312 



FUNCTIONS OF THE NERVOUS SYSTEM. 



tributing to it sensory endowments only. The only apparent exception is in 

 the case of the Naso-Ciliary branch; since there is good reason to believe that 

 the long root of the ciliary ganglion, and the long ciliary nerves, possess motor 



[Fig. 151. 



A view of the distribution of the Trifacial or Fifth 

 pair; 1, orbit; 2, antrum highmorianum ; 3, tongue; 

 4, lower jaw-bone; 5, root of the fifth pair, forming 

 the ganglion of Gasser ; 6, first branch of the fifth pair, 

 or ophthalmic ; 7, second branch of the fifth pair, or 

 superior maxillary ; 8, third branch of the fifth pair, or 

 inferior maxillary ; 9, frontal branch, dividing into ex- 

 ternal and internal frontal nerves ; 10, lachrymal 

 branch of the fifth pair ; 11, nasal branch ; just under 

 the figure is the long root of the lenticular or ciliary 

 ganglion and a few of the ciliary nerves; 12, internal 

 nasal nerve, disappearing through the anterior eth- 

 moidal foramen; 13, external nasal nerve; 14, external 

 and internal frontal nerve; 15, infra-orbitary nerve ; 

 16, posterior dental branches; 17, middle dental 

 branch ; ,18, anterior dental nerve : 19, terminating 

 branches of the infra-orbital nerve, called the labial 

 and palpebral nerves; 20, subcutaneous malse, or or- 

 bitar branch ; 21, pterygoid, or recurrent nerve, from 

 Meckel's ganglion; 22, five anterior branches of the 

 third branch of the fifth pair; 23, lingual branch of the 

 fifth, joined by the chorda tympani ; 24. inferior dental 

 nerve ; 25, its menial branches ; 26, superficial tempo- 

 ral nerve ; 27, auricular branches ; 23, mylo-hyoid 

 branch.] 



powers ; but these appear to be derived from the Sympathetic nerve. When 

 the whole nerve, or its anterior branch, is divided in the rabbit, the pupil is 

 exceedingly contracted, and remains immovable ; but in dogs and pigeons it 

 is dilated. The pupil of the other eye is scarcely affected ; or, if its dimen- 

 sions be changed, it soon returns to its natural state. The eyeball speedily 

 becomes inflamed, however; and the inflammation usually runs on to suppu- 

 ration and complete disorganization. The commencement of these changes 

 may be commonly noticed within twenty-four hours after the operation ; and 

 they appear to be due to the want of the protective secretion, which (as will 

 be explained when the direct influence of the nervous system upon the organic 

 functions is considered), is necessary to keep the mucous surface of the eye 

 in its healthy condition, and which is not formed when the sensibility of that 

 surface is destroyed. The Superior Maxillary branch, considered in itself, 

 is equally destitute of motor endowments with the ophthalmic ; but its con- 

 nections with other nerves, through the spheno-palatine ganglion and its anas- 

 tomosing twigs, may introduce a few motor fibres into it. The Inferior 

 Maxillary branch is the only one which possesses motor as well as sensory 

 endowments from its origin; but its different subdivisions possess these endow- 

 ments in varying proportions, some being almost exclusively motor, and others 

 as completely of a sensory character. The latter is probably the nature of 

 the Lingual branch ; and there seems good reason to believe, as will hereafter 

 be shown, that this ministers not only to the tactile sensibility of the tongue, 

 but to the sense of Taste. The muscles put in action by this division of the 

 Fifth pair, are solely those concerned in the masticatory movements. 



405. The Third, Fourth, and Sixth pairs, together make up the appara- 

 tus of motor nerves, by which the muscles of the Orbit are called into ac- 

 tion. The Third pair supplies the greater number of the muscles ; the Fourth 



