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': 'Suprameatal triangle externally represents: \nSelect and explain. \nA. Transverse sinus, B. Promontory of middle car, C. Internal acoustic meatus, D. Mastoid antrum', 'role': 'user'}, {'content': "Answer: D \nExplanation: Suprameatal triangle, also known as MacEwen's triangle, is seen in temporal bone of skull, in\xa0 norma lateralis view.\nIt is a small area/depression present posterior and superior to external acoustic meatus.\nIt forms the lateral wall of mastoid antrum.\nIt is of importance to surgeons performing cortical mastoidectomy.\n\nBoundaries of Suprameatal triangle:\n\nSuperiorly: By supramastoid crest.\nAnteriorly: By posterosuperior margin of EAM (external acoustic meatus).\nPosteriorly: Vertical tangent to posterior margin of EAM (external acoustic meatus).\xa0\xa0\nAnteroinferiorly: By presence of suprameatal spine.\n\nKey Concept:\xa0\nSuprameatal triangle, also known as MacEwen's triangle, is seen in temporal bone of skull, in\xa0norma lateralis view. It represents mastoid antrum.", 'role': 'assistant'}]