The<unk>  is a paired<unk>  (with one for each half of the body) that is found in the abdominal and pelvic regions.  In the fetus, it extends into the<unk>  cord.
Umbilical artery
Vitelline arteries
Brachiocephalic vein
Circle of Willis
Iliac vein
Cephalic vein
Femoral vein
Internal jugular vein