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The radius is among the 2 bones that make up the forearm, the other being the ulna. It forms the radio-carpel joint at the wrist and also the radio-ulnar joint at the elbow. It is in the lateral forearm when in the anatomical position. The is the smaller sized of the 2 bones.

You are watching: In the anatomical position, the lateral forearm bone is the radius.

Structure

Proximal radius

The proximal radius is composed of the radial head, neck and also tuberosity.

The radial head is cylindrical which articulates through the capitellum that the humerus<1>. The head rotates within the annular ligament to produce supination and pronation of the forearm.<2>

The neck and tuberostiy assistance the head and provide points that attachments for supinator brevis and Biceps brachi<1>

Radial shaft

The tower of the radius is contempt curved into convex from the body. The bulk of the shaft has three borders: anterior, posterior and also interosseous.

Distal radius<2>

The distal radius has 5 surfaces:

Lateral - which extends to kind the styloid processMedial - consists of a concave ulnar notch to articulate through the ulnar head in pronationPosterior - convex and contains a influential ridge referred to as Lister"s tubercleAnterior - smooth and forms a distinctive margin

Function

The radius" main functions are to articulate v the ulna and humerus at the elbow to provide supination and pronation. Climate to articulate v the lunate and scaphoid to carry out all the movements of the wrist.

Articulations

Elbow

The radius articulates with the ulna in a synovial pivot joint. The radial head rotates within the annular ligament and also radial notch ~ above the ulna to develop pronation the the forearm.<3>

The radius and also ulna additionally articulate distally in turning back to your articulation at the elbow to develop supination. This activity occurs v the head of the ulna being received right into the ulnar notch the the radius. <3>


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Wrist

The radius articulates through the very first row of carpel bones: greatly scaphoid laterally and the lunate medially to kind the radio-carpel joint, triquetral just makes intermittent call on ulnar abduction. The radio-carpel share is an ellipsoid joint whereby the scaphoid, lunate and triquetral bones form a convex surface to articulate with the distal radius" concavity.

The radio-carpel joint has 4 movements: flexion, extension, radial and also ulnar deviation.

Muscle attachments

Proximal

Biceps brachii attaches to the radial tuberosity.

Supinator, flexor pollicis longus and the flexor digitorum superficialis connect to the upper third part of the pillar of the radius.

Mid shaft

Extensor Pollicis Brevis muscle, abductor pollicis longus muscle, and pronator teres all affix to the mid tower of the radius

Distal

Pronator quadratus muscle and the tendon that the supinator longus affix to the distal quarter of the radial shaft.

Clinical relevance

Colles fracture: is a fracture the the distal radius. Commonly caused by a autumn on outstretched hand (FOOSH)

Radial head fracture: typically caused from FOOSH this have the right to be add by dislocation the the radius and/or ulna which deserve to complicate the administration of this injury.

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Osteoarthritis that the wrist or elbow

Radial dysplasia or radial society hand can take place in paediatric patients together a congenital condition by which there is a shortening the the radius or even finish lack the radius in the forearm. This have the right to lead to ignorance abnormalities and also the require for surgical intervention to boost function.<6>