A fold starts out as a groove in your skin, an inward indentation with very little consequences.
But, at some point, the fold becomes permanent and the consequences on your health increase greatly.

A fold crossing is the place where two cutaneous folds meet.
You can find thousands of them all over your body.

Fold crossings start out as simple skin deformations, but they keep on growing and deepening all your life.
Fold crossings have several repercussions, but the two main ones are:
• Pain; most of the pain you feel comes from fold crossings,
• Skin defects and disorders; visible aesthetic deteriorations.

MAIN FOLD CROSSINGS ON THE FOREHEAD

As a person ages, several extra folds (sometimes diagonal) will be added in between the ones pictured above.

First, let’s separate the two folds of the crossing and call them; Fold A and Fold B.

Very early in your life, Fold A and Fold B started meeting when you would do a particular movement.
At first, they probably did not meet at the exact same place every time.
With time, the path of each fold became etched into your skin, under the action of the skin's wound-healing process; superficial cicatrisation.
The location of their crossing point became a fixed point.

A FOLD CROSSING HAS FOUR CORNERS

Once a crossing point is fixed in one location on your body, it becomes an anchor.
Any tension in the neighboring skin is relayed to the fold crossing.

Once the two folds become permanently engraved in the skin, their walls crash into each other, at the same point, every time you do the same movement.
At the crossing's center, the skin is badly and continuously deformed.
All this action generates heat.

The heat is a signal for your skin that it is being mistreated and that it may not be able to resist, if the damaging action doesn't stop.

Fresh epidermis cells, triggered by the skin's wound healing process, superficial cicatrisation, will come to the rescue of the poor crossing in order to prevent breakage or puncture.
One by one, coats of protective epidermis cells solidify the crossing's center.

EPIDERMIS LOCKS THE CENTER OF THE FOLD CROSSING

The newly added cells solidify the skin of the mistreated region, but they lock the crossing into place even more.

Over 95% of your fold crossing cannot be seen, along with the folds that generate them.
Since the folds and crossings are already made of epidermis, and that they get filled with epidermis cells to protect the skin; they cannot be observed easily.
It's epidermis over epidermis.
However, you can see a few of them in some places, such as the palms of your hands and feet and your face.
Normally, only problematic fold crossings will catch your attention.

MAIN FOLD CROSSINGS ON THE PALM OF THE HAND

The folds of a crossing often cross each other perpendicularly.
Since your most fundamental folds are vertical and horizontal, their intersections are straight.
But, your actions, positions and expressions distort the folds and create all kinds of new local folds that are often diagonal.
So, the shape of the fold crossings you'll find on your body is of your own making, and you'll discover all kinds of configurations.

The four corners of the fold crossing almost completely encase its center.
But, there remains a void.
With time, this structure solidifies, developing into a tunnel made of skin.

Even if the top of the fold crossing gets covered with coats of epidermis cells; there still remains a cavity.

Since folds A and B are already grooves, not mounds, the fold crossing is a hole.

As they evolve and fixate, fold crossings grow deeper and deeper below the surface of your skin.

Dimples are fold crossings

Each time epidermis formation paves the fold, it strengthens and hardens it.
Each new coat finds a new, evolved situation.
Conditions have changed slightly.
This results in a different epidermis structure for each new coat.
As the number of coats increases, unfolded skin at the top is pulled down, and the whole edifice deepens into the flesh.

When you groom a fold, it unfolds coat by coat.

The tensions on the chimney, in the center of the fold crossing, keep on increasing with time.
The fold crossing deepens.
The bottom of the crossing becomes riveted to whatever is beneath it.

The tension and grip from the thousands of fold crossings on your body, on whatever lies beneath them, augments continuously.
The consequence is that your skin becomes tightly fastened to your body.
It's as if your skin was shrinking on you.

The top opening of a fold crossing tunnel normally stays open.
When this is the case, the larger ones may be noticed as holes, cavities and oversized pores.
However, superficial cicatrisation often forms a cap that closes the top of the crossing.
When this happens, the outgrowth can keep on developing and become esthetically displeasing.
But, the real problem comes from the entrapped bodily wastes that remain locked-up inside the tunnel.

Your skin’s natural horizontal and vertical folding tendency ends up creating a grid of folds and crossings all over your body.

A fold crossing is always under tension.
It's like being in the center of a four-way tug-of-war.
Any movement you make pulls on the skin somewhere, and this tension is relayed to the neighboring fold crossings.
In many cases, the tension becomes so great that pain arises.

When you're inactive, the tension on your fold crossings may be equal on all four sides.

Stable fold crossing

But, when you move, your actions pull on the skin and consequently on the folds and their crossings.
The nearest fold crossings are destabilized by the tug coming from one direction.
In some situations, pain may appear.
The tension on one crossing is relayed to all the crossings in its vicinity, but mostly to the adjoining crossings on the same fold.

Destabilized fold crossings

The grid of fold crossings has several disadvantages;
• It greatly reduces the skin's flexibility and elasticity,
• It spreads the pain to adjoining regions,
• On the face, expressiveness and beauty are diminished,
• It interconnects problem areas,
• Doing one movement now affects regions further and further away,
• ...

Because the size of your body has increased since your youth; the grid has tightened continuously.
It is deepening into your flesh.
It's as if you were still wearing the clothes you wore in your youth.

With time, the folds and crossings multiply, enlarge and squeeze your skin still more.
This reduces your capacity to move, and makes anything you do more painful as you get older.