THE BNTIEE SKULL 517 



The zygomatic arch is shorter and closer to the side of the cranium 

 than it is in the cat. It defines externally the temporal fossa above 

 from the zygomatic fossa below. 



The temporal fossa is easily recognized. It is separated from the 

 orbit in front by a bony wall ; it communicates by an oval aperture 

 with the zygomatic fossa situated below it and extending medially 

 under the cranium ; it is open above. 



The temporal fossa is bounded above and behind by the temporal 

 line, which begins at the frontal external angular process, crosses the 

 coronal suture at the stephanion, and curves backward and downward 

 on the parietal to the asterion. A second curved line somewhat below 

 the temporal line begins at the front of the parietal, and arches to the 

 notch at the lower end of the parieto-mastoid suture, whence it is con- 

 tinued forward as the posterior root of the zygoma ; this line marks 

 the attachment of the temporal muscle. 



The temporal fossa is bounded below by a plane passing almost 

 horizontally through the upper edge of the zygomatic arch and the 

 infratemporal crest on the great wing of the sphenoid and the 

 squamous of the temporal. 



Its anterior wall is formed of the temporal surfaces of the frontal 

 external angular process, of the great wing of the sphenoid, and of the 

 orbital process of the malar. 



Its inner and posterior walls are formed by the squamous, the 

 parietal, the great wing of the sphenoid, and the frontal. On the 

 inner wall are the following sutures : the squamous suture, joining 

 the temporal and the parietal, the coronal suture, and its continuation 

 the fronto-sphenoidal suture, and at the pterion the short transverse 

 spheno-parietal suture. 



The roof of the zygomatic fossa is formed medially of the zygo- 

 matic surfaces of the squamous and the great wing of the sphenoid ; 

 laterally it presents an aperture which is bounded externally by the 

 zygoma and leads upward into the temporal fossa. The tip of the 

 coronoid process of the mandible projects into this aperture. 



The inner wall, which is complete only in the anterior part, is 

 formed by the lateral surface of the outer pterygoid plate and the 

 zygomatic surface of the maxillary. The anterior wall is formed by 

 the maxillary and the malar. The outer wall is furnished by the 

 zygoma above and the ramus of the mandible below. 



