208 BONES OF THE FACE. 



greater length extends from before backwards. They are 

 two in number and have an irregular form. Each presents 

 FIG. 49. two surfaces, an internal or convex, 



and external or concave. The superior 

 edge is united to the maxillary and 

 palate bones by their transverse ridges, 

 and from it ascends a small pyramidal process connecting 

 with the unguis to complete the nasal duct. The inferior 

 edge is free and rolled outwards. The anterior point forms 

 the inner wall of the lower orifice of the nasal duct. The 

 structure is thin, brittle, and filled with small pores. The 

 development is by a single point from the centre, commen- 

 cing about the fifth month of foetal life. The articulations 

 are with four bones, the superior maxillary, the lachrymal, 

 the ethmoid and palate. 



Vomer (the plough-share.) The vomer, a single bone, so 

 called from its supposed resemblance to the plough-share, 

 or, more properly, the coulter of the 

 FIG. 50. plough, is situated on the median line 



so as to divide the nares. It has two 

 ^ surfaces, which are lateral, and covered 

 by the pituitary membrane, and four 

 edges, a superior, an inferior, an anterior, and a posterior. 

 The superior is thick and hollow, and receives the azygos 

 process of the sphenoid bone. The inferior is long and united 

 to the palatine crest of the superior maxillary and palate 

 bones. The anterior edge is grooved to receive the middle 

 septum of the ethmoid bone and nasal cartilage ; while the 

 posterior is sharp and divides the nares behind. Its struc- 

 ture is compact, thin, and transparent. Its development is 

 from a single point, commencing about the end of the 

 second month, at its lower portion. Its articulation is with 



FIG." 49 represents the maxillary or outer aspect of the right Turbinated 

 Bone. 1 2 Posterior and anterior angles of the turbinated bone. 3 Lachry- 

 mal process. 4 Maxillary process. 5 Lower margin. 7 Curved portion of 

 the maxillary process. 



FIG. 50 represents the yomer in profile. 1 2 Superior edge, 3 Anterior 

 edge, 4 Inferior edge of Tomer. 6 Lateral surface. 



