| Kayser-Fleischer ring | A greenish yellow pigmented ring encircling the cornea just within the corneoscleral margin, seen in hepatolenticular degeneration, due to copper deposited in Descemet's membrane. Synonym: Fleischer-Strumpell ring. (05 Mar 2000) |
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| umbilical ring | An opening in the linea alba through which pass the umbilical vessels in the foetus; in young embryos it is relatively nearer to the pubis, but gradually ascends to the centre of the abdomen; it is closed in the adult, its site being indicated by the umbilicus or navel. Synonym: annulus umbilicalis, canalis umbilicalis. (05 Mar 2000) |
| Zinn's ring | A fibrous ring 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. Synonym: annulus tendineus communis, Zinn's ligament, Zinn's ring, Zinn's tendon. (05 Mar 2000) |
| femoral ring | 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 manoeuvre. Often occupied by a lymph node (Cloquet's) and is the site of femoral hernias. Synonym: annulus femoralis, crural ring. (05 Mar 2000) |
| fibrocartilaginous ring | Of tympanic membrane, the thickened portion of the circumference of the tympanic membrane that is fixed in the tympanic sulcus. Synonym: annulus fibrocartilagineus membranae tympani, Gerlach's annular tendon. (05 Mar 2000) |
| fibrous ring | One of four fibrous rings that surround atrioventricular and arterial orifices of the heart, providing attachment for the valve leaflets and maintaining patency of the orifice. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium. Synonym: annulus fibrosus cordis, annulus fibrosus, coronary tendon, fibrous ring, Lower's ring. (05 Mar 2000) |
| fibrous ring of heart | One of four fibrous rings that surround atrioventricular and arterial orifices of the heart, providing attachment for the valve leaflets and maintaining patency of the orifice. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium. Synonym: annulus fibrosus cordis, annulus fibrosus, coronary tendon, fibrous ring, Lower's ring. (05 Mar 2000) |
| fibrous ring of intervertebral disc | The ring of fibrocartilage and fibrous tissue forming the circumference of the intervertebral disc; surrounds the nucleus pulposus, which is prone to herniation when the annulus fibrosus is compromised. Synonym: annulus fibrosus disci intervertebralis, annulus fibrosus, fibrous ring of intervertebral disc, fibrous ring. (05 Mar 2000) |
| Fleischer's ring | An incomplete ring often present at the base of the keratoconus cone; it may be yellow or greenish from deposition of haemosiderin. (05 Mar 2000) |
| Fleischer-Strumpell ring | A greenish yellow pigmented ring encircling the cornea just within the corneoscleral margin, seen in hepatolenticular degeneration, due to copper deposited in Descemet's membrane. Synonym: Fleischer-Strumpell ring. (05 Mar 2000) |
| Flieringa's ring | A stainless steel ring sutured to the sclera to prevent collapse of the globe in difficult intraocular operations. (05 Mar 2000) |
| lateral crus of the superficial inguinal ring | Portion of the external oblique aponeurosis which passes lateral to the superficial inguinal ring blending into the inguinal ligament and forming the lateral boundary of the ring. Synonym: crus laterale anuli inguinalis superficialis. (05 Mar 2000) |
| furanose ring | <chemistry> A five-membered cyclic haemiacetal or hemiketal of a carbohydrate. (09 Jan 1998) |
| lesser ring of iris | The narrow inner zone of the iris. Synonym: annulus iridis minor. (05 Mar 2000) |
| Lower's ring | One of four fibrous rings that surround atrioventricular and arterial orifices of the heart, providing attachment for the valve leaflets and maintaining patency of the orifice. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium. Synonym: annulus fibrosus cordis, annulus fibrosus, coronary tendon, fibrous ring, Lower's ring. (05 Mar 2000) |