332 A MANUAL OF ANA TOMY. 



The dissection of the heart, see page 354. 

 The Pulmonary Artery. Figs. 57, 58, 70 to 73. Diag. 



22. 



Conveys the venous blood from the right heart to the 

 lungs. It is about two inches long, and is contained within 

 the pericardium, and ends by dividing into two terminal 

 branches, which pass through the pericardium. 



It presents in the interval between the two auricles, 

 curves upward, to the left, and backward beneath the aortic 

 arch, to which it is attached by the obliterated ductus 

 arteriosus (remains of the foetal communication between 

 the pulmonary artery and the aorta), where it divides into 

 its two terminal branches. 



Relations. At the beginning it is between the two auri- 

 cles, and has the ascending aorta behind and to the right. 

 The coronary arteries are on either side of it. It is covered 

 by the pericardium. At its termination it lies beneath the 

 aortic arch, to the left of the ascending aorta, and over the 

 left auricle, and is covered by pericardium on the left. 



(See page 352 for dissection.) 



The Ductus Arteriosus. Fig. 72. 



This is the fibrous cord in the adult which is found 

 joining the under surface of the transverse aorta to the 

 upper surface of the pulmonary artery. In the foetus it 

 was relatively a large trunk and conducted the blood from 

 the pulmonary artery into the aorta. 



The Right Pulmonary Artery. 



Is longer than the left, passes to the right lung, where it 

 divides into three main branches to the three lobes. 



Relations. In front, ascending aorta, superior vena cava, 

 phrenic nerve, and anterior pulmonary plexus of nerves ; 



