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Human jaw front view Human jaw left view Human jaw top view The jaw is either of the two opposable structures forming, or near the entrance to, the mouth. Image File history File links Download high resolution version (1567x1200, 222 KB) Multi-image synthesis to increase DOF. Canon 5D. 6500K illumination. ... Image File history File links Download high resolution version (1567x1200, 222 KB) Multi-image synthesis to increase DOF. Canon 5D. 6500K illumination. ... Image File history File links Download high resolution version (1600x1043, 216 KB) Macro photograph. ... Image File history File links Download high resolution version (1600x1043, 216 KB) Macro photograph. ... Image File history File links Download high resolution version (1153x1200, 118 KB) Macro photograph. ... Image File history File links Download high resolution version (1153x1200, 118 KB) Macro photograph. ... Look up Mouth in Wiktionary, the free dictionary. ... The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it. Contents 1 Arthropods 2 Vertebrates 2.1 Bones of the jaw 2.2 The jaw in fish and amphibians 2.3 The jaw in reptiles 3 See also 4 External links [edit] Arthropods In arthropods, the jaws are chitinous and oppose laterally, and may consist in mandibles, chelicerae, or, loosely, pedipalps. Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Types of chelicerae: jackknife (in green), scissor (in blue) and 3-segmented chelate (in red) The Chelicerae are mouth parts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata (horseshoe crabs), and Pycnogonida (sea spiders). ... Male European garden spider with swollen pedipalps Pedipalps are a pair of feelers on a spiders face. ... Their function is fundamentally for food acquisition, conveyance to the mouth, and/or initial processing (mastication or chewing). [edit] Vertebrates In most vertebrates, the jaws are bony or cartilaginous and oppose vertically, comprising an upper jaw and a lower jaw. Classes and Clades See below Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns. ... Grays Anatomy illustration of a human femur. ... Cartilage is a type of dense connective tissue. ... [edit] Bones of the jaw In vertebrates, the lower jaw, dentary or mandible is the mobile component that articulates at its posterior processes, or rami (singular ramus), with the temporal bones of the skull on either side; the word jaw used in the singular typically refers to the lower jaw. It has been suggested that this article or section be merged with jaw. ... It has been suggested that temporal fenestra be merged into this article or section. ... The upper jaw or maxilla is more or less fixed with the skull and is composed of two bones, the maxillae, fused intimately at the median line by a suture; incomplete closure of this suture and surrounding structures may be involved in the malformation known as cleft palate. The anatomical planes The anatomical position is a schematic convention for describing the relative morphology of the human body. ... It has been suggested that suture material be merged into this article or section. ... The maxillary bones form parts of the roof of the mouth, the floor and sides of the nasal cavity, and the floor of the orbit or eye socket. Human nose in profile A typical bulbous human nose Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for respiration. ... In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. ... The jaws typically accommodate the teeth or form the bases for the attachment of a beak. This does not cite its references or sources. ... The beak—otherwise known as the bill or rostrum—is an external anatomical structure which serves as the mouth in some animals. ... [edit] The jaw in fish and amphibians The vertebrate jaw probably originally evolved in the Silurian period and appeared in the Placoderm fish which further diversified in the Devonian. Jaws are thought to derive from the pharyngeal arches that support the gills in fish. The two most anterior of these arches are thought to have become the jaw itself and the hyoid arch, which braces the jaw against the braincase and increases mechanical efficiency. While there is no fossil evidence directly to support this theory, it makes sense in light of the numbers of pharyngeal arches that are visible in extant jawed (the Gnathostomes), which have seven arches, and primitive jawless vertebrates (the Agnatha), which have nine. The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ... Orders Antiarchi† Arthrodira† Petalichthyda† Phyllolepida† Ptyctodontida† Rhenanida† The Placodermi are armoured prehistoric fishes known from fossils dating from the late Silurian to the end of the Devonian Period. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... Disambiguation: Devonian is sometimes used to refer to the Southwestern Brythonic language, and the people of the county of Devon are sometimes referred to as Devonians The Devonian is a geologic period of the Paleozoic era. ... In aquatic organisms, gills are a respiratory organ for the extraction of oxygen from water and for the excretion of carbon dioxide. ... Classes Placodermi Chondrichthyes Acanthodii Osteichthyes Gnathostomata is the group of vertebrates with jaws. ... {{ | name = Agnatha | image = Agnata. ... It is thought that the original selective advantage garnered by the jaw was not related to feeding, but to increased respiration efficiency. The jaws were used in the buccal pump (observable in modern fish and amphibians) that pumps water across the gills of fish or air into the lungs in the case of amphibians. Over evolutionary time the more familiar use of jaws (to humans), in feeding, was selected for and became a very important function in vertebrates. For other uses, see Amphibian (disambiguation). ... [edit] The jaw in reptiles In reptiles, the mandible is made up of five bones. In the evolution of mammals, four of these bones were reduced in size and incorporated into the ear. In their reduced form, they are known as the malleus and incus; along with the more ancient stapes, they are the ossicles. This adaptation is advantageous, not only because a one-bone jaw is stronger, but also because the malleus and incus improve hearing. (However, reptiles tend to swallow prey whole because their pace of digestion is different than mammals, so multiple jaw bones may allow flexibility to expand the jaws around prey.) Subclasses Anapsida Diapsida Reptiles are tetrapods and amniotes, animals whose embryos are surrounded by an amniotic membrane. ... It has been suggested that this article or section be merged with jaw. ... I smoke weed im growing a blue penis dude#REDIRECT penises are cool ... The malleus is hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum. ... This article refers to a bone in the mammalian ear. ... The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the oval window which is adjacent to the vestibule of the inner ear. ... The ossicles (also called auditory ossicles) are the three smallest bones in the human body. ... [edit] See also Look up Jaw in Wiktionary, the free dictionary. Gnathostomata - jawed vertebrates Predentary Premaxilla Rostral bone Wikipedia does not have an article with this exact name. ... Wiktionary is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ... Classes Placodermi Chondrichthyes Acanthodii Osteichthyes Gnathostomata is the group of vertebrates with jaws. ... The predentary is an extra bone in the front of the lower jaw, which extended the dentary (the main lower jaw bone). ... The premaxilla is a pair of small bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. ... The rostral bone is the edentulous (toothless) dorsal component of the skeleton of the beak, unique to (an autapomorphy of) the ceratopsian dinosaurs. ... [edit] External links Prehistoric Fish Had Most Powerful Jaws MeSH Jaw Category: Head and neck Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ...

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