674 



DISSECTION OF THE HEAD. 



of palatine 

 and 



nasal 

 branches 



contained in osseous canals which require to be opened. The 

 branches are first to be sought, and these are then to be followed 

 to the ganglion and the main trunk. 



Dissection Dissection. The left half of the head is to be used for the dis- 

 play of Meckel's ganglion and its branches ; but the students will 

 derive advantage from rirst attempting the dissection on the remains 

 of the right side. 



To lay bare the branches to the palate, detach the soft parts in 

 the roof of the month from the bone, until the nerves and vessels 

 escaping from the posterior palatine canals are arrived at. Cut off, 

 with the bone forceps, the posterior part of the hard palate to a 

 level with the vessels and nerves ; and cleaning these, trace offsets 

 behind into the soft palate, and follow the main pieces forwards to 

 the front of the mouth. 



Take away, without injury to the naso-palatine nerve and vessels 

 (already found), the hinder portion of the loose piece of mucous 

 membrane detached from the septum nasi ; and separate the mucous 

 membrane from the outer wall of the nasal fossa, behind the spongy 

 bones, as high as the spbeno-palatine foramen. In reflecting for- 

 wards the membrane, vessels and nerves will be seen entering it 

 through the foramen ; but these may be left for the present, and 

 directions for their dissection will be subsequently given. When 

 the lining membrane of the nose has been removed behind the 

 spongy bones, the palatine nerves and vessels will appear through 

 the thin translucent palate bone, and may be readily reached by 

 breaking carefully through the latter with a chisel. Afterwards 

 the tube of membrane containing the palatine vessels and nerves 

 being opened, these are to be followed down to the soft palate and 

 the roof of the mouth, and upwards to the ganglion which is close to 

 the body of the sphenoid bone. 



To bring Meckel's ganglion fully into view, it will be necessary to 

 saw through the overhanging body of the sphenoid bone, to cut away 

 pieces of the bones surrounding the hollow in which it lies and to 

 remove with care the enveloping fat and the periosteum. The 

 ganglion then appears as a flattened reddish-looking body, from 

 which the Vidian and pharyngeal nerves pass backwards. Besides 

 these branches, the student should seek two large nerves from the 

 top of the ganglion which join the superior maxillary trunk, and 

 smaller offsets to the floor of the orbit. 



To trace backwards the Vidian branch to the carotid plexus and 

 the facial nerve, the student must lay open the Vidian canal in the 

 root of the pterygoid process ; and in doing this he must define the 

 small pharyngeal branches of nerve and artery which are superficial 

 to the Vidian, and lie in the pterygo-palatine canal. At the back of 

 the Vidian canal, a small branch from the nerve to the plexus on the 

 internal carotid artery is to be looked for. Lastly, the prolongation 

 of the Vidian nerve (large superficial petrosal) is to be followed into 

 the skull through the dense tissue in the foramen lacerum, after 

 cutting away the apex of the petrous portion of the temporal bone, 



body of 

 ganglion 



Vidian 

 nerve. 



