THE MUSCLES 17 



score of muscle-engines being set in motion in the foot 

 and leg, some of them big, others very small. Is it not 

 wonderful, with so little trouble on our part, each and all 

 of these engines are set to work just at the right instant 

 of time, and act just at the right rate and with the right 

 strength ? 



We are watching how the heel is raised and the limb is 

 swung forward as a step is taken. We notice that as the 

 heel is raised a bending takes place at the knee and at the 

 hip-joint (Plate II.), and then the limb begins to swing 

 forward until the foot is again planted on the ground, 

 the heel coming in contact with it before the toes. During 

 that swing every one of the fifty-four muscular engines, 

 which are placed within the moving limb, come into action, 

 some for a short spell and others for a longer, but in 

 point of action all are timed exactly. How wonderful 

 the machinery must be which controls all of these engines 

 we can best realise by remembering that, in walking at the 

 rate of four miles an hour, only half a second elapses from 

 the time the heel is raised until the limb has swung 

 forward and the foot is again planted on the ground. 

 Yet in that half second fifty-four engines have been started 

 and stopped, speeded up and slowed down a countless 

 number of times. 



It is not necessary for us to go fully into the muscles 

 or engines concerned in swinging the limb forward ; the 

 muscles of the buttock which act on the hip-joint and 

 those of the thigh — the hamstrings and extensors of the 

 knee can be seen in the moving figure drawn in Plate II. 

 But I should like to speak of one group of muscles which 

 is called into action at the end of the forward swing just 

 as the heel has reached the ground and the front part of 

 the foot has been firmly planted there. It is then that 

 the muscles which lie in front of the leg (Plate II.) and 

 whose tendons may be felt passing in front of the ankle 

 to be attached on the back of the foot and to the toes, 

 come into action. They prevent the front part of the 

 foot from going down with a jerk. They act as " pull " 

 engines, but " pull " engines of a curious kind. When a 



2 



