Someone suffering from backache may not be interested in the anatomy of the nerves involved. But for those who do the following description of the type of nerves that are involved may be of interest.

We need to know a little about the anatomy of muscles. Normal muscle contraction with any normal movement, such as walking across a room, is not painful.

The muscles, however, do become painful when there is excessive tension in a muscle. This tension can involve the whole muscle or it may be confined to a few muscle fibres only, or a few motor units as they are called, as occurs in common back ache and neck ache. This type of pain is of an aching quality, and may be stabbing, shooting, gripping or nagging.

When a tense muscle is made even more tense by giving it resistance so that it has to tense harder, the muscle becomes much more painful. When the same muscle is relaxed, the pain is reduced to the original level. To make sure the extra pain is coming from the muscle and not from the underlying joint, the joint is kept still when resistance is given to the muscle. When the muscle is totally relaxed the pain goes.

In these tense and painful muscles there are spots which are even more painful. They are called “trigger spots”. These trigger spots are always found in the same place, at the junction  of the tendinous and fleshy part of a muscle , near where it is attached to the bone.

Pressure on a trigger spot elicits severe and agonising pain. These trigger spots are found only in a tense and aching muscle and disappear with improvement of the condition. The trigger spots are found in exactly the same part of a muscle as the specialised part of a nerve , that is, a “nerve ending”.  These specialised nerve endings, or receptors, at the ends of muscles are called Golgi tendon organs and are one of the nerve endings for feelings of movement. They are termed one of the kinaesthetic receptors.

The kinaesthetic receptors tell us what position our bodies are in, even when our eyes are closed. For instance, if we close our eyes, stretch our arms to the ceiling, and keep our eyes closed, it is the kinaesthetic receptors which tell us that our arms are up there and they have not dropped down. If we keep our eyes closed and slowly lower our arms so that they are stretched out sideways like an aeroplane, it is the kinaesthetic receptors which tell us where our arms are in relationship to our body.

It would seem that the Golgi tendon organs play a double role. They are the nerve receptors for feelings of movement.  However, when they are over stimulated as in continuous muscle tension due to stress, they become painful.

It would seem that as well as being the nerve receptors for feelings of movement, Golgi tendon organs are also the nerve  receptors for aching pain.

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