86 SURGICAL APPLIED ANATOMY-. [Chap.vn. 



positions of the supra and infraorbital foramina and 

 of the mental foramen are indicated as follows. The 

 supraorbital foramen is found at the junction of the 

 inner with the middle third of the upper margin of the 

 orbit. A straight line drawn downwards from this 

 point so as to cross the gap between the two bicus- 

 pids in both jaws, will hit both the infraorbital and 

 mental foramina. The infraorbital foramen is a little 

 over a quarter of an inch below the margin of the 

 orbit. The dental foramen in the adult is midway 

 between the alveolus and the lower border of the 

 jaw, and is a little over a quarter of an inch below 

 the cul-de-sac of mucous membrane between the lower 

 lip and jaw. At puberty the foramen is nearer to the 

 lower border of the maxilla, and in old age it is close 

 to the alveolus. The infraorbital nerve has been 

 divided for neuralgia at its point of exit, the nerve 

 being reached either by external incision or through 

 the mouth by lifting up the cheek. In other cases the 

 floor of the orbit has been exposed, the infraorbital 

 canal (the anterior half of which has a bony roof) has 

 been opened up, and large portions of the trunk of the 

 nerve have been in this way resected. The inferior 

 dental nerve has been divided at the mental foramen 

 by an incision made through the mucous membrane. 

 Its trunk has been reached and a part excised through 

 a trephine hole made in the body of the lower jaw. 

 It has been divided also before its entry into the 

 dental foramen in the following manner : The mouth 

 being held widely open, an incision is made from the 

 last upper molar to the last lower molar just to the 

 inner side of the anterior border of the coronoid 

 process. The cut passes through the mucous mem- 

 brane down to the tendon of the temporal muscle. 

 The finger is introduced into the incision, and passed 

 between the ramus of the jaw and the internal ptery- 

 goid muscle until the bony point is felt that marks the 



