A case of permanent conjugate deviation of the eyes and head, the result of a lesion limited to the sixth nucleus : with remarks on associated lateral movements of the eyeballs, and rotation of the head and neck / by A. Hughes Bennett and Thomas Savill.

  • Alexander Hughes Bennett
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: A case of permanent conjugate deviation of the eyes and head, the result of a lesion limited to the sixth nucleus : with remarks on associated lateral movements of the eyeballs, and rotation of the head and neck / by A. Hughes Bennett and Thomas Savill. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    A. Cortex Cerebri; a. Voluntory tract from cortex to cervical ganglia ; b. Ditto to eleventh nucleus ; c. Ditto to sixth nucleus ; d. Ditto to third nucleus ; B. Decussation of voluntary motor tracts in pons and medulla ; III. Third nucleus; VI. Sixth nucleus; XI. Eleventh nucleus ; XIII. Upper cervical ganglia; e. Motor fibres from sixth nucleus to external rectus ; /. Crossed tract between third and sixth nuclei; g. Motor fibres from third nucleus to internal rectus; h. Afferent tract from retina to sixth nucleus ; i. Afferent tract from ear to sixth nucleus ; j. Communicat- ing tract between sixth nucleus and cervical ganglia on the same side ; k, Motor nerve from cervical ganglia to flexors of neck ; I. Crossed tract between sixth and eleventh nuclei of opposite sides ; vi. Motor nerve from eleventh nucleus to sterno-mastoid muscle. may be paralysed, it does not follow that they lose their function for other purposes. Here for example the internal rectus of one eye was inactive to either the voluntary or reflex impulse of conjugate movement, yet it acted normally when the other eye was closed, and to convergent require- ments. In short, this muscle was only cut off from the motor impulses derived from the sixth nucleus, while those connecting it with the third nucleus remained intact (Fig. 2). Therefore all the movements of the right eye were normal except during the act of conjugation, when the internal rectus was immovable. The external rectus of the left eye, on the other hand, was completely and permanently paralysed for all purposes, whether voluntary or reflex, for reasons which the preceding argument must have made obvious. Although conjugate movements may be of purely reflex production, the same physiological condition may be ac- complished as a voluntary act. Impulses from the cortex in connection with the pontine centres are capable of causing the eyeballs to move to the right or left at will. The posterior portion of the frontal convolutions are beheved by Ferrier to be the area in which these origi- nate, and both experiment and clinical observation seem to indicate this as the most probable region. Grasset and others beheve the angular gyrus and its neighbourhood to be the seat of this process. Whatever the exact area may be, there can be Httle doubt that conjugate movements of the eyeballs have a definite localisation in the cerebral cortex, as is abundantly shown by experimental and clinical observation. This cortical centre is connected with the
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