Notes on Anatomy and Physiology: Anatomy of the Fascial System

Recent work^{1, 2} on connective tissue has helped us better understand how all the seemingly disparate parts of our physiology are assembled into a coherent whole. For it is the connective tissue that literally knits us together, forming a web that binds, supports, connects and separates all regions of the body. From top to bottom. From structures at the surface to those lying deep in the interior.

Later, we will see how each individual cell is also implicated in this web and how the cell’s internal structure, its cytoskeleton, interacts with and is powerfully influenced by the larger web. But, for now, let’s look at the fascia, one specific form of connective tissue. By appreciating the impact of our art on fascia, we will begin to see how regular practice influences every element of the entire body.

The fasciae come in sheets and present as four distinct fascial layers. Intimately related to one another, they are constructed much like Russian dolls, each tube nestled inside another. Tubes within tubes. Each tube is continuous, ties into the structures that lie within the space it creates, and connects with the other layers.

Fig 1 Tubular structure of the fascial layers. Grant's Anatomy

Grant’s depiction of the fascial layers in figure 1 is not entirely accurate but it does give us a sense of their tubular nature. You can see how they each encompass a space within their borders and how they lie longitudinally, one inside the other.

The superficial fascia is the outermost layer. It covers the body’s entire surface, including the head. Loosely constructed and rich in adipose tissue, it warms and insulates. Because of its elasticity, it bends and moves as we do. It is the endpoint for the nerves and vessels that originate from deep within the body and run all the way out to the surface, providing sensitivity and nourishment to the skin. The breast tissue resides in this layer. The next two photos reveal just how coherent a fabric the superficial fascia is.

Fig 2 Remarkable dissection of the superficial fascia in its entirety done by Gil Hedley. http://www.gilhedley.com

Fig 3 Superficial fascia lying beside the body from which it came. Gil Hedley, 2005. http://www.gilhedley.com

The deep fascia is the next layer. It is a thin, tough membrane that houses the muscles of the body and then penetrates down through that muscle to insert on the bone beneath. This penetration reveals that the fascial sheets exist in all three planes, and reminds us that there are no independent structures in the body. For our purposes, the yellow tube in figure 1 represents the deep fascia.

The deep fascia extends from the torso out to the limbs and inserts into the base of the skull. It attaches to the midline of the body at the front and to the transverse and spinous processes of the spine at the back. Also called the axial fascia, this layer creates two compartments centered about the spinal column, an anterior one that contains the muscles of the abdomen and front of the neck, and a posterior one that supports the paraspinal muscles.

From an embryologic perspective, some large and important muscles – the pectoralis major and minor, the trapezius and latissimus dorsi – flow from the upper limbs onto the torso, covering parts of the deep fascia and inserting onto bone in the midline.

We will learn about the thoracolumbar fascia a bit later. Although given a separate name, it is actually part of the deep fascia and fuses to the sacral bone.

The visceral and cranial fasciae are the final layers. They are the green and blue tubes seen in figure 1 above. These layers provide the compartments that contain the body’s organs. At the front, the visceral fascia creates the ventral cavity that holds the internal organs of the thorax, abdomen and pelvis. The cranial fascia gives shape to the dorsal cavity towards the back and provides space for the brain and spinal cord. As we will see, these organs are not limited, in form or function, to the cavities in which they principally reside.

Figure 4 below provides a simplified outline of the head and torso with the green area representing the dorsal cavity, brain and spinal cord. The pink is the ventral cavity that runs from mouth to anus. The blue that envelops them both is the deep fascia. You see how the deep fascia surrounds the neck and torso, encompassing the visceral and cranial fascia and housing the body’s muscles.

Fig. 4 The visceral fascia (pink) and the cranial fascia (green) wrap about the head and torso. Willard, 2007. Disc 3

The fascial system, then, is a global one, even though anatomy texts have yet to present it in this way. All its layers or tubes alter with aging, trauma, illness, activity, mood and imitation. To keep healthy, they must continue to move in all directions and maintain the play that is meant to exist between them. As we go along, we will see that it is the unique stretching, separation, elongation of the body’s layers inherent in our art that permits differentiation of that which is integrated and connected, and keeps these structures supple and strong.

Dr. Bruce McFarlane

¹ “The Integral Anatomy Series”, volumes 1 through 4, Gil Hedley, offer wonderful insights into the fascial system of the body. Website: www.gilhedly.com

² “Fascial Continuity: Four Fascial Layers of the Body”, FH Willard, Ph.D., Department of Anatomy, University of New England, College of Osteopathic Medicine. A presentation given at the First International Fascia Research Congress 2007, disc 3, October 5, 2007.

© 2010, Taoist Tai Society of Canada