Noncoronary Leaflet of the Aortic Valve Visible in Transverse Section

Description

Centered in a transverse section through the cardiac base, the aortic root sits anterior to the left atrium and just superior to the left ventricular outflow tract. The noncoronary leaflet (posterior semilunar cusp) occupies the posterior aspect of the aortic valve ring, opposite the right and left coronary leaflets, and it lies closest to the interatrial septum and the anterior wall of the left atrium. A smooth free margin and thin lunula are implied at the coaptation edge, with the fibrous annulus framing the cusp at its base. Posteriorly, this cusp is nonadjacent to a coronary ostium, while the ascending aorta continues superiorly from the sinotubular junction. That posterior relationship is why this cusp matters clinically. The noncoronary sinus abuts the atrial septum, so aortic root pathology, such as a sinus of Valsalva aneurysm or perivalvular abscess in infective endocarditis, can extend toward the left atrium or involve the membranous septal region with conduction disturbance risk. Transverse anatomy also helps when teaching why transcatheter aortic valve replacement sizing focuses on annular geometry, commissural alignment, and the sinotubular junction, even though only two cusps carry coronary ostia. Use this artwork for cardiothoracic surgery texts discussing aortic valve anatomy, for echocardiography and CT correlation in aortic stenosis modules, or for pathology teaching sets comparing cusp thickening patterns and commissural fusion in bicuspid variants versus tricuspid valves. Clean, label-friendly edges make it suitable for board-style questions on semilunar valve orientation. Anatomical accuracy verified by SciePro's Medical Advisory Board.