The human skeletal system

In a nutshell

The human skeleton is a very important structure that gives the body its shape. The skeleton is made up of many different bones and joints. The four main jobs of the skeleton are protection, support, movement and making blood cells.

The skeletal system

There are $206$ bones in an adult human. All the bones in the body make up the human skeleton. Bones have two main layers.

Outer layer	Made from really strong and hard tissue. This stops the bones from bending or breaking.
Inner layer	Made from a lighter and more spongy layer. It is more flexible than the outer layer but is still very strong.

The main bones you need to know about are shown below.

Science; Human skeleton and muscles; KS3 Year 7; The human skeletal system

1.	Skull (cranium)	Protects the brain.
2.	Collarbone (clavicle)	Supports the shoulder.
3.	Ribcage	Protects the heart and lungs.
4.	Spine (vertebrae)	Provides general support and protects the spinal cord.
5.	Pelvis	Supports the weight of the upper body and protects the pelvic organs.
6.	Thigh bone (femur)	Supports the weight of the upper body and assists in movement.
7.	Knee cap (patella)	Protects the knee joint and allows leg movement.

Functions of the skeleton

The human skeleton has four main jobs.

Function	Explanation
Protection	As bone is rigid and tough, it is strong enough to protect the body’s important organs. The skull protects our brain, and the ribs protect our heart and lungs.
Support	The skeleton provides a framework for all the muscles and tissues to attach to. This helps the body to stay standing upright.
Movement	The skeleton’s bones provide surfaces for muscles to attach to. When these muscles contract, they allow the skeleton to move in different ways.
Making blood cells	Many bones in the skeleton contain a soft tissue called bone marrow in the centre of them. The bone marrow produces red blood cells and white blood cells. *Curiosity:* Red blood cells carry oxygen around the body. White blood cells protect the body from infection.