The Rotator Cuff Muscles Function Collectively
The Rotator Cuff muscles act on the shoulder joint to pull the head of the humerus downward and into the glenoid fossa. This is illustrated in the picture below by the arrows following the line of pull of each muscle.
And Have Unique Actions Such As
raising your arm up and out to the side;
pulling your arm down and in to your side from the raised, side horizontal position
and from the front horizontal position;
also, from the front horizontal position, pulling your arm directly back to the side
and, rotating your arm outward;
or, rotating your arm inward.
Although your rotator cuff muscles participate in these movements with a number of other
muscles, you will still want to specifically isolate and train them to achieve a more complete
conditioning, and therefore maximize their ability to function properly and maintain the
integrity your shoulder joint.