Back extensors

So far I have described the structure and function of the four muscles of the abdominal group, but there are other muscles that attach to, and provide stability, for both the lumbar spine and pelvis. The next group of muscles I would like to discuss are called the lumbar extensors or lower back muscles.

As I mentioned previously, the abdominal muscles are connected to each other, and also the bones of the skeleton, by strong connective tissue known as fascia. The strongest sheet being the thoracolumbar fascia that attaches the oblique muscles to the lumbar spine, bottom of the rib cage, and the top of the pelvic girdle. Its structure consists of numerous layers whose fibers run in opposing diagonal patterns to provide stability to the trunk region, to not only provide the strength to resist the outward pressure exerted by the contents of the abdominal cavity, but also the contractions of the numerous muscles.

The back extensors are strong bundles of muscles that attach to the top of the posterior pelvic girdle and run up the lower back, middle, upper back, neck, and connect to the bottom of the posterior skull. The strongest groups of these muscles are the ones that span the length of the lumbar spine and are encapsulated between the strong sheets of tissue of thoracolumbar fascia. This fascia holds these muscles in place and allows them to perform the function of lumbar extension. They create an upward pull on the posterior portion of the pelvic girdle, neutralizing the upward pull exerted on the anterior portion of the pelvis by the abdominal group, and providing lumbar stability and prevention of excessive torque and risk of injury to the lumbar spine.

The best exercises for isolating and strengthening this muscle group, are called back or trunk extension exercises, and I will provide a video in the next few days in the training tips section on the home page demonstrating these.