THE FACE. 41 



in the sulcus and canal of the same name in the roof of the maxillary sinus (see Figs, n and 16). 

 Neurectomy is sometimes demanded for the relief of severe neuralgia in this region. The nerve 

 may be resected above the second biscuspid tooth at the infraorbital foramen, but it is better to 

 make an incision down to the bone parallel to and below the infraorbital margin, elevating the 

 orbital contents with a spatula, and resecting the nerve as far back as possible in the infraorbital 

 fissure, after \vhich the peripheral portion may be torn out through the infraorbital foramen. 

 [The infraorbital foramen is about one-third of an inch below the lower margin of the orbit, 

 opposite the junction of inner and middle thirds of this margin, and can usually be easily located 

 with the finger. ED.] In this operation the alveolar branches to the teeth of the upper jaw are, 

 of course, torn away from the excised portion of the nerve. The nerve may also be exposed at 

 the infraorbital foramen from the vestibulum oris. Since the infraorbital nerve runs in the 

 relatively thin roof of the maxillary sinus (see Figs. 15 and 16) care must be taken to avoid injury 

 to the sinus, which may lead to subcutaneous emphysema of the orbit. Air entering the orbit in 

 this manner may cause exophthalmos. [When it is deemed necessary to expose and resect 

 MeckeV s ganglion as well as the infraorbital nerve, this is best accomplished by trephining the 

 anterior wall of the maxillary sinus, opening the bony canal of the infraorbital from beneath, 

 and trephining the posterior wall of the sinus, thus opening the spheno-maxillary fossa. The 

 ganglion is slightly below the main trunk of the nerve and in intimate relation with the terminal 

 branches of the internal maxillary artery. By this route the superior maxillary division of the 

 fifth nerve may be easily followed to its exit from the foramen rotundum. ED.] 



The inferior dental nerve, a branch of the inferior maxillary division of the fifth, passes 

 through the inferior dental canal, supplies the teeth of the lower jaw, and makes its exit at the 

 mental foramen below the second biscuspid tooth to be distributed to the skin of the chin 

 (see Fig. i). This nerve is also occasionally resected, the mental foramen being exposed from 

 the vestibulum oris or by direct incision of the overlying structures. In addition to this, the 

 nerve may be exposed by chiseling open or by trephining the infraorbital canal between the 

 angle of the jaw and the coronoid process. 



The important motor nerve of the face is the seventh cranial nerve, the facial nerve. Its 

 course in the petrous portion of the temporal bone (entrance at the internal auditory meatus, 

 exit at the stylomastoid foramen) and its not infrequent involvement in caries or fracture in this 

 situation have been previously mentioned (see page 32). After its exit from the bone, the nerve 

 soon imbeds itself in the parotid gland, from the anterior border of which its numerous branches 

 pass to the facial muscles (see Fig. 14). The nerve may be exposed at its exit from the stylomas- 

 toid foramen by entering behind the styloid process to the inner side of the mastoid process. 



The parotid gland covers the posterior part of the masseter muscle as well as the temporo- 

 maxillary articulation and a considerable portion of its substance extends deeply into the retro- 

 mandibular fossa, bounded in front by the ramus of the jaw and behind by the external auditory 

 meatus and the mastoid process. The parotid duct, frequently in relation with a soda parotidis, 

 passes anteriorly across the masseter and perforates the buccinator muscle to open into the 

 mouth opposite the second upper bicuspid tooth. The orifice of the duct may be made accessible 

 for probing by introducing the finger into the angle of the mouth and drawing the cheek away 

 from the teeth. 



