Radial collateral ligament of wrist joint

The radial collateral ligament (RCL) of the wrist is one of the two collateral ligaments of the radiocarpal joint (the other being the ulnar collateral ligament), classified among the extrinsic ligaments that connect the forearm to the carpus. It arises from the radial styloid process, positioned further radially than the radioscaphocapitate ligament, and courses distally to insert on the radial (lateral) aspect of the scaphoid and the lateral trapezium.

Key features:

• Origin/insertion: Radial styloid → radial margin of the scaphoid, often continuing to the trapezium, forming radioscaphoid and scaphotrapezial components.

• Function: Reinforces the lateral aspect of the radiocarpal joint capsule and contributes, along with the other extrinsic and intrinsic ligaments, to guiding and constraining carpal motion and maintaining carpal stability.

• Anatomic variation: On high-resolution MRI the RCL is variable, appearing either as separate radioscaphoid and scaphotrapezial bands or as a continuous radio-scapho-trapezial ligament, with narrow or broad scaphoid attachments.

• Classification note: Although grouped with the collateral ligaments, it is functionally considered part of the volar/radial extrinsic radiocarpal ligament group and is comparatively less robust than the strong volar radiocarpal ligaments (radioscaphocapitate, radiolunotriquetral, short radiolunate).

Gray's definition:

The radial collateral ligament extends from the tip of the styloid process of the radius to the radial side of the navicular, some of its fibers being prolonged to the greater multangular bone and the transverse carpal ligament. It is in relation with the radial artery, which separates the ligament from the tendons of the Abductor pollicis longus and Extensor pollicis brevis.