Anatomy Physiology

The human skeletal system is an amazingly complex set of bones. Without these bones, you wouldn’t be much more than a bag of water-filled cells – something like a land-based jellyfish. But bones are not merely hard structures to which muscles and other organs are attached – they are living tissues. Sure, they are hard and don’t appear to be “alive” in the same sense that say, your liver does – but bones are constantly undergoing restructuring and repair. Let’s take a look at the process of ossification and some of the clinical features of one bone in particular – the radius. 

The radius is one of two major bones in the forearm. The other is the ulna. The radius is located on the lateral side of the forearm when the arm is held in the proper anatomical position. Lateral here refers to being away from the midline of the body – for the definition of the anatomical position, do a Google search.

Ossification is the process by which a bone becomes hard and completely solid. When bones are first formed in a fetus, they are not completely hard. In fact, early on in development, they are rather soft and flexible. This has advantages when a fetus needs to be packed in to a small place like the mom’s uterus, and when the newborn is being squeezed through the birth canal. But once the baby is born and it has to support it’s own weight, the bones need to become harder.

The radius begins to ossify (harden) from three different parts of the bone. The center, or shaft, of the radius is the first part to harden. The distal end (the end near the wrist) hardens next. The last part of the radius to ossify is the end nearest the elbow. This entire process can take several months to a few years after a child is born.

Of course, the plates where the radial bones grow from don’t stop and completely seal until later in life. These areas are known as the epiphiseal plates, and they are located near the ends of the radius. They fuse when a person is in their late teens, early twenties. After these areas harden and fuse, the person has essentially stopped growing.

The radius is the bone in the forearm that articulates with the bones in the wrist. It is somewhat fragile on the wrist end, and is a commonly broken bone in children. When a child falls on an outstretched arm, the radius is one of the bones that can easily be broken. This risk is logical given that the ends are the last parts to ossify.

Distal radius (wrist end) fractures are generally pretty easy to see on an x-ray. They can range in severity from a small crack to being completely poked through the skin (called an open fracture). The treatment and stabilization of these fractures is dependent on many factors including the exact location of the break, the severity, and other bones that may be effected.