cusp of cardiac valve

Sealing a heart valve when it closes is the work of its cusps. Each cardiac valve carries three of them, with one exception: the mitral valve has only two, which is the origin of its alternative name, the bicuspid valve. At the tip of each cusp lie nodules, thickenings that allow the free edges to meet more closely and form a tighter seal when the valve is shut. The cusp is therefore described as a part of the valve rather than as an independent structure, since its geometry is meaningful only in apposition to its neighbours. Three subordinate structures are recorded beneath this entry in the anatomical hierarchy, matching the three-cusp arrangement of the valves that have it, and the Latin form is given as cardiac valve cusp.