Your shoulder is where your upper arm bone, or humerus, attaches to your scapula, or shoulder blade, through a ball-and-socket connection. In addition to these two bones, smaller bones comprise your shoulder, including:
• The acromion, a small bone off your scapula.
• The collarbone, which attaches to your shoulder via the acromion.
• The coracoid process, which is a tiny bone on your scapula.
While these bones make up the foundational structure of the shoulder, it’s what keeps these bones working together that frequently gets injured, including your:
• Rotator cuff — the group of muscles and tendons that provide your range of motion.
• Bursa — a small sac of fluid that protects the tendons in your rotator cuff.
• Cartilage — the cartilage in your shoulder that creates a cup over your upper-arm bone.
Since your shoulder joint is complicated, numerous conditions or injuries can cause shoulder pain, including:
• Rotator cuff tears
• Frozen shoulder, which is an inflammation that limits movement
• Degenerative joint disorders, such as osteoarthritis
• Injury or trauma leading to bone fractures
• Bursitis or tendonitis
In all of these cases, limited movement of the arm or sharp intermittent pain that comes with movement often accompany shoulder pain.