Causes of Shoulder Pain

by Stephanie Meadows
Your shoulder is a ball-and-socket joint. The ball portion of the joint consists of the rounded head of the upper arm bone (humerus), and the socket portion is made up of a depression (glenoid) in the shoulder blade. The humeral head (ball) fits into the glenoid (socket) creating the joint that allows you to move your shoulder. The joint is surrounded and lined by cartilage, muscles, and tendons that provide support and stability and make it easy for you to move. It's your shoulder joint that lets you rotate your arm in all directions. Your range of motion depends on the proper articulation of the humeral head upon the glenoid.