Is ankle a ball and socket joint?
Hi Lamer, No, the ankle is a hinge joint. A few personal observations reveal the different mechanical nature of the main joints of the limbs: elbows and knees have no side-to-side movement and a range approaching a half-circle; these and the finger and toe joints work like hinges. The restrictions are imposed mainly by the shape of the bones at the elbow, and by ligamentous connections between them at the knee. At the shoulder, by contrast, the arm can be wielded in all directions, implying something like a ‘ball-and-socket’ — though the socket has to be shallower than that in a car-to-trailer joint which allows movement only in the horizontal plane. This arrangement makes the shoulder more liable than any other joint to dislocation — the ball at the top of the humerus slipping out of its socket on the scapula (shoulder blade). The hips also have a ball and socket structure, with a somewhat deeper socket in the ilium (pelvic or hip bone) for the head of the femur (thigh bone). The wris
