1 8 THE ANATOMY OF THE ADULT HUMAN SALIVARY GLANDS 



In other cases, the lesser sublingual group of glands stops cephalad 

 of the Hngual nerve, and the series is resumed caudad of this point as 

 a scattered collection of separate glands which ascend in the mucosa 

 covering the areas palatinus. These constitute the isthmian or 

 faucial glands. 



They may be confined to the Hmits of the anterior faucial pillar, 

 or they may extend without interruption caudodorsad to become 

 continuous with the field of separate glands located in the mucosa 

 of the velum palati and forming the group of the palatine glands. 



Owing to the close relation of the lingual nerve of the primates to 

 the alveolingual oral mucosa (cf. Part III, page 78, Figs. A, b), the 

 line of the nerve may, in this mammalian order, represent the divi- 

 sion between a lesser subhngual group of glands sensu stricto, and a 

 caudal group of the same derivation which ascends, as the isthmian 

 glands, into the faucial pillar. In the same way the palatoglossal 

 muscle may interrupt the continuity of the isthmian group of separate 

 glands with the glands of the soft palate. But morphologically all 

 three sections of greater sublingual, isthmian, and palatine glands rep- 

 resent a single glandiferous lateral line which, in proceeding cephalo- 

 caudad along the lateral liinit of the narrowing oral floor, escapes 

 from the confines of this area by turning first caudodorsad, and then 

 mesad, into the anterior faucial arch and then into the palatine area. 

 The close apposition of the lingual nerve to the oral mucosa may or 

 may not interrupt the continuity of the lesser sublingual and isthmian 

 elements. In the same sense there may or may not be a break in the 

 glandular line as the same turns from the palatine arch into the soft 

 palate. 



Genetically all the elements of the lesser sublingual, isthmian, and 

 palatine groups must be regarded as derivatives from an originally 

 continuous lateral border line which has conformed to the secondary 

 conditions imposed by the mechanical adaptations of the mammalian 

 vestibule and oral ca\'ity. The widely different conditions which 

 obtain in mammalia in general, other than the primates, in reference 

 to the topographical position of the hngual nerve in relation to the 

 lateral alveohngual glandular field, are discussed in detail in other 

 portions of this volume (cf. Part III, page 78, Part VIII, page 328). 



One point deserves especial notice, namely, the tendency exhibited 



