Whatever your opinion of the navel, one thing is certain - it has already attached you to your mother. The umbilical cord is cut at birth, leaving only a small stump that gradually withers and falls off a week or two later.
What remains, in most cases, is a small wrinkled depression. That's if you have an inward navel, as the majority - 90% apparently - do. From this point on, the belly button seems to become redundant - apart from attaching dust and fluff.
But that's not the whole story - your belly button has more depth than just a few millimeters.
The umbilicus is an access point for the vessels that carry blood to and from the fetus. These come from the placenta and run through the umbilical cord, coated in Wharton's jelly, a gelatinous connective tissue contained in the cord that insulates and protects them.
Normally, there are three vessels within the umbilical cord. The one that carries oxygen and nutrients to the fetus is the umbilical vein. It passes through the navel and feeds the circulation of the developing fetus. There are also two umbilical arteries, although these carry deoxygenated blood and waste products, which flow in the opposite direction, back to the placenta.
This circulation is not needed after the baby is born and, once disconnected from the placenta, the umbilical vessels close naturally. However, the small section of cut umbilical cord that remains attached can still be useful for a short time, especially in newborns with health problems. The vessels can be fitted with drip tubes and used for infusions of medication, or blood samples can be taken from it for analysis.
The umbilicus is a portal in the wall of the abdomen - a little-known fact is that during embryonic development, the intestines have to leave the abdominal cavity due to limited space, but return a few weeks later. They do so through the navel, passing into the umbilical cord.
The navel is therefore not only a point of access, but also a point of weakness. An umbilical hernia occurs if a section of intestine enters through any opening. An operation may be necessary to correct it.
The nun and her belly button
Poor Sister Mary Joseph Dempsey. Mary was a nun who dedicated much of her life to caring for patients in a hospital in Minnesota, USA. She trained as a nurse and later became William Mayo's surgical assistant. It was during this period that she made an interesting observation.
At that time (late 19th century), cancers of the abdomen and pelvis were usually diagnosed much later and, unfortunately, were often more extensive. We call this process metastasis, when a cancer starts in one organ or place and then spreads to another.
Mary noticed that some patients with metastatic cancer had a new swelling or palpable lump in their navel. She then took the noble step of reporting this to Mayo, who had obviously not noticed it. The surgeon then published these findings under his own name, without giving due credit to his esteemed colleague. It was only after Dempsey and Mayo's death - both in 1939 - that another doctor, Hamilton Bailey, correctly called the finding Sister Mary Joseph's nodule.
The nodule is firm, variable in color and is actually the result of cancer spreading to the umbilical tissue. Nowadays, this is not so common, as more and more cancers are diagnosed earlier, before extensive spread occurs.
Medusa's head
There are other signs on the navel that have a basis in mythology. One example allows us to establish a link between the liver and the navel.
The skin around the belly button has beds of superficial veins that flow back into the deeper circulation. In fact, they drain blood into the hepatic portal vein, a large vessel heading towards the liver, full of nutrients absorbed from the intestine.
If the pressure in the portal vein becomes too high (mainly as a result of liver diseases such as alcoholic cirrhosis), the pressure also increases in the connecting vessels. Veins have thinner walls than arteries and tend to dilate under pressure.
As a result, the small veins around the navel dilate in size and become visible under the skin, spreading out in all directions. This sign, resembling a head full of snakes instead of hair, is called caput medusae, or Medusa's head. In Greek mythology, Medusa, whose head was cut off by the hero Perseus, had the ability to turn anyone who looked at her into stone.
And on this topic, all the dirt, debris and dead skin in our navels should also receive an honorable (or perhaps dishonorable) mention - the prolonged accumulation of this material inside the cavity can cause it to harden over time, forming a stone mass. We call this an omphalolith, or umbilical stone.
Thus, the navel is a kind of reliable crystal ball for diagnosing internal illnesses. But if you consider it an attractive part of your own anatomy, you have to ask yourself the following question: do you have an inward or outward navel?
