Q.5 Define Joint and write down the types of Joints.
Answer
Joints:
A joint is a location at which two or more bones make contact. Joints allow movement and provide mechanical support.
Types of joints: Joints can be classified on the basis of degree of movement they allow..
1) Immoveable joints (Fixed).
2) Slightly moveable joints
3) Moveable joints
1. Immoveable joints:
Such joints allow no movement e.g. the joints between the skull bones.
2. Slightly moveable joints: 
Such joints allow slight or little movements e.g. joints between the vertebrae.

3. Moveable joints:
They show a variety of movements e.g. shoulder joint, hip joint, elbow joint, knee joint etc.
Types of Moveable Joints
There are many types of moveable joints:
1) Hinge joint
2) Ball and socket joint
1. Hinge joints:
Hinge joint move back and forth like the hinge on a door and allow movements in one plane only. The knee and elbow are hinge joints.
2. Ball and socket joints:
These joints allow movement in all directions. The hip and shoulder joints are ball and socket joints.