THE HEART AND VASCULAR SYSTEM. 211 



Vena azygos minor, Right superior intercostal 



Vena hemi-azygos accessoria, vein, 



Louver end of left superior Right subcostal vein, 



intercostal vein, CEsophageal, 



Lower 8 or 9 intercostal Right bronchial. 



veins, 



The hemi-azygos veins' are two in number: 



The vena azygos minor arises on the left side, similarly to 

 the azygos major, and passes through the left crus of the dia- 

 phragm and about the eighth dorsal vertebra crosses beneath the 

 aorta to join the vena azygos major; 



The vena hemi-azygos accessoria communicates with the 

 upper left intercostal vein, and terminates either in the vena 

 azygos minor or the azygos major. 



The inferior cava formed by the junction of the common 

 iliac veins, at the sides of the fourth lumbar vertebra, ascends on 

 the right of the aorta, grooves the posterior border of the liver, 

 and passes through the quadrate foramen in the central tendon 

 of the diaphragm, and ends in the right auricle. It receives 



Middle sacral, Renal veins the left, the 

 Lumbar, longer, crosses in front 



Spermatic (from spermatic of the aorta, 



plexus), Suprarenal, 



Ovarian (from ovarian Phrenic, 



plexus), Hepatic (2 or 3). 



The portal vein, about three inches in length, is formed by 

 the inferior and superior mesenteric, the gastric, splenic, and 

 pancreatic veins. It ascends in the right border of the lesser 

 omentum to the transverse fissure of the liver, where it divides 

 into the right and left. Its blood is distributed through the liver, 

 mixing with the arterial blood from the hepatic artery, to be 

 returned to the inferior cava by the hepatic veins. It receives 



The superior mesenteric, Cystic, 



Splenic, Inferior mesentery, 



Coronary, Right gastro-epiploic. 



The portal vein and its branches are destitute of valv<s. 



VEINS OF THE VERTEBRAL COLUMN. 1. The dorsi-spinal 

 veins commence in an intricate net-work surrounding the verte- 

 bral arches and their processes. They communicate with the in- 

 tercostal, vertebral, intraspinal plexus, lumbar, sacral, and the 

 superficial veins of the back. 



2. The intraspinal or meningo-rachidian veins form an in- 

 tricate plexus between the vcrtchra' and dura mater within the 

 spinal canal. They consist of four longitudinal veins two in 



