Bones in the Arm

By Amelia Son, PTA

What are the 3 Bones in the Arm?

There are three bones in your arm the humerus, the ulna, and the radius. The upper arm is made up of the humerus bone. Additionally, the forearm is made up of the ulna and the radius.  These three bones meet to form the elbow joint. The radius and ulna join the hand to make the wrist joint, which is known as the carpus.

Radius, Ulna, Humerus labeled in the x-ray image of all bones in the arm. JOI REHAB

Image of Bones in the Arm

While it is easy to note that the humerus runs down the arm from the shoulder to the elbow, the radius and ulnar are specific to either the pinky or thumb side of the wrist.  The Radius runs from the elbow joint to the wrist’s thumb side and the ulna from the elbow to the pinky side of the wrist.

Injuries to the Arm Bones

Bone fractures are common in the arms and are usually short-term injuries.  The most commonly occur from high-impact collisions such as falls, sports injuries, and automobile accidents.  The most common broken bones in the arm are the forearm bones, the radius, and the ulna.

Complicated fractures that have multiple breaks may need surgical intervention. The forearm bones are cast in the proper position to heal a simple fracture.  The forearm bone’s composition includes collagen and is strong but flexible.  This is how it can take so much force and pressure daily.

Forearm Supination and pronation of the human arm bones. JOI Rehab

Arm supination and pronation vector or the forearm

This strength is important, considering that most people tend to throw their arms out in front of them to protect them from a fall or accident. The term for this injury is FOOSH or falling on an outstretched hand.  Hence the reasons for fractured forearms and, in some cases, shoulder injuries or even a broken collar bone.  The bones of the arm enable the forearm perform pronation and supination.

Jacksonville Orthopaedic Institute knows the importance of keeping arms strong and mobile for everyday life. Our physical and occupational therapists are here to rehab your arm back to functional status.

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Written by: Amelia Son, PTA

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