When I received my MRI back from the doctor’s office it just said “rotator cuff tear”. What a tease! There are four rotator cuff muscles in the shoulder and each of them does a different, vitally important role. Even medical professionals tend to lump them together into one poorly-defined category. But the better you know each one and can strengthen them with precision, the easier it will be to keep your shoulders happy and healthy. The rotator cuff muscles are responsible for the rotational qualities of your arm bone in your shoulder