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KMID : 0376219870240010001
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Chonnam Medical Journal
1987 Volume.24 No. 1 p.1 ~ p.10
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Studies on the relationship between the posterior semicircular canals and the extraocular muscles in cats
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Abstract
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In order to explore detailed neural organization for vestibuloocular reflex action, it is necessary to , observe reactions of the individual extraocular muscles in response to selective excitation of the each semicircular canal. In urethane anaesthetized cats, the posterior semicircular canal was subjected. to electrical stimulation, rapid. freezing and/or lymphatic fluid flow, and the reaction of the extraocular muscles were recorded in terms of electromyographic activity and tension.
1) The superior oblique, medial rectus and superior rectus muscles were contracted by excitation of the ipsilateral canal nerve and were relaxed by the contralateral canal.
2) The inferior oblique, lateral rectus and inferior rectus muscles were contracted by excitation of the contralateral canal nerve and were relaxed by the ipsilateral canal.
3) Reactions of the extraocular muscles in response to rapid freezing or lymphatic fluid flow subjected to the posterior canal also supported the above results obtained .by electrical stimulation.
These experimental results are all in accordance with those already reported by Kim in rabbits, whereas the major portions of the results are out of accord with the observation of Cohen et al. made in cats. Theoretical consideration on the latter´s works revealed some simple and yet important contradictions involved in their results.
It has been emphasized by previous authors that the vestibuloocular relations are somewhat different between the frontal eyed cat and lateral eyed rabbit. The present experimental evidences, however, suggest that there is no room for qualitative difference in vestibuloocular relation between these two animals.
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