NERVOUS SYSTEM. 



In the human subject the sublingual is usually more or less affected in 

 hemiplegia. In these cases, as the patient protrudes the tongue the point is 

 deviated. This is due to the unopposed action of the genio-hyo-glossus upon 

 the sound side, which, as it protrudes the tongue, directs the point toward 

 the side affected with paralysis. 



A disease of rather rare occurrence has been described under the name 

 of glosso-labial-paralysis, which is characterized by paralysis of the sublin- 

 guals, affecting also the orbicularis oris and frequently the intrinsic muscles 

 of the larynx. The phenomena referable to the loss of power over 'the tongue 

 correspond to those observed in animals after section of the sublingual nerves. 

 Patients affected in this way experience difficulty in deglutition, and in addi- 

 tion there is some interference with articulation, which can not be observed 

 in experiments upon animals. 



TRIFACIAL (LARGE ROOT OF THE FIFTH NERVE). 



A single nerve, the large root of the fifth pair, called the trifacial or the 



trigeminal, gives general sensibility to 

 the face and to the head as far back 

 as the vertex. This nerve is impor- 

 tant, not only as the great sensitive 

 nerve of the face, but from its con- 

 nections with other nerves and its re- 

 lations to the organs of special sense. 

 Physiological A natomy. The ap- 

 parent origin of the large root of the 

 fifth is from the lateral portion of the 

 pons Varolii, posterior and inferior to 

 the origin of the small root, from 

 which it is separated by a few trans- 

 verse fibres of white substance. The 

 deep origin is far removed from its 

 point of emergence from the encepha- 

 lon. The roots pass entirely through 

 the substance of the pons, from with- 

 out inward and from before back- 

 ward, without any connection with 

 the fibres of the pons itself. By this 

 course the fibres reach the medulla 

 oblongata, where the roots divide into 

 three bundles. The anterior bundle 

 passes from behind forward, between 

 the anterior fibres of the pons and the 

 cerebellar portion of the restiform 

 bodies, to anastomose with the fibres 

 of the auditory nerve. The other 

 bundles, which are posterior, pass, the 



FIG. 809. Principal branches of the large root of 

 the fifth nerve (Robin). 



a, ganglion of Gasser ; a-w. ophthalmic division 

 of the fifth ; 6, ophthalmic ganglion ; c, 

 branch from the ophthalmic division of the 

 fifth to the ophthalmic ganglion ; d, motor 

 oculi communis ; e, carotid ; /, ciliary nerves ; 

 g. cornea and iris ; a-fc, superior maxillary di- 

 vision of the fifth; f, iico branches from the 

 superior maxillary division of the fifth to the 

 spheno-palatine ganglion ; j, deep petrosal 

 nerve ; fr, filaments from the motor root of the 

 fifth to the internal muscle of the malleus ; i, 

 naso-palatine ganglion ; m. otic ganglion : n, 

 small superficial petrosal nerve ; o, branches 

 of the fifth to the submaxillary ganglion ; p. 

 branches to the sublingual gland ; g, facial 

 nerve ; r. sympathetic ganglion ; s, nerve of 

 mastication ; , chorda tympani, joining the 

 lingual branch of the fifth ; it, Vidian nerve : 

 w, branch from the motor root, to the internal 

 pterygoid muscle ; w, branch of Ihe fifth to 

 the lachrymal gland ; x, bend of the facial 

 nerve ; y, middle meningeal artery ; z. fila- 

 ment from the carotid plexus, to the ophthal- 

 mic ganglion ; (1 and 2 are not in the figure) 3, 

 external spheno-palatine filaments ; 4, spheno- 

 palatine ganglion ; 5, naso-palatine nerve : 6, 

 anterior palatine nerve ; 7, inferior maxillary 

 division of the fifth ; 8, nerve of Jacohson. 



