What is the term for a small fluid-filled sac that develops at the point where a muscle or tendon slides across a bone?

The term for a small fluid-filled sac that develops at the point where a muscle or tendon slides across a bone is "bursa." A bursa serves as a cushion to reduce friction and irritation between these structures, which is particularly important in areas where movement occurs frequently. This fluid-filled sac contains synovial fluid, which lubricates the joint and protects the tendon or muscle as it moves over the bone. The presence and function of bursae help to facilitate smooth, pain-free movement during physical activity. Understanding the role of a bursa is crucial for those involved in fields like anatomy, physical therapy, and rehabilitation, as it underscores the importance of minimizing friction in musculoskeletal movement.

Cysts, abscesses, and fibromas refer to other types of fluid collections or growths, but do not specifically serve the same functional purpose as a bursa in the context of muscle and tendon interaction with bones.