What is a joint?
Have you ever wondered how we are able to bend and rotate our body parts? It is because of the joints present in our body.
The place where two or more bones are joined together is known as a joint.
Bones are rigid structures that cannot be bent or rotated. But still, we can do so with the help of joints. Hence, joints play a prominent role in the movement and locomotion of animals such as humans.
These joints are of different types and are broadly categorized into two categories. They are the movable and the immovable or fixed joints.
Movable joints:
The joints that allow movement are known as movable joints. These joints include the ball and socket joint, pivotal joint and hinge joint.
Ball and socket joint:
It is a type of joint found in the shoulder bone. In this joint, a ball-like surface of the bone fits into the cup-like hollow space of the other. It is a joint that allows movement in all the directions.
Pivotal joint:
It is a joint in which a cylindrical bone rotates in a ring. It is the joint that connects the neck with the head. We can bend, turn our head due to the presence of this joint.
Hinge joint:
The joints found in the elbow and knee that allows only a back and forth movement is known as a Hinge joint.
Immovable joints:
The joints that do not permit any movement are known as fixed or immovable joints. The joint between the upper jaw and the remaining portion of the head is a fixed joint. The joints found between the bones of the skull is an example of this joint.
Movement of bones in the joints:
Bones cannot move on their own. The muscle brings about the movement of bones. The muscle is the prominent tissue that plays a significant role in the movement of the bones. Muscle is a tissue that works in pairs as they cannot push. The movement of the bone is brought about the contraction of one of the muscle.
Among the pairs of the muscles, when one of the muscle contracts the other relaxes. The bone is moved in the direction in which the muscle contracts. To move the bone in the opposite direction, the muscle which is under relaxation contracts to pull the bone towards its original position. During this, the other muscle relaxes.
Hinge joint