122 TOPOGRAPHIC AND APPLIED ANATOMY. 



PLATE 13. 



The position of the thoracic and abdominal viscera of a boy, seen from the left and from the right. From the mode, 

 of Plate ii. 



FIG. 55. A diagrammatic representation of the communications between the superior and inferior venae cavae and 

 the portal vein. 



in the middle of the so-called Richter-Monro line, drawn from the anterior superior spine of the 

 ilium to the navel, or to the inner side of the vessel (Naunyn) through the rectus abdominis muscle, 

 three centimeters from the linea alba midway between the navel and the symphysis. 



3. The deep circumflex iliac artery, the remaining branch of the external iliac, passes outward 

 along the iliac crest and then upward to supply the abdominal muscles; upon the iliacus muscle 

 it anastomoses with the iliac branch of the iliolumbar artery (from the internal iliac). 



4. The four pairs of lumbar arteries which arise from the abdominal aorta pass in front oi 

 the bodies of the first to the fourth lumbar vertebras beneath the tendinous arch of origin of the 

 psoas muscle, and run partly in front of and partly behind the quadratus lumborum to the mus- 

 culature of the lateral abdominal wall. 



The veins of the abdominal wall may also be divided into a superficial and a deep set 



(Fig. 55)- 



The superficial or subcutaneous veins are the superficial epigastric and the superficial cir- 

 cumflex iliac; they are considerably larger than the arteries of the same name which they accom- 

 pany, and empty into the femoral vein below Poupart's ligament. The superficial epigastric 

 vein anastomoses above with the long thoracic through the thoracico-epigastric vein, and thus 

 aids in the formation of a subcutaneous venous connection in the thoracic and abdominal walls 

 between the axillary and the femoral veins. 



The deep veins are the vena comites of the inferior epigastric artery (which anastomose 

 above with the superior epigastric branch of the internal mammary vein), the venae comites of 

 the superficial circumflex iliac artery, and the single lumbar veins (which run above their accom- 

 panying lumbar artery). The vertical anastomoses of the lumbar veins behind the psoas muscle 

 form the ascending lumbar veins upon each side which give origin to the vena azygos major and 

 minor. In this manner a venous communication is formed between the superior and inferior 

 vena cava in the posterior portion of the body; the importance of this venous connection has 

 been previously emphasized (see page 116). A stasis in the inferior vena cava may ilso make 

 itself visible through the anterior abdominal wall, since the blood from the inferior vena cava 

 tries to reach the superior vena cava through the dilated superficial epigastric veins. 



The superficial veins of the abdominal wall form a subcutaneous venous plexus which com- 

 municates with the area drained by the deep epigastric veins by means of numerous anastomoses 

 passing through the abdominal wall (Fig. 55). These anastomoses are also directly con- 

 nected with the portal vein, on the inferior surface of the liver, by four or five small 

 parumbilical veins (accessory portal branches) which pass along the round ligament of 

 the liver. The portal vein enters the liver at the porta hepatis and arises from the 

 veins of the stomach, of the intestines, of the spleen, and of the pancreas. Diseases of 

 the liver cirrhosis, for example easily produce stasis in the venous radicals of the portal 

 vein and transudation from the vessels in the organs which have just been mentioned; 



