NERVES IX BASE OF SKULL. 



515 



case of the second nerve, terminates as the nerve enters the dura 

 mater. Some of the nerves in the middle fossa of the skull pierce 

 the dura mater before they reach the foramina of exit. The nerves 

 are arranged in twelve pairs, which are enumerated from before 

 backwards in the order in which they perforate the dura mater. 

 Only part of the intracraiiial course of each nerve will be seen at this only partly 

 '.ill be learnt in the dissection of the base of the brain. >e 



FIG. 189. CRANIAL NERVES IN THE BA^E OF THE SKULL. ON TBE LEFT 

 SIDE THE DURA MATER HAS BEEN REMOVED FROM THE MlDDLF. FOSSA 

 TO SHOW THE XERVES IX THE WALL OF THE CAVERNOUS SlNCS, THE 

 GASSERIAN GANGLION, AND THE THREE TRUNKS OF THE FIFTH NERVE. 



2, 3, 4, 5, 6. Second to sixth 

 nerves. 



ial and auditory. 



8. Glosso-pharyngeal, vagus and 

 spinal acce>- 



9. Hypoglossal. On the right side 

 the dura mater is untouched. 



f Offset to the ten tori um from the 

 ophthalmic nerve. 



The FIRST or OLFACTORY XERVES are about twenty small Olfactory 

 filaments which arise from the olfactory bulb of the brain as j^^Tnose 

 it lies in the groove at the side of the crista galli, and descend 

 to the nose through the foramina in the cribriform plate of the 

 ethmoid bone. 



The SECOND or OPTIC NERVE (fig. 189, 2 ), diverging to the eyeball Second 

 from its commissure, enters the orbit through the optic foramen, totife eye! 68 

 It is accompanied by the ophthalmic artery. 



L L 2 



