Pain is psycho-somatic. What does that mean & why do you care?
This means that pain has physical (somatic) and psychological (psycho) components. The fibers that conduct pain in the body begin as receptors peripherally in the skin & tissues and enter the spinal cord. They then travel thru a portion of the spinal cord known as the spinothalamic tract and eventually transmit to the primary somatosensory cortex of the brain which also sends fibers to the secondary somatosensory cortex of the brain. In theses areas of the brain physical pain is perceived and localized. The same area of the brain functions as the memory of sensory input.
This is anatomically why pain is psychosomatic. Because pain can be felt physically in a moment due to a stimulus yet it can also be perceived by the brain via the triggers of experience and memory. The affects of pain on things such as the immune system and mood are subjects of current study.
Since daily choices play an integral role in how we experience and thus remember life the idea that the perception of pain (psycho or somatic) can be affected via physical and psychological factors is a powerful one. This is why Chiropractors emphasize wellness care which means care to prevent sickness as opposed to sick care which is to remedy after sickness has incurred.