Palmar radiocarpal ligament

The palmar radiocarpal ligament complex is the group of strong extrinsic (capsular) ligaments spanning the palmar (volar) aspect of the radiocarpal joint, connecting the distal radius to the proximal carpal row. These ligaments lie within the joint capsule as organized thickenings of parallel collagen fascicles, each enveloped in a superficial fibrous stratum and a deep synovial stratum, and they function to guide and constrain carpal motion while resisting ulnar and palmar translation of the carpus.

In the classification defined by Berger, the complex comprises four named ligaments:

• Radioscaphocapitate (RSC) ligament — originates from the radial styloid process, courses across and supports the waist of the scaphoid (interdigitating with palmar TFCC fibers palmar to the capitate head), with a minor distal insertion into the capitate. It stabilizes the palmar-flexed scaphoid. The Terminologia Anatomica 2 list a variant of the RSC, the Radiocapitate ligament

• Long radiolunate (LRL) ligament — arises just ulnar to the RSC, separated from it by the interligamentous sulcus; it passes palmar to (but separate from) the scapholunate interosseous ligament and inserts into the radial half of the palmar lunate. Also described as part of the radiolunotriquetral ligament in some nomenclatures.

• Short radiolunate (SRL) ligament — originates from the palmar rim of the lunate facet of the distal radius and inserts as a flat sheet into the proximal palmar margin of the lunate; it resists lunate dorsiflexion. [1][3]

• Radioscapholunate ligament (of Testut and Kuenz) — a small structure that is functionally a neurovascular conduit rather than a true mechanical stabilizer.

Functionally, these ligaments are among the strongest wrist stabilizers and act together (with the dorsal radiocarpal ligament) as the principal restraints against ulnar translation of the carpus; biomechanical sectioning studies show progressive ulnar translation only after multiple of these ligaments are divided.

Previous Gray's description of Palmar radiocarpal ligament:

The palmar radiocarpal ligament (Volar Radiocarpal Ligament, anterior ligament) , is a broad membranous band, attached above to the anterior margin of the lower end of the radius, to its styloid process, and to the front of the lower end of the ulna; its fibers pass downward and medialward to be inserted into the volar surfaces of the navicular, lunate, and triangular bones, some being continued to the capitate. In addition to this broad membrane, there is a rounded fasciculus, superficial to the rest, which reaches from the base of the styloid process of the ulna to the lunate and triangular bones. The ligament is perforated by apertures for the passage of vessels, and is in relation, in front, with the tendons of the Flexor digitorum profundus and Flexor pollicislongus; behind, it is closely adherent to the anterior border of the articular disk of the distal radioulnar articulation.