Bone Articulations (Joints)Joints exist wherever bones meet, and are classified according to the means by which the bones are bound together. Most joints where movement occurs are classified as synovial joints. Here, bones are held together by the joint capsule (which is strengthened by the presence of ligaments). Between the bones involved exists a joint cavity, which is surrounded by the inner surfaces of the capsule. These surfaces are lined with a specialized type of integumentary membrane, the synovial membrane, which secretes synovial fluid that acts as a lubricant so that the bones do not crunch against each other.