350 Jacob Parsons Schaeffer. 
of the processus uncinatus—thus greatly narrowing the hiatus 
semilunaris, the infundibulum ethmoidale may be of average 
dimensions. This is an important fact, and must always be borne 
in mind when considering the fronto-maxillary relations. 
The processus uncinatus with its covering of mucous membrane 
projects inferiorly and dorsally. By its free superior border it 
forms the inferior boundary of the hiatus semilunaris. This pro- 
cess frequently terminates dorsally in what may be termed two 
roots; the inferior one passes towards the superior edge of the 
concha nasalis inferior, while the superior root curves superiorly 
behind the dorsal termination of the bulla ethmoidalis (figs. 28 and 
29). Such a condition, as the latter, causes the infundibulum 
ethmoidale to end dorsally in a pocket. This fact is of extreme 
importance because the pocket is so situated that it will direct 
any fluid coming to the dorsal end of the infundibulum eth- 
moidale into the sinus maxillaris, via the ostium maxillare which 
is in the immediate location. 
The infundibulum ethmoidale is a groove or gutter situated 
upon the lateral nasal wall. It is bounded superiorly by the 
inferior surface of the bulla ethmoidalis throughout the greater 
part of its extent, save ventrally and superiorly where the bulla 
is replaced by some anterior ethmoidal cells. The inferior and 
medial boundary of the groove is formed by the lateral surface 
of the processus uncinatus. This groove communicates with the 
meatus nasi medius through the hiatus semilunaris. The in- 
fundibulum may end, as stated above, in a pocket; or may loose 
its depth gradually and be lost in the meatus nasi medius (figs. 28, 
29, 30). The superior and ventral end of the infundibulum may 
terminate blindly without dilatation, or in an air cell; or may be 
continuous with the nasofrontal duct. The lateral wall of the 
infundibulum is formed partly by mucous membrane. The depth 
of this gutter-like channel, or the distance from the superior 
border of the processus uncinatus to the floor of the groove, 
varies from 1 to 12 mm., with approximately an average of 5 mm. 
The sinus maxillaris communicates ¢ndirectly with the meatus 
nasi medius by means of an opening—the ostium maxillare— 
which pierces the superior and ventral part of the base of the 
