On the mechanism of the movements of the iris / by J. N. Langley and H. K. Anderson.

  • Langley, J. N. (John Newport), 1852-1925.
Date:
[1892]
Catalogue details

Licence: Public Domain Mark

Credit: On the mechanism of the movements of the iris / by J. N. Langley and H. K. Anderson. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    made with the 3rd nerve. So much of the unstriated muscle of the body is supplied with inhibitory as well as with constrictor nerve-fibres, that there is a prima facie probability that all the unstriated muscle of the body is supplied with inhibitory nerve-fibres. Since we had failed to find inhibitory fibres for the sphincter in the cervical sympathetic, and since constrictor and inhibitory fibres often run together, it seemed to us worth while to observe carefully the action of the 3rd nerve. We have carefully stimulated the 3rd nerve in the skull with induced currents of varying strength and of varying rate, and with the direct battery current of varying strength and interrupted at varying intervals. But we have never found any other effect than constriction of the pupil, except when there were indications of escape to the 5th nerve. Summary. We append a brief abstract of the line of argument of the preceding paper, and of the chief facts dealt with in it. The other points which we have considered may be gathered from the ' contents' given at the beginning of the paper. The proofs which have been brought forward up to the present time as to the way in which the sympathetic causes dilation of the pupil are inconclusive. For a dilator muscle it has been said:— That the spincter muscle dies at a time when the cervical sympa- thetic nerve will still cause a dilation of the pupil (Budge). The rapid death of the sphincter postulated here, was shown by Brown-Sequard not to occur. That the occurrence of a local dilation of the pupil (Bernstein and Dogiel, Engelhardt, Jegorow) shows the presence of a radial muscle. It might however, be produced by local contraction of blood vessels, or by local inhibition of the sphincter muscle. That dilation of the pupil in the rabbits may be obtained after removal of the sphincter (Kolliker). But this might be due to a contraction of the blood vessels of the iris, or possibly to a mechanical bulging of the lens. Against a dilator muscle it has been urged:— That the ciliary portion of the iris does not contract with warmth like the sphincter portion; (Samkowy and Grunhagen). This is true but the difference is only one of degree.