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': 'Structure crossing dorsal surface of ischial spine are all except \nSelect and explain. \nA. Internal pudendal vessel, B. Pudendal nerve, C. Obturator nerve, D. Nerve to obturator internus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Pudendal nerve, internal pudendal vessels, and nerve to obturator internus after leaving the pelvis through greater sciatic foramen, cross the dorsal aspect of the ischial spine and then re-enter the pelvis through the lesser sciatic foramen.', 'role': 'assistant'}]