What is the name for a joint that can only move in two directions?
A hinge joint can only move in two directions. The elbow is a hinge joint. It can only bring the lower arm closer to the upper arm or move it away from the upper arm. In a ball-and-socket joint, the rounded top of one bone fits into a concave part of another bone, enabling the first bone to rotate around in this socket. This connection is slightly less stable than other types of joints in the human body and is therefore supported by a denser network of ligaments. The shoulder and hip are both examples of ball-and-socket joints.