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A head is the part of an
organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fu ...
which usually includes the ears,
brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...
, forehead, cheeks,
chin The chin is the forward pointed part of the anterior mandible ( mental region) below the lower lip. A fully developed human skull has a chin of between 0.7 cm and 1.1 cm. Evolution The presence of a well-developed chin is considered to be one ...
, eyes,
nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passe ...
, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may not have a head, but many bilaterally symmetric forms do, regardless of size. Heads develop in animals by an
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
ary trend known as cephalization. In bilaterally symmetrical animals,
nervous tissue Nervous tissue, also called neural tissue, is the main tissue component of the nervous system. The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the bra ...
concentrate at the anterior region, forming structures responsible for information processing. Through biological evolution, sense organs and feeding structures also concentrate into the anterior region; these collectively form the head.


Human head

The human head is an anatomical unit that consists of the
skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
, hyoid bone and
cervical vertebrae In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...
. The term "skull" collectively denotes the
mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...
(lower jaw bone) and the cranium (upper portion of the skull that houses the brain). Sculptures of human heads are generally based on a skeletal structure that consists of a cranium, jawbone, and cheekbone. Though the number of muscles making up the face is generally consistent between sculptures, the shape of the muscles varies widely based on the function, development, and expressions reflected on the faces of the subjects. Proponents of identism believe that the mind is identical to the brain. Philosopher John Searle asserts his identist beliefs, stating "the
brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...
is the only thing in the human head". Similarly, Dr. Henry Bennet-Clark has stated that the head encloses billions of "miniagents and microagents (with no single Boss)". File:View of a Skull III.jpg, Mid-sagittal section of a
human skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
, by
Leonardo da Vinci Leonardo di ser Piero da Vinci (15 April 14522 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially rested on ...
, File:Bartholin head transect.jpg, Transection of a human head, by Thomas Bartholin, 1673


Other animals

The evolution of a head is associated with the cephalization that occurred in Bilateria some 555 million years ago.


Arthropods

In some
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...
s, especially
trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the ...
s (pictured at right), the
cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont Company. Baldino s ...
, or cephalic region, is the region of the head which is a collective of "fused segments".


Insects

A typical insect head is composed of eyes, antennae, and components of mouth. As these components differ substantially from insect to insect, they form important identification links. Eyes in the head found, in several types of insects, are in the form of a pair of compound eyes with multiple faces. In many other types of insects, the compound eyes are seen in a "single facet or group of single facets". In some cases, the eyes may be seen as marks on the dorsal or located near or toward the head, two or three ocelli (single faceted organs). Antennae on the insect's head is found in the form of segmented attachments, in pairs, that are usually located between the eyes. These are in varying shapes and sizes, in the form of filaments or in different enlarged or clubbed form. Insects have mouth parts in various shapes depending on their feeding habits. Labrum is the "upper lip" which is in the front area of the head and is the most exterior part. A pair of mandibles is found on the backside of the labrum flanking the side of the mouth, succeeded by a pair of maxillae each of which is known as maxilliary palp. At the back side of the mouth is the
labium Labium is the Latin word for lip. In English, it may refer to: * Labia, a part of the female external genitalia * Labium (botany), a modified petal in certain monocot flowers, which attracts insects for pollination * Labium (arthropod mouthpart), ...
or lower lip. There is also an extra mouth part in some insects which is termed as
hypopharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struct ...
which is usually located between the maxillac.


Vertebrates and the "new head hypothesis"

Though
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
chordate A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These fi ...
s – such as the
tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one t ...
larvae or the lancelets – have heads, there has been a question of how the vertebrate head, characterized by a bony skull clearly separated from the main body, might have evolved from the head structures of these animals. According to Hyman (1979), the evolution of the head in the vertebrates has occurred by the fusion of a fixed number of anterior segments, in the same manner as in other "heteronomously segmented animals". In some cases, segments or a portion of the segments disappear. The head segments also lose most of their systems, except for the nervous system. With the progressive development of cephalization, "the head incorporates more and more of the adjacent segments into its structure, so that in general it may be said that the higher the degree of cephalization the greater is the number of segments composing the head". In the 1980s, the "new head hypothesis" was proposed, suggesting that the vertebrate head is an evolutionary novelty resulting from the emergence of neural crest and cranial placodes. In 2014, a transient
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...
tissue of the lancelet was found to be virtually indistinguishable from the neural crest-derived cartilage which forms the vertebrate skull, suggesting that persistence of this tissue and expansion into the entire headspace could be a viable evolutionary route to formation of the vertebrate head.


In society and culture


Heraldry

The heads of humans and other animals are commonly recurring
charges Charge or charged may refer to: Arts, entertainment, and media Films * ''Charge, Zero Emissions/Maximum Speed'', a 2011 documentary Music * ''Charge'' (David Ford album) * ''Charge'' (Machel Montano album) * '' Charge!!'', an album by The Aqu ...
in heraldry. Heads of humans are sometimes blazoned simply as a "man's head", but are far more frequently described in greater detail, either characteristic of a particular race or nationality (such as Moors' heads, Saxons' heads, Egyptians' heads or Turks' heads), or specifically identified (such as the head of Moses in the crest of Hilton, or the head of St. John the Baptist in the crest of the London Company of Tallowchandlers). Several varieties of women's heads also occur, including maidens' heads (often couped under the bust, with hair disheveled), ladies' heads, nuns' heads (often veiled), and occasionally queens' heads. The arms of Devaney of Norfolk include "three nun's heads veiled couped at the shoulders proper," and the bust of a queen occurs in the arms of Queenborough, Kent. Infants' or children's heads are often couped at the shoulders with a snake wrapped around the neck (e.g. "Argent, a boy's head proper, crined or, couped below the shoulders, vested gules, tarnished gold," in the arms of Boyman). File:Flag of Corsica.svg, The flag of
Corsica Corsica ( , Upper , Southern ; it, Corsica; ; french: Corse ; lij, Còrsega; sc, Còssiga) is an island in the Mediterranean Sea and one of the 18 regions of France. It is the fourth-largest island in the Mediterranean and lies southeast of ...
displays a head in profile view


Art

One of the ways of drawing sketches of heads—as Jack Hamm advises—is to develop it in six well-defined steps, starting with the shape of the head in the shape of an egg. The female head, in particular, is sketched in a double circle design procedure with proportions considered as an ideal of a female head. In the first circle, the division is made of five sections on the
diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid f ...
, each section of five eyes width. It is then developed over a series of ten defined steps, with the smaller circle imposed partially over the larger circle at the lower end at the fourth stage. Eyes and chins are fitted in various shapes to form the head.
Leonardo da Vinci Leonardo di ser Piero da Vinci (15 April 14522 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially rested on ...
, considered one of the world's greatest artists, drew sketches of human anatomy using grid structures. His image of the face drawn on the grid structure principle is in perfect proportion. In this genre, using the technique of pen and ink, Leonardo created a sketch which is a "Study on the proportions of head and eyes" (pictured).


Idiomatic expressions

An
idiom An idiom is a phrase or expression that typically presents a figurative, non-literal meaning attached to the phrase; but some phrases become figurative idioms while retaining the literal meaning of the phrase. Categorized as formulaic language ...
is a phrase or a fixed expression that has a figurative, or sometimes literal, meaning. * "To be big-headed" - to be overly full of oneself * "To come to a head" – to reach a critical stage and require immediate action * "To bite someone's head off" – to criticize someone strongly * " Can't make head or tail of something" – cannot understand something * "A head start" – an early start that provides an advantage over others * " Head and shoulders above someone or something" – better than someone or something in some way * "To want someone's head on a platter" – to want someone severely punished * "To bang your head against a brick wall" – to continually try to achieve something without success * "To have one's head in the clouds" – to not pay attention to what is happening around one because one is so absorbed by one's own thoughts


Engineering and scientific fields

The head's function and appearance play an analogous role in the etymology of many technical terms.
Cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas in more modern o ...
,
pothead A pothead is a type of insulated electrical terminal used for transitioning between overhead line and underground high-voltage cable or for connecting overhead wiring to equipment like transformers. Its name comes from the process of potting o ...
, and
weatherhead A weatherhead, also called a weathercap, service head, service entrance cap, or gooseneck (slang) is a weatherproof service drop entry point where overhead power or telephone wires enter a building, or where wires transition between overhead an ...
are three such examples.


Gallery

File:Head nerves.gif, Nerves of the human head, from '' Gray's Anatomy'', 1858 File:Andrea Vaccaro, Tête de Saint-Jean Baptiste.jpg, Head of St. John the Baptist by
Andrea Vaccaro Andrea Vaccaro (baptised on 8 May 1604 – 18 January 1670) was an Italian painter of the Baroque period. Vaccaro was in his time one of the most successful painters in Naples, a city then under Spanish rule. Very successful and valued in his li ...
, oil on canvas, 17th century File:Statue de Saint Solange.JPG, Sculpture of the beheaded Saint Solange, patron saint of the French province of Berry File:Zürcher Stadtheilige.jpg, Patron saints of
Zürich , neighboring_municipalities = Adliswil, Dübendorf, Fällanden, Kilchberg, Maur, Oberengstringen, Opfikon, Regensdorf, Rümlang, Schlieren, Stallikon, Uitikon, Urdorf, Wallisellen, Zollikon , twintowns = Kunming, San Francisco Z ...
, fresco, File:POL powiat kaliski COA.svg, Heraldic depiction of a
bison Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised. Of the two surviving species, the American bison, ''B. bison'', found only in North A ...
head
cabossed In heraldry, cabossed, or caboched, is a term used where the head of a beast is cut off behind the ears, by a section parallel to the face; or by a perpendicular section: in contrast to couping, which is done by a horizontal line, and farther fr ...


See also

*
Cephalic disorder Cephalic disorders () are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. Cephalic disorders are not necessarily caused by a single factor, but may be influenced by hereditary or genetic c ...
* Cephalic flexure * Cephalic index * Cephalic phase * Cephalic presentation * Cephalic vein * ''Circle of Animals/Zodiac Heads'' – an artwork by Chinese contemporary artist and political commentator Ai Weiwei * Cynocephaly – a characteristic of having the head of a dog or of a jackal. It is a widely attested mythical phenomenon existing in many forms and contexts. * Khutang – a type of harp often surmounted by a carven animal head, often a swan * Theriocephaly – in some religious beliefs, the condition or quality of having the head of an animal, commonly used to refer the depiction in art of humans (or deities) with animal heads


References


Further reading

* {{Authority control