Which bone articulates with the acetabulum to form the hip joint?

• A. Head of the femur
• B. Tibia
• C. Humerus
• D. Radius

Answer: (A)

The hip joint is formed where the spherical head of the femur fits into the cup-shaped acetabulum of the pelvis, creating a ball-and-socket joint that allows a wide range of motion. The head of the femur provides the rounded, movable end that sits securely within the acetabulum, supported by ligaments and the acetabular labrum to stabilize the joint.

The other bones listed do not participate in the hip joint: the tibia forms the knee joint with the femur, the humerus forms the shoulder joint with the scapula, and the radius forms joints in the forearm and wrist. Therefore, the bone that articulates with the acetabulum to form the hip joint is the head of the femur.