/'///; TRIOEMINAL M-h'\ I- 969 



lion. The trunk is situated between the pterygoideus externus externally and the 

 otic ganglion and the tensor palati internally. In front of it is the posterior border 

 of the pterygoideus interims, and behind it , I he middle mcningeal artery. Two 

 branches arise from the trunk of the ner\e before its division, namely, the spinons 

 (recurrent) nerve and the nerve to the pterygoideus interims. 



The spinous (recurrent) nerve, after receiving a lilament from the otic- ganglion, 

 enters the craniuin through the foramen spinostim. accompanying the middle 

 ineningeal artery, and divides into an anterior and a posterior branch. The anterior 

 branch communicates with the meningeal branch of the maxillary division of the 

 fifth nerve, furnishes filaments to the dura mater, and ends in the osseous sub- 

 stance of tiie great wing of the .sphenoid. The posterior branch traverses the petro- 

 squamous suture and ends in the lining membrane of the mastoid cells. 



The nerve to the internal pterygoid passes under cover of a dense layer of fascia 

 derived from an expansion of the ligament urn pterygo-spinosum, and enters the deep 

 surface of t he muscle. Near its commencement this nerve furnishes a motor root to 

 the otic ganglion, and small branches to the tensor tympani and tensor palati. 



The Anterior Portion of the mandibular nerve is smaller than the posterior and 

 is chiefly motor; it .supplies the muscles of mastication, the temporalis, masseter, and 

 pterygoideus externus, and gives oil a sensory branch, the buccinator (long buccal) 

 nerve. The latter is accompanied, in the first part of its course, by a small strand 

 of motor fibres which leaves it to end in the anterior part of the temporal muscle. 



The deep temporal nerves, usually two in number, posterior and anterior, pass 

 between the bone and the upper border of the external pterygoid muscle, and turn 

 upwards around the infra-temporal crest of the sphenoid bone to end in the deep sur- 

 face of the temporalis (fig. 703). The posterior of the two often arises in common 

 with the masseteric nerve. The anterior is frequently associated with the "buccinator 

 (long 1 mccal ) nerve till t he lat ter has passed between the two heads of the pterygoideus 

 externus. There is frequently a third branch, the medius, which passes outwards 

 above the pterygoideus externus, and turns upwards close to the bone to enter the 

 deep surface of that muscle. 



The masseteric nerve, which frequently arises in common with the posterior 

 deep temporal nerves, passes between the bone and the pterygoideus externus, and 

 accompanies the masseteric artery through the notch of the mandible to be dis- 

 tributed to the masseter (fig. 703). It is easily traced through the deeper fibres 

 nearly to the anterior border of the masseter. As it emerges above the pterygoideus 

 externus it gives off a twig to the temporo-mandibular articulation. 



The nerve to the external pterygoid, after a course of about 3 mm. (an eighth of 

 an inch), divides into twigs which enter the deep surface of the two heads of the 

 muscle. It is usually adherent at its origin to the long buccal nerve. 



The buccinator (long buccal) nerve, entirely sensory, passes between the two 

 heads of the external pterygoid muscle and runs downwards and forwards under 

 cover of or through the anterior fibres of the temporalis to the cheek (fig. 703). As it 

 passes forwards it emerges from under cover of the anterior border of the masseter 

 and lies on the superficial surface of the buccinator, where it communicates with the 

 buccal branches of the seventh nerve and gives off filaments to supply the superjacent 

 .skin ; finally it pierces the buccinator and supplies the mucous membrane on its inner 

 surface as far forwards as the angle of the mouth. The fibres of the anterior deep 

 temporal nerve are frequently associated with the buccinator until the latter has 

 passed between the heads of the external pterygoid; then the anterior deep tempo- 

 ral nerve separates from the buccinator and passes upwards on the outer surface of 

 the upper head of the external pterygoid. 



The Posterior Portion of the mandibular nerve divides into three large branches. 

 Two of these, the lingual and the auriculo-temporal nerves, are exclusively sensory; 

 the third, the inferior alveolar (dental) nerve, contains a strand of motor 'fibres, the 

 mylo-hyoid nerve. 



The Lingual Nerve is the most anterior branch of the mandibular nerve (figs. 703, 

 707). It lies in front and to the inner side of the inferior alveolar (dental) nerve and 

 descends at first on the inner side of the pterygoideus externus. then between the 

 pterygoideus interims and the ramus of the mandible to the posterior part of the mylo- 

 hyoid ridge, where it passes off the anterior border of the pterygoideus interim.-, 

 this point it is situated a short distance behind the last molar tooth and is covered in 

 front by the mucous membrane of the posterior part of the mouth. After leaving 



