The Sinus Maxillaris in Man. 359 
with the infundibulum ethmoidale, and the other communicat- 
ing directly with the meatus nasi medius (positive and negative 
relations) (fig. 30). 
d. By the nasofrontal duct being continued down to. the 
infundibulum ethmoidale; and in conjunction there being a 
passage-way between the ventral attachment of the concha 
nasalis media and the processus uncinatus of the ethmoid bone, 
to the meatus nasi medius (considered as positive relations). 
e. By a direct communication between the sinus maxillaris 
and the sinus frontalis, by what may be termed the maxillo- 
frontal duct (direct relation) (fig. 26). 
Of the SO specimens studied to ascertain the fronto-maxillary 
relations; 45 showed a positive relation, or a percentage of 56.25: 
32 a negative relation, or a percentage of 40: 2.a combination of post- 
tive and negative, or a percentage of 2.5 ; 1 a direct communication 
between the two sinuses, or a percentage of 1.25. 
The importance of the above conditions was in each case 
tested by putting fluid unto the sinus frontalis to determine 
the course of drainage. It at once became apparent that the 
specimens falling under classes (a) and (d) should be classed 
together as representing positive fronto-maxillary relations. 
The only difference in the above two conditions is that in class 
(a) all of the fluid put into the sinus frontalis will reach the 
supertor and ventral part of the infundibulum ethmoidale; 
while in class (d) some of it. will pass directly into the meatus 
nasi medius, and the remaining portion to the infundibulum eth- 
moidale. 
Class (6) will drain fluid from the sinus frontalis directly into 
the meatus nasi medius. It is, however, important to know 
that even in these cases some fluid may reach the infundibulum 
ethmoidale, because of the intimate relations existing between 
the nasofrontal duct and the superior and ventral end of the 
infundibulum ethmoidale (fig. 29). 
Class (c), where the sinus frontalis has two nasofrontal ducts, 
the drainage is of course partly into the meatus nasi medius and 
partly into the infundibulum ethmoidale. This class leads to 
similar results as mentioned above, the only difference being that 
