This structure is called the acromion process. Often times, this condition is caused by a combination of overuse and improper strength or balance of strength of the muscles of the shoulder girdle, most specifically, but not exclusively the rotator cuff. After a proper evaluation is performed and if in deed some of the above conditions exist, then a proper exercise regimen is instituted to restore proper mechanics to the shoulder. These exercises include resistance training for the rotator cuff itself with resistance applied either with weights, latex bands or latex tubing to internal and external rotation of the shoulder. I also recommend an exercise that we call a bench press with a plus.
Shoulder shrugs are also advisable.
The earlier that this condition is diagnosed by an orthopedist or sports medicine specialist and then evaluated and addressed by a properly trained physical therapist the better the long term result. If this condition is allowed to become chronic over too long a period of time, it can result in damage to the rotator cuff tendons and persistent shoulder pain. For a more detailed explanation of the shoulder's anatomy, I would recommend a review of the information and anatomical pictures in The Shoulder article recently published to this website. If you have further questions, I invite you to ask them on the sports medicine discussion forum, and others or I will be more than pleased to answer them. T hank you for your question Wendy.