Final answer:
The iliofemoral ligament joins the femur to the ilium, stabilizing the hip joint and limiting excessive thigh extension. It works alongside the ligament of the head of the femur, which also contributes to hip stability.
Step-by-step explanation:
The ligament that joins the femur to the ilium is known as the iliofemoral ligament. This intrinsic ligament is found on the superior-anterior aspect of the hip joint and is crucial for stabilizing the hip by limiting excessive extension of the thigh and maintaining an upright standing position with minimal muscle contraction. Another important ligament in the hip joint is the ligament of the head of the femur, which is an intracapsular ligament running from the acetabulum to the head of the femur, providing a pathway for an artery to the femoral head.
Both the iliofemoral and the ligament of the head of the femur contribute to the stability and function of the hip joint. The pubofemoral ligament, which spans from the pubis of the hip bone to the femur on the anterior-inferior aspect, is also essential for hip joint stability.