170 OSTEOLOGY. 
may be deflected to one or other side. They communicate with the nose through 
a passage called the infundibulum, which opens inferiorly into the fore part of the 
middle meatus. 
The fact should not be overlooked that the air spaces within the temporal 
bone, viz. the tympanic cavity and the mastoid air cells, are brought into com- 
munication with the naso-pharynx through the Eustachian tubes. For further 
details regarding the air-sinuses and the mode of their growth, consult the deserip- 
tion of the individual bones. 
CORONAL SECTIONS. 
The relations of many parts of the cranium are well displayed in a series of coronal 
sections. 
By sawing off a thin slice from the front of the lower part of the frontal bone 
above, and carrying the section downwards through the inner wall of the orbit and 
Fic. 120.—PartT OF THE FrontTAL, NASAL, AND SUPERIOR MAXILLARY BONES REMOVED IN ORDER TO 
DISPLAY THE RELATION OF THE VARIOUS CAVITIES EXPOSED. 
1. Frontal sinus. 7. Cavity of antrum laid open. 
2. Septum of frontal sinus deflected towards the right. 8. Middle meatus of nose. 
3. Infundibulum leading from sinus to middle meatus. 9. Inferior meatus of nose. 
4. Anterior ethmoidal air sinuses. 10. Inferior turbinated bone. 
5. Middle turbinated bone. 11. Nasal septum. 
6. Red line in upper part of osseous canal for nasal 12. Canal for nasal duct laid open throughout its 
duct, laid open throughout its entire length on entire length. 
the right side. 13. Anterior nasal spine. 
the nasal process of the superior maxilla, into the anterior nares below, a number of im- 
portant relations are revealed (see Fig. 120). In the frontal region the extent and 
arrangement of the frontal sinuses are displayed. The partition between the two sinuses, 
be it noted, is usually complete and central in position, though it may occasionally be 
