Development The umbilical arteries supply systemic arterial blood from the fetus to the
placenta. Umbilical artery blood is enriched in CO2 and has a lower oxygen content in comparison with systemic arterial blood after birth or in the adult. There are usually two umbilical arteries present together with one
umbilical vein in the
umbilical cord. The umbilical arteries surround the
urinary bladder and then carry all the deoxygenated blood out of the fetus through the umbilical cord. Inside the placenta, the umbilical arteries connect with each other at a distance of approximately 5 mm from the cord insertion in what is called the
Hyrtl anastomosis. Subsequently, they branch into
chorionic arteries or
intraplacental fetal arteries. The umbilical arteries are actually the anterior division of the
internal iliac arteries, and retain part of this function after birth. The
pressure inside the umbilical artery is approximately 50
mmHg. Resistance to blood flow decreases during development as the artery grows wider.
After development The umbilical artery regresses after birth. A portion obliterates to become the
medial umbilical ligament (not to be confused with the
median umbilical ligament, a different structure that represents the remnant of the embryonic
urachus). A portion remains open as a branch of the anterior division of the internal iliac artery. The umbilical artery is found in the
pelvis, and gives rise to the
superior vesical arteries, which in males usually supplies the
artery to the ductus deferens. Alternately, the latter artery can be supplied by the
inferior vesical artery in some individuals. == Clinical significance ==