RELATIONS OF LUNGS. 



447 



The posterior border is half as long again as the anterior, and Posterior 

 projects inferiorly between the lower ribs and the diaphragm ; it is thfck? 

 thick and vertical, and is received into the hollow by the side of 

 the spinal column. 



The outer surface of the lung is convex, and is in contact with External 

 the wall of the thorax : a large cleft, known as the great fissure, 

 divides it into two parts, and on the right side there is an additional 

 smaller fissure. The inner surface is flat when compared with the internal 

 outer : at the fore part is a large hollow which lodges the heart and 

 great vessels, and is most marked on the left lung ; and behind gives attach- 

 this is a depression about three inches long, hilum pulmonis, which roo t. 



FIG. 162. DIAGRAM TO SHOW THE DIFFERENCE IN THE ANTERIOR BORDER 

 OF THE RIGHT AND LEFT LUNG, THE EDGE BEING INDICATED BY THE 

 DARK LINE ; AND TO MARK THE DIFFERENT LEVEL OF THE BASE ON 



THE TWO SIDES. 



receives the vessels of the root of the lung. In the hardened 

 specimen well-marked grooves are seen upon the lung for the 

 reception of the great vessels with which it is in contact, and on 

 the left lung is a specially deep groove in its inner surface formed 

 by the arch of the aorta, and by the descending thoracic aorta 

 (fig. 163, p. 448). 



Each lung (fig. 161) is divided into two lobes by the great fissure, Division 

 which, running obliquely downwards and forwards, begins at the m 

 posterior border near the apex, and ends at the fore part of the base, {^{J h{ 

 and the lower lobe of the lung is larger than the upper. In the an <ithe 



right lung a second horizontal fissure is directed forwards from the right 



. J ,, three lobes, 



middle of the oblique one to the anterior border, and cuts on a small 



