240 THE ARTISTIC ANATOMY OF ANIMALS 



of this lip and of the aUe of the nose. It raises the 

 upper Hp. 



In the ox, it arises from the maxillary spine, and then 

 divides into three parts ; the superior passes under the 

 internal portion of the internal elevator of the upper lip and 

 the alae of the nose, and goes into the nostril ; whilst the two 

 others, situated lower down, terminate in the upper lip. 



In the pig, it is formed of two superimposed fasciculi, 

 which arise from the spine of the maxilla and the impressions 

 in front of it. These two fasciculi terminate in the snout, 

 which they move laterally. 



In the horse, it is situated at a certain distance from the 

 external elevator ; in the preceding animals it is in contact 

 with the latter. Arising behind from the external surface 

 of the maxilla, in front of the maxillary spine, it is directed 

 towards the anterior part of the face, passes under the 

 external portion of the internal elevator (it is the oppo- 

 site of this in the ox), and proceeds, on expanding, to ter- 

 minate in the skin of the nostril. Bv its contraction it 

 dilates the latter. 



Orbicularis Oris (Fig. 91, 8 ; Fig. 92). — This muscle, very 

 fleshy in the solipeds and the ruminants, is arranged as a 

 ring round the buccal orifice, in the thickness of the lips, 

 where it is blended with the other muscles of this region. 



Having for its function the narrowing of the orifice it 

 surrounds, it acts during suction and in the prehension of 

 food. 



Triangularis Oris. — This muscle does not exist in 

 domestic quadrupeds. 



Quadratus Menti. — In the pig and the carnivora, it 

 arises from the anterior part of the body of the inferior 

 maxillary bone, and passes at the other end to terminate 

 in the corresponding portion of the lower lip, which it 

 depresses by its contraction. 



In the ox and the horse this muscle does not exist ; it 

 is replaced for the depression of the lower lip, which it 

 affects in other animals, by supplemental fibres of the 

 buccinator. 



The Prominence of the Chin. — Below the lower lip in 



