mcuibAL OUIUUL 



300 HEAD AND NECK 



above it, but are separated from it by a thin plate of bone, 

 which, however, may be replaced by fibrous tissue. 



Nervus Caroticus Interims. The dissector has already 

 noted that the internal carotid nerve is a large branch which 

 proceeds from the upper end of the superior cervical ganglion, 

 and enters the carotid canal, with the internal carotid artery. 

 It divides almost immediately into two parts, which are placed 

 one on each side of the artery. Each part soon divides into 

 a number of branches which communicate together, around 

 the internal carotid artery, forming the internal carotid plexus. 

 The dissection of the branches is a matter of some difficulty, 

 and can be satisfactorily effected only under specially favour- 

 able circumstances. 



At the posterior end of the cavernous sinus a ganglion is 

 sometimes found in the plexus, and where the sixth nerve 

 crosses the internal carotid artery the plexus is very dense. 

 That part is known as the cavernous plexus. At the anterior 

 end of the cavernous sinus the carotid plexus breaks up into 

 branches which accompany the anterior and middle cerebral 

 arteries. 



The internal carotid plexus communicates with the 

 tympanic plexus by means of superior and inferior carotico- 

 tympanic branches given off in the carotid canal, and with 

 the spheno-palatine ganglion by the great deep petrosal 

 branch, which unites with the greater superficial petrosal of 

 the facial nerve to form the nerve of the pterygoid canal 

 (O.T. Vidian). It gives branches also to the semilunar 

 ganglion, the third, fourth, sixth and the ophthalmic branch 

 of the fifth nerve, and a branch which accompanies the naso- 

 ciliary nerve into the orbit, where it joins the ciliary 

 ganglion. 



NERVUS MAXILLARIS. 



As the maxillary nerve passes forwards, from the semilunar 

 ganglion to the face, it traverses the foramen rotundum, the 

 upper part^f the pterygo-palatine^fossa/the pterygo-maxillary 

 fissure, the nifra-temporal fossa, the inferior orbital fissure, and 

 the infra-orbital canal. The dissector should therefore proceed 

 to expose the nerve in those localities. 



Dissection. Remove the temporal muscle and the upper 

 head of the external pterygoid muscle, and, placing the saw 



