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  • Antampatrana (people)

    Antandroy, a Malagasy people living in southernmost Madagascar. Numbering about 500,000 in the late 20th century, the Antandroy (“People of the Thorn Bush”) speak one of the Malagasy languages, a group of closely related Western Austronesian languages; Antandroy chiefs claim Indian origins. The

  • antanaclasis (literature)

    Antanaclasis, a word used in two or more of its possible meanings, as in the final two lines of Robert Frost’s “Stopping by Woods on a Snowy Evening”: The first use of “sleep” refers to nocturnal rest, the second to

  • Antanala (people)

    Tanala, a Malagasy people living in southeastern Madagascar who are separated from the coast by the Antaimoro and other ethnic groups. They are divided into two subgroups: the Tanala Menabe in the mountainous north and the Tanala Ikongo dwelling in the more accessible southern part of the Tanala

  • Antananarivo (national capital, Madagascar)

    Antananarivo, town and national capital of Madagascar, central Madagascar island. It was founded in the 17th century and was the capital of the Hova chiefs. Antananarivo stands on a high hill. Avenues and flights of steps lead up to a rocky ridge (4,694 feet [1,431 metres]) on which stands the

  • Antandroy (people)

    Antandroy, a Malagasy people living in southernmost Madagascar. Numbering about 500,000 in the late 20th century, the Antandroy (“People of the Thorn Bush”) speak one of the Malagasy languages, a group of closely related Western Austronesian languages; Antandroy chiefs claim Indian origins. The

  • Antapodosis (work by Liutprand of Cremona)

    Italy: Literature and art: 972), whose Antapodosis is a florid but highly literate satire of the kings of the first half of the 10th century. Charlemagne’s court drew Italian intellectuals to it and away from the peninsula, but Carolingian patronage returned to the cities of northern Italy in the mid-9th century,…

  • ʿAntar, Romance of (Arabic literature)

    Romance of ʿAntar, tales of chivalry centred on the Arab desert poet and warrior ʿAntarah ibn Shaddād, one of the poets of the celebrated pre-Islamic collection Al-Muʿallaqāt. Though the Romance of ʿAntar itself credits the 9th-century philologist al-Aṣmaʿī with its authorship, it was composed

  • Antara (Indonesian news agency)

    Adam Malik: …founded the Indonesian news agency Antara, which originally served as an organ of the nationalist press. During World War II he was active in the Indonesian youth movement. In 1945 he was involved with the abduction of the Indonesian leaders Sukarno and Mohammad Hatta in order to “force” them to…

  • Antaradus (Syria)

    Ṭarṭūs, town, western Syria, situated on the Mediterranean coast opposite Arwād Island. It was founded in antiquity as Antaradus, a colony of Aradus (now Arwād Island). It was rebuilt in 346 ce by Emperor Constantine I and flourished during Roman and Byzantine times. Crusaders occupied Ṭarṭūs, then

  • ʿAntarah ibn Shaddād (Arab poet)

    Islamic arts: Poetry: ʿAntarah ibn Shaddād, son of an Arab king and a black slave girl, won such fame on the battlefield and for his poetry that he later became the hero of the Romance of ʿAntar, an Arabic folk romance.

  • Antarctic Archipelago (island group, Antarctica)

    Palmer Archipelago, island group off the northwestern coast of the Antarctic Peninsula, from which it is separated by Gerlache and Bismarck straits. The archipelago, which includes the islands of Anvers (46 miles [74 km] long by 35 miles [56 km] wide), Liège, Brabant, and Wiencke, was discovered

  • Antarctic beech (plant)

    beech: The wavy-leaved Antarctic beech, or nire (Nothofagus antarctica), and the roble beech (N. obliqua), both 30-metre (98-foot) trees native to Chile and Argentina, differ from other species of false beech in being deciduous; they are planted as ornamentals on other continents. The pink-brown hardwood of the Antarctic…

  • Antarctic Bottom Water (oceanography)

    density current: Density currents originating from marginal seas: …and this water forms the Antarctic Bottom Water (AABW). Alternatively, an intermediate layer is created if the density difference with the surrounding waters reaches zero before the density current arrives at the bottom of the ocean. In this scenario, the current spreads horizontally at an intermediate depth. Such intermediate layers…

  • Antarctic Circle

    Antarctic Circle, parallel, or line of latitude around the Earth, at 66°30′ S. Because the Earth’s axis is inclined about 23.5° from the vertical, this parallel marks the northern limit of the area within which, for one day or more each year, at the summer and winter solstices, the Sun does not set

  • Antarctic Circumpolar Current (oceanography)

    Antarctic Circumpolar Current, surface oceanic current encircling Antarctica and flowing from west to east. Affected by adjacent landmasses, submarine topography, and prevailing winds, the Antarctic Circumpolar Current is irregular in width and course. Its motion is further complicated by c

  • Antarctic Convergence

    Antarctic Convergence, transition region of the Southern Hemisphere, a major boundary zone of the world’s oceans that separates the waters surrounding Antarctica into Antarctic and sub-antarctic regions. (It is sometimes referred to as a polar front, but use of this term can cause it to be

  • Antarctic Dinosaurs

    Two stories involving Antarctic dinosaurs captured the imagination of paleontologists and the public in 2011. Early in the year, William Hammer and colleagues revealed the discovery of two nearly 200-million-year-old dinosaur skeletons and the partial remains of a massive sauropod (a large

  • Antarctic dragonfish (fish)

    perciform: Annotated classification: Family Bathydraconidae (Antarctic dragonfishes) About 15 species; true Antarctic fishes, occurring on coasts of Antarctic continent; body greatly elongated; usually a spatulate, pikelike snout; no first dorsal fin; live on coasts of Antarctic continent to depths of 500–700 metres (about 1,650–2,300 feet), a few down to 2,500…

  • Antarctic Ice Sheet (geology)

    glacier: Antarctic Ice Sheet: The bedrock of the continent of Antarctica is almost completely buried under ice. Mountain ranges and isolated nunataks (a term derived from Greenland’s Inuit language, used for individual mountains surrounded by ice) locally protrude through the ice. Extensive in area are…

  • Antarctic Intermediate Water (oceanography)

    Antarctic Intermediate Water, ocean water mass found in all the southern oceans at depths of about 1,650 to 4,000 ft (500 to 1,200 m), characterized by temperatures of 37° to 45° F (3° to 7° C) and salinities of 33.8 to about 34.5 parts per thousand. This water mass forms at the Antarctic

  • Antarctic kingdom (floral region)

    Antarctica: Plant life: Antarctica supports only an impoverished community of cold-tolerant land plants that are capable of surviving lengthy winter periods of total or near-total darkness during which photosynthesis cannot take place. Growth must occur in short summer bursts lasting only a few days, a few weeks, or…

  • Antarctic krill (crustacean)

    krill: The body of E. superba is about 5 cm (2 inches) long and translucent, with reddish brown blotches. The swimming larvae pass through nine stages of development. Males mature in about 22 months, females in about 25 months. During a spawning period of about five and a half…

  • Antarctic meteorite (astronomy)

    Antarctic meteorite, any of a large group of meteorites that have been collected in Antarctica, first by Japanese expeditions and subsequently by U.S. and European teams since the discovery of meteorite concentrations there in 1969. Although meteorites fall more or less uniformly over Earth’s

  • Antarctic Muon and Neutrino Detector Array (research project)

    Antarctica: Climate: …on Earth is AMANDA, the Antarctic Muon and Neutrino Detector Array. This involves an array of hundreds of optical devices set at depths of up to 1.2 miles (2 km) in the ice below the South Pole. It is essentially a telescope built within the ice sheet to detect high-energy…

  • Antarctic Ocean

    Southern Ocean, the southern portions of the Pacific, Atlantic, and Indian oceans and their tributary seas surrounding Antarctica. Unbroken by any other continental landmass, the Southern Ocean’s narrowest constriction is the Drake Passage, 600 miles (about 1,000 km) wide, between South America and

  • Antarctic ozone hole

    ozone depletion: Ozone layer recovery: …while the size of the Antarctic ozone hole had been decreasing. Overall ozone concentrations away from the poles have continued to fall since 1998; however, a 2018 study showed that declines in ozone concentrations in the lower stratosphere contrasted with gains made in the upper stratosphere between 60° N and…

  • Antarctic Peninsula (peninsula, Antarctica)

    Antarctic Peninsula, peninsula claimed by the United Kingdom, Chile, and Argentina. It forms an 800-mile (1,300-km) northward extension of Antarctica toward the southern tip of South America. The peninsula is ice-covered and mountainous, the highest point being Mount Jackson at 10,446 feet (3,184

  • Antarctic petrel (bird)

    Antarctica: Birds: but only three—the emperor penguin, Antarctic petrel, and South Polar (McCormick’s) skua—breed exclusively on the continent or on nearby islands. An absence of mammalian land predators and the rich offshore food supply make Antarctic coasts a haven for immense seabird rookeries. Penguins, of the order Sphenisciformes, symbolize this polar region,…

  • Antarctic Plate (geology)

    Antarctica: Antarctica and continental drift: …and jostling of immense crustal plates (see plate tectonics). Modern plate boundaries may be far different from ancient ones presumably marked by old fold belts. Ancient Antarctic mobile belts, such as are followed by today’s Transantarctic Mountains, terminate at continental margins abruptly, as if sliced off, and seemingly reappear in…

  • Antarctic realm (faunal region)

    Antarctica: The term Antarctic region refers to all area—oceanic, island, and continental—lying in the cold Antarctic climatic zone south of the Antarctic Convergence, an important boundary around 55° S, with little seasonal variability, where warm subtropical waters meet and mix with cold polar waters (see also polar ecosystem).

  • Antarctic region (faunal region)

    Antarctica: The term Antarctic region refers to all area—oceanic, island, and continental—lying in the cold Antarctic climatic zone south of the Antarctic Convergence, an important boundary around 55° S, with little seasonal variability, where warm subtropical waters meet and mix with cold polar waters (see also polar ecosystem).

  • Antarctic Shield (geology)

    Antarctica: Structural framework: …structural provinces—a long, stable Precambrian shield in East Antarctica and a much younger Mesozoic and Cenozoic mobile belt in West Antarctica—separated by the fault-block belt, or horst, of the Transantarctic Mountains. East and West Antarctica have come to be known respectively as the Gondwana and Andean provinces, indicating general affinities…

  • Antarctic Surface Water (oceanography)

    Antarctica: The surrounding seas: …cold Antarctic water, called the Antarctic Surface Water, to form a mass with intermediate characteristics called Subantarctic Surface Water. Mixing occurs in a shallow but broad zone of approximately 10° latitude lying south of the Subtropical Convergence (at about 40° S) and north of the Antarctic Convergence (between about 50°…

  • Antarctic Treaty (1959)

    Antarctic Treaty, (Dec. 1, 1959), agreement signed by 12 nations, in which the Antarctic continent was made a demilitarized zone to be preserved for scientific research. The treaty resulted from a conference in Washington, D.C., attended by representatives of Argentina, Australia, Belgium, Britain,

  • Antarctic Treaty System (international treaties)

    Antarctica: The Antarctic Treaty: …agreements are collectively called the Antarctic Treaty System (ATS). The granting of consultative status within the Antarctic Treaty, permitting full participation in its operation with that of the original 12 contracting states, depends on long-term scientific commitment. It began in 1977 with the addition of Poland, followed by West Germany…

  • Antarctic wolf (extinct mammal)

    South American fox: …and the Falkland Island, or Antarctic, wolf (Dusicyon australis), which was hunted to extinction in the late 1800s.

  • Antarctic zone (climatic zone)

    Indian Ocean: Subantarctic and Antarctic zone: The fourth, or subantarctic and Antarctic, zone occupies the wide belt between latitude 45° S and the continent of Antarctica. Steady westerly winds prevail, reaching gale force at times with their passage through deep Antarctic low-pressure zones. The average winter air temperature varies from…

  • Antarctica (continent)

    Antarctica, fifth in size among the world’s continents. Its landmass is almost wholly covered by a vast ice sheet. Often described as a continent of superlatives, Antarctica is the world’s southernmost continent. It is also the world’s highest, driest, windiest, coldest, and iciest continent.

  • Antares (star)

    Antares, red, semiregular variable star, with apparent visual magnitude about 1.1, the brightest star in the zodiacal constellation Scorpius and one of the largest known stars, having several hundred times the diameter of the Sun and 10,000 times the Sun’s luminosity. It has a fifth-magnitude blue

  • antas (architecture)

    Anta, in architecture, slightly projecting column at the end of a wall, produced by either a thickening of the wall or attachment of a separate strip. The former type, commonly flanking porches of Greek and Roman temples, is a masonry vestige of the wooden structural posts used to reinforce the

  • antbear (mammal)

    Aardvark, (Orycteropus afer), stocky African mammal found south of the Sahara Desert in savanna and semiarid areas. The name aardvark—Afrikaans for “earth pig”—refers to its piglike face and burrowing habits. The aardvark weighs up to 65 kg (145 pounds) and measures up to 2.2 metres (7.2 feet)

  • antbird (bird family)

    Antbird, (family Thamnophilidae), any of numerous insect-eating birds of the American tropics (order Passeriformes) known for habitually following columns of marching ants. There are roughly 210 species in some 45 genera. Like their near relatives, the Furnariidae, antbirds are highly diverse; all

  • Ante-Nicene Father

    patristic literature: The pre-Nicene period: During the first three centuries of its existence, the Christian church had first to emerge from the Jewish environment that had cradled it and then come to terms with the predominantly Hellenistic (Greek) culture surrounding it. Its legal position being at best…

  • anteanaresis (mathematics)

    Euclidean algorithm, procedure for finding the greatest common divisor (GCD) of two numbers, described by the Greek mathematician Euclid in his Elements (c. 300 bc). The method is computationally efficient and, with minor modifications, is still used by computers. The algorithm involves

  • anteater (mammal)

    Anteater, (suborder Vermilingua), any of four species of toothless, insect-eating mammals found in tropical savannas and forests from southern Mexico to Paraguay and northern Argentina. They are long-tailed animals with elongated skulls and tubular muzzles. The mouth opening of the muzzle is small,

  • anteating (biology)

    mammal: Teeth: …termites, a specialization generally termed myrmecophagy (“ant eating”). Trends frequently associated with myrmecophagy include strong claws, an elongate rounded skull, a wormlike extensible tongue, marked reduction in the mandible (lower jaw), and loss or extreme simplification of the teeth (dentition). This habit has led to remarkably similar morphology among animals…

  • antecedence (geology)

    valley: Cross-axial drainage: …such relationships is that of antecedence. According to this view, the rivers were already in their present positions when the various anticlinal folds and upwarps began to grow. A relevant analogy is a saw into which a log is being pushed. The saw represents the river and its continuing degradation,…

  • antecedent (logic)

    applied logic: Hypothetical and counterfactual reasoning: …discourse, counterfactual conditionals (conditionals whose antecedent is false) are not always considered true.

  • antecedent canyon

    river: Formation of canyons and gorges: Antecedent canyons have been identified in the Alps, the Himalayas, the Andes, the Pacific coastal ranges of the United States, and every other region of the world that has experienced recent or ongoing tectonism. Second, complexly folded and faulted terranes are sometimes buried by a…

  • antecedent, denial of the (logic)

    applied logic: Formal fallacies: Among the best known are denying the antecedent (“If A, then B; not-A; therefore, not-B”) and affirming the consequent (“If A, then B; B; therefore, A”). The invalid nature of these fallacies is illustrated in the following examples:

  • Antechinomys laniger (marsupial)

    marsupial mouse: …legs—are the two species of Antechinomys, also of the Australian outback. The two species of brush-tailed marsupial mice, or tuans (Phascogale), are grayish above and whitish below in colour; the distal half of the long tail is thickly furred and resembles a bottle brush when the hairs are erected. Tuans…

  • Antechinomys spenceri (marsupial)

    marsupial mouse: …legs—are the two species of Antechinomys, also of the Australian outback. The two species of brush-tailed marsupial mice, or tuans (Phascogale), are grayish above and whitish below in colour; the distal half of the long tail is thickly furred and resembles a bottle brush when the hairs are erected. Tuans…

  • Antechinus (mammal)

    marsupial mouse: …the broad-footed marsupial mice (Antechinus species) are also known to eat nectar. The fat-tailed dunnart (Sminthopsis crassicaudata) stores excess fat in its tail. Members of all genera except Antechinus will go into torpor when food is scarce. The crest-tailed marsupial mouse, or mulgara (Dasycercus cristicauda), an arid-land species valued…

  • Antéchrist, L’  (work by Renan)

    Ernest Renan: Later writings: …found expression in L’Antéchrist (1873; The Antichrist, 1896; vol. 4 of the Histoire des origines), with its satirical portrait of Nero and its apocalyptic atmosphere—replete with expectations of a cataclysmic consummation of history—assuredly the most impressive of his historical narratives. The “festival of the universe” provides a visionary end to…

  • antefix (architecture)

    imbrex: …of imbrex tiles was an antefix, or decorative terminal.

  • Anteia (Greek mythology)

    Bellerophon: …of King Proetus of Argos—named Anteia (in Homer’s telling) or Stheneboea (in the works of Hesiod and later writers)—loved Bellerophon; when he rejected her overtures, she falsely accused him to her husband. Proetus then sent Bellerophon to Iobates, the king of Lycia, with a message that he was to be…

  • Antelami, Benedetto (Italian artist)

    Benedetto Antelami, Italian sculptor and architect considered to have been one of the greatest of his time. Little is known of his life. It is believed that he served his apprenticeship in sculpture at Saint-Trophîme in Arles, Fr., and that this service may have influenced his sensitivity to French

  • Antella, Saint Benedict dell’ (Italian friar)
  • Antelope (island, Utah, United States)

    Great Salt Lake: Surface features and chemistry: …the largest of which are Antelope and Fremont, lie south of the cutoff. The Great Salt Lake’s record high levels in the mid-1980s threatened the Lucin Cutoff, highways, and sewage-treatment plants along the shore, and in 1987 pumps were installed that began draining some of the lake’s excess waters into…

  • antelope (mammal)

    Antelope, any of numerous Old World grazing and browsing hoofed mammals belonging to the family Bovidae (order Artiodactyla). Antelopes account for over two-thirds of the approximately 135 species of hollow-horned ruminants (cud chewers) in the family Bovidae, which also includes cattle, sheep, and

  • antelope ground squirrel (rodent)

    ground squirrel: Nontropical ground squirrels: …populated by five species of antelope ground squirrel (genus Ammospermophilus). The white-tailed antelope squirrel (A. leucurus) of the southwestern United States is one of the smallest of all ground squirrels, weighing 96 to 117 grams (3.4 to 4 ounces) and having a body up to 17 cm (6.7 inches) long…

  • Antelope Wife, The (novel by Erdrich)

    Louise Erdrich: …of Burning Love (1996) and The Antelope Wife (1998) detail tumultuous relationships between men and women and their aftermath. Erdrich returned to the setting of her earlier novels for The Last Report on the Miracles at Little No Horse (2001), about the tribulations of a woman who assumes the identity…

  • antemasque (entertainment)

    Ben Jonson: His masques at court: …he also invented the “antimasque,” which preceded the masque proper and which featured grotesques or comics who were primarily actors rather than dancers or musicians.

  • Antemoro (people)

    Madagascar: Madagascar from 1500 to c. 1650: …another group known as the Antemoro. By the 1630s the Antemoro had formed a theocratic state, which was the only state in Madagascar at the time to possess written texts. Using the Arabic alphabet, the texts were written in the Malagasy language and were both religious and secular in nature.…

  • antemortem inspection (food processing)

    meat processing: Antemortem and postmortem inspection: Antemortem inspection identifies animals not fit for human consumption. Here animals that are down, disabled, diseased, or dead (known as 4D animals) are removed from the food chain and labeled “condemned.” Other animals showing signs of being sick are labeled “suspect” and are segregated from…

  • antenatal development (physiology)

    Prenatal development, in humans, the process encompassing the period from the formation of an embryo, through the development of a fetus, to birth (or parturition). The human body, like that of most animals, develops from a single cell produced by the union of a male and a female gamete (or sex

  • antenna (electronics)

    Antenna, component of radio, television, and radar systems that directs incoming and outgoing radio waves. Antennas are usually metal and have a wide variety of configurations, from the mastlike devices employed for radio and television broadcasting to the large parabolic reflectors used to r

  • antenna (animal appendage)

    crustacean: Appendages: …most adults the antennules and antennae are sensory organs, but in the nauplius larva the antennae often are used for both swimming and feeding. Processes at the base of the antennae can help the mandibles push food into the mouth. The mandibles of a nauplius have two branches with a…

  • antenna array (electronics)

    antenna: More powerful antennas were constructed during the 1920s by combining a number of elements in a systematic array. Metal horn antennas were devised during the subsequent decade following the development of waveguides that could direct the propagation of very high-frequency radio signals.

  • antennal gland (anatomy)

    coxal gland: They are called antennal glands or maxillary glands, depending on whether they open at the base of the antennae or at the maxillae. If the tubule adjacent to the excretory pore is green, the gland is called a green gland.

  • antennal squame (crustacean)

    malacostracan: Size range and diversity of structure: The outer branch of the second antennae (antennal squame), which is usually flat and bladelike for elevation and swimming balance, has two segments in stomatopods and some mysids and one segment in syncarids and eucarids; it may be small or lost entirely in amphipods, isopods, and other bottom-dwelling or subterranean…

  • Antennaria (plant)

    Pussy-toes, any of several species of low-growing, gray-white, wooly plants of a genus (Antennaria) in the aster family (Asteraceae), native to North and South America, northern Europe, and Asia. Typically the basal leaves are large, with smaller and fewer leaves along the upright stem. Some

  • Antennaria dioica (plant)

    pussy-toes: Antennaria dioica has several cultivated varieties of white, wooly appearance and with small clusters of white to rose flowers. In some species, including smaller pussy-toes (A. neodioica), male flowers are rare. The plantain-leaved pussy-toes (A. plantaginifolia), also called ladies’ tobacco, has longer and broader basal…

  • Antennaria plantaginifolia (plant)

    pussy-toes: The plantain-leaved pussy-toes (A. plantaginifolia), also called ladies’ tobacco, has longer and broader basal leaves.

  • Antennariidae (fish)

    Frogfish, any of about 60 species of small marine fishes of the family Antennariidae (order Lophiiformes), usually found in shallow, tropical waters. Frogfishes are robust, rather lumpy fishes with large mouths and, often, prickly skins. The largest species grow about 30 cm (12 inches) long.

  • antennule (crustacean)

    malacostracan: Size range and diversity of structure: The first antennae (antennules) usually have two branches (three in the subclass Hoplocarida). The outer branch of the second antennae (antennal squame), which is usually flat and bladelike for elevation and swimming balance, has two segments in stomatopods and some mysids and one segment in syncarids and eucarids;…

  • Antenor (Greek sculptor)

    Antenor, Athenian sculptor of the late Archaic period who carved the first group of statues of the tyrannicides Harmodius and Aristogiton for the Athenian agora and a kore (a freestanding figure of a maiden) for the Acropolis (now in the Acropolis Museum in Athens). Antenor’s bronze sculpture of

  • Antequera (Spain)

    Antequera, city, Málaga provincia (province), in the comunidad autónoma (autonomous community) of Andalusia, southern Spain, northwest of Málaga, at the foot of the Sierra del Torcal. Neolithic dolmens (Menga, Viera, and El Romeral) attest to prehistoric occupation of the site. The city, known to

  • Antequera, El de (king of Aragon)

    Ferdinand I, king of Aragon from 1412 to 1416, second son of John I of Castile and Eleanor, daughter of Peter IV of Aragon. Because his elder brother, Henry III, was an invalid, Ferdinand took the battlefield against the Muslims of Granada. When Henry III died in 1406, his son John II was an infant

  • Antequera, José (Colombian politician)

    Ernesto Samper Pizano: …as he stood talking to José Antequera, a member of the left-wing Patriotic Union (Unión Patriótica; UP), an assassin opened fire, killing Antequera and wounding Samper. The attack prevented Samper from running for president in the 1990 election, but he served in Pres. César Gaviria Trujillo’s cabinet as minister of…

  • Antergan (drug)

    antihistamine: H1 receptor antagonists: …antihistamines (an aniline derivative called Antergan) was discovered. Subsequently, compounds that were more potent, more specific, and less toxic were prepared, including the H1 receptor antagonists diphenhydramine, chlorpheniramine, promethazine, and loratidine.

  • anterior blepharitis (medical condition)

    blepharitis: …are two forms of blepharitis: anterior, which affects the exterior edge of the eyelid, and posterior, which affects the inner part of the eyelid (the surface that touches the eye). Anterior blepharitis can result from either an infectious or a noninfectious process, while posterior blepharitis is caused by dysfunction of…

  • anterior fontanel (anatomy)

    fontanel: The largest fontanel, the anterior, is at the crown between the halves of the frontal and the parietals. It is diamond shaped and about 2.5 centimetres by 4 centimetres (about 1 by 1.5 inches). The lateral fontanels close within three months of birth, the posterior fontanel at about two…

  • anterior fontanelle (anatomy)

    fontanel: The largest fontanel, the anterior, is at the crown between the halves of the frontal and the parietals. It is diamond shaped and about 2.5 centimetres by 4 centimetres (about 1 by 1.5 inches). The lateral fontanels close within three months of birth, the posterior fontanel at about two…

  • anterior foregut (zoology)

    malacostracan: Digestion and nutrition: The large anterior foregut, or cardiac stomach, occupies much of the posterior aspect of the head and the anterior thoracic body cavity. A constriction separates it from the smaller, more ventral, pyloric stomach that lies in the posterior part of the thorax. Lining the inside of the greatly folded and…

  • anterior interventricular sulcus (anatomy)

    human cardiovascular system: External surface of the heart: The other, the anterior interventricular sulcus, runs along the line between the right and left ventricles and contains a branch of the left coronary artery.

  • anterior lobe (anatomy)

    hormone: Hormones of the pituitary gland: The other is the adenohypophysis, which develops as an upgrowth from the buccal cavity (mouth region) and usually includes two glandular portions, the pars distalis and the pars intermedia, which secrete a number of hormones. The hormones secreted by the adenohypophysis are protein or polypeptide in nature and vary…

  • anterior nasal diphtheria (pathology)

    diphtheria: …appears inside the nostrils in anterior nasal diphtheria; almost no toxin is absorbed from this site, so there is little danger to life, and complications are rare. In faucial diphtheria, the most common type, the infection is limited mostly to the tonsillar region; most patients recover if properly treated with…

  • anterior nuclear group (anatomy)

    human nervous system: Thalamus: …major thalamic nuclei include the anterior nuclear group, the mediodorsal nucleus, and the pulvinar. The anterior nuclear group receives input from the hypothalamus and projects upon parts of the limbic lobe (i.e., the cingulate gyrus). The mediodorsal nucleus, part of the medial nuclear group, has reciprocal connections with large parts…

  • anterior pituitary hormone

    pituitary gland: Structure and function of anterior pituitary hormones: The hormones of the anterior pituitary are proteins that consist of one or two long polypeptide chains. TSH, LH, and FSH are called glycoproteins because they contain complex carbohydrates known as glycosides. Each of those hormones is composed of two glycopeptide chains,…

  • anterior pituitary lobe (anatomy)

    hormone: Hormones of the pituitary gland: The other is the adenohypophysis, which develops as an upgrowth from the buccal cavity (mouth region) and usually includes two glandular portions, the pars distalis and the pars intermedia, which secrete a number of hormones. The hormones secreted by the adenohypophysis are protein or polypeptide in nature and vary…

  • anterior semicircular canal (anatomy)

    human ear: Semicircular canals: …designated according to their position: superior, horizontal, and posterior. The superior and posterior canals are in diagonal vertical planes that intersect at right angles. Each canal has an expanded end, the ampulla, which opens into the vestibule. The ampullae of the horizontal and superior canals lie close together, just above…

  • anterior speech area (anatomy)

    Broca area, region of the brain that contains neurons involved in speech function. This area, located in the frontal part of the left hemisphere of the brain, was discovered in 1861 by French surgeon Paul Broca, who found that it serves a vital role in the generation of articulate speech. The Broca

  • anterior superior alveolar nerve (anatomy)

    human nervous system: Maxillary nerve: …middle cranial fossa, (2) the alveolar nerves, serving the upper teeth and gingiva and the lining of the maxillary sinus, (3) the nasal and palatine nerves, which serve portions of the nasal cavity and the mucosa of the hard and soft palate, and (4) the infraorbital, zygomaticotemporal, and zygomaticofacial nerves,…

  • anterior uveitis (pathology)

    uveitis: Anatomical forms of uveitis: Anterior uveitis typically refers to inflammation of the iris and anterior chamber; intermediate uveitis refers to inflammation of the ciliary body and vitreous humour (the jellylike filling in the anterior portion of the eye); and posterior uveitis refers to inflammation of the retina, choroid, or…

  • anterior vagal trunk (anatomy)

    human nervous system: Vagus nerve (CN X or 10): …form the posterior (right) and anterior (left) vagal nerves. Right and left vagal nerves are joined in the thorax by cardiac, pulmonary, and esophageal branches. In addition, general visceral afferent fibres from the larynx below the vocal folds join the vagus via the recurrent laryngeal nerves, while comparable input from…

  • anterior vena cava (anatomy)

    vena cava: …of two major trunks, the anterior and posterior venae cavae, that deliver oxygen-depleted blood to the right side of the heart. The anterior vena cava, also known as the precava, drains the head end of the body, while the posterior vena cava, or postcava, drains the tail, or rear, end.…

  • antero-posterior dominance (biology)

    Charles Manning Child: …Child advanced a theory of antero-posterior dominance, stating that physiological activity in a multicellular organism increases along its axis from bottom to top (or tail to head), and that this gradient of activity in a tissue fragment determines the position of structures growing from it. He felt that the gradient…

  • anterograde amnesia (pathology)

    memory abnormality: Organic disorders: …events) the defect is termed anterograde amnesia. Retrograde loss may progressively abate or shrink if recovery begins, or it may gradually enlarge in scope, as in cases of progressive brain disease. Minor grades of memory defect are not uncommon aftereffects of severe head injury or infections such as encephalitis; typically…

  • anterograde degeneration (pathology)

    human nervous system: Functions of the human nervous system: This phenomenon is called anterograde degeneration. In retrograde degeneration, similar changes may occur in neurons that have lost the main recipient of their outflow.

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