THE INFERIOR MAXILLARY BONE. 27 



Anterior Border? is grooved for the ethmoidal plate and the nasal cartilage. 



Inferior Border? the longest, articulates with the nasal crest of the superior 

 maxillary and palate bones. 



Posterior Border, is free and presents towards the pharynx. 



Naso-palatine Grooves, laterally, for the naso-palatine nerves. 



Fttrrows, on the lateral surfaces, 6 for vessels and nerve-filaments. 



Name its articulations, centres, and muscles. The vomer articulates 

 with 6 bones, the sphenoid, ethmoid, 2 superior maxillary, and 2 palate 

 bones. It is developed by one centre, which appears about the 6th fcetal week 

 in cartilage between two laminae which coalesce after puberty. It has no 

 muscles attached to it. 



THE INFERIOR MAXILLARY BONE. 



Describe its general characteristics. The inferior maxillary bone forms 

 the lower jaw, receives the inferior teeth, and is the second bone of the body 

 in which ossification appears, the clavicle being the first. It consists of a body 

 and two rami. 



Describe the Body of the bone. It is shaped somewhat like a horse- 

 shoe, and presents for examination the following: viz. 



Alveolar Portion, above the oblique line, containing on its upper border 



alveoli for 16 teeth in the adult, for 10 in the child. 

 Symphysis, a vertical ridge on the median line, marking the junction of the 



two symmetrical portions of which the bone originally consisted. 

 Mental Process, a prominent triangular eminence, forming the chin. 

 Externally on each side from the symphysis backwards, are the 

 Incisive fossa, above the chin, for 

 the origin of the levator menti. 

 Mental Foramen, below the 2d 

 bicuspid alveolus, transmitting 

 the mental artery and nerve. 

 External Oblique Line, for the 

 origins of the depressor labii 

 inferioris and depressor anguli 

 oris muscles from its anterior 

 half. 

 Groove, near the angle, for the 



facial artery. 



Internally, on each side from the median depression backwards, are the 

 Genial Tubercles, the superior for the genio-hyo-glossus muscle; the infer! 01 



for the genio-hyoid. 

 Mylo-hyoid Ridge, obliquely backwards, for the mylo-hyoid muscle. 



