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. The radius articulates with the capitulum of the humerus.

The word "radius" is Latin for "ray." In the context of the radius bone, a ray can be thought of rotating around an axis line extending diagonally from centre of capitulum to the centre of distal ulna.

It has a body and two extremities:

• Body of radius
• Upper extremity of radius
• Lower extremity of radius

Structure

The long narrow medullary cavity is enclosed in a strong wall of compact bone which is thickest along the interosseous border and thinnest at the extremities except over the cup-shaped articular surface (fovea) of the head where it is thickened.

The trabeculae of the spongy tissue are somewhat arched at the upper end and pass upward from the compact layer of the shaft to the fovea capituli; they are crossed by others parallel to the surface of the fovea.

The arrangement at the lower end is somewhat similar.

See also

• Bone terminology
• Terms for anatomical location
• Ossification of radius

Additional images

<gallery> Image:Radius ant.jpg|Radius l. dx. - ant. view Image:Radius post.jpg|Radius l. dx. - post. view Image:RightHumanPosteriorRadiusUlna.jpg|Right human radius and ulna - post. view Image:Human arm bones diagram.svg|Human arm bones diagram Image:Gray213.png|Bones of left forearm - ant. view Image:Gray214.png|Bones of left forearm - post. view Image:Gray329.png|Left elbow-joint, showing anterior and ulnar collateral ligaments Image:Gray420.png|The Supinator Image:Gray417_color.PNG|Cross-section through middle of forearm Image:Gray421.png|Transverse section across distal ends of radius and ulna </gallery>

External links

• Radial fractures

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