48 INFERIOR TURBINATED BONES. 



the external, which looks into the 

 Fig. 26.* spheno-maxillary fossa. 



The sphenoidal portion, much smaller 

 than the orbital, has three surfaces, 

 two lateral and one superior. The ex- 

 ternal lateral surface enters into the 

 formation of the spheno-maxillary fos- 

 sa ; 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 sphe- 

 noid bone, and assists the sphenoidal 

 spongy bones in closing the sphenoidal 

 sinuses. This portion takes part in 

 the formation of the pterygo-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 horizontal with the perpendicular por- 

 tion of the bone. It is received into the angular fissure, which exists 

 between the two plates of the pterygoid process at their inferior extre- 

 mity, and presents three surfaces: one concave and smooth, which 

 forms part of the pterygoid fossa ; and one at each side to articulate 

 with the pterygoid plates. The anterior face of this process is rough 

 and articulates with the superior maxillary bone. 



Development. By a single centre, which appears in the angle of 

 union between the horizontal and perpendicular portion, at the same 

 time with ossification in the vertebrae. 



Articulations. With six bones ; two of the cranium, the sphenoid 

 and ethmoid ; and four of the face, the superior maxillary, inferior 

 turbinated bone, vomer, and the palate bone of the opposite side. 



Attachment of Muscles. To four ; the tensor palati, azygos uvulae, 

 internal and external pterygoid. 



INFERIOR TURBINATED BONES. The inferior turbinated or spongy 

 bone, is a thin layer of light and porous bone, attached to the crista 

 turbinalis inferior of the inner wall of the nares, and projecting in- 

 wards towards the septum narium. The inferior turbinated bone is 

 broad in front, narrow and tapering behind, and slightly curled upon 

 itself, so as to bear some resemblance to one valve of a bivalve shell, 



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

 maxillary surface. 1. The rough surface of this plate, which articulates with 

 the superior maxillary bone and bounds the antrum. 2. The posterior palatine 

 canal, completed by the tuberosity of the superior maxillary bone and pterygoid 

 process. The rough surface to the left of the canal (2) articulates with the 

 internal pterygoid plate. 3. The spheno-palatine notch. 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 

 maxillary bone. 7 The sphenoidal portion of the perpendicular plate. 8. The 

 pterygoid process or tuberosity of the bone. 



