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ANATOMY AND PHYSIOLOGY 



the cranial bones. Some are nerves of motion, some of sensation 

 and some are mixed (Fig. 196). They are named as follows: 



1. Olfactory. 7. Facial. 



2. Optic. 8. Acoustic or auditory. 



3. Oculo-motor. 9. Glosso-pharyngeal. 



4. Trochlear, or pulley nerve. 10. Vagus, or pneumo gas trie. 



5. Trifacial, or trigeminus. u. Spinal accessory. 



6. Abducens. 12. Hypoglossal. 



First, olfactory 



Third, oculo-motor 

 Fourth, pathetic 



(trochlear) 

 Fifth, trifacial 

 Sixth, abducens 

 Seventh, facial 

 Eighth, auditory 



Ninth, glosso-pharynxal 



Tenth, vagus 



Eleventh, spinal accessory 



Twelfth, hypoglossal 



FIG. 196. BASE OF BRAIN AND CRANIAL NERVES, SHOWING RELATION OF THE PONS 

 MEDULLA, AND CEREBRUM. (Monat and Doyen; Brubaker.) 



The first, or olfactory (Fig. 196), is the nerve of smell. Being 

 sensory it is traced toward the brain. 



Minute nerves from the upper part of the nasal mucous membrane 

 (olfactory region), pass up through the sieve-like plate of the ethmoid bone and 

 enter the olfactory bulb; from the bulb, a soft band of fibers called the olfactory 

 tract proceeds to the brain; most of them finally reach the temporal lobe, 

 where they end in the center for the sense of smell, or olfactory center. 



The second, or optic (Fig. 197), is the nerve of vision, 

 begins in the retina. 



It 



The retinal fibers are gathered to form the nerve, which passes through the 

 optic foramen into the cranial cavity. The two optic nerves meet above the 

 body of the sphenoid bone and most of the fibers cross each other there, 



