180 



TOPOGRAPHICAL ANATOMY OF THE 



The cerebral nerves (Nervi cerebrales).— Twelve pairs of nerves 

 arise from eacli half of the brain. These are either named numerically, 



vm 



Fic;. 83. — Diagram of the origin and relations of the root-fibres 

 of the cerebral nerves. 



or are given designations that signify their function, distribution or 

 some notable characteristic : — 



Nervus olfadorius. 



,, opticus. 



., oculomotorius. 



,, trochlearis. 



„ trigtrainus. 



., abducens. 



,, facialis. 



., acusticus. 



,, gIosso2}haryngeus. 



„ vagus. 



,, accessorius. 



„ hypoglossus. 



The intracranial course of the cerebral nerves, and their mode of 

 exit from the cranium, have been previously determined (page 142). 

 Each nerve is associated with cells in the interior of the brain, from 

 which it can be traced to some definite point on the surface where it 

 has what is generally called its " superficial origin." This is the best 

 time at which the superficial origins of the various nerves may be 

 determined. 



