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': 'The forcible separation of the head of the radius from the capitulum of the humerus is mainly prevented by the: \nSelect and explain. \nA. Aicular capsule, B. Annular ligament, C. Quadrate ligament, D. Radial collateral ligament', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The radial notch of the ulna and the annular ligament form a ring in which the head of the radius rotates at its aiculation with the capitulum of the humerus. The annular ligament narrows over the neck, cupping the head of the radius and preventing downward dislocation. Ref: Moon D.A., Foreman K.B., Albeine K.H. (2011). Chapter 31. Arm. In D.A. Moon, K.B. Foreman, K.H. Albeine (Eds), The Big Picture: Gross Anatomy.', 'role': 'assistant'}]