- Any structure resembling a bent bow or an a.; an arc. In anatomy, any vaulted or archlike structure. See arcus. SYN: arcus [TA]. [thru O. Fr. fr. L. arcus, bow]- abdominothoracic a. a bell-shaped line defined by the lower end of the sternum and the costal arches on each side, constituting a boundary line between the anterolateral portions of the thoracic and abdominal walls.- alveolar a. of mandible [TA] the free margin of the alveolar process of the mandible. SYN: arcus alveolaris mandibulae [TA], limbus alveolaris (1).- alveolar a. of maxilla [TA] the free border of the alveolar process of the maxilla. SYN: arcus alveolaris maxillae [TA], limbus alveolaris (2).- anterior a. of atlas [TA] an a. that connects the lateral masses of the atlas anteriorly and articulates with the anterior articular facet of the dens of the axis. SYN: arcus anterior atlantis [TA].- aortic a. 1. the curved portion between the ascending and descending parts of the aorta; it begins as a continuation of the ascending aorta posterior to the sternal angle, runs posteriorly and slightly to the left as it passes over the root of the left lung, and becomes the descending aorta as it reaches and begins to course along the vertebral column; it gives rise to the brachiocephalic trunk, the left common carotid and left subclavian arteries; SYN: a. of the aorta. 2. any member of the several pairs of arterial channels encircling the embryonic pharynx in the mesenchyme of the brachial arches; there are potentially six pairs, but in mammals the fifth pair is poorly developed or absent. The first and second pairs are functional only in very young embryos; the third pair is involved in the formation of the carotids; the fourth a. on the left is incorporated in the a. of the aorta; the sixth pair forms the proximal part of the pulmonary arteries. SYN: arcus aortae.- aortic arches a series of arterial channels encircling the embryonic pharynx in the mesenchyme of the branchial arches. There are potentially six pairs, but in mammals the fifth pair is poorly developed or absent. The first and second pairs are functional only in very young embryos; the third pair is involved in the formation of the carotids; the fourth a. on the left is incorporated in the a. of the aorta; the sixth pair forms the proximal part of the pulmonary arteries.- arterial arches of colon anastomoses between adjacent branches of the colic arteries that form arches in the mesocolon from which the walls of the colon are supplied. When these form a continuous paracolic artery, it is referred to as the marginal artery of the colon. See marginal artery of colon.- arterial arches of ileum arches formed in the mesentery by branches of the superior mesenteric artery from which vessels (vasa recta, under vas) arise to supply the wall of the ileum. SEE ALSO: intestinal arterial arcades, under arcade.- arterial arches of jejunum arches formed in the mesentery by branches of the superior mesenteric artery from which vessels (vasa recta, under vas) arise to supply the walls of the jejunum. SEE ALSO: intestinal arterial arcades, under arcade.- axillary a. SYN: pectorodorsalis muscle.- branchial arches typically, 6 arches in vertebrates; in the lower vertebrates, they bear gills; in the higher vertebrates, they appear transiently and give rise to specialized structures in the head and neck. SYN: pharyngeal arches, visceral arches.- carpal arches two anastomotic arterial twigs running transversely across the wrist : the palmar or anterior lies in front of the carpus, being formed by palmar carpal branches of the radial and ulnar arteries; the dorsal or posterior lies on the dorsal surface of the carpus, being formed by the dorsal carpal branches of the radial and ulnar arteries.- coracoacromial a. a protective a. formed by the smooth inferior aspect of the acromion and the coracoid process of the scapula with the coracoacromial ligament spanning between them. This osseoligamentous structure overlies the head of the humerus, preventing its upward displacement from the glenoid fossa.- cortical arches of kidney the portions of renal substance (cortex) intervening between the bases of the pyramids and the capsule of the kidney.- a. of cricoid cartilage [TA] the narrow part of the cartilage that encircles the air passage anterior to the lamina. SYN: arcus cartilaginis cricoideae [TA].- deep palmar (arterial) a. [TA] the arterial a. located deep to the long flexor tendons in the hand. It is formed by the terminal part of the radial artery in conjunction with the deep palmar branch of the ulnar artery. The a. gives rise to palmar metacarpal and princeps pollicis arteries. SYN: arcus palmaris profundus, arcus volaris profundus.- deep palmar venous a. [TA] the venous a. that accompanies the deep palmar arterial a.; it usually consists of paired venae comitantes. SYN: arcus venosus palmaris profundus [TA].- dental a. the curved composite structure of the natural dentition and the residual ridge, or the remains thereof after the loss of some or all of the natural teeth.- dorsal carpal arterial a. [TA] a vascular network over the dorsal surface of the carpal joints, formed by anastomoses of branches of the anterior and posterior interosseous, and dorsal carpal branches of the radial and ulnar arteries. SYN: rete carpale dorsale [TA], dorsal carpal network, rete carpi posterius.- dorsal venous a. of foot [TA] the a. in the subcutaneous tissue of the dorsum of the foot formed by the dorsal and digital veins; it unites medially with the dorsal vein of the great toe to form the great saphenous vein, and laterally with the dorsal vein of the little toe to form the small saphenous. SYN: arcus venosus dorsalis pedis [TA].- double aortic a. congenital malformation of the aorta that splits and has a right and a left a. instead of a single a..- expansion a. an orthodontic appliance that moves the dental structures distally, bucally, or labially, creating increased molar to molar width and a. length.- fallen arches a breaking down of the arches of the foot, either longitudinal, transverse, or both; the resulting deformity is flat (longitudinal) or splay (transverse) foot, or both.- glossopalatine a. SYN: palatoglossal a..- hemal arches 1. the arches that collectively comprise the thoracic cage, each consisting of a vertebra (body, pedicle, and transverse processes), the corresponding pair of ribs and their articular cartilages, and the portion of the sternum to which they attach. 2. three or four V-shaped bones located ventral to the bodies of the third to sixth coccygeal vertebrae; they represent intercentra and usually enclose the ventral caudal artery and vein.- iliopectineal a. [TA] a thickened band of fused iliac and psoas fascia passing from the posterior aspect of the inguinal ligament anteriorly across the front of the femoral nerve to attach to the iliopectineal eminence of the hip bone posteriorly. The iliopectinal a. thus forms a septum which subdivides the space deep to the inguinal ligament into a lateral muscular lacunae and a medial vascular lacunae. When a psoas minor muscle is present, its tendon of insertion blends with the iliopectineal a.. SYN: arcus iliopectineus [TA], iliopectineal ligament, ligamentum iliopectineale.- inferior palpebral (arterial) a. [TA] formed by the medial palpebral artery, which communicates with a branch of the lacrimal artery along the tarsal margin. SYN: arcus palpebralis inferior [TA], arterial a. of lower eyelid.- jugular venous a. [TA] a connecting vein between the two anterior jugular veins in the suprasternal space. SYN: arcus venosus juguli [TA].- Langer a. SYN: pectorodorsalis muscle.- lateral longitudinal a. of foot formed by calcaneus, cuboid, and two lateral metatarsals; the combined a. is supported normally by ligaments, intrinsic muscles, and the tendons of extrinsic muscles of the foot. SYN: arcus pedis longitudinalis pars lateralis.- longitudinal a. of foot See medial longitudinal a. of foot, lateral longitudinal a. of foot. SYN: arcus pedis longitudinalis.- medial longitudinal a. of foot formed by the calcaneus, talus, navicular, three cuneiform bones, and the three medial metatarsals. SYN: arcus pedis longitudinalis pars medialis.- nasal a. bridge of the nose, the upward arching roof of the piriform aperture formed by the nasal processes of the maxilla of each side and the nasal bones between them. Eyeglasses rest centrally on various portions of this a..- nasal venous a. an a. formed at the root of the nose by the two supratrochlear veins connected by a transverse vein.- palatoglossal a. [TA] one of a pair of ridges or folds of mucous membrane passing from the soft palate to the side of the tongue; it encloses the palatoglossus muscle and forms the anterior margin of the tonsillar fossa. Also demarcates the oral cavity from the isthmus of fauces. SYN: arcus palatoglossus [TA], anterior pillar of fauces, plica anterior faucium, anterior palatine a., arcus glossopalatinus, glossopalatine a., glossopalatine fold.- palatopharyngeal a. [TA] one of a pair of ridges or folds of mucous membrane that pass downward from the posterior margin of the soft palate to the lateral wall of the pharynx. It encloses the palatopharyngeus muscle and forms the posterior margin of the tonsillar fossa. It also demarcates the isthmus of fauces from the oropharynx. SYN: arcus palatopharyngeus [TA], plica posterior faucium, posterior pillar of fauces, pharyngopalatine a., posterior palatine a..- plantar venous a. [TA] the a. formed by the plantar digital veins from the toes, which accompanies the plantar arterial a.. SYN: arcus venosus plantaris [TA].- posterior a. of atlas [TA] the posterior a. of the atlas that connects the lateral masses of the atlas posteriorly, forming the posterior wall of the vertebral canal at this level. SYN: arcus posterior atlantis [TA].- postoral arches the series of branchial arches caudal to the mouth; the first is the mandibular, the second is the hyoid; caudal to the hyoid, the arches are unnamed, and designated only by their postoral number.- primitive costal arches arches formed in the thoracic region of the vertebral column in the embryo from the costal processes or costal elements which give rise to the ribs.- pubic a. [TA] the a. formed by the symphysis, bodies, and inferior rami of the pubic bones. SEE ALSO: subpubic angle. SYN: arcus pubis [TA].- ribbon a. a thin, ribbon-shaped, rectangular orthodontic a. wire applied to the dental arches so that its widest dimension is parallel to the labial or buccal surfaces of the teeth.- superciliary a. [TA] a fullness extending laterally from the glabella on either side, above the orbital margin of the frontal bone. SYN: arcus superciliaris [TA], superciliary ridge.- superficial palmar (arterial) a. [TA] the arterial a. in the hand located superficial to the long flexor tendons approximately at the level of a line extrapolated across the palm from the distal side of the outstretched thumb. It is formed principally by the termination of the superficial ulnar artery and is usually completed by a communication with the superficial palmar branch of the radial artery. The a. gives rise to the common palmar digital arteries. SYN: arcus palmaris superficialis [TA], arcus volaris superficialis.- superficial palmar venous a. [TA] the venous a. accompanying the superficial palmar arterial a.; it consists usually of paired venae comitantes and is drained by the superficial ulnar and radial veins. SYN: arcus venosus palmaris superficialis [TA].- superior palpebral (arterial) a. [TA] formed by communicating branches of the medial and lateral palpebral arteries. Often two arches are present, one located near the free border of the tarsal plate, the other along the upper border of the tarsus. SYN: arcus palpebralis superior [TA], arterial a. of upper eyelid.- tendinous a. [TA] 1. a white, fibrous band attached to bone and/or muscle, arching over and thus protecting neurovascular elements passing beneath it from injurious compression; 2. a linear thickening of the deep fascia of a muscle which provides attachment for ligaments and/or muscle fibers. SYN: arcus tendineus [TA].- tendinous a. of levator ani muscle [TA] a thickened portion of the obturator fascia that extends in an arching line from the pubis posteriorly to the ischial spine and gives origin to part of the levator ani muscle. SYN: arcus tendineus musculi levatoris ani [TA], arcus tendineus of obturator fascia, arcus tendineus of pelvic diaphragm.- tendinous a. of pelvic fascia [TA] a linear thickening of the superior fascia of the pelvic diaphragm extending posteriorly from the body of the pubis alongside the bladder (and vagina in the female) and giving attachment to the supporting ligaments of the pelvic viscera. SYN: arcus tendineus fasciae pelvis [TA].- tendinous a. of soleus muscle [TA] a tendinous a. stretching over—and defining the termination of—the popliteal vessels between the tibia and fibula, which gives origin to the central portion of the soleus muscle. SYN: arcus tendineus musculi solei [TA].- a. of thoracic duct [TA] terminal portion of thoracic duct that turns abruptly to the left, usually at the C7 vertebral level, to enter the superolateral aspect of the junction of the left subclavian and internal jugular veins. SEE ALSO: thoracic duct. SYN: arcus ductus thoracici [TA].- transverse a. of foot the a. formed by the proximal parts of the metatarsal bones, the three cuneiform bones, and the cuboid. SYN: arcus pedis transversalis.- Treitz a. SYN: paraduodenal fold.- vertebral a. [TA] the posterior projection from the body of a vertebra that encloses the vertebral foramen; it consists of paired pedicles and laminae; the spinous, transverse, and articular processes arise from the a.. In aggregate, the venous arches—and the ligamenta flava that unite them—form the posterior wall of the vertebral (spinal) canal. SYN: arcus vertebrae [TA], neural a. of vertebra.- W-a. a fixed maxillary expansion device attached to the lingual part of the molars, with either bilateral or unilateral extension arms.- zygomatic a. [TA] the a. formed by the temporal process of the zygomatic bone that joins the zygomatic process of the temporal bone. SYN: arcus zygomaticus [TA], cheek bone (2), malar a., zygoma (2).* * *Amiodarone Reduces Coronary Artery Bypass Grafting Hospitalization [trial]; automated record for child health
* * *arch 'ärch n1) an anatomical structure that resembles an arch in form or function: asa) either of two vaulted portions of the bony structure of the foot that impart elasticity to it: (1) a longitudinal arch supported posteriorly by the basal tuberosity of the calcaneus and anteriorly by the heads of the metatarsal bones (2) a transverse arch consisting of the metatarsals and first row of tarsals and resulting from elevation of the central anterior portion of the median longitudinal archb) ARCH OF THE AORTA2) a fingerprint in which all the ridges run from side to side and make no backward turn
* * *(ahrch) [L. arcus bow] a structure with a curved or bowlike outline. arcual adj
For specific anatomic structures not listed here, see under arcus.
Medical dictionary. 2011.