THE CIRCULATION 217 



Aortic Valve. The anterior cusp is largest, and lies some- 

 what deeper in the heart than the others. At each side it 

 is attached to the aortic wall, but below it is attached to the 

 upper part of the septum ventriculi, so that the base of the 

 sinus of Valsalva is formed by the upper part of the 

 septum. At a somewhat higher level is a cusp which 

 is partly attached to the upper part of the septum, partly 



FIG. 108. Vertical Mesial Section through Heart to show Aortic and Mitral Valves. 

 R.V., Right Ventricle; L.V., Left < Ventricle with Papillary Muscle; L.A., 

 Left Auricle ; Ao. , Aorta with Anterior Cusp. 



to the posterior wall of the aorta, where this becomes con- 

 tinuous with the anterior cusp of the mitral. The third 

 cusp is still higher, and is attached to the aortic wall 

 where it becomes continuous with the anterior cusp of 

 the mitral. 



Pulmonary Yalve. The posterior cusp is mounted on the 

 top of the septum ventriculi, and is at a somewhat lower 

 level than the other two. 



Thus in each valve the cusp placed lowest is mounted on 



