Visceral branches of the aorta are divided into unpaired arteries (coeliac, superior mesenteric, inferior mesenteric) and paired arteries (suprarenal, renal, testicular/ovarian, umbilical). The umbilical arteries shift caudally as the embryo increases in size and form anastomoses with the somatic intersegmental arteries (5th lumbar segment). After degeneration of the visceral anastomoses, they originate only from the parietal lumbar intersegmental arteries. The umbilical arteries become branches of the internal iliac arteries once the latter have been formed from the intersegmental arteries.