The tragus is a small pointed eminence of the

external ear The outer ear, external ear, or auris externa is the external part of the ear, which consists of the auricle (also pinna) and the ear canal. It gathers sound energy and focuses it on the eardrum (tympanic membrane). Structure Auricle The ...

, situated in front of the concha, and projecting backward over the

meatus In anatomy, a meatus (, ),'' OED'' 2nd edition, 1989, as . plural "meatus" or "meatuses",

. It also is the name of hair growing at the entrance of the ear. Its name comes the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

(), meaning 'goat', and is descriptive of its general covering on its under surface with a tuft of hair, resembling a

goat The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the a ...

beard A beard is the hair that grows on the jaw, chin, upper lip, lower lip, cheeks, and neck of humans and some non-human animals. In humans, usually pubescent or adult males are able to grow beards. Throughout the course of history, societal at ...

. The nearby

antitragus The antitragus is a feature of mammalian ear anatomy. In humans, it is a small tubercle on the visible part of the ear, the pinna. The antitragus is located just above the earlobe and points anteriorly. It is separated from the tragus by the ...

projects forwards and upwards. Because the tragus faces rearwards, it aids in collecting sounds from behind. These sounds are delayed more than sounds arriving from the front, assisting the brain to sense front vs. rear sound sources. In a positive

fistula A fistula (plural: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") in anatomy is an abnormal connection between two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other hollow or ...

test (for the presence of a fistula from

cholesteatoma Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of th ...

to the

labyrinth In Greek mythology, the Labyrinth (, ) was an elaborate, confusing structure designed and built by the legendary artificer Daedalus for King Minos of Crete at Knossos. Its function was to hold the Minotaur, the monster eventually killed by t ...

), pressure on the tragus causes

vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...

or eye deviation by inducing movement of

perilymph Perilymph is an extracellular fluid located within the inner ear. It is found within the scala tympani and scala vestibuli of the cochlea. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid. The major ...

Other animals

The tragus is a key feature in many bat species. As a piece of skin in front of the ear canal, it plays an important role in directing sounds into the ear for prey location and navigation via echolocation.Chiu, C., & Moss, C. F. (2007). The role of the external ear in vertical sound localization in the free flying bat, Eptesicus fuscus. The Journal of the Acoustical Society of America, 121(4), 2227-2235. Because the tragus tends to be prominent in bats, it is an important feature in identifying bat species. The tragus allows echolocating bat species to vertically discriminate the objects around them, which is key to identifying where prey items and obstacles are in three-dimensional space. In studies where an individual's tragi are temporarily glued out of their normal positions, the bat's navigational acuity is one-fourth as effective as individuals with unmodified tragi. Based on this study, the authors concluded that the tragus's function is to create acoustic cues to determine the direction of a target in the vertical plane. Not all echolocating bats possess tragi, however.

Horseshoe bat Horseshoe bats are bats in the family Rhinolophidae. In addition to the single living genus, ''Rhinolophus'', which has about 106 species, the extinct genus '' Palaeonycteris'' has been recognized. Horseshoe bats are closely related to the Old ...

s are one such family; the way in which the outer bottom edge of the ear folds in on itself is thought to function in a similar way to the tragus in other families. File:Brown long-eared bat (Plecotus auritus) - geograph.org.uk - 1415542.jpg, The long tragus of the

brown long-eared bat The brown long-eared bat or common long-eared bat (''Plecotus auritus'') is a small Eurasian insectivorous bat. It has distinctive ears, long and with a distinctive fold. It is extremely similar to the much rarer grey long-eared bat which was o ...

File:Red bat (6022957658).jpg, The curved tragus of the

eastern red bat The eastern red bat (''Lasiurus borealis'') is a species of microbat in the family Vespertilionidae. Eastern red bats are widespread across eastern North America, with additional records in Bermuda. Taxonomy and etymology It was described in 1 ...

File:Side view of spotted bat -Euderma maculatum- by Paul Cryan.jpg, The blunt tragus of the spotted bat

Additional images

File:Gray908.png, Horizontal section through left ear; upper half of section. File:Slide2COR.JPG, External ear. Right auricle.Lateral view. File:Slide4COR.JPG, External ear. Right auricle.Lateral view.

References

External links

* * () (#7) {{Authority control Ear

Other animals

Additional images

See also

References

External links