Ear Anatomy and Common Conditions (2024)

The ears are a pair of sensory organs whose primary functions are hearing and balance. They are divided into three portions: the outer ear, the middle ear, and the inner ear. Each has an intricate structure of bones, nerves, and muscles.

Just like other parts of the body, the ears can be affected by bacterial and viral infections, as well as disease. Healthcare providers use a variety of tools to examine the ears and measure how well they're functioning.

Anatomy

The ears are two sensory organs. They are located at the sides of the head, directly over a person's temporal lobe, a part of the brain. They have two main functions: hearing and balance. Each ear is divided into an outer, middle, and inner section that have distinct structures.

Outer Ear

The outer ear includes two parts:

• Auricle: Also known as the pinna, this is the outer portion of the ear. It is composed of skin and cartilage and attaches to the skull.
• External acoustic meatus: Also called the external auditory canal, this tube leads from the outside of the ear to the eardrum. Its outer portion is surrounded by cartilage, and the inner part is surrounded by the bones of the skull.

Tympanic Membrane (Eardrum)

The tympanic membrane (eardrum) is the border between the outer and middle ear. It is composed of a membrane attached by fibrous cartilage to the surrounding bone. The inner surface is curved toward the middle ear and connects with the malleus bone.

Middle Ear

The middle ear (also known as the tympanum or tympanic cavity) starts on the other side of the eardrum. It is a narrow tube with concave walls that is separated from the inner ear by its labyrinthine (medial) wall.

Three small ossicles (bones) in the middle ear transmit vibrations to the inner ear:

• Malleus (hammer), which is attached to the eardrum
• Incus (anvil), which is attached to the malleus
• Stapes (stirrup), which is attached to the incus and is also the smallest bone in the human body

The eustachian tube connects the middle ear to the upper throat and nasal cavity. It's lined with mucous and helps regulate pressure around the eardrum so that sound waves can be transferred.

Inner Ear

The inner ear is a bony labyrinth that is filled with a fluid called perilymph.

The major structures of the inner ear include:

• Vestibule: A cavity that contains two sacs (the utricle and the saccule) which are receptors for balance
• Cochlea: A spiral-shaped organ that consists of three compartments that contain critical nerves for hearing
• Semicircular canals: Three semi-circular canals that contain balance receptors

Anatomical Variations

Ears can vary, so what's considered normal anatomy of the inner or outer ear in one person may be different for another. For example, 19% to 54% of people have an attached earlobe, which is a genetic variation.

Hearing

The shape of the outer ear directs sound waves from the environment to the ear canal. These waves are then directed toward the tympanic membrane (eardrum), which causes it to vibrate. The vibration passes on to the malleus, incus, and stapes, which leads the perilymph within the cochlea to vibrate. This stimulates tiny hairs on the organ of Corti, a small structure in the cochlea. This stimulation is translated into electrical signals that are delivered to the auditory nerves of the brain for processing.

Balance

Sense of balance and position is regulated by the semicircular canals in the inner ear. Each is filled with fluid and sensors. When your head changes position, the fluid moves and also moves the sensors. Those sensors transmit information on your position along the vestibular nerve to your brain. Your brain uses this intel to send signals to your muscles to keep you balanced. As the head rotates, the endolymph is displaced, exciting the cells and generating a sense of balance.

Ear Conditions

Many health conditions can affect how the ear functions. These include:

• Tinnitus: Persistent ringing, roaring, hissing, or buzzing in one or both ears. Tinnitus may be caused by many different factors including age-related hearing loss, overexposure to loud noises, physical injury, Meniere’s disease, brain tumors, and certain medicines.
• Meniere’s disease: Also known as idiopathic endolymphatic hydrops. This inner-ear disorder can cause vertigo, tinnitus, fluctuations in hearing ability, pain, headaches, nausea, and other symptoms.
• Otitis Media: An infection of the middle ear that can cause ear pain and pressure, as well as a fever
• Otitis Externa (Swimmer's ear): A bacterial or fungal infection in the ear canal that results in ear pain and pressure as well as a fever
  
• Cerumen: Excessive wax build-up that blocks passages between the outer and middle ear and affects hearing
• Auricular hematoma: Also called cauliflower ear. This is a collection of blood in the outer ear that is usually the result of trauma or injury.
• Ruptured tympanic membrane: A hole in the eardrum caused by infection, a loud noise, trauma, or a foreign object
• Eustachian tube dysfunction: When the lining of the eustachian tube is swollen, preventing it from working properly to equalize pressure
• Perichondritis: An infection of the tissue that surrounds the outer ear's cartilage

Symptoms of Ear Problems

See a healthcare provider if you or your child experience any of the following symptoms:

• Ear pain (with or without a fever)
• Muffled hearing
• A feeling of pressure or fullness in your ears
• Itchiness in the ear(s)
• Fluid coming out of ears

Diagnostic Tools

A healthcare provider may use one or more of these tools and tests to assess the ear and its functioning:

• Otoscopy: This examination of the ear canal and eardrum uses a tool called an otoscope
• Pure-tone test: This hearing evaluation involves patients wearing headphones and raising a hand if and when they hear certain tones.
• Speech test: Hearing loss is sometimes evaluated by having people repeat certain words or phrases played at specific volumes
• Tympanometry: This test checks the motion and health of the tympanic membrane and middle ear by pushing air into the ear and measuring the pressure with a probe.
• Acoustic reflex measure: This test stimulates some of the musculature in the middle ear to see if there's a weak or absent response, which indicates hearing loss.
• Static acoustic impedance: This test can find an eardrum rupture, fluid build-up, and blockage by measuring the air in the ear canal.
• Auditory brainstem response (ABR) test: A test of inner ear function (as well as neural pathways), this examination involves using electrodes on the skin to measure brain activity in response to stimuli.
• Otoacoustic emissions (OAE): This hearing test is performed by inserting a small, sound-emitting probe into the ear and measuring the response.

How to Care For Your Ears

Here are some simple steps you can take to keep your ears healthy:

• Avoid or limit exposure to excessively loud sounds.
• Turn the volume down when listening through headphones.
• Use hearing protection.
• Use a bathing cap, earplugs, or custom-fitted swim molds when swimming.
• Dry ears thoroughly after swimming or showering.
• Do not use any foreign object (including cotton swabs) to clean your ear canal.

Summary

The ears are a pair of organs on each side of the head that help with balance and hearing. Each ear consists of an outer, middle, and inner portion. All three parts of the ear are involved in hearing.

Several health conditions can affect the ears, including Meniere's disease, tinnitus, and infection. A healthcare provider can diagnose some ear problems by examining the ear with an otoscope.