In the cavities of synovial joints.
Synovia or synovial fluid is a viscous, non-Newtonian fluid present in the cavities of synovial joints and has the consistency as that of an egg-white. It is a thick liquid which lubricates our joints and enables their smooth movement. They are found in our joints in the knees, hips, shoulders, feet, hands. The main role of this fluid is to decrease the friction that arises between the articulate cartilage of the synovial joints when in motion. Synovia is a very small component of the transcellular fluid, part of extracellular fluid. The synovial membrane secretes the synovial fluid inside the cavity of the joints.
When there is a movement, the synovial fluid present in the cartilage is mechanically squeezed out in order to maintain a fluid layer on the surface of the cartilage. Synovia performs some critical functions such as – decreases friction, absorbs shock, transports wastes and nutrients, molecular sieving etc.