Albl's ring, a ring-shaped shadow observed in a radiograph of the skull, caused by an aneurysm of a cerebral artery.
amnion ring, the attached margin of the amnion about the umbilicus of the fetus.
annular rings, round or oval opacities surrounding a translucent area in a radiograph of the lung, indicative of cavitation in pulmonary tuberculosis. Called also pleural rings.
atrial ring, the ring surrounding the opening between the atrium and ventricle of the primitive vertebrate heart; represented in the mammalian heart by the atrioventricular node.
atrioventricular rings, atrioventricular valve rings,
Balbiani's rings, a series of loops of the chromonemata of polytene chromosomes, similar in nature to chromosome puffs and in appearance to lampbrush chromosomes.
Bandl's ring, pathologic retraction
benzene ring, the closed hexagon of carbon atoms in benzene (C6H6), from which the different benzene compounds are derived by replacement of the hydrogen atoms.
Bickel's ring, Waldeyer's tonsillar
Cabot's rings, Cabot's ring bodies
Cannon's ring, in the radiograph after a barium meal, a narrow area or focal contraction at the mid-third of the transverse colon, representing the junction of the primitive midgut and hindgut and marking an area of overlap between the superior and inferior nerve plexuses.
carbocyclic ring, a chemical ring that includes only carbon atoms.
cardiac lymphatic ring, anulus lymphaticus cardiae.
Carpentier ring, a semi-rigid prosthetic ring used in annuloplasty to restore competence to a regurgitant cardiac valve.
casting ring, 1. a cylinder used as a container for the investment and mold during the process of casting. 2. refractory flask.
ciliary ring, orbiculus ciliaris.
common tendinous ring, anulus tendineus communis.
conjunctival ring, anulus conjunctivae.
constriction ring, a contracted area of the uterus, allegedly possible at any level, occurring where the resistance of the uterine contents is slight, as over a depression in the contour of the fetal body, or below the presenting part.
contact ring, the wound inflicted at the site of entrance of a bullet on the surface of the body.
crural ring, anulus femoralis.
Döllinger's tendinous ring, thickening of Descemet's membrane, forming an elastic ring around the limbus.
Duran ring, a flexible prosthetic ring used in annuloplasty to restore competence to a regurgitant cardiac valve.
esophageal ring, an annular constriction of the lower esophagus, usually at the junction of the esophageal and gastric mucosa. Called also Schatzki's
femoral ring, anulus femoralis.
fibrocartilaginous ring of tympanic membrane, anulus fibrocartilagineus membranae tympani.
fibrous ring, interpubic, discus interpubicus.
fibrous rings of heart, see anulus fibrosus dexter/sinister cordis.
fibrous ring of intervertebral disk, anulus fibrosus disci intervertebralis.
Fleischer ring, an incomplete annular pigmented line at the base of the cone in keratoconus.
Fleischer-Strümpell ring, Kayser-Fleischer
germ ring, the proliferating marginal zone of the early blastoderm that is about to become the lips of the blastopore.
glaucomatous ring, a light yellowish ring around the optic disk in glaucoma, indicating atrophy of the choroid.
heterocyclic ring, a chemical ring that includes atoms of different elements.
homocyclic ring, a chemical ring in which all the members are atoms of the same element.
inguinal ring, deep, anulus inguinalis profundus.
inguinal ring, external, anulus inguinalis superficialis.
inguinal ring, internal, anulus inguinalis profundus.
inguinal ring, superficial, anulus inguinalis superficialis.
ring of iris, greater, anulus iridis major.
ring of iris, lesser, anulus iridis minor.
isocyclic ring, homocyclic
Kayser-Fleischer ring, a golden brown or green discoloration at the level of Descemet's membrane in the limbic region of the cornea seen in Wilson's disease and other liver disorders.
Landolt's rings, broken rings used in testing of visual acuity, the width of the ring and the break in its continuity each being one-fifth of its overall diameter; the observer is to identify the orientation of the break, with the ability to identify a break subtending 1 minute of arc corresponding to 20/20 vision.
Liesegang rings, concentric laminations due to deposition of calcium, such as occur within some tumors or other lesions.
Löwe's ring, a ring in the visual field caused by the macula retinae.
Lower's rings, see anulus fibrosus dexter/sinister cordis.
lymphoid ring, Waldeyer's tonsillar
Maxwell's ring, a ring resembling Löwe's, but smaller and fainter.
mitral ring, mitral valve ring, see anulus fibrosus dexter/sinister cordis.
neonatal ring, see neonatal line, under line.
Ochsner's ring, a circular mucosal thickening at the opening of the pancreatic duct into the common bile duct.
periosteal bone ring, see under collar.
pleural rings, annular r's.
polar ring, an electron-dense, annular, anterior thickening of the pellicle of apicocomplexan protozoa, occurring at some stage in the life cycle, and forming part of the apical complex. Called also apical ring.
retraction ring, a ringlike thickening and indentation occurring in normal labor at the junction of the isthmus and corpus uteri, delineating the upper contracting portion and the lower dilating portion (physiologic retraction ring), or a persistent retraction ring in abnormal or prolonged labor that obstructs expulsion of the fetus (pathologic retraction ring).
pelvic ring, pelvis ossea.
Schatzki's ring, esophageal ring.
Schwalbe's ring, Schwalbe's anterior border ring, a circular ridge composed of collagenous fibers surrounding the outer margin of Descemet's membrane (lamina limitans posterior corneae).
scleral ring, a white ring seen adjacent to the optic disk in ophthalmoscopy when the retinal pigment epithelium and choroid do not extend to the disk.
sewing ring, a cloth-covered ring surrounding an artificial cardiac valve and used for securing the valve in position.
signet ring, ring form.
Soemmering's ring, 1. a doughnut-shaped remnant of lens behind the pupil, occurring after cataract surgery or secondary to trauma as a result of contact between the anterior capsule and the posterior capsule, which traps varying amounts of lens substance peripherally; called also Soemmering's ring cataract. 2. a developmental cataract in which the primary lens cells fail to develop or are absorbed during intrauterine disease. Later developing subcapsular cells, having no fetal nucleus around which to grow, form doughnut-shaped ring cataracts.
tracheal rings, cartilagines tracheales.
tympanic ring, anulus tympanicus.
umbilical ring, anulus umbilicalis.
vascular ring, any of various developmental anomalies in which the aortic arches encircle the trachea and esophagus, sometimes compressing them.
ring of Vieussens, limbus fossae ovalis.
Vossius' ring, a ring of pigment on the lens caused by pressure of the pupillary margin against the lens following a contusion.
Waldeyer's tonsillar ring, the circular series of lymphoid tissue formed by the lingual, pharyngeal, and faucial tonsils. Called also Bickel's ring and lymphoid ring.
Zinn's ring, anulus tendineus communis.