What type of joint allows for both internal and external rotation as well as bending?

The type of joint that allows for both internal and external rotation, as well as bending, is the ball-and-socket joint. This joint structure features a rounded end of one bone (the ball) that fits into a cup-like cavity (the socket) of another bone. This anatomical design permits an extensive range of motion in multiple directions, enabling not only flexion and extension (bending) but also internal and external rotation, making it the most mobile joint in the human body.

For example, the shoulder joint and the hip joint are both ball-and-socket joints. They allow the arm and leg to move in various planes, providing the ability to rotate them inward and outward while also bending at the joints. This comprehensive range of motion is essential for many activities we perform in daily life, such as throwing a ball or rotating the leg while walking.

In contrast, other types of joints have more limited ranges of motion. Hinge joints allow movement primarily in one direction (like a door), pivot joints permit rotation around a single axis, and ellipsoid joints allow for movement in two planes but do not facilitate full rotational motion.