Thoracolumbar Fascia and Your Lower Back Pain

Thoracolumbar fascia pain affecting your lower back is linked to tissue that's found behind the spinal column and positioned at both the lumbar (low back) and thoracic (mid-back) levels.

This fascia tissue—thick connective tissue that covers, organizes, and supports all the muscles, bones, tendons, ligaments and organs of the body—contains nerve endings that may cause pain due to injury or inflammation.

The pain and stiffness affect the thoracolumbar fascia, also called the lumbodorsal fascia or simply LF.

What the Thoracolumbar Fascia Does

When you look at the thoracolumbar fascia from the back view of an anatomical drawing or diagram, you can see that it makes a diamond shape. Because of this shape, its large size, and its fairly central location on the back, the LF is in a unique position to help unify the movements of the upper body with those of the lower.

The fibers that make up the LF fascia are very strong, enabling this connective tissue sheath to also lend support. But fascial tissue also has flexibility, as well. It is this quality that enables the LF to help transmit forces of movement as the back muscles contract and relax. And the thoracolumbar fascia is a key player in contralateral movements. A perfect example of this is the act of walking.

Back Pain and the Thoracolumbar Fascia

Scientists and doctors don't know for sure, but it's possible that the lumbodorsal fascia may play a role in the presence of low back pain. A 2017 study published in the journal Biomedical Research International found that the lumbodorsal fascia may generate back pain in three possible ways. 

First, if you sustain micro-injuries and/or inflammation—often the two are related—these may stimulate changes in the free nerve endings that live in the fascia. Free nerve endings are, as the name suggests, the ends of nerves that arise from your central nervous system, i.e., your brain and spinal cord. Their job is to pick up information at the outer reaches of your body such as your skin and fascia and relay it back to your central nervous system. As the theory goes, when the fascia that's close to your skin, as the LF is, becomes damaged or infused with inflammatory substances these "insults" are communicated back up to your brain and spinal cord for processing and response.

Second, after an injury, it's common for tissues to become stiff. It is unclear if this change is the cause or the result of having back pain, but alterations of the quality of thoracolumbar fascia have been noted in some studies of patients with back pain.

And finally, as we've seen above, injury tends to stimulate nerves. This can lead to increased sensitivity to pain.

Anatomy

The thoracolumbar fascia is divided into three layers: the back layer (called the posterior layer), the middle layer, and the front layer (called the anterior layer).

Many back muscles attach to the thoracolumbar fascia. For example, the erector spinae, a muscle group also known as the paraspinals, run longitudinally down the spine. The paraspinals are attached to the thoracolumbar fascia, as well as to the bony spine.

The lumbar part of the posterior layer of the thoracolumbar fascia extends from the 12th (lowest) rib down to the top of your hip bone (called the iliac crest). Along the way, it connects with the transverse abdominal muscle. Because of these connections, the thoracolumbar fascia helps bridge the muscles of the back to the muscles of the abdominal wall.

Higher up, the latissimus dorsi, a large, superficially located back muscle that plays a major role in bearing and moving the weight of the body with the arms and shoulders, also has connections to the thoracolumbar fascia. (The fibers of the lats, as this muscle is often called, extend outward from the fascia.)

The front part of the thoracolumbar fascia (the anterior layer) covers a muscle called the quadratus lumborum. The quadratus lumborum bends the trunk to the side and helps maintain a healthy upright posture. The quadratus, as it is sometimes called for short, is often implicated in muscle-related low back pain.