Ọ dị mma maka ndị na-achọ ihi ụra n'otu akụkụ, nwere cervical vertebra na ubu mgbu, na-arụ ọrụ na ekwentị mkpanaaka ma ọ bụ na-agbada ruo ogologo oge, na-emekarị ọsụsọ na-atụ egwu okpomọkụ.Mgbe ị dinara n'azụ, n'etiti nhazi urukurubụba 3D, radian iji kwado isi, olu na ubu, ụra nchebe olu.Mgbe ị na-ehi ụra n'akụkụ, nhazi pụrụ iche nke nku occipital na-ekowe ogo 45 na-ahapụ nrụgide olu ka e wee nwee ike ịkwado ubu n'ụzọ zuru ezu.