Muscles and bones act together to achieve a variety of movement by forming different types of levers
A lever consists of four main parts: lever arm, fulcrum, force and load
- Bones function as the lever arm (structural framework of lever)
- Joints function as the fulcrum (point on which the lever turns)
- Muscles provide the force or effort required to move the lever
- The load is typically the weight of the body part being moved
Levers can be categorised into different classes according to the relative positions of the lever components
- In first class levers, the fulcrum is between the load and the force (e.g. nodding the head)
- In second class levers, the load is inbetween the fulcrum and the force (e.g. standing on tip toes)
- In third class levers, the force is inbetween the fulcrum and the load (e.g. bending your arm)
Types of Levers in the Human Body