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COMPARATIVE MORPHOLOGY OF VERTEBRATES 



A number of facts go to show that the ophthalmic branches of the trigeminal 

 nerve really form a distinct nerve, and so it has been represented in figure 190. 

 Among these features the most prominent is that, while the centre of the rest 

 of the fifth nerve lies in the medulla, the fibres of the ophthalmic are traced 

 into the mid-brain (fig. 168). 



In teleosts the fifth nerve often sends a nerve backward (the recurrent or 

 lateralis of the fifth) along the dorsal side of the body near the dorsal fin. This 

 receives branches from the spinal nerves. In a few fishes this goes also to the 

 paired fins. 



Fig. 195. — Diagram of cranial nerves of a cat, the lower jaw reflected, after Mivart. 

 II-XII, cranial nerves; ct, chorda tympani; d, dentary nerve; g, Gasserian ganglion; to, 

 infraorbital nerve; /, lingual nerve; li, Is, laryngeus inferior and superior; tnd, man- 

 dibularis nerve; mx, maxillaris nerve; 0, ophthalmic nerve; /, tongue. 



VII. The facial nerve (Nervus facialis) arises from the medulla 

 oblongata just in front of the ear. In the forms with a lateral line 

 component it bears two closely associated ganglia (fig. 190, VII), but 

 in all others only a single geniculate ganglion, these being closely 

 associated with the Gasserian ganglion of the fifth nerve in the 

 ichthyopsida. The true facial nerve gives off a palatine nerve 

 which runs in the roof of the mouth, and then it divides, just above 

 the spiracle into a pretrematic nerve which goes into the lower jaw, 

 and a postrematic branch, called the hyoid nerve in comparative 

 anatomy. It is the facial nerve of man. In the higher vertebrates 

 this hyoid gives off a small nerve, the chorda tympani, which soon 



