Which synovial joint type is multiaxial and allows movement in multiple planes?

• A. Ball-and-socket (multiaxial)
• B. Hinge (uniaxial)
• C. Pivot (uniaxial rotational)
• D. Saddle (biaxial)

Answer: (A)

Movement in multiple planes is possible when the joint allows motion around several axes. A ball-and-socket joint has a rounded head that fits into a cup-shaped socket, enabling flexion and extension (sagittal plane), abduction and adduction (frontal plane), and rotation around the long axis (transverse plane), with circumduction as a combination of these. This combination gives it motion in many directions, which is why it’s multiaxial. Classic examples are the shoulder and hip joints.

Hinge joints move mainly in one plane (flexion and extension), so they are uniaxial. Pivot joints allow rotation around a single axis, also uniaxial. Saddle joints are biaxial, permitting two planes of motion (like some movements of the thumb) but not the three-dimensional freedom of a ball-and-socket joint.