Fibrous trigones

The fibrous trigones are dense fibrous structures that anchor the aortic-mitral curtain to the ventricular myocardium at either end of the area of fibrous continuity between the mitral and aortic valves. There are two fibrous trigones: the left fibrous trigone and the right fibrous trigone.

The right fibrous trigone is continuous with the membranous septum, and together they form the central fibrous body, which is the most substantial component of the cardiac fibrous skeleton. The penetrating portion of the atrioventricular conduction axis (bundle of His) passes through the atrioventricular component of the membranous septum within this central fibrous body.

The fibrous trigones are part of the larger fibrous skeleton of the heart, which is concentrated at the base of the ventricular mass and serves critical functions including providing electrical insulation at the atrioventricular level and fibrous continuity for the leaflets of the mitral, aortic, and tricuspid valves.