Notes on Anatomy and Physiology: The Thoracolumbar Fascia

Thus far, we have devoted considerable time to a review of the form and physiology of the spine, a structure that plays a central role in the body and in the Taoist Tai Chi™ internal arts of health.

There is one last element of the spinal region we need to examine and that is the thoracolumbar fascia.

Earlier, we described the deep fascia of the body as a thin, tough membrane that envelops the body’s muscles and then penetrates down through the muscle onto the bones beneath. As it extends out from the torso to the limbs and inserts into the base of the skull, the deep fascia forms part of a larger network of connective tissue whose function is to support, connect and separate all parts of the organism. Before proceeding further with this article, it might be useful to have another look at Notes on Anatomy and Physiology: Anatomy of the Fascial System that was posted several months ago.

Now, the thoracolumbar fascia is a large, diamond-shaped sheet that forms part of the deep fascia. Most developed in the lumbar region, it consists of multiple layers of crosshatched collagen fibers that cover the back muscles in the lower thoracic and lumbar area before slipping through these muscles to attach to the sacral bone.

As you review the images below, remember that you can enlarge any picture by simply clicking on it.

Fig 1 A surface view of the diamond-shaped thoracolumbar fascia which, by means of its extensions, connects with the upper and lower limbs, abdomen and pelvis. The muscles deep to the thoracolumbar fascia are depicted in red. The deltoid, trapezius and latissimus dorsi on the right side have been removed. Biel, page 194

As seen in the figures below, the thoracolumbar fascia has 3 layers – posterior, middle and anterior.  These insert on the transverse and spinous processes of the lumbar vertebrae. They also attach themselves to the iliac crest near the dimples of the low back and fuse with the posterior surface of the sacrum.

Fig 2 A view from above of a horizontal cross-section through the front wall of the abdomen. The top of the picture is the front of the body. The transversus abdominis and internal oblique muscles act as extensions of the thoracolumbar fascia as they sweep forward, thus connecting the back with the front. Neumann, page 390

Fig 3 A view from above of a horizontal cross-section through the torso at the level of L3. The bottom of the picture is the back of the body. The posterior, middle and anterior layers of the thoracolumbar fascia surround various muscles. Neumann, page 362

Because of its rich connections, the thoracolumbar fascia links up with most of the rest of the body:

• the upper limbs, head and neck by virtue of it ties with the trapezius and latissimus dorsi. See figure 1 and 5.
• the midline of the abdomen. The posterior and middle layers of the thoracolumbar fascia fuse laterally to form the lateral raphe, a weave of connective tissue that then joins with 2 abdominal  muscles, the transversus abdominis and internal oblique. These muscles wrap around to the front, surround the rectus abdominis and merge at the linea alba. See figures 2 and 3.
• the deep structures of the spine by extending down to the spinal muscles, spinal ligaments, vertebral column and spinal canal. See figures 3 and 4.
• the lower limbs by melding with the gluteus maximus. See figures 1 and 5.

Figure 4 Horizontal view of the lumbar region. The top of the image is at the back of the body. We see the continuous nature of the thoracolumbar fascia-supraspinous ligament-ligamentum flavum connection. The multifidus is one of the muscles running along the spine. Lee, page 29

Fig 5 The sweep of the thoracolumbar fascia as it connects disparate regions of the body with one other. Myers, pg. 171

Its centrality and its way of rippling out in all directions, allows the thoracolumbar fascia to serve as a nodal point. It draws together all corners of the body – the head and neck, hands, abdomen, pelvis and feet. With the spine lying in the midst of it all.

Using the analogy of a circus tent, the spine is the centre pole, the soft tissues of the body (including the thoracolumbar fascia) are the fabric of the tent wall, the arms and legs serve as guy wires, and the hands and feet are tent pegs.

Many of the lessons learned in our practice of the Taoist Tai Chi™ internal arts of health have to do with rhythmically drawing taut/separating out/lengthening, and then releasing, the entire fabric of the thoracolumbar fascia and its connections.

Next time, we will examine further the roles played by the thoracolumbar fascia in everyday life, something that has become much better understood over the last few decades.

1. Trail Guide to the Body, Third Edition, 2005, Andrew Biel, Books of Discovery, ISBN 0-9658534-5-4

2. Kinesiology of the Musculoskeletal System, 2010, Donald A. Neumann, Mosby Elsevier, ISBN 978-0-323-03989-5

3. The Pelvic Girdle, Second Edition, 1999, Diane Lee, Churchill Livingston, ISBN 0 443 05814 8

4. Anatomy Trains, Second Edition, 2009, Thomas W. Myers, Churchill Livingston Elsevier, ISBN: 978-0-443-10283-7

Bruce McFarlane MD

© Taoist Tai Chi Society of Canada 2010