The Sinus Maxillaris in Man. 343 
1. The dorsosuperior diagonal, from the most dorsal and 
lateral part of the sinus floor diagonally across the base or median 
wall of the sinus, to the most medial and superior part of the re- 
cessus infraorbitalis; 
2. The ventrosuperior diagonal, from the most ventral and 
medial part of the recessus alveolaris diagonally across the base 
of the sinus, to the most lateral and superior point of the cavity; 
3. The superoinferior, from the roof or infraorbital wall of 
the sinus, to the sinus floor (always using uniform points) ; 
4. The ventrodorsal, from the most ventral point of the 
cavity midway between the roof and the floor, to the dorsal wall; 
5. The mediolateral, from the base midway between its 
most ventral and dorsal points, to the precessus zygomaticus of the 
maxilla (in some cases this extends into the maxillary border of 
the zygomatic bone due to the extension of the recessus zygomat- 
icus of the sinus maxillaris into this bone). 
The ventrodorsal distance is especially affected by the degree 
of approximation of the ventral wall of the sinus; the superoin- 
ferior by the degree of hollowing out of the processus alveolaris 
of the maxilla; the mediolateral by the degree of encroachment of 
the lateral nasa! wall; the ventrosuperior diagonal by the extent 
of the recessus alveolaris; and the dors >superior diagonal by the 
extent of the recessus infraorbitalis. Of cours? there are other 
contributing factors to shorten or leng hen these distances, but 
these are the primary factors especially affecting the several 
measurements. 
In order that the measurements of the sinus maxillaris may be 
of most value, it is necessary to compare the two sinuses of the 
same individual, to compare them with the respective sinuses of 
another individual; also to consider the age and the sex. 
A careful examination of the following tables (A, B, C) will 
show conclusively that the sinus maxillaris has a rather wide 
range of variation. These tables also show that in the adult, 
age does not have much bearing on the size of the cavity. A 
reference to table C will show that the smallest cavity is that 
of an old man, aged 70 years; while the largest cavity is also that 
of an old man, aged 77 years. This same table shows that the 
cavity of a, young adult, aged 21 years is a close second to the 
