The vertebrae serve as a "suit of armor" for the spinal column. Nerves, from the spine, project out to the body from the contoured spaces between the vertebrae.
When these spaces change in size due to misalignment of the involved vertebrae, a subluxation occurs. This means that the nerve is being pinched ( little or more ) and signals are not being conducted along that nerve as well they should be (or not at all ).
Hinder the nerves communication and the brain has less than 100% access to the body and the body has less ability to help itself to function normally and be healthy and/or heal.