A spinal nerve is rarely compressed by a misaligned vertebra. When a spinal nerve is compressed, usually by disc herniation or osteophyte formation, symptoms occur in the musculoskeletal structures supplied by the affected nerve but the body’s organs are not affected. Severance of the spinal cord at or above the 4th cervical vertebra, shutting off brain impulses to spinal nerves, can cause paralysis of muscles from the neck down while the body’s organs continue to function.
Although the original theory of chiropractic defines a subluxation as a vertebral misalignment that places pressure on a spinal nerve, more recent theories define a subluxation as a “vertebral subluxation complex” that affects nerve, blood vessel, and connective tissue structures in a spinal segment, causing nerve interference without misalignment of a vertebra. Both types of subluxations are alleged to affect general health; neither has been proven to exist. Nevertheless, it is common practice among chiropractors to treat a health problem by adjusting the spine to “realign the vertebrae” or to “remove nerve interference.”