The accuracy in the classification is lower than those reported for majority of sexual dimorphism morphological indicators for the occipital bone, and hence, the indexes and tables of the expected range of foramen magnum dimensions in skulls of men and women should be used only as a first approximation to the diagnosis of sex, which is more accurate when we look at the qualitative features of the occipital bone, such as the roughness of the nuchal lines, the shape of the occipital condyles, and the characteristics of the external occipital protuberance
Roughness of the occipital bone: in the occipital bone in male exist a remarkable development of superior and inferior nuchal lines, as well as the external occipital protuberance
, occipital crest and the insertion ruggedness, where inserting semispinosus muscle of the head.
The external occipital protuberance
was located on the external lamina of the squamous occipital bone which was sharp and pointed, in contrast, it was wide and blunt in sheep (May), small and double in leopard cat (Sarma et al.
Neck circumference was measured at the level of the cricoid cartilage, and head circumference was measured through the superciliary arch and external occipital protuberances