Our body can do many functions.It can move, see, hear, etc.It can also perform digestion, respiration, etc.To do all these functions there are certain organs and organ systems in our body.The organs are well placed and protected in a bony cage.
Skeleton is a bony structure, present in our body.It looks like a bony frame.This frame gives not only shape to the body, but also protection to the important parts present inside the body.It is made up of more than 200 bones.
The bones are mainly made up of calcium and phosphorus.Bones are hard.They move with the help of muscle attached to them.Nearly 600 muscles are there in our body.Bones can grow also.
Red blood corpuscles are produced from the bone marrow, present inside the bones.
Main functions of the bones and muscles:
Bones give support and shape to the body.Blood cells are produced from the bone marrow.The skeleton gives protection to the vital organs of our body, such as brain, heart and lungs.
Muscles help for the movement of bones.Organs like heart, digestive canal are also made up of muscles.While some muscles help in contraction, some are useful for expansion.
So, bones and muscles work together with coordination in the movement of limbs.
Joint: The place, where two bones join together is called a Joint.There are two kinds of joints in our body.They are immovable and movable joints.
Bones of the skull are fixed.They cannot move.So, the joints in the skull are called Immovable joints.
The joints present in the neck, hand, leg and in some other parts are movable.So, these are called Movable joints.
According to the type of movements, joints are of four kinds.They are Ball and Socket joint, Hinge joint, Pivot joint and Gliding joint.
Ball and Socket joint: In this joint, the ball like end of the upper arm is fixed in the socket or a cup like structure of the shoulder bone.Such a joint is called Ball and Socket joint.
Hinge Joint: Observe the movements of elbow, while taking the food.You move your hand towards the mouth to bring food up to the mouth.You cannot bend the elbow joint in the opposite or backward direction.
Observe the doors of a house.Doors can fold only in one direction.The hinges, which are arranged to the doors allow this one sided movement.
Similarly the elbow joint acts like a hinge of a door.So, this is called a Hinge joint.
Pivot Joint: The arrangement of bones between head and neck helps to rotate the head.In this joint one bone is shaped like a ring.The other bone is arranged inside the ring.This joint helps to rotate the head freely.It is called the Pivot joint.
Gliding Joint: Observe the movements of the back bone, while bending and taking any article from the ground.
Observe the movements of your fore arm, specially while you are rotating the key to open a lock.
The joints present in those parts of the body help to move and do those functions.The bones of these joints glide together, while they are performing such activity.After completing the work the bones are brought to their normal position.Such joints are called the Gliding joints.