THE BRANCHES OF THE FIFTH NERVE. 735 



the facial nerve round the facial vein. The lower branch passes forward to the 

 angle of the mouth : it supplies the integument and Buccinator muscle, as well 

 as the mucous membrane lining the inner surface of that muscle, and joins the 

 facial nerve. 1 



The External Pterygoid Nerve is most frequently derived from the buccal, but 

 it may be given off separately from the anterior trunk of the nerve. It enters 

 the muscle on its inner surface. 



The posterior and larger division of the inferior maxillary nerve is for the 

 most part sensory, but receives a few filaments from the motor root. It divides 

 into three branches : auriculo-temporal, lingual (gustatory), and inferior dental. 



The auriculo-temporal nerve generally arises by two roots, between which the 

 middle meningeal artery passes. It runs backward beneath the External pterv- 

 goid muscle to the inner side of the neck of the lower jaw. It then turns upward 

 with the temporal artery, between the external ear and condyle of the jaw, under 

 cover of the parotid gland, and, escaping from beneath this structure, ascends 

 over the zygoma and divides into two temporal branches. 



The branches of communication are with the facial and with the otic ganglion. 

 The branches of communication with the facial, usually two in number, pass for- 

 ward from behind the neck of the condyle of the jaw, to join this nerve at the 

 posterior border of the Masseter muscle. They form one of the principal branches 

 of communication between the facial and the fifth nerve. The filaments of com- 

 munication with the otic ganglion are derived from the commencement of the 

 auriculo-temporal nerve. 



The branches of distribution are 



Anterior auricular. Articular. 



Branches to the meatus auditorius. Parotid. 



Superficial temporal. 



The anterior auricular branches are usually two in number. They supply the 

 front of the upper part of the pinna, being distributed principally to the skin 

 covering the front of the helix and tragus. 



Branches to the meatus auditorius, two in number, enter the canal between the 

 bony and cartilaginous portion of the meatus. They supply the skin lining the 

 meatus ; the upper one sending a filament to the membrana tympani. 



A branch to the temporo-mandibular articulation is usually derived from the 

 auriculo-temporal nerve. 



The parotid branches supply the parotid gland. 



The superficial temporal accompanies the temporal artery to the vertex of the 

 skull, and supplies the integument of the temporal region, communicating with 

 the facial nerve, and the temporal branch of the temporo-malar, from the superior 

 maxillary. 



The lingual nerve (gustatory) supplies the papillae arid mucous membrane of 

 the anterior two-thirds 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 this nerve, and is 

 occasionally joined to it by a branch which may cross 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 

 Superior constrictor and Stylo-glossus muscles, and then between the Hyo-glossus 

 muscle and deep part of the submaxillary gland ; the nerve finally 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 tym- 

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



1 There seems to be no reason to doubt that the brancli supplying the Buccinator muscle is entirely 

 a rierve of ordinary sensation, and that the true motor supply of this muscle is from the facial. 



