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.

    45/64 (page 45)
    nerves ; whether the spinal ganglia send fine fibres to their own anterior branches ; whether the fine fibres arising in the spinal cord go to the sym¬ pathetic or to the spinal nerves, or to both; and what course the fine fibres which run with the spinal nerves take, though, from the large number of them in the branches of sensitive nerves, one may conclude that they are chiefly distributed with these. As to the relative proportions of large and fine fibres in the nerves distri¬ buted to various parts, Kblliker concludes from liis own and other observa¬ tions that, 1st, the nerves of voluntary muscles contain in their trunks a ma¬ jority of large fibres, but in their peripheral distribution either only, or a majority of, fine fibres; 2d, the nerves of the skin contain (for the most part) equal numbers of both ; but in some of them, one or other size of fibres greatly preponderates, and in all of them the fine fibres greatly preponderate in their peripheral distribution; 3d, the nerves of sensitive mucous mem¬ brane are, in this respect, like those of the skin, except that in the nerves of the teeth-pulps and the gums there is a great majority of large fibres; 4th, in the nerves of involuntary muscles, and of the less sensitive or insensible mucous membranes, there is a great predominance of fine fibres. To these important conclusions respecting the general anatomy of the nerve-fibres, a few less considerable facts may still be added. Structure of the Fibres. Stadelmann* describes the axis-cylinder of the nerve-fibres as very distinctly visible in transverse sections of them. Its outline has commonly the same form, and is nearly half as large, as that of the nerve-fibre itself, but sometimes it looks like a mere chink or a central point. Hartingf has once noticed (but long after death) some peculiar fibres in the neurilemma of a nerve on the abdominal muscles of a Molge (Triton?) punc¬ tata. They were narrow, spirally twisted, band-like, with sharp outlines, and each of them had on its outer edge a row of very short cilise, which ended in minute round knobs, and were set at regular distances from one another. The average width of the fibres was about 1-1600th of an inch ; the average length of the ciliae 1-1100th; the diameter of their knobs l-2300th ; their dis¬ tance apart about 1-S00tli. Central Terminations of Nerve-fibres. Probably we must not conclude from the foregoing observations by Hannover, Kolliker, and others, that the fibres in the nerve-centres have no other mode of termination (if it may be so called) than that by connexion with the nerve-corpuscles. In the last Report, I mentioned the observations of Dr. Lonsdale,]; who found, in two cases of anen- aphalous monsters, that the nerve-fibres in the truncated portions of the fifth and other nerves, which hung unattached in the base of the skull, formed loops; a fact which seemed confirmatory of the theory of central terminal loops of the nerve-fibres in the brain. I have recently had occasion to con¬ firm this fact in a mature foetus, whose cerebro-spinal axis was truncated at the medulla oblongata. In the loose hanging ends of the fourth and fifth nerves, all the fibres appeared forming loops, exactly like those figured by Dr. Lonsdale. There can be no doubt therefore that this is the usual ar¬ rangement of the nerve-fibres in these cases, whatever may be the import of the fact. Peripheral Terminations of Nerve-fibres. In doubt concerning the terminal loops of nerve-fibres, Volkmann§ tried the experiment of dividing half the * Sectiones transversse partium corporis humani, p. 17- t Tijdschrift voor natuurl. Geschied. en Physiologic, 1845, d. xii, st. 1. In another examination he could not find these fibres. There is some similarity between this observation and that of Remak, in Muller’s Arehiv, 1841, p.39, and Valentin’s Repertorium for 1841, p. 108. x In the Edinb. Med. and Surg. Journal, No. 157. § Wagner’s Handworterbueh, art. Nervenphysiologie, p. 5G5.