Chap. XI] THE VASCULAR SYSTEM 



189 



(4) The abdominal aorta commences about the lower border of 

 the last thoracic vertebra, and terminates below by dividing into 



Phrenic 



A lumbar vein 



Fig. 120. — Abdominal Aorta. (Gerrish.) 



the two common iliac arteries. The bifurcation usually takes 

 place about halfway down the body of the fourth lumbar vertebra, 

 which corresponds to a spot on the front of the abdomen, slightly 



