Also known as the pubocapsular ligament, the pubofemoral ligament attaches the pubis, a bone on the underside of the pelvis, to the femur bone of the thigh. It crosses the inferior or bottom aspect of the acetabulofemoral or hip joint. In doing so, this ligament functions along with the other joint ligaments to hold the head of the femur inside of the acetabulum, a concave socket formed by the intersection of the three bones of the pelvis: the ilium, ischium, and pubis.
The pelvic bones include the ilium above and the ischium and pubis below, with the pubis forming the front portion of the lower pelvis and the ischium forming the rear portion. When viewing the pelvis from the side, the three bones intersect to form a round cavity known as the acetabulum. Shaped like a bowl, this socket receives the ball-shaped head of the femur, which moves relatively freely in the acetabulum to move the leg in multiple directions.
Holding the head of the femur in the hip socket is a capsule of three ligaments originating on the neck of the femur bone, crossing the hip joint, and attaching to the pelvic bones. These include the iliofemoral ligament, ischiofemoral ligament, and the pubofemoral ligament, which forms the underside of this capsule. It is situated slightly toward the front of the underside of the joint.
On its outside end, the pubofemoral ligament attaches to the bottom interior aspect of the neck of the femur. The femoral neck is a length of bone that angles upward and inward off the top of the shaft of the femur, and the femoral head sits on top of the neck. Just above where the femoral neck meets the shaft on the medial or inside aspect of the neck, the pubofemoral ligament begins. Running parallel to the neck of the femur, it angles inward and upward toward the pelvis and crosses the underside of the hip joint. Its upper fibers are continuous with those of the iliofemoral ligament, a broad ligament that makes up the front and top portions of the capsule.
This ligament then attaches on its inside end to the pubic bone. Specifically, it connects to the superior ramus and obturator crest of the pubis. The superior ramus is the upper arch of the pubis, and it forms the front margin of the acetabulum. On the underside of this arch is a ridge referred to as the obturator crest. The pubofemoral ligament attaches on the lower anterior pubis to these two surfaces, thus supporting the femur in the hip joint from below and limiting external or lateral rotation of the leg in the joint.