MA: Thanks to Skillshare for supporting this episode of SciShow

The human body can perform incredible physical feats like surfing an 18 meter wave or jumping over 2 meters in the air.

And while you might applaud muscles for such acts you should probably credit fascia too.  Fascia is the vast network of connective tissue that makes your body a single continuous unit capable of sensations and actions.  

I mean, it would be pretty hard to surf if your muscles didn't fully contract when you wanted, or if you didn"t know where you feet were without looking at them.

Fascia not only connects organs to other organs, like muscle to skin, its also got all kinds of nerve endings which help you sense your body in space and even what's happening inside you.  Yet, for decades doctors and scientists considered it boring filler tissue. They'd throw it away thinking that provided a cleaner view of the organ they were really studying.  

Today, they know better.  Fascia is considered to be an important sensory organ in its own right.  And one with some weird physical traits.  And the more we learn about it the more incredible it seems to get.

Your fascia is everywhere inside you.  There isn't an organ, muscle or blood vessel that isn't connected to or enveloped by it.  

It's one of the major kinds of supportive connective tissue, along with ligaments and tendons, all of which are mostly made up of stretchy bundles of elastin and collagen proteins suspended in a gelatinous goo called ground substance. And the most obvious roles are to keep us together and help us move around.  

But even among these supportive connective tissues, fascia is a bit of a star.  See, ligaments and tendons have pretty much one job: to transfer energy between muscles and bones by being strong, yet stretchy.  

Fascia does that too, like the fascia in your foot that connects your heel to your toes, but it also acts as a lubricant.  You can find it between the muscle fibers within a muscle and also surrounding the whole muscle and that helps ensure that your muscles can fully contract while preventing damage from friction when you flex.

One of the most intriguing things about fascia is that it is able to have these very different mechanical properties.  

After all, being strong and stretchy doesn't really help things slip around when they need to.

In part this can be explained by different kinds of fascia.  In general, the stretchy collagen fibers in fascia are woven in mesh-like layers but in some areas these meshes are more tightly woven or have more collagen or have different types of collagen.

No one is quite sure how many different types of fascial tissue there are but that still doesn't explain how specific regions of fascia can hold muscles or organs in place and act as a lubricant for them.  

It turns out fascia can do something kind of remarkable:  it can change its material properties.  When the tissue needs to be more rigid, it can take on a more gel-like form.  Then, when it needs to be slick and slippery, it can essentially liquefy.  And, to be honest, no one's 100% sure how it does that.

Some people think it's simply that the ground substance makes fascia thixotropic, that is when stressed it becomes more liquidy.  

Others think the tissue is more of a liquid crystal and like many solid crystals, that means when pressure is applied, electrical charge moves around.  That charge movement could then trigger the cells in the tissue to produce or breakdown key components like collagen.

And still other scientists think it has more to do with the nerve and muscle cells in the tissues.  That's because fascia has lots of special neural receptors called mechanosensors that can detect pressure or stretch.  

When triggered they can tell muscle cells to relax or contract directly, or to dilate or constrict blood vessels and by doing so, move fluid around to adjust gooeyness.

More research will have to settle the debate between these three ideas or determine if they are all somewhat right.  

But however fascia manages to perform it's solid to liquid trick, one thing is clear, it isn't just the weird glue that holds us together.

For centuries it was considered filler material, or just basic packaging that kept your parts where they belonged.  Now, scientists speculate that fascia could play a role in all sorts of poorly understood phenomena.  

Because it's around all of your organs, anything our body wants to move around has to pass through it and that means it could have a big part to play in everything from hormonal signaling to your immune response.  

Also, scientists now consider fascia to be one giant sensory organ. Since it's all throughout your body and packed with mechanosensors it's thought to play a big role in proprioception, or the ability to sense where your body parts are in space.  

It's also probably important for interoception, or the ability to sense what's going on inside your body.  

And fascias ability to contract or dilate blood vessels ties it to your autonomic nervous system, the system that unconsciously regulates the activity of your internal organs such as your guts, bladder, or salivary and sweat glands.

It might even play a role in psychological disorders, though a lot more research is needed, studies suggest that fascia could play a big part in how we regulate our feelings and emotions because it tells your brain so much information about the location and condition of your body parts.

Fascia is also being investigated for its potential role in conditions like fibromyalgia and chronic pain.  That's not as much as a reach as it might sound since fascia contains a lot of pain receptors and the swelling of fascia, also called fasciitis, can cause persistent pain in joints and other body parts.

And its not just medical doctor or psychologists getting in on the fascia research action.  Engineers are also interested in fascia because of those mechanical properties.

There aren't a whole lot of substances out there that can go from stiff to fluid like fascia can, so they are keen to uncover exactly how fascia performs this biomechanical miracle.

The truth is, there is just so much we don't know about fascia yet and this is probably because, well, fascia is really complex.  

Fascia produces cellular, extracellular, neural and biomechanical responses,  and the layering of collagen varies based on where the fascia is found.

Scientists are working out how to classify fascial tissues into functional groups so they can better explore their capabilities.

And since fascia connects the entire body with amazing, dynamic, elastic properties, there's no doubt the future of fascia will be exciting.