The second cervical vertebra in humans and other vertebrates, which allows the head to rotate; also called the axis vertebra.
From Greek 'epi-' (upon) + 'strophē' (turning), named because this bone enables the turning or rotation of the head relative to the first cervical vertebra.
Naming a vertebra after a Greek turning-motion is brilliant—this small bone at the base of your skull literally lets your head spin around, and the name describes exactly what it does!
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