The visible part of the ear attached to the head, also known as the pinna or auricle, was considered by the public and the medical community to be a vestigial organ with no real function, especially when compared to the ears of animals. However, as the science of the auditory (hearing) system progressed the role of the pinna in the functioning of the ear became more understood. It is now known that when sound waves emanate from a sound source the pinna collects the sound energy and directs the sound, particularly the high-frequency portion, to a central focal point- the entrance to the auditory canal. The configuration of the pinna also enables the individual to determine whether sounds are originating from in front or from behind.
The structure of the pinna is cartilage covered with skin. The anatomy of the pinna includes such features as the helix, triangular fossa, scaphoid fossa, anti-helix, tragus, anti-tragus, concha, intertragal notch, and the lobule. In contemporary society, all of these parts of the outer ear are subject to "decorative piercings."
As it is the visible part of the ear, the abnormalities of the pinna can usually be seen. The following is a partial list of pinna abnormalities:
* Macrotia (also known as big ears, or hypertrophy of the ears)
* Microtia (small or partially developed ears)
* Prominent ear (also known as bat ear or wingnut ear) -- an ear that protrudes
* Cup deformity -- helical rim is compressed
* Lop ear -- the top of the helical rim folded over
* Preauricular sinus (small holes visible from birth at the front of the ears where the pinna joins the head)
* Rim kinks -- a kink of the helical rim
* Selhurst's handle (also known as cup handle) -- an ear that can be 50% larger than normal.
* Stahl's bar (also known as Spock ear) -- a pointed top of the ear