THORACIC CAVITY 



81 



the ventricular contraction ceases and the elastic reaction of 

 the walls of the aorta tends to force blood back into the 

 ventricle. 



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

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



Trachea 



Innominate artery- 

 Right innominate vein 

 Left innominate vein 



Superior vena cava- 

 Ascending aorta. 



Upper right pulmonary vein- 

 Right auricle- 

 Anterior aortic sinus" 



Right coronary artery- 

 Moderator band- 

 Anterior 

 papillary muscle" 



Tricuspid orific 

 Moderator band 



--Left subclavian artery 

 ...Left common carotid arte 

 Left internal jugular vei 



Left subclavian vein 

 -Arch of aorta 



Pulmonary artery turnec 

 upwards 



Left pulmonary artery 

 Front of left atrium 

 Left auricle 



coronary artery 



Left posterior aortic sinu 

 Aortic vestibule 



Anterior cusp of mitr 

 valve 



Mitral orifice 

 Anterior papillary 

 muscle 



_ Posterior papillary 

 ~ muscle 



Interventricular 

 septum 



FIG. 40. Dissection of the Heart from the anterior aspect. 



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

 margin is separated from the atrio- ventricular orifice by the 

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

 the aortic valve, which prevents regurgitation from the aorta 

 into the ventricle. This valve, like the pulmonary valve, 

 consists of three semilunar cusps, but in contradistinction to 



VOL. II 6 



