Which joint is multiaxial and permits flexion, extension, abduction, adduction, medial and lateral rotation, and circumduction, such as the hip?

• A. Suture
• B. Interosseous membrane
• C. Plane (gliding) joint
• D. Ball-and-socket (spheroid) joint

Answer: (D)

Multiaxial ball-and-socket joints allow movement around three perpendicular axes, enabling flexion and extension, abduction and adduction, and internal and external rotation, with circumduction as a combined motion. The hip is a classic example: the spherical head of the femur sits in the deep acetabulum of the pelvis, providing a wide range of motion in all those directions. This combination of a spherical surface in a cup-shaped cavity gives the broad, multi-directional mobility that characterizes ball-and-socket joints.

Sutures are immobile fibrous joints between skull bones, so they do not permit these kinds of movements. Interosseous membranes are fibrous connections between bones that provide stability and some limited movement but are not true synovial joints with multiple axes. Plane (gliding) joints allow mainly sliding motions between flat surfaces and are typically nonaxial or have very limited motion, not the rich multi-axial rotation and circumduction seen in ball-and-socket joints.