Why are the rotator cuff muscles important to your shoulder? And how can you look after them?
Did you know that 10% of the population will develop shoulder pain at some point in their lives!
Given the nature of the shoulder joint being highly mobile and as a result of this wide range of mobility causes it to be a fairly unstable joint, it is easy to see why. The shoulder is essentially a ball (head of the humerus bone) and socket joint (glenoid fossa) amongst a sea of muscle. Whilst it has some support from ligaments and a cartilaginous structure called the glenoid labrum, it relies heavily on dynamic muscular input. The four key muscles responsible for maintaining shoulder stability are the rotator cuff muscles called; Supraspinatus, Subscapularis, Infraspinatus and Teres Minor. Another structure to be aware of is the acromion (a flat bone that sits above the “ball” that allows muscular attachments and a connection to the collar bone (clavicle) so that the shoulder and arm can join to the rest of the skeleton. A space between the “ball” of the shoulder and the acromion is called the subacromion space. This structure is important to be aware of when dealing with rotator cuff issues and shoulder pain.
Shoulder Movement & Rotator Cuff
The rotator cuff muscles play an intricate role in shoulder movement. When the head of the humerus bone moves the shoulder blade moves too. This is a complicated relationship that if disturbed can cause an alteration to the mechanical function of the shoulder. If the relationship of the muscles is disturbed for whatever reason simple everyday movements like putting the shopping away in a cupboard on the wall can become painful and troublesome, and sports such as tennis can become nearly impossible.
Essentially the rotator cuff muscles all help to stabilise the shoulder by working together to apply a “quadrangular” stabilising force to the ball of the shoulder joint. Each muscle has its own specialist role to enable stability of the shoulder. However, the muscles all have their own individual input to generate movement at the shoulder as well.
The unique movement of the Supraspinatus muscle is to provide the first 20 – 30 degrees of a movement called abduction (lifting your arm out to the side). After 30 degrees is reached a much larger muscle, called deltoid, takes over. As previously mentioned the supraspinatus muscle also has a stabilising role to fulfil. Without the stabilising contribution of the supraspinatus muscles, the “ball” of the shoulder would be unstable. This is because this muscle helps to keep the “ball” pressed against the socket which helps to prevent the ball slipping upwards when the arm moves.
Affected by everyday activities
The Infraspinatus and Teres Minor muscles work together to give their unique movement of lateral rotation of the shoulder (turning your arm outwards). This is important for 1000’s of every day activities, for example being able to put your hand behind your head in order to wash your hair. Again the Infraspinatus and Teres Minor muscles have an important stabilising effect on the “ball” of the shoulder as well by generating a force that pulls the “ball” downwards and slightly backwards. This stops the shoulder from sliding upwards and forwards during shoulder movement. When the arm is in full abduction, these muscles allow the “ball” to laterally rotate. This gives clearance to the tendons in the subacromial space and prevents them from being pinched, irritated and injured when moving the arm.
Lastly, but by no means least, the subscapularis muscle medially rotates the arm (turns it inwards). This allows you to do up your bra strap or put your arm into a coat sleeve. The stabilising role of the subscapularis muscle is to further reduce upward displacement of the “ball” of the shoulder when other muscles, such as deltoid, biceps and triceps, are active.
So you can see that not only is the mechanics of shoulder movement very complicated and intricate, but successful pain free movement also relies heavily on strong rotator cuff muscles and good stability and control of the “ball” of the shoulder joint. Without this control you can develop pain due to structures, including the supraspinatus tendon, being squashed in the subacromial space which can lead to inflammation and further squashing therefore more pain. It is possible to develop pain from weakness to the rotator cuff muscles as the muscles become overworked in the presence of weakness. Simple repetitive everyday tasks can become troublesome and a constant source of pain, and when shoulder pain develops other muscles quickly make compensatory changes which can cause secondary problems and pain.
Neglecting your muscles
Frequently people will neglect the smaller rotator cuff muscles in favour of developing the big power house muscles such as the pecs, biceps and triceps. But by neglecting the rotator cuff muscles you run a risk of developing pain in the shoulder by losing the control and stability of the shoulder and this can cause disruption not only to your training programme, or participation in sport but to making every day tasks difficult and painful.
This exercise helps to strengthen up the medial rotator (subscapularis). Tie a band to a door handle. Bend your elbow to 90 degrees and hold on to the band, making sure there is some tension to the band. Then keeping your elbow bent to 90 degrees turn it inwards going against the resistance of the band across your body. Repeat 8-10 times as long as you can maintain good technique.
If you have a specific shoulder problem that you think can be attributed to rotator cuff weakness than you should consult a physiotherapist first, in order to be assessed and have an appropriate rehabilitation programme created and explained to you. Depending on what the exact issues are depends on what type of exercises will benefit you best and help you achieve the greatest results and ultimately get you back to full fitness as soon as possible. So remember; the rotator cuff muscles, although they may be small in stature they are key to a happy and good working shoulder.