146 



THE HUMAN BODY. 



ment of such levers (Fig. 57) in the Body, we may take the 

 act of standing on the toes. Here the foot represents the 

 lever, the fulcrum is at the contact of its fore part with 



F 



FIG. 57. A lever of the second order. F, fulcrum; P, power; TF, weight. 

 The arrows indicate the direction in which the forces act. 



the ground ; the weight is that of the Body acting down 

 through the ankle-joints at Ta, Fig. 58; and the power is 

 the great muscle of the calf acting by its tendon inserted 

 into the heel-bone (Ca, Fig. 58). Another example is 

 afforded by holding up the thigh when one foot is kept 

 raised from the ground, as in hopping on the other. Here 

 the fulcrum is at the hip- joint, the power is applied at the 



VTO. 58. The skeleton of the foot from the outer side. Ta, surface with 

 which the leer-bones articulate ; Ca, the calcaneum into which the tendon (tendo 

 Achillis) of the calf muscle is inserted : Mb, the metatarsal bone of the fifth 

 digit; N, the scaphoid bone; CI, CII, CT/7, first, second, and third cuneiform 

 bones; Cb, the cuboid bone. 



knee-cap by a 'great muscle (rectus femoris) inserted theie 

 and which arises from the pelvis; and the weight is that 

 of the whole lower limb acting at its centre of gravity, 

 which will lie somewhere in the thigh between the hip and 



