Pinna
Encyclopedia
In animal anatomy
, the pinna (Latin
for feather
) is the visible part of the ear
that resides outside of the head (this may also be referred to as the auricle or auricula).
In botany
, it can refer to the segments of the leg a pinnate
frond blade and is discussed in that section.
, head-related transfer function
, pinna notch). The filtering effect of the human pinna preferentially selects sounds in the frequency range of human speech.
In various species, the pinna can also signal mood and radiate heat.
trauma
resulting
from elevated sound levels
.
effect.
of Hiss), which are derived from the first and second branchial arches.
These hillocks develop into the folds of the pinna and gradually shift upwards and backwards to their final position on the head. En-route accessory auricles (also known as preauricular tags) may be left behind.
The first three hillocks are derived from the 1st branchial arch and form the tragus, crus of the helix, and helix, respectively. Cutaneous sensation to these areas is via the trigeminal nerve, the attendant nerve of the 1st branchial arch.
The final three hillocks are derived from the 2nd branchial arch and form the antihelix, antitragus, and lobule, respectively. These portions of the ear are supplied by the cervical plexus and a small portion by the facial nerve. This explains why vesicles are classically seen on the pinna in herpes infections of the facial nerve (Ramsay Hunt syndrome type II).
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
, the pinna (Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for feather
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
) is the visible part of the ear
Ear
The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....
that resides outside of the head (this may also be referred to as the auricle or auricula).
In botany
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
, it can refer to the segments of the leg a pinnate
Pinnate
Pinnate is a term used to describe feather-like or multi-divided features arising from both sides of a common axis in plant or animal structures, and comes from the Latin word pinna meaning "feather", "wing", or "fin". A similar term is pectinate, which refers to a comb-like arrangement of parts...
frond blade and is discussed in that section.
Function
The function of the pinna is to collect sound, and perform spectral transformations to incoming sounds which enable the process of vertical localization to take place. It collects sound by acting as a funnel, amplifying the sound and directing it to the auditory canal. While reflecting from the pinna, sound also goes through a filtering process, as well as frequency dependent amplitude modulation which adds directional information to the sound (see sound localizationSound localization
Sound localization refers to a listener's ability to identify the location or origin of a detected sound in direction and distance. It may also refer to the methods in acoustical engineering to simulate the placement of an auditory cue in a virtual 3D space .The sound localization mechanisms of the...
, head-related transfer function
Head-related transfer function
A head-related transfer function is a response that characterizes how an ear receives a sound from a point in space; a pair of HRTFs for two ears can be used to synthesize a binaural sound that seems to come from a particular point in space. Some consumer home entertainment products designed to...
, pinna notch). The filtering effect of the human pinna preferentially selects sounds in the frequency range of human speech.
In various species, the pinna can also signal mood and radiate heat.
Amplification
Amplification of sound by the pinna, tympanic membrane and middle ear causes an increase in level of about 10 to 15 dB in a frequency range of 1.5 kHz to 7 kHz. This amplification is an important factor in inner earInner ear
The inner ear is the innermost part of the vertebrate ear. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:...
trauma
Physical trauma
Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
resulting
from elevated sound levels
Noise health effects
Noise health effects are the health consequences of elevated sound levels. Elevated workplace or other noise can cause hearing impairment, hypertension, ischemic heart disease, annoyance and sleep disturbance. Changes in the immune system and birth defects have been attributed to noise exposure...
.
Pinna notch
The pinna works differently for low and high frequency sounds. For low frequencies, it behaves similarly to a reflector dish, directing sounds toward the ear canal. For high frequencies, however, its value is thought to be more sophisticated. While some of the sounds that enter the ear travel directly to the canal, others reflect off the contours of the pinna first: these enter the ear canal at a very slight delay. Such a delay translates into phase cancellation, where the frequency component whose wave period is twice the delay period is virtually eliminated. Neighboring frequencies are dropped significantly. This is known as the pinna notch, where the pinna creates a notch filteringBand-stop filter
In signal processing, a band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels. It is the opposite of a band-pass filter...
effect.
Anatomy
The diagram shows the shape and location of most 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
- Aperture is the entrance to the ear canal
- Auricular sulcusSulcus (anatomy)A sulcus is a depression or fissure in the surface of an organ, especially the brain.-Elsewhere:* anterior interventricular sulcus* calcaneal sulcus* coronal sulcus* gingival sulcus* gluteal sulcus* interlabial sulci...
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 ear canalEar canalThe ear canal , is a tube running from the outer ear to the middle ear. The human ear canal extends from the pinna to the eardrum and is about 35 mm in length and 5 to 10 mm in diameter....
- Fossa triangularis is the depression in the fork of the antihelix
- Helix is the folded over outside edge of the ear
- Incisura anterior aurisIncisura anterior aurisThe incisura anterior auris, or intertragic incisure, is the space between the tragus and antitragus of the pinna — a portion of the external ear. Other names include anterior auricular groove, auricular notch, sulcus auriculae anterior.The incisura anterior auris is the point specified in the U.S...
, or intertragic incisure, or intertragal notch, is the space between the tragus and antitragus - LobeEarlobeThe human earlobe is composed of tough areolar and adipose connective tissues, lacking the firmness and elasticity of the rest of the pinna. Since the earlobe does not contain cartilage it has a large blood supply and may help to warm the ears and maintain balance. However earlobes are not...
(lobule) - attached or free according to a classic single-gene dominance relationshipDominance relationshipDominance in genetics is a relationship between two variant forms of a single gene, in which one allele masks the effect of the other in influencing some trait. In the simplest case, if a gene exists in two allelic forms , three combinations of alleles are possible: AA, AB, and BB... - Scapha
- Tragus
Embryology
The developing pinna is first noticeable around the sixth week of gestation in the human fetus, developing from six rounded protuberances (the six hillocksAxon hillock
The axon hillock is a specialized part of the cell body of a neuron that connects to the axon. As a result, the axon hillock is the last site in the soma where membrane potentials propagated from synaptic inputs are summated before being transmitted to the axon. For many years it was believed...
of Hiss), which are derived from the first and second branchial arches.
These hillocks develop into the folds of the pinna and gradually shift upwards and backwards to their final position on the head. En-route accessory auricles (also known as preauricular tags) may be left behind.
The first three hillocks are derived from the 1st branchial arch and form the tragus, crus of the helix, and helix, respectively. Cutaneous sensation to these areas is via the trigeminal nerve, the attendant nerve of the 1st branchial arch.
The final three hillocks are derived from the 2nd branchial arch and form the antihelix, antitragus, and lobule, respectively. These portions of the ear are supplied by the cervical plexus and a small portion by the facial nerve. This explains why vesicles are classically seen on the pinna in herpes infections of the facial nerve (Ramsay Hunt syndrome type II).
Abnormalities
There are various visible ear abnormalities:- Prominent ear (also known as bat ear or wingnut ear) — an ear that 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
- MacrotiaMacrotiaMacrotia refers to an ear which is larger than would be expected.In some cases, surgery is performed to reduce the size....
(also known as big ears, or hypertrophy of the ears) - MicrotiaMicrotiaMicrotia, also called microtia-anotia, is a congenital deformity where the pinna is very small and underdeveloped or absent . It can be unilateral or bilateral . It occurs in 1 out of about 8,000–10,000 births. In unilateral microtia, the right ear is most commonly affected...
(small or partially developed ears) - Preauricular sinus (small holes usually visible from birth at the front of the ears where the pinna joins the head)
- Accessory Auricles (small pieces of skin at the front of the ears where the pinna joins the head, vestigial remnants of the developing ears migration to its final position)
- 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) — third crus (in between the superior crux and inferior crux) making the top of the ear pointed
- Zaheer's ear — having a deformed anti-tragus, which appears as a bump, as opposed to a protrusion, which would normally allow the snug insertion of earbud headphones