What is shoulder bursitis?
A bursa is a tiny fluid-filled sac that functions as a gliding surface to reduce friction between tissues of the body. The plural of bursa is bursae. There are 160 bursae in the body. The major bursae are located adjacent to the tendons near the large joints, such as the shoulders, elbows, hips, and knees.
Bursitis is inflammation of a bursa. Injury or inflammation of a bursa around the shoulder joint occurs causes shoulder bursitis.
How does a bursa become inflamed?
A bursa can become inflamed from injury, infection (rare in the shoulder), or an underlying rheumatic condition. Examples include infection of the bursa in front of the knee from a knee scraping on asphalt (septic prepatellar bursitis), inflammation of the elbow bursa from gout crystals (gouty olecranon bursitis), or injury as subtle as lifting a bag of groceries into the car, which could inflame the shoulder bursa (shoulder bursitis).