The place where two bones join are called Joints.
Joints may be Fibrous, Cartilaginous or Synovial Joints.
Fibrous joints are fixed while cartilaginous are slightly movable and Imperfect joints.
Sutures : These are joints between flat bones found in the skull.The bones are held together by inter locking arrangement. A thin layer of fibrous connective tissue is present at the sutures.
Synovial joints freely move and are Perfect joints which are further classified into many types given below.Synovial fluid lubricates the joints.
Ball and socket joints show movement in all directions. In this one end of the bone is rounded and it fits into a corresponding socket in the other bone.The shoulder and hips joints are of this type. In the shoulder joint a cavity called glenoid is formed by the shoulder bone (scapula). The bone of humerus has a rounded end which fits into this. Similarly in the hip joint in the cavity called acetabulum the femur head fits in.
Hinge joints show movement in only one direction. The type of movement is flexion-extension. e.g. : Knee, Elbow.
Pivot joints show rotatory movement. The joints between the radius and ulna of the forearm which permits pronation and supination is an example. Another example is the joint between the first vertebra (atlas) and the odontoid process of the second vertebra.
Gliding joints show gliding movement.The bones are joint by flat articular surfaces.The bones can glide or slide over one another to produce different kinds of movements.e.g bones of the wrist (carpals)and of ankle (tarsals).
Saddle joints move in many directions e.g. : Fingers
Condylar joints show movement in one place only. This is similar to hinge joint. But is more flexible as movement in two planes is possible. The wrist joint between the forearm bones and the carpals are of this type.
