The human navel, commonly known as the belly button or umbilicus, is a universally recognized feature on the abdomen. It represents a scar, marking the precise location where the umbilical cord once connected a developing fetus to its mother. Many people wonder about the internal structures to which this external landmark might be connected.
The Umbilical Cord’s Function
The belly button’s origin traces back to the umbilical cord, a temporary organ that serves as a lifeline during fetal development. This cord typically contains two umbilical arteries and one umbilical vein, encased within a protective substance called Wharton’s jelly. The umbilical vein is responsible for transporting oxygenated, nutrient-rich blood from the placenta to the growing fetus. Concurrently, the two umbilical arteries carry deoxygenated blood and metabolic waste products from the fetus back to the placenta for removal. Beyond these blood vessels, another structure, the urachus, provides a temporary connection between the fetal bladder and the allantois, which is part of the umbilical cord.
Changes After Birth
At birth, the umbilical cord is clamped and then cut, severing the physical link between the newborn and the placenta. This action signals the end of the cord’s physiological function. The remaining stump on the baby’s abdomen typically dries and falls off within one to three weeks, leaving behind the belly button as a scar. Internally, the vessels and structures that once coursed through the umbilical cord are no longer needed for circulation or waste removal. These pathways naturally close off and undergo a transformation, becoming non-functional, fibrous cords or ligaments.
The Internal Remnants
In adults, the belly button is internally connected to several specific fibrous remnants, which are the transformed structures of the fetal umbilical cord. The umbilical vein, which carried oxygenated blood to the fetus, becomes the round ligament of the liver, also known as the ligamentum teres hepatis. This fibrous cord extends from the belly button upwards to the liver, where it is found within the falciform ligament.
The two umbilical arteries, responsible for returning deoxygenated blood to the placenta, transform into the paired medial umbilical ligaments. These ligaments extend downwards from the navel towards the pelvis, located on either side of the midline. While the distal parts of these arteries become completely fibrous, their proximal segments may remain open, contributing to the blood supply of the bladder. Finally, the urachus, which connected the fetal bladder to the umbilical cord, becomes the median umbilical ligament. This single, unpaired ligament runs from the top of the urinary bladder to the belly button.
Abdominal Organs and the Navel
A common misconception is that the belly button maintains a direct, functional connection to internal organs such as the intestines or stomach. In reality, the belly button is a surface scar and does not have direct, active connections to the digestive tract or other major organs in adults. While many abdominal organs, including the intestines, bladder, and liver, are located within the abdominal cavity and are physically close to the navel, they are not functionally attached to it. The only internal structures linked to the belly button are the non-functional fibrous remnants of the umbilical cord discussed earlier. The navel therefore serves primarily as an external reminder of our prenatal development.