This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Upper Extremity, Subject name: Anatomy
[{'content': "Which structure passes through Guyon's canal? \nSelect and explain. \nA. Ulnar nerve, B. Median nerve, C. Radial nerve, D. Flexor carpi radialis", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. A Ulnar nerveRef: Gray's Anatomy review E-book, P 336Clinical Correlates: Guyon's Canal Syndrome* Guyon's canal (ulnar tunnel) is formed by the pisiform, hook of the hamate, and pisohamate ligament, deep to the palmaris brevis and palmar carpal ligament and transmits the ulnar nerve and artery.* Guyon's canal syndrome is an entrapment of the ulnar nerve in the Guyon's canal.* Symptoms: Pain, numbness, and tingling in the ring and little fingers, followed by loss of sensation and motor weakness.* Rx: Surgical decompression of the nerve.", 'role': 'assistant'}]