4M ANATOMY IX A NUTSHELL. 



(in vena azygos minor from the Left side, (c) oesophageal, pericardiac, and medias- 

 tinal veins, (d) the right bronchial vein, (e) the right superior intercostal vein. 



2. The vena azygos minor, also called left lower or smaller azygos vein. 

 This vein is formed by a branch from (a) the lumbar veins, (b) or from the left 

 renal vein. After passing through the left cms of the Diaphragm, it passes 

 along the left side of the vertebral column ami at the ninth dorsal vertebra 

 passes to the right behind the thoracic aorta and thoracic duct to end in 

 the vena azygos major. 1 1 > radicles are, (a) four or five lower intercostal veins 

 cf the left side, (b) some (esophageal and mediastinal veins. 



3. The left upper azygos vein, also called vena azygos tertius. The radicles 

 of this vein are from the intercostal spaces between the left superior intercostal 

 vein and the highest radicle of the vena azygos minor. These radicles join to 

 form a main trunk, which empties into the vena azygos major or the vena azygos 

 minor. Somtimes this vena azygos tertius is wanting, then the left superior 

 intercostal vein takes its place. 



The bronchial veins from the right side empty into the vena azygos major; 

 while those of the left side open into the left superior intercostal or vena azygos 

 tertius. 



For veins of the abdomen see page 186. 



LESSON CLVII. 

 The Portal System of Ykixs. (Plates CXXXVIII.) 



The portal system collects the blood from the digestive tract and from the 

 spleen. The veins of this system form the portal vein which enters the liver 

 and breaks up into branches like an artery into the substance of the liver. 

 This system consists of: 



1. The inferior mesenteric vein, which drains the blood from the rectum, 

 sigmoid flexure, and the descending colon. This vein empties into the splenic 

 vein after passing behind the transverse pari of the duodenum and the pancreas 

 and over the left kidney. Its hemorrhoidal radicles inosculate with the luemor- 

 rhoidal branches of the internal iliac. 



2. The superior mesenteric vein collects the blood from the small intestine, 

 the caecum, the ascending colon, and transverse colon. The radicles of this 

 vein correspond with the branches of the superior mesenteric artery, just as 

 the radicles of the inferior mesenteric correspond to the branches of the in- 

 ferior mesenteric artery. This vein passes in front of the transverse portion of 

 the duodenum and behind the pancreas to join the splenic vein at the upper 

 binder of the pancreas where it forms the portal vein. 



3. The splenic vein commences in the hilum of the spleen by five or six 

 branches which unite to form one main funk. It now passes below the splenic 

 artery and behind the upper border of the pancreas in front of the abdominal 

 aorta to join the superior mesenteric vein. 



I. The gastric vein, also called coronary, is a large vein which passes along 

 the lesser curvature of the stomach to the cardiac end where it receives radicles 



