Located in the rear and slightly to the sides of each vertebra, there are two top and two bottom hinges that connect the bone above and the bone below. These connections are called spinal joints or articulations. Just like any other joint in your body, spinal joints separate bones and at the same time allow them to move in very specific ranges of motion. Each joint is a uniquely shaped engineering marvel that acts as a frictionless hinge allowing for only a fraction of the motion in your spine. There are over seventy-five joints in the spine, and together they allow the entire structure to range more than 180 degrees, in any combination of up-and-down or side-to-side movements. The joint surfaces are a very hard, smooth, highly polished, slippery type of connective tissue called articular cartilage. The surfaces are separated by a thin layer of cushioning fluid, and the entire joint is held together by an extremely strong outer elastic capsule and connective wrapping called ligaments. The joints not only allow you to move, they also transfer weight and loads from one vertebra to the next without the bones ever touching each other.
Spinal joints are a lot like the highly polished steel shaft and casings of the hydraulic lifts you see on construction equipment. Because the bones are separated by lubricating fluid, the joints can transfer tremendous weight and pressure and still move with minimal effort. And while hydraulic lifts can move in only one direction, your joints provide movement and variability in many directions. Your spinal joints are much more than hinges. They are the strongest, most sophisticated, self-regulating, self-adjusting, and self-lubricating movement device ever designed by man or nature.
More Answers from Gerald M. Silverman