Understanding Back Pain: The Soft Tissues

In part 1, we looked at the bony structures that make up the spine and pelvis. We discussed normal spinal curvatures and how their alignment allows for optimal function. We introduced the concept that alterations from normal structure contribute to spinal joint dysfunction, de-conditioning and ultimately degradation and pain. In this issue, it will become apparent that it is equally as important to understand the role of the soft tissues (muscles, ligaments) to know how your spine works.

Recall that a spinal joint consists of two vertebra and the disc in between. There are ligaments, which are pieces of rubber band like tissue, that connect the bones together and help to maintain proper alignment. In a protective way, ligaments limit the movement of a joint by the amount of stretch that they have. But a joint cannot move unless a muscle exerts a force or a pull on it. Hence optimal spinal function is dependent upon the muscles that move it and the ligaments that protect it.

Each vertebra forms with specific protuberances called “processes” which act as levers to which the muscles attach. With this lever, a muscle can exert a pull in a specific direction dependent upon what it is designed to do. Therefore, the musculoskeletal system is simply a machine with moveable parts that work in a lever and pulley fashion. Anywhere within the system problems can arise, often without a provocative factor, causing back pain.

The muscular system is designed in layers, the largest on the outside to the smallest on the inside. Large muscles tend to attach to groups of vertebrae and contribute to maintaining posture or carrying out big movements by working in groups. Smaller muscles have more specific functions as they get closer to the spine. Ultimately there are very small muscles which attach each vertebra together so that they control the movement of a joint in a specific direction, such as rotation (twisting), lateral bending (side to side bending) or flexion and extension. It is this group of muscles, the very small, deep inter-vertebral muscles, which are often the culprit in idiopathic back pain. Finally, dispersed throughout and between all these structures are little nerves which control, monitor and coordinate all aspects of spinal joint movement. Because pain is mediated through the nervous system, it is clear that joint and muscular dysfunction will cause these nerves to become irritated and inflamed, the end result being pain and joint incoordination.

We have now seen how in addition to the spinal joints, the deepest soft tissues that attach to the spine are important structures in maintaining spinal function and health and in understanding back pain. Injuries or problems with these tissues result in spinal joint dysfunction which in turn will cause further stress on the muscles involved, perpetuating a vicious cycle of dysfunction, pain and musculoskeletal breakdown.

The final step in knowing how your spine works is to understand the role of the nervous system and pain. The next issue will address the basics of joint dysfunction and nerve irritation in back pain.