476 PRACTICAL ANATOMY. 



It is about three inches long. About one-half of the vessel is in the pericar- 

 dium. It returns practically all the blood to the heart from above the dia- 

 phragm. Its minor tributaries are the vena azygos major and minor and the 

 pericardiac, mediastinal, and cesophageal veins. The vena cava superior has no 

 valves, but its tributaries are provided therewith. The vessel opens into the right 

 auricle of the heart. 



THE VEINS OF THE LOWER EXTREMITIES 



Are but superficial and deep. The superficial veins are very numerous, anastomose 

 quite freely, but only two are of sufficient import to be entitled to special names. 

 The general name by which structures in the superficial fascia are designated is 

 cutaneous or superficial. The special names for the two important veins of the 

 lower extremity are : (i) Long saphenous ; (2) short saphenous. 



The long saphenous vein begins at the inner end of the dorsal arch of the 

 foot, passes in front of the inner malleolus, behind the inner tuberosity of the 

 tibia and the inner condyle of the femur, and passes through the saphenous 

 opening in the fascia lata to become tributary to the common femoral vein. 

 Below the knee this vein is attended by the long saphenous nerve. This vein has 

 valves. It communicates with venae comites in its course. Above the knee its 

 tributaries are the superficial external pudic, the superficial epigastric, the super- 

 ficial circumflex iliac, and the internal and external femoral cutaneous veins. 



The short saphenous vein begins at the outer end of the dorsal arch of 

 the foot, passes behind the outer malleolus, gains the mid-line of the leg pos- 

 teriorly, and pierces the popliteal fascia to become tributary to the popliteal vein. 



The deep veins of the lower extremity accompany the arteries, and take 

 the same name, where there is but one vein to attend the artery ; where, how- 

 ever, there are two, as is the case below the knee, then the term vcnce comites is 

 used. About one inch below Poupart's ligament the common femoral vein is 

 formed by the confluence of the superficial and deep femoral veins. The com- 

 mon femoral vein is in the femoral sheath, between the common femoral artery 

 and the femoral canal. Above Poupart's ligament this vessel is continued 

 upward, under the name of external iliac vein. Opposite the junction between the 

 sacrum and ilium the external iliac becomes confluent with the internal iliac vein, 

 to form the common iliac vein. 



The ascending vena cava is formed by the confluence of the common iliac 

 veins. It begins opposite the fourth or fifth lumbar vertebra. It lies to the right 

 of the abdominal aorta. It passes through a groove on the posterior surface of 

 the liver. It passes through the caval opening in the diaphragm and opens into 

 the right auricle of the heart. The sacra media vein is the first tributary, the 

 hepatic vein the last tributary, that the vena cava receives in its course. Between 

 these two extremes the tributaries are numerous and important : the lumbar, 

 right spermatic or ovarian, renal, suprarenal, and phrenic. The left spermatic 

 vein is tributary to the left renal, as is also its homologue, the ovarian. 



The portal vein is formed by the gastric, splenic, superior mesenteric, and 

 inferior mesenteric arteries. These veins have no valves. Blood coming from 

 the abdominal organs is laden with bile and sugar, both of which are removed 

 from the portal blood by the liver. The bile is stored up in the gall-bladder ; 

 the sugar is stored up as potential energy in the hepatic cells. The portal vein 

 enters the root of the liver, between the hepatic artery and the common bile-duct. 



