Yoke muscle of right lateral rectus is
Correct Answer: Left medial rectus
Description: (A) Left medial rectus[?]Yoke muscle (contra-lateral synergists):Reference to muscles which are primary muscles (one from each eye) that accomplish (contract) a given version.YOKE MUSCLES IN CARDINAL POSITIONS OF GAZE* Eyes up & rightRSR & LIO* Eyes up & leftLSR & RIO* Eyes rightRLR & LMR* Eyes leftLLR & RMR* Eyes down & rightRIR & LSO* Eyes down & leftLIR & RSOContralaterally paired extra-ocular muscles that work synergistically to direct the gaze in a given direction.For example, in directing the gaze to the right, the right lateral rectus and left medial rectus operate together as yoke muscles. ACTION OF EXTRA-OCULAR MUSCLESBeing approximately horizontal, when the visual axis is in its primary position, i.e. directed to the horizon, they rotate the eye medially (adduction) or laterally (abduction) about an imaginary vertical axis.They are antagonists.Visual axis can be swept through a horizontal arc by reciprocal adjustment of their lengths.When, as is usual, both eyes are involved, the medial & lateral recti of each eye either can adjust both visual axes in a conjugate movement from point to point at infinity (their axes remaining parallel), or they can converge or diverge the axes to or from nearer or more distant objects of attention in the visual field.Medial & lateral recti do not rotate the eye around its horizontal axis and so cannot elevate or depress the visual axes as gaze is transferred from nearer to more distant objects or the reverse.Normally, movements of the two eyes are harmoniously coordinated.Such coordinated movements of both eyes are called conjugate ocular movements.Conjugate movements are usually horizontal or vertical, but oblique conjugate movements may also occur.Dissociated movements of the two eyes are known as disjunctive movements (skew deviation).Levator palpebrae superioris elevates the upper lid, & its antagonist is the palpebral part of orbicularis oculi.
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