The ulna (formerly called the cubitus bone) is part of the skeleton of the forearm.
The ulna is a forearm bone which lies parallel to the radius and is located between:
The ulna is a long bone composed of:
The ulna articulates in the elbow to enable the forearm to flex, and in the wrist to articulate the hand.
The ulna is the bone lying above, the other one is the radius. © DR