What Function Does the Belly Button Have?

While your eyelashes shield your eyes, your lungs enable breathing, and nearly every other part of your body—both inside and out—has its own well-understood role, your belly button mainly serves as a collector of lint. Despite this, it did serve a crucial purpose before your birth, and it still has some function today.

As ZME Science explains, your belly button once acted as a vital connection when you were a fetus: your umbilical cord extended from it and linked you to the placenta on your mother’s uterine wall. Through this connection, the placenta provided you with nutrients and oxygen while you sent waste back through the cord.

When you were born, your umbilical cord was cut, leaving behind a small bulge that eventually healed into scar tissue—what we know today as your belly button, navel, or umbilicus. Contrary to the popular belief that the shape of your belly button is determined by the doctor’s skill with scissors, this is actually untrue. Dr. Dan Polk, a neonatologist in Chicago, told the Chicago Tribune that a belly button's shape depends on the amount of skin from the baby’s body that extends onto the umbilical cord. Less skin results in an innie, while more skin creates an outie. Around 90 percent of people have innies.

No matter how your belly button appears, it's unlikely that you use it on a regular basis. However, for those who have studied anatomy, medicine, or a related discipline, it’s familiar as the central point for dividing the abdomen into four quadrants: right upper, left upper, right lower, and left lower. Alternatively, the area can be divided into nine regions, including the hypochondriac, lumbar, iliac, epigastric, and hypogastric regions, with the umbilical region at the center.

Your belly button also serves as an entry point for laparoscopic surgery, offering the advantage of avoiding visible scars on other parts of your abdomen.

Outside of the medical world, the navel is an important reference point as well. If you've participated in yoga or Pilates, you might have heard it called the center of balance or gravity. Since it lies directly over the abdominal muscles, the belly button becomes an easy marker for instructors to mention when guiding you to engage your core, aiding in balance.

And, of course, belly buttons are famous for collecting a surprising amount of lint, which always seems to be blue (you can read more about that here).