Heart. 



183 



Ostium 

 arterios. 



525, The Left Ostium auriculo-ventriculare s. venosum 



and CITterWSUn?, from above. After a dried specimen, natural size. 



The wall of the left ventricle, Ventriculus sinister, is, in the 

 adult, considerably thicker than that of the right. Its auriculo-ventricular 

 opening is guarded by the bicuspid or mitral valve, Valvula bicus- 

 pidalis s. mitralis, which consists of an anterior and a posterior segment. 

 Of the semilunar valves surrounding the orifice of the aorta, one is 

 placed to the right, one to the left and one posteriorly ; they are stronger 

 and thicker than those of the pulmonary artery, and the Noduli Arantii 

 are larger and more prominent. 



During the diastole the auricles and ventricles of the heart are 

 filled with blood, which, during the systole is again driven out. The 

 systole of both auricles is, as well as that of the ventricles, synchronous, 

 and the latter follows the former after a very short interval. During 

 the diastole the right heart is filled by the venous blood from the 

 Venae cavae and coronary veins, and during the systole it drives the 

 blood into the pulmonary artery. The left heart is filled during the 

 diastole with the arterial blood from the four pulmonary veins, and 

 during the systole drives the blood into the aorta. 



