448 



DISSECTION OF THE THORAX. 



Surface 

 marking of 

 the fissures. 



triangular piece from the upper lobe, which is called the middle 

 lobe. Occasionally there may be a trace of the third lobe in the 

 left lung. 



The surface marking for the great fissure of the lung is a line 

 taken downwards and forwards round the chest from the middle 

 line of the back behind opposite the root of the spine of the scapula, 

 to the junction of the sixth rib with its cartilage in front and 

 below. The horizontal fissure of the right lung is marked by a line 



FIG. 163. THE ROOTS OP THE LUNGS FROM THE FRONT. THE LUNGS WERE 

 SEPARATED FROM ONE ANOTHER, THE GREATER PART OF THE ARCH OF 

 THE AORTA CUT AWAY, AND THE HEART DRAWN DOWN. 



Difference 

 in form and 

 size of the 

 lungs. 



Root of the 

 lung : 



situation 



drawn outwards from the middle of the sternum opposite the fourth 

 costal cartilage until it meets the line of the great fissure. 



Besides the difference in the number of the lobes, the right lung 

 is larger and heavier, and is wider and more hollowed out at the 

 base, as well as being somewhat shorter than the left. The increased 

 length and the narrowness of the left lung are due to the absence of 

 a large projecting body like the liver below it, and to the direction 

 of the heart to the left side. 



The ROOT OF THE LUNG (fig. 163) consists of the vessels entering the 

 fissure on the inner surface ; and as these are bound together by 

 the pleura and some areolar tissue they form a stalk, which 

 attaches the lung to the heart and windpipe. The root is situate 



