The three different types of joints in the body of every human being are basically classified as fibrous joints, cartilaginous joints and synovial joints. The fibrous joints of the human body are those joints which connect the bones of the human body and do not allow any movement. The bones of the skull and the pelvis, the union of the processes of the spine and the vertebrae are examples of fibrous joints.
The cartilaginous joints are defined as those joints in which the bones are attached by cartilage. These are slightly more flexible. The joints in the spine and the ribs are examples of cartilaginous joints. The synovial joints are defined as those joints which are the most flexible. The cavities between the bones in the synovial joints (such as the Bursa sacks) are filled with a fluid which is known as synovial fluid. It helps to lubricate and protect the bones.
Bones can move because of the way they are joined together. The place where two or more bones come together is called a joint. The bones at a joint are held together by strong bands of tissue called ligaments which allow the bones to move. However, there are several different kinds of joint, and each one moves differently.
The ball-and-socket joint is found in the hip-bone and the shoulder and allows the most movement of all the joints. One bone (like the femur my student found) has a ball-like knob at the end of it, and the knob fits into a cup-like space on the other side. The ball-and-socket joint is what allows baseball pitchers to throw a ball with such tremendous speed.
The sliding joint is found in the vertebral column and allows small sliding movements. The vertebrae have pads of cartilage between them, and the bones slide over these pads. This is what makes the backbone so flexible.
The pivot joint allows movement turning from side to side, and your head is attached to your vertebral column with this joint. A hole in one bone fits over a pointed part of the other bone, so that one bone can turn on top of the other.
The hinge joint allows bones to move back and forth, and is found in your elbow and knee. It allows bones to move like a hinge in a door.
It might seem funny, but there is one type of joint which doesn't allow any movement at all. A joint between bones that do not move at all is called a fixed joint, and one place the fixed joint is found is in your skull. When babies are born, their skull bones are not joined together yet. In fact, there is a gap between them called the fontanel, or soft spot. However, the bones quickly grow together to protect the brain.
1. Fixed joint 2. Pivot joint 3. Ball-and-socket joint 4. Sliding joint 5. Hinge joint
In fact, all your life the bones of your skeletal system are changing. They are constantly renewing themselves, making new bone tissue. That is because the bones inside your body are living organs, made of cells and tissues, working together to help your body live and move.