THE FIFTH, TRIGEMINAL, OR TRIFACIAL NERVE 991 



The external pterygoid nerve (n. pterygoideus externus] is most frequently 

 derived from the buccal, but it may be given off separately from the anterior 

 trunk of the inferior maxillary nerve. It enters the muscle on its inner surface. 



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

 part sensor, but receives a few filaments from the motor root. It divides into three 

 branches auriculotemporal, lingual, and inferior dental (Fig. 734). 



The auriculotemporal nerve (n. auriculotemporalis) (Fig. 736) generally arises 

 by two roots, between which the middle meningeal artery passes. It runs back- 

 ward beneath the External pterygoid muscle to the inner side of the neck of the 

 mandible. It then turns upward with the temporal artery, between the external 

 auditory canal and the condyle of the mandible, 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 of the auriculotemporal nerve are with the facial 

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

 (rami anastomotici cum n.faciali), usually two in number, pass forward from behind 

 the neck of the condyle of the mandible, to join this nerve at the posterior border 

 of the Masseter muscle. The filaments of communication with the otic ganglion 

 are derived from the commencement of the auriculotemporal nerve. 



The branches of distribution are: 



Anterior auricular. Parotid. 



Articular. Superficial temporal. 



Branches to the external auditory meatus. 



The anterior auricular branches (nn. auriculares anteriores) 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. 



A branch to the temporomandibular articulation, the articular branch, is usually 

 derived from the auriculotemporal nerve. 



The parotid branches -(rami parotidei) supply the parotid gland. 



The superficial temporal branches (rami temporales superficiales) accompany the 

 temporal artery to the vertex of the skull, and supply the integument of the tem- 

 poral region, communicating with the facial nerve, and with the temporal branch 

 of the temporomalar from the superior maxillary nerve. 



The branches to the external auditory meatus (n. meatus auditorii externi\ 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 (ramus membranae tympani). 



The lingual nerve (n. lingualis) (Fig. 734) supplies the papillae and mucous 

 membrane of the anterior two-thirds of the tongue, and is deeply placed throughout 

 the whole of its course. It lies at first beneath the External pterygoid muscle, 

 being placed to the inner side and in front of the inferior dental nerve, and is 

 occasionally joined to this nerve by a branch which may cross the internal maxil- 

 lary artery. The chorda tympani nerve also joins it at an acute angle in this situ- 

 ation. The nerve then passes between the Internal pterygoid muscle and the 

 inner side of the ramus of the mandible, and crosses obliquely to the side of the 

 tongue over the Superior constrictor of the pharynx and the Styloglossus muscles, 

 and then between the Hyoglossus muscle and the deep part of the submaxillary 

 gland; the nerve finally runs across the submaxillary or 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 inferior dental and hypoglossal 

 nerves and the submaxillary ganglion, and, apparently only, with the facial through 

 the chorda tympani. The branches to the submaxillary ganglion are two or three 



