umbilical cord, a flexible structure connecting the umbilicus with the placenta in the gravid uterus and giving passage to the two umbilical arteries and the umbilical vein. In the newborn it is about 2 feet long and ½ inch in diameter. First formed during the fifth week of pregnancy from the connecting stalk, it contains the yolk sac, stalk, and allantois. Also called chorda umbilicalis, funiculus umbilicalis. See also allantois.
