Selected monographs on dermatology / Unna, Nielsen, Duhring, Bronson, Blanc, Berger, Prince-Morrow.

  • New Sydenham Society.
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: Selected monographs on dermatology / Unna, Nielsen, Duhring, Bronson, Blanc, Berger, Prince-Morrow. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    26/636 (page 12)
    alternative—by which all hyperaernias, without distinction, are attributed, either to a paralysis of the vaso-motor nerves, or to an irritation of the inhibitory (dilator) nerves—to definite pathological pictures of the so various clinical ano- malies of the cutaneous circulation, we must shortly review the physiological experiments which have led to the doctrines current to-day on the normal circulation of the skin. These experiments justify the diagram given above. Ostroumoff's observations1 showed that tetanising the newly-cut nerve produced with certainty great arterial con- striction and lowering of temperature (by the tract m—g—a). The inhibitory (dilator) nerves, on the other hand, were chiefly affected by weak stimulation, by rythmic stimulation at intervals of five seconds, and by strong tetanic stimula- tion when the vaso-constrictors were already dead (on the fourth day for the sciatic). In all these instances, hyperemia, with rise of temperature, resulted, i. e. not only a removal of the tonic influence (by the path m—g—a) of the vaso-motor centre, but also an inhibition (m g) of the spontaneous action (by the path g—a) of the vascular ganglia, and hence a maximum dilatation. The nature of the conditions justifies the conclusion that the dilatation is not due to an independent muscular action of the artery (Exner), but to an inhibition of all vaso-constricting influences at the peripheral ganglion, which is the point best suited for this purpose. For, with this assumption, we can understand how it is that weak stimuli produce an effect so prodigious as the removal of the contraction of the strong circular muscular fibres of the arteries ; further, that rhythmic, i. e. cell stimuli, are par- ticularly effective; and that after commencing degeneration •of the vaso-motors a still further dilatation must ensue, since now by strong stimulation of the inhibitory fibres, which probably degenerate just as quickly, only inhibitory impulses can be started in the ganglia. By mapping out the path m to a in the way shown in the diagram, we avoid having to assume two different kinds of nerves with antagonistic muscle apparatus in the artery, for which the histology of the cutaneous vessels gives us no warrant. Neither do we 1 Experiments on the Inhibitory Nerves of Cutaneous Vessels, ' Pfliiger's Archiv,' 1876, p. 219.