288 



CIRCULATORY APPARATUS. 



points which touch each other during the closure of the valve, 

 are always separated when it opens; but the inflamed valves no 



Fig. 90. 



Insufficiency and stenosis of the mitral valve. The valve is 

 converted into a rigid funnel, laid open at a ; the mnscnli 

 papillares have been cut away from the ventricular wall. 

 The cut surface at a shows the thickening of the flaps, 

 which is also seen in the background ; at a moreover there 

 is a nucleus of calcification. The chordfB tendineJB are 

 thickened and fused together; the muse, papillares indurated 

 and tendinous at their tips. 



longer, as a r 

 always begins 



Fig. 91. 



Adhesion of the 

 right and pos- 

 terior flaps of 

 the aortic valve. 

 At a the line 

 of union. The 

 valve is com- 

 petent, though 

 it consists of 

 only two flaps. 



ule, possess their full mobility; and adhesion 

 between those points which are least separated 

 during the opening of the valves. The coales- 

 cence of two neighbouring flaps takes place along 

 the " line of contact " from without inwards. In 

 the sigmoid valves of the aorta the fusion always 

 occurs first between the right and posterior flaps. 

 When once it has extended as far as the nodulus 

 Arantii, the partition between the adjacent sinuses 

 of Valsalva sinks down, and the two flaps are 

 fused into one ; this in some measure does the 

 work of both, unless otherwise prcA^ented by 

 tliickening and contraction (fig. 89). Fusion of 

 the curtains of the mitral, stands foremost as 

 regards frequency and mischievous effect. The 

 auriculo-ventricular orifice is thus gradually 

 narrowed from either side, till it finallv becomes 



