Rotator Cuff Muscles: The basics

Rotator cuff exercises

If you have injured your shoulder in the past it is likely you will have heard of the rotator cuff muscles. You may also have been given specific exercises to strengthen them. Many people, however, have very little idea what these muscles are and what they are primarily designed to do.

The rotator cuff muscles are a group of 4 muscles with the main role of stabilising the shoulder joint. The shoulder joint (known as the glenohumeral joint) is inherently unstable. This is largely because the joint capsule is very shallow. The benefit of this shallow joint capsule is that it allows a large range of motion at the joint. This does mean that the stability at the joint is compromised. This is where the rotator cuff muscles come in. They are very small muscles that attach over the joint coming from the front, back and top of the joint. When the muscles are functioning correctly they will co-contact (firing together) to stabilise the joint through it's large range of motion.

If these muscles contact in isolation rather than co-contracting as a group they perform very specific movements. Below are the names of each individual muscle and the specific action it creates:

Supraspinatus: Abducts, or elevates, the shoulder joint.
Infraspinatus: Externally rotates the shoulder joint - or turns it outwards.
Teres Minor: Externally rotates the shoulder joint - or turns it outwards.
Subscapularis: Internally rotates the shoulder joint - or turns it inwards. The subscapularis muscle also works to depress the head of the humerus. This prevents the joint getting compressed during overhead movements.

Due to the specific actions each muscle creates, exercises to isolate and strengthen the rotator cuff muscles are often broken down into their separate actions:

Abduction (Lifting the arm away from the body) - Click here to see a series of exercises to strengthen the Supraspinatus => 5 Exercises

External Rotation (Turns the arm outwards) - Click here to see a series of exercises to strengthen the Infraspinatus and Teres Minor => 7 Exercises

Internal Rotation (Turns the arm inwards) Click here to see a series of exercises to strengthen the Subscapularis => 5 Exercises

As always with this type of blog post, it is for information only, please consult a musculoskeletal therapist before starting any of the above exercises. Rehabilitation exercises always need to be specific.