The quadrate ligament is a fibrous band attached to the inferior border of the radial notch on the ulna and to the neck of the radius.

It is supported by the quadrate ligament below the annular ligament where it also forms a fold which gives the head of the radius freedom of movement.

In human anatomy, the quadrate ligament or ligament of Denucé is one of the ligaments of the proximal radioulnar joint in the upper forearm.

The quadrate ligament was first described by the French anatomist Jean-Paul-Louis Denucé in 1854, but its function and even presence has been disputed in anatomical literature ever since.

A thickened band which extends from the inferior border of the anular ligament below the radial notch to the neck of the radius is known as the quadrate ligament.

The quadrate ligament reinforces the inferior part of the capsule of the elbow joint and contributes to joint stability by securing the proximal radius against the radial notch and by restricting excessive supination (10-20 restriction) and, to a lesser degree, pronation (5-8 ).