The belly button, or navel, is a scar marking where the umbilical cord once connected a developing baby to its mother. This indentation originates from the link that sustained life during pregnancy. Understanding its formation and internal connections reveals how the body adapts after birth.
The Umbilical Cord: Life’s First Lifeline
The umbilical cord serves as a conduit during prenatal development, linking the fetus to the placenta. It facilitates the exchange of substances for growth. Oxygen and nutrient-rich blood flow from the placenta to the fetus.
It also transports deoxygenated blood and waste products away from the fetus to the placenta. From there, these waste materials are processed by the mother’s body. The cord contains two umbilical arteries and one umbilical vein, encased within a gelatinous substance called Wharton’s jelly.
From Cord to Navel: The External Transformation
After birth, the umbilical cord’s function ends as the baby’s organ systems operate independently. Healthcare providers clamp the cord in two places and then cut it between the clamps, a procedure painless for both mother and baby.
The remaining stump, usually a few centimeters long, is left attached to the baby’s abdomen. This stump naturally dries and shrivels over several days to a few weeks. It then detaches, leaving behind the characteristic navel, which is essentially a healed scar.
Internal Connections: Remnants of the Umbilical Cord
While the external umbilical cord stump detaches, internal remnants persist. These transform into fibrous cords or ligaments, adapting the body from fetal circulation to independent life. The single umbilical vein, which carried oxygenated blood to the fetus, becomes the round ligament of the liver, also known as the ligamentum teres hepatis.
This ligament extends from the deep surface of the navel to the liver, where it joins the left portal vein. The two umbilical arteries, which carried deoxygenated blood away from the fetus, transform into the medial umbilical ligaments. These paired structures run from the internal iliac arteries, alongside the bladder, and ascend towards the navel.
Another remnant is the urachus, a fetal tube connecting the bladder to the umbilical cord, which drained fetal urine. After birth, the urachus obliterates and becomes the median umbilical ligament. This single ligament extends from the apex of the bladder to the navel, situated in the midline of the lower abdominal wall.
What These Internal Connections Do Now
In adulthood, the internal remnants generally become non-functional fibrous cords. The round ligament of the liver, for instance, no longer carries blood but serves as an anatomical landmark within the liver. Similarly, the medial umbilical ligaments primarily provide structural support and are used as landmarks during surgical procedures, such as those involving the pelvis.
The median umbilical ligament, formed from the urachus, exists as a fibrous band that helps anchor the bladder. While these structures have no active physiological role in adult life, their presence is a normal consequence of fetal development. In rare instances, incomplete closure or persistence of these fetal structures can occur, which may lead to minor medical considerations.