IO2 



APPLIED ANATOMY. 



depression in the median line separating the superciliary ridges. In operating on 

 the sinus from in front, the opening is to be made just to the outer side of the gla- 

 bella in order to avoid the septum between the sinuses. In curetting the sinus, the 

 thinness of the upper and posterior wall separating it from the brain, and of the 

 lower wall or roof of the orbit, should be borne in mind, otherwise they are apt to be 

 perforated. The sinus may be divided into recesses by partial septa projecting from 



FIGS. 123 and 124. Two views of the frontal sinus, showing variation in size in different individuals. The 

 anterior wall has been cut away to expose the interior of the sinus. 



the sides. Drainage into the nose is obtained by passing an instrument from above 

 downward through the anterior ethmoidal cells. In entering the sinus from below 

 from the outside, the opening is made at the extreme anterior upper edge of the 

 orbit, perforating the bone in a direction upward and inward. The opening into the 

 sinus may be enlarged from within the nose by first inserting a probe to protect the 



brain and posterior wall and then chisel- 

 ling or gnawing away the bone in front 

 so that easy access is obtained through 

 the nose for drainage, packing, etc. 



The ethmoidal sinuses or cells, 

 three in number on each side, anterior, 

 middle, and posterior, lie between the 

 sphenoidal sinus posteriorly, and the 

 lower extremity of the frontal sinus an- 

 teriorly. The anterior cells lie in front 

 of or just above the hiatus and open 

 into it. The middle lie just posterior to 

 the hiatus and open into the outer wall 

 of the middle meatus, perforating the 

 bulla ethmoidalis, which is a rounded 

 projection on the outer wall beneath the 

 middle turbinated bone. The posterior 

 cells open still farther back beneath the 

 superior turbinated bone in the superior 

 meatus. In disease of these cells, pus 

 from the middle and anterior ones will 

 show in the middle meatus; from the 

 posterior cells in the superior meatus. In this latter case it is to be detected pos- 

 teriorly by means of the rhinoscopic mirror. Access to the cells is obtained by 

 removing the middle turbinated bone. This is done by dividing it into two pieces 

 by a transverse cut with forceps or scissors and then removing the two halves with 

 a snare. By means of probes, curettes, and forceps, the openings into the cells may 



FIG. 125. Probes introduced into the frontal, max 

 illary, and sphenoidal sinuses. The anterior portion of th< 

 middle turbinate has been removed. 



