What is a synovial joint?
A synovial joint is one in which the ends of the bones are enclosed in a capsule containing a thick, slippery liquid called synovial fluid. The capsule is made of strong, fibrous tissue and is lined with a membrane called the synovial membrane. The bone ends are covered in a smooth layer of a tough, rubbery substance known as cartilage. The synovial fluid in the joint capsule has four important functions: • it keeps the bones slightly apart, protecting their cartilage coverings from wear and tear • it absorbs shocks, again protecting the cartilage • it lubricates the joint, helping it to work freely and easily • it acts as a filter, letting nurtrients reach the cartilage, but blocking the passage of harmful cells and substances. The most important component of synovial fluid is a substance called hyaluronic acid. It is this substance that lets synovial fluid perform its four different functions all at the same time. Most of the joints in your body are synovial joints. Good examples, be
