THE THORAX 



949 



inspiration than expiration, but leaving an area of the pericardium 

 uncovered, which is known as the area of precordial diilness. The 

 anterior border of the right lung keeps behind the sternum as low 

 as the sixth right costal cartilage. The corresponding border of 

 the left lung, beyond the lower border of the fourth left costal 

 cartilage, presents a deep V-shaped notch, called the cardiac notch, 

 for the reception of the apical portion of the heart, enclosed in the 

 pericardium. The posterior border is elongated, thick, and round, 

 and it occupies the pulmonary groove of the tnorax, by \\v^ side of 

 the thoracic portion of the vertebral column. 



Each lung is divided into two lobes, upper and lower, by au 

 extensive, oblique, and deep fissure, which penetrates almost to 



Groove for Subclavian Artery, 

 Groove for Innominate Vein 



Upper Lobe 



,Groove for Subclavian Artery 

 _ Groove for Innominate Vein 



Upper Lobe 



Lower Lobe ' 



Interlobar Fissure 



Cardiac 

 Notch 



Interlobar Fissure 



Lower Lobe 



Fig. 388. — The Lungs (Anterior View). 

 A, the Right Lung ; B, the Left Lung. 



the hilum. So deep is this fissure that, unless adhesions have 

 formed, the Irnig appears to consist of two halves. The fissure 

 commences on the inner surface, near the posterior border, about 

 3 inches below the apex. It then turns round the posterior border, 

 and passes obliquely downwards and forwards over the outer sur- 

 face to the basal margin. In the case of the right Itmg the fissure 

 joins the basal margin some little distance from the lower end of 

 the anterior border ; but, in the case of the left lung, the fissure 

 joins the basal margin distinctly farther forwards. A good ready 

 guide to this fissure is the lower border of the pectoralis major 

 muscle, as it forms the anterior fold of the axilla. 



