The cartilage is smooth and slippery, it protects the ends of the bone where it meets other bones to stop them rubbing together
Exercise causes cartilage to become thicker, so our joints move smoothly and absorb shock better as we jump or run.
Functions of the skeleton
The 4 functions of the skeleton are:
- Shape and Support
- Blood Production
Types of bones in the skeleton
There are 4 types of bones in our skeleton:
- Long Bones: upper and lower arms and legs, collar bone, ribs, metatarsals, metacarpals and phalanges.
- Short Bones: carpals of the wrist, tarsals of the feet
- Flat Bones: scapula, pelvis and cranium
- Irregular bones: the vertabrae
The types of joints
Joints are where 2, or more, bones meet
The 3 types of Joints are:
- Fixed of immoveable joints- the bones cannot move at all. they are held close together by tough fibres
- Slightly moveable joints - the bones can only move a little, they are held together by ligaments and joined by cartilage.
- Freely moveable joints - the bones can move quite freely e.g. knee joint.
Examples of synovial joints
- The ball and socket joint - most moveable joint. One bone has a huge bulge like a ball at the end which fits into the socket in the other bone e.g the hip joint and shoulder joint
- The hinge joint - works like a hinge on a door. The end of one bone fits into a hollow of the other. The joint will open until it is straight but no further e.g. the elbow joint and the knee joint.
- The pivot joint - One bone has a bit that just out, this fits into a ring or notch on the other bone. The joint allows only roation e.g. the joint between the raduis and ulna, rotation here results in changing from backhand to forehand in table tennis.
- The gliding joint - The ends of the bones are flat enough to glide over each other. There is a little movement in all directions, this joint gives the least movement. E.g. the joints between carpals and tarsals and the joints between most of the vertabae.
Ligaments hold the bones together and keep them in place. They are long cords and straps that lash bones together and hold a joint in place. They are a bit elastic - enough to let the bones move.
Tendons are the cords and straps that connect muscle to bone.