritis, lupus, or ulcerative colitis.
• CANVAS syndrome: CANVAS stands for cerebellar ataxia, neuropathy, and vestibular areflexia. It is a rare condition that may cause neuropathic pain in the inner ear.
• Tumors: An acoustic neuroma, or vestibular schwannoma, is a noncancerous tumor that develops on the nerves supplying the inner ear. As the tumor grows, it compresses the nerves and may cause hearing loss, tinnitus, and loss of balance. It may also result in pain behind the ear, on the side of the tumor.

Learn about ear cancer here.

Inner ear infections are usually viral and less commonly bacterial. These infections can inflame the inner ear and the nerves that connect the inner ear to the brain.

If the infection affects both branches of the vestibulocochlear nerve, doctors call this labyrinthitis. However, if it affects just one branch, they refer to it as vestibular neuritis. A person with this condition may experience:

• hearing changes
• dizziness
• vertigo of varying degrees

In serous labyrinthitis, the bacteria that infect the middle ear produce toxins that affect the inner ear and inflame the cochlea. Serous labyrinthitis usually occurs if someone has untreated chronic middle ear infections. However, serous labyrinthitis is usually viral.

A less common condition is suppurative labyrinthitis. This happens as a result of bacteria invading the inner ear. It can start with a middle ear infection or bacterial meningitis.

Doctors encounter viral infections of the inner ear more often. However, they know less about them. A viral inner ear infection may happen because of a systemic viral illness, such as infectious mononucleosis or measles. Conversely, the infection may affect only the labyrinth or the vestibulocochlear nerve on one side.

Viruses associated with vestibular neuritis or labyrinthitis include:

Viruses may run their course and then go dormant in the nerves. When this happens, symptoms may flare up at any time.

In many cases of labyrinthitis, the virus that has caused the condition remains unidentified.

A variety of common health problems may affect the inner ear:

Hearing loss

People may lose some or all of their hearing due to damage to the inner ear's hairs or nerve cells. Healthcare professionals call this sensorineural damage.

Sensorineural damage can happen as part of the aging process, exposure to loud noises, Ménière's disease, viruses, or head trauma.

People may notice that noises seem muffled or that they cannot understand words or tell where sounds originate.

Balance issues

Balance relies on the vestibular organs of the inner ear. If the system becomes damaged through injury, disease, or aging, a person may develop balance-related problems, such as:

A common cause of vertigo is benign paroxysmal positional vertigo. It develops because the calcium carbonate crystals in the inner ear become dislodged and migrate into other areas.

The second most common cause of vertigo is vestibular migraine. During these episodes, a person may feel as if they are moving, falling, or spinning while sitting still. Headaches are not always a symptom of vestibular migraine, but individuals may experience sound and light sensitivity in common with other types of migraine.

The inner ear is at the end of the ear canals, resting in the temporal bone. It consists of the cochlea, semicircular canals, and vestibule and is responsible for hearing, balance, and equilibrium.

The cochlea converts sound into nerve impulses that the brain processes to interpret sound. The other parts of the inner ear help with an individual's balance and equilibrium.

Some conditions, such as tumors, autoimmune inner ear disease, or CANVAS syndrome, may cause inner ear pain.

Other inner ear issues may lead to balance problems, such as vertigo and dizziness, and hearing loss.

If a person is concerned about pain of the inner ear or is experiencing difficulties with balance or hearing, they should contact a doctor.