548 ANATOMY IN A NUTSHELL. 



The vertical plate is broad and thick and is directed upward and slightly 

 inward. This plate has two surfaces and four borders. 



The external surface articulates with the superior maxillary bone for most 

 of its extent. This pari of the hone is rough. The front part of this surface 

 is smooth and covers the orifice of the antrum of Highmore. The upper and 

 back part of this surface helps to form the spheno-maxillary fossa and is also 

 smooth. On the posterior part of this surface is a deep groove which with the 

 superior maxillary hone forms the posterior palatine canal for the descending 

 palatine vessels and the descending palatine nerve. 



The internal surface forms part of the inferior meatus which is below the 

 inferior turbinated crest.* The superior turbinated crest articulates with the 

 middle turbinated hone, and above this crest is the superior meatus, while 

 between this crest and the inferior turbinated crest is the middle meatus. 



The inferior border joins the horizontal plate at right angles. 



PLATE CCLXXX. 



The Outee Surface of the Pinna. 



The superior border has a notch separating the sphenoidal process from 

 i he orbital process, and this notch is converted into the spheno-palatine foramen 

 by the sphenoidal turbinated bone. The spheno-palatine vessels and the 

 superior nasal and naso-palatine oerves pass through this foramen. It was 

 stated above that this notch was converted into a foramen by the sphenoidal 

 turbinated bone, but it may be convened into a foramen by the two processes 

 meet ing. 



The anterior border has the maxillary process at the anterior extremity 

 of tlw inferior turbinated crest. This process closes the antrum of Highmore 

 posteriorly and inferiorly. This border articulates with the superior maxillary 



I MlllC. 



The posterior border has a deep groove and articulates with the pterygoid 

 process of the sphenoid bone. The Internal pterygoid muscle has part of its 

 origin from a median groove on the lower pari of this border which forms part 

 of the pterygoid process. 



The orbital process is triangular in shape and is directed upward and out- 



