Question

What lubricates the freely movable joint at the shoulder?

Answer 1

Synovial fluid, also called synovia, is a viscous, non-Newtonian fluid found in the cavities of synovial joints. With its egg white–like consistency, the principal role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement. The shoulder joints are encapsulated in the synovial membrane, which produces synovial fluid.