Pinna
From Free net encyclopedia
The pinna (Latin for feather) is the visible part of the ear that resides outside of the head. We often use the pinna, which is also called the auricle, for hanging earrings and resting eyeglasses, pencils, and cigarettes; but the evolutionary purpose of the pinna is to collect sound. It does so by acting as a funnel, amplifying the sound and directing it to the ear canal. While reflecting from the pinna, sound also goes through a filtering process which adds directional information to the sound (see sound localization, head-related transfer function, pinna notch). Notably, the filtering of the human pinna also selects for sounds in the frequency range of human speech.
Amplification of sound by the pinna, tymphanic membrane and middle ear structures create a sound pressure level of 20 relative to sound entering the pinna. This amplification is an important basis for inner ear trauma that can result from elevated sound levels.
Anatomy
Please refer to the diagram for an idea of the shape and location of these components:
- Anthelix (antihelix) forms a 'Y' shape where the upper parts are:
- Superior crux (to the left of the fossa triangularis in the diagram)
- Inferior crux (to the right of the fossa triangularis in the diagram)
- Antitragus is below the tragus
- Auricular sulcus is the depression behind the ear next to the head
- Concha is the hollow next to the ear canal
- Conchal angle is the angle that the back of the concha makes with the side of the head
- Crus of the helix is just above the tragus
- Cymba conchae is the narrowest end of the concha
- External auditory meatus is the opening to the ear canal
- Fossa triangularis
- Helix is the folded over outside edge of the ear
- Incisura anterior (auris) is between the tragus and the antitragus
- Lobe (lobule)
- Scapha
- Tragus
Abnormalities
There are various visible ear abnormalities:
- Bat ear (also known as wingnut ear) — an ear that sticks out or protrudes
- Cryptotia (hidden ear) — upper auricular sulcus not visible
- Cup deformity — helical rim is compressed
- Darwinian tubercle (auricular tubercle) — a projection from the helical rim
- Lop ear — the top of the helical rim folded over
- Macrotia (also known as big ears, or hypertrophy of the ears)
- Rim kinks — a kink of the helical rim
- Stahl’s bar (also known as Spock ear) — third crus (in between the superior crux and inferior crux) making the top of the ear pointed
See also
- Earrings for pierced earsTemplate:Anatomy-stub