PMID: 3746400Jul 1, 1986Paper

Contractile differences between muscle units in the medial rectus and lateral rectus muscles in the cat

Journal of Neurophysiology
M A Meredith, S J Goldberg

Abstract

Conjugate eye movements in the horizontal plane are accomplished by the coactivation of the medial rectus (MR) muscle of one orbit and the lateral rectus (LR) muscle of the other. While control of these excursions has been thought to be effected by identical inputs to these muscles, recent studies have demonstrated that MR motoneurons receive different inputs than LR motoneurons. This raises the question of whether the character of the muscles they control are different. The present study evaluated the contractile properties of MR and LR muscle units in the cat. Based on the mechanical aspects of their contractile properties, only two physiological types of muscle units were identified within the MR and LR muscles: twitch and non-twitch muscle units. Twitch muscle units represented over 90% of the units sampled in each muscle. Significant differences in the rate-related and the tension-related contractile properties were demonstrated between MR and LR twitch muscle units. MR muscle units exhibited significantly faster twitch contractions than did LR units. The rate of stimulation at which MR units exhibited fused tetany was significantly higher than for LR units, although units from both muscles demonstrated similar rates of ri...Continue Reading

Citations

Aug 25, 2007·Journal of Applied Physiology·Keith N BishopMary S Shall
Aug 2, 2001·Movement Disorders : Official Journal of the Movement Disorder Society·J H FalkenbergL K McLoon
Feb 15, 2019·Proceedings of the National Academy of Sciences of the United States of America·Rosendo HernándezAngel M Pastor
Aug 1, 1997·The Anatomical Record·I BilligP Buisseret
Apr 20, 1999·Biochemical and Biophysical Research Communications·J D Porter, P Karathanasis
May 1, 1995·Survey of Ophthalmology·J D PorterJ K Brueckner

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