THE FACE. 



57 



through its upper wall. This latter procedure is liable to give trouble, because if 

 the track of the canal is not encountered the instrument breaks into the maxillary 

 sinus, the roof of which is very thin. The infra-orbital canal does not pass directly 

 backward but backward and outward, striking the sphenomaxillary fissure about 2 

 cm. (in a large skull) behind its anterior extremity. Sometimes the roof of the 

 canal is fibrous, in which case the groove so formed can be readily felt, but in others 

 it is bony. The nerve is hooked up and cut as far back as one can, so as to remove, 

 if possible, the posterior dental branches. The terminal branches are then pulled off 

 from the cheek, and the nerve drawn out from the front. It is in the highest degree 

 desirable to avoid wounding the artery, as death is said to have followed it, and 



4th nerve 



Ophthalmic branch 5th nerve 

 Motor root 



Sensory root 



Maxillary branch 



Gasserian ganglion 



Meckel's ganglion 



Infra-orbital 

 nerve and artery 



Middle meningeal artery 

 Mandibular branch 

 Temporomalar nerve 



Buccal branch 



Stump of external 

 pterygoid muscle 



Lingual nerve 



Inferior alveolar 

 nerve and artery 



Internal pterygoid 

 muscle 



FIG. 66. The fifth or trifacial nerve with its various branches. 



there may be bleeding into the orbit, causing protrusion of the eye and serious inter- 

 ference with its sight. A better way of removing the nerve, the method of Thiersch 

 ( Verhand. der Deutschen Gesell. fur Chir., 18 Congress, Berlin, 1889, p. 44), is to 

 grasp it with a pair of slender, curved forceps, then by rotating the forceps very 

 slowly (about i turn a minute) both the distal and proximal ends are wound around 

 it and an extremely long portion of the nerve can be removed. 



Removal of Meckel's Ganglion. Operating from the front through 

 the maxillary sinus (Carnochan's operation, or removal of the sphenopalatine 

 (Meckel's) ganglion and maxillary nerve). The incision is V-shaped, the apex 

 being 2 cm. above the angle of the mouth, and the branches 3 cm. long. This flap 

 should consist of all tissues down to the bone. The bleeding will be free, as the 

 facial vein and branches of the facial artery will be cut. As the infra-orbital foramen 

 is reached, the nerve is detached from its under surface. The anterior wall of the 



