THE LUNGS 



463 



cardiac, and diaphragmatic. The right lung has four or five lobes; the apical 



lobe is much hirger than that of the U'ft king, and occupieis the space in front of 

 the pericardium, pushing the mediastinum against the left wall;^ the mediastinal 

 lobe resembles that of the horse, while the cardiac lobe is often divided by a fissure 

 into two parts. The apical Io1)e of the right hmg receives a special bronchus from 

 the trachea opposite the third rib. The right lung is adherent to the trachea from 

 the second rib backward. 



Apicdl lobe 



- Cardiac lobe 



Mediastinal lobe 



Diaphragmatic lobe 



Posterior mediastinal lymph gland 



Fi(i. 3fi9. — LuxGS AND Heart of Sheep, Ventral View. 

 Specimen hardened in situ. Si)ace between heart and kings was occupied by pericardium and fat. 



The interlobar fissures begin at the ventral margin of the lung and pass toward the root. 

 Those of the left lung lie opposite to the fourth and sixth ribs. The diaphragmatic lobe is the 

 largest, and has the form of a three-sided pyramid with its base resting on the diaphragm. The 

 cardiac lobe is prismatic and forms the posterior margin of the cardiac notch; its long axis corre- 

 sponds to the fifth rib. The apical lobe of tlie left lung is small and pointed; its \-cntral margin 

 lies on the pulmonary artery and the anterior aorta; below this the space in front of the heart 

 is occupied by the apical lobe of the right lung. The cardiac lolje of the right lung is much larger 

 than that of "the left lung, and covers the right face of the pericardium, so that the latter has no 

 contact with the lateral wall of the thorax. 



The lobulation is very distinct on account of the extremely large amount of 

 interlobular tissue. 



1 It is therefore often termed the precardiac lobe. 



