12 



(6) The right anterior intercostal vein, joining the vena cava just 



in front of the vena azygos. 



(7) The right internal mammary vein, from the inner surface of 



the ventral thoracic wall, joining the vena cava at the level of 

 the first rib. 



(b) The left anterior vena cava, differing from the right only in so far 



as it receives no azygos vein, and has a different course in order to 

 reach the heart. 



(c) The posterior vena cava, running forwards through the liver dor- 



sally, to pierce the central tendon of the diaphragm, and open 

 into the right auricle. Note the following veins joining it — 



(1) The posterior phrenic veins, from the diaphragm. 



(2) The hepatic veins, generally four in number, joining the 



inferior vena cava in the liver substance. 



(3) The renal veins, (one pair), from the kidneys. Each receives 



a small vein from the adrenal body, and one from the dorsal 

 wall of the abdomen. 



(4) The spermatic veins (ovarian in the female), (one pair), from 



the testes (or ovaries). 



(5) The ilio-lumbar veins, (one pair), from the hinder part of the 



abdominal walls. 



(6) The external iliac veins, (one pair), direct continuations of the 



femoral veins from the thigh. 



(7) The internal iliac veins, (one pair), running through the pelvis 



from the dorsal aspect of the thighs. 

 2. The portal system. Observe the portal vein lying close to the posterior 

 vena cava, and dividing to supply the various lobes of the liver. It is 

 formed by the junction of — 



(1) The lieno-gastric from the walls of the stomach and the spleen. 



(2) The duodenal, from the duodenum and the pancreas. 



(3) The anterior mesenteric, carrying blood from the small intes- 



tine, caecum, colon, and rectum. 



(4) The posterior mesenteric, from the rectum. 

 The pulmonary system. (See above, p. 10, 2, (c).) 



The arteries. 



1. The aorta. Trace this artery along its whole length, noting the 

 following branches — • 

 (a) The innominate artery, from the arch of the aorta dividing into — 



(1) The right subclavian artery, running on as the brachial artery 



and giving off the vertebral and the internal mammary 

 arteries. 



(2) The right carotid artery, dividing into the inter al and the 



external carotid arteries. 

 (h) The left carotid artery, dividing into the left internal and the 

 external carotid arteries. 



