290 



FIFTH PAIR OF NERVES. 



the structure of the lid, and anastomoses with 

 the portio dura, lachrymal, and malar nerves, 

 as also with the internal palpebral. 



The descending or labial branches are the 

 largest and the most numerous ; for the most 

 part they are three, at times four. They de- 

 scend to the upper lip, one toward its middle, 

 the second toward its intermediate, and the 

 third toward its outer part, the commissure of 

 the lips, and are denominated internal, mid- 

 dle, and external ; they are situate, all at first, 

 beneath the levator labii superioris, between it 

 and the levator anguli oris or canine muscle; 

 as they descend, they give filaments to these 

 muscles and to the parts superficial to them ; 

 and they pass to their several destinations, the 

 internal between the levator labii and the de- 

 pressor alae nasi ; the middle between the same 

 muscles ; and the external superficial to the 

 levator anguli, and uncovered by the levator 

 labii ; as they approach the lip they divide 

 each into branches, which are distributed to 

 the structures of the part at their several situa- 

 tions ; to the orbicularis oris, and the insertions 

 of the other muscles of the lip, to the integu- 

 ment of the lip, inteinal and external, and also 

 to the labial glands ; they all communicate to- 

 gether, and with branches of the portio dura ; 

 the external more particularly with the latter, 

 as also with the neighbouring branches of the 

 fifth ; the internal with the inferior nasal ; the 

 external with the inferior labial and buccal 

 nerves. In the infraorbital region, the branches 

 of the superior maxillary are crossed by and 

 interlaced with those of the portio dura; the 

 latter running from without inward, and for the 

 most part superficial to the former ; but also 

 beneath and among them, and even forming 

 loops about them ; while the former run from 

 above downward, and are principally deeply 

 seated. In consequence of this diversity in 

 their directions and the numerous anastomoses 

 which they hold with each other, the branches 

 of the two nerves form a very intricate mesh iu 

 that region. 



In some Carnivora filaments of the facial 

 branches of the fifth nerve have been traced 

 into the bulbs of the hairs of the whiskers and 

 the tufts with which they are furnished ; this 

 is remarkably so in the seal, as described by 

 Andral : they are strongly expressed by Rapp.* 



The internal or nasal branches are, for the most 

 part, two ; they are termed superficial nasal by 

 the elder Meckel, and distinguished into supe- 

 rior and inferior; they pass, both, inward toward 

 the nose, beneath the levator labii superioris, 

 the inferior at the same time descending, and 

 having reached the side of the nostril they sub- 

 divide. 



The superior is the smaller of the two, and 

 arises frequently fr.om a branch common to it 

 and the internal inferior palpebral ; it divides 

 into three, of which the first, the uppermost, is 

 distributed to the origin of the levator labii 

 alicque nasi, to the compressor naris, and to the 

 integuments on the dorsum of the nose; the 



* Die Verrichtungcn des funfteu Hirnnerven- 



paars. 



second, the middle, to the compressor naris 

 and also to the integuments of the nostril, and 

 the third, the inferior, to the compressor naris, 

 to the depressor alae nasi, and to the integu- 

 ments of the ala. 



The inferior superficial nasal, the larger of 

 the two, first gives occasionally a branch, which 

 ascends to the eyelid ; then communicates with 

 the superior, and having reached the ala of the 

 nose, it gives off numerous ramifications which 

 are distributed to the levator and depressor alae, 

 to the integuments of the inferior part of the 

 ala, of the tip, and of the septum, and also to 

 the upper lip ; it communicates with the rami- 

 fications of the naso-lobar branch of the nasal 

 nerve, of the internal labial, and of the portio 

 dura. 



The third division of the fifth. This trunk 

 has been denominated by Winslow, on account 

 of its general distribution, the inferior maxillary 

 nerve, and it is generally known by that appel- 

 lation ; yet it appears to the writer that it 

 would have been much better had that title 

 been applied only to that portion of the nerve 

 which enters the lower jaw. Such is the 

 opinion of the elder Meckel, who observes that 

 this use of the epithet leads to the inconveni- 

 ence that the branch alluded to and the trunk 

 of the nerve may be easily confounded. It is 

 much the largest of the three divisions, and 

 differs remarkably from the other two in its 

 composition ; they are both single, and derived 

 altogether from the Gasserian ganglion; it on 

 the contrary is composed and made up of two 

 portions, one derived from the ganglion, the 

 other not connected with it ; the former is the 

 largest of the three trunks connected with the 

 ganglion ; it is attached to its posterior external 

 extremity ; at its attachment it is cineritious 

 and very wide, but as it proceeds it loses that 

 tint, and acquires a compressed cylindrical 

 form. It is situate external, posterior, and in- 

 ferior to the others, and its course within the 

 cranium is very short or none, for from the 

 ganglion it enters at once the inferior maxillary 

 or foramen ovale of the sphenoid bone, and 

 escapes from the cavity, passing downward, for- 

 ward, and outward, nearly at right angles with 

 the second division of the fifth. Before leaving 

 the cranium it is joined, as the first and second 

 divisions are, by a filament from the sympa- 

 thetic, according to Munniks, Laumonier, and 

 Bock.* 



The second portion, of which the third 

 division is composed, is the lesser packet of 

 the fifth itself; this, it has been already stated, 

 does not join the ganglion, but passing out- 

 ward, beneath that body, is united to the former 

 portion posteriorly, in the foramen ovale ; it 

 forms, however, but a small proportion of the 

 nerve, that part which is attached to the gan- 

 glion exceeding it very much in size. At its 

 junction, it is placed posterior to the other, 

 but it immediately spreads out, and increases 

 very much in width, and at the same time is 

 lapped round the inner side of the ganglionic 

 portion so as to get before it, and to form the 



* Op. cit. and Journ. Compl. 



