1244 HUMAN ANATOMY. 



of the mandible just anterior to the ramus. It has been seen in one case to arise directly from 

 the Gasserian ganghon and emerge from the cranium through a special foramen situated between 

 the foramina rotundum and ovale. 



The Posterior Division of the mandibular nerve is sensory, with the exception 

 of the mylo-hyoid nerve. It passes downward beneath the external pterygoid and, 

 after giving ofi the two roots of the aicriado-temporal nerve, terminates by dividing 

 into the ling^ial and the mferiof dental nerve. 



Branches.— These are: (i) the auriculo-temporal (2) the lijigiial ^nd (3) 



the inferior dental. 



I. The auriculo-temporal nerve (n. auriculotemporalis) (Fig. 1063) arises just 

 below the foramen ovale by two roots which enclose between them the middle meningeal 

 artery. It passes backward beneath the external pterygoid muscle and between the 

 spheno-mandibular ligament and the neck of the mandible, and then turns upward 

 through the parotid gland between the temporo-mandibular articulation and the external 

 ear. Emerging from the upper margin of the gland, the nerve passes over the root of 

 the zygoma and ascends to the temporal region behind and in company with the 

 superficial temporal artery. 



Branches. — These are : {a) the articular, (d) the parotid, (^) the meatal, {d) 

 the anterior auricular and (<?) the superficial temporal. The last three are 

 terminal branches. 



a. The articular branches (rr. articulares) are one or two delicate filaments which enter 

 the posterior portion of the temporo-mandibular articulation. 



b. The parotid branches (rr. parotidei) pass to the gland ; they arise either from the 

 auriculo-temporal or from its communicating filaments with the facial nerve. 



c. The meatal branches (nn. meatus auditorii externi) are two in number, an upper and a 

 lower. They enter the external auditory canal between the bone and the cartilage and supply 

 the skin covering the corresponding parts of the meatus, the upper branch in addition sending a 

 twig (r. membranae tympani) to the tympanic membrane. 



d. The anterior auricular nerves (nn. auriculares anteriores) , usually two in number, supply 

 skin of the tragus and of the upper anterior portion of the auricle. 



e. The superficial temporal nerve (rr, temporales superficiales) (Fig. 106S) breaks up into 

 a number of fine twigs which supply the skin of the temporal region and of the scalp almost to 

 the sagittal suture. 



The auriculo-temporal communicates by its roots, close to their origin, with branches from 

 the otic ganglion, and by its parotid and superficial temporal branches with the facial nerve. 

 By the first of these communications secretory fibres of the glosso-pharyngeal and sympathetic 

 fibres are carried to the parotid gland ; by means of the second junction sensory trigeminal 

 fibres accompany the peripheral motor filaments of the facial. 



Variations. — In a specimen found in the anatomical laboratory of the University of Pennsyl- 

 vania, the middle meningeal artery, instead of passing between the two roots of the nerve, 

 pierced the anterior one. 



2. The lingual nerve (n. lingualls) (Fig. 1079) is the smaller of the 

 terminal branches of the mandibular nerve. Lying internal and anterior to the 

 inferior dental nerve, it passes downward beneath the external pterygoid as far as the 

 lower border of that muscle. It is usually connected with the inferior dental nerve by 

 an oblique strand of fibres, which occasionally crosses the internal maxillary artery 

 and, close to its origin, it is additionally joined at an acute angle by the chorda 

 tympani nerve. After emerging from under cover of the external pterygoid, it passes 

 between the internal pterygoid and the ramus of the mandible. It then turns inward, 

 forward and downward under the mucous membrane of the floor of. the mouth, cross- 

 ing over the superior border of the superior constrictor of the pharynx and the deep 

 portion of the submaxillary gland, and passes under the submaxillary duct between 

 the mylo-hyoid and hyo-glossus muscles. Reaching the side of the tongue the nerve 

 continues forward to the apex, lying just beneath the mucous membrane. 



Branches. — The lingual nerve supplies small filaments to the sublingual gland, 

 the floor and side of the mouth, the side of the tongue and the lower gum. It 

 gives of? the sensory root of the submaxillary ganglion and its terminal filaments 

 (rr. lingualcs) pass upward through the muscles of the tongue to supply the mucous 



