THE SKULL THE CEANIUM 



281 



upper and longest ridge indicates the lower limit of the external 

 frontal sinus. To these lines are attached the bony partitions between 



FIG. 204. 



Nasal Process, with Nasal. 

 With Maxillary. 



Opening oj Frontal Sinus >| 



Median Plate. 

 With Maxillary | 



Nasal Surface, with Ridges 

 for Lateral Ethmoid. 



Postorbital Process. 



Orbital Surface. 



LEFT FRONTAL BONE, ANTERIOR VIEW. 



the scroll-like portion of the lateral ethmoid. This surface forms the 

 upper posterior part of the outer wall of the nasal cavity. Its anterior 

 border articulates above the internal angular process with the maxillary, 



FIG. 205. 



Left Premaxillary. 



Left Premaxillo-maxillary Suture. 



Posterior Surface of Left Nasal Bone. 

 Ridge for Median Nasal Septum. 



Ridge for Partition of Mesial Scrolls, 

 m. 



Upper Wall of Infra-orbital Foramen. 



Ridge on Maxillary for Ethmoidal 

 Cleft-plate. 



Nasal Process of Left Frontal Bone. 

 Fossa in Nasal, and Frontal for An- 

 terior End of Ethmoidal Scroll, 1'. 



Fossa on Frontal for Scroll, 1'. 



Ridyefor Upper Ethmoidal Parti- 

 tion, 1. 



Orbital Plate of Frontal. 

 Fossa for Ethmoidal Scroll, 1" . 



Frontal Sinus. 



ROOF AND PART OF ANTERIOR WALL OF NASAL CHAMBER ; ETHMOID REMOVED. 



and below it with the lachrymal, the os planum, the palatine, and the 

 orbitosphenoid. 



