Copy 1, Volume 3

The study of medicine / By John Mason Good ... Improved from the author's manuscripts, and by reference to the latest advances in physiology, pathology, and practice.

  • Good, John Mason, 1764-1827.
Date:
1840
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Licence: Public Domain Mark

Credit: The study of medicine / By John Mason Good ... Improved from the author's manuscripts, and by reference to the latest advances in physiology, pathology, and practice. Source: Wellcome Collection.

    11/506 (page 5)
    nodule, usually flattened, of an oval or circular shape, and of a reddish gray colour, which is found either on the trunk of a single nerve, or where two or more branches coalesce. Sir Charles Bell’s opinion respecting the ganglions will be presently noticed. Scarpa supposes, that a ganglion is but a bed of gelatinous membrane, in which the smallest fibrils of the nerves are arranged in new com- binations. Others believe, that nervous filaments originate in the gray matter of ganglions.*] As the brain consists of three general divisions, it might, at first sight, be supposed that each of these is allotted to some distinct purpose ; as, for example, that of forming the seat of intellect or thinking; the seat of the local senses of sight, sound, taste, and smell, and the seat of general feeling or motivity. The investi- gations and experiments of Sir Charles Bell, and M. Magendie, to which we shall presently advert, pave the way to some import- ant doctrines in respect to a few of these points, but leave us quite in the dark with respect to various others; and particularly as to the source of intellect; while it is difficult to reconcile even the doctrines which have been thus fairly deduced, with the motific, and even with the sentient powers that must exist in numerous cases of an extensive disorganisation of the brain, and in acephalous animals. The first and second nerves and the portio mollis of the seventh sufficiently attest their exclusive uses as nerves of the special senses ; while the distribution of the greater part of the third, of the fourth, and of the sixth nerves f to voluntary muscles, which receive filaments from no other source, prove clearly, that these nerves are voluntary nerves, as well as conducive to mus- cular sensation. “ Perhaps,” says Mr. Mayo, “ it is not unfair to argue analogically from the preceding instances, that the same surface of the brain or spinal chord furnishes to each voluntary muscle of the body its voluntary and sentient nerves, if the two are not identical.” \ There is in like manner reason for believing, that the fifth nerve, which, at its origin, consists of two portions, is not only a nerve, of voluntary motion, but furnishes branches to the special senses, and even communicates general sensation to the muscular fibres; and that its gustatory twig is a nerve of both touch and taste at the same time. § Class IV. I. Nature of the brain, its ramifications and substitutes. Reason of the division of the brain into dis- tinct compart- ments not clearly known. The same nerve seems at times subservient to different pur- poses, or dif- ferent nerves to the same purpose. * Mayo’s Outlines of Physiology, p. 324. 2d edit. t A is a remark, made by Sir Charles Bell, that the principles and facts un- folded in his views of the nervous system, lead us to understand the “ use of all the intricate nerves of the body, with the exception of the sixth. The sixth nerve stands connected with another system of nerves altogether; I mean the system hitherto called the sympathetic, or sometimes the ganglionic system of nerves ; and of this system we know so little, that it cannot be matter of surprise if we reason ignorantly of the connection of the sixth with it.” Natural System of the Nerves of the Human Body, p. 64. — Ed. | Anatomical and Physiological Commentaries, No. ii. p. 1. 8vo. Lond. 1822. The fact of the same nerve seeming to answer both for motion and sens- ation, is accounted for by the important discoveries of Sir Charles Bell and M. Magendie. Mr. Mayo’s experiments and arguments tend to prove, that “ the ganglionless portion of the fifth, and the hard portion of the seventh nerve, are voluntary nerves to parts, which receive sentient nerves from the larger or %ang- ionic portion of the fifth.” By the expression sentient nerves, Mr. Mayo means t ose, the division of which is followed by instantaneous loss of sensation in a part; by voluntary nerves, he means those upon the division of which the will ceases to influence the muscles they supply. Outlines, Sec. p. 331, &c. — Ed. B 3