468 Anatomy Applied to Medicine and Surgeiy. 



orbital foramen, identified. The anterior wall of the su- 

 perior maxillary bone is then trephined, the floor of the 

 orbit is chiselled away, so as to expose the nerve in its 

 canal, and the posterior wall of the antrum having been 

 opened, the gangloin and nerve may be ex- 

 sected. Care should be taken in this operation 

 to avoid the internal maxillary artery that lies 

 just behind the posterior wall of the superior maxillary 

 bone. When the inferior dental is the nerve at fault, its 

 termination on the face may be stretched or divided by an 

 incision placed just below the lower border of the jaw, so 

 that the tissues may be raised up, sufficiently, to expose the 

 mental foramen. This incision makes a less conspicuous 

 wound, afterwards, than one over the bone itself. Should 

 the pain still persist, then the nerve may be exsected far- 

 ther back, by means of a trephine opening made through 

 an incision placed below the margin of the lower jaw. 

 The skin is pushed up, the muscles separated from the bone 

 and the trephine applied about one and a quarter inches 

 above the angle, i.e., about opposite the point correspond- 

 ing to the commencement of the inferior dental foramen 

 on the inner side of the bone, or, the nerve may be exposed 

 through the mouth, by an incision in the mucous mem- 

 brane opposite 'the anterior border of the ascending ramus 

 of the jaw ; the internal pterygoid muscle is then separated 

 from the bone by the finger, which also feels the bony 

 spine marking the beginning of the dental canal ; a sharply 

 curved hook is now employed to draw out the nerve and 

 the latter is exsected. Should, however, intense pain 

 still persist in spite of the division of one or more of these 

 branches of the fifth, then the Gasserian ganglion may be 

 removed. Extirpation of the Gasserian ganglion is done 

 by means of an Omega-shaped incision, made in the tem- 

 poral region with the highest part of the curve near the 



