Arm · Long bone
Radius (Forearm Bone)
The radius is one of the two forearm bones, on the thumb side. It is the main bone involved at the wrist and lets you rotate your forearm to turn the palm up and down.
What it is
The radius runs alongside the ulna in the forearm, on the thumb side. It is the larger contributor to the wrist joint.
Where it is
The forearm, on the thumb (lateral) side, from the elbow to the wrist.
What it does
Forms much of the wrist joint and rotates around the ulna to turn the palm up (supination) and down (pronation); helps transmit force from the hand to the arm.
Connections
Joints and connections
- Elbow joint
- Wrist joint
- Joints with the ulna
When things go wrong
Common injuries and conditions
- Distal radius fracture (a very common wrist fracture, often from falling onto an outstretched hand — a "Colles' fracture")
- Radial head fracture at the elbow
Education and reference only. This explains the anatomy in plain terms; it is not a diagnosis. A severe injury, a visibly deformed limb, or the inability to move or bear weight needs urgent assessment — call 999 or go to A&E for a serious injury.
Did you know?
An interesting fact
A distal radius fracture is one of the most common broken bones, especially in older adults and children.
Answers
Radius: frequently asked questions
What is the radius bone?
The radius is the forearm bone on the thumb side. It forms much of the wrist joint and lets you rotate your palm up and down.
Is a broken wrist usually the radius?
Yes — the most common wrist fracture is a break of the lower end of the radius, often after falling onto an outstretched hand.
Explore the arm
Related bones
Sources
Where this is drawn from
- NHS — Anatomy and body systems
- Gray's Anatomy for Students (Drake, Vogl, Mitchell)
- TeachMeAnatomy — skeletal system
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