110 



THE SKELETON. 



The Lateral Region of the Skull. 



The Lateral Region of the Skull is of a somewhat triangular form, the base of 

 the triangle being formed by a line extending from the external angular process 

 of the frontal bone along the temporal ridge backward to the outer extremity of 

 the superior curved line of the occiput : and the sides by two lines, the one drawn 

 downward and backward from the external angular process of the frontal bone 

 to the angle of the lower jaw, the other from the angle of the jaw upward and 



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FIG. 73. Side view of the skull. 



backward to the outer extremity of the superior curved line. This region is 

 divisible into three portions temporal fossa, mastoid portion, and zygomatic fossa. 



The Temporal Fossa. 



The Temporal Fossa is bounded above and behind by the temporal ridges, which 

 extend from the external angular process of the frontal upward and backward 

 across the frontal and parietal bones, curving downward behind to terminate in the 

 posterior root of the zygomatic process (supra-mastoid crest}. In front it is bounded 

 by the frontal, malar, and great wing of the sphenoid; externally by the zygomatic 

 arch formed conjointly by the malar and temporal bones; below, it is separated 

 from the zygomatic fossa by the pterygoid ridge, seen on the outer surface of the 

 great wing of the sphenoid. This fossa is formed by five bones, part of the frontal, 

 great wing of the sphenoid, parietal, squamous portion of the temporal, and malar 

 bones, and is traversed by six sutures, part of the transverse facial, spheno-malar, 

 coronal, spheno-parietal, squamo-parietal, and squamo-sphenoidal. The point 



