The Joint of Human Body

There are three type of joint.

Ball and Socket Joints

These are found in the shoulder and the hip. They allow a circular movement in these joints. At the shoulder the 'ball' is part of the humerus, the long bone in the top of the arm. The 'socket' is formed by the scapula or the shoulder blade. The muscles joined to these bones allow a circular movement when they contract. In the hip it is the femur which provides the 'ball'. The pelvis, or hip bone, provides the socket.

Hinge Joints

These are found at the elbow and the knee. They allow a movement of 180° in one direction. Try moving your arm at the elbow. It can only move in a half circle (180°) and only up and down. Now move your arm from the shoulder and see the difference.

Semi-movable Joints

These joints only move slightly. They can be found in the backbone. The backbone is made of many small bones called vertebrae. Each one of them is called a vertebra. The semi-movable joints are between the vertebrae. Because there are so many vertebrae there are many semi-movable joints.

Each one moves very slightly but when they move together it make the movement more obvious.

Immovable Joints

These joints do not move at all! You can find them in the skull. they have grown together like a very complicated jig-saw puzzle. When babies are born care is taken not to bump their heads. This is because the bones in the head are still soft and have not yet grown together. Within a few months the bones meet each other as the baby grows. Eventually they are so well held together that they are impossible to separate.

About skeleton JointThere are three type of joint in human skeleton.

1. Fibrous2. Cartilaginous3. Synovial

FibrousFibrous joints connect bones without allowing any movement. The bones of your skull and pelvis are held together by fibrous joints. The union of the spinous processes and vertebrae are fibrous joints.

CartilaginousCartilaginous joints are joints in which the bones are attached by cartilage. These joints allow for only a little movement, such as in the spine or ribs.

SynovialSynovial joints allow for much more movement than cartilaginous joints. Cavaties between bones in synovial joints are filled with synovial fluid. This fluid helps lubricate and protect the bones. Bursa sacks contain* the synovial fluid. 

Hinge A hinge joint allows extension and retraction of an apendage.

Saddle A saddle joint allows movement back and forth and up and down, bot does not allow for rotation like a ball and socket joint.

Ball and Socket A ball and socket joint allows for radial movement in almost any direction. They are found in the hips and shoulders.

Gliding In a gliding or plane joint bones slide past each other. Midcarpal and midtarsal joints are gliding joints

Ellipsoid

Ellipsoid joints are similar to a ball and socket joint. They allow the same type of movment to a lesser magnitude. The wrist is an ellipsoid joint.

Pivot

Pivot joints allow rotation arround an axis. The neck and forearms have pivot joints. In the neck the occipital bone spins over the top of the axis. In the forearms the radius and ulna twist arround each other.

The Joint Part 2end

Major Joints of the Body

Joint Type Degrees of Freedom

Vertebrae Amphiarthroidial 3

Hip Ball-and-Socket 3

Shoulder Ball-and-Socket 3

Knee Condyloid 2

Wrist Ellipsoid 2

Metacarpophalangeal (fingers) Ellipsoid 2

Carpometacarpal (thumb) Saddle 2

Elbow Hinge 1

Radioulnar Pivot 1

Atlantoaxial Pivot 1

Ankle Hinge 1

Interphalangeal Hinge 1

Vertebrae & Amphiarthrodial

Hip & ball

and socket

Knee & Condyloid

Wrist & Ellipsoid