THE SPHENOIDAL TURBIXAL 



51 



At birth tliis bone is represented by two scroll-like Itones, very delicate, and covered 

 with irregular dej^ressions, which give it a worm-eaten appearance. Six months 

 after ])irth a nucleus appears in the ethmo-vomerine plate for the mesethmoid. 

 This gradually extends into the crista galli. During the third year the lateral 

 masses and tlie mesethmoid (perpendicular plate) ankylose. The criljriform plate 

 is derived from the lateral masses. 



The ethmoidal cells do not make their appearance before the third year, and they 

 gradually produce attenuation of the lateral masses. In many places there is so 



Fig. 61.— Skction through the Nasal Fossa to show the Lateral Mass of the 

 Ethmoid, It shows also the Outer Wall of the Left Nasal Fossa. 



BODY OF SPHENOID 



SPHENOIDAL SINUS 



SPHENO-PALATINE FORAMEN 



MIDDLE MEATUS 



INTERNAL PTERYGOID PLATE 



PALATE BONE 



FRONTAL SINUS 



SUPERIOR TURBINAL 

 MIDDLE TURBINAL 

 INFUNDBULUM 



INFERIOR T'-RBINAL 



ANTERIOR NASAL SPINE 



ANTERIOR PALATINE FORAMEN 



much absorption of bone that the cells perforate the ethmoid in situations where 

 it is overlapped by other bones. Along the lower border of the bone, near its articu- 

 lation with the maxilla, the aljsoi-ption leads to the partial detachment of a narrow 

 strip known as the uncinate or unciform process. Sometimes a second but smaller 

 hook-like process is formed, above and anterior to the large one. This process is 

 so very fragile that it is difficult to preserve it in disarticulated bones. The relations 

 of the uncinate process are best studied by removing the outer wall of the antrum. 



THE SPHENOIDAL TURBINAL 



These l)ones (often referred to as the bones of Bertin) are two hollow cones, 

 flattened externally in three planes. They may be obtained as distinct ossicles 

 about the fifth year. At this date they are wedged in between the under surface 



Fig. 62.— The Sphenoidal Turbixal at the Sixth Year. 



of the })re-sphenoid and the orl)ital and si)henoidal processes of the palate bone. 

 The apex of the cone is directed backwards, and appears near the vaginal jn-ocess 

 of the sphenoid. Of its three surfaces, the outer one is in relation with the 

 spheno-maxillary fossa, and occasionally extends upwards between the sphenoid 

 and the os planum of tlie ethmoid to appear on the inner wall of the orbit (fig. 64). 



