424 SPECIAL ANATOMY. 



a. N. carotico-tympanicus inferior, from the external branch, 

 passes through a little canal on the posterior outer wall of 

 can. carotic. into the tympanum for the nerv. Jacobsonii 

 (see n. glosso-pharyngeus). 



b. N. Vidianus .profundus (s. petrosus prof, major), passes 

 through can. Vidianus, with n. Vid. superficial, to the gangl. 

 Meckelii (see trigeminus), after it has received the superior 

 connecting branches with the pkx. tympanicus. 



N. petrosus profundus minor. This passes out between 

 can. caroticus and the osseous tuba Eustachii. 

 c. Connecting branches with m. abducens ; commonly, three 

 wind round the second curvature of the carotis outwards, 

 and pass into the sinus cavernosus, to nerv. abducens, 

 where this crosses the carotis. 







672. Plexus cavernosus, is situated below and on the inner side 

 of carotis, at its entrance into the sinus cavernosus, is gray, per- 

 forated by arteries, and gives numerous branches, which form a 

 plexus, partly about the carotis and its branches, and partly pass 

 to other nerves. Branches : 



1. For n. oculo-motorius. A twig passes, constantly, between 

 n. oculo-motor. and ophthalmicus (n. quinti) through Jissura 

 orbital, super, to the longer (or shorter) root of ganglion cili- 

 are. Others pass close over n. abducens to n. ocido-motorius. 



2. For n. trigeminus. They pass over the third curvature of 

 carotis from within outwards, and advance, partly into the in- 

 ternal portion of gangl. Gasseri, partly into n. ophtlialmicus. 

 Several rr. recurrentes pass backwards to the tentorium cere- 

 beUi. 



3. For n. abducens. They pass on the internal inferior side of 

 n. abducens below the last curvature of the carotid ; some- 

 times to n. trochlearis. 



4. For n. options and gangl. spheno-palatinum. Some fila- 

 ments go on the inner side of nerv. abducens from the supe- 

 rior anterior part ofplez. cavernosus, but only reach as far as 

 the sheath of the optic nerve, and appear to anastomose with 

 filaments of the gangl. spheno-pal. (Valentin.) 



5. Ramuli sphenoidales (four to six) pass inwards to the dura 

 mater around the hypophysis (but probably not into this), and 

 into the sinus sphenoidalis. 



6. Ramuli ad carotidem cerebralem pass on the inner side of n. 

 abducens, on the sigmoidal superior curvature of the carotis 

 to plex. n. mollium. 



