228 THE ARTISTIC ANATO:\IY OF ANIMALS 



We may add, with regard to the tendo-AchiUis, that it 

 is more clearly perceived as an external feature, because the 

 skin sinks in front of it, as it does in man, over the lateral 

 parts of the region which it occupies. 



The gastrocnemius, when it contracts, extends the foot 

 on the leg. 



It serves to maintain the tibio-tarsal angle in the standing 

 position, and during walking, to determine the steadying 

 of the hind-limbs, which then, after the fashion of a spring, 

 project the body forward. 



By an analogous movement they take part in the pos- 

 terior projection of the hind-limbs in the act of kicking; 

 but they are not the only ones to act in this case, the 

 muscles of the buttock and thigh also being brought into 

 play. 



Soleus (Fig. 83, 10 ; Fig. 86, 8). — This muscle, much less 

 developed in quadrupeds than in man, does not exist in the 

 dog. 



With regard to the soleus in the pig. Professor Lesbre says : 

 ' jNIeckel denied its existence ; we, however, believe that it 

 is united to the external head of the gastrocnemius, its 

 origin being transferred to the femur.'* 



But in animals in which it exists, this muscle, of but little 

 importance, occupies the outer side of the leg. It arises 

 above from the external tuberosity of the tibia, and ter- 

 minates below in a tendon which is united with that of the 

 gastrocnemius. 



The soleus has the same action as these latter. 



Plantaris. — In quadrupeds this muscle is blended with 

 the superficial flexor of the toes, which we will study 

 afterwards. 



Popliteus (Fig. 87, 16 ; Fig. 88, 14). — In man, this 

 muscle, which occupies the posterior surface of the tibia, 

 above the oblique line, is completeh^ covered by the gastroc- 

 nemius. 



In quadrupeds, where it is more voluminous, it projects 



* F. X. Lesbre, ' Essai de Myologie comparee de I'homme et des mam- 

 miferes domestiques en vue d'etablir une nomenclature unique et ration- 

 elle,' Lyon, 1S97, p. 169. 



