Three Arm Bones The humerus, the radius, the ulna

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This article was edited and updated on November 13, 2019.

Three Bones in the Arm: Humerus, Radius, and Ulna

Three bones, along with their muscle attachments, help you to move your arm in many ways. The wrist and hand are even more intricate and allow you to perform many other tasks.

The primary protein in bone is collagen — a substance which is stronger than steel, but far more flexible. Bone also contains calcium phosphate — which makes bone hard; as a result, we have bones which are both strong and flexible. This is important because when we lose our balance or panic, it is instinctive to put our arms out in front of us. If the bones aren't strong, they will break when they try to support our full body weight.

The large bones of the arm are:

The Humerus

Thanks to Wikipedia for the image.

The humerus is located in the upper arm and it goes from the shoulder to the elbow. It connects to the scapula at the top and to the radius and ulna in the lower arm, and it also helps both the shoulder and elbow joints to move.

Because of the humerus and the shoulder joint, we can move our arm out to the side, straight up over the shoulder, and even back behind us. The arm and hand together obviously help us perform many other tasks.

Fractures of the humerus — in car accidents, sports injuries, and falls — are unfortunately all too common. In older adults, the humerus is more likely to break during a fall, particularly if osteoporosis is present.

The Radius

Thanks (again) to Wikipedia for the image.

The radius is one of two bones which run parallel to each other in the forearm. It begins at the lateral side of the elbow and goes to the thumb side of the wrist.

The radius helps us to rotate our arm. Like the humerus, however, the radius can fracture — and this almost always occurs about one inch from the end of the bone.

A common fracture of the radius is known as the Colles fracture; it was named for an Irish surgeon and anatomist, Abraham Colles, who discovered it. When this type of fracture occurs, the broken fragment of the radius tilts upward. Unfortunately, a broken radius can take a long time to heal.

The Ulna

Thanks (again) to Wikipedia for the image.

The ulna — sometimes called the elbow bone — is the other long bone of the forearm. It runs parallel to the radius but the radius is shorter and smaller than the ulna. When the arms are down at the sides and the palms of the hands face forward, the ulna is located closest to the body and on the same side as the little finger.

Fractures to either bone in the forearm are fairly common. A strong force is required to break them, but if they have been weakened by osteoporosis, they may break more easily. It is fairly common for adults to break both bones during a forearm injury. When only one bone in the forearm is broken, it is typically the ulna — usually as a result of a direct blow to the outside of your arm when falling or raising your arm in self-defence. 2

Treatment for fractures depends on where the break occurs, how many breaks there are, and whether or not the skin is broken.

Why and how do we keep our bones strong?

Remember that bone is living tissue; it therefore responds to exercise by becoming stronger. Research indicates that when young people exercise regularly, they achieve greater peak bone mass than those who do not. Bone mass peaks for everyone sometime during the third decade of our life; after that, we begin to lose bone.

Our bones have many tasks. They:

If not taken care of, bones can become weak and break. Broken bones are painful and surgery is sometimes needed. Once broken, there can be long-lasting health problems.

There are things you can do to keep your bones healthy and strong:

How do we exercise our bones?

Exercising allows us to maintain muscle strength, coordination, and balance — and those things help us to prevent falls and fractures.

Some of the best exercises to improve bone strength in the arms are:

For more information related to the arm bones or other bones of the body, see also:

I am a BCRPA-certified fitness instructor in Vancouver, BC. I teach four classes at the West End Community Centre in Vancouver, BC, mostly designed for the older adult. The Inevitable Disclaimer: Everything published here expresses only my opinion, based on my training and research. What you do with the information is entirely your own responsibility. I am not liable for any injury you suffer that seems to be related to anything you read here. Always consult your doctor before beginning an exercise program. For other articles, return to the table of contents.

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  1. These three dots behave exactly like a footnote. Click on them and you will get more information about the topic. 

  2. Older adults often break this bone when they fall. That is why it's so important to exercise the muscles of the forearm.