Various bones are connected to each other with the help of Joints. Joints render many types of relative movement to the bones. And according to the type of motion they offer, joints are of numerous types. Despite of existence of many types of joints, their basic construction, more or less remains the same.

The principle elements which unite in construction of joints are: Bones, Cartilage, Synovial membrane and Ligaments.

• Bones: Bones are the principle element forming the joint. Follow the link for more information on Bones.
• Cartilage: The joint ends of the Bones are coated with a thin and elastic layer called cartilage. Its main purpose is to provide a cushioning against every type of shock on the Body. There are many activities which render great amount of shocks to the Body, for e.g. running, playing, Jumping, Fighting etc. The second most important benefit offered by Cartilage is to prevent the Bones to rub against each other, by providing a protective covering to them.
• Synovial Membrane: A very delicate connective tissue, lining the capsules of the Joints is called Synovial Membrane. It also provides a covering to Ligaments connected with Caps. Joint oil called Synovia, is secreted from this membrane. This thick and glairy oil helps the smooth functioning of the Joint.
• Ligaments: These are generally the bands or bundles of Fibrous tissues, with which the bones are held together. Ligaments are very similar to parallel ATA (PATA) cables, used for connecting storage devices with the motherboard of computers. The fibers are very closely interlaced with each other and present a silvery and shiny aspect.  Ligaments prevent the bones from getting dislocated and provide a controlled movement to the joint. The basic features of Ligament fibers include: their high strength, high flexibility, high toughness and low extensibility  Ligaments are so tough that bone will be broken before any rapture takes place in them.

Besides these elements, there are muscles, which provide a great help in maintain the joint surfaces in proper relation. Another important component in proper functioning of the joints is the pressure of the outside air. That is why, the hip joints are so completely surrounded by the Ligaments that joint becomes completely airtight. Any damage to this protective covering will reduce the air pressure. And this reduced air pressure is very dangerous to the health of bones.