Aortic valve annulus (anatomy)

The aortic valve annulus is part of the fibrous skeleton of the heart. It functions to support the valve and root of the aorta against the high pressures resulting from left ventricular systole. It consists of a ring of collagenous tissue that surrounds and supports the aortic orifice.

The annulus is arranged as three arches. The distal parts of each arch blend with the fibro-elastic tissue of the aortic sinuses. The part of each arch that faces the lumen of the aorta blends with the lamina fibrosa of the valve leaflets.

The proximal part of each arch shows a collagenous thickening at its most inferior point:

• anterior arch: the least thickened of the arches; connects with the tendon of the infundibulum to provide a link with the pulmonary valve fibrous skeleton
• left arch: forms the left fibrous trigone
• right arch: forms the right fibrous trigone

Inferior to the arches of the annulus are fibrous extension which merge with inferior structures. These include the:

• anterior sheet of fibrous tissue between the fibrous annuli of the anterior and left posterior aortic valve leaflets; this merges with the tendon of the infundibulum
• subaortic curtain
• pars membranacea septi