arcuate line of ilium arcuate line of ilium the arcuate line of the ilium is a smooth rounded border on the internal surface of the ilium. it is immediately inferior to the iliac fossa and iliacus muscle. for other uses, see arcuate line. arcuate line (ilium)male pelvis. (arcuate line shown in red.)right hip bone. internal surface. (arcuate line visible shown in red.)detailsidentifierslatinlinea arcuata ossis iliita98a02.5.01.105ta21320fma75088anatomical terms of bone it forms part of the border of the pelvic inlet. in combination with the pectineal line, it comprises the iliopectineal line. the arcuate line marks the border between the body (corpus) and the wing (ala) of the ilium, and, running inferior, anterior, and medial from the auricular surface to the area corresponding to the acetabulum, it also indicates where weight is transferred from the sacroiliac joint to the hip joint. additional images position of arcuate line of ilium. shown in red. close up pelvis with the iliopectineal line indicated in red