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arch |
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arch (ahrch) a structure of bowlike or curved outline. arch of aorta , aortic arch the curving portion between the ascending aorta and the descending aorta, giving rise to the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery. aortic arches paired vessels arching from the ventral to the dorsal aorta through the branchial arches of fishes and the pharyngeal arches of amniote embryos. In mammalian development, arches 1 and 2 disappear; 3 joins the common to the internal carotid artery; 4 becomes the arch of the aorta and joins the aorta and subclavian artery; 5 disappears; 6 forms the pulmonary arteries and, until birth, the ductus arteriosus. branchial arches paired arched columns that bear the gills in lower aquatic vertebrates and which, in embryos of higher vertebrates, become modified into structures of the head and neck. In human embryos, called pharyngeal a's. cervical aortic arch a rare anomaly in which the aortic arch has an unusually superior location. dental arch the curving structure formed by the teeth in their normal position; the inferior dental a. is formed by the mandibular teeth, the superior dental a. by the maxillary teeth. double aortic arch a congenital anomaly in which the aorta divides into two branches which embrace the trachea and esophagus and reunite to form the descending aorta. arches of foot the longitudinal and transverse arches of the foot. lingual arch a wire appliance that conforms to the lingual aspect of the dental arch, used to promote or prevent movement of the teeth in orthodontic work. mandibular arch 1. the first pharyngeal arch, from which are developed the bone of the lower jaw, malleus, and incus. maxillary arch 1. palatal a. 2. superior dental a., see dental a. neural arch the primordium of the vertebral arch; one of the cartilaginous structures surrounding the embryonic spinal cord. open pubic arch a congenital anomaly in which the pubic arch is not fused, the bodies of the pubic bones being spread apart. oral arch one formed by the roof of the mouth from the teeth (or residual dental arch) on one side to those on the other. palatal arch the arch formed by the roof of the mouth from the teeth on one side of the maxilla to the teeth on the other or, if the teeth are missing, from the residual dental arch on one side to that on the other. palatoglossal arch the anterior of the two folds of mucous membrane on either side of the oropharynx, enclosing the palatoglossal muscle. palatopharyngeal arch the posterior of the two folds of mucous membrane on either side of the oropharynx, enclosing the palatopharyngeal muscle. palmar arches four arches in the palm: the deep palmar arterial a. formed by anastomosis of the terminal part of the radial artery with the deep branch of the ulnar, its accompanying deep palmar venous a., and the superficial palmar arterial a. formed by anastomosis of the terminal part of the ulnar artery with the superficial palmar branch of the radial and its accompanying superficial palmar venous a. pharyngeal arches the branchial arches in the human embryo. plantar arch the arch in the foot formed by anastomosis of the lateral plantar artery with the deep plantar branch of the dorsal artery. pubic arch the arch formed by the conjoined rami of the ischial and pubic bones on two sides of the body. pulmonary arches the most caudal of the aortic arches, which become the pulmonary arteries. residual dental arch the curved contour of the ridge remaining after tooth removal. right aortic arch a congenital anomaly in which the aorta is displaced to the right and passes behind the esophagus, thus forming a vascular ring that may cause compression of the trachea and esophagus. supraorbital arch the curved margin of the frontal bone forming the upper boundary of the orbit. tarsal arches two arches of the median palpebral artery, one of which supplies the upper eyelid, the other the lower. tendinous arch a linear thickening of fascia over some part of a muscle. vertebral arch the bony arch on the dorsal aspect of a vertebra, composed of the laminae and pedicles. zygomatic arch one formed by processes of zygomatic and temporal bones.
arch, any anatomic structure that is curved or has a bowlike appearance. Also called arcus. arch (pl. es), n a structure with a curved outline, such as bone. arch bar, n See bar, arch. arch, basal, n See base, apical. arch, branchial, n the small pouches that emerge during embryonic development on each side of the pharynx. Also known as the pharyngeal arches. arch, dental, n the composite structure of the dentition and alveolar ridge or the remains thereof after the loss of some or all of the natural teeth. arch, dental, contraction, n See contraction. arch, dentulous dental n a dental arch containing natural teeth. arch, edentulous dental n a dental arch from which all natural teeth are missing. Also called the residual alveolar ridge. arch expansion, n See expansion. arch form, See form, arch. arch, high labial, n a labial arch wire adapted so that it lies gingival to the anterior tooth crowns; it has auxiliary springs extending downward in contact with the teeth to be moved. arch, inferior dental, n See arch, lower. arch length, n the length of a dental arch, usually measured through the points of contact between adjoining teeth. arch length, available, n the space available for all teeth. arch length, deficiency, n the difference between required and available arch length. arch length, required, n the sum of the mesiodistal widths of all teeth. arch, lower, n the arch-like curve of the cutting edges and surfaces of the teeth on the mandible. Also known as the inferior dental arch. arch, ovoid, n an arch that curves continuously from the molars on one side to the molars on the opposite side so that two such arches placed back to back describe an oval. arch, palatine, n (glossopalatine arch), the pillars of the fauces; the two arches of mucous membrane enclosing the muscles at the sides of the passage from the oral cavity to the pharynx. arch, partially edentulous dental, n a dental arch from which one or more but not all teeth are missing. arch, passive lingual, n an orthodontic appliance effective in maintaining space and preserving arch length when bilateral primary molars are prematurely lost. arch, pharyngeal, n See arch, branchial. arch, removable lingual, n an arch wire designed to fit the lingual sur-face of the teeth. It has two posts soldered on each end that fit snugly into the vertical tubes of the molar anchor bands. arch, stationary lingual, n an arch wire designed to fit the lingual surface of the teeth and soldered to the anchor bands. arch, tapering, n a dental arch that converges from molars to central incisors to such an extent that lines passing through the central grooves of the molars and premolars intersect within 1 inch (2.5 cm) anterior to the central incisors. arch, trapezoidal n an arch that has the same convergence as a tapering arch but to a lesser degree. The anterior teeth are somewhat square to abruptly rounded from canine tip to canine tip. The canines act as corners of the arch. arch, U-shaped, n a dental arch in which there is little difference in diameter (width) between the first premolars and the last molars; the curve from canine to canine is abrupt, so a dental arch in the shape of a capital U is formed. arch width, n the width of a dental arch. The width, which varies in all diameters between the right and left opposites, is determined by direct measurement between the canines, between the first molars, and between the second premolars. These intercanine, interpremolar, and intermolar distances can be cited as arch width. arch wire, n a wire applied to two or more teeth through fixed attachments to cause or guide orthodontic tooth movement. arch wire, full, n a wire extending from the molar region of one side of an arch to the other. arch wire, sectional, n a wire extending to only a few teeth, usually on one side or in the anterior segment. arch a structure of bowlike or curved outline. arch of aorta the curving portion between the ascending and descending aorta, giving rise to the brachiocephalic trunk and, in some species, the left common carotid and the left subclavian artery. aortic a's paired vessels that run from the ventral to the dorsal aortae through the branchial arches of fishes and amniote embryos. In mammalian development, arches 1 and 2 disappear; 3 joins the common to become the internal carotid artery; 4 becomes the arch of the aorta and joins the aorta and subclavian artery; 5 disappears; 6 forms the pulmonary arteries and, until birth, the ductus arteriosus. arterial arch one or more arteries that form an anastomotic connection between two more or less parallel tributaries; found commonly around joints and other moveable parts. arch arteriosus, arcus arteriosus a large communicating branch between two arteries. branchial a's four pairs of mesenchymal and later cartilaginous columns in the pharyngeal wall which in fish develop into gills and in mammals become modified into structures of the ear and neck. branchial arch derivatives derivatives of the arches are first arch (mandible, ossicles), second arch (hyoid apparatus, ear ossicles), third arch (hyoid apparatus), fourth arch (laryngeal cartilages). costal arch the rim to the bony thorax formed by the conjoined asternal ribs and their connecting elastic tissue. cricoid arch the slender ventral half of the cricoid cartilage of the larynx. The most caudal of the palpable landmarks of the larynx. dental arch the curving structure formed by the crowns of the teeth in their normal position, or by the residual ridge after loss of the teeth. hemal arch the v- or y-shaped bone borne on the ventral surface of the tail vertebrae of some animals and which protects blood vessels. Called also chevron bone. hyoid arch the second branchial arch. ischial arch, ischiatic arch the caudal rim of the pelvis formed by the conjunction of the two ischiae. Called also sciatic arch. lumbocostal arch of the diaphragm the dorsal part of the diaphragm where it crosses the ventral surface of the psoas muscles. Here it is without any attachment and only serous membranes separate the thoracic and peritoneal cavities. mandibular arch the first branchial arch, being the rudiment of the maxillary and mandibular regions. neural arch the dorsal vertebral arch. palatal arch the arch formed by the roof of the mouth from the teeth on one side to those on the other. palatoglossal arch the thick fold of tissue passing from the soft palate to the lateral border of the tongue. palatopharyngeal arch a horizontal fold of pharyngeal mucosa that passes from the soft palate and joins with its opposite fold over the entrance to the esophagus. palmar arch a superficial and a deep vascular arch behind the carpus formed by the conjunction of several arteries of the forearm. pulmonary a's the most caudal of the embryonic aortic arches, which become the pulmonary arteries. sciatic arch ischial arch. subcarpal arch the deep palmar arch, especially of horses. superficial dorsal arch one of the arterial arches in the foot of carnivores. supracarpal arch the superficial palmar arch, especially of horses. tendinous arch a linear arched thickening of fascia that provides attachment for some muscles. terminal arch the union between the medial and lateral palmar digital arteries, which in horses runs through the solar canal within the distal phalanx. vertebral arch the dorsal bony arch of a vertebra, composed of paired laminae and pedicles. zygomatic arch the arch formed by the processes of the zygomatic and temporal bones that is the principal origin of the masseter muscle and is particularly broad and prominent in carnivores. 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