The shoulder is a highly mobile joint. However, with mobility comes instability, and the muscles of the shoulder take a lot of strain. This means shoulder trigger points are very common.
The shoulder muscles can be put into three groups: the rotator cuff muscles, postural muscles, and power muscles.
Rotator cuff muscles:
The muscles of the rotator cuff all act in harmony to stabilise and rotate the humerus in the shoulder joint socket. They are very prone to getting trigger points, as they have to balance large forces and work in perfect coordination.
Of the rotator cuff muscles, the infraspinatus and supraspinatus are the most vulnerable. In particular, the supraspinatus has to pass under the acromion bone to attach into the head of humerus. When this muscle has trigger points, it can cause impingement due to not coordinating shoulder movement properly.
So the supraspinatus is a very important muscle, and is often missed as a cause of shoulder pain, impingement, and bursitis.
The power muscles of the shoulder provide the force for actions like lifting, swimming, sports. All the movement when you need to direct force through your arms – this is where the power muscles come in.
These muscles are strong and less likely to get trigger points. However, if undue force is used, or you’ve become deconditioned, you can certainly set off triggers in these muscles.
Again, power muscles tend to be close to the surface and easy to reach, and is the case for all the shoulder power muscles.
The upper trapezius muscle contains the most common trigger point in the body. However, all the posture muscles of the shoulder are very likely to get trigger points.
This is especially true for people who spend a long time hunched over computers, or cellphones, or driving. Poor posture is a big cause of triggers, and can create a lot of pain and muscle stiffness.
When the shoulder muscles are tight, this often creates a corresponding tightness in the chest muscles. While pectoralis major and minor are located in the chest, they affect the shoulder joint at are involved in many arm movements.
If you want to fully release shoulder posture muscles, you’ll often need to find and treat your chest muscles as well.