common tendinous ring

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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common tendinous ring,

the thickening of the periorbita around the optic canal and the central part of the superior orbital fissure in the posterior part of the bony orbit. It is the point of origin of the four rectus muscles.