This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Ophthalmology
[{'content': 'Muscle not paralysed in retrobulbar block- \nSelect and explain. \nA. Superior oblique, B. Lateral rectus, C. Superior rectus, D. Medial rectus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: *A retrobulbar block is a regional anaesthetic nerve block in the retrobulbar space, the area located behind the globe of the eye. Injection of local anaesthetic into this space constitutes the retrobulbar block. This injection provides akinesia of the extraocular muscles by blocking cranial nerves II,III, VI, thereby preventing movement of the globe. Cranial nerve IV lies outside the muscle cone, but is blocked by diffusion of the local anaesthetic. *Superior oblique is supplied by cranial nerve IV. Ref: Delhi Ophthalmic society aicle', 'role': 'assistant'}]