520 



THE CRANIAL NERVES. 



The arrangement of Scemmerring is on the whole the preferable one ; 

 but as the plan of Willis has long been in general use, it cannot be 

 entirely abandoned. 



Connection with the encephalon. — The roots of the cranial nerves 

 may be traced for some depth into the substance of the encephalon, a 

 circumstance wliich has led to the distinction of the deep and the siipcr- 

 jlcial origin, by which latter is understood the place at which the nerve 

 appears to be attached to the surface of the encephalon. 



Fig. 328. 



Fig. 328. — View from 



BELOW OP THE CONNEC- 

 TION OF THE Principal 

 Nerves with the 

 Brain. (A. T.) 



The full description of 

 this figure will be found 

 at p. 534 of vol. ii. The 

 following refei-ences apply 

 to the roots of the nerves ; 

 I', the right olfactory tract 

 divided near its middle; 

 II, the left ojitic nerve 

 springing from the com- 

 missure which is con- 

 cealed by the pituitary 

 body ; II', the right optic 

 tract ; the left tract is 

 seen passing back into 

 i and c, the internal and 

 external corpora genicu- 

 lata ; III, the left oculo- 

 motor nerve ; IV, the 

 trochlear ; V, V, the 

 large roots of the tri- 

 facial nerves ; + + , the 

 lesser roots, the -f- of the 

 right side is placed on 

 the Gasserian ganglion ; 

 1, the o^Dhthalmic ; 2, the 

 superior maxillary, and 

 3, the inferior maxillary 

 nerves ; VI, the left ab- 

 ducent nerve; VII, a, h, 

 the facial and auditory 

 nerves; a, VIII, h, the 

 glosso-pharyngeal, pneu- 

 mo-gastric, and spinal ac- 

 cessory nerves; IX, the 

 right hypoglossal nerve ; 

 at 0, on the left side, the 

 rootlets are seen cut 

 short ; C I, the left sub- 

 occipital or first cervical 

 nerve. 



The superficial origin of these nerves is quite obvious. The first pair 

 are attached to the under surface of the frontal'lobes, the second to the 

 posterior portion of the optic thalami, the third to the crura cerebri, the 

 fourth to the valve of Vieussens, the fifth to the sides of the pons, 

 and the remainder to the medulla oblongata. 



