784 



ORGANS OF YOICE AND RESPIRATION. 



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

 border, and projects below between the ribs and the 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 in which the pericardium is exposed. 



Fig. 433. Front View of the Heart and Lungs. 



Duftut Arter/a 



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 inclina- 

 tion of the heart to the left side; it 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 three lobes. 



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

 two lobes. 



A little above the middle of the inner surface of each lung, and nearer its 

 posterior than its anterior border, is its root, by which the lung is connected to 

 the heart and the trachea. The root is formed by the bronchial tube, the pul- 

 monary artery, the pulmonary veins, the bronchial arteries and veins, the pul- 



