SPINAL ANATOMY Doctors of chiropractic are specialists in evaluating the causative factors in the bio-mechanical and structural derangements of the spine that affect the nervous system, and in treating these derangements to restore and maintain health. The health of the spinal column and the nerves that flow through it are central to the chiropractic philosophy. Optimum health, we believe, can only be achieved when this relationship between the spinal column and the nervous system is intact and allowed to function unimpaired. The nervous system consists of the brain, spinal cord and nerves. Nerve fibers relay impulses through this system to virtually every cell, tissue and organ of the body, controlling all bodily functions both voluntary and involuntary. The brain coordinates and controls the body's activities by sending impulses down the spinal nerve roots which emerge from the spinal column through small openings called the intervertebral foramen, which are located on each side of each vertebra. Spinal nerve roots are collectively made up of thousands of nerve fibers less than 1/100th the diameter of a human hair. To help the brain know how everything in the body is functioning, a feedback loop sends information from the tissues back to the brain in a system of checks and balances. The spinal cord, the pathway for almost all nerve impulses transmitted to and from the brain, is protected within 24 movable bones called vertebrae, as well as the lowest bones in the spinal column called the sacrum and the coccyx. Several components make the back a strong, yet flexible, structure. First, each vertebra has two bony projections called facets, which form a hinge with the facets of the adjoining vertebrae. A thin, soft intervertebral disc lies between two vertebrae. The intervertebral discs consist of a tough outer layer of cartilage and an elastic tissue, both surrounding a soft, gelatin-like material known as the nucleus. This soft, pulpy filling enables the nucleus of the disc to act as a shock absorber. The combination of the vertebrae and the discs provides flexibility in the spine. The spine's support comes from the ligaments, tendons and muscles that surround and attach directly to the spine. The back is also supported by muscles in the abdomen, hips, buttocks and legs. The muscles hold the spine in a long S-shape curve (when viewed from the sides but appears straight when viewed from the front or back) that keeps the body in its most balanced position. If the body is in proper alignment, the ears, shoulders and hips should all line up equidistant along a straight vertical line and horizontally parallel to each other and the ground. In this alignment, the physical strains endured by the spine and its supporting structures are evenly distributed throughout the back. The unique clinical concern in chiropractic is the unobstructed transmission of the spinal nerve impulses as they exit the spine. Misalignment of a vertebra can cause the exiting nerve to become stretched, impinged, entrapped, compressed, pinched or otherwise irritated. Since it is the purpose of the nervous system to coordinate the functions of the entire body, an obstruction, no matter how slight, can disrupt the body's delicate balance. This can predispose the body to pain, discomfort and even disease processes which might not have occurred had the nerve transmission not been altered. Therefore, it can be said that the unobstructed transmission of nerve impulses is of primary concern to the doctor of chiropractic.