THE HEAD. 51 



ties.^ The tliird is situated behind the maxillary turbinated bone, and 

 is confounded with the floor of the nasal fossa. 



The turbinated bones are essentially destined to furnish the membrane 

 of the nose with a vast surface of development. This membrane, indeed, 

 covers their entire superficies, and even penetrates the anfractuous cells of 

 their lower compartment. 



9. Vomer. 



This, a single bone, elongated from above to below, flattened on both 

 sides, and extending on the median line from the body of the sphenoid to 

 the premaxillary bone, offers for study two lateral faces, two borders, and 

 tioo extremities. 



The faces are smooth, plane, and covered by the nasal membrane. The 

 anterior border is channeled for the whole of its length by a deep groove 

 which receives the posterior border of the cartilaginous septum of the 

 nose. The posterior border is sharp and smooth in its upper half, which 

 separates the two guttural openings of the nasal cavities : it is thick and 

 slightly denticulated for the remainder of its extent, and rests on the 

 median suture resulting from the union of the two supermaxillary bones. 

 The superior extremity is provided, in its middle, with a notch which divides 

 it into two lateral prolongations shaped like a cat's ears ; it articulates 

 with the inferior sphenoid, ethmoid, palate, and pterygoid bones. The 

 inferior extremity rests on the prolongations of the incisive bones. 



This bone is entirely compact, and is developed from one centre of 

 ossification. 



10. Inferior Maxillary Bone. 



The maxillary bone is not consolidated with any of the preceding bones, 

 and is only united to two of them, the temporals, by diarthrodial articula- 

 tion. It is a considerable bone, situated behind the upper jaw, and composed 

 of two symmetrical branches, which are flattened on both sides, wider 

 above than below, curved ^rwards in their upper third, joined at their lower 

 extremities, and separated superiorly so as to leave a wide gap between 

 them, like the letter' V in shape, called the intramaxillary space. Each 

 offers for study two faces, two borders, and two extremities. 



Faces. The external face of the maxillary branches is smooth and 



rounded in its inferior two-thirds, and transformed superiorly into a 

 rugged surface, in which is implanted the fibres of the masseter muscle. 

 The internal face presents, in the corresponding point, an excavated surface 

 on which is remarked the superior orifice of the maxillo- dental canal, a long 

 channel which descends between the two plates of the branch, passing under 

 the roots of the molar teeth, and insensibly disappearing in the body of the 

 bone after being widely opened externally by the mental (or anterior maxillary) 

 foramen. In its inferior two-thirds, the internal face is smooth nearly 

 plane, and shows nothing very remarkable. Near the alveolar border there 

 IS a slightly-projecting line-the mijloid ridge; and quite below, or rather 

 at the very summit of the re-entering angle formed by the separation of 

 the branches, there is a slight rugged excavation confounded with that of the 

 opposite branch, and named the ^emaZ sMr/ace. 



Borders— The anterior, also named the alveolar border, exhibits tor 

 study a straight or inferior, and a curved or superior portion. The first is 

 hoUowed by six alveoli to receive the inferior molar teeth. 



> The two turbinated bones, in being applied against tiie excavation on the inner 

 face of the supermaxillary, almost entirely close it, only leaving between them a vertical 

 pjit which constitutes the opening mentioned above. 



