2. The _optic_, or second pair of nerves, pass to the eyeballs, and are the nerves of vision. 3, 4, 6. The _motores oculi_ (eye movers) are three pairs of nerves used to move the eyes. 5. The _trifacial_, or fifth pair of nerves, divide each into three branches--hence the name--the first to the upper part of the face, eyes, and nose; the second to the upper jaw and teeth; the third to the lower jaw and the mouth, where it forms the nerve of taste. These nerves are implicated when we have the toothache or neuralgia. 7. The _facial_, or seventh pair of nerves, are distributed over the face, and give it expression. [Footnote: If it is palsied, on one side there will be a blank, while the other side will laugh or cry, and the whole face will look funny indeed. There were some cruel people in the middle ages who used to cut the nerve and deform children's faces in this way, for the purpose of making money of them at shows. When this nerve was wrongly supposed to be the seat of neuralgia, or tic douloureux, it was often cut by surgeons. The patient suffered many dangers, and no relief of pain was gained.--MAPOTHER.] FIG. 55. [Illustration: _The Brain and the origin of the twelve pairs of Cranial Nerves._ F, E, _the cerebrum;_ D, _the cerebellum, showing the arbor vitæ;_ G, _the eye;_ H, _the medulla oblongata;_ A, _the spinal cord;_ C and B, _the first two pairs of spinal nerves._] 8. The _auditory_, or eighth pair of nerves, go to the ears, and are the nerves of hearing. 9. The _glos-so-pha-ryn'-ge-al_, or ninth pair of nerves, are distributed over the mucous membrane of the pharynx, tonsils, etc. 10. The _pneu-mo-gas'-tric_, or tenth pair of nerves, preside over the larynx, lungs, liver, stomach, and one branch extends to the heart. This is the only nerve which goes so far from the head. 11. The _accessory_, or eleventh pair of nerves, rise from the spinal cord, run up to the medulla oblongata, and thence leave the skull at the same opening with the ninth and tenth pairs. They regulate the vocal movements of the larynx. 12. The _hyp-o-glos'-sal_, or twelfth pair of nerves, give motion to the tongue. FIG. 56. [Illustration: _Spinal Nerve, Sympathetic Cord, and the Network of Sympathetic Nerves around the Internal Organs_. K, _aorta;_ A, _œophagus;_ B, _diaphragm;_ C, _stomach._] THE SYMPATHETIC SYSTEM contains the nerves of organic life. It consists of a double chain of ganglia on either side of the backbone, extending into the chest and abdomen. From, these, delicate nerves, generally soft and of a grayish color, run to the organs on which life depends--the heart, lungs, stomach, etc.--to the blood vessels, and to the spinal and cranial nerves over the body. Thus the entire system is bound together with cords of sympathy, so that, "if one member suffers, all the members suffer with it."