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KMID : 0376219870240020269
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Chonnam Medical Journal
1987 Volume.24 No. 2 p.269 ~ p.279
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Functional Interrelationship between Posterior Semicircular Canals and Ocular Rectus Muscles in Cats
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Abstract
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In urethane anaesthetized cats, a posterior semicircular canal nerve was subjected to electrical stimulation by means of a fine monopolar electrode introduced into the canal ampulla, and reflex responses of the extraocular muscles were recorded in terms of changes in isometric tension and electro￢myographic activities. The experimental results revealed obvious functional interrelationship between the posterior canals and the extraocular rectus muscles in this animal.
1) Electrical stimulation of a unilateral posterior canal nerve evoked con￢traction of superior rectus muscle and relaxation of inferior rectus muscle in the ipsilateral eye.
2) Stimulation of a posterior canal nerve elicited contraction of the superior rectus in the homolateral eye and relaxation of the synonymous muscle in the contralateral eye, and relaxation of the inferior rectus in the homolateral eye and contraction of the synonymous muscle in the contralateral eye.
3) Stimulation of a posterior canal nerve caused simultaneous contraction of the homolateral medial rectus and contralateral lateral rectus muscles, and reciprocal responses of the bilateral medial rectus muscles, contraction of the homolateral and relaxation of the contralateral medial rectus.
4) Stimulation of a posterior canal nerve evoked, contraction of superior oblique and relaxation of inferior oblique muscles in the homolateral eye, and relaxation of superior oblique and contraction of inferior oblique muscles in the contralateral eye.
5) Stimulation of a unilateral posterior canal nerve elicited simultaneous contraction of the supero-medial muscle group(superior rectus, medial rectus and superior oblique muscles) and relaxation of the infero-lateral muscle group (inferior rectus, lateral rectus and inferior oblique muscles) in the homolateral eye. Stimulation of the same canal nerve elicited reversed responses of the two muscle groups in the contralateral eye.
Based on the experimental results listed above, a simple axiom is proposed as following; excitation of a unilateral posterior canal elicites contraction of the supero-medial muscle group and relaxation of the infero-lateral muscle group in the homolateral eye, and relaxation of the supero-medial muscle group and contraction of the infero-lateral muscle group in the contralateral eye.
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