🦴 Radioulnar Joints

Brian Lee

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Here are the three articulations connecting the radius and ulna along the length of the forearm:

Joint	Location	Anatomical Type	Degrees of Freedom	Primary Motion
Proximal radioulnar joint	Elbow region (radial head & radial notch of ulna)	Synovial pivot	1	Pronation / Supination
Middle radioulnar syndesmosis	Interosseous membrane between shafts	Fibrous syndesmosis	~0 (slight)	Minimal gliding (stabilizes)
Distal radioulnar joint	Wrist region (ulnar notch of radius & head of ulna)	Synovial pivot	1	Pronation / Supination

The proximal and distal radioulnar joints are true pivot joints, each permitting the radius to rotate around the ulna for pronation and supination.
The interosseous membrane is a fibrous “joint” (syndesmosis) that binds the shafts, transmitting load and maintaining alignment, with only very slight movement.