720 THE NERVES. 



Among the anatomo-physiological facts pertaining to the study of this 

 ganglion, we may remark that the staphylin, or posterior palatine, nerve 

 derives from it the motor property which permits it to excite the con- 

 traction of the muscles in the soft palate. 



3. OTIC (OR ARNOLD'S) GANGLION. It appears to us that the presence 

 of this ganglion is not constant, for we have sometimes found it replaced 

 by a small plexus provided with some almost microscopic ganglionic 

 granulations. 



When it does exist, it presents itself as a small fusiform enlargement 

 placed within the origin of the inferior maxillary nerve, beneath the inser- 

 tion of the Eustachian tube. To discover it, we have only to look for the 

 commencement of the buccal nerve, to which it is joined by some filaments 

 which are so short and thick, that we might imagine it to be fixed on that 

 trunk. 



Its sensitive roots are represented by the preceding filaments. The small 

 superficial petrous nerve, coming from the facial, constitutes its motor root. 

 From the sympathetic ramuscule accompanying the internal maxillary 

 artery, it receives its filament of communication with the superior cervical 

 ganglion. 



Among its emergent ramuscules must be cited a superior filament, which 

 enters the petrous portion of the temporal bone to disappear in the internal 

 muscle of the malleus (tensor tympani), and two inferior filaments of a 

 more considerable volume which separate in numerous ramuscules destined 

 to the pterygoid muscles, the Eustachian tube, and the tensor palati 

 muscle. 



PHYSIOLOGICAL RESUME OP THE FIFTH PAIR. The trigemini convey 

 sensation to the skin covering the head, into the eyelids, the soft and hard 

 palate, the nasal fossse and sinuses, the nostrils, the greater portion of the 

 tongue, and into the salivary glands and cheeks, and the upper and lower lips. 

 The enormous tuft formed by the terminal branches of the superior 

 maxillary nerve, endow the upper lip with the attributes of an organ of very 

 exquisite tact. 



The gustatory branch is,' for the anterior two-thirds of the tongue, the 

 essential instrument of the sense of taste. 



By its motor root, the inferior maxillary nerve provokes the contraction 

 of the muscles that bring the jaws into apposition all those composing the 

 raasseteric region, except the digastricus. This root is often designated, in 

 consequence of its function, the masticatory nerve. 



The fifth pair also influences, as is demonstrated by vivisections and the 

 observation of pathological facts, the secretion of the mucous membranes 

 and glands receiving its filaments: undoubtedly by a reflex action which 

 proceeds from the isthmus, and perhaps from the Gasserian ganglion. 



Finally, it is admitted that the nutrition of the tissues in which the 

 trigeminus ramifies depends upon that nerve. But here there is an exagge- 

 ration; for if nutrition be modified in these tissues, consequent on the 

 section of the fifth pair, this effect is certainly due to paralysis of the 

 capillaries, whose contractility is probably excited by the organic motor 

 fibres mixed with the sensitive filaments of the fifth pair. 



The ramuscules sent by the sympathetic chain to the Gasserian ganglion, 

 are perhaps not foreign to the part the fifth pair seems to play in the 

 secretory and nutritive functions. 



