right and left fibrous rings of heart

right and left fi·brous rings of heart

(rīt left fī'brŭs ringz hahrt)
Two fibrous rings that surround the atrioventricular orifices of the heart, providing attachment for the atrioventricular valve leaflets and maintaining patency of the orifices. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium.
Synonym(s): anulus fibrosus (1) [TA] .