1582 A MANUAL OF ANATOMY 



Meckel's ganglion is now to be dissected. It is suspended from the trunk 

 ot the superior maxillary nerve in the spheno-maxillary fossa by means of 

 the two short spheno-palatine nerves, and lies close to the spheno-palatine 

 foramen on the inner wall of the fossa. To understand the course of the 

 branches of this ganglion it is absolutely necessary that the dissector should 

 have an accurate knowledge of the foramina and canals which communicate 

 with the spheno-maxillary fossa. With this knowledge his path will be 

 comparatively smooth, but without it he is certain to become befogged. 

 The spheno-maxillary fossa is so much hemmed in by bone that the dissection 

 of Meckel's ganglion and its branches is one of the nicest dissections in the 

 body. The dissector must act with discretion and osteological knowledge, 

 and he will no doubt clear paths with the bone-pliers which will show the 

 course of the nerves now to be mentioned. 



The spheno-palatine nerves have been already shown descending from the 

 superior maxillary nerve to the ganglion, to which they convey sensory fibres. 

 To understand the courses taken by the branches of the ganglion, it may be 

 said that four paths lead from the spheno-maxillary fossa, namely (i) internal, 

 representing the spheno-palatine foramen ; (2) inferior, representing the 

 posterior palatine canal and its two byways — the posterior and externa) 

 accessory palatine canals ; (3) posterior, representing (a) the Vidian or pterygoid 

 canal and (b) the pterygo-palatine canal ; and (4) antero-superior, representing 

 the spheno-maxillary fissure. The dissector will now, it is to be hoped, be 

 able to follow the branches of Meckel's ganglion. Taking the internal path 

 through the spheno-palatine foramen, he will find (i) the superior nasal 

 Qerves, and (2) the naso-palatine nerve, or nerve of Cotunnius, all of which 

 enter the nasal fossa. Traversing the inferior path and its two byways, he 

 will find the three descending palatine nerves — great or anterior, small or 

 posterior, and external. In following out the great or anterior descending 

 palatine nerve through the posterior palatine canal the dissector is to show 

 the two inferior nasal nerves which it gives off, and these can be traced without 

 much difficulty to the nasal fossa by removing with the bone-pliers whatever of 

 the vertical plate of the palate bone may be necessary. Pursuing the pos- 

 terior paths, the dissector should look for (i) the Vidian nerve, which takes the 

 Vidian or pterygoid route, and (2) the pharyngeal nerve, which passes through 

 the pterygo-palatine canal. The orbital branch (or branches) of the ganglion 

 takes the antero-Superior path, and, passing through the spheno-maxillary 

 fissure, enters the orbit. 



The branches of the third part of the internal maxillary artery fall in the 

 way of being dissected in the course of the foregoing very complicated dis- 

 section. The dissector cannot possibly hope to show everything, so that, to 

 a certain extent, he should rest satisfied with the description given in the 

 text. The posterior dental artery has been already dissected. The infra- 

 orbital artery may be available for dissection. If so, it will have become 

 evident in the course of dissecting the infra-orbital nerve, of which it is 

 the companion in all respects. The spheno-palatine, descending palatine. 

 Vidian, and pterygo-palatine branches may be left with this enumeration 

 of them. 



The course of the Vidian nerve, just referred to, may be exposed by re- 

 moving the portion of bone which lies external to the foramen ovale, and 

 laying open the Vidian canal. Like the preceding dissection, this is one of 

 much nicety. The Vidian nerve, when followed backwards to the region of 

 the foramen lacerum medium, will be found to divide into the great super- 

 ficial petrosal and great deep petrosal nerves. The great superficial petrosal 

 nerve may be followed beneath the Gasserian ganglion to the hiatus Fallopii, 

 through which it enters the aqueduct of Fallopius to reach the geniculate 

 ganglion of the facial nerve. The great deep petrosal nerve passes to the 

 carotid plexus of the s)rmpathetic. 



The foramen ovale may now be laid open and the inferior maxillary nerve, 

 with the motor root of the fifth cranial nerve, exposed. The internal ptery- 

 goid nerve is to be shown arising from the back part of the inferior maxillary 

 immediately after the latter has received the motor root, and, in intimate 



