382 



MAMMALIAN ANATOMY 



The lower surface of the vomer (Fig. 301) has the same general 

 form as the upper surface ; it presents, however, a median longitudinal 

 ridge instead of a median longitudinal furrow. The anterior third, or 

 more, of this ridge is roughened, and articulates with the anterior 

 median part of the upper surface of the joined horizontal plates of 

 the palatines and with the median borders of the horizontal plates of 

 the maxillaries. The anterior end is incised to receive the posterior 

 ends of the palatine plates of the two premaxillaries. The rest of the 

 lower surface is smooth and non-articular ; it is covered with mucous 



Upper Anterior part of 

 Ethmo-turbinal. ' 



Maxitto-turbinal. 



Cut edge of Cribriform plate 

 of Ethmoid. 



Lower Posterior part 

 of Ethmo-turbinal 

 in Sinus. 



Vertical Longitudi- 

 nal Partition 



.. 



'"-'dal Sinus. 



Premaxillary . 



Horizontal plates 

 of Maxillary 

 and Palatine. 



Vomer. 



RIGHT NASAL CHAMBER, SIDE VIEW FROM WITHIN. 



membrane, and forms the roof of the canal which leads from the nose to 

 the posterior nares. The vomer can scarcely be said to have lateral sur- 

 faces ; they are mere borders which widen in front, as the sides of the 

 prominent inferior ridge. Each edge of the expanded posterior portion 

 joins (1) the lower edge of the lateral ethmoid, (2) a ridge just over the 

 spheno-palatine foramen on the nasal surface of the ethmoidal process of 

 the palatine, and (3) the sphenoidal process of the palatine (Fig. 300). 

 The vomer slopes slightly downward at the anterior end, and this slope 

 is apparently increased the greater the height of the bone. 



