132 GENERAL BIOLOGY. 



A. The Veins. 



Leave those in the posterior abdominal region 

 until after the reproductive organs, etc , have 

 been examined. 

 I. The Yense Cavse. 



A diagram should be begun at an early stage in 

 the dissection of the veins, etc., and added to 

 as each new structure is seen. 



The anterior venae cavse. 



Opening into the right auricle the right anterior 

 vena cava, a large vein bringing blood from the 

 right arm and the right side of the head, etc. 

 It receives near the heart (best seen by turn- 

 ing the heart over to the left) : 



1. The azygos vein which comes from the median 



dorsal thoracic region, bringing blood from 

 the posterior intercostal spaces of both 

 right and left sides of the body. 



2. Near the entrance of the azygos a smaller 



vein, the right intercostal vein, bringing 

 blood from the right anterior intercostal 

 region. 



3. Anterior to the intercostal vein a vertebral vein 



from the brain and the spinal cord. 

 4 A small vein from the inner side of the ven- 

 tral wall of the thorax, the internal mam- 

 mary vein. Near the entrance of the in- 

 ternal mammary vein the anterior vena 

 cava is formed by the union of : 



