What are the functions of the skeletal system?
The different bones of the body meet to form a joint. These joints act as leavers to create movement. Muscles are attached to bones by tendons. As the muscles contract they pull on the bones to create movement around a joint. You need to know the joints and the movements that can occur at the joints during physical activity.
The body gets it shape and size from bones. The bones support different body positions and allow the muscles to attach to a framework to give us shape. If you are stood up, sat down or even tucked up in a somersault your bones give your body support in lots of different positions. The size of your bones can affect your height and body composition.
The body has lots of vital delicate organs that need protecting from damage. The skeleton helps protect them by surrounding some delicate parts of the body. For example, the cranium protects the brain, The ribs protect the heart and lungs and the vertebrae protect the spinal chord.
Joints and movement
A joint is a place where two or more bones meet. As the bones move at a joint there are a few things that help to keep the joint working and stable.
Cartilage - cartilage covers the ends of bones where the meet. It is a smooth surface which allows the bones to slide across each other reducing friction. It is also tough and a bit spongy to act as a shock absorber which helps cushion impacts around the joints.
Synovial fluid - Around joints there is synovial fluid to act as a lubricant. It works like oil in an engine; allow the cartilage to rub together smoothly and reducing friction.
Joint capsule - Around the joint there is a tough joint capsule which helps keep the synovial fluid in place and produces more fluid when necessary.
Ligaments - Ligaments are a tough fibre that attach bone to bone. These are located to hold bones in place and stop joints moving in certain ways. They create stability around joints. Ligaments can damaged from joints being put under strain. Joints can be dislocated out of place and ligaments severely damaged during some sports.
There are two types of joint that you need to be able to talk about in your exam. They are;
In you exam you need to use the elbow or knee as your examples of hinge joints.
X-ray of elbow
X-ray of knee
They work like a hinge of a door allowing only two types of movement, flexion (closing) and extension (opening).
You need to be able to give sporting examples of when flexion and extension occur at joints. For example, bending (flexion) your knee to draw your leg back before you kick a ball and then straightening (extension) the leg again to make contact with the ball and kick it.
Flexion at knee (leg bent)
Extension at knee (leg straight)
Ball and socket joints
Ball and sockets are more complex and allow a lot more movement. In the exam you need to use the shoulder and the hip as examples of ball and socket joints. They allow a lot of movement in many directions because the ball at the end of the bone fits into a socket which allows the bone to swivel in many ways.
The ball and socket joint can allow flexion (closing of a joint), extension (opening of a joint), adduction (the movement of a limb towards the centre line of body) , abduction (the movement of a limb away from the centre line of body) and rotation (moving the joint in a circle motion).
How to work the movements out
If the angle of the joint is getting smaller than the movement is flexion.
If the angle of the joint is getting bigger then the movement is extension.
If the movement is taking away from the body then the movement is abduction.
If the action is adding towards the body then the movement is adduction.
If the movement is around then the movement is rotation.