The Distal Oblique Bundle of the Distal Interosseous Membrane of the Forearm

Abstract

The distal interosseous membrane (DIOM) of the forearm is on the distal side of the central band of the interosseous membrane, spanning the radius and ulna at the dorsal region of the pronator quadratus muscle. Recent anatomical studies have revealed that the thickness of the DIOM varies widely among specimens (0.5–2.6 mm), and an obvious thick fiber within the DIOM, called the distal oblique bundle (DOB), exists in 40% of specimens. 1,2 The DOB originates from the distal ulna 54 mm (on average; range, 50–57 mm) proximal to the ulnar head and runs distally to insert on the dorsal inferior rim of the sigmoid notch of the radius (►Fig. 1a,b). The DOB has an anatomical relationship with the triangular fibrocartilage complex (TFCC) (►Fig. 2), both of which