294 



FIFTH PAIR OF NERVES. 



poro-facial, while the other continues forward, 

 upon the face, below the zygoma, and deeper 

 than the branches of the temporo-facial : it 

 divides into numerous long filaments, of which 

 some join botli branches of the temporo-facial ; 

 others are distributed superficially upon the 

 side of the face beneath the zygoma and upon 

 the malar region, and, ascending over the 

 former part, to the inferior anterior part of 

 the temple, as far forward as the margin of 

 the orbit. These may be called the commu- 

 nicating branches, in consequence of the re- 

 markable and important communication which 

 they establish witii the portio dura. 



The next may be called external auricular ; 

 they ascend to the anterior part of the car- 

 tilaginous tube of the ear, concealed by the 

 temporal artery, attach themselves to the tube 

 in front, and are distributed to the integuments 

 of the concha. 



Lastly, the superficial temporal nerve 

 emerges from the parotid gland, beneath the 

 root of the zygoma, between the condyle of 

 the jaw and the cartilaginous tube of the ear, 

 in company with the temporal artery, and 

 concealed by it : it then changes its course 

 and ascends with the artery behind the zygoma 

 and in front of the ear, upon the temple: there 

 it emerges from beneath the artery, posterior 

 to it, and divides into branches, which become 

 subcutaneous, run superficial to the fascia and 

 the artery beneath the subcutaneous cellular 

 structure, and are ultimately distributed to the 

 integument of the temple : their number is 

 two or three ; they may be distinguished into 

 anterior, middle, and posterior, and they are 

 destined to the corresponding parts of the 

 temple : they correspond in their course, but 

 by no means regularly or strictly so, to the 

 branches of the temporal artery, from which 

 they are separated by the fascia. 



Of the two terminal branches of the third 

 division, the larger one, the inferior maxil- 

 lary or dental, descends outward to the upper 

 orifice of the inferior maxillary canal. In 

 its course it passes always behind the inter- 

 nal maxillary artery, and soon glides between 

 the internal lateral ligament of the temporo- 

 maxillary articulation, and the ramus of the 

 jaw, descending in front of the anterior margin 

 of the ligament, which thus becomes interposed 

 between it and the lingual branch, and also be- 

 tween it and the internal pterygoid muscle, from 

 the pressure of which the ligament is considered 

 to protect it. In that situation it is joined by the 

 inferior dental artery, a branch of the internal 

 maxillary given off between the ligament and 

 the jaw, which accompanies it through its further 

 course. It next enters the canal, and is trans- 

 mitted through it downward, forward, and 

 inward toward the chin, beneath the sockets of 

 the teeth; having reached the termination of 

 the canal, it is reflected upward and outward 

 through the mental foramen, and escapes from 

 the canal upon the lateral and superficial surface 

 of the jaw, at either side of the chin; at its 

 exit it is beneath the second bicuspid tooth of 

 the lower jaw, and covered by the muscles of 

 the lip : it then terminates by dividing into two 



branches, called inferior labial nerves, external 

 and internal. The branches of the inferior 

 maxillary are as follow : presently after its 

 origin it gives off the branch by which the 

 lingual branch and the inferior maxillary are 

 connected, and which completes the loop 

 through which the internal maxillary artery 

 passes ; also the branch which forms a root of 

 the superficial temporal nerve. Next, imme- 

 diately before entering the dental canal, it gives 

 off a long slender branch, denominated mylo- 

 hyoid nerve; this branch descends forward and 

 inward along the inside of the ramus of the 

 jaw, between it and the internal pterygoid 

 muscle, and lodged in a groove upon the sur- 

 face of the bone, which leads in the same 

 direction, and is occasionally in part a bony 

 canal ; it is covered in the groove by a prolon- 

 gation of the internal lateral ligament, and 

 escapes from it inferiorly in front of the insertion 

 of the internal pterygoid muscle and beneath 

 the lingual branch ; it then passes beneath or 

 external to the mylohyoid muscle, between the 

 submaxillary gland and the internal surface of 

 the jaw, gains the surface of the muscle itself 

 and runs forward and inward above the super- 

 ficial portion of the gland, between it and the 

 muscle, and accompanied by the submental 

 artery; finally, it divides into a leash of branches. 

 Of these one is sometimes destined to the sub- 

 maxillary gland ; two or three are distributed 

 to the mylohyoid muscle ; another to the anterior 

 belly of the digastric, and the last passes first 

 between the anterior belly of the digastric and 

 the mylohyoid, gives filaments to the muscles 

 in its passage, then ascends upon the chin 

 internal to the belly of the digastric, and is 

 consumed in the depressor labii muscle. 



The next branches of the nerve are those 

 which are given off by it while within the 

 inferior maxillary canal : they have two desti- 

 nations, viz. the roots and periosteum of the 

 teeth and the gum of the lower jaw. During 

 its course through the canal the nerve gives off 

 several long, slender branches, which run for 

 some distance within the canal, ascend thence 

 througn the bone beneath and on either side of 

 the roots of the teeth, ramify as they proceed, 

 and distribute their ramifications to the desti- 

 nations which have been mentioned. The 

 author has never found these branches as they 

 are for the most part represented, viz. short 

 single filaments ascending almost directly into 

 the several fangs of the teeth : they are deci- 

 dedly less remarkable and less numerous in the 

 old subject after the fall of the teeth than in 

 the young. Again, at the mental foramen, anil 

 immediately before its escape from the canal, 

 the nerve gives off a more considerable branch, 

 denominated by Cruveilhier dentaire incisif, 

 which is continued through the jaw toward the 

 symphysis beneath the canine and incisor 

 teeth, and distributed to them. The former 

 set supplies the posterior molar teeth. Accord- 

 ing to the general opinion the nerves of the 

 teeth enter the fangs through the apertures 

 in their extremities, and are transmitted through 

 them into the bodies of the teeth, to be con- 

 sumed in the pulp and the structure of the 



