2QO 



THE VASCULAR SYSTEM 



swallowing is often a painful process, and the pain is referred 

 to the terminal branches of the upper intercostal nerves. The 

 occurrence of this symptom in cases of acute rheumatic fever 

 may be the first indication of pericardial involvement. 



Anteriorly, the pericardium is partly overlapped by the 

 lungs and pleural sacs, but it is in direct contact with the 

 sternum over a small area (Fig. 106). In young children the 



FIG. 105. Diagram of a Transverse Section through the upper part 

 of the Pericardium. 



The serous layer of the pericardium is represented by the dotted line. 



1. Pulmonary artery. 



2. Fibrous layer of pericardium. 



3. Ascending aorta. 



4, 5. Serous layer of pericardium. 



6. Superior vena cava. 



7. Right pulmonary vein. 



8. Transverse sinus of pericardium. 



9. Upper extremity of left atrium (auricle). 



dulness obtained on percussion over this area may be con- 

 tinued upwards to the upper border of the sternum. This 

 phenomenon usually indicates the presence of a large thymus 

 (p. 413). The area of contact with the anterior thoracic 

 wall becomes greatly increased in large effusions, owing to the 

 retraction of the anterior borders of the compressed lungs. 

 In these cases it may be possible to determine by percussion 

 that the dulness extends over an area which corresponds to 

 the conical shape of the pericardial sac. 



