970 



THE NERVOUS SYSTEM 



the pterygoideus interims it crosses the fibres of the superior constrictor, which arise 

 from the mandible, and turns forwards towards the tip of the tongue, crossing the 

 outer surfaces of the stylo-glossus, liyo-glossus, and genio-glossus. In its course 

 across the hyo-glossus it lies first above, then to the outer side of, and finally 

 below Wharton's duct, and as it ascends on the genio-glossus it lies on the inner side 



of the duel. 



Communications and Branches. While it is on the inner side of the pterygoid- 

 eus externus, the lingual nerve is joined, at an acute angle, by the chorda tympani 

 (figs. 703, 707), a branch of the seventh nerve, and as it lies between the ramus of 

 the mandible and the pterygoideus interims it is connected by a communicating 

 branch with the inferior alveolar (dental) nerve, and gives off one or two small 

 branches, the rami isthmi faucium, which pass to the tonsil and the mucous mem- 

 brane of 'the posterior part of the mouth (fig. 707). 



While it is above the duct it gives a branch, which contains many chorda tympani 

 fibres, to the submaxillary ganglion (see p. 974), and it receives branches from 



FIG. 703. DISTRIBUTION OF THE MANDIBULAR DIVISION OF THE TRIGEMINTS. (Hcnle.) 



BUCCINATOH 



NERVK 



SUBMAXILLARY 

 GANGLION 



MENTAL 

 BRANCH 



.1 NTERIOR 



. 



rollAL NKIIVK 

 Al i:il-l'l.ll-TE.M- 



PORAI. NKKVE 

 POSTER I Hi: 



/>/:!;/' '/'/: v- 



POEAI. NKltVl-: 



NERVE TO 

 SETER 



CHORDA TYM- 

 PANI 

 MYLO-HYOID 



NEK Vh 

 LINOrAL 

 NERVE 

 1. Ml-: HI OR 

 M.VKOLAR 

 NER \'E 



that ganglion. A little further forwards it is connected by one or two branches, 

 which run along the anterior border of the hyo-glossus, with the hypoglossal 

 nerve (fig. 707). It then gives off the sublingual nerve, which runs forwards 

 to supply the sublingual gland and the neighbouring mucous membrane (fig. 707). 

 Its terminal (lingual) branches pierce the muscular substance of the tongue and are 

 distributed to the mucous membrane of its anterior two-thirds. They anastomose 

 with similar branches of the other side and with branches of the glosso-pharyngeal 

 nerve. 



The Inferior Alveolar (dental) Nerve is the largest branch of the posterior 

 portion of the mandibular nerve. It commences on the inner side of the external 

 pterygoid muscle and descends to the interval between, the spheno-mandibular liga- 

 ment and the ramus of the mandible, where it receives one or two communicating 

 branches from the lingual nerve. Opposite the middle of the inner surface of the 

 ramus it enters the mandibular (inferior dental) canal, accompanied by the inferior 



