This section is from the book "The Human Body: An Elementary Text-Book Of Anatomy, Physiology, And Hygiene", by H. Newell Martin. Also available from Amazon: The Human Body.
In this form of lever (Fig. 37), the weight or resistance acts between the fulcrum and the power. The power-arm PF is accordingly always longer than the weight-arm, WF, and so a comparatively weak force can overcome a considerable resistance. There is, however, a loss in rapidity and extent of movement, since it is obvious that when P is raised a certain distance W will be raised less. As an example of this kind of lever we may take the act of standing on the toes. Here the foot is the lever, and the fulcrum is where its fore part rests on the ground; the weight is that of the body, and acts downwards through the ankle joint at Ta, Fig, 19 ; the power is the great muscle of the calf of the leg pulling by its tendon, which is fixed to the end of the heel bone, Ca.
What is lost when power is gained?
Are there many levers of the first order in the body? Give an example of one, describing the action. Describe a lever of the second order.