50 PALATE BONES. 



border is concave, and presents at its inner extremity 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, to which is united the inferior turbinated bone. The slightly 

 concave surface below this ridge enters into the formation of the 

 inferior meatus of the nose, and that above the ridge of the middle 

 and superior meatus. The external surface, extremely irregular, is 

 rough on each side for articulation with the 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 forms the posterior palatine canal. 



Near the upper part of the perpendicular plate is a large opening, 

 the spheno-palatine foramen, which transmits the 

 Fig. 21 * spheno-palatine nerves and artery, and serves to 



divide the upper extremity of the bone into two 

 portions, an anterior or orbital, and a posterior 

 or sphenoidal portion. The orbital portion pre- 

 sents five surfaces ; three articular, and two 

 free ; the three articular are the anterior, which 

 looks forward and articulates with the superior 

 maxillary bone, internal with the ethmoid, and 

 posterior with the sphenoid. The free surfaces 

 are the superior or orbital, which forms the pos- 

 terior part of the floor of the orbit, and the exter- 

 nal, which looks into the spheno-maxillary fossa. 

 The sphenoidal portion,] much smaller than 



the orbital, has three surfaces, two lateral and one superior. The 

 external lateral surface enters into the formation of the spheno- 



its internal or nasal surface. 3. 10, 11. The pterygoid process or tuberosity. 4. The 

 broad internal border of the horizontal plate which articulates with the similar border 

 of the opposite bone. 5. The pointed process, which with a similar process of the 

 opposite bone forms the palate spine. 6. The horizontal ridge which gives attach- 

 ment to the inferior turbinated bone ; the concavity below this ridge enters into the 

 formation of the inferior meatus, and the concavity (2) above the ridge into that of the 

 middle and superior meatus. 7. The spheno-palatine foramen. 8. The orbital portion. 

 10. The middle facet of the tuberosity, which enters into the formation of the pterygoid 

 fossa. The facets 11 and 3 articulate with the two pterygoid plates, 11 with the 

 internal, and 3 with the external. 



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

 lary surface. 1. The rough surface of this plate, which articulates with the superior 

 maxillary bone. 2. The posterior palatine canal, completed by the tuberosity of the 

 superior maxillary bone. The rough surface to the left of the canal (2) articulates 

 with the internal pterygoid plate. 3. The spheno-palatine foramen. 4, 5, 6. The 

 orbital portion of the perpendicular plate. 4. The spheno-maxillary facet of this por- 

 tion ; 5. its orbital facet ; 6. its maxillary facet, to articulate with the superior maxil- 

 lary bone. 7. The sphenoidal portion of the perpendicular plate. 8. The pterygoid 

 process or tuberosity of the bone. 



t Called by Homer, the pterygoid apophysis. G. 



