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Name of bone



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, prism-shaped 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 as rotating around an axis line extending diagonally from the center of the capitulum to the center of the distal ulna. The purpose of the radius is to connect the elbow to the forearm.

The radius has a body and two extremities:

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

Figure 1. Radius, ulna, and humerus

Muscle and ligament attachments

Surface anatomy

The long, narrow medullary cavity is enclosed in a strong wall of compact bone. It 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. It is missing in radial aplasia.


Physical examination




Radius fracture 

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Academic Resources

Resources on Radius from Pubget.

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