148 SKELETON. 



fore the angle of the bone, we see a concavity of this edge, but 

 generally it is straight, or nearly so. 



The extremities or rami of the lower jaw are quadrilateral, 

 and rise up much above the level of the body. The superior 

 margin presents a thin concave edge, bounded in front by the 

 coronoid, and behind by the condyloid process. The coronoid 

 process is triangular, and receives the insertion of the temporal 

 muscle; its base is thick, but its apex is a thin rounded point. 

 The condyloid process is a transverse cylindrical ridge, directed 

 inwards, with a slight inclination backwards, its middle being 

 somewhat more elevated than the extremities. It springs from 

 the ramus by a narrow neck. There is a concavity at the 

 inner fore part of its neck for the insertion of the pterygoideus 

 externus, and a convexity behind. 



The external face of the ramus is flat, but marked by the in- 

 sertion of the masseter muscle. The internal face, at its lower 

 part, is flat and rough, for the insertion of the pterygoideus in- 

 ternus. At the upper part of this roughness is the posterior 

 mental or maxillary foramen, through which the inferior maxil- 

 lary vessels and nerve pass. It is partially concealed by a spine 

 of bone, into which a ligament from the os temporis is inserted. 

 Leading from this foramen is a small superficial groove, made 

 by a filament of the inferior maxillary nerve. 



The angle of the inferior maxillary bone, formed by the 

 meeting of the'base and the posterior margin of the ramus, pre- 

 sents diversities well worth attention, at .different epochs of life, 

 and in different individuals. In very early life, and in very 

 advanced, when the alveoli are absorbed, it is remarkably ob- 

 tuse. In most middle-aged individuals it is nearly rectangular. 

 Besides which, its corner is sometimes bent outwards and some- 

 times inwards, increasing or diminishing thereby the breadth 

 of the face at its lower part. 



The substance of this bone, externally, is hard and compact. 

 Internally there is a cellular structure, through the centre of 

 which runs the canal for the nerves and blood vessels. From 

 this canal smaller ones are detached, containing the vascular and 

 nervous filaments which go to the roots of the teeth. The max- 

 illare inferius articulates with the temporal bones, by means of 

 their glenoid cavities. 



