The Spinal Discs
Discs probably receive more attention than any other structure in the spine.
Most people learn about them in their damaged state — “bulging discs, ruptured discs, herniated discs.”
Discs are hydrodynamic, elastic structures spaced between two vertebrae, separating them and acting as shock absorbers.
Visually, they look like washers that space the vertebrae apart.
Several metaphors describe a disc, such as a tough jelly donut with a gooey inside, surrounded by a tough, fibrous, circular layer on the outside.
The gooey gel inside constitutes the nucleus pulposus, while the fibrous layered collagen sheets that envelop it constitute the annulus.
The nucleus gel of the disc is a blend of fibers, sugars, and acids. Its purpose is to absorb water and give it a spongelike function.
For the gel to maintain its hydrodynamic, water-absorbing function, it must receive nutrients like all other cells in the body.
In the early years of life, the gel is provided with nutrients via a blood flow through the vertebral segments above and below.
However, in the years of maturity, the vertebral bodies’ growth plates close, cutting off the critical blood supply to the discs.
From this point on, the gel matrix can only receive nutrients via a process that involves alternating compression and relaxation.
This pump-like effect allows nutrients to flow in and out of the central nucleus matrix from the surrounding annular ring layers and vertebral ends.
When the inner gel matrix is hydrated, it functions much like a tire with an internal pressure that separates the outer threads.
Think about how important it is for tires to stay inflated to effectively grip the road and how quickly the outer treads wear out when driven on low pressure, especially on curvy roads that require a great deal of turning.
When deflated they are sure to pop a flat.
The interior disc matrix functions in a similar manner.
It requires an internal pressure to spread the collagen fibers of the annulus outward so that those fibers can stay elongated and maintain their tensile strength to absorb shock and separate the vertebrae.
Of course, there are other variables that we will cover in the disc pathology section; but that, in a nutshell, is how discs work.
Imagine what happens to your discs if they don’t receive the mandatory alternating compression and relaxation, spongelike action that is essential for their health and function.
For example, if you sit all day long you do just that by squishing them constantly with no room for decompression.
Now imagine you combine excessive sitting and slouching with lots of bending and twisting.
You now have a deflated tire that is going to overstretch and possibly tear. Welcome to the world of bulging and herniated discs.