THE CRANIAL NERVES. 



259 



arrangement of the grey matter in the brain stem as there is in 

 the cord. Instead of forming horns, the grey matter is scat- 

 tered in colonies or nuclei, many of which are centers for 

 the fibers of the cranial nerves. Some of these fibers are, of 

 course, afferent and some efferent. Since many of the cranial 

 nerves are connected with the nose, mouth and teeth, it is im- 

 portant for us to learn something concerning the location of 

 their centers and the general function of the nerves. There are 

 twelve pairs of cranial nerves, and the last ten of these originate 

 from the grey matter of the medulla, pons or midbrain. The 

 following list indicates the general functions of the nerves: 



1. Olfactory. 



2. Optic. 



3. Oculo motor. 



4. Trochlear. 



6. Abducens. 



5. Trigeminal. 



7. Facial. 



8. Auditory. 



9. Glosso-pharyn- 

 geal. 



10. Vagus. 



11. Spinal accessory. 



12. Hypoglossal. 



It is important to 

 the cranial nerves are 



nerve of smell, 

 nerve of sight. 



nerves to the mus- 

 cles of the eyeball. 



sensory nerve of 



face, 

 main motor nerve of 



face muscles, 

 nerve of hearing and 



of semicircular 



canals. 



motor nerve of phar- 

 ynx, sensory nerve 



of taste, 

 efferent and afferent 



nerve to various 



viscera, 

 mainly blends with 



vagus 



motor nerve for 

 tongue muscles 



arises from fore- 

 brain. 



arises from fore- 

 brain. 



arise from midbrain. 



arises mainly in 



pons. 

 arises in pons and 



medulla, 

 arises in pons. 



arises mainly in 

 medulla. 



arises in medulla. 



arises with vagus 

 except spinal por- 

 tion, which extends 

 down into spinal 

 cord. 



arises in medulla. 



note that, like the spinal nerves, many of 

 composed of two roots, motor and sensory, 



