BONES OF THE FACE. 211 



ing, says Mr. Nasmyth, downwards and backwards ; a fact 

 which he regards of great practical moment in the man- 

 agement of the teeth, as a space is thus gained of three or 

 four lines hetween the roots of the two bicuspids. This 

 alveolus is larger than that of the anterior, hut less than 

 that of the canine. 



The alveolus of the first molar has a partition dividing it 

 into an anterior and posterior cavity the anterior being 

 rather the larger, and the axes of both looking backwards. 

 The septum is described as thickest in the centre, abound- 

 ing with openings for the passage of vessels, and has its 

 direction inwards and backwards from the outer side. Its 

 opening is of a quadrilateral form, having its front margin 

 indented. 



The alveolus of the second molar has also a septum 

 (occasionally absent) dividing it into an anterior and pos- 

 terior cavity, the anterior being the larger, and found to be 

 somewhat contracted in its middle and "compressed from 

 before backwards;" the posterior is oval and not so deep. 

 Its opening is also quadrilateral. 



The alveolus of the third molar is always smaller and shal- 

 lower than either of the others, and is found to present 

 great variety both in form and size. It is seen sometimes 

 divided into two cavities, and then again having but one. 

 The alveoli of the molar teeth all look outwards, so that the 

 crowns of these teeth have a direction inwards.* At the 

 posterior extremity of the lateral portions is the angle, which 

 is nearly a right angle in the adult, but quite obtuse in the 

 foetus, and to which, on its internal edge, is attached the 

 stylo maxillary ligament. From the posterior ends of the 

 lower jaw there rises, almost perpendicularly, a process 

 called the ramus. This process is square-shaped and very 

 strong. It has different angles at different periods of life. 

 In the infant it is nearly on a line with the lateral portions. 

 In youth it is oblique. In the adult it becomes nearly ver- 

 tical, while in old age it again returns to the infant state 

 Its external surface is covered by the masseter muscle 



* Alexander Nasmyth's late Researches on the Teeth. 



