ring (redirected from Fibrous rings of heart)

ring (ring)

1. any annular or circular organ or area.

2. in chemistry, a collection of atoms united in a continuous or closed chain.

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Albl's ring  a ring-shaped shadow in radiographs of the skull, caused by aneurysm of a cerebral artery.

Bandl's ring  pathologic retraction r.; see retraction r.

benzene ring  the closed hexagon of carbon atoms in benzene, from which different benzene compounds are derived by replacement of hydrogen atoms.

Benzene ring structure represented as a hybrid of two possible ring structures; sometimes called a resonance hybrid.

Cannon's ring  a focal contraction seen radiographically at the mid-third of the transverse colon, marking an area of overlap between the superior and inferior nerve plexuses.

common tendinous ring  the annular ligament of origin common to the recti muscles of the eye, attached to the edge of the optic canal and the inner part of the superior orbital fissure.

conjunctival ring  a ring at the junction of the conjunctiva and cornea.

constriction ring  a contracted area of the uterus, where the resistance of the uterine contents is slight, as over a depression in the contour of the fetus, or below the presenting part.

femoral ring  the abdominal opening of the femoral canal, normally closed by the crural septum and peritoneum.

fibrous rings of heart  see anulus fibrosus (1).

greater ring of iris  the less coarsely striated outer concentric circle on the anterior surface of the iris.

inguinal ring, deep  an aperture in the transverse fascia for the spermatic cord or the round ligament.

inguinal ring, superficial  an opening in the aponeurosis of the external oblique muscle for the spermatic cord or the round ligament.

Kayser-Fleischer ring  a gray-green to red-gold pigmented ring at the outer margin of the cornea, seen in progressive lenticular degeneration and pseudosclerosis.

Landolt's rings  broken rings used in testing visual acuity.

lesser ring of iris  the more coarsely striated inner concentric circle on the anterior surface of the iris.

mitral ring  see anulus fibrosus.

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 r.), or a persistent retraction ring in abnormal or prolonged labor that obstructs expulsion of the fetus (pathologic retraction r.) .

Schwalbe's ring  a circular ridge composed of collagenous fibers surrounding the outer margin of Descemet's membrane.

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.

tracheal rings  tracheal cartilages: the 16 to 20 incomplete rings which, held together and enclosed by a strong, elastic, fibrous membrane, constitute the wall of the trachea.

tricuspid ring  see anulus fibrosus.

tympanic ring  the bony ring forming part of the temporal bone at birth and developing into the tympanic plate.

umbilical ring  the aperture in the fetal abdominal wall through which the umbilical cord communicates with the fetus.

vascular ring  a developmental anomaly of the aortic arch wherein the trachea and esophagus are encircled by vascular structures, many variations being possible.

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ring (rng)

n.

1. A circular object, form, or arrangement with a vacant circular center.

2. The area between two concentric circles; annulus.

3. A group of atoms linked by bonds that may be represented graphically in circular or triangular form.

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ring

1. any annular or circular organ, structure or area.

2. in chemistry, a collection of atoms united in a continuous or closed chain.

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abdominal ring (external)

an opening in the aponeurosis of the external oblique muscle for the spermatic cord or round ligament. Called also external inguinal ring.

abdominal ring (internal)

an aperture in the transverse fascia for the spermatic cord or round ligament. Called also internal inguinal ring.

Bandl's ring

see bandl's rings.

ring cell

an immature granulocyte, intermediate between the myelocyte and metamyelocyte, found in the bone marrow of rats. There is a 'hole' in the nucleus.

ciliary ring

the posterior part of the ciliary body of the eye, a continuation of the choroid.

conjunctival ring

a ring at the junction of the conjunctiva and cornea.

constriction ring

a contracted area of the uterus, where the resistance of the uterine contents is slight, as over a depression in the contour of the fetus, or below the presenting part.

deep inguinal ring

an aperture in the transverse fascia for the spermatic cord or the round ligament.

docking ring

see elastrator.

femoral ring

the abdominal opening of the femoral canal through which the femoral nerve and blood vessels pass from the peritoneal cavity to the limb.

inguinal ring

see abdominal ring (above).

pancreatic ring

the ring in the pancreas that accommodates the portal vein.

ring precipitin test

see precipitin reaction.

preputial ring

the rim of the external orifice of the prepuce proper, the internal prepuce, on the penis of the horse.

retraction ring

the demarcation between the upper, contracting portion of the uterus in normal parturition and the lower, dilating part.

retraction ring (pathological)

a complication of prolonged labor marked by failure of relaxation of the circular fibers at the internal opening of the cervix, obstructing delivery of the fetus.

Schwalbe's ring

see schwalbe's ring.

scleral ring

see ring of ossicles.

stallion ring

a rubber ring fitted over the glans penis of the stallion which discourages erection and masturbation.

superficial inguinal ring

a fissure-like opening in the aponeurosis of the external abdominal oblique muscle for the spermatic cord or the round ligament.

ring test

see ascoli test.

tympanic ring

the bony ring forming part of the temporal bone at birth and developing into the tympanic plate.

umbilical ring

the orifice in the abdominal wall of the fetus for transmission of the umbilical vein and arteries.

ring vaccination

vaccination of all animals in a zone around an area in which the subject disease occurs. A preventive strategy that contains the infected population so that the eradication team has a finite target.

vascular ring

any of a number of congenital anomalies of the aortic arch and its branches, the vessels forming a ring about the trachea and esophagus that cause varying degrees of compression, vomiting and esophageal dilatation. See also persistent right aortic arch.