Anatomy Physiology

The human skeletal system is a complex set of bones and connective tissues that serve several functions in the body. One of the primary functions of the bones is to provide support and structure. You couldn’t move well without a skeleton to attach muscles to. Instead you would slink about like a giant ameoba – not much fun. The radius is one of two bones found in the forearm of humans. This article will take a look at the basic anatomy of the human radius.

Despite a similar name, the radius has nothing whatsoever to do with the geometry term. It’s not the distance from the center of any circle to the edge. There are two bones in the forearm of a human, the ulna and the radius.

If you place a body in the anatomical position (laying flat, with the arms to the sides, hands facing forward), the radius is on the outside (lateral). If you trace a line from the tip of the thumb and follow the backside of the thumb toward the forearm, you’ll be touching the radius.

The upper end (called the proximal end) of the radius has an area that attaches to the humerus (the major bone in the upper arm) at the elbow joint. At the elbow joint, the radius also attaches the other bone in the forearm – the ulna. These bones are all connected with muscles and ligaments.

There are many muscles attached to the main shaft of the radius. Anatomists generally agree that there are three surfaces to the radius (oddly, there are debates in anatomy regarding the naming and classification of some structures. They actually have conferences to argue about things like this. Bizarre.). They are the anterior, posterior, and lateral surface. Various muscles attach to different parts of these three surfaces. 

Near the wrist joint is the distal end of the radius. This is the thickest and largest part of the radius (it’s the narrowest part of the ulna, which keeps your forearm from getting wider as you get closer to your hand.). The radius articulates with many of the bones in the wrist, specifically the lunate and scaphoid. The radius also attaches again to the ulna near the wrist. The radius and ulna do not make contact along the shaft.

The radial artery can be felt as it runs near the surface against the radius just below the wrist. There are a variety of muscles attached to the radius at various points. THIS ARTICLE outlines some of the major muscle attachments to the radius.

The radius is a commonly broken bone. Radial fractures are frequently seen near the wrist, and in some cases can be quite severe – often requiring surgery and pins to fix. There is of course, a lot more to the anatomy of the radius and the forearm – this article is meant to be an introduction to the topic.