THE VALVES OF THE HEART 



49 



poured into the upper ends of the vessel will cause its 

 valves to close tightly, and allow nothing to flow out after 

 the first moment. 



Thus the arrangement of the auriculo-ventricular valves 

 is such, that any fluid contained in the chambers of the 

 heart can be made to pass through the auriculo-ventricular 

 apertures in one direction only : tliat is to say, from the 

 auricles to the ventricles. On the other hand, the arrange- 

 ment of the semilunar valves is such that the fluid con- 



FiG. 18.— View of the Orifices of the Heart from below, the whole 

 OF THE Ventricles having been cut away. 



R.A. V. riglit auriculo-ventricuhr orifice surrouuded bv the three flaps 

 t.v. 1 t.i-. 2, t.r. 3, of the tricuspid valve ; these are stretched bv weiehts 

 attached to the chorda tuadinfiK. ' 



I. A. r. left auriculo-ventricular orifice surrounded in same wav bv the 

 two flaps, m.v. 1, m.v. 2, of mitral valve ; P.A. the orifice of pulmonarv 

 artery, the semilunar valves having: met and closed together • Ao the 

 orifice of the aorta with its semilunar vahes. The shaded portion 

 leading from K.A. V. to P. A., represents the funnel seen in Fig 16 



