Which statement correctly compares hinge joints and ball-and-socket joints?

Which statement correctly compares hinge joints and ball-and-socket joints?

• A. Hinge joints allow multi-axial movements in several planes.
• B. Ball-and-socket joints allow only flexion and extension.
• C. Hinge joints allow flexion/extension in one plane; ball-and-socket joints allow multi-axial movements including rotation.
• D. Ball-and-socket joints are examples of hinge joints.

Answer: (C)

Movement at joints is defined by the number of directions they allow. Hinge joints are uniaxial, permitting flexion and extension in one plane, such as the elbow or knee. Ball-and-socket joints are multiaxial, allowing flexion/extension, abduction/adduction, and rotation, with the shoulder and hip as classic examples because the spherical head fits into a socket to enable movement around multiple axes, including circumduction. Therefore, the statement that hinge joints operate in one plane of flexion/extension while ball-and-socket joints enable multi-axial movements including rotation best captures the contrast. The other descriptions misstate the movement capabilities—for instance, hinge joints do not have multi-axial movement, and ball-and-socket joints are not limited to just flexion/extension or classified as hinge joints.

Movement at joints is defined by the number of directions they allow. Hinge joints are uniaxial, permitting flexion and extension in one plane, such as the elbow or knee. Ball-and-socket joints are multiaxial, allowing flexion/extension, abduction/adduction, and rotation, with the shoulder and hip as classic examples because the spherical head fits into a socket to enable movement around multiple axes, including circumduction. Therefore, the statement that hinge joints operate in one plane of flexion/extension while ball-and-socket joints enable multi-axial movements including rotation best captures the contrast. The other descriptions misstate the movement capabilities—for instance, hinge joints do not have multi-axial movement, and ball-and-socket joints are not limited to just flexion/extension or classified as hinge joints.