Report on the progress of human anatomy and physiology in the year 1844-5 / [Sir James Paget].

  • James Paget
Date:
1846
Catalogue details

Licence: Public Domain Mark

Credit: Report on the progress of human anatomy and physiology in the year 1844-5 / [Sir James Paget]. Source: Wellcome Collection.

    53/64 (page 53)
    Dr. Morganti* has published a long and important monograph on the facial nerve. He insists on the distinction of its two roots, reckoning as one the small fasciculus, the portio intermedia of Wrisberg. He traces, as Malacarne did, the principal root into the substance of the medulla oblongata, in which it at once divides into two fasciculi, one ascending, the other transverse. The first of these fasciculi is composed of longitudinal fibres, which seem to descend from the lateral tract of the medulla oblongata into the nerve; the second, or transverse, is composed of more numerous fibres, and looks like the continua¬ tion of the principal root of the nerve; it passes through the substance of the lateral tract, and is directed to its posterior surface, towards the median line of the floor of the fourth ventricle, where it meets its fellow of the opposite side, and is covered by the expanded gray substance of the cord. The smaller root, or portio intermedia, may be traced to the external part of the posterior [restiform ?] tract of the medulla oblongata, in which it con¬ nects itself with the filaments of the vestibular branch of the auditory nerve, arising from the substance of the restiform body, where it combines to form the crus cerebelli. By the aid of nitric acid and very careful dissection, Morganti has unravel¬ led the communication between the trunk of the facial, this portio intermedia, and the vestibular division of the auditory nerve. The portio intermedia gives off a small branch, which unites with one from the vestibular, and in union with it enters the vestibular nerve. Then, next, it gives off two slender branches, which join the chief trunk of the facial, and cannot be traced further. Then an appearance of a plexus is produced by a branch being given off from this chief trunk, which branch crosses in front of the portio intermedia, and then winds behind it, looking just as if it were given to the portio intermedia and to the geniculate ganglion, but really passing them and rejoining the trunk. By separating this branch, it is shown that the geniculate ganglion is formed exclusively on the fibres of the portio intermedia, and has only a connexion of contiguity with the trunk of the facial. Further, it appears that the geniculate ganglion gives origin—1st, to the superficial petrosal nerves, (to the greater of which is added a small branch or two from the trunk of the facial); and, 2d, to two or three descending branches. These descending branches appear to join the knee-shaped bend of the trunk of the facial, but being unravelled they separate into—1st, numerous small branches forming a kind of plexus and then joining the main trunk of the facial; and, 2d, the chorda tympani, which the author holds, is thus formed from the portio inter¬ media, with the addition of one or two small branches from the trunk of the facial. The author confirms this account by evidence from comparative anatomy; and he draws from the whole the conclusion that the geniculate ganglion (for the truly ganglionic nature of which he gives sufficient proofs) is to be classed with the ganglia on the posterior roots of the spinal nerves. In accordance with this view also, he holds that the facial is a mixed or double-rooted nerve, analogous to the fifth and spinal nerves; that the trunk (as it is here called) is its anterior root, and the portio intermedia its posterior root; that the su¬ perficial petrosal nerves are mixed branches, chiefly composed of fibres going from the facial to the spheno-palatine and otic ganglia ; the chorda tympani, a mixed branch from the facial to the lingual branch of the fifth ; and that, after the formation of the geniculate ganglion, the trunk and branches of the facial contain both sensitive and motor fibres continued from its roots. The author opposes, in detail, all the objections to these views ; and in an¬ swer to the belief that the trunk of the facial is insensible till it is joined by branches from the pneumogastrie and fifth, and that, the chorda tympani is # Annali Universali di Medicina; Giugno, 1845.