CRANIAL NERVES. 489 



arising from the medulla oblongata (as do all 

 that follow), has a (Gasserian) ganglion on its 

 root, and three main branches — the sensory 

 maxillary, which unites with the inner buccal 

 of VII. ; the motor mandibular, which inner- 

 vates the muscles of the jaws ; and the sensory 

 superficial ophthalmic (or orbitonasal), which 

 runs over the eye to the snout, closely united 

 (inside the same sheath) with a similar branch 

 of VII. 

 Parallel to these superficial ophthalmics, internal to 

 and above the inner buccal of VII., there is 

 a ganglionated ophthalmicus profundus, which 

 sends branches to the eyeball, snout, etc., and 

 is referred by some to III., by others to V., and 

 is regarded by others as an independent nerve. 

 VI. The abducens, a slender nerve, arising near the 

 mid-ventral line, adjacent to V. and VIII., and 

 hidden beneath the former, supplies the external 

 rectus muscle of the eye. 

 VII. The facial, the nerve of the spiracular cleft, 

 supplies all the five groups of ampullar on the 

 head, and has numerous branches. 



1. The ophthalmicus superficialis runs over and past 



the eye, in intimate association with the similar 

 branch of V., and supplies ampullae on the 

 snout. 



2. The inner buccal runs under the eye, through the 



nasal capsule, to inner buccal ampullae. The 

 outer buccal runs under the eye, external to the 

 olfactory capsule, to outer buccal ampullae. 



3. The large hyomandibular runs directly outwards 



behind the spiracle to hyoid ampullae. It gives 

 off minor hyoidean nerves. 



4. The external mandibular runs behind and outside 



of the mandibular muscle to mandibular ampullae, 

 and is a branch of the hyo-mandibular. 



5. The palatine descends in front of the spiracle to the 



roof of the mouth. Close beside it there is a 

 prespiracular. 



6. The "facial proper," apparently arising from 3, 



supplies the muscles of the hyoid arch. 



7. The " chorda tympani," apparently arising from 3, 



runs under the spiracle to the inner side of the jaw. 

 With the loss of the sensory ampullEe, the seventh 



