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': 'Axis is the name for: \nSelect and explain. \nA. IV cervical vertebra, B. III cervical vertebra, C. II cervical vertebra, D. I cervical vertebra', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Second cervical vertebra (axis)\n\nPresence of odontoid process.\nTransverse processes are small and lack the anterior tubercle.\nAnterior margin of the inferior surface of the body projects downwards to a considerable extent.\nForamen transversarium is directed superolaterally (expand\xa0in typical vertebrae it is directed vertically)\nInferior surface presents a deep and wide inferior vertebral notch placed in front of the inferior articular process. The superior vertebral notch is shallow and is present behind the superior articular process.\n\nKey concept:\nSecond cervical vertebra is called the axis. it is identiﬁed by the presence of the dens or odontoid\xa0process which is a strong, tooth-like process projecting upwards from the body. The dens is usually\xa0 believed to represent the centrum or body of the atlas which has fused with the centrum of the axis.', 'role': 'assistant'}]