The shoulder joint is controlled by the surrounding muscles. These muscles also help to keep the shoulder stable.
The main muscles involved in shoulder function are the trapezius muscle, the deltoid muscle and the rotator cuff group of muscles. The rotator cuff muscle group consists of supraspinatus, infraspinatus, subscapularis and teres minor. The first three are the most important for day to day shoulder function and the first two are the most commonly injured.
Shoulder muscle pain may involve the muscles themselves or the tendons that connect the muscle to the bone. In general the latter is more common. Shoulder muscle tendon inflammation is called tendinitis.
What causes Shoulder Muscle Pain
A group of muscles surrounds the joint and helps to both control movement and provide stability. All the shoulder muscles work in co-operation with each other. Pain arises as a result of injury or due to unaccustomed overuse.
You can read related shoulder pain content elsewhere on this site - follow the links at the bottom of the page for a description of shoulder impingement and shoulder bursitis. Both of these conditions are closely related to shoulder muscle pain.
Injury to the shoulder muscles or to the tendons triggers an initial inflammation reaction. This can progress to muscle or tendon damage and - in a few cases - eventual shoulder muscle tear or rupture of the tendons.
Shoulder muscle pain is often associated with bursitis or inflammation in the bag of fluid that surrounds the muscles and their tendons.
How to diagnose Shoulder Muscle Pain
The symptoms of shoulder muscle pain often begin gradually over some weeks or months. Pain is the main problem. Rarely the problem can start with severe pain and progress rapidly but this is not common. More often it starts with a gradual pain in the region of the outer part of the shoulder - over the deltoid muscle. Having problems trying to sleep on the affected side is a common symptom. Lifting, reaching out or using the arm above the head are common triggers for the pain.
Shoulder muscle pain is felt over the deltoid muscle area around the shoulder. It may spread down the arm towards the elbow or wrist. The pain is made worse by lying on the affected side, by lifting or carrying or by trying to use the arm above the head.
Some people become aware of a "painful arc" of movement. This means that they have no pain when their arm hangs by their side but they develop a pain as they lift their arm up and outwards. The pain often arises when their arm reaches about sixty degrees of elevation. Once they get a bit beyond the ninety degree point, the pain eases again or goes away completely.
If a doctor or therapist resists the patients attempt to contract the affected muscle then the pain will become more pronounced.
If a muscle tear is suspected then your doctor may organise an ultrasound scan or an MRI scan of the shoulder region
How to treat Shoulder Muscle Pain
The treatment of shoulder muscle pain will in part depend on the cause that your doctor or therapist discovers.
One of the most important aspects of treating shoulder muscle pain is to stop doing the movement or activity that provoked it in the first place.
Of course this may be easier said than done but you might consider changing your technique or equipment if you are involved in sport. If your muscle pain has been triggered by work then give some thought to changing the way that you tackle your job tasks and activities.
Treatment options for shoulder muscle pain include:
painkiller or anti-inflammation medication
physical therapy from a physiotherapist, chiropractor or osteopath
