Fascia. An up and coming buzzword that’s attracting a lot of attention. When explaining fascia to people I describe it as that white filmy stuff that wraps around meat (muscle). In some places it’s thin and wispy, while elsewhere very tough and thick.
Fascia can be easily lifted from the muscle in some parts of the anatomy, yet in other places it’s so firmly attached that separating it requires cutting into the muscle fibers (the parts of the steak you throw to the dog). These differences – called regional specialization – are based on location in the body and reflect the different roles the fascia fulfills according to the demand placed on it. For example, the iliotibial band (ITB or IT band) running down the outer part of the thigh is one of the thickest, toughest pieces of fascia in the body. The high forces transmitted throughout the lower limb require such a design. By contrast, the fascia of the inner part of the arm or forearm is not nearly as thick as the ITB since it does not handle the same amount of load.
The literature on fascia has been very confusing over the years, which has not helped our understanding of this connective tissue. As often happens, people like to name things after themselves and fascial anatomy is no different. This has led to multiple different names for fascia throughout areas like, for example, the abdomen and pelvis. Not only is this confusing, but it also gives the false impression that these differently named regions of fascia are separate structures, when they are actually one seamless network. From head to toe, right to left, front to back, the fascia is continuous, intermingling, and creates relationships throughout the body: between the shoulder and the shin, the hand and the head, even the back and the bladder.
When looked at with the naked eye or even under a microscope fascia can look very disorganized and messy, like the deep fascia on the deer tenderloin in Figure 1. This is why some sources categorize deep fascia as irregular dense connective tissue. But when separated by layer, it is actually found to be quite orderly with collagen fiber bundles laid down in a very organized manner, parallel to each other within that layer like fingers on a hand.
Fascia is made of many cells (essential for the life of the tissue), fibers (primarily collagen and elastin or elastic which provide structure and support), and a ground substance uniting it all (water, ions, and glycosaminoglycans or GAGS which make it adaptable).
The layered formation of the fascia has only recently been demonstrated by researchers. The superficial fascia has two tissue layers, while the deep fascia has two to three layers according to body region.
They are separated by layers of loose connective tissue (LCT), which has a very high content of elastic, water, and a substance known as hyaluronan (also called hyaluronic acid or HA). This is our body’s biochemical lubricant that provides space and slide between tissue layers. HA is found in connective tissues throughout the body, and also happens to be an ingredient used in injections to help joints move better, like the knee. The integrity of this sliding system is thought to be key to pain free movement of joints and overall function.
Fascia is loaded with nerves, which is another feature we have only recently come to appreciate.
Chemical staining of the fascia and viewing slices under a microscope reveal the presence of a variety of nerves that perceive pressure, stretch, temperature, and pain. This is remarkable to comprehend, as fascia has historically been considered a tissue existing primarily for containment purposes – not a potential source of pain! Once again, the demand dictates the structure: body regions that need more information in order to keep us safe and functioning (wrist, ankle) have a higher content of nerves in the fascia as compared to areas like the elbow and knee, which are better suited for stabilization. In the muscles, fascia is connected to the portion of the nerve that turns it on (muscle spindle). Conversely, near the tendons the fascia communicates with the mechanism that turns it off (golgi tendon organ or GTO). Fascia surrounds the nerves to protect, cushion, and facilitate glide for pain free mobility and function.
Nerves also have to pass through the layers of fascia to reach their target structure: skin, muscles, blood vessels, sweat and oil glands just to name a few of the structures the nerves communicate with.
Internal organs like our stomach, bladder, ovaries, prostate, and intestines are lined with fascia full of nerves which coordinate the involuntary, autonomic functions these organs fulfill.
This post is part of a series explaining fascia. Read the rest of the series here: Where is Fascia found? and What can go wrong with the Fascia? The posts are combined on the page Fascia Facts.
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2 thoughts on “What is Fascia? (Fascia Facts Part 1)”
Interesting article. Looking forward to part 2.
Marge is that you??? How great to hear from you! This is an old post, the rest of it can be found in subsequent posts as well as all combined in a page under Fascia Facts. Thanks for reading, hope you guys are well, would love to reconnect!