io8 



THORAX 



therefore they remain quiescent during the contraction of the 

 ventricle and, as a result, the rapid closure of the aortic valve 

 is not interfered with when the ventricular contraction ceases 

 and the elastic reaction of the walls of the aorta tends to force 

 blood back into the ventricle. 



Trachea _ 

 Innominate artery .__ 



Right innominate vein. 

 Left innominate vein- 



Superior vena cava__ 



Ascending aorta _^H 



Upper right pulmonary vein. 

 Right auricle. 

 Anterior aortic sinus- 

 Right coronary artery. 



Moderator band- 

 Anterior 

 papillary muscle 



Tricuspid ori 

 Moderator band- 



Left subclavian artery 

 Left common carotid arten 

 Left internal jugular vein 



Left subclavian vein 



--Arch of aorta 



Pulmonary artery turned 

 upwards 



Left pulmonary artery 

 Front of left atrium 

 Left auricle 

 Left coronary artery 



Left posterior aortic sinu 

 Aortic vestibule 



Anterior cusp of b 

 cuspid valve 

 J'.icuspid orifice 

 Anterior papillary 

 muscle 



Inferior papillary 

 muscle 



Interventricular 

 septum 



FIG. 53. Dissection of the Heart from the anterior aspect. 



The aortic orifice lies at the upper, right, and posterior 

 part of the cavity, posterior to the left margin of the sternum, at 

 the level of the third intercostal space. Its left and inferior 

 margin is separated from the atrio-ventricular orifice by the 

 superior cusp of the mitral valve. It is guarded by a valve, 

 the aortic valve, which prevents regurgitation from the aorta 

 into the ventricle. The aortic valve, like the pulmonary 



