The Anatomy of Outer Ear

There is much more to the ear than what you see from the outside. There are three parts to the ear—the outer ear, the middle ear, and the inner ear. These sections work together to collect sound from the world around you and send it to the brain where speech and auditory centers translate the information. The outer ear is the part of the ear that you can see and where sound waves enter the ear before traveling to the inner ear and brain. While the outer ear may not be as complex as its counterparts, it serves a vital function in your sense of hearing.

outer ear

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Anatomy

Structure

The outer ear—sometimes called the auricle or pinna—is mostly made of skin and cartilage. It is made up of several components:

  • Helix: The outermost curvature of the ear, extending from where the ear joins the head at the top to where it meets the lobule. The helix begins the funneling of sound waves into the ear
  • Fossa, superior crus, inferior crus, and antihelix: These sections make up the middle ridges and depressions of the outer ear. The superior crus is the first ridge that emerges moving in from the helix. The inferior crus is an extension of the superior crus, branching off toward the head. The antihelix is the lowest extension of this ridge. Fossas are the depressions between these ridges. These shapes work together to funnel sound waves collected at the helix toward the middle ear
  • Concha: The concha is the depressed area at the opening of the middle ear, or the external acoustic meatus. The concha is the final point that directs sound into the ear
  • Tragus and antitragus: These two cartilage prominences border the concha at the top and bottom
  • Lobule: The lobule is the bottom-most part of the ear, often called the earlobe. It is the only part of the outer ear that is not supported by cartilage. Since this section is softer and has a larger blood supply than the rest of the ear, it is thought to help keep the rest of the ear warm
  • External acoustic meatus: This inch-long section is sometimes called the ear canal, and serves as the bridge between the outer and middle ear. It’s a hollow tube that curves slightly downward as it moves into the ear toward the tympanic membrane, or eardrum. The eardrum is the ending point of the outer ear and the beginning of the middle ear
outer ear diagram

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Location

The outer ear lies directly next to the middle ear. Though mostly made of cartilage and skin, the outer ear arises from the temporal bone. Located on either side of the head, the ears are found directly over the temporal lobe of the brain. This is the part of the brain that controls speech, hearing, memory, and some emotion.

Anatomical Variations

While ears may seem simple and functional, they are also very unique. The exact size and shape of the outer ridges of the ear and the lobule are different for everyone. Genetics play a role in the size and shape of your ear—including whether the lobule hangs freely or is completely attached to the side of your head.

Function

The outer ear is divided into several sections, but they all work together toward one purpose: The helix, antihelix, superior and inferior crus, the tragus and antitragus, the concha, and the external acoustic meatus all work together to funnel and direct sound waves from the world around you to the inner parts of your ears. Sound waves are carried from the outer ear and ear canal to the tympanic membrane, where vibrations are sent through the middle and inner ears and become electrical impulses (sound signals). These signals then give your brain information about both sound and the direction and balance of your body.

Many nerves run through the ear, and they are responsible for carrying signals about sound and balance to the brain. The skin of the ear canal is thin and very sensitive, and branches of the facial and vagus nerves run under portions of the ear canal and other parts of the outer ear. Other cranial nerves run through the ear as well, but have little to no known function.

Associated Conditions

A number of conditions can affect the outer ear. Depending on the cause, these problems can be treated by a primary care physician or an otolaryngologist.

The outer ear is prone to these medical issues:

  • Auricular hematoma: This is a condition where blood collects between the cartilage of the ear and the overlying layer of skin. It is typically caused by trauma, and is a common sports injury. The blood may reabsorb on its own, but more severe causes could require drainage by a healthcare professional. If left undrained, severe cases could lead to necrosis of the cartilage—a condition commonly known as cauliflower ear
  • Cerumen impaction: Various skin cells and glands in the ear canal secrete waxy substances that protect the canal, but can also cause a buildup of earwax, or cerumen. Normally, cerumen can be removed as it builds, but in some cases it builds to the point that it obstructs the ear canal or eardrum. These cases may be associated with itchiness, pain, tinnitus, or even hearing loss. Your doctor will likely give you a medication to soften the wax. Over-the-counter ear drops won't cause harm, but it’s not certain whether they can help either. Irrigation and manual removal by a healthcare provider may be necessary in more severe cases
  • Exostoses: These are bony growths in the ear canal, sometimes referred to as surfer’s ear. They appear as small, smooth bony growths, usually in both ears. Exostoses may appear after exposure of the ear to cold water, but they can also happen without water exposure. Most of the time, exostoses don’t require treatment. Surgical removal may be required if hearing loss or obstruction occurs, however. Otherwise, your doctor may choose to observe the exostoses and clean the area of any skin cells or debris that becomes trapped between the growths
  • Obstructions: Obstructions occur when there is a foreign body lodged in the ear canal. A common problem with small children, items lodged in the ear can cause irritation, inflammation, and the formation of ulcers. Extraction should be done by a doctor using the appropriate pain management and equipment
  • Otitis externa: Often called swimmer's ear, this is a condition that happens when the outer ear canal becomes infected, irritated, or inflamed. Usually caused by bacteria in contaminated water, this condition can cause pain and even swelling or eardrum injury. It can be treated with antibiotics, steroids, and pain medications

Birth Defects Involving the Outer Ear

A number of congenital conditions—or condition present at birth—can affect the outer ear:

  • Microtia: This problem arises when the outer folds of the outer ear develop improperly or not at all. Most of the time, this condition affects only one ear
  • Atresia: Congenital aural atresia is fairly common and occurs when the ear canal doesn’t develop properly. This problem, present at birth, can appear in one or both ears. It can sometimes occur alongside microtia

With both of these congenital defects, hearing tests should be done by a pediatric audiologist soon after birth to determine if the problem is cosmetic or if it interferes with hearing. Surgery is a possibility for children with impaired hearing from either of these issues, but isn’t recommended before age 5.

Tests

The location of the outer ear and its structures make examining this part of the body fairly straightforward. In most cases, your doctor will be able to visually inspect the outer ear. In some cases, they may use an otoscope for a more detailed view. An otoscope is a magnifying device with a light that is inserted into the ear canal for a view of the canal and eardrum. If your doctor needs to see the underlying or deeper structures, a computed tomography (CT) scan may be required.

Hearing Tests

If a hearing test is recommended to evaluate your outer ear problem, your doctor may perform some basic testing and then you may be referred to an audiologist.

Some types of hearing tests include:

  • Pure-tone test: This test is also called an audiometry test. You will hear a variety of sounds played through headphones. This test helps find the quietest sounds you can hear at different pitches
  • Tuning fork tests: A two-pronged metal fork is placed behind your ear or on the top of the head. The provider performing the test will strike the fork to make a tone. This test can show if there is hearing loss in one or both ears. It can also show which type of hearing loss you have

Talk to your doctor if you have ongoing ear pain or are experiencing hearing loss. You should always check with a healthcare professional before putting anything in your ear. Some home remedies, like candling, are no longer recommended.

When To Seek Help

Hearing problems can become serious or dangerous when you can't hear things like:

  • Safety information
  • Oncoming traffic
  • Emergency signals

Balance problems are often more emergent since issues with your vestibular system can cause falls and lead to injury.

If you are experiencing any of these symptoms, you should see a doctor.

 

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Article Sources
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  1. University of Texas Health, McGovern Medical School. Ear Anatomy-Outer Ear.

  2. Teach Me Anatomy. The External Ear.

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  10. American Academy of Pediatrics. Updated guideline advises on treating children with impacted cerumen. Updated 2017.