246 SKELETON. 



than their flexion, from whence results an important advantage 

 in walking or in standing upon the toes. The shortness of the 

 second and third phalanges of the small toes, together with the 

 thickness of the sole of the foot contiguous to them in their ex- 

 treme flexion, causes them rather to be doubled up on them- 

 selves, than on the sole of the foot. 



On the General Motions of the Lower Extremities. 



These may be resolved into three; walking, running, and 

 leaping. 



In walking, though the first step may be taken in a variety 

 of relative positions of the lower extremities to each other, yet 

 it will make the investigation more clear to suppose the indivi- 

 dual standing erect, with the two feet precisely on the same 

 plane, and giving equal support to the trunk. The first step is 

 then taken, by detaching the foot of one side from the ground ; 

 in order to do which, the thigh is bent upon the trunk, the leg 

 upon the thigh, and the limb by being thus elevated becomes 

 shorter. At this period the ankle joint remains at rest, with a 

 slight inclination of the toes downwards. By the subsequent 

 relaxation of the muscles of the limb advanced, with an incli- 

 nation of the trunk to the same side, the limb is caused to de- 

 scend upon the ground. These are the only motions when the 

 step is short and easy; but, when a long stride is taken, by which 

 the limb is put very much in advance of its fellow, in order to 

 bring it to the ground, the pelvis is caused to rotate forwards 

 on the head of the stationary thigh bone, whereby the trunk of 

 the body, instead of presenting the sternum forwards, has it 

 turned to one side. 



When a step has been taken so as to leave one inferior extre- 

 mity advanced before the other, for example the left, the limb 

 behind is brought forward by .the following mechanism: The 

 left foot, remaining fixed, becomes the point of support to the 

 trunk; and the right, which is behind, is elevated successively, 

 from the heel to the toes, by the action of the muscles on the back 

 of the leg, and rests, upon the phalanges. The effect of this po- 

 sition is to elongate the right inferior extremity to the amount 

 of the distance between the fore part of the ankle joint and the 



