Final answer:
The gap in the ridge of the margins of the acetabulum is called the obturator foramen. It is a large opening located on the anteroinferior side of the hip bone, between the ischium and pubis.
Step-by-step explanation:
The gap in the ridge of the margins of the acetabulum is called the obturator foramen. This is a large opening located on the anteroinferior side of the hip bone, between the ischium and pubis. It is largely filled in by connective tissue and serves for the attachment of muscles.