462 TOPOGRAPHICAL ANATOMY. 



4. TrochUaris, appears at the anterior lateral border of pans 

 Varolii, before the cms cerebelli ad pontem, perforates the dura 

 mater behind proc. clinoid. post., passes in a canal formed by it 

 above the apex of the petrous bone, between the superior and outer 

 wall of sinus cavernosus, to the fiss. orbital, super., and into the 

 orbit. 



5. Trigeminus, appears at the anterior lateral border of pans 

 Varolii, before the crura cerebelli ad pontem, external to troch- 

 learis, penetrates the anterior border of tentorium close above the 

 apex of the petrous bone, and there forms the ganglion Gasseri, 

 from the inferior border of which its first, second, and a portion of 

 its third division pass off. 



Ramus I. passes th rough fissura orb. superior. 



II. through foram. rotundum. 



III. through foram. ovale out of the skull. 



6. Abducens, appears between the posterior border ofpotis Va- 

 rolii and the corp. pyramid., enters through the fissure of the dura 

 mater, on the clivus, into the sinus cavernos., and passes, when in 

 this, on the outer side of the carotis to the^ss. orbital, superior. 



I. Facialis, appears at the posterior lateral border of pans Va- 

 rolii, between crus cerebelli ad pont. and corp. restiforme, passes 

 in a sulcus of the acusticus; and enters, by the meatus auditor, in- 

 tern M into the canal Fallopice. 



8. Acusticus, appears externally close to the last, passes to 

 meatus auditor, intern, between corp. olivare, floccul., and crus 

 cerebelli ad pontem. 



9 and 10. Glosso-pharyngeus and vagus, appear below the pos- 

 terior border ofpons Varolii, between corp. olivare and restiforme, 

 they pass out through foram. jugulare [post, lacerated foramen]. 



II. Accessorius Willisii, passes through for. magnum into the 

 cranium, and leaves it through foram. jugulare [post, lacerated 

 foramen]. 



12. Hypoglossus, appears between corp. olivare and pyramid., 

 passes out th rough foram. condyloid. anterius. 



713. VIII. Arteries [see 552, and 554.] 



1 . Carotis cerebralis, enters the sinus cavernosus at the apex of 

 the petrous bone, surrounded by plexus carotic. intern., lies upon 

 the outer inferior side of the sinus, penetrates it behind foram. 

 opticum, gives off art. opkthalmica, and divides into the three fol- 

 lowing arteries : 



a. Art. corpor. callos. [ant. cerebral], lies at its commencement 

 before the chiasma above n. options, then in the scissura 

 longitudinal. 



