686 OF THE FUNCTIONS OF THE NERVOUS SYSTEM. 



experimented on the roots exposed within the cranium, it possesses no sensory 

 endowments at its origin; since, when these roots were touched, the animals 

 gave no signs of pain, though violent muscular movements were excited in the 

 face. Subsequently to its first entrance into the canal by which it emerges, 



Fig. 184. 



>* 



The Nerves of the OrUt seen from the outer side: after Arnold.!. Section of the frontal bone; imme. 

 diately behind the numeral is the frontal sinus, and, in front, the integument. 2. The superior maxillary 

 bone ; the section in front of the numeral exhibits the maxillary sinus. 3. Part of the sphenoid bone. 4. The 

 levator palpebrae and superior rectus muscles. 5. The superior oblique muscle. 6. The inferior oblique 

 muscle. 7. The ocular half of the external rectus muscle drawn forwards. 8. The orbital half of the external 

 rectus muscle turned downwards. On this muscle the sixth nerve is seen dividing into branches. 9. The 

 inferior rectus muscle. 10. The optic nerve. 11. The internal carotid artery emerging from the cavernous 

 sinus. 12. The ophthalmic artery. 13. The third nerve. 14. The branch of the third nerve to the inferior 

 oblique muscle. Between this and the sixth nerve (7) is seen the branch which supplies the inferior rectus; 

 its branch to the ophthalmic ganglion is seen proceeding from the upper side of the trunk of the nerve, at the 

 bottom of the orbit. 15. The fourth nerve. 16. The trunk of the fifth nerve. 17. The Gasserian ganglion. 

 18. The ophthalmic nerve. 19. The superior maxillary nerve. 20. The inferior maxillary nerve. 21. The 

 frontal nerve. 22. Its division into branches to supply the integument of the forehead. 23. The lachrymal 

 nerve. 24. The nasal nerve; the small nerve seen in the bifurcation of the nasal and frontal nerve is one 

 of the branches of the upper division of the third nerve . 25 . The nasal nerve passing over the internal rectus 

 muscle to the anterior ethmoidal foramen. 26. The infra-trochlear nerve. 27. A long ciliary branch of the 

 nasal ; another long ciliary branch is seen proceeding from the lower aspect of the nerve. 28. The long root 

 of the ophthalmic ganglion, proceeding from the nasal nerve, and receiving the sympathetic root which joins 

 it at an acute angle. 29. The ophthalmic ganglion, giving off from its fore part the short ciliary nerves. 30. 

 The globe of the eye. 



however, it anastomoses with other nerves ; and thus sensory fibres are intro- 

 duced into it from many different sources anteriorly, from the 5th pair, and 

 posteriorly, from the cervical nerves which cause irritation of several of its 

 branches to produce pain. The number and situation of the anastomoses vary 

 much in different animals ; so that it is impossible to make any very compre- 

 hensive statement in regard to them. Experimental researches leave no doubt 

 that the Portio Dura is the general motor nerve of the face ; ministering to the 

 influence of Volition and of Emotion, and also being the channel of the reflex 

 movements concerned in respiration and other automatic actions of the muscles ; 

 but not being in the least concerned in the act of mastication. 



717. The functions of the Glosso-Pharyngeal nerve have been heretofore 

 alluded td in part ; but there still remain several questions to be discussed in 

 regard to them. Reasons have been given for the belief that it is chiefly an 

 afferent nerve scarcely having any direct power of exciting muscular contrac- 



