144 Life and Health 



^ 218. The Great Blood Vessels connected with the Left 

 Side of the Heart. Let us now turn to the left side of 

 the heart and study the general plan of its great vessels. 

 Four veins, called the pulmonary veins, open into the left 

 auricle, two from each lung. They start from very minute 



FIG. 73. Lateral Section of the 

 Right Chest. 



(Showing the relative position of the 

 heart and its great vessels, and of 

 the oesophagus and trachea.) 



A, inferior constrictor muscle (aids in 

 conveying food down the oesopha- 

 gus) ; B, oesophagus ; C, section of 

 the right bronchus ; D, two right 

 pulmonary veins; E, great azygos 

 vein crossing oesophagus and right 

 bronchus to empty into the superior 

 vena cava; F, thoracic duct; H, 

 thoracic aorta ; K, lower portion of 

 oesophagus passing through the dia- 

 phragm; L, diaphragm as it ap- 

 pears in sectional view, enveloping 

 the heart; M, inferior vena cava 

 passing through diaphragm and 

 emptying into auricle; N, right 

 auricle ; O, section of right branch 

 of the pulmonary artery ; P, aorta ; 

 R, superior vena cava ; S, trachea. 



vessels and form larger and larger vessels until they become 

 two large veins in each lung, and pour their contents into 

 the left auricle. 



Remember, then, that the pulmonary artery carries venous 

 blood from the right ventricle to the lungs, and that the 



