In this section we discuss the anatomy of the human spine and what happens at a basic, structural, level when we experience back pain.
There are many things that can go wrong with the spine, but, in essence, up to 98% of all back pain is either caused by, or directly linked to, compression. That is the term used to describe the spine when it becomes squashed, or shortened from its natural length.
However, the spine is not a completely solid structure. If it were, it would be very difficult to compress. Instead, it is made up of individual vertebrae, or units of bone, that are stacked on top of each other, joined, or linked, by facet joints. Ultimately, it is the facet joints that become compressed and, as a result, the spine becomes squashed.
When this happens, we become stiff (a common symptom of back pain) because the joints are not able to move freely.
In addition to this, the compression reduces the space between the vertebrae, which, in turn, leads to compression of the intervertebral discs. If the pressure becomes too great, the disc ruptures, a condition commonly referred to as a herniated, or slipped disc (shown below).
Compression also causes the joints to rub together and, over time, they may become arthritic and painful (just like any other joint).
Finally, due to the way in which the spinal cord exits the vertebral column (a structure also known as the spinal column), compression can lead to nerve-root entrapment, a condition which is extremely painful.
Like any other form of pain, though, back pain is ultimately caused by damage to the human nervous system; the nerves simply produce pain in response to a harmful event (thereby alerting the brain of the problem). But, because the nervous system is responsible for many other activities, the effects of facet joint compression are wide ranging. Compression can also lead to referred pain (e.g. Sciatica), organ dysfunction and various other effects (e.g. Pins and Needles), as well as aggravating a whole host of bone conditions.
This section is designed to start at the beginning. We first examine the basic structure of the human spine, and then take a more detailed look at the individual vertebrae, what they look like and how they come together to form the spinal column. Next we look at the facet joints and explain how they lock the vertebrae together; we also examine what happens to the spine when they become compressed.
Finally, and we admit that things get slightly more complex at this point, we look at the human nervous system. We examine the nerves that exit the spinal column (and the brain), and divide the peripheral nervous system (PNS) into its various subcomponents. Next we discuss the function of the individual sub-systems, in terms of both sensory and motor components, and examine the symptoms of nerve-root compression.