Final answer:
The bifurcation of the aorta at the level of the fourth lumbar vertebra results in the formation of the two common iliac arteries which supply blood to the lower limbs and pelvis.
Step-by-step explanation:
The vessels formed by the bifurcation of the aorta at the level of the fourth lumbar vertebra are the two common iliac arteries. Prior to this bifurcation, the abdominal aorta gives rise to several important branches including the celiac trunk, which further divides into the left gastric artery, the splenic artery, and the common hepatic artery, along with the superior and inferior mesenteric arteries.
The superior mesenteric artery supplies blood to the small intestine and parts of the large intestine, while the inferior mesenteric artery supplies the distal segment of the large intestine, including the rectum.