492 



DIGESTIVE SYSTEM OF THE DOG 



has a small, central, bare area which forms part of the muzzle, and is marked by a 

 central groove, the philtrum, or (as in the bull-dog) a fissure, giving the appearance 

 of harelip. The lateral borders of the lower lip are flaccid and denticulated. The 

 mucous membrane is usually pigmented and forms distinct frena labiorum. The 

 labial glands are small and scanty. 



The cheeks are loose and capacious, and their mucous lining is smooth and 

 more or less pigmented. The parotid duct opens usually opposite the third upper 

 cheek tooth. Near the last tooth are the openings of the four or five ducts from 

 the zygomatic gland. This gland may be regarded as the homologue of the dorsal 



Fig. 433. — Palate of Dog. 



The lower jaw and related structures have been removed by sawing through the rami of the mandible and cutting 

 the soft structures horizontally. 



1, Raph6 of palate; 2, ridges of palate; 3, papilla incisiva; 4, soft palate; 5, tonsil; 6, meatus naso-pharyngeus; 7, 

 dorsal wall of pharynx; 8, parotid gland; 9, mandibular gland; 10, pharyngeal lymph gland; 11, m. oecipito- 

 mandibularis (cut); 12, m. masseter (cut); 13, cheek (cut); 14, ramus of mandible (section); 15, parotid lymph gland; 

 16, carotid artery; J, incisor teeth; C, canine tooth; P, premolar teeth; M, molar teeth. 



buccal glands of the other animals; it will be described later. The ventral buccal 

 glands are opposite the cheek teeth and in series with the inferior labial glands. 



The hard palate is widest between the fourth pair of cheek teeth. It has 

 eight to ten curved ridges on either side of the median raphe; the latter may be 

 indistinct or scarcely recognizable. Behind the first pair of incisor teeth is the 

 rounded or triangular papilla incisiva, at which the incisive or naso-palatine ducts 

 open. The mucous membrane is usually pigmented. 



The soft palate (Figs. 433, 488) is thick, except at its margins. In the resting 

 state of the parts it comes in contact with the epiglottis.^ Between its anterior and 



' It is usually stated that it is in contact with the oral surface of the epiglottis, but the epi- 

 glottis may be \'entral to the soft palate (Fig. 488). 



