THE FACE 397 



muscle. The internal oblique line, which begins in front near the 

 tubercles, becomes more prominent as it nears the alveolar border, 



to 



behind ; to it is attached the mylo-hyoid muscle, and in the groove 

 below is lodged the submaxillary gland. 



The superior border contains the alveoli of sixteen teeth, eight on 

 each side, which are, two incisors, one canine, two premolars, and three 

 molars. 



Each ramus, or ascending ramus, is more vertical than the corre- 

 sponding part of the mandible of the cat. The condyloid process is 

 high up at the posterior superior angle ; the coronoid process is rela- 

 tively low, and the sigmoid notch on the superior border is almost 

 horizontal. The angle is less prominent and rounded, and there is no 

 true inferior notch in the posterior border. 



The condyle is relatively narrower than the mandibular condyle of 

 the cat ; its long axis is transverse to the long axis of the ramus, but 

 not transverse to the long axis of the skull ; the outer end, bearing the 

 condyloid tubercle, is more anterior than the inner end. It has a 

 decided neck, which is flattened in front for the attachment of the 

 external pterygoid muscle. 



The lesser width and increased rotundity of the condyle and 

 the manner of its articulation in the gienoid cavity of the temporal 

 give to the lower jaw a larger range of motion than is given by the 

 wider and sharper condyle in the cat ; hence the posterior teeth are 

 true grinding teeth and are not modified into shearing instruments. 



The external surface of the ramus is not deeply depressed by a 

 temporo-masseteric fossa ; it is rough and receives the masseter muscle 

 only ; the temporal muscle, which in man is small compared with the 

 temporal of the cat, is inserted upon the end of the coronoid process. 

 The internal surface is marked by the large dental foramen, guarded 

 in front and above by the mandibular spine. The groove passing 

 downward and forward from the foramen is for the mylo-hyoid nerve 

 and artery. Behind the groove is inserted the internal pterygoid 



muscle. 



THE HYOID BONES. 



General Description. The Hyoid apparatus consists of two 

 slender, jointed rods, each of which is attached by its upper end to the 

 skull (Fig. 314) within the mastoid process of the temporal bone, and 

 at its lower end is joined to its fellow by a shorter unjointed transverse 



