THE MAXILLARY BONES. 31 



in position and in size in different individuals. The upper 

 pair of tubercles give attachment to the genio-hyo-glossus, 

 the lower to the genio-hyoid muscles ; they are interesting to 

 the dental student not only as giving attachment to muscles 

 concerned in deglutition, but as affording convenient fixed 

 points for measurements of the relative growth of parts of 

 the jaw. Beneath these genioid tubercles lie the slight 

 depressions which give attachment to the anterior belly of 

 the digrastric muscle, while between the two points alluded 

 to commences the internal oblique line, which runs ob- 

 liquely upwards and backwards, becoming more pronounced 

 as it extends backwards, and terminating at the inferior 

 dental foramen. This internal oblique ridge marks the line 

 of growth of the condyle (see Development of the Jaws), and 

 gives attachment to the mylohyoid muscle, which forms the 

 floor of the mouth, in all its length. Thus the bone above 

 the ridge belongs strictly to the mouth, that below it has 

 more relation with cervical structures. The depression for 

 the sublingual gland is above this line, consequently this 

 gland is visible from the mouth ; that for the submaxillary 

 gland is beneath it and further back. 



The inner surface of the ascending ramus gives attach- 

 ment to the following muscles : at the neck of the condyle 

 to the external pterygoid ; on the inner face of the coro- 

 noid process, as far down as the level of the top of the 

 crown of the wisdom tooth, to the temporal ; on the inner 

 side of the angle, over a large surface, to the internal 

 pterygoid. 



The orifice of the inferior dental canal is rough and 

 spinous, giving attachment to the internal lateral ligament 

 of the jaw, while beneath and behind it is the groove for 

 the mylohyoid vessels and nerves ; the canal runs forward 

 in the bone a little distance beneath the ends of the roots of 

 the teeth, and emerges at the mental foramen, turning out- 

 wards at an angle to reach it, and sending onwards small 



