718 



ORGANS OF YOICE AND RESPIRATION. 



The posterior border is rounded and broad, and is received in the deep con- 

 cavity on either side of the spinal column. It is much longer than the anterior 

 border, and projects below between the ribs and Diaphragm. 



The anterior border is thin and sharp, and overlaps the front of the peri- 

 cardium. 



The anterior border of the right lung corresponds to the median line of the 

 sternum, and is in contact with its fellow, the pleurae being interposed, as low as 

 the fourth costal cartilage ; below this, the contiguous borders are separated by an 

 irregularly-shaped interval, formed at the expense of the anterior border of the 

 left lung, and corresponding to which the pericardium is exposed. 



Fig. 3(56. Front View of the Heart and Lungs. 



Dartltt Artor/oiu* 



Each lung is divided into two lobes, an upper and lower, by a long and deep 

 fissure, which extends from the upper part of the posterior border of the organ, 

 about three inches from its apex, downwards and forwards to the lower part of 

 its anterior border. This fissure penetrates nearly to the root. In the right lung 

 the upper lobe is partially divided by a second and shorter fissure, which extends 

 from the middle of the preceding, forwards and upwards, to the anterior margin of 

 the organ, marking off a small triangular portion, the middle lobe. 



The right lung is the largest ; it is broader than the left, owing to the inclination 

 of the heart to the left side, and is also shorter by an inch, in consequence of the 

 Diaphragm rising higher on the right side to accommodate the liver. The right 

 lung has also three lobes. 



The left lung is smaller, narrower, and longer than the right, and has only two 

 lobes. 



