2o6 



HUMAN ANATOMY. 



cesses of the sphenoid. The posterior border is free. Thick above, just under the 

 alee, it soon narrows and runs downward and forward. The inferior border fits 



Fig. 231. 



SUPERIOR BORDER 



Ala 



Naso-palatiiie groove 



Vomer in place, from left side. 



Fig. 232. 



Ala 



Groove for 

 rostrum of 

 sphenoid 



Vomer, superior surface. 



Groove for 

 rostrum of 

 sphenoid 



Ant. border 

 for ethmoid 



between the nasal crests of the palatals and maxillae, and anteriorly changes its direc 

 tion so as to rise over the higher incisor crests as far as the anterior palatine canal, 



The anterior border is the longest. Its 

 upper part articulates with the back of 

 the vertical plate of the ethmoid, the 

 lower part with the triangular cartilage of 

 the nasal septum. The latter is received, 

 into a groove which may extend behind 

 the vertical plate. The sides of the vomer 

 are covered with mucous membrane. 

 They present a few irregularities, the 

 most important of which is a groove on 

 either side, nearer the front than the 

 back, for the naso-palatine nerve ; and, 

 just anterior to this, a thickening which is normally insignificant, 

 but occasionally is developed to one side or the other, forming a 

 spur which may nearly close the passage. 



Articulations. — The vomer articulates with the sphenoid, 

 ethmoid, palate, and superior maxillary bones and the median 

 triangular cartilage. 



Development.— It is to be remembered that, although the 

 vomer becomes through ossification one of the separate bones of 

 the face, at an early period it is but a portion of the septal car- 

 tilage without any hint of demarcation. A single centre appears 

 before the close of the second foetal month in the membrane at the under border 

 of the cartilage, which then forms the septum. This grows upward on either side 

 of the cartilage until the bone is complete. The young bone shows very clearly 

 its formation in two plates ; but in the adult this appears only in the groove between 

 the wings and in the lower part of the front border, which still receives the triangular 

 cartilage. 



Grooved 

 ant. border 

 for sejDtal 

 cartilage 



Vomer from before 

 and above. 



