Anatomy & Organs

Auricle – structure, function & diseases

Auricle

The auricle is the outer part of the ear that is individually shaped for each person. It has both functionally important and non-functional parts (e.g. earlobes). Diseases of the auricles are often the result of mechanical influences, injuries, piercings, insect bites or operations.

What is an auricle?

The auricle marks the externally visible part of the ear . Its Latin name is Auricula auris . It consists largely of cartilage tissue covered with skin. Their job is to pick up sound, which is concentrated towards the inner ear by the funnel effect.

The elastic cartilage shapes the shape of the auricle, which is fused to the skull and covered with a layer of tissue ( periosteum ). The sensations in the auricle are controlled by four different nerves . However, the functionless earlobe is largely insensitive to pain and is therefore often used to take blood for laboratory tests.

Like the ear muscles and Darwin’s ear cusp, the earlobe no longer has any function. The entire morphology of the auricle is genetically determined and therefore has specific characteristics for each person.

Anatomy & Structure

Every human being has uniquely formed auricles made of cartilage tissue covered with skin. Its main feature is the striking relief with folds and depressions. The outer edge of the auricle is called the helix. The helix runs parallel to the crescent-shaped antihelix. Both are separated by the scapha, a crescent-shaped recess. This relief acts as an important filter system for the incident sound.

The relief edges cause the refraction and, depending on its frequency, also the different damping of the sound. The shape and size of the auricles also determines the overall visual impression of the face , which has no physiological, but in many cases psychological significance. While most animals can move their ears in the direction of sound sources, human mobility is greatly reduced.

The ear musculature responsible for this has lost all meaning in humans and is only a rudiment. However, each person has individually designed earlobes. Overall, the human ear is just as unique as a fingerprint and can be used in forensic science for identification purposes.

Function & Tasks

As already mentioned, the relief system of the ear cups takes care of filtering the incoming sound. Through the refraction and the damping of the sound waves, which depends on the frequency, the brain obtains information about its spatial origin. The elevations and depressions within the auricles give the sound its own timbre depending on its origin.

Based on this timbre, the brain can determine whether the sound is coming from the front, from behind, from below or from above. However, determining whether the sound source is on the right or left is mediated by other mechanisms. To do this, the brain analyzes the time difference of the sound, among other things. Another possibility is to assess the loudness, whereby the sound source closest to the ear is usually the loudest. In the animal kingdom there is often the possibility of actively aligning the ears to the corresponding sound source.

This is conveyed via the ear muscles. This ability no longer exists in humans. Some people can wiggle their ears in a rudimentary way, but this no longer has any physiological significance. Because of this, the pinnae are sometimes mistaken for superfluous organs. That’s by no means the case, though, as directional hearing wouldn’t be possible without the function of the front-facing earcups.

Diseases & Ailments

Diseases of the auricles are often triggered by external stimuli. Injuries, piercings, insect bites, frostbite or even operations sometimes lead to an othematoma . The othematoma is a bloody-serous effusion between the cartilage of the auricle and the overlying connective tissue ( perichondrium ). Sometimes lying on a folded ear cup is enough.

Violence often plays a role as well. The othematoma manifests itself as a reddish swelling on the front of the auricula auris. Pain usually does not occur. However, the connective tissue can reorganize as a result of the effusion, which sometimes leads to a significant change in the auricle. If the othematoma is not treated, it can lead to auricular perichondritis. Inflammatory reactions occur within the auricle due to infection with Pseudomonas aeruginosa or more rarely with Staphylococcus aureus .

These infections are very serious because they can completely destroy the cartilage tissue. The disease is associated with severe pain and abscess formation . Although the earlobe may be reddened, it is not subject to the painful inflammatory processes. Auricular perichondritis is treated with alcohol compresses and antibiotics. The auricles often also suffer from the so-called chondrodermatitis nodularis helicis.

This disease is characterized by nodulation on the helix or the antihelix. These nodules are very painful and quickly enlarge to 5-8mm in diameter. After that they remain stable. The causes of this disease are unknown. In addition to these acquired diseases, there are also congenital malformations of the auricles. These malformations manifest themselves as ear cysts, ear pendants, ear fistulas or auricle dysplasia.

Ear cysts are cavities in the area of ​​the ear. Ear appendages are flap-like skin protuberances on the ear. Auricular dysplasia describes structural changes in the auricles which, depending on their severity, can have purely cosmetic or functional effects.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.