Configuration of the Left Coronary Leaflet of the Aortic Valve on the Left Side Viewed Laterally

Description

Shown in lateral profile, the left coronary leaflet (left semilunar cusp, valvula semilunaris aortae) forms a crescentic curtain at the aortic root, its free margin projecting centrally toward the valve orifice while its basal attachment follows the fibrous aortic annulus. Immediately superior to the cusp lies the left aortic sinus (sinus of Valsalva), with the cusp body spanning between the commissures that tether it to adjacent semilunar leaflets. Anterior and posterior relationships are defined by the aortic root contour in section, with the sinus bulging outward relative to the thinner leaflet tissue. Orientation is lateral. This lateral configuration matters because the left coronary cusp and its sinus define the immediate neighborhood of the left coronary ostium, where coronary flow occurs in diastole and can be compromised by iatrogenic obstruction or malposition after aortic valve replacement or transcatheter aortic valve implantation. Subtle differences in cusp height, coaptation line, and sinus geometry also influence paravalvular leak risk and root hemodynamics, and they help explain why bicuspid aortic valve phenotypes often show eccentric closure lines and asymmetric sinus development. For teaching valve mechanics, the side view clarifies how semilunar cusps billow into the sinuses during systole and coapt along their free margins in diastole. Use this illustration in cardiothoracic surgery and interventional cardiology materials discussing aortic root anatomy, coronary ostial safety during TAVR planning, and the structural basis of aortic regurgitation. It also fits gross anatomy labs, echocardiography correlation (parasternal long-axis concepts), and pathology chapters covering cusp calcification and commissural fusion. Anatomical accuracy verified by SciePro's Medical Advisory Board.