992 



THE NERVE SYSTEM 



in number; those connected with the hypoglossal nerve form a plexus at the anterior 

 margin of the Hyoglossus muscle. 



The branches of distribution supply the mucous membrane of the mouth, the 

 gums, the sublingual gland, and the mucous membrane of the anterior two- 

 thirds of the tongue; the terminal filaments communicate at the tip of the tongue, 

 with the hypoglossal nerve. The chorda tympani fibres which join the lingual 

 nerve are probably taste fibres and excitoglandular for the submaxillary and sub- 

 lingual salivary glands. 



The inferior dental nerve (n. alveolaris inferior) (Fig. 734) is the largest of the 

 branches of the inferior maxillary nerve. It passes downward with the inferior 

 dental artery, at first beneath the External pterygoid muscle, and then* between 

 the internal lateral ligament and the ramus of the mandible to the dental foramen. 

 It then passes forward in the dental canal of the mandible, lying beneath the teeth, 

 as far as the mental foramen, where it divides into two terminal branches, incisor 

 and mental. 



The branches of the inferior dental are the mylohyoid, dental, incisor, and 

 mental. 



The mylohyoid (n. mylohyoideus) is derived from the inferior dental just as that 

 nerve is about to enter the dental foramen. It descends in a groove on the inner 

 surface of the ramus of the mandible, in which it is retained by a process of fibrous 

 membrane. It reaches the under surface of the Mylohyoid muscle, and supplies 

 it and the anterior belly of the Digastric. 



The dental branches supply the molar and bicuspid teeth. They correspond 

 in number to the fangs of those teeth, each nerve entering the orifice at the point 

 of the fang and supplying the pulp of the tooth. 



The incisor branch is continued onward within the bone to the middle line, and 

 supplies the canine and incisor teeth. 



The dental branches and the incisor branch form a plexus (plexus dentalis infe- 

 rior), and from this plexus come the branches to the teeth (rami dentales inferiores) 

 and to the gums (rami gingivales inferiores). 



The mental branch (n. mentalis) emerges from the bone at the mental foramen, 

 and divides beneath the Depressor anguli oris muscle into two or three branches ; 

 one descends to supply the skin of the chin, and another (sometimes two) ascends 

 to supply the skin and mucous membrane of the lower lip. These branches com- 

 municate freely with the facial nerve. 



Two small ganglia are connected with the inferior maxillary nerve the otic 

 with the trunk of the nerve, and the submaxillary with its lingual branch. 



The Otic Ganglion (ganglion oticum) (Fig. 734) is a small, oval-shaped, flattened 

 ganglion of a reddish-gray color, situated immediately below the foramen ovale, 

 on the inner surface of the inferior maxillary nerve, and surrounding the origin 

 of the internal pterygoid nerve. It is in relation, externally, with the trunk of 

 the inferior maxillary nerve, at the point where the motor root joins the sensor 

 portion; internally, with the cartilaginous part of the Eustachian tube, and the 

 origin of the Tensor palati muscle; behind, it lies in relation with the middle 

 meningeal artery. 



Branches of Communication. This ganglion is connected with the internal 

 pterygoid branch of the inferior maxillary nerve by two or three short, delicate 

 filaments. From this nerve the ganglion may obtain a motor root, and possibly 

 also a sensor root, as these filaments from the nerve to the Internal pterygoid 

 perhaps contain sensor fibres. The otic ganglion communicates with the glosso- 

 pharyngeal and facial nerves through the small superficial petrosal nerve (Figs. 736 

 and 739) continued from the tympanic plexus, and through this communication 

 it probably receives its sensor root from the glossopharyngeal and its motor root 

 from the facial; its communication with the sympathetic is effected by a filament 



