92 SURGICAL APPLIED ANATOMY. [Chap. vn. 



with the masseteric. This bend should be taken 

 into consideration in passing a probe along the duct 

 from the mouth. The course of the duct across 

 the masseter is represented by a line drawn 

 from the lower margin of the concha to a point 

 midway between the ala of the nose and the red 

 margin of the lip. It lies about a finger-breadth 

 below the zygoma, having the transverse facial artery 

 above it and the facial nerve below it. The duct has 

 been ruptured subcutaneously, leading to extravasa- 

 tion of saliva. Wounds of the duct are apt to lead to 

 salivary fistulge. When the fistula involves the buccal 

 segment of the duct it may be cured by opening the 

 duct into the mouth on the proximal side of the 

 fistula. Fistulse of the masseteric segment are, on 

 the other hand, very difficult to relieve. At least one- 

 half of the buccal part of the duct is embedded in the 

 substance of the buccinator muscle. A salivary 

 fistula over the masseter may involve the parotid 

 gland itself, or that part of it known as the socia 

 parotidis. Inflammatory conditions may spread to 

 the parotid from the mouth along Stenson's duct. 



3. The upper and lower jaws, and parts 

 connected with them. 



The superior maxilla (for antrum, see Nose, 

 page 81 ; for hard palate, see Mouth, page 110). 

 This bone, on account of its fragility, and the 

 manner in which it is hollowed out, is very readily 

 fractured. The fracture may be due to direct violence, 

 as by a blow from a " knuckle-duster," or it may 

 be broken by a force transmitted from the lower 

 jaw through the teeth, as in cases of severe blows or 

 falls upon the chin. It may be broken by a blow 

 upon the head, when the chin is fixed, no other bone 

 being damaged \ and, lastly, it may be crushed, as 

 above stated, by the driving in of the malar bone. 

 The displacement of the fragments depends upon the 



