The rotator cuff is a muscle-tendon plate that extends like a sheath around the shoulder joint. The muscles originate at the scapula and attach to the humeral head. The four tendons serve to provide mobility and stabilization of the shoulder joint.
A rotator cuff tear refers to a damage or an injury to one or more tendons of this muscle-tendon plate. A tear can affect parts or the entire tendon. Tears are partly a result of wear and tear. For instance, if you sent all 60-year-olds to an MRI exam, you would find a tear in the rotator cuff in about 50%. These tears do not always cause symptoms and do not require treatment in certain cases. Complete tears are a separation of the tendons from the bone.
Tears can occur within the tendon (intratendinous), on the top of the tendon (bursal partial tear), or at the bottom of the tendon (partial articular tear, also known as a PASTA lesion).