232 



PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



the food and draw it within the mouth. The extrinsic muscles are 

 connected with the hyoid bone and chin, and render possible the pro- 

 trusion and retraction of the tongue ; the intrinsic muscles permit of 



FIG. 81. AFTER GAMGEE AND CHAITVEATT. 



1 and 2, attricnlar muscles ; 3, scutiform cartilage: 4, external scuto-auricular muscle; A A, 

 ular branches of first pair of cervical nerves ; B B. anterior auricular nerves ; C, terminal fibres of the 

 supraorbital nerve; D, superficial branch of the lachrymal nerve; Y, tendon of muscle to elevate upper 

 lip ; Z, naso-transversalis muscle. 



the change of shape of the tongue required in mastication and deglu- 

 tition. The tongue is, further, covered with a mucous membrane, on 

 the dorsal surface of which are numerous more or less horny papillae, 



