Muscle control

On many occasions in the clinic room we hear variations of the phrase “my muscles have seized up”. The question is how do muscles seize up? Well, read on to find out more.

Muscles are like soldiers, they do what they are told without question. This is important because a slight hesitation could mean the differences between catching a swing door or having a big bruise on your face! Within the body, there is a chain of command and unfortunately for the muscles they sit at the bottom of this chain. The command chain is:

Brain > Spinal cord > Nerve > Muscles and Joints

If the brain wants something done, it transmits a signal down the spinal cord which in turn relays the message to the nerves. They take that message to the muscles and tell them to contract. The muscle contraction moves the joint and completes the action. The joints and muscles work together thus alternating who commands the other. i.e. in the example above the muscles are telling the joint to move however if the joint feels it is being pulled to hard or fast it will command the muscles to relax..

Essentially muscle seize when there is a prolonged muscular contraction. This causes pain because:

1 – The muscles get tired (no muscle is designed to stay contracted for greater than a few minutes),

2 – The muscle contractions squeezes the veins and arteries that run through them. This reduces the local blood flow causing pain producing nerves to get irritated (as their nutrient supply is being affect).

So we know that muscles respond to commands. Therefore a seized muscle is the fault of one of the command levels and not the muscle itself. Examples of how different command levels can cause muscles to seize is shown below:

Command level = Brain; Example = Mental Stress.
The brain responds to stress by preparing the body for action. The muscles are put on high alert (meaning held slightly contracted), the blood sugar levels are raised to increase energy supplies, the sleep centre suppressed, etc… If stress is prolonged and continues for a few days, weeks or even months the muscles get tired because they are not designed to hold that prolonged contraction.

Command Level = Spinal cord; Example = Slipped disc.
A slipped disc can push against the spinal cord. The increased pressure causes the nerves in that area to fire erroneously. If the affected area is where the nerves to certain muscles come from, they will receive erroneous signals and contract. The brain cannot override this signal, as it cannot remove the pressure on the cord.

Command level = Nerves; Example = Inflammation or nerve trauma (e.g. a fall).
An impact can mildly damage a nerve. The nerve like any other tissue will swell. This swelling irritates the nerve and causes it to continuously fire. The muscles it supplies therefore remain contracted. The brain and spinal cord cannot modify the signal as they communicate with the muscles via the irriated nerve!

Command level = Joints; Example = Osteoarthritis or rheumatoid arthritis.
If the joints themselves are irritated, they can tell the local muscles to contract thus reducing their movement and allowing them to heal. The joints are clever because they too send a message to the brain explaining what they are doing. As a result the brain tends to help out, reinforcing the contraction.

It is for this reason that osteopaths rarely work on just the irritated muscle. i.e. the muscle is not the problem, it is usually the victim! We hope this article has been of interest and we wish you all a good health.