PLATE XII 



Plate XII is from the upper surface of a section through 

 the uppermost part of the disc between the eighth and ninth 

 thoracic vertebrae posteriorly and the articulations of the 

 fifth costal cartilages with the sternum anteriorly. The 

 plane of the section is 2.5 cm. below that of the last section 

 and is horizontal. 



The vena cava inferior pierces the diaphragm and en- 

 ters the inferior and posterior part of the right auricle 

 (Atrium dextrum) near the upper surface of this section. 

 What is labeled vena cava inferior in the plate is in reality 

 the lowest part of the auricle into which the vein opens 

 about .5 cm. below the surface of the section. 



The right pleural cavity appears exaggerated in 

 size in this figure, on account of the great width of the 

 shallow space between the base of the lung and the super- 

 ior surface of the diaphragm. A similar exaggeration is 

 seen in the pericardial cavity. 



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