THE VOMER. 



95 



of the superior border presents three well-marked processes, which vary much in 

 their size and form. Of these, the anterior and smallest is situated at the junction 

 of the anterior fourth with the posterior three-fourths of the bone : it is small and 

 pointed, and is called the lachrymal process ; it articulates by its apex with the 

 anterior inferior angle of the lachrymal bone, and by its margins Avith the groove 

 on the back of the nasal process of the superior maxillary, and thus assists in 

 forming the canal for the nasal duct. At the junction of the two middle fourths of 

 the bone, but encroaching on its posterior fourth, a broad, thin plate, the ethmoidal 

 process, ascends to join the unciform process of the ethmoid ; from the lower border 

 of this process a thin lamina of bone curves downward and outward, hooking 

 over the lower edge of the orifice of the antrum, which it narrows below : it is 

 called the maxillary process, and fixes the bone firmly to the outer wall of the 

 nasal fossa. The inferior border is free, thick, and cellular in structure, more 

 especially in the middle of the bone. Bone extremities are more or less narrow 

 and pointed, the posterior being the more tapering. If the bone is held so that 

 its outer concave surface is directed backward (i. e., toward the holder), and its 

 superior border, from which the lachrymal and ethmoidal processes project, up- 

 ward, the lachrymal process will be directed to the side to which the bone belongs. 1 



Development. By a single centre, Avhich makes its appearance about the 

 middle of foetal life. 



Articulations. With four bones : one of the cranium, the ethmoid, and three 

 of the face, the superior maxillary, lachrymal, and palate. 



No muscles are attached to this bone. 



The Vomer. 



The Vomer (vomer, a ploughshare) is a single bone, situated vertically at the 

 back part of the nasal fossae, forming part of the septum of the nose (Fig. 63). 



Frontal sinuses. 

 . Crista galli. 



Sphenoidal sinuses. 



Perpendicular 

 plate of eth- 

 moid. 



Space for triangular 

 cartilage of septum. 



Vomer. 



Rostrum of sphenoid. 

 Palate process. 

 Int. pterygoid plate. 



FIG. 63. Vomer in situ. 



It is thin, somewhat like a ploughshare in form ; but it varies in different indi- 



1 If the lachrymal process is broken off, as is often the case, the side to which the bone belongs 

 may be known by recollecting that the maxillary process is nearer the back than the front of the bone. 



