Overview
The proximal radius is the upper end of the forearm bone on the thumb side. Its disc-shaped radial head meets the capitellum of the humerus and rotates against the ulna.
The annular ligament encircles the radial head, holding it in place while allowing the forearm to turn. Just below it, the radial tuberosity provides the attachment for the distal biceps tendon.
Function
- Helps turn the palm upward and downward
- Transfers force from the wrist toward the elbow
- Contributes to outer-elbow stability
- Provides leverage for the biceps during supination
Common Problems
Radial head fractures often follow a fall onto an outstretched hand and may make forearm rotation painful. The radial head can also dislocate with more complex elbow injuries. In young children, a sudden pull on the arm can allow the annular ligament to slip over the radial head—a different injury called nursemaid’s elbow.
When to Get It Assessed
Seek assessment after a fall if rotation is sharply limited, the elbow swells quickly, or you cannot fully bend or straighten it.
References
- StatPearls. “Anatomy, Shoulder and Upper Limb, Forearm Radius.” https://www.ncbi.nlm.nih.gov/books/NBK544512/
- AAOS OrthoInfo. “Radial Head Fractures of the Elbow.” https://orthoinfo.aaos.org/en/diseases--conditions/radial-head-fractures-of-the-elbow/