The navel, or umbilicus, is a universal feature found on every person. This small mark, commonly known as the belly button, is the scar that remains from the temporary organ that sustained life before birth. It is a profound biological signature tracing back to our earliest development. The structure of this scar is a direct result of how this temporary connection was formed and how the body healed after it was no longer needed.
The Necessity of the Umbilical Cord
The existence of the belly button is explained by the necessity of the umbilical cord during gestation. This cord functions as a biological lifeline, connecting the developing fetus to the placenta for circulatory exchange. The cord contains three vessels: one umbilical vein and two umbilical arteries, suspended in a protective, gelatinous substance called Wharton’s jelly.
The umbilical vein transports oxygenated, nutrient-rich blood from the placenta to the fetus. The two umbilical arteries carry deoxygenated blood and metabolic waste products back to the placenta for removal. This circulatory system is necessary because the fetus’s lungs and digestive tract are not functional in the womb. Once the baby is born and begins to breathe and feed, the cord’s purpose is fulfilled. It is clamped and severed, leaving a small stump that dries up and detaches within a few weeks, leaving the navel.
Anatomy of the Navel Scar
The belly button is a permanent scar composed of fibrous tissue that seals the former entry point into the abdominal wall. After the umbilical stump falls off, the internal blood vessels that were part of the cord close up and degenerate. The umbilical vein transforms into the round ligament of the liver, and the two umbilical arteries become the medial umbilical ligaments. These former vessels become internal, ligament-like structures that anchor the navel area but serve no circulatory function in the adult body. The navel is simply a surface scar attached to the fascia beneath the skin. It serves no active biological purpose, marking a profound developmental history.
Common Shapes and Required Care
The different appearances of the navel are broadly categorized as “innies” (concave) or “outies” (protruding). The final shape is determined by the natural process of scar formation, influenced by how the underlying skin and scar tissue heal and pull inward, the structure of the abdominal wall, and surrounding body fat. The way the umbilical cord is cut by a healthcare provider does not determine whether a person has an innie or an outie.
Most people, about 90%, have an innie, which is a depression in the skin. An outie, occurring in about 10% of the population, forms when the scar tissue protrudes slightly outward, sometimes involving a minor umbilical hernia that resolved naturally. Routine care for the navel is minimal and involves simple cleaning, as the indentation can accumulate lint and dead skin cells.