THE LVNGS 



1191 



The base (basis pulmonis') is broad, concave, and rests upon the convex surface 

 of the Diaphragm, which separates the right lung from the upper surface of the 

 right lobe of the liver and the left lung from the upper surface of the left lobe 

 of the liver, the fundus of the stomach, and the spleen. Since the Diaphragm 

 extends higher on the right than on the left side, it follows that the concavity 

 on the base of the right lung is deeper than that of the left. Laterally and 

 behind, the base is bounded by a thin, sharp margin which projects for some 

 distance into the costophrenic sinus of the pleura, between the lower ribs and the 

 costal attachment of the Diaphragm. The base of the lung descends during 

 inspiration and ascends during expiration; its relation to the thoracic wall is 

 indicated in Figs. 909 and 910. 



ROOT OF 

 LUNG 



SUBCLAVIAN 

 GROOVE 



PULMONARY 

 ARTERY 



BRONCHUS 



PULMONARY 

 VEINS 



BRONCHIAL 

 ARTERIES 



BRONCHIAL 

 LYMPH NODE 



LIGAMENTUM 



LATUM 



PULMONIS 



CARDIAC 

 DEPRESSION 



INFERIOR 

 BORDER 



FIG. 904. The left lung. The inner or mediastinal surface, with the root of the lung cut across. (Toldt.) 



Surfaces. The external, costal, or thoracic surface (Jades costalis) (Figs. 907 

 and 908) is smooth, convex, of considerable extent, and corresponds to the form 

 of the cavity of the thorax, being deeper behind than in front. It is in contact 

 with the costal pleura, and presents, in a hardened specimen, slight grooves 

 corresponding to the overlying ribs. 



The inner or mediastinal surface (Jades mediastinalis) (Figs. 903 and 904) 

 is in contact with that portion of the pleura which forms the lateral boundary of 

 the mediastinal space. It presents a deep concavity which accommodates the 

 pericardial sac; this is larger and deeper on the left than on the right lung, on 

 account of the heart projecting farther to the left than to the right of the mesal plane. 

 Above and behind this concavity is a triangular depression named the hilum (Jiilus 

 pulmonis], where the structures which form the root of the lung enter and leave 

 the viscus. 



On the right lung (Fig. 905) immediately above the hilum, is an arched furrow 

 which accommodates the vena azygos major, while running upward, and then arch- 

 ing outward some little distance below the apex, is a wide groove for the superior 

 vena cava and right innominate vein; and behind this, nearer the apex, is a second 



