592 



THE BLOOD-VASCULAR SYSTEM 



left renal; (7) right and left internal spermatic; (8) right and left second lumbar; 

 (9) inferior mesenteric; (10) right and left third lumbar; (11) right and left fourth 

 lumbar; (12) right and left common iliac; (13) middle sacral. 



The above branches may be divided into the parietal, the visceral, and the 

 terminal. 



The parietal branches are distributed to the abdominal walls. They are the 

 right and left phrenics, and the four right and left lumbars. 



The visceral branches supply the viscera. Three of these are given ofif singly 

 from the front of the aorta, namely, the cceliac, the superior mesenteric, and the 

 inferior mesenteric; and three are given off in pairs, namely, the two suprarenals, 

 the two renals, and the two spermatics. 



The terminal branches are the middle sacral and the right and left common 

 iliac arteries. 



Fig. 480. — Scheme of the Abdominal Aorta. (Walsham.) 



X, / IL 



Diaphragm- 



Lesser nmpntnm, "\^ 



Splenic vein 



Pancreas 



Left renal vein 

 Superior mesenteric 

 artery 

 Transverse meso-colon 



Inferior part of 

 duodenum 



Transverse colon 

 Mesentery 



Small intestines 

 Great omentum 



Inferior mesenteric 

 artery 



Thoracic duct 

 Coeliac artery 



—First lumbar vein 

 Cisterna chyli 



Second lumbar vein 



Peritoneum 

 Third lumbar vein 



Fourth lumbar vein 



A. The Parietal Branches of the Abdominal Aorta 



1. THE INFERIOR PHRENIC ARTERIES 



The inferior phrenic artery [a. phrenica inferior] usually arises from the aorta 

 as it passes between the medial crura of the diaphragm. At times it comes off 

 from the co'liac artery; or when it arises as two separate vessels, either the right 

 or left vessel may come from this artery, or from other of the upper branches of 

 the abdominal aorta. 



Tlie right phrenic passes (fig. 480) over the right medial cms of the diapliragm behind 

 the vena cava, and then upward and to the right between the central and right leaflets of the 

 central tendon of the muscle, where it divides into an anterior and a posterior branch. The 

 former courses anteriorly and medially and anastomoses with the anterior branch of the left 

 phrenic, with the musculo-phrenic branches of the internal mammary, and with the pericardio- 

 phrenic arteries; the latter passes j)osteriorly and hi te rally toward tlie ribs, and anastomoses 

 with the intercostal arteries, liesides the two termiii;d branches aTid branches for the supply 

 of the diai)hragm itself the right i)hrenic gives olT the right superior suprarenal [ramus supra- 

 renalis suijerior], to the right suprarenal ghiud, as well as branches to the vena cava, to the 

 liver, and to the pericardium. 



The left phrenic cro.s.ses the left medial crus of the diaphragm behind the oesophagus, 

 and, like the right artery, divides into an anterior and posterior branch and gives off a left 

 suprarenal branch. The distribution and anastamoses are similar on the two sides. 



