The involuntary nervous system / by Walter Holbrook Gaskell.

  • W. H. Gaskell
Date:
1916
Catalogue details

Licence: In copyright

Credit: The involuntary nervous system / by Walter Holbrook Gaskell. Source: Wellcome Collection.

    17/200 page 1
    THE HISTORY OF THE INVOLUNTARY NERVOUS SYSTEM. The muscular tissue of the body is divisible into two well- marked groups, the voluntary muscles and the involuntary muscles; terms which in themselves imply a distinction between the nervous arrangements connected with these two groups of muscles. We may therefore look upon the nervous system as composed of two parts, the one connected with the movements of voluntary muscles, and the other with those of involuntary muscles. The former part may be termed shortly the voluntary nervous system; and the latter, the involuntary nervous system. Our knowledge of the methods, by which sensory stimuli are converted into action, is chiefly based upon investigations of the voluntary nervous system; and has led to the conception that the nervous system is built up of a series of neurons, through which all the complicated movements can be effected. In the vertebrate a reflex action in the spinal cord is caused by a sensory stimulus, which travels from the periphery along a sensory nerve to a nerve cell in the ganglion on a posterior root, and thence by a root fibre to make communication with some cell or cells in the central nervous system itself This primary or sensory neuron has been called the receptor element, and its parts consist of a sensory nerve cell, a sensory nerve fibre and a sensory root fibre; the last is not confined to its own segment in the cord, but communicates with other segments, some near, some far away. In all cases these root fibres ultimately make connexion with another neuron. In the simplest case this other neuron may consist of a motor cell with dendrites and with an axon which goes direct to the muscles and forms its motor nerve fibre. This neuron has been called the excitor element. However, in most cases, possibly in all, the receptor element does not connect directly with the excitor element, but an intermediate neuron in I
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