This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ocular Motility, Subject name: Ophthalmology
[{'content': 'All are actions of superior oblique except: \nSelect and explain. \nA. Extorsion, B. Intorsion, C. Lateral rotation, D. Downward movement', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: a (Extorsion) Ref:Khorana, 4th ed, p. 315All are actions of superior oblique except extorsion which is the primary action of the inferior obliqueAction of extraocular musclesMusclePrimary actionSecondary actionTertiary actionMRAdduction LRAbduction SRElevationIntorsionAdductionIRDepressionExtorsionAdductionSOIntorsionDepressionAbduction10ExtorsionElevationAbduction Some useful mnemonics:All superiors are intorters. So inferiors are extortersAll recti are adductors. So obliques are abductorsRegarding nerve supply: Remaining all including levator palpabrae superioris by 3rd nerve.', 'role': 'assistant'}]