| 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) |
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| 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) |
| 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) |
| L ring | <microbiology> Outermost ring of the basal part of the bacterial flagellum in gram-negative bacteria. It may serve as a bush to anchor the flagellum relative to the lipopolysaccharide layer. (18 Nov 1997) |
| lymphatic ring of cardiac part of stomach | A group of lymph nodes surrounding the cardia of the stomach. Synonym: annulus lymphaticus cardiae, cardiac lymphatic ring. (05 Mar 2000) |
| lymphoid ring | The broken ring of lymphoid tissue, formed of the lingual, faucial, and pharyngeal tonsils. Synonym: Bickel's ring, tonsillar ring, Waldeyer's throat ring. (05 Mar 2000) |