Such also is the opinion of J. F. Heckel,* according to whom the nerve " passes under the posterior peduncle of the cerebellum, along the outer side of the pons, toward the groove between the olivary and restiform bo dies, where it arises in part from the groove and in part from the olivary eminences." Cloquet likewise states the nerve to arise between the olivary and restiform bodies, and has adopted and copied, in his late work,/ the view given of its origin by Gall and Spurz heim. Further, the discovery of this origin of the nerve has been attributed by Aleckel§ and others to Santorini.
It is a hardy thing to contradict such au thorities as have been quoted, and the influence which they justly carry with them has made the author hesitate before adopting a contrary opinion ; but if reference be made to the workll of Santorini on the point, it will be found that he nowhere, in his account of the origin of the nerve, assigns the groove between the restiform and olivary bodies as its situation in the spinal bulb, as will appear from the following extract, the only paragraph of his account in which he particularizes it, and in which lie supposes it to be situate between the olivary and pyramidal bodies : " Unde in interiorem medullae ob longatm caudicem conjectus, fere inter olivaria et pyramidalia corpora locatus, quo demurn pergat, cum tenuium fibrarum implexus, tum earumdem mollitudo, neconsequerer, omnino prohibuere ;" from which it is plain, as has been stated, that he supposed the nerve to be between the two latter bodies ; and also that he had not been able to trace it to any particular destination, although, in a succeeding para graph, he conjectures the olivary body to be its source : hence there is reason to conclude that succeeding anatomists have assumed his conjecture to be an established fact, and have modelled their accounts and representations accordingly. Moreover, since the olivary bodies do not exist in the lower classes of animals, it is not likely that they should be points of origin or attachment for nerves ; in fine, the author has so uniformly succeeded in tracing the nerve to the destination which has been described, that he is satisfied of the accuracy of it, in which he is confirmed by the fact that the account here given accords with the opinions of Santorini, Ssemmerring, and Rolando, so far as that of the first has been determined to be accurate, or as those of the others extend: the particulars in which it differs from, or rather in which it goes beyond these, rest upon the author's authority and remain to be confirmed, the attachment of the two packets to the same point, the existence of the eminence at the inser tion, and that of a cord of communication with the anterior column of the spinal marrow.
The encephalic connections of the nerve, as detailed, are corroborated by those to be observed in inferior animals. In those Mam malia in which the pons is but little deve loped, the nerve is attached between that part and the trapezium; in those instances in which the pons is more so, the nerve is attached, superficially, not actually behind that part, but near to its posterior margin ; with little trouble it can be followed to the back of the pons, where it is attached, as in Man, to the medulla oblongata, the point of attachment presenting here also, after the separation of the adjoining matter, the appearance of an emi nence or tubercle, from whence a cord de scends beneath the trapezium into the lateral column of the spinal bulb. This cord is of great size in many animals; and in some can be seen distinctly, without dissection, upon the surface of the spinal bulb, in consequence of the degree to which it projects : it is well expressed in the delineation of the brain of the calf in the third plate of Gall and Spurzheim, and in that of the brain of the horse in fig. 275 of M. Serres' Illustrations of the Comparative Anatomy of the Brain.
In Birds, Reptiles, and Fish, neither porn, trapezium, nor olivary bodies exist, and the nerve is attached to the lateral part of the spinal bulb at its superior or anterior extremity, and to its lateral column—the prolongation of the superior column of the spinal cord. In all three the point of attachment is situate a little way from the back of the bulb and be neath the floor of the ventricle, the cineritious stratum, of which the latter consists, being directly connected to the back of the nerve. In Birds (jig.142) the continuation of the nerve can be traced downward along the side of the bulb toward the spinal cord, and without diffi culty, inasmuch as it is superficial and is not crossed by a trapezium, as in the Mammalia.