Chiropractic is a clinical science based on:
The law of biology that every body wants to be and stay healthy;
The theory of physiology that the nervous system controls and coordinates all the other organs of the body;
The hypothesis that there is a relationship between health and the control of the nervous system;
The premise that there is a relationship between the muscles and skeleton and nerves of the body, i.e. that a faulty musculoskeletal system will cause a faulty nervous system and produce a loss of health.
In other words, chiropractic is a clinical science based on the fact that the body wants to, and strives to, be healthy. An example of this is readily seen when you cut your finger or catch a cold. Without you doing anything consciously, your cut and cold eventually heal.
Chiropractic is also based on the fact that the nervous system controls and regulates all the functions of the body, from healing your cold to digesting your food to regulating pain. These nerves are protected by the bones of the spine; the skull protects the brain, and the 24 movable vertebrae protect the spinal cord and the 25 delicate nerve roots that come out of the spine. When these bones are out of position or don’t move properly, they rub, scrape, irritate, or stretch the nerves. The nerves then lose their ability to conduct electrical impulses, or life force. The organs that these nerves connect to cannot function at 100% if they don’t receive 100% of their nerve supply. The result is a loss of health.
Notice that I didn’t say that the result is pain. Most of the time there is no spinal pain, but there is a loss of health. This could be manifested as an upset stomach, bronchitis, asthma, constipation, menstrual cramps, or headaches, just to name a few of the conditions that have responded to chiropractic care.
To summarize, a vertebra that is out of place or doesn’t move properly can irritate a nerve, which causes an end organ to malfunction. This is a subluxation, and this is what chiropractors treat.