THE MEDIASTINUM. 



finger may consequently be passed behind both of these structures into the sinus transversus 

 pericardii, which is bounded anteriorly by the posterior surface of the pulmonary artery and of 

 the aorta, and posteriorly by the anterior wall of the auricles (consisting chiefly of the left auricle). 

 The aorta and the pulmonary artery are the only vessels around which the finger may be passed 

 after the pericardial sac has been opened. None of the other vessels possess a complete covering 

 of visceral pericardium at their cardiac extremities, but they are all more or less distinctly visible 



Orifice of azygos major vein 



Superior vena cava 



Lung 



Orifice of right superior 

 pulmonary vein 



Orifice of right inferior 

 pulmonary vein 



Esophagus - 



Orifice of inferior vena cava 



Innominate artery 

 Arch of aorta 



Sinus transversus pericardii 

 Ascending aorta 



Pulmonary artery 

 Bronchi 



Orifice of left superior 

 pulmonary vein 



Orifice of left inferior 

 pulmonary vein 



Left vagus nerve 



Diaphragm 



FIG qi The dorsal half of a frontal section of the pericardium with the large vessels. An opening has been made 

 in the posterior wall of the pericardium so that the esophagus is exposed. (Formalin prepar 



in the pericardium. From in front, the superior vena cava may be seen high up and to the right 

 alongside of the aorta; the inferior vena cava is visible when the heart is pushed upward and to 

 the left; the left pulmonary veins are exposed by holding the heart upward and to the right by 

 means of its apex; the right pulmonary veins are scarcely to be seen because they are covered 

 by the right auricle. By moving the heart about in this manner it will be seen that it is suspended 

 in the pericardial cavity by the great vessels. The removal of the heart may consequently be 



