- 1. A circular band surrounding a wide central opening; a r.-shaped or circular structure surrounding an opening or level area. SYN: anulus [TA]. 2. The closed ( i.e., endless) chain of atoms in a cyclic compound; commonly used for “cyclic” or “cycle.” 3. A marginal growth on the upper surface of a broth culture of bacteria, adhering to the sides of the test tube in the form of a circle. SYN: annulus. [A.S. hring]- amnion r. the r. formed by the attachment of the amnion to the umbilical cord at its point of emergence from the umbilicus.- annuloplasty r. the dilated annulus is sutured, often to a prosthetic r., thereby reducing it to its normal systolic size.- benzene r. the closed-chain arrangement of the carbon and hydrogen atoms in the benzene molecule. SEE ALSO: cyclic compound.- common tendinous r. of extraocular muscles [TA] a fibrous r. that surrounds the optic canal and the medial part of the superior orbital fissure; it gives origin to the four rectus muscles of the eye and is partially fused with the sheath of the optic nerve. SYN: anulus of Zinn, anulus tendineus communis, Zinn ligament, Zinn r., Zinn tendon.- conjunctival r. [TA] a narrow r. at the junction of the periphery of the cornea with the conjunctiva. SYN: anulus conjunctivae [TA].- constriction r. 1. true spastic stricture of the uterine cavity resulting when a zone of muscle goes into local tetanic contraction and forms a tight constriction about some part of the fetus; 2. SYN: amnionic band.- deep inguinal r. [TA] the opening in the transversalis fascia through which the ductus deferens and gonadal vessels (or round ligament in the female) enter the inguinal canal. Located midway between anterior superior iliac spine and pubic tubercle, it is bounded medially by the lateral umbilical fold (inferior epigastric vessels) and inferiorly by the iliopubic tract. Indirect inguinal hernias exit the abdominal cavity via the deep inguinal r. SYN: anulus inguinalis profundus [TA], abdominal r., anulus abdominalis, internal inguinal r..- femoral r. [TA] the superior opening of the femoral canal, bounded anteriorly by the inguinal ligament, posteriorly by the pectineus muscle, medially by the lacunar ligament, and laterally by the femoral vein. Passageway by which many lymphatics from lower limb pass to abdomen. Accommodates enlargement of femoral vein in Valsalva maneuver. Often occupied by a lymph node (Cloquet) and is the site of femoral hernias. SYN: anulus femoralis [TA], crural r..- fibrocartilaginous r. of tympanic membrane [TA] the thickened portion of the circumference of the tympanic membrane that is fixed in the tympanic sulcus. SYN: anulus fibrocartilagineus membranae tympani [TA], Gerlach annular tendon.- fibrous r. 1. SYN: (right and left) fibrous rings of heart. 2. SYN: anulus fibrosus of intervertebral disk.- Fleischer r. an incomplete r. often present at the base of the keratoconus cone; it may be yellow or greenish from deposition of hemosiderin.- Fleischer-Strümpell r. SYN: Kayser-Fleischer r..- Flieringa r. a stainless steel r. sutured to the sclera to prevent collapse of the globe in difficult intraocular operations.- gestational r. the white r. identified by pulse echosonography that signals an early stage of pregnancy.- Graefenberg r. obsolete term for a silver or silkworm gut r. designed for insertion into the uterine cavity as a means of contraception.- Kayser-Fleischer r. a greenish yellow pigmented r. encircling the cornea just within the corneoscleral margin, seen in hepatolenticular degeneration, due to copper deposited in Descemet membrane. SYN: Fleischer-Strümpell r..- Liesegang rings colored rings of precipitated silver chromate formed when a drop of concentrated silver nitrate is added to the surface of a gel (such as gelatin, agar, or silica gel) containing potassium dichromate.- lymphatic r. of cardiac part of stomach SYN: lymph node s around cardia of stomach, under lymph node.- pathologic retraction r. a constriction located at the junction of the thinned lower uterine segment with the thick retracted upper uterine segment, resulting from obstructed labor; this is one of the classic signs of threatened rupture of the uterus.- pharyngeal lymphatic r. [TA] the broken r. of lymphoid tissue, formed of the lingual, faucial, and pharyngeal tonsils. SYN: anulus lymphoideus pharyngis [TA], Bickel r., tonsillar r., Waldeyer throat r..- physiologic retraction r. a ridge on the inner uterine surface at the boundary line between the upper and lower uterine segment that occurs in the course of normal labor.- polar r. a thickened, electron-dense r. at the anterior end of certain stages of the Apicomplexa; part of the apical complex characteristic of these sporozoans.- (right and left) fibrous rings of heart [TA] two fibrous rings that surround atrioventricular orifices of the heart, providing attachment for the atrioventricular valve leaflets and maintaining patency of the orifices. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium. SYN: anulus fibrosus (1) [TA], anulus fibrosus dexter/sinister cordis, coronary tendon, fibrous r. (1), Lower r..- Schatzki r. a contraction r. or incomplete mucosal diaphragm in the lower third of the esophagus, which is occasionally symptomatic.- scleral r. the appearance of the sclera adjacent to the optic disk when the retinal pigment epithelium does not extend to the optic nerve.- signet r. the early stage of trophozoite development of the malaria parasite in the red blood cell; the parasite cytoplasm stains blue around its circular margin, and the nucleus stains red in Romanowsky stains, while the central vacuole is clear, giving the ringlike appearance.- r. of Soemmerring a mass of lenticular fibers enclosed between the anterior and posterior portion of the lenticular capsule, leaving the pupillary area relatively free.- superficial inguinal r. [TA] the slitlike opening in the aponeurosis of the external oblique muscle of the abdominal wall through which the spermatic cord (round ligament in the female) and inguinal hernias emerge from the inguinal canal. SEE ALSO: aponeurosis of external oblique muscle. SYN: anulus inguinalis superficialis, external inguinal r., subcutaneous r..- tympanic r. [TA] in the fetus, a more or less complete bony r. at the medial end of the cartilaginous external acoustic meatus, to which is attached the tympanic membrane. SYN: anulus tympanicus, tympanic bone.- umbilical r. [TA] an opening in the linea alba through which pass the umbilical vessels in the fetus; in young embryos it is relatively nearer to the pubis, but gradually ascends to the center of the abdomen; it is closed in the adult, its site being indicated by the umbilicus or navel. SYN: anulus umbilicalis, canalis umbilicalis.- vascular r. anomalous arteries (aortic arches) congenitally encircling the trachea and esophagus, at times producing pressure symptoms.- Vieussens r. SYN: limbus fossae ovalis.- Vossius lenticular r. a r.-shaped opacity found on the anterior lens capsule after contusion of the eye, due to pigment and blood.
* * *ring 'riŋ n1 a) a circular bandb) an anatomical structure having a circular opening: ANNULUS2) an arrangement of atoms represented in formulas or models in a cyclic manner as a closed chain called also cyclering vi, rang 'raŋ; rung 'rəŋ; ring·ing 'riŋ-iŋ to have the sensation of being filled with a humming sound <his ears rang>
* * *n.
* * *(ring) [from A.S. hring;] 1. any annular or circular organ or area; for names of specific anatomical structures, see under anulus. See also circle and circulus. 2. in chemistry, a collection of atoms united in a continuous or closed chain.
Medical dictionary. 2011.