THE CRANIAL OR ENCEPHALIC NERVES. 7U 



mrttn^vf ^^,*^''' ^^'''' ^'' '"^ «°"°^"nication with several cranial nerves 

 ^ W7 ^^ " pneumogastric, glosso-pharyngeal, facial, and auditory 

 sen"rrt ^f thTw ^-^^-— ThiV|anglion, ^hich receives the 

 w^lTl T i tr geminus, is crescent shaped, its concavity beine 



ScarSrot :lr""'".-l* "^^ ""' '^'^'^'"'^ imbeddeJin h! 

 te^^oral mZ, «.H 1 ■? ^^'''^ '° P"^'* ''^^^^^ *lie occipito-spheno- 

 temporal hiatus, and divides it into several particular foramina Its 



tTth^t ^itbrLr^"^'^ '' ^'^ '"^^ '^^'^^' ^-' -'^^ ^ numberTf fiLenJ: 

 The Gasserian ganglion is not continued by a single trunk, but imme- 

 diately gives rise to two thick branches, one of which leaves the craZL 



wT.nlpVrnr"'-Ti'~:^''^ T""^^ ^°™^'l ^y t^e above-named hiatus; 

 while the other is lodged in the external fissure in the intereranial face of 

 the sphenoid bone, and passing along it as far as the entrance to the supra- 

 spiienoidal foramina, bifurcates. 



Hence it results that the trigeminus is divided, even at its origin, into 

 three branches: two superior— the ophthalmic branch of Willis, and the 

 superior maxillary nerve, commencing by the same trunk ; and an inferior 

 which constitutes the inferior maxillary nerve. 



Motor or small root (Figs. 337, 338).— This is a flattened band which 

 emerges from the pons Varolii, at the inner side of the principal root. Its 

 fibres may be easily followed to the interior of the pons Varolii, and in their 

 dii-ection they comport themselves like those of the large root, by becoming 

 confounded with the substance of the antero-lateral fasciculus of the 

 medulla oblongata. Leaving the pons, this root passes forwards on the 

 inferior face of the Gasserian ganglion, which it crosses in a diagonal 

 manner outwards, and beyond which it intimately unites with the fibres 

 of the inferior maxillary nerve. The superior maxillary nerve and the 

 ophthalmic branch do not receive any fibres from it. In the fifth pair, then, 

 it is only the inferior maxillary nerves which are at the same time sensitive 

 and motor, and are real mixed nerves. 



A. Ophthalmic Beanoh (Pig. 335, 1).— This is the smallest of the 

 three divisions furnished by the Gasserian ganglion, and proceeds by a 

 trunk common to it and the maxillary nerve, which will be described here- 

 after. ^ This branch enters the smallest of the large suprasphenoidal 

 foramina, along with the common and external oculo-motor nerves, and 

 in the interior of this bony canal divides into three ramuscules, which reach 

 the bottom of the ocular sheath by the orbital hiatus. 



These ramuscules are : 



1. The/roMtaZ or supra-orbital (supratrochlear) nerve. 



2. The lachrymal nerve. 



3. The nasal or palpebro-nasal nerve. 



1. Frontal Neeve (Fig. 335, 4). — This is a flat, voluminous branch 

 placed on the inner wall of the ocular sheath, and proceeding nearly parallel 

 with the great oblique muscle of the eye to the supra-orbital foramen, into 

 which it passes along with the artery of the same name. Undivided before 

 its entrance into this orifice, immediately after its exit from it, it separates 

 into several ramuscules, which meet the anterior auricular nerve, and are 

 expended in the skin of the forehead and upper eyelid. 



2. Lachrymal Neeve (Fig. 335, 3). — This is composed of several 

 filaments, which ascend between the ocular sheath and the elevator muscles 

 of the eyelid and superior rectus, to enter the lachrymal gland. One of 



