40 THE THORACIC: VISCEKA, BOCCALACAVITY, 
I. The Veins opening into the Right Auricle. 
a. THE SUPERIOR VENA Cava (pre-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 tothe 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- 
tenor ‘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 PuLtmonary 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 ascexding aorta, then curves posteriorly 
