THE CEKEBRO-SPINAL SYSTEM OP NERVES. 581 



Speaking* generally, a good knowledge of the anatomy of these 

 nerves is a great step toward the mastery of what is known of 



Corpus (until 

 quadri' < 

 geminum(p08ticum' 



Locus cocruletis 

 Eniinentia ter 



Conartum 



SracTiinm conjutiotivum anticum 

 .Brachium coujunctivum 



posticum 



■Corpus gerStsviiitum 



mediale 



Fedunculita cerebri 



ad coi^pora quaA 

 ~ dvigemina f Cms 

 .ad meduUam f cerebelli 

 oblongatam ) 



Ala ctnerea 

 ^cceseortua nucleus 



Obex 



Clava 



Funtculus cuneatus' 



Funiculus gracihs' 



Pig. 425.— Intended to show especially the origin of both deep and snperficial cranial 

 nerves (after Landois), Koman characters are used to indicate the nerves as they 

 emerge, and Arabic figures their nuclei or deep origin. 



their functions, and such will be assumed in this chapter, so that 

 the student may expect to find the treatment of the subject 

 somewhat condensed. 



The Motor-Oculi or Third Nerve.— With a deep origin in the 

 gray matter of the floor and roof of the aqueduct of Sylvius, 

 branches of distribution pass to the following muscles : 1. All 

 of the muscles attached to the eyeball, with the exception of the 

 external rectus and the superior oblique. 2. The levator pal- 

 pebrse. 3. The circular muscle of the iris. 4. The ciliary 

 muscle. Both the latter branches reach the muscles by the 

 ciliary nerves, as they pass from the lenticular (ciliary, ophthal- 

 mic) ganglion. The relation of the third nerve, as seen in the 



