The dermis

	Just below the epidermis lies the dermis.
Skin

The dermis may fold over on itself several times,
as you can see on your face.

The supple and resistant dermis is much thicker than the epidermis.
Its water content is over 60%.
It is made of dense fibrous connective tissue, primarily collagen. Another fibre is elastin, your head has more of it.
Together they give your skin its super elasticity.
The dermis can repair itself and renew injured tissue.

Old and new dermis theory

This chapter is divided into two sections pertaining to;
•Traditional dermis theory,
•New dermis theory, introduced by the advent of grooming and the changes it brings to our comprehension of skin.

 

Traditional dermis theory

Dermis components

An area of your skin may contain various amounts of the following constituents. Some are found only in specific locations.

• Blood vessels

The dermis is laced with tiny blood vessels.
Capillaries find their way up into the epidermis.

• Free nerve endings

Bundles of nerves reach up into the epidermis.
These neurons communicate bilaterally with your brain, but also do so between each other, thus creating a neuronal grid all over your body.
Free nerve endings are responsible for detecting temperature, mechanical stimuli (such as pressure), pain, and touch information.

• Hair follicles with sebum glands

Hair is a compressed, filamentous creation of the skin found only in mammals.

Each hair follicle has:
•Blood vessels feeding it,
•Nerve endings (each one can feel),
•A muscle,
•One or more sebum glands,
•...

The hair is supposed to be loose at the top of the follicle.
If so, the sebum can escape through the free space around the hair in the hair shaft.
Even though humans are labelled as hairless apes, they have more hair follicles per square inch of skin than other great apes such as chimpanzees and gorillas.
You will find them everywhere on your body except on your palms, soles, lips, eyelids, penis, labia minora and nipples.

• Sweat glands

Called eccrine glands, most are part of your thermo-regulating system.
Sweat, almost all water, is cooled by your movements while it evaporates, thus reducing your internal temperature.

Some sweat glands are different. Those on your forehead, underarms, palm and soles respond to psychological stress.

• Specialized receptors

Some areas of your body also contain specialized nervous receptors.

They complement the information from the free nerve endings through tiny corpuscles.
What each one does precisely is still debated, but some seem to react more to specific types of stimulation such as heat, pressure, ...
There is an astonishing concentration of such receptors on your fingertips, making them the most sensitive part of you.

 

The hypodermis or subcutis

	Just below the dermis lies the hypodermis
Skin

This is a layer of fat between your skin and whatever lies beneath it, muscle, bone, organ, cartilage, gland, ...
The hypodermis is not necessarily considered as being part of the skin.
Your body uses it for insulation and as an energy reserve.
Blood vessels and nerves travel through it to reach into the skin.

 

New dermis theory

• Langer's lines

They are folds, not lines

«Langer's lines» is what they call skin folds in dermatology manuals.
Not understanding that the skin is folded, science has named this way what it could see of the folds.
It describes them as deep bundles of collagen inside the skin.
Surgeons try to cut on them, (when they can see them), in order to obscure the incisions they make.

Bad maps

The existing maps of these lines on the body resemble my horizontal and vertical folds illustrations.
I'm sorry to say that they are very wrong.
These are not lines, but folds.
And they cannot be seen, only felt.
  

• Sebum glands

Sebum glands were designed with grooming in mind.
There are about six times more of them on your head, where you are more folded and where more grooming is needed.
Known as «sebaceous glands», they are attached to the top of the hair follicle shaft.

Grooming and sebum glands

We've all heard about overactive sebum glands and their excessive production, possibly due to some hormonal imbalance.
Actually, their content is supposed to be expelled regularly when you groom your skin.
Here's how it works:
•As your fingertip and nail pass over your skin, they bend the base of the hair they encounter.
•This creates a mechanical pressure on the sebum glands to release some of the sebum.

As your fingertip curves the hair,
it forces out some sebum.

Because of this, sebum glands are;
•Big on smaller hair (neck) and
•Small on bigger hair (beard).

Sebum is a lubricant for grooming

Sebum, an oily, waxy substance that is unique to mammals, lubricates the skin while you groom.
It enables your nails to glide over the surface without tearing it.
Regular grooming frees the glands from their content.
Failure to do so has resulted, in our race, in huge glands compared to chimpanzees.
It also keeps hair and fur shiny, flexible, impermeable, ...

Several glands get trapped
inside fold crossings

Several hair follicles, including their sebum glands, stay imprisoned inside fold crossings.
The sebum they produce then flows into the crossing, where it accumulates.
These become blackheads or pimples.

Sebum glands almost everywhere

Your lips, eyelids, penis, labia minora and nipples are hairless, but they still have sebum glands. It reaches the surface through ducts.
Since your palms and soles have none, their skin is special. It is thicker and easily groomable. You can even see the folds there.
On a human fetus, these same sebum glands secrete the white substance called Vernix caseosa.
  

• Skin pores

Pores are very hard to see when they reach the surface of your skin.
When you think you can distinguish them individually, you are in fact looking at fold crossings.
They may be very close to one another and follow orderly patterns, but this simply confirms the presence of folds beneath them.
  

• Fingerprints

Papillary ridges and fingerprints

The top of the dermis is undulated, mostly on your palms and soles.
On the tip of your fingers, these ridges are commonly known as fingerprints.
When you look at your fingertips, you can see their design as nice rounded curves.
You can also spot many irregularities, with lines and holes modifying the motif.
I believe that these alterations are due to folds in the skin and the crossings they create.
You can see several of the bigger folds when your hands are wet.
  

• Skin orientation

Your skin is vertical

Skin is an organic tissue.
My suggestion is that the orientation of the skin’s various elements; cells, fibres, ..., follows a general horizontal-vertical axis.
We all are familiar with woven materials which exhibit a similar foundation.
We can also see it in our food.
This orientation favours straight, on-axis folding of the skin.
  

• Hair muscle

The «arrector pili» muscles actually pull your hair out of your skin.
This creates elevations called «goose bumps».
Under the control of the autonomic nervous system, they react to fear, cold, excitement, ...
Shivering is caused by these muscles contracting and relaxing cyclically, generating heat.
Unfortunately, the skin on your head is so folded that the muscles do not function.
Your hair should stand stiff on your head when you are emotionally charged, the way it does for some groomed primates.