What is a bursa?

• A. A fluid-filled bag cushioning tendons as they slide over bones and reduces friction
• B. A system of muscles that produce movement
• C. Longitudinally oriented filaments that extend along the muscle
• D. Unstriated fibers lining various organs and blood vessels

Answer: (B)

Bursae are small fluid-filled sacs that act as cushions between moving tissues, especially where tendons glide over bones. They’re lined with a synovial membrane and filled with synovial fluid, which lets tendons and other soft tissues slide smoothly, reducing friction during movement. This makes the description of a fluid-filled bag cushioning tendons as they slide over bones and lowering friction the best fit. The other ideas describe different tissues: one is the muscular system that generates movement, another refers to the filaments inside muscle fibers, and the last describes smooth muscle lining various organs and vessels.