824 THE NERVES. 



found it divided into three small masses, connected with each other by numerous 

 filaments of a deep grey colour, and free from all connection with the spheno- 

 palatine nerve. The small posterior mass in this case received the Vidian nerve 

 and the sensitive roots from the fifth pair. The distribution of the emergent 

 branches was unaltered. 



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

 ganglion, we may remark that the staphyline, or posterior palatine, nerve derives 

 from it the motor property which permits it to cause contraction of the muscles 

 in the soft palate. 



3. Otic or Arnold's Ganglion. — It appears to us that the presence of 

 this gangUon is not constant ; for we have sometimes found it replaced by a small 

 plexus, provided with some ahnost microscopic ganghonic granules. 



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

 within the origin of the inferior maxillary nerve, beneath the insertion 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 that are so short and 

 thick, that we might imagine it to be fused on that trunk. 



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

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

 From the sympathetic ramuscule accompanying the internal maxillary artery, it 

 receives \i^ filament of communication with the superior cervical gangUon. 



Among its efferent 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 for the pterygoid muscles, the 

 Eustachian tube, and the tensor and levator palati muscles. 



PHYSiOLoaiCAL R6suMi6 OF THE FiFTH Pair. — The trigeminus conveys 

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

 the nasal fossae and sinuses, the nostrils, the greater portion of the tongue, the 

 saUvary 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 produces contraction of the 

 muscles that bring the jaws into apposition — all those composing the masseteric 

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

 this 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. Moussu believes he has experimentally proved 

 that the excito-secretory fibres of the inferior molar and the parotid gland— in the 

 Horse and Ruminants — proceed from the fifth pair, and not from the facial nerve.^ 



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

 trigeminus ramifies depends upon this nerve. 



' He says, with regard to the Horse : " The excito-secretory nerve of the parotid can be 

 isolated from the Gaeserian ganglion. It is composed of from four to five filaments, which lie 

 beside either the subzygomatic or the inferior maxillary nerve for a very short distance; then 

 it is placed on the surface of the guttural pouch, and reaches the posterior border of the inferior 

 maxilla and internal maxillary vein, to enter the parotid gland." 



