A bursa is a small, fluid-filled sac located between bone and surrounding soft tissue, bones and tendons, and/or muscles around joints. They are useful to the human body by reducing tension and negative effects of wear-and-tear at points of friction and provide resistance-free movement by the human body. The bursa sac is lined by a synovial membrane or synovium, which contains the synovial fluid that is comparable to the consistency of raw egg whites. The sac is semi-permeable and allows certain materials to flow in and out of its membrane; when there is an injury to the bursa, fluid, such as blood, can fill the sac and cause irritation. There are up to 160 bursae present in the human body, and they vary in size and shape depending on the person and the location of the bursa. Bursae are classified as superficial when their structure lies between bones, tendons, or skin, and deep when they’re between bones and muscles. The most common clinical scenario related to bursae is the inflammation of bursae called bursitis. The typical clinical presentation is localized pain in the area around the inflamed bursa combined with a restricted range of movement.