cTiAr. IX.] NERVOUS SYSTEM AND OBGANS OF SENSE. 273 



The second of the three branches of the fifth nerve is called the 

 SUPERIOR MAXILLARY NERVE. It passes through the foraincu 

 rotunduuv, and supplies the lower eyelid, the side of the nose, the 

 upper teeth, and the upper part of the mouth and phar^^nx. After 

 issuing through the foramen rotund urn, the nerve crosses to the 

 infra-orbital canal (Fig. 130, 5b), which it traverses, and then 

 divides and goes to the parts adjacent. The anterior and posterior 

 dental branches supply the teeth. 



Connected with this nerve is a structure called the spJieno- 

 jjalatine ganglion — or Meckel's ganglion — which is placed outside the 

 spheno-palatine foramen. 



The THIRD BRANCH of the trigeminal (Fig. 130, be), which is 

 the largest branch, is termed the inferior imaxillary nerve. It 

 passes through the foramen ovale, and supplies the ear, side of the 

 head, lower lip, gums, teeth, salivary glands, and inside of the mouth. 



As has been said, it is this part with which the smaller, or motor, 

 root of the trigeminal alone unites. After such union, which 

 takes place just outside the foramen ovale, it subdivides into two 

 portions. The smaller of these (which conveys a motor influence 

 alone) goes to the masticatory muscles ; the larger again subdivides 

 into three nerves. 



The first of these, the auriculo-teinporal nerve, passes backwards, 

 under the external pterygoid muscle, and then upwards between the 

 mandible and the external meatus, underneath the parotid gland. 

 There it divides, and its ramifications extend up in the temporal region. 



The second, or gustatory nerve (Fig. 130, gn), which ministers to 

 taste, descends beneath the pterygoid muscles to the side of the 

 tongue, passing above the deep part of the submaxillary gland and 

 crossing Wharton's duct. 



In the early part of its course this nerve is joined by a slender 

 branch from the seventh nerve, called the chorda tympani (Fii:-. 

 130,(70.. . . ^ ^ ^ ° 



The third, or inferior dental nerve (which is the largest of the 

 divisions of the third branch of the trigeminal), descends outside 

 the gustatory nerve and enters the inferior dental canal and supplies 

 the lower teeth (Fig. 130, in.d). 



Before entering the canal it gives off the mijlo-Jujoid hrancli 

 (hih), which runs down the inside of the mandible to the mylo- 

 hyoid and digastric muscles. 



• A branch of the inferior dental foramen escapes outwards at the 

 mental foramen and supplies the adjacent muscles. 



^ 13. The SIXTH nerve (Figs. 128 & 130, c), called also the 

 alducens, seems again to take its origin from the floor of the fourth 

 ventricle. It comes to the surface at the hinder margin of the pons 

 Varolii, between that margin and the anterior pyramid and olivary 

 body of the same side of the medulla oblongata. 



The nerve passes forwards and enters the orbit through the 

 sphenoidal fissure, and is distributed to the external rectus and the 

 choanoid muscles of the eyeball. 



