MUSCULAR SYSTEM OF MAMMALIA. 



10 



the femur, has its fixed point in the fibula, from the head to half- 

 way down the bone, fleshy ; its tendon passes obliquely inward, 

 and glides behind the inner malleolus to its insertion in the plantar 

 fascia, so that it rotates the tibia inward besides extending the 

 foot. The soleus has an extensive origin from the proximal to 

 near the distal end of the fibula. There are, as usual, three deep- 

 seated muscles at the back of the leg. Of these three the 

 muscle homologous with the tibialis posticus is readily recognised ; 

 its tendon glides behind the inner malleolus, and is inserted into 

 the inner or tibial cuneiform bone. 



The muscle which has the relative position and origins of the 

 flexor longus poMcis, sends its tendon by the usual route to the 

 sole of the foot, where it di- g 



vides and distributes a flexor 

 tendon to all the toes except 

 the rudimental hallux ; it has 

 the same disposition in the 

 Opossums, where the hinder 

 thumb or great toe is fully 

 developed : for this modifica- 

 tion, however, the Compara- 

 tive Anatomist is already pre- 

 pared by meeting with such 

 common office of the muscle 

 in the first step from Man, 

 viz. in the Orang, Gorilla, and 

 Chimpanzee. 



The third deep-seated mus- 

 cle, being situated internal to 

 the two preceding ones, may 

 be the homologue of the flexor 

 digitorum communis longus ; 

 it nevertheless sends no ten- 

 don to the toes nor even to 

 the tarsus, but its fibres 

 pass from the tibia obliquely 

 outward and downward be- 

 tween the preceding muscle 

 and the interosseous ligament 

 to the fibula, where they are 

 exclusively inserted so as to 

 oppose the plantaris and rotate the foot outward. This muscle 

 closely adheres to the interosseous fascia, and thus resembles in its 



Muscles of leg, Phalangista vulpina. 



