circle

circle (ser´kl)

1. A ring-shaped structure or group of structures. 2. A line or process with every point equidistant from the center.circellus; [L. circulus]
arterial c. of cerebrum an anastomotic "circle" of arteries (roughly pentagonal in outline) at the base of the brain, formed, sequentially and in anterior to posterior direction, by the anterior communicating artery, the two anterior cerebral, the two internal carotid, the two posterior communicating, and the two posterior cerebral arteries.circulus arteriosus cerebri [NA] , c. of Willis;
articular vascular c. an anastomosis of vessels encircling a joint. See articular vascular network.circulus articularis vasculosus [NA];
Baudelocque's uterine c. pathologic retraction ring
Carus' c. Carus' curve
cerebral arterial c. the roughly pentagonally shaped c. of vessels on the ventral aspect of the brain in the area of the optic chiasm, hypothalamus, and interpeduncular fossa. See c. of Willis.
closed c. a circuit for administration of an inhalation anesthetic in which there is complete rebreathing with carbon dioxide absorption.
defensive c. obsolete term for the addition of a secondary affection that limits or arrests the progress of the primary affection, as thought to occur when pneumothorax supervenes on pulmonary tuberculosis, the former having a therapeutic effect on the latter.
greater arterial c. of iris an arterial circle at the ciliary border of the iris.circulus arteriosus iridis major [NA];
Haller's c. 1. vascular c. of optic nerve 2. areolar venous plexus
Huguier's c. anastomosis around the isthmus of the uterus (junction of the cervix with the body) between the right and left uterine arteries.
least diffusion c. in the configuration of rays emerging from a spherocylindrical lens system, the place where diverging rays of the lens first forming a line image are balanced by converging rays of the second lens.
lesser arterial c. of iris an arterial circle near the pupillary margin of the iris.circulus arteriosus iridis minor [NA];
Pagenstecher's c. in the case of a freely movable abdominal tumor, the mass is moved throughout its entire range, its position at intervals being marked on the abdominal wall; when these points are joined, a c. is formed, the center of which marks the point of attachment of the tumor.
Ridley's c. circular sinus (1)
rolling c. a mechanism for the replication of circular DNA.
semi-closed c. a circuit for administration of an inhalation anesthetic in which partial rebreathing with carbon dioxide absorption is combined with loss from the circuit of a portion of respired gases through valves.
vascular c. 1. the c. around the mouth formed by the inferior and superior labial arteries; 2. areolar venous plexus
vascular c. of optic nerve a network of branches of the short ciliary arteries on the sclera around the point of entrance of the optic nerve.circulus vasculosus nervi optici [NA] , circulus arteriosus halleri, circulus zinnii, Haller's c. (1) , Zinn's corona, Zinn's vascular c;
venous c. of mammary gland areolar venous plexus
vicious c. 1. the mutually accelerating action of two independent diseases or phenomena, or of a primary and secondary affection; 2. the passage of food, after a gastroenterostomy, from the artificial opening through the intestinal loop by antiperistaltic action and back into the stomach again by the pyloric orifice, or the reverse.
c. of Willis arterial c. of cerebrum
Zinn's vascular c. vascular c. of optic nerve

 

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