170 Mujcles of the Foot. [Book IX. 



ftrong cord called tendo achillis, which is inferted into 

 the pofterior and projecting part of the os calcis. The 

 diftance of the extremity of the os calcis from the 

 aftragalus, which is the center, on which the motions 

 of the foot are performed, gives thefe mufcles great 

 power. Their effect is to extend the foot by bring- 

 ing it more nearly into the direction of the tibia. 

 When the foot, however, becomes the more fixed 

 point, as in the erect pofture of the body, thefe two 

 mufcles, by preffing the foot againft the ground, raife 

 the body ; they are therefore very much employed in 

 walking, running, and jumping, but particularly in 

 afcending fteps, whence the fatigue felt in thefe 

 mufcles which form the calves of the legs by a con- 

 tinuance of that exercife. 



The plantaris arifes from the upper and back part 

 of the external condyl of the os femoris, adhering 

 in its defcent to the capfular ligament of the knee. 

 Pafling under the gemellus, it fbon terminates in a thin 

 tendon, which is the longeft in the body, and wh^ch 

 is inferted into the infide of the back part of the os 

 calcis. It co-operates with the former mufcle in ex- 

 tending the foot, and alfo pulls the capfular ligament 

 of the knee from between the, bones, and prevents it 

 from being pinched. / 



The flexors of the foot are four, two of which be- 

 long to the tibia and two to the fibula. 



The tibialis anticus proceeds from the upper and 

 fore part of the tibia, and from the interoffeus liga- 

 ment. Near the extremity of the tibia it fends ofPa 

 round tendon, which paffes under the ligamentum 

 tarfi annulare near the inner ankle. It is inferted into 

 the infide of the os cuneiforme internum and the pofte- 

 rior end of the metacarpal bone, which fuftains the 

 great toe. The effect of this mufcle is to bend the 



foot* 



