Why are the rotator cuff muscles important to your shoulder? And how can you look after them?

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Jasper Marsh
6 years ago
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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!

The shoulder is essentially a ball (head of the humerus bone) and socket joint (glenoid fossa) amongst a sea of muscle.

1 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. The two images above highlight where the rotator cuff muscles are situated. The grey image on the left is looking from the front with the ribs removed so you can see the under surface of the shoulder blade. The grey image on the right shows the view from looking behind. The colour image on the right shows where the rotator cuff muscles attach into the ball of the humerus, but also highlights the acromion and the position of the subacromial space. 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.

2 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 degrees of a movement called abduction (lifting your arm out to the side see picture to right). 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. The Infraspinatus and Teres Minor muscles work together to give their unique movement of lateral rotation of the shoulder (turning your arm outwards see picture on left). 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 (see above), 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

problems and pain. 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.

training programme, or participation in sport but to making every day tasks difficult and painful.

3 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. 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. Simple exercises that you can do to help reduce the chances of developing this type of problem include: This exercise helps to strengthen up the lateral rotators (Infraspinatus and Teres Minor). 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 outwards going against the resistance of the band as far as you comfortably can. Repeat 8-10 times as long as you can maintain good technique.

This exercise helps to strengthen up the infraspinatus muscle in particular.

towel to prevent it slipping. Repeat 8-10 times as long as you can maintain good technique.

Move your arm forwards and out to the side a short way then slowly return to the starting position.

4 This exercise helps to strengthen up the infraspinatus muscle in particular. Similar to the previous exercise, put a towel under your arm and bend your elbow to 90 degrees and squeeze the towel with your elbow. Hold a small weight in your hand (a tin of beans will do), then turn your arm outwards whilst maintaining a squeeze on the towel to prevent it slipping. Repeat 8-10 times as long as you can maintain good technique. This exercise targets the supraspinatus muscle. Stand with a small weight in your hand with your palm facing backwards. Move your arm forwards and out to the side a short way then slowly return to the starting position. Repeat 8-10 times as long as you can maintain good technique. This exercise helps to strengthen up the medial rotator (subscapularis). Tie a band to a door handle just like in exercise 1, except you won t have the band running across you at this point. Bend your elbow to 90 degrees and hold on to the band, making sure there is some

5 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. Whilst this is not a comprehensive list of exercises, it is a good base line as it involves the use of all the rotator cuff muscles and will help to strengthen them. In order to strengthen the muscles you need to do the exercises on a regular basis. If you have an injury involving the rotator cuff muscles you may need to do the exercises more regularly than someone who doesn t. 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.

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