Chiropractic is likely the most common form of alternative complementary medicine that people have experienced. Chiropractic uses manipulation of joints. Their theory is that nervous system function is improved by improving musculoskeletal function. In brief, looking at the spine specifically, the anatomy is such that the nerves emerge from the spine and move through foramina in the spinal column to their various end points. It is felt by chiropractors that subtle subluxations of the various spinal vertebrae can affect the function of these nerves as they emerge from the spinal canal. By adjusting the subluxations, one can achieve more optimal nervous system function. It has also been shown that spinal manipulation causes the release of endorphins and enkephalins, the body's androgenous painkillers. Chiropractic has also been shown to be helpful in the treatment of addiction. This may well be because of its release of these androgenous pain killers.