Bones and Skeleton

Framework of the Human Body

All the bones in our body form a framework to give a shape to our body. This framework is called the skeleton.  Thus a skeleton is made up of many bones. These bones give your body structure, let you move in many ways, protect your internal organs, and more. 

The bones in our body have various shapes.  One way to see the shapes of the bones in our body is by looking at the X-ray images of the human body. An X-ray is a photograph of the inside of the body that helps to find out about any possible injuries that might have happened to the bones by showing the shapes of the bones in our bodies. 

Few Parts of the Skeleton 

Skull

Your skull protects the most important part of all, the brain. You can feel your skull by pushing on your head, especially in the back a few inches above your neck. The skull is actually made up of different bones. Some of these bones protect your brain, whereas others make up the structure of your face. If you touch beneath your eyes, you can feel the ridge of the bone that forms the hole where your eye sits. 

Shoulder Bones 

Make your friend stand with his hands pressed to a wall. Ask him to and try to push the wall. You will see two bones standing where his shoulders are.  They are called shoulder bones. 

Ribs

Ribs act like a cage of bones around your chest. Some important internal parts of our body like the heart, lungs and liver lie protected inside this cage. It's easy to feel the bottom of this cage by running your fingers along the sides and front of your body, a few inches below your heart. If you breathe in deeply, you can easily feel your ribs right in the front of your body, too. 

You might have noticed that the ribs are curiously bent. They join the chest bone and the backbone together to form a box. This is called the rib cage.  Your ribs come in pairs, and the left and right sides of each pair are exactly the same. All the pairs of ribs are attached in the back to the spine. 

Spine

The spine, or backbone, protects the spinal cord, which is the message pathway between the brain and the body.  The spine lets you twist and bend, and it holds your body upright. It also protects the spinal cord, a large bundle of nerves that sends information from your brain to the rest of your body.  The spine or the backbone is made of many small bones. The rib cage is joined to these bones.  

Your spine is one part of the skeleton that's easy to check out. Reach around to the centre of your back and you'll feel its bumps under your fingers.  You can also ask a friend to touch his toes without bending his knees and then put your fingers at the centre of his back, you can feel the long and hard structure which is the backbone.  

Pelvis

The pelvis is a bowl-shaped structure that supports the spine. They enclose the portion of your body below the stomach. This is the part you sit on. The pelvis acts as a tough ring of protection around parts of the digestive system, parts of the urinary system, and parts of the reproductive system. 

Cartilage

There are some additional parts of the skeleton that are not as hard as bones and that which can be bent. These are called cartilages. They are semi rigid yet flexible. They form parts of the body where more flexibility is required. 

To know how a cartilage is, try feeling your ear. There are no hard bony parts that cannot be bent. Now press together the ear lobe and the portion above it between your fingers. You will feel something in the upper part of the ear that is not as soft as the ear lobe but, not as hard as a bone. This is cartilage. Cartilage is also found in the joints of the body. Few examples of other parts it can be found are - the nose, elbow, knee, and ankle. 

Muscle

Muscles are the "engine" that your body uses to propel itself, they turn energy into motion. Make a fist with one hand, bend your arm at the elbow and touch your shoulder with the thumb If you now touch your upper arm with the other hand you will feel a swollen region inside your upper arm.  This is a muscle. The muscle bulged due to contraction (it became smaller in length). When you bring your arm back to its normal position the muscle relaxes and return to normal. You can observe similar contraction of muscles in your leg when you walk or run. 

When contracted, the muscle becomes shorter, stiffer and thicker. It pulls the bone. Muscles work in pairs. When one of them contracts, the bone is pulled in that direction. The other muscle of the pair relaxes. To move the bone in the opposite direction, the relaxed muscle contracts to pull the bone towards its original position, while the first relaxes. A muscle can only pull. It cannot push. Thus, two muscles have to work together to move a bone. 

Summary

  • Bones and cartilage form the skeleton of the human body. It gives the frame and shape to the body and helps in movement. It protects the inner organs.
  • The skeleton comprises the skull, the back bone, ribs and the breast bone, shoulder and hipbones, and the bones of hands and legs.
  • The bones are moved by alternate contractions and relaxations of two sets of muscles.

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