Base Of The Distal Phalanx, Posterior View

Description

Distal phalanx anatomy is centered here on the proximal base as seen from the posterior (dorsal) aspect of a human finger. Along the superior margin of the base, a subtle raised ridge forms the dorsal lip immediately proximal to the shaft, sitting proximal to the distal phalangeal tuberosity (tuft) that would extend inferiorly in the same orientation. Just deep to this dorsal contour lies the proximal articular surface for the head of the middle phalanx at the distal interphalangeal (DIP) joint (or for the proximal phalanx in the thumb), with the dorsal base positioned posterior to the volar surface where the flexor digitorum profundus inserts. Small but specific. Hand clinicians care about this ridge because the terminal extensor tendon inserts on the dorsal base of the distal phalanx, and even small avulsion fragments at this location change DIP joint mechanics. Mallet finger classically involves a dorsal avulsion fracture at the base, while intra-articular fractures can produce step-off at the DIP joint and later stiffness or arthrosis if reduction is imperfect. The fixed posterior perspective separates the dorsal insertional anatomy from the palmar (volar) flexor footprint, which helps when teaching why dorsal splinting positions and percutaneous pin trajectories must respect the extensor apparatus and the joint surface. Orthopedic and plastic surgery texts can pair this illustration with mallet injury classification, dorsal base fracture patterns, and DIP joint arthrodesis discussions. Anatomy and radiography courses can also use it to reinforce posterior versus volar surface terminology when correlating to lateral finger radiographs and oblique hand projections. Anatomical accuracy verified by SciePro's Medical Advisory Board.