The 4 pillars of pain

Signals of overloads, injuries or dysfunctions are recorded by nerves and carried to the spinal cord. Ascending neural pathways bring the messages to the brain.

Pillar1.
Signals of overload or dysfunction from the musculoskeletal system and fascia are recorded by nerves from the "somatic nervous system"

Pillar 2.

Signals of overload or dysfunction from organs, hormones, circulation and immune system are recorded by nerves from the "autonomic nervous system".

Pillar3.
All pillar 1 and 2 stimuli are joined in the spinal cord and give rise to neural pathways to the brain centers.

Spinal cord and brain together form the "central nervous system".

Pillar 4.
In the middle of the brain lies an area called limbic system, in which the incoming stimuli are compared with emotions, stress factors, learning processes, environmental factors, etc. All these factors can strengthen or dampen the stimulus transfer.

The communication between the nerves from the four pillars is done by chemicals or "neurotransmitters."
Some neurotransmitters are very stimulating, while others are very dampening.
Moreover, all this can still be influenced by hormones from the circulatory system and immune system that can also strengthen or dampen the signals.

When and how does pain occur and to what extent is the severity of the pain determined?

All signals from the body, emotions, learning processes, environmental factors and other are processed in the brain by an interplay of neurons connected in circuits.  

A "pain circuit" occurs when the various brain centers decide that there is a threat, a danger. That pain circuit can in turn be strengthened or tuned down.

A fear circuit (e.g. fear of moving in case of back pain) on top of the pain circuit will strengthen the pain.

A motivation circuit (e.g. this is not bad, I have to continue) can weaken the pain circuit.

So, the brain decides, regardless of the severity of the damage, how severe the pain will be.

Pain is therefore more likely to be seen as a "friendly" signal, a protection factor.

How big that protection factor will be depends on emotions, memory, learning processes and environment factors.

Important!

Pain is not only caused by overloads or functional disorders in the body.
Emotions, traumatic experiences or psycho-emotional overload directly disrupt the centers in the limbic system. As a result, they can cause numerous changes throughout the body, including physical pain.
Read more about this in the article about stress, burn-out and fybromyalgia under the heading  "More information".