Wherever two or more bones meet, they form a joint. Some of these joints aren’t moveable, such as the skull, but most are flexible, allowing some movement between the bones.
Joints give skeletons flexibility for all the different ways we move our bodies – from running and jumping to pickling up objects, or sitting down. It is still the muscles that make the movement happen by pulling on the bones, but the kind of movement each joint makes depends on the shape of the ends of the bones that meet.
Flexibility varies between individuals, particularly in terms of differences in muscle length of multi-joint muscles. Flexibility in some joints can be increased to a certain degree by exercise, with stretching a common exercise component to maintain or improve flexibility.
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