VASCULAR SYSTEM 5 1 



VENOUS SYSTEM. (Plate VI.) 



A. — Prae-cava. 



The Prae-cava, or Superior Vena Cava, is the large 

 vein which brings back blood from the anterior 

 part of the body, and empties into the right auri- 

 cle, as already described. It receives the follow- 

 ing branches : 



1. The Azygos Vein collects the blood from the 

 intercostal and lumbar regions, and empties into 

 the prae-cava in front of the heart. 



2. The Vertebral Vein of the right side joins the 

 superior vena cava some distance anterior to the 

 azygos vein. 



3. The Sternal Veins enter the prae-cava by a 

 common trunk on its ventral side just anterior to 

 the right vertebral vein. They arise as two veins 

 on either side of the sternum, and, passing ante- 

 riorly, unite at the level of the fourth rib. 



4. The Brachio-cephalic or Innominate Veins are 

 two large veins which unite at the level of the 

 subclavian arteries to form the prae-cava. 



5. The External Jugular Vein is formed by the 

 union of the temporal, internal maxillary, and 

 facial veins, which correspond to the arteries of 

 the same names. It runs just beneath the skin, 

 across the sterno-mastoid muscle, and empties into 

 the subclavian vein. Between the temporal and 



