Fear of Belly Buttons

That single fact does more to explain a fear of it than anything written under the phobia term, which is nothing at all. Searching for omphalophobia returns an anatomy article, and the anatomy article does not mention it.

What the scar consists of

The parts have names. The umbilical tip is the often protruding remnant of the cord itself, at the centre. Around it sits the umbilical collar, formed by the dense fibrous umbilical ring, and beyond that the periumbilical skin.

Directly behind the navel a thick fibrous cord called the urachus runs down from the bladder, which is a second and less visible remnant of the same arrangement.

The position is consistent enough to be used as a landmark. The skin at the level of the navel is supplied by the tenth thoracic spinal nerve, and the umbilicus typically sits at the junction between the third and fourth lumbar vertebrae, varying between the third and fifth.

How the shapes are classified

Because it is a scar, no two are the same, and medical practitioners have classified the general forms. The list is eleven items and it is worth setting out, because a body part with a formal taxonomy of shapes is unusual.

An outie is any navel where the tip protrudes past the surrounding skin, meaning any navel that is not concave. The variants of it:

• the swirly, where the scar forms a spiral
• the split, where a fissure cleaves the protruding scar and gives it the appearance of a coffee bean
• the protrusion, where the remnant is completely exposed
• the circlet, where the whole remnant sits outside the collar with a deep central fissure, producing a shape like a doughnut

An innie is any navel that is concave. The variants there are round, vertical, oval with superior, inferior or no hooding, T-shaped, and horizontal, the last being the least visible because the natural lines of the tendinous intersection fold over the scar. Anything that fits none of these is classed as distorted.

What a changed navel means

The clinical significance is the reason the anatomy matters here, and it corrects a common assumption. An outie is sometimes mistaken for an umbilical hernia and is a completely different shape with no health concern. A hernia is a protrusion of five centimetres or more, usually with a diameter of half an inch or more.

The shape of a navel can be altered slowly by diet and exercise. An unexpected change in shape may be the result of ascites, which is a reason to have it looked at.

Rarer conditions involve the navel directly: umbilical sinus or fistula, which in rare cases produces menstrual or faecal discharge from it, with menstrual discharge associated with umbilical endometriosis. Omphalitis is inflammation of the umbilicus in a newborn, usually bacterial.

To minimise scarring the navel is a recommended site of incision for several operations, including transgastric appendicectomy and gall bladder surgery, which means an existing scar is used to hide new ones.

Where the culture has put it

The navel has carried more meaning than most anatomy. During the early Jomon period in northern Japan, flat clay objects representing the female body were made with three small balls for the breasts and the navel, the navel exaggerated in size, informed by a belief that it symbolised the centre where life began.

Buddhism and Hinduism place a chakra at the navel, the manipura. In qigong it is the main energy centre, the dantian. In Hinduism, Kundalini energy is sometimes described as located there. Belly dancing in Arabic-Levantine culture is built around movement of the torso and navel.

Exposure has been governed by taboo in the West, banned in some jurisdictions, and has since become unremarkable, while remaining a long-standing feature of dress in India with saris and lehengas.

What a fear of it would be about

Nothing in the material describes omphalophobia, so what follows is stated as inference rather than as finding.

The navel is the visible remainder of a severed connection, a scar everyone carries from an event nobody remembers, sitting over a fibrous cord that still runs to the bladder. A reaction to being reminded of that is more intelligible than a reaction to a body part. The neighbouring aversions here, Trypophobia and Fear of Body Deformity, both fire on how the body looks rather than on what it means.

All placental mammals have one. There is even an account of a dinosaur, Psittacosaurus, preserved with a navel, shaped like the egg-laying rather than the mammalian type.