In very simple terms a Subluxation is a trapped nerve. Nerve tissue is soft and pliable and therefore very susceptable to pressure, stretching and or twisting. Any alteration to the tension on the spinal cord or nerves will result in impaired function of those nerves. As the Central Nervous System is housed within the skull and spine any tension here will affect the nerves and cause altered nerve function.
Subluxations are caused by any stress the body cannot properly deal with. DD Palmer called this 'an unbalanced concussion of forces'. It is not the size of the stress alone but more how we interact with it. Many people can deal with large forces seemingly without harm while others react to even the smallest upsets. We can devide these forces into three subgroups, PHYSICAL, MENTAL, CHEMICAL.
Any physical activity may lead to subluxation. Including knocks, falls, car accidents, sports injuries, bending twisting lifting and even the birth process itself.
Sedentary or passive activities such as being seated at a desk, driving or working in an awkward position can also cause subluxations. The onset is more insidious but the effects are just as devastating.
Mental stresses that you do not recover from may cause subluxations that persist in your body. As a simple example, depressed people tend to look down which stresses the spine. Hence we may have a 'body language' that gives away our mental state. We even have language to reflect this such as "He has the weight of the world on his shoulders" ,"my boss is getting on my back" or "my spouse is a pain in the neck".
When the body cannot properly deal with its chemical load it may subluxate. Exposure to Dusts, Fumes, liquids, smog, and any chemicals can cause stress on the body. We must not forget that all Foods and Drugs (prescription or not) are chemicals that interact with our bodies and my cause subluxations.