Medicograspers | Anatomy notes | Upper limb | Notes on Radius and Ulna |

 

    RADIUS AND ULNA

"805 Ulna and radius", licensed under CC BY 3.0

In this article, you will learn the anatomy of Radius and Ulnar bones in detail. 

Radius and Ulnar bones are present in the forearm:

    The bone Radius is on the Lateral side of the body

    The bone Ulna is located on the Medial side of the body. 

    THE ELBOW JOINT IS THE HINGE SYNOVIAL JOINT WHICH ALLOWS ONLY FOR FLEXION AND EXTENSION.    

Radius:

            It articulates with the capitulum of the humerus, proximally.

            Starting from proximal to distal, the radius consists of the head, neck, radial tuberosity, shaft of the radius, styloid process, and styloid tubercle.    

Ulna:

            It articulates with the trochlea of the humerus. The ulnar notch has an olecranon process which is the extension of an ulnar notch. The ulnar notch articulates with the trochlea of the humerus.

• At the proximal radioulnar joint, the head of the radius articulates with the radial notch which is present on the head of the ulna, which allows for pronation and supination of the forearm.
• At the distal radioulnar joint, the ulna articulates with the ulnar notch which is present on the radius, which allows for pronation and supination of the forearm.
• At the proximal radioulnar joint, there occurs a ligament named Annular ligament.
• This annular ligament rings around the radius. It emerges from the posterior side of the ulnar bone below the olecranon process. It surrounds or rings around the radius.
• It provides the stabilization of the radioulnar joint and this ligament blends with the fibrous membrane of the elbow joint. This ligament allows for the rotation of the radius against the capitulum and the radial notch of the ulna.

Radial head subluxation/ nursemaid’s elbow:

   If we forcefully pull the elbow of the young children, the radial bone gets dislocated from the annular ring. It's more common in younger children under 5 years of age.

    The head of the radius is located at the proximal radioulnar joint and the head of the ulna is located at the distal radioulnar joint.

   The heads of both bones articulate with the notches of both bones i.e., radial head with a radial notch on ulnar bone and ulnar head with an ulnar notch on the radial bone.

Supinator muscles:

    Biceps brachii and supinator.

Pronator muscles:

    Pronator teres proximally and pronator quadratus distally.