Nerves as a part of the danger alarm system
Pain is a highly sophisticated alarm system that is designed to warn the body of danger. We all need it to keep ourselves and our tissues safe.
Nerves conducting messages from our muscles, skin and joints are only a part of the system. Today we will explore why there is no such thing as 'muscle or joint pain'.
Take the example of a paper cut on the end of your thumb. Sensors on the end of the nerves that supply the skin of that thumb will detect some damage to the skin. Alarm bells will 'ring' at these sensors and an electrical impulse travelling at 150km per hour will tell the brain "there's something going on at my thumb." The brain will take this message and will use that with other pieces of information to produce (or not) an experience of pain. Such other information could include the intensity of the alarm signal, visual inputs of the sight of the blood, visual impact of realising the deepness of the cut, memories of this happening before and really hurting etc.
This alarm system from the tissues (skin, muscle, joint) to the spinal cord and brain is called 'nociception', which means 'danger message'. From the example above, it can be seen that nociceptive messages along the nerves does not always result in pain. You may have experience this yourself when noticing much later that you have a little cut on your thumb with the presence of dried blood, but can't recall when you had cut yourself.
Nociception is only one small part of the pain experience.
We all have nociception going on all of the time- quite often beyond our consciousness. However most of us do not feel pain all the time. The brain has not thought there needed to be any concern to worry or alert you that you are or your tissues are actually in danger.
Even more interesting is that pain can be experienced without any nociception at all. Take emotional pain. Or strange tales of husbands experiencing 'labour like' pains when their wives are giving birth, or twins who feel the pain of the other.
So it can be said that pain does not 'live' in your muscles, skin or joints. It is nerve sensors that do - alerting the brain and consciousness that danger is about. Pain is the complex construction as your brain evaluates these danger messages with other information relevant.
You can impress your dinner party guests that what you hear about targeting 'muscle and joint pain on the Panadol and Voltaren ads on TV is not entirely true from a physiological view!
More on nerves, their sensors and nociception next time.