2o6 THE ARTISTIC ANATOMY OF ANIMALS 



In the dog and the cat it also arises from the sacro-sciatic 

 ligament. At this level its contour is distinguishable from 

 that which corresponds to the gluteal muscles, so that we 

 there iind two prominences one above the other. The 

 superior is formed by the gluteal muscles ; the inferior cor- 

 responds to the tuberosity of the ischium. The two pro- 

 minences are separated by a depression, from which the 

 biceps emerges. We draw attention to this form, the 

 character of which is so expressive of energy in the car- 

 nivora. 



In these animals the biceps is inserted, by its anterior 

 fibres, into the articulation of the knee, while in the rest of 

 its extent it covers in great measure by its aponeurosis the 

 external aspect of the leg. 



, In the pig, the biceps is but slightly marked off from 

 the posterior part of the great gluteal. In the ox, the 

 division between these two muscles is a little more distinct. 



In the horse, the sciatic origin of the biceps is covered by 

 the semi-tendinosus, so that it only becomes free lower 

 down, to appear in the space limited behind by the semi- 

 tendinosus, and in front by the posterior part of the gluteus 

 maximus. 



When the biceps contracts, taking its fixed point from 

 above, it flexes the leg and helps to extend the thigh. If, 

 on the other hand, it takes its fixed point from below, it 

 lowers the ischium, makes the pelvis undergo a see-saw 

 movement, and acts thus in the movement of rearing. It 

 is sometimes called, on account of one of its actions, 

 and the position which it occupies, the ' external flexor, or 

 peroneal muscle of the leg.' 



Semi-tendinosus (Fig. 68, 31 ; Fig. 70, -^"j ; Fig. %"], i ; 

 Fig. 88, I ; Fig. 89, 28). — This muscle forms the contour of 

 the thigh posteriorly, so that when the latter is viewed from 

 the side, it is the semi-tendinosus above all that forms the 

 outline. But, as we shall soon see, it is in this case more 

 distinct above than below, because of the deviation which it 

 undergoes in order to occupy by its inferior part the 

 internal side of the leg. 



In the dog, the cat, and the ox, the semi-tendinosus 



