Ulna

The ulna (formerly called the cubitus bone) is part of the skeleton of the forearm.

Location of the ulna

The ulna is a forearm bone which lies parallel to the radius and is located between:

• the humerus in the elbow
• and a joint disc in the wrist.

Structure of the ulna

The ulna is a long bone composed of:

• a diaphysis, the central part which has a triangular section,
• and two epiphyses, distal and proximal, involved in the joints.

Function of the ulna

The ulna articulates in the elbow to enable the forearm to flex, and in the wrist to articulate the hand.