284 THE RABBIT 



(c) The inferior vena cava or postcaval, which returns blood from the 

 abdominal region, passes through the diaphragm and opens into the 

 posterior end of the right auricle. 



From the right ventricle the pulmonary artery arises. It conveys the 

 venous blood from heart to lungs. It arches over to the dorsal surface of 

 the left auricle, and there divides into the right and the left pulmonary arteries. 

 It is connected with the aorta by the ductus arteriosus. 



The pulmonary veins, which return the blood from the lungs to the heart, 

 open into the left auricle on its dorsal surface. 



The aorta, which conveys the purified blood from the heart to the body, 

 arises anteriorly from the left ventricle. It goes forwards, then bends over 

 to the left (aortic arch) and passes backwards, along the vertebral column, as 

 the dorsal aorta. Note the ductus arteriosus, which arises just before the 

 bifurcation of the pulmonary arch and connects that arch with the aorta. 



A. The Venous System. 



The right precaval (right anterior or superior vena cava) is formed? by the 

 following veins :— 



(a) The right subclavian vein, from the fore-limb and shoulder. 



(b) The right external jugular vein, along the side of the neck, formed by 



the union of the anterior and posterior facial veins in the anterior 

 region of the neck. It joins the subclavian vein at the base of the arm. 

 (See page 278.) 



(c) The right internal jugular vein, running close to the trachea, and joining 



the external jugular. (See page 278.) 



(d) The azygos vein, passing forwards along the vertebral column on the 



right-hand side only, and joining the right precaval vein near the right 

 auricle. It receives seven or eight pairs of intercostal veins from the 

 spaces between the ribs. 



The left precaval (left anterior or superior vena cava) is formed by similar 

 veins on the left ~ side, and then passes over the anterior surface of the lungs 

 to open into the right auricle. It does not receive an azygos vein, there being 

 only one. 



The postcaval (posterior or inferior vena cava), running forwards through 

 the dorsal part of the liver, receives the following veins in its course : — 



(a) The posterior phrenic veins from the diaphragm. 



(b) The hepatic veins from the liver. 



(c) The pair of renal veins from the kidneys. 



(d) The pair of spermatic veins from the testes, or the pair of ovarian veins 



from the ovaries. In the male each spermatic vein and spermatic 

 artery together with some connective tissue form a spermatic cord, 

 which passes from the abdomen to the testis. 



(e) The pair of ilio-lumbar veins from the hinder part of the abdominal 



walls. 

 (/) The pair of external iliac veins, which are continuations of the femoral 

 veins from the thighs. 



