246 



Anatomy of Skeleton 



If the outer wall of the cavity with its soft parts (Fig. 194) is studied, it is seen that 

 the inferior turbinal body is separated by the middle meatus from the middle turbinal, 

 which is the lowest part of a mass that projects into the nasal fossa towards the septum : 

 evidently this mass lies between the outer wall (os planum) and the upper and middle 



nafi.1 l/enes . 



JC. 



H. 



infundit. 



sphenoid.. 



<'(. tup. 

 tort, turt. 



FIG. 196. Schemes of the arrangements of the groups of cells which constitute the 

 labyrinth. i. Groups of left mass seen from the right (inner or septalside). 

 P., the posterior group, is on the whole above and internal to the middle group, 

 M., as well as behind it, and this group is again above and internal to the anterior 

 group, A. ; i.e., each group overlaps the one in front of it internally and above 

 and thus grooves may be considered to exist along the lower margins of P. and M., 

 directed forwards and upwards and due to the prominence of the more posterior 

 group. Such grooves make the upper and middle meatuses, and the corresponding 

 turbinals are suspended over them from the prominent overhanging margins. The 

 frontal sinus and infundibulum may be considered an upgrowth from the groove 

 between M. and A., and thus it is separated from the outer wall by A. Sections 

 through i, about the levels of the arrows, would cut the groups somewhat as shown 

 in 3, in which the position of the uncinate process of the ethmoid is also indicated, 

 showing how the anterior group can extend into it downwards. 2 is the same 

 scheme of arrangement seen from above, showing the relations of the groups to 

 the outer wall (os planum and lachrymal). Compare this with the next figure and 

 the one after that. 



turbinates, which are simply dependent folds on its inner or septal aspect. On removing 

 the mucous membrane (No. 2) the underlying bony structure presents the same appear- 

 ance of turbinate bones as comparatively small folds or projections suspended from the 

 inner or superficial aspect of a deeper mass ; the general surface exposed is flat, marked 

 by the mucous covering, and the middle turbinate bone hangs from its lower border 

 and is thus held away from the outer wall of the nose by the depth of the intervening 

 mass. 



