The navel, known clinically as the umbilicus, is an anatomical feature found on the abdomen of all placental mammals. It represents the remnant of the temporary structure that was the sole physical connection between a developing fetus and the maternal placenta. Its formation results from a specialized biological process, but its final appearance is determined purely by the body’s natural healing response.
The Navel’s Origin and Adult Function
The navel is fundamentally a scar left behind after the umbilical cord detaches following birth. Before birth, the umbilical cord functions as a biological highway, transporting materials between the fetus and the placenta. The cord typically contains three blood vessels: one umbilical vein and two umbilical arteries, encased within a protective, gelatinous substance called Wharton’s jelly.
The single umbilical vein carries oxygenated, nutrient-rich blood from the placenta to the fetus. Conversely, the two umbilical arteries transport deoxygenated, waste-carrying blood away from the fetus and back toward the placenta. Once the newborn begins breathing independently, blood flow through these vessels is no longer needed, causing them to naturally close and shrivel.
After the cord is clamped and cut, the remaining stump dries out and typically falls off within one to three weeks. The resulting tissue heals and forms the navel. In adulthood, the navel serves no active biological function; the remnants of the vessels become fibrous cords within the abdominal cavity. Healthcare providers use the navel as a reference point for surgical procedures and for dividing the abdomen into quadrants during physical examinations.
Understanding Anatomical Variations
The appearance of the navel is determined by how the scar tissue heals, and has no relation to how the cord was cut at birth. The two most common forms are the concave “innie” and the protruding “outie,” with the innie being the shape for approximately 90 percent of people. The inverted shape forms when the skin attaches and heals inward over the closed umbilical ring.
An “outie” navel, occurring in about 10 percent of the population, results when the scar tissue protrudes outward instead of adhering inward. A common cause for a protruding navel is a minor umbilical hernia, where a small part of the intestine or fatty tissue pushes through a weak spot in the abdominal wall. In infants, these small hernias are usually harmless and often close on their own by the age of two to five years.
In adults, an innie navel can temporarily convert to an outie due to increased internal abdominal pressure, such as during pregnancy or significant weight gain. The final shape is primarily dictated by the amount of scar tissue, the structure of the surrounding abdominal muscles, and the thickness of the subcutaneous fat layer.
Basic Care and Minor Medical Issues
Because the navel is a small depression in the skin, it can easily trap debris, including lint, dead skin cells, and sweat. This accumulation can encourage bacterial growth, sometimes leading to an unpleasant odor or mild irritation. Regular hygiene involves cleaning the area with mild soap and water during a shower.
It is important to dry the area thoroughly after washing to prevent moisture from encouraging the growth of yeast or bacteria. A cloudy discharge, often accompanied by redness, can indicate a minor surface skin infection caused by common bacteria. This localized infection can often be managed with careful cleaning and, if needed, a non-prescription antibiotic ointment.
A more serious, though rare, condition in newborns is omphalitis, a bacterial infection of the umbilical stump tissue. Symptoms like persistent redness spreading from the navel, tenderness, or a foul-smelling discharge require immediate medical attention. Omphalitis can quickly lead to a broader systemic infection, while a sudden, painful bulge in adults could signal an incarcerated hernia, which requires prompt evaluation.