What is mainly contained within bursae in synovial joints?

Within bursae in synovial joints, the primary substance is synovial fluid. Bursae are small, fluid-filled sacs located throughout the body and are particularly prevalent in areas where friction occurs, such as between bones and tendons or muscles. Their main role is to reduce friction and allow for smooth movement between structures, providing cushioning and lubrication.

The synovial fluid contained within bursae serves not only as a lubricant but also helps to provide nourishment to the surrounding structures, aids in shock absorption, and plays a role in the immune response by containing various proteins and cells that can help combat inflammation. This is crucial for maintaining joint health and function during movement.

In contrast, cartilage is a connective tissue that provides support and reduces friction at joint surfaces but is not contained within bursae itself. Bone marrow is located within the cavities of bones and is responsible for producing blood cells, while nerve endings are more associated with the sensory functions of joints but do not characterize the main content of bursae.