CIRCULATION.] 



PHYSIOLOGY, 



69 



water will immediately fill the auricle and run over. 

 If you look at the membrane carefully as it comes 

 bulging up, you will notice that it is made up of three 

 pieces joined together as is shown in Fig. 9 (Iv, i, 

 Iv, 2, Iv, 3). These three pieces form the valve 

 between the right auricle and ventricle, called the 

 tricuspid; or three-peaked valve. Why it is so 



IS 



'i;- 



'MVj 



\\ 



nLVA 



ucr 



m.y.a 



Fig. 10,— View 0/ the Orifices of the Heart front below, the whole of the 



Ventricles having been cut away. 



R.A.V. right auriculo-ventricular orifice surrounded by the three flaps, 

 t.v.\, t.v. 2, ^.z/. 3, of the tricuspid valve ; these are stretched by weights 

 attached to the chorcUe tendineee. 



L.A.V. left auriculo-ventriculv orifice surrounded m same way by the 

 two flaps, m.v. i, m.v. 2, of mitral valve ; P. A. the orifice of pulmonary 

 arter- the semilunar valves having met and closed together ; Ao. the orifice 

 of the aorta with its semilunar valves. The shaded portion, leading from 

 R.A.V. to P. A,, represents the funnel seen in Fig. 8. 



