736 THE NERVOUS SYSTEM. 



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

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

 Hyo-glossus muscle. 



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

 gums, the sublingual gland, the filiform and fungiform papillae and mucous mem- 

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

 with the hypoglossal nerve. 



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. 



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. 397). 



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. 



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 it may obtain a motor root, and possibly also a sensory root, 

 as these filaments from the nerve to the Internal pterygoid may contain sensory 

 fibres. It communicates with the glosso-pharyngeal and facial nerves through the 

 small superficial petrosal nerve continued from the tympanic plexus, and through 

 this communication it probably receives its sensory root from the glosso-pharyngeal 

 and its motor root from the facial; its communication with the sympathetic is 

 effected by a filament from the plexus surrounding the middle meningeal artery. 

 The ganglion also communicates with the auriculo-temporal nerve. This is prob- 

 ably a branch from the glosso-pharyngeal which passes to the ganglion, and through 

 it and the auriculo-temporal nerve to the parotid gland. A slender filament 

 (sphenoidat) ascends from it to the Vidian nerve. 



Its branches of distribution are a filament to the Tensor tympani and one to the 

 Tensor palati. The former passes backward on the outer side of the Eustachian 



