external occipital crest external occipital crest the external occipital crest is part of the external surface of the squamous part of the occipital bone. it is a ridge along the midline, beginning at the external occipital protuberance and descending to the foramen magnum, that gives attachment to the nuchal ligament. it is also called the median nuchal line. external occipital crestskull seen from belowdetailsidentifierslatincrista occipitalis externata98a02.1.04.023ta2569fma75753anatomical terminology