The large majority of the bodys joints, including the elbow, are capable of producing what are known as accessory movements, small sliding and gliding movements occurring inside a joint which a person cannot perform on their own. Accessory movements are vital for the normal use of a joint and are easily disrupted, limited or abolished by trauma or postural bodily misuse. The elbow accessory movements are very limited in size and consist of a small sideways gapping of the joint, which does not make a large difference to the ability to achieve various positions with the hand but does increase functional ability.

These little accessory movements may not seem to be able to make a difference to the use of the elbow joint but they can permit a slight lengthening of the extensor muscles of the wrist when we are trying to adjust our arm position to get hold of something. If a muscle is stretched slightly this increases the contractibility and thereby its function. In this case the extensor muscles can extend the wrist more successfully to allow the flexor muscles to apply grip strength.

If the opposite muscles dominate and the extensor compartment of the elbow and forearm is tight and shortened to some extent the muscles will not be able to position the wrist well to allow effective grip and holding of objects. The rotatory ability of the radial head within its supporting ligament is also of high importance in allowing the hand to be positioned in virtually any number of positions.

The two commonest and repeated movements we perform again and again throughout the day are extending the wrist with the fingers downwards and rotating the forearm so that the palm faces up. The groups of muscles which perform these two actions start life over the same patch of bone on the outer side of the elbow, leading to potential overuse and pain problems. Overuse of the muscles can increase the tone in the outer elbow compartment, reducing both the elasticity of the tissues and causing them to shorten. This can develop into a cycle of becoming tight, adapting by using the hand in new ways and then tightening further.

If the arm is used for many actions and over some time in a bent position so the wrist is extended and the elbow flexed this can cause a mechanical disadvantage as the wrist extensors are slackened off and so can exert less force. A typical activity of this sort is piano playing and use of a computer mouse. If the muscles have to continually try and recover from ongoing posture stresses which persist for a long period they can shorten close to their origin. With time this sets the elbow up for the small event which will be the last straw and alter the achy, annoying problem into an acute, terrible pain.

Tennis elbow is a widespread problem which often develops slowly as described, however the onset can be sudden and unexpected after a lot of physical work which can overstress the joints tissues and cause local inflammation and trauma. Typically the slower onset is more common with the more minor problems being present for some time until there is a sudden, often small trauma. The tennis backhand stroke is a good example of how to significantly stress the origin of the extensor muscles but other activities which reflect that kind of action can add up to the same.

If the muscles are over tight and the muscular action forces are pulling the opposite way as we grip or hold something, there may be an overstress of the tendon-bone junction leading to some of the local tissue fibres tearing away from the bone. Once this has occurred and a degree of healing followed, it becomes easier and easier to re-injure the area with less and less physical force. The healing process, involving scar formation, can also cause tightening as it contracts and lead to a further vulnerability to stretch. In serious cases the severity of the pain can be so bad that simple minor actions can be painful and so are avoided.