2.The posterior aspect of the skull The most outstanding feature of the occipital bone is external occipital protuberance 枕外隆凸 The ridge骨嵴 passing on each side laterally of the protuberance is the superior umn nuchalline上项线 downUp 2.The posterior aspect of the skull down The most outstanding feature of the occipital bone is external occipital protuberance 枕外隆凸. The ridge骨嵴 passing on each side laterally of the protuberance is the superior nuchal line上项线