Subscapularis Action and Function
The subscapularis is an important muscle of the shoulder. It is located right in front of the shoulder blade, an area called subscapularis fossa and inserts in the lesser tuberosity of the humeral head. The subscapularis muscle and associated tendon are part of the well-known “rotator cuff”, an important structure responsible for the dynamic stability of the shoulder joint. The main action of the subscapularis is to internally rotate the arm, i.e. bringing your arm to your stomach. However, it also has a major role in stabilising the shoulder during the extension of the arm (i.e. bringing your arm back).
What causes Subscapularis pain?
Pain in the subscapularis muscle is generally due to overuse. Repetitive actions are generally responsible for symptoms onset, such as consistent bowling in cricket or serving in tennis. This generally leads to subscapularis tendinopathy, with pain and some degree of shoulder weakness, depending on how irritable your symptoms are. This condition is generally managed conservatively, with exercises that preferentially load the subscapularis muscle.
Another common cause of subscapularis pain is a tear within the muscle or the tendon. This can have a traumatic origin, typically in the younger population, or degenerative origin in older adults. Symptoms tends to vary depending on the extent of the tear. Generally, pain and weakness are noticed with internal rotation and with bringing your arm to your back. In the event of a small tear, a graded exercise program should resolve the problem. However, in a significant tear with likely compromise of shoulder stability, an Orthopaedic consultation is warranted.
Lastly, calcification around the area of insertion of the subscapularis muscle may be responsible for the symptoms. A calcification is a deposit of calcium that tends to affect people between the age of 40 and 60: people with thyroid dysfunction and diabetes seem to be more predisposed. The calcium deposit can impair mobility and functioning of the subscapularis tendon, with often high pain levels and disability as a result. Treatment for this condition generally involves shockwave therapy, corticosteroid injection, or surgical removal of the calcific deposit as the last resort.
Resisted Internal Rotation with a band:
- Hold a resistance band to the side of your body with the elbow bent
- Keep the elbow close to your side and pull the hand across the body
- Slowly release the hand away from the body
Shoulder Flexion Against Resisted Internal Rotation
- Hold a band in your hand, with the other end attached beside you
- Bend the elbow to generate tension on the resistance band
- Raise the arm forward, keeping the elbow bent
- Slowly lower the arm down, keeping your elbow bent, with a good shoulder position
Isometric Subscapularis Exercise
- Bend your elbow then rotate your arm towards you
- Place the other hand over the wrist to resist movement of the wrist to the stomach
- Apply a firm pressure that you can tolerate for the time prescribed
- Relax the arm