## Encyclopedia > Ulna

Article Content

# Ulna

The ulna (along with the radius) is one of the two bones in the forearm. In the anatomical position, it is medial to the radius.

The ulna articulates with:

• the humerus, at the elbow as a hinge joint.
• the radius, near the elbow as a pivot joint, this allows the radius to cross over the ulna in pronation.
• the distal radius, where it fits into the ulna notch.

The ulna is broader proximally, and narrower distally.

Proximally, the ulna has a bony process, the olecranon process, a hook-like structure that fits into the olecranon fossa of the humerus. This prevents hyperextension and forms a hinge joint with the trochlea of the humerus. There is also a radial notch for the head of the radius, and the ulna tuberosity to which muscles can attach.

Distally (near the hand), there is a styloid process.

All Wikipedia text is available under the terms of the GNU Free Documentation License

Search Encyclopedia
 Search over one million articles, find something about almost anything!

Featured Article
 Quadratic formula ... square roots of both sides yields $x+\frac{b}{2a}=\frac{\pm\sqrt{b^2-4ac}}{2a}.$ Subtracting ...

This page was created in 24.7 ms