J 



550 



THE LUNGS. 



The lungs are two conical organs, situated one on each side of the 

 chest, embracing the heart, and separated from each other by that 

 organ and by a membranous partition, the mediastinum. On the ex- 

 ternal or thoracic side they are convex, and correspond with the form 

 of the cavity of the chest; internally they are concave, to receive the 

 convexity of the heart. Superiorly they terminate in a tapering cone, 

 which extends above the level of the first rib, and inferiorly they are 

 broad and concave, and rest upon the convex surface of the diaphragm . 



Fig. 166*. 



* Anatomy of the heart and lungs, l. The right ventricle ; the vessels to 

 the right of the figure are the middle coronary artery and veins ; and those to 

 its left, the anterior coronary artery and veins. 2 The left ventricle. 3. The 

 right auricle. 4. The left auricle. 5. The pulmonary artery. 6. The right 

 pulmonary artery. 7. The left pulmonary artery. 8. The remains of the duc- 

 tus arteriosus. 9. The arch of the aorta. 10. The superior vena cava. 11. 

 The right arteria innominata, and in front of it the vena innominata. 12. The 

 right subclavian vein, and behind it its corresponding artery. 13. The right 

 common carotid artery and vein. 14. The left vena innominata. 15. The 

 left carotid artery and vein. 16. The left subclavian vein and artery. 17. The 

 trachea. 18. The right bronchus. 19. The left bronchus. 20, 20. The pul- 

 monary veins ; 18, 20, form the root of the ricrht lung ; and /, 19, 20, the root 

 of the left. 21. The superior lobe of the risht lung. 22. Its middle lobe. 

 23 Its inferior lobe. 24. The superior lobe of the left lung. 25. Its inferior 



