Near the middle of the occipital squama is the external occipital protuberance, and extending lateralward from it on either side is the superior nuchal line, and above this the faintly marked highest nuchal line. It is less pronounced in females. The inion is the highest point of the external occipital protuberance. a projection on the external surface of the squamous part of the occipital bone in the midline [ http://en.wikipedia.org/wiki/External_occipital_protuberance ]