ANATOMICAL DESCRIPTION 



291 



and communicates with a nerve plexus of the sympathetic 

 system. 



4. The trochlear, the smallest of the cranial nerves, is 

 motor. It supplies the superior oblique muscle of the eye, 

 and communicates with the same plexus as does the third 

 nerve. 



5. The trigeminal, 

 the largest cranial 

 nerve, is mixed in 

 function. Its motor 

 division goes to the 

 muscles of mastica- 

 tion. The larger 

 division is the great 

 sensory nerve of the 

 face and head. 



6. The abducens 

 supplies the external 

 rectus muscle of the 

 eyeball as its motor 

 nerve. 



7. The facial is 

 the great motor nerve 



of the muscles of the face. One of its branches, the 

 chorda tympani, passes across the tympanum and joins the 

 lingual branch of the fifth nerve. It is purely motor. 



8. The auditory; a sensory nerve, leaves the surface of 

 the brain in two roots : one, the cochlear branch, is the 

 auditory nerve proper, and goes to the cochlea ; the ves- 

 tibular branch ends in the semicircular canals, the utricle, 

 and the saccule. 



9. The glossopharyngeal, after communicating with 

 several neighboring nerves and ganglia, separates into 



\*t and -2nd 



"Spinal Nerves 



Fig. 135. Diagram of the distribution of 

 the cranial nerves. 



