Chordomas are thought to arise from remnants of embryonal notochord. In the embryonic stage, the upper ends of notochords mainly distribute to the sphenoid bone and occipital bone of the skull base. While the lower ends of notochords distribute to the middle of sacrum and the tissue surrounding. Therefore chordomas can arise from bones in the skull base and anywhere along the spine. The two most common locations are cranially at the clivus and in the sacrum at the bottom of the spine.