The elbow, like most of the bodys joints, exhibits what are called accessory movements, small gliding and sliding movements which occur inside the joint during movement but which cannot be performed independently. These small movements are essential to the function of a joint and are easily disturbed, reduced or lost in injury or long term postural abnormality. The elbow has small, hardly noticeable movements in a sideways direction as the joint gaps slightly under pressure. This small gapping does not contribute greatly to the positions attainable by the wrist or hand but does make a functional contribution.
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 elbow is bent and the wrist is extended in an activity which is repetitive and lasts for some time then this can be damaging as the elbow bend loosens the extensor muscles a little and reduces their effectiveness to some degree. Examples of this activity are using a computer mouse or playing a piano. Continuous postural stresses from repeated actions over a long period can permanently cause tightening as the muscles continually recover. All this prepares the elbow for a time when a relatively minor added stress changes the typical, irritating achy joint into a highly acute and painful problem.
Tennis elbow is a common condition and typically develops as described above. It can come on acutely out of the blue after someone does an excessive amount of work, stressing the elbow very heavily and causing local injury and inflammation. More commonly there is a slow and longer term development of problems followed by a more sudden acute episode as a sudden stress is applied. Playing the backhand stroke in tennis is a particularly troublesome action to stress the common extensor origin but many other actions can produce the same result.
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.