132 



SPECIAL ANATOMY OF THE SKELETON 



these, as well as the surfaces of bone between them, are rough for the attachment 

 of the muscles, which are enumerated on page 70. 



The Lateral Region of the Skull. The norma lateralis 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 mandible, the other from the angle 

 of the mandible upward and backward to the outer extremity of the superior 

 curved line. This region is divisible into three portions temporal fossa, mastoid 

 portion, and zygomatic or infratemporal fossa. 



FIG. 99. Lateral aspect of the skull. 



The Temporal Fossa (fossa temporalis). 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. In 

 front it is bounded by the frontal, malar, and greater 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 greater wing of the sphenoid. This fossa is formed by five bones, 

 part of the frontal, greater wing of the sphenoid, parietal, squamous portion of the 

 temporal and malar bones, and is traversed by six sutures, part of the frontomalar, 

 sphenomalar, coronal, sphenoparietal, squamoparietal, and squamosphenoidal. 

 The point where the coronal suture crosses the superior temporal ridge is named 

 the stephanion; and the region where the four bones, the parietal, the frontal, 

 the squamous, and the greater wing of the sphenoid, meet, at the anterior inferior 



