PALATE BONES. 79 



posterior palatine nerve and artery, and the latter the middle palatine 

 nerve. The posterior border is concave, and presents at its inner extre- 

 mity a sharp point, which, with a corresponding point in the opposite 

 bone, constitutes the palate spine for the attachment of the azygos uvulae 

 muscle. 



The perpendicular plate is also quadrilateral ; and presents two surfaces, 

 one internal or nasal, forming a part of the wall of the nares ; the other 

 external, bounding the spheno-maxillary fossa and antrum. The internal 

 surface is marked near its middle by a horizontal ridge (crista turbinalis 

 inferior), to which is united the inferior turbinated bone ; and, at about 

 half an inch above this is another ridge (crista turbinalis superior) for the 

 attachment of the middle turbinated bone. The concave surface below 

 the inferior ridge is the lateral boundary of the inferior meatus of the nose; 

 that between the two ridges corresponds with the middle meatus, and the 

 surface above the superior ridge with the superior meatus. The external 

 surface, extremely irregular, is rough on each side for articulation with 

 neighbouring bones, and smooth in the middle to constitute the inner 

 boundary of the spheno-maxillary fossa. This smooth surface terminates 

 inferiorly in a deep groove, which being completed by the tuberosity of 

 the superior maxillary bone and pterygoid process of the sphenoid, forms 

 the posterior palatine canal. 



Near the upper part of the perpendicular plate is a large oval notch 

 completed by the sphenoid, the spheno-palatine foramen, which transmits 

 the spheno-palatine nerves and artery, and serves to divide the upper ex- 

 tremity of the bone into two portions, an anterior or orbital, and a poste- 

 rior or sphenoidal portion. The orbital portion is hollow within, and pre- 

 sents five surfaces externally, three articular, and two free ; the three 

 articular are the anterior, which looks forward and articulates with the 

 superior maxillary bone, the internal with the eth- Fio . 37 * 



moid, and the posterior with the sphenoid. The 

 free surfaces are the superior or orbital, which forms 

 the posterior part of the floor of the orbit, and the 

 external, which looks into the spheno-maxillary fossa. 



The sphenoidal portion, much smaller than the 

 orbital, has three surfaces, two lateral and one supe- 

 rior. The external lateral surface enters into the 

 formation of the spheno-maxillary fossa ; the internal 

 lateral forms part of the lateral boundary of the nares ; 

 and the superior surface articulates with the under 

 part of the body of the sphenoid bone, and assists 

 the sphenoidal spongy bones in closing the sphenoidal sinuses. This 

 portion takes part in the formation of the ptery go-palatine canal. 



The pterygoid process or tuberosity of the palate bone is the thick and 

 rough process which stands backwards from the angle of union of the 



* The perpendicular plate of the palate bone seen upon its external or spheno-max- 

 illary surface. 1. The rough surface of this plate, which articulates with the superio' 

 maxillary bone and bounds the antrum. 2. The posterior palatine canal, completed 

 by the tuberosity of the superior maxillary bone and pterygoid process. 'The roufrl. 

 surface to the left of the canal (2) articulates with the internal pterygoid plate. .'.'. 

 The spheno-palatine notch. 4, 5, 6. The orbital portion of the perpendicular plate. 4. 

 The spheno-maxillary facet of this portion; 5. As orbital facet; 6, its maxillary facet, 

 to articulate with the superior maxillary bone. 7. The sphenoidal portion of \l?a p-r 

 pendicular plate. 8. The pterygoid process or tuberosity of the bone. 



