THE HEAD. 75 



orbital cavity. By its it\ferior bonier, it rests on thu entire length of the median suture of the 

 palatine ami supermaxilLiry bones. 



C. Pig. — The vomer in this animal adheres to tlie bones of the palatine arch for a great 

 extent. The free porticm of the inferior border is short and but little prominent. 



D. Carnivora. — In the Dog and Cat, the vomer is short, but its wings are very large. 



10. Inferior Maxillary Bone (Fig. 44). 



The inferior maxillar// bone is not consolidated with any of the preceding bones, 

 and is only united to two of them — the temporals — by diarthrodial articulation. 

 It is a consideralile bone, situated behind the upper jaw, and composed of two 

 symmetrical branches, which are flattened on both sides, wider above than below, 

 curved forwards in their upper third, joined at their lower extremities, and 

 separated superiorly so as to leave a wide gap between them, like the letter Y in 

 shape, called the intra-maxiUary space. Each offers for study tiro 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 maxillar//) 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 myloid ridije ; 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 genial surface. 



Borders. — The anterior, also named the alveolar border, exhibits for study a 

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

 six alveoh to receive the inferior molar teeth. 



The second, thinner, concave, and rugged, serves for muscular insertion. 

 The posterior border is also divided into straight and curved portions. The latter 

 is convex, thick, rugged, and margined on each side by an uneven hp ; the first 

 is regularly rectilinear, so that all its points rest at the same time on a horizontal 

 plane ; it is thick and rounded in the young animal, but becomes sharp with 

 age ; an oblique and transverse fissure — the maxiUary — separates it from the 

 curved part. The union of these two portions forms the anylc of the jaw. 



Extremities. — The superior extremity has two eminences : a condyle, and a 

 long non-articular process named the coronoid process. The condyle is elongated 

 transversely, and convex in its two diameters ; it responds, through the medium 

 of a fibro-cartilaginous disc, to the articular surface of the zygomatic process. 

 The coronoid process is situated in front of the condyle, from which it is sepa- 

 rated liy a division called the sigmoid or corono-condgloid notch ; it is flattened on 

 both sides, and curved backwards and slightly inwards. 



From the union of the branches of the maxillary bone at their inferior 

 extremity, results a single piece, flattened before and l)ehind, and widened like a 

 spatula, which has been designated the body of the bone. This merits a special 

 description. 



Its form allows us to divide it into an anterior or buccal face, a posterior or 



