text: what is bursitis and what is a bursa?   bursae are small sacs between your the bones, tendons, and muscles in your joints.  they contain fliuids that help your joints move more easily.  bursitis is an inflammation of a bursa, typically caused by overuse or repetitive use of the affected joint.  it typically goes away in about a week with proper treatment, which usually involves rest, ice, and anti-inflammatory medications like ibuprofen (advil, e.g.).