Apple #536: Tragus

Oops, almost forgot the Daily Apple for today. So I'm going to pose what I think will be a relatively easy question to answer.

(Every time I think that, though, I wind up getting curious about the topic at hand and get all into it, and three hours later, I'm searching for just the right image to demonstrate a particular nuance. We'll see how this one turns out.)

My question for today: what's that funny bump at the outer opening of your ear called? And what's it for?

• The funny bump is called the tragus.

All the various hollows and curves of the ear have names, as it turns out. But the particular place I'm interested in is the tragus, the pointy bump over the ear canal.
(Diagram posted by boogieman4215 at sherdog.net)

• In general, all those curves and hollows and whorls are about collecting and channeling sound effectively and safely into the ear canal. The tragus is one part of that noise-channeling system.

• Specifically, the tragus aids in hearing sounds that are coming from behind you. Every other part of the ear is facing forward, collecting sound waves that come at you from the front. The tragus, however, is backward facing. Small though it is, it does manage to collect some of the sound waves coming from behind and bounces them into the ear canal.

• In addition, some of the sounds getting funneled into the ear canal from other parts of the external ear bounce off the tragus before going into the canal.

• The tragus and its counterpart, the antitragus, together help to keep water out of the ear, although that function has been observed more extensively in animals other than humans.

• The tragus has other functions in other animals. In cats, the tragus includes muscles that help cats move their ears to catch sounds.
  

• In bats, the tragus is believed to aid in echo-location, that is, helping bats use sound to orient themselves relative to the horizon.

Ear shapes of lots of different species of bats. The diagrams on the right show close-ups of ears, and the long pointy thing in the middle of each one is the tragus. You can see how the traguses are shaped differently in various species. I think people have differently shaped traguses, too, though maybe not with this degree of variety. And obviously bats' traguses are far larger than humans'.
(Diagram from Malaysian Bat Education Adventure)

• I can wriggle my ears, and it feels like there might be muscles in or near the tragus that are involved in that. So maybe those of us who are ear-wrigglers are not that far removed from cats.

• And here's an even bigger maybe: maybe, if I worked at it, maybe I could use my tragus for echo-location the way bats can. Though, since my tragus is much smaller than a bat's, I doubt it.

• OK, back to reality, and human beings. The tragus is useful in other ways besides just aiding in hearing.

• To find out if you've got an ear infection, pressing the tragus will tell you pretty quickly. If it feels inflamed, if it hurts, or if goo emerges, you've got an infection in there somewhere.

The tragus press: a quick way to evaluate the ear for infection.
(Photo from Operational Medicine 2001)

• If you have an ear infection and you need to use ear drops, some doctors suggest massaging the tragus to help ear medicine travel more deeply into the ear canal.

• Ear buds -- those tiny little headphones -- are held in place courtesy of the tragus.

• Finally, some people like to pierce their tragus. It's mostly cartilage and doesn't have many nerve endings, so most people who've had this piercing say it doesn't hurt much at all.

Tragus pierced with a hoop
(Image from tattooculture)

• However, some people say that it hurt when they had it done. It can also hurt or be very sensitive after it's pierced, for a few days or as long as a few weeks.
  

• Because of this initial sensitivity, you'll want to avoid using any earphones for a while. Sleeping on that side will be painful, and pulling shirts or clothing down over the ear could catch on the earring and that will also be painful. In general, you'll want to avoid bumping your ear against much of anything at all.
  

• This particular spot is also prone to infection, so it's important that you keep the piercing clean, especially during the first 8 weeks after piercing. Some people say theirs took as long as a year to heal.

• Clean the area, front and back, with saline solution three times a day to keep infections at bay.

• Hydrogen peroxide and alcohol are both specifically not recommended. Salt water is gentler and will in the end help the piercing heal faster.
  

• Be careful not to handle the tragus too much with your bare fingers because that can lead to infection.

• The first few days after piercing, the tragus might be swollen, but that should die down.

Tragus pierced with a barbell, and swollen.
(Photo posted by White Lies at altnation.com)

• If swelling appears later on, or if it never goes away, if it feels hot to the touch, or if there's pus or other fluid coming out of it, you may have an infection.
  

• Most of the body piercing sites say not to panic and not to remove the piercing. Taking out the piercing only exposes the unhealed tissue to more bacteria, which could make the infection worse. They recommend continuing to clean the area with warm salt water but otherwise leaving it alone to heal.

• They also recommend going to a doctor, if the swelling persists. If it were me, I wouldn't wait to see a doctor. I'd get it checked out right away.
  

• The upshot: if you do get your tragus pierced, take care of it. That little bump really does serve a purpose!

Sources
WiseGeek, What Is the Tragus?
Nathan E. Nachlas, "Otoplasty," Facial Plastic and Reconstructive Surgery, p 423
Just Answer, Cat Veterinary, The small cat's ear
Chen Chiu and Cynthia F. Moss, The Role of the External Ear Tragus in Obstacle Avoidance by Echolocation in the FM-Bat, February 2005
Tribalectic, Experiences of Tragus Piercings on Women
Joan White, Hub Pages, Tragus Piercing
Piercing Guides, Tragus and Anti-Tragus Piercings