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NERVOUS SYSTEM 



line in the anterior wall of the fourth ventricle. From this origin the 

 large root of the fifth passes obliquely upward and forward to the gan- 

 glion of Gasser, which is situated in a depression in the petrous portion 

 of the temporal bone, on the internal portion of its anterior face. 



The Gasserian ganglion is semilunar in form, with its concavity look- 

 ing upward and inward. At the ganglion the nerve receives filaments of 



communication from the carotid 

 plexus of the sympathetic. This 

 is important in view of certain 

 remote effects that follow division 

 of the fifth nerve through the 

 ganglion in living animals. 



At the ganglion of Gasser, 

 from its anterior and external 

 portion, are given off a few small 

 and unimportant branches to the 

 dura mater and the tentorium. 



From the convex border of 

 the ganglion the three great di- 

 visions arise, which have given to 

 the nerve the name of trifacial 

 or trigeminal. These are : I, the 

 ophthalmic ; 2, the superior max- 

 illary ; 3, the inferior maxillary. 

 The ophthalmic and superior max- 

 illary divisions are derived en- 

 tirely from the sensory root. The 

 inferior maxillary division joins 

 the motor root and with it forms 

 a mixed nerve. 



The ophthalmic, the first di- 

 vision of the fifth, is the smallest 

 of the three. Before it enters 

 the orbit it receives filaments of 

 communication from the sympa- 

 thetic, sends small branches to 

 all the motor nerves of the eye- 



Fig. 126. Principal branches of the large root of 

 the fifth nerve (Robin). 



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

 of the fifth ; b, ophthalmic ganglion ; c, branch from 

 the ophthalmic division of the fifth to the ophthalmic 

 ganglion; d, motor oculi communis; e, carotid; f t 

 ciliary nerves ; g, cornea and iris ; a-h, superior 

 maxillary division of the fifth ; i, two branches from 

 the superior maxillary division of the fifth to the 

 spheno-palatine ganglion ; j, deep petrosal nerve; 

 k, filaments from the motor root of the fifth to the 

 internal muscle of the malleus; /, naso-palatine 

 ganglion ; m, otic ganglion ; n, small superficial 

 petrosal nerve ; o, branches of the fifth to the sub- 

 maxillary ganglion ; p, branches to the sublingual 

 gland; q, facial nerve; r, sympathetic ganglion; 

 s, nerve of mastication ; t, chorda tympani, joining 

 the lingual branch of the fifth ; u, Vidian nerve ; 

 v, branch from the motor root to the internal ptery- 

 goid muscle; w, branch of the fifth to the lachrymal 

 gland; x, bend of the facial nerve; y, middle me- 

 ningeal artery ; z, filament from the carotid plexus 

 to the ophthalmic ganglion; (i 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 jacobson. 



ball and gives off a small recur- 

 rent branch which passes between the layers -of the tentorium. 



Just before the ophthalmic enters the orbit by the sphenoidal fissure 

 it divides into three branches, the lachrymal, frontal and nasal. 



The lachrymal, the smallest of the three, sends a branch to the orbi- 



