392 SPECIAL ANATOMY. 



5. Nn. pterygoidei externus and internus to the muscles of the 

 same name. The last gives filaments to m. tensor palati 

 and tympani by means ofgangl. oticum. (Hence the mem- 

 brana tympani is stretched by the pterygoid muscles in loud 

 sounds, &c.) [?]. 



Distribution of the Trigeminus : 



a. It perforates all the muscles of the face ; 



b. Supplies the pterygoid muscles (with motor nerves) ; 



c. Supplies the skin of the whole face ; 

 * d. The teeth, gums, and jaws ; 



e. Enters into the organs of smell, sight, hearing, taste, endow- 

 ing them with common feeling, but not the specific sensation 

 of smell, sight, &c. ; and also nutrition, e. g. in the conjunc- 

 tiva of the eyes. 



638. VI. N. abducens, the nerve for the external rectus muscle. 



Origin : with two roots : a. from the posterior border of pom 

 Varolii ; b. from the superior part of corpus pyramidale. Course : 

 upwards and rather outwards from under the pons, perforates the 

 dura mater, and passes inwards over the apex of the petrous bone 

 into the cavernous sinus. Here it lies on the outer side ofcarotis 

 and to the inside of the veins of the sinus, and receives two 

 branches from plex. caroticus and one from n. ophthalmicus ; it 

 then passes directly forwards through the fissura orbitalis supe- 

 rior into the orbita, [between the two origins of] m. rectus exter- 

 nus, lying there on its internal surface above the n. oculo-moto- 

 rius, under n. ophthalmicus. 



639. VII. TV. facialis s. communicans faciei, 



formerly known as portio dura paris VII., is a mixed nerve, 

 which arises with two roots ; the larger anterior (motor) root 

 from the posterior border of pons Varol., in the fossa between this 

 and the medidla oblongata ; the smaller posterior (sensitive), from 

 corpus restiforme, where the auditory nerve arises (hence the 

 guidance of the undulations producing sound to the ear by means 

 of n. facialis). Course : external to and above in front of n. 

 acusticus, with which it passes along to the meatus auditorius 

 internus. 



Pars petrosa. In the auditory meatus the nerve gives a small 

 filament to n. acusticus, it enters the canolis Fallopii, forms at 

 the hiatus c. Fall, a curve the bend around the cavity of the 



