50 PRACTICAL ANATQMY. 



surface, which completes the pterygoid fossa anteriorly. 

 At the junction of the horizontal portion with the tuber- 

 osity are several foramina, leading into canals, the acces- 

 sory posterior palatine. The orbital process is a hollow 

 wedge, which projects from the upper anterior border 

 of the vertical plate ; it ig about one-half inch antero- 

 posteriorly, one-half inch vertically, and., one-fourth inch 

 transversely. It presents five surfaces, two of which are 

 non-articular and three articular. The non-articular sur- 

 faces are the orbital and zygomatic ; the articular are 

 the ethmoidal, maxillary, and sphenoidal surfaces. The 

 orbital surface is triangular and smooth, and is directed 

 upward and forward and outward, and assists in forming 

 the floor of the orbit. The zygomatic surface is quadri- 

 lateral in outline, smooth, is directed outward, backward, 

 and slightly downward. It limits the spheno-maxillary 

 fossa anteriorly. The angle of junction of the zygomatic 

 and orbital surfaces is smooth and rounded, and forms 

 part of the anterior boundary of the spheno-maxillary 

 fissure. The ethmoidal surface is directed forward, in- 

 ward, and upward; it articulates with the lateral mass 

 of the ethmoid behind and below the os planum. Occa- 

 sionally the cavity of the orbital process communicates 



with the cells of the ethmoid. The maxillary surface is 







directed forward, downward, and outward, is trilateral 

 in outline, and slightly rough for articulation with the 

 upper part of the posterior border of the superior maxil- 

 lary. The sphenoidal is directed backward, inward, and 

 upward. It is a quadrilateral surface, the margins of 

 which are roughened for articulation with the sphenoidal 

 turbinated bone. The sinus of the orbital process is 

 sufficiently large to hold a currant; its walls are thin and 

 translucent, its floor (maxillary surface) being frequently 

 cribriform. The sphenoidal process projects from the 



