258 ANIMAL MECHANICS. 



fibres influence, in addition, the ankle joint. We shall, how- 

 ever, regard it as a whole, represented by its resultant force 

 acting in the direction OX. The other hamstring muscles, 



Fig. 68. 



semi-tendinosus and semimembranosus, take origin from the 

 tuber ischii, immediately beside the biceps, and are inserted 

 into the tibia, in a position corresponding with the position 



