Healthy nerves need to move

Nerves need to be able to move, slide and stretch as the body moves. This may seem like common sense, but ironically this way of thinking has only come to be incorporated into rehabilitation since the 1980s and still isn't completely acknowledged across all medical professions today.

When you lift your arm over your head the path some nerves follow is 20% longer than when your arm is at your side. Although our nerves do have the ability to stretch, this ability is limited. Primarily, nerves need to be able to slide around other tissues of the body as we move. Nerves can slide up to 2 centimeters under surrounding structures, and if this ability to slide is restricted, problems can occur.

The easiest analogy to use when discussing this type of movement is to think of the nerves as dental floss. As we move, the nerves are "flossed" between our bones, muscles and connective tissue.

Try this out: put your fingers in the center of your knee crease and straighten your leg. If you pay careful attention under your fingers, you will feel a rope-like structure push against your fingers. What you are feeling is your tibial nerve (an extension of your sciatic nerve). Bend and straighten your leg a few times and you will see how the tension on this nerve increases as you straighten your leg. Now keep your leg relatively straight and flex your foot toward your body and you should be able to feel the tension increase even more.

In my last post, I discussed that when you flex your foot up during a hamstring stretch the pull that you feel is due to the fascia. The fascia running up the back of your leg is part of the reason for the pull, but the other reason for the pull is tension on the nerve. Ironically, regardless of the primary structure causing the restriction, a problem in this area can often be solved by treating fascial restrictions. Nerves have to run through "tunnels" between muscles, and between muscles and bones. Muscles and bones are surrounded by fascia, and as I described in my previous post, if we do not maintain mobility of our tissues, fascial restrictions will occur. These restrictions can make the "tunnels" smaller and put more pressure on the nerves. Even worse, scarring following injury  can link the nervous system to the surrounding tissues.

Now, why are free-flowing nerves important for good health? To simplify neurophysiology, you can think of nerves as functioning like garden hoses. The nutrition required for the nerve travels down the center of the nerve. If the nerve is compressed, the nutrition cannot travel appropriately through the nerve.  This will negatively affect the health of the nerve and the muscles supplied by the nerve.

There are many other reasons why pressure and excessive stretch are bad for the health of your nerves and muscles, but I'll leave that for another post.

Dave Zelibka, BScPT, GunnIMS, CAFCI

Registered Physiotherapist
London, Ontario

Phone: (226)777-7111

Email: dave@elevatephysio.com

Web: londonphysio.ca