Types of union between cartilages or bones in the skeleton of human body.
Area of union between cartilages or bones in the skeleton are called joints in anatomy. The bones of movable joints are wrapped with smooth cartilage and lubricated by a thick fluid, called synovial fluid, produced between the bones in membranous sacs, know as bursae. Inflammation or bursitis of the bursae is a common painful circumstance of movables joints.
Joint example via Wikipedia
Synarthroses are inflexible, immovable joints, such as the connections between the bones of the skull; diarthroses are movable joints, such as the meeting of the bones of the limbs with those of the trunk at the shoulder and hip.
Joints: 1- Ball-and-socket, 2- ellipsoid joint, 3- saddle joint, 4- Hinge Joint, 5- Pivot Joint via Wikipedia
Typical movable joints consist of an external layer of fibrous cartilage giving rise to strong ligaments which support the separate bones. Immovable joints are held together by actual inter growing of bone or by powerful fibrous cartilage. Slightly movable joints are held together by flexible cartilage.
The human organic structure has several types of movable joints. Pivot joints, permitting rotation only, are found between the first two vertebrae; the head rotates from side to side on a joint of this type called the axis. Hinge joints, allowing movement in one plane simply, are found in the knees, fingers, and elbows.
Gliding joints, in which the surfaces of the bones move a short length over each other, are found between the various bones of ankle and of the wrist. Ball and socket joints, which allow free movements in all directions, are found in the shoulder and hip.