Collateral Ligaments of the Distal Interphalangeal Joints, Posterior View

Description

Positioned on the dorsum of a male hand, the distal phalanges and middle phalanges meet at the distal interphalangeal (DIP) joints, where paired collateral ligaments span from the lateral tubercles of each middle phalanx head to the corresponding bases of the distal phalanges. From this posterior perspective, each collateral band sits slightly dorsal to the joint’s center of rotation and runs obliquely from proximal to distal, framing the joint line on the radial and ulnar sides. Adjacent articular cartilage caps the opposing phalangeal surfaces, while the metacarpals and carpal bones provide proximal context. Small joints, clear landmarks. Collateral ligament orientation at the DIP joint matters because stability changes with flexion: the proper collateral ligament tightens as the joint flexes, while the accessory collateral fibers relate to the volar plate and resist hyperextension. Ulnar or radial-sided DIP pain after a “jammed finger” often reflects partial tearing of these ligaments, and chronic laxity can contribute to angular deformity or accelerate osteoarthritic change at the terminal hinge. For clinicians splinting a mallet finger or evaluating a distal phalanx fracture, appreciating the collateral attachments helps predict whether the distal phalanx will drift into ulnar or radial deviation and whether the joint remains concentrically reduced. Educators can drop this posterior-view ligament study straight into hand anatomy labs, orthopedic exam teaching on varus and valgus stress at the DIP, or surgical illustrations discussing dorsal approaches where the terminal extensor tendon and collateral complexes must be protected. It also fits radiology and sports medicine content that correlates collateral injury patterns with joint congruity on PA and lateral finger radiographs. Anatomical accuracy verified by SciePro's Medical Advisory Board.