The shoulder joint is a ball on the top of your arm bone and socket which is a part of the shoulder blade. Above the ball and socket, the joint is a ligament that is attached to a bony prominence on your shoulder blade. This forms an arch. The area between the arch and shoulder joint is known as the sub-acromial space Dr. Shekhar Srivastav - HOD Sant Parmanand Hospital is a leading Shoulder Arthroscopy Rotator Cuff Repair Surgeon in Delhi