Functions of Skeleton
The skeleton inside our body is there to support us in movement and standing and doing various activities.
One of its functions is that it protects various internal organs such as the cranium protects our brain and the ribs protect the heart and the lungs.
Second being that the bones produce blood platelets and blood cells. The bone marrow of the bones such as the femur, pelvis and the vertebrae produces blood cells and platelets which forms the blood.
The skeleton also helps humans and animals stand firm and keeps the body in a specific shape and size.
Also it forms the joints which helps in movement called locomotion.
To understand movement you should learn that planes are a flat surface which is imagined around an object. A 3 dimensional object has 3 planes.
There are three types of joints found in the body.
- The immovable joints which do not move such as the skull bones.
- The partially movable joints which moves only partially like the vertebral column
- The movable joints which allow free movement such as the knees, elbow and shoulder joints etc.
The knee and elbow joint are compare to a hinge. These provide movement in one direction only. Take the elbow for an example. When you flex it there will come a point where you can’t move it further just like a hinge. The ulna and radius fit into the humerus like hinge which limit the movement to one direction.
Now if you take the shoulder and the pelvis-femur joint for an example you would notice that you can move it around the 3 planes easily meaning you can move it backwards, forwards, left and right. In this case we compare it to the ball and socket.
How joints are attached
Joints are attached by a capsule and ligament to prevent dislocation of the bone. For preventing friction there is a membrane found inside the capsule called the synovial membrane which secretes a substance called the synovial fluid which lubricates the bones for movement. Further the ends of each bone in the joint has a cartilage layer in it which acts as shock absorbents.
How we Move
Movement is supported by the bones it is not done by it. Movement occurs with the contraction of the muscles found on the bones. The best example would be the biceps and the triceps
which you would be familiar with. When the biceps contract then the triceps relax making the arm rise or flex. When the triceps contract and the biceps relax the arm descends. the muscles basically pull on each other.