550 



SEVENTH PAIR OF NERVES. 



.spheno-palatine, and the lesser (z) to the otic 

 ganglion : the first of these Morganti has de- 

 picted receiving a filament (A-), which comes 

 from the facial, and in its course to the pe- 

 trosal nerve passes over the ganglion without 

 joining it. The second or lesser of the two 

 appears to be derived solely from the ganglion. 

 3. A large branch (?) which forms the great 

 bulk of the chorda tympani ; but, in order to 

 this, is also joined by one or two filaments (w) 

 from the facial nerve, which accompanies it in 

 the Fallopian canal. 4. Branches (/) which 

 passing downwards are lost in the trunk of 

 the portio dura. 



The annexed diagram, (j%. 405.) with the 

 letters attached to it, will assist the reader in 

 following this otherwise intricate description. 

 It is taken from a drawing by Morganti in 

 the essay referred to ; but it has been reduced 

 in size and simplified, so as better to allow 

 of its introduction here. 



The same author has examined into the 

 comparative anatomy of the ganglion and the 

 nerves connected with it in many of the 

 other mammalia, as the dog, calf, lamb, mule, 

 and dormouse. 



The general results of these examinations 

 abundantly verify his description of the ar- 

 rangement in the human subject. Indeed, 

 these animals offer by far the most favourable 

 subjects for exemplifying the truth of the 

 preceding description, being, as Morganti 

 remarks, natural preparations of these parts. 

 Not only is the dense and intimately adherent 

 sheath of fibrous tissue, which is present in 

 man, much looser in the ganglion and nerves 

 of these animals, but the position of this body 

 with respect to the nerve is considerably 

 altered. The much less marked anterior 

 bend of their portio dura occurs at some 

 little distance from the hiatus Fallopii ; and 

 the ganglion, which is in immediate proximity 

 to this aperture, is thus no longer geniculate 

 in its position, being removed from the knee 

 of the facial. Hence it is, as it were, out of 

 the way of the facial branches, and ceases to 

 be entangled amongst them, as in the human 

 subject. 



The author of this article can bear testi- 

 mony to the accuracy of these statements; 

 indeed, any one may easily verify them for 

 himself, in most of these animals, with scarcely 

 more trouble than removing the brain and 

 osseous roof of the Fallopian canal, and then 

 stripping off the comparatively lax neuri- 

 lemma from the subjacent ganglion and 

 nerves. The accompanying sketch (fig. 406.) 

 was taken from the left side of a sheep's head. 

 With as little artificial separation as possible, 

 it represents the arrangement of the ganglion 

 and nerves in situ, especially the manner in 

 which the trunk of the portio intermedia 

 crosses the facial nerve without joining it, 

 and the apposition or proximity, without 

 mingling, of the ganglion and the latter nerve. 



The varieties of arrangement which obtain 

 in the different animals whose nerves Mor- 

 ganti examined, are chiefly, as might be 

 expected, differences in the degree of inter- 



lacement of the adjacent nerves. In parti- 

 cular, that of the portio intermedia with the 



Fig. 406. 



Auditory, Facial, and Intermediate Nerves of a Sheep 

 as seen in situ. Magnified about 2J diameters. 



a, portio dura ; b, portio intermedia ; c, portio 

 mollis ; e, origin of the superficial petrosal nerves ; 

 /, chorda tympani ; g, geniculate ganglion. 



vestibular nerve is sometimes so complete 

 and intricate, as to render it in such instances 

 difficult to ascertain from their examination 

 only, whether the former of these nerves 

 gives branches to the latter, or, vice versa, 

 this to that. In the mule, he exhibits a fila- 

 ment from the facial to the ganglion ; but 

 thinks this a possible restitution of one or 

 both of the two previously given to it by the 

 portio intermedia. 



The general anatomical conclusion to be 

 drawn from these details is, that the facial 

 nerve as implying in this term both the 

 portio dura and the portio intermedia 

 arises by two roots. Upon the smaller of 

 these a ganglion is formed, while the latter is 

 entirely devoid of such a structure. The 

 branches of the facial nerve in the Fallopian 

 canal are mixed nerves, being formed partly 

 by filaments from the ganglion ; partly also 

 by filaments from the aganglionic root ; the 

 latter being in considerably lesser numbers. 

 And the trunk of the facial itself, beyond the 

 ganglion, is also a mixed nerve, since, although 

 by far the greater part of its bulk consists of 

 fibres from the greater root, yet it also con- 

 tains one or two filaments which come from 

 the ganglion. The analogy of this arrange- 

 ment to that of the spinal nerves is sufficiently 

 obvious, and will be hereafter again re- 

 ferred to. 



It deserves to be mentioned in this place, 

 that many other accounts of the arrangement 

 of these nerves might easily have been added 

 from various authors, but that all of them are 

 more or less at variance, both with the above 

 description by Morganti, and with each other. 

 It has seemed fit, however, to assign these a 

 very subordinate position in the present short 

 article, since the verification of a ganglion 

 belonging exclusively to the portio intermedia 

 includes not only the denial, but I think we 

 may add the disproof, of many of these 

 descriptions. So far as our knowledge of the 

 structure of ganglia at present extends, and 

 whether the late brilliant researches of Ru- 

 dolph Wagner* apply universally or not, we 

 are at least justified in viewing with great 



* Handwb'rterbuch der Physiologic. Sieben- 

 zehnte Lieferung. Artikel " Sympathi?cher Nerv 

 Ganglienstruktur und Nervenendigung." 



