Radius

SkeletalSkeletonArmLeft and right

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What it is

The lateral (thumb-side) forearm bone: a disc-shaped head that spins against the capitulum and ulna, a bowed shaft, and a broad lower end that forms most of the wrist joint, ending in the styloid process.

Function

Rotates around the ulna to turn the palm up and down (supination and pronation) and carries the hand.

Size

≈ 24 cm long; head ≈ 22 mm across

Clinical note

The distal radius (Colles' fracture) is the most common fracture in adults, typically from a fall on an outstretched hand.