40 THE THORACIC VISCERA, BUCCAL CAVITY, 



1. The Veins opening into the Right Auricle. 



a. The Superior Vena Cava (picE-cava) opens 

 into the anterior end of the auricle, and brings back 

 venous blood from the head, neck, upper limbs and 

 thorax. 



b. Just above the root of the right lung the su- 

 perior cava receives the large azygos vein. Lift up 

 the right lung and follow the azygos along the dorsal 

 wall of the thorax to the diaphragm. Notice the side 

 branches, the intercostal veins, which it receives from 

 the walls of the thorax. 



c. The Inferior Vena Cava (post-cava) empties 

 into the posterior end of the auricle. Follow it to the 

 diaphragm. 



2. Arteries arising from the Right Ventricle. 



a. The Pulmonary Artery arises from the an- 

 terior and dorsal corner of the ventricle, passes 

 dorsally for a short distance, and then divides into 

 the right and left pulmonary arteries which go to the 

 two lungs, entering each at its root. They carry 

 venous blood from the heart to the lungs. 



3. Veins opening into the Left Auricle. 



a. The Pulmonary Veins. There are two prin- 

 cipal veins on each side : on the left side, one from 

 each lobe ; on the right side, one from the two upper 

 and one from the two lower lobes. These four veins 

 converge to enter the auricle, the two from the right 

 lung passing directly underneath the right auricle to 

 reach their destination. These veins bring back 

 arterial blood from the lungs to the heart. 



4. Arteries arising from the Left Ventricle. 



a. The Aorta arises from the anterior end of the 

 ventricle, immediately dorsal to the origin of the 

 pulmonary artery. It passes for a short distance 

 anteriorly, the ascending aoi'ta, then curves posteriorly 



