THE INFERIOR MAXILLARY BONE 63 



passing up and back to the ramus, is the internal oblique line 

 or mylohyoid ridge, for the mylohyoid muscle and a slip of the 

 superior constrictor of the pharynx. Above this line is a fossa 

 for the sublingual gland, and below it another for the sub- 

 maxillary. 



The ramus is thinner than the body, and where its posterior 

 border meets the base it forms the slightly everted angle. 

 The external surface is flat, and near the angle it shows oblique 

 lines for tendinous attachment of the masseter muscle. At 

 the centre of the internal surface, on a level with the crowns 

 of the molar teeth, is the inferior dental foramen, leading to the 

 dental canal; the inner margin of the foramen is sharp anteriorly, 

 and called the lingula mandibulce. Beginning at the notch 

 behind the lingula is the mylohyoid groove (sometimes a canal), 

 terminating below the hinder end of the mylohyoid ridge. 

 Behind and below this is a rough surface for the internal ptery- 

 goid muscle. On the upper border of the ramus are two processes 

 the condyle for articulation and the coronoid, for muscular 

 attachment; they are separated by the semilunar or sigmoid 

 notch. The condyle passes up from the posterior part of the 

 ramus, supported on a constricted neck, on the front of which 

 internally is a depression for the external pterygoid muscle 

 (\ inch; 8 mm.); below the articular surface there may be 

 an external tubercle for the external lateral ligament. The 

 condyle is convex, transversely elongated, and the axes of 

 the two would meet at the anterior margin of the foramen 

 magnum. The coronoid process passes up from the forepart 

 of the ramus, inclined out and somewhat beak-shaped; by its 

 apex, sharp margins, upper and anterior part of the external 

 surface, and inner surface, it gives attachment to the tem- 

 poral muscle. 



The anterior border of the ramus shows three oblique ridges 

 an external one to the end of the external oblique line; internal 

 to that is a groove bounded posteriorly by a ridge passing 

 from the internal oblique line to the middle aspect of the coro- 

 noid ; at the lower part of the groove, extending a short distance 

 to the outer side of the alveolus, is the third or buccal line. 



The lower jaw consists of a thick shell of compact tissue 

 enclosing cancellous tissue; the dental canal in its posterior 

 two-thirds lies close to the inner compact layer; it is prolonged 

 beyond the mental foramen under the canine and incisor 



