364 THE DIGESTIVE APPARATUS IN MAMMALIA. 



1. Lips. The lips have a thick, free, everted border. They are lined by a rosy 

 mucous membrane, which is insensibly continued inwards by the buccal membrane. 

 The upper lip is limited by the nose and the naso-labial furrow ; the lower is limited by 

 the mento-lubial groove. The first has in its middle the subnasal furrow. Their 

 structure is analogous to those of animals. 



2. Cheeks. The cheeks are limited by the inferior border of the maxilla, the root of 

 the ear, the prominence of the chin, and the naso-labial furrow. Between the skin and 

 the mucous membrane, there is found, as in brutes, a glandular layer and muscles, 

 chiefly the buccinator. An adipose ball is always found near the anterior border of the 

 masseter. 



3. Palate. It does not possess a vascular membrane, as in the Horse, and its mucous 

 membrane shows a longitudinal and transverse furrows in its anterior two-thirds. It 

 is pale and resisting. 



4. Tongue. This is thick, short, and broad ; its base is almost vertical, and in the 

 middle is a perpendicular, fibrous, and semilunar lamina, the lingual septum which gives 

 insertion to muscular fibres. 



Anthropotomists distinguish intrinsic and extrinsic muscles. The first are : the 

 lingualis superior and inferior, transversus, and longittidinalis. The second are, as in 

 Solipeds, the stylo-glossus, genio-glossus, hyo-glossus, and pharyngo-glossus. There is 

 also described a palato-glossus, which partly belongs to the soft palate. 



The mucous membrane shows the different characters recognised in that of animals. 

 That of the dorsal face is divided into two portions by two A-shaped rows of papillae, 

 whose summit abuts on the deep mucous follicle named the foramen cxcum. The 

 posterior portion presents depressions which correspond to the closed follicles, and the 

 fungitbrm and calyciform papillae ; the anterior portion has a viljous aspect, due to the 

 great number of filiform papillae covering it. 



5. Soft Palate. In Man, the soft pala,te is short and divided into two portions : an 

 anterior, horizontal, attached to the base of the tongue by the anterior pillars of the 

 curtain; a posterior, movable and oblique, having a free portion, the uvula, and fixed to 

 the lateral walls of the pharynx by the posterior pillars. The amygdala', or mass of 

 closed follicles, are lodged in the triangular space between the anterior and posterior 

 pillars. The fibrous structure is not present, unless the small expansion of the 

 external tensor of the palate represents it. The muscles are the same as in animals, 

 and, in addition, there are described two palato-glossal muscles, included between the 

 mucous folds that form the anterior pillars. The palato-pharyngeus extends to the 

 posterior nasal spine. The isthmus of the fauces is wider than in the Carnivora. 



6. Teeth. The teeth are thirty-two in number, sixteen in each jaw. They are 

 distributed in the following manner : four incisors, two canines, two small molars 

 (bicuspidati), and three large molars (mutti-cuspiaaU). 



The incisors, when viewed in profile or longitudinal section, have a wedge-shape, and 

 their free border is more or less sharp. The canines are irregularly conical ; the molars 

 have a multiple fang, and the crown is studded with a variable number of tubercles : two 

 on each small molar and four on the large. In youth, there are only twenty teeth, ten 

 in each jaw. 



THE SALIVARY GLANDS. 



The salivary glands are secretory organs annexed to the buccal cavity, 

 into which they pour saliva : a recrementitious fluid that softens the food, 

 favours its mastication and deglutition, and has a chemical action upon it 

 after its arrival in the abdominal portion of the digestive canal. 



Though very diversified in form, yet they present in their structure such 

 common characters, that, to obviate a recurrence to their organisation when 

 speaking of each gland, we will describe it here. 



The salivary glands are constituted by a red or yellow spongy tissue, 

 which is divided into small, rounded, or polyhedral masses, called salivary 

 lobules. These extend in a layer beneath the adherent face of the mucous 

 membrane, and remain isolated from each other, or are agglomerated in a 

 body to form a single gland. In the latter case they are united by condensed 

 connective tissue, which is disposed over the surface of the organ as a very 

 thin enveloping membrane, and into the lobular interstices in lamellar 

 prolongations. 



