The belly button, or umbilicus, is a distinctive anatomical feature on every human abdomen. It forms as a natural consequence of birth, specifically from the healing process after the umbilical cord is severed. This cord connected the developing fetus to the placenta, serving as a conduit for nutrients and oxygen. Once cut, the remaining stump dries and detaches, leaving behind the unique scar known as the belly button.
The Anatomy of Depth
The visible depth and appearance of a belly button are not standardized but result from several individual anatomical factors. The initial healing of the umbilical cord stump plays a significant role in its final shape and depth. The way skin and underlying tissues retract and scar varies, determining whether the navel appears as an “innie” or an “outie.”
Variations in abdominal muscle tone and the distribution of subcutaneous fat around the navel also contribute to its perceived depth. A more defined musculature or less fat in the surrounding area can make the belly button appear deeper, while a softer abdominal wall might lead to a shallower appearance. The elasticity of the skin influences how taut or relaxed the skin around the umbilicus appears, affecting its contour and depth.
In some instances, an umbilical hernia can alter the belly button’s appearance and apparent depth. This occurs when a small portion of abdominal contents pushes through a weak spot in the abdominal wall near the navel, causing a protrusion. While it can change the external shape, it does not represent a deep internal opening.
What’s Behind the Belly Button?
Despite its appearance, the belly button is a completely closed scar and does not provide a direct opening or deep cavity connecting to internal organs. It is fundamentally a part of the abdominal wall, a robust, multilayered structure that protects the abdominal cavity. The skin and connective tissues at the navel are securely fused, creating a sealed surface.
Internally, the belly button is associated with remnants of structures active during fetal development. These include the umbilical arteries and the umbilical vein, which, after birth, transform into fibrous cords known as umbilical ligaments. These ligaments extend from the navel region to other internal structures within the pelvis and liver. They are solid, non-functional fibrous bands, not open vessels or pathways.
The common misconception of the belly button being a “hole” or directly connected to digestive organs like the intestines is inaccurate. It is a superficial scar integrated into the abdominal wall, serving as a testament to our prenatal development without providing direct access to the body’s interior.