The autonomic nervous system / by J.N. Langley.

  • John Newport Langley
Date:
1921-
Catalogue details

Licence: In copyright

Credit: The autonomic nervous system / by J.N. Langley. Source: Wellcome Collection.

    30/96 page 18
    London.) The statement of Ranson that there are numer¬ ous non-medullated fibres in the posterior roots I shall discuss later. From these and other results Gaskell came to the important conclusion that only those nerves which had white rami sent fibres to the sympathetic system. These formed his “ thoracic outflow.” In the dog he found white rami from the 2nd thoracic to the 2nd lumbar (the 4th lumbar of most writers). The limits of the white rami will be dealt with under the section of the sympathetic system; here it is sufficient to take them as present in the dog from the 1st thoracic to about the 4th lumbar nerve. The facts described by Gaskell showed conclusively that the very great majority of the nerve fibres passing to the sympathetic arose from a limited region of the spinal cord. They were less conclusive as to the total absence of such fibres from the upper and lower regions of the cord. As evidence of total absence Gaskell relied on two ob¬ servations, first that the anterior roots of the cervical and lower lumbar nerves had no fibres less than 3.6/x in diameter. This statement is not quite accurate; there are a few fibres 2 to 3*6/x, i.e. of the size of sympathetic preganglionic fibres, in the anterior roots of the nerves having no white rami. The other point relied on was that the grey rami contained very few small medul- lated fibres. In fact, however, the grey rami of the cat and of some other animals contain a considerable number of small medullated fibres (cp. p. 24). Whether there are few or many it is impossible to follow them when undegenerated through the nerve trunk and into the roots in such way as to be certain that none arise from the spinal cord. The contradiction between the conclusion drawn
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