122 THE SKULL [chap. 



Connected with the posterior lateral parts of the cranium 

 are two appended bony parts : the lower jaw or mandible, 

 and the hyoidean apparatus. The former forms the frame- 

 work for the floor of the mouth, and supports the lower 

 series of teeth ; the latter gives a firm yet movable point 

 of attachment to the root of the tongue and to the larynx, 

 or organ of voice. 



The 7?iandible consists of two symmetrical elongated rami 

 (see Fig. 45, p. 97), diverging behind, and coming in contact 

 in front at the middle line, by a roughened surface called the 

 symphysis {s) ; here they are firmly held together by inter- 

 posed fibrous tissue, or in old animals they may become 

 ankylosed. 



Each ramus is compressed from side to side, has a 

 thickened rounded lower border, slightly curved in the 

 longitudinal direction, and a nearly straight upper alveolar 

 border, in which the teeth are implanted. The inferior 

 border inclines upward in front to meet the alveolar border 

 at the front of the symphysis. Near the posterior extremity 

 is the condyle [cd), a transversely-extended projection, with its 

 upper surface rounded in the antero-posterior direction, and 

 which, fitting into the glenoid cavity of the squamosal bone, 

 forms the hinge-like synovial articulation by which the lower 

 jaw moves on the skull. The upper border, between the 

 condyle and the hindermost tooth, rises into a high, com- 

 pressed, recurved process (the coronoid process, cp), to which 

 the temporal muscle is attached. The outer surface of this 

 process gradually subsides into a considerable hollow in the 

 side of the ramus, with prominent anterior, inferior, and 

 posterior edges, to which the masseter, another powerful 

 muscle for closing the jaw, is attached. 



The point at which the vertical hinder edge of the ramus, 

 descending from the condyle, meets the horizontal inferior 



