The navel, or umbilicus, is a familiar feature on the human body, yet many people wonder about its purpose since it serves no obvious function in adult life. It is essentially a biological remnant, marking our earliest connection to the world. The belly button’s role is defined by two phases: its temporary, life-sustaining function before birth and its current, non-functional status as a scar.
The Navel’s Role in Fetal Development
The structure that creates the navel begins as the umbilical cord, a temporary connection forming the lifeline between a developing fetus and the placenta. This cord is necessary for sustaining the fetus throughout gestation. It is a conduit containing two umbilical arteries and one umbilical vein, all embedded within Wharton’s jelly.
The umbilical vein transports oxygenated, nutrient-rich blood from the placenta directly to the fetus. The two umbilical arteries carry deoxygenated blood and metabolic waste products from the fetal circulation back to the placenta for removal. This bidirectional system ensures the continuous supply of elements required for organ development, cell division, and growth. The entire structure represents a vital, temporary organ enabling fetal life within the womb.
Current Purpose and Anatomical Structure
In the adult body, the belly button has no physiological function related to circulation, digestion, or respiration. It is a permanent scar that results from the natural process of birth and the subsequent healing of the umbilical cord site. After a baby is born, the cord is clamped and cut, which leaves a small stump attached to the newborn’s abdomen.
The stump typically shrivels and falls off within one to two weeks after birth. The skin and underlying tissue then close and heal, forming the scar known as the navel. Internally, the remnants of the umbilical vessels and other embryonic ducts close off and become thick, fibrous cords or ligaments attached to the abdominal wall. The resulting navel is an anatomical landmark, which healthcare providers often use as a reference point to divide the abdomen into quadrants for diagnosis and treatment.
Innies, Outies, and Common Medical Issues
The final appearance of the navel, whether it is an “innie” (concave) or an “outie” (convex), is determined entirely by how the scar tissue forms during the healing process. An innie is a depression formed when the scar tissue pulls inward, and this is the shape that occurs in approximately 90% of people. An outie forms when the remaining tissue from the cord stump protrudes outward instead of retracting inward.
While most outies are a normal variation, a common medical issue, particularly in infants, is an umbilical hernia. This occurs when a small opening in the abdominal muscles does not close completely, allowing a loop of intestine or fatty tissue to push through the gap and create a bulge. Most umbilical hernias in children resolve on their own by age five, but they may require surgical repair if they persist or cause complications. The navel’s shape also makes it a site prone to collecting lint and debris, and it can harbor a diverse microbial community, making proper hygiene important to prevent minor infections.