What does the term 'extension' indicate in relation to joints?

The term 'extension' in relation to joints specifically refers to the straightening motion that occurs at a joint. When extension takes place, the angle between the connecting bones increases, which allows the body part to move from a bent position back to a straightened position.

For example, when you straighten your arm after bending it at the elbow, this action is considered extension. Similarly, when you extend your leg by straightening it outward, you are also performing an extension at the knee joint. Understanding this definition is crucial for those studying human movement and anatomy, as it lays the foundation for further learning about joint mechanics and the various movements associated with them.