Types of Levers

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