Radius

The radius is the bone of the forearm that extends from the lateral side of the elbow to the thumb side of the wrist. The radius is situated on the lateral side of the ulna, which exceeds it in length and size. It is a long bone, prismatic in form and slightly curved longitudinally.

Anatomy of the Radius

The radius consists of a body and two extremities:

• The body of the radius,
• The upper extremity of the radius, and
• The lower extremity of the radius.

Body of Radius

The body of the radius is prismoid in form, narrower above than below. It consists of three borders and three surfaces.

The borders include:

• The volar border which extends from the lower part of the tuberosity above to the anterior part of the base of the styloid process below, and separates the volar from the lateral surface,
• The dorsal border which begins above at the back of the neck, and ends below at the posterior part of the base of the styloid process; it separates the posterior from the lateral surface, and
• The interosseous crest which separates the volar from the dorsal surface, and gives attachment to the interosseous membrane.

The surface includes:

• The volar surface,
• the dorsal surface, and
• The lateral surface

Upper Extremity of Radius

The upper extremity of the radius (or proximal extremity) presents a head, neck, and tuberosity.

The radial head has a cylindrical form, and on its upper surface is a shallow cup or fovea for articulation with the capitulum (or capitellum) of the humerus.

The head is supported on a round, smooth, and constricted portion called the neck, on the back of which is a slight ridge for the insertion of part of the supinator muscle.

the radial tuberosity has a surface is divided into a posterior, rough portion, for the insertion of the tendon of the biceps brachii muscle, and an anterior, smooth portion, on which a bursa is interposed between the tendon and the bone.

The Lower Extremity of the Radius

The lower extremity of the radius consists of both articular surfaces and non-articular surfaces.

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