56 APPLIED ANATOMY. 



hard palate. The operations devised for its relief are both numerous and intricate, 

 and necessitate an accurate anatomical knowledge of the parts. The maxillary 

 nerve is the second division of the fifth cranial nerve. It leaves the skull cavity by 

 the foramen rotundum, then crosses the sphenomaxillary fossa, enters the spheno- 

 maxillary fissure and infra-orbital canal to emerge on the cheek, opposite the middle 

 of the lower edge of the orbit and about 6 mm. below it. The intracranial portion 

 is 6 to 8 mm. in length. From the sphenomaxillary fossa to the infra-orbital fora- 

 men is about 5 cm. (2 in. ). Its branches are as follows: one or two small branches 

 to the dura mater, the orbital or sphenomalar. branch to the cheek and anterior tem- 

 poral region, sphenopalatine branches going to Meckel's ganglion, the posterior, 

 middle, and anterior dental to the upper teeth, and the terminal branches, labial, 

 nasal, and palpebral, on the face. 



Its anterior portion has been removed through an incision on the face, and its 

 posterior portion with Meckel's ganglion has been operated on either anteriorly 

 through the maxillary sinus or laterally through the temporal fossa, after removing 

 the zygoma. The writer has removed the intracranial portion by entering the ante- 

 rior cerebral fossa through the temporal region. Removal of the infra-orbital portion 



Infra-orbital nerve 

 breaking into branches 



Infra-orbital artery 



FIG. 65. Exposure of the infra-orbital nerve and artery. 



of the nerve is so liable to be followed by recurrence of the pain and interferes so 

 much with the more complete procedures, as it destroys the guide (the nerve itself) 

 which leads the operator to Meckel's ganglion, that it is doubtful whether it should 

 ever be resorted to. The posterior dental branches are given off so far back that 

 they are not apt to be removed in this operation. 



Removal of the Infra-orbital Nerve. An incision 3 cm. in length is made 

 along the lower edge of the orbit. This divides the orbicularis palpebrarum muscle. 

 Arising from the bone, between the infra-orbital foramen and the edge of the orbit, 

 is the levator labii superioris muscle. This should be carefully detached, and the 

 foramen with its artery and nerve will be found opposite the middle of the lower edge 

 of the orbit and about 6 mm. ( % in. ) below it, on a line drawn from the supra-orbital 

 notch to between the premolar teeth. The position of the foramen having been 

 located, the palpebral ligament and periosteum are divided and the contents of the 

 orbit raised. The canal is next to be opened. This can be done either by chiselling 

 away its roof from the opening on the face and following it backward or by breaking 



