Bursa

A bursa is a small fluid-filled sac which helps reduce friction between bones and tendons to allow free movement. There are hundreds of bursae in the body, and they are found around most major joints.

Definition of a bursa

A bursa (plural bursae or bursas) is a small fluid-filled sac lined by a synovial membrane with an inner capillary layer of viscous fluid (similar in consistency to that of a raw egg white). It provides a cushion between bones and tendons and/or muscles around a joint. This helps to reduce friction between the bones and allows free movement. Bursae are filled with synovial fluid and are found around most major joints of the body. (Source: Wikipedia)

If a bursa is irritated and becomes inflamed a bursitis may develop.

For more information about bursae and bursitis read more under the following links: