The acetabulum is completely surrounded by these three bones, but its cup always retains an open foramen; from its posterior rim arises the strong antitrochanter.
In front of the acetabulum a thick process of the ilium descends to meet the pubis, and a similar process behind meets the ischium.
In.; and to both systems were added from the Attic the cyathus (2.87 cub in.), acetabulum (4.3 cub.