This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
[{'content': "Enophthalmos is an uncommon feature of Horner's syndrome. Enophthalmos is due to palsy of? \nSelect and explain. \nA. Levator palpebrae superioris, B. Superior tarsal muscle, C. Orbitalis muscle, D. Inferior tarsal muscle", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Enophthalmos (sinking of the eye) is the inward displacement of the eyeball. It results from paralysis of the orbitalis muscle (a smooth muscle that spans the inferior orbital fissure and may contribute to maintaining the normal position of the eyeball).', 'role': 'assistant'}]