OSSA PALATI. 93 



Fig. 20.* middle fossa, which is very superficial, 



makes up a part of what is commonly 

 called the fossa pterygoidca. The foreside 

 of this pterygoid process is rotf^h and 

 irregular where it joins the back part of 

 the great tuberosity of the maxillary bone. 

 Frequently several small holes may be 

 observed in this triangular process, par- 

 ticularly one near the middle of its base, 

 which a little above communicates with 

 the common and proper holes of this bone 

 already mentioned. 



The nasal lamella of this bone is extremely thin and brittle, 

 and rises upwards from the upper side of the external edge of 

 the square bone, and from the narrow extremity of the ptery- 

 goid process ; it is so weak, and, at the same time, so firmly 

 fixed to the maxillary bone, as to be very liable to be broken 

 in separating the bones. From the part where the plate rises, 

 it runs up broad on the inside of the tuberosity of the maxillary 

 bone, to form a considerable share of the sides of the maxillary 

 sinus, and to close up the space between the sphenoid and the 

 great bulge of the maxillary bone, where there would other- 

 wise be a large slit opening into the nostrils. On the middle 

 of the internal side of this thin plate, there is a transverse ridge, 

 continued from one which is similar to it in the maxillary bone 



* A posterior view of the palate bone in its natural position ; it is slightly 

 turned to one side to obtain a view of the internal surface of the perpendicular 

 plate (2). 1. The horizontal plate of the bone; its upper or nasal surface. 



2. The perpendicular plate or nasal lamella, seen on its internal or nasal surface. 



3, 10, 11. The pterygoid process or tuberosity. 4. The broad internal border of 

 the horizontal or palatine process, which articulates with the similar process of 

 the bone of the other side. 5. The ridge which with a similar elevation of the 

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

 attachment to the inferior turbinated bone ; the concavity below this ridge forms 

 a part of the inferior meatus of the nose, and the concavity (2) above the ridge 

 forms a part of the middle and superior meatus. 7. The spheno-palatine fora- 

 men. 8. The orbital process of the bone. 10. The middle facet of the ptery- 

 goid process or tuberosity which forms the middle of the pterygoid fossa. The 

 fossae 11 and 3, articulate with the two pterygoid plates of the sphenoid bone: 

 11 with the internal, and 3 with the external. 



