454 ARTERIES. 



and has attached to it, above, the fibrous layer of this membrane. Behind, it 

 rests at first upon the ascending aorta, and higher up in front of the left auricle. 

 On either side of its origin are the appendix of the corresponding auricle, and a 

 coronary artery ; and higher up it passes to the left side of the ascending aorta. 

 A little to the left of its point of bifurcation, it is connected to the under surface 

 of the arch of the aorta by a short fibrous cord, the remains of a vessel peculiar 

 to fcetal life, the ductus arteriosus. 



The right pulmonary artery, longer and larger than the left, runs horizontally 

 outwards, behind the ascending aorta and superior vena cava, to the root of the 

 right lung, where it divides into two branches, of which the lower, the larger, 

 supplies the lower lobe ; the upper giving a branch to the middle lobe. 



The left pulmonary artery, shorter and somewhat smaller than the right, passes 

 horizontally in front of the descending aorta and left bronchus to the root of the 

 left lung, where it divides into two branches for the two lobes. 



The author has to acknowledge valuable aid derived from the following works : Harrison's " Sur- 

 gical Anatomy of the Arteries of the Human Body," Dublin, 1824. Richard Quain's ''Ana- 

 tomy of the Arteries of the Human Body," London, 1844. Sibson's " Medical Anatomy," and 

 the other works on General and Microscopic Anatomy before referred to. 



