SUPERFICIAL EXAMINATION 3 



manipulated, since it is concerned in the performance of two operations 

 to be hereafter described. 



Below the zygomatic ridge is an almost flat area, the inferior 

 three-fourths of which are found to be covered by muscle. This is 

 the area of the masseter ; and its posterior, inferior, and anterior 

 boundaries are indicated by a continuous curve which extends from 

 immediately below the articular condyle of the inferior maxillary 

 bone, round the angle of this bone, to terminate on the face near the 

 anterior or lower extremity of the zygomatic ridge. The anterior 

 arm of the curve, which runs almost vertically across the face, 

 indicates the border of the masseter muscle, and also the course of 

 Stenson's Duct with its accompanying vessels, the submaxillary artery 

 and vein. As the vessels curve round the inferior border of the 

 lower jaw, the artery is quite superficially placed, and since it rests 

 immediately on the underlying bone, this is a convenient situation 

 for the taking of the pulse. 



The only point of surgical importance in connection with the 

 masseteric area is the fact that on the external surface of the muscle 

 there is formed an intricate network of nerves called the pes anserinus. 

 To the formation of this plexus the seventh cranial nerve and the 

 sub-zygomatic branch of the fifth cranial nerve contribute. 



Above the zygomatic ridge is an elongated area, which extends 

 from the rim of the orbit above, to the angle of the mouth below. 

 This area is clothed by the thin facial muscles, amongst which 

 ramify the terminal branches of the submaxillary artery and vein 

 and of the infra-orbital branch of the superior maxillary division 

 of the fifth nerve, together with the seventh cranial nerve. Along 

 the line of division between the anterior and middle thirds of this 

 area, but within the nasal chamber, runs the lachrymal duct in 

 the osseous canal on the superior maxillary bone. 



In a direct line with the inferior extremity of the zygomatic 

 ridge, and at a distance of two inches in a superior direction from 



