Anatomy Of A Muscle Spasm

back spasm nude“What the hell did I do?” That plaintive question, along with a string of cuss words and an awkward posture, was usually a good sign that a patient with a muscle spasm had walked in through the clinic door. Muscle spasms are sneaky little devils, often seeming to show up out of the blue and leveling the sufferer with a pain and disability all out of proportion to whatever they did to cause it.

They are fascinating phenomena, physiologically speaking. The human body has evolved a host of spectacular protective mechanisms that keep us out of trouble and help us when we’re injured. A muscle spasm is a good example of this process getting a little overeager and working against itself.

It all starts with an irritation. This could be torn fibers from one too-mighty exertion, or a buildup of waste products from a long period of overwork, or a shot of pain from a nearby joint or ligament. Could be lots of things, but it all starts here. The muscle hurts.

Then the reflexes kick in. The pain moves up the sensory nerve fibers connected to our muscle and lets our conscious awareness know there is a problem down there. But before the pain signals reach our brain and get processed into an ‘Ouch’ – long before, in the millisecond timeframe of the nervous system – they reach the switching center in the spinal cord where the peripheral nerve from the muscle passes the signals on to the central nerves of the cord. This is where the nervous system gets its first chance to react to the pain. This is where reflexes live, hardwired into the spinal cord itself.reflex arc

Maybe the level of stimulus won’t be enough to trip an alarm. Maybe the pain is considerable, but higher commands from the brainstem or consciousness override the reflex and tell everyone to keep calm. Or maybe the signal from the aggrieved muscle trips the reflex alarm. Then your spinal cord fires up some motor neurons and tells your muscle to tighten up and protect itself, for its own good.

This is perfectly sound primal reasoning. If you’ve been damaged you want to splint the area, right? Keep it from getting hurt any more. The problem is, this system is too basic, doesn’t take enough factors into account. The last thing you want to do to a torn muscle is yank on it. The last thing you want to do to a muscle that’s tired and full of irritating waste products is stiffen it, making it work even more and squeezing out the refreshing blood supply.

All that does is create more pain. And in the inexorable logic of a positive feedback loop, more pain creates more tightening. If no higher commands get the chance to tell interrupt the process, the sensory-motor-reflex system will lock the muscle down in a full-blown, and very painful, spasm that has you jumping and twisting and inventing new vocabulary.

The whole process, from first pain to full spasm, can take a matter of minutes, or less than a second. It can kick in long after the exercise or work or fun that initiated it, or lay you flat on the weight room floor before you know you’ve hurt yourself.

Massage therapists have lots of ways to work out muscle spasms. Ice can help take down the original inflammation, and freeze out nerve conduction to the muscle, stopping the feedback loop. Circulatory massage can help ease the muscle back out to its full length and push fresh blood through the tight fibers. Other techniques can trick the nervous system into letting go, or work on the spasm from other angles. It’s a fundamental part of the job.

I had to remind myself, when a full-cuss spasm came through the door, to be caring and concerned and to tone down my eager interest in the process unfolding before me. Most of my patients appreciated an explanation once the pain started subsiding, however, which made this little talk about muscle spasms one of my most frequent tableside anatomy lessons.