Muscles are capable of complete relaxation and of great contraction. When they contract they shorten. All muscles cause some movement when they contract. The majority of muscles start on one side of a joint and end via a tendon or ligament on another side of the joint. When they contract they make the joint move. Other muscles may just make the skin move as in the muscles of facial expression.
One might think that when a muscle is relaxed that it has no contraction at all. This is not the case. There are very few times when a muscle has no contraction at all in it. It might happen after a sever injury to the spinal cord, after a stroke or shortly after death. Even when it is at total rest a muscle has some amount of contraction in it at all times. This amount of contraction is called the resting muscle tone. In everyday life we refer quite accurately to the phenomenon of muscle tone. When someone is out of shape and flabby we can see and say that they have poor tone. When they are buff and fit, we see the outlines of the muscles and the slight bulge of the belly of the muscle and we say they look great and "toned." The concept is the same in medicine.
There is a reason that all muscles always have some tone, even when they are not being used. It takes energy to go from completely relaxed and long to contract enough to initiate movement. If we had to do this with every muscle every time we wanted to move, just the slightest movements would be exhausting. In children with abnormalities of low muscle tone we see this. Floppy babies move very little and become exhausted with the simple movements of controlling their head or with nursing. So, all of our muscles stay partially, slightly contracted to be ready immediately for the command from the brain to move. Constant tone or contraction in the muscles is required for us to maintain ourselves upright or to remain standing. The resting tone varies with our posture and our activity.
Though muscle tone can be measured in the movement laboratory or by EMG, in day to day practice tone is measure subjectively by the doctor or the physical therapist by passively moving our limbs back and forth. It takes a long time and a lot of patients to become comfortable with what the range of normal "tone" is. If you are sitting with your legs dangling and the examiner grabs your ankle and pumps your lower leg out and back, they expect to feel very little - but some - resistance. It should be pretty much the same resistance whether they pump it fast or slow. And the amount of resistance should be the same on both sides.
Now, we can cause the tone to be higher or lower, depending on the circumstances. If you sense you are in danger or threatened, your muscle tone will rise readying you for immediate action. If you have had an incredible massage and then a soak in a hot bath (pretend you don't have MS) your tone may dip very low and if someone were to shake your arm it might flop around like it didn't belong to a live person. We have all experienced that. Also, if you decide at that moment to become very active, you find that it takes a huge amount of effort and you become quickly exhausted.
In certain neurological diseases and injuries the muscle tone in certain muscle groups is altered - when it is increased you have a condition known as spasticity. This causes an imbalance with the other muscle groups and interferes with smooth and easy movement. One of the concepts you need to understand in understanding spasticity is the existence of opposing muscle groups. For almost every action we use muscles to do, there is another set of muscles to do the opposite action. If you use your biceps to flex your elbow, you contract the biceps and the brain sends a signal to the triceps to relax and allow the movement. If you then want to straighten the arm, you contract your triceps to extend the elbow and make it straight again. The brain commands the triceps to contract and the biceps to relax to allow the arm to straighten. It is always a give and take as you move. All of this happens automatically and far below your conscious level.
In spasticity the whole thing goes awry. I am going to use my own experience as an example. My first presenting symptom of MS was spasticity in my right leg all the way from my right lower back to my foot. In my case the groups of muscles called the "extensors" had an increased tone in them at all times. The extensors arch the lower back, swing the leg backwards at the hip, straighten the knee, and pull the toes of the foot downward. I found that it took a lot of effort to lift my right foot off the floor. My brain would command the hip "flexors" to bring the knee up (like to step up a step) but the signal to relax the hip and leg extensors never happened. They didn't relax, but instead continued to "pull" against my efforts. If I laid on my back the increased tone in the paraspinal muscles would cause those muscles to keep contracting until they were spasmed into a knot, and I learned I had to leep with my hips bent and began sleeping in my recliner.
I no longer could bend my knee while standing to look at the bottom of my foot. The non-stop tone of the knee extensors kept me from performing that action. I could bring my toes all the way up toward my knee, but it was hard. When I walked, though, the extensor tone was stronger than my ability to bring up my toes and my toes pulled down and tripped me. I had a "functional" foot drop. That is why I was fitted for a brace.
Spasticity, though is "velocity-dependent." This means that the faster the message to contract against the tight muscles is, the stronger the signal to keep them rigid. Use the example of the person sitting on an exam table dangling the legs. If the examiner pumps the leg out and back slowly they may feel a little increased resistance. But, the faster they pump, the higher the resistance to their attempts. Many of you have seen this in action. You have a leg that often doesn't want to move. It feels like you have a 40# weight on your foot keeping your pace slow. But, you can move. However, if you need to step with that foot fast (say to catch yourself off balance of to dodge a thrown object) the foot is stuck, like it is literally nailed down. The signal to move fast, increases the tone in the spastic muscles.
My spasticity was mild. But, as it grows in strength, movement becomes harder and harder. The muscles become rigid and the person can no longer overcome the higher tone. As the signal grows to keep the tone up the muscles can became extraordinarily painful and the joints can actually twist into unnatural shapes.
Sometimes, spasticity works somewhat to a persons advantage. A common problem that accompanies spasticity is muscle weakness. The muscle doesn't get a clear signal to move and it doesn't work. If a person has extensor spasticity, this tend to help them maintain an upright posture. If they have the increased tone in the flexors, it will bend them over, bend the knees, pull the elbows into tight flexion. This is incapacitating.
Spasms are the nonstop contraction of a muscle or muscle group. It is caused by the non-stop signal from a damaged nervous system to "Keep on Contracting." It can happen without spasticity, but more often the underlying cause is spasticity and unrelenting increased tone in that group of muscles.
I hope this has made Muscle tone and spasticity more clear. Please ask questions.
Does this "signal" to contract start in the brain? It is something that can orginiate from the brain down the spinal cord, where there is damage from a lesion?
Since leg spasms are the greatest part of my daily pain, I have always wondered if this orginates in the brain and/or the lesion in the right hand side of my spinal cord. This lesion has been present in every MRI for twelve years. It has shown 'activity' (active demyelination) on several occasions, as seen on MRI. The "scar" has never disppeared. I guess the question really is, "Do we know where the "spasm message" starts?
Here is yet another posting which belongs in a permanent viewing spot.
So, the constant pain in my ribs is likely a constant spasm? And the reason I have difficulty with my legs, (lifting my knees in exercise class, walking up, or down stairs) is spasticity, likely?
I was just sitting thinking yesterday, that it was the act of using any muscle group repeatedly and quickly, which has been making me so tired the last couple of days, again. Typing, mixing stuff (cooking), moving legs (knee / hip joints), elbows, jaw, etc. They don't really hurt, just are very tight and tired feeling. After a short while using any of them, I had to rest.
Yet, exercise classes, though difficult, seem to give me more mobility. Does that make sense? It is tiring, sometimes I have to cut class short, sometimes I can take a short break and then be fine. Lately, though, any exercise which causes me to rapidly lift my knees, or use my legs at all quickly causes a great pain to suddenly explode in my hips or my knees, depending on the exercise. It subsides quickly enough, when I stop. But it can sure be debilitating when it strikes, I have to crouch down, scrunched into a little ball for the pain to abate. Then I get up, and go at it again.
Thanks again for all the info. Yes, this last posting you have done on spasticity needs to be there as well. Do I sound demanding? LOL :)
More answers come everyday for me, from here. What would we all do without this place !!??
I have this thing that happens with my right leg. It seems to be slower , when I turn or stand and take first step my foot slides across the floor. If I concentrate it will obey. So I have been watching this and came up with, its in my hip movement. hhmmm Also when standing for a couple of minutes I HAVE to raise my foot , like a march, Marching was one of my first sx. With p.t. and concentrating I am able to walk fairly normal, but lifting foot remains. I had no flex in right knee or either foot on exam.
I get exhausted doing little repetitious thing too ( my jaw , that's weird ) And my arms are like jello some of the time
I hope its o.k. to post here, if not delete... sorry Jo
That foot-lifting thing---it's part of restless leg syndrome. You can't NOT do it. Have been there, and in fact am there at the moment. For me, I'm beginning to see that I get little muscle contractions just above the knee cap of my right leg, and that seems to confuse my knee considerably. If I'm outside and walking fairly vigorously, sometimes my knee seems unsteady, as if it's not sure what to do, and I wonder whether it will hold me up. This, despite the fact that my muscles are quite strong. So go figure. I think we might be in the same boat again.
Heather, the abnormal signal to resist stretching can be anywhere in the central nervous system pathway from the brain to the spinal cord.
The best info I have found on spasticity - and I almost hate to put it down, because you'll see that what I wrote is not entirely true, but true enough to understand it. Everyone with problems with spasticity, muscle stiffness, "being glued to the floor", or spasms should read the info at this link:
Hey guys, well I've been trying the Zanaflex, or rather the generic of it - Tizanidine at 4 mg for these non stop muscle spasms. Not one bit of help. :(
I have a serious problem of raising my leg up past the knee position- such as, if you were stepping over something like a small barrier, or shrub for example (mine is a puppy barrier made out of the lid to a plastic tote, laid on its side- I use it in the doorway to my utility room). I can start to lift my leg- (mainly left)but right one to a degree- then I have to actually 'hold' the leg up with my hand to get it the rest of the way over and then let go of it, once across the barrier. Course, this thing is not very high at all. Its nuts, but I am used to doing it now.
I keep getting "jumpy" muscles. Kinda like your eyelid but in the long head of the tricep, the top of the rectus abdominus and the right calf. They just twitch almost like a heart beat for a few minutes to a few hours. This happens almost everyday. Oh ya, my gluteals do it too! :-). LOL It's always the same muscles if that makes a difference. They like to dance on their own... la la la doo da doo da! Is that the same thing or something different?
You're describing small muscle twitches which are called fasciculations. These are common both in normal states (muscle fatigue, muscle use after a period of inactivity, with a viral infection, stress ((especially around the eyelids)) and in muscular and neuromuscular disorders. This is not the same thing as is talked about when we talk about spasms, though they are tiny, brief contractions of a small group of muscle fibers. Most of us have these as well as people without illnesses.
I believe that I have "increased tone" on the left side of my body. When I go to run or walk the left side of my body completely seizes up for abou 5 seconds. My left arm will contract right up under my armpit and I find it hard to talk because the muscles on that side of my mouth are hard to move. After about 5 seconds everything goes back to normal and if I go to run again straight after this happens it won't happen again - it's almost as if my body "resets" itself. I don't know if this is relevant to this thread but I thought I'd post it anyway. Hope you can give me some insight in to what this might be and if there is anything I can do to stop it from happening. Cheers!
Quix: this was a very interesting read indeed. setting aside my previous posts
on my history, symptoms for possible ms ect. ---
this really struck a cord with me , because so many times i have often wondered
why i could be have so many problems with some of my joints. the docs know that somthing is causing problems with the joints because of the periodic swelling in them. Especially left hip and both knees.. ( I have had torn meniscus surgery right leg this past monday) and healing well. the docs have tested fluid off these joints, they have checked for several arthitis conditions ect and nothing shows up. But the damage is there.
my right hip got so bad one time with pain i could barley walk for days. now my orthopedic wants to xray my hip after i recover from knee surgery. I hadnt told her of the hip problem yet ( because of all the ms testing going on and upcomming surgery on knee it was just to much to deal with all at once) but while in her office for knee exam i went to stand up and she heard the mad sanpping noise in my hip as well as saw the pain it left me in for a couple of minutes. after the pain stops i can then stand straight up. I have never injured these areas in any way.
I also seem to be tripping over my left foot it seems that the front bottom part of my foot will hit the floor to soon and the rest of my body is not ready for and i will trip
as if there were somthing lying on the floor in my path. very strange.
i have wondered several time over the past 6 years if there was some kind of problem with the muscles around those joints are where the problem is. Im so glad you wrote this, it leads me to some very interesting questions for my nero and ortho, possibly my reumo as well thank you for the enlightement
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