"two bones along the palatal fissure that form the upper jaw. This is similar to the mandible (lower jaw), which is also a fusion of two halves at the mandibular symphysis. In bony fish, the maxilla is called the ""upper maxilla,"" with the mandible being the ""lower maxilla"". The alveolar process of the maxilla holds the upper teeth, and is referred to as the maxillary arch. In most vertebrates, the foremost part of the upper jaw, to which the incisors are attached in mammals consists of a separate pair of bones, the premaxillae. In bony fish, both maxilla and premaxilla"
"Situated beneath the mandibles, paired maxillae manipulate food during mastication. Maxillae can have hairs and ""teeth"" along their inner margins. At the outer margin, the galea is a cupped or scoop-like structure, which sits over the outer edge of the labium. They also have palps, which are used to sense the characteristics of potential foods. The maxillae occupy a lateral position, one on each side of the head behind the mandibles. The proximal part of the maxilla consists of a basal cardo, which has a single articulation with the head, and a flat plate, the stipes, hinged to the cardo."
"Maxilla (arthropod mouthpart) In arthropods, the maxillae (singular maxilla) are paired structures present on the head as mouthparts in members of the clade Mandibulata, used for tasting and manipulating food. Embryologically, the maxillae are derived from the 4th and 5th segment of the head and the maxillary palps; segmented appendages extending from the base of the maxilla represent the former leg of those respective segments. In most cases, two pairs of maxillae are present and in different arthropod groups the two pairs of maxillae have been variously modified. In crustaceans, the first pair are called maxillulae (singular maxillula). Modified coxae"
"the two pairs of maxillae are called maxillulae (1st pair) and maxillae (2nd pair). They serve to transport food to the mandibles but also frequently help in the filtration process and additionally they may sometimes play a role in cleaning and grooming. These structures show an incredible diversity throughout crustaceans but generally are very much flattened and leaf-like. The two pairs are normally positioned very close together and their apical parts generally are in direct contact with the mandible. The generalized condition in hexapods is for the first pair of maxillae to consist of a basal triangular sclerite called the"
"food. Each maxilla consists of two parts, the proximal cardo (plural ""cardines""), and distal stipes (plural ""stipites""). At the apex of each stipes are two lobes, the inner lacinia and outer galea (plurals ""laciniae"" and ""galeae""). At the outer margin, the typical galea is a cupped or scoop-like structure, located over the outer edge of the labium. In non-chewing insects, such as adult Lepidoptera, the maxillae may be drastically adapted to other functions. Unlike the mandibles, but like the labium, the maxillae bear lateral palps on their stipites. These palps serve as organs of touch and taste in feeding, and"
"to the head, where the mandibles can eat it. The labium is similar in structure to the maxilla, but with the appendages of the two sides fused by the midline, so they come to form a median plate. The basal part of the labium, equivalent to the maxillary cardines and possibly including a part of the sternum of the labial segment, is called the postmentum. This may be subdivided into a proximal submentum and a distal mentum. Distal to the postmentum, and equivalent to the fused maxillary stipites, is the prementum. The prementum closes the preoral cavity from behind. Terminally,"
"hypopharynx, and the labrum. The mandibles and the maxillae are used for piercing the skin. The mandibles are pointed, while the maxillae end in flat, toothed ""blades"". To force these into the skin, the mosquito moves its head backwards and forwards. On one movement, the maxillae are moved as far forward as possible. On the opposite movement, the mandibles are pushed deeper into the skin by levering against the maxillae. The maxillae do not slip back because the toothed blades grip the skin. The hypopharynx and the labrum are both hollow. Saliva with anticoagulant is pumped down the hypopharynx to"
"growth. Proponents of this theory state that cartilage is responsible for the growth and bone just replaced it. In this theory, mandibular condyle having cartilage at its end allows the downward and forward growth of the mandible. Maxilla, consisting of the nasal septum and nasomaxillary complex, which is made up of cartilage, moves forward and downward also by the forces from the nasal septum. Bones in both maxilla and mandible respond to their respective cartilaginous growth centers. To test this theory, two approaches were taken by researchers in past. Either the cartilage was removed from the nasal septum or the"
"Processes The mandible has two main holes (foramina), found on both its right and left sides: The Inferior alveolar nerve, a branch of the mandibular nerve, (a major division of the trigeminal nerve), enters the mandibular foramen and runs forward in the mandibular canal, supplying sensation to the teeth. At the mental foramen, the nerve divides into two terminal branches: incisive and mental nerves. The incisive nerve runs forward in the mandible and supplies the anterior teeth. The mental nerve exits the mental foramen and supplies sensation to the lower lip. Males generally have squarer, stronger, and larger mandibles than"
"less heavily sclerotised than mandibles, so they are more important in manipulating soft, liquid, or particulate food rather than cutting or crushing food such as material that requires the mandibles to cut or crush. Like the mandibles, maxillae are innervated by the sub-esopharyngeal ganglia. The labium typically is a roughly quadrilateral structure, formed by paired, fused secondary maxillae. It is the major component of the floor of the mouth. Typically, together with the maxillae, the labrum assists manipulation of food during mastication. The role of the labium in some insects however, is adapted to special functions; perhaps the most dramatic"
"to the lower lip (labium). Crustaceans have a pair of mandibles that typically consist of an enlarged basal segment (coxa) and a palp (sensory feeler) consisting of all other segments. In some groups, such as the Branchiopoda, the palp is reduced or absent. Crustacean mandibles may be equipped with special teeth (molar and incisor processes). Mandible (arthropod mouthpart) The mandible (from or mandĭbŭ-lum, a jaw) of an arthropod is a pair of mouthparts used either for biting or cutting and holding food. Mandibles are often simply referred to as jaws. Mandibles are present in the extant subphyla Myriapoda (millipedes and"
"species, the mandibles. The labrum is a simple, fused sclerite, often called the upper lip, and moves longitudinally, which is hinged to the clypeus. The mandibles (jaws) are a highly sclerotized pair of structures that move at right angles to the body, used for biting, chewing, and severing food. The maxillae are paired structures that can also move at right angles to the body and possess segmented palps. The labium (lower lip) is the fused structure that moves longitudinally and possesses a pair of segmented palps. The mouthparts, along with the rest of the head, can be articulated in at"
"and mandibles, which have been modified into elongated shapes from a basic, ancestral style. The right and left maxillary stylets are connected at their midline and a section at the centerline forms a large food canal and a smaller salivary canal. The entire maxillary and mandibular bundle penetrates the skin. The tips of the right and left maxillary stylets are not the same; the right is hook-like and curved, and the left is straight. The right and left mandibular stylets extend along the outer sides of their respective maxillary stylets and do not reach anywhere near the tip of the"
"which the fly can imbibe liquids. In Lepidopterans, the fluid-sucking proboscis is formed entirely from the galea of the maxillae although labial palps are also present. In Odonata nymphs, the labium forms a mask-like extensible structure, which is used for reaching out and grasping prey. Maxilla (arthropod mouthpart) In arthropods, the maxillae (singular maxilla) are paired structures present on the head as mouthparts in members of the clade Mandibulata, used for tasting and manipulating food. Embryologically, the maxillae are derived from the 4th and 5th segment of the head and the maxillary palps; segmented appendages extending from the base of"
"embryonically is—two structures). It is the upper-most of the mouthparts and located on the midline. It serves to hold food in place during chewing by the mandibles and thus can simply be described as an upper lip. Chewing insects have two mandibles, one on each side of the head. They are typically the largest mouthpart of chewing insects, being used to masticate (cut, shred, tear, crush, chew) food items. They open outwards (to the sides of the head) and come together medially. Paired maxillae cut food and manipulate it during mastication. Maxillae can have hairs and ""teeth"" along their inner"
"Premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla and usually termed as the incisive bone. Other terms used for this structure include premaxillary bone or os premaxillare, and intermaxillary bone or os intermaxillare. In humans, the premaxilla is referred to as the incisive bone and is the part of the maxilla which bears the incisor teeth, and encompasses the anterior nasal spine and alar region. In the nasal cavity,"
"as a 'template', but the mandible does ""not"" arise from direct ossification of Meckel's cartilage. The skeletal elements and muscles are derived from mesoderm of the pharyngeal arches. Mucous membrane and glands of the anterior two thirds of the tongue are derived from ectoderm and endoderm of the arch. The mandibular and maxillary branches of the trigeminal nerve (CN V) innervate the structures derived from the corresponding processes of the first arch. In some lower animals, each arch is supplied by two cranial nerves. The nerve of the arch itself runs along the cranial side of the arch and is"
"Maxillary nerve The maxillary nerve (CN V) is one of the three branches or divisions of the trigeminal nerve, the fifth (V) cranial nerve. It comprises the principal functions of sensation from the maxillary, nasal cavity, sinuses, the palate and subsequently that of the mid-face, and is intermediate, both in position and size, between the ophthalmic nerve and the mandibular nerve. It begins at the middle of the trigeminal ganglion as a flattened plexiform band, and, passing horizontally forward, it leaves the skull through the foramen rotundum, where it becomes more cylindrical in form, and firmer in texture. It then"
"Buccinator muscle The buccinator ( ) is a thin quadrilateral muscle occupying the interval between the maxilla and the mandible at the side of the face. It forms the anterior part of the cheek or the lateral wall of the oral cavity. It arises from the outer surfaces of the alveolar processes of the maxilla and mandible, corresponding to the three pairs of molar teeth; and behind, from the anterior border of the pterygomandibular raphé which separates it from the constrictor pharyngis superior. It is attached upon the buccinator crest as far forward as the first molar tooth. The fibers"
"a maxillary process and a mandibular process, giving rise to structures including the bones of the lower two-thirds of the face and the jaw. The maxillary process becomes the maxilla (or upper jaw), and palate while the mandibular process becomes the mandible or lower jaw. This arch also gives rise to the muscles of mastication. Meckel's cartilage forms in the mesoderm of the mandibular process and eventually regresses to form the incus and malleus of the middle ear, the anterior ligament of the malleus and the sphenomandibular ligament. The mandible or lower jaw forms by perichondral ossification using Meckel's cartilage"
"are on located on the upper jaw, and two pairs of mandibular barbels are on the lower jaw. The maxillary barbel has a narrow membrane attached near the base and is straight without any branches. It extends at least as far as the base of the pectoral spine, a bit less than half of length of the head. The outer pair of mandibular barbels extends just past the front of the pectoral girdle, about of the length of the head, and contains three to six weak branches, usually without secondary branches. The inner pair of mandibular barbels is about to"
"called the upper lip, and moves longitudinally, which is hinged to the clypeus. The mandibles (jaws) are a highly sclerotized pair of structures that move at right angles to the body; used for biting, chewing and severing food. The maxillae are paired structures that can also move at right angles to the body and possess segmented palps. The labium (lower lip) is the fused structure that moves longitudinally and possesses a pair of segmented palps. The mouthparts, along with the rest of the head, can be articulated in at least three different positions: prognathous, opisthognathous and hypognathous. In species with"
"at the base of the pedipalps in spiders are also called ""maxillae"", although they are not homologous with mandibulate maxillae. In millipedes, the second maxillae have been lost, reducing the mouthparts to only the first maxillae which have fused together to form a gnathochilarium, acting as a lower lip to the buccal cavity and the mandibles which have been enlarged and specialized greatly, used for chewing food. The gnathochilarium is richly infused with chemosensory and tactile receptors along its edge. A pair of maxillary glands, also called nephridial organs, involved in osmoregulation and excreting nitrogenous waste open up to the"
"a bone called the mandible, more commonly known as the jaw, at their respective alveolar processes. The surface of the oral cavity between the teeth and the inner side of the lips are called the oral vestibule. Surrounding the oral cavity, there are many different muscles that facilitate chewing, opening the mouth, and swallowing. Each muscle, group of muscles, or separate anatomical compartment is encased in a thin fibrous layer of connective tissue called fascia. Normally, the fascia of adjacent structures are in direct contact with each other. However, air or pus can occupy the space between adjacent fascia, known"
"aspect of the maxillary molar teeth. The gingiva on the palatal aspect of the maxillary teeth is innervated by the greater palatine nerve apart from in the incisor region, where it is the nasopalatine nerve (long sphenopalatine nerve). The gingiva of the lingual aspect of the mandibular teeth is innervated by the sublingual nerve, a branch of the lingual nerve. The gingiva on the facial aspect of the mandibular incisors and canines is innervated by the mental nerve, the continuation of the inferior alveolar nerve emerging from the mental foramen. The gingiva of the buccal (cheek) aspect of the mandibular"
"to the labrum show it is innervated by the tritocerebrum of the brain, which is the fused ganglia of the third head segment. This is formed from fusion of parts of a pair of ancestral appendages found on the third head segment, showing their relationship. Its ventral, or inner, surface is usually membranous and forms the lobe-like epipharynx, which bears mechanosensilla and chemosensilla. Chewing insects have two mandibles, one on each side of the head. The mandibles are positioned between the labrum and maxillae. The mandibles cut and crush food, and may be used for defense; generally, they have an"
"mandibles and a single pair of maxillae fused into a lip; centipedes have long, threadlike antennae, a pair of small mandibles, two pairs of maxillae and a pair of large poison claws. Millipedes come in a variety of body shapes and sizes, ranging from to around in length, and can have as few as eleven to over a hundred segments. They are generally black or brown in colour, although there are a few brightly coloured species, and some have aposematic colouring to warn that they are toxic. Species of ""Motyxia"" produce cyanide as a chemical defence and are bioluminescent. Body"
"lacineal flexor arises in the cranium, but neither the lacinea nor the galea has an extensor muscle. The palp has levator and depressor muscles arising in the stipes, and each segment of the palp has a single muscle causing flexion of the next segment. In mandibulate mouthparts, the labium is a quadrupedal structure, although it is formed from two fused secondary maxillae. It can be described as the floor of the mouth. With the maxillae, it assists with manipulation of food during mastication or chewing or, in the unusual case of the dragonfly nymph, extends out to snatch prey back"
"affected more commonly than the maxilla. This is thought to be related to the differences in blood supply between the mandible and the maxilla. The maxilla has a better blood supply, and has thin cortical plates and less medullary spaces. These factors mean that infections of the maxilla are not readily confined to the bone, and readily dissipate edema and pus into the surrounding soft tissues and the paranasal air sinuses. OM of the maxilla may rarely occur during an uncontrolled infection of the middle ear or in infants who have sustained birth injury due to forceps. The mandible in"
"needle-like projections used to penetrate plant and animal tissues. The stylets and the feeding tube form the modified mandibles, maxilla, and hypopharynx. Mandibular mouthparts are found in species of Odonata, adult Neuroptera, Coleoptera, Hymenoptera, Blattodea, Orthoptera, and Lepidoptera. However, most adult Lepidoptera have siphoning mouthparts, while their larvae (commonly called caterpillars) have mandibles. The labrum is a broad lobe forming the roof of the preoral cavity, suspended from the clypeus in front of the mouth and forming the upper lip. On its inner side, it is membranous and may be produced into a median lobe, the epipharynx, bearing some sensilla."
"two sides of the mandible. Fibres at the back of the muscle cross the mandible, some being inserted into the bone below the oblique line, others into the skin and subcutaneous tissue of the lower part of the face. Many of these fibers blend with the muscles about the angle and lower part of the mouth. Sometimes fibers can be traced to the zygomaticus, or to the margin of the orbicularis oris. Beneath the platysma, the external jugular vein descends from the angle of the mandible to the clavicle. Variations occur in the extension over the face and over the"
"the second antenna has been lost independently in each group, perhaps as a result of a convergent adaptation to life on land. Furthermore, there is general agreement that the mandibles, first maxillae and labium/second maxillae each represent a post-oral segment; and that the first antenna represents a preoral segment. Areas of disagreement can be grouped into three categories: the nature of the pre-antennal region in mandibulates; the nature of the labrum; and the relationship between the chelicerate and mandibulate anterior segments. The degree to which the area in front of the mouth is segmented remains one of the major controversies"
"Mandible (insect mouthpart) Insect mandibles are a pair of appendages near the insect’s mouth, and the most anterior of the three pairs of oral appendages (the labrum is more anterior, but is a single fused structure). Their function is typically to grasp, crush, or cut the insect’s food, or to defend against predators or rivals. Insect mandibles, which appear to be evolutionarily derived from legs, move in the horizontal plane unlike those of vertebrates, which appear to be derived from gill arches and move vertically. The mouthparts of orthopteran insects are often used as a basic example of mandibulate (chewing)"