718 THE NERVES. 



of the great sympathetic nerve, in reality belong to the special system 

 formed by that nervous chain, as they possess the formation and properties 

 of the other ganglia composing it. It is therefore necessary that we should 

 have a motive sufficiently powerful to induce us to move them from their 

 natural category, and mix up their description with a nerve so different to 

 them in its nature and functions. This motive we find in the intimate 

 relations of contiguity and continuity which these ganglia manifest towards 

 the branches of the trigemini ; in the fact that we sometimes find them united 

 to these branches, and deeply mixed up with their fibres ; and also because, 

 in certain cases, they seem to disappear entirely, and then their filaments 

 of emission or reception are directly received or emitted by the fifth pair. 



The study we are about to undertake of each of the ganglia will fully 

 justify what we have advanced. We will precede it by a few words of 

 introduction as to the general facts relating to these small organs. 



The number of sympathetic ganglia annexed to the fifth pair is suscep- 

 tible of variation, not only in different species, but also with individuals 

 of the same species. 



In the domesticated mammifers, we somewhat constantly, though not in- 

 variably, find three principal, placed on the course of tlie branches ema- 

 nating from the Gasserian ganglion. These are : 1, The opTiihalmic ganglion, 

 belonging to the nerve of the same name ; 2, The spheno-palatine ganglion, 

 annexed to the superior maxillary branch ; 3, The otic ganglion, which lies 

 beside the inferior maxillary nerve. Anatomists describe other two, the 

 submaxillary ganglion and the naso-palatine (or Cloquei's) ganglion ; but. 

 their presence is not always constant in Solipeds, and their existence in the 

 other domesticated animals is at least problematical. 



These small bodies possess those common characters which have been 

 so clearly indicated by Longet, and to which we will briefiy refer. All 

 are in communication with the superior cervical ganglion by one or more 

 generally very slender filaments, and all receive one or more ramuscules 

 from a sensitive and a motor nerve : these ramuscules— the afferent branches 

 of the ganglia— are considered as their roots. All, finally, emit from their 

 periphery a more or less considerable number of emergent branches or ramifi- 

 cations which share the properties, more or less modified, of the two orders 

 of roots. The description of each ganglion therefore includes, indepen- 

 dently of its form, situation, etc., an indication of all these ramuscules : 

 ramuscules of communication with the superior cervical ganglion ; afferent 

 ramuscules or roots ; and emergent ramuscules. This rule can be applied to 

 all the ganglia, and renders their study perfectly methodical. 



1. Ophthalmic (Ciliary or Lenticular) Ganglion. — This ganglion 

 is readily discovered, as it is always in contact with the common oculo- 

 motor nerve, and united to it near the point where the branch passing to 

 the inferior oblique muscle arises. It rarely exceeds the volume of a grain 

 of millet, and is sometimes so minute that it would altogether escape ob- 

 servation, did we not know exactly where to look for it. 



Its motor root is generally formed of two very short ramuscules coming 

 from the third pair. Its sensitive root, much longer, proceeds from the 

 palpebro-nasal nerve ; it is usually through the medium of this root that 

 the ophthalmic ganglion communicates with the superior cervical ganglion, 

 by means of a thin filament it receives from the cavernous plexus. 



The emergent filaments leave the anterior part of the ganglion, and 

 arrange themselves in a flexuous manner around the optic nerve to reach 

 the sclerotica, bearing the name of ciliary nerves. Some emanate directly 



