PHYSIOLOGY OF THE CRANIAL NERVES. 



535 



that when the fifth nerve is divided, animals are always slow and awk- 

 ward in the movement of the muscles of the face and head, or hold them 

 still, or guide their movements by the sight of the objects towards 

 which they wish to move. 



Again, the fifth nerve has an indirect influence on the muscular 

 movements, by (b) conveying sensations of the state and position of the 

 skin and other parts: which the mind perceiving, is enabled to deter- 

 mine appropriate acts. Thus, when the fifth nerve or its infra-orbital 

 branch is divided, the movements of the lips in feeding may cease, or be 

 imperfect. Bell supposed that the motion of the upper lip in grasping 



FIG. 367. General plan of the branches of the fifth pair. %. 1, lesser root of the fifth pair; 2, 

 greater root passing forwards into the Gasserian ganglion ; 3, placed on the bone above the ophthal- 

 mic nerve which is seen dividing into the supra-orbital, lachrymal, and nasal branches, the latter 

 connected with the ophthalmic ganglion; 4, placed on the bone close to the foramen rotundum, 

 marks the superior maxillary division, which is connected below with the spheno-palatine ganglion, 

 and passes forwards to the infra orbital foramen; 5, placed on the bone over the foramen ovale, 

 marks the inferior maxillary nerve, giving off the anterior auricular and muscular branches, and 

 continued by the inferior dental to the lower jaw, and by the gustatory to the tongue; a, the sub- 

 maxillary gland, the submaxillary ganglion placed above it in connection with the gustatory nerve; 

 6, the chorda tympani; 7, the facial nerve issuing from the stylomastoid foramen. (Charles Bell.) 



food depended directly on the infra-orbital nerve; for he found that, 

 after he had divided that nerve on both sides in an ass, it no longer 

 seized the food with its lips, but merely pressed them against the ground, 

 arid used the tongue for the prehension of the food. Mayo corrected 

 this error. He found, indeed, that after the infra-orbital nerve had 

 been divided, the animal did not seize its food with the lip, and could 

 not use it well during mastication, but that it could open the lips. He, 



