BRANCHES OF THE FIFTH NERVE. 807 



maxillary. The posterior temporal, the smaller of the two, is distributed to the 

 upper part of the pinna and the neighboring tissues. 



The Lingual Nerve (gustatory) supplies the papillae and mucous membrane of 

 the tongue. It is deeply placed throughout the whole of its course. It lies at 

 first beneath the External pterygoid muscle, together with the inferior dental 

 nerve, being placed to the inner side of the latter nerve, and is occasionally 

 joined to it by a branch which crosses the internal maxillary artery. The chorda 

 tympani also joins it at an acute angle in this situation. The nerve then passes 

 between the Internal pterygoid muscle and the inner side of the ramus of the 

 jaw, and crosses obliquely to the side of the tongue over the Stylo-glossus 

 muscle, and then between the Hyo-glossus muscle and deep part of the submaxil- 

 lary gland : the nerve lastly runs across Wharton's duct, and along the side of 

 the tongue to its apex, lying immediately beneath the mucous membrane. 



The branches of communication are with the facial through the chorda tympani, 

 the inferior dental and hypoglossal nerves, and the submaxillary ganglion. The 

 branches to the submaxillary ganglion are two or three in number ; those con- 

 nected with the hypoglossal nerve form a plexus at the anterior margin of the 

 Hyo-glossus muscle. 



The branches of distribution are few in number. They supply the mucous 

 membrane of the mouth, the gums, and the sublingual gland, while the lingual 

 or terminal branches supply the mucous membrane of the tongue over its anterior 

 two-thirds, terminating in the filiform and fungiform papillae. 



The Inferior Dental is the largest of the three branches of the inferior max- 

 illary 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 jaw to the dental foramen. It then passes forward in the 

 dental canal of the inferior maxillary bone, 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 mylo-hyoid, dental, incisive, and 

 mental. 



The mylo-hyoid 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 jaw, in which it is retained by a process of fibrous membrane. It 

 reaches the under surface of the Mylo-hyoid muscle, and supplies it and the 

 anterior belly of the Digastric, occasionally sending one or two filaments to the 

 submaxillary gland. 



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 incisive branch is continued onward within the bone to the middle line, 

 and supplies the canine and incisor teeth. 



The mental branch emerges from the bone at the mental foramen, and divides 

 beneath the Depressor anguli oris 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 communicate 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. 



Otic Ganglion (Fig. 485). 



The Otic Ganglion (Arnold's) 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 round the origin of the internal ptery- 

 goid nerve. It is in relation, externally, with the trunk of the inferior maxillary 

 nerve, at the point where the motor root joins the sensory portion ; internally. 

 with the cartilaginous part of the Eustachian tube, and the origin of the Tensor 

 palati muscle ; behind it is the middle meningeal artery. 



