THE REGION OF THE ORBIT. 39 



the tendo-oculi, and the internal portion of the palpebral 

 aponeurosis. The exact situation of the sac can be felt 

 with the finger, and the best landmark is the anterior 

 lip of the lachrymal groove, surmounted by a small tu- 

 bercle of bone, formed by the external border of the 

 nasal process of the superior maxilla, or if both the lids 

 be abducted from the mesial line, tension is made on 

 the tendo-oculi, which will show itself as a flat cord 

 immediately over the sac, bisecting it. 



To introduce a Probe into the Nasal Dud by the punctum 

 lachrymale. It is frequently necessary to pass a probe 

 into the nasal canal through the punctum ; the lower 

 lid is to be everted, when the punctum will be seen 

 about two lines from the inner angle on a small papilla. 

 The probe is first to be introduced vertically, and pushed 

 downwards for a short distance, when the hand is to be 

 depressed, and the probe pushed inwards until arrested 

 by the os unguis, then raised again vertically ; when the 

 slightest pressure will cause it to traverse the lachrymal 

 sac and enter the nasal canal, pushing it downwards, 

 backwards, and inwards. 



When suppuration takes place in the lachrymal sac, 

 and ulceration through the integument follows, lachry- 

 mal fistula is the result. 



The tears may be prevented passing into the puncta, 

 owing to their being obstructed, or to eversion of the 

 lid from some cause, such as ectropion, as a result of a 

 burn or other injury, or cicatrization after syphilitic 

 ulceration. 



Internal Orbital Region. 



Dissection. To expose the contents of the orbit (the 

 skull cap having been removed) a saw should be entered 



