382 SPECIAL ANATOMY. 



632. III. N. ocuk-motorius, the nerve of Motion for the 



muscles moving the globe of the Eye. 



Origin : between the crura cerebri, and from them, with a series 

 of filaments, the most internal meeting in the subst. perforata media 

 (therefore the simultaneous movement of both pupils, see gangl. 

 ophthalm.}, it passes forth between pans Varolii and corpp. mam- 

 millaria. Course : at the commencement flat, between art. cerebri 

 poster, and cerebelli superior, then round the last upwards, out- 

 wards and forwards as far as sella turcica, where it perforates the 

 dura mater and the sinus caver nos., and passes at the most inter- 

 nal part through Jissura orbitalis superior into the orbit. Before 

 that it divides into a ram. superior and inferior , which separate in 

 the orbita and unite (not always) with plexus caroticus. Situation 

 in the cavernous sinus : external to carotis, above n. abducens, in- 

 ternal to n. patheticus and ophthalmicus ; immediately in the 

 orbits, below n. frontalis and patheticus, internal to ram. nasalis. 



1. Ramus superior, below and for m. rectus super., and for lev. 

 palpebr. super., in which it soon ramifies with many branches. 



2. Ramus inferior, much larger, between n. opticus and abdu- 

 cens, internal to m. rect. externus ; it immediately divides into 

 three branches : 



a. Ram. internus, to the internal surface of m. rect. internus. 



b. Ram. inferior, to m. rect. inferior. 



c. Ram. externus, passes on the outer border of m. rectus infe- 

 rior to m. obliq. inferior, and gives off the short root of gangl. 

 ciliare. 



N. oculo-motor is the motor nerve for all the muscles of the 

 globe of the eye, with the exception of m. obliquus superior and 

 rectus externus. 



633. IV. N. Trochkaris s. patheticus. 



Origin : with three to four filaments from valvula cerebelli ante- 

 rior s. magna, between the cerebrum and cerebellum, behind the 

 corpp. quadrigemm. ; it inclines round the crus cerebelli super. 

 and appears at the basis before the pons Varolii, external to crus 

 cerebelli, internal to n. trigeminus. Course : forwards through a 

 canal of the tentorium to the outer wall of the sinus cavernosus ; 

 passes through the broadest part of the Jissura orbit, super., at the 

 same time with ram. frontalis, into the orbits. Here it passes in- 

 wards and forwards, obliquely over iheram. super, n. oculo-motor., 

 and the posterior extremity of mm. levator. and rectus sup., to the 

 superior border of m. obliquus superior. Situation : as far as sella 



